KEYS: Add an alloc flag to convey the builtinness of a key

BugLink: http://bugs.launchpad.net/bugs/1569924

Add KEY_ALLOC_BUILT_IN to convey that a key should have KEY_FLAG_BUILTIN
set rather than setting it after the fact.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
(cherry picked from commit 5d2787cf)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Andy Whitcroft <andy.whitcroft@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

certs/system_keyring.c

@@ -84,13 +84,13 @@ static __init int load_system_certificate_list(void)
 					   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 					   KEY_USR_VIEW | KEY_USR_READ),
 					   KEY_ALLOC_NOT_IN_QUOTA |
-					   KEY_ALLOC_TRUSTED);
+					   KEY_ALLOC_TRUSTED |
+					   KEY_ALLOC_BUILT_IN);
 		if (IS_ERR(key)) {
 			pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
 			       PTR_ERR(key));
 			WARN_ON_ONCE(1);
 		} else {
-			set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
 			pr_notice("Loaded X.509 cert '%s'\n",
 				  key_ref_to_ptr(key)->description);
 			key_ref_put(key);

include/linux/key.h

@@ -218,6 +218,7 @@ extern struct key *key_alloc(struct key_type *type,
 #define KEY_ALLOC_QUOTA_OVERRUN	0x0001	/* add to quota, permit even if overrun */
 #define KEY_ALLOC_NOT_IN_QUOTA	0x0002	/* not in quota */
 #define KEY_ALLOC_TRUSTED	0x0004	/* Key should be flagged as trusted */
+#define KEY_ALLOC_BUILT_IN	0x0008	/* Key is built into kernel */
 
 extern void key_revoke(struct key *key);
 extern void key_invalidate(struct key *key);

security/keys/key.c

@@ -296,6 +296,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 		key->flags |= 1 << KEY_FLAG_IN_QUOTA;
 	if (flags & KEY_ALLOC_TRUSTED)
 		key->flags |= 1 << KEY_FLAG_TRUSTED;
+	if (flags & KEY_ALLOC_BUILT_IN)
+		key->flags |= 1 << KEY_FLAG_BUILTIN;
 
 #ifdef KEY_DEBUGGING
 	key->magic = KEY_DEBUG_MAGIC;