Security: Introduce security= boot parameter

Add the security= boot parameter. This is done to avoid LSM
registration clashes in case of more than one bult-in module.

User can choose a security module to enable at boot. If no
security= boot parameter is specified, only the first LSM
asking for registration will be loaded. An invalid security
module name will be treated as if no module has been chosen.

LSM modules must check now if they are allowed to register
by calling security_module_enable(ops) first. Modify SELinux
and SMACK to do so.

Do not let SMACK register smackfs if it was not chosen on
boot. Smackfs assumes that smack hooks are registered and
the initial task security setup (swapper->security) is done.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: James Morris <jmorris@namei.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 256a2162503c..4b0f1ae31a4c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -366,6 +366,12 @@ and is between 256 and 4096 characters. It is defined in the file
                         possible to determine what the correct size should be.
                         This option provides an override for these situations.
 
+        security=       [SECURITY] Choose a security module to enable at boot.
+                        If this boot parameter is not specified, only the first
+                        security module asking for security registration will be
+                        loaded. An invalid security module name will be treated
+                        as if no module has been chosen.
+
         capability.disable=
                         [SECURITY] Disable capabilities.  This would normally
                         be used only if an alternative security model is to be