| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* 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 implementation |
| * |
| * This module provides the abstraction for an SCTP transport representing |
| * a remote transport address. For local transport addresses, we just use |
| * union sctp_addr. |
| * |
| * Please send any bug reports or fixes you make to the |
| * email address(es): |
| * lksctp developers <linux-sctp@vger.kernel.org> |
| * |
| * Written or modified by: |
| * La Monte H.P. Yarroll <piggy@acm.org> |
| * Karl Knutson <karl@athena.chicago.il.us> |
| * Jon Grimm <jgrimm@us.ibm.com> |
| * Xingang Guo <xingang.guo@intel.com> |
| * Hui Huang <hui.huang@nokia.com> |
| * Sridhar Samudrala <sri@us.ibm.com> |
| * Ardelle Fan <ardelle.fan@intel.com> |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/slab.h> |
| #include <linux/types.h> |
| #include <linux/random.h> |
| #include <net/sctp/sctp.h> |
| #include <net/sctp/sm.h> |
| |
| /* 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) |
| { |
| /* Copy in the address. */ |
| 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; |
| |
| /* From 6.3.1 RTO Calculation: |
| * |
| * C1) Until an RTT measurement has been made for a packet sent to the |
| * given destination transport address, set RTO to the protocol |
| * parameter 'RTO.Initial'. |
| */ |
| peer->rto = msecs_to_jiffies(net->sctp.rto_initial); |
| |
| peer->last_time_heard = 0; |
| peer->last_time_ecne_reduced = jiffies; |
| |
| peer->param_flags = SPP_HB_DISABLE | |
| SPP_PMTUD_ENABLE | |
| SPP_SACKDELAY_ENABLE; |
| |
| /* Initialize the default path max_retrans. */ |
| peer->pathmaxrxt = net->sctp.max_retrans_path; |
| peer->pf_retrans = net->sctp.pf_retrans; |
| |
| INIT_LIST_HEAD(&peer->transmitted); |
| INIT_LIST_HEAD(&peer->send_ready); |
| INIT_LIST_HEAD(&peer->transports); |
| |
| 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)); |
| |
| refcount_set(&peer->refcnt, 1); |
| |
| return peer; |
| } |
| |
| /* Allocate and initialize a new transport. */ |
| struct sctp_transport *sctp_transport_new(struct net *net, |
| const union sctp_addr *addr, |
| gfp_t gfp) |
| { |
| struct sctp_transport *transport; |
| |
| transport = kzalloc(sizeof(*transport), gfp); |
| if (!transport) |
| goto fail; |
| |
| if (!sctp_transport_init(net, transport, addr, gfp)) |
| goto fail_init; |
| |
| 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 |
| * delay until it last reference count. |
| */ |
| void sctp_transport_free(struct sctp_transport *transport) |
| { |
| /* Try to delete the heartbeat timer. */ |
| if (del_timer(&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 transport is going away. |
| */ |
| if (del_timer(&transport->T3_rtx_timer)) |
| sctp_transport_put(transport); |
| |
| if (del_timer(&transport->reconf_timer)) |
| sctp_transport_put(transport); |
| |
| if (del_timer(&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_transport_put(transport); |
| |
| sctp_transport_put(transport); |
| } |
| |
| static void sctp_transport_destroy_rcu(struct rcu_head *head) |
| { |
| struct sctp_transport *transport; |
| |
| transport = container_of(head, struct sctp_transport, rcu); |
| |
| dst_release(transport->dst); |
| kfree(transport); |
| SCTP_DBG_OBJCNT_DEC(transport); |
| } |
| |
| /* Destroy the transport data structure. |
| * Assumes there are no more users of this structure. |
| */ |
| static void sctp_transport_destroy(struct sctp_transport *transport) |
| { |
| if (unlikely(refcount_read(&transport->refcnt))) { |
| WARN(1, "Attempt to destroy undead transport %p!\n", transport); |
| return; |
| } |
| |
| 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_t3_rtx(struct sctp_transport *transport) |
| { |
| /* RFC 2960 6.3.2 Retransmission Timer Rules |
| * |
| * R1) Every time a DATA chunk is sent to any address(including a |
| * retransmission), if the T3-rtx timer of that address is not running |
| * start it running so that it will expire after the RTO of that |
| * address. |
| */ |
| |
| if (!timer_pending(&transport->T3_rtx_timer)) |
| 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 ((time_before(transport->hb_timer.expires, expires) || |
| !timer_pending(&transport->hb_timer)) && |
| !mod_timer(&transport->hb_timer, |
| expires + prandom_u32_max(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 (timer_pending(&transport->probe_timer)) |
| return; |
| if (!mod_timer(&transport->probe_timer, |
| jiffies + transport->probe_interval)) |
| sctp_transport_hold(transport); |
| } |
| |
| /* This transport has been assigned to an association. |
| * Initialize fields from the association or from the sock itself. |
| * Register the reference count in the association. |
| */ |
| void sctp_transport_set_owner(struct sctp_transport *transport, |
| struct sctp_association *asoc) |
| { |
| transport->asoc = asoc; |
| sctp_association_hold(asoc); |
| } |
| |
| /* Initialize the pmtu of a 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) { |
| sctp_transport_dst_release(transport); |
| transport->af_specific->get_dst(transport, &transport->saddr, |
| &transport->fl, sk); |
| } |
| |
| 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_pl_send(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); |
| |
| if (t->pl.probe_count < SCTP_MAX_PROBES) { |
| t->pl.probe_count++; |
| return; |
| } |
| |
| 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_MIN_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); |
| } |
| } |
| t->pl.probe_count = 1; |
| } |
| |
| void 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) { |
| t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, |
| SCTP_MAX_PLPMTU); |
| return; |
| } |
| t->pl.probe_size += SCTP_PL_MIN_STEP; |
| if (t->pl.probe_size >= t->pl.probe_high) { |
| t->pl.probe_high = 0; |
| t->pl.raise_count = 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); |
| } |
| } else if (t->pl.state == SCTP_PL_COMPLETE) { |
| t->pl.raise_count++; |
| if (t->pl.raise_count == 30) { |
| /* Raise probe_size again after 30 * interval in Search Complete */ |
| t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */ |
| t->pl.probe_size += SCTP_PL_MIN_STEP; |
| } |
| } |
| } |
| |
| 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_MIN_PLPMTU; |
| t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t); |
| } |
| } 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); |
| } else if (pmtu > t->pl.pmtu && pmtu < t->pl.probe_size) { |
| t->pl.probe_size = pmtu; |
| t->pl.probe_count = 0; |
| |
| return false; |
| } |
| } 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); |
| } |
| } |
| |
| return true; |
| } |
| |
| 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_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); |
| |
| 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) { |
| 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); |
| 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 |
| * address. |
| */ |
| void sctp_transport_route(struct sctp_transport *transport, |
| union sctp_addr *saddr, struct sctp_sock *opt) |
| { |
| 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) |
| memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); |
| else |
| af->get_saddr(opt, transport, &transport->fl); |
| |
| sctp_transport_pmtu(transport, sctp_opt2sk(opt)); |
| |
| /* 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. */ |
| int sctp_transport_hold(struct sctp_transport *transport) |
| { |
| return refcount_inc_not_zero(&transport->refcnt); |
| } |
| |
| /* Release a reference to a transport and clean up |
| * if there are no more references. |
| */ |
| void sctp_transport_put(struct sctp_transport *transport) |
| { |
| if (refcount_dec_and_test(&transport->refcnt)) |
| sctp_transport_destroy(transport); |
| } |
| |
| /* Update transport's RTO based on the newly calculated RTT. */ |
| void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) |
| { |
| if (unlikely(!tp->rto_pending)) |
| /* We should not be doing any RTO updates unless rto_pending is set. */ |
| pr_debug("%s: rto_pending not set on transport %p!\n", __func__, tp); |
| |
| if (tp->rttvar || tp->srtt) { |
| struct net *net = tp->asoc->base.net; |
| /* 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' |
| */ |
| |
| /* Note: The above algorithm has been rewritten to |
| * express rto_beta and rto_alpha as inverse powers |
| * of two. |
| * 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)abs((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta); |
| tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha) |
| + (rtt >> net->sctp.rto_alpha); |
| } else { |
| /* 6.3.1 C2) When the first RTT measurement R is made, set |
| * SRTT <- R, RTTVAR <- R/2. |
| */ |
| tp->srtt = rtt; |
| tp->rttvar = rtt >> 1; |
| } |
| |
| /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then |
| * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY. |
| */ |
| if (tp->rttvar == 0) |
| tp->rttvar = SCTP_CLOCK_GRANULARITY; |
| |
| /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */ |
| tp->rto = tp->srtt + (tp->rttvar << 2); |
| |
| /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min |
| * seconds then it is rounded up to RTO.Min seconds. |
| */ |
| if (tp->rto < tp->asoc->rto_min) |
| tp->rto = tp->asoc->rto_min; |
| |
| /* 6.3.1 C7) A maximum value may be placed on RTO provided it is |
| * at least RTO.max seconds. |
| */ |
| if (tp->rto > tp->asoc->rto_max) |
| tp->rto = tp->asoc->rto_max; |
| |
| sctp_max_rto(tp->asoc, tp); |
| tp->rtt = rtt; |
| |
| /* Reset rto_pending so that a new RTT measurement is started when a |
| * new data chunk is sent. |
| */ |
| tp->rto_pending = 0; |
| |
| pr_debug("%s: transport:%p, rtt:%d, srtt:%d rttvar:%d, rto:%ld\n", |
| __func__, tp, rtt, tp->srtt, tp->rttvar, tp->rto); |
| } |
| |
| /* This routine updates the transport's cwnd and partial_bytes_acked |
| * parameters based on the bytes acked in the received SACK. |
| */ |
| void sctp_transport_raise_cwnd(struct sctp_transport *transport, |
| __u32 sack_ctsn, __u32 bytes_acked) |
| { |
| struct sctp_association *asoc = transport->asoc; |
| __u32 cwnd, ssthresh, flight_size, pba, pmtu; |
| |
| cwnd = transport->cwnd; |
| flight_size = transport->flight_size; |
| |
| /* See if we need to exit Fast Recovery first */ |
| if (asoc->fast_recovery && |
| TSN_lte(asoc->fast_recovery_exit, sack_ctsn)) |
| asoc->fast_recovery = 0; |
| |
| ssthresh = transport->ssthresh; |
| pba = transport->partial_bytes_acked; |
| pmtu = transport->asoc->pathmtu; |
| |
| if (cwnd <= ssthresh) { |
| /* 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 (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 |
| cwnd += bytes_acked; |
| |
| pr_debug("%s: slow start: transport:%p, bytes_acked:%d, " |
| "cwnd:%d, ssthresh:%d, flight_size:%d, pba:%d\n", |
| __func__, transport, bytes_acked, cwnd, ssthresh, |
| flight_size, pba); |
| } else { |
| /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, |
| * 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), 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 && flight_size < cwnd) |
| pba = cwnd; |
| if (pba >= cwnd && flight_size >= cwnd) { |
| pba = pba - cwnd; |
| cwnd += pmtu; |
| } |
| |
| pr_debug("%s: congestion avoidance: transport:%p, " |
| "bytes_acked:%d, cwnd:%d, ssthresh:%d, " |
| "flight_size:%d, pba:%d\n", __func__, |
| transport, bytes_acked, cwnd, ssthresh, |
| flight_size, pba); |
| } |
| |
| transport->cwnd = cwnd; |
| transport->partial_bytes_acked = pba; |
| } |
| |
| /* This routine is used to lower the transport's cwnd when congestion is |
| * detected. |
| */ |
| void sctp_transport_lower_cwnd(struct sctp_transport *transport, |
| enum sctp_lower_cwnd reason) |
| { |
| struct sctp_association *asoc = transport->asoc; |
| |
| switch (reason) { |
| case SCTP_LOWER_CWND_T3_RTX: |
| /* RFC 2960 Section 7.2.3, sctpimpguide |
| * When the T3-rtx timer expires on an address, SCTP should |
| * perform slow start by: |
| * ssthresh = max(cwnd/2, 4*MTU) |
| * cwnd = 1*MTU |
| * partial_bytes_acked = 0 |
| */ |
| transport->ssthresh = max(transport->cwnd/2, |
| 4*asoc->pathmtu); |
| transport->cwnd = asoc->pathmtu; |
| |
| /* T3-rtx also clears fast recovery */ |
| asoc->fast_recovery = 0; |
| break; |
| |
| case SCTP_LOWER_CWND_FAST_RTX: |
| /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the |
| * 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 |
| * 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 (asoc->fast_recovery) |
| return; |
| |
| /* Mark Fast recovery */ |
| asoc->fast_recovery = 1; |
| asoc->fast_recovery_exit = asoc->next_tsn - 1; |
| |
| transport->ssthresh = max(transport->cwnd/2, |
| 4*asoc->pathmtu); |
| transport->cwnd = transport->ssthresh; |
| break; |
| |
| case SCTP_LOWER_CWND_ECNE: |
| /* RFC 2481 Section 6.1.2. |
| * If the sender receives an ECN-Echo ACK packet |
| * then the sender knows that congestion was encountered in the |
| * network on the path from the sender to the receiver. The |
| * indication of congestion should be treated just as a |
| * congestion loss in non-ECN Capable TCP. That is, the TCP |
| * source halves the congestion window "cwnd" and reduces the |
| * slow start threshold "ssthresh". |
| * A critical condition is that TCP does not react to |
| * congestion indications more than once every window of |
| * data (or more loosely more than once every round-trip time). |
| */ |
| if (time_after(jiffies, transport->last_time_ecne_reduced + |
| transport->rtt)) { |
| transport->ssthresh = max(transport->cwnd/2, |
| 4*asoc->pathmtu); |
| transport->cwnd = transport->ssthresh; |
| transport->last_time_ecne_reduced = jiffies; |
| } |
| break; |
| |
| case SCTP_LOWER_CWND_INACTIVE: |
| /* RFC 2960 Section 7.2.1, sctpimpguide |
| * When the endpoint does not transmit data on a given |
| * transport address, the cwnd of the transport address |
| * should be adjusted to max(cwnd/2, 4*MTU) per RTO. |
| * NOTE: Although the draft recommends that this check needs |
| * to be done every RTO interval, we do it every hearbeat |
| * interval. |
| */ |
| transport->cwnd = max(transport->cwnd/2, |
| 4*asoc->pathmtu); |
| /* RFC 4960 Errata 3.27.2: also adjust sshthresh */ |
| transport->ssthresh = transport->cwnd; |
| break; |
| } |
| |
| transport->partial_bytes_acked = 0; |
| |
| pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d\n", |
| __func__, transport, reason, transport->cwnd, |
| transport->ssthresh); |
| } |
| |
| /* Apply Max.Burst limit to the congestion window: |
| * sctpimpguide-05 2.14.2 |
| * D) When the time comes for the sender to |
| * transmit new DATA chunks, the protocol parameter Max.Burst MUST |
| * first be applied to limit how many new DATA chunks may be sent. |
| * The limit is applied by adjusting cwnd as follows: |
| * if ((flightsize+ Max.Burst * MTU) < cwnd) |
| * cwnd = flightsize + Max.Burst * MTU |
| */ |
| |
| void sctp_transport_burst_limited(struct sctp_transport *t) |
| { |
| struct sctp_association *asoc = t->asoc; |
| u32 old_cwnd = t->cwnd; |
| u32 max_burst_bytes; |
| |
| if (t->burst_limited || asoc->max_burst == 0) |
| return; |
| |
| max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu); |
| if (max_burst_bytes < old_cwnd) { |
| t->cwnd = max_burst_bytes; |
| t->burst_limited = old_cwnd; |
| } |
| } |
| |
| /* Restore the old cwnd congestion window, after the burst had it's |
| * desired effect. |
| */ |
| void sctp_transport_burst_reset(struct sctp_transport *t) |
| { |
| if (t->burst_limited) { |
| t->cwnd = t->burst_limited; |
| t->burst_limited = 0; |
| } |
| } |
| |
| /* What is the next timeout value for this transport? */ |
| unsigned long sctp_transport_timeout(struct sctp_transport *trans) |
| { |
| /* 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 */ |
| 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->burst_limited = 0; |
| t->ssthresh = asoc->peer.i.a_rwnd; |
| t->rto = asoc->rto_initial; |
| sctp_max_rto(asoc, t); |
| t->rtt = 0; |
| t->srtt = 0; |
| t->rttvar = 0; |
| |
| /* Reset these additional variables 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; |
| |
| /* 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; |
| } |
| |
| /* Schedule retransmission on the given transport */ |
| void sctp_transport_immediate_rtx(struct sctp_transport *t) |
| { |
| /* Stop pending T3_rtx_timer */ |
| if (del_timer(&t->T3_rtx_timer)) |
| sctp_transport_put(t); |
| |
| sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX); |
| if (!timer_pending(&t->T3_rtx_timer)) { |
| if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto)) |
| sctp_transport_hold(t); |
| } |
| } |
| |
| /* 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; |
| } |