From 1728ca444f9858041b1b9a3df17cf710b4bdd7ec Mon Sep 17 00:00:00 2001 From: Wei Yongjun Date: Fri, 10 Oct 2008 14:33:52 +0800 Subject: [PATCH 2/4] sctp: Add check for the TSN field of the SHUTDOWN chunk If SHUTDOWN chunk is received Cumulative TSN Ack beyond the max tsn currently send, SHUTDOWN chunk be accepted and the association will be broken. New data is send, but after received SACK it will be drop because TSN in SACK is less than the Cumulative TSN, data will be retrans again and again even if correct SACK is received. The packet sequence is like this: Endpoint A Endpoint B ULP (ESTABLISHED) (ESTABLISHED) <----------- DATA (TSN=x-1) <----------- DATA (TSN=x) SHUTDOWN -----------> (Now Cumulative TSN=x+1000) (TSN=x+1000) <----------- DATA (TSN=x+1) SACK -----------> drop the SACK (TSN=x+1) <----------- DATA (TSN=x+1)(retrans) This patch fix this problem by terminating the association and respond to the sender with an ABORT. Signed-off-by: Wei Yongjun Signed-off-by: Vlad Yasevich --- net/sctp/sm_statefuns.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index d4c3fbc..12f6217 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -2544,6 +2544,7 @@ sctp_disposition_t sctp_sf_do_9_2_shutdown(const struct sctp_endpoint *ep, sctp_shutdownhdr_t *sdh; sctp_disposition_t disposition; struct sctp_ulpevent *ev; + __u32 ctsn; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(ep, asoc, type, arg, commands); @@ -2558,6 +2559,14 @@ sctp_disposition_t sctp_sf_do_9_2_shutdown(const struct sctp_endpoint *ep, sdh = (sctp_shutdownhdr_t *)chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_shutdownhdr_t)); chunk->subh.shutdown_hdr = sdh; + ctsn = ntohl(sdh->cum_tsn_ack); + + /* If Cumulative TSN Ack beyond the max tsn currently + * send, terminating the association and respond to the + * sender with an ABORT. + */ + if (!TSN_lt(ctsn, asoc->next_tsn)) + return sctp_sf_violation_ctsn(ep, asoc, type, arg, commands); /* API 5.3.1.5 SCTP_SHUTDOWN_EVENT * When a peer sends a SHUTDOWN, SCTP delivers this notification to -- 1.5.3.5