1/* SCTP kernel implementation
   2 * (C) Copyright IBM Corp. 2001, 2004
   3 * Copyright (c) 1999-2000 Cisco, Inc.
   4 * Copyright (c) 1999-2001 Motorola, Inc.
   5 * Copyright (c) 2001 Intel Corp.
   6 * Copyright (c) 2001 La Monte H.P. Yarroll
   7 *
   8 * This file is part of the SCTP kernel implementation
   9 *
  10 * This module provides the abstraction for an SCTP association.
  11 *
  12 * This SCTP implementation is free software;
  13 * you can redistribute it and/or modify it under the terms of
  14 * the GNU General Public License as published by
  15 * the Free Software Foundation; either version 2, or (at your option)
  16 * any later version.
  17 *
  18 * This SCTP implementation is distributed in the hope that it
  19 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20 *                 ************************
  21 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22 * See the GNU General Public License for more details.
  23 *
  24 * You should have received a copy of the GNU General Public License
  25 * along with GNU CC; see the file COPYING.  If not, see
  26 * <http://www.gnu.org/licenses/>.
  27 *
  28 * Please send any bug reports or fixes you make to the
  29 * email address(es):
  30 *    lksctp developers <linux-sctp@vger.kernel.org>
  31 *
  32 * Written or modified by:
  33 *    La Monte H.P. Yarroll <piggy@acm.org>
  34 *    Karl Knutson          <karl@athena.chicago.il.us>
  35 *    Jon Grimm             <jgrimm@us.ibm.com>
  36 *    Xingang Guo           <xingang.guo@intel.com>
  37 *    Hui Huang             <hui.huang@nokia.com>
  38 *    Sridhar Samudrala	    <sri@us.ibm.com>
  39 *    Daisy Chang	    <daisyc@us.ibm.com>
  40 *    Ryan Layer	    <rmlayer@us.ibm.com>
  41 *    Kevin Gao             <kevin.gao@intel.com>
  42 */
  43
  44#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  45
  46#include <linux/types.h>
  47#include <linux/fcntl.h>
  48#include <linux/poll.h>
  49#include <linux/init.h>
  50
  51#include <linux/slab.h>
  52#include <linux/in.h>
  53#include <net/ipv6.h>
  54#include <net/sctp/sctp.h>
  55#include <net/sctp/sm.h>
  56
  57/* Forward declarations for internal functions. */
  58static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
  59static void sctp_assoc_bh_rcv(struct work_struct *work);
  60static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
  61static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
  62
  63/* 1st Level Abstractions. */
  64
  65/* Initialize a new association from provided memory. */
  66static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
  67					  const struct sctp_endpoint *ep,
  68					  const struct sock *sk,
  69					  sctp_scope_t scope,
  70					  gfp_t gfp)
  71{
  72	struct net *net = sock_net(sk);
  73	struct sctp_sock *sp;
 
  74	int i;
  75	sctp_paramhdr_t *p;
  76	int err;
  77
  78	/* Retrieve the SCTP per socket area.  */
  79	sp = sctp_sk((struct sock *)sk);
  80
  81	/* Discarding const is appropriate here.  */
  82	asoc->ep = (struct sctp_endpoint *)ep;
  83	asoc->base.sk = (struct sock *)sk;
 
  84
  85	sctp_endpoint_hold(asoc->ep);
  86	sock_hold(asoc->base.sk);
  87
  88	/* Initialize the common base substructure.  */
  89	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
  90
  91	/* Initialize the object handling fields.  */
  92	atomic_set(&asoc->base.refcnt, 1);
  93
  94	/* Initialize the bind addr area.  */
  95	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
  96
  97	asoc->state = SCTP_STATE_CLOSED;
  98	asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
  99	asoc->user_frag = sp->user_frag;
 100
 101	/* Set the association max_retrans and RTO values from the
 102	 * socket values.
 103	 */
 104	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
 105	asoc->pf_retrans  = net->sctp.pf_retrans;
 
 
 106
 107	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
 108	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
 109	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
 110
 111	/* Initialize the association's heartbeat interval based on the
 112	 * sock configured value.
 113	 */
 114	asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
 
 
 
 115
 116	/* Initialize path max retrans value. */
 117	asoc->pathmaxrxt = sp->pathmaxrxt;
 118
 119	/* Initialize default path MTU. */
 120	asoc->pathmtu = sp->pathmtu;
 121
 122	/* Set association default SACK delay */
 123	asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
 124	asoc->sackfreq = sp->sackfreq;
 125
 126	/* Set the association default flags controlling
 127	 * Heartbeat, SACK delay, and Path MTU Discovery.
 128	 */
 129	asoc->param_flags = sp->param_flags;
 130
 131	/* Initialize the maximum number of new data packets that can be sent
 132	 * in a burst.
 133	 */
 134	asoc->max_burst = sp->max_burst;
 135
 
 
 136	/* initialize association timers */
 137	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
 138	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
 139	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
 140
 141	/* sctpimpguide Section 2.12.2
 142	 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
 143	 * recommended value of 5 times 'RTO.Max'.
 144	 */
 145	asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
 146		= 5 * asoc->rto_max;
 147
 148	asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
 149	asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
 
 150
 151	/* Initializes the timers */
 152	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
 153		setup_timer(&asoc->timers[i], sctp_timer_events[i],
 154				(unsigned long)asoc);
 155
 156	/* Pull default initialization values from the sock options.
 157	 * Note: This assumes that the values have already been
 158	 * validated in the sock.
 159	 */
 160	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
 161	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
 162	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;
 163
 164	asoc->max_init_timeo =
 165		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
 166
 167	/* Set the local window size for receive.
 168	 * This is also the rcvbuf space per association.
 169	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
 170	 * 1500 bytes in one SCTP packet.
 171	 */
 172	if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
 173		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
 174	else
 175		asoc->rwnd = sk->sk_rcvbuf/2;
 176
 177	asoc->a_rwnd = asoc->rwnd;
 178
 179	/* Use my own max window until I learn something better.  */
 180	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
 181
 182	/* Initialize the receive memory counter */
 183	atomic_set(&asoc->rmem_alloc, 0);
 184
 185	init_waitqueue_head(&asoc->wait);
 186
 187	asoc->c.my_vtag = sctp_generate_tag(ep);
 188	asoc->c.my_port = ep->base.bind_addr.port;
 189
 190	asoc->c.initial_tsn = sctp_generate_tsn(ep);
 191
 192	asoc->next_tsn = asoc->c.initial_tsn;
 193
 194	asoc->ctsn_ack_point = asoc->next_tsn - 1;
 195	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
 196	asoc->highest_sacked = asoc->ctsn_ack_point;
 197	asoc->last_cwr_tsn = asoc->ctsn_ack_point;
 198
 199	/* ADDIP Section 4.1 Asconf Chunk Procedures
 200	 *
 201	 * When an endpoint has an ASCONF signaled change to be sent to the
 202	 * remote endpoint it should do the following:
 203	 * ...
 204	 * A2) a serial number should be assigned to the chunk. The serial
 205	 * number SHOULD be a monotonically increasing number. The serial
 206	 * numbers SHOULD be initialized at the start of the
 207	 * association to the same value as the initial TSN.
 208	 */
 209	asoc->addip_serial = asoc->c.initial_tsn;
 
 210
 211	INIT_LIST_HEAD(&asoc->addip_chunk_list);
 212	INIT_LIST_HEAD(&asoc->asconf_ack_list);
 213
 214	/* Make an empty list of remote transport addresses.  */
 215	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
 216
 217	/* RFC 2960 5.1 Normal Establishment of an Association
 218	 *
 219	 * After the reception of the first data chunk in an
 220	 * association the endpoint must immediately respond with a
 221	 * sack to acknowledge the data chunk.  Subsequent
 222	 * acknowledgements should be done as described in Section
 223	 * 6.2.
 224	 *
 225	 * [We implement this by telling a new association that it
 226	 * already received one packet.]
 227	 */
 228	asoc->peer.sack_needed = 1;
 229	asoc->peer.sack_generation = 1;
 230
 231	/* Assume that the peer will tell us if he recognizes ASCONF
 232	 * as part of INIT exchange.
 233	 * The sctp_addip_noauth option is there for backward compatibility
 234	 * and will revert old behavior.
 235	 */
 236	if (net->sctp.addip_noauth)
 237		asoc->peer.asconf_capable = 1;
 238
 239	/* Create an input queue.  */
 240	sctp_inq_init(&asoc->base.inqueue);
 241	sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
 242
 243	/* Create an output queue.  */
 244	sctp_outq_init(asoc, &asoc->outqueue);
 245
 246	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
 247		goto fail_init;
 
 
 
 
 
 
 248
 249	/* Assume that peer would support both address types unless we are
 250	 * told otherwise.
 251	 */
 252	asoc->peer.ipv4_address = 1;
 253	if (asoc->base.sk->sk_family == PF_INET6)
 254		asoc->peer.ipv6_address = 1;
 255	INIT_LIST_HEAD(&asoc->asocs);
 256
 257	asoc->default_stream = sp->default_stream;
 258	asoc->default_ppid = sp->default_ppid;
 259	asoc->default_flags = sp->default_flags;
 260	asoc->default_context = sp->default_context;
 261	asoc->default_timetolive = sp->default_timetolive;
 262	asoc->default_rcv_context = sp->default_rcv_context;
 263
 264	/* AUTH related initializations */
 265	INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
 266	err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
 267	if (err)
 268		goto fail_init;
 269
 270	asoc->active_key_id = ep->active_key_id;
 
 271
 272	/* Save the hmacs and chunks list into this association */
 273	if (ep->auth_hmacs_list)
 274		memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
 275			ntohs(ep->auth_hmacs_list->param_hdr.length));
 276	if (ep->auth_chunk_list)
 277		memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
 278			ntohs(ep->auth_chunk_list->param_hdr.length));
 279
 280	/* Get the AUTH random number for this association */
 281	p = (sctp_paramhdr_t *)asoc->c.auth_random;
 282	p->type = SCTP_PARAM_RANDOM;
 283	p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
 284	get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
 285
 286	return asoc;
 287
 288fail_init:
 
 289	sock_put(asoc->base.sk);
 290	sctp_endpoint_put(asoc->ep);
 291	return NULL;
 292}
 293
 294/* Allocate and initialize a new association */
 295struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
 296					 const struct sock *sk,
 297					 sctp_scope_t scope,
 298					 gfp_t gfp)
 299{
 300	struct sctp_association *asoc;
 301
 302	asoc = kzalloc(sizeof(*asoc), gfp);
 303	if (!asoc)
 304		goto fail;
 305
 306	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
 307		goto fail_init;
 308
 309	SCTP_DBG_OBJCNT_INC(assoc);
 310
 311	pr_debug("Created asoc %p\n", asoc);
 312
 313	return asoc;
 314
 315fail_init:
 316	kfree(asoc);
 317fail:
 318	return NULL;
 319}
 320
 321/* Free this association if possible.  There may still be users, so
 322 * the actual deallocation may be delayed.
 323 */
 324void sctp_association_free(struct sctp_association *asoc)
 325{
 326	struct sock *sk = asoc->base.sk;
 327	struct sctp_transport *transport;
 328	struct list_head *pos, *temp;
 329	int i;
 330
 331	/* Only real associations count against the endpoint, so
 332	 * don't bother for if this is a temporary association.
 333	 */
 334	if (!list_empty(&asoc->asocs)) {
 335		list_del(&asoc->asocs);
 336
 337		/* Decrement the backlog value for a TCP-style listening
 338		 * socket.
 339		 */
 340		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
 341			sk->sk_ack_backlog--;
 342	}
 343
 344	/* Mark as dead, so other users can know this structure is
 345	 * going away.
 346	 */
 347	asoc->base.dead = true;
 348
 349	/* Dispose of any data lying around in the outqueue. */
 350	sctp_outq_free(&asoc->outqueue);
 351
 352	/* Dispose of any pending messages for the upper layer. */
 353	sctp_ulpq_free(&asoc->ulpq);
 354
 355	/* Dispose of any pending chunks on the inqueue. */
 356	sctp_inq_free(&asoc->base.inqueue);
 357
 358	sctp_tsnmap_free(&asoc->peer.tsn_map);
 359
 360	/* Free ssnmap storage. */
 361	sctp_ssnmap_free(asoc->ssnmap);
 
 
 
 362
 363	/* Clean up the bound address list. */
 364	sctp_bind_addr_free(&asoc->base.bind_addr);
 365
 366	/* Do we need to go through all of our timers and
 367	 * delete them?   To be safe we will try to delete all, but we
 368	 * should be able to go through and make a guess based
 369	 * on our state.
 370	 */
 371	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
 372		if (del_timer(&asoc->timers[i]))
 373			sctp_association_put(asoc);
 374	}
 375
 376	/* Free peer's cached cookie. */
 377	kfree(asoc->peer.cookie);
 378	kfree(asoc->peer.peer_random);
 379	kfree(asoc->peer.peer_chunks);
 380	kfree(asoc->peer.peer_hmacs);
 381
 382	/* Release the transport structures. */
 383	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
 384		transport = list_entry(pos, struct sctp_transport, transports);
 385		list_del_rcu(pos);
 386		sctp_unhash_transport(transport);
 387		sctp_transport_free(transport);
 388	}
 389
 390	asoc->peer.transport_count = 0;
 391
 392	sctp_asconf_queue_teardown(asoc);
 393
 394	/* Free pending address space being deleted */
 395	kfree(asoc->asconf_addr_del_pending);
 396
 397	/* AUTH - Free the endpoint shared keys */
 398	sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
 399
 400	/* AUTH - Free the association shared key */
 401	sctp_auth_key_put(asoc->asoc_shared_key);
 402
 403	sctp_association_put(asoc);
 404}
 405
 406/* Cleanup and free up an association. */
 407static void sctp_association_destroy(struct sctp_association *asoc)
 408{
 409	if (unlikely(!asoc->base.dead)) {
 410		WARN(1, "Attempt to destroy undead association %p!\n", asoc);
 411		return;
 412	}
 413
 414	sctp_endpoint_put(asoc->ep);
 415	sock_put(asoc->base.sk);
 416
 417	if (asoc->assoc_id != 0) {
 418		spin_lock_bh(&sctp_assocs_id_lock);
 419		idr_remove(&sctp_assocs_id, asoc->assoc_id);
 420		spin_unlock_bh(&sctp_assocs_id_lock);
 421	}
 422
 423	WARN_ON(atomic_read(&asoc->rmem_alloc));
 424
 425	kfree(asoc);
 426	SCTP_DBG_OBJCNT_DEC(assoc);
 427}
 428
 429/* Change the primary destination address for the peer. */
 430void sctp_assoc_set_primary(struct sctp_association *asoc,
 431			    struct sctp_transport *transport)
 432{
 433	int changeover = 0;
 434
 435	/* it's a changeover only if we already have a primary path
 436	 * that we are changing
 437	 */
 438	if (asoc->peer.primary_path != NULL &&
 439	    asoc->peer.primary_path != transport)
 440		changeover = 1 ;
 441
 442	asoc->peer.primary_path = transport;
 
 
 443
 444	/* Set a default msg_name for events. */
 445	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
 446	       sizeof(union sctp_addr));
 447
 448	/* If the primary path is changing, assume that the
 449	 * user wants to use this new path.
 450	 */
 451	if ((transport->state == SCTP_ACTIVE) ||
 452	    (transport->state == SCTP_UNKNOWN))
 453		asoc->peer.active_path = transport;
 454
 455	/*
 456	 * SFR-CACC algorithm:
 457	 * Upon the receipt of a request to change the primary
 458	 * destination address, on the data structure for the new
 459	 * primary destination, the sender MUST do the following:
 460	 *
 461	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
 462	 * to this destination address earlier. The sender MUST set
 463	 * CYCLING_CHANGEOVER to indicate that this switch is a
 464	 * double switch to the same destination address.
 465	 *
 466	 * Really, only bother is we have data queued or outstanding on
 467	 * the association.
 468	 */
 469	if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
 470		return;
 471
 472	if (transport->cacc.changeover_active)
 473		transport->cacc.cycling_changeover = changeover;
 474
 475	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
 476	 * a changeover has occurred.
 477	 */
 478	transport->cacc.changeover_active = changeover;
 479
 480	/* 3) The sender MUST store the next TSN to be sent in
 481	 * next_tsn_at_change.
 482	 */
 483	transport->cacc.next_tsn_at_change = asoc->next_tsn;
 484}
 485
 486/* Remove a transport from an association.  */
 487void sctp_assoc_rm_peer(struct sctp_association *asoc,
 488			struct sctp_transport *peer)
 489{
 490	struct list_head	*pos;
 491	struct sctp_transport	*transport;
 
 492
 493	pr_debug("%s: association:%p addr:%pISpc\n",
 494		 __func__, asoc, &peer->ipaddr.sa);
 495
 496	/* If we are to remove the current retran_path, update it
 497	 * to the next peer before removing this peer from the list.
 498	 */
 499	if (asoc->peer.retran_path == peer)
 500		sctp_assoc_update_retran_path(asoc);
 501
 502	/* Remove this peer from the list. */
 503	list_del_rcu(&peer->transports);
 504	/* Remove this peer from the transport hashtable */
 505	sctp_unhash_transport(peer);
 506
 507	/* Get the first transport of asoc. */
 508	pos = asoc->peer.transport_addr_list.next;
 509	transport = list_entry(pos, struct sctp_transport, transports);
 510
 511	/* Update any entries that match the peer to be deleted. */
 512	if (asoc->peer.primary_path == peer)
 513		sctp_assoc_set_primary(asoc, transport);
 514	if (asoc->peer.active_path == peer)
 515		asoc->peer.active_path = transport;
 516	if (asoc->peer.retran_path == peer)
 517		asoc->peer.retran_path = transport;
 518	if (asoc->peer.last_data_from == peer)
 519		asoc->peer.last_data_from = transport;
 520
 
 
 
 
 
 
 521	/* If we remove the transport an INIT was last sent to, set it to
 522	 * NULL. Combined with the update of the retran path above, this
 523	 * will cause the next INIT to be sent to the next available
 524	 * transport, maintaining the cycle.
 525	 */
 526	if (asoc->init_last_sent_to == peer)
 527		asoc->init_last_sent_to = NULL;
 528
 529	/* If we remove the transport an SHUTDOWN was last sent to, set it
 530	 * to NULL. Combined with the update of the retran path above, this
 531	 * will cause the next SHUTDOWN to be sent to the next available
 532	 * transport, maintaining the cycle.
 533	 */
 534	if (asoc->shutdown_last_sent_to == peer)
 535		asoc->shutdown_last_sent_to = NULL;
 536
 537	/* If we remove the transport an ASCONF was last sent to, set it to
 538	 * NULL.
 539	 */
 540	if (asoc->addip_last_asconf &&
 541	    asoc->addip_last_asconf->transport == peer)
 542		asoc->addip_last_asconf->transport = NULL;
 543
 544	/* If we have something on the transmitted list, we have to
 545	 * save it off.  The best place is the active path.
 546	 */
 547	if (!list_empty(&peer->transmitted)) {
 548		struct sctp_transport *active = asoc->peer.active_path;
 549		struct sctp_chunk *ch;
 550
 551		/* Reset the transport of each chunk on this list */
 552		list_for_each_entry(ch, &peer->transmitted,
 553					transmitted_list) {
 554			ch->transport = NULL;
 555			ch->rtt_in_progress = 0;
 556		}
 557
 558		list_splice_tail_init(&peer->transmitted,
 559					&active->transmitted);
 560
 561		/* Start a T3 timer here in case it wasn't running so
 562		 * that these migrated packets have a chance to get
 563		 * retransmitted.
 564		 */
 565		if (!timer_pending(&active->T3_rtx_timer))
 566			if (!mod_timer(&active->T3_rtx_timer,
 567					jiffies + active->rto))
 568				sctp_transport_hold(active);
 569	}
 570
 
 
 
 
 571	asoc->peer.transport_count--;
 572
 
 573	sctp_transport_free(peer);
 574}
 575
 576/* Add a transport address to an association.  */
 577struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
 578					   const union sctp_addr *addr,
 579					   const gfp_t gfp,
 580					   const int peer_state)
 581{
 582	struct net *net = sock_net(asoc->base.sk);
 583	struct sctp_transport *peer;
 584	struct sctp_sock *sp;
 585	unsigned short port;
 586
 587	sp = sctp_sk(asoc->base.sk);
 588
 589	/* AF_INET and AF_INET6 share common port field. */
 590	port = ntohs(addr->v4.sin_port);
 591
 592	pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
 593		 asoc, &addr->sa, peer_state);
 594
 595	/* Set the port if it has not been set yet.  */
 596	if (0 == asoc->peer.port)
 597		asoc->peer.port = port;
 598
 599	/* Check to see if this is a duplicate. */
 600	peer = sctp_assoc_lookup_paddr(asoc, addr);
 601	if (peer) {
 602		/* An UNKNOWN state is only set on transports added by
 603		 * user in sctp_connectx() call.  Such transports should be
 604		 * considered CONFIRMED per RFC 4960, Section 5.4.
 605		 */
 606		if (peer->state == SCTP_UNKNOWN) {
 607			peer->state = SCTP_ACTIVE;
 608		}
 609		return peer;
 610	}
 611
 612	peer = sctp_transport_new(net, addr, gfp);
 613	if (!peer)
 614		return NULL;
 615
 616	sctp_transport_set_owner(peer, asoc);
 617
 618	/* Initialize the peer's heartbeat interval based on the
 619	 * association configured value.
 620	 */
 621	peer->hbinterval = asoc->hbinterval;
 
 
 
 622
 623	/* Set the path max_retrans.  */
 624	peer->pathmaxrxt = asoc->pathmaxrxt;
 625
 626	/* And the partial failure retrans threshold */
 627	peer->pf_retrans = asoc->pf_retrans;
 
 
 628
 629	/* Initialize the peer's SACK delay timeout based on the
 630	 * association configured value.
 631	 */
 632	peer->sackdelay = asoc->sackdelay;
 633	peer->sackfreq = asoc->sackfreq;
 634
 
 
 
 
 
 
 
 
 
 
 
 
 635	/* Enable/disable heartbeat, SACK delay, and path MTU discovery
 636	 * based on association setting.
 637	 */
 638	peer->param_flags = asoc->param_flags;
 639
 640	sctp_transport_route(peer, NULL, sp);
 641
 642	/* Initialize the pmtu of the transport. */
 643	if (peer->param_flags & SPP_PMTUD_DISABLE) {
 644		if (asoc->pathmtu)
 645			peer->pathmtu = asoc->pathmtu;
 646		else
 647			peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
 648	}
 649
 650	/* If this is the first transport addr on this association,
 651	 * initialize the association PMTU to the peer's PMTU.
 652	 * If not and the current association PMTU is higher than the new
 653	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
 654	 */
 655	if (asoc->pathmtu)
 656		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
 657	else
 658		asoc->pathmtu = peer->pathmtu;
 659
 660	pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
 661		 asoc->pathmtu);
 662
 663	peer->pmtu_pending = 0;
 664
 665	asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
 666
 667	/* The asoc->peer.port might not be meaningful yet, but
 668	 * initialize the packet structure anyway.
 669	 */
 670	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
 671			 asoc->peer.port);
 672
 673	/* 7.2.1 Slow-Start
 674	 *
 675	 * o The initial cwnd before DATA transmission or after a sufficiently
 676	 *   long idle period MUST be set to
 677	 *      min(4*MTU, max(2*MTU, 4380 bytes))
 678	 *
 679	 * o The initial value of ssthresh MAY be arbitrarily high
 680	 *   (for example, implementations MAY use the size of the
 681	 *   receiver advertised window).
 682	 */
 683	peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
 684
 685	/* At this point, we may not have the receiver's advertised window,
 686	 * so initialize ssthresh to the default value and it will be set
 687	 * later when we process the INIT.
 688	 */
 689	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
 690
 691	peer->partial_bytes_acked = 0;
 692	peer->flight_size = 0;
 693	peer->burst_limited = 0;
 694
 695	/* Set the transport's RTO.initial value */
 696	peer->rto = asoc->rto_initial;
 697	sctp_max_rto(asoc, peer);
 698
 699	/* Set the peer's active state. */
 700	peer->state = peer_state;
 701
 
 
 
 
 
 
 
 
 702	/* Attach the remote transport to our asoc.  */
 703	list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
 704	asoc->peer.transport_count++;
 705	/* Add this peer into the transport hashtable */
 706	sctp_hash_transport(peer);
 707
 708	/* If we do not yet have a primary path, set one.  */
 709	if (!asoc->peer.primary_path) {
 710		sctp_assoc_set_primary(asoc, peer);
 711		asoc->peer.retran_path = peer;
 712	}
 713
 714	if (asoc->peer.active_path == asoc->peer.retran_path &&
 715	    peer->state != SCTP_UNCONFIRMED) {
 716		asoc->peer.retran_path = peer;
 717	}
 718
 719	return peer;
 720}
 721
 722/* Delete a transport address from an association.  */
 723void sctp_assoc_del_peer(struct sctp_association *asoc,
 724			 const union sctp_addr *addr)
 725{
 726	struct list_head	*pos;
 727	struct list_head	*temp;
 728	struct sctp_transport	*transport;
 729
 730	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
 731		transport = list_entry(pos, struct sctp_transport, transports);
 732		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
 733			/* Do book keeping for removing the peer and free it. */
 734			sctp_assoc_rm_peer(asoc, transport);
 735			break;
 736		}
 737	}
 738}
 739
 740/* Lookup a transport by address. */
 741struct sctp_transport *sctp_assoc_lookup_paddr(
 742					const struct sctp_association *asoc,
 743					const union sctp_addr *address)
 744{
 745	struct sctp_transport *t;
 746
 747	/* Cycle through all transports searching for a peer address. */
 748
 749	list_for_each_entry(t, &asoc->peer.transport_addr_list,
 750			transports) {
 751		if (sctp_cmp_addr_exact(address, &t->ipaddr))
 752			return t;
 753	}
 754
 755	return NULL;
 756}
 757
 758/* Remove all transports except a give one */
 759void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
 760				     struct sctp_transport *primary)
 761{
 762	struct sctp_transport	*temp;
 763	struct sctp_transport	*t;
 764
 765	list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
 766				 transports) {
 767		/* if the current transport is not the primary one, delete it */
 768		if (t != primary)
 769			sctp_assoc_rm_peer(asoc, t);
 770	}
 771}
 772
 773/* Engage in transport control operations.
 774 * Mark the transport up or down and send a notification to the user.
 775 * Select and update the new active and retran paths.
 776 */
 777void sctp_assoc_control_transport(struct sctp_association *asoc,
 778				  struct sctp_transport *transport,
 779				  sctp_transport_cmd_t command,
 780				  sctp_sn_error_t error)
 781{
 782	struct sctp_ulpevent *event;
 783	struct sockaddr_storage addr;
 784	int spc_state = 0;
 785	bool ulp_notify = true;
 786
 787	/* Record the transition on the transport.  */
 788	switch (command) {
 789	case SCTP_TRANSPORT_UP:
 790		/* If we are moving from UNCONFIRMED state due
 791		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
 792		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
 793		 */
 794		if (SCTP_UNCONFIRMED == transport->state &&
 795		    SCTP_HEARTBEAT_SUCCESS == error)
 796			spc_state = SCTP_ADDR_CONFIRMED;
 797		else
 798			spc_state = SCTP_ADDR_AVAILABLE;
 799		/* Don't inform ULP about transition from PF to
 800		 * active state and set cwnd to 1 MTU, see SCTP
 801		 * Quick failover draft section 5.1, point 5
 802		 */
 803		if (transport->state == SCTP_PF) {
 804			ulp_notify = false;
 805			transport->cwnd = asoc->pathmtu;
 806		}
 
 
 807		transport->state = SCTP_ACTIVE;
 
 808		break;
 809
 810	case SCTP_TRANSPORT_DOWN:
 811		/* If the transport was never confirmed, do not transition it
 812		 * to inactive state.  Also, release the cached route since
 813		 * there may be a better route next time.
 814		 */
 815		if (transport->state != SCTP_UNCONFIRMED)
 816			transport->state = SCTP_INACTIVE;
 817		else {
 818			dst_release(transport->dst);
 819			transport->dst = NULL;
 
 820			ulp_notify = false;
 821		}
 822
 823		spc_state = SCTP_ADDR_UNREACHABLE;
 824		break;
 825
 826	case SCTP_TRANSPORT_PF:
 827		transport->state = SCTP_PF;
 828		ulp_notify = false;
 
 
 
 829		break;
 830
 831	default:
 832		return;
 833	}
 834
 835	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification
 836	 * to the user.
 837	 */
 838	if (ulp_notify) {
 839		memset(&addr, 0, sizeof(struct sockaddr_storage));
 840		memcpy(&addr, &transport->ipaddr,
 841		       transport->af_specific->sockaddr_len);
 842
 843		event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
 844					0, spc_state, error, GFP_ATOMIC);
 845		if (event)
 846			sctp_ulpq_tail_event(&asoc->ulpq, event);
 847	}
 848
 849	/* Select new active and retran paths. */
 850	sctp_select_active_and_retran_path(asoc);
 851}
 852
 853/* Hold a reference to an association. */
 854void sctp_association_hold(struct sctp_association *asoc)
 855{
 856	atomic_inc(&asoc->base.refcnt);
 857}
 858
 859/* Release a reference to an association and cleanup
 860 * if there are no more references.
 861 */
 862void sctp_association_put(struct sctp_association *asoc)
 863{
 864	if (atomic_dec_and_test(&asoc->base.refcnt))
 865		sctp_association_destroy(asoc);
 866}
 867
 868/* Allocate the next TSN, Transmission Sequence Number, for the given
 869 * association.
 870 */
 871__u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
 872{
 873	/* From Section 1.6 Serial Number Arithmetic:
 874	 * Transmission Sequence Numbers wrap around when they reach
 875	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
 876	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
 877	 */
 878	__u32 retval = asoc->next_tsn;
 879	asoc->next_tsn++;
 880	asoc->unack_data++;
 881
 882	return retval;
 883}
 884
 885/* Compare two addresses to see if they match.  Wildcard addresses
 886 * only match themselves.
 887 */
 888int sctp_cmp_addr_exact(const union sctp_addr *ss1,
 889			const union sctp_addr *ss2)
 890{
 891	struct sctp_af *af;
 892
 893	af = sctp_get_af_specific(ss1->sa.sa_family);
 894	if (unlikely(!af))
 895		return 0;
 896
 897	return af->cmp_addr(ss1, ss2);
 898}
 899
 900/* Return an ecne chunk to get prepended to a packet.
 901 * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
 902 * No we don't, but we could/should.
 903 */
 904struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
 905{
 906	if (!asoc->need_ecne)
 907		return NULL;
 908
 909	/* Send ECNE if needed.
 910	 * Not being able to allocate a chunk here is not deadly.
 911	 */
 912	return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
 913}
 914
 915/*
 916 * Find which transport this TSN was sent on.
 917 */
 918struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
 919					     __u32 tsn)
 920{
 921	struct sctp_transport *active;
 922	struct sctp_transport *match;
 923	struct sctp_transport *transport;
 924	struct sctp_chunk *chunk;
 925	__be32 key = htonl(tsn);
 926
 927	match = NULL;
 928
 929	/*
 930	 * FIXME: In general, find a more efficient data structure for
 931	 * searching.
 932	 */
 933
 934	/*
 935	 * The general strategy is to search each transport's transmitted
 936	 * list.   Return which transport this TSN lives on.
 937	 *
 938	 * Let's be hopeful and check the active_path first.
 939	 * Another optimization would be to know if there is only one
 940	 * outbound path and not have to look for the TSN at all.
 941	 *
 942	 */
 943
 944	active = asoc->peer.active_path;
 945
 946	list_for_each_entry(chunk, &active->transmitted,
 947			transmitted_list) {
 948
 949		if (key == chunk->subh.data_hdr->tsn) {
 950			match = active;
 951			goto out;
 952		}
 953	}
 954
 955	/* If not found, go search all the other transports. */
 956	list_for_each_entry(transport, &asoc->peer.transport_addr_list,
 957			transports) {
 958
 959		if (transport == active)
 960			continue;
 961		list_for_each_entry(chunk, &transport->transmitted,
 962				transmitted_list) {
 963			if (key == chunk->subh.data_hdr->tsn) {
 964				match = transport;
 965				goto out;
 966			}
 967		}
 968	}
 969out:
 970	return match;
 971}
 972
 973/* Is this the association we are looking for? */
 974struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
 975					   struct net *net,
 976					   const union sctp_addr *laddr,
 977					   const union sctp_addr *paddr)
 978{
 979	struct sctp_transport *transport;
 980
 981	if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
 982	    (htons(asoc->peer.port) == paddr->v4.sin_port) &&
 983	    net_eq(sock_net(asoc->base.sk), net)) {
 984		transport = sctp_assoc_lookup_paddr(asoc, paddr);
 985		if (!transport)
 986			goto out;
 987
 988		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
 989					 sctp_sk(asoc->base.sk)))
 990			goto out;
 991	}
 992	transport = NULL;
 993
 994out:
 995	return transport;
 996}
 997
 998/* Do delayed input processing.  This is scheduled by sctp_rcv(). */
 999static void sctp_assoc_bh_rcv(struct work_struct *work)
1000{
1001	struct sctp_association *asoc =
1002		container_of(work, struct sctp_association,
1003			     base.inqueue.immediate);
1004	struct net *net = sock_net(asoc->base.sk);
 
1005	struct sctp_endpoint *ep;
1006	struct sctp_chunk *chunk;
1007	struct sctp_inq *inqueue;
1008	int state;
1009	sctp_subtype_t subtype;
1010	int error = 0;
 
1011
1012	/* The association should be held so we should be safe. */
1013	ep = asoc->ep;
1014
1015	inqueue = &asoc->base.inqueue;
1016	sctp_association_hold(asoc);
1017	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1018		state = asoc->state;
1019		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1020
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1021		/* SCTP-AUTH, Section 6.3:
1022		 *    The receiver has a list of chunk types which it expects
1023		 *    to be received only after an AUTH-chunk.  This list has
1024		 *    been sent to the peer during the association setup.  It
1025		 *    MUST silently discard these chunks if they are not placed
1026		 *    after an AUTH chunk in the packet.
1027		 */
1028		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1029			continue;
1030
1031		/* Remember where the last DATA chunk came from so we
1032		 * know where to send the SACK.
1033		 */
1034		if (sctp_chunk_is_data(chunk))
1035			asoc->peer.last_data_from = chunk->transport;
1036		else {
1037			SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1038			asoc->stats.ictrlchunks++;
1039			if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1040				asoc->stats.isacks++;
1041		}
1042
1043		if (chunk->transport)
1044			chunk->transport->last_time_heard = ktime_get();
1045
1046		/* Run through the state machine. */
1047		error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1048				   state, ep, asoc, chunk, GFP_ATOMIC);
1049
1050		/* Check to see if the association is freed in response to
1051		 * the incoming chunk.  If so, get out of the while loop.
1052		 */
1053		if (asoc->base.dead)
1054			break;
1055
1056		/* If there is an error on chunk, discard this packet. */
1057		if (error && chunk)
1058			chunk->pdiscard = 1;
 
 
 
1059	}
1060	sctp_association_put(asoc);
1061}
1062
1063/* This routine moves an association from its old sk to a new sk.  */
1064void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1065{
1066	struct sctp_sock *newsp = sctp_sk(newsk);
1067	struct sock *oldsk = assoc->base.sk;
1068
1069	/* Delete the association from the old endpoint's list of
1070	 * associations.
1071	 */
1072	list_del_init(&assoc->asocs);
1073
1074	/* Decrement the backlog value for a TCP-style socket. */
1075	if (sctp_style(oldsk, TCP))
1076		oldsk->sk_ack_backlog--;
1077
1078	/* Release references to the old endpoint and the sock.  */
1079	sctp_endpoint_put(assoc->ep);
1080	sock_put(assoc->base.sk);
1081
1082	/* Get a reference to the new endpoint.  */
1083	assoc->ep = newsp->ep;
1084	sctp_endpoint_hold(assoc->ep);
1085
1086	/* Get a reference to the new sock.  */
1087	assoc->base.sk = newsk;
1088	sock_hold(assoc->base.sk);
1089
1090	/* Add the association to the new endpoint's list of associations.  */
1091	sctp_endpoint_add_asoc(newsp->ep, assoc);
1092}
1093
1094/* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1095void sctp_assoc_update(struct sctp_association *asoc,
1096		       struct sctp_association *new)
1097{
1098	struct sctp_transport *trans;
1099	struct list_head *pos, *temp;
1100
1101	/* Copy in new parameters of peer. */
1102	asoc->c = new->c;
1103	asoc->peer.rwnd = new->peer.rwnd;
1104	asoc->peer.sack_needed = new->peer.sack_needed;
1105	asoc->peer.auth_capable = new->peer.auth_capable;
1106	asoc->peer.i = new->peer.i;
1107	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1108			 asoc->peer.i.initial_tsn, GFP_ATOMIC);
 
 
1109
1110	/* Remove any peer addresses not present in the new association. */
1111	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1112		trans = list_entry(pos, struct sctp_transport, transports);
1113		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1114			sctp_assoc_rm_peer(asoc, trans);
1115			continue;
1116		}
1117
1118		if (asoc->state >= SCTP_STATE_ESTABLISHED)
1119			sctp_transport_reset(trans);
1120	}
1121
1122	/* If the case is A (association restart), use
1123	 * initial_tsn as next_tsn. If the case is B, use
1124	 * current next_tsn in case data sent to peer
1125	 * has been discarded and needs retransmission.
1126	 */
1127	if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1128		asoc->next_tsn = new->next_tsn;
1129		asoc->ctsn_ack_point = new->ctsn_ack_point;
1130		asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1131
1132		/* Reinitialize SSN for both local streams
1133		 * and peer's streams.
1134		 */
1135		sctp_ssnmap_clear(asoc->ssnmap);
1136
1137		/* Flush the ULP reassembly and ordered queue.
1138		 * Any data there will now be stale and will
1139		 * cause problems.
1140		 */
1141		sctp_ulpq_flush(&asoc->ulpq);
1142
1143		/* reset the overall association error count so
1144		 * that the restarted association doesn't get torn
1145		 * down on the next retransmission timer.
1146		 */
1147		asoc->overall_error_count = 0;
1148
1149	} else {
1150		/* Add any peer addresses from the new association. */
1151		list_for_each_entry(trans, &new->peer.transport_addr_list,
1152				transports) {
1153			if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
1154				sctp_assoc_add_peer(asoc, &trans->ipaddr,
1155						    GFP_ATOMIC, trans->state);
1156		}
1157
1158		asoc->ctsn_ack_point = asoc->next_tsn - 1;
1159		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1160		if (!asoc->ssnmap) {
1161			/* Move the ssnmap. */
1162			asoc->ssnmap = new->ssnmap;
1163			new->ssnmap = NULL;
1164		}
1165
1166		if (!asoc->assoc_id) {
1167			/* get a new association id since we don't have one
1168			 * yet.
1169			 */
1170			sctp_assoc_set_id(asoc, GFP_ATOMIC);
1171		}
1172	}
1173
1174	/* SCTP-AUTH: Save the peer parameters from the new associations
1175	 * and also move the association shared keys over
1176	 */
1177	kfree(asoc->peer.peer_random);
1178	asoc->peer.peer_random = new->peer.peer_random;
1179	new->peer.peer_random = NULL;
1180
1181	kfree(asoc->peer.peer_chunks);
1182	asoc->peer.peer_chunks = new->peer.peer_chunks;
1183	new->peer.peer_chunks = NULL;
1184
1185	kfree(asoc->peer.peer_hmacs);
1186	asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1187	new->peer.peer_hmacs = NULL;
1188
1189	sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1190}
1191
1192/* Update the retran path for sending a retransmitted packet.
1193 * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1194 *
1195 *   When there is outbound data to send and the primary path
1196 *   becomes inactive (e.g., due to failures), or where the
1197 *   SCTP user explicitly requests to send data to an
1198 *   inactive destination transport address, before reporting
1199 *   an error to its ULP, the SCTP endpoint should try to send
1200 *   the data to an alternate active destination transport
1201 *   address if one exists.
1202 *
1203 *   When retransmitting data that timed out, if the endpoint
1204 *   is multihomed, it should consider each source-destination
1205 *   address pair in its retransmission selection policy.
1206 *   When retransmitting timed-out data, the endpoint should
1207 *   attempt to pick the most divergent source-destination
1208 *   pair from the original source-destination pair to which
1209 *   the packet was transmitted.
1210 *
1211 *   Note: Rules for picking the most divergent source-destination
1212 *   pair are an implementation decision and are not specified
1213 *   within this document.
1214 *
1215 * Our basic strategy is to round-robin transports in priorities
1216 * according to sctp_trans_score() e.g., if no such
1217 * transport with state SCTP_ACTIVE exists, round-robin through
1218 * SCTP_UNKNOWN, etc. You get the picture.
1219 */
1220static u8 sctp_trans_score(const struct sctp_transport *trans)
1221{
1222	switch (trans->state) {
1223	case SCTP_ACTIVE:
1224		return 3;	/* best case */
1225	case SCTP_UNKNOWN:
1226		return 2;
1227	case SCTP_PF:
1228		return 1;
1229	default: /* case SCTP_INACTIVE */
1230		return 0;	/* worst case */
1231	}
1232}
1233
1234static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1235						   struct sctp_transport *trans2)
1236{
1237	if (trans1->error_count > trans2->error_count) {
1238		return trans2;
1239	} else if (trans1->error_count == trans2->error_count &&
1240		   ktime_after(trans2->last_time_heard,
1241			       trans1->last_time_heard)) {
1242		return trans2;
1243	} else {
1244		return trans1;
1245	}
1246}
1247
1248static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1249						    struct sctp_transport *best)
1250{
1251	u8 score_curr, score_best;
1252
1253	if (best == NULL || curr == best)
1254		return curr;
1255
1256	score_curr = sctp_trans_score(curr);
1257	score_best = sctp_trans_score(best);
1258
1259	/* First, try a score-based selection if both transport states
1260	 * differ. If we're in a tie, lets try to make a more clever
1261	 * decision here based on error counts and last time heard.
1262	 */
1263	if (score_curr > score_best)
1264		return curr;
1265	else if (score_curr == score_best)
1266		return sctp_trans_elect_tie(best, curr);
1267	else
1268		return best;
1269}
1270
1271void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1272{
1273	struct sctp_transport *trans = asoc->peer.retran_path;
1274	struct sctp_transport *trans_next = NULL;
1275
1276	/* We're done as we only have the one and only path. */
1277	if (asoc->peer.transport_count == 1)
1278		return;
1279	/* If active_path and retran_path are the same and active,
1280	 * then this is the only active path. Use it.
1281	 */
1282	if (asoc->peer.active_path == asoc->peer.retran_path &&
1283	    asoc->peer.active_path->state == SCTP_ACTIVE)
1284		return;
1285
1286	/* Iterate from retran_path's successor back to retran_path. */
1287	for (trans = list_next_entry(trans, transports); 1;
1288	     trans = list_next_entry(trans, transports)) {
1289		/* Manually skip the head element. */
1290		if (&trans->transports == &asoc->peer.transport_addr_list)
1291			continue;
1292		if (trans->state == SCTP_UNCONFIRMED)
1293			continue;
1294		trans_next = sctp_trans_elect_best(trans, trans_next);
1295		/* Active is good enough for immediate return. */
1296		if (trans_next->state == SCTP_ACTIVE)
1297			break;
1298		/* We've reached the end, time to update path. */
1299		if (trans == asoc->peer.retran_path)
1300			break;
1301	}
1302
1303	asoc->peer.retran_path = trans_next;
1304
1305	pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1306		 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1307}
1308
1309static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1310{
1311	struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1312	struct sctp_transport *trans_pf = NULL;
1313
1314	/* Look for the two most recently used active transports. */
1315	list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1316			    transports) {
1317		/* Skip uninteresting transports. */
1318		if (trans->state == SCTP_INACTIVE ||
1319		    trans->state == SCTP_UNCONFIRMED)
1320			continue;
1321		/* Keep track of the best PF transport from our
1322		 * list in case we don't find an active one.
1323		 */
1324		if (trans->state == SCTP_PF) {
1325			trans_pf = sctp_trans_elect_best(trans, trans_pf);
1326			continue;
1327		}
1328		/* For active transports, pick the most recent ones. */
1329		if (trans_pri == NULL ||
1330		    ktime_after(trans->last_time_heard,
1331				trans_pri->last_time_heard)) {
1332			trans_sec = trans_pri;
1333			trans_pri = trans;
1334		} else if (trans_sec == NULL ||
1335			   ktime_after(trans->last_time_heard,
1336				       trans_sec->last_time_heard)) {
1337			trans_sec = trans;
1338		}
1339	}
1340
1341	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1342	 *
1343	 * By default, an endpoint should always transmit to the primary
1344	 * path, unless the SCTP user explicitly specifies the
1345	 * destination transport address (and possibly source transport
1346	 * address) to use. [If the primary is active but not most recent,
1347	 * bump the most recently used transport.]
1348	 */
1349	if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1350	     asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1351	     asoc->peer.primary_path != trans_pri) {
1352		trans_sec = trans_pri;
1353		trans_pri = asoc->peer.primary_path;
1354	}
1355
1356	/* We did not find anything useful for a possible retransmission
1357	 * path; either primary path that we found is the the same as
1358	 * the current one, or we didn't generally find an active one.
1359	 */
1360	if (trans_sec == NULL)
1361		trans_sec = trans_pri;
1362
1363	/* If we failed to find a usable transport, just camp on the
1364	 * active or pick a PF iff it's the better choice.
1365	 */
1366	if (trans_pri == NULL) {
1367		trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1368		trans_sec = trans_pri;
1369	}
1370
1371	/* Set the active and retran transports. */
1372	asoc->peer.active_path = trans_pri;
1373	asoc->peer.retran_path = trans_sec;
1374}
1375
1376struct sctp_transport *
1377sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1378				  struct sctp_transport *last_sent_to)
1379{
1380	/* If this is the first time packet is sent, use the active path,
1381	 * else use the retran path. If the last packet was sent over the
1382	 * retran path, update the retran path and use it.
1383	 */
1384	if (last_sent_to == NULL) {
1385		return asoc->peer.active_path;
1386	} else {
1387		if (last_sent_to == asoc->peer.retran_path)
1388			sctp_assoc_update_retran_path(asoc);
1389
1390		return asoc->peer.retran_path;
1391	}
1392}
1393
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1394/* Update the association's pmtu and frag_point by going through all the
1395 * transports. This routine is called when a transport's PMTU has changed.
1396 */
1397void sctp_assoc_sync_pmtu(struct sock *sk, struct sctp_association *asoc)
1398{
1399	struct sctp_transport *t;
1400	__u32 pmtu = 0;
1401
1402	if (!asoc)
1403		return;
1404
1405	/* Get the lowest pmtu of all the transports. */
1406	list_for_each_entry(t, &asoc->peer.transport_addr_list,
1407				transports) {
1408		if (t->pmtu_pending && t->dst) {
1409			sctp_transport_update_pmtu(sk, t,
1410						   WORD_TRUNC(dst_mtu(t->dst)));
1411			t->pmtu_pending = 0;
1412		}
1413		if (!pmtu || (t->pathmtu < pmtu))
1414			pmtu = t->pathmtu;
1415	}
1416
1417	if (pmtu) {
1418		asoc->pathmtu = pmtu;
1419		asoc->frag_point = sctp_frag_point(asoc, pmtu);
1420	}
1421
1422	pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1423		 asoc->pathmtu, asoc->frag_point);
1424}
1425
1426/* Should we send a SACK to update our peer? */
1427static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1428{
1429	struct net *net = sock_net(asoc->base.sk);
 
1430	switch (asoc->state) {
1431	case SCTP_STATE_ESTABLISHED:
1432	case SCTP_STATE_SHUTDOWN_PENDING:
1433	case SCTP_STATE_SHUTDOWN_RECEIVED:
1434	case SCTP_STATE_SHUTDOWN_SENT:
1435		if ((asoc->rwnd > asoc->a_rwnd) &&
1436		    ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1437			   (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1438			   asoc->pathmtu)))
1439			return true;
1440		break;
1441	default:
1442		break;
1443	}
1444	return false;
1445}
1446
1447/* Increase asoc's rwnd by len and send any window update SACK if needed. */
1448void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1449{
1450	struct sctp_chunk *sack;
1451	struct timer_list *timer;
1452
1453	if (asoc->rwnd_over) {
1454		if (asoc->rwnd_over >= len) {
1455			asoc->rwnd_over -= len;
1456		} else {
1457			asoc->rwnd += (len - asoc->rwnd_over);
1458			asoc->rwnd_over = 0;
1459		}
1460	} else {
1461		asoc->rwnd += len;
1462	}
1463
1464	/* If we had window pressure, start recovering it
1465	 * once our rwnd had reached the accumulated pressure
1466	 * threshold.  The idea is to recover slowly, but up
1467	 * to the initial advertised window.
1468	 */
1469	if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
1470		int change = min(asoc->pathmtu, asoc->rwnd_press);
1471		asoc->rwnd += change;
1472		asoc->rwnd_press -= change;
1473	}
1474
1475	pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1476		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1477		 asoc->a_rwnd);
1478
1479	/* Send a window update SACK if the rwnd has increased by at least the
1480	 * minimum of the association's PMTU and half of the receive buffer.
1481	 * The algorithm used is similar to the one described in
1482	 * Section 4.2.3.3 of RFC 1122.
1483	 */
1484	if (sctp_peer_needs_update(asoc)) {
1485		asoc->a_rwnd = asoc->rwnd;
1486
1487		pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1488			 "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1489			 asoc->a_rwnd);
1490
1491		sack = sctp_make_sack(asoc);
1492		if (!sack)
1493			return;
1494
1495		asoc->peer.sack_needed = 0;
1496
1497		sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
1498
1499		/* Stop the SACK timer.  */
1500		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1501		if (del_timer(timer))
1502			sctp_association_put(asoc);
1503	}
1504}
1505
1506/* Decrease asoc's rwnd by len. */
1507void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1508{
1509	int rx_count;
1510	int over = 0;
1511
1512	if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1513		pr_debug("%s: association:%p has asoc->rwnd:%u, "
1514			 "asoc->rwnd_over:%u!\n", __func__, asoc,
1515			 asoc->rwnd, asoc->rwnd_over);
1516
1517	if (asoc->ep->rcvbuf_policy)
1518		rx_count = atomic_read(&asoc->rmem_alloc);
1519	else
1520		rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1521
1522	/* If we've reached or overflowed our receive buffer, announce
1523	 * a 0 rwnd if rwnd would still be positive.  Store the
1524	 * the potential pressure overflow so that the window can be restored
1525	 * back to original value.
1526	 */
1527	if (rx_count >= asoc->base.sk->sk_rcvbuf)
1528		over = 1;
1529
1530	if (asoc->rwnd >= len) {
1531		asoc->rwnd -= len;
1532		if (over) {
1533			asoc->rwnd_press += asoc->rwnd;
1534			asoc->rwnd = 0;
1535		}
1536	} else {
1537		asoc->rwnd_over = len - asoc->rwnd;
1538		asoc->rwnd = 0;
1539	}
1540
1541	pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1542		 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1543		 asoc->rwnd_press);
1544}
1545
1546/* Build the bind address list for the association based on info from the
1547 * local endpoint and the remote peer.
1548 */
1549int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1550				     sctp_scope_t scope, gfp_t gfp)
1551{
 
1552	int flags;
1553
1554	/* Use scoping rules to determine the subset of addresses from
1555	 * the endpoint.
1556	 */
1557	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
 
 
1558	if (asoc->peer.ipv4_address)
1559		flags |= SCTP_ADDR4_PEERSUPP;
1560	if (asoc->peer.ipv6_address)
1561		flags |= SCTP_ADDR6_PEERSUPP;
1562
1563	return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1564				   &asoc->base.bind_addr,
1565				   &asoc->ep->base.bind_addr,
1566				   scope, gfp, flags);
1567}
1568
1569/* Build the association's bind address list from the cookie.  */
1570int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1571					 struct sctp_cookie *cookie,
1572					 gfp_t gfp)
1573{
1574	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
 
1575	int var_size3 = cookie->raw_addr_list_len;
1576	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1577
1578	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1579				      asoc->ep->base.bind_addr.port, gfp);
1580}
1581
1582/* Lookup laddr in the bind address list of an association. */
1583int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1584			    const union sctp_addr *laddr)
1585{
1586	int found = 0;
1587
1588	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1589	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1590				 sctp_sk(asoc->base.sk)))
1591		found = 1;
1592
1593	return found;
1594}
1595
1596/* Set an association id for a given association */
1597int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1598{
1599	bool preload = gfpflags_allow_blocking(gfp);
1600	int ret;
1601
1602	/* If the id is already assigned, keep it. */
1603	if (asoc->assoc_id)
1604		return 0;
1605
1606	if (preload)
1607		idr_preload(gfp);
1608	spin_lock_bh(&sctp_assocs_id_lock);
1609	/* 0 is not a valid assoc_id, must be >= 1 */
1610	ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
 
 
 
1611	spin_unlock_bh(&sctp_assocs_id_lock);
1612	if (preload)
1613		idr_preload_end();
1614	if (ret < 0)
1615		return ret;
1616
1617	asoc->assoc_id = (sctp_assoc_t)ret;
1618	return 0;
1619}
1620
1621/* Free the ASCONF queue */
1622static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1623{
1624	struct sctp_chunk *asconf;
1625	struct sctp_chunk *tmp;
1626
1627	list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1628		list_del_init(&asconf->list);
1629		sctp_chunk_free(asconf);
1630	}
1631}
1632
1633/* Free asconf_ack cache */
1634static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1635{
1636	struct sctp_chunk *ack;
1637	struct sctp_chunk *tmp;
1638
1639	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1640				transmitted_list) {
1641		list_del_init(&ack->transmitted_list);
1642		sctp_chunk_free(ack);
1643	}
1644}
1645
1646/* Clean up the ASCONF_ACK queue */
1647void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1648{
1649	struct sctp_chunk *ack;
1650	struct sctp_chunk *tmp;
1651
1652	/* We can remove all the entries from the queue up to
1653	 * the "Peer-Sequence-Number".
1654	 */
1655	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1656				transmitted_list) {
1657		if (ack->subh.addip_hdr->serial ==
1658				htonl(asoc->peer.addip_serial))
1659			break;
1660
1661		list_del_init(&ack->transmitted_list);
1662		sctp_chunk_free(ack);
1663	}
1664}
1665
1666/* Find the ASCONF_ACK whose serial number matches ASCONF */
1667struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1668					const struct sctp_association *asoc,
1669					__be32 serial)
1670{
1671	struct sctp_chunk *ack;
1672
1673	/* Walk through the list of cached ASCONF-ACKs and find the
1674	 * ack chunk whose serial number matches that of the request.
1675	 */
1676	list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1677		if (sctp_chunk_pending(ack))
1678			continue;
1679		if (ack->subh.addip_hdr->serial == serial) {
1680			sctp_chunk_hold(ack);
1681			return ack;
1682		}
1683	}
1684
1685	return NULL;
1686}
1687
1688void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1689{
1690	/* Free any cached ASCONF_ACK chunk. */
1691	sctp_assoc_free_asconf_acks(asoc);
1692
1693	/* Free the ASCONF queue. */
1694	sctp_assoc_free_asconf_queue(asoc);
1695
1696	/* Free any cached ASCONF chunk. */
1697	if (asoc->addip_last_asconf)
1698		sctp_chunk_free(asoc->addip_last_asconf);
1699}