[PATCH v7 00/28] Landlock audit support

[PATCH v7 00/28] Landlock audit support

[Mickaël Salaün]

Hi,

This patch series adds audit support to Landlock.

Logging denied requests is useful for different use cases:
- sysadmins: to look for users' issues,
- security experts: to detect attack attempts,
- power users: to understand denials,
- developers: to ease sandboxing support and get feedback from users.

Because of its unprivileged nature, Landlock can compose standalone
security policies (i.e. domains).  To make logs useful, they need to
contain the most relevant Landlock domain that denied an action, and the
reason of such denial.  This translates to the latest nested domain and
the related blockers: missing access rights or other kind of
restrictions.

# Main changes from previous version

A lot of new tests for domain layers, filesystem, and netwoking.  the
previous test race condition is fixed.  Test coverage is now 94%!

Some issues fixed thanks to the new tests, code simplification, a few
cosmetic changes, and an improved documentation.

This series is rebased on top of these fixes:
https://lore.kernel.org/r/20250318161443.279194-1-mic@digikod.net

# Design

Log records are created for any denied actions caused by a Landlock
policy, which means that a well-sandboxed applications should not log
anything except for unattended access requests that might be the result
of attacks or bugs.

However, sandbox tools creating restricted environments could lead to
abundant log entries because the sandboxed processes may not be aware of
the related restrictions.  To avoid log spam, the
landlock_restrict_self(2) syscall gets new flags to not log denials
related to this specific domain.  Except for well-understood exceptions,
these flags should not be set.  Indeed, applications sandboxing
themselves should only try to bypass their own sandbox if they are
compromised, which should ring a bell thanks to log events.

When an action is denied, the related Landlock domain ID is specified.
If this domain was not previously described in a log record, one is
created.  This record contains the domain ID, its creation time, and
informations about the process that enforced the restriction (at the
time of the call to landlock_restrict_self): PID, UID, executable path,
and name (comm).

This new approach also brings building blocks for an upcoming
unprivileged introspection interface.  The unique Landlock IDs will be
useful to tie audit log entries to running processes, and to get
properties of the related Landlock domains.  This will replace the
previously logged ruleset properties.

# Samples

Here are two examples of log events (see serial numbers):

$ LL_FS_RO=/ LL_FS_RW=/ LL_SCOPED=s LL_FORCE_LOG=1 ./sandboxer kill 1

  type=LANDLOCK_ACCESS msg=audit(1729738800.268:30): domain=1a6fdc66f blockers=scope.signal opid=1 ocomm="systemd"
  type=LANDLOCK_DOMAIN msg=audit(1729738800.268:30): domain=1a6fdc66f status=allocated mode=enforcing pid=286 uid=0 exe="/root/sandboxer" comm="sandboxer"
  type=SYSCALL msg=audit(1729738800.268:30): arch=c000003e syscall=62 success=no exit=-1 [..] ppid=272 pid=286 auid=0 uid=0 gid=0 [...] comm="kill" [...]
  type=PROCTITLE msg=audit(1729738800.268:30): proctitle=6B696C6C0031
  type=LANDLOCK_DOMAIN msg=audit(1729738800.324:31): domain=1a6fdc66f status=deallocated denials=1

$ LL_FS_RO=/ LL_FS_RW=/tmp LL_FORCE_LOG=1 ./sandboxer sh -c "echo > /etc/passwd"

  type=LANDLOCK_ACCESS msg=audit(1729738800.221:33): domain=1a6fdc679 blockers=fs.write_file path="/dev/tty" dev="devtmpfs" ino=9
  type=LANDLOCK_DOMAIN msg=audit(1729738800.221:33): domain=1a6fdc679 status=allocated mode=enforcing pid=289 uid=0 exe="/root/sandboxer" comm="sandboxer"
  type=SYSCALL msg=audit(1729738800.221:33): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
  type=PROCTITLE msg=audit(1729738800.221:33): proctitle=7368002D63006563686F203E202F6574632F706173737764
  type=LANDLOCK_ACCESS msg=audit(1729738800.221:34): domain=1a6fdc679 blockers=fs.write_file path="/etc/passwd" dev="vda2" ino=143821
  type=SYSCALL msg=audit(1729738800.221:34): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
  type=PROCTITLE msg=audit(1729738800.221:34): proctitle=7368002D63006563686F203E202F6574632F706173737764
  type=LANDLOCK_DOMAIN msg=audit(1729738800.261:35): domain=1a6fdc679 status=deallocated denials=2

# Previous versions

v6: https://lore.kernel.org/r/20250308184422.2159360-1-mic@digikod.net
v5: https://lore.kernel.org/r/20250131163059.1139617-1-mic@digikod.net
v4: https://lore.kernel.org/r/20250108154338.1129069-1-mic@digikod.net
v3: https://lore.kernel.org/r/20241122143353.59367-1-mic@digikod.net
v2: https://lore.kernel.org/r/20241022161009.982584-1-mic@digikod.net
v1: https://lore.kernel.org/r/20230921061641.273654-1-mic@digikod.net

Regards,

Mickaël Salaün (28):
  lsm: Add audit_log_lsm_data() helper
  landlock: Add unique ID generator
  landlock: Move domain hierarchy management
  landlock: Prepare to use credential instead of domain for filesystem
  landlock: Prepare to use credential instead of domain for network
  landlock: Prepare to use credential instead of domain for scope
  landlock: Prepare to use credential instead of domain for fowner
  landlock: Identify domain execution crossing
  landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials
  landlock: Add AUDIT_LANDLOCK_DOMAIN and log domain status
  landlock: Log mount-related denials
  landlock: Log file-related denials
  landlock: Factor out IOCTL hooks
  landlock: Log truncate and IOCTL denials
  landlock: Log TCP bind and connect denials
  landlock: Log scoped denials
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_*_EXEC_* flags
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
  samples/landlock: Enable users to log sandbox denials
  selftests/landlock: Add test for invalid ruleset file descriptor
  selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags
  selftests/landlock: Add tests for audit flags and domain IDs
  selftests/landlock: Test audit with restrict flags
  selftests/landlock: Add audit tests for ptrace
  selftests/landlock: Add audit tests for abstract UNIX socket scoping
  selftests/landlock: Add audit tests for filesystem
  selftests/landlock: Add audit tests for network
  landlock: Add audit documentation

 Documentation/admin-guide/LSM/index.rst       |   1 +
 Documentation/admin-guide/LSM/landlock.rst    | 158 +++++
 Documentation/security/landlock.rst           |  13 +-
 Documentation/userspace-api/landlock.rst      |  17 +
 MAINTAINERS                                   |   1 +
 include/linux/lsm_audit.h                     |   8 +
 include/uapi/linux/audit.h                    |   4 +-
 include/uapi/linux/landlock.h                 |  33 +
 samples/landlock/sandboxer.c                  |  37 +-
 security/landlock/.kunitconfig                |   2 +
 security/landlock/Makefile                    |   5 +
 security/landlock/access.h                    |  23 +
 security/landlock/audit.c                     | 523 +++++++++++++++
 security/landlock/audit.h                     |  76 +++
 security/landlock/cred.c                      |  26 +-
 security/landlock/cred.h                      |  92 ++-
 security/landlock/domain.c                    | 264 ++++++++
 security/landlock/domain.h                    | 174 +++++
 security/landlock/fs.c                        | 288 +++++++--
 security/landlock/fs.h                        |  37 +-
 security/landlock/id.c                        | 251 ++++++++
 security/landlock/id.h                        |  25 +
 security/landlock/limits.h                    |   7 +-
 security/landlock/net.c                       |  74 ++-
 security/landlock/ruleset.c                   |  30 +-
 security/landlock/ruleset.h                   |  48 +-
 security/landlock/setup.c                     |   2 +
 security/landlock/syscalls.c                  |  77 ++-
 security/landlock/task.c                      | 243 +++++--
 security/lsm_audit.c                          |  27 +-
 tools/testing/kunit/configs/all_tests.config  |   2 +
 tools/testing/selftests/landlock/.gitignore   |   1 +
 tools/testing/selftests/landlock/Makefile     |   6 +-
 tools/testing/selftests/landlock/audit.h      | 472 ++++++++++++++
 tools/testing/selftests/landlock/audit_test.c | 551 ++++++++++++++++
 tools/testing/selftests/landlock/base_test.c  |  84 ++-
 tools/testing/selftests/landlock/common.h     |  19 +
 tools/testing/selftests/landlock/config       |   1 +
 tools/testing/selftests/landlock/fs_test.c    | 594 ++++++++++++++++++
 tools/testing/selftests/landlock/net_test.c   | 132 ++++
 .../testing/selftests/landlock/ptrace_test.c  | 140 +++++
 .../landlock/scoped_abstract_unix_test.c      | 111 ++++
 .../selftests/landlock/wait-pipe-sandbox.c    | 131 ++++
 43 files changed, 4554 insertions(+), 256 deletions(-)
 create mode 100644 Documentation/admin-guide/LSM/landlock.rst
 create mode 100644 security/landlock/audit.c
 create mode 100644 security/landlock/audit.h
 create mode 100644 security/landlock/domain.c
 create mode 100644 security/landlock/domain.h
 create mode 100644 security/landlock/id.c
 create mode 100644 security/landlock/id.h
 create mode 100644 tools/testing/selftests/landlock/audit.h
 create mode 100644 tools/testing/selftests/landlock/audit_test.c
 create mode 100644 tools/testing/selftests/landlock/wait-pipe-sandbox.c


base-commit: 4f06e22607e6e138be661494964d7f2614ec7ae6
-- 
2.49.0

[PATCH v7 01/28] lsm: Add audit_log_lsm_data() helper

[Mickaël Salaün]

Extract code from dump_common_audit_data() into the audit_log_lsm_data()
helper. This helps reuse common LSM audit data while not abusing
AUDIT_AVC records because of the common_lsm_audit() helper.

Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: James Morris <jmorris@namei.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Depends-on: 7ccbe076d987 ("lsm: Only build lsm_audit.c if CONFIG_SECURITY and CONFIG_AUDIT are set")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v4:
- Add Depends-on tag.

Changes since v3:
- Rebase on top of the v6.13's get_task_comm() fix.
- Add Acked-by Paul.

Changes since v1:
- Fix commit message (spotted by Paul).
- Constify dump_common_audit_data()'s and audit_log_lsm_data()'s "a"
  argument.
- Fix build without CONFIG_NET: see previous patch.
---
 include/linux/lsm_audit.h |  8 ++++++++
 security/lsm_audit.c      | 27 ++++++++++++++++++---------
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
index e13d2f947b51..bddd694f7c4c 100644
--- a/include/linux/lsm_audit.h
+++ b/include/linux/lsm_audit.h
@@ -132,6 +132,9 @@ void common_lsm_audit(struct common_audit_data *a,
 	void (*pre_audit)(struct audit_buffer *, void *),
 	void (*post_audit)(struct audit_buffer *, void *));
 
+void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a);
+
 #else /* CONFIG_AUDIT */
 
 static inline void common_lsm_audit(struct common_audit_data *a,
@@ -140,6 +143,11 @@ static inline void common_lsm_audit(struct common_audit_data *a,
 {
 }
 
+static inline void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a)
+{
+}
+
 #endif /* CONFIG_AUDIT */
 
 #endif
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 52db886dbba8..a61c7ebdb6a7 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -189,16 +189,13 @@ static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 }
 
 /**
- * dump_common_audit_data - helper to dump common audit data
+ * audit_log_lsm_data - helper to log common LSM audit data
  * @ab : the audit buffer
  * @a : common audit data
- *
  */
-static void dump_common_audit_data(struct audit_buffer *ab,
-				   struct common_audit_data *a)
+void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a)
 {
-	char comm[sizeof(current->comm)];
-
 	/*
 	 * To keep stack sizes in check force programmers to notice if they
 	 * start making this union too large!  See struct lsm_network_audit
@@ -206,9 +203,6 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	 */
 	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 
-	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
-	audit_log_untrustedstring(ab, get_task_comm(comm, current));
-
 	switch (a->type) {
 	case LSM_AUDIT_DATA_NONE:
 		return;
@@ -431,6 +425,21 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	} /* switch (a->type) */
 }
 
+/**
+ * dump_common_audit_data - helper to dump common audit data
+ * @ab : the audit buffer
+ * @a : common audit data
+ */
+static void dump_common_audit_data(struct audit_buffer *ab,
+				   const struct common_audit_data *a)
+{
+	char comm[sizeof(current->comm)];
+
+	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
+	audit_log_untrustedstring(ab, get_task_comm(comm, current));
+	audit_log_lsm_data(ab, a);
+}
+
 /**
  * common_lsm_audit - generic LSM auditing function
  * @a:  auxiliary audit data
-- 
2.49.0

[PATCH v7 02/28] landlock: Add unique ID generator

[Mickaël Salaün]

Landlock IDs can be generated to uniquely identify Landlock objects.
For now, only Landlock domains get an ID at creation time.  These IDs
map to immutable domain hierarchies.

Landlock IDs have important properties:
- They are unique during the lifetime of the running system thanks to
  the 64-bit values: at worse, 2^60 - 2*2^32 useful IDs.
- They are always greater than 2^32 and must then be stored in 64-bit
  integer types.
- The initial ID (at boot time) is randomly picked between 2^32 and
  2^33, which limits collisions in logs across different boots.
- IDs are sequential, which enables users to order them.
- IDs may not be consecutive but increase with a random 2^4 step, which
  limits side channels.

Such IDs can be exposed to unprivileged processes, even if it is not the
case with this audit patch series.  The domain IDs will be useful for
user space to identify sandboxes and get their properties.

These Landlock IDs are more secure that other absolute kernel IDs such
as pipe's inodes which rely on a shared global counter.

For checkpoint/restore features (i.e. CRIU), we could easily implement a
privileged interface (e.g. sysfs) to set the next ID counter.

IDR/IDA are not used because we only need a bijection from Landlock
objects to Landlock IDs, and we must not recycle IDs.  This enables us
to identify all Landlock objects during the lifetime of the system (e.g.
in logs), but not to access an object from an ID nor know if an ID is
assigned.   Using a counter is simpler, it scales (i.e. avoids growing
memory footprint), and it does not require locking.  We'll use proper
file descriptors (with IDs used as inode numbers) to access Landlock
objects.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Clean up headers.

Changes since v5:
- Add KUnit error message, suggested by Günther.

Changes since v3:
- Rename landlock_get_id_range() helper to reflect the "range" of IDs.
- Add docstring for landlock_get_id_range().

Changes since v2:
- Extend commit message.
- Rename global_counter to next_id.
- Fix KUnit's test __init types, spotted by kernel test robot.

Changes since v1:
- New patch.
---
 security/landlock/.kunitconfig               |   2 +
 security/landlock/Makefile                   |   2 +
 security/landlock/id.c                       | 251 +++++++++++++++++++
 security/landlock/id.h                       |  25 ++
 security/landlock/setup.c                    |   2 +
 tools/testing/kunit/configs/all_tests.config |   2 +
 6 files changed, 284 insertions(+)
 create mode 100644 security/landlock/id.c
 create mode 100644 security/landlock/id.h

diff --git a/security/landlock/.kunitconfig b/security/landlock/.kunitconfig
index 03e119466604..f9423f01ac5b 100644
--- a/security/landlock/.kunitconfig
+++ b/security/landlock/.kunitconfig
@@ -1,4 +1,6 @@
+CONFIG_AUDIT=y
 CONFIG_KUNIT=y
+CONFIG_NET=y
 CONFIG_SECURITY=y
 CONFIG_SECURITY_LANDLOCK=y
 CONFIG_SECURITY_LANDLOCK_KUNIT_TEST=y
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index b4538b7cf7d2..e1777abbc413 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -4,3 +4,5 @@ landlock-y := setup.o syscalls.o object.o ruleset.o \
 	cred.o task.o fs.o
 
 landlock-$(CONFIG_INET) += net.o
+
+landlock-$(CONFIG_AUDIT) += id.o
diff --git a/security/landlock/id.c b/security/landlock/id.c
new file mode 100644
index 000000000000..11fab9259c15
--- /dev/null
+++ b/security/landlock/id.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock - Unique identification number generator
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#include <kunit/test.h>
+#include <linux/atomic.h>
+#include <linux/random.h>
+#include <linux/spinlock.h>
+
+#include "common.h"
+#include "id.h"
+
+#define COUNTER_PRE_INIT 0
+
+static atomic64_t next_id = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+static void __init init_id(atomic64_t *const counter, const u32 random_32bits)
+{
+	u64 init;
+
+	/*
+	 * Ensures sure 64-bit values are always used by user space (or may
+	 * fail with -EOVERFLOW), and makes this testable.
+	 */
+	init = 1ULL << 32;
+
+	/*
+	 * Makes a large (2^32) boot-time value to limit ID collision in logs
+	 * from different boots, and to limit info leak about the number of
+	 * initially (relative to the reader) created elements (e.g. domains).
+	 */
+	init += random_32bits;
+
+	/* Sets first or ignores.  This will be the first ID. */
+	atomic64_cmpxchg(counter, COUNTER_PRE_INIT, init);
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void __init test_init_min(struct kunit *const test)
+{
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, 0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), 1ULL + U32_MAX);
+}
+
+static void __init test_init_max(struct kunit *const test)
+{
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, ~0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), 1 + (2ULL * U32_MAX));
+}
+
+static void __init test_init_once(struct kunit *const test)
+{
+	const u64 first_init = 1ULL + U32_MAX;
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, 0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), first_init);
+
+	init_id(&counter, ~0);
+	KUNIT_EXPECT_EQ_MSG(
+		test, atomic64_read(&counter), first_init,
+		"Should still have the same value after the subsequent init_id()");
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+void __init landlock_init_id(void)
+{
+	return init_id(&next_id, get_random_u32());
+}
+
+/*
+ * It's not worth it to try to hide the monotonic counter because it can still
+ * be inferred (with N counter ranges), and if we are allowed to read the inode
+ * number we should also be allowed to read the time creation anyway, and it
+ * can be handy to store and sort domain IDs for user space.
+ *
+ * Returns the value of next_id and increment it to let some space for the next
+ * one.
+ */
+static u64 get_id_range(size_t number_of_ids, atomic64_t *const counter,
+			u8 random_4bits)
+{
+	u64 id, step;
+
+	/*
+	 * We should return at least 1 ID, and we may need a set of consecutive
+	 * ones (e.g. to generate a set of inodes).
+	 */
+	if (WARN_ON_ONCE(number_of_ids <= 0))
+		number_of_ids = 1;
+
+	/*
+	 * Blurs the next ID guess with 1/16 ratio.  We get 2^(64 - 4) -
+	 * (2 * 2^32), so a bit less than 2^60 available IDs, which should be
+	 * much more than enough considering the number of CPU cycles required
+	 * to get a new ID (e.g. a full landlock_restrict_self() call), and the
+	 * cost of draining all available IDs during the system's uptime.
+	 */
+	random_4bits = random_4bits % (1 << 4);
+	step = number_of_ids + random_4bits;
+
+	/* It is safe to cast a signed atomic to an unsigned value. */
+	id = atomic64_fetch_add(step, counter);
+
+	/* Warns if landlock_init_id() was not called. */
+	WARN_ON_ONCE(id == COUNTER_PRE_INIT);
+	return id;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_range1_rand0(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 0), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 1);
+}
+
+static void test_range1_rand1(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 1), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+static void test_range1_rand16(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 16), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 1);
+}
+
+static void test_range2_rand0(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 0), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+static void test_range2_rand1(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 1), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 3);
+}
+
+static void test_range2_rand2(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 2), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 4);
+}
+
+static void test_range2_rand16(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 16), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+/**
+ * landlock_get_id_range - Get a range of unique IDs
+ *
+ * @number_of_ids: Number of IDs to hold.  Must be greater than one.
+ *
+ * Returns: The first ID in the range.
+ */
+u64 landlock_get_id_range(size_t number_of_ids)
+{
+	return get_id_range(number_of_ids, &next_id, get_random_u8());
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static struct kunit_case __refdata test_cases[] = {
+	/* clang-format off */
+	KUNIT_CASE(test_init_min),
+	KUNIT_CASE(test_init_max),
+	KUNIT_CASE(test_init_once),
+	KUNIT_CASE(test_range1_rand0),
+	KUNIT_CASE(test_range1_rand1),
+	KUNIT_CASE(test_range1_rand16),
+	KUNIT_CASE(test_range2_rand0),
+	KUNIT_CASE(test_range2_rand1),
+	KUNIT_CASE(test_range2_rand2),
+	KUNIT_CASE(test_range2_rand16),
+	{}
+	/* clang-format on */
+};
+
+static struct kunit_suite test_suite = {
+	.name = "landlock_id",
+	.test_cases = test_cases,
+};
+
+kunit_test_init_section_suite(test_suite);
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
diff --git a/security/landlock/id.h b/security/landlock/id.h
new file mode 100644
index 000000000000..45dcfb9e9a8b
--- /dev/null
+++ b/security/landlock/id.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock - Unique identification number generator
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#ifndef _SECURITY_LANDLOCK_ID_H
+#define _SECURITY_LANDLOCK_ID_H
+
+#ifdef CONFIG_AUDIT
+
+void __init landlock_init_id(void);
+
+u64 landlock_get_id_range(size_t number_of_ids);
+
+#else /* CONFIG_AUDIT */
+
+static inline void __init landlock_init_id(void)
+{
+}
+
+#endif /* CONFIG_AUDIT */
+
+#endif /* _SECURITY_LANDLOCK_ID_H */
diff --git a/security/landlock/setup.c b/security/landlock/setup.c
index 0c85ea27e409..bd53c7a56ab9 100644
--- a/security/landlock/setup.c
+++ b/security/landlock/setup.c
@@ -15,6 +15,7 @@
 #include "cred.h"
 #include "errata.h"
 #include "fs.h"
+#include "id.h"
 #include "net.h"
 #include "setup.h"
 #include "task.h"
@@ -67,6 +68,7 @@ static int __init landlock_init(void)
 	landlock_add_task_hooks();
 	landlock_add_fs_hooks();
 	landlock_add_net_hooks();
+	landlock_init_id();
 	landlock_initialized = true;
 	pr_info("Up and running.\n");
 	return 0;
diff --git a/tools/testing/kunit/configs/all_tests.config b/tools/testing/kunit/configs/all_tests.config
index b0049be00c70..cdd9782f9646 100644
--- a/tools/testing/kunit/configs/all_tests.config
+++ b/tools/testing/kunit/configs/all_tests.config
@@ -41,6 +41,8 @@ CONFIG_DAMON_PADDR=y
 
 CONFIG_REGMAP_BUILD=y
 
+CONFIG_AUDIT=y
+
 CONFIG_SECURITY=y
 CONFIG_SECURITY_APPARMOR=y
 CONFIG_SECURITY_LANDLOCK=y
-- 
2.49.0

[PATCH v7 03/28] landlock: Move domain hierarchy management

[Mickaël Salaün]

Create a new domain.h file containing the struct landlock_hierarchy
definition and helpers.  This type will grow with audit support.  This
also prepares for a new domain type.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Clean up headers.

Changes since v4:
- Revert v3 changes because of the new audit rule patch removal.

Changes since v3:
- Export landlock_get_hierarchy() and landlock_put_hierarchy().
- Clean up Makefile entries.

Changes since v1:
- New patch.
---
 security/landlock/domain.h  | 48 +++++++++++++++++++++++++++++++++++++
 security/landlock/ruleset.c | 21 +++-------------
 security/landlock/ruleset.h | 17 +------------
 security/landlock/task.c    |  1 +
 4 files changed, 53 insertions(+), 34 deletions(-)
 create mode 100644 security/landlock/domain.h

diff --git a/security/landlock/domain.h b/security/landlock/domain.h
new file mode 100644
index 000000000000..d22712e5fb0f
--- /dev/null
+++ b/security/landlock/domain.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock - Domain management
+ *
+ * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ */
+
+#ifndef _SECURITY_LANDLOCK_DOMAIN_H
+#define _SECURITY_LANDLOCK_DOMAIN_H
+
+#include <linux/mm.h>
+#include <linux/refcount.h>
+
+/**
+ * struct landlock_hierarchy - Node in a domain hierarchy
+ */
+struct landlock_hierarchy {
+	/**
+	 * @parent: Pointer to the parent node, or NULL if it is a root
+	 * Landlock domain.
+	 */
+	struct landlock_hierarchy *parent;
+	/**
+	 * @usage: Number of potential children domains plus their parent
+	 * domain.
+	 */
+	refcount_t usage;
+};
+
+static inline void
+landlock_get_hierarchy(struct landlock_hierarchy *const hierarchy)
+{
+	if (hierarchy)
+		refcount_inc(&hierarchy->usage);
+}
+
+static inline void landlock_put_hierarchy(struct landlock_hierarchy *hierarchy)
+{
+	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
+		const struct landlock_hierarchy *const freeme = hierarchy;
+
+		hierarchy = hierarchy->parent;
+		kfree(freeme);
+	}
+}
+
+#endif /* _SECURITY_LANDLOCK_DOMAIN_H */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index bff4e40a3093..adb7f87828df 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -23,6 +23,7 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "domain.h"
 #include "limits.h"
 #include "object.h"
 #include "ruleset.h"
@@ -307,22 +308,6 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset,
 	return insert_rule(ruleset, id, &layers, ARRAY_SIZE(layers));
 }
 
-static void get_hierarchy(struct landlock_hierarchy *const hierarchy)
-{
-	if (hierarchy)
-		refcount_inc(&hierarchy->usage);
-}
-
-static void put_hierarchy(struct landlock_hierarchy *hierarchy)
-{
-	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
-		const struct landlock_hierarchy *const freeme = hierarchy;
-
-		hierarchy = hierarchy->parent;
-		kfree(freeme);
-	}
-}
-
 static int merge_tree(struct landlock_ruleset *const dst,
 		      struct landlock_ruleset *const src,
 		      const enum landlock_key_type key_type)
@@ -477,7 +462,7 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
 		err = -EINVAL;
 		goto out_unlock;
 	}
-	get_hierarchy(parent->hierarchy);
+	landlock_get_hierarchy(parent->hierarchy);
 	child->hierarchy->parent = parent->hierarchy;
 
 out_unlock:
@@ -501,7 +486,7 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
 		free_rule(freeme, LANDLOCK_KEY_NET_PORT);
 #endif /* IS_ENABLED(CONFIG_INET) */
 
-	put_hierarchy(ruleset->hierarchy);
+	landlock_put_hierarchy(ruleset->hierarchy);
 	kfree(ruleset);
 }
 
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 52f4f0af6ab0..bbb5996545d2 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -17,6 +17,7 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "domain.h"
 #include "limits.h"
 #include "object.h"
 
@@ -108,22 +109,6 @@ struct landlock_rule {
 	struct landlock_layer layers[] __counted_by(num_layers);
 };
 
-/**
- * struct landlock_hierarchy - Node in a ruleset hierarchy
- */
-struct landlock_hierarchy {
-	/**
-	 * @parent: Pointer to the parent node, or NULL if it is a root
-	 * Landlock domain.
-	 */
-	struct landlock_hierarchy *parent;
-	/**
-	 * @usage: Number of potential children domains plus their parent
-	 * domain.
-	 */
-	refcount_t usage;
-};
-
 /**
  * struct landlock_ruleset - Landlock ruleset
  *
diff --git a/security/landlock/task.c b/security/landlock/task.c
index 4578ce6e319d..e04646d80e78 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -19,6 +19,7 @@
 
 #include "common.h"
 #include "cred.h"
+#include "domain.h"
 #include "fs.h"
 #include "ruleset.h"
 #include "setup.h"
-- 
2.49.0

[PATCH v7 04/28] landlock: Prepare to use credential instead of domain for filesystem

[Mickaël Salaün]

This cosmetic change is needed for audit support, specifically to be
able to filter according to cross-execution boundaries.

Add landlock_get_applicable_subject(), mainly a copy of
landlock_get_applicable_domain(), which will fully replace it in a
following commit.

Optimize current_check_access_path() to only handle the access request.

Partially replace get_current_fs_domain() with explicit calls to
landlock_get_applicable_subject().  The remaining ones will follow with
more changes.

Remove explicit domain->num_layers check which is now part of the
landlock_get_applicable_subject() call.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Update headers.

Changes since v4:
- New patch to avoid duplicated computation of the layer level that
  denied an access.
---
 security/landlock/cred.h | 53 +++++++++++++++++++++++++++++++-
 security/landlock/fs.c   | 65 +++++++++++++++++++++++-----------------
 2 files changed, 90 insertions(+), 28 deletions(-)

diff --git a/security/landlock/cred.h b/security/landlock/cred.h
index bf755459838a..eb691130dd67 100644
--- a/security/landlock/cred.h
+++ b/security/landlock/cred.h
@@ -1,9 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Landlock LSM - Credential hooks
+ * Landlock - Credential hooks
  *
  * Copyright © 2019-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2019-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #ifndef _SECURITY_LANDLOCK_CRED_H
@@ -13,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/rcupdate.h>
 
+#include "access.h"
 #include "ruleset.h"
 #include "setup.h"
 
@@ -53,6 +55,55 @@ static inline bool landlocked(const struct task_struct *const task)
 	return has_dom;
 }
 
+/**
+ * landlock_get_applicable_subject - Return the subject's Landlock credential
+ *                                   if its enforced domain applies to (i.e.
+ *                                   handles) at least one of the access rights
+ *                                   specified in @masks
+ *
+ * @cred: credential
+ * @masks: access masks
+ * @handle_layer: returned youngest layer handling a subset of @masks.  Not set
+ *                if the function returns NULL.
+ *
+ * Returns: landlock_cred(@cred) if any access rights specified in @masks is
+ * handled, or NULL otherwise.
+ */
+static inline const struct landlock_cred_security *
+landlock_get_applicable_subject(const struct cred *const cred,
+				const struct access_masks masks,
+				size_t *const handle_layer)
+{
+	const union access_masks_all masks_all = {
+		.masks = masks,
+	};
+	const struct landlock_ruleset *domain;
+	ssize_t layer_level;
+
+	if (!cred)
+		return NULL;
+
+	domain = landlock_cred(cred)->domain;
+	if (!domain)
+		return NULL;
+
+	for (layer_level = domain->num_layers - 1; layer_level >= 0;
+	     layer_level--) {
+		union access_masks_all layer = {
+			.masks = domain->access_masks[layer_level],
+		};
+
+		if (layer.all & masks_all.all) {
+			if (handle_layer)
+				*handle_layer = layer_level;
+
+			return landlock_cred(cred);
+		}
+	}
+
+	return NULL;
+}
+
 __init void landlock_add_cred_hooks(void);
 
 #endif /* _SECURITY_LANDLOCK_CRED_H */
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 47c862fe14e4..fd858f989a3d 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -773,11 +773,14 @@ static bool is_access_to_paths_allowed(
 
 	if (!access_request_parent1 && !access_request_parent2)
 		return true;
-	if (WARN_ON_ONCE(!domain || !path))
+
+	if (WARN_ON_ONCE(!path))
 		return true;
+
 	if (is_nouser_or_private(path->dentry))
 		return true;
-	if (WARN_ON_ONCE(domain->num_layers < 1 || !layer_masks_parent1))
+
+	if (WARN_ON_ONCE(!layer_masks_parent1))
 		return false;
 
 	allowed_parent1 = is_layer_masks_allowed(layer_masks_parent1);
@@ -928,16 +931,21 @@ static bool is_access_to_paths_allowed(
 static int current_check_access_path(const struct path *const path,
 				     access_mask_t access_request)
 {
-	const struct landlock_ruleset *const dom = get_current_fs_domain();
+	const struct access_masks masks = {
+		.fs = access_request,
+	};
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), masks, NULL);
 	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
 
-	if (!dom)
+	if (!subject)
 		return 0;
 
-	access_request = landlock_init_layer_masks(
-		dom, access_request, &layer_masks, LANDLOCK_KEY_INODE);
-	if (is_access_to_paths_allowed(dom, path, access_request, &layer_masks,
-				       NULL, 0, NULL, NULL))
+	access_request = landlock_init_layer_masks(subject->domain,
+						   access_request, &layer_masks,
+						   LANDLOCK_KEY_INODE);
+	if (is_access_to_paths_allowed(subject->domain, path, access_request,
+				       &layer_masks, NULL, 0, NULL, NULL))
 		return 0;
 
 	return -EACCES;
@@ -1100,7 +1108,8 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 				    struct dentry *const new_dentry,
 				    const bool removable, const bool exchange)
 {
-	const struct landlock_ruleset *const dom = get_current_fs_domain();
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs, NULL);
 	bool allow_parent1, allow_parent2;
 	access_mask_t access_request_parent1, access_request_parent2;
 	struct path mnt_dir;
@@ -1108,10 +1117,9 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 	layer_mask_t layer_masks_parent1[LANDLOCK_NUM_ACCESS_FS] = {},
 		     layer_masks_parent2[LANDLOCK_NUM_ACCESS_FS] = {};
 
-	if (!dom)
+	if (!subject)
 		return 0;
-	if (WARN_ON_ONCE(dom->num_layers < 1))
-		return -EACCES;
+
 	if (unlikely(d_is_negative(old_dentry)))
 		return -ENOENT;
 	if (exchange) {
@@ -1136,10 +1144,11 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 		 * for same-directory referer (i.e. no reparenting).
 		 */
 		access_request_parent1 = landlock_init_layer_masks(
-			dom, access_request_parent1 | access_request_parent2,
+			subject->domain,
+			access_request_parent1 | access_request_parent2,
 			&layer_masks_parent1, LANDLOCK_KEY_INODE);
 		if (is_access_to_paths_allowed(
-			    dom, new_dir, access_request_parent1,
+			    subject->domain, new_dir, access_request_parent1,
 			    &layer_masks_parent1, NULL, 0, NULL, NULL))
 			return 0;
 		return -EACCES;
@@ -1162,10 +1171,12 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 						      old_dentry->d_parent;
 
 	/* new_dir->dentry is equal to new_dentry->d_parent */
-	allow_parent1 = collect_domain_accesses(dom, mnt_dir.dentry, old_parent,
+	allow_parent1 = collect_domain_accesses(subject->domain, mnt_dir.dentry,
+						old_parent,
 						&layer_masks_parent1);
-	allow_parent2 = collect_domain_accesses(
-		dom, mnt_dir.dentry, new_dir->dentry, &layer_masks_parent2);
+	allow_parent2 = collect_domain_accesses(subject->domain, mnt_dir.dentry,
+						new_dir->dentry,
+						&layer_masks_parent2);
 
 	if (allow_parent1 && allow_parent2)
 		return 0;
@@ -1177,9 +1188,9 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 	 * destination parent access rights.
 	 */
 	if (is_access_to_paths_allowed(
-		    dom, &mnt_dir, access_request_parent1, &layer_masks_parent1,
-		    old_dentry, access_request_parent2, &layer_masks_parent2,
-		    exchange ? new_dentry : NULL))
+		    subject->domain, &mnt_dir, access_request_parent1,
+		    &layer_masks_parent1, old_dentry, access_request_parent2,
+		    &layer_masks_parent2, exchange ? new_dentry : NULL))
 		return 0;
 
 	/*
@@ -1506,11 +1517,10 @@ static int hook_file_open(struct file *const file)
 	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
 	access_mask_t open_access_request, full_access_request, allowed_access,
 		optional_access;
-	const struct landlock_ruleset *const dom =
-		landlock_get_applicable_domain(
-			landlock_cred(file->f_cred)->domain, any_fs);
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(file->f_cred, any_fs, NULL);
 
-	if (!dom)
+	if (!subject)
 		return 0;
 
 	/*
@@ -1531,9 +1541,10 @@ static int hook_file_open(struct file *const file)
 	full_access_request = open_access_request | optional_access;
 
 	if (is_access_to_paths_allowed(
-		    dom, &file->f_path,
-		    landlock_init_layer_masks(dom, full_access_request,
-					      &layer_masks, LANDLOCK_KEY_INODE),
+		    subject->domain, &file->f_path,
+		    landlock_init_layer_masks(subject->domain,
+					      full_access_request, &layer_masks,
+					      LANDLOCK_KEY_INODE),
 		    &layer_masks, NULL, 0, NULL, NULL)) {
 		allowed_access = full_access_request;
 	} else {
-- 
2.49.0

[PATCH v7 05/28] landlock: Prepare to use credential instead of domain for network

[Mickaël Salaün]

This cosmetic change that is needed for audit support, specifically to
be able to filter according to cross-execution boundaries.

Optimize current_check_access_socket() to only handle the access
request.

Remove explicit domain->num_layers check which is now part of the
landlock_get_applicable_subject() call.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v4:
- New patch.
---
 security/landlock/net.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/security/landlock/net.c b/security/landlock/net.c
index 104b6c01fe50..6fb3e60bc5ff 100644
--- a/security/landlock/net.c
+++ b/security/landlock/net.c
@@ -39,10 +39,6 @@ int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
 	return err;
 }
 
-static const struct access_masks any_net = {
-	.net = ~0,
-};
-
 static int current_check_access_socket(struct socket *const sock,
 				       struct sockaddr *const address,
 				       const int addrlen,
@@ -54,14 +50,14 @@ static int current_check_access_socket(struct socket *const sock,
 	struct landlock_id id = {
 		.type = LANDLOCK_KEY_NET_PORT,
 	};
-	const struct landlock_ruleset *const dom =
-		landlock_get_applicable_domain(landlock_get_current_domain(),
-					       any_net);
+	const struct access_masks masks = {
+		.net = access_request,
+	};
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), masks, NULL);
 
-	if (!dom)
+	if (!subject)
 		return 0;
-	if (WARN_ON_ONCE(dom->num_layers < 1))
-		return -EACCES;
 
 	if (!sk_is_tcp(sock->sk))
 		return 0;
@@ -145,9 +141,10 @@ static int current_check_access_socket(struct socket *const sock,
 	id.key.data = (__force uintptr_t)port;
 	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
 
-	rule = landlock_find_rule(dom, id);
-	access_request = landlock_init_layer_masks(
-		dom, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT);
+	rule = landlock_find_rule(subject->domain, id);
+	access_request = landlock_init_layer_masks(subject->domain,
+						   access_request, &layer_masks,
+						   LANDLOCK_KEY_NET_PORT);
 	if (landlock_unmask_layers(rule, access_request, &layer_masks,
 				   ARRAY_SIZE(layer_masks)))
 		return 0;
-- 
2.49.0

[PATCH v7 06/28] landlock: Prepare to use credential instead of domain for scope

[Mickaël Salaün]

This cosmetic change that is needed for audit support, specifically to
be able to filter according to cross-execution boundaries.

Replace hardcoded LANDLOCK_SCOPE_SIGNAL with the signal_scope.scope
variable.

Use scoped guards for RCU read-side critical sections.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Rebase on the signal scoping fix.

Changes since v4:
- New patch.
---
 security/landlock/task.c | 49 +++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/security/landlock/task.c b/security/landlock/task.c
index e04646d80e78..a44b8e4a6ea6 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -7,6 +7,7 @@
  */
 
 #include <asm/current.h>
+#include <linux/cleanup.h>
 #include <linux/cred.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
@@ -214,15 +215,15 @@ static int hook_unix_stream_connect(struct sock *const sock,
 				    struct sock *const other,
 				    struct sock *const newsk)
 {
-	const struct landlock_ruleset *const dom =
-		landlock_get_applicable_domain(landlock_get_current_domain(),
-					       unix_scope);
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), unix_scope,
+						NULL);
 
 	/* Quick return for non-landlocked tasks. */
-	if (!dom)
+	if (!subject)
 		return 0;
 
-	if (is_abstract_socket(other) && sock_is_scoped(other, dom))
+	if (is_abstract_socket(other) && sock_is_scoped(other, subject->domain))
 		return -EPERM;
 
 	return 0;
@@ -231,11 +232,11 @@ static int hook_unix_stream_connect(struct sock *const sock,
 static int hook_unix_may_send(struct socket *const sock,
 			      struct socket *const other)
 {
-	const struct landlock_ruleset *const dom =
-		landlock_get_applicable_domain(landlock_get_current_domain(),
-					       unix_scope);
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), unix_scope,
+						NULL);
 
-	if (!dom)
+	if (!subject)
 		return 0;
 
 	/*
@@ -245,7 +246,8 @@ static int hook_unix_may_send(struct socket *const sock,
 	if (unix_peer(sock->sk) == other->sk)
 		return 0;
 
-	if (is_abstract_socket(other->sk) && sock_is_scoped(other->sk, dom))
+	if (is_abstract_socket(other->sk) &&
+	    sock_is_scoped(other->sk, subject->domain))
 		return -EPERM;
 
 	return 0;
@@ -257,15 +259,12 @@ static const struct access_masks signal_scope = {
 
 static int hook_task_kill(struct task_struct *const p,
 			  struct kernel_siginfo *const info, const int sig,
-			  const struct cred *const cred)
+			  const struct cred *cred)
 {
 	bool is_scoped;
-	const struct landlock_ruleset *dom;
+	const struct landlock_cred_security *subject;
 
-	if (cred) {
-		/* Dealing with USB IO. */
-		dom = landlock_cred(cred)->domain;
-	} else {
+	if (!cred) {
 		/*
 		 * Always allow sending signals between threads of the same process.
 		 * This is required for process credential changes by the Native POSIX
@@ -277,18 +276,22 @@ static int hook_task_kill(struct task_struct *const p,
 		if (same_thread_group(p, current))
 			return 0;
 
-		dom = landlock_get_current_domain();
+		/* Not dealing with USB IO. */
+		cred = current_cred();
 	}
-	dom = landlock_get_applicable_domain(dom, signal_scope);
+
+	subject = landlock_get_applicable_subject(cred, signal_scope, NULL);
 
 	/* Quick return for non-landlocked tasks. */
-	if (!dom)
+	if (!subject)
 		return 0;
 
-	rcu_read_lock();
-	is_scoped = domain_is_scoped(dom, landlock_get_task_domain(p),
-				     LANDLOCK_SCOPE_SIGNAL);
-	rcu_read_unlock();
+	scoped_guard(rcu)
+	{
+		is_scoped = domain_is_scoped(subject->domain,
+					     landlock_get_task_domain(p),
+					     signal_scope.scope);
+	}
 	if (is_scoped)
 		return -EPERM;
 
-- 
2.49.0

[PATCH v7 07/28] landlock: Prepare to use credential instead of domain for fowner

[Mickaël Salaün]

This cosmetic change is needed for audit support, specifically to be
able to filter according to cross-execution boundaries.

struct landlock_file_security's size stay the same for now but it will
increase with struct landlock_cred_security's size.

Only save Landlock domain in hook_file_set_fowner() if the current
domain has LANDLOCK_SCOPE_SIGNAL, which was previously done for each
hook_file_send_sigiotask() calls.  This should improve a bit
performance.

Replace hardcoded LANDLOCK_SCOPE_SIGNAL with the signal_scope.scope
variable.

Use scoped guards for RCU read-side critical sections.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Refactor and simplify hook_file_set_fowner().
- Rebase on the signal scope fix.

Changes since v5:
- Only call landlock_get_ruleset() when needed in
  hook_file_set_fowner().

Changes since v4:
- New patch.
---
 security/landlock/fs.c   | 20 ++++++++++++++------
 security/landlock/fs.h   | 12 +++++++-----
 security/landlock/task.c | 25 ++++++++++++++++---------
 3 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index fd858f989a3d..13d1cd78e8c8 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1644,9 +1644,9 @@ static int hook_file_ioctl_compat(struct file *file, unsigned int cmd,
 static void hook_file_set_fowner(struct file *file)
 {
 	struct fown_struct *fown = file_f_owner(file);
-	struct landlock_ruleset *new_dom = NULL;
 	struct landlock_ruleset *prev_dom;
 	struct task_struct *p;
+	struct landlock_cred_security fown_subject = {};
 
 	/*
 	 * Lock already held by __f_setown(), see commit 26f204380a3c ("fs: Fix
@@ -1660,12 +1660,20 @@ static void hook_file_set_fowner(struct file *file)
 	 */
 	p = pid_task(fown->pid, fown->pid_type);
 	if (!same_thread_group(p, current)) {
-		new_dom = landlock_get_current_domain();
-		landlock_get_ruleset(new_dom);
+		static const struct access_masks signal_scope = {
+			.scope = LANDLOCK_SCOPE_SIGNAL,
+		};
+		const struct landlock_cred_security *new_subject =
+			landlock_get_applicable_subject(current_cred(),
+							signal_scope, NULL);
+		if (new_subject) {
+			landlock_get_ruleset(new_subject->domain);
+			fown_subject = *new_subject;
+		}
 	}
 
-	prev_dom = landlock_file(file)->fown_domain;
-	landlock_file(file)->fown_domain = new_dom;
+	prev_dom = landlock_file(file)->fown_subject.domain;
+	landlock_file(file)->fown_subject = fown_subject;
 
 	/* Called in an RCU read-side critical section. */
 	landlock_put_ruleset_deferred(prev_dom);
@@ -1673,7 +1681,7 @@ static void hook_file_set_fowner(struct file *file)
 
 static void hook_file_free_security(struct file *file)
 {
-	landlock_put_ruleset_deferred(landlock_file(file)->fown_domain);
+	landlock_put_ruleset_deferred(landlock_file(file)->fown_subject.domain);
 }
 
 static struct security_hook_list landlock_hooks[] __ro_after_init = {
diff --git a/security/landlock/fs.h b/security/landlock/fs.h
index d445f411c26a..1449a90e92c7 100644
--- a/security/landlock/fs.h
+++ b/security/landlock/fs.h
@@ -14,6 +14,7 @@
 #include <linux/rcupdate.h>
 
 #include "access.h"
+#include "cred.h"
 #include "ruleset.h"
 #include "setup.h"
 
@@ -54,12 +55,13 @@ struct landlock_file_security {
 	 */
 	access_mask_t allowed_access;
 	/**
-	 * @fown_domain: Domain of the task that set the PID that may receive a
-	 * signal e.g., SIGURG when writing MSG_OOB to the related socket.
-	 * This pointer is protected by the related file->f_owner->lock, as for
-	 * fown_struct's members: pid, uid, and euid.
+	 * @fown_subject: Landlock credential of the task that set the PID that
+	 * may receive a signal e.g., SIGURG when writing MSG_OOB to the
+	 * related socket.  This pointer is protected by the related
+	 * file->f_owner->lock, as for fown_struct's members: pid, uid, and
+	 * euid.
 	 */
-	struct landlock_ruleset *fown_domain;
+	struct landlock_cred_security fown_subject;
 };
 
 /**
diff --git a/security/landlock/task.c b/security/landlock/task.c
index a44b8e4a6ea6..1ccd780e1354 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -301,22 +301,29 @@ static int hook_task_kill(struct task_struct *const p,
 static int hook_file_send_sigiotask(struct task_struct *tsk,
 				    struct fown_struct *fown, int signum)
 {
-	const struct landlock_ruleset *dom;
+	const struct landlock_cred_security *subject;
 	bool is_scoped = false;
 
 	/* Lock already held by send_sigio() and send_sigurg(). */
 	lockdep_assert_held(&fown->lock);
-	dom = landlock_get_applicable_domain(
-		landlock_file(fown->file)->fown_domain, signal_scope);
+	subject = &landlock_file(fown->file)->fown_subject;
 
-	/* Quick return for unowned socket. */
-	if (!dom)
+	/*
+	 * Quick return for unowned socket.
+	 *
+	 * subject->domain has already been filtered when saved by
+	 * hook_file_set_fowner(), so there is no need to call
+	 * landlock_get_applicable_subject() here.
+	 */
+	if (!subject->domain)
 		return 0;
 
-	rcu_read_lock();
-	is_scoped = domain_is_scoped(dom, landlock_get_task_domain(tsk),
-				     LANDLOCK_SCOPE_SIGNAL);
-	rcu_read_unlock();
+	scoped_guard(rcu)
+	{
+		is_scoped = domain_is_scoped(subject->domain,
+					     landlock_get_task_domain(tsk),
+					     signal_scope.scope);
+	}
 	if (is_scoped)
 		return -EPERM;
 
-- 
2.49.0

[PATCH v7 08/28] landlock: Identify domain execution crossing

[Mickaël Salaün]

Extend struct landlock_cred_security with a domain_exec bitmask to
identify which Landlock domain were created by the current task's bprm.
The whole bitmask is reset on each execve(2) call.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Add documentation and pack struct landlock_cred_security to minimize
  struct landlock_file_security.

Changes since v4:
- New patch.
---
 security/landlock/cred.c     | 26 ++++++++++++++++++++++----
 security/landlock/cred.h     | 32 +++++++++++++++++++++++++++++++-
 security/landlock/syscalls.c |  5 +++++
 3 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/security/landlock/cred.c b/security/landlock/cred.c
index db9fe7d906ba..a22756fe3b71 100644
--- a/security/landlock/cred.c
+++ b/security/landlock/cred.c
@@ -4,8 +4,10 @@
  *
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2025 Microsoft Corporation
  */
 
+#include <linux/binfmts.h>
 #include <linux/cred.h>
 #include <linux/lsm_hooks.h>
 
@@ -17,11 +19,12 @@
 static void hook_cred_transfer(struct cred *const new,
 			       const struct cred *const old)
 {
-	struct landlock_ruleset *const old_dom = landlock_cred(old)->domain;
+	const struct landlock_cred_security *const old_llcred =
+		landlock_cred(old);
 
-	if (old_dom) {
-		landlock_get_ruleset(old_dom);
-		landlock_cred(new)->domain = old_dom;
+	if (old_llcred->domain) {
+		landlock_get_ruleset(old_llcred->domain);
+		*landlock_cred(new) = *old_llcred;
 	}
 }
 
@@ -40,10 +43,25 @@ static void hook_cred_free(struct cred *const cred)
 		landlock_put_ruleset_deferred(dom);
 }
 
+#ifdef CONFIG_AUDIT
+
+static int hook_bprm_creds_for_exec(struct linux_binprm *const bprm)
+{
+	/* Resets for each execution. */
+	landlock_cred(bprm->cred)->domain_exec = 0;
+	return 0;
+}
+
+#endif /* CONFIG_AUDIT */
+
 static struct security_hook_list landlock_hooks[] __ro_after_init = {
 	LSM_HOOK_INIT(cred_prepare, hook_cred_prepare),
 	LSM_HOOK_INIT(cred_transfer, hook_cred_transfer),
 	LSM_HOOK_INIT(cred_free, hook_cred_free),
+
+#ifdef CONFIG_AUDIT
+	LSM_HOOK_INIT(bprm_creds_for_exec, hook_bprm_creds_for_exec),
+#endif /* CONFIG_AUDIT */
 };
 
 __init void landlock_add_cred_hooks(void)
diff --git a/security/landlock/cred.h b/security/landlock/cred.h
index eb691130dd67..3bf18551d7b8 100644
--- a/security/landlock/cred.h
+++ b/security/landlock/cred.h
@@ -10,17 +10,47 @@
 #ifndef _SECURITY_LANDLOCK_CRED_H
 #define _SECURITY_LANDLOCK_CRED_H
 
+#include <linux/container_of.h>
 #include <linux/cred.h>
 #include <linux/init.h>
 #include <linux/rcupdate.h>
 
 #include "access.h"
+#include "limits.h"
 #include "ruleset.h"
 #include "setup.h"
 
+/**
+ * struct landlock_cred_security - Credential security blob
+ *
+ * This structure is packed to minimize the size of struct
+ * landlock_file_security.  However, it is always aligned in the LSM cred blob,
+ * see lsm_set_blob_size().
+ */
 struct landlock_cred_security {
+	/**
+	 * @domain: Immutable ruleset enforced on a task.
+	 */
 	struct landlock_ruleset *domain;
-};
+
+#ifdef CONFIG_AUDIT
+	/**
+	 * @domain_exec: Bitmask identifying the domain layers that were enforced by
+	 * the current task's executed file (i.e. no new execve(2) since
+	 * landlock_restrict_self(2)).
+	 */
+	u16 domain_exec;
+#endif /* CONFIG_AUDIT */
+} __packed;
+
+#ifdef CONFIG_AUDIT
+
+/* Makes sure all layer executions can be stored. */
+static_assert(BITS_PER_TYPE(typeof_member(struct landlock_cred_security,
+					  domain_exec)) >=
+	      LANDLOCK_MAX_NUM_LAYERS);
+
+#endif /* CONFIG_AUDIT */
 
 static inline struct landlock_cred_security *
 landlock_cred(const struct cred *cred)
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index cf9e0483e542..b7b268f43a3b 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -510,5 +510,10 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	/* Replaces the old (prepared) domain. */
 	landlock_put_ruleset(new_llcred->domain);
 	new_llcred->domain = new_dom;
+
+#ifdef CONFIG_AUDIT
+	new_llcred->domain_exec |= 1 << (new_dom->num_layers - 1);
+#endif /* CONFIG_AUDIT */
+
 	return commit_creds(new_cred);
 }
-- 
2.49.0

[PATCH v7 09/28] landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials

[Mickaël Salaün]

Add a new AUDIT_LANDLOCK_ACCESS record type dedicated to an access
request denied by a Landlock domain.  AUDIT_LANDLOCK_ACCESS indicates
that something unexpected happened.

For now, only denied access are logged, which means that any
AUDIT_LANDLOCK_ACCESS record is always followed by a SYSCALL record with
"success=no".  However, log parsers should check this syscall property
because this is the only sign that a request was denied.  Indeed, we
could have "success=yes" if Landlock would support a "permissive" mode.
We could also add a new field to AUDIT_LANDLOCK_DOMAIN for this mode
(see following commit).

By default, the only logged access requests are those coming from the
same executed program that enforced the Landlock restriction on itself.
In other words, no audit record are created for a task after it called
execve(2).  This is required to avoid log spam because programs may only
be aware of their own restrictions, but not the inherited ones.

Following commits will allow to conditionally generate
AUDIT_LANDLOCK_ACCESS records according to dedicated
landlock_restrict_self(2)'s flags.

The AUDIT_LANDLOCK_ACCESS message contains:
- the "domain" ID restricting the action on an object,
- the "blockers" that are missing to allow the requested access,
- a set of fields identifying the related object (e.g. task identified
  with "opid" and "ocomm").

The blockers are implicit restrictions (e.g. ptrace), or explicit access
rights (e.g. filesystem), or explicit scopes (e.g. signal).  This field
contains a list of at least one element, each separated with a comma.

The initial blocker is "ptrace", which describe all implicit Landlock
restrictions related to ptrace (e.g. deny tracing of tasks outside a
sandbox).

Add audit support to ptrace_access_check and ptrace_traceme hooks.  For
the ptrace_access_check case, we log the current/parent domain and the
child task.  For the ptrace_traceme case, we log the parent domain and
the current/child task.  Indeed, the requester and the target are the
current task, but the action would be performed by the parent task.

Audit event sample:

  type=LANDLOCK_ACCESS msg=audit(1729738800.349:44): domain=195ba459b blockers=ptrace opid=1 ocomm="systemd"
  type=SYSCALL msg=audit(1729738800.349:44): arch=c000003e syscall=101 success=no [...] pid=300 auid=0

A following commit adds user documentation.

Add KUnit tests to check reading of domain ID relative to layer level.

The quick return for non-landlocked tasks is moved from task_ptrace() to
each LSM hooks.

It is not useful to inline the audit_enabled check because other
computation are performed by landlock_log_denial().

Use scoped guards for RCU read-side critical sections.

Cc: Günther Noack <gnoack@google.com>
Acked-by: Paul Moore <paul@paul-moore.com> (Audit)
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Improve consistency and clarity by renaming "node" variables to
  "hierarchy".
- Identify current (instead of the parent) as the task object in traceme
  requests.  It makes more sense to always log the target as the object.
- Improve is_valid_request() by checking the layer_plus_one number.
- Clean up includes and headers.
- Explain rationale for allocation flags.

Changes since v5:
- Add Acked-by Paul.
- Move request declarations in the landlock_log_denial() calls to
  not impact allowed requests with audit, and return as soon as possible
  when access is allowed.
- Remove the audit_context() check in landlock_log_denial() because the
  context may not already exist.  This issue was identified thanks to a
  new test.
- Remove unlikely().

Changes since v4:
- Rename AUDIT_LANDLOCK_DENY to AUDIT_LANDLOCK_ACCESS, requested by
  Paul.
- Make landlock_log_denial() get Landlock credential instead of Landlock
  domain to be able to filter on the domain_exe variable.
- Rebase on top of the migration from struct landlock_ruleset to struct
  landlock_cred_security.
- Rename landlock_init_current_hierarchy() to
  landlock_init_hierarchy_log().
- Rebase on top of the scoped guard patches.
- By default, do not log denials after an execution.
- Use scoped guards for RCU read-side critical sections.

Changes since v3:
- Extend commit message.

Changes since v2:
- Log domain IDs as hexadecimal number: this is a more compact notation
  (i.e. at least one less digit), it improves alignment in logs, and it
  makes most IDs start with 1 as leading digit (because of the 2^32
  minimal value).  Do not use the "0x" prefix that would add useless
  data to logs.
- Constify function arguments.
- Clean up Makefile entries.

Changes since v1:
- Move most audit code to this patch.
- Rebase on the TCP patch series.
- Don't log missing access right: simplify and make it generic for rule
  types.
- Don't log errno and then don't wrap the error with
  landlock_log_request(), as suggested by Jeff.
- Add a WARN_ON_ONCE() check to never dereference null pointers.
- Only log when audit is enabled.
- Don't log task's PID/TID with log_task() because it would be redundant
  with the SYSCALL record.
- Move the "op" in front and rename "domain" to "denying_domain" to make
  it more consistent with other entries.
- Don't update the request with the domain ID but add an helper to get
  it from the layer masks (and in a following commit with a struct
  file).
- Revamp get_domain_id_from_layer_masks() into
  get_level_from_layer_masks().
- For ptrace_traceme, log the parent domain instead of the current one.
- Add documentation.
- Rename AUDIT_LANDLOCK_DENIAL to AUDIT_LANDLOCK_DENY.
- Only log the domain ID and the target task.
- Log "blockers", which are either implicit restrictions (e.g. ptrace)
  or explicit access rights (e.g. filesystem), or scopes (e.g. signal).
- Don't log LSM hook names/operations.
- Pick an audit event ID folling the IPE ones.
- Add KUnit tests.
---
 include/uapi/linux/audit.h  |   3 +-
 security/landlock/Makefile  |   5 +-
 security/landlock/audit.c   | 151 ++++++++++++++++++++++++++++++++++++
 security/landlock/audit.h   |  52 +++++++++++++
 security/landlock/domain.c  |  28 +++++++
 security/landlock/domain.h  |  22 ++++++
 security/landlock/ruleset.c |   6 ++
 security/landlock/task.c    |  96 +++++++++++++++++------
 8 files changed, 338 insertions(+), 25 deletions(-)
 create mode 100644 security/landlock/audit.c
 create mode 100644 security/landlock/audit.h
 create mode 100644 security/landlock/domain.c

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index d9a069b4a775..5dd53f416a4a 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -33,7 +33,7 @@
  * 1100 - 1199 user space trusted application messages
  * 1200 - 1299 messages internal to the audit daemon
  * 1300 - 1399 audit event messages
- * 1400 - 1499 SE Linux use
+ * 1400 - 1499 access control messages
  * 1500 - 1599 kernel LSPP events
  * 1600 - 1699 kernel crypto events
  * 1700 - 1799 kernel anomaly records
@@ -146,6 +146,7 @@
 #define AUDIT_IPE_ACCESS	1420	/* IPE denial or grant */
 #define AUDIT_IPE_CONFIG_CHANGE	1421	/* IPE config change */
 #define AUDIT_IPE_POLICY_LOAD	1422	/* IPE policy load */
+#define AUDIT_LANDLOCK_ACCESS	1423	/* Landlock denial */
 
 #define AUDIT_FIRST_KERN_ANOM_MSG   1700
 #define AUDIT_LAST_KERN_ANOM_MSG    1799
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index e1777abbc413..3160c2bdac1d 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -5,4 +5,7 @@ landlock-y := setup.o syscalls.o object.o ruleset.o \
 
 landlock-$(CONFIG_INET) += net.o
 
-landlock-$(CONFIG_AUDIT) += id.o
+landlock-$(CONFIG_AUDIT) += \
+	id.o \
+	audit.o \
+	domain.o
diff --git a/security/landlock/audit.c b/security/landlock/audit.c
new file mode 100644
index 000000000000..b0752263012a
--- /dev/null
+++ b/security/landlock/audit.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock - Audit helpers
+ *
+ * Copyright © 2023-2025 Microsoft Corporation
+ */
+
+#include <kunit/test.h>
+#include <linux/audit.h>
+#include <linux/lsm_audit.h>
+
+#include "audit.h"
+#include "cred.h"
+#include "domain.h"
+#include "limits.h"
+#include "ruleset.h"
+
+static const char *get_blocker(const enum landlock_request_type type)
+{
+	switch (type) {
+	case LANDLOCK_REQUEST_PTRACE:
+		return "ptrace";
+	}
+
+	WARN_ON_ONCE(1);
+	return "unknown";
+}
+
+static void log_blockers(struct audit_buffer *const ab,
+			 const enum landlock_request_type type)
+{
+	audit_log_format(ab, "%s", get_blocker(type));
+}
+
+static struct landlock_hierarchy *
+get_hierarchy(const struct landlock_ruleset *const domain, const size_t layer)
+{
+	struct landlock_hierarchy *hierarchy = domain->hierarchy;
+	ssize_t i;
+
+	if (WARN_ON_ONCE(layer >= domain->num_layers))
+		return hierarchy;
+
+	for (i = domain->num_layers - 1; i > layer; i--) {
+		if (WARN_ON_ONCE(!hierarchy->parent))
+			break;
+
+		hierarchy = hierarchy->parent;
+	}
+
+	return hierarchy;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_get_hierarchy(struct kunit *const test)
+{
+	struct landlock_hierarchy dom0_hierarchy = {
+		.id = 10,
+	};
+	struct landlock_hierarchy dom1_hierarchy = {
+		.parent = &dom0_hierarchy,
+		.id = 20,
+	};
+	struct landlock_hierarchy dom2_hierarchy = {
+		.parent = &dom1_hierarchy,
+		.id = 30,
+	};
+	struct landlock_ruleset dom2 = {
+		.hierarchy = &dom2_hierarchy,
+		.num_layers = 3,
+	};
+
+	KUNIT_EXPECT_EQ(test, 10, get_hierarchy(&dom2, 0)->id);
+	KUNIT_EXPECT_EQ(test, 20, get_hierarchy(&dom2, 1)->id);
+	KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, 2)->id);
+	KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, -1)->id);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+static bool is_valid_request(const struct landlock_request *const request)
+{
+	if (WARN_ON_ONCE(request->layer_plus_one > LANDLOCK_MAX_NUM_LAYERS))
+		return false;
+
+	if (WARN_ON_ONCE(!request->layer_plus_one))
+		return false;
+
+	return true;
+}
+
+/**
+ * landlock_log_denial - Create audit records related to a denial
+ *
+ * @subject: The Landlock subject's credential denying an action.
+ * @request: Detail of the user space request.
+ */
+void landlock_log_denial(const struct landlock_cred_security *const subject,
+			 const struct landlock_request *const request)
+{
+	struct audit_buffer *ab;
+	struct landlock_hierarchy *youngest_denied;
+	size_t youngest_layer;
+
+	if (WARN_ON_ONCE(!subject || !subject->domain ||
+			 !subject->domain->hierarchy || !request))
+		return;
+
+	if (!is_valid_request(request))
+		return;
+
+	if (!audit_enabled)
+		return;
+
+	youngest_layer = request->layer_plus_one - 1;
+	youngest_denied = get_hierarchy(subject->domain, youngest_layer);
+
+	/* Ignores denials after an execution. */
+	if (!(subject->domain_exec & (1 << youngest_layer)))
+		return;
+
+	/* Uses consistent allocation flags wrt common_lsm_audit(). */
+	ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
+			     AUDIT_LANDLOCK_ACCESS);
+	if (!ab)
+		return;
+
+	audit_log_format(ab, "domain=%llx blockers=", youngest_denied->id);
+	log_blockers(ab, request->type);
+	audit_log_lsm_data(ab, &request->audit);
+	audit_log_end(ab);
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static struct kunit_case test_cases[] = {
+	/* clang-format off */
+	KUNIT_CASE(test_get_hierarchy),
+	{}
+	/* clang-format on */
+};
+
+static struct kunit_suite test_suite = {
+	.name = "landlock_audit",
+	.test_cases = test_cases,
+};
+
+kunit_test_suite(test_suite);
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
new file mode 100644
index 000000000000..3a6ec7c8e7c3
--- /dev/null
+++ b/security/landlock/audit.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock - Audit helpers
+ *
+ * Copyright © 2023-2025 Microsoft Corporation
+ */
+
+#ifndef _SECURITY_LANDLOCK_AUDIT_H
+#define _SECURITY_LANDLOCK_AUDIT_H
+
+#include <linux/audit.h>
+#include <linux/lsm_audit.h>
+
+#include "cred.h"
+
+enum landlock_request_type {
+	LANDLOCK_REQUEST_PTRACE = 1,
+};
+
+/*
+ * We should be careful to only use a variable of this type for
+ * landlock_log_denial().  This way, the compiler can remove it entirely if
+ * CONFIG_AUDIT is not set.
+ */
+struct landlock_request {
+	/* Mandatory fields. */
+	enum landlock_request_type type;
+	struct common_audit_data audit;
+
+	/**
+	 * layer_plus_one: First layer level that denies the request + 1.  The
+	 * extra one is useful to detect uninitialized field.
+	 */
+	size_t layer_plus_one;
+};
+
+#ifdef CONFIG_AUDIT
+
+void landlock_log_denial(const struct landlock_cred_security *const subject,
+			 const struct landlock_request *const request);
+
+#else /* CONFIG_AUDIT */
+
+static inline void
+landlock_log_denial(const struct landlock_cred_security *const subject,
+		    const struct landlock_request *const request)
+{
+}
+
+#endif /* CONFIG_AUDIT */
+
+#endif /* _SECURITY_LANDLOCK_AUDIT_H */
diff --git a/security/landlock/domain.c b/security/landlock/domain.c
new file mode 100644
index 000000000000..e6367933303c
--- /dev/null
+++ b/security/landlock/domain.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock - Domain management
+ *
+ * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#include "domain.h"
+#include "id.h"
+
+#ifdef CONFIG_AUDIT
+
+/**
+ * landlock_init_hierarchy_log - Partially initialize landlock_hierarchy
+ *
+ * @hierarchy: The hierarchy to initialize.
+ *
+ * @hierarchy->parent and @hierarchy->usage should already be set.
+ */
+int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
+{
+	hierarchy->id = landlock_get_id_range(1);
+	return 0;
+}
+
+#endif /* CONFIG_AUDIT */
diff --git a/security/landlock/domain.h b/security/landlock/domain.h
index d22712e5fb0f..f8df7103bd3d 100644
--- a/security/landlock/domain.h
+++ b/security/landlock/domain.h
@@ -4,6 +4,7 @@
  *
  * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2024-2025 Microsoft Corporation
  */
 
 #ifndef _SECURITY_LANDLOCK_DOMAIN_H
@@ -26,8 +27,29 @@ struct landlock_hierarchy {
 	 * domain.
 	 */
 	refcount_t usage;
+
+#ifdef CONFIG_AUDIT
+	/**
+	 * @id: Landlock domain ID, sets once at domain creation time.
+	 */
+	u64 id;
+#endif /* CONFIG_AUDIT */
 };
 
+#ifdef CONFIG_AUDIT
+
+int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy);
+
+#else /* CONFIG_AUDIT */
+
+static inline int
+landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
+{
+	return 0;
+}
+
+#endif /* CONFIG_AUDIT */
+
 static inline void
 landlock_get_hierarchy(struct landlock_hierarchy *const hierarchy)
 {
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index adb7f87828df..f273a40e9780 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -23,6 +23,7 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "audit.h"
 #include "domain.h"
 #include "limits.h"
 #include "object.h"
@@ -505,6 +506,7 @@ static void free_ruleset_work(struct work_struct *const work)
 	free_ruleset(ruleset);
 }
 
+/* Only called by hook_cred_free(). */
 void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset)
 {
 	if (ruleset && refcount_dec_and_test(&ruleset->usage)) {
@@ -564,6 +566,10 @@ landlock_merge_ruleset(struct landlock_ruleset *const parent,
 	if (err)
 		return ERR_PTR(err);
 
+	err = landlock_init_hierarchy_log(new_dom->hierarchy);
+	if (err)
+		return ERR_PTR(err);
+
 	return no_free_ptr(new_dom);
 }
 
diff --git a/security/landlock/task.c b/security/landlock/task.c
index 1ccd780e1354..60e2953d2c71 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -11,6 +11,7 @@
 #include <linux/cred.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
+#include <linux/lsm_audit.h>
 #include <linux/lsm_hooks.h>
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
@@ -18,6 +19,7 @@
 #include <net/af_unix.h>
 #include <net/sock.h>
 
+#include "audit.h"
 #include "common.h"
 #include "cred.h"
 #include "domain.h"
@@ -40,41 +42,29 @@ static bool domain_scope_le(const struct landlock_ruleset *const parent,
 {
 	const struct landlock_hierarchy *walker;
 
+	/* Quick return for non-landlocked tasks. */
 	if (!parent)
 		return true;
+
 	if (!child)
 		return false;
+
 	for (walker = child->hierarchy; walker; walker = walker->parent) {
 		if (walker == parent->hierarchy)
 			/* @parent is in the scoped hierarchy of @child. */
 			return true;
 	}
+
 	/* There is no relationship between @parent and @child. */
 	return false;
 }
 
-static bool task_is_scoped(const struct task_struct *const parent,
-			   const struct task_struct *const child)
-{
-	bool is_scoped;
-	const struct landlock_ruleset *dom_parent, *dom_child;
-
-	rcu_read_lock();
-	dom_parent = landlock_get_task_domain(parent);
-	dom_child = landlock_get_task_domain(child);
-	is_scoped = domain_scope_le(dom_parent, dom_child);
-	rcu_read_unlock();
-	return is_scoped;
-}
-
-static int task_ptrace(const struct task_struct *const parent,
-		       const struct task_struct *const child)
+static int domain_ptrace(const struct landlock_ruleset *const parent,
+			 const struct landlock_ruleset *const child)
 {
-	/* Quick return for non-landlocked tasks. */
-	if (!landlocked(parent))
-		return 0;
-	if (task_is_scoped(parent, child))
+	if (domain_scope_le(parent, child))
 		return 0;
+
 	return -EPERM;
 }
 
@@ -94,7 +84,39 @@ static int task_ptrace(const struct task_struct *const parent,
 static int hook_ptrace_access_check(struct task_struct *const child,
 				    const unsigned int mode)
 {
-	return task_ptrace(current, child);
+	const struct landlock_cred_security *parent_subject;
+	const struct landlock_ruleset *child_dom;
+	int err;
+
+	/* Quick return for non-landlocked tasks. */
+	parent_subject = landlock_cred(current_cred());
+	if (!parent_subject)
+		return 0;
+
+	scoped_guard(rcu)
+	{
+		child_dom = landlock_get_task_domain(child);
+		err = domain_ptrace(parent_subject->domain, child_dom);
+	}
+
+	if (!err)
+		return 0;
+
+	/*
+	 * For the ptrace_access_check case, we log the current/parent domain
+	 * and the child task.
+	 */
+	if (!(mode & PTRACE_MODE_NOAUDIT))
+		landlock_log_denial(parent_subject, &(struct landlock_request) {
+			.type = LANDLOCK_REQUEST_PTRACE,
+			.audit = {
+				.type = LSM_AUDIT_DATA_TASK,
+				.u.tsk = child,
+			},
+			.layer_plus_one = parent_subject->domain->num_layers,
+		});
+
+	return err;
 }
 
 /**
@@ -111,7 +133,35 @@ static int hook_ptrace_access_check(struct task_struct *const child,
  */
 static int hook_ptrace_traceme(struct task_struct *const parent)
 {
-	return task_ptrace(parent, current);
+	const struct landlock_cred_security *parent_subject;
+	const struct landlock_ruleset *child_dom;
+	int err;
+
+	child_dom = landlock_get_current_domain();
+
+	guard(rcu)();
+	parent_subject = landlock_cred(__task_cred(parent));
+	err = domain_ptrace(parent_subject->domain, child_dom);
+
+	if (!err)
+		return 0;
+
+	/*
+	 * For the ptrace_traceme case, we log the domain which is the cause of
+	 * the denial, which means the parent domain instead of the current
+	 * domain.  This may look unusual because the ptrace_traceme action is a
+	 * request to be traced, but the semantic is consistent with
+	 * hook_ptrace_access_check().
+	 */
+	landlock_log_denial(parent_subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_PTRACE,
+		.audit = {
+			.type = LSM_AUDIT_DATA_TASK,
+			.u.tsk = current,
+		},
+		.layer_plus_one = parent_subject->domain->num_layers,
+	});
+	return err;
 }
 
 /**
@@ -130,7 +180,7 @@ static bool domain_is_scoped(const struct landlock_ruleset *const client,
 			     access_mask_t scope)
 {
 	int client_layer, server_layer;
-	struct landlock_hierarchy *client_walker, *server_walker;
+	const struct landlock_hierarchy *client_walker, *server_walker;
 
 	/* Quick return if client has no domain */
 	if (WARN_ON_ONCE(!client))
-- 
2.49.0

[PATCH v7 10/28] landlock: Add AUDIT_LANDLOCK_DOMAIN and log domain status

[Mickaël Salaün]

Asynchronously log domain information when it first denies an access.
This minimize the amount of generated logs, which makes it possible to
always log denials for the current execution since they should not
happen.  These records are identified with the new AUDIT_LANDLOCK_DOMAIN
type.

The AUDIT_LANDLOCK_DOMAIN message contains:
- the "domain" ID which is described;
- the "status" which can either be "allocated" or "deallocated";
- the "mode" which is for now only "enforcing";
- for the "allocated" status, a minimal set of properties to easily
  identify the task that loaded the domain's policy with
  landlock_restrict_self(2): "pid", "uid", executable path ("exe"), and
  command line ("comm");
- for the "deallocated" state, the number of "denials" accounted to this
  domain, which is at least 1.

This requires each domain to save these task properties at creation
time in the new struct landlock_details.  A reference to the PID is kept
for the lifetime of the domain to avoid race conditions when
investigating the related task.  The executable path is resolved and
stored to not keep a reference to the filesystem and block related
actions.  All these metadata are stored for the lifetime of the related
domain and should then be minimal.  The required memory is not accounted
to the task calling landlock_restrict_self(2) contrary to most other
Landlock allocations (see related comment).

The AUDIT_LANDLOCK_DOMAIN record follows the first AUDIT_LANDLOCK_ACCESS
record for the same domain, which is always followed by AUDIT_SYSCALL
and AUDIT_PROCTITLE.  This is in line with the audit logic to first
record the cause of an event, and then add context with other types of
record.

Audit event sample for a first denial:

  type=LANDLOCK_ACCESS msg=audit(1732186800.349:44): domain=195ba459b blockers=ptrace opid=1 ocomm="systemd"
  type=LANDLOCK_DOMAIN msg=audit(1732186800.349:44): domain=195ba459b status=allocated mode=enforcing pid=300 uid=0 exe="/root/sandboxer" comm="sandboxer"
  type=SYSCALL msg=audit(1732186800.349:44): arch=c000003e syscall=101 success=no [...] pid=300 auid=0

Audit event sample for a following denial:

  type=LANDLOCK_ACCESS msg=audit(1732186800.372:45): domain=195ba459b blockers=ptrace opid=1 ocomm="systemd"
  type=SYSCALL msg=audit(1732186800.372:45): arch=c000003e syscall=101 success=no [...] pid=300 auid=0

Log domain deletion with the "deallocated" state when a domain was
previously logged.  This makes it possible for log parsers to free
potential resources when a domain ID will never show again.

The number of denied access requests is useful to easily check how many
access requests a domain blocked and potentially if some of them are
missing in logs because of audit rate limiting, audit rules, or Landlock
log configuration flags (see following commit).

Audit event sample for a deletion of a domain that denied something:

  type=LANDLOCK_DOMAIN msg=audit(1732186800.393:46): domain=195ba459b status=deallocated denials=2

Cc: Günther Noack <gnoack@google.com>
Acked-by: Paul Moore <paul@paul-moore.com> (Audit)
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Improve consistency and clarity by renaming log_node() to log_domain()
  and "node" variables to "hierarchy".
- Fix unsigned integer check, reported by Dan Carpenter:
  https://lore.kernel.org/r/2425110b-b5ca-4b33-bf75-e6fca0b0de63@stanley.mountain
- Fix inconsistent memory allocation flags and explain rationale,
  spotted by Paul.
- Fix domain deallocation logs by moving the call from cred put to
  hierarchy put.  Update landlock_log_drop_domain() accordingly.  This
  required to not include domain.h in ruleset.h anymore to avoid
  recursive include.
- Free hierarchy's details when putting a hierarchy.
- Save UID instead of keeping a reference to the current cred, which is
  not useful for now.
- Clean up includes.

Changes since v5:
- Add Acked-by Paul.
- Improve comment.
- Cosmetic code move in landlock_log_denial() for consistency, and to
  get a cleaner diff regarding the non-changing audit_enabled check.
- Remove unlikely().

Changes since v4:
- Rename AUDIT_LANDLOCK_DOM_{INFO,DROP} to AUDIT_LANDLOCK_DOMAIN and add
  a "status" field, as requested by Paul.
- Add a harcoded "mode=enforcing" to leave room for a potential future
  permissive mode, as suggested by Paul.
- Remove the "creation" timestamp, as suggested by Paul.
- Move LANDLOCK_PATH_MAX_SIZE to domain.h, check the size of the
  greatest landlock_details at build time, and improve comments.
- Improve audit check in landlock_log_drop_domain().
- Add missing headers.
- Fix typo in comment.
- Rebase on top of the landlock_log_denial() and subject type changes.

Changes since v3:
- Log number of denied access requests with AUDIT_LANDLOCK_DOM_DROP
  records, suggested by Tyler.
- Do not store a struct path pointer but the resolved string instead.
  This enables us to not block unmount of the initially restricted task
  executable's mount point.  See the new get_current_info() and
  get_current_exe().  A following patch add tests for this case.
- Create and allocate a new struct landlock_details for initially
  restricted task's information.
- Remove audit_get_ctime() call, as requested by Paul.  We now always
  have a standalone timestamp per Landlock domain creations.
- Fix docstring.

Changes since v2:
- Fix docstring.
- Fix log_status check in log_hierarchy() to also log
  LANDLOCK_LOG_DISABLED.
- Add audit's creation time to domain's properties.
- Use hexadecimal notation for domain IDs.
- Remove domain's parent records: parent domains are not really useful
  in the logs.  They will be available with the upcoming introspection
  feature though.
- Extend commit message with audit's timestamp explanation.

Changes since v1:
- Add a ruleset's version for atomic logs.
- Rebased on the TCP patch series.
- Rename operation using "_" instead of "-".
- Rename AUDIT_LANDLOCK to AUDIT_LANDLOCK_RULESET.
- Only log when audit is enabled, but always set domain IDs.
- Don't log task's PID/TID with log_task() because it would be redundant
  with the SYSCALL record.
- Remove race condition when logging ruleset creation and logging
  ruleset modification while the related file descriptor was already
  registered but the ruleset creation not logged yet.
- Fix domain drop logs.
- Move the domain drop record from the previous patch into this one.
- Do not log domain creation but log first domain use instead.
- Save task's properties that sandbox themselves.
---
 include/uapi/linux/audit.h  |   1 +
 security/landlock/audit.c   |  90 ++++++++++++++++++++++++++++++--
 security/landlock/audit.h   |   7 +++
 security/landlock/domain.c  | 101 ++++++++++++++++++++++++++++++++++++
 security/landlock/domain.h  |  86 ++++++++++++++++++++++++++++++
 security/landlock/ruleset.c |   3 ++
 security/landlock/ruleset.h |   3 +-
 7 files changed, 287 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 5dd53f416a4a..9a4ecc9f6dc5 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -147,6 +147,7 @@
 #define AUDIT_IPE_CONFIG_CHANGE	1421	/* IPE config change */
 #define AUDIT_IPE_POLICY_LOAD	1422	/* IPE policy load */
 #define AUDIT_LANDLOCK_ACCESS	1423	/* Landlock denial */
+#define AUDIT_LANDLOCK_DOMAIN	1424	/* Landlock domain status */
 
 #define AUDIT_FIRST_KERN_ANOM_MSG   1700
 #define AUDIT_LAST_KERN_ANOM_MSG    1799
diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index b0752263012a..a0e6041a1e21 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -8,6 +8,7 @@
 #include <kunit/test.h>
 #include <linux/audit.h>
 #include <linux/lsm_audit.h>
+#include <linux/pid.h>
 
 #include "audit.h"
 #include "cred.h"
@@ -32,6 +33,38 @@ static void log_blockers(struct audit_buffer *const ab,
 	audit_log_format(ab, "%s", get_blocker(type));
 }
 
+static void log_domain(struct landlock_hierarchy *const hierarchy)
+{
+	struct audit_buffer *ab;
+
+	/* Ignores already logged domains.  */
+	if (READ_ONCE(hierarchy->log_status) == LANDLOCK_LOG_RECORDED)
+		return;
+
+	/* Uses consistent allocation flags wrt common_lsm_audit(). */
+	ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
+			     AUDIT_LANDLOCK_DOMAIN);
+	if (!ab)
+		return;
+
+	WARN_ON_ONCE(hierarchy->id == 0);
+	audit_log_format(
+		ab,
+		"domain=%llx status=allocated mode=enforcing pid=%d uid=%u exe=",
+		hierarchy->id, pid_nr(hierarchy->details->pid),
+		hierarchy->details->uid);
+	audit_log_untrustedstring(ab, hierarchy->details->exe_path);
+	audit_log_format(ab, " comm=");
+	audit_log_untrustedstring(ab, hierarchy->details->comm);
+	audit_log_end(ab);
+
+	/*
+	 * There may be race condition leading to logging of the same domain
+	 * several times but that is OK.
+	 */
+	WRITE_ONCE(hierarchy->log_status, LANDLOCK_LOG_RECORDED);
+}
+
 static struct landlock_hierarchy *
 get_hierarchy(const struct landlock_ruleset *const domain, const size_t layer)
 {
@@ -110,12 +143,20 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 	if (!is_valid_request(request))
 		return;
 
-	if (!audit_enabled)
-		return;
-
 	youngest_layer = request->layer_plus_one - 1;
 	youngest_denied = get_hierarchy(subject->domain, youngest_layer);
 
+	/*
+	 * Consistently keeps track of the number of denied access requests
+	 * even if audit is currently disabled, or if audit rules currently
+	 * exclude this record type, or if landlock_restrict_self(2)'s flags
+	 * quiet logs.
+	 */
+	atomic64_inc(&youngest_denied->num_denials);
+
+	if (!audit_enabled)
+		return;
+
 	/* Ignores denials after an execution. */
 	if (!(subject->domain_exec & (1 << youngest_layer)))
 		return;
@@ -130,6 +171,49 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 	log_blockers(ab, request->type);
 	audit_log_lsm_data(ab, &request->audit);
 	audit_log_end(ab);
+
+	/* Logs this domain the first time it shows in log. */
+	log_domain(youngest_denied);
+}
+
+/**
+ * landlock_log_drop_domain - Create an audit record on domain deallocation
+ *
+ * @hierarchy: The domain's hierarchy being deallocated.
+ *
+ * Only domains which previously appeared in the audit logs are logged again.
+ * This is useful to know when a domain will never show again in the audit log.
+ *
+ * This record is not directly tied to a syscall entry.
+ *
+ * Called by the cred_free() hook, in an uninterruptible context.
+ */
+void landlock_log_drop_domain(const struct landlock_hierarchy *const hierarchy)
+{
+	struct audit_buffer *ab;
+
+	if (WARN_ON_ONCE(!hierarchy))
+		return;
+
+	if (!audit_enabled)
+		return;
+
+	/* Ignores domains that were not logged.  */
+	if (READ_ONCE(hierarchy->log_status) != LANDLOCK_LOG_RECORDED)
+		return;
+
+	/*
+	 * If logging of domain allocation succeeded, warns about failure to log
+	 * domain deallocation to highlight unbalanced domain lifetime logs.
+	 */
+	ab = audit_log_start(audit_context(), GFP_ATOMIC,
+			     AUDIT_LANDLOCK_DOMAIN);
+	if (!ab)
+		return;
+
+	audit_log_format(ab, "domain=%llx status=deallocated denials=%llu",
+			 hierarchy->id, atomic64_read(&hierarchy->num_denials));
+	audit_log_end(ab);
 }
 
 #ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 3a6ec7c8e7c3..40ff230316c4 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -36,11 +36,18 @@ struct landlock_request {
 
 #ifdef CONFIG_AUDIT
 
+void landlock_log_drop_domain(const struct landlock_hierarchy *const hierarchy);
+
 void landlock_log_denial(const struct landlock_cred_security *const subject,
 			 const struct landlock_request *const request);
 
 #else /* CONFIG_AUDIT */
 
+static inline void
+landlock_log_drop_domain(const struct landlock_hierarchy *const hierarchy)
+{
+}
+
 static inline void
 landlock_log_denial(const struct landlock_cred_security *const subject,
 		    const struct landlock_request *const request)
diff --git a/security/landlock/domain.c b/security/landlock/domain.c
index e6367933303c..3c1715e4b1c9 100644
--- a/security/landlock/domain.c
+++ b/security/landlock/domain.c
@@ -7,21 +7,122 @@
  * Copyright © 2024-2025 Microsoft Corporation
  */
 
+#include <linux/cred.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/path.h>
+#include <linux/pid.h>
+#include <linux/sched.h>
+#include <linux/uidgid.h>
+
 #include "domain.h"
 #include "id.h"
 
 #ifdef CONFIG_AUDIT
 
+/**
+ * get_current_exe - Get the current's executable path, if any
+ *
+ * @exe_str: Returned pointer to a path string with a lifetime tied to the
+ *           returned buffer, if any.
+ * @exe_size: Returned size of @exe_str (including the trailing null
+ *            character), if any.
+ *
+ * Returns: A pointer to an allocated buffer where @exe_str point to, %NULL if
+ * there is no executable path, or an error otherwise.
+ */
+static const void *get_current_exe(const char **const exe_str,
+				   size_t *const exe_size)
+{
+	const size_t buffer_size = LANDLOCK_PATH_MAX_SIZE;
+	struct mm_struct *mm = current->mm;
+	struct file *file __free(fput) = NULL;
+	char *buffer __free(kfree) = NULL;
+	const char *exe;
+	ssize_t size;
+
+	if (!mm)
+		return NULL;
+
+	file = get_mm_exe_file(mm);
+	if (!file)
+		return NULL;
+
+	buffer = kmalloc(buffer_size, GFP_KERNEL);
+	if (!buffer)
+		return ERR_PTR(-ENOMEM);
+
+	exe = d_path(&file->f_path, buffer, buffer_size);
+	if (WARN_ON_ONCE(IS_ERR(exe)))
+		/* Should never happen according to LANDLOCK_PATH_MAX_SIZE. */
+		return ERR_CAST(exe);
+
+	size = buffer + buffer_size - exe;
+	if (WARN_ON_ONCE(size <= 0))
+		return ERR_PTR(-ENAMETOOLONG);
+
+	*exe_size = size;
+	*exe_str = exe;
+	return no_free_ptr(buffer);
+}
+
+/*
+ * Returns: A newly allocated object describing a domain, or an error
+ * otherwise.
+ */
+static struct landlock_details *get_current_details(void)
+{
+	/* Cf. audit_log_d_path_exe() */
+	static const char null_path[] = "(null)";
+	const char *path_str = null_path;
+	size_t path_size = sizeof(null_path);
+	const void *buffer __free(kfree) = NULL;
+	struct landlock_details *details;
+
+	buffer = get_current_exe(&path_str, &path_size);
+	if (IS_ERR(buffer))
+		return ERR_CAST(buffer);
+
+	/*
+	 * Create the new details according to the path's length.  Do not
+	 * allocate with GFP_KERNEL_ACCOUNT because it is independent from the
+	 * caller.
+	 */
+	details =
+		kzalloc(struct_size(details, exe_path, path_size), GFP_KERNEL);
+	if (!details)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(details->exe_path, path_str, path_size);
+	WARN_ON_ONCE(current_cred() != current_real_cred());
+	details->pid = get_pid(task_pid(current));
+	details->uid = from_kuid(&init_user_ns, current_uid());
+	get_task_comm(details->comm, current);
+	return details;
+}
+
 /**
  * landlock_init_hierarchy_log - Partially initialize landlock_hierarchy
  *
  * @hierarchy: The hierarchy to initialize.
  *
+ * The current task is referenced as the domain that is enforcing the
+ * restriction.  The subjective credentials must not be in an overridden state.
+ *
  * @hierarchy->parent and @hierarchy->usage should already be set.
  */
 int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
 {
+	struct landlock_details *details;
+
+	details = get_current_details();
+	if (IS_ERR(details))
+		return PTR_ERR(details);
+
+	hierarchy->details = details;
 	hierarchy->id = landlock_get_id_range(1);
+	hierarchy->log_status = LANDLOCK_LOG_PENDING;
+	atomic64_set(&hierarchy->num_denials, 0);
 	return 0;
 }
 
diff --git a/security/landlock/domain.h b/security/landlock/domain.h
index f8df7103bd3d..2c6f04da3628 100644
--- a/security/landlock/domain.h
+++ b/security/landlock/domain.h
@@ -10,8 +10,62 @@
 #ifndef _SECURITY_LANDLOCK_DOMAIN_H
 #define _SECURITY_LANDLOCK_DOMAIN_H
 
+#include <linux/limits.h>
 #include <linux/mm.h>
+#include <linux/path.h>
+#include <linux/pid.h>
 #include <linux/refcount.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "audit.h"
+
+enum landlock_log_status {
+	LANDLOCK_LOG_PENDING = 0,
+	LANDLOCK_LOG_RECORDED,
+};
+
+/**
+ * struct landlock_details - Domain's creation information
+ *
+ * Rarely accessed, mainly when logging the first domain's denial.
+ *
+ * The contained pointers are initialized at the domain creation time and never
+ * changed again.  Contrary to most other Landlock object types, this one is
+ * not allocated with GFP_KERNEL_ACCOUNT because its size may not be under the
+ * caller's control (e.g. unknown exe_path) and the data is not explicitly
+ * requested nor used by tasks.
+ */
+struct landlock_details {
+	/**
+	 * @pid: PID of the task that initially restricted itself.  It still
+	 * identifies the same task.  Keeping a reference to this PID ensures that
+	 * it will not be recycled.
+	 */
+	struct pid *pid;
+	/**
+	 * @uid: UID of the task that initially restricted itself, at creation time.
+	 */
+	uid_t uid;
+	/**
+	 * @comm: Command line of the task that initially restricted itself, at
+	 * creation time.  Always NULL terminated.
+	 */
+	char comm[TASK_COMM_LEN];
+	/**
+	 * @exe_path: Executable path of the task that initially restricted
+	 * itself, at creation time.  Always NULL terminated, and never greater
+	 * than LANDLOCK_PATH_MAX_SIZE.
+	 */
+	char exe_path[];
+};
+
+/* Adds 11 extra characters for the potential " (deleted)" suffix. */
+#define LANDLOCK_PATH_MAX_SIZE (PATH_MAX + 11)
+
+/* Makes sure the greatest landlock_details can be allocated. */
+static_assert(struct_size_t(struct landlock_details, exe_path,
+			    LANDLOCK_PATH_MAX_SIZE) <= KMALLOC_MAX_SIZE);
 
 /**
  * struct landlock_hierarchy - Node in a domain hierarchy
@@ -29,10 +83,25 @@ struct landlock_hierarchy {
 	refcount_t usage;
 
 #ifdef CONFIG_AUDIT
+	/**
+	 * @log_status: Whether this domain should be logged or not.  Because
+	 * concurrent log entries may be created at the same time, it is still
+	 * possible to have several domain records of the same domain.
+	 */
+	enum landlock_log_status log_status;
+	/**
+	 * @num_denials: Number of access requests denied by this domain.
+	 * Masked (i.e. never logged) denials are still counted.
+	 */
+	atomic64_t num_denials;
 	/**
 	 * @id: Landlock domain ID, sets once at domain creation time.
 	 */
 	u64 id;
+	/**
+	 * @details: Information about the related domain.
+	 */
+	const struct landlock_details *details;
 #endif /* CONFIG_AUDIT */
 };
 
@@ -40,6 +109,16 @@ struct landlock_hierarchy {
 
 int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy);
 
+static inline void
+landlock_free_hierarchy_details(struct landlock_hierarchy *const hierarchy)
+{
+	if (WARN_ON_ONCE(!hierarchy || !hierarchy->details))
+		return;
+
+	put_pid(hierarchy->details->pid);
+	kfree(hierarchy->details);
+}
+
 #else /* CONFIG_AUDIT */
 
 static inline int
@@ -48,6 +127,11 @@ landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
 	return 0;
 }
 
+static inline void
+landlock_free_hierarchy_details(struct landlock_hierarchy *const hierarchy)
+{
+}
+
 #endif /* CONFIG_AUDIT */
 
 static inline void
@@ -62,6 +146,8 @@ static inline void landlock_put_hierarchy(struct landlock_hierarchy *hierarchy)
 	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
 		const struct landlock_hierarchy *const freeme = hierarchy;
 
+		landlock_log_drop_domain(hierarchy);
+		landlock_free_hierarchy_details(hierarchy);
 		hierarchy = hierarchy->parent;
 		kfree(freeme);
 	}
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index f273a40e9780..ce7940efea51 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -521,6 +521,9 @@ void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset)
  * @parent: Parent domain.
  * @ruleset: New ruleset to be merged.
  *
+ * The current task is requesting to be restricted.  The subjective credentials
+ * must not be in an overridden state. cf. landlock_init_hierarchy_log().
+ *
  * Returns the intersection of @parent and @ruleset, or returns @parent if
  * @ruleset is empty, or returns a duplicate of @ruleset if @parent is empty.
  */
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index bbb5996545d2..28af42d66261 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -17,10 +17,11 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
-#include "domain.h"
 #include "limits.h"
 #include "object.h"
 
+struct landlock_hierarchy;
+
 /**
  * struct landlock_layer - Access rights for a given layer
  */
-- 
2.49.0

[PATCH v7 11/28] landlock: Log mount-related denials

[Mickaël Salaün]

Add audit support for sb_mount, move_mount, sb_umount, sb_remount, and
sb_pivot_root hooks.

The new related blocker is "fs.change_topology".

Audit event sample:

  type=LANDLOCK_DENY msg=audit(1729738800.349:44): domain=195ba459b blockers=fs.change_topology name="/" dev="tmpfs" ino=1

Remove landlock_get_applicable_domain() and get_current_fs_domain()
which are now fully replaced with landlock_get_applicable_subject().

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Use "change_topology" instead of "change_layout".

Changes since v5:
- Move request declaration in the landlock_log_denial() calls.

Changes since v4:
- Rebase on top of the landlock_log_denial() and subject type changes.
- Fix off-by-one error in landlock_match_layer_level(), now merged into
  landlock_get_applicable_domain().

Changes since v3:
- Cosmetic change to the "fs.change_layout" name.

Changes since v2:
- Log the domain that denied the action because not all layers block FS
  layout changes.
- Fix landlock_match_layer_level().

Changes since v1:
- Rebased on the TCP patch series.
- Don't log missing permissions, only domain layer, and then remove the
  permission word (suggested by Günther)
---
 security/landlock/audit.c   |  3 ++
 security/landlock/audit.h   |  1 +
 security/landlock/fs.c      | 81 ++++++++++++++++++++++++++++++++-----
 security/landlock/ruleset.h | 30 --------------
 4 files changed, 74 insertions(+), 41 deletions(-)

diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index a0e6041a1e21..423e8c61ebbd 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -21,6 +21,9 @@ static const char *get_blocker(const enum landlock_request_type type)
 	switch (type) {
 	case LANDLOCK_REQUEST_PTRACE:
 		return "ptrace";
+
+	case LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY:
+		return "fs.change_topology";
 	}
 
 	WARN_ON_ONCE(1);
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 40ff230316c4..9ebe8766bbfd 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -15,6 +15,7 @@
 
 enum landlock_request_type {
 	LANDLOCK_REQUEST_PTRACE = 1,
+	LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
 };
 
 /*
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 13d1cd78e8c8..7249371857fc 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -23,6 +23,7 @@
 #include <linux/kernel.h>
 #include <linux/limits.h>
 #include <linux/list.h>
+#include <linux/lsm_audit.h>
 #include <linux/lsm_hooks.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
@@ -39,6 +40,7 @@
 #include <uapi/linux/landlock.h>
 
 #include "access.h"
+#include "audit.h"
 #include "common.h"
 #include "cred.h"
 #include "fs.h"
@@ -395,12 +397,6 @@ static const struct access_masks any_fs = {
 	.fs = ~0,
 };
 
-static const struct landlock_ruleset *get_current_fs_domain(void)
-{
-	return landlock_get_applicable_domain(landlock_get_current_domain(),
-					      any_fs);
-}
-
 /*
  * Check that a destination file hierarchy has more restrictions than a source
  * file hierarchy.  This is only used for link and rename actions.
@@ -1335,6 +1331,34 @@ static void hook_sb_delete(struct super_block *const sb)
 		       !atomic_long_read(&landlock_superblock(sb)->inode_refs));
 }
 
+static void
+log_fs_change_topology_path(const struct landlock_cred_security *const subject,
+			    size_t handle_layer, const struct path *const path)
+{
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
+		.audit = {
+			.type = LSM_AUDIT_DATA_PATH,
+			.u.path = *path,
+		},
+		.layer_plus_one = handle_layer + 1,
+	});
+}
+
+static void log_fs_change_topology_dentry(
+	const struct landlock_cred_security *const subject, size_t handle_layer,
+	struct dentry *const dentry)
+{
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
+		.audit = {
+			.type = LSM_AUDIT_DATA_DENTRY,
+			.u.dentry = dentry,
+		},
+		.layer_plus_one = handle_layer + 1,
+	});
+}
+
 /*
  * Because a Landlock security policy is defined according to the filesystem
  * topology (i.e. the mount namespace), changing it may grant access to files
@@ -1357,16 +1381,30 @@ static int hook_sb_mount(const char *const dev_name,
 			 const struct path *const path, const char *const type,
 			 const unsigned long flags, void *const data)
 {
-	if (!get_current_fs_domain())
+	size_t handle_layer;
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs,
+						&handle_layer);
+
+	if (!subject)
 		return 0;
+
+	log_fs_change_topology_path(subject, handle_layer, path);
 	return -EPERM;
 }
 
 static int hook_move_mount(const struct path *const from_path,
 			   const struct path *const to_path)
 {
-	if (!get_current_fs_domain())
+	size_t handle_layer;
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs,
+						&handle_layer);
+
+	if (!subject)
 		return 0;
+
+	log_fs_change_topology_path(subject, handle_layer, to_path);
 	return -EPERM;
 }
 
@@ -1376,15 +1414,29 @@ static int hook_move_mount(const struct path *const from_path,
  */
 static int hook_sb_umount(struct vfsmount *const mnt, const int flags)
 {
-	if (!get_current_fs_domain())
+	size_t handle_layer;
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs,
+						&handle_layer);
+
+	if (!subject)
 		return 0;
+
+	log_fs_change_topology_dentry(subject, handle_layer, mnt->mnt_root);
 	return -EPERM;
 }
 
 static int hook_sb_remount(struct super_block *const sb, void *const mnt_opts)
 {
-	if (!get_current_fs_domain())
+	size_t handle_layer;
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs,
+						&handle_layer);
+
+	if (!subject)
 		return 0;
+
+	log_fs_change_topology_dentry(subject, handle_layer, sb->s_root);
 	return -EPERM;
 }
 
@@ -1399,8 +1451,15 @@ static int hook_sb_remount(struct super_block *const sb, void *const mnt_opts)
 static int hook_sb_pivotroot(const struct path *const old_path,
 			     const struct path *const new_path)
 {
-	if (!get_current_fs_domain())
+	size_t handle_layer;
+	const struct landlock_cred_security *const subject =
+		landlock_get_applicable_subject(current_cred(), any_fs,
+						&handle_layer);
+
+	if (!subject)
 		return 0;
+
+	log_fs_change_topology_path(subject, handle_layer, new_path);
 	return -EPERM;
 }
 
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 28af42d66261..5da9a64f5af7 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -243,36 +243,6 @@ landlock_union_access_masks(const struct landlock_ruleset *const domain)
 	return matches.masks;
 }
 
-/**
- * landlock_get_applicable_domain - Return @domain if it applies to (handles)
- *				    at least one of the access rights specified
- *				    in @masks
- *
- * @domain: Landlock ruleset (used as a domain)
- * @masks: access masks
- *
- * Returns: @domain if any access rights specified in @masks is handled, or
- * NULL otherwise.
- */
-static inline const struct landlock_ruleset *
-landlock_get_applicable_domain(const struct landlock_ruleset *const domain,
-			       const struct access_masks masks)
-{
-	const union access_masks_all masks_all = {
-		.masks = masks,
-	};
-	union access_masks_all merge = {};
-
-	if (!domain)
-		return NULL;
-
-	merge.masks = landlock_union_access_masks(domain);
-	if (merge.all & masks_all.all)
-		return domain;
-
-	return NULL;
-}
-
 static inline void
 landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
 			    const access_mask_t fs_access_mask,
-- 
2.49.0

[PATCH v7 12/28] landlock: Log file-related denials

[Mickaël Salaün]

Add audit support for path_mkdir, path_mknod, path_symlink, path_unlink,
path_rmdir, path_truncate, path_link, path_rename, and file_open hooks.

The dedicated blockers are:
- fs.execute
- fs.write_file
- fs.read_file
- fs.read_dir
- fs.remove_dir
- fs.remove_file
- fs.make_char
- fs.make_dir
- fs.make_reg
- fs.make_sock
- fs.make_fifo
- fs.make_block
- fs.make_sym
- fs.refer
- fs.truncate
- fs.ioctl_dev

Audit event sample for a denied link action:

  type=LANDLOCK_DENY msg=audit(1729738800.349:44): domain=195ba459b blockers=fs.refer path="/usr/bin" dev="vda2" ino=351
  type=LANDLOCK_DENY msg=audit(1729738800.349:44): domain=195ba459b blockers=fs.make_reg,fs.refer path="/usr/local" dev="vda2" ino=365

We could pack blocker names (e.g. "fs:make_reg,refer") but that would
increase complexity for the kernel and log parsers.  Moreover, this
could not handle blockers of different classes (e.g. fs and net).  Make
it simple and flexible instead.

Add KUnit tests to check the identification from a layer_mask_t array of
the first layer level denying such request.

Cc: Günther Noack <gnoack@google.com>
Depends-on: 058518c20920 ("landlock: Align partial refer access checks with final ones")
Depends-on: d617f0d72d80 ("landlock: Optimize file path walks and prepare for audit support")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Fix log_request_* update typo in is_access_to_paths_allowed().

Changes since v4:
- Rebase on top of the landlock_log_denial() and subject type changes.
- Add Depends-on tags.

Changes since v3:
- Rename blockers from fs_* to fs.*
- Extend commit message.

Changes since v2:
- Replace integer with bool in log_blockers().
- Always initialize youngest_layer, spotted by Francis Laniel.
- Fix incorrect log reason by using access_masked_parent1 instead of
  access_request_parent1 (thanks to the previous fix patches).
- Clean up formatting.

Changes since v1:
- Move audit code to the ptrace patch.
- Revamp logging and support the path_link and path_rename hooks.
- Add KUnit tests.
---
 security/landlock/audit.c | 178 ++++++++++++++++++++++++++++++++++++--
 security/landlock/audit.h |   9 ++
 security/landlock/fs.c    |  62 +++++++++++--
 3 files changed, 233 insertions(+), 16 deletions(-)

diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index 423e8c61ebbd..d0c5f9ce1d43 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -7,23 +7,56 @@
 
 #include <kunit/test.h>
 #include <linux/audit.h>
+#include <linux/bitops.h>
 #include <linux/lsm_audit.h>
 #include <linux/pid.h>
+#include <uapi/linux/landlock.h>
 
 #include "audit.h"
+#include "common.h"
 #include "cred.h"
 #include "domain.h"
 #include "limits.h"
 #include "ruleset.h"
 
-static const char *get_blocker(const enum landlock_request_type type)
+static const char *const fs_access_strings[] = {
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = "fs.execute",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_WRITE_FILE)] = "fs.write_file",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_READ_FILE)] = "fs.read_file",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_READ_DIR)] = "fs.read_dir",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_REMOVE_DIR)] = "fs.remove_dir",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_REMOVE_FILE)] = "fs.remove_file",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_CHAR)] = "fs.make_char",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_DIR)] = "fs.make_dir",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_REG)] = "fs.make_reg",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_SOCK)] = "fs.make_sock",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_FIFO)] = "fs.make_fifo",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_BLOCK)] = "fs.make_block",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_MAKE_SYM)] = "fs.make_sym",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_REFER)] = "fs.refer",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_TRUNCATE)] = "fs.truncate",
+	[BIT_INDEX(LANDLOCK_ACCESS_FS_IOCTL_DEV)] = "fs.ioctl_dev",
+};
+
+static_assert(ARRAY_SIZE(fs_access_strings) == LANDLOCK_NUM_ACCESS_FS);
+
+static __attribute_const__ const char *
+get_blocker(const enum landlock_request_type type,
+	    const unsigned long access_bit)
 {
 	switch (type) {
 	case LANDLOCK_REQUEST_PTRACE:
+		WARN_ON_ONCE(access_bit != -1);
 		return "ptrace";
 
 	case LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY:
+		WARN_ON_ONCE(access_bit != -1);
 		return "fs.change_topology";
+
+	case LANDLOCK_REQUEST_FS_ACCESS:
+		if (WARN_ON_ONCE(access_bit >= ARRAY_SIZE(fs_access_strings)))
+			return "unknown";
+		return fs_access_strings[access_bit];
 	}
 
 	WARN_ON_ONCE(1);
@@ -31,9 +64,20 @@ static const char *get_blocker(const enum landlock_request_type type)
 }
 
 static void log_blockers(struct audit_buffer *const ab,
-			 const enum landlock_request_type type)
+			 const enum landlock_request_type type,
+			 const access_mask_t access)
 {
-	audit_log_format(ab, "%s", get_blocker(type));
+	const unsigned long access_mask = access;
+	unsigned long access_bit;
+	bool is_first = true;
+
+	for_each_set_bit(access_bit, &access_mask, BITS_PER_TYPE(access)) {
+		audit_log_format(ab, "%s%s", is_first ? "" : ",",
+				 get_blocker(type, access_bit));
+		is_first = false;
+	}
+	if (is_first)
+		audit_log_format(ab, "%s", get_blocker(type, -1));
 }
 
 static void log_domain(struct landlock_hierarchy *const hierarchy)
@@ -115,12 +159,113 @@ static void test_get_hierarchy(struct kunit *const test)
 
 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
 
+static size_t get_denied_layer(const struct landlock_ruleset *const domain,
+			       access_mask_t *const access_request,
+			       const layer_mask_t (*const layer_masks)[],
+			       const size_t layer_masks_size)
+{
+	const unsigned long access_req = *access_request;
+	unsigned long access_bit;
+	access_mask_t missing = 0;
+	long youngest_layer = -1;
+
+	for_each_set_bit(access_bit, &access_req, layer_masks_size) {
+		const access_mask_t mask = (*layer_masks)[access_bit];
+		long layer;
+
+		if (!mask)
+			continue;
+
+		/* __fls(1) == 0 */
+		layer = __fls(mask);
+		if (layer > youngest_layer) {
+			youngest_layer = layer;
+			missing = BIT(access_bit);
+		} else if (layer == youngest_layer) {
+			missing |= BIT(access_bit);
+		}
+	}
+
+	*access_request = missing;
+	if (youngest_layer == -1)
+		return domain->num_layers - 1;
+
+	return youngest_layer;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_get_denied_layer(struct kunit *const test)
+{
+	const struct landlock_ruleset dom = {
+		.num_layers = 5,
+	};
+	const layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT(0),
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_READ_FILE)] = BIT(1),
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_READ_DIR)] = BIT(1) | BIT(0),
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_REMOVE_DIR)] = BIT(2),
+	};
+	access_mask_t access;
+
+	access = LANDLOCK_ACCESS_FS_EXECUTE;
+	KUNIT_EXPECT_EQ(test, 0,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_EXECUTE);
+
+	access = LANDLOCK_ACCESS_FS_READ_FILE;
+	KUNIT_EXPECT_EQ(test, 1,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_FILE);
+
+	access = LANDLOCK_ACCESS_FS_READ_DIR;
+	KUNIT_EXPECT_EQ(test, 1,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_DIR);
+
+	access = LANDLOCK_ACCESS_FS_READ_FILE | LANDLOCK_ACCESS_FS_READ_DIR;
+	KUNIT_EXPECT_EQ(test, 1,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access,
+			LANDLOCK_ACCESS_FS_READ_FILE |
+				LANDLOCK_ACCESS_FS_READ_DIR);
+
+	access = LANDLOCK_ACCESS_FS_EXECUTE | LANDLOCK_ACCESS_FS_READ_DIR;
+	KUNIT_EXPECT_EQ(test, 1,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_DIR);
+
+	access = LANDLOCK_ACCESS_FS_WRITE_FILE;
+	KUNIT_EXPECT_EQ(test, 4,
+			get_denied_layer(&dom, &access, &layer_masks,
+					 sizeof(layer_masks)));
+	KUNIT_EXPECT_EQ(test, access, 0);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
 static bool is_valid_request(const struct landlock_request *const request)
 {
 	if (WARN_ON_ONCE(request->layer_plus_one > LANDLOCK_MAX_NUM_LAYERS))
 		return false;
 
-	if (WARN_ON_ONCE(!request->layer_plus_one))
+	if (WARN_ON_ONCE(!(!!request->layer_plus_one ^ !!request->access)))
+		return false;
+
+	if (request->access) {
+		if (WARN_ON_ONCE(!request->layer_masks))
+			return false;
+	} else {
+		if (WARN_ON_ONCE(request->layer_masks))
+			return false;
+	}
+
+	if (WARN_ON_ONCE(!!request->layer_masks ^ !!request->layer_masks_size))
 		return false;
 
 	return true;
@@ -138,6 +283,7 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 	struct audit_buffer *ab;
 	struct landlock_hierarchy *youngest_denied;
 	size_t youngest_layer;
+	access_mask_t missing;
 
 	if (WARN_ON_ONCE(!subject || !subject->domain ||
 			 !subject->domain->hierarchy || !request))
@@ -146,8 +292,25 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 	if (!is_valid_request(request))
 		return;
 
-	youngest_layer = request->layer_plus_one - 1;
-	youngest_denied = get_hierarchy(subject->domain, youngest_layer);
+	missing = request->access;
+	if (missing) {
+		/* Gets the nearest domain that denies the request. */
+		if (request->layer_masks) {
+			youngest_layer = get_denied_layer(
+				subject->domain, &missing, request->layer_masks,
+				request->layer_masks_size);
+		} else {
+			/* This will change with the next commit. */
+			WARN_ON_ONCE(1);
+			youngest_layer = subject->domain->num_layers;
+		}
+		youngest_denied =
+			get_hierarchy(subject->domain, youngest_layer);
+	} else {
+		youngest_layer = request->layer_plus_one - 1;
+		youngest_denied =
+			get_hierarchy(subject->domain, youngest_layer);
+	}
 
 	/*
 	 * Consistently keeps track of the number of denied access requests
@@ -171,7 +334,7 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 		return;
 
 	audit_log_format(ab, "domain=%llx blockers=", youngest_denied->id);
-	log_blockers(ab, request->type);
+	log_blockers(ab, request->type, missing);
 	audit_log_lsm_data(ab, &request->audit);
 	audit_log_end(ab);
 
@@ -224,6 +387,7 @@ void landlock_log_drop_domain(const struct landlock_hierarchy *const hierarchy)
 static struct kunit_case test_cases[] = {
 	/* clang-format off */
 	KUNIT_CASE(test_get_hierarchy),
+	KUNIT_CASE(test_get_denied_layer),
 	{}
 	/* clang-format on */
 };
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 9ebe8766bbfd..2a154116134e 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -11,11 +11,13 @@
 #include <linux/audit.h>
 #include <linux/lsm_audit.h>
 
+#include "access.h"
 #include "cred.h"
 
 enum landlock_request_type {
 	LANDLOCK_REQUEST_PTRACE = 1,
 	LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
+	LANDLOCK_REQUEST_FS_ACCESS,
 };
 
 /*
@@ -33,6 +35,13 @@ struct landlock_request {
 	 * extra one is useful to detect uninitialized field.
 	 */
 	size_t layer_plus_one;
+
+	/* Required field for configurable access control. */
+	access_mask_t access;
+
+	/* Required fields for requests with layer masks. */
+	const layer_mask_t (*layer_masks)[];
+	size_t layer_masks_size;
 };
 
 #ifdef CONFIG_AUDIT
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 7249371857fc..ba03439caab9 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -726,6 +726,7 @@ static void test_is_eacces_with_write(struct kunit *const test)
  *     those identified by @access_request_parent1).  This matrix can
  *     initially refer to domain layer masks and, when the accesses for the
  *     destination and source are the same, to requested layer masks.
+ * @log_request_parent1: Audit request to fill if the related access is denied.
  * @dentry_child1: Dentry to the initial child of the parent1 path.  This
  *     pointer must be NULL for non-refer actions (i.e. not link nor rename).
  * @access_request_parent2: Similar to @access_request_parent1 but for a
@@ -734,6 +735,7 @@ static void test_is_eacces_with_write(struct kunit *const test)
  *     the source.  Must be set to 0 when using a simple path request.
  * @layer_masks_parent2: Similar to @layer_masks_parent1 but for a refer
  *     action.  This must be NULL otherwise.
+ * @log_request_parent2: Audit request to fill if the related access is denied.
  * @dentry_child2: Dentry to the initial child of the parent2 path.  This
  *     pointer is only set for RENAME_EXCHANGE actions and must be NULL
  *     otherwise.
@@ -753,10 +755,12 @@ static bool is_access_to_paths_allowed(
 	const struct path *const path,
 	const access_mask_t access_request_parent1,
 	layer_mask_t (*const layer_masks_parent1)[LANDLOCK_NUM_ACCESS_FS],
-	const struct dentry *const dentry_child1,
+	struct landlock_request *const log_request_parent1,
+	struct dentry *const dentry_child1,
 	const access_mask_t access_request_parent2,
 	layer_mask_t (*const layer_masks_parent2)[LANDLOCK_NUM_ACCESS_FS],
-	const struct dentry *const dentry_child2)
+	struct landlock_request *const log_request_parent2,
+	struct dentry *const dentry_child2)
 {
 	bool allowed_parent1 = false, allowed_parent2 = false, is_dom_check,
 	     child1_is_directory = true, child2_is_directory = true;
@@ -921,6 +925,25 @@ static bool is_access_to_paths_allowed(
 	}
 	path_put(&walker_path);
 
+	if (!allowed_parent1) {
+		log_request_parent1->type = LANDLOCK_REQUEST_FS_ACCESS;
+		log_request_parent1->audit.type = LSM_AUDIT_DATA_PATH;
+		log_request_parent1->audit.u.path = *path;
+		log_request_parent1->access = access_masked_parent1;
+		log_request_parent1->layer_masks = layer_masks_parent1;
+		log_request_parent1->layer_masks_size =
+			ARRAY_SIZE(*layer_masks_parent1);
+	}
+
+	if (!allowed_parent2) {
+		log_request_parent2->type = LANDLOCK_REQUEST_FS_ACCESS;
+		log_request_parent2->audit.type = LSM_AUDIT_DATA_PATH;
+		log_request_parent2->audit.u.path = *path;
+		log_request_parent2->access = access_masked_parent2;
+		log_request_parent2->layer_masks = layer_masks_parent2;
+		log_request_parent2->layer_masks_size =
+			ARRAY_SIZE(*layer_masks_parent2);
+	}
 	return allowed_parent1 && allowed_parent2;
 }
 
@@ -933,6 +956,7 @@ static int current_check_access_path(const struct path *const path,
 	const struct landlock_cred_security *const subject =
 		landlock_get_applicable_subject(current_cred(), masks, NULL);
 	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
+	struct landlock_request request = {};
 
 	if (!subject)
 		return 0;
@@ -941,9 +965,11 @@ static int current_check_access_path(const struct path *const path,
 						   access_request, &layer_masks,
 						   LANDLOCK_KEY_INODE);
 	if (is_access_to_paths_allowed(subject->domain, path, access_request,
-				       &layer_masks, NULL, 0, NULL, NULL))
+				       &layer_masks, &request, NULL, 0, NULL,
+				       NULL, NULL))
 		return 0;
 
+	landlock_log_denial(subject, &request);
 	return -EACCES;
 }
 
@@ -1112,6 +1138,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 	struct dentry *old_parent;
 	layer_mask_t layer_masks_parent1[LANDLOCK_NUM_ACCESS_FS] = {},
 		     layer_masks_parent2[LANDLOCK_NUM_ACCESS_FS] = {};
+	struct landlock_request request1 = {}, request2 = {};
 
 	if (!subject)
 		return 0;
@@ -1143,10 +1170,13 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 			subject->domain,
 			access_request_parent1 | access_request_parent2,
 			&layer_masks_parent1, LANDLOCK_KEY_INODE);
-		if (is_access_to_paths_allowed(
-			    subject->domain, new_dir, access_request_parent1,
-			    &layer_masks_parent1, NULL, 0, NULL, NULL))
+		if (is_access_to_paths_allowed(subject->domain, new_dir,
+					       access_request_parent1,
+					       &layer_masks_parent1, &request1,
+					       NULL, 0, NULL, NULL, NULL))
 			return 0;
+
+		landlock_log_denial(subject, &request1);
 		return -EACCES;
 	}
 
@@ -1185,10 +1215,20 @@ static int current_check_refer_path(struct dentry *const old_dentry,
 	 */
 	if (is_access_to_paths_allowed(
 		    subject->domain, &mnt_dir, access_request_parent1,
-		    &layer_masks_parent1, old_dentry, access_request_parent2,
-		    &layer_masks_parent2, exchange ? new_dentry : NULL))
+		    &layer_masks_parent1, &request1, old_dentry,
+		    access_request_parent2, &layer_masks_parent2, &request2,
+		    exchange ? new_dentry : NULL))
 		return 0;
 
+	if (request1.access) {
+		request1.audit.u.path.dentry = old_parent;
+		landlock_log_denial(subject, &request1);
+	}
+	if (request2.access) {
+		request2.audit.u.path.dentry = new_dir->dentry;
+		landlock_log_denial(subject, &request2);
+	}
+
 	/*
 	 * This prioritizes EACCES over EXDEV for all actions, including
 	 * renames with RENAME_EXCHANGE.
@@ -1578,6 +1618,7 @@ static int hook_file_open(struct file *const file)
 		optional_access;
 	const struct landlock_cred_security *const subject =
 		landlock_get_applicable_subject(file->f_cred, any_fs, NULL);
+	struct landlock_request request = {};
 
 	if (!subject)
 		return 0;
@@ -1604,7 +1645,7 @@ static int hook_file_open(struct file *const file)
 		    landlock_init_layer_masks(subject->domain,
 					      full_access_request, &layer_masks,
 					      LANDLOCK_KEY_INODE),
-		    &layer_masks, NULL, 0, NULL, NULL)) {
+		    &layer_masks, &request, NULL, 0, NULL, NULL, NULL)) {
 		allowed_access = full_access_request;
 	} else {
 		unsigned long access_bit;
@@ -1634,6 +1675,9 @@ static int hook_file_open(struct file *const file)
 	if ((open_access_request & allowed_access) == open_access_request)
 		return 0;
 
+	/* Sets access to reflect the actual request. */
+	request.access = open_access_request;
+	landlock_log_denial(subject, &request);
 	return -EACCES;
 }
 
-- 
2.49.0

[PATCH v7 13/28] landlock: Factor out IOCTL hooks

[Mickaël Salaün]

Compat and non-compat IOCTL hooks are almost the same, except to compare
the IOCTL command.  Factor out these two IOCTL hooks to highlight the
difference and minimize audit changes (see next commit).

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- New patch.
---
 security/landlock/fs.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index ba03439caab9..c67ef35248e3 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1698,8 +1698,8 @@ static int hook_file_truncate(struct file *const file)
 	return -EACCES;
 }
 
-static int hook_file_ioctl(struct file *file, unsigned int cmd,
-			   unsigned long arg)
+static int hook_file_ioctl_common(const struct file *const file,
+				  const unsigned int cmd, const bool is_compat)
 {
 	access_mask_t allowed_access = landlock_file(file)->allowed_access;
 
@@ -1715,33 +1715,23 @@ static int hook_file_ioctl(struct file *file, unsigned int cmd,
 	if (!is_device(file))
 		return 0;
 
-	if (is_masked_device_ioctl(cmd))
+	if (unlikely(is_compat) ? is_masked_device_ioctl_compat(cmd) :
+				  is_masked_device_ioctl(cmd))
 		return 0;
 
 	return -EACCES;
 }
 
+static int hook_file_ioctl(struct file *file, unsigned int cmd,
+			   unsigned long arg)
+{
+	return hook_file_ioctl_common(file, cmd, false);
+}
+
 static int hook_file_ioctl_compat(struct file *file, unsigned int cmd,
 				  unsigned long arg)
 {
-	access_mask_t allowed_access = landlock_file(file)->allowed_access;
-
-	/*
-	 * It is the access rights at the time of opening the file which
-	 * determine whether IOCTL can be used on the opened file later.
-	 *
-	 * The access right is attached to the opened file in hook_file_open().
-	 */
-	if (allowed_access & LANDLOCK_ACCESS_FS_IOCTL_DEV)
-		return 0;
-
-	if (!is_device(file))
-		return 0;
-
-	if (is_masked_device_ioctl_compat(cmd))
-		return 0;
-
-	return -EACCES;
+	return hook_file_ioctl_common(file, cmd, true);
 }
 
 static void hook_file_set_fowner(struct file *file)
-- 
2.49.0

[PATCH v7 14/28] landlock: Log truncate and IOCTL denials

[Mickaël Salaün]

Add audit support to the file_truncate and file_ioctl hooks.

Add a deny_masks_t type and related helpers to store the domain's layer
level per optional access rights (i.e. LANDLOCK_ACCESS_FS_TRUNCATE and
LANDLOCK_ACCESS_FS_IOCTL_DEV) when opening a file, which cannot be
inferred later.  In practice, the landlock_file_security aligned blob size is
still 16 bytes because this new one-byte deny_masks field follows the
existing two-bytes allowed_access field and precede the packed
fown_subject.

Implementing deny_masks_t with a bitfield instead of a struct enables a
generic implementation to store and extract layer levels.

Add KUnit tests to check the identification of a layer level from a
deny_masks_t, and the computation of a deny_masks_t from an access right
with its layer level or a layer_mask_t array.

Audit event sample:

  type=LANDLOCK_DENY msg=audit(1729738800.349:44): domain=195ba459b blockers=fs.ioctl_dev path="/dev/tty" dev="devtmpfs" ino=9 ioctlcmd=0x5401

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Remove useless include.

Changes since v5:
- Switch to LSM_AUDIT_DATA_IOCTL_OP for IOCTL hooks, and update sample
  accordingly.
- Move request declarations in the landlock_log_denial() calls to
  not impact allowed requests with audit, and remove update_request()
  which is now useless.

Changes since v4:
- Rebase on top of the landlock_log_denial() and subject type changes.

Changes since v3:
- Rename get_layer_from_deny_masks().

Changes since v2:
- Fix !CONFIG_AUDIT build warning.
- Rename ACCESS_FS_OPTIONAL to _LANDLOCK_ACCESS_FS_OPTIONAL.
---
 security/landlock/access.h |  23 +++++++
 security/landlock/audit.c  | 101 ++++++++++++++++++++++++++--
 security/landlock/audit.h  |   4 ++
 security/landlock/domain.c | 133 +++++++++++++++++++++++++++++++++++++
 security/landlock/domain.h |   7 ++
 security/landlock/fs.c     |  34 ++++++++++
 security/landlock/fs.h     |   9 +++
 7 files changed, 306 insertions(+), 5 deletions(-)

diff --git a/security/landlock/access.h b/security/landlock/access.h
index 74fd8f399fbd..1eaaafa63178 100644
--- a/security/landlock/access.h
+++ b/security/landlock/access.h
@@ -28,6 +28,12 @@
 	LANDLOCK_ACCESS_FS_REFER)
 /* clang-format on */
 
+/* clang-format off */
+#define _LANDLOCK_ACCESS_FS_OPTIONAL ( \
+	LANDLOCK_ACCESS_FS_TRUNCATE | \
+	LANDLOCK_ACCESS_FS_IOCTL_DEV)
+/* clang-format on */
+
 typedef u16 access_mask_t;
 
 /* Makes sure all filesystem access rights can be stored. */
@@ -60,6 +66,23 @@ typedef u16 layer_mask_t;
 /* Makes sure all layers can be checked. */
 static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
 
+/*
+ * Tracks domains responsible of a denied access.  This is required to avoid
+ * storing in each object the full layer_masks[] required by update_request().
+ */
+typedef u8 deny_masks_t;
+
+/*
+ * Makes sure all optional access rights can be tied to a layer index (cf.
+ * get_deny_mask).
+ */
+static_assert(BITS_PER_TYPE(deny_masks_t) >=
+	      (HWEIGHT(LANDLOCK_MAX_NUM_LAYERS - 1) *
+	       HWEIGHT(_LANDLOCK_ACCESS_FS_OPTIONAL)));
+
+/* LANDLOCK_MAX_NUM_LAYERS must be a power of two (cf. deny_masks_t assert). */
+static_assert(HWEIGHT(LANDLOCK_MAX_NUM_LAYERS) == 1);
+
 /* Upgrades with all initially denied by default access rights. */
 static inline struct access_masks
 landlock_upgrade_handled_access_masks(struct access_masks access_masks)
diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index d0c5f9ce1d43..f50ce677e3a0 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -12,6 +12,7 @@
 #include <linux/pid.h>
 #include <uapi/linux/landlock.h>
 
+#include "access.h"
 #include "audit.h"
 #include "common.h"
 #include "cred.h"
@@ -249,6 +250,88 @@ static void test_get_denied_layer(struct kunit *const test)
 
 #endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
 
+static size_t
+get_layer_from_deny_masks(access_mask_t *const access_request,
+			  const access_mask_t all_existing_optional_access,
+			  const deny_masks_t deny_masks)
+{
+	const unsigned long access_opt = all_existing_optional_access;
+	const unsigned long access_req = *access_request;
+	access_mask_t missing = 0;
+	size_t youngest_layer = 0;
+	size_t access_index = 0;
+	unsigned long access_bit;
+
+	/* This will require change with new object types. */
+	WARN_ON_ONCE(access_opt != _LANDLOCK_ACCESS_FS_OPTIONAL);
+
+	for_each_set_bit(access_bit, &access_opt,
+			 BITS_PER_TYPE(access_mask_t)) {
+		if (access_req & BIT(access_bit)) {
+			const size_t layer =
+				(deny_masks >> (access_index * 4)) &
+				(LANDLOCK_MAX_NUM_LAYERS - 1);
+
+			if (layer > youngest_layer) {
+				youngest_layer = layer;
+				missing = BIT(access_bit);
+			} else if (layer == youngest_layer) {
+				missing |= BIT(access_bit);
+			}
+		}
+		access_index++;
+	}
+
+	*access_request = missing;
+	return youngest_layer;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_get_layer_from_deny_masks(struct kunit *const test)
+{
+	deny_masks_t deny_mask;
+	access_mask_t access;
+
+	/* truncate:0 ioctl_dev:2 */
+	deny_mask = 0x20;
+
+	access = LANDLOCK_ACCESS_FS_TRUNCATE;
+	KUNIT_EXPECT_EQ(test, 0,
+			get_layer_from_deny_masks(&access,
+						  _LANDLOCK_ACCESS_FS_OPTIONAL,
+						  deny_mask));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE);
+
+	access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV;
+	KUNIT_EXPECT_EQ(test, 2,
+			get_layer_from_deny_masks(&access,
+						  _LANDLOCK_ACCESS_FS_OPTIONAL,
+						  deny_mask));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV);
+
+	/* truncate:15 ioctl_dev:15 */
+	deny_mask = 0xff;
+
+	access = LANDLOCK_ACCESS_FS_TRUNCATE;
+	KUNIT_EXPECT_EQ(test, 15,
+			get_layer_from_deny_masks(&access,
+						  _LANDLOCK_ACCESS_FS_OPTIONAL,
+						  deny_mask));
+	KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE);
+
+	access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV;
+	KUNIT_EXPECT_EQ(test, 15,
+			get_layer_from_deny_masks(&access,
+						  _LANDLOCK_ACCESS_FS_OPTIONAL,
+						  deny_mask));
+	KUNIT_EXPECT_EQ(test, access,
+			LANDLOCK_ACCESS_FS_TRUNCATE |
+				LANDLOCK_ACCESS_FS_IOCTL_DEV);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
 static bool is_valid_request(const struct landlock_request *const request)
 {
 	if (WARN_ON_ONCE(request->layer_plus_one > LANDLOCK_MAX_NUM_LAYERS))
@@ -258,16 +341,23 @@ static bool is_valid_request(const struct landlock_request *const request)
 		return false;
 
 	if (request->access) {
-		if (WARN_ON_ONCE(!request->layer_masks))
+		if (WARN_ON_ONCE(!(!!request->layer_masks ^
+				   !!request->all_existing_optional_access)))
 			return false;
 	} else {
-		if (WARN_ON_ONCE(request->layer_masks))
+		if (WARN_ON_ONCE(request->layer_masks ||
+				 request->all_existing_optional_access))
 			return false;
 	}
 
 	if (WARN_ON_ONCE(!!request->layer_masks ^ !!request->layer_masks_size))
 		return false;
 
+	if (request->deny_masks) {
+		if (WARN_ON_ONCE(!request->all_existing_optional_access))
+			return false;
+	}
+
 	return true;
 }
 
@@ -300,9 +390,9 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 				subject->domain, &missing, request->layer_masks,
 				request->layer_masks_size);
 		} else {
-			/* This will change with the next commit. */
-			WARN_ON_ONCE(1);
-			youngest_layer = subject->domain->num_layers;
+			youngest_layer = get_layer_from_deny_masks(
+				&missing, request->all_existing_optional_access,
+				request->deny_masks);
 		}
 		youngest_denied =
 			get_hierarchy(subject->domain, youngest_layer);
@@ -388,6 +478,7 @@ static struct kunit_case test_cases[] = {
 	/* clang-format off */
 	KUNIT_CASE(test_get_hierarchy),
 	KUNIT_CASE(test_get_denied_layer),
+	KUNIT_CASE(test_get_layer_from_deny_masks),
 	{}
 	/* clang-format on */
 };
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 2a154116134e..8130a6fcad07 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -42,6 +42,10 @@ struct landlock_request {
 	/* Required fields for requests with layer masks. */
 	const layer_mask_t (*layer_masks)[];
 	size_t layer_masks_size;
+
+	/* Required fields for requests with deny masks. */
+	const access_mask_t all_existing_optional_access;
+	deny_masks_t deny_masks;
 };
 
 #ifdef CONFIG_AUDIT
diff --git a/security/landlock/domain.c b/security/landlock/domain.c
index 3c1715e4b1c9..f61fa5ae8e56 100644
--- a/security/landlock/domain.c
+++ b/security/landlock/domain.c
@@ -7,6 +7,9 @@
  * Copyright © 2024-2025 Microsoft Corporation
  */
 
+#include <kunit/test.h>
+#include <linux/bitops.h>
+#include <linux/bits.h>
 #include <linux/cred.h>
 #include <linux/file.h>
 #include <linux/mm.h>
@@ -15,6 +18,8 @@
 #include <linux/sched.h>
 #include <linux/uidgid.h>
 
+#include "access.h"
+#include "common.h"
 #include "domain.h"
 #include "id.h"
 
@@ -126,4 +131,132 @@ int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
 	return 0;
 }
 
+static deny_masks_t
+get_layer_deny_mask(const access_mask_t all_existing_optional_access,
+		    const unsigned long access_bit, const size_t layer)
+{
+	unsigned long access_weight;
+
+	/* This may require change with new object types. */
+	WARN_ON_ONCE(all_existing_optional_access !=
+		     _LANDLOCK_ACCESS_FS_OPTIONAL);
+
+	if (WARN_ON_ONCE(layer >= LANDLOCK_MAX_NUM_LAYERS))
+		return 0;
+
+	access_weight = hweight_long(all_existing_optional_access &
+				     GENMASK(access_bit, 0));
+	if (WARN_ON_ONCE(access_weight < 1))
+		return 0;
+
+	return layer
+	       << ((access_weight - 1) * HWEIGHT(LANDLOCK_MAX_NUM_LAYERS - 1));
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_get_layer_deny_mask(struct kunit *const test)
+{
+	const unsigned long truncate = BIT_INDEX(LANDLOCK_ACCESS_FS_TRUNCATE);
+	const unsigned long ioctl_dev = BIT_INDEX(LANDLOCK_ACCESS_FS_IOCTL_DEV);
+
+	KUNIT_EXPECT_EQ(test, 0,
+			get_layer_deny_mask(_LANDLOCK_ACCESS_FS_OPTIONAL,
+					    truncate, 0));
+	KUNIT_EXPECT_EQ(test, 0x3,
+			get_layer_deny_mask(_LANDLOCK_ACCESS_FS_OPTIONAL,
+					    truncate, 3));
+
+	KUNIT_EXPECT_EQ(test, 0,
+			get_layer_deny_mask(_LANDLOCK_ACCESS_FS_OPTIONAL,
+					    ioctl_dev, 0));
+	KUNIT_EXPECT_EQ(test, 0xf0,
+			get_layer_deny_mask(_LANDLOCK_ACCESS_FS_OPTIONAL,
+					    ioctl_dev, 15));
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+deny_masks_t
+landlock_get_deny_masks(const access_mask_t all_existing_optional_access,
+			const access_mask_t optional_access,
+			const layer_mask_t (*const layer_masks)[],
+			const size_t layer_masks_size)
+{
+	const unsigned long access_opt = optional_access;
+	unsigned long access_bit;
+	deny_masks_t deny_masks = 0;
+
+	/* This may require change with new object types. */
+	WARN_ON_ONCE(access_opt !=
+		     (optional_access & all_existing_optional_access));
+
+	if (WARN_ON_ONCE(!layer_masks))
+		return 0;
+
+	if (WARN_ON_ONCE(!access_opt))
+		return 0;
+
+	for_each_set_bit(access_bit, &access_opt, layer_masks_size) {
+		const layer_mask_t mask = (*layer_masks)[access_bit];
+
+		if (!mask)
+			continue;
+
+		/* __fls(1) == 0 */
+		deny_masks |= get_layer_deny_mask(all_existing_optional_access,
+						  access_bit, __fls(mask));
+	}
+	return deny_masks;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_landlock_get_deny_masks(struct kunit *const test)
+{
+	const layer_mask_t layers1[BITS_PER_TYPE(access_mask_t)] = {
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_EXECUTE)] = BIT_ULL(0) |
+							  BIT_ULL(9),
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_TRUNCATE)] = BIT_ULL(1),
+		[BIT_INDEX(LANDLOCK_ACCESS_FS_IOCTL_DEV)] = BIT_ULL(2) |
+							    BIT_ULL(0),
+	};
+
+	KUNIT_EXPECT_EQ(test, 0x1,
+			landlock_get_deny_masks(_LANDLOCK_ACCESS_FS_OPTIONAL,
+						LANDLOCK_ACCESS_FS_TRUNCATE,
+						&layers1, ARRAY_SIZE(layers1)));
+	KUNIT_EXPECT_EQ(test, 0x20,
+			landlock_get_deny_masks(_LANDLOCK_ACCESS_FS_OPTIONAL,
+						LANDLOCK_ACCESS_FS_IOCTL_DEV,
+						&layers1, ARRAY_SIZE(layers1)));
+	KUNIT_EXPECT_EQ(
+		test, 0x21,
+		landlock_get_deny_masks(_LANDLOCK_ACCESS_FS_OPTIONAL,
+					LANDLOCK_ACCESS_FS_TRUNCATE |
+						LANDLOCK_ACCESS_FS_IOCTL_DEV,
+					&layers1, ARRAY_SIZE(layers1)));
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static struct kunit_case test_cases[] = {
+	/* clang-format off */
+	KUNIT_CASE(test_get_layer_deny_mask),
+	KUNIT_CASE(test_landlock_get_deny_masks),
+	{}
+	/* clang-format on */
+};
+
+static struct kunit_suite test_suite = {
+	.name = "landlock_domain",
+	.test_cases = test_cases,
+};
+
+kunit_test_suite(test_suite);
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
 #endif /* CONFIG_AUDIT */
diff --git a/security/landlock/domain.h b/security/landlock/domain.h
index 2c6f04da3628..96642dd87b33 100644
--- a/security/landlock/domain.h
+++ b/security/landlock/domain.h
@@ -18,6 +18,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 
+#include "access.h"
 #include "audit.h"
 
 enum landlock_log_status {
@@ -107,6 +108,12 @@ struct landlock_hierarchy {
 
 #ifdef CONFIG_AUDIT
 
+deny_masks_t
+landlock_get_deny_masks(const access_mask_t all_existing_optional_access,
+			const access_mask_t optional_access,
+			const layer_mask_t (*const layer_masks)[],
+			size_t layer_masks_size);
+
 int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy);
 
 static inline void
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index c67ef35248e3..9d7443ff67c7 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -43,6 +43,7 @@
 #include "audit.h"
 #include "common.h"
 #include "cred.h"
+#include "domain.h"
 #include "fs.h"
 #include "limits.h"
 #include "object.h"
@@ -1671,6 +1672,11 @@ static int hook_file_open(struct file *const file)
 	 * file access rights in the opened struct file.
 	 */
 	landlock_file(file)->allowed_access = allowed_access;
+#ifdef CONFIG_AUDIT
+	landlock_file(file)->deny_masks = landlock_get_deny_masks(
+		_LANDLOCK_ACCESS_FS_OPTIONAL, optional_access, &layer_masks,
+		ARRAY_SIZE(layer_masks));
+#endif /* CONFIG_AUDIT */
 
 	if ((open_access_request & allowed_access) == open_access_request)
 		return 0;
@@ -1695,6 +1701,19 @@ static int hook_file_truncate(struct file *const file)
 	 */
 	if (landlock_file(file)->allowed_access & LANDLOCK_ACCESS_FS_TRUNCATE)
 		return 0;
+
+	landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_FS_ACCESS,
+		.audit = {
+			.type = LSM_AUDIT_DATA_FILE,
+			.u.file = file,
+		},
+		.all_existing_optional_access = _LANDLOCK_ACCESS_FS_OPTIONAL,
+		.access = LANDLOCK_ACCESS_FS_TRUNCATE,
+#ifdef CONFIG_AUDIT
+		.deny_masks = landlock_file(file)->deny_masks,
+#endif /* CONFIG_AUDIT */
+	});
 	return -EACCES;
 }
 
@@ -1719,6 +1738,21 @@ static int hook_file_ioctl_common(const struct file *const file,
 				  is_masked_device_ioctl(cmd))
 		return 0;
 
+	landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_FS_ACCESS,
+		.audit = {
+			.type = LSM_AUDIT_DATA_IOCTL_OP,
+			.u.op = &(struct lsm_ioctlop_audit) {
+				.path = file->f_path,
+				.cmd = cmd,
+			},
+		},
+		.all_existing_optional_access = _LANDLOCK_ACCESS_FS_OPTIONAL,
+		.access = LANDLOCK_ACCESS_FS_IOCTL_DEV,
+#ifdef CONFIG_AUDIT
+		.deny_masks = landlock_file(file)->deny_masks,
+#endif /* CONFIG_AUDIT */
+	});
 	return -EACCES;
 }
 
diff --git a/security/landlock/fs.h b/security/landlock/fs.h
index 1449a90e92c7..3a09ba985b74 100644
--- a/security/landlock/fs.h
+++ b/security/landlock/fs.h
@@ -54,6 +54,15 @@ struct landlock_file_security {
 	 * needed to authorize later operations on the open file.
 	 */
 	access_mask_t allowed_access;
+
+#ifdef CONFIG_AUDIT
+	/**
+	 * @deny_masks: Domain layer levels that deny an optional access (see
+	 * _LANDLOCK_ACCESS_FS_OPTIONAL).
+	 */
+	deny_masks_t deny_masks;
+#endif /* CONFIG_AUDIT */
+
 	/**
 	 * @fown_subject: Landlock credential of the task that set the PID that
 	 * may receive a signal e.g., SIGURG when writing MSG_OOB to the
-- 
2.49.0

[PATCH v7 15/28] landlock: Log TCP bind and connect denials

[Mickaël Salaün]

Add audit support to socket_bind and socket_connect hooks.

The related blockers are:
- net.bind_tcp
- net.connect_tcp

Audit event sample:

  type=LANDLOCK_DENY msg=audit(1729738800.349:44): domain=195ba459b blockers=net.connect_tcp daddr=127.0.0.1 dest=80

Cc: Günther Noack <gnoack@google.com>
Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Cc: Mikhail Ivanov <ivanov.mikhail1@huawei-partners.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Move request declaration in the landlock_log_denial() call to
  not impact allowed requests with audit.

Changes since v4:
- Rebase on top of the landlock_log_denial() and subject type changes.

Changes since v3:
- Rename blockers from net_* to net.*

Changes since v2:
- Remove potentially superfluous IPv6 saddr log, spotted by Francis
  Laniel.
- Cosmetic improvements.
---
 security/landlock/audit.c | 12 +++++++++
 security/landlock/audit.h |  1 +
 security/landlock/net.c   | 51 ++++++++++++++++++++++++++++++++++++---
 3 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index f50ce677e3a0..66ff9a5d9866 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -41,6 +41,13 @@ static const char *const fs_access_strings[] = {
 
 static_assert(ARRAY_SIZE(fs_access_strings) == LANDLOCK_NUM_ACCESS_FS);
 
+static const char *const net_access_strings[] = {
+	[BIT_INDEX(LANDLOCK_ACCESS_NET_BIND_TCP)] = "net.bind_tcp",
+	[BIT_INDEX(LANDLOCK_ACCESS_NET_CONNECT_TCP)] = "net.connect_tcp",
+};
+
+static_assert(ARRAY_SIZE(net_access_strings) == LANDLOCK_NUM_ACCESS_NET);
+
 static __attribute_const__ const char *
 get_blocker(const enum landlock_request_type type,
 	    const unsigned long access_bit)
@@ -58,6 +65,11 @@ get_blocker(const enum landlock_request_type type,
 		if (WARN_ON_ONCE(access_bit >= ARRAY_SIZE(fs_access_strings)))
 			return "unknown";
 		return fs_access_strings[access_bit];
+
+	case LANDLOCK_REQUEST_NET_ACCESS:
+		if (WARN_ON_ONCE(access_bit >= ARRAY_SIZE(net_access_strings)))
+			return "unknown";
+		return net_access_strings[access_bit];
 	}
 
 	WARN_ON_ONCE(1);
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 8130a6fcad07..486b4e7050d3 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -18,6 +18,7 @@ enum landlock_request_type {
 	LANDLOCK_REQUEST_PTRACE = 1,
 	LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
 	LANDLOCK_REQUEST_FS_ACCESS,
+	LANDLOCK_REQUEST_NET_ACCESS,
 };
 
 /*
diff --git a/security/landlock/net.c b/security/landlock/net.c
index 6fb3e60bc5ff..f4478e6a2c0b 100644
--- a/security/landlock/net.c
+++ b/security/landlock/net.c
@@ -7,10 +7,12 @@
  */
 
 #include <linux/in.h>
+#include <linux/lsm_audit.h>
 #include <linux/net.h>
 #include <linux/socket.h>
 #include <net/ipv6.h>
 
+#include "audit.h"
 #include "common.h"
 #include "cred.h"
 #include "limits.h"
@@ -55,6 +57,7 @@ static int current_check_access_socket(struct socket *const sock,
 	};
 	const struct landlock_cred_security *const subject =
 		landlock_get_applicable_subject(current_cred(), masks, NULL);
+	struct lsm_network_audit audit_net = {};
 
 	if (!subject)
 		return 0;
@@ -68,18 +71,48 @@ static int current_check_access_socket(struct socket *const sock,
 
 	switch (address->sa_family) {
 	case AF_UNSPEC:
-	case AF_INET:
+	case AF_INET: {
+		const struct sockaddr_in *addr4;
+
 		if (addrlen < sizeof(struct sockaddr_in))
 			return -EINVAL;
-		port = ((struct sockaddr_in *)address)->sin_port;
+
+		addr4 = (struct sockaddr_in *)address;
+		port = addr4->sin_port;
+
+		if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) {
+			audit_net.dport = port;
+			audit_net.v4info.daddr = addr4->sin_addr.s_addr;
+		} else if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
+			audit_net.sport = port;
+			audit_net.v4info.saddr = addr4->sin_addr.s_addr;
+		} else {
+			WARN_ON_ONCE(1);
+		}
 		break;
+	}
 
 #if IS_ENABLED(CONFIG_IPV6)
-	case AF_INET6:
+	case AF_INET6: {
+		const struct sockaddr_in6 *addr6;
+
 		if (addrlen < SIN6_LEN_RFC2133)
 			return -EINVAL;
-		port = ((struct sockaddr_in6 *)address)->sin6_port;
+
+		addr6 = (struct sockaddr_in6 *)address;
+		port = addr6->sin6_port;
+
+		if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) {
+			audit_net.dport = port;
+			audit_net.v6info.daddr = addr6->sin6_addr;
+		} else if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
+			audit_net.sport = port;
+			audit_net.v6info.saddr = addr6->sin6_addr;
+		} else {
+			WARN_ON_ONCE(1);
+		}
 		break;
+	}
 #endif /* IS_ENABLED(CONFIG_IPV6) */
 
 	default:
@@ -149,6 +182,16 @@ static int current_check_access_socket(struct socket *const sock,
 				   ARRAY_SIZE(layer_masks)))
 		return 0;
 
+	audit_net.family = address->sa_family;
+	landlock_log_denial(subject,
+			    &(struct landlock_request){
+				    .type = LANDLOCK_REQUEST_NET_ACCESS,
+				    .audit.type = LSM_AUDIT_DATA_NET,
+				    .audit.u.net = &audit_net,
+				    .access = access_request,
+				    .layer_masks = &layer_masks,
+				    .layer_masks_size = ARRAY_SIZE(layer_masks),
+			    });
 	return -EACCES;
 }
 
-- 
2.49.0

[PATCH v7 16/28] landlock: Log scoped denials

[Mickaël Salaün]

Add audit support for unix_stream_connect, unix_may_send, task_kill, and
file_send_sigiotask hooks.

The related blockers are:
- scope.abstract_unix_socket
- scope.signal

Audit event sample for abstract unix socket:

  type=LANDLOCK_DENY msg=audit(1729738800.268:30): domain=195ba459b blockers=scope.abstract_unix_socket path=00666F6F

Audit event sample for signal:

  type=LANDLOCK_DENY msg=audit(1729738800.291:31): domain=195ba459b blockers=scope.signal opid=1 ocomm="systemd"

Refactor and simplify error handling in LSM hooks.

Extend struct landlock_file_security with fown_layer and use it to log
the blocking domain.  The struct aligned size is still 16 bytes.

Cc: Günther Noack <gnoack@google.com>
Cc: Tahera Fahimi <fahimitahera@gmail.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Fix missing ifdef CONFIG_AUDIT for fown_layer, spotted by kernel test
  robot.
- Update headers.

Changes since v5:
- Move request declarations in the landlock_log_denial() calls to
  not impact allowed requests with audit, and return as soon as
  possible when access is allowed.
- Store a fown_layer per file and use it to log the blocking domain.
- Refactor and simplify error handling in LSM hooks.

Changes since v4:
- Rebase on top of the landlock_log_denial() and subject type changes.

Changes since v3:
- Cosmetic change to the "scope.*" blocker names.
- Extend commit message.

Changes since v1:
- New patch.
---
 security/landlock/audit.c |  8 ++++
 security/landlock/audit.h |  2 +
 security/landlock/fs.c    |  8 +++-
 security/landlock/fs.h    | 16 ++++++++
 security/landlock/task.c  | 84 +++++++++++++++++++++++++++++++--------
 5 files changed, 99 insertions(+), 19 deletions(-)

diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index 66ff9a5d9866..2dcc55ad451c 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -70,6 +70,14 @@ get_blocker(const enum landlock_request_type type,
 		if (WARN_ON_ONCE(access_bit >= ARRAY_SIZE(net_access_strings)))
 			return "unknown";
 		return net_access_strings[access_bit];
+
+	case LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET:
+		WARN_ON_ONCE(access_bit != -1);
+		return "scope.abstract_unix_socket";
+
+	case LANDLOCK_REQUEST_SCOPE_SIGNAL:
+		WARN_ON_ONCE(access_bit != -1);
+		return "scope.signal";
 	}
 
 	WARN_ON_ONCE(1);
diff --git a/security/landlock/audit.h b/security/landlock/audit.h
index 486b4e7050d3..92428b7fc4d8 100644
--- a/security/landlock/audit.h
+++ b/security/landlock/audit.h
@@ -19,6 +19,8 @@ enum landlock_request_type {
 	LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY,
 	LANDLOCK_REQUEST_FS_ACCESS,
 	LANDLOCK_REQUEST_NET_ACCESS,
+	LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET,
+	LANDLOCK_REQUEST_SCOPE_SIGNAL,
 };
 
 /*
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 9d7443ff67c7..36d06a8e2287 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1774,6 +1774,7 @@ static void hook_file_set_fowner(struct file *file)
 	struct landlock_ruleset *prev_dom;
 	struct task_struct *p;
 	struct landlock_cred_security fown_subject = {};
+	size_t fown_layer = 0;
 
 	/*
 	 * Lock already held by __f_setown(), see commit 26f204380a3c ("fs: Fix
@@ -1791,8 +1792,8 @@ static void hook_file_set_fowner(struct file *file)
 			.scope = LANDLOCK_SCOPE_SIGNAL,
 		};
 		const struct landlock_cred_security *new_subject =
-			landlock_get_applicable_subject(current_cred(),
-							signal_scope, NULL);
+			landlock_get_applicable_subject(
+				current_cred(), signal_scope, &fown_layer);
 		if (new_subject) {
 			landlock_get_ruleset(new_subject->domain);
 			fown_subject = *new_subject;
@@ -1801,6 +1802,9 @@ static void hook_file_set_fowner(struct file *file)
 
 	prev_dom = landlock_file(file)->fown_subject.domain;
 	landlock_file(file)->fown_subject = fown_subject;
+#ifdef CONFIG_AUDIT
+	landlock_file(file)->fown_layer = fown_layer;
+#endif /* CONFIG_AUDIT*/
 
 	/* Called in an RCU read-side critical section. */
 	landlock_put_ruleset_deferred(prev_dom);
diff --git a/security/landlock/fs.h b/security/landlock/fs.h
index 3a09ba985b74..294ca813c7f2 100644
--- a/security/landlock/fs.h
+++ b/security/landlock/fs.h
@@ -9,6 +9,7 @@
 #ifndef _SECURITY_LANDLOCK_FS_H
 #define _SECURITY_LANDLOCK_FS_H
 
+#include <linux/build_bug.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/rcupdate.h>
@@ -61,6 +62,11 @@ struct landlock_file_security {
 	 * _LANDLOCK_ACCESS_FS_OPTIONAL).
 	 */
 	deny_masks_t deny_masks;
+	/**
+	 * @fown_layer: Layer level of @fown_subject->domain with
+	 * LANDLOCK_SCOPE_SIGNAL.
+	 */
+	u8 fown_layer;
 #endif /* CONFIG_AUDIT */
 
 	/**
@@ -73,6 +79,16 @@ struct landlock_file_security {
 	struct landlock_cred_security fown_subject;
 };
 
+#ifdef CONFIG_AUDIT
+
+/* Makes sure all layers can be identified. */
+/* clang-format off */
+static_assert((typeof_member(struct landlock_file_security, fown_layer))~0 >=
+	      LANDLOCK_MAX_NUM_LAYERS);
+/* clang-format off */
+
+#endif /* CONFIG_AUDIT */
+
 /**
  * struct landlock_superblock_security - Superblock security blob
  *
diff --git a/security/landlock/task.c b/security/landlock/task.c
index 60e2953d2c71..e95e4ebe724d 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Landlock LSM - Ptrace hooks
+ * Landlock - Ptrace hooks
  *
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2019-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #include <asm/current.h>
@@ -265,26 +266,41 @@ static int hook_unix_stream_connect(struct sock *const sock,
 				    struct sock *const other,
 				    struct sock *const newsk)
 {
+	size_t handle_layer;
 	const struct landlock_cred_security *const subject =
 		landlock_get_applicable_subject(current_cred(), unix_scope,
-						NULL);
+						&handle_layer);
 
 	/* Quick return for non-landlocked tasks. */
 	if (!subject)
 		return 0;
 
-	if (is_abstract_socket(other) && sock_is_scoped(other, subject->domain))
-		return -EPERM;
+	if (!is_abstract_socket(other))
+		return 0;
+
+	if (!sock_is_scoped(other, subject->domain))
+		return 0;
 
-	return 0;
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET,
+		.audit = {
+			.type = LSM_AUDIT_DATA_NET,
+			.u.net = &(struct lsm_network_audit) {
+				.sk = other,
+			},
+		},
+		.layer_plus_one = handle_layer + 1,
+	});
+	return -EPERM;
 }
 
 static int hook_unix_may_send(struct socket *const sock,
 			      struct socket *const other)
 {
+	size_t handle_layer;
 	const struct landlock_cred_security *const subject =
 		landlock_get_applicable_subject(current_cred(), unix_scope,
-						NULL);
+						&handle_layer);
 
 	if (!subject)
 		return 0;
@@ -296,11 +312,23 @@ static int hook_unix_may_send(struct socket *const sock,
 	if (unix_peer(sock->sk) == other->sk)
 		return 0;
 
-	if (is_abstract_socket(other->sk) &&
-	    sock_is_scoped(other->sk, subject->domain))
-		return -EPERM;
+	if (!is_abstract_socket(other->sk))
+		return 0;
+
+	if (!sock_is_scoped(other->sk, subject->domain))
+		return 0;
 
-	return 0;
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET,
+		.audit = {
+			.type = LSM_AUDIT_DATA_NET,
+			.u.net = &(struct lsm_network_audit) {
+				.sk = other->sk,
+			},
+		},
+		.layer_plus_one = handle_layer + 1,
+	});
+	return -EPERM;
 }
 
 static const struct access_masks signal_scope = {
@@ -312,6 +340,7 @@ static int hook_task_kill(struct task_struct *const p,
 			  const struct cred *cred)
 {
 	bool is_scoped;
+	size_t handle_layer;
 	const struct landlock_cred_security *subject;
 
 	if (!cred) {
@@ -330,7 +359,8 @@ static int hook_task_kill(struct task_struct *const p,
 		cred = current_cred();
 	}
 
-	subject = landlock_get_applicable_subject(cred, signal_scope, NULL);
+	subject = landlock_get_applicable_subject(cred, signal_scope,
+						  &handle_layer);
 
 	/* Quick return for non-landlocked tasks. */
 	if (!subject)
@@ -342,10 +372,19 @@ static int hook_task_kill(struct task_struct *const p,
 					     landlock_get_task_domain(p),
 					     signal_scope.scope);
 	}
-	if (is_scoped)
-		return -EPERM;
 
-	return 0;
+	if (!is_scoped)
+		return 0;
+
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_SCOPE_SIGNAL,
+		.audit = {
+			.type = LSM_AUDIT_DATA_TASK,
+			.u.tsk = p,
+		},
+		.layer_plus_one = handle_layer + 1,
+	});
+	return -EPERM;
 }
 
 static int hook_file_send_sigiotask(struct task_struct *tsk,
@@ -374,10 +413,21 @@ static int hook_file_send_sigiotask(struct task_struct *tsk,
 					     landlock_get_task_domain(tsk),
 					     signal_scope.scope);
 	}
-	if (is_scoped)
-		return -EPERM;
 
-	return 0;
+	if (!is_scoped)
+		return 0;
+
+	landlock_log_denial(subject, &(struct landlock_request) {
+		.type = LANDLOCK_REQUEST_SCOPE_SIGNAL,
+		.audit = {
+			.type = LSM_AUDIT_DATA_TASK,
+			.u.tsk = tsk,
+		},
+#ifdef CONFIG_AUDIT
+		.layer_plus_one = landlock_file(fown->file)->fown_layer + 1,
+#endif /* CONFIG_AUDIT */
+	});
+	return -EPERM;
 }
 
 static struct security_hook_list landlock_hooks[] __ro_after_init = {
-- 
2.49.0

[PATCH v7 17/28] landlock: Add LANDLOCK_RESTRICT_SELF_LOG_*_EXEC_* flags

[Mickaël Salaün]

Most of the time we want to log denied access because they should not
happen and such information helps diagnose issues.  However, when
sandboxing processes that we know will try to access denied resources
(e.g. unknown, bogus, or malicious binary), we might want to not log
related access requests that might fill up logs.

By default, denied requests are logged until the task call execve(2).

If the LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF flag is set, denied
requests will not be logged for the same executed file.

If the LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON flag is set, denied
requests from after an execve(2) call will be logged.

The rationale is that a program should know its own behavior, but not
necessarily the behavior of other programs.

Because LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF is set for a specific
Landlock domain, it makes it possible to selectively mask some access
requests that would be logged by a parent domain, which might be handy
for unprivileged processes to limit logs.  However, system
administrators should still use the audit filtering mechanism.  There is
intentionally no audit nor sysctl configuration to re-enable these logs.
This is delegated to the user space program.

Increment the Landlock ABI version to reflect this interface change.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Replace the LANDLOCK_ABI_VERSION value with the new
  landlock_abi_version variable.
- Update headers.

Changes since v5:
- Rename LANDLOCK_RESTRICT_SELF_QUIET to
  LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF, and adjust
  landlock_log_denial() accordingly.  This better reflects what is the
  impact of this flag, especially wrt the following
  LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON, and makes both flags
  compatible and complementary.
- Rename LANDLOCK_RESTRICT_SELF_LOG_CROSS_EXEC to
  LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON to be more consistent with
  other flags.
- Change flag values.
- Squash the LOG_SAME_EXEC_OFF and the LOG_NEW_EXEC_ON patches to get
  a more consistent patch.

Changes since v4:
- Rebase on top of the scoped guard patches.

Changes since v3:
- Rename LANDLOCK_RESTRICT_SELF_LOGLESS to LANDLOCK_RESTRICT_SELF_QUIET.
  "quiet" is already used by kernel's cmdline to disable most log
  messages, so this name makes sense for Landlock.
- Improve the LANDLOCK_ABI_VERSION comment.

Changes since v2:
- Update ABI version test.
---
 include/uapi/linux/landlock.h                | 21 +++++++++++
 security/landlock/audit.c                    | 16 ++++++--
 security/landlock/domain.c                   |  2 +
 security/landlock/domain.h                   | 11 ++++++
 security/landlock/limits.h                   |  7 +++-
 security/landlock/syscalls.c                 | 39 ++++++++++++++++----
 tools/testing/selftests/landlock/base_test.c |  2 +-
 7 files changed, 85 insertions(+), 13 deletions(-)

diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 8806a132d7b8..56b0094ef792 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -4,6 +4,7 @@
  *
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #ifndef _UAPI_LINUX_LANDLOCK_H
@@ -64,6 +65,26 @@ struct landlock_ruleset_attr {
 #define LANDLOCK_CREATE_RULESET_ERRATA			(1U << 1)
 /* clang-format on */
 
+/*
+ * sys_landlock_restrict_self() flags:
+ *
+ * - %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF: Do not create any log related to the
+ *   enforced restrictions.  This should only be set by tools launching unknown
+ *   or untrusted programs (e.g. a sandbox tool, container runtime, system
+ *   service manager).  Because programs sandboxing themselves should fix any
+ *   denied access, they should not set this flag to be aware of potential
+ *   issues reported by system's logs (i.e. audit).
+ * - %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON: Explicitly ask to continue
+ *   logging denied access requests even after an :manpage:`execve(2)` call.
+ *   This flag should only be set if all the programs than can legitimately be
+ *   executed will not try to request a denied access (which could spam audit
+ *   logs).
+ */
+/* clang-format off */
+#define LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF		(1U << 0)
+#define LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON			(1U << 1)
+/* clang-format on */
+
 /**
  * enum landlock_rule_type - Landlock rule type
  *
diff --git a/security/landlock/audit.c b/security/landlock/audit.c
index 2dcc55ad451c..7ababc314236 100644
--- a/security/landlock/audit.c
+++ b/security/landlock/audit.c
@@ -422,6 +422,9 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 			get_hierarchy(subject->domain, youngest_layer);
 	}
 
+	if (READ_ONCE(youngest_denied->log_status) == LANDLOCK_LOG_DISABLED)
+		return;
+
 	/*
 	 * Consistently keeps track of the number of denied access requests
 	 * even if audit is currently disabled, or if audit rules currently
@@ -433,9 +436,16 @@ void landlock_log_denial(const struct landlock_cred_security *const subject,
 	if (!audit_enabled)
 		return;
 
-	/* Ignores denials after an execution. */
-	if (!(subject->domain_exec & (1 << youngest_layer)))
-		return;
+	/* Checks if the current exec was restricting itself. */
+	if (subject->domain_exec & (1 << youngest_layer)) {
+		/* Ignores denials for the same execution. */
+		if (!youngest_denied->log_same_exec)
+			return;
+	} else {
+		/* Ignores denials after a new execution. */
+		if (!youngest_denied->log_cross_exec)
+			return;
+	}
 
 	/* Uses consistent allocation flags wrt common_lsm_audit(). */
 	ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
diff --git a/security/landlock/domain.c b/security/landlock/domain.c
index f61fa5ae8e56..9a601fcbe1e2 100644
--- a/security/landlock/domain.c
+++ b/security/landlock/domain.c
@@ -127,6 +127,8 @@ int landlock_init_hierarchy_log(struct landlock_hierarchy *const hierarchy)
 	hierarchy->details = details;
 	hierarchy->id = landlock_get_id_range(1);
 	hierarchy->log_status = LANDLOCK_LOG_PENDING;
+	hierarchy->log_same_exec = true;
+	hierarchy->log_cross_exec = false;
 	atomic64_set(&hierarchy->num_denials, 0);
 	return 0;
 }
diff --git a/security/landlock/domain.h b/security/landlock/domain.h
index 96642dd87b33..57d4f8e41c97 100644
--- a/security/landlock/domain.h
+++ b/security/landlock/domain.h
@@ -24,6 +24,7 @@
 enum landlock_log_status {
 	LANDLOCK_LOG_PENDING = 0,
 	LANDLOCK_LOG_RECORDED,
+	LANDLOCK_LOG_DISABLED,
 };
 
 /**
@@ -103,6 +104,16 @@ struct landlock_hierarchy {
 	 * @details: Information about the related domain.
 	 */
 	const struct landlock_details *details;
+	/**
+	 * @log_same_exec: Set if the domain is *not* configured with
+	 * %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF.  Set to true by default.
+	 */
+	u32 log_same_exec : 1,
+		/**
+		 * @log_cross_exec: Set if the domain is configured with
+		 * %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON.  Set to false by default.
+		 */
+		log_cross_exec : 1;
 #endif /* CONFIG_AUDIT */
 };
 
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index 15f7606066c8..404e880cccf9 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -1,9 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Landlock LSM - Limits for different components
+ * Landlock - Limits for different components
  *
  * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #ifndef _SECURITY_LANDLOCK_LIMITS_H
@@ -29,6 +30,10 @@
 #define LANDLOCK_LAST_SCOPE		LANDLOCK_SCOPE_SIGNAL
 #define LANDLOCK_MASK_SCOPE		((LANDLOCK_LAST_SCOPE << 1) - 1)
 #define LANDLOCK_NUM_SCOPE		__const_hweight64(LANDLOCK_MASK_SCOPE)
+
+#define LANDLOCK_LAST_RESTRICT_SELF	LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
+#define LANDLOCK_MASK_RESTRICT_SELF	((LANDLOCK_LAST_RESTRICT_SELF << 1) - 1)
+
 /* clang-format on */
 
 #endif /* _SECURITY_LANDLOCK_LIMITS_H */
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index b7b268f43a3b..5c49a6ef14e4 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -1,9 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Landlock LSM - System call implementations and user space interfaces
+ * Landlock - System call implementations and user space interfaces
  *
  * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #include <asm/current.h>
@@ -28,6 +29,7 @@
 #include <uapi/linux/landlock.h>
 
 #include "cred.h"
+#include "domain.h"
 #include "fs.h"
 #include "limits.h"
 #include "net.h"
@@ -151,7 +153,14 @@ static const struct file_operations ruleset_fops = {
 	.write = fop_dummy_write,
 };
 
-#define LANDLOCK_ABI_VERSION 6
+/*
+ * The Landlock ABI version should be incremented for each new Landlock-related
+ * user space visible change (e.g. Landlock syscalls).  This version should
+ * only be incremented once per Linux release, and the date in
+ * Documentation/userspace-api/landlock.rst should be updated to reflect the
+ * UAPI change.
+ */
+const int landlock_abi_version = 7;
 
 /**
  * sys_landlock_create_ruleset - Create a new ruleset
@@ -247,8 +256,6 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
 	return ruleset_fd;
 }
 
-const int landlock_abi_version = LANDLOCK_ABI_VERSION;
-
 /*
  * Returns an owned ruleset from a FD. It is thus needed to call
  * landlock_put_ruleset() on the return value.
@@ -443,7 +450,10 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  * sys_landlock_restrict_self - Enforce a ruleset on the calling thread
  *
  * @ruleset_fd: File descriptor tied to the ruleset to merge with the target.
- * @flags: Must be 0.
+ * @flags: Supported values:
+ *
+ * - %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF
+ * - %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
  *
  * This system call enables to enforce a Landlock ruleset on the current
  * thread.  Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
@@ -453,7 +463,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
- * - %EINVAL: @flags is not 0.
+ * - %EINVAL: @flags contains an unknown bit.
  * - %EBADF: @ruleset_fd is not a file descriptor for the current thread;
  * - %EBADFD: @ruleset_fd is not a ruleset file descriptor;
  * - %EPERM: @ruleset_fd has no read access to the underlying ruleset, or the
@@ -469,6 +479,7 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 		*ruleset __free(landlock_put_ruleset) = NULL;
 	struct cred *new_cred;
 	struct landlock_cred_security *new_llcred;
+	bool log_same_exec, log_cross_exec;
 
 	if (!is_initialized())
 		return -EOPNOTSUPP;
@@ -481,10 +492,15 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	    !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
-	/* No flag for now. */
-	if (flags)
+	if ((flags | LANDLOCK_MASK_RESTRICT_SELF) !=
+	    LANDLOCK_MASK_RESTRICT_SELF)
 		return -EINVAL;
 
+	/* Translates "off" flag to boolean. */
+	log_same_exec = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF);
+	/* Translates "on" flag to boolean. */
+	log_cross_exec = !!(flags & LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON);
+
 	/* Gets and checks the ruleset. */
 	ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
 	if (IS_ERR(ruleset))
@@ -507,6 +523,13 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 		return PTR_ERR(new_dom);
 	}
 
+#ifdef CONFIG_AUDIT
+	new_dom->hierarchy->log_same_exec = log_same_exec;
+	new_dom->hierarchy->log_cross_exec = log_cross_exec;
+	if (!log_same_exec && !log_cross_exec)
+		new_dom->hierarchy->log_status = LANDLOCK_LOG_DISABLED;
+#endif /* CONFIG_AUDIT */
+
 	/* Replaces the old (prepared) domain. */
 	landlock_put_ruleset(new_llcred->domain);
 	new_llcred->domain = new_dom;
diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index c0abadd0bbbe..7dc431a0e18e 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -76,7 +76,7 @@ TEST(abi_version)
 	const struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
 	};
-	ASSERT_EQ(6, landlock_create_ruleset(NULL, 0,
+	ASSERT_EQ(7, landlock_create_ruleset(NULL, 0,
 					     LANDLOCK_CREATE_RULESET_VERSION));
 
 	ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0,
-- 
2.49.0

[PATCH v7 18/28] landlock: Add LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF

[Mickaël Salaün]

Add LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF for the case of sandboxer
tools, init systems, or runtime containers launching programs sandboxing
themselves in an inconsistent way.  Setting this flag should only
depends on runtime configuration (i.e. not hardcoded).

We don't create a new ruleset's option because this should not be part
of the security policy: only the task that enforces the policy (not the
one that create it) knows if itself or its children may request denied
actions.

This is the first and only flag that can be set without actually
restricting the caller (i.e. without providing a ruleset).

Extend struct landlock_cred_security with a u8 log_subdomains_off.
struct landlock_file_security is still 16 bytes.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Closes: https://github.com/landlock-lsm/linux/issues/3
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Rename LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS to
  LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF.  As for
  LANDLOCK_RESTRICT_SELF_LOG_OFF, this makes more sense.
- Store the log_subdomains bit in landlock_cred instead of
  landlock_hirerarchy because it is not directly related to the current
  domain.
- Make it possible to set this flag without actually restricting the
  calling task, and update the related documentation.

Changes since v4:
- New patch.
---
 include/uapi/linux/landlock.h | 12 ++++++++++
 security/landlock/cred.h      |  7 ++++++
 security/landlock/limits.h    |  2 +-
 security/landlock/syscalls.c  | 41 ++++++++++++++++++++++++++++++-----
 4 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 56b0094ef792..d9d0cb827117 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -79,10 +79,22 @@ struct landlock_ruleset_attr {
  *   This flag should only be set if all the programs than can legitimately be
  *   executed will not try to request a denied access (which could spam audit
  *   logs).
+ * - %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF: Do not create any log related
+ *   to the enforced restrictions coming from future nested domains created by
+ *   the caller or its descendants.  This should only be set according to a
+ *   runtime configuration (i.e. not hardcoded) by programs launching other
+ *   unknown or untrusted programs that may create their own Landlock domains
+ *   and spam logs.  The main use case is for container runtimes to enable users
+ *   to mute buggy sandboxed programs for a specific container image.  Other use
+ *   cases include sandboxer tools and init systems.  Unlike
+ *   %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
+ *   %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF does not impact the requested
+ *   restriction (if any) but only the future nested domains.
  */
 /* clang-format off */
 #define LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF		(1U << 0)
 #define LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON			(1U << 1)
+#define LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF		(1U << 2)
 /* clang-format on */
 
 /**
diff --git a/security/landlock/cred.h b/security/landlock/cred.h
index 3bf18551d7b8..c82fe63ec598 100644
--- a/security/landlock/cred.h
+++ b/security/landlock/cred.h
@@ -40,6 +40,13 @@ struct landlock_cred_security {
 	 * landlock_restrict_self(2)).
 	 */
 	u16 domain_exec;
+	/**
+	 * @log_subdomains_off: Set if the domain descendants's log_status should be
+	 * set to %LANDLOCK_LOG_DISABLED.  This is not a landlock_hierarchy
+	 * configuration because it applies to future descendant domains and it does
+	 * not require a current domain.
+	 */
+	u8 log_subdomains_off : 1;
 #endif /* CONFIG_AUDIT */
 } __packed;
 
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index 404e880cccf9..65b5ff051674 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -31,7 +31,7 @@
 #define LANDLOCK_MASK_SCOPE		((LANDLOCK_LAST_SCOPE << 1) - 1)
 #define LANDLOCK_NUM_SCOPE		__const_hweight64(LANDLOCK_MASK_SCOPE)
 
-#define LANDLOCK_LAST_RESTRICT_SELF	LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
+#define LANDLOCK_LAST_RESTRICT_SELF	LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
 #define LANDLOCK_MASK_RESTRICT_SELF	((LANDLOCK_LAST_RESTRICT_SELF << 1) - 1)
 
 /* clang-format on */
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 5c49a6ef14e4..74d5cc2963b7 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -454,12 +454,16 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  *
  * - %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF
  * - %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
+ * - %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
  *
  * This system call enables to enforce a Landlock ruleset on the current
  * thread.  Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
  * namespace or is running with no_new_privs.  This avoids scenarios where
  * unprivileged tasks can affect the behavior of privileged children.
  *
+ * It is allowed to only pass the %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
+ * flag with a @ruleset_fd value of -1.
+ *
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
@@ -479,7 +483,8 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 		*ruleset __free(landlock_put_ruleset) = NULL;
 	struct cred *new_cred;
 	struct landlock_cred_security *new_llcred;
-	bool log_same_exec, log_cross_exec;
+	bool log_same_exec, log_cross_exec, log_subdomains,
+		__maybe_unused prev_log_subdomains;
 
 	if (!is_initialized())
 		return -EOPNOTSUPP;
@@ -500,11 +505,20 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	log_same_exec = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF);
 	/* Translates "on" flag to boolean. */
 	log_cross_exec = !!(flags & LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON);
+	/* Translates "off" flag to boolean. */
+	log_subdomains = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF);
 
-	/* Gets and checks the ruleset. */
-	ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
-	if (IS_ERR(ruleset))
-		return PTR_ERR(ruleset);
+	/*
+	 * It is allowed to set %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF with -1
+	 * as @ruleset_fd, but no other flag must be set.
+	 */
+	if (!(ruleset_fd == -1 &&
+	      flags == LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
+		/* Gets and checks the ruleset. */
+		ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
+		if (IS_ERR(ruleset))
+			return PTR_ERR(ruleset);
+	}
 
 	/* Prepares new credentials. */
 	new_cred = prepare_creds();
@@ -513,6 +527,21 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 
 	new_llcred = landlock_cred(new_cred);
 
+#ifdef CONFIG_AUDIT
+	prev_log_subdomains = !new_llcred->log_subdomains_off;
+	new_llcred->log_subdomains_off = !prev_log_subdomains ||
+					 !log_subdomains;
+#endif /* CONFIG_AUDIT */
+
+	/*
+	 * The only case when a ruleset may not be set is if
+	 * LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF is set and ruleset_fd is -1.
+	 * We could optimize this case by not calling commit_creds() if this flag
+	 * was already set, but it is not worth the complexity.
+	 */
+	if (!ruleset)
+		return commit_creds(new_cred);
+
 	/*
 	 * There is no possible race condition while copying and manipulating
 	 * the current credentials because they are dedicated per thread.
@@ -526,7 +555,7 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 #ifdef CONFIG_AUDIT
 	new_dom->hierarchy->log_same_exec = log_same_exec;
 	new_dom->hierarchy->log_cross_exec = log_cross_exec;
-	if (!log_same_exec && !log_cross_exec)
+	if ((!log_same_exec && !log_cross_exec) || !prev_log_subdomains)
 		new_dom->hierarchy->log_status = LANDLOCK_LOG_DISABLED;
 #endif /* CONFIG_AUDIT */
 
-- 
2.49.0

[PATCH v7 19/28] samples/landlock: Enable users to log sandbox denials

[Mickaël Salaün]

By default, denials from within the sandbox are not logged.  Indeed, the
sandboxer's security policy might not be fitted to the set of sandboxed
processes that could be spawned (e.g. from a shell).

For test purpose, parse the LL_FORCE_LOG environment variable to log
every sandbox denials, including after launching the initial sandboxed
program thanks to LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Update with new flag.

Changes since v3:
- Extend error message, suggested by Francis Laniel.

Changes since v2:
- New patch.
---
 samples/landlock/sandboxer.c | 37 +++++++++++++++++++++++++++++++++---
 security/landlock/syscalls.c |  8 ++------
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index 07fab2ef534e..4e2854c6f9a3 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -58,6 +58,7 @@ static inline int landlock_restrict_self(const int ruleset_fd,
 #define ENV_TCP_BIND_NAME "LL_TCP_BIND"
 #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT"
 #define ENV_SCOPED_NAME "LL_SCOPED"
+#define ENV_FORCE_LOG_NAME "LL_FORCE_LOG"
 #define ENV_DELIMITER ":"
 
 static int str2num(const char *numstr, __u64 *num_dst)
@@ -295,7 +296,7 @@ static bool check_ruleset_scope(const char *const env_var,
 
 /* clang-format on */
 
-#define LANDLOCK_ABI_LAST 6
+#define LANDLOCK_ABI_LAST 7
 
 #define XSTR(s) #s
 #define STR(s) XSTR(s)
@@ -322,6 +323,9 @@ static const char help[] =
 	"  - \"a\" to restrict opening abstract unix sockets\n"
 	"  - \"s\" to restrict sending signals\n"
 	"\n"
+	"A sandboxer should not log denied access requests to avoid spamming logs, "
+	"but to test audit we can set " ENV_FORCE_LOG_NAME "=1\n"
+	"\n"
 	"Example:\n"
 	ENV_FS_RO_NAME "=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
 	ENV_FS_RW_NAME "=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
@@ -340,7 +344,7 @@ int main(const int argc, char *const argv[], char *const *const envp)
 	const char *cmd_path;
 	char *const *cmd_argv;
 	int ruleset_fd, abi;
-	char *env_port_name;
+	char *env_port_name, *env_force_log;
 	__u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ,
 	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE;
 
@@ -351,6 +355,8 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		.scoped = LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET |
 			  LANDLOCK_SCOPE_SIGNAL,
 	};
+	int supported_restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON;
+	int set_restrict_flags = 0;
 
 	if (argc < 2) {
 		fprintf(stderr, help, argv[0]);
@@ -422,6 +428,13 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		/* Removes LANDLOCK_SCOPE_* for ABI < 6 */
 		ruleset_attr.scoped &= ~(LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET |
 					 LANDLOCK_SCOPE_SIGNAL);
+		__attribute__((fallthrough));
+	case 6:
+		/* Removes LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON for ABI < 7 */
+		supported_restrict_flags &=
+			~LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON;
+
+		/* Must be printed for any ABI < LANDLOCK_ABI_LAST. */
 		fprintf(stderr,
 			"Hint: You should update the running kernel "
 			"to leverage Landlock features "
@@ -456,6 +469,24 @@ int main(const int argc, char *const argv[], char *const *const envp)
 	if (check_ruleset_scope(ENV_SCOPED_NAME, &ruleset_attr))
 		return 1;
 
+	/* Enables optional logs. */
+	env_force_log = getenv(ENV_FORCE_LOG_NAME);
+	if (env_force_log) {
+		if (strcmp(env_force_log, "1") != 0) {
+			fprintf(stderr, "Unknown value for " ENV_FORCE_LOG_NAME
+					" (only \"1\" is handled)\n");
+			return 1;
+		}
+		if (!(supported_restrict_flags &
+		      LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON)) {
+			fprintf(stderr,
+				"Audit logs not supported by current kernel\n");
+			return 1;
+		}
+		set_restrict_flags |= LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON;
+		unsetenv(ENV_FORCE_LOG_NAME);
+	}
+
 	ruleset_fd =
 		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
 	if (ruleset_fd < 0) {
@@ -483,7 +514,7 @@ int main(const int argc, char *const argv[], char *const *const envp)
 		perror("Failed to restrict privileges");
 		goto err_close_ruleset;
 	}
-	if (landlock_restrict_self(ruleset_fd, 0)) {
+	if (landlock_restrict_self(ruleset_fd, set_restrict_flags)) {
 		perror("Failed to enforce ruleset");
 		goto err_close_ruleset;
 	}
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 74d5cc2963b7..49ad633db54e 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -508,12 +508,8 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	/* Translates "off" flag to boolean. */
 	log_subdomains = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF);
 
-	/*
-	 * It is allowed to set %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF with -1
-	 * as @ruleset_fd, but no other flag must be set.
-	 */
-	if (!(ruleset_fd == -1 &&
-	      flags == LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
+	if (!(flags == LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF &&
+	      ruleset_fd == -1)) {
 		/* Gets and checks the ruleset. */
 		ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
 		if (IS_ERR(ruleset))
-- 
2.49.0

[PATCH v7 20/28] selftests/landlock: Add test for invalid ruleset file descriptor

[Mickaël Salaün]

To align with fs_test's layout1.inval and layout0.proc_nsfs which test
EBADFD for landlock_add_rule(2), create a new base_test's
restrict_self_fd which test EBADFD for landlock_restrict_self(2).

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- New standalone patch (that can be backported).
---
 tools/testing/selftests/landlock/base_test.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index 7dc431a0e18e..cb13416533d2 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -269,6 +269,17 @@ TEST(restrict_self_checks_ordering)
 	ASSERT_EQ(0, close(ruleset_fd));
 }
 
+TEST(restrict_self_fd)
+{
+	int fd;
+
+	fd = open("/dev/null", O_RDONLY | O_CLOEXEC);
+	ASSERT_LE(0, fd);
+
+	EXPECT_EQ(-1, landlock_restrict_self(fd, 0));
+	EXPECT_EQ(EBADFD, errno);
+}
+
 TEST(ruleset_fd_io)
 {
 	struct landlock_ruleset_attr ruleset_attr = {
-- 
2.49.0

[PATCH v7 21/28] selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags

[Mickaël Salaün]

Add the base_test's restrict_self_fd_flags tests to align with previous
restrict_self_fd tests but with the new
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF flag.

Add the restrict_self_flags tests to check that
LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON, and
LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF are valid but not the next
bit.  Some checks are similar to restrict_self_checks_ordering's ones.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v5:
- Rename restrict flags.
- Update LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF test to pass with -1
  as ruleset FD, and flag ordering.
- Add restrict_self_fd_flags tests.

Changes since v4:
- Update with LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS, and
  LANDLOCK_RESTRICT_SELF_LOG_CROSS_EXEC.

Changes since v3:
- Use a last_flag variable.

Changes since v2:
- New patch.
---
 tools/testing/selftests/landlock/base_test.c | 71 ++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index cb13416533d2..c75ac925b912 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -280,6 +280,77 @@ TEST(restrict_self_fd)
 	EXPECT_EQ(EBADFD, errno);
 }
 
+TEST(restrict_self_fd_flags)
+{
+	int fd;
+
+	fd = open("/dev/null", O_RDONLY | O_CLOEXEC);
+	ASSERT_LE(0, fd);
+
+	/*
+	 * LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF accepts -1 but not any file
+	 * descriptor.
+	 */
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      fd, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADFD, errno);
+}
+
+TEST(restrict_self_flags)
+{
+	const __u32 last_flag = LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF;
+
+	/* Tests invalid flag combinations. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, last_flag << 1));
+	EXPECT_EQ(EINVAL, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, -1));
+	EXPECT_EQ(EINVAL, errno);
+
+	/* Tests valid flag combinations. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(-1, 0));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -1, LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1,
+			  LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF |
+				  LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1,
+			  LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON |
+				  LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -1, LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(-1,
+		  landlock_restrict_self(
+			  -1, LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF |
+				      LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON));
+	EXPECT_EQ(EBADF, errno);
+
+	/* Tests with an invalid ruleset_fd. */
+
+	EXPECT_EQ(-1, landlock_restrict_self(
+			      -2, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+	EXPECT_EQ(EBADF, errno);
+
+	EXPECT_EQ(0, landlock_restrict_self(
+			     -1, LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF));
+}
+
 TEST(ruleset_fd_io)
 {
 	struct landlock_ruleset_attr ruleset_attr = {
-- 
2.49.0

[PATCH v7 22/28] selftests/landlock: Add tests for audit flags and domain IDs

[Mickaël Salaün]

Add audit_test.c to check with and without LANDLOCK_RESTRICT_SELF_*
flags against the two Landlock audit record types:
AUDIT_LANDLOCK_ACCESS and AUDIT_LANDLOCK_DOMAIN.

Check consistency of domain IDs per layer in AUDIT_LANDLOCK_ACCESS and
AUDIT_LANDLOCK_DOMAIN messages: denied access, domain allocation, and
domain deallocation.

These tests use signal scoping to make it simple.  They are not in the
scoped_signal_test.c file but in the new dedicated audit_test.c file.

Tests are run with audit filters to ensure the audit records come from
the test program.  Moreover, because there can only be one audit
process, tests would failed if run in parallel.  Because of audit
limitations, tests can only be run in the initial namespace.

The audit test helpers were inspired by libaudit and
tools/testing/selftests/net/netfilter/audit_logread.c

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Phil Sutter <phil@nwl.cc>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Fix the race condition on some systems when checking the asynchronous
  domain deallacation event.
- Update audit_count_records() to check for audit errors.
- Add audit.layers tests to check consistency of domain IDs per layer.
- Move and simplify the domain allocated and deallocated helpers to
  audit.h
- Add missing include.

Changes since v5:
- Enhance audit_match_record() with an __u64 *domain_id argument set
  according to the audit logs.
- Rename audit_fork.flags to audit_flags.signal .
- Rename variants according to new flags.
- Check consistency of domain IDs.

Changes since v4:
- Update with the new landlock_restrict_self()'s flags, the new audit
  rule types, and message fields.
- Simplify audit_filter_exe() and audit_init_filter_exe().
- Test with kill() instead of umount().
- Test domain deallocation events.

Changes since v3:
- Improve audit_request() to check Netlink errors and handle multiple
  replies.
- Make audit_filter_exe() more generic to handle several audit rule
  lists.
- Merge audit_init_state() into audit_init() and create
  audit_init_with_exe_filter() to handle AUDIT_EXE_LANDLOCK_DENY with an
  arbitrary path.
- Add matches_log_dom_info().

Changes since v2:
- New patch.
---
 tools/testing/selftests/landlock/audit.h      | 437 ++++++++++++++++++
 tools/testing/selftests/landlock/audit_test.c | 332 +++++++++++++
 tools/testing/selftests/landlock/common.h     |   2 +
 tools/testing/selftests/landlock/config       |   1 +
 4 files changed, 772 insertions(+)
 create mode 100644 tools/testing/selftests/landlock/audit.h
 create mode 100644 tools/testing/selftests/landlock/audit_test.c

diff --git a/tools/testing/selftests/landlock/audit.h b/tools/testing/selftests/landlock/audit.h
new file mode 100644
index 000000000000..08a5c53bd6f5
--- /dev/null
+++ b/tools/testing/selftests/landlock/audit.h
@@ -0,0 +1,437 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Landlock audit helpers
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/audit.h>
+#include <linux/limits.h>
+#include <linux/netlink.h>
+#include <regex.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#endif
+
+#ifndef __maybe_unused
+#define __maybe_unused __attribute__((__unused__))
+#endif
+
+#define REGEX_LANDLOCK_PREFIX "^audit([0-9.:]\\+): domain=\\([0-9a-f]\\+\\)"
+
+struct audit_filter {
+	__u32 record_type;
+	size_t exe_len;
+	char exe[PATH_MAX];
+};
+
+struct audit_message {
+	struct nlmsghdr header;
+	union {
+		struct audit_status status;
+		struct audit_features features;
+		struct audit_rule_data rule;
+		struct nlmsgerr err;
+		char data[PATH_MAX + 200];
+	};
+};
+
+static const struct timeval audit_tv_dom_drop = {
+	/*
+	 * Because domain deallocation is tied to asynchronous credential
+	 * freeing, receiving such event may take some time.  In practice,
+	 * on a small VM, it should not exceed 100k usec, but let's wait up
+	 * to 1 second to be safe.
+	 */
+	.tv_sec = 1,
+};
+
+static const struct timeval audit_tv_default = {
+	.tv_usec = 1,
+};
+
+static int audit_send(const int fd, const struct audit_message *const msg)
+{
+	struct sockaddr_nl addr = {
+		.nl_family = AF_NETLINK,
+	};
+	int ret;
+
+	do {
+		ret = sendto(fd, msg, msg->header.nlmsg_len, 0,
+			     (struct sockaddr *)&addr, sizeof(addr));
+	} while (ret < 0 && errno == EINTR);
+
+	if (ret < 0)
+		return -errno;
+
+	if (ret != msg->header.nlmsg_len)
+		return -E2BIG;
+
+	return 0;
+}
+
+static int audit_recv(const int fd, struct audit_message *msg)
+{
+	struct sockaddr_nl addr;
+	socklen_t addrlen = sizeof(addr);
+	struct audit_message msg_tmp;
+	int err;
+
+	if (!msg)
+		msg = &msg_tmp;
+
+	do {
+		err = recvfrom(fd, msg, sizeof(*msg), 0,
+			       (struct sockaddr *)&addr, &addrlen);
+	} while (err < 0 && errno == EINTR);
+
+	if (err < 0)
+		return -errno;
+
+	if (addrlen != sizeof(addr) || addr.nl_pid != 0)
+		return -EINVAL;
+
+	/* Checks Netlink error or end of messages. */
+	if (msg->header.nlmsg_type == NLMSG_ERROR)
+		return msg->err.error;
+
+	return 0;
+}
+
+static int audit_request(const int fd,
+			 const struct audit_message *const request,
+			 struct audit_message *reply)
+{
+	struct audit_message msg_tmp;
+	bool first_reply = true;
+	int err;
+
+	err = audit_send(fd, request);
+	if (err)
+		return err;
+
+	if (!reply)
+		reply = &msg_tmp;
+
+	do {
+		if (first_reply)
+			first_reply = false;
+		else
+			reply = &msg_tmp;
+
+		err = audit_recv(fd, reply);
+		if (err)
+			return err;
+	} while (reply->header.nlmsg_type != NLMSG_ERROR &&
+		 reply->err.msg.nlmsg_type != request->header.nlmsg_type);
+
+	return reply->err.error;
+}
+
+static int audit_filter_exe(const int audit_fd,
+			    const struct audit_filter *const filter,
+			    const __u16 type)
+{
+	struct audit_message msg = {
+		.header = {
+			.nlmsg_len = NLMSG_SPACE(sizeof(msg.rule)) +
+				     NLMSG_ALIGN(filter->exe_len),
+			.nlmsg_type = type,
+			.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
+		},
+		.rule = {
+			.flags = AUDIT_FILTER_EXCLUDE,
+			.action = AUDIT_NEVER,
+			.field_count = 1,
+			.fields[0] = filter->record_type,
+			.fieldflags[0] = AUDIT_NOT_EQUAL,
+			.values[0] = filter->exe_len,
+			.buflen = filter->exe_len,
+		}
+	};
+
+	if (filter->record_type != AUDIT_EXE)
+		return -EINVAL;
+
+	memcpy(msg.rule.buf, filter->exe, filter->exe_len);
+	return audit_request(audit_fd, &msg, NULL);
+}
+
+static int audit_filter_drop(const int audit_fd, const __u16 type)
+{
+	struct audit_message msg = {
+		.header = {
+			.nlmsg_len = NLMSG_SPACE(sizeof(msg.rule)),
+			.nlmsg_type = type,
+			.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
+		},
+		.rule = {
+			.flags = AUDIT_FILTER_EXCLUDE,
+			.action = AUDIT_NEVER,
+			.field_count = 1,
+			.fields[0] = AUDIT_MSGTYPE,
+			.fieldflags[0] = AUDIT_NOT_EQUAL,
+			.values[0] = AUDIT_LANDLOCK_DOMAIN,
+		}
+	};
+
+	return audit_request(audit_fd, &msg, NULL);
+}
+
+static int audit_set_status(int fd, __u32 key, __u32 val)
+{
+	const struct audit_message msg = {
+		.header = {
+			.nlmsg_len = NLMSG_SPACE(sizeof(msg.status)),
+			.nlmsg_type = AUDIT_SET,
+			.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
+		},
+		.status = {
+			.mask = key,
+			.enabled = key == AUDIT_STATUS_ENABLED ? val : 0,
+			.pid = key == AUDIT_STATUS_PID ? val : 0,
+		}
+	};
+
+	return audit_request(fd, &msg, NULL);
+}
+
+/*
+ * @domain_id: The domain ID extracted from the audit message (if the first part
+ * of @pattern is REGEX_LANDLOCK_PREFIX).  It is set to 0 if the domain ID is
+ * not found.
+ */
+static int audit_match_record(int audit_fd, const __u16 type,
+			      const char *const pattern, __u64 *domain_id)
+{
+	struct audit_message msg;
+	int ret, err = 0;
+	bool matches_record = !type;
+	regmatch_t matches[2];
+	regex_t regex;
+
+	ret = regcomp(&regex, pattern, 0);
+	if (ret)
+		return -EINVAL;
+
+	do {
+		memset(&msg, 0, sizeof(msg));
+		err = audit_recv(audit_fd, &msg);
+		if (err)
+			goto out;
+
+		if (msg.header.nlmsg_type == type)
+			matches_record = true;
+	} while (!matches_record);
+
+	ret = regexec(&regex, msg.data, ARRAY_SIZE(matches), matches, 0);
+	if (ret) {
+		printf("DATA: %s\n", msg.data);
+		printf("ERROR: no match for pattern: %s\n", pattern);
+		err = -ENOENT;
+	}
+
+	if (domain_id) {
+		*domain_id = 0;
+		if (matches[1].rm_so != -1) {
+			int match_len = matches[1].rm_eo - matches[1].rm_so;
+			/* The maximal characters of a 2^64 hexadecimal number is 17. */
+			char dom_id[18];
+
+			if (match_len > 0 && match_len < sizeof(dom_id)) {
+				memcpy(dom_id, msg.data + matches[1].rm_so,
+				       match_len);
+				dom_id[match_len] = '\0';
+				if (domain_id)
+					*domain_id = strtoull(dom_id, NULL, 16);
+			}
+		}
+	}
+
+out:
+	regfree(&regex);
+	return err;
+}
+
+static int __maybe_unused matches_log_domain_allocated(int audit_fd,
+						       __u64 *domain_id)
+{
+	return audit_match_record(
+		audit_fd, AUDIT_LANDLOCK_DOMAIN,
+		REGEX_LANDLOCK_PREFIX
+		" status=allocated mode=enforcing pid=[0-9]\\+ uid=[0-9]\\+"
+		" exe=\"[^\"]\\+\" comm=\".*_test\"$",
+		domain_id);
+}
+
+static int __maybe_unused matches_log_domain_deallocated(
+	int audit_fd, unsigned int num_denials, __u64 *domain_id)
+{
+	static const char log_template[] = REGEX_LANDLOCK_PREFIX
+		" status=deallocated denials=%u$";
+	char log_match[sizeof(log_template) + 10];
+	int log_match_len;
+
+	log_match_len = snprintf(log_match, sizeof(log_match), log_template,
+				 num_denials);
+	if (log_match_len > sizeof(log_match))
+		return -E2BIG;
+
+	return audit_match_record(audit_fd, AUDIT_LANDLOCK_DOMAIN, log_match,
+				  domain_id);
+}
+
+struct audit_records {
+	size_t access;
+	size_t domain;
+};
+
+static int audit_count_records(int audit_fd, struct audit_records *records)
+{
+	struct audit_message msg;
+	int err;
+
+	records->access = 0;
+	records->domain = 0;
+
+	do {
+		memset(&msg, 0, sizeof(msg));
+		err = audit_recv(audit_fd, &msg);
+		if (err) {
+			if (err == -EAGAIN)
+				return 0;
+			else
+				return err;
+		}
+
+		switch (msg.header.nlmsg_type) {
+		case AUDIT_LANDLOCK_ACCESS:
+			records->access++;
+			break;
+		case AUDIT_LANDLOCK_DOMAIN:
+			records->domain++;
+			break;
+		}
+	} while (true);
+
+	return 0;
+}
+
+static int audit_init(void)
+{
+	int fd, err;
+
+	fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_AUDIT);
+	if (fd < 0)
+		return -errno;
+
+	err = audit_set_status(fd, AUDIT_STATUS_ENABLED, 1);
+	if (err)
+		return err;
+
+	err = audit_set_status(fd, AUDIT_STATUS_PID, getpid());
+	if (err)
+		return err;
+
+	/* Sets a timeout for negative tests. */
+	err = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &audit_tv_default,
+			 sizeof(audit_tv_default));
+	if (err)
+		return -errno;
+
+	return fd;
+}
+
+static int audit_init_filter_exe(struct audit_filter *filter, const char *path)
+{
+	char *absolute_path = NULL;
+
+	/* It is assume that there is not already filtering rules. */
+	filter->record_type = AUDIT_EXE;
+	if (!path) {
+		filter->exe_len = readlink("/proc/self/exe", filter->exe,
+					   sizeof(filter->exe) - 1);
+		if (filter->exe_len < 0)
+			return -errno;
+
+		return 0;
+	}
+
+	absolute_path = realpath(path, NULL);
+	if (!absolute_path)
+		return -errno;
+
+	/* No need for the terminating NULL byte. */
+	filter->exe_len = strlen(absolute_path);
+	if (filter->exe_len > sizeof(filter->exe))
+		return -E2BIG;
+
+	memcpy(filter->exe, absolute_path, filter->exe_len);
+	free(absolute_path);
+	return 0;
+}
+
+static int audit_cleanup(int audit_fd, struct audit_filter *filter)
+{
+	struct audit_filter new_filter;
+
+	if (audit_fd < 0 || !filter) {
+		int err;
+
+		/*
+		 * Simulates audit_init_with_exe_filter() when called from
+		 * FIXTURE_TEARDOWN_PARENT().
+		 */
+		audit_fd = audit_init();
+		if (audit_fd < 0)
+			return audit_fd;
+
+		filter = &new_filter;
+		err = audit_init_filter_exe(filter, NULL);
+		if (err)
+			return err;
+	}
+
+	/* Filters might not be in place. */
+	audit_filter_exe(audit_fd, filter, AUDIT_DEL_RULE);
+	audit_filter_drop(audit_fd, AUDIT_DEL_RULE);
+
+	/*
+	 * Because audit_cleanup() might not be called by the test auditd
+	 * process, it might not be possible to explicitly set it.  Anyway,
+	 * AUDIT_STATUS_ENABLED will implicitly be set to 0 when the auditd
+	 * process will exit.
+	 */
+	return close(audit_fd);
+}
+
+static int audit_init_with_exe_filter(struct audit_filter *filter)
+{
+	int fd, err;
+
+	fd = audit_init();
+	if (fd < 0)
+		return fd;
+
+	err = audit_init_filter_exe(filter, NULL);
+	if (err)
+		return err;
+
+	err = audit_filter_exe(fd, filter, AUDIT_ADD_RULE);
+	if (err)
+		return err;
+
+	return fd;
+}
diff --git a/tools/testing/selftests/landlock/audit_test.c b/tools/testing/selftests/landlock/audit_test.c
new file mode 100644
index 000000000000..59764dc18ecb
--- /dev/null
+++ b/tools/testing/selftests/landlock/audit_test.c
@@ -0,0 +1,332 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock tests - Audit
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/landlock.h>
+#include <sys/mount.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "audit.h"
+#include "common.h"
+
+static int matches_log_signal(struct __test_metadata *const _metadata,
+			      int audit_fd, const pid_t opid, __u64 *domain_id)
+{
+	static const char log_template[] = REGEX_LANDLOCK_PREFIX
+		" blockers=scope\\.signal opid=%d ocomm=\"audit_test\"$";
+	char log_match[sizeof(log_template) + 10];
+	int log_match_len;
+
+	log_match_len =
+		snprintf(log_match, sizeof(log_match), log_template, opid);
+	if (log_match_len > sizeof(log_match))
+		return -E2BIG;
+
+	return audit_match_record(audit_fd, AUDIT_LANDLOCK_ACCESS, log_match,
+				  domain_id);
+}
+
+FIXTURE(audit)
+{
+	struct audit_filter audit_filter;
+	int audit_fd;
+	__u64(*domain_stack)[16];
+};
+
+FIXTURE_SETUP(audit)
+{
+	disable_caps(_metadata);
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd)
+	{
+		const char *error_msg;
+
+		/* kill "$(auditctl -s | sed -ne 's/^pid \([0-9]\+\)$/\1/p')" */
+		if (self->audit_fd == -EEXIST)
+			error_msg = "socket already in use (e.g. auditd)";
+		else
+			error_msg = strerror(-self->audit_fd);
+		TH_LOG("Failed to initialize audit: %s", error_msg);
+	}
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+
+	self->domain_stack = mmap(NULL, sizeof(*self->domain_stack),
+				  PROT_READ | PROT_WRITE,
+				  MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(MAP_FAILED, self->domain_stack);
+	memset(self->domain_stack, 0, sizeof(*self->domain_stack));
+}
+
+FIXTURE_TEARDOWN(audit)
+{
+	EXPECT_EQ(0, munmap(self->domain_stack, sizeof(*self->domain_stack)));
+
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	EXPECT_EQ(0, audit_cleanup(self->audit_fd, &self->audit_filter));
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+}
+
+TEST_F(audit, layers)
+{
+	const struct landlock_ruleset_attr ruleset_attr = {
+		.scoped = LANDLOCK_SCOPE_SIGNAL,
+	};
+	int status, ruleset_fd, i;
+	__u64 prev_dom = 3;
+	pid_t child;
+
+	ruleset_fd =
+		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+	ASSERT_LE(0, ruleset_fd);
+	EXPECT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		for (i = 0; i < ARRAY_SIZE(*self->domain_stack); i++) {
+			__u64 denial_dom = 1;
+			__u64 allocated_dom = 2;
+
+			EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, 0));
+
+			/* Creates a denial to get the domain ID. */
+			EXPECT_EQ(-1, kill(getppid(), 0));
+			EXPECT_EQ(EPERM, errno);
+			EXPECT_EQ(0,
+				  matches_log_signal(_metadata, self->audit_fd,
+						     getppid(), &denial_dom));
+			EXPECT_EQ(0, matches_log_domain_allocated(
+					     self->audit_fd, &allocated_dom));
+			EXPECT_NE(denial_dom, 1);
+			EXPECT_NE(denial_dom, 0);
+			EXPECT_EQ(denial_dom, allocated_dom);
+
+			/* Checks that the new domain is younger than the previous one. */
+			EXPECT_GT(allocated_dom, prev_dom);
+			prev_dom = allocated_dom;
+			(*self->domain_stack)[i] = allocated_dom;
+		}
+
+		/* Checks that we reached the maximum number of layers. */
+		EXPECT_EQ(-1, landlock_restrict_self(ruleset_fd, 0));
+		EXPECT_EQ(E2BIG, errno);
+
+		/* Updates filter rules to match the drop record. */
+		set_cap(_metadata, CAP_AUDIT_CONTROL);
+		EXPECT_EQ(0, audit_filter_drop(self->audit_fd, AUDIT_ADD_RULE));
+		EXPECT_EQ(0,
+			  audit_filter_exe(self->audit_fd, &self->audit_filter,
+					   AUDIT_DEL_RULE));
+		clear_cap(_metadata, CAP_AUDIT_CONTROL);
+
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	if (WIFSIGNALED(status) || !WIFEXITED(status) ||
+	    WEXITSTATUS(status) != EXIT_SUCCESS)
+		_metadata->exit_code = KSFT_FAIL;
+
+	/* Purges log from deallocated domains. */
+	EXPECT_EQ(0, setsockopt(self->audit_fd, SOL_SOCKET, SO_RCVTIMEO,
+				&audit_tv_dom_drop, sizeof(audit_tv_dom_drop)));
+	for (i = ARRAY_SIZE(*self->domain_stack) - 1; i >= 0; i--) {
+		__u64 deallocated_dom = 2;
+
+		EXPECT_EQ(0, matches_log_domain_deallocated(self->audit_fd, 1,
+							    &deallocated_dom));
+		EXPECT_EQ((*self->domain_stack)[i], deallocated_dom)
+		{
+			TH_LOG("Failed to match domain %llx (#%d)",
+			       (*self->domain_stack)[i], i);
+		}
+	}
+	EXPECT_EQ(0, setsockopt(self->audit_fd, SOL_SOCKET, SO_RCVTIMEO,
+				&audit_tv_default, sizeof(audit_tv_default)));
+
+	EXPECT_EQ(0, close(ruleset_fd));
+}
+
+FIXTURE(audit_flags)
+{
+	struct audit_filter audit_filter;
+	int audit_fd;
+	__u64 *domain_id;
+};
+
+FIXTURE_VARIANT(audit_flags)
+{
+	const int restrict_flags;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_flags, default) {
+	/* clang-format on */
+	.restrict_flags = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_flags, same_exec_off) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_flags, subdomains_off) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_flags, cross_exec_on) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON,
+};
+
+FIXTURE_SETUP(audit_flags)
+{
+	disable_caps(_metadata);
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd)
+	{
+		const char *error_msg;
+
+		/* kill "$(auditctl -s | sed -ne 's/^pid \([0-9]\+\)$/\1/p')" */
+		if (self->audit_fd == -EEXIST)
+			error_msg = "socket already in use (e.g. auditd)";
+		else
+			error_msg = strerror(-self->audit_fd);
+		TH_LOG("Failed to initialize audit: %s", error_msg);
+	}
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+
+	self->domain_id = mmap(NULL, sizeof(*self->domain_id),
+			       PROT_READ | PROT_WRITE,
+			       MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(MAP_FAILED, self->domain_id);
+	/* Domain IDs are greater or equal to 2^32. */
+	*self->domain_id = 1;
+}
+
+FIXTURE_TEARDOWN(audit_flags)
+{
+	EXPECT_EQ(0, munmap(self->domain_id, sizeof(*self->domain_id)));
+
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	EXPECT_EQ(0, audit_cleanup(self->audit_fd, &self->audit_filter));
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+}
+
+TEST_F(audit_flags, signal)
+{
+	int status;
+	pid_t child;
+	struct audit_records records;
+	__u64 deallocated_dom = 2;
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		const struct landlock_ruleset_attr ruleset_attr = {
+			.scoped = LANDLOCK_SCOPE_SIGNAL,
+		};
+		int ruleset_fd;
+
+		/* Add filesystem restrictions. */
+		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
+						     sizeof(ruleset_attr), 0);
+		ASSERT_LE(0, ruleset_fd);
+		EXPECT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
+		ASSERT_EQ(0, landlock_restrict_self(ruleset_fd,
+						    variant->restrict_flags));
+		EXPECT_EQ(0, close(ruleset_fd));
+
+		/* First signal checks to test log entries. */
+		EXPECT_EQ(-1, kill(getppid(), 0));
+		EXPECT_EQ(EPERM, errno);
+
+		if (variant->restrict_flags &
+		    LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF) {
+			EXPECT_EQ(-EAGAIN, matches_log_signal(
+						   _metadata, self->audit_fd,
+						   getppid(), self->domain_id));
+			EXPECT_EQ(*self->domain_id, 1);
+		} else {
+			__u64 allocated_dom = 3;
+
+			EXPECT_EQ(0, matches_log_signal(
+					     _metadata, self->audit_fd,
+					     getppid(), self->domain_id));
+
+			/* Checks domain information records. */
+			EXPECT_EQ(0, matches_log_domain_allocated(
+					     self->audit_fd, &allocated_dom));
+			EXPECT_NE(*self->domain_id, 1);
+			EXPECT_NE(*self->domain_id, 0);
+			EXPECT_EQ(*self->domain_id, allocated_dom);
+		}
+
+		/* Second signal checks to test audit_count_records(). */
+		EXPECT_EQ(-1, kill(getppid(), 0));
+		EXPECT_EQ(EPERM, errno);
+
+		/* Makes sure there is no superfluous logged records. */
+		EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+		if (variant->restrict_flags &
+		    LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF) {
+			EXPECT_EQ(0, records.access);
+		} else {
+			EXPECT_EQ(1, records.access);
+		}
+		EXPECT_EQ(0, records.domain);
+
+		/* Updates filter rules to match the drop record. */
+		set_cap(_metadata, CAP_AUDIT_CONTROL);
+		EXPECT_EQ(0, audit_filter_drop(self->audit_fd, AUDIT_ADD_RULE));
+		EXPECT_EQ(0,
+			  audit_filter_exe(self->audit_fd, &self->audit_filter,
+					   AUDIT_DEL_RULE));
+		clear_cap(_metadata, CAP_AUDIT_CONTROL);
+
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	if (WIFSIGNALED(status) || !WIFEXITED(status) ||
+	    WEXITSTATUS(status) != EXIT_SUCCESS)
+		_metadata->exit_code = KSFT_FAIL;
+
+	if (variant->restrict_flags &
+	    LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF) {
+		EXPECT_EQ(-EAGAIN,
+			  matches_log_domain_deallocated(self->audit_fd, 0,
+							 &deallocated_dom));
+		EXPECT_EQ(deallocated_dom, 2);
+	} else {
+		EXPECT_EQ(0, setsockopt(self->audit_fd, SOL_SOCKET, SO_RCVTIMEO,
+					&audit_tv_dom_drop,
+					sizeof(audit_tv_dom_drop)));
+		EXPECT_EQ(0, matches_log_domain_deallocated(self->audit_fd, 2,
+							    &deallocated_dom));
+		EXPECT_NE(deallocated_dom, 2);
+		EXPECT_NE(deallocated_dom, 0);
+		EXPECT_EQ(deallocated_dom, *self->domain_id);
+		EXPECT_EQ(0, setsockopt(self->audit_fd, SOL_SOCKET, SO_RCVTIMEO,
+					&audit_tv_default,
+					sizeof(audit_tv_default)));
+	}
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h
index 076a9a625c98..54b6f80fc697 100644
--- a/tools/testing/selftests/landlock/common.h
+++ b/tools/testing/selftests/landlock/common.h
@@ -11,6 +11,7 @@
 #include <errno.h>
 #include <linux/securebits.h>
 #include <sys/capability.h>
+#include <sys/prctl.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <sys/wait.h>
@@ -37,6 +38,7 @@ static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 	/* Only these three capabilities are useful for the tests. */
 	const cap_value_t caps[] = {
 		/* clang-format off */
+		CAP_AUDIT_CONTROL,
 		CAP_DAC_OVERRIDE,
 		CAP_MKNOD,
 		CAP_NET_ADMIN,
diff --git a/tools/testing/selftests/landlock/config b/tools/testing/selftests/landlock/config
index 425de4c20271..8fe9b461b1fd 100644
--- a/tools/testing/selftests/landlock/config
+++ b/tools/testing/selftests/landlock/config
@@ -1,4 +1,5 @@
 CONFIG_AF_UNIX_OOB=y
+CONFIG_AUDIT=y
 CONFIG_CGROUPS=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_INET=y
-- 
2.49.0

[PATCH v7 23/28] selftests/landlock: Test audit with restrict flags

[Mickaël Salaün]

Add audit_exec tests to filter Landlock denials according to
cross-execution or muted subdomains.

Add a wait-pipe-sandbox.c test program to sandbox itself and send a
(denied) signals to its parent.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Check audit_count_records() calls for audit errors.
- Simplify matches_log_fs_read_root().
- Update .gitignore

Changes since v5:
- Rename audit_exec.flags to audit_exec.signal_and_open .

Changes since v4:
- Revamp to test the Landlock syscall flags instead of the audit rules.
- Copy wait-pipe.c to wait-pipe-sandbox.c and extend it.
- Fix regex.

Changes since v3:
- New patch.
---
 tools/testing/selftests/landlock/.gitignore   |   1 +
 tools/testing/selftests/landlock/Makefile     |   6 +-
 tools/testing/selftests/landlock/audit_test.c | 219 ++++++++++++++++++
 tools/testing/selftests/landlock/common.h     |   1 +
 .../selftests/landlock/wait-pipe-sandbox.c    | 131 +++++++++++
 5 files changed, 357 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/landlock/wait-pipe-sandbox.c

diff --git a/tools/testing/selftests/landlock/.gitignore b/tools/testing/selftests/landlock/.gitignore
index 335b2b1a3463..a820329cae0d 100644
--- a/tools/testing/selftests/landlock/.gitignore
+++ b/tools/testing/selftests/landlock/.gitignore
@@ -2,3 +2,4 @@
 /sandbox-and-launch
 /true
 /wait-pipe
+/wait-pipe-sandbox
diff --git a/tools/testing/selftests/landlock/Makefile b/tools/testing/selftests/landlock/Makefile
index 5cb0828f0514..a3f449914bf9 100644
--- a/tools/testing/selftests/landlock/Makefile
+++ b/tools/testing/selftests/landlock/Makefile
@@ -10,7 +10,11 @@ src_test := $(wildcard *_test.c)
 
 TEST_GEN_PROGS := $(src_test:.c=)
 
-TEST_GEN_PROGS_EXTENDED := true sandbox-and-launch wait-pipe
+TEST_GEN_PROGS_EXTENDED := \
+	true \
+	sandbox-and-launch \
+	wait-pipe \
+	wait-pipe-sandbox
 
 # Short targets:
 $(TEST_GEN_PROGS): LDLIBS += -lcap -lpthread
diff --git a/tools/testing/selftests/landlock/audit_test.c b/tools/testing/selftests/landlock/audit_test.c
index 59764dc18ecb..a0643070c403 100644
--- a/tools/testing/selftests/landlock/audit_test.c
+++ b/tools/testing/selftests/landlock/audit_test.c
@@ -7,7 +7,9 @@
 
 #define _GNU_SOURCE
 #include <errno.h>
+#include <limits.h>
 #include <linux/landlock.h>
+#include <stdlib.h>
 #include <sys/mount.h>
 #include <sys/prctl.h>
 #include <sys/types.h>
@@ -329,4 +331,221 @@ TEST_F(audit_flags, signal)
 	}
 }
 
+static int matches_log_fs_read_root(int audit_fd)
+{
+	return audit_match_record(
+		audit_fd, AUDIT_LANDLOCK_ACCESS,
+		REGEX_LANDLOCK_PREFIX
+		" blockers=fs\\.read_dir path=\"/\" dev=\"[^\"]\\+\" ino=[0-9]\\+$",
+		NULL);
+}
+
+FIXTURE(audit_exec)
+{
+	struct audit_filter audit_filter;
+	int audit_fd;
+};
+
+FIXTURE_VARIANT(audit_exec)
+{
+	const int restrict_flags;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_exec, default) {
+	/* clang-format on */
+	.restrict_flags = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_exec, same_exec_off) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_exec, subdomains_off) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_exec, cross_exec_on) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit_exec, subdomains_off_and_cross_exec_on) {
+	/* clang-format on */
+	.restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF |
+			  LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON,
+};
+
+FIXTURE_SETUP(audit_exec)
+{
+	disable_caps(_metadata);
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+
+	self->audit_fd = audit_init();
+	EXPECT_LE(0, self->audit_fd)
+	{
+		const char *error_msg;
+
+		/* kill "$(auditctl -s | sed -ne 's/^pid \([0-9]\+\)$/\1/p')" */
+		if (self->audit_fd == -EEXIST)
+			error_msg = "socket already in use (e.g. auditd)";
+		else
+			error_msg = strerror(-self->audit_fd);
+		TH_LOG("Failed to initialize audit: %s", error_msg);
+	}
+
+	/* Applies test filter for the bin_wait_pipe_sandbox program. */
+	EXPECT_EQ(0, audit_init_filter_exe(&self->audit_filter,
+					   bin_wait_pipe_sandbox));
+	EXPECT_EQ(0, audit_filter_exe(self->audit_fd, &self->audit_filter,
+				      AUDIT_ADD_RULE));
+
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+}
+
+FIXTURE_TEARDOWN(audit_exec)
+{
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	EXPECT_EQ(0, audit_filter_exe(self->audit_fd, &self->audit_filter,
+				      AUDIT_DEL_RULE));
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+	EXPECT_EQ(0, close(self->audit_fd));
+}
+
+TEST_F(audit_exec, signal_and_open)
+{
+	struct audit_records records;
+	int pipe_child[2], pipe_parent[2];
+	char buf_parent;
+	pid_t child;
+	int status;
+
+	ASSERT_EQ(0, pipe2(pipe_child, 0));
+	ASSERT_EQ(0, pipe2(pipe_parent, 0));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		const struct landlock_ruleset_attr layer1 = {
+			.scoped = LANDLOCK_SCOPE_SIGNAL,
+		};
+		char pipe_child_str[12], pipe_parent_str[12];
+		char *const argv[] = { (char *)bin_wait_pipe_sandbox,
+				       pipe_child_str, pipe_parent_str, NULL };
+		int ruleset_fd;
+
+		/* Passes the pipe FDs to the executed binary. */
+		EXPECT_EQ(0, close(pipe_child[0]));
+		EXPECT_EQ(0, close(pipe_parent[1]));
+		snprintf(pipe_child_str, sizeof(pipe_child_str), "%d",
+			 pipe_child[1]);
+		snprintf(pipe_parent_str, sizeof(pipe_parent_str), "%d",
+			 pipe_parent[0]);
+
+		ruleset_fd =
+			landlock_create_ruleset(&layer1, sizeof(layer1), 0);
+		if (ruleset_fd < 0) {
+			perror("Failed to create a ruleset");
+			_exit(1);
+		}
+		prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+		if (landlock_restrict_self(ruleset_fd,
+					   variant->restrict_flags)) {
+			perror("Failed to restrict self");
+			_exit(1);
+		}
+		close(ruleset_fd);
+
+		ASSERT_EQ(0, execve(argv[0], argv, NULL))
+		{
+			TH_LOG("Failed to execute \"%s\": %s", argv[0],
+			       strerror(errno));
+		};
+		_exit(1);
+		return;
+	}
+
+	EXPECT_EQ(0, close(pipe_child[1]));
+	EXPECT_EQ(0, close(pipe_parent[0]));
+
+	/* Waits for the child. */
+	EXPECT_EQ(1, read(pipe_child[0], &buf_parent, 1));
+
+	/* Tests that there was no denial until now. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+
+	/*
+	 * Wait for the child to do a first denied action by layer1 and
+	 * sandbox itself with layer2.
+	 */
+	EXPECT_EQ(1, write(pipe_parent[1], ".", 1));
+	EXPECT_EQ(1, read(pipe_child[0], &buf_parent, 1));
+
+	/* Tests that the audit record only matches the child. */
+	if (variant->restrict_flags & LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON) {
+		/* Matches the current domain. */
+		EXPECT_EQ(0, matches_log_signal(_metadata, self->audit_fd,
+						getpid(), NULL));
+	}
+
+	/* Checks that we didn't miss anything. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+
+	/*
+	 * Wait for the child to do a second denied action by layer1 and
+	 * layer2, and sandbox itself with layer3.
+	 */
+	EXPECT_EQ(1, write(pipe_parent[1], ".", 1));
+	EXPECT_EQ(1, read(pipe_child[0], &buf_parent, 1));
+
+	/* Tests that the audit record only matches the child. */
+	if (variant->restrict_flags & LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON) {
+		/* Matches the current domain. */
+		EXPECT_EQ(0, matches_log_signal(_metadata, self->audit_fd,
+						getpid(), NULL));
+	}
+
+	if (!(variant->restrict_flags &
+	      LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
+		/* Matches the child domain. */
+		EXPECT_EQ(0, matches_log_fs_read_root(self->audit_fd));
+	}
+
+	/* Checks that we didn't miss anything. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+
+	/* Waits for the child to terminate. */
+	EXPECT_EQ(1, write(pipe_parent[1], ".", 1));
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	ASSERT_EQ(1, WIFEXITED(status));
+	ASSERT_EQ(0, WEXITSTATUS(status));
+
+	/* Tests that the audit record only matches the child. */
+	if (!(variant->restrict_flags &
+	      LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
+		/*
+		 * Matches the child domains, which tests that the
+		 * llcred->domain_exec bitmask is correctly updated with a new
+		 * domain.
+		 */
+		EXPECT_EQ(0, matches_log_fs_read_root(self->audit_fd));
+		EXPECT_EQ(0, matches_log_signal(_metadata, self->audit_fd,
+						getpid(), NULL));
+	}
+
+	/* Checks that we didn't miss anything. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+}
+
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h
index 54b6f80fc697..6e1d143ddfa7 100644
--- a/tools/testing/selftests/landlock/common.h
+++ b/tools/testing/selftests/landlock/common.h
@@ -31,6 +31,7 @@
 
 static const char bin_sandbox_and_launch[] = "./sandbox-and-launch";
 static const char bin_wait_pipe[] = "./wait-pipe";
+static const char bin_wait_pipe_sandbox[] = "./wait-pipe-sandbox";
 
 static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 {
diff --git a/tools/testing/selftests/landlock/wait-pipe-sandbox.c b/tools/testing/selftests/landlock/wait-pipe-sandbox.c
new file mode 100644
index 000000000000..87dbc9164430
--- /dev/null
+++ b/tools/testing/selftests/landlock/wait-pipe-sandbox.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Write in a pipe, wait, sandbox itself, test sandboxing, and wait again.
+ *
+ * Used by audit_exec.flags from audit_test.c
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <linux/landlock.h>
+#include <linux/prctl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+
+#include "wrappers.h"
+
+static int sync_with(int pipe_child, int pipe_parent)
+{
+	char buf;
+
+	/* Signals that we are waiting. */
+	if (write(pipe_child, ".", 1) != 1) {
+		perror("Failed to write to first argument");
+		return 1;
+	}
+
+	/* Waits for the parent do its test. */
+	if (read(pipe_parent, &buf, 1) != 1) {
+		perror("Failed to write to the second argument");
+		return 1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	const struct landlock_ruleset_attr layer2 = {
+		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_DIR,
+	};
+	const struct landlock_ruleset_attr layer3 = {
+		.scoped = LANDLOCK_SCOPE_SIGNAL,
+	};
+	int err, pipe_child, pipe_parent, ruleset_fd;
+
+	/* The first argument must be the file descriptor number of a pipe. */
+	if (argc != 3) {
+		fprintf(stderr, "Wrong number of arguments (not two)\n");
+		return 1;
+	}
+
+	pipe_child = atoi(argv[1]);
+	pipe_parent = atoi(argv[2]);
+	/* PR_SET_NO_NEW_PRIVS already set by parent. */
+
+	/* First step to test parent's layer1. */
+	err = sync_with(pipe_child, pipe_parent);
+	if (err)
+		return err;
+
+	/* Tries to send a signal, denied by layer1. */
+	if (!kill(getppid(), 0)) {
+		fprintf(stderr, "Successfully sent a signal to the parent");
+		return 1;
+	}
+
+	/* Second step to test parent's layer1 and our layer2. */
+	err = sync_with(pipe_child, pipe_parent);
+	if (err)
+		return err;
+
+	ruleset_fd = landlock_create_ruleset(&layer2, sizeof(layer2), 0);
+	if (ruleset_fd < 0) {
+		perror("Failed to create the layer2 ruleset");
+		return 1;
+	}
+
+	if (landlock_restrict_self(ruleset_fd, 0)) {
+		perror("Failed to restrict self");
+		return 1;
+	}
+	close(ruleset_fd);
+
+	/* Tries to send a signal, denied by layer1. */
+	if (!kill(getppid(), 0)) {
+		fprintf(stderr, "Successfully sent a signal to the parent");
+		return 1;
+	}
+
+	/* Tries to open ., denied by layer2. */
+	if (open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC) >= 0) {
+		fprintf(stderr, "Successfully opened /");
+		return 1;
+	}
+
+	/* Third step to test our layer2 and layer3. */
+	err = sync_with(pipe_child, pipe_parent);
+	if (err)
+		return err;
+
+	ruleset_fd = landlock_create_ruleset(&layer3, sizeof(layer3), 0);
+	if (ruleset_fd < 0) {
+		perror("Failed to create the layer3 ruleset");
+		return 1;
+	}
+
+	if (landlock_restrict_self(ruleset_fd, 0)) {
+		perror("Failed to restrict self");
+		return 1;
+	}
+	close(ruleset_fd);
+
+	/* Tries to open ., denied by layer2. */
+	if (open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC) >= 0) {
+		fprintf(stderr, "Successfully opened /");
+		return 1;
+	}
+
+	/* Tries to send a signal, denied by layer3. */
+	if (!kill(getppid(), 0)) {
+		fprintf(stderr, "Successfully sent a signal to the parent");
+		return 1;
+	}
+
+	return 0;
+}
-- 
2.49.0

[PATCH v7 24/28] selftests/landlock: Add audit tests for ptrace

[Mickaël Salaün]

Add tests for all ptrace actions checking "blockers=ptrace" records.

This also improves PTRACE_TRACEME and PTRACE_ATTACH tests by making sure
that the restrictions comes from Landlock, and with the expected
process.  These extended tests are like enhanced errno checks that make
sure Landlock enforcement is consistent.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Check audit_count_records() calls for audit errors.
- Update and fix PTRACE_TRACEME test to reflect kernel change.

Changes since v5:
- Move all audit tests to a new audit.trace test suite.
- Simplify tests by only checking PTRACE_TRACEME and PTRACE_ATTACH with
  one scenario.  This is preferable to not impact existing tests.
- Make sure there is no unknown Landlock audit record.

Changes since v3:
- Update test coverage.

Changes since v2:
- New patch.
---
 .../testing/selftests/landlock/ptrace_test.c  | 140 ++++++++++++++++++
 1 file changed, 140 insertions(+)

diff --git a/tools/testing/selftests/landlock/ptrace_test.c b/tools/testing/selftests/landlock/ptrace_test.c
index 8f31b673ff2d..4e356334ecb7 100644
--- a/tools/testing/selftests/landlock/ptrace_test.c
+++ b/tools/testing/selftests/landlock/ptrace_test.c
@@ -4,6 +4,7 @@
  *
  * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2019-2020 ANSSI
+ * Copyright © 2024-2025 Microsoft Corporation
  */
 
 #define _GNU_SOURCE
@@ -17,6 +18,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include "audit.h"
 #include "common.h"
 
 /* Copied from security/yama/yama_lsm.c */
@@ -434,4 +436,142 @@ TEST_F(hierarchy, trace)
 		_metadata->exit_code = KSFT_FAIL;
 }
 
+static int matches_log_ptrace(struct __test_metadata *const _metadata,
+			      int audit_fd, const pid_t opid)
+{
+	static const char log_template[] = REGEX_LANDLOCK_PREFIX
+		" blockers=ptrace opid=%d ocomm=\"ptrace_test\"$";
+	char log_match[sizeof(log_template) + 10];
+	int log_match_len;
+
+	log_match_len =
+		snprintf(log_match, sizeof(log_match), log_template, opid);
+	if (log_match_len > sizeof(log_match))
+		return -E2BIG;
+
+	return audit_match_record(audit_fd, AUDIT_LANDLOCK_ACCESS, log_match,
+				  NULL);
+}
+
+FIXTURE(audit)
+{
+	struct audit_filter audit_filter;
+	int audit_fd;
+};
+
+FIXTURE_SETUP(audit)
+{
+	disable_caps(_metadata);
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd);
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+}
+
+FIXTURE_TEARDOWN_PARENT(audit)
+{
+	EXPECT_EQ(0, audit_cleanup(-1, NULL));
+}
+
+/* Test PTRACE_TRACEME and PTRACE_ATTACH for parent and child. */
+TEST_F(audit, trace)
+{
+	pid_t child;
+	int status;
+	int pipe_child[2], pipe_parent[2];
+	int yama_ptrace_scope;
+	char buf_parent;
+	struct audit_records records;
+
+	/* Makes sure there is no superfluous logged records. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+
+	yama_ptrace_scope = get_yama_ptrace_scope();
+	ASSERT_LE(0, yama_ptrace_scope);
+
+	if (yama_ptrace_scope > YAMA_SCOPE_DISABLED)
+		TH_LOG("Incomplete tests due to Yama restrictions (scope %d)",
+		       yama_ptrace_scope);
+
+	/*
+	 * Removes all effective and permitted capabilities to not interfere
+	 * with cap_ptrace_access_check() in case of PTRACE_MODE_FSCREDS.
+	 */
+	drop_caps(_metadata);
+
+	ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
+	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		char buf_child;
+
+		ASSERT_EQ(0, close(pipe_parent[1]));
+		ASSERT_EQ(0, close(pipe_child[0]));
+
+		/* Waits for the parent to be in a domain, if any. */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
+
+		/* Tests child PTRACE_TRACEME. */
+		EXPECT_EQ(-1, ptrace(PTRACE_TRACEME));
+		EXPECT_EQ(EPERM, errno);
+		/* We should see the child process. */
+		EXPECT_EQ(0, matches_log_ptrace(_metadata, self->audit_fd,
+						getpid()));
+
+		EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+		EXPECT_EQ(0, records.access);
+		/* Checks for a domain creation. */
+		EXPECT_EQ(1, records.domain);
+
+		/*
+		 * Signals that the PTRACE_ATTACH test is done and the
+		 * PTRACE_TRACEME test is ongoing.
+		 */
+		ASSERT_EQ(1, write(pipe_child[1], ".", 1));
+
+		/* Waits for the parent PTRACE_ATTACH test. */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
+		_exit(_metadata->exit_code);
+		return;
+	}
+
+	ASSERT_EQ(0, close(pipe_child[1]));
+	ASSERT_EQ(0, close(pipe_parent[0]));
+	create_domain(_metadata);
+
+	/* Signals that the parent is in a domain. */
+	ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
+
+	/*
+	 * Waits for the child to test PTRACE_ATTACH on the parent and start
+	 * testing PTRACE_TRACEME.
+	 */
+	ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
+
+	/* The child should not be traced by the parent. */
+	EXPECT_EQ(-1, ptrace(PTRACE_DETACH, child, NULL, 0));
+	EXPECT_EQ(ESRCH, errno);
+
+	/* Tests PTRACE_ATTACH on the child. */
+	EXPECT_EQ(-1, ptrace(PTRACE_ATTACH, child, NULL, 0));
+	EXPECT_EQ(EPERM, errno);
+	EXPECT_EQ(0, matches_log_ptrace(_metadata, self->audit_fd, child));
+
+	/* Signals that the parent PTRACE_ATTACH test is done. */
+	ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	if (WIFSIGNALED(status) || !WIFEXITED(status) ||
+	    WEXITSTATUS(status) != EXIT_SUCCESS)
+		_metadata->exit_code = KSFT_FAIL;
+
+	/* Makes sure there is no superfluous logged records. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
 TEST_HARNESS_MAIN
-- 
2.49.0

[PATCH v7 25/28] selftests/landlock: Add audit tests for abstract UNIX socket scoping

[Mickaël Salaün]

Add a new scoped_audit.connect_to_child test to check the abstract UNIX
socket blocker.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Check audit_count_records() calls for audit errors.
- Simplify tests.

Changes since v5:
- New patch.
---
 .../landlock/scoped_abstract_unix_test.c      | 111 ++++++++++++++++++
 1 file changed, 111 insertions(+)

diff --git a/tools/testing/selftests/landlock/scoped_abstract_unix_test.c b/tools/testing/selftests/landlock/scoped_abstract_unix_test.c
index a6b59d2ab1b4..6825082c079c 100644
--- a/tools/testing/selftests/landlock/scoped_abstract_unix_test.c
+++ b/tools/testing/selftests/landlock/scoped_abstract_unix_test.c
@@ -20,6 +20,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include "audit.h"
 #include "common.h"
 #include "scoped_common.h"
 
@@ -267,6 +268,116 @@ TEST_F(scoped_domains, connect_to_child)
 		_metadata->exit_code = KSFT_FAIL;
 }
 
+FIXTURE(scoped_audit)
+{
+	struct service_fixture dgram_address;
+	struct audit_filter audit_filter;
+	int audit_fd;
+};
+
+FIXTURE_SETUP(scoped_audit)
+{
+	disable_caps(_metadata);
+
+	memset(&self->dgram_address, 0, sizeof(self->dgram_address));
+	set_unix_address(&self->dgram_address, 1);
+
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd);
+	drop_caps(_metadata);
+}
+
+FIXTURE_TEARDOWN_PARENT(scoped_audit)
+{
+	EXPECT_EQ(0, audit_cleanup(-1, NULL));
+}
+
+/* python -c 'print(b"\0selftests-landlock-abstract-unix-".hex().upper())' */
+#define ABSTRACT_SOCKET_PATH_PREFIX \
+	"0073656C6674657374732D6C616E646C6F636B2D61627374726163742D756E69782D"
+
+/*
+ * Simpler version of scoped_domains.connect_to_child, but with audit tests.
+ */
+TEST_F(scoped_audit, connect_to_child)
+{
+	pid_t child;
+	int err_dgram, status;
+	int pipe_child[2], pipe_parent[2];
+	char buf;
+	int dgram_client;
+	struct audit_records records;
+
+	/* Makes sure there is no superfluous logged records. */
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+
+	ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
+	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		int dgram_server;
+
+		EXPECT_EQ(0, close(pipe_parent[1]));
+		EXPECT_EQ(0, close(pipe_child[0]));
+
+		/* Waits for the parent to be in a domain. */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf, 1));
+
+		dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0);
+		ASSERT_LE(0, dgram_server);
+		ASSERT_EQ(0, bind(dgram_server, &self->dgram_address.unix_addr,
+				  self->dgram_address.unix_addr_len));
+
+		/* Signals to the parent that child is listening. */
+		ASSERT_EQ(1, write(pipe_child[1], ".", 1));
+
+		/* Waits to connect. */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf, 1));
+		EXPECT_EQ(0, close(dgram_server));
+		_exit(_metadata->exit_code);
+		return;
+	}
+	EXPECT_EQ(0, close(pipe_child[1]));
+	EXPECT_EQ(0, close(pipe_parent[0]));
+
+	create_scoped_domain(_metadata, LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET);
+
+	/* Signals that the parent is in a domain, if any. */
+	ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
+
+	dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0);
+	ASSERT_LE(0, dgram_client);
+
+	/* Waits for the child to listen */
+	ASSERT_EQ(1, read(pipe_child[0], &buf, 1));
+	err_dgram = connect(dgram_client, &self->dgram_address.unix_addr,
+			    self->dgram_address.unix_addr_len);
+	EXPECT_EQ(-1, err_dgram);
+	EXPECT_EQ(EPERM, errno);
+
+	EXPECT_EQ(
+		0,
+		audit_match_record(
+			self->audit_fd, AUDIT_LANDLOCK_ACCESS,
+			REGEX_LANDLOCK_PREFIX
+			" blockers=scope\\.abstract_unix_socket path=" ABSTRACT_SOCKET_PATH_PREFIX
+			"[0-9A-F]\\+$",
+			NULL));
+
+	ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
+	EXPECT_EQ(0, close(dgram_client));
+
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	if (WIFSIGNALED(status) || !WIFEXITED(status) ||
+	    WEXITSTATUS(status) != EXIT_SUCCESS)
+		_metadata->exit_code = KSFT_FAIL;
+}
+
 FIXTURE(scoped_vs_unscoped)
 {
 	struct service_fixture parent_stream_address, parent_dgram_address,
-- 
2.49.0

[PATCH v7 26/28] selftests/landlock: Add audit tests for filesystem

[Mickaël Salaün]

Test all filesystem blockers, including events with several records, and
record with several blockers:
- fs.execute
- fs.write_file
- fs.read_file
- fs_read_dir
- fs.remove_dir
- fs.remove_file
- fs.make_char
- fs.make_dir
- fs.make_reg
- fs.make_sock
- fs.make_fifo
- fs.make_block
- fs.make_sym
- fs.refer
- fs.truncate
- fs.ioctl_dev
- fs.change_topology

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Check audit_count_records() calls for audit errors.
- Add regression test for commit d617f0d72d80 ("landlock: Optimize file
  path walks and prepare for audit support").
- Add test_rename and test_exchange tests.
- Check domain allocation interwinded record.
- Add the execute_make test.
- Use a set of access rights instead of only one to make sure only the
  relevant access rights are blocked and logged.
- Add new audit_layout1.mount test.
- Add comments.

Changes since v5:
- New patch.
---
 tools/testing/selftests/landlock/audit.h   |  35 ++
 tools/testing/selftests/landlock/common.h  |  16 +
 tools/testing/selftests/landlock/fs_test.c | 594 +++++++++++++++++++++
 3 files changed, 645 insertions(+)

diff --git a/tools/testing/selftests/landlock/audit.h b/tools/testing/selftests/landlock/audit.h
index 08a5c53bd6f5..b9054086a0c9 100644
--- a/tools/testing/selftests/landlock/audit.h
+++ b/tools/testing/selftests/landlock/audit.h
@@ -208,6 +208,41 @@ static int audit_set_status(int fd, __u32 key, __u32 val)
 	return audit_request(fd, &msg, NULL);
 }
 
+/* Returns a pointer to the last filled character of @dst, which is `\0`.  */
+static __maybe_unused char *regex_escape(const char *const src, char *dst,
+					 size_t dst_size)
+{
+	char *d = dst;
+
+	for (const char *s = src; *s; s++) {
+		switch (*s) {
+		case '$':
+		case '*':
+		case '.':
+		case '[':
+		case '\\':
+		case ']':
+		case '^':
+			if (d >= dst + dst_size - 2)
+				return (char *)-ENOMEM;
+
+			*d++ = '\\';
+			*d++ = *s;
+			break;
+		default:
+			if (d >= dst + dst_size - 1)
+				return (char *)-ENOMEM;
+
+			*d++ = *s;
+		}
+	}
+	if (d >= dst + dst_size - 1)
+		return (char *)-ENOMEM;
+
+	*d = '\0';
+	return d;
+}
+
 /*
  * @domain_id: The domain ID extracted from the audit message (if the first part
  * of @pattern is REGEX_LANDLOCK_PREFIX).  It is set to 0 if the domain ID is
diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h
index 6e1d143ddfa7..88a3c78f5d98 100644
--- a/tools/testing/selftests/landlock/common.h
+++ b/tools/testing/selftests/landlock/common.h
@@ -208,6 +208,22 @@ enforce_ruleset(struct __test_metadata *const _metadata, const int ruleset_fd)
 	}
 }
 
+static void __maybe_unused
+drop_access_rights(struct __test_metadata *const _metadata,
+		   const struct landlock_ruleset_attr *const ruleset_attr)
+{
+	int ruleset_fd;
+
+	ruleset_fd =
+		landlock_create_ruleset(ruleset_attr, sizeof(*ruleset_attr), 0);
+	EXPECT_LE(0, ruleset_fd)
+	{
+		TH_LOG("Failed to create a ruleset: %s", strerror(errno));
+	}
+	enforce_ruleset(_metadata, ruleset_fd);
+	EXPECT_EQ(0, close(ruleset_fd));
+}
+
 struct protocol_variant {
 	int domain;
 	int type;
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index aa6f2c1cbec7..f819011a8798 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -41,6 +41,7 @@
 #define _ASM_GENERIC_FCNTL_H
 #include <linux/fcntl.h>
 
+#include "audit.h"
 #include "common.h"
 
 #ifndef renameat2
@@ -5554,4 +5555,597 @@ TEST_F_FORK(layout3_fs, release_inodes)
 	ASSERT_EQ(EACCES, test_open(TMP_DIR, O_RDONLY));
 }
 
+static int matches_log_fs_extra(struct __test_metadata *const _metadata,
+				int audit_fd, const char *const blockers,
+				const char *const path, const char *const extra)
+{
+	static const char log_template[] = REGEX_LANDLOCK_PREFIX
+		" blockers=fs\\.%s path=\"%s\" dev=\"[^\"]\\+\" ino=[0-9]\\+$";
+	char *absolute_path = NULL;
+	size_t log_match_remaining = sizeof(log_template) + strlen(blockers) +
+				     PATH_MAX * 2 +
+				     (extra ? strlen(extra) : 0) + 1;
+	char log_match[log_match_remaining];
+	char *log_match_cursor = log_match;
+	size_t chunk_len;
+
+	chunk_len = snprintf(log_match_cursor, log_match_remaining,
+			     REGEX_LANDLOCK_PREFIX " blockers=%s path=\"",
+			     blockers);
+	if (chunk_len < 0 || chunk_len >= log_match_remaining)
+		return -E2BIG;
+
+	/*
+	 * It is assume that absolute_path does not contain control characters nor
+	 * spaces, see audit_string_contains_control().
+	 */
+	absolute_path = realpath(path, NULL);
+	if (!absolute_path)
+		return -errno;
+
+	log_match_remaining -= chunk_len;
+	log_match_cursor += chunk_len;
+	log_match_cursor = regex_escape(absolute_path, log_match_cursor,
+					log_match_remaining);
+	free(absolute_path);
+	if (log_match_cursor < 0)
+		return (long long)log_match_cursor;
+
+	log_match_remaining -= log_match_cursor - log_match;
+	chunk_len = snprintf(log_match_cursor, log_match_remaining,
+			     "\" dev=\"[^\"]\\+\" ino=[0-9]\\+%s$",
+			     extra ?: "");
+	if (chunk_len < 0 || chunk_len >= log_match_remaining)
+		return -E2BIG;
+
+	return audit_match_record(audit_fd, AUDIT_LANDLOCK_ACCESS, log_match,
+				  NULL);
+}
+
+static int matches_log_fs(struct __test_metadata *const _metadata, int audit_fd,
+			  const char *const blockers, const char *const path)
+{
+	return matches_log_fs_extra(_metadata, audit_fd, blockers, path, NULL);
+}
+
+FIXTURE(audit_layout1)
+{
+	struct audit_filter audit_filter;
+	int audit_fd;
+};
+
+FIXTURE_SETUP(audit_layout1)
+{
+	prepare_layout(_metadata);
+
+	create_layout1(_metadata);
+
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd);
+	disable_caps(_metadata);
+}
+
+FIXTURE_TEARDOWN_PARENT(audit_layout1)
+{
+	remove_layout1(_metadata);
+
+	cleanup_layout(_metadata);
+
+	EXPECT_EQ(0, audit_cleanup(-1, NULL));
+}
+
+TEST_F(audit_layout1, execute_make)
+{
+	struct audit_records records;
+
+	copy_file(_metadata, bin_true, file1_s1d1);
+	test_execute(_metadata, 0, file1_s1d1);
+	test_check_exec(_metadata, 0, file1_s1d1);
+
+	drop_access_rights(_metadata,
+			   &(struct landlock_ruleset_attr){
+				   .handled_access_fs =
+					   LANDLOCK_ACCESS_FS_EXECUTE,
+			   });
+
+	test_execute(_metadata, EACCES, file1_s1d1);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.execute",
+				    file1_s1d1));
+	test_check_exec(_metadata, EACCES, file1_s1d1);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.execute",
+				    file1_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+/*
+ * Using a set of handled/denied access rights make it possible to check that
+ * only the blocked ones are logged.
+ */
+
+/* clang-format off */
+static const __u64 access_fs_16 =
+	LANDLOCK_ACCESS_FS_EXECUTE |
+	LANDLOCK_ACCESS_FS_WRITE_FILE |
+	LANDLOCK_ACCESS_FS_READ_FILE |
+	LANDLOCK_ACCESS_FS_READ_DIR |
+	LANDLOCK_ACCESS_FS_REMOVE_DIR |
+	LANDLOCK_ACCESS_FS_REMOVE_FILE |
+	LANDLOCK_ACCESS_FS_MAKE_CHAR |
+	LANDLOCK_ACCESS_FS_MAKE_DIR |
+	LANDLOCK_ACCESS_FS_MAKE_REG |
+	LANDLOCK_ACCESS_FS_MAKE_SOCK |
+	LANDLOCK_ACCESS_FS_MAKE_FIFO |
+	LANDLOCK_ACCESS_FS_MAKE_BLOCK |
+	LANDLOCK_ACCESS_FS_MAKE_SYM |
+	LANDLOCK_ACCESS_FS_REFER |
+	LANDLOCK_ACCESS_FS_TRUNCATE |
+	LANDLOCK_ACCESS_FS_IOCTL_DEV;
+/* clang-format on */
+
+TEST_F(audit_layout1, execute_read)
+{
+	struct audit_records records;
+
+	copy_file(_metadata, bin_true, file1_s1d1);
+	test_execute(_metadata, 0, file1_s1d1);
+	test_check_exec(_metadata, 0, file1_s1d1);
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	/*
+	 * The only difference with the previous audit_layout1.execute_read test is
+	 * the extra ",fs\\.read_file" blocked by the executable file.
+	 */
+	test_execute(_metadata, EACCES, file1_s1d1);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.execute,fs\\.read_file", file1_s1d1));
+	test_check_exec(_metadata, EACCES, file1_s1d1);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.execute,fs\\.read_file", file1_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+TEST_F(audit_layout1, write_file)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(EACCES, test_open(file1_s1d1, O_WRONLY));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.write_file", file1_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, read_file)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(EACCES, test_open(file1_s1d1, O_RDONLY));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.read_file",
+				    file1_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, read_dir)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(EACCES, test_open(dir_s1d1, O_DIRECTORY));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.read_dir",
+				    dir_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, remove_dir)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+	EXPECT_EQ(0, unlink(file2_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, rmdir(dir_s1d3));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_dir", dir_s1d2));
+
+	EXPECT_EQ(-1, unlinkat(AT_FDCWD, dir_s1d3, AT_REMOVEDIR));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_dir", dir_s1d2));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+TEST_F(audit_layout1, remove_file)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, unlink(file1_s1d3));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_file", dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_char)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFCHR | 0644, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_char",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_dir)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mkdir(file1_s1d3, 0755));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_dir",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_reg)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFREG | 0644, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_reg",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_sock)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFSOCK | 0644, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_sock",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_fifo)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFIFO | 0644, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_fifo",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_block)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, mknod(file1_s1d3, S_IFBLK | 0644, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.make_block", dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, make_sym)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, symlink("target", file1_s1d3));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.make_sym",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, refer_handled)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs =
+						      LANDLOCK_ACCESS_FS_REFER,
+				      });
+
+	EXPECT_EQ(-1, link(file1_s1d1, file1_s1d3));
+	EXPECT_EQ(EXDEV, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.refer",
+				    dir_s1d1));
+	EXPECT_EQ(0, matches_log_domain_allocated(self->audit_fd, NULL));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.refer",
+				    dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+TEST_F(audit_layout1, refer_make)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata,
+			   &(struct landlock_ruleset_attr){
+				   .handled_access_fs =
+					   LANDLOCK_ACCESS_FS_MAKE_REG |
+					   LANDLOCK_ACCESS_FS_REFER,
+			   });
+
+	EXPECT_EQ(-1, link(file1_s1d1, file1_s1d3));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.refer",
+				    dir_s1d1));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.make_reg,fs\\.refer", dir_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+TEST_F(audit_layout1, refer_rename)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(EACCES, test_rename(file1_s1d2, file1_s2d3));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_file,fs\\.refer", dir_s1d2));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_file,fs\\.make_reg,fs\\.refer",
+				    dir_s2d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+TEST_F(audit_layout1, refer_exchange)
+{
+	struct audit_records records;
+
+	EXPECT_EQ(0, unlink(file1_s1d3));
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	/*
+	 * The only difference with the previous audit_layout1.refer_rename test is
+	 * the extra ",fs\\.make_reg" blocked by the source directory.
+	 */
+	EXPECT_EQ(EACCES, test_exchange(file1_s1d2, file1_s2d3));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_file,fs\\.make_reg,fs\\.refer",
+				    dir_s1d2));
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.remove_file,fs\\.make_reg,fs\\.refer",
+				    dir_s2d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(0, records.domain);
+}
+
+/*
+ * This test checks that the audit record is correctly generated when the
+ * operation is only partially denied.  This is the case for rename(2) when the
+ * source file is allowed to be referenced but the destination directory is not.
+ *
+ * This is also a regression test for commit d617f0d72d80 ("landlock: Optimize
+ * file path walks and prepare for audit support") and commit 058518c20920
+ * ("landlock: Align partial refer access checks with final ones").
+ */
+TEST_F(audit_layout1, refer_rename_half)
+{
+	struct audit_records records;
+	const struct rule layer1[] = {
+		{
+			.path = dir_s2d2,
+			.access = LANDLOCK_ACCESS_FS_REFER,
+		},
+		{},
+	};
+	int ruleset_fd =
+		create_ruleset(_metadata, LANDLOCK_ACCESS_FS_REFER, layer1);
+
+	ASSERT_LE(0, ruleset_fd);
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	ASSERT_EQ(-1, rename(dir_s1d2, dir_s2d3));
+	ASSERT_EQ(EXDEV, errno);
+
+	/* Only half of the request is denied. */
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.refer",
+				    dir_s1d1));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, truncate)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata, &(struct landlock_ruleset_attr){
+					      .handled_access_fs = access_fs_16,
+				      });
+
+	EXPECT_EQ(-1, truncate(file1_s1d3, 0));
+	EXPECT_EQ(EACCES, errno);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd, "fs\\.truncate",
+				    file1_s1d3));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, ioctl_dev)
+{
+	struct audit_records records;
+	int fd;
+
+	drop_access_rights(_metadata,
+			   &(struct landlock_ruleset_attr){
+				   .handled_access_fs =
+					   access_fs_16 &
+					   ~LANDLOCK_ACCESS_FS_READ_FILE,
+			   });
+
+	fd = open("/dev/null", O_RDONLY | O_CLOEXEC);
+	ASSERT_LE(0, fd);
+	EXPECT_EQ(EACCES, ioctl_error(_metadata, fd, FIONREAD));
+	EXPECT_EQ(0, matches_log_fs_extra(_metadata, self->audit_fd,
+					  "fs\\.ioctl_dev", "/dev/null",
+					  " ioctlcmd=0x541b"));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
+TEST_F(audit_layout1, mount)
+{
+	struct audit_records records;
+
+	drop_access_rights(_metadata,
+			   &(struct landlock_ruleset_attr){
+				   .handled_access_fs =
+					   LANDLOCK_ACCESS_FS_EXECUTE,
+			   });
+
+	set_cap(_metadata, CAP_SYS_ADMIN);
+	EXPECT_EQ(-1, mount(NULL, dir_s3d2, NULL, MS_RDONLY, NULL));
+	EXPECT_EQ(EPERM, errno);
+	clear_cap(_metadata, CAP_SYS_ADMIN);
+	EXPECT_EQ(0, matches_log_fs(_metadata, self->audit_fd,
+				    "fs\\.change_topology", dir_s3d2));
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+}
+
 TEST_HARNESS_MAIN
-- 
2.49.0

[PATCH v7 27/28] selftests/landlock: Add audit tests for network

[Mickaël Salaün]

Test all network blockers:
- net.bind_tcp
- net.connect_tcp

Test coverage for security/landlock is 94.0% of 1430 lines according to
gcc/gcov-14.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- New patch.
---
 tools/testing/selftests/landlock/net_test.c | 132 ++++++++++++++++++++
 1 file changed, 132 insertions(+)

diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
index d9de0ee49ebc..2a45208551e6 100644
--- a/tools/testing/selftests/landlock/net_test.c
+++ b/tools/testing/selftests/landlock/net_test.c
@@ -20,6 +20,7 @@
 #include <sys/syscall.h>
 #include <sys/un.h>
 
+#include "audit.h"
 #include "common.h"
 
 const short sock_port_start = (1 << 10);
@@ -1868,4 +1869,135 @@ TEST_F(port_specific, bind_connect_1023)
 	EXPECT_EQ(0, close(bind_fd));
 }
 
+static int matches_log_tcp(const int audit_fd, const char *const blockers,
+			   const char *const dir_addr, const char *const addr,
+			   const char *const dir_port)
+{
+	static const char log_template[] = REGEX_LANDLOCK_PREFIX
+		" blockers=%s %s=%s %s=1024$";
+	/*
+	 * Max strlen(blockers): 16
+	 * Max strlen(dir_addr): 5
+	 * Max strlen(addr): 12
+	 * Max strlen(dir_port): 4
+	 */
+	char log_match[sizeof(log_template) + 37];
+	int log_match_len;
+
+	log_match_len = snprintf(log_match, sizeof(log_match), log_template,
+				 blockers, dir_addr, addr, dir_port);
+	if (log_match_len > sizeof(log_match))
+		return -E2BIG;
+
+	return audit_match_record(audit_fd, AUDIT_LANDLOCK_ACCESS, log_match,
+				  NULL);
+}
+
+FIXTURE(audit)
+{
+	struct service_fixture srv0;
+	struct audit_filter audit_filter;
+	int audit_fd;
+};
+
+FIXTURE_VARIANT(audit)
+{
+	const char *const addr;
+	const struct protocol_variant prot;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit, ipv4) {
+	/* clang-format on */
+	.addr = "127\\.0\\.0\\.1",
+	.prot = {
+		.domain = AF_INET,
+		.type = SOCK_STREAM,
+	},
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(audit, ipv6) {
+	/* clang-format on */
+	.addr = "::1",
+	.prot = {
+		.domain = AF_INET6,
+		.type = SOCK_STREAM,
+	},
+};
+
+FIXTURE_SETUP(audit)
+{
+	ASSERT_EQ(0, set_service(&self->srv0, variant->prot, 0));
+	setup_loopback(_metadata);
+
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	self->audit_fd = audit_init_with_exe_filter(&self->audit_filter);
+	EXPECT_LE(0, self->audit_fd);
+	disable_caps(_metadata);
+};
+
+FIXTURE_TEARDOWN(audit)
+{
+	set_cap(_metadata, CAP_AUDIT_CONTROL);
+	EXPECT_EQ(0, audit_cleanup(self->audit_fd, &self->audit_filter));
+	clear_cap(_metadata, CAP_AUDIT_CONTROL);
+}
+
+TEST_F(audit, bind)
+{
+	const struct landlock_ruleset_attr ruleset_attr = {
+		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
+				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
+	};
+	struct audit_records records;
+	int ruleset_fd, sock_fd;
+
+	ruleset_fd =
+		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+	ASSERT_LE(0, ruleset_fd);
+	enforce_ruleset(_metadata, ruleset_fd);
+	EXPECT_EQ(0, close(ruleset_fd));
+
+	sock_fd = socket_variant(&self->srv0);
+	ASSERT_LE(0, sock_fd);
+	EXPECT_EQ(-EACCES, bind_variant(sock_fd, &self->srv0));
+	EXPECT_EQ(0, matches_log_tcp(self->audit_fd, "net\\.bind_tcp", "saddr",
+				     variant->addr, "src"));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+
+	EXPECT_EQ(0, close(sock_fd));
+}
+
+TEST_F(audit, connect)
+{
+	const struct landlock_ruleset_attr ruleset_attr = {
+		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
+				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
+	};
+	struct audit_records records;
+	int ruleset_fd, sock_fd;
+
+	ruleset_fd =
+		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+	ASSERT_LE(0, ruleset_fd);
+	enforce_ruleset(_metadata, ruleset_fd);
+	EXPECT_EQ(0, close(ruleset_fd));
+
+	sock_fd = socket_variant(&self->srv0);
+	ASSERT_LE(0, sock_fd);
+	EXPECT_EQ(-EACCES, connect_variant(sock_fd, &self->srv0));
+	EXPECT_EQ(0, matches_log_tcp(self->audit_fd, "net\\.connect_tcp",
+				     "daddr", variant->addr, "dest"));
+
+	EXPECT_EQ(0, audit_count_records(self->audit_fd, &records));
+	EXPECT_EQ(0, records.access);
+	EXPECT_EQ(1, records.domain);
+
+	EXPECT_EQ(0, close(sock_fd));
+}
+
 TEST_HARNESS_MAIN
-- 
2.49.0

[PATCH v7 28/28] landlock: Add audit documentation

[Mickaël Salaün]

Because audit is dedicated to the system administrator, create a new
entry in Documentation/admin-guide/LSM .  Extend other Landlock
documentation's pages with this new one.

Extend UAPI with the new log flags.

Extend the guiding principles with logs.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---

Changes since v6:
- Extend UAPI with ABI v7.

Changes since v5:
- Extend the guiding principles with logs.

Changes since v4:
- New patch.
---
 Documentation/admin-guide/LSM/index.rst    |   1 +
 Documentation/admin-guide/LSM/landlock.rst | 158 +++++++++++++++++++++
 Documentation/security/landlock.rst        |  13 +-
 Documentation/userspace-api/landlock.rst   |  17 +++
 MAINTAINERS                                |   1 +
 5 files changed, 189 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/admin-guide/LSM/landlock.rst

diff --git a/Documentation/admin-guide/LSM/index.rst b/Documentation/admin-guide/LSM/index.rst
index ce63be6d64ad..b44ef68f6e4d 100644
--- a/Documentation/admin-guide/LSM/index.rst
+++ b/Documentation/admin-guide/LSM/index.rst
@@ -48,3 +48,4 @@ subdirectories.
    Yama
    SafeSetID
    ipe
+   landlock
diff --git a/Documentation/admin-guide/LSM/landlock.rst b/Documentation/admin-guide/LSM/landlock.rst
new file mode 100644
index 000000000000..9e61607def08
--- /dev/null
+++ b/Documentation/admin-guide/LSM/landlock.rst
@@ -0,0 +1,158 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. Copyright © 2025 Microsoft Corporation
+
+================================
+Landlock: system-wide management
+================================
+
+:Author: Mickaël Salaün
+:Date: March 2025
+
+Landlock can leverage the audit framework to log events.
+
+User space documentation can be found here:
+Documentation/userspace-api/landlock.rst.
+
+Audit
+=====
+
+Denied access requests are logged by default for a sandboxed program if `audit`
+is enabled.  This default behavior can be changed with the
+sys_landlock_restrict_self() flags (cf.
+Documentation/userspace-api/landlock.rst).  Landlock logs can also be masked
+thanks to audit rules.  Landlock can generate 2 audit record types.
+
+Record types
+------------
+
+AUDIT_LANDLOCK_ACCESS
+    This record type identifies a denied access request to a kernel resource.
+    The ``domain`` field indicates the ID of the domain that blocked the
+    request.  The ``blockers`` field indicates the cause(s) of this denial
+    (separated by a comma), and the following fields identify the kernel object
+    (similar to SELinux).  There may be more than one of this record type per
+    audit event.
+
+    Example with a file link request generating two records in the same event::
+
+        domain=195ba459b blockers=fs.refer path="/usr/bin" dev="vda2" ino=351
+        domain=195ba459b blockers=fs.make_reg,fs.refer path="/usr/local" dev="vda2" ino=365
+
+AUDIT_LANDLOCK_DOMAIN
+    This record type describes the status of a Landlock domain.  The ``status``
+    field can be either ``allocated`` or ``deallocated``.
+
+    The ``allocated`` status is part of the same audit event and follows
+    the first logged ``AUDIT_LANDLOCK_ACCESS`` record of a domain.  It identifies
+    Landlock domain information at the time of the sys_landlock_restrict_self()
+    call with the following fields:
+
+    - the ``domain`` ID
+    - the enforcement ``mode``
+    - the domain creator's ``pid``
+    - the domain creator's ``uid``
+    - the domain creator's executable path (``exe``)
+    - the domain creator's command line (``comm``)
+
+    Example::
+
+        domain=195ba459b status=allocated mode=enforcing pid=300 uid=0 exe="/root/sandboxer" comm="sandboxer"
+
+    The ``deallocated`` status is an event on its own and it identifies a
+    Landlock domain release.  After such event, it is guarantee that the
+    related domain ID will never be reused during the lifetime of the system.
+    The ``domain`` field indicates the ID of the domain which is released, and
+    the ``denials`` field indicates the total number of denied access request,
+    which might not have been logged according to the audit rules and
+    sys_landlock_restrict_self()'s flags.
+
+    Example::
+
+        domain=195ba459b status=deallocated denials=3
+
+
+Event samples
+--------------
+
+Here are two examples of log events (see serial numbers).
+
+In this example a sandboxed program (``kill``) tries to send a signal to the
+init process, which is denied because of the signal scoping restriction
+(``LL_SCOPED=s``)::
+
+  $ LL_FS_RO=/ LL_FS_RW=/ LL_SCOPED=s LL_FORCE_LOG=1 ./sandboxer kill 1
+
+This command generates two events, each identified with a unique serial
+number following a timestamp (``msg=audit(1729738800.268:30)``).  The first
+event (serial ``30``) contains 4 records.  The first record
+(``type=LANDLOCK_ACCESS``) shows an access denied by the domain `1a6fdc66f`.
+The cause of this denial is signal scopping restriction
+(``blockers=scope.signal``).  The process that would have receive this signal
+is the init process (``opid=1 ocomm="systemd"``).
+
+The second record (``type=LANDLOCK_DOMAIN``) describes (``status=allocated``)
+domain `1a6fdc66f`.  This domain was created by process ``286`` executing the
+``/root/sandboxer`` program launched by the root user.
+
+The third record (``type=SYSCALL``) describes the syscall, its provided
+arguments, its result (``success=no exit=-1``), and the process that called it.
+
+The fourth record (``type=PROCTITLE``) shows the command's name as an
+hexadecimal value.  This can be translated with ``python -c
+'print(bytes.fromhex("6B696C6C0031"))'``.
+
+Finally, the last record (``type=LANDLOCK_DOMAIN``) is also the only one from
+the second event (serial ``31``).  It is not tied to a direct user space action
+but an asynchronous one to free resources tied to a Landlock domain
+(``status=deallocated``).  This can be useful to know that the following logs
+will not concern the domain ``1a6fdc66f`` anymore.  This record also summarize
+the number of requests this domain denied (``denials=1``), whether they were
+logged or not.
+
+.. code-block::
+
+  type=LANDLOCK_ACCESS msg=audit(1729738800.268:30): domain=1a6fdc66f blockers=scope.signal opid=1 ocomm="systemd"
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.268:30): domain=1a6fdc66f status=allocated mode=enforcing pid=286 uid=0 exe="/root/sandboxer" comm="sandboxer"
+  type=SYSCALL msg=audit(1729738800.268:30): arch=c000003e syscall=62 success=no exit=-1 [..] ppid=272 pid=286 auid=0 uid=0 gid=0 [...] comm="kill" [...]
+  type=PROCTITLE msg=audit(1729738800.268:30): proctitle=6B696C6C0031
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.324:31): domain=1a6fdc66f status=deallocated denials=1
+
+Here is another example showcasing filesystem access control::
+
+  $ LL_FS_RO=/ LL_FS_RW=/tmp LL_FORCE_LOG=1 ./sandboxer sh -c "echo > /etc/passwd"
+
+The related audit logs contains 8 records from 3 different events (serials 33,
+34 and 35) created by the same domain `1a6fdc679`::
+
+  type=LANDLOCK_ACCESS msg=audit(1729738800.221:33): domain=1a6fdc679 blockers=fs.write_file path="/dev/tty" dev="devtmpfs" ino=9
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.221:33): domain=1a6fdc679 status=allocated mode=enforcing pid=289 uid=0 exe="/root/sandboxer" comm="sandboxer"
+  type=SYSCALL msg=audit(1729738800.221:33): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
+  type=PROCTITLE msg=audit(1729738800.221:33): proctitle=7368002D63006563686F203E202F6574632F706173737764
+  type=LANDLOCK_ACCESS msg=audit(1729738800.221:34): domain=1a6fdc679 blockers=fs.write_file path="/etc/passwd" dev="vda2" ino=143821
+  type=SYSCALL msg=audit(1729738800.221:34): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
+  type=PROCTITLE msg=audit(1729738800.221:34): proctitle=7368002D63006563686F203E202F6574632F706173737764
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.261:35): domain=1a6fdc679 status=deallocated denials=2
+
+
+Event filtering
+---------------
+
+If you get spammed with audit logs related to Landlock, this is either an
+attack attempt or a bug in the security policy.  We can put in place some
+filters to limit noise with two complementary ways:
+
+- with sys_landlock_restrict_self()'s flags if we can fix the sandboxed
+  programs,
+- or with audit rules (see :manpage:`auditctl(8)`).
+
+Additional documentation
+========================
+
+* `Linux Audit Documentation`_
+* Documentation/userspace-api/landlock.rst
+* Documentation/security/landlock.rst
+* https://landlock.io
+
+.. Links
+.. _Linux Audit Documentation:
+   https://github.com/linux-audit/audit-documentation/wiki
diff --git a/Documentation/security/landlock.rst b/Documentation/security/landlock.rst
index 59ecdb1c0d4d..e0fc54aff09e 100644
--- a/Documentation/security/landlock.rst
+++ b/Documentation/security/landlock.rst
@@ -7,7 +7,7 @@ Landlock LSM: kernel documentation
 ==================================
 
 :Author: Mickaël Salaün
-:Date: December 2022
+:Date: March 2025
 
 Landlock's goal is to create scoped access-control (i.e. sandboxing).  To
 harden a whole system, this feature should be available to any process,
@@ -45,6 +45,10 @@ Guiding principles for safe access controls
   sandboxed process shall retain their scoped accesses (at the time of resource
   acquisition) whatever process uses them.
   Cf. `File descriptor access rights`_.
+* Access denials shall be logged according to system and Landlock domain
+  configurations.  Log entries must contain information about the cause of the
+  denial and the owner of the related security policy.  Such log generation
+  should have a negligible performance and memory impact on allowed requests.
 
 Design choices
 ==============
@@ -124,6 +128,13 @@ makes the reasoning much easier and helps avoid pitfalls.
 .. kernel-doc:: security/landlock/ruleset.h
     :identifiers:
 
+Additional documentation
+========================
+
+* Documentation/userspace-api/landlock.rst
+* Documentation/admin-guide/LSM/landlock.rst
+* https://landlock.io
+
 .. Links
 .. _tools/testing/selftests/landlock/:
    https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/landlock/
diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
index 900171e3c494..1d0c2c15c22e 100644
--- a/Documentation/userspace-api/landlock.rst
+++ b/Documentation/userspace-api/landlock.rst
@@ -594,6 +594,16 @@ Starting with the Landlock ABI version 6, it is possible to restrict
 :manpage:`signal(7)` sending by setting ``LANDLOCK_SCOPE_SIGNAL`` to the
 ``scoped`` ruleset attribute.
 
+Logging (ABI < 7)
+-----------------
+
+Starting with the Landlock ABI version 7, it is possible to control logging of
+Landlock audit events with the ``LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF``,
+``LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON``, and
+``LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF`` flags passed to
+sys_landlock_restrict_self().  See Documentation/admin-guide/LSM/landlock.rst
+for more details on audit.
+
 .. _kernel_support:
 
 Kernel support
@@ -682,9 +692,16 @@ fine-grained restrictions).  Moreover, their complexity can lead to security
 issues, especially when untrusted processes can manipulate them (cf.
 `Controlling access to user namespaces <https://lwn.net/Articles/673597/>`_).
 
+How to disable Landlock audit records?
+--------------------------------------
+
+You might want to put in place filters as explained here:
+Documentation/admin-guide/LSM/landlock.rst
+
 Additional documentation
 ========================
 
+* Documentation/admin-guide/LSM/landlock.rst
 * Documentation/security/landlock.rst
 * https://landlock.io
 
diff --git a/MAINTAINERS b/MAINTAINERS
index 8e0736dc2ee0..a3aa52e47401 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13075,6 +13075,7 @@ L:	linux-security-module@vger.kernel.org
 S:	Supported
 W:	https://landlock.io
 T:	git https://git.kernel.org/pub/scm/linux/kernel/git/mic/linux.git
+F:	Documentation/admin-guide/LSM/landlock.rst
 F:	Documentation/security/landlock.rst
 F:	Documentation/userspace-api/landlock.rst
 F:	fs/ioctl.c
-- 
2.49.0

Re: [PATCH v7 01/28] lsm: Add audit_log_lsm_data() helper

[Günther Noack]

On Thu, Mar 20, 2025 at 08:06:50PM +0100, Mickaël Salaün wrote:
> diff --git a/security/lsm_audit.c b/security/lsm_audit.c
> index 52db886dbba8..a61c7ebdb6a7 100644
> --- a/security/lsm_audit.c
> +++ b/security/lsm_audit.c
> @@ -431,6 +425,21 @@ static void dump_common_audit_data(struct audit_buffer *ab,
>  	} /* switch (a->type) */
>  }
>  
> +/**
> + * dump_common_audit_data - helper to dump common audit data
> + * @ab : the audit buffer
> + * @a : common audit data
> + */

I was tempted to remark on the unusual documentation style with the
extra space before the colon, but I see that it has prior art in the
same file...

> +static void dump_common_audit_data(struct audit_buffer *ab,
> +				   const struct common_audit_data *a)
> +{
> +	char comm[sizeof(current->comm)];
> +
> +	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
> +	audit_log_untrustedstring(ab, get_task_comm(comm, current));
> +	audit_log_lsm_data(ab, a);
> +}
> +
>  /**
>   * common_lsm_audit - generic LSM auditing function
>   * @a:  auxiliary audit data
> -- 
> 2.49.0
> 

Reviewed-by: Günther Noack <gnoack3000@gmail.com>

Re: [PATCH v7 03/28] landlock: Move domain hierarchy management

[Günther Noack]

On Thu, Mar 20, 2025 at 08:06:52PM +0100, Mickaël Salaün wrote:
> Create a new domain.h file containing the struct landlock_hierarchy
> definition and helpers.  This type will grow with audit support.  This
> also prepares for a new domain type.
> 
> Cc: Günther Noack <gnoack@google.com>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>

Reviewed-by: Günther Noack <gnoack3000@gmail.com>

Re: [PATCH v7 09/28] landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials

[Tingmao Wang]

Hi Mickaël,

On 3/20/25 19:06, Mickaël Salaün wrote:
[...]
> +static struct landlock_hierarchy *
> +get_hierarchy(const struct landlock_ruleset *const domain, const size_t layer)
> +{
> +	struct landlock_hierarchy *hierarchy = domain->hierarchy;
> +	ssize_t i;
> +
> +	if (WARN_ON_ONCE(layer >= domain->num_layers))
> +		return hierarchy;
> +
> +	for (i = domain->num_layers - 1; i > layer; i--) {
> +		if (WARN_ON_ONCE(!hierarchy->parent))
> +			break;
> +
> +		hierarchy = hierarchy->parent;
> +	}
> +
> +	return hierarchy;
> +}
> +
> +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
> +
> +static void test_get_hierarchy(struct kunit *const test)
> +{
> +	struct landlock_hierarchy dom0_hierarchy = {
> +		.id = 10,
> +	};
> +	struct landlock_hierarchy dom1_hierarchy = {
> +		.parent = &dom0_hierarchy,
> +		.id = 20,
> +	};
> +	struct landlock_hierarchy dom2_hierarchy = {
> +		.parent = &dom1_hierarchy,
> +		.id = 30,
> +	};
> +	struct landlock_ruleset dom2 = {
> +		.hierarchy = &dom2_hierarchy,
> +		.num_layers = 3,
> +	};
> +
> +	KUNIT_EXPECT_EQ(test, 10, get_hierarchy(&dom2, 0)->id);
> +	KUNIT_EXPECT_EQ(test, 20, get_hierarchy(&dom2, 1)->id);
> +	KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, 2)->id);
> +	KUNIT_EXPECT_EQ(test, 30, get_hierarhy(&dom2, -1)->id);

This causes a warning from WARN_ON_ONCE(layer >= domain->num_layers)
when running this test, I guess because layer is unsigned.  Should it
be ssize_t, if this is an expected usage?

------------[ cut here ]------------
WARNING: CPU: 7 PID: 145 at security/landlock/audit.c:142 get_hierarchy (security/landlock/audit.c:142)
Modules linked in:
CPU: 7 UID: 0 PID: 145 Comm: kunit_try_catch Tainted: G                 N  6.14.0-next-20250326-dev-00004-g4e57edc3e062-dirty #5 PREEMPT(undef)
Tainted: [N]=TEST
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:get_hierarchy (security/landlock/audit.c:142)
Code: 83 e8 02 e8 18 00 84 c0 75 02 0f 0b 48 83 c4 08 48 89 d8 5b 41 5c 41 5e 5d c3 48 c7 c7 00 f3 21 83 e8 e2 e7 18 00 84 c0 75 e2 <0f> 0b eb de 48 89 75 e0 e8 a1 a9 a7 ff 48 8b 75 e0 e9 76 ff ff ff
// snip //
Call Trace:
 <TASK>
test_get_hierarchy (security/landlock/audit.c:178 (discriminator 5))
? test_get_denied_layer (security/landlock/audit.c:158)
? lock_repin_lock (kernel/locking/lockdep.c:5649 kernel/locking/lockdep.c:5978)
? __lock_acquire (kernel/locking/lockdep.c:4675 kernel/locking/lockdep.c:5189)
? _raw_spin_unlock_irqrestore (./include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194)
? find_held_lock (kernel/locking/lockdep.c:5348)
? trace_irq_enable (./include/trace/events/preemptirq.h:40 (discriminator 17))
? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:80)
? kvm_clock_get_cycles (./arch/x86/include/asm/preempt.h:95 arch/x86/kernel/kvmclock.c:80 arch/x86/kernel/kvmclock.c:86)
? ktime_get_ts64 (kernel/time/timekeeping.c:318 (discriminator 4) kernel/time/timekeeping.c:335 (discriminator 4) kernel/time/timekeeping.c:907 (discriminator 4))
kunit_try_run_case (lib/kunit/test.c:400 lib/kunit/test.c:443)
? kunit_try_run_case_cleanup (lib/kunit/test.c:430)

Re: [PATCH v7 09/28] landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials

[Mickaël Salaün]

On Thu, Mar 27, 2025 at 09:38:05PM +0000, Tingmao Wang wrote:
> Hi Mickaël,

Hi, thanks for the report.

> 
> On 3/20/25 19:06, Mickaël Salaün wrote:
> [...]
> > +static struct landlock_hierarchy *
> > +get_hierarchy(const struct landlock_ruleset *const domain, const size_t layer)
> > +{
> > +	struct landlock_hierarchy *hierarchy = domain->hierarchy;
> > +	ssize_t i;
> > +
> > +	if (WARN_ON_ONCE(layer >= domain->num_layers))
> > +		return hierarchy;
> > +
> > +	for (i = domain->num_layers - 1; i > layer; i--) {
> > +		if (WARN_ON_ONCE(!hierarchy->parent))
> > +			break;
> > +
> > +		hierarchy = hierarchy->parent;
> > +	}
> > +
> > +	return hierarchy;
> > +}
> > +
> > +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
> > +
> > +static void test_get_hierarchy(struct kunit *const test)
> > +{
> > +	struct landlock_hierarchy dom0_hierarchy = {
> > +		.id = 10,
> > +	};
> > +	struct landlock_hierarchy dom1_hierarchy = {
> > +		.parent = &dom0_hierarchy,
> > +		.id = 20,
> > +	};
> > +	struct landlock_hierarchy dom2_hierarchy = {
> > +		.parent = &dom1_hierarchy,
> > +		.id = 30,
> > +	};
> > +	struct landlock_ruleset dom2 = {
> > +		.hierarchy = &dom2_hierarchy,
> > +		.num_layers = 3,
> > +	};
> > +
> > +	KUNIT_EXPECT_EQ(test, 10, get_hierarchy(&dom2, 0)->id);
> > +	KUNIT_EXPECT_EQ(test, 20, get_hierarchy(&dom2, 1)->id);
> > +	KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, 2)->id);
> > +	KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, -1)->id);
> 
> This causes a warning from WARN_ON_ONCE(layer >= domain->num_layers)
> when running this test, I guess because layer is unsigned.

Interestingly this doesn't make the test to fail (because the result is
still correct), nor to show up when using tools/testing/kunit/kunit.py,
which is why I didn't see that.

> Should it
> be ssize_t, if this is an expected usage?

The get_hierarchy() code is correct, and the KUnit test is correct too.
Using a ssize_t would introduce a bug.

The issue is that I wanted to test a case that should never happen,
hence the WARN_ON_ONCE().

I guess the best "fix" for now would be to remove the KUnit test with
-1, but there is a new KUnit feature to hide this kind of warning:
https://lore.kernel.org/linux-kselftest/20250313114329.284104-1-acarmina@redhat.com/
It is currently in linux-next, but I'm not sure it will be merged in
Linux 6.15 .

For now I'll keep this commit but I'll send a fix/update to either
remove the test or use the new DEFINE_SUPPRESSED_WARNING macros
depending on its merge status.

> 
> ------------[ cut here ]------------
> WARNING: CPU: 7 PID: 145 at security/landlock/audit.c:142 get_hierarchy (security/landlock/audit.c:142)
> Modules linked in:
> CPU: 7 UID: 0 PID: 145 Comm: kunit_try_catch Tainted: G                 N  6.14.0-next-20250326-dev-00004-g4e57edc3e062-dirty #5 PREEMPT(undef)
> Tainted: [N]=TEST
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:get_hierarchy (security/landlock/audit.c:142)
> Code: 83 e8 02 e8 18 00 84 c0 75 02 0f 0b 48 83 c4 08 48 89 d8 5b 41 5c 41 5e 5d c3 48 c7 c7 00 f3 21 83 e8 e2 e7 18 00 84 c0 75 e2 <0f> 0b eb de 48 89 75 e0 e8 a1 a9 a7 ff 48 8b 75 e0 e9 76 ff ff ff
> // snip //
> Call Trace:
>  <TASK>
> test_get_hierarchy (security/landlock/audit.c:178 (discriminator 5))
> ? test_get_denied_layer (security/landlock/audit.c:158)
> ? lock_repin_lock (kernel/locking/lockdep.c:5649 kernel/locking/lockdep.c:5978)
> ? __lock_acquire (kernel/locking/lockdep.c:4675 kernel/locking/lockdep.c:5189)
> ? _raw_spin_unlock_irqrestore (./include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194)
> ? find_held_lock (kernel/locking/lockdep.c:5348)
> ? trace_irq_enable (./include/trace/events/preemptirq.h:40 (discriminator 17))
> ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:80)
> ? kvm_clock_get_cycles (./arch/x86/include/asm/preempt.h:95 arch/x86/kernel/kvmclock.c:80 arch/x86/kernel/kvmclock.c:86)
> ? ktime_get_ts64 (kernel/time/timekeeping.c:318 (discriminator 4) kernel/time/timekeeping.c:335 (discriminator 4) kernel/time/timekeeping.c:907 (discriminator 4))
> kunit_try_run_case (lib/kunit/test.c:400 lib/kunit/test.c:443)
> ? kunit_try_run_case_cleanup (lib/kunit/test.c:430)
> 
>