[SCTP]: Update ASCONF processing to conform to spec.
The processing of the ASCONF chunks has changed a lot in the
spec. New items are:
1. A list of ASCONF-ACK chunks is now cached
2. The source of the packet is used in response.
3. New handling for unexpect ASCONF chunks.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index b6aaa7e..a1be9d9 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -3402,48 +3402,68 @@
/* Verify the ASCONF chunk before processing it. */
if (!sctp_verify_asconf(asoc,
- (sctp_paramhdr_t *)((void *)addr_param + length),
- (void *)chunk->chunk_end,
- &err_param))
+ (sctp_paramhdr_t *)((void *)addr_param + length),
+ (void *)chunk->chunk_end,
+ &err_param))
return sctp_sf_violation_paramlen(ep, asoc, type,
- (void *)&err_param, commands);
+ (void *)&err_param, commands);
- /* ADDIP 4.2 C1) Compare the value of the serial number to the value
+ /* ADDIP 5.2 E1) Compare the value of the serial number to the value
* the endpoint stored in a new association variable
* 'Peer-Serial-Number'.
*/
if (serial == asoc->peer.addip_serial + 1) {
- /* ADDIP 4.2 C2) If the value found in the serial number is
- * equal to the ('Peer-Serial-Number' + 1), the endpoint MUST
- * do V1-V5.
+ /* If this is the first instance of ASCONF in the packet,
+ * we can clean our old ASCONF-ACKs.
+ */
+ if (!chunk->has_asconf)
+ sctp_assoc_clean_asconf_ack_cache(asoc);
+
+ /* ADDIP 5.2 E4) When the Sequence Number matches the next one
+ * expected, process the ASCONF as described below and after
+ * processing the ASCONF Chunk, append an ASCONF-ACK Chunk to
+ * the response packet and cache a copy of it (in the event it
+ * later needs to be retransmitted).
+ *
+ * Essentially, do V1-V5.
*/
asconf_ack = sctp_process_asconf((struct sctp_association *)
asoc, chunk);
if (!asconf_ack)
return SCTP_DISPOSITION_NOMEM;
- } else if (serial == asoc->peer.addip_serial) {
- /* ADDIP 4.2 C3) If the value found in the serial number is
- * equal to the value stored in the 'Peer-Serial-Number'
- * IMPLEMENTATION NOTE: As an optimization a receiver may wish
- * to save the last ASCONF-ACK for some predetermined period of
- * time and instead of re-processing the ASCONF (with the same
- * serial number) it may just re-transmit the ASCONF-ACK.
+ } else if (serial < asoc->peer.addip_serial + 1) {
+ /* ADDIP 5.2 E2)
+ * If the value found in the Sequence Number is less than the
+ * ('Peer- Sequence-Number' + 1), simply skip to the next
+ * ASCONF, and include in the outbound response packet
+ * any previously cached ASCONF-ACK response that was
+ * sent and saved that matches the Sequence Number of the
+ * ASCONF. Note: It is possible that no cached ASCONF-ACK
+ * Chunk exists. This will occur when an older ASCONF
+ * arrives out of order. In such a case, the receiver
+ * should skip the ASCONF Chunk and not include ASCONF-ACK
+ * Chunk for that chunk.
*/
- if (asoc->addip_last_asconf_ack)
- asconf_ack = asoc->addip_last_asconf_ack;
- else
+ asconf_ack = sctp_assoc_lookup_asconf_ack(asoc, hdr->serial);
+ if (!asconf_ack)
return SCTP_DISPOSITION_DISCARD;
} else {
- /* ADDIP 4.2 C4) Otherwise, the ASCONF Chunk is discarded since
+ /* ADDIP 5.2 E5) Otherwise, the ASCONF Chunk is discarded since
* it must be either a stale packet or from an attacker.
*/
return SCTP_DISPOSITION_DISCARD;
}
- /* ADDIP 4.2 C5) In both cases C2 and C3 the ASCONF-ACK MUST be sent
- * back to the source address contained in the IP header of the ASCONF
- * being responded to.
+ /* ADDIP 5.2 E6) The destination address of the SCTP packet
+ * containing the ASCONF-ACK Chunks MUST be the source address of
+ * the SCTP packet that held the ASCONF Chunks.
+ *
+ * To do this properly, we'll set the destination address of the chunk
+ * and at the transmit time, will try look up the transport to use.
+ * Since ASCONFs may be bundled, the correct transport may not be
+ * created untill we process the entire packet, thus this workaround.
*/
+ asconf_ack->dest = chunk->source;
sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
return SCTP_DISPOSITION_CONSUME;