SCTP: properly clean up fragment and ordering queues during FWD-TSN.

When we recieve a FWD-TSN (meaning the peer has abandoned the data),
we need to clean up any partially received messages that may be
hanging out on the re-assembly or re-ordering queues.  This is
a MUST requirement that was not properly done before.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com.>

2 files changed, 65 insertions, 13 deletions

diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index d9fad4f6ffc..1907318e70f 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1130,6 +1130,9 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
                         /* Move the Cumulattive TSN Ack ahead. */
                         sctp_tsnmap_skip(&asoc->peer.tsn_map, cmd->obj.u32);
 
+                        /* purge the fragmentation queue */
+                        sctp_ulpq_reasm_flushtsn(&asoc->ulpq, cmd->obj.u32);
+
                         /* Abort any in progress partial delivery. */
                         sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
                         break;
diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c
index 34eb977a204..fa0ba2a5564 100644
--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -659,6 +659,46 @@ done:
         return retval;
 }
 
+/*
+ * Flush out stale fragments from the reassembly queue when processing
+ * a Forward TSN.
+ *
+ * RFC 3758, Section 3.6
+ *
+ * After receiving and processing a FORWARD TSN, the data receiver MUST
+ * take cautions in updating its re-assembly queue.  The receiver MUST
+ * remove any partially reassembled message, which is still missing one
+ * or more TSNs earlier than or equal to the new cumulative TSN point.
+ * In the event that the receiver has invoked the partial delivery API,
+ * a notification SHOULD also be generated to inform the upper layer API
+ * that the message being partially delivered will NOT be completed.
+ */
+void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *ulpq, __u32 fwd_tsn)
+{
+        struct sk_buff *pos, *tmp;
+        struct sctp_ulpevent *event;
+        __u32 tsn;
+
+        if (skb_queue_empty(&ulpq->reasm))
+                return;
+
+        skb_queue_walk_safe(&ulpq->reasm, pos, tmp) {
+                event = sctp_skb2event(pos);
+                tsn = event->tsn;
+
+                /* Since the entire message must be abandoned by the
+                 * sender (item A3 in Section 3.5, RFC 3758), we can
+                 * free all fragments on the list that are less then
+                 * or equal to ctsn_point
+                 */
+                if (TSN_lte(tsn, fwd_tsn)) {
+                        __skb_unlink(pos, &ulpq->reasm);
+                        sctp_ulpevent_free(event);
+                } else
+                        break;
+        }
+}
+
 /* Helper function to gather skbs that have possibly become
  * ordered by an an incoming chunk.
  */
@@ -794,7 +834,7 @@ static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
 /* Helper function to gather skbs that have possibly become
  * ordered by forward tsn skipping their dependencies.
  */
-static inline void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq)
+static inline void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq, __u16 sid)
 {
         struct sk_buff *pos, *tmp;
         struct sctp_ulpevent *cevent;
@@ -813,31 +853,40 @@ static inline void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq)
                 csid = cevent->stream;
                 cssn = cevent->ssn;
 
-                if (cssn != sctp_ssn_peek(in, csid))
+                /* Have we gone too far?  */
+                if (csid > sid)
                         break;
 
-                /* Found it, so mark in the ssnmap. */
-                sctp_ssn_next(in, csid);
+                /* Have we not gone far enough?  */
+                if (csid < sid)
+                        continue;
+
+                /* see if this ssn has been marked by skipping */
+                if (!SSN_lt(cssn, sctp_ssn_peek(in, csid)))
+                        break;
 
                 __skb_unlink(pos, &ulpq->lobby);
-                if (!event) {
+                if (!event)
                         /* Create a temporary list to collect chunks on.  */
                         event = sctp_skb2event(pos);
-                        __skb_queue_tail(&temp, sctp_event2skb(event));
-                } else {
-                        /* Attach all gathered skbs to the event.  */
-                        __skb_queue_tail(&temp, pos);
-                }
+
+                /* Attach all gathered skbs to the event.  */
+                __skb_queue_tail(&temp, pos);
         }
 
         /* Send event to the ULP.  'event' is the sctp_ulpevent for
          * very first SKB on the 'temp' list.
          */
-        if (event)
+        if (event) {
+                /* see if we have more ordered that we can deliver */
+                sctp_ulpq_retrieve_ordered(ulpq, event);
                 sctp_ulpq_tail_event(ulpq, event);
+        }
 }
 
-/* Skip over an SSN. */
+/* Skip over an SSN. This is used during the processing of
+ * Forwared TSN chunk to skip over the abandoned ordered data
+ */
 void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
 {
         struct sctp_stream *in;
@@ -855,7 +904,7 @@ void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
         /* Go find any other chunks that were waiting for
          * ordering and deliver them if needed.
          */
-        sctp_ulpq_reap_ordered(ulpq);
+        sctp_ulpq_reap_ordered(ulpq, sid);
         return;
 }