sctp: Fix SCTP_MAXSEG socket option to comply to spec.

We had a bug that we never stored the user-defined value for
MAXSEG when setting the value on an association.  Thus future
PMTU events ended up re-writing the frag point and increasing
it past user limit.  Additionally, when setting the option on
the socket/endpoint, we effect all current associations, which
is against spec.

Now, we store the user 'maxseg' value along with the computed
'frag_point'.  We inherit 'maxseg' from the socket at association
creation and use it as an upper limit for 'frag_point' when its
set.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 39c3821b7d3d..1f05b942564e 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -112,6 +112,7 @@ static struct sctp_association *sctp_association_init(struct sctp_association *a
         asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
                                         * 1000;
         asoc->frag_point = 0;
+        asoc->user_frag = sp->user_frag;
 
         /* Set the association max_retrans and RTO values from the
          * socket values.
@@ -674,7 +675,7 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
                           "%d\n", asoc, asoc->pathmtu);
         peer->pmtu_pending = 0;
 
-        asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);
+        asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
 
         /* The asoc->peer.port might not be meaningful yet, but
          * initialize the packet structure anyway.
@@ -1330,9 +1331,8 @@ void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
         }
 
         if (pmtu) {
-                struct sctp_sock *sp = sctp_sk(asoc->base.sk);
                 asoc->pathmtu = pmtu;
-                asoc->frag_point = sctp_frag_point(sp, pmtu);
+                asoc->frag_point = sctp_frag_point(asoc, pmtu);
         }
 
         SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",