sctp: avoid overwrite the return value of sctp_process_asconf_ack()
[linux-2.6.git] / net / sctp / transport.c
index 268ddaf..e5dde45 100644 (file)
@@ -1,23 +1,23 @@
-/* SCTP kernel reference Implementation
+/* SCTP kernel implementation
  * Copyright (c) 1999-2000 Cisco, Inc.
  * Copyright (c) 1999-2001 Motorola, Inc.
  * Copyright (c) 2001-2003 International Business Machines Corp.
  * Copyright (c) 2001 Intel Corp.
  * Copyright (c) 2001 La Monte H.P. Yarroll
  *
- * This file is part of the SCTP kernel reference Implementation
+ * This file is part of the SCTP kernel implementation
  *
  * This module provides the abstraction for an SCTP tranport representing
  * a remote transport address.  For local transport addresses, we just use
  * union sctp_addr.
  *
- * The SCTP reference implementation is free software;
+ * This SCTP implementation is free software;
  * you can redistribute it and/or modify it under the terms of
  * the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
- * The SCTP reference implementation is distributed in the hope that it
+ * This SCTP implementation is distributed in the hope that it
  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  *                 ************************
  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
@@ -49,6 +49,7 @@
  */
 
 #include <linux/types.h>
+#include <linux/random.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
 
@@ -73,11 +74,13 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
         * given destination transport address, set RTO to the protocol
         * parameter 'RTO.Initial'.
         */
+       peer->last_rto = peer->rto = msecs_to_jiffies(sctp_rto_initial);
        peer->rtt = 0;
-       peer->rto = sctp_rto_initial;
        peer->rttvar = 0;
        peer->srtt = 0;
        peer->rto_pending = 0;
+       peer->hb_sent = 0;
+       peer->fast_recovery = 0;
 
        peer->last_time_heard = jiffies;
        peer->last_time_used = jiffies;
@@ -85,26 +88,29 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
 
        peer->init_sent_count = 0;
 
-       peer->state = SCTP_ACTIVE;
-       peer->hb_allowed = 0;
+       peer->param_flags = SPP_HB_DISABLE |
+                           SPP_PMTUD_ENABLE |
+                           SPP_SACKDELAY_ENABLE;
+       peer->hbinterval  = 0;
 
        /* Initialize the default path max_retrans.  */
-       peer->max_retrans = sctp_max_retrans_path;
+       peer->pathmaxrxt  = sctp_max_retrans_path;
        peer->error_count = 0;
 
        INIT_LIST_HEAD(&peer->transmitted);
        INIT_LIST_HEAD(&peer->send_ready);
        INIT_LIST_HEAD(&peer->transports);
 
-       /* Set up the retransmission timer.  */
-       init_timer(&peer->T3_rtx_timer);
-       peer->T3_rtx_timer.function = sctp_generate_t3_rtx_event;
-       peer->T3_rtx_timer.data = (unsigned long)peer;
+       peer->T3_rtx_timer.expires = 0;
+       peer->hb_timer.expires = 0;
 
-       /* Set up the heartbeat timer. */
-       init_timer(&peer->hb_timer);
-       peer->hb_timer.function = sctp_generate_heartbeat_event;
-       peer->hb_timer.data = (unsigned long)peer;
+       setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event,
+                       (unsigned long)peer);
+       setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event,
+                       (unsigned long)peer);
+
+       /* Initialize the 64-bit random nonce sent with heartbeat. */
+       get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));
 
        atomic_set(&peer->refcnt, 1);
        peer->dead = 0;
@@ -124,9 +130,9 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
 struct sctp_transport *sctp_transport_new(const union sctp_addr *addr,
                                          gfp_t gfp)
 {
-        struct sctp_transport *transport;
+       struct sctp_transport *transport;
 
-        transport = t_new(struct sctp_transport, gfp);
+       transport = t_new(struct sctp_transport, gfp);
        if (!transport)
                goto fail;
 
@@ -179,7 +185,7 @@ static void sctp_transport_destroy(struct sctp_transport *transport)
        if (transport->asoc)
                sctp_association_put(transport->asoc);
 
-        sctp_packet_free(&transport->packet);
+       sctp_packet_free(&transport->packet);
 
        dst_release(transport->dst);
        kfree(transport);
@@ -189,7 +195,7 @@ static void sctp_transport_destroy(struct sctp_transport *transport)
 /* Start T3_rtx timer if it is not already running and update the heartbeat
  * timer.  This routine is called every time a DATA chunk is sent.
  */
-void sctp_transport_reset_timers(struct sctp_transport *transport)
+void sctp_transport_reset_timers(struct sctp_transport *transport, int force)
 {
        /* RFC 2960 6.3.2 Retransmission Timer Rules
         *
@@ -199,7 +205,7 @@ void sctp_transport_reset_timers(struct sctp_transport *transport)
         * address.
         */
 
-       if (!timer_pending(&transport->T3_rtx_timer))
+       if (force || !timer_pending(&transport->T3_rtx_timer))
                if (!mod_timer(&transport->T3_rtx_timer,
                               jiffies + transport->rto))
                        sctp_transport_hold(transport);
@@ -229,10 +235,49 @@ void sctp_transport_pmtu(struct sctp_transport *transport)
        dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL);
 
        if (dst) {
-               transport->pmtu = dst_mtu(dst);
+               transport->pathmtu = dst_mtu(dst);
                dst_release(dst);
        } else
-               transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+               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;
+
+       if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
+               printk(KERN_WARNING "%s: Reported pmtu %d too low, "
+                      "using default minimum of %d\n",
+                      __func__, pmtu,
+                      SCTP_DEFAULT_MINSEGMENT);
+               /* Use default minimum segment size and disable
+                * pmtu discovery on this transport.
+                */
+               t->pathmtu = SCTP_DEFAULT_MINSEGMENT;
+       } else {
+               t->pathmtu = pmtu;
+       }
+
+       dst = sctp_transport_dst_check(t);
+       if (dst)
+               dst->ops->update_pmtu(dst, pmtu);
 }
 
 /* Caches the dst entry and source address for a transport's destination
@@ -251,20 +296,23 @@ void sctp_transport_route(struct sctp_transport *transport,
        if (saddr)
                memcpy(&transport->saddr, saddr, sizeof(union sctp_addr));
        else
-               af->get_saddr(asoc, dst, daddr, &transport->saddr);
+               af->get_saddr(opt, asoc, dst, daddr, &transport->saddr);
 
        transport->dst = dst;
+       if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) {
+               return;
+       }
        if (dst) {
-               transport->pmtu = dst_mtu(dst);
+               transport->pathmtu = dst_mtu(dst);
 
                /* Initialize sk->sk_rcv_saddr, if the transport is the
                 * association's active path for getsockname().
-                */ 
+                */
                if (asoc && (transport == asoc->peer.active_path))
                        opt->pf->af->to_sk_saddr(&transport->saddr,
                                                 asoc->base.sk);
        } else
-               transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+               transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
 }
 
 /* Hold a reference to a transport.  */
@@ -337,6 +385,7 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
                tp->rto = tp->asoc->rto_max;
 
        tp->rtt = rtt;
+       tp->last_rto = tp->rto;
 
        /* Reset rto_pending so that a new RTT measurement is started when a
         * new data chunk is sent.
@@ -344,7 +393,7 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
        tp->rto_pending = 0;
 
        SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d "
-                         "rttvar: %d, rto: %d\n", __FUNCTION__,
+                         "rttvar: %d, rto: %ld\n", __func__,
                          tp, rtt, tp->srtt, tp->rttvar, tp->rto);
 }
 
@@ -359,30 +408,41 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
        cwnd = transport->cwnd;
        flight_size = transport->flight_size;
 
+       /* See if we need to exit Fast Recovery first */
+       if (transport->fast_recovery &&
+           TSN_lte(transport->fast_recovery_exit, sack_ctsn))
+               transport->fast_recovery = 0;
+
        /* The appropriate cwnd increase algorithm is performed if, and only
-        * if the cumulative TSN has advanced and the congestion window is
+        * if the cumulative TSN whould advanced and the congestion window is
         * being fully utilized.
         */
-       if ((transport->asoc->ctsn_ack_point >= sack_ctsn) ||
+       if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) ||
            (flight_size < cwnd))
                return;
 
        ssthresh = transport->ssthresh;
        pba = transport->partial_bytes_acked;
-       pmtu = transport->asoc->pmtu;
+       pmtu = transport->asoc->pathmtu;
 
        if (cwnd <= ssthresh) {
-               /* RFC 2960 7.2.1, sctpimpguide-05 2.14.2 When cwnd is less
-                * than or equal to ssthresh an SCTP endpoint MUST use the
-                * slow start algorithm to increase cwnd only if the current
-                * congestion window is being fully utilized and an incoming
-                * SACK advances the Cumulative TSN Ack Point. Only when these
-                * two conditions are met can the cwnd be increased otherwise
-                * the cwnd MUST not be increased. If these conditions are met
-                * then cwnd MUST be increased by at most the lesser of
-                * 1) the total size of the previously outstanding DATA
-                * chunk(s) acknowledged, and 2) the destination's path MTU.
+               /* RFC 4960 7.2.1
+                * o  When cwnd is less than or equal to ssthresh, an SCTP
+                *    endpoint MUST use the slow-start algorithm to increase
+                *    cwnd only if the current congestion window is being fully
+                *    utilized, an incoming SACK advances the Cumulative TSN
+                *    Ack Point, and the data sender is not in Fast Recovery.
+                *    Only when these three conditions are met can the cwnd be
+                *    increased; otherwise, the cwnd MUST not be increased.
+                *    If these conditions are met, then cwnd MUST be increased
+                *    by, at most, the lesser of 1) the total size of the
+                *    previously outstanding DATA chunk(s) acknowledged, and
+                *    2) the destination's path MTU.  This upper bound protects
+                *    against the ACK-Splitting attack outlined in [SAVAGE99].
                 */
+               if (transport->fast_recovery)
+                       return;
+
                if (bytes_acked > pmtu)
                        cwnd += pmtu;
                else
@@ -390,7 +450,7 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
                SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, "
                                  "bytes_acked: %d, cwnd: %d, ssthresh: %d, "
                                  "flight_size: %d, pba: %d\n",
-                                 __FUNCTION__,
+                                 __func__,
                                  transport, bytes_acked, cwnd,
                                  ssthresh, flight_size, pba);
        } else {
@@ -416,7 +476,7 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
                SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: "
                                  "transport: %p, bytes_acked: %d, cwnd: %d, "
                                  "ssthresh: %d, flight_size: %d, pba: %d\n",
-                                 __FUNCTION__,
+                                 __func__,
                                  transport, bytes_acked, cwnd,
                                  ssthresh, flight_size, pba);
        }
@@ -441,8 +501,8 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
                 *      partial_bytes_acked = 0
                 */
                transport->ssthresh = max(transport->cwnd/2,
-                                         4*transport->asoc->pmtu);
-               transport->cwnd = transport->asoc->pmtu;
+                                         4*transport->asoc->pathmtu);
+               transport->cwnd = transport->asoc->pathmtu;
                break;
 
        case SCTP_LOWER_CWND_FAST_RTX:
@@ -450,16 +510,23 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
                 * destination address(es) to which the missing DATA chunks
                 * were last sent, according to the formula described in
                 * Section 7.2.3.
-                *
-                * RFC 2960 7.2.3, sctpimpguide Upon detection of packet
+                *
+                * RFC 2960 7.2.3, sctpimpguide Upon detection of packet
                 * losses from SACK (see Section 7.2.4), An endpoint
                 * should do the following:
                 *      ssthresh = max(cwnd/2, 4*MTU)
                 *      cwnd = ssthresh
                 *      partial_bytes_acked = 0
                 */
+               if (transport->fast_recovery)
+                       return;
+
+               /* Mark Fast recovery */
+               transport->fast_recovery = 1;
+               transport->fast_recovery_exit = transport->asoc->next_tsn - 1;
+
                transport->ssthresh = max(transport->cwnd/2,
-                                         4*transport->asoc->pmtu);
+                                         4*transport->asoc->pathmtu);
                transport->cwnd = transport->ssthresh;
                break;
 
@@ -476,10 +543,10 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
                 * congestion indications more than once every window of
                 * data (or more loosely more than once every round-trip time).
                 */
-               if ((jiffies - transport->last_time_ecne_reduced) >
-                   transport->rtt) {
+               if (time_after(jiffies, transport->last_time_ecne_reduced +
+                                       transport->rtt)) {
                        transport->ssthresh = max(transport->cwnd/2,
-                                                 4*transport->asoc->pmtu);
+                                                 4*transport->asoc->pathmtu);
                        transport->cwnd = transport->ssthresh;
                        transport->last_time_ecne_reduced = jiffies;
                }
@@ -494,15 +561,16 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
                 * to be done every RTO interval, we do it every hearbeat
                 * interval.
                 */
-               if ((jiffies - transport->last_time_used) > transport->rto)
+               if (time_after(jiffies, transport->last_time_used +
+                                       transport->rto))
                        transport->cwnd = max(transport->cwnd/2,
-                                                4*transport->asoc->pmtu);
+                                                4*transport->asoc->pathmtu);
                break;
-       };
+       }
 
        transport->partial_bytes_acked = 0;
        SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: "
-                         "%d ssthresh: %d\n", __FUNCTION__,
+                         "%d ssthresh: %d\n", __func__,
                          transport, reason,
                          transport->cwnd, transport->ssthresh);
 }
@@ -511,7 +579,43 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
 unsigned long sctp_transport_timeout(struct sctp_transport *t)
 {
        unsigned long timeout;
-       timeout = t->hb_interval + t->rto + sctp_jitter(t->rto);
+       timeout = t->rto + sctp_jitter(t->rto);
+       if (t->state != SCTP_UNCONFIRMED)
+               timeout += t->hbinterval;
        timeout += jiffies;
        return timeout;
 }
+
+/* Reset transport variables to their initial values */
+void sctp_transport_reset(struct sctp_transport *t)
+{
+       struct sctp_association *asoc = t->asoc;
+
+       /* RFC 2960 (bis), Section 5.2.4
+        * All the congestion control parameters (e.g., cwnd, ssthresh)
+        * related to this peer MUST be reset to their initial values
+        * (see Section 6.2.1)
+        */
+       t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
+       t->ssthresh = asoc->peer.i.a_rwnd;
+       t->last_rto = t->rto = asoc->rto_initial;
+       t->rtt = 0;
+       t->srtt = 0;
+       t->rttvar = 0;
+
+       /* Reset these additional varibles so that we have a clean
+        * slate.
+        */
+       t->partial_bytes_acked = 0;
+       t->flight_size = 0;
+       t->error_count = 0;
+       t->rto_pending = 0;
+       t->hb_sent = 0;
+       t->fast_recovery = 0;
+
+       /* Initialize the state information for SFR-CACC */
+       t->cacc.changeover_active = 0;
+       t->cacc.cycling_changeover = 0;
+       t->cacc.next_tsn_at_change = 0;
+       t->cacc.cacc_saw_newack = 0;
+}