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 <lucien.xin@xxxxxxxxx>
---
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 6cab7c3..c91d97e 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);
--
2.1.0
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