SCTP: Limit association max_retrans setting in setsockopt.

When using ASSOCINFO socket option, we need to limit the number of
maximum association retransmissions to be no greater than the sum
of all the path retransmissions. This is specified in Section 7.1.2
of the SCTP socket API draft.
However, we only do this if the association has multiple paths. If
there is only one path, the protocol stack will use the
assoc_max_retrans setting when trying to retransmit packets.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 42a22355e027d87b9401d08984775d3fe19161cb..04707003ffaed2cf1137ea73eb35a6285857b46e 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2537,8 +2537,32 @@ static int sctp_setsockopt_associnfo(struct sock *sk, char __user *optval, int o
 
        /* Set the values to the specific association */
        if (asoc) {
-               if (assocparams.sasoc_asocmaxrxt != 0)
+               if (assocparams.sasoc_asocmaxrxt != 0) {
+                       __u32 path_sum = 0;
+                       int   paths = 0;
+                       struct list_head *pos;
+                       struct sctp_transport *peer_addr;
+
+                       list_for_each(pos, &asoc->peer.transport_addr_list) {
+                               peer_addr = list_entry(pos,
+                                               struct sctp_transport,
+                                               transports);
+                               path_sum += peer_addr->pathmaxrxt;
+                               paths++;
+                       }
+
+                       /* Only validate asocmaxrxt if we have more then
+                        * one path/transport.  We do this because path
+                        * retransmissions are only counted when we have more
+                        * then one path.
+                        */
+                       if (paths > 1 &&
+                           assocparams.sasoc_asocmaxrxt > path_sum)
+                               return -EINVAL;
+
                        asoc->max_retrans = assocparams.sasoc_asocmaxrxt;
+               }
+
                if (assocparams.sasoc_cookie_life != 0) {
                        asoc->cookie_life.tv_sec =
                                        assocparams.sasoc_cookie_life / 1000;