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