KEYS: Use structure to capture key restriction function and data

Replace struct key's restrict_link function pointer with a pointer to
the new struct key_restriction. The structure contains pointers to the
restriction function as well as relevant data for evaluating the
restriction.

The garbage collector checks restrict_link->keytype when key types are
unregistered. Restrictions involving a removed key type are converted
to use restrict_link_reject so that restrictions cannot be removed by
unregistering key types.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/security/keys/gc.c b/security/keys/gc.c
index 44789256c88c..15b9ddf510e4 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -229,6 +229,9 @@ continue_scanning:
 				set_bit(KEY_FLAG_DEAD, &key->flags);
 				key->perm = 0;
 				goto skip_dead_key;
+			} else if (key->type == &key_type_keyring &&
+				   key->restrict_link) {
+				goto found_restricted_keyring;
 			}
 		}
 
@@ -334,6 +337,14 @@ found_unreferenced_key:
 	gc_state |= KEY_GC_REAP_AGAIN;
 	goto maybe_resched;
 
+	/* We found a restricted keyring and need to update the restriction if
+	 * it is associated with the dead key type.
+	 */
+found_restricted_keyring:
+	spin_unlock(&key_serial_lock);
+	keyring_restriction_gc(key, key_gc_dead_keytype);
+	goto maybe_resched;
+
 	/* We found a keyring and we need to check the payload for links to
 	 * dead or expired keys.  We don't flag another reap immediately as we
 	 * have to wait for the old payload to be destroyed by RCU before we