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authorXin Long <lucien.xin@gmail.com>2017-04-15 17:00:27 +0300
committerDavid S. Miller <davem@davemloft.net>2017-04-18 20:39:50 +0300
commite4dc99c7c21ba456fd72a70ada5d8d5f3850bcf5 (patch)
tree229495a2bb00111e9bc642e29872b05d508e3a84 /net/sctp
parentb89f04c61efe3b7756434d693b9203cc0cce002e (diff)
downloadlinux-e4dc99c7c21ba456fd72a70ada5d8d5f3850bcf5.tar.xz
sctp: process duplicated strreset out and addstrm out requests correctly
Now sctp stream reconf will process a request again even if it's seqno is less than asoc->strreset_inseq. If one request has been done successfully and some data chunks have been accepted and then a duplicated strreset out request comes, the streamin's ssn will be cleared. It will cause that stream will never receive chunks any more because of unsynchronized ssn. It allows a replay attack. A similar issue also exists when processing addstrm out requests. It will cause more extra streams being added. This patch is to fix it by saving the last 2 results into asoc. When a duplicated strreset out or addstrm out 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. Note that it saves last 2 results instead of only last 1 result, because two requests can be sent together in one chunk. And note that when receiving a duplicated request, the receiver side will still reply it even if the peer has received the response. It's safe, As the response will be dropped by the peer. Signed-off-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sctp')
-rw-r--r--net/sctp/stream.c39
1 files changed, 29 insertions, 10 deletions
diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index 4ec3679a1cef..6cab7c3721a3 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -344,6 +344,13 @@ static sctp_paramhdr_t *sctp_chunk_lookup_strreset_param(
return NULL;
}
+static void sctp_update_strreset_result(struct sctp_association *asoc,
+ __u32 result)
+{
+ asoc->strreset_result[1] = asoc->strreset_result[0];
+ asoc->strreset_result[0] = result;
+}
+
struct sctp_chunk *sctp_process_strreset_outreq(
struct sctp_association *asoc,
union sctp_params param,
@@ -360,15 +367,19 @@ struct sctp_chunk *sctp_process_strreset_outreq(
if (ntohl(outreq->send_reset_at_tsn) >
sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map)) {
result = SCTP_STRRESET_IN_PROGRESS;
- goto out;
+ goto err;
}
- 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];
+ goto err;
}
+ asoc->strreset_inseq++;
/* Check strreset_enable after inseq inc, as sender cannot tell
* the peer doesn't enable strreset after receiving response with
@@ -427,6 +438,8 @@ struct sctp_chunk *sctp_process_strreset_outreq(
GFP_ATOMIC);
out:
+ sctp_update_strreset_result(asoc, result);
+err:
return sctp_make_strreset_resp(asoc, result, request_seq);
}
@@ -582,15 +595,19 @@ struct sctp_chunk *sctp_process_strreset_addstrm_out(
__u32 result = SCTP_STRRESET_DENIED;
struct sctp_stream_in *streamin;
__u32 request_seq, incnt;
- __u16 in;
+ __u16 in, 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];
+ goto err;
}
+ asoc->strreset_inseq++;
if (!(asoc->strreset_enable & SCTP_ENABLE_CHANGE_ASSOC_REQ))
goto out;
@@ -638,6 +655,8 @@ struct sctp_chunk *sctp_process_strreset_addstrm_out(
0, ntohs(addstrm->number_of_streams), 0, GFP_ATOMIC);
out:
+ sctp_update_strreset_result(asoc, result);
+err:
return sctp_make_strreset_resp(asoc, result, request_seq);
}