Merge tag 'blob-stacking-security-next' of https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into next-general

LSM: Module stacking for SARA and Landlock

The combined series of LSM refactoring and addition of blob-sharing for
SARA and Landlock.

From Casey:

v5: Include Kees Cook's rework of the lsm command
    line interface.
v4: Finer granularity in the patches and other
    cleanups suggested by Kees Cook.
    Removed dead code created by the removal of SELinux
    credential blob poisoning.
v3: Add ipc blob for SARA and task blob for Landlock.
    Removing the SELinux cred blob pointer poisoning
    results selinux_is_enabled() being unused, so it and
    all it's overhead has been removed.
    Broke up the cred infrastructure patch.
v2: Reduce the patchset to what is required to support
    the proposed SARA and LandLock security modules

The SARA security module is intended to be used
in conjunction with other security modules. It requires
state to be maintained for the credential, which
in turn requires a mechanism for sharing the credential
security blob. It also uses the ipc security blob. The
module also requires mechanism for user space manipulation
of the credential information, hence an additional
subdirectory in /proc/.../attr.

The LandLock security module provides user configurable
policy in the secmark mechanism. It requires data in
the credential, file, inode and task security blobs. For
this to be used along side the existing "major" security
modules mechanism for sharing these blobs are provided.

A side effect of providing sharing of the crendential
security blob is that the TOMOYO module can be used at
the same time as the other "major" modules.

The mechanism for configuring which security modules are
enabled has to change when stacking in enabled. Any
module that uses just the security blobs that are shared
can be selected. Additionally, one other "major" module
can be selected.

The security module stacking issues around networking and
IPC are not addressed here as they are beyond what is
required for TOMOYO, SARA and LandLock.

2 files changed, 14 insertions, 3 deletions

diff --git a/Documentation/admin-guide/LSM/index.rst b/Documentation/admin-guide/LSM/index.rst
index c980dfe9abf1..9842e21afd4a 100644
--- a/Documentation/admin-guide/LSM/index.rst
+++ b/Documentation/admin-guide/LSM/index.rst
@@ -17,9 +17,8 @@ MAC extensions, other extensions can be built using the LSM to provide
 specific changes to system operation when these tweaks are not available
 in the core functionality of Linux itself.
 
-Without a specific LSM built into the kernel, the default LSM will be the
-Linux capabilities system. Most LSMs choose to extend the capabilities
-system, building their checks on top of the defined capability hooks.
+The Linux capabilities modules will always be included. This may be
+followed by any number of "minor" modules and at most one "major" module.
 For more details on capabilities, see ``capabilities(7)`` in the Linux
 man-pages project.
 
@@ -30,6 +29,14 @@ order in which checks are made. The capability module will always
 be first, followed by any "minor" modules (e.g. Yama) and then
 the one "major" module (e.g. SELinux) if there is one configured.
 
+Process attributes associated with "major" security modules should
+be accessed and maintained using the special files in ``/proc/.../attr``.
+A security module may maintain a module specific subdirectory there,
+named after the module. ``/proc/.../attr/smack`` is provided by the Smack
+security module and contains all its special files. The files directly
+in ``/proc/.../attr`` remain as legacy interfaces for modules that provide
+subdirectories.
+
 .. toctree::
    :maxdepth: 1
 
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b799bcf67d7b..e59e1471d4db 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2319,6 +2319,10 @@
 
 	lsm.debug	[SECURITY] Enable LSM initialization debugging output.
 
+	lsm=lsm1,...,lsmN
+			[SECURITY] Choose order of LSM initialization. This
+			overrides CONFIG_LSM.
+
 	machvec=	[IA-64] Force the use of a particular machine-vector
 			(machvec) in a generic kernel.
 			Example: machvec=hpzx1_swiotlb