sctp: Fix to handle SHUTDOWN in SHUTDOWN_RECEIVED state

Once an endpoint has reached the SHUTDOWN-RECEIVED state,
it MUST NOT send a SHUTDOWN in response to a ULP request.
The Cumulative TSN Ack of the received SHUTDOWN chunk
MUST be processed.

This patch fix to process Cumulative TSN Ack of the received
SHUTDOWN chunk in SHUTDOWN_RECEIVED state.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 47 insertions, 1 deletions

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 029a54a02396..c1dd89365833 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -125,6 +125,7 @@ sctp_state_fn_t sctp_sf_beat_8_3;
 sctp_state_fn_t sctp_sf_backbeat_8_3;
 sctp_state_fn_t sctp_sf_do_9_2_final;
 sctp_state_fn_t sctp_sf_do_9_2_shutdown;
+sctp_state_fn_t sctp_sf_do_9_2_shut_ctsn;
 sctp_state_fn_t sctp_sf_do_ecn_cwr;
 sctp_state_fn_t sctp_sf_do_ecne;
 sctp_state_fn_t sctp_sf_ootb;
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 12f62174f4a1..a6a0ea71ae93 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -2608,6 +2608,51 @@ out:
         return disposition;
 }
 
+/*
+ * sctp_sf_do_9_2_shut_ctsn
+ *
+ * Once an endpoint has reached the SHUTDOWN-RECEIVED state,
+ * it MUST NOT send a SHUTDOWN in response to a ULP request.
+ * The Cumulative TSN Ack of the received SHUTDOWN chunk
+ * MUST be processed.
+ */
+sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(const struct sctp_endpoint *ep,
+                                           const struct sctp_association *asoc,
+                                           const sctp_subtype_t type,
+                                           void *arg,
+                                           sctp_cmd_seq_t *commands)
+{
+        struct sctp_chunk *chunk = arg;
+        sctp_shutdownhdr_t *sdh;
+
+        if (!sctp_vtag_verify(chunk, asoc))
+                return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
+
+        /* Make sure that the SHUTDOWN chunk has a valid length. */
+        if (!sctp_chunk_length_valid(chunk,
+                                      sizeof(struct sctp_shutdown_chunk_t)))
+                return sctp_sf_violation_chunklen(ep, asoc, type, arg,
+                                                  commands);
+
+        sdh = (sctp_shutdownhdr_t *)chunk->skb->data;
+
+        /* If Cumulative TSN Ack beyond the max tsn currently
+         * send, terminating the association and respond to the
+         * sender with an ABORT.
+         */
+        if (!TSN_lt(ntohl(sdh->cum_tsn_ack), asoc->next_tsn))
+                return sctp_sf_violation_ctsn(ep, asoc, type, arg, commands);
+
+        /* verify, by checking the Cumulative TSN Ack field of the
+         * chunk, that all its outstanding DATA chunks have been
+         * received by the SHUTDOWN sender.
+         */
+        sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
+                        SCTP_BE32(sdh->cum_tsn_ack));
+
+        return SCTP_DISPOSITION_CONSUME;
+}
+
 /* RFC 2960 9.2
  * If an endpoint is in SHUTDOWN-ACK-SENT state and receives an INIT chunk
  * (e.g., if the SHUTDOWN COMPLETE was lost) with source and destination
diff --git a/net/sctp/sm_statetable.c b/net/sctp/sm_statetable.c
index a5b5590dc1a6..5c8186d88c61 100644
--- a/net/sctp/sm_statetable.c
+++ b/net/sctp/sm_statetable.c
@@ -270,7 +270,7 @@ const sctp_sm_table_entry_t *sctp_sm_lookup_event(sctp_event_t event_type,
         /* SCTP_STATE_SHUTDOWN_SENT */ \
         TYPE_SCTP_FUNC(sctp_sf_do_9_2_shutdown_ack), \
         /* SCTP_STATE_SHUTDOWN_RECEIVED */ \
-        TYPE_SCTP_FUNC(sctp_sf_discard_chunk), \
+        TYPE_SCTP_FUNC(sctp_sf_do_9_2_shut_ctsn), \
         /* SCTP_STATE_SHUTDOWN_ACK_SENT */ \
         TYPE_SCTP_FUNC(sctp_sf_discard_chunk), \
 } /* TYPE_SCTP_SHUTDOWN */