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 int error = 0; 184 185 pr_debug("%s: packet:%p size:%Zu chunk:%p size:%d\n", __func__, 186 packet, packet->size, chunk, chunk->skb ? chunk->skb->len : -1); 187 188 switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { 189 case SCTP_XMIT_PMTU_FULL: 190 if (!packet->has_cookie_echo) { 191 error = sctp_packet_transmit(packet, gfp); 192 if (error < 0) 193 chunk->skb->sk->sk_err = -error; 194 195 /* If we have an empty packet, then we can NOT ever 196 * return PMTU_FULL. 197 */ 198 if (!one_packet) 199 retval = sctp_packet_append_chunk(packet, 200 chunk); 201 } 202 break; 203 204 case SCTP_XMIT_RWND_FULL: 205 case SCTP_XMIT_OK: 206 case SCTP_XMIT_DELAY: 207 break; 208 } 209 210 return retval; 211 } 212 213 /* Try to bundle an auth chunk into the packet. */ 214 static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, 215 struct sctp_chunk *chunk) 216 { 217 struct sctp_association *asoc = pkt->transport->asoc; 218 struct sctp_chunk *auth; 219 sctp_xmit_t retval = SCTP_XMIT_OK; 220 221 /* if we don't have an association, we can't do authentication */ 222 if (!asoc) 223 return retval; 224 225 /* See if this is an auth chunk we are bundling or if 226 * auth is already bundled. 227 */ 228 if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth) 229 return retval; 230 231 /* if the peer did not request this chunk to be authenticated, 232 * don't do it 233 */ 234 if (!chunk->auth) 235 return retval; 236 237 auth = sctp_make_auth(asoc); 238 if (!auth) 239 return retval; 240 241 retval = __sctp_packet_append_chunk(pkt, auth); 242 243 if (retval != SCTP_XMIT_OK) 244 sctp_chunk_free(auth); 245 246 return retval; 247 } 248 249 /* Try to bundle a SACK with the packet. */ 250 static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, 251 struct sctp_chunk *chunk) 252 { 253 sctp_xmit_t retval = SCTP_XMIT_OK; 254 255 /* If sending DATA and haven't aleady bundled a SACK, try to 256 * bundle one in to the packet. 257 */ 258 if (sctp_chunk_is_data(chunk) && !pkt->has_sack && 259 !pkt->has_cookie_echo) { 260 struct sctp_association *asoc; 261 struct timer_list *timer; 262 asoc = pkt->transport->asoc; 263 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; 264 265 /* If the SACK timer is running, we have a pending SACK */ 266 if (timer_pending(timer)) { 267 struct sctp_chunk *sack; 268 269 if (pkt->transport->sack_generation != 270 pkt->transport->asoc->peer.sack_generation) 271 return retval; 272 273 asoc->a_rwnd = asoc->rwnd; 274 sack = sctp_make_sack(asoc); 275 if (sack) { 276 retval = __sctp_packet_append_chunk(pkt, sack); 277 if (retval != SCTP_XMIT_OK) { 278 sctp_chunk_free(sack); 279 goto out; 280 } 281 asoc->peer.sack_needed = 0; 282 if (del_timer(timer)) 283 sctp_association_put(asoc); 284 } 285 } 286 } 287 out: 288 return retval; 289 } 290 291 292 /* Append a chunk to the offered packet reporting back any inability to do 293 * so. 294 */ 295 static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet, 296 struct sctp_chunk *chunk) 297 { 298 sctp_xmit_t retval = SCTP_XMIT_OK; 299 __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); 300 301 /* Check to see if this chunk will fit into the packet */ 302 retval = sctp_packet_will_fit(packet, chunk, chunk_len); 303 if (retval != SCTP_XMIT_OK) 304 goto finish; 305 306 /* We believe that this chunk is OK to add to the packet */ 307 switch (chunk->chunk_hdr->type) { 308 case SCTP_CID_DATA: 309 /* Account for the data being in the packet */ 310 sctp_packet_append_data(packet, chunk); 311 /* Disallow SACK bundling after DATA. */ 312 packet->has_sack = 1; 313 /* Disallow AUTH bundling after DATA */ 314 packet->has_auth = 1; 315 /* Let it be knows that packet has DATA in it */ 316 packet->has_data = 1; 317 /* timestamp the chunk for rtx purposes */ 318 chunk->sent_at = jiffies; 319 /* Mainly used for prsctp RTX policy */ 320 chunk->sent_count++; 321 break; 322 case SCTP_CID_COOKIE_ECHO: 323 packet->has_cookie_echo = 1; 324 break; 325 326 case SCTP_CID_SACK: 327 packet->has_sack = 1; 328 if (chunk->asoc) 329 chunk->asoc->stats.osacks++; 330 break; 331 332 case SCTP_CID_AUTH: 333 packet->has_auth = 1; 334 packet->auth = chunk; 335 break; 336 } 337 338 /* It is OK to send this chunk. */ 339 list_add_tail(&chunk->list, &packet->chunk_list); 340 packet->size += chunk_len; 341 chunk->transport = packet->transport; 342 finish: 343 return retval; 344 } 345 346 /* Append a chunk to the offered packet reporting back any inability to do 347 * so. 348 */ 349 sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, 350 struct sctp_chunk *chunk) 351 { 352 sctp_xmit_t retval = SCTP_XMIT_OK; 353 354 pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk); 355 356 /* Data chunks are special. Before seeing what else we can 357 * bundle into this packet, check to see if we are allowed to 358 * send this DATA. 359 */ 360 if (sctp_chunk_is_data(chunk)) { 361 retval = sctp_packet_can_append_data(packet, chunk); 362 if (retval != SCTP_XMIT_OK) 363 goto finish; 364 } 365 366 /* Try to bundle AUTH chunk */ 367 retval = sctp_packet_bundle_auth(packet, chunk); 368 if (retval != SCTP_XMIT_OK) 369 goto finish; 370 371 /* Try to bundle SACK chunk */ 372 retval = sctp_packet_bundle_sack(packet, chunk); 373 if (retval != SCTP_XMIT_OK) 374 goto finish; 375 376 retval = __sctp_packet_append_chunk(packet, chunk); 377 378 finish: 379 return retval; 380 } 381 382 static void sctp_packet_release_owner(struct sk_buff *skb) 383 { 384 sk_free(skb->sk); 385 } 386 387 static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk) 388 { 389 skb_orphan(skb); 390 skb->sk = sk; 391 skb->destructor = sctp_packet_release_owner; 392 393 /* 394 * The data chunks have already been accounted for in sctp_sendmsg(), 395 * therefore only reserve a single byte to keep socket around until 396 * the packet has been transmitted. 397 */ 398 atomic_inc(&sk->sk_wmem_alloc); 399 } 400 401 /* All packets are sent to the network through this function from 402 * sctp_outq_tail(). 403 * 404 * The return value is a normal kernel error return value. 405 */ 406 int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) 407 { 408 struct sctp_transport *tp = packet->transport; 409 struct sctp_association *asoc = tp->asoc; 410 struct sctphdr *sh; 411 struct sk_buff *nskb = NULL, *head = NULL; 412 struct sctp_chunk *chunk, *tmp; 413 struct sock *sk; 414 int err = 0; 415 int padding; /* How much padding do we need? */ 416 int pkt_size; 417 __u8 has_data = 0; 418 int gso = 0; 419 int pktcount = 0; 420 struct dst_entry *dst; 421 unsigned char *auth = NULL; /* pointer to auth in skb data */ 422 423 pr_debug("%s: packet:%p\n", __func__, packet); 424 425 /* Do NOT generate a chunkless packet. */ 426 if (list_empty(&packet->chunk_list)) 427 return err; 428 429 /* Set up convenience variables... */ 430 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 431 sk = chunk->skb->sk; 432 433 /* Allocate the head skb, or main one if not in GSO */ 434 if (packet->size > tp->pathmtu && !packet->ipfragok) { 435 if (sk_can_gso(sk)) { 436 gso = 1; 437 pkt_size = packet->overhead; 438 } else { 439 /* If this happens, we trash this packet and try 440 * to build a new one, hopefully correct this 441 * time. Application may notice this error. 442 */ 443 pr_err_once("Trying to GSO but underlying device doesn't support it."); 444 goto nomem; 445 } 446 } else { 447 pkt_size = packet->size; 448 } 449 head = alloc_skb(pkt_size + MAX_HEADER, gfp); 450 if (!head) 451 goto nomem; 452 if (gso) { 453 NAPI_GRO_CB(head)->last = head; 454 skb_shinfo(head)->gso_type = sk->sk_gso_type; 455 } 456 457 /* Make sure the outbound skb has enough header room reserved. */ 458 skb_reserve(head, packet->overhead + MAX_HEADER); 459 460 /* Set the owning socket so that we know where to get the 461 * destination IP address. 462 */ 463 sctp_packet_set_owner_w(head, sk); 464 465 if (!sctp_transport_dst_check(tp)) { 466 sctp_transport_route(tp, NULL, sctp_sk(sk)); 467 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { 468 sctp_assoc_sync_pmtu(sk, asoc); 469 } 470 } 471 dst = dst_clone(tp->dst); 472 if (!dst) 473 goto no_route; 474 skb_dst_set(head, dst); 475 476 /* Build the SCTP header. */ 477 sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr)); 478 skb_reset_transport_header(head); 479 sh->source = htons(packet->source_port); 480 sh->dest = htons(packet->destination_port); 481 482 /* From 6.8 Adler-32 Checksum Calculation: 483 * After the packet is constructed (containing the SCTP common 484 * header and one or more control or DATA chunks), the 485 * transmitter shall: 486 * 487 * 1) Fill in the proper Verification Tag in the SCTP common 488 * header and initialize the checksum field to 0's. 489 */ 490 sh->vtag = htonl(packet->vtag); 491 sh->checksum = 0; 492 493 pr_debug("***sctp_transmit_packet***\n"); 494 495 do { 496 /* Set up convenience variables... */ 497 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); 498 pktcount++; 499 500 /* Calculate packet size, so it fits in PMTU. Leave 501 * other chunks for the next packets. 502 */ 503 if (gso) { 504 pkt_size = packet->overhead; 505 list_for_each_entry(chunk, &packet->chunk_list, list) { 506 int padded = WORD_ROUND(chunk->skb->len); 507 508 if (pkt_size + padded > tp->pathmtu) 509 break; 510 pkt_size += padded; 511 } 512 513 /* Allocate a new skb. */ 514 nskb = alloc_skb(pkt_size + MAX_HEADER, gfp); 515 if (!nskb) 516 goto nomem; 517 518 /* Make sure the outbound skb has enough header 519 * room reserved. 520 */ 521 skb_reserve(nskb, packet->overhead + MAX_HEADER); 522 } else { 523 nskb = head; 524 } 525 526 /** 527 * 3.2 Chunk Field Descriptions 528 * 529 * The total length of a chunk (including Type, Length and 530 * Value fields) MUST be a multiple of 4 bytes. If the length 531 * of the chunk is not a multiple of 4 bytes, the sender MUST 532 * pad the chunk with all zero bytes and this padding is not 533 * included in the chunk length field. The sender should 534 * never pad with more than 3 bytes. 535 * 536 * [This whole comment explains WORD_ROUND() below.] 537 */ 538 539 pkt_size -= packet->overhead; 540 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 541 list_del_init(&chunk->list); 542 if (sctp_chunk_is_data(chunk)) { 543 /* 6.3.1 C4) When data is in flight and when allowed 544 * by rule C5, a new RTT measurement MUST be made each 545 * round trip. Furthermore, new RTT measurements 546 * SHOULD be made no more than once per round-trip 547 * for a given destination transport address. 548 */ 549 550 if (!chunk->resent && !tp->rto_pending) { 551 chunk->rtt_in_progress = 1; 552 tp->rto_pending = 1; 553 } 554 555 has_data = 1; 556 } 557 558 padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; 559 if (padding) 560 memset(skb_put(chunk->skb, padding), 0, padding); 561 562 /* if this is the auth chunk that we are adding, 563 * store pointer where it will be added and put 564 * the auth into the packet. 565 */ 566 if (chunk == packet->auth) 567 auth = skb_tail_pointer(nskb); 568 569 memcpy(skb_put(nskb, chunk->skb->len), 570 chunk->skb->data, chunk->skb->len); 571 572 pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n", 573 chunk, 574 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)), 575 chunk->has_tsn ? "TSN" : "No TSN", 576 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0, 577 ntohs(chunk->chunk_hdr->length), chunk->skb->len, 578 chunk->rtt_in_progress); 579 580 /* If this is a control chunk, this is our last 581 * reference. Free data chunks after they've been 582 * acknowledged or have failed. 583 * Re-queue auth chunks if needed. 584 */ 585 pkt_size -= WORD_ROUND(chunk->skb->len); 586 587 if (!sctp_chunk_is_data(chunk) && chunk != packet->auth) 588 sctp_chunk_free(chunk); 589 590 if (!pkt_size) 591 break; 592 } 593 594 /* SCTP-AUTH, Section 6.2 595 * The sender MUST calculate the MAC as described in RFC2104 [2] 596 * using the hash function H as described by the MAC Identifier and 597 * the shared association key K based on the endpoint pair shared key 598 * described by the shared key identifier. The 'data' used for the 599 * computation of the AUTH-chunk is given by the AUTH chunk with its 600 * HMAC field set to zero (as shown in Figure 6) followed by all 601 * chunks that are placed after the AUTH chunk in the SCTP packet. 602 */ 603 if (auth) 604 sctp_auth_calculate_hmac(asoc, nskb, 605 (struct sctp_auth_chunk *)auth, 606 gfp); 607 608 if (packet->auth) { 609 if (!list_empty(&packet->chunk_list)) { 610 /* We will generate more packets, so re-queue 611 * auth chunk. 612 */ 613 list_add(&packet->auth->list, 614 &packet->chunk_list); 615 } else { 616 sctp_chunk_free(packet->auth); 617 packet->auth = NULL; 618 } 619 } 620 621 if (!gso) 622 break; 623 624 if (skb_gro_receive(&head, nskb)) 625 goto nomem; 626 nskb = NULL; 627 if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >= 628 sk->sk_gso_max_segs)) 629 goto nomem; 630 } while (!list_empty(&packet->chunk_list)); 631 632 /* 2) Calculate the Adler-32 checksum of the whole packet, 633 * including the SCTP common header and all the 634 * chunks. 635 * 636 * Note: Adler-32 is no longer applicable, as has been replaced 637 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. 638 * 639 * If it's a GSO packet, it's postponed to sctp_skb_segment. 640 */ 641 if (!sctp_checksum_disable || gso) { 642 if (!gso && (!(dst->dev->features & NETIF_F_SCTP_CRC) || 643 dst_xfrm(dst) || packet->ipfragok)) { 644 sh->checksum = sctp_compute_cksum(head, 0); 645 } else { 646 /* no need to seed pseudo checksum for SCTP */ 647 head->ip_summed = CHECKSUM_PARTIAL; 648 head->csum_start = skb_transport_header(head) - head->head; 649 head->csum_offset = offsetof(struct sctphdr, checksum); 650 } 651 } 652 653 /* IP layer ECN support 654 * From RFC 2481 655 * "The ECN-Capable Transport (ECT) bit would be set by the 656 * data sender to indicate that the end-points of the 657 * transport protocol are ECN-capable." 658 * 659 * Now setting the ECT bit all the time, as it should not cause 660 * any problems protocol-wise even if our peer ignores it. 661 * 662 * Note: The works for IPv6 layer checks this bit too later 663 * in transmission. See IP6_ECN_flow_xmit(). 664 */ 665 tp->af_specific->ecn_capable(sk); 666 667 /* Set up the IP options. */ 668 /* BUG: not implemented 669 * For v4 this all lives somewhere in sk->sk_opt... 670 */ 671 672 /* Dump that on IP! */ 673 if (asoc) { 674 asoc->stats.opackets += pktcount; 675 if (asoc->peer.last_sent_to != tp) 676 /* Considering the multiple CPU scenario, this is a 677 * "correcter" place for last_sent_to. --xguo 678 */ 679 asoc->peer.last_sent_to = tp; 680 } 681 682 if (has_data) { 683 struct timer_list *timer; 684 unsigned long timeout; 685 686 /* Restart the AUTOCLOSE timer when sending data. */ 687 if (sctp_state(asoc, ESTABLISHED) && 688 asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) { 689 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 690 timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; 691 692 if (!mod_timer(timer, jiffies + timeout)) 693 sctp_association_hold(asoc); 694 } 695 } 696 697 pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len); 698 699 if (gso) { 700 /* Cleanup our debris for IP stacks */ 701 memset(head->cb, 0, max(sizeof(struct inet_skb_parm), 702 sizeof(struct inet6_skb_parm))); 703 704 skb_shinfo(head)->gso_segs = pktcount; 705 skb_shinfo(head)->gso_size = GSO_BY_FRAGS; 706 707 /* We have to refresh this in case we are xmiting to 708 * more than one transport at a time 709 */ 710 rcu_read_lock(); 711 if (__sk_dst_get(sk) != tp->dst) { 712 dst_hold(tp->dst); 713 sk_setup_caps(sk, tp->dst); 714 } 715 rcu_read_unlock(); 716 } 717 head->ignore_df = packet->ipfragok; 718 tp->af_specific->sctp_xmit(head, tp); 719 720 out: 721 sctp_packet_reset(packet); 722 return err; 723 no_route: 724 kfree_skb(head); 725 if (nskb != head) 726 kfree_skb(nskb); 727 728 if (asoc) 729 IP_INC_STATS(sock_net(asoc->base.sk), IPSTATS_MIB_OUTNOROUTES); 730 731 /* FIXME: Returning the 'err' will effect all the associations 732 * associated with a socket, although only one of the paths of the 733 * association is unreachable. 734 * The real failure of a transport or association can be passed on 735 * to the user via notifications. So setting this error may not be 736 * required. 737 */ 738 /* err = -EHOSTUNREACH; */ 739 err: 740 /* Control chunks are unreliable so just drop them. DATA chunks 741 * will get resent or dropped later. 742 */ 743 744 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { 745 list_del_init(&chunk->list); 746 if (!sctp_chunk_is_data(chunk)) 747 sctp_chunk_free(chunk); 748 } 749 goto out; 750 nomem: 751 if (packet->auth && list_empty(&packet->auth->list)) 752 sctp_chunk_free(packet->auth); 753 err = -ENOMEM; 754 goto err; 755 } 756 757 /******************************************************************** 758 * 2nd Level Abstractions 759 ********************************************************************/ 760 761 /* This private function check to see if a chunk can be added */ 762 static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 763 struct sctp_chunk *chunk) 764 { 765 size_t datasize, rwnd, inflight, flight_size; 766 struct sctp_transport *transport = packet->transport; 767 struct sctp_association *asoc = transport->asoc; 768 struct sctp_outq *q = &asoc->outqueue; 769 770 /* RFC 2960 6.1 Transmission of DATA Chunks 771 * 772 * A) At any given time, the data sender MUST NOT transmit new data to 773 * any destination transport address if its peer's rwnd indicates 774 * that the peer has no buffer space (i.e. rwnd is 0, see Section 775 * 6.2.1). However, regardless of the value of rwnd (including if it 776 * is 0), the data sender can always have one DATA chunk in flight to 777 * the receiver if allowed by cwnd (see rule B below). This rule 778 * allows the sender to probe for a change in rwnd that the sender 779 * missed due to the SACK having been lost in transit from the data 780 * receiver to the data sender. 781 */ 782 783 rwnd = asoc->peer.rwnd; 784 inflight = q->outstanding_bytes; 785 flight_size = transport->flight_size; 786 787 datasize = sctp_data_size(chunk); 788 789 if (datasize > rwnd && inflight > 0) 790 /* We have (at least) one data chunk in flight, 791 * so we can't fall back to rule 6.1 B). 792 */ 793 return SCTP_XMIT_RWND_FULL; 794 795 /* RFC 2960 6.1 Transmission of DATA Chunks 796 * 797 * B) At any given time, the sender MUST NOT transmit new data 798 * to a given transport address if it has cwnd or more bytes 799 * of data outstanding to that transport address. 800 */ 801 /* RFC 7.2.4 & the Implementers Guide 2.8. 802 * 803 * 3) ... 804 * When a Fast Retransmit is being performed the sender SHOULD 805 * ignore the value of cwnd and SHOULD NOT delay retransmission. 806 */ 807 if (chunk->fast_retransmit != SCTP_NEED_FRTX && 808 flight_size >= transport->cwnd) 809 return SCTP_XMIT_RWND_FULL; 810 811 /* Nagle's algorithm to solve small-packet problem: 812 * Inhibit the sending of new chunks when new outgoing data arrives 813 * if any previously transmitted data on the connection remains 814 * unacknowledged. 815 */ 816 817 if (sctp_sk(asoc->base.sk)->nodelay) 818 /* Nagle disabled */ 819 return SCTP_XMIT_OK; 820 821 if (!sctp_packet_empty(packet)) 822 /* Append to packet */ 823 return SCTP_XMIT_OK; 824 825 if (inflight == 0) 826 /* Nothing unacked */ 827 return SCTP_XMIT_OK; 828 829 if (!sctp_state(asoc, ESTABLISHED)) 830 return SCTP_XMIT_OK; 831 832 /* Check whether this chunk and all the rest of pending data will fit 833 * or delay in hopes of bundling a full sized packet. 834 */ 835 if (chunk->skb->len + q->out_qlen > 836 transport->pathmtu - packet->overhead - sizeof(sctp_data_chunk_t) - 4) 837 /* Enough data queued to fill a packet */ 838 return SCTP_XMIT_OK; 839 840 /* Don't delay large message writes that may have been fragmented */ 841 if (!chunk->msg->can_delay) 842 return SCTP_XMIT_OK; 843 844 /* Defer until all data acked or packet full */ 845 return SCTP_XMIT_DELAY; 846 } 847 848 /* This private function does management things when adding DATA chunk */ 849 static void sctp_packet_append_data(struct sctp_packet *packet, 850 struct sctp_chunk *chunk) 851 { 852 struct sctp_transport *transport = packet->transport; 853 size_t datasize = sctp_data_size(chunk); 854 struct sctp_association *asoc = transport->asoc; 855 u32 rwnd = asoc->peer.rwnd; 856 857 /* Keep track of how many bytes are in flight over this transport. */ 858 transport->flight_size += datasize; 859 860 /* Keep track of how many bytes are in flight to the receiver. */ 861 asoc->outqueue.outstanding_bytes += datasize; 862 863 /* Update our view of the receiver's rwnd. */ 864 if (datasize < rwnd) 865 rwnd -= datasize; 866 else 867 rwnd = 0; 868 869 asoc->peer.rwnd = rwnd; 870 /* Has been accepted for transmission. */ 871 if (!asoc->peer.prsctp_capable) 872 chunk->msg->can_abandon = 0; 873 sctp_chunk_assign_tsn(chunk); 874 sctp_chunk_assign_ssn(chunk); 875 } 876 877 static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, 878 struct sctp_chunk *chunk, 879 u16 chunk_len) 880 { 881 size_t psize, pmtu; 882 sctp_xmit_t retval = SCTP_XMIT_OK; 883 884 psize = packet->size; 885 if (packet->transport->asoc) 886 pmtu = packet->transport->asoc->pathmtu; 887 else 888 pmtu = packet->transport->pathmtu; 889 890 /* Decide if we need to fragment or resubmit later. */ 891 if (psize + chunk_len > pmtu) { 892 /* It's OK to fragment at IP level if any one of the following 893 * is true: 894 * 1. The packet is empty (meaning this chunk is greater 895 * the MTU) 896 * 2. The packet doesn't have any data in it yet and data 897 * requires authentication. 898 */ 899 if (sctp_packet_empty(packet) || 900 (!packet->has_data && chunk->auth)) { 901 /* We no longer do re-fragmentation. 902 * Just fragment at the IP layer, if we 903 * actually hit this condition 904 */ 905 packet->ipfragok = 1; 906 goto out; 907 } 908 909 /* It is also okay to fragment if the chunk we are 910 * adding is a control chunk, but only if current packet 911 * is not a GSO one otherwise it causes fragmentation of 912 * a large frame. So in this case we allow the 913 * fragmentation by forcing it to be in a new packet. 914 */ 915 if (!sctp_chunk_is_data(chunk) && packet->has_data) 916 retval = SCTP_XMIT_PMTU_FULL; 917 918 if (psize + chunk_len > packet->max_size) 919 /* Hit GSO/PMTU limit, gotta flush */ 920 retval = SCTP_XMIT_PMTU_FULL; 921 922 if (!packet->transport->burst_limited && 923 psize + chunk_len > (packet->transport->cwnd >> 1)) 924 /* Do not allow a single GSO packet to use more 925 * than half of cwnd. 926 */ 927 retval = SCTP_XMIT_PMTU_FULL; 928 929 if (packet->transport->burst_limited && 930 psize + chunk_len > (packet->transport->burst_limited >> 1)) 931 /* Do not allow a single GSO packet to use more 932 * than half of original cwnd. 933 */ 934 retval = SCTP_XMIT_PMTU_FULL; 935 /* Otherwise it will fit in the GSO packet */ 936 } 937 938 out: 939 return retval; 940 } 941