keys: don't generate user and user session keyrings unless they're accessed

Don't generate the per-UID user and user session keyrings unless they're
explicitly accessed.  This solves a problem during a login process whereby
set*uid() is called before the SELinux PAM module, resulting in the per-UID
keyrings having the wrong security labels.

This also cures the problem of multiple per-UID keyrings sometimes appearing
due to PAM modules (including pam_keyinit) setuiding and causing user_structs
to come into and go out of existence whilst the session keyring pins the user
keyring.  This is achieved by first searching for extant per-UID keyrings
before inventing new ones.

The serial bound argument is also dropped from find_keyring_by_name() as it's
not currently made use of (setting it to 0 disables the feature).

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: <kwc@citi.umich.edu>
Cc: <arunsr@cse.iitk.ac.in>
Cc: <dwalsh@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 8 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 838d1e5e63a..4e4de98941a 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5551,14 +5551,6 @@ static __init int selinux_init(void)
 	else
 		printk(KERN_DEBUG "SELinux:  Starting in permissive mode\n");
 
-#ifdef CONFIG_KEYS
-	/* Add security information to initial keyrings */
-	selinux_key_alloc(&root_user_keyring, current,
-			  KEY_ALLOC_NOT_IN_QUOTA);
-	selinux_key_alloc(&root_session_keyring, current,
-			  KEY_ALLOC_NOT_IN_QUOTA);
-#endif
-
 	return 0;
 }