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Commit df593ee2 authored by David Howells's avatar David Howells
Browse files

keys: Hoist locking out of __key_link_begin() 



Hoist the locking of out of __key_link_begin() and into its callers.  This
is necessary to allow the upcoming key_move() operation to correctly order
taking of the source keyring semaphore, the destination keyring semaphore
and the keyring serialisation lock.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent eb0f68cb

security/keys/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -93,6 +93,8 @@ extern wait_queue_head_t request_key_conswq; 
extern struct key_type *key_type_lookup(const char *type);

extern void key_type_put(struct key_type *ktype);



extern int __key_link_lock(struct key *keyring,

			   const struct keyring_index_key *index_key);

extern int __key_link_begin(struct key *keyring,

			    const struct keyring_index_key *index_key,

			    struct assoc_array_edit **_edit);

security/keys/key.c

+21 −6
Original line number Diff line number Diff line
@@ -500,7 +500,7 @@ int key_instantiate_and_link(struct key *key, 
			     struct key *authkey)

{

	struct key_preparsed_payload prep;

	struct assoc_array_edit *edit;

	struct assoc_array_edit *edit = NULL;

	int ret;



	memset(&prep, 0, sizeof(prep));
@@ -515,10 +515,14 @@ int key_instantiate_and_link(struct key *key, 
	}



	if (keyring) {

		ret = __key_link_begin(keyring, &key->index_key, &edit);

		ret = __key_link_lock(keyring, &key->index_key);

		if (ret < 0)

			goto error;



		ret = __key_link_begin(keyring, &key->index_key, &edit);

		if (ret < 0)

			goto error_link_end;



		if (keyring->restrict_link && keyring->restrict_link->check) {

			struct key_restriction *keyres = keyring->restrict_link;
@@ -570,7 +574,7 @@ int key_reject_and_link(struct key *key, 
			struct key *keyring,

			struct key *authkey)

{

	struct assoc_array_edit *edit;

	struct assoc_array_edit *edit = NULL;

	int ret, awaken, link_ret = 0;



	key_check(key);
@@ -583,7 +587,12 @@ int key_reject_and_link(struct key *key, 
		if (keyring->restrict_link)

			return -EPERM;



		link_ret = __key_link_lock(keyring, &key->index_key);

		if (link_ret == 0) {

			link_ret = __key_link_begin(keyring, &key->index_key, &edit);

			if (link_ret < 0)

				__key_link_end(keyring, &key->index_key, edit);

		}

	}



	mutex_lock(&key_construction_mutex);
@@ -810,7 +819,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, 
		.description	= description,

	};

	struct key_preparsed_payload prep;

	struct assoc_array_edit *edit;

	struct assoc_array_edit *edit = NULL;

	const struct cred *cred = current_cred();

	struct key *keyring, *key = NULL;

	key_ref_t key_ref;
@@ -860,12 +869,18 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, 
	}

	index_key.desc_len = strlen(index_key.description);



	ret = __key_link_begin(keyring, &index_key, &edit);

	ret = __key_link_lock(keyring, &index_key);

	if (ret < 0) {

		key_ref = ERR_PTR(ret);

		goto error_free_prep;

	}



	ret = __key_link_begin(keyring, &index_key, &edit);

	if (ret < 0) {

		key_ref = ERR_PTR(ret);

		goto error_link_end;

	}



	if (restrict_link && restrict_link->check) {

		ret = restrict_link->check(keyring, index_key.type,

					   &prep.payload, restrict_link->key);

security/keys/keyring.c

+47 −31
Original line number Diff line number Diff line
@@ -1199,14 +1199,34 @@ static int keyring_detect_cycle(struct key *A, struct key *B) 
	return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);

}



/*

 * Lock keyring for link.

 */

int __key_link_lock(struct key *keyring,

		    const struct keyring_index_key *index_key)

	__acquires(&keyring->sem)

	__acquires(&keyring_serialise_link_lock)

{

	if (keyring->type != &key_type_keyring)

		return -ENOTDIR;



	down_write(&keyring->sem);



	/* Serialise link/link calls to prevent parallel calls causing a cycle

	 * when linking two keyring in opposite orders.

	 */

	if (index_key->type == &key_type_keyring)

		mutex_lock(&keyring_serialise_link_lock);



	return 0;

}



/*

 * Preallocate memory so that a key can be linked into to a keyring.

 */

int __key_link_begin(struct key *keyring,

		     const struct keyring_index_key *index_key,

		     struct assoc_array_edit **_edit)

	__acquires(&keyring->sem)

	__acquires(&keyring_serialise_link_lock)

{

	struct assoc_array_edit *edit;

	int ret;
@@ -1215,20 +1235,13 @@ int __key_link_begin(struct key *keyring, 
	       keyring->serial, index_key->type->name, index_key->description);



	BUG_ON(index_key->desc_len == 0);

	BUG_ON(*_edit != NULL);



	if (keyring->type != &key_type_keyring)

		return -ENOTDIR;



	down_write(&keyring->sem);

	*_edit = NULL;



	ret = -EKEYREVOKED;

	if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))

		goto error_krsem;



	/* serialise link/link calls to prevent parallel calls causing a cycle

	 * when linking two keyring in opposite orders */

	if (index_key->type == &key_type_keyring)

		mutex_lock(&keyring_serialise_link_lock);

		goto error;



	/* Create an edit script that will insert/replace the key in the

	 * keyring tree.
@@ -1239,7 +1252,7 @@ int __key_link_begin(struct key *keyring, 
				  NULL);

	if (IS_ERR(edit)) {

		ret = PTR_ERR(edit);

		goto error_sem;

		goto error;

	}



	/* If we're not replacing a link in-place then we're going to need some
@@ -1258,11 +1271,7 @@ int __key_link_begin(struct key *keyring, 


error_cancel:

	assoc_array_cancel_edit(edit);

error_sem:

	if (index_key->type == &key_type_keyring)

		mutex_unlock(&keyring_serialise_link_lock);

error_krsem:

	up_write(&keyring->sem);

error:

	kleave(" = %d", ret);

	return ret;

}
@@ -1312,9 +1321,6 @@ void __key_link_end(struct key *keyring, 
	BUG_ON(index_key->type == NULL);

	kenter("%d,%s,", keyring->serial, index_key->type->name);



	if (index_key->type == &key_type_keyring)

		mutex_unlock(&keyring_serialise_link_lock);



	if (edit) {

		if (!edit->dead_leaf) {

			key_payload_reserve(keyring,
@@ -1323,6 +1329,9 @@ void __key_link_end(struct key *keyring, 
		assoc_array_cancel_edit(edit);

	}

	up_write(&keyring->sem);



	if (index_key->type == &key_type_keyring)

		mutex_unlock(&keyring_serialise_link_lock);

}



/*
@@ -1358,7 +1367,7 @@ static int __key_link_check_restriction(struct key *keyring, struct key *key) 
 */

int key_link(struct key *keyring, struct key *key)

{

	struct assoc_array_edit *edit;

	struct assoc_array_edit *edit = NULL;

	int ret;



	kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
@@ -1366,17 +1375,24 @@ int key_link(struct key *keyring, struct key *key) 
	key_check(keyring);

	key_check(key);



	ret = __key_link_lock(keyring, &key->index_key);

	if (ret < 0)

		goto error;



	ret = __key_link_begin(keyring, &key->index_key, &edit);

	if (ret == 0) {

	if (ret < 0)

		goto error_end;



	kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));

	ret = __key_link_check_restriction(keyring, key);

	if (ret == 0)

		ret = __key_link_check_live_key(keyring, key);

	if (ret == 0)

		__key_link(key, &edit);

		__key_link_end(keyring, &key->index_key, edit);

	}



error_end:

	__key_link_end(keyring, &key->index_key, edit);

error:

	kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));

	return ret;

}

security/keys/request_key.c

+6 −1
Original line number Diff line number Diff line
@@ -343,7 +343,7 @@ static int construct_alloc_key(struct keyring_search_context *ctx, 
			       struct key_user *user,

			       struct key **_key)

{

	struct assoc_array_edit *edit;

	struct assoc_array_edit *edit = NULL;

	struct key *key;

	key_perm_t perm;

	key_ref_t key_ref;
@@ -372,6 +372,9 @@ static int construct_alloc_key(struct keyring_search_context *ctx, 
	set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);



	if (dest_keyring) {

		ret = __key_link_lock(dest_keyring, &ctx->index_key);

		if (ret < 0)

			goto link_lock_failed;

		ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);

		if (ret < 0)

			goto link_prealloc_failed;
@@ -423,6 +426,8 @@ static int construct_alloc_key(struct keyring_search_context *ctx, 
	return ret;



link_prealloc_failed:

	__key_link_end(dest_keyring, &ctx->index_key, edit);

link_lock_failed:

	mutex_unlock(&user->cons_lock);

	key_put(key);

	kleave(" = %d [prelink]", ret);