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>

7 files changed, 65 insertions, 44 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index 5f20da01..805e60b 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -107,13 +107,10 @@ extern int iterate_over_keyring(const struct key *keyring,
 				int (*func)(const struct key *key, void *data),
 				void *data);
 
-typedef int (*key_match_func_t)(const struct key *, const void *);
-
 struct keyring_search_context {
 	struct keyring_index_key index_key;
 	const struct cred	*cred;
-	key_match_func_t	match;
-	const void		*match_data;
+	struct key_match_data	match_data;
 	unsigned		flags;
 #define KEYRING_SEARCH_LOOKUP_TYPE	0x0001	/* [as type->def_lookup_type] */
 #define KEYRING_SEARCH_NO_STATE_CHECK	0x0002	/* Skip state checks */
@@ -152,7 +149,8 @@ extern struct key *request_key_and_link(struct key_type *type,
 					struct key *dest_keyring,
 					unsigned long flags);
 
-extern int lookup_user_key_possessed(const struct key *key, const void *target);
+extern int lookup_user_key_possessed(const struct key *key,
+				     const struct key_match_data *match_data);
 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 				 key_perm_t perm);
 #define KEY_LOOKUP_CREATE	0x01
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 @@ static int keyring_search_iterator(const void *object, void *iterator_data)
 	}
 
 	/* 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 @@ skipped:
  */
 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 @@ static bool search_nested_keyrings(struct key *keyring,
 	/* 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 @@ key_ref_t keyring_search(key_ref_t keyring,
 		.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 @@ static int keyring_detect_cycle_iterator(const void *object,
 
 	/* 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_iterator(const void *object,
 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();
diff --git a/security/keys/proc.c b/security/keys/proc.c
index d3f6f2f..972eeb3 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -194,10 +194,10 @@ static int proc_keys_show(struct seq_file *m, void *v)
 		.index_key.type		= key->type,
 		.index_key.description	= key->description,
 		.cred			= current_cred(),
-		.match			= lookup_user_key_possessed,
-		.match_data		= key,
-		.flags			= (KEYRING_SEARCH_NO_STATE_CHECK |
-					   KEYRING_SEARCH_LOOKUP_DIRECT),
+		.match_data.cmp		= lookup_user_key_possessed,
+		.match_data.raw_data	= key,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.flags			= KEYRING_SEARCH_NO_STATE_CHECK,
 	};
 
 	key_ref = make_key_ref(key, 0);
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 0cf8a13..08bd533 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -489,9 +489,10 @@ found:
 /*
  * See if the key we're looking at is the target key.
  */
-int lookup_user_key_possessed(const struct key *key, const void *target)
+int lookup_user_key_possessed(const struct key *key,
+			      const struct key_match_data *match_data)
 {
-	return key == target;
+	return key == match_data->raw_data;
 }
 
 /*
@@ -516,9 +517,9 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
 			  key_perm_t perm)
 {
 	struct keyring_search_context ctx = {
-		.match	= lookup_user_key_possessed,
-		.flags	= (KEYRING_SEARCH_NO_STATE_CHECK |
-			   KEYRING_SEARCH_LOOKUP_DIRECT),
+		.match_data.cmp		= lookup_user_key_possessed,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.flags			= KEYRING_SEARCH_NO_STATE_CHECK,
 	};
 	struct request_key_auth *rka;
 	struct key *key;
@@ -673,7 +674,7 @@ try_again:
 		ctx.index_key.type		= key->type;
 		ctx.index_key.description	= key->description;
 		ctx.index_key.desc_len		= strlen(key->description);
-		ctx.match_data			= key;
+		ctx.match_data.raw_data		= key;
 		kdebug("check possessed");
 		skey_ref = search_process_keyrings(&ctx);
 		kdebug("possessed=%p", skey_ref);
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 3814119..408523e 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -531,9 +531,9 @@ struct key *request_key_and_link(struct key_type *type,
 		.index_key.type		= type,
 		.index_key.description	= description,
 		.cred			= current_cred(),
-		.match			= type->match,
-		.match_data		= description,
-		.flags			= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.match_data.cmp		= type->match,
+		.match_data.raw_data	= description,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 	};
 	struct key *key;
 	key_ref_t key_ref;
@@ -543,6 +543,14 @@ struct key *request_key_and_link(struct key_type *type,
 	       ctx.index_key.type->name, ctx.index_key.description,
 	       callout_info, callout_len, aux, dest_keyring, flags);
 
+	if (type->match_preparse) {
+		ret = type->match_preparse(&ctx.match_data);
+		if (ret < 0) {
+			key = ERR_PTR(ret);
+			goto error;
+		}
+	}
+
 	/* search all the process keyrings for a key */
 	key_ref = search_process_keyrings(&ctx);
 
@@ -555,7 +563,7 @@ struct key *request_key_and_link(struct key_type *type,
 			if (ret < 0) {
 				key_put(key);
 				key = ERR_PTR(ret);
-				goto error;
+				goto error_free;
 			}
 		}
 	} else if (PTR_ERR(key_ref) != -EAGAIN) {
@@ -565,12 +573,15 @@ struct key *request_key_and_link(struct key_type *type,
 		 * should consult userspace if we can */
 		key = ERR_PTR(-ENOKEY);
 		if (!callout_info)
-			goto error;
+			goto error_free;
 
 		key = construct_key_and_link(&ctx, callout_info, callout_len,
 					     aux, dest_keyring, flags);
 	}
 
+error_free:
+	if (type->match_free)
+		type->match_free(&ctx.match_data);
 error:
 	kleave(" = %p", key);
 	return key;
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 739e745..9ae0281 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -246,9 +246,9 @@ 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			= user_match,
-		.match_data		= description,
-		.flags			= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.match_data.cmp		= user_match,
+		.match_data.raw_data	= description,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 	};
 	struct key *authkey;
 	key_ref_t authkey_ref;
diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
index eee3400..ec8a560 100644
--- a/security/keys/user_defined.c
+++ b/security/keys/user_defined.c
@@ -141,9 +141,9 @@ EXPORT_SYMBOL_GPL(user_update);
 /*
  * match users on their name
  */
-int user_match(const struct key *key, const void *description)
+int user_match(const struct key *key, const struct key_match_data *match_data)
 {
-	return strcmp(key->description, description) == 0;
+	return strcmp(key->description, match_data->raw_data) == 0;
 }
 
 EXPORT_SYMBOL_GPL(user_match);