KEYS: Preparse match data

Preparse the match data.  This provides several advantages:

 (1) The preparser can reject invalid criteria up front.

 (2) The preparser can convert the criteria to binary data if necessary (the
     asymmetric key type really wants to do binary comparison of the key IDs).

 (3) The preparser can set the type of search to be performed.  This means
     that it's not then a one-off setting in the key type.

 (4) The preparser can set an appropriate comparator function.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 8314a7d..10f0a5f 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -545,7 +545,7 @@
 	}
 
 	/* keys that don't match */
-	if (!ctx->match(key, ctx->match_data)) {
+	if (!ctx->match_data.cmp(key, &ctx->match_data)) {
 		kleave(" = 0 [!match]");
 		return 0;
 	}
@@ -585,8 +585,7 @@
  */
 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
 {
-	if ((ctx->flags & KEYRING_SEARCH_LOOKUP_TYPE) ==
-	    KEYRING_SEARCH_LOOKUP_DIRECT) {
+	if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
 		const void *object;
 
 		object = assoc_array_find(&keyring->keys,
@@ -627,7 +626,7 @@
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */
-	if (ctx->flags & KEYRING_SEARCH_LOOKUP_ITERATE ||
+	if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
 	    keyring_compare_object(keyring, &ctx->index_key)) {
 		ctx->skipped_ret = 2;
 		ctx->flags |= KEYRING_SEARCH_DO_STATE_CHECK;
@@ -885,16 +884,28 @@
 		.index_key.type		= type,
 		.index_key.description	= description,
 		.cred			= current_cred(),
-		.match			= type->match,
-		.match_data		= description,
-		.flags			= (type->def_lookup_type |
-					   KEYRING_SEARCH_DO_STATE_CHECK),
+		.match_data.cmp		= type->match,
+		.match_data.raw_data	= description,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.flags			= KEYRING_SEARCH_DO_STATE_CHECK,
 	};
+	key_ref_t key;
+	int ret;
 
-	if (!ctx.match)
+	if (!ctx.match_data.cmp)
 		return ERR_PTR(-ENOKEY);
 
-	return keyring_search_aux(keyring, &ctx);
+	if (type->match_preparse) {
+		ret = type->match_preparse(&ctx.match_data);
+		if (ret < 0)
+			return ERR_PTR(ret);
+	}
+
+	key = keyring_search_aux(keyring, &ctx);
+
+	if (type->match_free)
+		type->match_free(&ctx.match_data);
+	return key;
 }
 EXPORT_SYMBOL(keyring_search);
 
@@ -1014,7 +1025,7 @@
 
 	/* We might get a keyring with matching index-key that is nonetheless a
 	 * different keyring. */
-	if (key != ctx->match_data)
+	if (key != ctx->match_data.raw_data)
 		return 0;
 
 	ctx->result = ERR_PTR(-EDEADLK);
@@ -1031,14 +1042,14 @@
 static int keyring_detect_cycle(struct key *A, struct key *B)
 {
 	struct keyring_search_context ctx = {
-		.index_key	= A->index_key,
-		.match_data	= A,
-		.iterator	= keyring_detect_cycle_iterator,
-		.flags		= (KEYRING_SEARCH_LOOKUP_DIRECT |
-				   KEYRING_SEARCH_NO_STATE_CHECK |
-				   KEYRING_SEARCH_NO_UPDATE_TIME |
-				   KEYRING_SEARCH_NO_CHECK_PERM |
-				   KEYRING_SEARCH_DETECT_TOO_DEEP),
+		.index_key		= A->index_key,
+		.match_data.raw_data	= A,
+		.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
+		.iterator		= keyring_detect_cycle_iterator,
+		.flags			= (KEYRING_SEARCH_NO_STATE_CHECK |
+					   KEYRING_SEARCH_NO_UPDATE_TIME |
+					   KEYRING_SEARCH_NO_CHECK_PERM |
+					   KEYRING_SEARCH_DETECT_TOO_DEEP),
 	};
 
 	rcu_read_lock();