KEYS: Allow expiry time to be set when preparsing a key

Allow a key type's preparsing routine to set the expiry time for a key.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NSteve Dickson <steved@redhat.com>
Acked-by: NJeff Layton <jlayton@primarydata.com>
Reviewed-by: NSage Weil <sage@redhat.com>

Documentation/security/keys.txt

@@ -1150,20 +1150,24 @@ The structure has a number of fields, some of which are mandatory:
 		const void	*data;
 		size_t		datalen;
 		size_t		quotalen;
+		time_t		expiry;
 	};
 
      Before calling the method, the caller will fill in data and datalen with
      the payload blob parameters; quotalen will be filled in with the default
-     quota size from the key type and the rest will be cleared.
+     quota size from the key type; expiry will be set to TIME_T_MAX and the
+     rest will be cleared.
 
      If a description can be proposed from the payload contents, that should be
      attached as a string to the description field.  This will be used for the
      key description if the caller of add_key() passes NULL or "".
 
      The method can attach anything it likes to type_data[] and payload.  These
-     are merely passed along to the instantiate() or update() operations.
+     are merely passed along to the instantiate() or update() operations.  If
+     set, the expiry time will be applied to the key if it is instantiated from
+     this data.
 
-     The method should return 0 if success ful or a negative error code
+     The method should return 0 if successful or a negative error code
      otherwise.
 
      

include/linux/key-type.h

@@ -45,6 +45,7 @@ struct key_preparsed_payload {
 	const void	*data;		/* Raw data */
 	size_t		datalen;	/* Raw datalen */
 	size_t		quotalen;	/* Quota length for proposed payload */
+	time_t		expiry;		/* Expiry time of key */
 	bool		trusted;	/* True if key is trusted */
 };
 

security/keys/key.c

@@ -437,6 +437,11 @@ static int __key_instantiate_and_link(struct key *key,
 			/* disable the authorisation key */
 			if (authkey)
 				key_revoke(authkey);
+
+			if (prep->expiry != TIME_T_MAX) {
+				key->expiry = prep->expiry;
+				key_schedule_gc(prep->expiry + key_gc_delay);
+			}
 		}
 	}
 
@@ -479,6 +484,7 @@ int key_instantiate_and_link(struct key *key,
 	prep.data = data;
 	prep.datalen = datalen;
 	prep.quotalen = key->type->def_datalen;
+	prep.expiry = TIME_T_MAX;
 	if (key->type->preparse) {
 		ret = key->type->preparse(&prep);
 		if (ret < 0)
@@ -811,6 +817,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 	prep.datalen = plen;
 	prep.quotalen = index_key.type->def_datalen;
 	prep.trusted = flags & KEY_ALLOC_TRUSTED;
+	prep.expiry = TIME_T_MAX;
 	if (index_key.type->preparse) {
 		ret = index_key.type->preparse(&prep);
 		if (ret < 0) {
@@ -941,6 +948,7 @@ int key_update(key_ref_t key_ref, const void *payload, size_t plen)
 	prep.data = payload;
 	prep.datalen = plen;
 	prep.quotalen = key->type->def_datalen;
+	prep.expiry = TIME_T_MAX;
 	if (key->type->preparse) {
 		ret = key->type->preparse(&prep);
 		if (ret < 0)