sctp: send abort chunk when max_retrans exceeded

In the event that an association exceeds its max_retrans attempts, we should
send an ABORT chunk indicating that we are closing the assocation as a result.
Because of the nature of the error, its unlikely to be received, but its a nice
clean way to close the association if it does make it through, and it will give
anyone watching via tcpdump a clue as to what happened.

Change notes:
v2)
	* Removed erroneous changes from sctp_make_violation_parmlen

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: linux-sctp@vger.kernel.org
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 29 insertions, 1 deletions

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index b5887e1677e4..2a82d1384706 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -234,6 +234,8 @@ struct sctp_chunk *sctp_make_abort_violation(const struct sctp_association *,
 struct sctp_chunk *sctp_make_violation_paramlen(const struct sctp_association *,
                                    const struct sctp_chunk *,
                                    struct sctp_paramhdr *);
+struct sctp_chunk *sctp_make_violation_max_retrans(const struct sctp_association *,
+                                                   const struct sctp_chunk *);
 struct sctp_chunk *sctp_make_heartbeat(const struct sctp_association *,
                                   const struct sctp_transport *);
 struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *,
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index fbe1636309a7..e0f01a4e8cd6 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1090,6 +1090,25 @@ nodata:
         return retval;
 }
 
+struct sctp_chunk *sctp_make_violation_max_retrans(
+        const struct sctp_association *asoc,
+        const struct sctp_chunk *chunk)
+{
+        struct sctp_chunk *retval;
+        static const char error[] = "Association exceeded its max_retans count";
+        size_t payload_len = sizeof(error) + sizeof(sctp_errhdr_t);
+
+        retval = sctp_make_abort(asoc, chunk, payload_len);
+        if (!retval)
+                goto nodata;
+
+        sctp_init_cause(retval, SCTP_ERROR_PROTO_VIOLATION, sizeof(error));
+        sctp_addto_chunk(retval, sizeof(error), error);
+
+nodata:
+        return retval;
+}
+
 /* Make a HEARTBEAT chunk.  */
 struct sctp_chunk *sctp_make_heartbeat(const struct sctp_association *asoc,
                                   const struct sctp_transport *transport)
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 6eecf7e6338d..c0769569b05d 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -577,7 +577,7 @@ static void sctp_cmd_assoc_failed(sctp_cmd_seq_t *commands,
                                   unsigned int error)
 {
         struct sctp_ulpevent *event;
-
+        struct sctp_chunk *abort;
         /* Cancel any partial delivery in progress. */
         sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
 
@@ -593,6 +593,13 @@ static void sctp_cmd_assoc_failed(sctp_cmd_seq_t *commands,
                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                                 SCTP_ULPEVENT(event));
 
+        if (asoc->overall_error_count >= asoc->max_retrans) {
+                abort = sctp_make_violation_max_retrans(asoc, chunk);
+                if (abort)
+                        sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
+                                        SCTP_CHUNK(abort));
+        }
+
         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
                         SCTP_STATE(SCTP_STATE_CLOSED));