net/sctp/output.c

   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  *
   6  * This file is part of the SCTP kernel implementation
   7  *
   8  * These functions handle output processing.
   9  *
  10  * This SCTP implementation is free software;
  11  * you can redistribute it and/or modify it under the terms of
  12  * the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * This SCTP implementation is distributed in the hope that it
  17  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  18  *                 ************************
  19  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  20  * See the GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with GNU CC; see the file COPYING.  If not, see
  24  * <http://www.gnu.org/licenses/>.
  25  *
  26  * Please send any bug reports or fixes you make to the
  27  * email address(es):
  28  *    lksctp developers <[email protected]>
  29  *
  30  * Written or modified by:
  31  *    La Monte H.P. Yarroll <[email protected]>
  32  *    Karl Knutson          <[email protected]>
  33  *    Jon Grimm             <[email protected]>
  34  *    Sridhar Samudrala     <[email protected]>
  35  */
  36
  37 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  38
  39 #include <linux/types.h>
  40 #include <linux/kernel.h>
  41 #include <linux/wait.h>
  42 #include <linux/time.h>
  43 #include <linux/ip.h>
  44 #include <linux/ipv6.h>
  45 #include <linux/init.h>
  46 #include <linux/slab.h>
  47 #include <net/inet_ecn.h>
  48 #include <net/ip.h>
  49 #include <net/icmp.h>
  50 #include <net/net_namespace.h>
  51
  52 #include <linux/socket.h> /* for sa_family_t */
  53 #include <net/sock.h>
  54
  55 #include <net/sctp/sctp.h>
  56 #include <net/sctp/sm.h>
  57 #include <net/sctp/checksum.h>
  58
  59 /* Forward declarations for private helpers. */
  60 static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
  61                                                  struct sctp_chunk *chunk);
  62 static enum sctp_xmit sctp_packet_can_append_data(struct sctp_packet *packet,
  63                                                   struct sctp_chunk *chunk);
  64 static void sctp_packet_append_data(struct sctp_packet *packet,
  65                                     struct sctp_chunk *chunk);
  66 static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet,
  67                                            struct sctp_chunk *chunk,
  68                                            u16 chunk_len);
  69
  70 static void sctp_packet_reset(struct sctp_packet *packet)
  71 {
  72         /* sctp_packet_transmit() relies on this to reset size to the
  73          * current overhead after sending packets.
  74          */
  75         packet->size = packet->overhead;
  76
  77         packet->has_cookie_echo = 0;
  78         packet->has_sack = 0;
  79         packet->has_data = 0;
  80         packet->has_auth = 0;
  81         packet->ipfragok = 0;
  82         packet->auth = NULL;
  83 }
  84
  85 /* Config a packet.
  86  * This appears to be a followup set of initializations.
  87  */
  88 void sctp_packet_config(struct sctp_packet *packet, __u32 vtag,
  89                         int ecn_capable)
  90 {
  91         struct sctp_transport *tp = packet->transport;
  92         struct sctp_association *asoc = tp->asoc;
  93         struct sctp_sock *sp = NULL;
  94         struct sock *sk;
  95
  96         pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
  97         packet->vtag = vtag;
  98
  99         /* do the following jobs only once for a flush schedule */
 100         if (!sctp_packet_empty(packet))
 101                 return;
 102
 103         /* set packet max_size with pathmtu, then calculate overhead */
 104         packet->max_size = tp->pathmtu;
 105
 106         if (asoc) {
 107                 sk = asoc->base.sk;
 108                 sp = sctp_sk(sk);
 109         }
 110         packet->overhead = sctp_mtu_payload(sp, 0, 0);
 111         packet->size = packet->overhead;
 112
 113         if (!asoc)
 114                 return;
 115
 116         /* update dst or transport pathmtu if in need */
 117         if (!sctp_transport_dst_check(tp)) {
 118                 sctp_transport_route(tp, NULL, sp);
 119                 if (asoc->param_flags & SPP_PMTUD_ENABLE)
 120                         sctp_assoc_sync_pmtu(asoc);
 121         }
 122
 123         if (asoc->pmtu_pending) {
 124                 if (asoc->param_flags & SPP_PMTUD_ENABLE)
 125                         sctp_assoc_sync_pmtu(asoc);
 126                 asoc->pmtu_pending = 0;
 127         }
 128
 129         /* If there a is a prepend chunk stick it on the list before
 130          * any other chunks get appended.
 131          */
 132         if (ecn_capable) {
 133                 struct sctp_chunk *chunk = sctp_get_ecne_prepend(asoc);
 134
 135                 if (chunk)
 136                         sctp_packet_append_chunk(packet, chunk);
 137         }
 138
 139         if (!tp->dst)
 140                 return;
 141
 142         /* set packet max_size with gso_max_size if gso is enabled*/
 143         rcu_read_lock();
 144         if (__sk_dst_get(sk) != tp->dst) {
 145                 dst_hold(tp->dst);
 146                 sk_setup_caps(sk, tp->dst);
 147         }
 148         packet->max_size = sk_can_gso(sk) ? tp->dst->dev->gso_max_size
 149                                           : asoc->pathmtu;
 150         rcu_read_unlock();
 151 }
 152
 153 /* Initialize the packet structure. */
 154 void sctp_packet_init(struct sctp_packet *packet,
 155                       struct sctp_transport *transport,
 156                       __u16 sport, __u16 dport)
 157 {
 158         pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport);
 159
 160         packet->transport = transport;
 161         packet->source_port = sport;
 162         packet->destination_port = dport;
 163         INIT_LIST_HEAD(&packet->chunk_list);
 164         /* The overhead will be calculated by sctp_packet_config() */
 165         packet->overhead = 0;
 166         sctp_packet_reset(packet);
 167         packet->vtag = 0;
 168 }
 169
 170 /* Free a packet.  */
 171 void sctp_packet_free(struct sctp_packet *packet)
 172 {
 173         struct sctp_chunk *chunk, *tmp;
 174
 175         pr_debug("%s: packet:%p\n", __func__, packet);
 176
 177         list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
 178                 list_del_init(&chunk->list);
 179                 sctp_chunk_free(chunk);
 180         }
 181 }
 182
 183 /* This routine tries to append the chunk to the offered packet. If adding
 184  * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
 185  * is not present in the packet, it transmits the input packet.
 186  * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
 187  * as it can fit in the packet, but any more data that does not fit in this
 188  * packet can be sent only after receiving the COOKIE_ACK.
 189  */
 190 enum sctp_xmit sctp_packet_transmit_chunk(struct sctp_packet *packet,
 191                                           struct sctp_chunk *chunk,
 192                                           int one_packet, gfp_t gfp)
 193 {
 194         enum sctp_xmit retval;
 195
 196         pr_debug("%s: packet:%p size:%zu chunk:%p size:%d\n", __func__,
 197                  packet, packet->size, chunk, chunk->skb ? chunk->skb->len : -1);
 198
 199         switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
 200         case SCTP_XMIT_PMTU_FULL:
 201                 if (!packet->has_cookie_echo) {
 202                         int error = 0;
 203
 204                         error = sctp_packet_transmit(packet, gfp);
 205                         if (error < 0)
 206                                 chunk->skb->sk->sk_err = -error;
 207
 208                         /* If we have an empty packet, then we can NOT ever
 209                          * return PMTU_FULL.
 210                          */
 211                         if (!one_packet)
 212                                 retval = sctp_packet_append_chunk(packet,
 213                                                                   chunk);
 214                 }
 215                 break;
 216
 217         case SCTP_XMIT_RWND_FULL:
 218         case SCTP_XMIT_OK:
 219         case SCTP_XMIT_DELAY:
 220                 break;
 221         }
 222
 223         return retval;
 224 }
 225
 226 /* Try to bundle an auth chunk into the packet. */
 227 static enum sctp_xmit sctp_packet_bundle_auth(struct sctp_packet *pkt,
 228                                               struct sctp_chunk *chunk)
 229 {
 230         struct sctp_association *asoc = pkt->transport->asoc;
 231         enum sctp_xmit retval = SCTP_XMIT_OK;
 232         struct sctp_chunk *auth;
 233
 234         /* if we don't have an association, we can't do authentication */
 235         if (!asoc)
 236                 return retval;
 237
 238         /* See if this is an auth chunk we are bundling or if
 239          * auth is already bundled.
 240          */
 241         if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth)
 242                 return retval;
 243
 244         /* if the peer did not request this chunk to be authenticated,
 245          * don't do it
 246          */
 247         if (!chunk->auth)
 248                 return retval;
 249
 250         auth = sctp_make_auth(asoc, chunk->shkey->key_id);
 251         if (!auth)
 252                 return retval;
 253
 254         auth->shkey = chunk->shkey;
 255         sctp_auth_shkey_hold(auth->shkey);
 256
 257         retval = __sctp_packet_append_chunk(pkt, auth);
 258
 259         if (retval != SCTP_XMIT_OK)
 260                 sctp_chunk_free(auth);
 261
 262         return retval;
 263 }
 264
 265 /* Try to bundle a SACK with the packet. */
 266 static enum sctp_xmit sctp_packet_bundle_sack(struct sctp_packet *pkt,
 267                                               struct sctp_chunk *chunk)
 268 {
 269         enum sctp_xmit retval = SCTP_XMIT_OK;
 270
 271         /* If sending DATA and haven't aleady bundled a SACK, try to
 272          * bundle one in to the packet.
 273          */
 274         if (sctp_chunk_is_data(chunk) && !pkt->has_sack &&
 275             !pkt->has_cookie_echo) {
 276                 struct sctp_association *asoc;
 277                 struct timer_list *timer;
 278                 asoc = pkt->transport->asoc;
 279                 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
 280
 281                 /* If the SACK timer is running, we have a pending SACK */
 282                 if (timer_pending(timer)) {
 283                         struct sctp_chunk *sack;
 284
 285                         if (pkt->transport->sack_generation !=
 286                             pkt->transport->asoc->peer.sack_generation)
 287                                 return retval;
 288
 289                         asoc->a_rwnd = asoc->rwnd;
 290                         sack = sctp_make_sack(asoc);
 291                         if (sack) {
 292                                 retval = __sctp_packet_append_chunk(pkt, sack);
 293                                 if (retval != SCTP_XMIT_OK) {
 294                                         sctp_chunk_free(sack);
 295                                         goto out;
 296                                 }
 297                                 asoc->peer.sack_needed = 0;
 298                                 if (del_timer(timer))
 299                                         sctp_association_put(asoc);
 300                         }
 301                 }
 302         }
 303 out:
 304         return retval;
 305 }
 306
 307
 308 /* Append a chunk to the offered packet reporting back any inability to do
 309  * so.
 310  */
 311 static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
 312                                                  struct sctp_chunk *chunk)
 313 {
 314         __u16 chunk_len = SCTP_PAD4(ntohs(chunk->chunk_hdr->length));
 315         enum sctp_xmit retval = SCTP_XMIT_OK;
 316
 317         /* Check to see if this chunk will fit into the packet */
 318         retval = sctp_packet_will_fit(packet, chunk, chunk_len);
 319         if (retval != SCTP_XMIT_OK)
 320                 goto finish;
 321
 322         /* We believe that this chunk is OK to add to the packet */
 323         switch (chunk->chunk_hdr->type) {
 324         case SCTP_CID_DATA:
 325         case SCTP_CID_I_DATA:
 326                 /* Account for the data being in the packet */
 327                 sctp_packet_append_data(packet, chunk);
 328                 /* Disallow SACK bundling after DATA. */
 329                 packet->has_sack = 1;
 330                 /* Disallow AUTH bundling after DATA */
 331                 packet->has_auth = 1;
 332                 /* Let it be knows that packet has DATA in it */
 333                 packet->has_data = 1;
 334                 /* timestamp the chunk for rtx purposes */
 335                 chunk->sent_at = jiffies;
 336                 /* Mainly used for prsctp RTX policy */
 337                 chunk->sent_count++;
 338                 break;
 339         case SCTP_CID_COOKIE_ECHO:
 340                 packet->has_cookie_echo = 1;
 341                 break;
 342
 343         case SCTP_CID_SACK:
 344                 packet->has_sack = 1;
 345                 if (chunk->asoc)
 346                         chunk->asoc->stats.osacks++;
 347                 break;
 348
 349         case SCTP_CID_AUTH:
 350                 packet->has_auth = 1;
 351                 packet->auth = chunk;
 352                 break;
 353         }
 354
 355         /* It is OK to send this chunk.  */
 356         list_add_tail(&chunk->list, &packet->chunk_list);
 357         packet->size += chunk_len;
 358         chunk->transport = packet->transport;
 359 finish:
 360         return retval;
 361 }
 362
 363 /* Append a chunk to the offered packet reporting back any inability to do
 364  * so.
 365  */
 366 enum sctp_xmit sctp_packet_append_chunk(struct sctp_packet *packet,
 367                                         struct sctp_chunk *chunk)
 368 {
 369         enum sctp_xmit retval = SCTP_XMIT_OK;
 370
 371         pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
 372
 373         /* Data chunks are special.  Before seeing what else we can
 374          * bundle into this packet, check to see if we are allowed to
 375          * send this DATA.
 376          */
 377         if (sctp_chunk_is_data(chunk)) {
 378                 retval = sctp_packet_can_append_data(packet, chunk);
 379                 if (retval != SCTP_XMIT_OK)
 380                         goto finish;
 381         }
 382
 383         /* Try to bundle AUTH chunk */
 384         retval = sctp_packet_bundle_auth(packet, chunk);
 385         if (retval != SCTP_XMIT_OK)
 386                 goto finish;
 387
 388         /* Try to bundle SACK chunk */
 389         retval = sctp_packet_bundle_sack(packet, chunk);
 390         if (retval != SCTP_XMIT_OK)
 391                 goto finish;
 392
 393         retval = __sctp_packet_append_chunk(packet, chunk);
 394
 395 finish:
 396         return retval;
 397 }
 398
 399 static void sctp_packet_release_owner(struct sk_buff *skb)
 400 {
 401         sk_free(skb->sk);
 402 }
 403
 404 static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
 405 {
 406         skb_orphan(skb);
 407         skb->sk = sk;
 408         skb->destructor = sctp_packet_release_owner;
 409
 410         /*
 411          * The data chunks have already been accounted for in sctp_sendmsg(),
 412          * therefore only reserve a single byte to keep socket around until
 413          * the packet has been transmitted.
 414          */
 415         refcount_inc(&sk->sk_wmem_alloc);
 416 }
 417
 418 static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
 419 {
 420         if (SCTP_OUTPUT_CB(head)->last == head)
 421                 skb_shinfo(head)->frag_list = skb;
 422         else
 423                 SCTP_OUTPUT_CB(head)->last->next = skb;
 424         SCTP_OUTPUT_CB(head)->last = skb;
 425
 426         head->truesize += skb->truesize;
 427         head->data_len += skb->len;
 428         head->len += skb->len;
 429
 430         __skb_header_release(skb);
 431 }
 432
 433 static int sctp_packet_pack(struct sctp_packet *packet,
 434                             struct sk_buff *head, int gso, gfp_t gfp)
 435 {
 436         struct sctp_transport *tp = packet->transport;
 437         struct sctp_auth_chunk *auth = NULL;
 438         struct sctp_chunk *chunk, *tmp;
 439         int pkt_count = 0, pkt_size;
 440         struct sock *sk = head->sk;
 441         struct sk_buff *nskb;
 442         int auth_len = 0;
 443
 444         if (gso) {
 445                 skb_shinfo(head)->gso_type = sk->sk_gso_type;
 446                 SCTP_OUTPUT_CB(head)->last = head;
 447         } else {
 448                 nskb = head;
 449                 pkt_size = packet->size;
 450                 goto merge;
 451         }
 452
 453         do {
 454                 /* calculate the pkt_size and alloc nskb */
 455                 pkt_size = packet->overhead;
 456                 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list,
 457                                          list) {
 458                         int padded = SCTP_PAD4(chunk->skb->len);
 459
 460                         if (chunk == packet->auth)
 461                                 auth_len = padded;
 462                         else if (auth_len + padded + packet->overhead >
 463                                  tp->pathmtu)
 464                                 return 0;
 465                         else if (pkt_size + padded > tp->pathmtu)
 466                                 break;
 467                         pkt_size += padded;
 468                 }
 469                 nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
 470                 if (!nskb)
 471                         return 0;
 472                 skb_reserve(nskb, packet->overhead + MAX_HEADER);
 473
 474 merge:
 475                 /* merge chunks into nskb and append nskb into head list */
 476                 pkt_size -= packet->overhead;
 477                 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
 478                         int padding;
 479
 480                         list_del_init(&chunk->list);
 481                         if (sctp_chunk_is_data(chunk)) {
 482                                 if (!sctp_chunk_retransmitted(chunk) &&
 483                                     !tp->rto_pending) {
 484                                         chunk->rtt_in_progress = 1;
 485                                         tp->rto_pending = 1;
 486                                 }
 487                         }
 488
 489                         padding = SCTP_PAD4(chunk->skb->len) - chunk->skb->len;
 490                         if (padding)
 491                                 skb_put_zero(chunk->skb, padding);
 492
 493                         if (chunk == packet->auth)
 494                                 auth = (struct sctp_auth_chunk *)
 495                                                         skb_tail_pointer(nskb);
 496
 497                         skb_put_data(nskb, chunk->skb->data, chunk->skb->len);
 498
 499                         pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
 500                                  chunk,
 501                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 502                                  chunk->has_tsn ? "TSN" : "No TSN",
 503                                  chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
 504                                  ntohs(chunk->chunk_hdr->length), chunk->skb->len,
 505                                  chunk->rtt_in_progress);
 506
 507                         pkt_size -= SCTP_PAD4(chunk->skb->len);
 508
 509                         if (!sctp_chunk_is_data(chunk) && chunk != packet->auth)
 510                                 sctp_chunk_free(chunk);
 511
 512                         if (!pkt_size)
 513                                 break;
 514                 }
 515
 516                 if (auth) {
 517                         sctp_auth_calculate_hmac(tp->asoc, nskb, auth,
 518                                                  packet->auth->shkey, gfp);
 519                         /* free auth if no more chunks, or add it back */
 520                         if (list_empty(&packet->chunk_list))
 521                                 sctp_chunk_free(packet->auth);
 522                         else
 523                                 list_add(&packet->auth->list,
 524                                          &packet->chunk_list);
 525                 }
 526
 527                 if (gso)
 528                         sctp_packet_gso_append(head, nskb);
 529
 530                 pkt_count++;
 531         } while (!list_empty(&packet->chunk_list));
 532
 533         if (gso) {
 534                 memset(head->cb, 0, max(sizeof(struct inet_skb_parm),
 535                                         sizeof(struct inet6_skb_parm)));
 536                 skb_shinfo(head)->gso_segs = pkt_count;
 537                 skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
 538                 rcu_read_lock();
 539                 if (skb_dst(head) != tp->dst) {
 540                         dst_hold(tp->dst);
 541                         sk_setup_caps(sk, tp->dst);
 542                 }
 543                 rcu_read_unlock();
 544                 goto chksum;
 545         }
 546
 547         if (sctp_checksum_disable)
 548                 return 1;
 549
 550         if (!(skb_dst(head)->dev->features & NETIF_F_SCTP_CRC) ||
 551             dst_xfrm(skb_dst(head)) || packet->ipfragok) {
 552                 struct sctphdr *sh =
 553                         (struct sctphdr *)skb_transport_header(head);
 554
 555                 sh->checksum = sctp_compute_cksum(head, 0);
 556         } else {
 557 chksum:
 558                 head->ip_summed = CHECKSUM_PARTIAL;
 559                 head->csum_not_inet = 1;
 560                 head->csum_start = skb_transport_header(head) - head->head;
 561                 head->csum_offset = offsetof(struct sctphdr, checksum);
 562         }
 563
 564         return pkt_count;
 565 }
 566
 567 /* All packets are sent to the network through this function from
 568  * sctp_outq_tail().
 569  *
 570  * The return value is always 0 for now.
 571  */
 572 int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 573 {
 574         struct sctp_transport *tp = packet->transport;
 575         struct sctp_association *asoc = tp->asoc;
 576         struct sctp_chunk *chunk, *tmp;
 577         int pkt_count, gso = 0;
 578         struct dst_entry *dst;
 579         struct sk_buff *head;
 580         struct sctphdr *sh;
 581         struct sock *sk;
 582
 583         pr_debug("%s: packet:%p\n", __func__, packet);
 584         if (list_empty(&packet->chunk_list))
 585                 return 0;
 586         chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
 587         sk = chunk->skb->sk;
 588
 589         /* check gso */
 590         if (packet->size > tp->pathmtu && !packet->ipfragok) {
 591                 if (!sk_can_gso(sk)) {
 592                         pr_err_once("Trying to GSO but underlying device doesn't support it.");
 593                         goto out;
 594                 }
 595                 gso = 1;
 596         }
 597
 598         /* alloc head skb */
 599         head = alloc_skb((gso ? packet->overhead : packet->size) +
 600                          MAX_HEADER, gfp);
 601         if (!head)
 602                 goto out;
 603         skb_reserve(head, packet->overhead + MAX_HEADER);
 604         sctp_packet_set_owner_w(head, sk);
 605
 606         /* set sctp header */
 607         sh = skb_push(head, sizeof(struct sctphdr));
 608         skb_reset_transport_header(head);
 609         sh->source = htons(packet->source_port);
 610         sh->dest = htons(packet->destination_port);
 611         sh->vtag = htonl(packet->vtag);
 612         sh->checksum = 0;
 613
 614         /* drop packet if no dst */
 615         dst = dst_clone(tp->dst);
 616         if (!dst) {
 617                 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 618                 kfree_skb(head);
 619                 goto out;
 620         }
 621         skb_dst_set(head, dst);
 622
 623         /* pack up chunks */
 624         pkt_count = sctp_packet_pack(packet, head, gso, gfp);
 625         if (!pkt_count) {
 626                 kfree_skb(head);
 627                 goto out;
 628         }
 629         pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len);
 630
 631         /* start autoclose timer */
 632         if (packet->has_data && sctp_state(asoc, ESTABLISHED) &&
 633             asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
 634                 struct timer_list *timer =
 635                         &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
 636                 unsigned long timeout =
 637                         asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
 638
 639                 if (!mod_timer(timer, jiffies + timeout))
 640                         sctp_association_hold(asoc);
 641         }
 642
 643         /* sctp xmit */
 644         tp->af_specific->ecn_capable(sk);
 645         if (asoc) {
 646                 asoc->stats.opackets += pkt_count;
 647                 if (asoc->peer.last_sent_to != tp)
 648                         asoc->peer.last_sent_to = tp;
 649         }
 650         head->ignore_df = packet->ipfragok;
 651         if (tp->dst_pending_confirm)
 652                 skb_set_dst_pending_confirm(head, 1);
 653         /* neighbour should be confirmed on successful transmission or
 654          * positive error
 655          */
 656         if (tp->af_specific->sctp_xmit(head, tp) >= 0 &&
 657             tp->dst_pending_confirm)
 658                 tp->dst_pending_confirm = 0;
 659
 660 out:
 661         list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
 662                 list_del_init(&chunk->list);
 663                 if (!sctp_chunk_is_data(chunk))
 664                         sctp_chunk_free(chunk);
 665         }
 666         sctp_packet_reset(packet);
 667         return 0;
 668 }
 669
 670 /********************************************************************
 671  * 2nd Level Abstractions
 672  ********************************************************************/
 673
 674 /* This private function check to see if a chunk can be added */
 675 static enum sctp_xmit sctp_packet_can_append_data(struct sctp_packet *packet,
 676                                                   struct sctp_chunk *chunk)
 677 {
 678         size_t datasize, rwnd, inflight, flight_size;
 679         struct sctp_transport *transport = packet->transport;
 680         struct sctp_association *asoc = transport->asoc;
 681         struct sctp_outq *q = &asoc->outqueue;
 682
 683         /* RFC 2960 6.1  Transmission of DATA Chunks
 684          *
 685          * A) At any given time, the data sender MUST NOT transmit new data to
 686          * any destination transport address if its peer's rwnd indicates
 687          * that the peer has no buffer space (i.e. rwnd is 0, see Section
 688          * 6.2.1).  However, regardless of the value of rwnd (including if it
 689          * is 0), the data sender can always have one DATA chunk in flight to
 690          * the receiver if allowed by cwnd (see rule B below).  This rule
 691          * allows the sender to probe for a change in rwnd that the sender
 692          * missed due to the SACK having been lost in transit from the data
 693          * receiver to the data sender.
 694          */
 695
 696         rwnd = asoc->peer.rwnd;
 697         inflight = q->outstanding_bytes;
 698         flight_size = transport->flight_size;
 699
 700         datasize = sctp_data_size(chunk);
 701
 702         if (datasize > rwnd && inflight > 0)
 703                 /* We have (at least) one data chunk in flight,
 704                  * so we can't fall back to rule 6.1 B).
 705                  */
 706                 return SCTP_XMIT_RWND_FULL;
 707
 708         /* RFC 2960 6.1  Transmission of DATA Chunks
 709          *
 710          * B) At any given time, the sender MUST NOT transmit new data
 711          * to a given transport address if it has cwnd or more bytes
 712          * of data outstanding to that transport address.
 713          */
 714         /* RFC 7.2.4 & the Implementers Guide 2.8.
 715          *
 716          * 3) ...
 717          *    When a Fast Retransmit is being performed the sender SHOULD
 718          *    ignore the value of cwnd and SHOULD NOT delay retransmission.
 719          */
 720         if (chunk->fast_retransmit != SCTP_NEED_FRTX &&
 721             flight_size >= transport->cwnd)
 722                 return SCTP_XMIT_RWND_FULL;
 723
 724         /* Nagle's algorithm to solve small-packet problem:
 725          * Inhibit the sending of new chunks when new outgoing data arrives
 726          * if any previously transmitted data on the connection remains
 727          * unacknowledged.
 728          */
 729
 730         if ((sctp_sk(asoc->base.sk)->nodelay || inflight == 0) &&
 731             !asoc->force_delay)
 732                 /* Nothing unacked */
 733                 return SCTP_XMIT_OK;
 734
 735         if (!sctp_packet_empty(packet))
 736                 /* Append to packet */
 737                 return SCTP_XMIT_OK;
 738
 739         if (!sctp_state(asoc, ESTABLISHED))
 740                 return SCTP_XMIT_OK;
 741
 742         /* Check whether this chunk and all the rest of pending data will fit
 743          * or delay in hopes of bundling a full sized packet.
 744          */
 745         if (chunk->skb->len + q->out_qlen > transport->pathmtu -
 746             packet->overhead - sctp_datachk_len(&chunk->asoc->stream) - 4)
 747                 /* Enough data queued to fill a packet */
 748                 return SCTP_XMIT_OK;
 749
 750         /* Don't delay large message writes that may have been fragmented */
 751         if (!chunk->msg->can_delay)
 752                 return SCTP_XMIT_OK;
 753
 754         /* Defer until all data acked or packet full */
 755         return SCTP_XMIT_DELAY;
 756 }
 757
 758 /* This private function does management things when adding DATA chunk */
 759 static void sctp_packet_append_data(struct sctp_packet *packet,
 760                                 struct sctp_chunk *chunk)
 761 {
 762         struct sctp_transport *transport = packet->transport;
 763         size_t datasize = sctp_data_size(chunk);
 764         struct sctp_association *asoc = transport->asoc;
 765         u32 rwnd = asoc->peer.rwnd;
 766
 767         /* Keep track of how many bytes are in flight over this transport. */
 768         transport->flight_size += datasize;
 769
 770         /* Keep track of how many bytes are in flight to the receiver. */
 771         asoc->outqueue.outstanding_bytes += datasize;
 772
 773         /* Update our view of the receiver's rwnd. */
 774         if (datasize < rwnd)
 775                 rwnd -= datasize;
 776         else
 777                 rwnd = 0;
 778
 779         asoc->peer.rwnd = rwnd;
 780         sctp_chunk_assign_tsn(chunk);
 781         asoc->stream.si->assign_number(chunk);
 782 }
 783
 784 static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet,
 785                                            struct sctp_chunk *chunk,
 786                                            u16 chunk_len)
 787 {
 788         enum sctp_xmit retval = SCTP_XMIT_OK;
 789         size_t psize, pmtu, maxsize;
 790
 791         /* Don't bundle in this packet if this chunk's auth key doesn't
 792          * match other chunks already enqueued on this packet. Also,
 793          * don't bundle the chunk with auth key if other chunks in this
 794          * packet don't have auth key.
 795          */
 796         if ((packet->auth && chunk->shkey != packet->auth->shkey) ||
 797             (!packet->auth && chunk->shkey &&
 798              chunk->chunk_hdr->type != SCTP_CID_AUTH))
 799                 return SCTP_XMIT_PMTU_FULL;
 800
 801         psize = packet->size;
 802         if (packet->transport->asoc)
 803                 pmtu = packet->transport->asoc->pathmtu;
 804         else
 805                 pmtu = packet->transport->pathmtu;
 806
 807         /* Decide if we need to fragment or resubmit later. */
 808         if (psize + chunk_len > pmtu) {
 809                 /* It's OK to fragment at IP level if any one of the following
 810                  * is true:
 811                  *      1. The packet is empty (meaning this chunk is greater
 812                  *         the MTU)
 813                  *      2. The packet doesn't have any data in it yet and data
 814                  *         requires authentication.
 815                  */
 816                 if (sctp_packet_empty(packet) ||
 817                     (!packet->has_data && chunk->auth)) {
 818                         /* We no longer do re-fragmentation.
 819                          * Just fragment at the IP layer, if we
 820                          * actually hit this condition
 821                          */
 822                         packet->ipfragok = 1;
 823                         goto out;
 824                 }
 825
 826                 /* Similarly, if this chunk was built before a PMTU
 827                  * reduction, we have to fragment it at IP level now. So
 828                  * if the packet already contains something, we need to
 829                  * flush.
 830                  */
 831                 maxsize = pmtu - packet->overhead;
 832                 if (packet->auth)
 833                         maxsize -= SCTP_PAD4(packet->auth->skb->len);
 834                 if (chunk_len > maxsize)
 835                         retval = SCTP_XMIT_PMTU_FULL;
 836
 837                 /* It is also okay to fragment if the chunk we are
 838                  * adding is a control chunk, but only if current packet
 839                  * is not a GSO one otherwise it causes fragmentation of
 840                  * a large frame. So in this case we allow the
 841                  * fragmentation by forcing it to be in a new packet.
 842                  */
 843                 if (!sctp_chunk_is_data(chunk) && packet->has_data)
 844                         retval = SCTP_XMIT_PMTU_FULL;
 845
 846                 if (psize + chunk_len > packet->max_size)
 847                         /* Hit GSO/PMTU limit, gotta flush */
 848                         retval = SCTP_XMIT_PMTU_FULL;
 849
 850                 if (!packet->transport->burst_limited &&
 851                     psize + chunk_len > (packet->transport->cwnd >> 1))
 852                         /* Do not allow a single GSO packet to use more
 853                          * than half of cwnd.
 854                          */
 855                         retval = SCTP_XMIT_PMTU_FULL;
 856
 857                 if (packet->transport->burst_limited &&
 858                     psize + chunk_len > (packet->transport->burst_limited >> 1))
 859                         /* Do not allow a single GSO packet to use more
 860                          * than half of original cwnd.
 861                          */
 862                         retval = SCTP_XMIT_PMTU_FULL;
 863                 /* Otherwise it will fit in the GSO packet */
 864         }
 865
 866 out:
 867         return retval;
 868 }