linux/net/sctp/transport.c
Jason Gunthorpe 299ee123e1 sctp: Fixup v4mapped behaviour to comply with Sock API
The SCTP socket extensions API document describes the v4mapping option as
follows:

8.1.15.  Set/Clear IPv4 Mapped Addresses (SCTP_I_WANT_MAPPED_V4_ADDR)

   This socket option is a Boolean flag which turns on or off the
   mapping of IPv4 addresses.  If this option is turned on, then IPv4
   addresses will be mapped to V6 representation.  If this option is
   turned off, then no mapping will be done of V4 addresses and a user
   will receive both PF_INET6 and PF_INET type addresses on the socket.
   See [RFC3542] for more details on mapped V6 addresses.

This description isn't really in line with what the code does though.

Introduce addr_to_user (renamed addr_v4map), which should be called
before any sockaddr is passed back to user space. The new function
places the sockaddr into the correct format depending on the
SCTP_I_WANT_MAPPED_V4_ADDR option.

Audit all places that touched v4mapped and either sanely construct
a v4 or v6 address then call addr_to_user, or drop the
unnecessary v4mapped check entirely.

Audit all places that call addr_to_user and verify they are on a sycall
return path.

Add a custom getname that formats the address properly.

Several bugs are addressed:
 - SCTP_I_WANT_MAPPED_V4_ADDR=0 often returned garbage for
   addresses to user space
 - The addr_len returned from recvmsg was not correct when
   returning AF_INET on a v6 socket
 - flowlabel and scope_id were not zerod when promoting
   a v4 to v6
 - Some syscalls like bind and connect behaved differently
   depending on v4mapped

Tested bind, getpeername, getsockname, connect, and recvmsg for proper
behaviour in v4mapped = 1 and 0 cases.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-31 21:49:06 -07:00

657 lines
20 KiB
C

/* 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
* <http://www.gnu.org/licenses/>.
*
* 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->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);
}
}