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Commit d0f025e6 authored by Xin Long's avatar Xin Long Committed by David S. Miller
Browse files

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: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e4dc99c7

net/sctp/stream.c

+29 −9
Original line number Diff line number Diff line
@@ -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);