sctp: check cached dst before using it

dst_check() will take care of SA (and obsolete field), hence
IPsec rekeying scenario is taken into account.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Vlad Yaseivch <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 14 insertions, 20 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 6ee44b24864a..a2ef81466b00 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -704,4 +704,17 @@ static inline void sctp_v4_map_v6(union sctp_addr *addr)
         addr->v6.sin6_addr.s6_addr32[2] = htonl(0x0000ffff);
 }
 
+/* The cookie is always 0 since this is how it's used in the
+ * pmtu code.
+ */
+static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
+{
+        if (t->dst && !dst_check(t->dst, 0)) {
+                dst_release(t->dst);
+                t->dst = NULL;
+        }
+
+        return t->dst;
+}
+
 #endif /* __net_sctp_h__ */
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 817174eb5f41..8fc4dcd294ab 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -377,9 +377,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
          */
         skb_set_owner_w(nskb, sk);
 
-        /* The 'obsolete' field of dst is set to 2 when a dst is freed. */
-        if (!dst || (dst->obsolete > 1)) {
-                dst_release(dst);
+        if (!sctp_transport_dst_check(tp)) {
                 sctp_transport_route(tp, NULL, sctp_sk(sk));
                 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) {
                         sctp_assoc_sync_pmtu(asoc);
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 3889330b7b04..b026ba0c6992 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -226,23 +226,6 @@ void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk)
                 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
 }
 
-/* this is a complete rip-off from __sk_dst_check
- * the cookie is always 0 since this is how it's used in the
- * pmtu code
- */
-static struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
-{
-        struct dst_entry *dst = t->dst;
-
-        if (dst && dst->obsolete && dst->ops->check(dst, 0) == NULL) {
-                dst_release(t->dst);
-                t->dst = NULL;
-                return NULL;
-        }
-
-        return dst;
-}
-
 void sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
 {
         struct dst_entry *dst;