From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/sctp/transport.c | 656 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 656 insertions(+) create mode 100644 net/sctp/transport.c (limited to 'net/sctp/transport.c') diff --git a/net/sctp/transport.c b/net/sctp/transport.c new file mode 100644 index 000000000..a0a431824 --- /dev/null +++ b/net/sctp/transport.c @@ -0,0 +1,656 @@ +/* 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 tranport 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, see + * . + * + * Please send any bug reports or fixes you make to the + * email address(es): + * lksctp developers + * + * Written or modified by: + * La Monte H.P. Yarroll + * Karl Knutson + * Jon Grimm + * Xingang Guo + * Hui Huang + * Sridhar Samudrala + * Ardelle Fan + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include + +/* 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->ipaddr = *addr; + peer->af_specific = sctp_get_af_specific(addr->sa.sa_family); + 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 = ktime_get(); + 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); + + 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); + + /* 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; +} + +/* 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) +{ + transport->dead = 1; + + /* 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 tranport is going away. + */ + if (del_timer(&transport->T3_rtx_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); + + 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(!transport->dead)) { + 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_timers(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); + + /* When a data chunk is sent, reset the heartbeat interval. */ + if (!mod_timer(&transport->hb_timer, + sctp_transport_timeout(transport))) + 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) { + dst_release(transport->dst); + transport->af_specific->get_dst(transport, &transport->saddr, + &transport->fl, sk); + } + + if (transport->dst) { + transport->pathmtu = dst_mtu(transport->dst); + } else + transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; +} + +void sctp_transport_update_pmtu(struct sock *sk, struct sctp_transport *t, u32 pmtu) +{ + struct dst_entry *dst; + + 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; + } + + dst = sctp_transport_dst_check(t); + if (!dst) + t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); + + if (dst) { + dst->ops->update_pmtu(dst, sk, NULL, pmtu); + + dst = sctp_transport_dst_check(t); + if (!dst) + t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); + } +} + +/* 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; + + 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); + + if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) { + return; + } + if (transport->dst) { + transport->pathmtu = dst_mtu(transport->dst); + + /* 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->to_sk_saddr(&transport->saddr, + asoc->base.sk); + } else + transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; +} + +/* Hold a reference to a transport. */ +void sctp_transport_hold(struct sctp_transport *transport) +{ + atomic_inc(&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 (atomic_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 = sock_net(tp->asoc->base.sk); + /* 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)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); + } 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; + + /* 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; + + 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; + + 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 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. + * + * 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). + */ + pba += bytes_acked; + if (pba >= cwnd) { + cwnd += pmtu; + pba = ((cwnd < pba) ? (pba - cwnd) : 0); + } + + 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, + sctp_lower_cwnd_t 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); + 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) + prandom_u32_max(trans->rto); + + if (trans->state != SCTP_UNCONFIRMED && + trans->state != SCTP_PF) + timeout += trans->hbinterval; + + return timeout + jiffies; +} + +/* 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 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; + + /* 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); + } +} -- cgit v1.2.3-54-g00ecf