[PATCH] Keys: Remove key duplication

Remove the key duplication stuff since there's nothing that uses it, no way
to get at it and it's awkward to deal with for LSM purposes.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/keys.txt

@@ -860,24 +860,6 @@ The structure has a number of fields, some of which are mandatory:
      It is safe to sleep in this method.
 
 
- (*) int (*duplicate)(struct key *key, const struct key *source);
-
-     If this type of key can be duplicated, then this method should be
-     provided. It is called to copy the payload attached to the source into the
-     new key. The data length on the new key will have been updated and the
-     quota adjusted already.
-
-     This method will be called with the source key's semaphore read-locked to
-     prevent its payload from being changed, thus RCU constraints need not be
-     applied to the source key.
-
-     This method does not have to lock the destination key in order to attach a
-     payload. The fact that KEY_FLAG_INSTANTIATED is not set in key->flags
-     prevents anything else from gaining access to the key.
-
-     It is safe to sleep in this method.
-
-
  (*) int (*update)(struct key *key, const void *data, size_t datalen);
 
      If this type of key can be updated, then this method should be provided.

include/keys/user-type.h

@@ -35,7 +35,6 @@ struct user_key_payload {
 extern struct key_type key_type_user;
 
 extern int user_instantiate(struct key *key, const void *data, size_t datalen);
-extern int user_duplicate(struct key *key, const struct key *source);
 extern int user_update(struct key *key, const void *data, size_t datalen);
 extern int user_match(const struct key *key, const void *criterion);
 extern void user_destroy(struct key *key);

include/linux/key.h

@@ -193,14 +193,6 @@ struct key_type {
 	 */
 	int (*instantiate)(struct key *key, const void *data, size_t datalen);
 
-	/* duplicate a key of this type (optional)
-	 * - the source key will be locked against change
-	 * - the new description will be attached
-	 * - the quota will have been adjusted automatically from
-	 *   source->quotalen
-	 */
-	int (*duplicate)(struct key *key, const struct key *source);
-
 	/* update a key of this type (optional)
 	 * - this method should call key_payload_reserve() to recalculate the
 	 *   quota consumption

security/keys/key.c

@@ -240,9 +240,9 @@ static inline void key_alloc_serial(struct key *key)
 /*
  * allocate a key of the specified type
  * - update the user's quota to reflect the existence of the key
- * - called from a key-type operation with key_types_sem read-locked by either
- *   key_create_or_update() or by key_duplicate(); this prevents unregistration
- *   of the key type
+ * - called from a key-type operation with key_types_sem read-locked by
+ *   key_create_or_update()
+ *   - this prevents unregistration of the key type
  * - upon return the key is as yet uninstantiated; the caller needs to either
  *   instantiate the key or discard it before returning
  */
@@ -887,56 +887,6 @@ int key_update(key_ref_t key_ref, const void *payload, size_t plen)
 
 EXPORT_SYMBOL(key_update);
 
-/*****************************************************************************/
-/*
- * duplicate a key, potentially with a revised description
- * - must be supported by the keytype (keyrings for instance can be duplicated)
- */
-struct key *key_duplicate(struct key *source, const char *desc)
-{
-	struct key *key;
-	int ret;
-
-	key_check(source);
-
-	if (!desc)
-		desc = source->description;
-
-	down_read(&key_types_sem);
-
-	ret = -EINVAL;
-	if (!source->type->duplicate)
-		goto error;
-
-	/* allocate and instantiate a key */
-	key = key_alloc(source->type, desc, current->fsuid, current->fsgid,
-			source->perm, 0);
-	if (IS_ERR(key))
-		goto error_k;
-
-	down_read(&source->sem);
-	ret = key->type->duplicate(key, source);
-	up_read(&source->sem);
-	if (ret < 0)
-		goto error2;
-
-	atomic_inc(&key->user->nikeys);
-	set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
-
- error_k:
-	up_read(&key_types_sem);
- out:
-	return key;
-
- error2:
-	key_put(key);
- error:
-	up_read(&key_types_sem);
-	key = ERR_PTR(ret);
-	goto out;
-
-} /* end key_duplicate() */
-
 /*****************************************************************************/
 /*
  * revoke a key

security/keys/keyring.c

@@ -48,7 +48,6 @@ static inline unsigned keyring_hash(const char *desc)
  */
 static int keyring_instantiate(struct key *keyring,
 			       const void *data, size_t datalen);
-static int keyring_duplicate(struct key *keyring, const struct key *source);
 static int keyring_match(const struct key *keyring, const void *criterion);
 static void keyring_destroy(struct key *keyring);
 static void keyring_describe(const struct key *keyring, struct seq_file *m);
@@ -59,7 +58,6 @@ struct key_type key_type_keyring = {
 	.name		= "keyring",
 	.def_datalen	= sizeof(struct keyring_list),
 	.instantiate	= keyring_instantiate,
-	.duplicate	= keyring_duplicate,
 	.match		= keyring_match,
 	.destroy	= keyring_destroy,
 	.describe	= keyring_describe,
@@ -118,68 +116,6 @@ static int keyring_instantiate(struct key *keyring,
 
 } /* end keyring_instantiate() */
 
-/*****************************************************************************/
-/*
- * duplicate the list of subscribed keys from a source keyring into this one
- */
-static int keyring_duplicate(struct key *keyring, const struct key *source)
-{
-	struct keyring_list *sklist, *klist;
-	unsigned max;
-	size_t size;
-	int loop, ret;
-
-	const unsigned limit =
-		(PAGE_SIZE - sizeof(*klist)) / sizeof(struct key *);
-
-	ret = 0;
-
-	/* find out how many keys are currently linked */
-	rcu_read_lock();
-	sklist = rcu_dereference(source->payload.subscriptions);
-	max = 0;
-	if (sklist)
-		max = sklist->nkeys;
-	rcu_read_unlock();
-
-	/* allocate a new payload and stuff load with key links */
-	if (max > 0) {
-		BUG_ON(max > limit);
-
-		max = (max + 3) & ~3;
-		if (max > limit)
-			max = limit;
-
-		ret = -ENOMEM;
-		size = sizeof(*klist) + sizeof(struct key *) * max;
-		klist = kmalloc(size, GFP_KERNEL);
-		if (!klist)
-			goto error;
-
-		/* set links */
-		rcu_read_lock();
-		sklist = rcu_dereference(source->payload.subscriptions);
-
-		klist->maxkeys = max;
-		klist->nkeys = sklist->nkeys;
-		memcpy(klist->keys,
-		       sklist->keys,
-		       sklist->nkeys * sizeof(struct key *));
-
-		for (loop = klist->nkeys - 1; loop >= 0; loop--)
-			atomic_inc(&klist->keys[loop]->usage);
-
-		rcu_read_unlock();
-
-		rcu_assign_pointer(keyring->payload.subscriptions, klist);
-		ret = 0;
-	}
-
- error:
-	return ret;
-
-} /* end keyring_duplicate() */
-
 /*****************************************************************************/
 /*
  * match keyrings on their name

security/keys/user_defined.c

@@ -26,7 +26,6 @@
 struct key_type key_type_user = {
 	.name		= "user",
 	.instantiate	= user_instantiate,
-	.duplicate	= user_duplicate,
 	.update		= user_update,
 	.match		= user_match,
 	.destroy	= user_destroy,
@@ -68,40 +67,8 @@ int user_instantiate(struct key *key, const void *data, size_t datalen)
 	return ret;
 
 } /* end user_instantiate() */
-
 EXPORT_SYMBOL_GPL(user_instantiate);
 
-/*****************************************************************************/
-/*
- * duplicate a user defined key
- * - both keys' semaphores are locked against further modification
- * - the new key cannot yet be accessed
- */
-int user_duplicate(struct key *key, const struct key *source)
-{
-	struct user_key_payload *upayload, *spayload;
-	int ret;
-
-	/* just copy the payload */
-	ret = -ENOMEM;
-	upayload = kmalloc(sizeof(*upayload) + source->datalen, GFP_KERNEL);
-	if (upayload) {
-		spayload = rcu_dereference(source->payload.data);
-		BUG_ON(source->datalen != spayload->datalen);
-
-		upayload->datalen = key->datalen = spayload->datalen;
-		memcpy(upayload->data, spayload->data, key->datalen);
-
-		key->payload.data = upayload;
-		ret = 0;
-	}
-
-	return ret;
-
-} /* end user_duplicate() */
-
-EXPORT_SYMBOL_GPL(user_duplicate);
-
 /*****************************************************************************/
 /*
  * dispose of the old data from an updated user defined key