KEYS: Remove key_type::match in favour of overriding default by match_preparse

A previous patch added a ->match_preparse() method to the key type.  This is
allowed to override the function called by the iteration algorithm.
Therefore, we can just set a default that simply checks for an exact match of
the key description with the original criterion data and allow match_preparse
to override it as needed.

The key_type::match op is then redundant and can be removed, as can the
user_match() function.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

security/keys/big_key.c

@@ -36,7 +36,6 @@ struct key_type key_type_big_key = {
 	.preparse		= big_key_preparse,
 	.free_preparse		= big_key_free_preparse,
 	.instantiate		= generic_key_instantiate,
-	.match			= user_match,
 	.revoke			= big_key_revoke,
 	.destroy		= big_key_destroy,
 	.describe		= big_key_describe,

security/keys/encrypted-keys/encrypted.c

@@ -970,7 +970,6 @@ struct key_type key_type_encrypted = {
 	.name = "encrypted",
 	.instantiate = encrypted_instantiate,
 	.update = encrypted_update,
-	.match = user_match,
 	.destroy = encrypted_destroy,
 	.describe = user_describe,
 	.read = encrypted_read,

security/keys/internal.h

@@ -127,6 +127,8 @@ struct keyring_search_context {
 	struct timespec		now;
 };
 
+extern int key_default_cmp(const struct key *key,
+			   const struct key_match_data *match_data);
 extern key_ref_t keyring_search_aux(key_ref_t keyring_ref,
 				    struct keyring_search_context *ctx);
 

security/keys/key.c

@@ -799,7 +799,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 	}
 
 	key_ref = ERR_PTR(-EINVAL);
-	if (!index_key.type->match || !index_key.type->instantiate ||
+	if (!index_key.type->instantiate ||
 	    (!index_key.description && !index_key.type->preparse))
 		goto error_put_type;
 

security/keys/keyring.c

@@ -89,7 +89,6 @@ struct key_type key_type_keyring = {
 	.preparse	= keyring_preparse,
 	.free_preparse	= keyring_free_preparse,
 	.instantiate	= keyring_instantiate,
-	.match		= user_match,
 	.revoke		= keyring_revoke,
 	.destroy	= keyring_destroy,
 	.describe	= keyring_describe,
@@ -511,6 +510,15 @@ struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 }
 EXPORT_SYMBOL(keyring_alloc);
 
+/*
+ * By default, we keys found by getting an exact match on their descriptions.
+ */
+int key_default_cmp(const struct key *key,
+		    const struct key_match_data *match_data)
+{
+	return strcmp(key->description, match_data->raw_data) == 0;
+}
+
 /*
  * Iteration function to consider each key found.
  */
@@ -884,7 +892,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 		.index_key.type		= type,
 		.index_key.description	= description,
 		.cred			= current_cred(),
-		.match_data.cmp		= type->match,
+		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,
 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 		.flags			= KEYRING_SEARCH_DO_STATE_CHECK,
@@ -892,9 +900,6 @@ key_ref_t keyring_search(key_ref_t keyring,
 	key_ref_t key;
 	int ret;
 
-	if (!ctx.match_data.cmp)
-		return ERR_PTR(-ENOKEY);
-
 	if (type->match_preparse) {
 		ret = type->match_preparse(&ctx.match_data);
 		if (ret < 0)

security/keys/request_key.c

@@ -531,7 +531,7 @@ struct key *request_key_and_link(struct key_type *type,
 		.index_key.type		= type,
 		.index_key.description	= description,
 		.cred			= current_cred(),
-		.match_data.cmp		= type->match,
+		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,
 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 	};

security/keys/request_key_auth.c

@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 		.index_key.type		= &key_type_request_key_auth,
 		.index_key.description	= description,
 		.cred			= current_cred(),
-		.match_data.cmp		= user_match,
+		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,
 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 	};

security/keys/trusted.c

@@ -1096,7 +1096,6 @@ struct key_type key_type_trusted = {
 	.name = "trusted",
 	.instantiate = trusted_instantiate,
 	.update = trusted_update,
-	.match = user_match,
 	.destroy = trusted_destroy,
 	.describe = user_describe,
 	.read = trusted_read,

security/keys/user_defined.c

@@ -30,7 +30,6 @@ struct key_type key_type_user = {
 	.free_preparse		= user_free_preparse,
 	.instantiate		= generic_key_instantiate,
 	.update			= user_update,
-	.match			= user_match,
 	.revoke			= user_revoke,
 	.destroy		= user_destroy,
 	.describe		= user_describe,
@@ -51,7 +50,6 @@ struct key_type key_type_logon = {
 	.free_preparse		= user_free_preparse,
 	.instantiate		= generic_key_instantiate,
 	.update			= user_update,
-	.match			= user_match,
 	.revoke			= user_revoke,
 	.destroy		= user_destroy,
 	.describe		= user_describe,
@@ -136,16 +134,6 @@ error:
 
 EXPORT_SYMBOL_GPL(user_update);
 
-/*
- * match users on their name
- */
-int user_match(const struct key *key, const struct key_match_data *match_data)
-{
-	return strcmp(key->description, match_data->raw_data) == 0;
-}
-
-EXPORT_SYMBOL_GPL(user_match);
-
 /*
  * dispose of the links from a revoked keyring
  * - called with the key sem write-locked