[RFC PATCH v9 01/16] security: add ipe lsm

[Fan Wu <wufan@linux.microsoft.com>]

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
---
 MAINTAINERS           |  5 +++++
 security/Kconfig      | 11 ++++++-----
 security/Makefile     |  1 +
 security/ipe/Kconfig  | 17 +++++++++++++++++
 security/ipe/Makefile | 10 ++++++++++
 security/ipe/ipe.c    | 40 ++++++++++++++++++++++++++++++++++++++++
 security/ipe/ipe.h    | 13 +++++++++++++
 7 files changed, 92 insertions(+), 5 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/MAINTAINERS b/MAINTAINERS
index 8a5c25c20d00..5e27e84763cc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10273,6 +10273,11 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
 F:	security/integrity/ima/
 F:	security/integrity/
 
+INTEGRITY POLICY ENFORCEMENT (IPE)
+M:	Fan Wu <wufan@linux.microsoft.com>
+S:	Supported
+F:	security/ipe/
+
 INTEL 810/815 FRAMEBUFFER DRIVER
 M:	Antonino Daplas <adaplas@gmail.com>
 L:	linux-fbdev@vger.kernel.org
diff --git a/security/Kconfig b/security/Kconfig
index e6db09a779b7..9f59add2d16c 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -207,6 +207,7 @@ source "security/yama/Kconfig"
 source "security/safesetid/Kconfig"
 source "security/lockdown/Kconfig"
 source "security/landlock/Kconfig"
+source "security/ipe/Kconfig"
 
 source "security/integrity/Kconfig"
 
@@ -246,11 +247,11 @@ endchoice
 
 config LSM
 	string "Ordered list of enabled LSMs"
-	default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
-	default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
-	default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
-	default "landlock,lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
-	default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
+	default "landlock,lockdown,yama,loadpin,safesetid,integrity,ipe,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
+	default "landlock,lockdown,yama,loadpin,safesetid,integrity,ipe,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
+	default "landlock,lockdown,yama,loadpin,safesetid,integrity,ipe,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
+	default "landlock,lockdown,yama,loadpin,safesetid,integrity,ipe,bpf" if DEFAULT_SECURITY_DAC
+	default "landlock,lockdown,yama,loadpin,safesetid,integrity,ipe,selinux,smack,tomoyo,apparmor,bpf"
 	help
 	  A comma-separated list of LSMs, in initialization order.
 	  Any LSMs left off this list will be ignored. This can be
diff --git a/security/Makefile b/security/Makefile
index 18121f8f85cd..527b1864d96c 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -24,6 +24,7 @@ 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-$(CONFIG_INTEGRITY)			+= integrity/
diff --git a/security/ipe/Kconfig b/security/ipe/Kconfig
new file mode 100644
index 000000000000..e4875fb04883
--- /dev/null
+++ b/security/ipe/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Integrity Policy Enforcement (IPE) configuration
+#
+
+menuconfig SECURITY_IPE
+	bool "Integrity Policy Enforcement (IPE)"
+	depends on SECURITY && SECURITYFS
+	select PKCS7_MESSAGE_PARSER
+	select SYSTEM_DATA_VERIFICATION
+	help
+	  This option enables the Integrity Policy Enforcement LSM
+	  allowing users to define a policy to enforce a trust-based access
+	  control. A key feature of IPE is a customizable policy to allow
+	  admins to reconfigure trust requirements on the fly.
+
+	  If unsure, answer N.
diff --git a/security/ipe/Makefile b/security/ipe/Makefile
new file mode 100644
index 000000000000..571648579991
--- /dev/null
+++ b/security/ipe/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) Microsoft Corporation. All rights reserved.
+#
+# Makefile for building the IPE module as part of the kernel tree.
+#
+
+obj-$(CONFIG_SECURITY_IPE) += \
+	hooks.o \
+	ipe.o \
diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
new file mode 100644
index 000000000000..9ed3bf4dcc04
--- /dev/null
+++ b/security/ipe/ipe.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#include "ipe.h"
+
+static struct lsm_blob_sizes ipe_blobs __lsm_ro_after_init = {
+};
+
+static struct security_hook_list ipe_hooks[] __lsm_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 loads the properties compiled into
+ * the kernel, and register's IPE's hooks. The boot policy is loaded
+ * later, during securityfs init, at which point IPE will start
+ * enforcing its policy.
+ *
+ * Return:
+ * * 0		- OK
+ * * -ENOMEM	- Context creation failed.
+ */
+static int __init ipe_init(void)
+{
+	int rc = 0;
+
+	security_add_hooks(ipe_hooks, ARRAY_SIZE(ipe_hooks), "ipe");
+
+	return rc;
+}
+
+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..ee7ec3f3b55d
--- /dev/null
+++ b/security/ipe/ipe.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#ifndef IPE_H
+#define IPE_H
+
+#define pr_fmt(fmt) "IPE " fmt "\n"
+
+#include <linux/lsm_hooks.h>
+
+#endif /* IPE_H */
-- 
2.39.0