[PATCH v20 01/20] security: add ipe lsm

Fan Wu
2024-08-03T06:17:51Z

From: Deven Bowers <deven.desai@linux.microsoft.com>

Integrity Policy Enforcement (IPE) is an LSM that provides an
complimentary approach to Mandatory Access Control than existing LSMs
today.

Existing LSMs have centered around the concept of access to a resource
should be controlled by the current user's credentials. IPE's approach,
is that access to a resource should be controlled by the system's trust
of a current resource.

The basis of this approach is defining a global policy to specify which
resource can be trusted.

Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
---
v2:
+ Split evaluation loop, access control hooks,
and evaluation loop from policy parser and userspace
interface to pass mailing list character limit

v3:
+ Move ipe_load_properties to patch 04.
+ Remove useless 0-initializations
+ Prefix extern variables with ipe_
+ Remove kernel module parameters, as these are
exposed through sysctls.
+ Add more prose to the IPE base config option
help text.
+ Use GFP_KERNEL for audit_log_start.
+ Remove unnecessary caching system.
+ Remove comments from headers
+ Use rcu_access_pointer for rcu-pointer null check
+ Remove usage of reqprot; use prot only.
+ Move policy load and activation audit event to 03/12

v4:
+ Remove sysctls in favor of securityfs nodes
+ Re-add kernel module parameters, as these are now
exposed through securityfs.
+ Refactor property audit loop to a separate function.

v5:
+ fix minor grammatical errors
+ do not group rule by curly-brace in audit record,
reconstruct the exact rule.

v6:
+ No changes

v7:
+ Further split lsm creation into a separate commit from the
evaluation loop and audit system, for easier review.

+ Introduce the concept of an ipe_context, a scoped way to
introduce execution policies, used initially for allowing for
kunit tests in isolation.

v8:
+ Follow lsmname_hook_name convention for lsm hooks.
+ Move LSM blob accessors to ipe.c and mark LSM blobs as static.

v9:
+ Remove ipe_context for simplification

v10:
+ Add github url

v11:
+ Correct github url
+ Move ipe before bpf

v12:
+ Switch to use lsm_id instead of string for lsm name

v13:
+ No changes

v14:
+ No changes

v15:
+ Add missing code in tools/testing/selftests/lsm/lsm_list_modules_test.c

v16:
+ No changes

v17:
+ Add years to license header
+ Fix code and documentation style issues

v18:
+ No changes

v19:
+ No changes

v20:
+ No changes
---
include/uapi/linux/lsm.h | 1 +
security/Kconfig | 11 ++---
security/Makefile | 1 +
security/ipe/Kconfig | 17 ++++++++
security/ipe/Makefile | 9 ++++
security/ipe/ipe.c | 42 +++++++++++++++++++
security/ipe/ipe.h | 16 +++++++
security/security.c | 3 +-
.../selftests/lsm/lsm_list_modules_test.c | 3 ++
9 files changed, 97 insertions(+), 6 deletions(-)
create mode 100644 security/ipe/Kconfig
create mode 100644 security/ipe/Makefile
create mode 100644 security/ipe/ipe.c
create mode 100644 security/ipe/ipe.h

diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
index 33d8c9f4aa6b..938593dfd5da 100644
--- a/include/uapi/linux/lsm.h
+++ b/include/uapi/linux/lsm.h
@@ -64,6 +64,7 @@ struct lsm_ctx {
#define LSM_ID_LANDLOCK 110
#define LSM_ID_IMA 111
#define LSM_ID_EVM 112
+#define LSM_ID_IPE 113

/*
* LSM_ATTR_XXX definitions identify different LSM attributes
diff --git a/security/Kconfig b/security/Kconfig
index 412e76f1575d..9fb8f9b14972 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -192,6 +192,7 @@ source "security/yama/Kconfig"
source "security/safesetid/Kconfig"
source "security/lockdown/Kconfig"
source "security/landlock/Kconfig"
+source "security/ipe/Kconfig"

source "security/integrity/Kconfig"

@@ -231,11 +232,11 @@ endchoice

config LSM
string "Ordered list of enabled LSMs"
- default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
- default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
- default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
- default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
- default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
+ default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,ipe,bpf" if DEFAULT_SECURITY_SMACK
+ default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,ipe,bpf" if DEFAULT_SECURITY_APPARMOR
+ default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,ipe,bpf" if DEFAULT_SECURITY_TOMOYO
+ default "landlock,lockdown,yama,loadpin,safesetid,ipe,bpf" if DEFAULT_SECURITY_DAC
+ default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,ipe,bpf"
help
A comma-separated list of LSMs, in initialization order.
Any LSMs left off this list, except for those with order
diff --git a/security/Makefile b/security/Makefile
index 59f238490665..cc0982214b84 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_SECURITY_LOCKDOWN_LSM) += lockdown/
obj-$(CONFIG_CGROUPS) += device_cgroup.o
obj-$(CONFIG_BPF_LSM) += bpf/
obj-$(CONFIG_SECURITY_LANDLOCK) += landlock/
+obj-$(CONFIG_SECURITY_IPE) += ipe/

# Object integrity file lists
obj-$(CONFIG_INTEGRITY) += integrity/
diff --git a/security/ipe/Kconfig b/security/ipe/Kconfig
new file mode 100644
index 000000000000..e4875fb04883
--- /dev/null
+++ b/security/ipe/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Integrity Policy Enforcement (IPE) configuration
+#
+
+menuconfig SECURITY_IPE
+ bool "Integrity Policy Enforcement (IPE)"
+ depends on SECURITY && SECURITYFS
+ select PKCS7_MESSAGE_PARSER
+ select SYSTEM_DATA_VERIFICATION
+ help
+ This option enables the Integrity Policy Enforcement LSM
+ allowing users to define a policy to enforce a trust-based access
+ control. A key feature of IPE is a customizable policy to allow
+ admins to reconfigure trust requirements on the fly.
+
+ If unsure, answer N.
diff --git a/security/ipe/Makefile b/security/ipe/Makefile
new file mode 100644
index 000000000000..5486398a69e9
--- /dev/null
+++ b/security/ipe/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+#
+# Makefile for building the IPE module as part of the kernel tree.
+#
+
+obj-$(CONFIG_SECURITY_IPE) += \
+ ipe.o \
diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
new file mode 100644
index 000000000000..8d4ea372873e
--- /dev/null
+++ b/security/ipe/ipe.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+ */
+#include <uapi/linux/lsm.h>
+
+#include "ipe.h"
+
+static struct lsm_blob_sizes ipe_blobs __ro_after_init = {
+};
+
+static const struct lsm_id ipe_lsmid = {
+ .name = "ipe",
+ .id = LSM_ID_IPE,
+};
+
+static struct security_hook_list ipe_hooks[] __ro_after_init = {
+};
+
+/**
+ * ipe_init() - Entry point of IPE.
+ *
+ * This is called at LSM init, which happens occurs early during kernel
+ * start up. During this phase, IPE registers its hooks and loads the
+ * builtin boot policy.
+ *
+ * Return:
+ * * %0 - OK
+ * * %-ENOMEM - Out of memory (OOM)
+ */
+static int __init ipe_init(void)
+{
+ security_add_hooks(ipe_hooks, ARRAY_SIZE(ipe_hooks), &ipe_lsmid);
+
+ return 0;
+}
+
+DEFINE_LSM(ipe) = {
+ .name = "ipe",
+ .init = ipe_init,
+ .blobs = &ipe_blobs,
+};
diff --git a/security/ipe/ipe.h b/security/ipe/ipe.h
new file mode 100644
index 000000000000..adc3c45e9f53
--- /dev/null
+++ b/security/ipe/ipe.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+ */
+
+#ifndef _IPE_H
+#define _IPE_H
+
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+#define pr_fmt(fmt) "ipe: " fmt
+
+#include <linux/lsm_hooks.h>
+
+#endif /* _IPE_H */
diff --git a/security/security.c b/security/security.c
index 8cee5b6c6e6d..8218c745d5e2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -51,7 +51,8 @@
(IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
(IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \
(IS_ENABLED(CONFIG_IMA) ? 1 : 0) + \
- (IS_ENABLED(CONFIG_EVM) ? 1 : 0))
+ (IS_ENABLED(CONFIG_EVM) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_IPE) ? 1 : 0))

/*
* These are descriptions of the reasons that can be passed to the
diff --git a/tools/testing/selftests/lsm/lsm_list_modules_test.c b/tools/testing/selftests/lsm/lsm_list_modules_test.c
index 06d24d4679a6..1cc8a977c711 100644
--- a/tools/testing/selftests/lsm/lsm_list_modules_test.c
+++ b/tools/testing/selftests/lsm/lsm_list_modules_test.c
@@ -128,6 +128,9 @@ TEST(correct_lsm_list_modules)
case LSM_ID_EVM:
name = "evm";
break;
+ case LSM_ID_IPE:
+ name = "ipe";
+ break;
default:
name = "INVALID";
break;
--
2.44.0