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 <linux-sctp@vger.kernel.org> 29 * 30 * Written or modified by: 31 * La Monte H.P. Yarroll <piggy@acm.org> 32 * Karl Knutson <karl@athena.chicago.il.us> 33 * Jon Grimm <jgrimm@austin.ibm.com> 34 * Sridhar Samudrala <sri@us.ibm.com> 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 sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet, 61 struct sctp_chunk *chunk); 62 static sctp_xmit_t 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 sctp_xmit_t 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 packet->size = packet->overhead; 73 packet->has_cookie_echo = 0; 74 packet->has_sack = 0; 75 packet->has_data = 0; 76 packet->has_auth = 0; 77 packet->ipfragok = 0; 78 packet->auth = NULL; 79 } 80 81 /* Config a packet. 82 * This appears to be a followup set of initializations. 83 */ 84 struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, 85 __u32 vtag, int ecn_capable) 86 { 87 struct sctp_transport *tp = packet->transport; 88 struct sctp_association *asoc = tp->asoc; 89 90 pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag); 91 92 packet->vtag = vtag; 93 94 if (asoc && tp->dst) { 95 struct sock *sk = asoc->base.sk; 96 97 rcu_read_lock(); 98 if (__sk_dst_get(sk) != tp->dst) { 99 dst_hold(tp->dst); 100 sk_setup_caps(sk, tp->dst); 101 } 102 103 if (sk_can_gso(sk)) { 104 struct net_device *dev = tp->dst->dev; 105 106 packet->max_size = dev->gso_max_size; 107 } else { 108 packet->max_size = asoc->pathmtu; 109 } 110 rcu_read_unlock(); 111 112 } else { 113 packet->max_size = tp->pathmtu; 114 } 115 116 if (ecn_capable && sctp_packet_empty(packet)) { 117 struct sctp_chunk *chunk; 118 119 /* If there a is a prepend chunk stick it on the list before 120 * any other chunks get appended. 121 */ 122 chunk = sctp_get_ecne_prepend(asoc); 123 if (chunk) 124 sctp_packet_append_chunk(packet, chunk); 125 } 126 127 return packet; 128 } 129 130 /* Initialize the packet structure. */ 131 struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, 132 struct sctp_transport *transport, 133 __u16 sport, __u16 dport) 134 { 135 struct sctp_association *asoc = transport->asoc; 136 size_t overhead; 137 138 pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport); 139 140 packet->transport = transport; 141 packet->source_port = sport; 142 packet->destination_port = dport; 143 INIT_LIST_HEAD(&packet->chunk_list); 144 if (asoc) { 145 struct sctp_sock *sp = sctp_sk(asoc->base.sk); 146 overhead = sp->pf->af->net_header_len; 147 } else { 148 overhead = sizeof(struct ipv6hdr); 149 } 150 overhead += sizeof(struct sctphdr); 151 packet->overhead = overhead; 152 sctp_packet_reset(packet); 153 packet->vtag = 0; 154 155 return packet; 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 sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, 179 struct sctp_chunk *chunk, 180 int one_packet, gfp_t gfp) 181 { 182 sctp_xmit_t 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 sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, 216 struct sctp_chunk *chunk) 217 { 218 struct sctp_association *asoc = pkt->transport->asoc; 219 struct sctp_chunk *auth; 220 sctp_xmit_t retval = SCTP_XMIT_OK; 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); 239 if (!auth) 240 return retval; 241 242 retval = __sctp_packet_append_chunk(pkt, auth); 243 244 if (retval != SCTP_XMIT_OK) 245 sctp_chunk_free(auth); 246 247 return retval; 248 } 249 250 /* Try to bundle a SACK with the packet. */ 251 static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, 252 struct sctp_chunk *chunk) 253 { 254 sctp_xmit_t retval = SCTP_XMIT_OK; 255 256 /* If sending DATA and haven't aleady bundled a SACK, try to 257 * bundle one in to the packet. 258 */ 259 if (sctp_chunk_is_data(chunk) && !pkt->has_sack && 260 !pkt->has_cookie_echo) { 261 struct sctp_association *asoc; 262 struct timer_list *timer; 263 asoc = pkt->transport->asoc; 264 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; 265 266 /* If the SACK timer is running, we have a pending SACK */ 267 if (timer_pending(timer)) { 268 struct sctp_chunk *sack; 269 270 if (pkt->transport->sack_generation != 271 pkt->transport->asoc->peer.sack_generation) 272 return retval; 273 274 asoc->a_rwnd = asoc->rwnd; 275 sack = sctp_make_sack(asoc); 276 if (sack) { 277 retval = __sctp_packet_append_chunk(pkt, sack); 278 if (retval != SCTP_XMIT_OK) { 279 sctp_chunk_free(sack); 280 goto out; 281 } 282 asoc->peer.sack_needed = 0; 283 if (del_timer(timer)) 284 sctp_association_put(asoc); 285 } 286 } 287 } 288 out: 289 return retval; 290 } 291 292 293 /* Append a chunk to the offered packet reporting back any inability to do 294 * so. 295 */ 296 static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet, 297 struct sctp_chunk *chunk) 298 { 299 sctp_xmit_t retval = SCTP_XMIT_OK; 300 __u16 chunk_len = SCTP_PAD4(ntohs(chunk->chunk_hdr->length)); 301 302 /* Check to see if this chunk will fit into the packet */ 303 retval = sctp_packet_will_fit(packet, chunk, chunk_len); 304 if (retval != SCTP_XMIT_OK) 305 goto finish; 306 307 /* We believe that this chunk is OK to add to the packet */ 308 switch (chunk->chunk_hdr->type) { 309 case SCTP_CID_DATA: 310 /* Account for the data being in the packet */ 311 sctp_packet_append_data(packet, chunk); 312 /* Disallow SACK bundling after DATA. */ 313 packet->has_sack = 1; 314 /* Disallow AUTH bundling after DATA */ 315 packet->has_auth = 1; 316 /* Let it be knows that packet has DATA in it */ 317 packet->has_data = 1; 318 /* timestamp the chunk for rtx purposes */ 319 chunk->sent_at = jiffies; 320 /* Mainly used for prsctp RTX policy */ 321 chunk->sent_count++; 322 break; 323 case SCTP_CID_COOKIE_ECHO: 324 packet->has_cookie_echo = 1; 325 break; 326 327 case SCTP_CID_SACK: 328 packet->has_sack = 1; 329 if (chunk->asoc) 330 chunk->asoc->stats.osacks++; 331 break; 332 333 case SCTP_CID_AUTH: 334 packet->has_auth = 1; 335 packet->auth = chunk; 336 break; 337 } 338 339 /* It is OK to send this chunk. */ 340 list_add_tail(&chunk->list, &packet->chunk_list); 341 packet->size += chunk_len; 342 chunk->transport = packet->transport; 343 finish: 344 return retval; 345 } 346 347 /* Append a chunk to the offered packet reporting back any inability to do 348 * so. 349 */ 350 sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, 351 struct sctp_chunk *chunk) 352 { 353 sctp_xmit_t retval = SCTP_XMIT_OK; 354 355 pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk); 356 357 /* Data chunks are special. Before seeing what else we can 358 * bundle into this packet, check to see if we are allowed to 359 * send this DATA. 360 */ 361 if (sctp_chunk_is_data(chunk)) { 362 retval = sctp_packet_can_append_data(packet, chunk); 363 if (retval != SCTP_XMIT_OK) 364 goto finish; 365 } 366 367 /* Try to bundle AUTH chunk */ 368 retval = sctp_packet_bundle_auth(packet, chunk); 369 if (retval != SCTP_XMIT_OK) 370 goto finish; 371 372 /* Try to bundle SACK chunk */ 373 retval = sctp_packet_bundle_sack(packet, chunk); 374 if (retval != SCTP_XMIT_OK) 375 goto finish; 376 377 retval = __sctp_packet_append_chunk(packet, chunk); 378 379 finish: 380 return retval; 381 } 382 383 static void sctp_packet_release_owner(struct sk_buff *skb) 384 { 385 sk_free(skb->sk); 386 } 387 388 static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk) 389 { 390 skb_orphan(skb); 391 skb->sk = sk; 392 skb->destructor = sctp_packet_release_owner; 393 394 /* 395 * The data chunks have already been accounted for in sctp_sendmsg(), 396 * therefore only reserve a single byte to keep socket around until 397 * the packet has been transmitted. 398 */ 399 atomic_inc(&sk->sk_wmem_alloc); 400 } 401 402 /* All packets are sent to the network through this function from 403 * sctp_outq_tail(). 404 * 405 * The return value is a normal kernel error return value. 406 */ 407 int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) 408 { 409 struct sctp_transport *tp = packet->transport; 410 struct sctp_association *asoc = tp->asoc; 411 struct sctphdr *sh; 412 struct sk_buff *nskb = NULL, *head = NULL; 413 struct sctp_chunk *chunk, *tmp; 414 struct sock *sk; 415 int err = 0; 416 int padding; /* How much padding do we need? */ 417 int pkt_size; 418 __u8 has_data = 0; 419 int gso = 0; 420 int pktcount = 0; 421 int auth_len = 0; 422 struct dst_entry *dst; 423 unsigned char *auth = NULL; /* pointer to auth in skb data */ 424 425 pr_debug("%s: packet:%p\n", __func__, packet); 426 427 /* Do NOT generate a chunkless packet. */ 428 if (list_empty(&packet->chunk_list)) 429 return err; 430 431 /* Set up convenience variables... */ 432 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 433 sk = chunk->skb->sk; 434 435 /* Allocate the head skb, or main one if not in GSO */ 436 if (packet->size > tp->pathmtu && !packet->ipfragok) { 437 if (sk_can_gso(sk)) { 438 gso = 1; 439 pkt_size = packet->overhead; 440 } else { 441 /* If this happens, we trash this packet and try 442 * to build a new one, hopefully correct this 443 * time. Application may notice this error. 444 */ 445 pr_err_once("Trying to GSO but underlying device doesn't support it."); 446 goto err; 447 } 448 } else { 449 pkt_size = packet->size; 450 } 451 head = alloc_skb(pkt_size + MAX_HEADER, gfp); 452 if (!head) 453 goto err; 454 if (gso) { 455 NAPI_GRO_CB(head)->last = head; 456 skb_shinfo(head)->gso_type = sk->sk_gso_type; 457 } 458 459 /* Make sure the outbound skb has enough header room reserved. */ 460 skb_reserve(head, packet->overhead + MAX_HEADER); 461 462 /* Set the owning socket so that we know where to get the 463 * destination IP address. 464 */ 465 sctp_packet_set_owner_w(head, sk); 466 467 if (!sctp_transport_dst_check(tp)) { 468 sctp_transport_route(tp, NULL, sctp_sk(sk)); 469 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { 470 sctp_assoc_sync_pmtu(sk, asoc); 471 } 472 } 473 dst = dst_clone(tp->dst); 474 if (!dst) { 475 if (asoc) 476 IP_INC_STATS(sock_net(asoc->base.sk), 477 IPSTATS_MIB_OUTNOROUTES); 478 goto nodst; 479 } 480 skb_dst_set(head, dst); 481 482 /* Build the SCTP header. */ 483 sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr)); 484 skb_reset_transport_header(head); 485 sh->source = htons(packet->source_port); 486 sh->dest = htons(packet->destination_port); 487 488 /* From 6.8 Adler-32 Checksum Calculation: 489 * After the packet is constructed (containing the SCTP common 490 * header and one or more control or DATA chunks), the 491 * transmitter shall: 492 * 493 * 1) Fill in the proper Verification Tag in the SCTP common 494 * header and initialize the checksum field to 0's. 495 */ 496 sh->vtag = htonl(packet->vtag); 497 sh->checksum = 0; 498 499 pr_debug("***sctp_transmit_packet***\n"); 500 501 do { 502 /* Set up convenience variables... */ 503 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 504 pktcount++; 505 506 /* Calculate packet size, so it fits in PMTU. Leave 507 * other chunks for the next packets. 508 */ 509 if (gso) { 510 pkt_size = packet->overhead; 511 list_for_each_entry(chunk, &packet->chunk_list, list) { 512 int padded = SCTP_PAD4(chunk->skb->len); 513 514 if (chunk == packet->auth) 515 auth_len = padded; 516 else if (auth_len + padded + packet->overhead > 517 tp->pathmtu) 518 goto nomem; 519 else if (pkt_size + padded > tp->pathmtu) 520 break; 521 pkt_size += padded; 522 } 523 524 /* Allocate a new skb. */ 525 nskb = alloc_skb(pkt_size + MAX_HEADER, gfp); 526 if (!nskb) 527 goto nomem; 528 529 /* Make sure the outbound skb has enough header 530 * room reserved. 531 */ 532 skb_reserve(nskb, packet->overhead + MAX_HEADER); 533 } else { 534 nskb = head; 535 } 536 537 /** 538 * 3.2 Chunk Field Descriptions 539 * 540 * The total length of a chunk (including Type, Length and 541 * Value fields) MUST be a multiple of 4 bytes. If the length 542 * of the chunk is not a multiple of 4 bytes, the sender MUST 543 * pad the chunk with all zero bytes and this padding is not 544 * included in the chunk length field. The sender should 545 * never pad with more than 3 bytes. 546 * 547 * [This whole comment explains SCTP_PAD4() below.] 548 */ 549 550 pkt_size -= packet->overhead; 551 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 552 list_del_init(&chunk->list); 553 if (sctp_chunk_is_data(chunk)) { 554 /* 6.3.1 C4) When data is in flight and when allowed 555 * by rule C5, a new RTT measurement MUST be made each 556 * round trip. Furthermore, new RTT measurements 557 * SHOULD be made no more than once per round-trip 558 * for a given destination transport address. 559 */ 560 561 if (!chunk->resent && !tp->rto_pending) { 562 chunk->rtt_in_progress = 1; 563 tp->rto_pending = 1; 564 } 565 566 has_data = 1; 567 } 568 569 padding = SCTP_PAD4(chunk->skb->len) - chunk->skb->len; 570 if (padding) 571 memset(skb_put(chunk->skb, padding), 0, padding); 572 573 /* if this is the auth chunk that we are adding, 574 * store pointer where it will be added and put 575 * the auth into the packet. 576 */ 577 if (chunk == packet->auth) 578 auth = skb_tail_pointer(nskb); 579 580 memcpy(skb_put(nskb, chunk->skb->len), 581 chunk->skb->data, chunk->skb->len); 582 583 pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n", 584 chunk, 585 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)), 586 chunk->has_tsn ? "TSN" : "No TSN", 587 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0, 588 ntohs(chunk->chunk_hdr->length), chunk->skb->len, 589 chunk->rtt_in_progress); 590 591 /* If this is a control chunk, this is our last 592 * reference. Free data chunks after they've been 593 * acknowledged or have failed. 594 * Re-queue auth chunks if needed. 595 */ 596 pkt_size -= SCTP_PAD4(chunk->skb->len); 597 598 if (!sctp_chunk_is_data(chunk) && chunk != packet->auth) 599 sctp_chunk_free(chunk); 600 601 if (!pkt_size) 602 break; 603 } 604 605 /* SCTP-AUTH, Section 6.2 606 * The sender MUST calculate the MAC as described in RFC2104 [2] 607 * using the hash function H as described by the MAC Identifier and 608 * the shared association key K based on the endpoint pair shared key 609 * described by the shared key identifier. The 'data' used for the 610 * computation of the AUTH-chunk is given by the AUTH chunk with its 611 * HMAC field set to zero (as shown in Figure 6) followed by all 612 * chunks that are placed after the AUTH chunk in the SCTP packet. 613 */ 614 if (auth) 615 sctp_auth_calculate_hmac(asoc, nskb, 616 (struct sctp_auth_chunk *)auth, 617 gfp); 618 619 if (packet->auth) { 620 if (!list_empty(&packet->chunk_list)) { 621 /* We will generate more packets, so re-queue 622 * auth chunk. 623 */ 624 list_add(&packet->auth->list, 625 &packet->chunk_list); 626 } else { 627 sctp_chunk_free(packet->auth); 628 packet->auth = NULL; 629 } 630 } 631 632 if (!gso) 633 break; 634 635 if (skb_gro_receive(&head, nskb)) { 636 kfree_skb(nskb); 637 goto nomem; 638 } 639 nskb = NULL; 640 if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >= 641 sk->sk_gso_max_segs)) 642 goto nomem; 643 } while (!list_empty(&packet->chunk_list)); 644 645 /* 2) Calculate the Adler-32 checksum of the whole packet, 646 * including the SCTP common header and all the 647 * chunks. 648 * 649 * Note: Adler-32 is no longer applicable, as has been replaced 650 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. 651 * 652 * If it's a GSO packet, it's postponed to sctp_skb_segment. 653 */ 654 if (!sctp_checksum_disable || gso) { 655 if (!gso && (!(dst->dev->features & NETIF_F_SCTP_CRC) || 656 dst_xfrm(dst) || packet->ipfragok)) { 657 sh->checksum = sctp_compute_cksum(head, 0); 658 } else { 659 /* no need to seed pseudo checksum for SCTP */ 660 head->ip_summed = CHECKSUM_PARTIAL; 661 head->csum_start = skb_transport_header(head) - head->head; 662 head->csum_offset = offsetof(struct sctphdr, checksum); 663 } 664 } 665 666 /* IP layer ECN support 667 * From RFC 2481 668 * "The ECN-Capable Transport (ECT) bit would be set by the 669 * data sender to indicate that the end-points of the 670 * transport protocol are ECN-capable." 671 * 672 * Now setting the ECT bit all the time, as it should not cause 673 * any problems protocol-wise even if our peer ignores it. 674 * 675 * Note: The works for IPv6 layer checks this bit too later 676 * in transmission. See IP6_ECN_flow_xmit(). 677 */ 678 tp->af_specific->ecn_capable(sk); 679 680 /* Set up the IP options. */ 681 /* BUG: not implemented 682 * For v4 this all lives somewhere in sk->sk_opt... 683 */ 684 685 /* Dump that on IP! */ 686 if (asoc) { 687 asoc->stats.opackets += pktcount; 688 if (asoc->peer.last_sent_to != tp) 689 /* Considering the multiple CPU scenario, this is a 690 * "correcter" place for last_sent_to. --xguo 691 */ 692 asoc->peer.last_sent_to = tp; 693 } 694 695 if (has_data) { 696 struct timer_list *timer; 697 unsigned long timeout; 698 699 /* Restart the AUTOCLOSE timer when sending data. */ 700 if (sctp_state(asoc, ESTABLISHED) && 701 asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) { 702 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 703 timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 704 705 if (!mod_timer(timer, jiffies + timeout)) 706 sctp_association_hold(asoc); 707 } 708 } 709 710 pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len); 711 712 if (gso) { 713 /* Cleanup our debris for IP stacks */ 714 memset(head->cb, 0, max(sizeof(struct inet_skb_parm), 715 sizeof(struct inet6_skb_parm))); 716 717 skb_shinfo(head)->gso_segs = pktcount; 718 skb_shinfo(head)->gso_size = GSO_BY_FRAGS; 719 720 /* We have to refresh this in case we are xmiting to 721 * more than one transport at a time 722 */ 723 rcu_read_lock(); 724 if (__sk_dst_get(sk) != tp->dst) { 725 dst_hold(tp->dst); 726 sk_setup_caps(sk, tp->dst); 727 } 728 rcu_read_unlock(); 729 } 730 head->ignore_df = packet->ipfragok; 731 tp->af_specific->sctp_xmit(head, tp); 732 goto out; 733 734 nomem: 735 if (packet->auth && list_empty(&packet->auth->list)) 736 sctp_chunk_free(packet->auth); 737 738 nodst: 739 /* FIXME: Returning the 'err' will effect all the associations 740 * associated with a socket, although only one of the paths of the 741 * association is unreachable. 742 * The real failure of a transport or association can be passed on 743 * to the user via notifications. So setting this error may not be 744 * required. 745 */ 746 /* err = -EHOSTUNREACH; */ 747 kfree_skb(head); 748 749 err: 750 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 751 list_del_init(&chunk->list); 752 if (!sctp_chunk_is_data(chunk)) 753 sctp_chunk_free(chunk); 754 } 755 756 out: 757 sctp_packet_reset(packet); 758 return err; 759 } 760 761 /******************************************************************** 762 * 2nd Level Abstractions 763 ********************************************************************/ 764 765 /* This private function check to see if a chunk can be added */ 766 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 767 struct sctp_chunk *chunk) 768 { 769 size_t datasize, rwnd, inflight, flight_size; 770 struct sctp_transport *transport = packet->transport; 771 struct sctp_association *asoc = transport->asoc; 772 struct sctp_outq *q = &asoc->outqueue; 773 774 /* RFC 2960 6.1 Transmission of DATA Chunks 775 * 776 * A) At any given time, the data sender MUST NOT transmit new data to 777 * any destination transport address if its peer's rwnd indicates 778 * that the peer has no buffer space (i.e. rwnd is 0, see Section 779 * 6.2.1). However, regardless of the value of rwnd (including if it 780 * is 0), the data sender can always have one DATA chunk in flight to 781 * the receiver if allowed by cwnd (see rule B below). This rule 782 * allows the sender to probe for a change in rwnd that the sender 783 * missed due to the SACK having been lost in transit from the data 784 * receiver to the data sender. 785 */ 786 787 rwnd = asoc->peer.rwnd; 788 inflight = q->outstanding_bytes; 789 flight_size = transport->flight_size; 790 791 datasize = sctp_data_size(chunk); 792 793 if (datasize > rwnd && inflight > 0) 794 /* We have (at least) one data chunk in flight, 795 * so we can't fall back to rule 6.1 B). 796 */ 797 return SCTP_XMIT_RWND_FULL; 798 799 /* RFC 2960 6.1 Transmission of DATA Chunks 800 * 801 * B) At any given time, the sender MUST NOT transmit new data 802 * to a given transport address if it has cwnd or more bytes 803 * of data outstanding to that transport address. 804 */ 805 /* RFC 7.2.4 & the Implementers Guide 2.8. 806 * 807 * 3) ... 808 * When a Fast Retransmit is being performed the sender SHOULD 809 * ignore the value of cwnd and SHOULD NOT delay retransmission. 810 */ 811 if (chunk->fast_retransmit != SCTP_NEED_FRTX && 812 flight_size >= transport->cwnd) 813 return SCTP_XMIT_RWND_FULL; 814 815 /* Nagle's algorithm to solve small-packet problem: 816 * Inhibit the sending of new chunks when new outgoing data arrives 817 * if any previously transmitted data on the connection remains 818 * unacknowledged. 819 */ 820 821 if (sctp_sk(asoc->base.sk)->nodelay) 822 /* Nagle disabled */ 823 return SCTP_XMIT_OK; 824 825 if (!sctp_packet_empty(packet)) 826 /* Append to packet */ 827 return SCTP_XMIT_OK; 828 829 if (inflight == 0) 830 /* Nothing unacked */ 831 return SCTP_XMIT_OK; 832 833 if (!sctp_state(asoc, ESTABLISHED)) 834 return SCTP_XMIT_OK; 835 836 /* Check whether this chunk and all the rest of pending data will fit 837 * or delay in hopes of bundling a full sized packet. 838 */ 839 if (chunk->skb->len + q->out_qlen > 840 transport->pathmtu - packet->overhead - sizeof(sctp_data_chunk_t) - 4) 841 /* Enough data queued to fill a packet */ 842 return SCTP_XMIT_OK; 843 844 /* Don't delay large message writes that may have been fragmented */ 845 if (!chunk->msg->can_delay) 846 return SCTP_XMIT_OK; 847 848 /* Defer until all data acked or packet full */ 849 return SCTP_XMIT_DELAY; 850 } 851 852 /* This private function does management things when adding DATA chunk */ 853 static void sctp_packet_append_data(struct sctp_packet *packet, 854 struct sctp_chunk *chunk) 855 { 856 struct sctp_transport *transport = packet->transport; 857 size_t datasize = sctp_data_size(chunk); 858 struct sctp_association *asoc = transport->asoc; 859 u32 rwnd = asoc->peer.rwnd; 860 861 /* Keep track of how many bytes are in flight over this transport. */ 862 transport->flight_size += datasize; 863 864 /* Keep track of how many bytes are in flight to the receiver. */ 865 asoc->outqueue.outstanding_bytes += datasize; 866 867 /* Update our view of the receiver's rwnd. */ 868 if (datasize < rwnd) 869 rwnd -= datasize; 870 else 871 rwnd = 0; 872 873 asoc->peer.rwnd = rwnd; 874 /* Has been accepted for transmission. */ 875 if (!asoc->peer.prsctp_capable) 876 chunk->msg->can_abandon = 0; 877 sctp_chunk_assign_tsn(chunk); 878 sctp_chunk_assign_ssn(chunk); 879 } 880 881 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 882 struct sctp_chunk *chunk, 883 u16 chunk_len) 884 { 885 size_t psize, pmtu, maxsize; 886 sctp_xmit_t retval = SCTP_XMIT_OK; 887 888 psize = packet->size; 889 if (packet->transport->asoc) 890 pmtu = packet->transport->asoc->pathmtu; 891 else 892 pmtu = packet->transport->pathmtu; 893 894 /* Decide if we need to fragment or resubmit later. */ 895 if (psize + chunk_len > pmtu) { 896 /* It's OK to fragment at IP level if any one of the following 897 * is true: 898 * 1. The packet is empty (meaning this chunk is greater 899 * the MTU) 900 * 2. The packet doesn't have any data in it yet and data 901 * requires authentication. 902 */ 903 if (sctp_packet_empty(packet) || 904 (!packet->has_data && chunk->auth)) { 905 /* We no longer do re-fragmentation. 906 * Just fragment at the IP layer, if we 907 * actually hit this condition 908 */ 909 packet->ipfragok = 1; 910 goto out; 911 } 912 913 /* Similarly, if this chunk was built before a PMTU 914 * reduction, we have to fragment it at IP level now. So 915 * if the packet already contains something, we need to 916 * flush. 917 */ 918 maxsize = pmtu - packet->overhead; 919 if (packet->auth) 920 maxsize -= SCTP_PAD4(packet->auth->skb->len); 921 if (chunk_len > maxsize) 922 retval = SCTP_XMIT_PMTU_FULL; 923 924 /* It is also okay to fragment if the chunk we are 925 * adding is a control chunk, but only if current packet 926 * is not a GSO one otherwise it causes fragmentation of 927 * a large frame. So in this case we allow the 928 * fragmentation by forcing it to be in a new packet. 929 */ 930 if (!sctp_chunk_is_data(chunk) && packet->has_data) 931 retval = SCTP_XMIT_PMTU_FULL; 932 933 if (psize + chunk_len > packet->max_size) 934 /* Hit GSO/PMTU limit, gotta flush */ 935 retval = SCTP_XMIT_PMTU_FULL; 936 937 if (!packet->transport->burst_limited && 938 psize + chunk_len > (packet->transport->cwnd >> 1)) 939 /* Do not allow a single GSO packet to use more 940 * than half of cwnd. 941 */ 942 retval = SCTP_XMIT_PMTU_FULL; 943 944 if (packet->transport->burst_limited && 945 psize + chunk_len > (packet->transport->burst_limited >> 1)) 946 /* Do not allow a single GSO packet to use more 947 * than half of original cwnd. 948 */ 949 retval = SCTP_XMIT_PMTU_FULL; 950 /* Otherwise it will fit in the GSO packet */ 951 } 952 953 out: 954 return retval; 955 } 956