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, 1 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 732ba27923c4..904bdc01a12b 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2424,7 +2424,9 @@ static void smack_release_secctx(char *secdata, u32 seclen)
 {
 }
 
-static struct security_operations smack_ops = {
+struct security_operations smack_ops = {
+        .name =                         "smack",
+
         .ptrace =                       smack_ptrace,
         .capget =                       cap_capget,
         .capset_check =                 cap_capset_check,
@@ -2557,6 +2559,9 @@ static struct security_operations smack_ops = {
  */
 static __init int smack_init(void)
 {
+        if (!security_module_enable(&smack_ops))
+                return 0;
+
         printk(KERN_INFO "Smack:  Initializing.\n");
 
         /*