From d0f025e611581169c81e3c0fc44b5133d12748dd Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sat, 15 Apr 2017 22:00:28 +0800 Subject: [PATCH] sctp: process duplicated strreset in and addstrm in requests correctly This patch is to fix the replay attack issue for strreset and addstrm in requests. When a duplicated strreset in or addstrm in request is received, reply it with bad seqno if it's seqno < asoc->strreset_inseq - 2, and reply it with the result saved in asoc if it's seqno >= asoc->strreset_inseq - 2. For strreset in or addstrm in request, if the receiver side processes it successfully, a strreset out or addstrm out request(as a response for that request) will be sent back to peer. reconf_time will retransmit the out request even if it's lost. So when receiving a duplicated strreset in or addstrm in request and it's result was performed, it shouldn't reply this request, but drop it instead. Signed-off-by: Xin Long Signed-off-by: David S. Miller --- net/sctp/stream.c | 38 +++++++++++++++++++++++++++++--------- 1 file changed, 29 insertions(+), 9 deletions(-) diff --git a/net/sctp/stream.c b/net/sctp/stream.c index 6cab7c3721a3..c91d97e5d590 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -456,12 +456,18 @@ struct sctp_chunk *sctp_process_strreset_inreq( __u32 request_seq; request_seq = ntohl(inreq->request_seq); - if (request_seq > asoc->strreset_inseq) { + if (TSN_lt(asoc->strreset_inseq, request_seq) || + TSN_lt(request_seq, asoc->strreset_inseq - 2)) { result = SCTP_STRRESET_ERR_BAD_SEQNO; - goto out; - } else if (request_seq == asoc->strreset_inseq) { - asoc->strreset_inseq++; + goto err; + } else if (TSN_lt(request_seq, asoc->strreset_inseq)) { + i = asoc->strreset_inseq - request_seq - 1; + result = asoc->strreset_result[i]; + if (result == SCTP_STRRESET_PERFORMED) + return NULL; + goto err; } + asoc->strreset_inseq++; if (!(asoc->strreset_enable & SCTP_ENABLE_RESET_STREAM_REQ)) goto out; @@ -496,10 +502,14 @@ struct sctp_chunk *sctp_process_strreset_inreq( asoc->strreset_outstanding = 1; sctp_chunk_hold(asoc->strreset_chunk); + result = SCTP_STRRESET_PERFORMED; + *evp = sctp_ulpevent_make_stream_reset_event(asoc, SCTP_STREAM_RESET_INCOMING_SSN, nums, str_p, GFP_ATOMIC); out: + sctp_update_strreset_result(asoc, result); +err: if (!chunk) chunk = sctp_make_strreset_resp(asoc, result, request_seq); @@ -671,15 +681,21 @@ struct sctp_chunk *sctp_process_strreset_addstrm_in( struct sctp_stream_out *streamout; struct sctp_chunk *chunk = NULL; __u32 request_seq, outcnt; - __u16 out; + __u16 out, i; request_seq = ntohl(addstrm->request_seq); - if (request_seq > asoc->strreset_inseq) { + if (TSN_lt(asoc->strreset_inseq, request_seq) || + TSN_lt(request_seq, asoc->strreset_inseq - 2)) { result = SCTP_STRRESET_ERR_BAD_SEQNO; - goto out; - } else if (request_seq == asoc->strreset_inseq) { - asoc->strreset_inseq++; + goto err; + } else if (TSN_lt(request_seq, asoc->strreset_inseq)) { + i = asoc->strreset_inseq - request_seq - 1; + result = asoc->strreset_result[i]; + if (result == SCTP_STRRESET_PERFORMED) + return NULL; + goto err; } + asoc->strreset_inseq++; if (!(asoc->strreset_enable & SCTP_ENABLE_CHANGE_ASSOC_REQ)) goto out; @@ -712,10 +728,14 @@ struct sctp_chunk *sctp_process_strreset_addstrm_in( stream->outcnt = outcnt; + result = SCTP_STRRESET_PERFORMED; + *evp = sctp_ulpevent_make_stream_change_event(asoc, 0, 0, ntohs(addstrm->number_of_streams), GFP_ATOMIC); out: + sctp_update_strreset_result(asoc, result); +err: if (!chunk) chunk = sctp_make_strreset_resp(asoc, result, request_seq); -- 2.20.1