sctp: allow authenticating DATA chunks that are bundled with COOKIE_ECHO

Currently, we can ask to authenticate DATA chunks and we can send DATA
chunks on the same packet as COOKIE_ECHO, but if you try to combine
both, the DATA chunk will be sent unauthenticated and peer won't accept
it, leading to a communication failure.

This happens because even though the data was queued after it was
requested to authenticate DATA chunks, it was also queued before we
could know that remote peer can handle authenticating, so
sctp_auth_send_cid() returns false.

The fix is whenever we set up an active key, re-check send queue for
chunks that now should be authenticated. As a result, such packet will
now contain COOKIE_ECHO + AUTH + DATA chunks, in that order.

Reported-by: Liu Wei <[e-mail]>
Signed-off-by: Marcelo Ricardo Leitner <[e-mail]>
Acked-by: Neil Horman <[e-mail]>
Acked-by: Vlad Yasevich <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/sctp/auth.c

···
 }
 
 
-/* Public interface to creat the association shared key.
+/* Public interface to create the association shared key.
  * See code above for the algorithm.
  */
 int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
 {
 	struct sctp_auth_bytes	*secret;
 	struct sctp_shared_key *ep_key;
+	struct sctp_chunk *chunk;
 
 	/* If we don't support AUTH, or peer is not capable
 	 * we don't need to do anything.
···
 
 	sctp_auth_key_put(asoc->asoc_shared_key);
 	asoc->asoc_shared_key = secret;
+
+	/* Update send queue in case any chunk already in there now
+	 * needs authenticating
+	 */
+	list_for_each_entry(chunk, &asoc->outqueue.out_chunk_list, list) {
+		if (sctp_auth_send_cid(chunk->chunk_hdr->type, asoc))
+			chunk->auth = 1;
+	}
 
 	return 0;
 }