[SCTP]: Verify some mandatory parameters.

Verify init_tag and a_rwnd mandatory parameters in INIT and
INIT-ACK chunks.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_make_chunk.c

@@ -1775,7 +1775,9 @@ int sctp_verify_init(const struct sctp_association *asoc,
 
 	/* Verify stream values are non-zero. */
 	if ((0 == peer_init->init_hdr.num_outbound_streams) ||
-	    (0 == peer_init->init_hdr.num_inbound_streams)) {
+	    (0 == peer_init->init_hdr.num_inbound_streams) ||
+	    (0 == peer_init->init_hdr.init_tag) ||
+	    (SCTP_DEFAULT_MINWINDOW > ntohl(peer_init->init_hdr.a_rwnd))) {
 
 		sctp_process_inv_mandatory(asoc, chunk, errp);
 		return 0;

net/sctp/sm_statefuns.c

@@ -440,7 +440,6 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep,
 {
 	struct sctp_chunk *chunk = arg;
 	sctp_init_chunk_t *initchunk;
-	__u32 init_tag;
 	struct sctp_chunk *err_chunk;
 	struct sctp_packet *packet;
 	sctp_error_t error;
@@ -462,24 +461,6 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep,
 	/* Grab the INIT header.  */
 	chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data;
 
-	init_tag = ntohl(chunk->subh.init_hdr->init_tag);
-
-	/* Verification Tag: 3.3.3
-	 *   If the value of the Initiate Tag in a received INIT ACK
-	 *   chunk is found to be 0, the receiver MUST treat it as an
-	 *   error and close the association by transmitting an ABORT.
-	 */
-	if (!init_tag) {
-		struct sctp_chunk *reply = sctp_make_abort(asoc, chunk, 0);
-		if (!reply)
-			goto nomem;
-
-		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
-		return sctp_stop_t1_and_abort(commands, SCTP_ERROR_INV_PARAM,
-					      ECONNREFUSED, asoc,
-					      chunk->transport);
-	}
-
 	/* Verify the INIT chunk before processing it. */
 	err_chunk = NULL;
 	if (!sctp_verify_init(asoc, chunk->chunk_hdr->type,