net/sctp/associola.c

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This source file includes following definitions.
sctp_association_init
sctp_association_new
sctp_association_free
sctp_association_destroy
sctp_assoc_set_primary
sctp_assoc_rm_peer
sctp_assoc_add_peer
sctp_assoc_del_peer
sctp_assoc_lookup_paddr
sctp_assoc_del_nonprimary_peers
sctp_assoc_control_transport
sctp_association_hold
sctp_association_put
sctp_association_get_next_tsn
sctp_cmp_addr_exact
sctp_get_ecne_prepend
sctp_assoc_lookup_tsn
sctp_assoc_bh_rcv
sctp_assoc_migrate
sctp_assoc_update
sctp_trans_score
sctp_trans_elect_tie
sctp_trans_elect_best
sctp_assoc_update_retran_path
sctp_select_active_and_retran_path
sctp_assoc_choose_alter_transport
sctp_assoc_update_frag_point
sctp_assoc_set_pmtu
sctp_assoc_sync_pmtu
sctp_peer_needs_update
sctp_assoc_rwnd_increase
sctp_assoc_rwnd_decrease
sctp_assoc_set_bind_addr_from_ep
sctp_assoc_set_bind_addr_from_cookie
sctp_assoc_lookup_laddr
sctp_assoc_set_id
sctp_assoc_free_asconf_queue
sctp_assoc_free_asconf_acks
sctp_assoc_clean_asconf_ack_cache
sctp_assoc_lookup_asconf_ack
sctp_asconf_queue_teardown
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* SCTP kernel implementation
   3  * (C) Copyright IBM Corp. 2001, 2004
   4  * Copyright (c) 1999-2000 Cisco, Inc.
   5  * Copyright (c) 1999-2001 Motorola, Inc.
   6  * Copyright (c) 2001 Intel Corp.
   7  * Copyright (c) 2001 La Monte H.P. Yarroll
   8  *
   9  * This file is part of the SCTP kernel implementation
  10  *
  11  * This module provides the abstraction for an SCTP association.
  12  *
  13  * Please send any bug reports or fixes you make to the
  14  * email address(es):
  15  *    lksctp developers <linux-sctp@vger.kernel.org>
  16  *
  17  * Written or modified by:
  18  *    La Monte H.P. Yarroll <piggy@acm.org>
  19  *    Karl Knutson          <karl@athena.chicago.il.us>
  20  *    Jon Grimm             <jgrimm@us.ibm.com>
  21  *    Xingang Guo           <xingang.guo@intel.com>
  22  *    Hui Huang             <hui.huang@nokia.com>
  23  *    Sridhar Samudrala     <sri@us.ibm.com>
  24  *    Daisy Chang           <daisyc@us.ibm.com>
  25  *    Ryan Layer            <rmlayer@us.ibm.com>
  26  *    Kevin Gao             <kevin.gao@intel.com>
  27  */
  28 
  29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  30 
  31 #include <linux/types.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/poll.h>
  34 #include <linux/init.h>
  35 
  36 #include <linux/slab.h>
  37 #include <linux/in.h>
  38 #include <net/ipv6.h>
  39 #include <net/sctp/sctp.h>
  40 #include <net/sctp/sm.h>
  41 
  42 /* Forward declarations for internal functions. */
  43 static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
  44 static void sctp_assoc_bh_rcv(struct work_struct *work);
  45 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
  46 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
  47 
  48 /* 1st Level Abstractions. */
  49 
  50 /* Initialize a new association from provided memory. */
  51 static struct sctp_association *sctp_association_init(
  52                                         struct sctp_association *asoc,
  53                                         const struct sctp_endpoint *ep,
  54                                         const struct sock *sk,
  55                                         enum sctp_scope scope, gfp_t gfp)
  56 {
  57         struct sctp_sock *sp;
  58         struct sctp_paramhdr *p;
  59         int i;
  60 
  61         /* Retrieve the SCTP per socket area.  */
  62         sp = sctp_sk((struct sock *)sk);
  63 
  64         /* Discarding const is appropriate here.  */
  65         asoc->ep = (struct sctp_endpoint *)ep;
  66         asoc->base.sk = (struct sock *)sk;
  67         asoc->base.net = sock_net(sk);
  68 
  69         sctp_endpoint_hold(asoc->ep);
  70         sock_hold(asoc->base.sk);
  71 
  72         /* Initialize the common base substructure.  */
  73         asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
  74 
  75         /* Initialize the object handling fields.  */
  76         refcount_set(&asoc->base.refcnt, 1);
  77 
  78         /* Initialize the bind addr area.  */
  79         sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
  80 
  81         asoc->state = SCTP_STATE_CLOSED;
  82         asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
  83         asoc->user_frag = sp->user_frag;
  84 
  85         /* Set the association max_retrans and RTO values from the
  86          * socket values.
  87          */
  88         asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
  89         asoc->pf_retrans  = sp->pf_retrans;
  90 
  91         asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
  92         asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
  93         asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
  94 
  95         /* Initialize the association's heartbeat interval based on the
  96          * sock configured value.
  97          */
  98         asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
  99 
 100         /* Initialize path max retrans value. */
 101         asoc->pathmaxrxt = sp->pathmaxrxt;
 102 
 103         asoc->flowlabel = sp->flowlabel;
 104         asoc->dscp = sp->dscp;
 105 
 106         /* Set association default SACK delay */
 107         asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
 108         asoc->sackfreq = sp->sackfreq;
 109 
 110         /* Set the association default flags controlling
 111          * Heartbeat, SACK delay, and Path MTU Discovery.
 112          */
 113         asoc->param_flags = sp->param_flags;
 114 
 115         /* Initialize the maximum number of new data packets that can be sent
 116          * in a burst.
 117          */
 118         asoc->max_burst = sp->max_burst;
 119 
 120         asoc->subscribe = sp->subscribe;
 121 
 122         /* initialize association timers */
 123         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
 124         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
 125         asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
 126 
 127         /* sctpimpguide Section 2.12.2
 128          * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
 129          * recommended value of 5 times 'RTO.Max'.
 130          */
 131         asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
 132                 = 5 * asoc->rto_max;
 133 
 134         asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
 135         asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
 136 
 137         /* Initializes the timers */
 138         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
 139                 timer_setup(&asoc->timers[i], sctp_timer_events[i], 0);
 140 
 141         /* Pull default initialization values from the sock options.
 142          * Note: This assumes that the values have already been
 143          * validated in the sock.
 144          */
 145         asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
 146         asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
 147         asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
 148 
 149         asoc->max_init_timeo =
 150                  msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
 151 
 152         /* Set the local window size for receive.
 153          * This is also the rcvbuf space per association.
 154          * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
 155          * 1500 bytes in one SCTP packet.
 156          */
 157         if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
 158                 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
 159         else
 160                 asoc->rwnd = sk->sk_rcvbuf/2;
 161 
 162         asoc->a_rwnd = asoc->rwnd;
 163 
 164         /* Use my own max window until I learn something better.  */
 165         asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
 166 
 167         /* Initialize the receive memory counter */
 168         atomic_set(&asoc->rmem_alloc, 0);
 169 
 170         init_waitqueue_head(&asoc->wait);
 171 
 172         asoc->c.my_vtag = sctp_generate_tag(ep);
 173         asoc->c.my_port = ep->base.bind_addr.port;
 174 
 175         asoc->c.initial_tsn = sctp_generate_tsn(ep);
 176 
 177         asoc->next_tsn = asoc->c.initial_tsn;
 178 
 179         asoc->ctsn_ack_point = asoc->next_tsn - 1;
 180         asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
 181         asoc->highest_sacked = asoc->ctsn_ack_point;
 182         asoc->last_cwr_tsn = asoc->ctsn_ack_point;
 183 
 184         /* ADDIP Section 4.1 Asconf Chunk Procedures
 185          *
 186          * When an endpoint has an ASCONF signaled change to be sent to the
 187          * remote endpoint it should do the following:
 188          * ...
 189          * A2) a serial number should be assigned to the chunk. The serial
 190          * number SHOULD be a monotonically increasing number. The serial
 191          * numbers SHOULD be initialized at the start of the
 192          * association to the same value as the initial TSN.
 193          */
 194         asoc->addip_serial = asoc->c.initial_tsn;
 195         asoc->strreset_outseq = asoc->c.initial_tsn;
 196 
 197         INIT_LIST_HEAD(&asoc->addip_chunk_list);
 198         INIT_LIST_HEAD(&asoc->asconf_ack_list);
 199 
 200         /* Make an empty list of remote transport addresses.  */
 201         INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
 202 
 203         /* RFC 2960 5.1 Normal Establishment of an Association
 204          *
 205          * After the reception of the first data chunk in an
 206          * association the endpoint must immediately respond with a
 207          * sack to acknowledge the data chunk.  Subsequent
 208          * acknowledgements should be done as described in Section
 209          * 6.2.
 210          *
 211          * [We implement this by telling a new association that it
 212          * already received one packet.]
 213          */
 214         asoc->peer.sack_needed = 1;
 215         asoc->peer.sack_generation = 1;
 216 
 217         /* Create an input queue.  */
 218         sctp_inq_init(&asoc->base.inqueue);
 219         sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
 220 
 221         /* Create an output queue.  */
 222         sctp_outq_init(asoc, &asoc->outqueue);
 223 
 224         if (!sctp_ulpq_init(&asoc->ulpq, asoc))
 225                 goto fail_init;
 226 
 227         if (sctp_stream_init(&asoc->stream, asoc->c.sinit_num_ostreams,
 228                              0, gfp))
 229                 goto fail_init;
 230 
 231         /* Initialize default path MTU. */
 232         asoc->pathmtu = sp->pathmtu;
 233         sctp_assoc_update_frag_point(asoc);
 234 
 235         /* Assume that peer would support both address types unless we are
 236          * told otherwise.
 237          */
 238         asoc->peer.ipv4_address = 1;
 239         if (asoc->base.sk->sk_family == PF_INET6)
 240                 asoc->peer.ipv6_address = 1;
 241         INIT_LIST_HEAD(&asoc->asocs);
 242 
 243         asoc->default_stream = sp->default_stream;
 244         asoc->default_ppid = sp->default_ppid;
 245         asoc->default_flags = sp->default_flags;
 246         asoc->default_context = sp->default_context;
 247         asoc->default_timetolive = sp->default_timetolive;
 248         asoc->default_rcv_context = sp->default_rcv_context;
 249 
 250         /* AUTH related initializations */
 251         INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
 252         if (sctp_auth_asoc_copy_shkeys(ep, asoc, gfp))
 253                 goto stream_free;
 254 
 255         asoc->active_key_id = ep->active_key_id;
 256         asoc->strreset_enable = ep->strreset_enable;
 257 
 258         /* Save the hmacs and chunks list into this association */
 259         if (ep->auth_hmacs_list)
 260                 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
 261                         ntohs(ep->auth_hmacs_list->param_hdr.length));
 262         if (ep->auth_chunk_list)
 263                 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
 264                         ntohs(ep->auth_chunk_list->param_hdr.length));
 265 
 266         /* Get the AUTH random number for this association */
 267         p = (struct sctp_paramhdr *)asoc->c.auth_random;
 268         p->type = SCTP_PARAM_RANDOM;
 269         p->length = htons(sizeof(*p) + SCTP_AUTH_RANDOM_LENGTH);
 270         get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
 271 
 272         return asoc;
 273 
 274 stream_free:
 275         sctp_stream_free(&asoc->stream);
 276 fail_init:
 277         sock_put(asoc->base.sk);
 278         sctp_endpoint_put(asoc->ep);
 279         return NULL;
 280 }
 281 
 282 /* Allocate and initialize a new association */
 283 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
 284                                               const struct sock *sk,
 285                                               enum sctp_scope scope, gfp_t gfp)
 286 {
 287         struct sctp_association *asoc;
 288 
 289         asoc = kzalloc(sizeof(*asoc), gfp);
 290         if (!asoc)
 291                 goto fail;
 292 
 293         if (!sctp_association_init(asoc, ep, sk, scope, gfp))
 294                 goto fail_init;
 295 
 296         SCTP_DBG_OBJCNT_INC(assoc);
 297 
 298         pr_debug("Created asoc %p\n", asoc);
 299 
 300         return asoc;
 301 
 302 fail_init:
 303         kfree(asoc);
 304 fail:
 305         return NULL;
 306 }
 307 
 308 /* Free this association if possible.  There may still be users, so
 309  * the actual deallocation may be delayed.
 310  */
 311 void sctp_association_free(struct sctp_association *asoc)
 312 {
 313         struct sock *sk = asoc->base.sk;
 314         struct sctp_transport *transport;
 315         struct list_head *pos, *temp;
 316         int i;
 317 
 318         /* Only real associations count against the endpoint, so
 319          * don't bother for if this is a temporary association.
 320          */
 321         if (!list_empty(&asoc->asocs)) {
 322                 list_del(&asoc->asocs);
 323 
 324                 /* Decrement the backlog value for a TCP-style listening
 325                  * socket.
 326                  */
 327                 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
 328                         sk->sk_ack_backlog--;
 329         }
 330 
 331         /* Mark as dead, so other users can know this structure is
 332          * going away.
 333          */
 334         asoc->base.dead = true;
 335 
 336         /* Dispose of any data lying around in the outqueue. */
 337         sctp_outq_free(&asoc->outqueue);
 338 
 339         /* Dispose of any pending messages for the upper layer. */
 340         sctp_ulpq_free(&asoc->ulpq);
 341 
 342         /* Dispose of any pending chunks on the inqueue. */
 343         sctp_inq_free(&asoc->base.inqueue);
 344 
 345         sctp_tsnmap_free(&asoc->peer.tsn_map);
 346 
 347         /* Free stream information. */
 348         sctp_stream_free(&asoc->stream);
 349 
 350         if (asoc->strreset_chunk)
 351                 sctp_chunk_free(asoc->strreset_chunk);
 352 
 353         /* Clean up the bound address list. */
 354         sctp_bind_addr_free(&asoc->base.bind_addr);
 355 
 356         /* Do we need to go through all of our timers and
 357          * delete them?   To be safe we will try to delete all, but we
 358          * should be able to go through and make a guess based
 359          * on our state.
 360          */
 361         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
 362                 if (del_timer(&asoc->timers[i]))
 363                         sctp_association_put(asoc);
 364         }
 365 
 366         /* Free peer's cached cookie. */
 367         kfree(asoc->peer.cookie);
 368         kfree(asoc->peer.peer_random);
 369         kfree(asoc->peer.peer_chunks);
 370         kfree(asoc->peer.peer_hmacs);
 371 
 372         /* Release the transport structures. */
 373         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
 374                 transport = list_entry(pos, struct sctp_transport, transports);
 375                 list_del_rcu(pos);
 376                 sctp_unhash_transport(transport);
 377                 sctp_transport_free(transport);
 378         }
 379 
 380         asoc->peer.transport_count = 0;
 381 
 382         sctp_asconf_queue_teardown(asoc);
 383 
 384         /* Free pending address space being deleted */
 385         kfree(asoc->asconf_addr_del_pending);
 386 
 387         /* AUTH - Free the endpoint shared keys */
 388         sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
 389 
 390         /* AUTH - Free the association shared key */
 391         sctp_auth_key_put(asoc->asoc_shared_key);
 392 
 393         sctp_association_put(asoc);
 394 }
 395 
 396 /* Cleanup and free up an association. */
 397 static void sctp_association_destroy(struct sctp_association *asoc)
 398 {
 399         if (unlikely(!asoc->base.dead)) {
 400                 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
 401                 return;
 402         }
 403 
 404         sctp_endpoint_put(asoc->ep);
 405         sock_put(asoc->base.sk);
 406 
 407         if (asoc->assoc_id != 0) {
 408                 spin_lock_bh(&sctp_assocs_id_lock);
 409                 idr_remove(&sctp_assocs_id, asoc->assoc_id);
 410                 spin_unlock_bh(&sctp_assocs_id_lock);
 411         }
 412 
 413         WARN_ON(atomic_read(&asoc->rmem_alloc));
 414 
 415         kfree_rcu(asoc, rcu);
 416         SCTP_DBG_OBJCNT_DEC(assoc);
 417 }
 418 
 419 /* Change the primary destination address for the peer. */
 420 void sctp_assoc_set_primary(struct sctp_association *asoc,
 421                             struct sctp_transport *transport)
 422 {
 423         int changeover = 0;
 424 
 425         /* it's a changeover only if we already have a primary path
 426          * that we are changing
 427          */
 428         if (asoc->peer.primary_path != NULL &&
 429             asoc->peer.primary_path != transport)
 430                 changeover = 1 ;
 431 
 432         asoc->peer.primary_path = transport;
 433 
 434         /* Set a default msg_name for events. */
 435         memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
 436                sizeof(union sctp_addr));
 437 
 438         /* If the primary path is changing, assume that the
 439          * user wants to use this new path.
 440          */
 441         if ((transport->state == SCTP_ACTIVE) ||
 442             (transport->state == SCTP_UNKNOWN))
 443                 asoc->peer.active_path = transport;
 444 
 445         /*
 446          * SFR-CACC algorithm:
 447          * Upon the receipt of a request to change the primary
 448          * destination address, on the data structure for the new
 449          * primary destination, the sender MUST do the following:
 450          *
 451          * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
 452          * to this destination address earlier. The sender MUST set
 453          * CYCLING_CHANGEOVER to indicate that this switch is a
 454          * double switch to the same destination address.
 455          *
 456          * Really, only bother is we have data queued or outstanding on
 457          * the association.
 458          */
 459         if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
 460                 return;
 461 
 462         if (transport->cacc.changeover_active)
 463                 transport->cacc.cycling_changeover = changeover;
 464 
 465         /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
 466          * a changeover has occurred.
 467          */
 468         transport->cacc.changeover_active = changeover;
 469 
 470         /* 3) The sender MUST store the next TSN to be sent in
 471          * next_tsn_at_change.
 472          */
 473         transport->cacc.next_tsn_at_change = asoc->next_tsn;
 474 }
 475 
 476 /* Remove a transport from an association.  */
 477 void sctp_assoc_rm_peer(struct sctp_association *asoc,
 478                         struct sctp_transport *peer)
 479 {
 480         struct sctp_transport *transport;
 481         struct list_head *pos;
 482         struct sctp_chunk *ch;
 483 
 484         pr_debug("%s: association:%p addr:%pISpc\n",
 485                  __func__, asoc, &peer->ipaddr.sa);
 486 
 487         /* If we are to remove the current retran_path, update it
 488          * to the next peer before removing this peer from the list.
 489          */
 490         if (asoc->peer.retran_path == peer)
 491                 sctp_assoc_update_retran_path(asoc);
 492 
 493         /* Remove this peer from the list. */
 494         list_del_rcu(&peer->transports);
 495         /* Remove this peer from the transport hashtable */
 496         sctp_unhash_transport(peer);
 497 
 498         /* Get the first transport of asoc. */
 499         pos = asoc->peer.transport_addr_list.next;
 500         transport = list_entry(pos, struct sctp_transport, transports);
 501 
 502         /* Update any entries that match the peer to be deleted. */
 503         if (asoc->peer.primary_path == peer)
 504                 sctp_assoc_set_primary(asoc, transport);
 505         if (asoc->peer.active_path == peer)
 506                 asoc->peer.active_path = transport;
 507         if (asoc->peer.retran_path == peer)
 508                 asoc->peer.retran_path = transport;
 509         if (asoc->peer.last_data_from == peer)
 510                 asoc->peer.last_data_from = transport;
 511 
 512         if (asoc->strreset_chunk &&
 513             asoc->strreset_chunk->transport == peer) {
 514                 asoc->strreset_chunk->transport = transport;
 515                 sctp_transport_reset_reconf_timer(transport);
 516         }
 517 
 518         /* If we remove the transport an INIT was last sent to, set it to
 519          * NULL. Combined with the update of the retran path above, this
 520          * will cause the next INIT to be sent to the next available
 521          * transport, maintaining the cycle.
 522          */
 523         if (asoc->init_last_sent_to == peer)
 524                 asoc->init_last_sent_to = NULL;
 525 
 526         /* If we remove the transport an SHUTDOWN was last sent to, set it
 527          * to NULL. Combined with the update of the retran path above, this
 528          * will cause the next SHUTDOWN to be sent to the next available
 529          * transport, maintaining the cycle.
 530          */
 531         if (asoc->shutdown_last_sent_to == peer)
 532                 asoc->shutdown_last_sent_to = NULL;
 533 
 534         /* If we remove the transport an ASCONF was last sent to, set it to
 535          * NULL.
 536          */
 537         if (asoc->addip_last_asconf &&
 538             asoc->addip_last_asconf->transport == peer)
 539                 asoc->addip_last_asconf->transport = NULL;
 540 
 541         /* If we have something on the transmitted list, we have to
 542          * save it off.  The best place is the active path.
 543          */
 544         if (!list_empty(&peer->transmitted)) {
 545                 struct sctp_transport *active = asoc->peer.active_path;
 546 
 547                 /* Reset the transport of each chunk on this list */
 548                 list_for_each_entry(ch, &peer->transmitted,
 549                                         transmitted_list) {
 550                         ch->transport = NULL;
 551                         ch->rtt_in_progress = 0;
 552                 }
 553 
 554                 list_splice_tail_init(&peer->transmitted,
 555                                         &active->transmitted);
 556 
 557                 /* Start a T3 timer here in case it wasn't running so
 558                  * that these migrated packets have a chance to get
 559                  * retransmitted.
 560                  */
 561                 if (!timer_pending(&active->T3_rtx_timer))
 562                         if (!mod_timer(&active->T3_rtx_timer,
 563                                         jiffies + active->rto))
 564                                 sctp_transport_hold(active);
 565         }
 566 
 567         list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list)
 568                 if (ch->transport == peer)
 569                         ch->transport = NULL;
 570 
 571         asoc->peer.transport_count--;
 572 
 573         sctp_transport_free(peer);
 574 }
 575 
 576 /* Add a transport address to an association.  */
 577 struct 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         if (addr->sa.sa_family == AF_INET6) {
 636                 __be32 info = addr->v6.sin6_flowinfo;
 637 
 638                 if (info) {
 639                         peer->flowlabel = ntohl(info & IPV6_FLOWLABEL_MASK);
 640                         peer->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
 641                 } else {
 642                         peer->flowlabel = asoc->flowlabel;
 643                 }
 644         }
 645         peer->dscp = asoc->dscp;
 646 
 647         /* Enable/disable heartbeat, SACK delay, and path MTU discovery
 648          * based on association setting.
 649          */
 650         peer->param_flags = asoc->param_flags;
 651 
 652         /* Initialize the pmtu of the transport. */
 653         sctp_transport_route(peer, NULL, sp);
 654 
 655         /* If this is the first transport addr on this association,
 656          * initialize the association PMTU to the peer's PMTU.
 657          * If not and the current association PMTU is higher than the new
 658          * peer's PMTU, reset the association PMTU to the new peer's PMTU.
 659          */
 660         sctp_assoc_set_pmtu(asoc, asoc->pathmtu ?
 661                                   min_t(int, peer->pathmtu, asoc->pathmtu) :
 662                                   peer->pathmtu);
 663 
 664         peer->pmtu_pending = 0;
 665 
 666         /* The asoc->peer.port might not be meaningful yet, but
 667          * initialize the packet structure anyway.
 668          */
 669         sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
 670                          asoc->peer.port);
 671 
 672         /* 7.2.1 Slow-Start
 673          *
 674          * o The initial cwnd before DATA transmission or after a sufficiently
 675          *   long idle period MUST be set to
 676          *      min(4*MTU, max(2*MTU, 4380 bytes))
 677          *
 678          * o The initial value of ssthresh MAY be arbitrarily high
 679          *   (for example, implementations MAY use the size of the
 680          *   receiver advertised window).
 681          */
 682         peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
 683 
 684         /* At this point, we may not have the receiver's advertised window,
 685          * so initialize ssthresh to the default value and it will be set
 686          * later when we process the INIT.
 687          */
 688         peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
 689 
 690         peer->partial_bytes_acked = 0;
 691         peer->flight_size = 0;
 692         peer->burst_limited = 0;
 693 
 694         /* Set the transport's RTO.initial value */
 695         peer->rto = asoc->rto_initial;
 696         sctp_max_rto(asoc, peer);
 697 
 698         /* Set the peer's active state. */
 699         peer->state = peer_state;
 700 
 701         /* Add this peer into the transport hashtable */
 702         if (sctp_hash_transport(peer)) {
 703                 sctp_transport_free(peer);
 704                 return NULL;
 705         }
 706 
 707         /* Attach the remote transport to our asoc.  */
 708         list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
 709         asoc->peer.transport_count++;
 710 
 711         /* If we do not yet have a primary path, set one.  */
 712         if (!asoc->peer.primary_path) {
 713                 sctp_assoc_set_primary(asoc, peer);
 714                 asoc->peer.retran_path = peer;
 715         }
 716 
 717         if (asoc->peer.active_path == asoc->peer.retran_path &&
 718             peer->state != SCTP_UNCONFIRMED) {
 719                 asoc->peer.retran_path = peer;
 720         }
 721 
 722         return peer;
 723 }
 724 
 725 /* Delete a transport address from an association.  */
 726 void sctp_assoc_del_peer(struct sctp_association *asoc,
 727                          const union sctp_addr *addr)
 728 {
 729         struct list_head        *pos;
 730         struct list_head        *temp;
 731         struct sctp_transport   *transport;
 732 
 733         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
 734                 transport = list_entry(pos, struct sctp_transport, transports);
 735                 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
 736                         /* Do book keeping for removing the peer and free it. */
 737                         sctp_assoc_rm_peer(asoc, transport);
 738                         break;
 739                 }
 740         }
 741 }
 742 
 743 /* Lookup a transport by address. */
 744 struct sctp_transport *sctp_assoc_lookup_paddr(
 745                                         const struct sctp_association *asoc,
 746                                         const union sctp_addr *address)
 747 {
 748         struct sctp_transport *t;
 749 
 750         /* Cycle through all transports searching for a peer address. */
 751 
 752         list_for_each_entry(t, &asoc->peer.transport_addr_list,
 753                         transports) {
 754                 if (sctp_cmp_addr_exact(address, &t->ipaddr))
 755                         return t;
 756         }
 757 
 758         return NULL;
 759 }
 760 
 761 /* Remove all transports except a give one */
 762 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
 763                                      struct sctp_transport *primary)
 764 {
 765         struct sctp_transport   *temp;
 766         struct sctp_transport   *t;
 767 
 768         list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
 769                                  transports) {
 770                 /* if the current transport is not the primary one, delete it */
 771                 if (t != primary)
 772                         sctp_assoc_rm_peer(asoc, t);
 773         }
 774 }
 775 
 776 /* Engage in transport control operations.
 777  * Mark the transport up or down and send a notification to the user.
 778  * Select and update the new active and retran paths.
 779  */
 780 void sctp_assoc_control_transport(struct sctp_association *asoc,
 781                                   struct sctp_transport *transport,
 782                                   enum sctp_transport_cmd command,
 783                                   sctp_sn_error_t error)
 784 {
 785         struct sctp_ulpevent *event;
 786         struct sockaddr_storage addr;
 787         int spc_state = 0;
 788         bool ulp_notify = true;
 789 
 790         /* Record the transition on the transport.  */
 791         switch (command) {
 792         case SCTP_TRANSPORT_UP:
 793                 /* If we are moving from UNCONFIRMED state due
 794                  * to heartbeat success, report the SCTP_ADDR_CONFIRMED
 795                  * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
 796                  */
 797                 if (SCTP_UNCONFIRMED == transport->state &&
 798                     SCTP_HEARTBEAT_SUCCESS == error)
 799                         spc_state = SCTP_ADDR_CONFIRMED;
 800                 else
 801                         spc_state = SCTP_ADDR_AVAILABLE;
 802                 /* Don't inform ULP about transition from PF to
 803                  * active state and set cwnd to 1 MTU, see SCTP
 804                  * Quick failover draft section 5.1, point 5
 805                  */
 806                 if (transport->state == SCTP_PF) {
 807                         ulp_notify = false;
 808                         transport->cwnd = asoc->pathmtu;
 809                 }
 810                 transport->state = SCTP_ACTIVE;
 811                 break;
 812 
 813         case SCTP_TRANSPORT_DOWN:
 814                 /* If the transport was never confirmed, do not transition it
 815                  * to inactive state.  Also, release the cached route since
 816                  * there may be a better route next time.
 817                  */
 818                 if (transport->state != SCTP_UNCONFIRMED)
 819                         transport->state = SCTP_INACTIVE;
 820                 else {
 821                         sctp_transport_dst_release(transport);
 822                         ulp_notify = false;
 823                 }
 824 
 825                 spc_state = SCTP_ADDR_UNREACHABLE;
 826                 break;
 827 
 828         case SCTP_TRANSPORT_PF:
 829                 transport->state = SCTP_PF;
 830                 ulp_notify = false;
 831                 break;
 832 
 833         default:
 834                 return;
 835         }
 836 
 837         /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
 838          * to the user.
 839          */
 840         if (ulp_notify) {
 841                 memset(&addr, 0, sizeof(struct sockaddr_storage));
 842                 memcpy(&addr, &transport->ipaddr,
 843                        transport->af_specific->sockaddr_len);
 844 
 845                 event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
 846                                         0, spc_state, error, GFP_ATOMIC);
 847                 if (event)
 848                         asoc->stream.si->enqueue_event(&asoc->ulpq, event);
 849         }
 850 
 851         /* Select new active and retran paths. */
 852         sctp_select_active_and_retran_path(asoc);
 853 }
 854 
 855 /* Hold a reference to an association. */
 856 void sctp_association_hold(struct sctp_association *asoc)
 857 {
 858         refcount_inc(&asoc->base.refcnt);
 859 }
 860 
 861 /* Release a reference to an association and cleanup
 862  * if there are no more references.
 863  */
 864 void sctp_association_put(struct sctp_association *asoc)
 865 {
 866         if (refcount_dec_and_test(&asoc->base.refcnt))
 867                 sctp_association_destroy(asoc);
 868 }
 869 
 870 /* Allocate the next TSN, Transmission Sequence Number, for the given
 871  * association.
 872  */
 873 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
 874 {
 875         /* From Section 1.6 Serial Number Arithmetic:
 876          * Transmission Sequence Numbers wrap around when they reach
 877          * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
 878          * after transmitting TSN = 2*32 - 1 is TSN = 0.
 879          */
 880         __u32 retval = asoc->next_tsn;
 881         asoc->next_tsn++;
 882         asoc->unack_data++;
 883 
 884         return retval;
 885 }
 886 
 887 /* Compare two addresses to see if they match.  Wildcard addresses
 888  * only match themselves.
 889  */
 890 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
 891                         const union sctp_addr *ss2)
 892 {
 893         struct sctp_af *af;
 894 
 895         af = sctp_get_af_specific(ss1->sa.sa_family);
 896         if (unlikely(!af))
 897                 return 0;
 898 
 899         return af->cmp_addr(ss1, ss2);
 900 }
 901 
 902 /* Return an ecne chunk to get prepended to a packet.
 903  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
 904  * No we don't, but we could/should.
 905  */
 906 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
 907 {
 908         if (!asoc->need_ecne)
 909                 return NULL;
 910 
 911         /* Send ECNE if needed.
 912          * Not being able to allocate a chunk here is not deadly.
 913          */
 914         return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
 915 }
 916 
 917 /*
 918  * Find which transport this TSN was sent on.
 919  */
 920 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
 921                                              __u32 tsn)
 922 {
 923         struct sctp_transport *active;
 924         struct sctp_transport *match;
 925         struct sctp_transport *transport;
 926         struct sctp_chunk *chunk;
 927         __be32 key = htonl(tsn);
 928 
 929         match = NULL;
 930 
 931         /*
 932          * FIXME: In general, find a more efficient data structure for
 933          * searching.
 934          */
 935 
 936         /*
 937          * The general strategy is to search each transport's transmitted
 938          * list.   Return which transport this TSN lives on.
 939          *
 940          * Let's be hopeful and check the active_path first.
 941          * Another optimization would be to know if there is only one
 942          * outbound path and not have to look for the TSN at all.
 943          *
 944          */
 945 
 946         active = asoc->peer.active_path;
 947 
 948         list_for_each_entry(chunk, &active->transmitted,
 949                         transmitted_list) {
 950 
 951                 if (key == chunk->subh.data_hdr->tsn) {
 952                         match = active;
 953                         goto out;
 954                 }
 955         }
 956 
 957         /* If not found, go search all the other transports. */
 958         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
 959                         transports) {
 960 
 961                 if (transport == active)
 962                         continue;
 963                 list_for_each_entry(chunk, &transport->transmitted,
 964                                 transmitted_list) {
 965                         if (key == chunk->subh.data_hdr->tsn) {
 966                                 match = transport;
 967                                 goto out;
 968                         }
 969                 }
 970         }
 971 out:
 972         return match;
 973 }
 974 
 975 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
 976 static void sctp_assoc_bh_rcv(struct work_struct *work)
 977 {
 978         struct sctp_association *asoc =
 979                 container_of(work, struct sctp_association,
 980                              base.inqueue.immediate);
 981         struct net *net = sock_net(asoc->base.sk);
 982         union sctp_subtype subtype;
 983         struct sctp_endpoint *ep;
 984         struct sctp_chunk *chunk;
 985         struct sctp_inq *inqueue;
 986         int first_time = 1;     /* is this the first time through the loop */
 987         int error = 0;
 988         int state;
 989 
 990         /* The association should be held so we should be safe. */
 991         ep = asoc->ep;
 992 
 993         inqueue = &asoc->base.inqueue;
 994         sctp_association_hold(asoc);
 995         while (NULL != (chunk = sctp_inq_pop(inqueue))) {
 996                 state = asoc->state;
 997                 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
 998 
 999                 /* If the first chunk in the packet is AUTH, do special
1000                  * processing specified in Section 6.3 of SCTP-AUTH spec
1001                  */
1002                 if (first_time && subtype.chunk == SCTP_CID_AUTH) {
1003                         struct sctp_chunkhdr *next_hdr;
1004 
1005                         next_hdr = sctp_inq_peek(inqueue);
1006                         if (!next_hdr)
1007                                 goto normal;
1008 
1009                         /* If the next chunk is COOKIE-ECHO, skip the AUTH
1010                          * chunk while saving a pointer to it so we can do
1011                          * Authentication later (during cookie-echo
1012                          * processing).
1013                          */
1014                         if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
1015                                 chunk->auth_chunk = skb_clone(chunk->skb,
1016                                                               GFP_ATOMIC);
1017                                 chunk->auth = 1;
1018                                 continue;
1019                         }
1020                 }
1021 
1022 normal:
1023                 /* SCTP-AUTH, Section 6.3:
1024                  *    The receiver has a list of chunk types which it expects
1025                  *    to be received only after an AUTH-chunk.  This list has
1026                  *    been sent to the peer during the association setup.  It
1027                  *    MUST silently discard these chunks if they are not placed
1028                  *    after an AUTH chunk in the packet.
1029                  */
1030                 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1031                         continue;
1032 
1033                 /* Remember where the last DATA chunk came from so we
1034                  * know where to send the SACK.
1035                  */
1036                 if (sctp_chunk_is_data(chunk))
1037                         asoc->peer.last_data_from = chunk->transport;
1038                 else {
1039                         SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1040                         asoc->stats.ictrlchunks++;
1041                         if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1042                                 asoc->stats.isacks++;
1043                 }
1044 
1045                 if (chunk->transport)
1046                         chunk->transport->last_time_heard = ktime_get();
1047 
1048                 /* Run through the state machine. */
1049                 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1050                                    state, ep, asoc, chunk, GFP_ATOMIC);
1051 
1052                 /* Check to see if the association is freed in response to
1053                  * the incoming chunk.  If so, get out of the while loop.
1054                  */
1055                 if (asoc->base.dead)
1056                         break;
1057 
1058                 /* If there is an error on chunk, discard this packet. */
1059                 if (error && chunk)
1060                         chunk->pdiscard = 1;
1061 
1062                 if (first_time)
1063                         first_time = 0;
1064         }
1065         sctp_association_put(asoc);
1066 }
1067 
1068 /* This routine moves an association from its old sk to a new sk.  */
1069 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1070 {
1071         struct sctp_sock *newsp = sctp_sk(newsk);
1072         struct sock *oldsk = assoc->base.sk;
1073 
1074         /* Delete the association from the old endpoint's list of
1075          * associations.
1076          */
1077         list_del_init(&assoc->asocs);
1078 
1079         /* Decrement the backlog value for a TCP-style socket. */
1080         if (sctp_style(oldsk, TCP))
1081                 oldsk->sk_ack_backlog--;
1082 
1083         /* Release references to the old endpoint and the sock.  */
1084         sctp_endpoint_put(assoc->ep);
1085         sock_put(assoc->base.sk);
1086 
1087         /* Get a reference to the new endpoint.  */
1088         assoc->ep = newsp->ep;
1089         sctp_endpoint_hold(assoc->ep);
1090 
1091         /* Get a reference to the new sock.  */
1092         assoc->base.sk = newsk;
1093         sock_hold(assoc->base.sk);
1094 
1095         /* Add the association to the new endpoint's list of associations.  */
1096         sctp_endpoint_add_asoc(newsp->ep, assoc);
1097 }
1098 
1099 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1100 int sctp_assoc_update(struct sctp_association *asoc,
1101                       struct sctp_association *new)
1102 {
1103         struct sctp_transport *trans;
1104         struct list_head *pos, *temp;
1105 
1106         /* Copy in new parameters of peer. */
1107         asoc->c = new->c;
1108         asoc->peer.rwnd = new->peer.rwnd;
1109         asoc->peer.sack_needed = new->peer.sack_needed;
1110         asoc->peer.auth_capable = new->peer.auth_capable;
1111         asoc->peer.i = new->peer.i;
1112 
1113         if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1114                               asoc->peer.i.initial_tsn, GFP_ATOMIC))
1115                 return -ENOMEM;
1116 
1117         /* Remove any peer addresses not present in the new association. */
1118         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1119                 trans = list_entry(pos, struct sctp_transport, transports);
1120                 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1121                         sctp_assoc_rm_peer(asoc, trans);
1122                         continue;
1123                 }
1124 
1125                 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1126                         sctp_transport_reset(trans);
1127         }
1128 
1129         /* If the case is A (association restart), use
1130          * initial_tsn as next_tsn. If the case is B, use
1131          * current next_tsn in case data sent to peer
1132          * has been discarded and needs retransmission.
1133          */
1134         if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1135                 asoc->next_tsn = new->next_tsn;
1136                 asoc->ctsn_ack_point = new->ctsn_ack_point;
1137                 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1138 
1139                 /* Reinitialize SSN for both local streams
1140                  * and peer's streams.
1141                  */
1142                 sctp_stream_clear(&asoc->stream);
1143 
1144                 /* Flush the ULP reassembly and ordered queue.
1145                  * Any data there will now be stale and will
1146                  * cause problems.
1147                  */
1148                 sctp_ulpq_flush(&asoc->ulpq);
1149 
1150                 /* reset the overall association error count so
1151                  * that the restarted association doesn't get torn
1152                  * down on the next retransmission timer.
1153                  */
1154                 asoc->overall_error_count = 0;
1155 
1156         } else {
1157                 /* Add any peer addresses from the new association. */
1158                 list_for_each_entry(trans, &new->peer.transport_addr_list,
1159                                     transports)
1160                         if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr) &&
1161                             !sctp_assoc_add_peer(asoc, &trans->ipaddr,
1162                                                  GFP_ATOMIC, trans->state))
1163                                 return -ENOMEM;
1164 
1165                 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1166                 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1167 
1168                 if (sctp_state(asoc, COOKIE_WAIT))
1169                         sctp_stream_update(&asoc->stream, &new->stream);
1170 
1171                 /* get a new assoc id if we don't have one yet. */
1172                 if (sctp_assoc_set_id(asoc, GFP_ATOMIC))
1173                         return -ENOMEM;
1174         }
1175 
1176         /* SCTP-AUTH: Save the peer parameters from the new associations
1177          * and also move the association shared keys over
1178          */
1179         kfree(asoc->peer.peer_random);
1180         asoc->peer.peer_random = new->peer.peer_random;
1181         new->peer.peer_random = NULL;
1182 
1183         kfree(asoc->peer.peer_chunks);
1184         asoc->peer.peer_chunks = new->peer.peer_chunks;
1185         new->peer.peer_chunks = NULL;
1186 
1187         kfree(asoc->peer.peer_hmacs);
1188         asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1189         new->peer.peer_hmacs = NULL;
1190 
1191         return sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1192 }
1193 
1194 /* Update the retran path for sending a retransmitted packet.
1195  * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1196  *
1197  *   When there is outbound data to send and the primary path
1198  *   becomes inactive (e.g., due to failures), or where the
1199  *   SCTP user explicitly requests to send data to an
1200  *   inactive destination transport address, before reporting
1201  *   an error to its ULP, the SCTP endpoint should try to send
1202  *   the data to an alternate active destination transport
1203  *   address if one exists.
1204  *
1205  *   When retransmitting data that timed out, if the endpoint
1206  *   is multihomed, it should consider each source-destination
1207  *   address pair in its retransmission selection policy.
1208  *   When retransmitting timed-out data, the endpoint should
1209  *   attempt to pick the most divergent source-destination
1210  *   pair from the original source-destination pair to which
1211  *   the packet was transmitted.
1212  *
1213  *   Note: Rules for picking the most divergent source-destination
1214  *   pair are an implementation decision and are not specified
1215  *   within this document.
1216  *
1217  * Our basic strategy is to round-robin transports in priorities
1218  * according to sctp_trans_score() e.g., if no such
1219  * transport with state SCTP_ACTIVE exists, round-robin through
1220  * SCTP_UNKNOWN, etc. You get the picture.
1221  */
1222 static u8 sctp_trans_score(const struct sctp_transport *trans)
1223 {
1224         switch (trans->state) {
1225         case SCTP_ACTIVE:
1226                 return 3;       /* best case */
1227         case SCTP_UNKNOWN:
1228                 return 2;
1229         case SCTP_PF:
1230                 return 1;
1231         default: /* case SCTP_INACTIVE */
1232                 return 0;       /* worst case */
1233         }
1234 }
1235 
1236 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1237                                                    struct sctp_transport *trans2)
1238 {
1239         if (trans1->error_count > trans2->error_count) {
1240                 return trans2;
1241         } else if (trans1->error_count == trans2->error_count &&
1242                    ktime_after(trans2->last_time_heard,
1243                                trans1->last_time_heard)) {
1244                 return trans2;
1245         } else {
1246                 return trans1;
1247         }
1248 }
1249 
1250 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1251                                                     struct sctp_transport *best)
1252 {
1253         u8 score_curr, score_best;
1254 
1255         if (best == NULL || curr == best)
1256                 return curr;
1257 
1258         score_curr = sctp_trans_score(curr);
1259         score_best = sctp_trans_score(best);
1260 
1261         /* First, try a score-based selection if both transport states
1262          * differ. If we're in a tie, lets try to make a more clever
1263          * decision here based on error counts and last time heard.
1264          */
1265         if (score_curr > score_best)
1266                 return curr;
1267         else if (score_curr == score_best)
1268                 return sctp_trans_elect_tie(best, curr);
1269         else
1270                 return best;
1271 }
1272 
1273 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1274 {
1275         struct sctp_transport *trans = asoc->peer.retran_path;
1276         struct sctp_transport *trans_next = NULL;
1277 
1278         /* We're done as we only have the one and only path. */
1279         if (asoc->peer.transport_count == 1)
1280                 return;
1281         /* If active_path and retran_path are the same and active,
1282          * then this is the only active path. Use it.
1283          */
1284         if (asoc->peer.active_path == asoc->peer.retran_path &&
1285             asoc->peer.active_path->state == SCTP_ACTIVE)
1286                 return;
1287 
1288         /* Iterate from retran_path's successor back to retran_path. */
1289         for (trans = list_next_entry(trans, transports); 1;
1290              trans = list_next_entry(trans, transports)) {
1291                 /* Manually skip the head element. */
1292                 if (&trans->transports == &asoc->peer.transport_addr_list)
1293                         continue;
1294                 if (trans->state == SCTP_UNCONFIRMED)
1295                         continue;
1296                 trans_next = sctp_trans_elect_best(trans, trans_next);
1297                 /* Active is good enough for immediate return. */
1298                 if (trans_next->state == SCTP_ACTIVE)
1299                         break;
1300                 /* We've reached the end, time to update path. */
1301                 if (trans == asoc->peer.retran_path)
1302                         break;
1303         }
1304 
1305         asoc->peer.retran_path = trans_next;
1306 
1307         pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1308                  __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1309 }
1310 
1311 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1312 {
1313         struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1314         struct sctp_transport *trans_pf = NULL;
1315 
1316         /* Look for the two most recently used active transports. */
1317         list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1318                             transports) {
1319                 /* Skip uninteresting transports. */
1320                 if (trans->state == SCTP_INACTIVE ||
1321                     trans->state == SCTP_UNCONFIRMED)
1322                         continue;
1323                 /* Keep track of the best PF transport from our
1324                  * list in case we don't find an active one.
1325                  */
1326                 if (trans->state == SCTP_PF) {
1327                         trans_pf = sctp_trans_elect_best(trans, trans_pf);
1328                         continue;
1329                 }
1330                 /* For active transports, pick the most recent ones. */
1331                 if (trans_pri == NULL ||
1332                     ktime_after(trans->last_time_heard,
1333                                 trans_pri->last_time_heard)) {
1334                         trans_sec = trans_pri;
1335                         trans_pri = trans;
1336                 } else if (trans_sec == NULL ||
1337                            ktime_after(trans->last_time_heard,
1338                                        trans_sec->last_time_heard)) {
1339                         trans_sec = trans;
1340                 }
1341         }
1342 
1343         /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1344          *
1345          * By default, an endpoint should always transmit to the primary
1346          * path, unless the SCTP user explicitly specifies the
1347          * destination transport address (and possibly source transport
1348          * address) to use. [If the primary is active but not most recent,
1349          * bump the most recently used transport.]
1350          */
1351         if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1352              asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1353              asoc->peer.primary_path != trans_pri) {
1354                 trans_sec = trans_pri;
1355                 trans_pri = asoc->peer.primary_path;
1356         }
1357 
1358         /* We did not find anything useful for a possible retransmission
1359          * path; either primary path that we found is the the same as
1360          * the current one, or we didn't generally find an active one.
1361          */
1362         if (trans_sec == NULL)
1363                 trans_sec = trans_pri;
1364 
1365         /* If we failed to find a usable transport, just camp on the
1366          * active or pick a PF iff it's the better choice.
1367          */
1368         if (trans_pri == NULL) {
1369                 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1370                 trans_sec = trans_pri;
1371         }
1372 
1373         /* Set the active and retran transports. */
1374         asoc->peer.active_path = trans_pri;
1375         asoc->peer.retran_path = trans_sec;
1376 }
1377 
1378 struct sctp_transport *
1379 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1380                                   struct sctp_transport *last_sent_to)
1381 {
1382         /* If this is the first time packet is sent, use the active path,
1383          * else use the retran path. If the last packet was sent over the
1384          * retran path, update the retran path and use it.
1385          */
1386         if (last_sent_to == NULL) {
1387                 return asoc->peer.active_path;
1388         } else {
1389                 if (last_sent_to == asoc->peer.retran_path)
1390                         sctp_assoc_update_retran_path(asoc);
1391 
1392                 return asoc->peer.retran_path;
1393         }
1394 }
1395 
1396 void sctp_assoc_update_frag_point(struct sctp_association *asoc)
1397 {
1398         int frag = sctp_mtu_payload(sctp_sk(asoc->base.sk), asoc->pathmtu,
1399                                     sctp_datachk_len(&asoc->stream));
1400 
1401         if (asoc->user_frag)
1402                 frag = min_t(int, frag, asoc->user_frag);
1403 
1404         frag = min_t(int, frag, SCTP_MAX_CHUNK_LEN -
1405                                 sctp_datachk_len(&asoc->stream));
1406 
1407         asoc->frag_point = SCTP_TRUNC4(frag);
1408 }
1409 
1410 void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu)
1411 {
1412         if (asoc->pathmtu != pmtu) {
1413                 asoc->pathmtu = pmtu;
1414                 sctp_assoc_update_frag_point(asoc);
1415         }
1416 
1417         pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1418                  asoc->pathmtu, asoc->frag_point);
1419 }
1420 
1421 /* Update the association's pmtu and frag_point by going through all the
1422  * transports. This routine is called when a transport's PMTU has changed.
1423  */
1424 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
1425 {
1426         struct sctp_transport *t;
1427         __u32 pmtu = 0;
1428 
1429         if (!asoc)
1430                 return;
1431 
1432         /* Get the lowest pmtu of all the transports. */
1433         list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
1434                 if (t->pmtu_pending && t->dst) {
1435                         sctp_transport_update_pmtu(t,
1436                                                    atomic_read(&t->mtu_info));
1437                         t->pmtu_pending = 0;
1438                 }
1439                 if (!pmtu || (t->pathmtu < pmtu))
1440                         pmtu = t->pathmtu;
1441         }
1442 
1443         sctp_assoc_set_pmtu(asoc, pmtu);
1444 }
1445 
1446 /* Should we send a SACK to update our peer? */
1447 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1448 {
1449         struct net *net = sock_net(asoc->base.sk);
1450         switch (asoc->state) {
1451         case SCTP_STATE_ESTABLISHED:
1452         case SCTP_STATE_SHUTDOWN_PENDING:
1453         case SCTP_STATE_SHUTDOWN_RECEIVED:
1454         case SCTP_STATE_SHUTDOWN_SENT:
1455                 if ((asoc->rwnd > asoc->a_rwnd) &&
1456                     ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1457                            (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1458                            asoc->pathmtu)))
1459                         return true;
1460                 break;
1461         default:
1462                 break;
1463         }
1464         return false;
1465 }
1466 
1467 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1468 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1469 {
1470         struct sctp_chunk *sack;
1471         struct timer_list *timer;
1472 
1473         if (asoc->rwnd_over) {
1474                 if (asoc->rwnd_over >= len) {
1475                         asoc->rwnd_over -= len;
1476                 } else {
1477                         asoc->rwnd += (len - asoc->rwnd_over);
1478                         asoc->rwnd_over = 0;
1479                 }
1480         } else {
1481                 asoc->rwnd += len;
1482         }
1483 
1484         /* If we had window pressure, start recovering it
1485          * once our rwnd had reached the accumulated pressure
1486          * threshold.  The idea is to recover slowly, but up
1487          * to the initial advertised window.
1488          */
1489         if (asoc->rwnd_press) {
1490                 int change = min(asoc->pathmtu, asoc->rwnd_press);
1491                 asoc->rwnd += change;
1492                 asoc->rwnd_press -= change;
1493         }
1494 
1495         pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1496                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1497                  asoc->a_rwnd);
1498 
1499         /* Send a window update SACK if the rwnd has increased by at least the
1500          * minimum of the association's PMTU and half of the receive buffer.
1501          * The algorithm used is similar to the one described in
1502          * Section 4.2.3.3 of RFC 1122.
1503          */
1504         if (sctp_peer_needs_update(asoc)) {
1505                 asoc->a_rwnd = asoc->rwnd;
1506 
1507                 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1508                          "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1509                          asoc->a_rwnd);
1510 
1511                 sack = sctp_make_sack(asoc);
1512                 if (!sack)
1513                         return;
1514 
1515                 asoc->peer.sack_needed = 0;
1516 
1517                 sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
1518 
1519                 /* Stop the SACK timer.  */
1520                 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1521                 if (del_timer(timer))
1522                         sctp_association_put(asoc);
1523         }
1524 }
1525 
1526 /* Decrease asoc's rwnd by len. */
1527 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1528 {
1529         int rx_count;
1530         int over = 0;
1531 
1532         if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1533                 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1534                          "asoc->rwnd_over:%u!\n", __func__, asoc,
1535                          asoc->rwnd, asoc->rwnd_over);
1536 
1537         if (asoc->ep->rcvbuf_policy)
1538                 rx_count = atomic_read(&asoc->rmem_alloc);
1539         else
1540                 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1541 
1542         /* If we've reached or overflowed our receive buffer, announce
1543          * a 0 rwnd if rwnd would still be positive.  Store the
1544          * the potential pressure overflow so that the window can be restored
1545          * back to original value.
1546          */
1547         if (rx_count >= asoc->base.sk->sk_rcvbuf)
1548                 over = 1;
1549 
1550         if (asoc->rwnd >= len) {
1551                 asoc->rwnd -= len;
1552                 if (over) {
1553                         asoc->rwnd_press += asoc->rwnd;
1554                         asoc->rwnd = 0;
1555                 }
1556         } else {
1557                 asoc->rwnd_over += len - asoc->rwnd;
1558                 asoc->rwnd = 0;
1559         }
1560 
1561         pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1562                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1563                  asoc->rwnd_press);
1564 }
1565 
1566 /* Build the bind address list for the association based on info from the
1567  * local endpoint and the remote peer.
1568  */
1569 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1570                                      enum sctp_scope scope, gfp_t gfp)
1571 {
1572         int flags;
1573 
1574         /* Use scoping rules to determine the subset of addresses from
1575          * the endpoint.
1576          */
1577         flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1578         if (asoc->peer.ipv4_address)
1579                 flags |= SCTP_ADDR4_PEERSUPP;
1580         if (asoc->peer.ipv6_address)
1581                 flags |= SCTP_ADDR6_PEERSUPP;
1582 
1583         return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1584                                    &asoc->base.bind_addr,
1585                                    &asoc->ep->base.bind_addr,
1586                                    scope, gfp, flags);
1587 }
1588 
1589 /* Build the association's bind address list from the cookie.  */
1590 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1591                                          struct sctp_cookie *cookie,
1592                                          gfp_t gfp)
1593 {
1594         int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1595         int var_size3 = cookie->raw_addr_list_len;
1596         __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1597 
1598         return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1599                                       asoc->ep->base.bind_addr.port, gfp);
1600 }
1601 
1602 /* Lookup laddr in the bind address list of an association. */
1603 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1604                             const union sctp_addr *laddr)
1605 {
1606         int found = 0;
1607 
1608         if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1609             sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1610                                  sctp_sk(asoc->base.sk)))
1611                 found = 1;
1612 
1613         return found;
1614 }
1615 
1616 /* Set an association id for a given association */
1617 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1618 {
1619         bool preload = gfpflags_allow_blocking(gfp);
1620         int ret;
1621 
1622         /* If the id is already assigned, keep it. */
1623         if (asoc->assoc_id)
1624                 return 0;
1625 
1626         if (preload)
1627                 idr_preload(gfp);
1628         spin_lock_bh(&sctp_assocs_id_lock);
1629         /* 0, 1, 2 are used as SCTP_FUTURE_ASSOC, SCTP_CURRENT_ASSOC and
1630          * SCTP_ALL_ASSOC, so an available id must be > SCTP_ALL_ASSOC.
1631          */
1632         ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, SCTP_ALL_ASSOC + 1, 0,
1633                                GFP_NOWAIT);
1634         spin_unlock_bh(&sctp_assocs_id_lock);
1635         if (preload)
1636                 idr_preload_end();
1637         if (ret < 0)
1638                 return ret;
1639 
1640         asoc->assoc_id = (sctp_assoc_t)ret;
1641         return 0;
1642 }
1643 
1644 /* Free the ASCONF queue */
1645 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1646 {
1647         struct sctp_chunk *asconf;
1648         struct sctp_chunk *tmp;
1649 
1650         list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1651                 list_del_init(&asconf->list);
1652                 sctp_chunk_free(asconf);
1653         }
1654 }
1655 
1656 /* Free asconf_ack cache */
1657 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1658 {
1659         struct sctp_chunk *ack;
1660         struct sctp_chunk *tmp;
1661 
1662         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1663                                 transmitted_list) {
1664                 list_del_init(&ack->transmitted_list);
1665                 sctp_chunk_free(ack);
1666         }
1667 }
1668 
1669 /* Clean up the ASCONF_ACK queue */
1670 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1671 {
1672         struct sctp_chunk *ack;
1673         struct sctp_chunk *tmp;
1674 
1675         /* We can remove all the entries from the queue up to
1676          * the "Peer-Sequence-Number".
1677          */
1678         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1679                                 transmitted_list) {
1680                 if (ack->subh.addip_hdr->serial ==
1681                                 htonl(asoc->peer.addip_serial))
1682                         break;
1683 
1684                 list_del_init(&ack->transmitted_list);
1685                 sctp_chunk_free(ack);
1686         }
1687 }
1688 
1689 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1690 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1691                                         const struct sctp_association *asoc,
1692                                         __be32 serial)
1693 {
1694         struct sctp_chunk *ack;
1695 
1696         /* Walk through the list of cached ASCONF-ACKs and find the
1697          * ack chunk whose serial number matches that of the request.
1698          */
1699         list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1700                 if (sctp_chunk_pending(ack))
1701                         continue;
1702                 if (ack->subh.addip_hdr->serial == serial) {
1703                         sctp_chunk_hold(ack);
1704                         return ack;
1705                 }
1706         }
1707 
1708         return NULL;
1709 }
1710 
1711 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1712 {
1713         /* Free any cached ASCONF_ACK chunk. */
1714         sctp_assoc_free_asconf_acks(asoc);
1715 
1716         /* Free the ASCONF queue. */
1717         sctp_assoc_free_asconf_queue(asoc);
1718 
1719         /* Free any cached ASCONF chunk. */
1720         if (asoc->addip_last_asconf)
1721                 sctp_chunk_free(asoc->addip_last_asconf);
1722 }
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root/net/sctp/associola.c

DEFINITIONS
