* FAILED: patch "[PATCH] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout" failed to apply to 6.1-stable tree
@ 2026-09-03 14:01 gregkh
2026-09-04 18:58 ` [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation Günther Noack
0 siblings, 1 reply; 13+ messages in thread
From: gregkh @ 2026-09-03 14:01 UTC (permalink / raw)
To: gnoack, brauner, mic; +Cc: stable
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 672fa082d48b21e1fb62cdb184fee41513e53421
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090318-unhook-scoff-4978@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 672fa082d48b21e1fb62cdb184fee41513e53421 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=BCnther=20Noack?= <gnoack@google.com>
Date: Thu, 13 Aug 2026 11:31:53 +0200
Subject: [PATCH] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout
creation
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Whiteout objects are used in the upper layer of an OverlayFS to
indicate that the file with this name does not exist in the unified
view, even if it is present in one of the lower layer file systems.
For the userspace implementations of OverlayFS (fuse-overlayfs),
whiteout objects can be created from userspace as well:
* mknod(2) with S_IFCHR and makedev(0, 0)
* renameat2(2) with RENAME_WHITEOUT,
creating the whiteout in the old place of the moved file.
This commit guards whiteout creation in both of these cases with
LANDLOCK_ACCESS_FS_MAKE_REG. Whiteout objects are *not* considered
character devices and are not bound to a driver.
LANDLOCK_ACCESS_FS_MAKE_REG describes the same permission class as a
whiteout object: creating one is the only S_IFCHR creation that the VFS
exempts from CAP_MKNOD, so it is as unprivileged as creating a regular
file, while LANDLOCK_ACCESS_FS_MAKE_CHAR and
LANDLOCK_ACCESS_FS_MAKE_BLOCK keep meaning the creation of devices that
expose a kernel interface [1].
For the mknod(2) case, introduce a Landlock erratum. The creation of
whiteout objects through mknod(2) was previously guarded using
LANDLOCK_ACCESS_FS_MAKE_CHAR, and it is now guarded using
LANDLOCK_ACCESS_FS_MAKE_REG.
For the renameat2(2) case, fix a bug: Before this commit, renameat2(2)
with RENAME_WHITEOUT would create a directory entry even when all
LANDLOCK_ACCESS_FS_MAKE_* rights were denied.
This does not affect normal renames within layered OverlayFS mounts:
When doing a regular rename() on a mounted fuse-overlayfs, it is the
fuse-overlayfs daemon that exercises renameat2() with RENAME_WHITEOUT,
and only the Landlock domain of that daemon is checked there.
Suggested-by: Christian Brauner <brauner@kernel.org>
Suggested-by: Mickaël Salaün <mic@digikod.net>
Cc: stable@vger.kernel.org
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Depends-on: 49c9e09d9610 ("landlock: Fix handling of disconnected directories")
Depends-on: fe72ce6710cb ("landlock: Add errata documentation section")
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://patch.msgid.link/20260720.chow9ohYie5b@digikod.net [1]
Link: https://patch.msgid.link/20260813093157.1436894-3-gnoack@google.com
[mic: Record why LANDLOCK_ACCESS_FS_MAKE_REG is the matching right, and
add link(2) to the user doc]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 272f047df438..27ae3f39cafb 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -351,6 +351,7 @@ struct landlock_net_port_attr {
* device.
* - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
* - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
+ * This also guards the creation of whiteout objects as used in OverlayFS.
* - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
* socket.
* - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
diff --git a/security/landlock/errata/abi-1.h b/security/landlock/errata/abi-1.h
index 3f099555f059..315ea7e0fe50 100644
--- a/security/landlock/errata/abi-1.h
+++ b/security/landlock/errata/abi-1.h
@@ -22,3 +22,26 @@
* from their original mount points.
*/
LANDLOCK_ERRATUM(3)
+
+/**
+ * DOC: erratum_4
+ *
+ * Erratum 4: Creation of whiteout objects
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This fix changes the access rights required for the creation of whiteout
+ * objects through :manpage:`mknod(2)`, :manpage:`renameat2(2)`, or
+ * :manpage:`link(2)`. Creating whiteout objects is now guarded by
+ * ``LANDLOCK_ACCESS_FS_MAKE_REG`` instead of ``LANDLOCK_ACCESS_FS_MAKE_CHAR``.
+ *
+ * Whiteout objects are used in OverlayFS to mark the absence of a file in an
+ * upper file system. Despite being created with ``S_IFCHR``, whiteout objects
+ * do not count as character devices.
+ *
+ * Impact:
+ *
+ * Sandboxed programs that create OverlayFS whiteouts (such as fuse-overlayfs)
+ * now require ``LANDLOCK_ACCESS_FS_MAKE_REG`` instead of
+ * ``LANDLOCK_ACCESS_FS_MAKE_CHAR``.
+ */
+LANDLOCK_ERRATUM(4)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index f7e5e4ef9eac..8fc7f82a374a 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -20,6 +20,7 @@
#include <linux/falloc.h>
#include <linux/fs.h>
#include <linux/init.h>
+#include <linux/kdev_t.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/list.h>
@@ -983,7 +984,8 @@ static int current_check_access_path(const struct path *const path,
return -EACCES;
}
-static __attribute_const__ access_mask_t get_mode_access(const umode_t mode)
+static __attribute_const__ access_mask_t get_mode_access(const umode_t mode,
+ const dev_t dev)
{
switch (mode & S_IFMT) {
case S_IFLNK:
@@ -991,6 +993,9 @@ static __attribute_const__ access_mask_t get_mode_access(const umode_t mode)
case S_IFDIR:
return LANDLOCK_ACCESS_FS_MAKE_DIR;
case S_IFCHR:
+ /* Whiteout objects are guarded with MAKE_REG. */
+ if (dev == WHITEOUT_DEV)
+ return LANDLOCK_ACCESS_FS_MAKE_REG;
return LANDLOCK_ACCESS_FS_MAKE_CHAR;
case S_IFBLK:
return LANDLOCK_ACCESS_FS_MAKE_BLOCK;
@@ -1007,6 +1012,13 @@ static __attribute_const__ access_mask_t get_mode_access(const umode_t mode)
}
}
+static access_mask_t get_dentry_access(const struct dentry *const dentry)
+{
+ const struct inode *const inode = d_backing_inode(dentry);
+
+ return get_mode_access(inode->i_mode, inode->i_rdev);
+}
+
static access_mask_t maybe_remove(const struct dentry *const dentry)
{
if (d_is_negative(dentry))
@@ -1093,6 +1105,7 @@ static bool collect_domain_accesses(const struct landlock_ruleset *const domain,
* @new_dentry: Destination file or directory.
* @removable: Sets to true if it is a rename operation.
* @exchange: Sets to true if it is a rename operation with RENAME_EXCHANGE.
+ * @whiteout: Sets to true if it is a rename operation with RENAME_WHITEOUT.
*
* Because of its unprivileged constraints, Landlock relies on file hierarchies
* (and not only inodes) to tie access rights to files. Being able to link or
@@ -1140,7 +1153,8 @@ static bool collect_domain_accesses(const struct landlock_ruleset *const domain,
static int current_check_refer_path(struct dentry *const old_dentry,
const struct path *const new_dir,
struct dentry *const new_dentry,
- const bool removable, const bool exchange)
+ const bool removable, const bool exchange,
+ const bool whiteout)
{
const struct landlock_cred_security *const subject =
landlock_get_applicable_subject(current_cred(), any_fs, NULL);
@@ -1159,18 +1173,25 @@ static int current_check_refer_path(struct dentry *const old_dentry,
if (exchange) {
if (unlikely(d_is_negative(new_dentry)))
return -ENOENT;
- access_request_parent1 =
- get_mode_access(d_backing_inode(new_dentry)->i_mode);
+ access_request_parent1 = get_dentry_access(new_dentry);
} else {
access_request_parent1 = 0;
}
- access_request_parent2 =
- get_mode_access(d_backing_inode(old_dentry)->i_mode);
+ access_request_parent2 = get_dentry_access(old_dentry);
if (removable) {
access_request_parent1 |= maybe_remove(old_dentry);
access_request_parent2 |= maybe_remove(new_dentry);
}
+ /*
+ * In case of renameat2(2) with RENAME_WHITEOUT, a whiteout object is
+ * created in the source location, so we require an additional access
+ * right there.
+ */
+ if (whiteout)
+ access_request_parent1 |=
+ get_mode_access(S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+
/* The mount points are the same for old and new paths, cf. EXDEV. */
if (old_dentry->d_parent == new_dir->dentry) {
/*
@@ -1520,7 +1541,7 @@ static int hook_path_link(struct dentry *const old_dentry,
struct dentry *const new_dentry)
{
return current_check_refer_path(old_dentry, new_dir, new_dentry, false,
- false);
+ false, false);
}
static int hook_path_rename(const struct path *const old_dir,
@@ -1531,7 +1552,8 @@ static int hook_path_rename(const struct path *const old_dir,
{
/* old_dir refers to old_dentry->d_parent and new_dir->mnt */
return current_check_refer_path(old_dentry, new_dir, new_dentry, true,
- !!(flags & RENAME_EXCHANGE));
+ !!(flags & RENAME_EXCHANGE),
+ !!(flags & RENAME_WHITEOUT));
}
static int hook_path_mkdir(const struct path *const dir,
@@ -1544,7 +1566,8 @@ static int hook_path_mknod(const struct path *const dir,
struct dentry *const dentry, const umode_t mode,
const unsigned int dev)
{
- return current_check_access_path(dir, get_mode_access(mode));
+ return current_check_access_path(
+ dir, get_mode_access(mode, new_decode_dev(dev)));
}
static int hook_path_symlink(const struct path *const dir,
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation
2026-09-03 14:01 FAILED: patch "[PATCH] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout" failed to apply to 6.1-stable tree gregkh
@ 2026-09-04 18:58 ` Günther Noack
2026-09-06 13:32 ` Sasha Levin
0 siblings, 1 reply; 13+ messages in thread
From: Günther Noack @ 2026-09-04 18:58 UTC (permalink / raw)
To: stable
Cc: Günther Noack, Christian Brauner, Mickaël Salaün,
Günther Noack
From: Günther Noack <gnoack@google.com>
Whiteout objects are used in the upper layer of an OverlayFS to
indicate that the file with this name does not exist in the unified
view, even if it is present in one of the lower layer file systems.
For the userspace implementations of OverlayFS (fuse-overlayfs),
whiteout objects can be created from userspace as well:
* mknod(2) with S_IFCHR and makedev(0, 0)
* renameat2(2) with RENAME_WHITEOUT,
creating the whiteout in the old place of the moved file.
This commit guards whiteout creation in both of these cases with
LANDLOCK_ACCESS_FS_MAKE_REG. Whiteout objects are *not* considered
character devices and are not bound to a driver.
LANDLOCK_ACCESS_FS_MAKE_REG describes the same permission class as a
whiteout object: creating one is the only S_IFCHR creation that the VFS
exempts from CAP_MKNOD, so it is as unprivileged as creating a regular
file, while LANDLOCK_ACCESS_FS_MAKE_CHAR and
LANDLOCK_ACCESS_FS_MAKE_BLOCK keep meaning the creation of devices that
expose a kernel interface [1].
For the mknod(2) case, introduce a Landlock erratum. The creation of
whiteout objects through mknod(2) was previously guarded using
LANDLOCK_ACCESS_FS_MAKE_CHAR, and it is now guarded using
LANDLOCK_ACCESS_FS_MAKE_REG.
For the renameat2(2) case, fix a bug: Before this commit, renameat2(2)
with RENAME_WHITEOUT would create a directory entry even when all
LANDLOCK_ACCESS_FS_MAKE_* rights were denied.
This does not affect normal renames within layered OverlayFS mounts:
When doing a regular rename() on a mounted fuse-overlayfs, it is the
fuse-overlayfs daemon that exercises renameat2() with RENAME_WHITEOUT,
and only the Landlock domain of that daemon is checked there.
Suggested-by: Christian Brauner <brauner@kernel.org>
Suggested-by: Mickaël Salaün <mic@digikod.net>
Cc: stable@vger.kernel.org
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Depends-on: 49c9e09d9610 ("landlock: Fix handling of disconnected directories")
Depends-on: fe72ce6710cb ("landlock: Add errata documentation section")
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://patch.msgid.link/20260720.chow9ohYie5b@digikod.net [1]
Link: https://patch.msgid.link/20260813093157.1436894-3-gnoack@google.com
[mic: Record why LANDLOCK_ACCESS_FS_MAKE_REG is the matching right, and
add link(2) to the user doc]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
(cherry picked from commit 672fa082d48b21e1fb62cdb184fee41513e53421)
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---
include/uapi/linux/landlock.h | 1 +
security/landlock/errata/abi-1.h | 24 +++++++++++++++++++
security/landlock/fs.c | 40 +++++++++++++++++++++++++-------
3 files changed, 56 insertions(+), 9 deletions(-)
create mode 100644 security/landlock/errata/abi-1.h
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 17bdfaa9eb87..d7a974f80cb9 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -115,6 +115,7 @@ struct landlock_path_beneath_attr {
* device.
* - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
* - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
+ * This also guards the creation of whiteout objects as used in OverlayFS.
* - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
* socket.
* - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
diff --git a/security/landlock/errata/abi-1.h b/security/landlock/errata/abi-1.h
new file mode 100644
index 000000000000..53c96c2057fa
--- /dev/null
+++ b/security/landlock/errata/abi-1.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/**
+ * DOC: erratum_4
+ *
+ * Erratum 4: Creation of whiteout objects
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This fix changes the access rights required for the creation of whiteout
+ * objects through :manpage:`mknod(2)`, :manpage:`renameat2(2)`, or
+ * :manpage:`link(2)`. Creating whiteout objects is now guarded by
+ * ``LANDLOCK_ACCESS_FS_MAKE_REG`` instead of ``LANDLOCK_ACCESS_FS_MAKE_CHAR``.
+ *
+ * Whiteout objects are used in OverlayFS to mark the absence of a file in an
+ * upper file system. Despite being created with ``S_IFCHR``, whiteout objects
+ * do not count as character devices.
+ *
+ * Impact:
+ *
+ * Sandboxed programs that create OverlayFS whiteouts (such as fuse-overlayfs)
+ * now require ``LANDLOCK_ACCESS_FS_MAKE_REG`` instead of
+ * ``LANDLOCK_ACCESS_FS_MAKE_CHAR``.
+ */
+LANDLOCK_ERRATUM(4)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 7b95afcc6b43..dd7f0fd921cf 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -15,6 +15,7 @@
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/init.h>
+#include <linux/kdev_t.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/list.h>
@@ -664,7 +665,7 @@ static inline int current_check_access_path(const struct path *const path,
return check_access_path(dom, path, access_request);
}
-static inline access_mask_t get_mode_access(const umode_t mode)
+static inline access_mask_t get_mode_access(const umode_t mode, const dev_t dev)
{
switch (mode & S_IFMT) {
case S_IFLNK:
@@ -672,6 +673,9 @@ static inline access_mask_t get_mode_access(const umode_t mode)
case S_IFDIR:
return LANDLOCK_ACCESS_FS_MAKE_DIR;
case S_IFCHR:
+ /* Whiteout objects are guarded with MAKE_REG. */
+ if (dev == WHITEOUT_DEV)
+ return LANDLOCK_ACCESS_FS_MAKE_REG;
return LANDLOCK_ACCESS_FS_MAKE_CHAR;
case S_IFBLK:
return LANDLOCK_ACCESS_FS_MAKE_BLOCK;
@@ -688,6 +692,13 @@ static inline access_mask_t get_mode_access(const umode_t mode)
}
}
+static inline access_mask_t get_dentry_access(const struct dentry *const dentry)
+{
+ const struct inode *const inode = d_backing_inode(dentry);
+
+ return get_mode_access(inode->i_mode, inode->i_rdev);
+}
+
static inline access_mask_t maybe_remove(const struct dentry *const dentry)
{
if (d_is_negative(dentry))
@@ -768,6 +779,7 @@ static bool collect_domain_accesses(
* @new_dentry: Destination file or directory.
* @removable: Sets to true if it is a rename operation.
* @exchange: Sets to true if it is a rename operation with RENAME_EXCHANGE.
+ * @whiteout: Sets to true if it is a rename operation with RENAME_WHITEOUT.
*
* Because of its unprivileged constraints, Landlock relies on file hierarchies
* (and not only inodes) to tie access rights to files. Being able to link or
@@ -816,7 +828,8 @@ static bool collect_domain_accesses(
static int current_check_refer_path(struct dentry *const old_dentry,
const struct path *const new_dir,
struct dentry *const new_dentry,
- const bool removable, const bool exchange)
+ const bool removable, const bool exchange,
+ const bool whiteout)
{
const struct landlock_ruleset *const dom =
landlock_get_current_domain();
@@ -836,18 +849,25 @@ static int current_check_refer_path(struct dentry *const old_dentry,
if (exchange) {
if (unlikely(d_is_negative(new_dentry)))
return -ENOENT;
- access_request_parent1 =
- get_mode_access(d_backing_inode(new_dentry)->i_mode);
+ access_request_parent1 = get_dentry_access(new_dentry);
} else {
access_request_parent1 = 0;
}
- access_request_parent2 =
- get_mode_access(d_backing_inode(old_dentry)->i_mode);
+ access_request_parent2 = get_dentry_access(old_dentry);
if (removable) {
access_request_parent1 |= maybe_remove(old_dentry);
access_request_parent2 |= maybe_remove(new_dentry);
}
+ /*
+ * In case of renameat2(2) with RENAME_WHITEOUT, a whiteout object is
+ * created in the source location, so we require an additional access
+ * right there.
+ */
+ if (whiteout)
+ access_request_parent1 |=
+ get_mode_access(S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+
/* The mount points are the same for old and new paths, cf. EXDEV. */
if (old_dentry->d_parent == new_dir->dentry) {
/*
@@ -1099,7 +1119,7 @@ static int hook_path_link(struct dentry *const old_dentry,
struct dentry *const new_dentry)
{
return current_check_refer_path(old_dentry, new_dir, new_dentry, false,
- false);
+ false, false);
}
static int hook_path_rename(const struct path *const old_dir,
@@ -1110,7 +1130,8 @@ static int hook_path_rename(const struct path *const old_dir,
{
/* old_dir refers to old_dentry->d_parent and new_dir->mnt */
return current_check_refer_path(old_dentry, new_dir, new_dentry, true,
- !!(flags & RENAME_EXCHANGE));
+ !!(flags & RENAME_EXCHANGE),
+ !!(flags & RENAME_WHITEOUT));
}
static int hook_path_mkdir(const struct path *const dir,
@@ -1128,7 +1149,8 @@ static int hook_path_mknod(const struct path *const dir,
if (!dom)
return 0;
- return check_access_path(dom, dir, get_mode_access(mode));
+ return check_access_path(dom, dir,
+ get_mode_access(mode, new_decode_dev(dev)));
}
static int hook_path_symlink(const struct path *const dir,
--
2.55.0
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation
2026-09-04 18:58 ` [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation Günther Noack
@ 2026-09-06 13:32 ` Sasha Levin
2026-09-09 18:18 ` Mickaël Salaün
` (4 more replies)
0 siblings, 5 replies; 13+ messages in thread
From: Sasha Levin @ 2026-09-06 13:32 UTC (permalink / raw)
To: stable
Cc: Sasha Levin, Günther Noack, Christian Brauner,
Mickaël Salaün, Günther Noack
> Whiteout objects are used in the upper layer of an OverlayFS to
> indicate that the file with this name does not exist in the unified
> view, even if it is present in one of the lower layer file systems.
>
> For the userspace implementations of OverlayFS (fuse-overlayfs),
> whiteout objects can be created from userspace as well:
Queued for 6.1, thanks. Note: 6.1 is missing 49c9e09d9610 ("landlock: Fix
handling of disconnected directories"), one of the two prerequisites this
commit's own message names -- 6.12 and 6.6 already carry it. The whiteout
check itself is still correct and worth having, but if a disconnected/
bind-mounted directory is involved on 6.1 specifically the enforcement may
not be reliable yet. Could you send 49c9e09d9610 as a follow-up for 6.1.y?
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation
2026-09-06 13:32 ` Sasha Levin
@ 2026-09-09 18:18 ` Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories Mickaël Salaün
` (3 subsequent siblings)
4 siblings, 0 replies; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-09 18:18 UTC (permalink / raw)
To: Sasha Levin
Cc: stable, Günther Noack, Christian Brauner, Günther Noack
On Sun, Sep 06, 2026 at 09:32:50AM -0400, Sasha Levin wrote:
> > Whiteout objects are used in the upper layer of an OverlayFS to
> > indicate that the file with this name does not exist in the unified
> > view, even if it is present in one of the lower layer file systems.
> >
> > For the userspace implementations of OverlayFS (fuse-overlayfs),
> > whiteout objects can be created from userspace as well:
>
> Queued for 6.1, thanks. Note: 6.1 is missing 49c9e09d9610 ("landlock: Fix
> handling of disconnected directories"), one of the two prerequisites this
> commit's own message names -- 6.12 and 6.6 already carry it. The whiteout
> check itself is still correct and worth having, but if a disconnected/
> bind-mounted directory is involved on 6.1 specifically the enforcement may
> not be reliable yet. Could you send 49c9e09d9610 as a follow-up for 6.1.y?
Hi Sasha,
These dependencies are indeed required to properly apply the patch, and
they are in fact fixes too (that failed to apply without changes). I'm
preparing a few backported patches (including these dependencies) that
I'll send this week.
Mickaël
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories
2026-09-06 13:32 ` Sasha Levin
2026-09-09 18:18 ` Mickaël Salaün
@ 2026-09-17 15:00 ` Mickaël Salaün
2026-09-18 0:52 ` Sasha Levin
2026-09-17 15:00 ` [PATCH 6.1.y 2/4] selftests/landlock: Add tests for access through disconnected paths Mickaël Salaün
` (2 subsequent siblings)
4 siblings, 1 reply; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-17 15:00 UTC (permalink / raw)
To: stable
Cc: Mickaël Salaün, Sasha Levin, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
[ Upstream commit 49c9e09d961025b22e61ef9ad56aa1c21b6ce2f1 ]
Disconnected files or directories can appear when they are visible and
opened from a bind mount, but have been renamed or moved from the source
of the bind mount in a way that makes them inaccessible from the mount
point (i.e. out of scope).
Previously, access rights tied to files or directories opened through a
disconnected directory were collected by walking the related hierarchy
down to the root of the filesystem, without taking into account the
mount point because it couldn't be found. This could lead to
inconsistent access results, potential access right widening, and
hard-to-debug renames, especially since such paths cannot be printed.
For a sandboxed task to create a disconnected directory, it needs to
have write access (i.e. FS_MAKE_REG, FS_REMOVE_FILE, and FS_REFER) to
the underlying source of the bind mount, and read access to the related
mount point. Because a sandboxed task cannot acquire more access
rights than those defined by its Landlock domain, this could lead to
inconsistent access rights due to missing permissions that should be
inherited from the mount point hierarchy, while inheriting permissions
from the filesystem hierarchy hidden by this mount point instead.
Landlock now handles files and directories opened from disconnected
directories by taking into account the filesystem hierarchy when the
mount point is not found in the hierarchy walk, and also always taking
into account the mount point from which these disconnected directories
were opened. This ensures that a rename is not allowed if it would
widen access rights [1].
The rationale is that, even if disconnected hierarchies might not be
visible or accessible to a sandboxed task, relying on the collected
access rights from them improves the guarantee that access rights will
not be widened during a rename because of the access right comparison
between the source and the destination (see LANDLOCK_ACCESS_FS_REFER).
It may look like this would grant more access on disconnected files and
directories, but the security policies are always enforced for all the
evaluated hierarchies. This new behavior should be less surprising to
users and safer from an access control perspective.
Remove a wrong WARN_ON_ONCE() canary in collect_domain_accesses() and
fix the related comment.
Because opened files have their access rights stored in the related file
security properties, there is no impact for disconnected or unlinked
files.
Cc: Christian Brauner <brauner@kernel.org>
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Reported-by: Tingmao Wang <m@maowtm.org>
Closes: https://lore.kernel.org/r/027d5190-b37a-40a8-84e9-4ccbc352bcdf@maowtm.org
Closes: https://lore.kernel.org/r/09b24128f86973a6022e6aa8338945fcfb9a33e4.1749925391.git.m@maowtm.org
Fixes: b91c3e4ea756 ("landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER")
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Link: https://lore.kernel.org/r/b0f46246-f2c5-42ca-93ce-0d629702a987@maowtm.org [1]
Reviewed-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
[mic: Backport: adjust the filesystem walk and errata insertion context]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
security/landlock/errata/abi-1.h | 15 ++++++++++++
security/landlock/fs.c | 40 +++++++++++++++++++++++---------
2 files changed, 44 insertions(+), 11 deletions(-)
diff --git a/security/landlock/errata/abi-1.h b/security/landlock/errata/abi-1.h
index 53c96c2057fa..80930957e84d 100644
--- a/security/landlock/errata/abi-1.h
+++ b/security/landlock/errata/abi-1.h
@@ -1,5 +1,20 @@
/* SPDX-License-Identifier: GPL-2.0-only */
+/**
+ * DOC: erratum_3
+ *
+ * Erratum 3: Disconnected directory handling
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This fix addresses an issue with disconnected directories that occur when a
+ * directory is moved outside the scope of a bind mount. The change ensures
+ * that evaluated access rights include both those from the disconnected file
+ * hierarchy down to its filesystem root and those from the related mount point
+ * hierarchy. This prevents access right widening through rename or link
+ * actions.
+ */
+LANDLOCK_ERRATUM(3)
+
/**
* DOC: erratum_4
*
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index dd7f0fd921cf..8f20a146648c 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -607,19 +607,31 @@ static int check_access_path_dual(
break;
}
}
+
if (unlikely(IS_ROOT(walker_path.dentry))) {
+ if (likely(walker_path.mnt->mnt_flags & MNT_INTERNAL)) {
+ /*
+ * Stops and allows access when reaching disconnected root
+ * directories that are part of internal filesystems (e.g. nsfs,
+ * which is reachable through /proc/<pid>/ns/<namespace>).
+ */
+ allowed_parent1 = true;
+ allowed_parent2 = true;
+ break;
+ }
+
/*
- * Stops at disconnected root directories. Only allows
- * access to internal filesystems (e.g. nsfs, which is
- * reachable through /proc/<pid>/ns/<namespace>).
+ * We reached a disconnected root directory from a bind mount.
+ * Let's continue the walk with the mount point we missed.
*/
- allowed_parent1 = allowed_parent2 =
- !!(walker_path.mnt->mnt_flags & MNT_INTERNAL);
- break;
+ dput(walker_path.dentry);
+ walker_path.dentry = walker_path.mnt->mnt_root;
+ dget(walker_path.dentry);
+ } else {
+ parent_dentry = dget_parent(walker_path.dentry);
+ dput(walker_path.dentry);
+ walker_path.dentry = parent_dentry;
}
- parent_dentry = dget_parent(walker_path.dentry);
- dput(walker_path.dentry);
- walker_path.dentry = parent_dentry;
}
path_put(&walker_path);
@@ -721,6 +733,9 @@ static inline access_mask_t maybe_remove(const struct dentry *const dentry)
* file. While walking from @dir to @mnt_root, we record all the domain's
* allowed accesses in @layer_masks_dom.
*
+ * Because of disconnected directories, this walk may not reach @mnt_dir. In
+ * this case, the walk will continue to @mnt_dir after this call.
+ *
* This is similar to check_access_path_dual() but much simpler because it only
* handles walking on the same mount point and only checks one set of accesses.
*
@@ -759,8 +774,11 @@ static bool collect_domain_accesses(
break;
}
- /* We should not reach a root other than @mnt_root. */
- if (dir == mnt_root || WARN_ON_ONCE(IS_ROOT(dir)))
+ /*
+ * Stops at the mount point or the filesystem root for a disconnected
+ * directory.
+ */
+ if (dir == mnt_root || unlikely(IS_ROOT(dir)))
break;
parent_dentry = dget_parent(dir);
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 6.1.y 2/4] selftests/landlock: Add tests for access through disconnected paths
2026-09-06 13:32 ` Sasha Levin
2026-09-09 18:18 ` Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories Mickaël Salaün
@ 2026-09-17 15:00 ` Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation Mickaël Salaün
4 siblings, 0 replies; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-17 15:00 UTC (permalink / raw)
To: stable
Cc: Mickaël Salaün, Sasha Levin, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
From: Tingmao Wang <m@maowtm.org>
[ Upstream commit a18ee3f31fd714173a62515d049d77e76ab55649 ]
This adds tests for the edge case discussed in [1], with specific ones
for rename and link operations when the operands are through
disconnected paths, as that go through a separate code path in Landlock.
This has resulted in a warning, due to collect_domain_accesses() not
expecting to reach a different root from path->mnt:
# RUN layout1_bind.path_disconnected ...
# OK layout1_bind.path_disconnected
ok 96 layout1_bind.path_disconnected
# RUN layout1_bind.path_disconnected_rename ...
[..] ------------[ cut here ]------------
[..] WARNING: CPU: 3 PID: 385 at security/landlock/fs.c:1065 collect_domain_accesses
[..] ...
[..] RIP: 0010:collect_domain_accesses (security/landlock/fs.c:1065 (discriminator 2) security/landlock/fs.c:1031 (discriminator 2))
[..] current_check_refer_path (security/landlock/fs.c:1205)
[..] ...
[..] hook_path_rename (security/landlock/fs.c:1526)
[..] security_path_rename (security/security.c:2026 (discriminator 1))
[..] do_renameat2 (fs/namei.c:5264)
# OK layout1_bind.path_disconnected_rename
ok 97 layout1_bind.path_disconnected_rename
Move the const char definitions a bit above so that we can use the path
for s4d1 in cleanup code.
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/027d5190-b37a-40a8-84e9-4ccbc352bcdf@maowtm.org [1]
Signed-off-by: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-4-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
[mic: Backport: adapt the tests to the older fixture teardown]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
tools/testing/selftests/landlock/fs_test.c | 423 ++++++++++++++++++++-
1 file changed, 415 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index b37c694d5c10..805fd1f9bc89 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -3240,6 +3240,18 @@ TEST_F_FORK(layout1, proc_pipe)
FIXTURE(layout1_bind) {};
/* clang-format on */
+static const char bind_dir_s1d3[] = TMP_DIR "/s2d1/s2d2/s1d3";
+static const char bind_file1_s1d3[] = TMP_DIR "/s2d1/s2d2/s1d3/f1";
+
+/* Move targets for disconnected path tests. */
+static const char dir_s4d1[] = TMP_DIR "/s4d1";
+static const char file1_s4d1[] = TMP_DIR "/s4d1/f1";
+static const char file2_s4d1[] = TMP_DIR "/s4d1/f2";
+static const char dir_s4d2[] = TMP_DIR "/s4d1/s4d2";
+static const char file1_s4d2[] = TMP_DIR "/s4d1/s4d2/f1";
+static const char file1_name[] = "f1";
+static const char file2_name[] = "f2";
+
FIXTURE_SETUP(layout1_bind)
{
prepare_layout(_metadata);
@@ -3257,14 +3269,14 @@ FIXTURE_TEARDOWN(layout1_bind)
EXPECT_EQ(0, umount(dir_s2d2));
clear_cap(_metadata, CAP_SYS_ADMIN);
+ remove_path(file1_s4d1);
+ remove_path(file2_s4d1);
+
remove_layout1(_metadata);
cleanup_layout(_metadata);
}
-static const char bind_dir_s1d3[] = TMP_DIR "/s2d1/s2d2/s1d3";
-static const char bind_file1_s1d3[] = TMP_DIR "/s2d1/s2d2/s1d3/f1";
-
/*
* layout1_bind hierarchy:
*
@@ -3275,20 +3287,25 @@ static const char bind_file1_s1d3[] = TMP_DIR "/s2d1/s2d2/s1d3/f1";
* │ └── s1d2
* │ ├── f1
* │ ├── f2
- * │ └── s1d3
+ * │ └── s1d3 [disconnected by path_disconnected]
* │ ├── f1
* │ └── f2
* ├── s2d1
* │ ├── f1
- * │ └── s2d2
+ * │ └── s2d2 [bind mount from s1d2]
* │ ├── f1
* │ ├── f2
* │ └── s1d3
* │ ├── f1
* │ └── f2
- * └── s3d1
- * └── s3d2
- * └── s3d3
+ * ├── s3d1
+ * │ └── s3d2
+ * │ └── s3d3
+ * └── s4d1 [renamed from s1d3 by path_disconnected]
+ * ├── f1
+ * ├── f2
+ * └── s4d2
+ * └── f1
*/
TEST_F_FORK(layout1_bind, no_restriction)
@@ -3487,6 +3504,396 @@ TEST_F_FORK(layout1_bind, reparent_cross_mount)
ASSERT_EQ(0, rename(bind_file1_s1d3, file1_s2d2));
}
+/*
+ * Make sure access to file through a disconnected path works as expected.
+ * This test moves s1d3 to s4d1.
+ */
+TEST_F_FORK(layout1_bind, path_disconnected)
+{
+ const struct rule layer1_allow_all[] = {
+ {
+ .path = TMP_DIR,
+ .access = ACCESS_ALL,
+ },
+ {},
+ };
+ const struct rule layer2_allow_just_f1[] = {
+ {
+ .path = file1_s1d3,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE,
+ },
+ {},
+ };
+ const struct rule layer3_only_s1d2[] = {
+ {
+ .path = dir_s1d2,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE,
+ },
+ {},
+ };
+
+ /* Landlock should not deny access just because it is disconnected. */
+ int ruleset_fd_l1 =
+ create_ruleset(_metadata, ACCESS_ALL, layer1_allow_all);
+
+ /* Creates the new ruleset now before we move the dir containing the file. */
+ int ruleset_fd_l2 =
+ create_ruleset(_metadata, ACCESS_RW, layer2_allow_just_f1);
+ int ruleset_fd_l3 =
+ create_ruleset(_metadata, ACCESS_RW, layer3_only_s1d2);
+ int bind_s1d3_fd;
+
+ ASSERT_LE(0, ruleset_fd_l1);
+ ASSERT_LE(0, ruleset_fd_l2);
+ ASSERT_LE(0, ruleset_fd_l3);
+
+ enforce_ruleset(_metadata, ruleset_fd_l1);
+ EXPECT_EQ(0, close(ruleset_fd_l1));
+
+ bind_s1d3_fd = open(bind_dir_s1d3, O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, bind_s1d3_fd);
+
+ /* Tests access is possible before we move. */
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file2_name, O_RDONLY));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, "..", O_RDONLY | O_DIRECTORY));
+
+ /* Makes it disconnected. */
+ ASSERT_EQ(0, rename(dir_s1d3, dir_s4d1))
+ {
+ TH_LOG("Failed to rename %s to %s: %s", dir_s1d3, dir_s4d1,
+ strerror(errno));
+ }
+
+ /* Tests that access is still possible. */
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file2_name, O_RDONLY));
+
+ /*
+ * Tests that ".." is not possible (not because of Landlock, but just
+ * because it's disconnected).
+ */
+ EXPECT_EQ(ENOENT,
+ test_open_rel(bind_s1d3_fd, "..", O_RDONLY | O_DIRECTORY));
+
+ /* This should still work with a narrower rule. */
+ enforce_ruleset(_metadata, ruleset_fd_l2);
+ EXPECT_EQ(0, close(ruleset_fd_l2));
+
+ EXPECT_EQ(0, test_open(file1_s4d1, O_RDONLY));
+ /*
+ * Accessing a file through a disconnected file descriptor can still be
+ * allowed by a rule tied to this file, even if it is no longer visible in
+ * its mount point.
+ */
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(EACCES, test_open_rel(bind_s1d3_fd, file2_name, O_RDONLY));
+
+ enforce_ruleset(_metadata, ruleset_fd_l3);
+ EXPECT_EQ(0, close(ruleset_fd_l3));
+
+ EXPECT_EQ(EACCES, test_open(file1_s4d1, O_RDONLY));
+ /*
+ * Accessing a file through a disconnected file descriptor can still be
+ * allowed by a rule tied to the original mount point, even if it is no
+ * longer visible in its mount point.
+ */
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(EACCES, test_open_rel(bind_s1d3_fd, file2_name, O_RDONLY));
+}
+
+/*
+ * Test that renameat with disconnected paths works under Landlock. This test
+ * moves s1d3 to s4d2, so that we can have a rule allowing refers on the move
+ * target's immediate parent.
+ */
+TEST_F_FORK(layout1_bind, path_disconnected_rename)
+{
+ const struct rule layer1[] = {
+ {
+ .path = dir_s1d2,
+ .access = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_MAKE_DIR |
+ LANDLOCK_ACCESS_FS_REMOVE_DIR |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_REMOVE_FILE |
+ LANDLOCK_ACCESS_FS_READ_FILE,
+ },
+ {
+ .path = dir_s4d1,
+ .access = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_MAKE_DIR |
+ LANDLOCK_ACCESS_FS_REMOVE_DIR |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_REMOVE_FILE |
+ LANDLOCK_ACCESS_FS_READ_FILE,
+ },
+ {}
+ };
+
+ /* This layer only handles LANDLOCK_ACCESS_FS_READ_FILE. */
+ const struct rule layer2_only_s1d2[] = {
+ {
+ .path = dir_s1d2,
+ .access = LANDLOCK_ACCESS_FS_READ_FILE,
+ },
+ {},
+ };
+ int ruleset_fd_l1, ruleset_fd_l2;
+ pid_t child_pid;
+ int bind_s1d3_fd, status;
+
+ ASSERT_EQ(0, mkdir(dir_s4d1, 0755))
+ {
+ TH_LOG("Failed to create %s: %s", dir_s4d1, strerror(errno));
+ }
+ ruleset_fd_l1 = create_ruleset(_metadata, ACCESS_ALL, layer1);
+ ruleset_fd_l2 = create_ruleset(_metadata, LANDLOCK_ACCESS_FS_READ_FILE,
+ layer2_only_s1d2);
+ ASSERT_LE(0, ruleset_fd_l1);
+ ASSERT_LE(0, ruleset_fd_l2);
+
+ enforce_ruleset(_metadata, ruleset_fd_l1);
+ EXPECT_EQ(0, close(ruleset_fd_l1));
+
+ bind_s1d3_fd = open(bind_dir_s1d3, O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, bind_s1d3_fd);
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+
+ /* Tests ENOENT priority over EACCES for disconnected directory. */
+ EXPECT_EQ(EACCES, test_open_rel(bind_s1d3_fd, "..", O_DIRECTORY));
+ ASSERT_EQ(0, rename(dir_s1d3, dir_s4d2))
+ {
+ TH_LOG("Failed to rename %s to %s: %s", dir_s1d3, dir_s4d2,
+ strerror(errno));
+ }
+ EXPECT_EQ(ENOENT, test_open_rel(bind_s1d3_fd, "..", O_DIRECTORY));
+
+ /*
+ * The file is no longer under s1d2 but we should still be able to access it
+ * with layer 2 because its mount point is evaluated as the first valid
+ * directory because it was initially a parent. Do a fork to test this so
+ * we don't prevent ourselves from renaming it back later.
+ */
+ child_pid = fork();
+ ASSERT_LE(0, child_pid);
+ if (child_pid == 0) {
+ enforce_ruleset(_metadata, ruleset_fd_l2);
+ EXPECT_EQ(0, close(ruleset_fd_l2));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(EACCES, test_open(file1_s4d2, O_RDONLY));
+
+ /*
+ * Tests that access widening checks indeed prevents us from renaming it
+ * back.
+ */
+ EXPECT_EQ(-1, rename(dir_s4d2, dir_s1d3));
+ EXPECT_EQ(EXDEV, errno);
+
+ /*
+ * Including through the now disconnected fd (but it should return
+ * EXDEV).
+ */
+ EXPECT_EQ(-1, renameat(bind_s1d3_fd, file1_name, AT_FDCWD,
+ file1_s2d2));
+ EXPECT_EQ(EXDEV, errno);
+ _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
+ return;
+ }
+
+ EXPECT_EQ(child_pid, waitpid(child_pid, &status, 0));
+ EXPECT_EQ(1, WIFEXITED(status));
+ EXPECT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
+
+ ASSERT_EQ(0, rename(dir_s4d2, dir_s1d3))
+ {
+ TH_LOG("Failed to rename %s back to %s: %s", dir_s4d1, dir_s1d3,
+ strerror(errno));
+ }
+
+ /* Now checks that we can access it under l2. */
+ child_pid = fork();
+ ASSERT_LE(0, child_pid);
+ if (child_pid == 0) {
+ enforce_ruleset(_metadata, ruleset_fd_l2);
+ EXPECT_EQ(0, close(ruleset_fd_l2));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(0, test_open(file1_s1d3, O_RDONLY));
+ _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
+ return;
+ }
+
+ EXPECT_EQ(child_pid, waitpid(child_pid, &status, 0));
+ EXPECT_EQ(1, WIFEXITED(status));
+ EXPECT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
+
+ /*
+ * Also test that we can rename via a disconnected path. We move the
+ * dir back to the disconnected place first, then we rename file1 to
+ * file2 through our dir fd.
+ */
+ ASSERT_EQ(0, rename(dir_s1d3, dir_s4d2))
+ {
+ TH_LOG("Failed to rename %s to %s: %s", dir_s1d3, dir_s4d2,
+ strerror(errno));
+ }
+ ASSERT_EQ(0,
+ renameat(bind_s1d3_fd, file1_name, bind_s1d3_fd, file2_name))
+ {
+ TH_LOG("Failed to rename %s to %s within disconnected %s: %s",
+ file1_name, file2_name, bind_dir_s1d3, strerror(errno));
+ }
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file2_name, O_RDONLY));
+ ASSERT_EQ(0, renameat(bind_s1d3_fd, file2_name, AT_FDCWD, file1_s2d2))
+ {
+ TH_LOG("Failed to rename %s to %s through disconnected %s: %s",
+ file2_name, file1_s2d2, bind_dir_s1d3, strerror(errno));
+ }
+ EXPECT_EQ(0, test_open(file1_s2d2, O_RDONLY));
+ EXPECT_EQ(0, test_open(file1_s1d2, O_RDONLY));
+
+ /* Move it back using the disconnected path as the target. */
+ ASSERT_EQ(0, renameat(AT_FDCWD, file1_s2d2, bind_s1d3_fd, file1_name))
+ {
+ TH_LOG("Failed to rename %s to %s through disconnected %s: %s",
+ file1_s1d2, file1_name, bind_dir_s1d3, strerror(errno));
+ }
+
+ /* Now make it connected again. */
+ ASSERT_EQ(0, rename(dir_s4d2, dir_s1d3))
+ {
+ TH_LOG("Failed to rename %s back to %s: %s", dir_s4d2, dir_s1d3,
+ strerror(errno));
+ }
+
+ /* Checks again that we can access it under l2. */
+ enforce_ruleset(_metadata, ruleset_fd_l2);
+ EXPECT_EQ(0, close(ruleset_fd_l2));
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+ EXPECT_EQ(0, test_open(file1_s1d3, O_RDONLY));
+}
+
+/*
+ * Test that linkat(2) with disconnected paths works under Landlock. This
+ * test moves s1d3 to s4d1.
+ */
+TEST_F_FORK(layout1_bind, path_disconnected_link)
+{
+ /* Ruleset to be applied after renaming s1d3 to s4d1. */
+ const struct rule layer1[] = {
+ {
+ .path = dir_s4d1,
+ .access = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_REMOVE_FILE,
+ },
+ {
+ .path = dir_s2d2,
+ .access = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_REMOVE_FILE,
+ },
+ {}
+ };
+ int ruleset_fd, bind_s1d3_fd;
+
+ /* Removes unneeded files created by layout1, otherwise it will EEXIST. */
+ ASSERT_EQ(0, unlink(file1_s1d2));
+ ASSERT_EQ(0, unlink(file2_s1d3));
+
+ bind_s1d3_fd = open(bind_dir_s1d3, O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, bind_s1d3_fd);
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY));
+
+ /* Disconnects bind_s1d3_fd. */
+ ASSERT_EQ(0, rename(dir_s1d3, dir_s4d1))
+ {
+ TH_LOG("Failed to rename %s to %s: %s", dir_s1d3, dir_s4d1,
+ strerror(errno));
+ }
+
+ /* Need this later to test different parent link. */
+ ASSERT_EQ(0, mkdir(dir_s4d2, 0755))
+ {
+ TH_LOG("Failed to create %s: %s", dir_s4d2, strerror(errno));
+ }
+
+ ruleset_fd = create_ruleset(_metadata, ACCESS_ALL, layer1);
+ ASSERT_LE(0, ruleset_fd);
+ enforce_ruleset(_metadata, ruleset_fd);
+ EXPECT_EQ(0, close(ruleset_fd));
+
+ /* From disconnected to connected. */
+ ASSERT_EQ(0, linkat(bind_s1d3_fd, file1_name, AT_FDCWD, file1_s2d2, 0))
+ {
+ TH_LOG("Failed to link %s to %s via disconnected %s: %s",
+ file1_name, file1_s2d2, bind_dir_s1d3, strerror(errno));
+ }
+
+ /* Tests that we can access via the new link... */
+ EXPECT_EQ(0, test_open(file1_s2d2, O_RDONLY))
+ {
+ TH_LOG("Failed to open newly linked %s: %s", file1_s2d2,
+ strerror(errno));
+ }
+
+ /* ...as well as the old one. */
+ EXPECT_EQ(0, test_open(file1_s4d1, O_RDONLY))
+ {
+ TH_LOG("Failed to open original %s: %s", file1_s4d1,
+ strerror(errno));
+ }
+
+ /* From connected to disconnected. */
+ ASSERT_EQ(0, unlink(file1_s4d1));
+ ASSERT_EQ(0, linkat(AT_FDCWD, file1_s2d2, bind_s1d3_fd, file2_name, 0))
+ {
+ TH_LOG("Failed to link %s to %s via disconnected %s: %s",
+ file1_s2d2, file2_name, bind_dir_s1d3, strerror(errno));
+ }
+ EXPECT_EQ(0, test_open(file2_s4d1, O_RDONLY));
+ ASSERT_EQ(0, unlink(file1_s2d2));
+
+ /* From disconnected to disconnected (same parent). */
+ ASSERT_EQ(0,
+ linkat(bind_s1d3_fd, file2_name, bind_s1d3_fd, file1_name, 0))
+ {
+ TH_LOG("Failed to link %s to %s within disconnected %s: %s",
+ file2_name, file1_name, bind_dir_s1d3, strerror(errno));
+ }
+ EXPECT_EQ(0, test_open(file1_s4d1, O_RDONLY))
+ {
+ TH_LOG("Failed to open newly linked %s: %s", file1_s4d1,
+ strerror(errno));
+ }
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, file1_name, O_RDONLY))
+ {
+ TH_LOG("Failed to open %s through newly created link under disconnected path: %s",
+ file1_name, strerror(errno));
+ }
+ ASSERT_EQ(0, unlink(file2_s4d1));
+
+ /* From disconnected to disconnected (different parent). */
+ ASSERT_EQ(0,
+ linkat(bind_s1d3_fd, file1_name, bind_s1d3_fd, "s4d2/f1", 0))
+ {
+ TH_LOG("Failed to link %s to %s within disconnected %s: %s",
+ file1_name, "s4d2/f1", bind_dir_s1d3, strerror(errno));
+ }
+ EXPECT_EQ(0, test_open(file1_s4d2, O_RDONLY))
+ {
+ TH_LOG("Failed to open %s after link: %s", file1_s4d2,
+ strerror(errno));
+ }
+ EXPECT_EQ(0, test_open_rel(bind_s1d3_fd, "s4d2/f1", O_RDONLY))
+ {
+ TH_LOG("Failed to open %s through disconnected path after link: %s",
+ "s4d2/f1", strerror(errno));
+ }
+}
+
#define LOWER_BASE TMP_DIR "/lower"
#define LOWER_DATA LOWER_BASE "/data"
static const char lower_fl1[] = LOWER_DATA "/fl1";
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites
2026-09-06 13:32 ` Sasha Levin
` (2 preceding siblings ...)
2026-09-17 15:00 ` [PATCH 6.1.y 2/4] selftests/landlock: Add tests for access through disconnected paths Mickaël Salaün
@ 2026-09-17 15:00 ` Mickaël Salaün
2026-09-18 0:52 ` Sasha Levin
2026-09-17 15:00 ` [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation Mickaël Salaün
4 siblings, 1 reply; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-17 15:00 UTC (permalink / raw)
To: stable
Cc: Mickaël Salaün, Sasha Levin, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
[ Upstream commit 54f9baf537b0a091adad860ec92e3e18e0a0754c ]
Test disconnected directories with two test suites
(layout4_disconnected_leafs and layout5_disconnected_branch) and 43
variants to cover the main corner cases.
These tests are complementary to the previous commit.
Add test_renameat() and test_exchangeat() helpers.
Test coverage for security/landlock is 92.1% of 1927 lines according to
LLVM 20.
Cc: Günther Noack <gnoack@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://lore.kernel.org/r/20251128172200.760753-5-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
[mic: Backport: skip empty rules, use the older fixture teardown, and
explicitly detach nested mounts]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
tools/testing/selftests/landlock/fs_test.c | 1064 ++++++++++++++++++++
1 file changed, 1064 insertions(+)
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 805fd1f9bc89..d4b3de74eb6b 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -237,6 +237,16 @@ static void cleanup_layout(struct __test_metadata *const _metadata)
EXPECT_EQ(0, remove_path(TMP_DIR));
}
+static void
+cleanup_layout_with_nested_mounts(struct __test_metadata *const _metadata)
+{
+ set_cap(_metadata, CAP_SYS_ADMIN);
+ /* Also detaches disconnected bind mounts nested below TMP_DIR. */
+ EXPECT_EQ(0, umount2(TMP_DIR, MNT_DETACH));
+ clear_cap(_metadata, CAP_SYS_ADMIN);
+ EXPECT_EQ(0, remove_path(TMP_DIR));
+}
+
static void create_layout1(struct __test_metadata *const _metadata)
{
create_file(_metadata, file1_s1d1);
@@ -595,6 +605,9 @@ static int create_ruleset(struct __test_metadata *const _metadata,
}
for (i = 0; rules[i].path; i++) {
+ if (!rules[i].access)
+ continue;
+
add_path_beneath(_metadata, ruleset_fd, rules[i].access,
rules[i].path);
}
@@ -1889,6 +1902,22 @@ static int test_exchange(const char *const oldpath, const char *const newpath)
return 0;
}
+static int test_renameat(int olddirfd, const char *oldpath, int newdirfd,
+ const char *newpath)
+{
+ if (renameat2(olddirfd, oldpath, newdirfd, newpath, 0))
+ return errno;
+ return 0;
+}
+
+static int test_exchangeat(int olddirfd, const char *oldpath, int newdirfd,
+ const char *newpath)
+{
+ if (renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_EXCHANGE))
+ return errno;
+ return 0;
+}
+
TEST_F_FORK(layout1, rename_file)
{
const struct rule rules[] = {
@@ -3894,6 +3923,1041 @@ TEST_F_FORK(layout1_bind, path_disconnected_link)
}
}
+/*
+ * layout4_disconnected_leafs with bind mount and renames:
+ *
+ * tmp
+ * ├── s1d1
+ * │ └── s1d2 [source of the bind mount]
+ * │ ├── s1d31
+ * │ │ └── s1d41 [now renamed beneath s3d1]
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d32
+ * │ └── s1d42 [now renamed beneath s4d1]
+ * │ ├── f3
+ * │ └── f4
+ * ├── s2d1
+ * │ └── s2d2 [bind mount of s1d2]
+ * │ ├── s1d31
+ * │ │ └── s1d41 [opened FD, now renamed beneath s3d1]
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d32
+ * │ └── s1d42 [opened FD, now renamed beneath s4d1]
+ * │ ├── f3
+ * │ └── f4
+ * ├── s3d1
+ * │ └── s1d41 [renamed here]
+ * │ ├── f1
+ * │ └── f2
+ * └── s4d1
+ * └── s1d42 [renamed here]
+ * ├── f3
+ * └── f4
+ */
+/* clang-format off */
+FIXTURE(layout4_disconnected_leafs) {
+ int s2d2_fd;
+};
+/* clang-format on */
+
+FIXTURE_SETUP(layout4_disconnected_leafs)
+{
+ prepare_layout(_metadata);
+
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d31/s1d41/f1");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d31/s1d41/f2");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d32/s1d42/f3");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d32/s1d42/f4");
+ create_directory(_metadata, TMP_DIR "/s2d1/s2d2");
+ create_directory(_metadata, TMP_DIR "/s3d1");
+ create_directory(_metadata, TMP_DIR "/s4d1");
+
+ self->s2d2_fd =
+ open(TMP_DIR "/s2d1/s2d2", O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, self->s2d2_fd);
+
+ set_cap(_metadata, CAP_SYS_ADMIN);
+ ASSERT_EQ(0, mount(TMP_DIR "/s1d1/s1d2", TMP_DIR "/s2d1/s2d2", NULL,
+ MS_BIND, NULL));
+ clear_cap(_metadata, CAP_SYS_ADMIN);
+}
+
+FIXTURE_TEARDOWN(layout4_disconnected_leafs)
+{
+ /* Teardown runs before this mount namespace exits. */
+
+ /* Removes files after renames. */
+ remove_path(TMP_DIR "/s3d1/s1d41/f1");
+ remove_path(TMP_DIR "/s3d1/s1d41/f2");
+ remove_path(TMP_DIR "/s4d1/s1d42/f1");
+ remove_path(TMP_DIR "/s4d1/s1d42/f3");
+ remove_path(TMP_DIR "/s4d1/s1d42/f4");
+ remove_path(TMP_DIR "/s4d1/s1d42/f5");
+
+ cleanup_layout_with_nested_mounts(_metadata);
+}
+
+FIXTURE_VARIANT(layout4_disconnected_leafs)
+{
+ /*
+ * Parent of the bind mount source. It should always be ignored when
+ * testing against files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_s1d1;
+ /*
+ * Source of bind mount (to s2d2). It should always be enforced when
+ * testing against files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_s1d2;
+ /*
+ * Original parent of s1d41. It should always be ignored when testing
+ * against files under the s1d41 disconnected directory.
+ */
+ const __u64 allowed_s1d31;
+ /*
+ * Original parent of s1d42. It should always be ignored when testing
+ * against files under the s1d42 disconnected directory.
+ */
+ const __u64 allowed_s1d32;
+ /*
+ * Opened and disconnected source directory. It should always be enforced
+ * when testing against files under the s1d41 disconnected directory.
+ */
+ const __u64 allowed_s1d41;
+ /*
+ * Opened and disconnected source directory. It should always be enforced
+ * when testing against files under the s1d42 disconnected directory.
+ */
+ const __u64 allowed_s1d42;
+ /*
+ * File in the s1d41 disconnected directory. It should always be enforced
+ * when testing against itself under the s1d41 disconnected directory.
+ */
+ const __u64 allowed_f1;
+ /*
+ * File in the s1d41 disconnected directory. It should always be enforced
+ * when testing against itself under the s1d41 disconnected directory.
+ */
+ const __u64 allowed_f2;
+ /*
+ * File in the s1d42 disconnected directory. It should always be enforced
+ * when testing against itself under the s1d42 disconnected directory.
+ */
+ const __u64 allowed_f3;
+ /*
+ * Parent of the bind mount destination. It should always be enforced when
+ * testing against files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_s2d1;
+ /*
+ * Directory covered by the bind mount. It should always be ignored when
+ * testing against files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_s2d2;
+ /*
+ * New parent of the renamed s1d41. It should always be ignored when
+ * testing against files under the s1d41 disconnected directory.
+ */
+ const __u64 allowed_s3d1;
+ /*
+ * New parent of the renamed s1d42. It should always be ignored when
+ * testing against files under the s1d42 disconnected directory.
+ */
+ const __u64 allowed_s4d1;
+
+ /* Expected result of the call to open([fd:s1d41]/f1, O_RDONLY). */
+ const int expected_read_result;
+ /* Expected result of the call to renameat([fd:s1d41]/f1, [fd:s1d42]/f1). */
+ const int expected_rename_result;
+ /*
+ * Expected result of the call to renameat([fd:s1d41]/f2, [fd:s1d42]/f3,
+ * RENAME_EXCHANGE).
+ */
+ const int expected_exchange_result;
+ /* Expected result of the call to renameat([fd:s1d42]/f4, [fd:s1d42]/f5). */
+ const int expected_same_dir_rename_result;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d1_mount_src_parent) {
+ /* clang-format on */
+ .allowed_s1d1 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d2_mount_src_refer) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d2_mount_src_create) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d2_mount_src_rename) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d31_s1d32_old_parent) {
+ /* clang-format on */
+ .allowed_s1d31 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s1d32 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d41_s1d42_disconnected_refer) {
+ /* clang-format on */
+ .allowed_s1d41 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE,
+ .allowed_s1d42 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d41_s1d42_disconnected_create) {
+ /* clang-format on */
+ .allowed_s1d41 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s1d42 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d41_s1d42_disconnected_rename_even) {
+ /* clang-format on */
+ .allowed_s1d41 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s1d42 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* The destination directory has more access right. */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d41_s1d42_disconnected_rename_more) {
+ /* clang-format on */
+ .allowed_s1d41 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s1d42 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_EXECUTE,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ /* Access denied. */
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* The destination directory has less access right. */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s1d41_s1d42_disconnected_rename_less) {
+ /* clang-format on */
+ .allowed_s1d41 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_EXECUTE,
+ .allowed_s1d42 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ /* Access allowed. */
+ .expected_rename_result = 0,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s2d1_mount_dst_parent_create) {
+ /* clang-format on */
+ .allowed_s2d1 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s2d1_mount_dst_parent_refer) {
+ /* clang-format on */
+ .allowed_s2d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s2d1_mount_dst_parent_mini) {
+ /* clang-format on */
+ .allowed_s2d1 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s2d2_covered_by_mount) {
+ /* clang-format on */
+ .allowed_s2d2 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* Tests collect_domain_accesses(). */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s3d1_s4d1_new_parent_refer) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s3d1_s4d1_new_parent_create) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs,
+ s3d1_s4d1_disconnected_rename_even){
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* The destination directory has more access right. */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s3d1_s4d1_disconnected_rename_more) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_EXECUTE,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ /* Access denied. */
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* The destination directory has less access right. */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, s3d1_s4d1_disconnected_rename_less) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG |
+ LANDLOCK_ACCESS_FS_EXECUTE,
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ /* Access allowed. */
+ .expected_rename_result = 0,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout4_disconnected_leafs, f1_f2_f3) {
+ /* clang-format on */
+ .allowed_f1 = LANDLOCK_ACCESS_FS_READ_FILE,
+ .allowed_f2 = LANDLOCK_ACCESS_FS_READ_FILE,
+ .allowed_f3 = LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+TEST_F_FORK(layout4_disconnected_leafs, read_rename_exchange)
+{
+ const __u64 handled_access =
+ LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE | LANDLOCK_ACCESS_FS_MAKE_REG;
+ const struct rule rules[] = {
+ {
+ .path = TMP_DIR "/s1d1",
+ .access = variant->allowed_s1d1,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2",
+ .access = variant->allowed_s1d2,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d31",
+ .access = variant->allowed_s1d31,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d32",
+ .access = variant->allowed_s1d32,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d31/s1d41",
+ .access = variant->allowed_s1d41,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d32/s1d42",
+ .access = variant->allowed_s1d42,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d31/s1d41/f1",
+ .access = variant->allowed_f1,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d31/s1d41/f2",
+ .access = variant->allowed_f2,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d32/s1d42/f3",
+ .access = variant->allowed_f3,
+ },
+ {
+ .path = TMP_DIR "/s2d1",
+ .access = variant->allowed_s2d1,
+ },
+ /* s2d2_fd */
+ {
+ .path = TMP_DIR "/s3d1",
+ .access = variant->allowed_s3d1,
+ },
+ {
+ .path = TMP_DIR "/s4d1",
+ .access = variant->allowed_s4d1,
+ },
+ {},
+ };
+ int ruleset_fd, s1d41_bind_fd, s1d42_bind_fd;
+
+ ruleset_fd = create_ruleset(_metadata, handled_access, rules);
+ ASSERT_LE(0, ruleset_fd);
+
+ /* Adds rule for the covered directory. */
+ if (variant->allowed_s2d2) {
+ ASSERT_EQ(0, landlock_add_rule(
+ ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+ &(struct landlock_path_beneath_attr){
+ .parent_fd = self->s2d2_fd,
+ .allowed_access =
+ variant->allowed_s2d2,
+ },
+ 0));
+ }
+ EXPECT_EQ(0, close(self->s2d2_fd));
+
+ s1d41_bind_fd = open(TMP_DIR "/s2d1/s2d2/s1d31/s1d41",
+ O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, s1d41_bind_fd);
+ s1d42_bind_fd = open(TMP_DIR "/s2d1/s2d2/s1d32/s1d42",
+ O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, s1d42_bind_fd);
+
+ /* Disconnects and checks source and destination directories. */
+ EXPECT_EQ(0, test_open_rel(s1d41_bind_fd, "..", O_DIRECTORY));
+ EXPECT_EQ(0, test_open_rel(s1d42_bind_fd, "..", O_DIRECTORY));
+ /* Renames to make it accessible through s3d1/s1d41 */
+ ASSERT_EQ(0, test_renameat(AT_FDCWD, TMP_DIR "/s1d1/s1d2/s1d31/s1d41",
+ AT_FDCWD, TMP_DIR "/s3d1/s1d41"));
+ /* Renames to make it accessible through s4d1/s1d42 */
+ ASSERT_EQ(0, test_renameat(AT_FDCWD, TMP_DIR "/s1d1/s1d2/s1d32/s1d42",
+ AT_FDCWD, TMP_DIR "/s4d1/s1d42"));
+ EXPECT_EQ(ENOENT, test_open_rel(s1d41_bind_fd, "..", O_DIRECTORY));
+ EXPECT_EQ(ENOENT, test_open_rel(s1d42_bind_fd, "..", O_DIRECTORY));
+
+ enforce_ruleset(_metadata, ruleset_fd);
+ EXPECT_EQ(0, close(ruleset_fd));
+
+ EXPECT_EQ(variant->expected_read_result,
+ test_open_rel(s1d41_bind_fd, "f1", O_RDONLY));
+
+ EXPECT_EQ(variant->expected_rename_result,
+ test_renameat(s1d41_bind_fd, "f1", s1d42_bind_fd, "f1"));
+ EXPECT_EQ(variant->expected_exchange_result,
+ test_exchangeat(s1d41_bind_fd, "f2", s1d42_bind_fd, "f3"));
+
+ EXPECT_EQ(variant->expected_same_dir_rename_result,
+ test_renameat(s1d42_bind_fd, "f4", s1d42_bind_fd, "f5"));
+}
+
+/*
+ * layout5_disconnected_branch before rename:
+ *
+ * tmp
+ * ├── s1d1
+ * │ └── s1d2 [source of the first bind mount]
+ * │ └── s1d3
+ * │ ├── s1d41
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d42
+ * │ ├── f3
+ * │ └── f4
+ * ├── s2d1
+ * │ └── s2d2 [source of the second bind mount]
+ * │ └── s2d3
+ * │ └── s2d4 [first s1d2 bind mount]
+ * │ └── s1d3
+ * │ ├── s1d41
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d42
+ * │ ├── f3
+ * │ └── f4
+ * ├── s3d1
+ * │ └── s3d2 [second s2d2 bind mount]
+ * │ └── s2d3
+ * │ └── s2d4 [first s1d2 bind mount]
+ * │ └── s1d3
+ * │ ├── s1d41
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d42
+ * │ ├── f3
+ * │ └── f4
+ * └── s4d1
+ *
+ * After rename:
+ *
+ * tmp
+ * ├── s1d1
+ * │ └── s1d2 [source of the first bind mount]
+ * │ └── s1d3
+ * │ ├── s1d41
+ * │ │ ├── f1
+ * │ │ └── f2
+ * │ └── s1d42
+ * │ ├── f3
+ * │ └── f4
+ * ├── s2d1
+ * │ └── s2d2 [source of the second bind mount]
+ * ├── s3d1
+ * │ └── s3d2 [second s2d2 bind mount]
+ * └── s4d1
+ * └── s2d3 [renamed here]
+ * └── s2d4 [first s1d2 bind mount]
+ * └── s1d3
+ * ├── s1d41
+ * │ ├── f1
+ * │ └── f2
+ * └── s1d42
+ * ├── f3
+ * └── f4
+ *
+ * Decision path for access from the s3d1/s3d2/s2d3/s2d4/s1d3 file descriptor:
+ * 1. first bind mount: s1d3 -> s1d2
+ * 2. second bind mount: s2d3
+ * 3. tmp mount: s4d1 -> tmp [disconnected branch]
+ * 4. second bind mount: s2d2
+ * 5. tmp mount: s3d1 -> tmp
+ * 6. parent mounts: [...] -> /
+ *
+ * The s4d1 directory is evaluated even if it is not in the s2d2 mount.
+ */
+
+/* clang-format off */
+FIXTURE(layout5_disconnected_branch) {
+ int s2d4_fd, s3d2_fd;
+};
+/* clang-format on */
+
+FIXTURE_SETUP(layout5_disconnected_branch)
+{
+ prepare_layout(_metadata);
+
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d3/s1d41/f1");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d3/s1d41/f2");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f3");
+ create_file(_metadata, TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f4");
+ create_directory(_metadata, TMP_DIR "/s2d1/s2d2/s2d3/s2d4");
+ create_directory(_metadata, TMP_DIR "/s3d1/s3d2");
+ create_directory(_metadata, TMP_DIR "/s4d1");
+
+ self->s2d4_fd = open(TMP_DIR "/s2d1/s2d2/s2d3/s2d4",
+ O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, self->s2d4_fd);
+
+ self->s3d2_fd =
+ open(TMP_DIR "/s3d1/s3d2", O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, self->s3d2_fd);
+
+ set_cap(_metadata, CAP_SYS_ADMIN);
+ ASSERT_EQ(0, mount(TMP_DIR "/s1d1/s1d2", TMP_DIR "/s2d1/s2d2/s2d3/s2d4",
+ NULL, MS_BIND, NULL));
+ ASSERT_EQ(0, mount(TMP_DIR "/s2d1/s2d2", TMP_DIR "/s3d1/s3d2", NULL,
+ MS_BIND | MS_REC, NULL));
+ clear_cap(_metadata, CAP_SYS_ADMIN);
+}
+
+FIXTURE_TEARDOWN(layout5_disconnected_branch)
+{
+ /* Teardown runs before this mount namespace exits. */
+
+ /* Removes files after renames. */
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d41/f1");
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d41/f2");
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f1");
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f3");
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f4");
+ remove_path(TMP_DIR "/s1d1/s1d2/s1d3/s1d42/f5");
+
+ cleanup_layout_with_nested_mounts(_metadata);
+}
+
+FIXTURE_VARIANT(layout5_disconnected_branch)
+{
+ /*
+ * Parent of all files. It should always be enforced when testing against
+ * files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_base;
+ /*
+ * Parent of the first bind mount source. It should always be ignored when
+ * testing against files under the s1d41 or s1d42 disconnected directories.
+ */
+ const __u64 allowed_s1d1;
+ const __u64 allowed_s1d2;
+ const __u64 allowed_s1d3;
+ const __u64 allowed_s2d1;
+ const __u64 allowed_s2d2;
+ const __u64 allowed_s2d3;
+ const __u64 allowed_s2d4;
+ const __u64 allowed_s3d1;
+ const __u64 allowed_s3d2;
+ const __u64 allowed_s4d1;
+
+ /* Expected result of the call to open([fd:s1d3]/s1d41/f1, O_RDONLY). */
+ const int expected_read_result;
+ /*
+ * Expected result of the call to renameat([fd:s1d3]/s1d41/f1,
+ * [fd:s1d3]/s1d42/f1).
+ */
+ const int expected_rename_result;
+ /*
+ * Expected result of the call to renameat([fd:s1d3]/s1d41/f2,
+ * [fd:s1d3]/s1d42/f3, RENAME_EXCHANGE).
+ */
+ const int expected_exchange_result;
+ /*
+ * Expected result of the call to renameat([fd:s1d3]/s1d42/f4,
+ * [fd:s1d3]/s1d42/f5).
+ */
+ const int expected_same_dir_rename_result;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d1_mount1_src_parent) {
+ /* clang-format on */
+ .allowed_s1d1 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d2_mount1_src_refer) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d2_mount1_src_create) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d2_mount1_src_rename) {
+ /* clang-format on */
+ .allowed_s1d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d3_fd_refer) {
+ /* clang-format on */
+ .allowed_s1d3 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d3_fd_create) {
+ /* clang-format on */
+ .allowed_s1d3 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d3_fd_rename) {
+ /* clang-format on */
+ .allowed_s1d3 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s1d3_fd_full) {
+ /* clang-format on */
+ .allowed_s1d3 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d1_mount2_src_parent) {
+ /* clang-format on */
+ .allowed_s2d1 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d2_mount2_src_refer) {
+ /* clang-format on */
+ .allowed_s2d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d2_mount2_src_create) {
+ /* clang-format on */
+ .allowed_s2d2 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d2_mount2_src_rename) {
+ /* clang-format on */
+ .allowed_s2d2 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d3_mount1_dst_parent_refer) {
+ /* clang-format on */
+ .allowed_s2d3 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d3_mount1_dst_parent_create) {
+ /* clang-format on */
+ .allowed_s2d3 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d3_mount1_dst_parent_rename) {
+ /* clang-format on */
+ .allowed_s2d3 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s2d4_mount1_dst) {
+ /* clang-format on */
+ .allowed_s2d4 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s3d1_mount2_dst_parent_refer) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s3d1_mount2_dst_parent_create) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s3d1_mount2_dst_parent_rename) {
+ /* clang-format on */
+ .allowed_s3d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s3d2_mount1_dst) {
+ /* clang-format on */
+ .allowed_s3d2 = LANDLOCK_ACCESS_FS_REFER |
+ LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s4d1_rename_parent_refer) {
+ /* clang-format on */
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = EACCES,
+ .expected_rename_result = EACCES,
+ .expected_exchange_result = EACCES,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s4d1_rename_parent_create) {
+ /* clang-format on */
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = 0,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = EXDEV,
+ .expected_exchange_result = EXDEV,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(layout5_disconnected_branch, s4d1_rename_parent_rename) {
+ /* clang-format on */
+ .allowed_s4d1 = LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_MAKE_REG,
+ .expected_read_result = EACCES,
+ .expected_same_dir_rename_result = 0,
+ .expected_rename_result = 0,
+ .expected_exchange_result = 0,
+};
+
+TEST_F_FORK(layout5_disconnected_branch, read_rename_exchange)
+{
+ const __u64 handled_access =
+ LANDLOCK_ACCESS_FS_REFER | LANDLOCK_ACCESS_FS_READ_FILE |
+ LANDLOCK_ACCESS_FS_EXECUTE | LANDLOCK_ACCESS_FS_MAKE_REG;
+ const struct rule rules[] = {
+ {
+ .path = TMP_DIR "/s1d1",
+ .access = variant->allowed_s1d1,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2",
+ .access = variant->allowed_s1d2,
+ },
+ {
+ .path = TMP_DIR "/s1d1/s1d2/s1d3",
+ .access = variant->allowed_s1d3,
+ },
+ {
+ .path = TMP_DIR "/s2d1",
+ .access = variant->allowed_s2d1,
+ },
+ {
+ .path = TMP_DIR "/s2d1/s2d2",
+ .access = variant->allowed_s2d2,
+ },
+ {
+ .path = TMP_DIR "/s2d1/s2d2/s2d3",
+ .access = variant->allowed_s2d3,
+ },
+ /* s2d4_fd */
+ {
+ .path = TMP_DIR "/s3d1",
+ .access = variant->allowed_s3d1,
+ },
+ /* s3d2_fd */
+ {
+ .path = TMP_DIR "/s4d1",
+ .access = variant->allowed_s4d1,
+ },
+ {},
+ };
+ int ruleset_fd, s1d3_bind_fd;
+
+ ruleset_fd = create_ruleset(_metadata, handled_access, rules);
+ ASSERT_LE(0, ruleset_fd);
+
+ /* Adds rules for the covered directories. */
+ if (variant->allowed_s2d4) {
+ ASSERT_EQ(0, landlock_add_rule(
+ ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+ &(struct landlock_path_beneath_attr){
+ .parent_fd = self->s2d4_fd,
+ .allowed_access =
+ variant->allowed_s2d4,
+ },
+ 0));
+ }
+ EXPECT_EQ(0, close(self->s2d4_fd));
+
+ if (variant->allowed_s3d2) {
+ ASSERT_EQ(0, landlock_add_rule(
+ ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+ &(struct landlock_path_beneath_attr){
+ .parent_fd = self->s3d2_fd,
+ .allowed_access =
+ variant->allowed_s3d2,
+ },
+ 0));
+ }
+ EXPECT_EQ(0, close(self->s3d2_fd));
+
+ s1d3_bind_fd = open(TMP_DIR "/s3d1/s3d2/s2d3/s2d4/s1d3",
+ O_DIRECTORY | O_PATH | O_CLOEXEC);
+ ASSERT_LE(0, s1d3_bind_fd);
+
+ /* Disconnects and checks source and destination directories. */
+ EXPECT_EQ(0, test_open_rel(s1d3_bind_fd, "..", O_DIRECTORY));
+ EXPECT_EQ(0, test_open_rel(s1d3_bind_fd, "../..", O_DIRECTORY));
+ /* Renames to make it accessible through s3d1/s1d41 */
+ ASSERT_EQ(0, test_renameat(AT_FDCWD, TMP_DIR "/s2d1/s2d2/s2d3",
+ AT_FDCWD, TMP_DIR "/s4d1/s2d3"));
+ EXPECT_EQ(0, test_open_rel(s1d3_bind_fd, "..", O_DIRECTORY));
+ EXPECT_EQ(ENOENT, test_open_rel(s1d3_bind_fd, "../..", O_DIRECTORY));
+
+ enforce_ruleset(_metadata, ruleset_fd);
+ EXPECT_EQ(0, close(ruleset_fd));
+
+ EXPECT_EQ(variant->expected_read_result,
+ test_open_rel(s1d3_bind_fd, "s1d41/f1", O_RDONLY));
+
+ EXPECT_EQ(variant->expected_rename_result,
+ test_renameat(s1d3_bind_fd, "s1d41/f1", s1d3_bind_fd,
+ "s1d42/f1"));
+ EXPECT_EQ(variant->expected_exchange_result,
+ test_exchangeat(s1d3_bind_fd, "s1d41/f2", s1d3_bind_fd,
+ "s1d42/f3"));
+
+ EXPECT_EQ(variant->expected_same_dir_rename_result,
+ test_renameat(s1d3_bind_fd, "s1d42/f4", s1d3_bind_fd,
+ "s1d42/f5"));
+}
+
#define LOWER_BASE TMP_DIR "/lower"
#define LOWER_DATA LOWER_BASE "/data"
static const char lower_fl1[] = LOWER_DATA "/fl1";
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation
2026-09-06 13:32 ` Sasha Levin
` (3 preceding siblings ...)
2026-09-17 15:00 ` [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites Mickaël Salaün
@ 2026-09-17 15:00 ` Mickaël Salaün
2026-09-18 19:45 ` Sasha Levin
4 siblings, 1 reply; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-17 15:00 UTC (permalink / raw)
To: stable
Cc: Mickaël Salaün, Sasha Levin, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
From: Günther Noack <gnoack@google.com>
[ Upstream commit ee890889b30b22f9a21636061def7a04e4f89380 ]
Add tests to check that whiteout object creation is guarded by
LANDLOCK_ACCESS_FS_MAKE_REG, in the cases where these are created from
userspace:
* Conventional creation with mknod()
* Linking or renaming an existing whiteout object
* renameat2() with RENAME_WHITEOUT,
which creates a new whiteout object in the source location
* renameat2() with RENAME_EXCHANGE,
with one of the renamed objects being a whiteout object
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://patch.msgid.link/20260813093157.1436894-4-gnoack@google.com
[mic: Update commit message as requested]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
[mic: Backport: adapt the tests to the older filesystem fixture and
ruleset helper]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
tools/testing/selftests/landlock/fs_test.c | 205 ++++++++++++++++++++-
1 file changed, 203 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index d4b3de74eb6b..0c3bfda86e87 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -70,6 +70,8 @@ static const char dir_s3d1[] = TMP_DIR "/s3d1";
/* dir_s3d2 is a mount point. */
static const char dir_s3d2[] = TMP_DIR "/s3d1/s3d2";
static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";
+static const char file1_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3/f1";
+static const char file1_s3d4[] = TMP_DIR "/s3d1/s3d2/s3d4/f1";
/*
* layout1 hierarchy:
@@ -266,7 +268,8 @@ static void create_layout1(struct __test_metadata *const _metadata)
ASSERT_EQ(0, mount("tmp", dir_s3d2, "tmpfs", 0, "size=4m,mode=700"));
clear_cap(_metadata, CAP_SYS_ADMIN);
- ASSERT_EQ(0, mkdir(dir_s3d3, 0700));
+ create_file(_metadata, file1_s3d3);
+ create_file(_metadata, file1_s3d4);
}
static void remove_layout1(struct __test_metadata *const _metadata)
@@ -283,7 +286,8 @@ static void remove_layout1(struct __test_metadata *const _metadata)
EXPECT_EQ(0, remove_path(file1_s2d2));
EXPECT_EQ(0, remove_path(file1_s2d1));
- EXPECT_EQ(0, remove_path(dir_s3d3));
+ EXPECT_EQ(0, remove_path(file1_s3d3));
+ EXPECT_EQ(0, remove_path(file1_s3d4));
set_cap(_metadata, CAP_SYS_ADMIN);
umount(dir_s3d2);
clear_cap(_metadata, CAP_SYS_ADMIN);
@@ -624,6 +628,27 @@ static void enforce_ruleset(struct __test_metadata *const _metadata,
}
}
+static void enforce_fs(struct __test_metadata *const _metadata,
+ const __u64 access_fs, const struct rule rules[])
+{
+ int ruleset_fd;
+
+ if (rules) {
+ ruleset_fd = create_ruleset(_metadata, access_fs, rules);
+ } else {
+ const struct landlock_ruleset_attr ruleset_attr = {
+ .handled_access_fs = access_fs,
+ };
+
+ 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));
+}
+
TEST_F_FORK(layout1, proc_nsfs)
{
const struct rule rules[] = {
@@ -2000,6 +2025,170 @@ TEST_F_FORK(layout1, rename_file)
RENAME_EXCHANGE));
}
+TEST_F_FORK(layout1, rename_whiteout_denied)
+{
+ /* The affected file is a FIFO. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+
+ /* Deny MAKE_REG, but allow MAKE_FIFO. */
+ enforce_fs(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, NULL);
+
+ /*
+ * Try to rename a file with RENAME_WHITEOUT.
+ * file1_s3d3 is in dir_s3d2 (tmpfs), so it supports RENAME_WHITEOUT.
+ * Denied, because whiteout creation is guarded with MAKE_REG.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+ EXPECT_EQ(EACCES, errno);
+}
+
+static bool is_whiteout(const char *const path)
+{
+ struct stat st;
+
+ if (stat(path, &st) == -1)
+ return false;
+
+ return S_ISCHR(st.st_mode) && st.st_rdev == makedev(0, 0);
+}
+
+static bool is_fifo(const char *const path)
+{
+ struct stat st;
+
+ return stat(path, &st) == 0 && S_ISFIFO(st.st_mode);
+}
+
+TEST_F_FORK(layout1, rename_whiteout_allowed)
+{
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The affected file is a FIFO. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+
+ /* Allow MAKE_REG below dir_s3d3. */
+ enforce_fs(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, rules);
+
+ /*
+ * Rename a file with RENAME_WHITEOUT within the same directory.
+ * Allowed, because MAKE_REG is granted for the whiteout object which
+ * gets created in the source location.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+
+ /* A whiteout object took the place of the moved FIFO. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(TMP_DIR "/s3d1/s3d2/s3d3/f2"));
+}
+
+TEST_F_FORK(layout1, rename_whiteout_reparenting)
+{
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d2,
+ .access = LANDLOCK_ACCESS_FS_REFER,
+ },
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The moved files are FIFOs. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+ ASSERT_EQ(0, unlink(file1_s3d4));
+ ASSERT_EQ(0, mknod(file1_s3d4, S_IFIFO | 0600, 0));
+
+ /* Allow REFER below dir_s3d2, but MAKE_REG only below dir_s3d3. */
+ enforce_fs(_metadata,
+ LANDLOCK_ACCESS_FS_MAKE_REG | LANDLOCK_ACCESS_FS_REFER,
+ rules);
+
+ /*
+ * The whiteout object is created in the source directory: Moving the
+ * FIFO out of dir_s3d4 is denied because MAKE_REG is not granted
+ * there, even though it is granted in the destination directory
+ * dir_s3d3.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d4, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+ EXPECT_EQ(EACCES, errno);
+
+ /*
+ * Moving the FIFO out of dir_s3d3 is allowed, because MAKE_REG is
+ * granted there for the created whiteout object.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d4/f2", RENAME_WHITEOUT));
+
+ /* A whiteout object took the place of the moved FIFO. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(TMP_DIR "/s3d1/s3d2/s3d4/f2"));
+}
+
+TEST_F_FORK(layout1, rename_whiteout_exchange)
+{
+ const char *const whiteout_s3d3 = TMP_DIR "/s3d1/s3d2/s3d3/f2";
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d2,
+ .access = LANDLOCK_ACCESS_FS_REFER,
+ },
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The exchanged files are FIFOs and an existing whiteout object. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+ ASSERT_EQ(0, mknod(whiteout_s3d3, S_IFCHR | 0600, makedev(0, 0)));
+ ASSERT_EQ(0, unlink(file1_s3d4));
+ ASSERT_EQ(0, mknod(file1_s3d4, S_IFIFO | 0600, 0));
+
+ /* Allow REFER below dir_s3d2, but MAKE_REG only below dir_s3d3. */
+ enforce_fs(_metadata,
+ LANDLOCK_ACCESS_FS_MAKE_REG | LANDLOCK_ACCESS_FS_REFER,
+ rules);
+
+ /*
+ * With RENAME_EXCHANGE, the whiteout object moves into the source
+ * directory of the rename: Exchanging the FIFO in dir_s3d4 with the
+ * whiteout object is denied because MAKE_REG is not granted in
+ * dir_s3d4, even though it is granted in the whiteout object's own
+ * directory dir_s3d3.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d4, AT_FDCWD, whiteout_s3d3,
+ RENAME_EXCHANGE));
+ EXPECT_EQ(EACCES, errno);
+
+ /*
+ * Exchanging the FIFO in dir_s3d3 with the whiteout object is
+ * allowed, because MAKE_REG is granted in the directory into which
+ * the whiteout object moves.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD, whiteout_s3d3,
+ RENAME_EXCHANGE));
+
+ /* The FIFO and the whiteout object swapped places. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(whiteout_s3d3));
+}
+
TEST_F_FORK(layout1, rename_dir)
{
const struct rule rules[] = {
@@ -3053,6 +3242,18 @@ TEST_F_FORK(layout1, make_char)
makedev(1, 3));
}
+TEST_F_FORK(layout1, make_whiteout)
+{
+ /*
+ * Creates a whiteout object (creation guarded by MAKE_REG).
+ *
+ * Contrary to the other character devices, this does not require
+ * CAP_MKNOD, cf. vfs_mknod().
+ */
+ test_make_file(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, S_IFCHR,
+ makedev(0, 0));
+}
+
TEST_F_FORK(layout1, make_block)
{
/* Creates a /dev/loop0 device. */
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories
2026-09-17 15:00 ` [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories Mickaël Salaün
@ 2026-09-18 0:52 ` Sasha Levin
0 siblings, 0 replies; 13+ messages in thread
From: Sasha Levin @ 2026-09-18 0:52 UTC (permalink / raw)
To: stable
Cc: Sasha Levin, Mickaël Salaün, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
> [ Upstream commit 49c9e09d961025b22e61ef9ad56aa1c21b6ce2f1 ]
>
> Disconnected files or directories can appear when they are visible and
> opened from a bind mount, but have been renamed or moved from the source
> of the bind mount in a way that makes them inaccessible from the mount
> point (i.e. out of scope).
Queued for 6.1, thanks. It also closes the gap where 6.1 shipped erratum
4 without erratum 3.
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites
2026-09-17 15:00 ` [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites Mickaël Salaün
@ 2026-09-18 0:52 ` Sasha Levin
0 siblings, 0 replies; 13+ messages in thread
From: Sasha Levin @ 2026-09-18 0:52 UTC (permalink / raw)
To: stable
Cc: Sasha Levin, Mickaël Salaün, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
> [ Upstream commit 54f9baf537b0a091adad860ec92e3e18e0a0754c ]
>
> Test disconnected directories with two test suites
> (layout4_disconnected_leafs and layout5_disconnected_branch) and 43
> variants to cover the main corner cases.
Queued for 6.18, 6.12, 6.6 and 6.1, thanks.
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation
2026-09-17 15:00 ` [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation Mickaël Salaün
@ 2026-09-18 19:45 ` Sasha Levin
2026-09-23 16:14 ` [PATCH 6.1.y v2] " Mickaël Salaün
0 siblings, 1 reply; 13+ messages in thread
From: Sasha Levin @ 2026-09-18 19:45 UTC (permalink / raw)
To: stable
Cc: Sasha Levin, Mickaël Salaün, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
> [mic: Backport: adapt the tests to the older filesystem fixture and
> ruleset helper]
Queued for 6.1, thanks.
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 6.1.y v2] selftests/landlock: Add tests for whiteout object creation
2026-09-18 19:45 ` Sasha Levin
@ 2026-09-23 16:14 ` Mickaël Salaün
2026-09-24 17:13 ` Sasha Levin
0 siblings, 1 reply; 13+ messages in thread
From: Mickaël Salaün @ 2026-09-23 16:14 UTC (permalink / raw)
To: stable
Cc: Mickaël Salaün, Sasha Levin, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
From: Günther Noack <gnoack@google.com>
[ Upstream commit ee890889b30b22f9a21636061def7a04e4f89380 ]
Add tests to check that whiteout object creation is guarded by
LANDLOCK_ACCESS_FS_MAKE_REG, in the cases where these are created from
userspace:
* Conventional creation with mknod()
* Linking or renaming an existing whiteout object
* renameat2() with RENAME_WHITEOUT,
which creates a new whiteout object in the source location
* renameat2() with RENAME_EXCHANGE,
with one of the renamed objects being a whiteout object
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://patch.msgid.link/20260813093157.1436894-4-gnoack@google.com
[mic: Update commit message as requested]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
[mic: Backport: adapt the tests to the older filesystem fixture and
ruleset helper]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
Changes since v1:
https://patch.msgid.link/1b6b0763e8d42e60d4d86489dab9972e554b94bc.1789655724.git.mic@digikod.net
- Define RENAME_WHITEOUT when libc headers do not provide it.
---
tools/testing/selftests/landlock/fs_test.c | 209 ++++++++++++++++++++-
1 file changed, 207 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 38c1003fb2f4..c585734cb83e 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -49,6 +49,10 @@ int open_tree(int dfd, const char *filename, unsigned int flags)
#define RENAME_EXCHANGE (1 << 1)
#endif
+#ifndef RENAME_WHITEOUT
+#define RENAME_WHITEOUT (1 << 2)
+#endif
+
#define TMP_DIR "tmp"
#define BINARY_PATH "./true"
@@ -75,6 +79,8 @@ static const char dir_s3d1[] = TMP_DIR "/s3d1";
/* dir_s3d2 is a mount point. */
static const char dir_s3d2[] = TMP_DIR "/s3d1/s3d2";
static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";
+static const char file1_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3/f1";
+static const char file1_s3d4[] = TMP_DIR "/s3d1/s3d2/s3d4/f1";
/*
* layout1 hierarchy:
@@ -271,7 +277,8 @@ static void create_layout1(struct __test_metadata *const _metadata)
ASSERT_EQ(0, mount("tmp", dir_s3d2, "tmpfs", 0, "size=4m,mode=700"));
clear_cap(_metadata, CAP_SYS_ADMIN);
- ASSERT_EQ(0, mkdir(dir_s3d3, 0700));
+ create_file(_metadata, file1_s3d3);
+ create_file(_metadata, file1_s3d4);
}
static void remove_layout1(struct __test_metadata *const _metadata)
@@ -288,7 +295,8 @@ static void remove_layout1(struct __test_metadata *const _metadata)
EXPECT_EQ(0, remove_path(file1_s2d2));
EXPECT_EQ(0, remove_path(file1_s2d1));
- EXPECT_EQ(0, remove_path(dir_s3d3));
+ EXPECT_EQ(0, remove_path(file1_s3d3));
+ EXPECT_EQ(0, remove_path(file1_s3d4));
set_cap(_metadata, CAP_SYS_ADMIN);
umount(dir_s3d2);
clear_cap(_metadata, CAP_SYS_ADMIN);
@@ -629,6 +637,27 @@ static void enforce_ruleset(struct __test_metadata *const _metadata,
}
}
+static void enforce_fs(struct __test_metadata *const _metadata,
+ const __u64 access_fs, const struct rule rules[])
+{
+ int ruleset_fd;
+
+ if (rules) {
+ ruleset_fd = create_ruleset(_metadata, access_fs, rules);
+ } else {
+ const struct landlock_ruleset_attr ruleset_attr = {
+ .handled_access_fs = access_fs,
+ };
+
+ 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));
+}
+
TEST_F_FORK(layout1, proc_nsfs)
{
const struct rule rules[] = {
@@ -2005,6 +2034,170 @@ TEST_F_FORK(layout1, rename_file)
RENAME_EXCHANGE));
}
+TEST_F_FORK(layout1, rename_whiteout_denied)
+{
+ /* The affected file is a FIFO. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+
+ /* Deny MAKE_REG, but allow MAKE_FIFO. */
+ enforce_fs(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, NULL);
+
+ /*
+ * Try to rename a file with RENAME_WHITEOUT.
+ * file1_s3d3 is in dir_s3d2 (tmpfs), so it supports RENAME_WHITEOUT.
+ * Denied, because whiteout creation is guarded with MAKE_REG.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+ EXPECT_EQ(EACCES, errno);
+}
+
+static bool is_whiteout(const char *const path)
+{
+ struct stat st;
+
+ if (stat(path, &st) == -1)
+ return false;
+
+ return S_ISCHR(st.st_mode) && st.st_rdev == makedev(0, 0);
+}
+
+static bool is_fifo(const char *const path)
+{
+ struct stat st;
+
+ return stat(path, &st) == 0 && S_ISFIFO(st.st_mode);
+}
+
+TEST_F_FORK(layout1, rename_whiteout_allowed)
+{
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The affected file is a FIFO. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+
+ /* Allow MAKE_REG below dir_s3d3. */
+ enforce_fs(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, rules);
+
+ /*
+ * Rename a file with RENAME_WHITEOUT within the same directory.
+ * Allowed, because MAKE_REG is granted for the whiteout object which
+ * gets created in the source location.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+
+ /* A whiteout object took the place of the moved FIFO. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(TMP_DIR "/s3d1/s3d2/s3d3/f2"));
+}
+
+TEST_F_FORK(layout1, rename_whiteout_reparenting)
+{
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d2,
+ .access = LANDLOCK_ACCESS_FS_REFER,
+ },
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The moved files are FIFOs. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+ ASSERT_EQ(0, unlink(file1_s3d4));
+ ASSERT_EQ(0, mknod(file1_s3d4, S_IFIFO | 0600, 0));
+
+ /* Allow REFER below dir_s3d2, but MAKE_REG only below dir_s3d3. */
+ enforce_fs(_metadata,
+ LANDLOCK_ACCESS_FS_MAKE_REG | LANDLOCK_ACCESS_FS_REFER,
+ rules);
+
+ /*
+ * The whiteout object is created in the source directory: Moving the
+ * FIFO out of dir_s3d4 is denied because MAKE_REG is not granted
+ * there, even though it is granted in the destination directory
+ * dir_s3d3.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d4, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d3/f2", RENAME_WHITEOUT));
+ EXPECT_EQ(EACCES, errno);
+
+ /*
+ * Moving the FIFO out of dir_s3d3 is allowed, because MAKE_REG is
+ * granted there for the created whiteout object.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD,
+ TMP_DIR "/s3d1/s3d2/s3d4/f2", RENAME_WHITEOUT));
+
+ /* A whiteout object took the place of the moved FIFO. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(TMP_DIR "/s3d1/s3d2/s3d4/f2"));
+}
+
+TEST_F_FORK(layout1, rename_whiteout_exchange)
+{
+ const char *const whiteout_s3d3 = TMP_DIR "/s3d1/s3d2/s3d3/f2";
+ const struct rule rules[] = {
+ {
+ .path = dir_s3d2,
+ .access = LANDLOCK_ACCESS_FS_REFER,
+ },
+ {
+ .path = dir_s3d3,
+ .access = LANDLOCK_ACCESS_FS_MAKE_REG,
+ },
+ {},
+ };
+
+ /* The exchanged files are FIFOs and an existing whiteout object. */
+ ASSERT_EQ(0, unlink(file1_s3d3));
+ ASSERT_EQ(0, mknod(file1_s3d3, S_IFIFO | 0600, 0));
+ ASSERT_EQ(0, mknod(whiteout_s3d3, S_IFCHR | 0600, makedev(0, 0)));
+ ASSERT_EQ(0, unlink(file1_s3d4));
+ ASSERT_EQ(0, mknod(file1_s3d4, S_IFIFO | 0600, 0));
+
+ /* Allow REFER below dir_s3d2, but MAKE_REG only below dir_s3d3. */
+ enforce_fs(_metadata,
+ LANDLOCK_ACCESS_FS_MAKE_REG | LANDLOCK_ACCESS_FS_REFER,
+ rules);
+
+ /*
+ * With RENAME_EXCHANGE, the whiteout object moves into the source
+ * directory of the rename: Exchanging the FIFO in dir_s3d4 with the
+ * whiteout object is denied because MAKE_REG is not granted in
+ * dir_s3d4, even though it is granted in the whiteout object's own
+ * directory dir_s3d3.
+ */
+ EXPECT_EQ(-1, renameat2(AT_FDCWD, file1_s3d4, AT_FDCWD, whiteout_s3d3,
+ RENAME_EXCHANGE));
+ EXPECT_EQ(EACCES, errno);
+
+ /*
+ * Exchanging the FIFO in dir_s3d3 with the whiteout object is
+ * allowed, because MAKE_REG is granted in the directory into which
+ * the whiteout object moves.
+ */
+ EXPECT_EQ(0, renameat2(AT_FDCWD, file1_s3d3, AT_FDCWD, whiteout_s3d3,
+ RENAME_EXCHANGE));
+
+ /* The FIFO and the whiteout object swapped places. */
+ EXPECT_TRUE(is_whiteout(file1_s3d3));
+ EXPECT_TRUE(is_fifo(whiteout_s3d3));
+}
+
TEST_F_FORK(layout1, rename_dir)
{
const struct rule rules[] = {
@@ -3058,6 +3251,18 @@ TEST_F_FORK(layout1, make_char)
makedev(1, 3));
}
+TEST_F_FORK(layout1, make_whiteout)
+{
+ /*
+ * Creates a whiteout object (creation guarded by MAKE_REG).
+ *
+ * Contrary to the other character devices, this does not require
+ * CAP_MKNOD, cf. vfs_mknod().
+ */
+ test_make_file(_metadata, LANDLOCK_ACCESS_FS_MAKE_REG, S_IFCHR,
+ makedev(0, 0));
+}
+
TEST_F_FORK(layout1, make_block)
{
/* Creates a /dev/loop0 device. */
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 6.1.y v2] selftests/landlock: Add tests for whiteout object creation
2026-09-23 16:14 ` [PATCH 6.1.y v2] " Mickaël Salaün
@ 2026-09-24 17:13 ` Sasha Levin
0 siblings, 0 replies; 13+ messages in thread
From: Sasha Levin @ 2026-09-24 17:13 UTC (permalink / raw)
To: stable
Cc: Sasha Levin, Mickaël Salaün, Günther Noack,
Christian Brauner, Günther Noack, Song Liu, Tingmao Wang
> Changes since v1:
> https://patch.msgid.link/1b6b0763e8d42e60d4d86489dab9972e554b94bc.1789655724.git.mic@digikod.net
> - Define RENAME_WHITEOUT when libc headers do not provide it.
Replaced v1 with v2 for 6.1, thanks.
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2026-09-24 17:13 UTC | newest]
Thread overview: 13+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-09-03 14:01 FAILED: patch "[PATCH] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout" failed to apply to 6.1-stable tree gregkh
2026-09-04 18:58 ` [PATCH 6.1.y] landlock: Require LANDLOCK_ACCESS_FS_MAKE_REG for whiteout creation Günther Noack
2026-09-06 13:32 ` Sasha Levin
2026-09-09 18:18 ` Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 1/4] landlock: Fix handling of disconnected directories Mickaël Salaün
2026-09-18 0:52 ` Sasha Levin
2026-09-17 15:00 ` [PATCH 6.1.y 2/4] selftests/landlock: Add tests for access through disconnected paths Mickaël Salaün
2026-09-17 15:00 ` [PATCH 6.1.y 3/4] selftests/landlock: Add disconnected leafs and branch test suites Mickaël Salaün
2026-09-18 0:52 ` Sasha Levin
2026-09-17 15:00 ` [PATCH 6.1.y 4/4] selftests/landlock: Add tests for whiteout object creation Mickaël Salaün
2026-09-18 19:45 ` Sasha Levin
2026-09-23 16:14 ` [PATCH 6.1.y v2] " Mickaël Salaün
2026-09-24 17:13 ` Sasha Levin
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