1 files changed, 328 insertions, 139 deletions

diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index bdbbc3fd7c14..0c56d9673cc1 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /* SCTP kernel implementation
  * Copyright (c) 1999-2000 Cisco, Inc.
  * Copyright (c) 1999-2001 Motorola, Inc.
@@ -7,33 +8,13 @@
  *
  * This file is part of the SCTP kernel implementation
  *
- * This module provides the abstraction for an SCTP tranport representing
+ * This module provides the abstraction for an SCTP transport representing
  * a remote transport address.  For local transport addresses, we just use
  * union sctp_addr.
  *
- * 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.
- *
- * 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.
- * See the GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GNU CC; see the file COPYING.  If not, write to
- * the Free Software Foundation, 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- *
  * Please send any bug reports or fixes you make to the
  * email address(es):
- *    lksctp developers <lksctp-developers@lists.sourceforge.net>
- *
- * Or submit a bug report through the following website:
- *    http://www.sf.net/projects/lksctp
+ *    lksctp developers <linux-sctp@vger.kernel.org>
  *
  * Written or modified by:
  *    La Monte H.P. Yarroll <piggy@acm.org>
@@ -43,9 +24,6 @@
  *    Hui Huang             <hui.huang@nokia.com>
  *    Sridhar Samudrala	    <sri@us.ibm.com>
  *    Ardelle Fan	    <ardelle.fan@intel.com>
- *
- * Any bugs reported given to us we will try to fix... any fixes shared will
- * be incorporated into the next SCTP release.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -59,14 +37,14 @@
 /* 1st Level Abstractions.  */
 
 /* Initialize a new transport from provided memory.  */
-static struct sctp_transport *sctp_transport_init(struct net *net,
-						  struct sctp_transport *peer,
-						  const union sctp_addr *addr,
-						  gfp_t gfp)
+static void sctp_transport_init(struct net *net,
+				struct sctp_transport *peer,
+				const union sctp_addr *addr,
+				gfp_t gfp)
 {
 	/* Copy in the address.  */
-	peer->ipaddr = *addr;
 	peer->af_specific = sctp_get_af_specific(addr->sa.sa_family);
+	memcpy(&peer->ipaddr, addr, peer->af_specific->sockaddr_len);
 	memset(&peer->saddr, 0, sizeof(union sctp_addr));
 
 	peer->sack_generation = 0;
@@ -79,7 +57,7 @@ static struct sctp_transport *sctp_transport_init(struct net *net,
 	 */
 	peer->rto = msecs_to_jiffies(net->sctp.rto_initial);
 
-	peer->last_time_heard = jiffies;
+	peer->last_time_heard = 0;
 	peer->last_time_ecne_reduced = jiffies;
 
 	peer->param_flags = SPP_HB_DISABLE |
@@ -94,19 +72,17 @@ static struct sctp_transport *sctp_transport_init(struct net *net,
 	INIT_LIST_HEAD(&peer->send_ready);
 	INIT_LIST_HEAD(&peer->transports);
 
-	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);
-	setup_timer(&peer->proto_unreach_timer,
-		    sctp_generate_proto_unreach_event, (unsigned long)peer);
+	timer_setup(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, 0);
+	timer_setup(&peer->hb_timer, sctp_generate_heartbeat_event, 0);
+	timer_setup(&peer->reconf_timer, sctp_generate_reconf_event, 0);
+	timer_setup(&peer->probe_timer, sctp_generate_probe_event, 0);
+	timer_setup(&peer->proto_unreach_timer,
+		    sctp_generate_proto_unreach_event, 0);
 
 	/* Initialize the 64-bit random nonce sent with heartbeat. */
 	get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));
 
-	atomic_set(&peer->refcnt, 1);
-
-	return peer;
+	refcount_set(&peer->refcnt, 1);
 }
 
 /* Allocate and initialize a new transport.  */
@@ -118,20 +94,13 @@ struct sctp_transport *sctp_transport_new(struct net *net,
 
 	transport = kzalloc(sizeof(*transport), gfp);
 	if (!transport)
-		goto fail;
+		return NULL;
 
-	if (!sctp_transport_init(net, transport, addr, gfp))
-		goto fail_init;
+	sctp_transport_init(net, transport, addr, gfp);
 
 	SCTP_DBG_OBJCNT_INC(transport);
 
 	return transport;
-
-fail_init:
-	kfree(transport);
-
-fail:
-	return NULL;
 }
 
 /* This transport is no longer needed.  Free up if possible, or
@@ -142,20 +111,26 @@ void sctp_transport_free(struct sctp_transport *transport)
 	transport->dead = 1;
 
 	/* Try to delete the heartbeat timer.  */
-	if (del_timer(&transport->hb_timer))
+	if (timer_delete(&transport->hb_timer))
 		sctp_transport_put(transport);
 
 	/* Delete the T3_rtx timer if it's active.
 	 * There is no point in not doing this now and letting
 	 * structure hang around in memory since we know
-	 * the tranport is going away.
+	 * the transport is going away.
 	 */
-	if (del_timer(&transport->T3_rtx_timer))
+	if (timer_delete(&transport->T3_rtx_timer))
+		sctp_transport_put(transport);
+
+	if (timer_delete(&transport->reconf_timer))
+		sctp_transport_put(transport);
+
+	if (timer_delete(&transport->probe_timer))
 		sctp_transport_put(transport);
 
 	/* Delete the ICMP proto unreachable timer if it's active. */
-	if (del_timer(&transport->proto_unreach_timer))
-		sctp_association_put(transport->asoc);
+	if (timer_delete(&transport->proto_unreach_timer))
+		sctp_transport_put(transport);
 
 	sctp_transport_put(transport);
 }
@@ -176,23 +151,23 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
  */
 static void sctp_transport_destroy(struct sctp_transport *transport)
 {
-	if (unlikely(!transport->dead)) {
+	if (unlikely(refcount_read(&transport->refcnt))) {
 		WARN(1, "Attempt to destroy undead transport %p!\n", transport);
 		return;
 	}
 
-	call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
-
 	sctp_packet_free(&transport->packet);
 
 	if (transport->asoc)
 		sctp_association_put(transport->asoc);
+
+	call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
 }
 
 /* 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_t3_rtx(struct sctp_transport *transport)
 {
 	/* RFC 2960 6.3.2 Retransmission Timer Rules
 	 *
@@ -206,11 +181,39 @@ void sctp_transport_reset_timers(struct sctp_transport *transport)
 		if (!mod_timer(&transport->T3_rtx_timer,
 			       jiffies + transport->rto))
 			sctp_transport_hold(transport);
+}
+
+void sctp_transport_reset_hb_timer(struct sctp_transport *transport)
+{
+	unsigned long expires;
 
 	/* When a data chunk is sent, reset the heartbeat interval.  */
+	expires = jiffies + sctp_transport_timeout(transport);
 	if (!mod_timer(&transport->hb_timer,
-		       sctp_transport_timeout(transport)))
-	    sctp_transport_hold(transport);
+		       expires + get_random_u32_below(transport->rto)))
+		sctp_transport_hold(transport);
+}
+
+void sctp_transport_reset_reconf_timer(struct sctp_transport *transport)
+{
+	if (!timer_pending(&transport->reconf_timer))
+		if (!mod_timer(&transport->reconf_timer,
+			       jiffies + transport->rto))
+			sctp_transport_hold(transport);
+}
+
+void sctp_transport_reset_probe_timer(struct sctp_transport *transport)
+{
+	if (!mod_timer(&transport->probe_timer,
+		       jiffies + transport->probe_interval))
+		sctp_transport_hold(transport);
+}
+
+void sctp_transport_reset_raise_timer(struct sctp_transport *transport)
+{
+	if (!mod_timer(&transport->probe_timer,
+		       jiffies + transport->probe_interval * 30))
+		sctp_transport_hold(transport);
 }
 
 /* This transport has been assigned to an association.
@@ -228,45 +231,208 @@ void sctp_transport_set_owner(struct sctp_transport *transport,
 void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk)
 {
 	/* If we don't have a fresh route, look one up */
-	if (!transport->dst || transport->dst->obsolete) {
-		dst_release(transport->dst);
+	if (!transport->dst || READ_ONCE(transport->dst->obsolete)) {
+		sctp_transport_dst_release(transport);
 		transport->af_specific->get_dst(transport, &transport->saddr,
 						&transport->fl, sk);
 	}
 
-	if (transport->dst) {
-		transport->pathmtu = dst_mtu(transport->dst);
-	} else
+	if (transport->param_flags & SPP_PMTUD_DISABLE) {
+		struct sctp_association *asoc = transport->asoc;
+
+		if (!transport->pathmtu && asoc && asoc->pathmtu)
+			transport->pathmtu = asoc->pathmtu;
+		if (transport->pathmtu)
+			return;
+	}
+
+	if (transport->dst)
+		transport->pathmtu = sctp_dst_mtu(transport->dst);
+	else
 		transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
+
+	sctp_transport_pl_update(transport);
 }
 
-void sctp_transport_update_pmtu(struct sock *sk, struct sctp_transport *t, u32 pmtu)
+void sctp_transport_pl_send(struct sctp_transport *t)
 {
+	if (t->pl.probe_count < SCTP_MAX_PROBES)
+		goto out;
+
+	t->pl.probe_count = 0;
+	if (t->pl.state == SCTP_PL_BASE) {
+		if (t->pl.probe_size == SCTP_BASE_PLPMTU) { /* BASE_PLPMTU Confirmation Failed */
+			t->pl.state = SCTP_PL_ERROR; /* Base -> Error */
+
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			sctp_assoc_sync_pmtu(t->asoc);
+		}
+	} else if (t->pl.state == SCTP_PL_SEARCH) {
+		if (t->pl.pmtu == t->pl.probe_size) { /* Black Hole Detected */
+			t->pl.state = SCTP_PL_BASE;  /* Search -> Base */
+			t->pl.probe_size = SCTP_BASE_PLPMTU;
+			t->pl.probe_high = 0;
+
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			sctp_assoc_sync_pmtu(t->asoc);
+		} else { /* Normal probe failure. */
+			t->pl.probe_high = t->pl.probe_size;
+			t->pl.probe_size = t->pl.pmtu;
+		}
+	} else if (t->pl.state == SCTP_PL_COMPLETE) {
+		if (t->pl.pmtu == t->pl.probe_size) { /* Black Hole Detected */
+			t->pl.state = SCTP_PL_BASE;  /* Search Complete -> Base */
+			t->pl.probe_size = SCTP_BASE_PLPMTU;
+
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			sctp_assoc_sync_pmtu(t->asoc);
+		}
+	}
+
+out:
+	pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, high: %d\n",
+		 __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, t->pl.probe_high);
+	t->pl.probe_count++;
+}
+
+bool sctp_transport_pl_recv(struct sctp_transport *t)
+{
+	pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, high: %d\n",
+		 __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, t->pl.probe_high);
+
+	t->pl.pmtu = t->pl.probe_size;
+	t->pl.probe_count = 0;
+	if (t->pl.state == SCTP_PL_BASE) {
+		t->pl.state = SCTP_PL_SEARCH; /* Base -> Search */
+		t->pl.probe_size += SCTP_PL_BIG_STEP;
+	} else if (t->pl.state == SCTP_PL_ERROR) {
+		t->pl.state = SCTP_PL_SEARCH; /* Error -> Search */
+
+		t->pl.pmtu = t->pl.probe_size;
+		t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+		sctp_assoc_sync_pmtu(t->asoc);
+		t->pl.probe_size += SCTP_PL_BIG_STEP;
+	} else if (t->pl.state == SCTP_PL_SEARCH) {
+		if (!t->pl.probe_high) {
+			if (t->pl.probe_size < SCTP_MAX_PLPMTU) {
+				t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP,
+						       SCTP_MAX_PLPMTU);
+				return false;
+			}
+			t->pl.probe_high = SCTP_MAX_PLPMTU;
+		}
+		t->pl.probe_size += SCTP_PL_MIN_STEP;
+		if (t->pl.probe_size >= t->pl.probe_high) {
+			t->pl.probe_high = 0;
+			t->pl.state = SCTP_PL_COMPLETE; /* Search -> Search Complete */
+
+			t->pl.probe_size = t->pl.pmtu;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			sctp_assoc_sync_pmtu(t->asoc);
+			sctp_transport_reset_raise_timer(t);
+		}
+	} else if (t->pl.state == SCTP_PL_COMPLETE) {
+		/* Raise probe_size again after 30 * interval in Search Complete */
+		t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */
+		t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_MIN_STEP, SCTP_MAX_PLPMTU);
+	}
+
+	return t->pl.state == SCTP_PL_COMPLETE;
+}
+
+static bool sctp_transport_pl_toobig(struct sctp_transport *t, u32 pmtu)
+{
+	pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, ptb: %d\n",
+		 __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, pmtu);
+
+	if (pmtu < SCTP_MIN_PLPMTU || pmtu >= t->pl.probe_size)
+		return false;
+
+	if (t->pl.state == SCTP_PL_BASE) {
+		if (pmtu >= SCTP_MIN_PLPMTU && pmtu < SCTP_BASE_PLPMTU) {
+			t->pl.state = SCTP_PL_ERROR; /* Base -> Error */
+
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			return true;
+		}
+	} else if (t->pl.state == SCTP_PL_SEARCH) {
+		if (pmtu >= SCTP_BASE_PLPMTU && pmtu < t->pl.pmtu) {
+			t->pl.state = SCTP_PL_BASE;  /* Search -> Base */
+			t->pl.probe_size = SCTP_BASE_PLPMTU;
+			t->pl.probe_count = 0;
+
+			t->pl.probe_high = 0;
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			return true;
+		} else if (pmtu > t->pl.pmtu && pmtu < t->pl.probe_size) {
+			t->pl.probe_size = pmtu;
+			t->pl.probe_count = 0;
+		}
+	} else if (t->pl.state == SCTP_PL_COMPLETE) {
+		if (pmtu >= SCTP_BASE_PLPMTU && pmtu < t->pl.pmtu) {
+			t->pl.state = SCTP_PL_BASE;  /* Complete -> Base */
+			t->pl.probe_size = SCTP_BASE_PLPMTU;
+			t->pl.probe_count = 0;
+
+			t->pl.probe_high = 0;
+			t->pl.pmtu = SCTP_BASE_PLPMTU;
+			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			sctp_transport_reset_probe_timer(t);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
+{
+	struct sock *sk = t->asoc->base.sk;
 	struct dst_entry *dst;
+	bool change = true;
 
 	if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
-		pr_warn("%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;
+		pr_warn_ratelimited("%s: Reported pmtu %d too low, using default minimum of %d\n",
+				    __func__, pmtu, SCTP_DEFAULT_MINSEGMENT);
+		/* Use default minimum segment instead */
+		pmtu = SCTP_DEFAULT_MINSEGMENT;
 	}
+	pmtu = SCTP_TRUNC4(pmtu);
 
-	dst = sctp_transport_dst_check(t);
-	if (!dst)
-		t->af_specific->get_dst(t, &t->saddr, &t->fl, sk);
+	if (sctp_transport_pl_enabled(t))
+		return sctp_transport_pl_toobig(t, pmtu - sctp_transport_pl_hlen(t));
 
+	dst = sctp_transport_dst_check(t);
 	if (dst) {
-		dst->ops->update_pmtu(dst, sk, NULL, pmtu);
+		struct sctp_pf *pf = sctp_get_pf_specific(dst->ops->family);
+		union sctp_addr addr;
+
+		pf->af->from_sk(&addr, sk);
+		pf->to_sk_daddr(&t->ipaddr, sk);
+		dst->ops->update_pmtu(dst, sk, NULL, pmtu, true);
+		pf->to_sk_daddr(&addr, sk);
 
 		dst = sctp_transport_dst_check(t);
-		if (!dst)
-			t->af_specific->get_dst(t, &t->saddr, &t->fl, sk);
 	}
+
+	if (!dst) {
+		t->af_specific->get_dst(t, &t->saddr, &t->fl, sk);
+		dst = t->dst;
+	}
+
+	if (dst) {
+		/* Re-fetch, as under layers may have a higher minimum size */
+		pmtu = sctp_dst_mtu(dst);
+		change = t->pathmtu != pmtu;
+	}
+	t->pathmtu = pmtu;
+
+	return change;
 }
 
 /* Caches the dst entry and source address for a transport's destination
@@ -278,6 +444,7 @@ void sctp_transport_route(struct sctp_transport *transport,
 	struct sctp_association *asoc = transport->asoc;
 	struct sctp_af *af = transport->af_specific;
 
+	sctp_transport_dst_release(transport);
 	af->get_dst(transport, saddr, &transport->fl, sctp_opt2sk(opt));
 
 	if (saddr)
@@ -285,27 +452,20 @@ void sctp_transport_route(struct sctp_transport *transport,
 	else
 		af->get_saddr(opt, transport, &transport->fl);
 
-	if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) {
-		return;
-	}
-	if (transport->dst) {
-		transport->pathmtu = dst_mtu(transport->dst);
+	sctp_transport_pmtu(transport, sctp_opt2sk(opt));
 
-		/* Initialize sk->sk_rcv_saddr, if the transport is the
-		 * association's active path for getsockname().
-		 */
-		if (asoc && (!asoc->peer.primary_path ||
-				(transport == asoc->peer.active_path)))
-			opt->pf->af->to_sk_saddr(&transport->saddr,
-						 asoc->base.sk);
-	} else
-		transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
+	/* Initialize sk->sk_rcv_saddr, if the transport is the
+	 * association's active path for getsockname().
+	 */
+	if (transport->dst && asoc &&
+	    (!asoc->peer.primary_path || transport == asoc->peer.active_path))
+		opt->pf->to_sk_saddr(&transport->saddr, asoc->base.sk);
 }
 
 /* Hold a reference to a transport.  */
-void sctp_transport_hold(struct sctp_transport *transport)
+int sctp_transport_hold(struct sctp_transport *transport)
 {
-	atomic_inc(&transport->refcnt);
+	return refcount_inc_not_zero(&transport->refcnt);
 }
 
 /* Release a reference to a transport and clean up
@@ -313,7 +473,7 @@ void sctp_transport_hold(struct sctp_transport *transport)
  */
 void sctp_transport_put(struct sctp_transport *transport)
 {
-	if (atomic_dec_and_test(&transport->refcnt))
+	if (refcount_dec_and_test(&transport->refcnt))
 		sctp_transport_destroy(transport);
 }
 
@@ -325,7 +485,8 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
 		pr_debug("%s: rto_pending not set on transport %p!\n", __func__, tp);
 
 	if (tp->rttvar || tp->srtt) {
-		struct net *net = sock_net(tp->asoc->base.sk);
+		struct net *net = tp->asoc->base.net;
+		unsigned int rto_beta, rto_alpha;
 		/* 6.3.1 C3) When a new RTT measurement R' is made, set
 		 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
 		 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
@@ -337,10 +498,14 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
 		 * For example, assuming the default value of RTO.Alpha of
 		 * 1/8, rto_alpha would be expressed as 3.
 		 */
-		tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta)
-			+ (((__u32)abs64((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta);
-		tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha)
-			+ (rtt >> net->sctp.rto_alpha);
+		rto_beta = READ_ONCE(net->sctp.rto_beta);
+		if (rto_beta < 32)
+			tp->rttvar = tp->rttvar - (tp->rttvar >> rto_beta)
+				+ (((__u32)abs((__s64)tp->srtt - (__s64)rtt)) >> rto_beta);
+		rto_alpha = READ_ONCE(net->sctp.rto_alpha);
+		if (rto_alpha < 32)
+			tp->srtt = tp->srtt - (tp->srtt >> rto_alpha)
+				+ (rtt >> rto_alpha);
 	} else {
 		/* 6.3.1 C2) When the first RTT measurement R is made, set
 		 * SRTT <- R, RTTVAR <- R/2.
@@ -399,14 +564,6 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
 	    TSN_lte(asoc->fast_recovery_exit, sack_ctsn))
 		asoc->fast_recovery = 0;
 
-	/* The appropriate cwnd increase algorithm is performed if, and only
-	 * if the cumulative TSN whould advanced and the congestion window is
-	 * being fully utilized.
-	 */
-	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->pathmtu;
@@ -429,6 +586,14 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
 		if (asoc->fast_recovery)
 			return;
 
+		/* The appropriate cwnd increase algorithm is performed
+		 * if, and only if the congestion window is being fully
+		 * utilized.  Note that RFC4960 Errata 3.22 removed the
+		 * other condition on ctsn moving.
+		 */
+		if (flight_size < cwnd)
+			return;
+
 		if (bytes_acked > pmtu)
 			cwnd += pmtu;
 		else
@@ -440,23 +605,33 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
 			 flight_size, pba);
 	} else {
 		/* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh,
-		 * upon each SACK arrival that advances the Cumulative TSN Ack
-		 * Point, increase partial_bytes_acked by the total number of
-		 * bytes of all new chunks acknowledged in that SACK including
-		 * chunks acknowledged by the new Cumulative TSN Ack and by
-		 * Gap Ack Blocks.
+		 * upon each SACK arrival, increase partial_bytes_acked
+		 * by the total number of bytes of all new chunks
+		 * acknowledged in that SACK including chunks
+		 * acknowledged by the new Cumulative TSN Ack and by Gap
+		 * Ack Blocks. (updated by RFC4960 Errata 3.22)
+		 *
+		 * When partial_bytes_acked is greater than cwnd and
+		 * before the arrival of the SACK the sender had less
+		 * bytes of data outstanding than cwnd (i.e., before
+		 * arrival of the SACK, flightsize was less than cwnd),
+		 * reset partial_bytes_acked to cwnd. (RFC 4960 Errata
+		 * 3.26)
 		 *
-		 * When partial_bytes_acked is equal to or greater than cwnd
-		 * and before the arrival of the SACK the sender had cwnd or
-		 * more bytes of data outstanding (i.e., before arrival of the
-		 * SACK, flightsize was greater than or equal to cwnd),
-		 * increase cwnd by MTU, and reset partial_bytes_acked to
-		 * (partial_bytes_acked - cwnd).
+		 * When partial_bytes_acked is equal to or greater than
+		 * cwnd and before the arrival of the SACK the sender
+		 * had cwnd or more bytes of data outstanding (i.e.,
+		 * before arrival of the SACK, flightsize was greater
+		 * than or equal to cwnd), partial_bytes_acked is reset
+		 * to (partial_bytes_acked - cwnd). Next, cwnd is
+		 * increased by MTU. (RFC 4960 Errata 3.12)
 		 */
 		pba += bytes_acked;
-		if (pba >= cwnd) {
+		if (pba > cwnd && flight_size < cwnd)
+			pba = cwnd;
+		if (pba >= cwnd && flight_size >= cwnd) {
+			pba = pba - cwnd;
 			cwnd += pmtu;
-			pba = ((cwnd < pba) ? (pba - cwnd) : 0);
 		}
 
 		pr_debug("%s: congestion avoidance: transport:%p, "
@@ -474,7 +649,7 @@ void sctp_transport_raise_cwnd(struct sctp_transport *transport,
  * detected.
  */
 void sctp_transport_lower_cwnd(struct sctp_transport *transport,
-			       sctp_lower_cwnd_t reason)
+			       enum sctp_lower_cwnd reason)
 {
 	struct sctp_association *asoc = transport->asoc;
 
@@ -553,6 +728,8 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport,
 		 */
 		transport->cwnd = max(transport->cwnd/2,
 					 4*asoc->pathmtu);
+		/* RFC 4960 Errata 3.27.2: also adjust sshthresh */
+		transport->ssthresh = transport->cwnd;
 		break;
 	}
 
@@ -579,7 +756,7 @@ void sctp_transport_burst_limited(struct sctp_transport *t)
 	u32 old_cwnd = t->cwnd;
 	u32 max_burst_bytes;
 
-	if (t->burst_limited)
+	if (t->burst_limited || asoc->max_burst == 0)
 		return;
 
 	max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu);
@@ -601,15 +778,16 @@ void sctp_transport_burst_reset(struct sctp_transport *t)
 }
 
 /* What is the next timeout value for this transport? */
-unsigned long sctp_transport_timeout(struct sctp_transport *t)
+unsigned long sctp_transport_timeout(struct sctp_transport *trans)
 {
-	unsigned long timeout;
-	timeout = t->rto + sctp_jitter(t->rto);
-	if ((t->state != SCTP_UNCONFIRMED) &&
-	    (t->state != SCTP_PF))
-		timeout += t->hbinterval;
-	timeout += jiffies;
-	return timeout;
+	/* RTO + timer slack +/- 50% of RTO */
+	unsigned long timeout = trans->rto >> 1;
+
+	if (trans->state != SCTP_UNCONFIRMED &&
+	    trans->state != SCTP_PF)
+		timeout += trans->hbinterval;
+
+	return max_t(unsigned long, timeout, HZ / 5);
 }
 
 /* Reset transport variables to their initial values */
@@ -631,9 +809,7 @@ void sctp_transport_reset(struct sctp_transport *t)
 	t->srtt = 0;
 	t->rttvar = 0;
 
-	/* Reset these additional varibles so that we have a clean
-	 * slate.
-	 */
+	/* Reset these additional variables so that we have a clean slate. */
 	t->partial_bytes_acked = 0;
 	t->flight_size = 0;
 	t->error_count = 0;
@@ -651,7 +827,7 @@ void sctp_transport_reset(struct sctp_transport *t)
 void sctp_transport_immediate_rtx(struct sctp_transport *t)
 {
 	/* Stop pending T3_rtx_timer */
-	if (del_timer(&t->T3_rtx_timer))
+	if (timer_delete(&t->T3_rtx_timer))
 		sctp_transport_put(t);
 
 	sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX);
@@ -659,5 +835,18 @@ void sctp_transport_immediate_rtx(struct sctp_transport *t)
 		if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto))
 			sctp_transport_hold(t);
 	}
-	return;
+}
+
+/* Drop dst */
+void sctp_transport_dst_release(struct sctp_transport *t)
+{
+	dst_release(t->dst);
+	t->dst = NULL;
+	t->dst_pending_confirm = 0;
+}
+
+/* Schedule neighbour confirm */
+void sctp_transport_dst_confirm(struct sctp_transport *t)
+{
+	t->dst_pending_confirm = 1;
 }