keys: Provide request_key_rcu() (896f1950) · Commits · 戴 / test

Documentation/security/keys/core.rst

+10 −0

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		@@ -1147,6 +1147,16 @@ payload contents" for more information.
		case error ERESTARTSYS will be returned.


		* To search for a key under RCU conditions, call::

		struct key request_key_rcu(const struct key_type type,
		const char *description);

		which is similar to request_key() except that it does not check for keys
		that are under construction and it will not call out to userspace to
		construct a key if it can't find a match.


		* When it is no longer required, the key should be released using::

		void key_put(struct key *key);

+9 −0

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		@@ -36,6 +36,11 @@ or::
		size_t callout_len,
		void *aux);

		or::

		struct key request_key_rcu(const struct key_type type,
		const char *description);

		Or by userspace invoking the request_key system call::

		key_serial_t request_key(const char *type,
		@@ -57,6 +62,10 @@ The two async in-kernel calls may return keys that are still in the process of
		being constructed. The two non-async ones will wait for construction to
		complete first.

		The request_key_rcu() call is like the in-kernel request_key() call, except
		that it doesn't check for keys that are under construction and doesn't attempt
		to construct missing keys.

		The userspace interface links the key to a keyring associated with the process
		to prevent the key from going away, and returns the serial number of the key to
		the caller.

+3 −0

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		@@ -274,6 +274,9 @@ extern struct key request_key(struct key_type type,
		const char *description,
		const char *callout_info);

		extern struct key request_key_rcu(struct key_type type,
		const char *description);

		extern struct key request_key_with_auxdata(struct key_type type,
		const char *description,
		const void *callout_info,

+44 −0

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		@@ -756,3 +756,47 @@ struct key request_key_async_with_auxdata(struct key_type type,
		callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
		}
		EXPORT_SYMBOL(request_key_async_with_auxdata);

		/**
		* request_key_rcu - Request key from RCU-read-locked context
		* @type: The type of key we want.
		* @description: The name of the key we want.
		*
		* Request a key from a context that we may not sleep in (such as RCU-mode
		* pathwalk). Keys under construction are ignored.
		*
		* Return a pointer to the found key if successful, -ENOKEY if we couldn't find
		* a key or some other error if the key found was unsuitable or inaccessible.
		*/
		struct key request_key_rcu(struct key_type type, const char *description)
		{
		struct keyring_search_context ctx = {
		.index_key.type = type,
		.index_key.description = description,
		.index_key.desc_len = strlen(description),
		.cred = current_cred(),
		.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 \|
		KEYRING_SEARCH_SKIP_EXPIRED),
		};
		struct key *key;
		key_ref_t key_ref;

		kenter("%s,%s", type->name, description);

		/* search all the process keyrings for a key */
		key_ref = search_process_keyrings_rcu(&ctx);
		if (IS_ERR(key_ref)) {
		key = ERR_CAST(key_ref);
		if (PTR_ERR(key_ref) == -EAGAIN)
		key = ERR_PTR(-ENOKEY);
		} else {
		key = key_ref_to_ptr(key_ref);
		}

		kleave(" = %p", key);
		return key;
		}
		EXPORT_SYMBOL(request_key_rcu);