1 /* SCTP kernel reference Implementation 2 * Copyright (c) 1999-2000 Cisco, Inc. 3 * Copyright (c) 1999-2001 Motorola, Inc. 4 * Copyright (c) 2001-2003 International Business Machines, Corp. 5 * Copyright (c) 2001 Intel Corp. 6 * Copyright (c) 2001 Nokia, Inc. 7 * Copyright (c) 2001 La Monte H.P. Yarroll 8 * 9 * This file is part of the SCTP kernel reference Implementation 10 * 11 * These functions handle all input from the IP layer into SCTP. 12 * 13 * The SCTP reference implementation is free software; 14 * you can redistribute it and/or modify it under the terms of 15 * the GNU General Public License as published by 16 * the Free Software Foundation; either version 2, or (at your option) 17 * any later version. 18 * 19 * The SCTP reference implementation is distributed in the hope that it 20 * will be useful, but WITHOUT ANY WARRANTY; without even the implied 21 * ************************ 22 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 23 * See the GNU General Public License for more details. 24 * 25 * You should have received a copy of the GNU General Public License 26 * along with GNU CC; see the file COPYING. If not, write to 27 * the Free Software Foundation, 59 Temple Place - Suite 330, 28 * Boston, MA 02111-1307, USA. 29 * 30 * Please send any bug reports or fixes you make to the 31 * email address(es): 32 * lksctp developers <lksctp-developers@lists.sourceforge.net> 33 * 34 * Or submit a bug report through the following website: 35 * http://www.sf.net/projects/lksctp 36 * 37 * Written or modified by: 38 * La Monte H.P. Yarroll <piggy@acm.org> 39 * Karl Knutson <karl@athena.chicago.il.us> 40 * Xingang Guo <xingang.guo@intel.com> 41 * Jon Grimm <jgrimm@us.ibm.com> 42 * Hui Huang <hui.huang@nokia.com> 43 * Daisy Chang <daisyc@us.ibm.com> 44 * Sridhar Samudrala <sri@us.ibm.com> 45 * Ardelle Fan <ardelle.fan@intel.com> 46 * 47 * Any bugs reported given to us we will try to fix... any fixes shared will 48 * be incorporated into the next SCTP release. 49 */ 50 51 #include <linux/types.h> 52 #include <linux/list.h> /* For struct list_head */ 53 #include <linux/socket.h> 54 #include <linux/ip.h> 55 #include <linux/time.h> /* For struct timeval */ 56 #include <net/ip.h> 57 #include <net/icmp.h> 58 #include <net/snmp.h> 59 #include <net/sock.h> 60 #include <net/xfrm.h> 61 #include <net/sctp/sctp.h> 62 #include <net/sctp/sm.h> 63 64 /* Forward declarations for internal helpers. */ 65 static int sctp_rcv_ootb(struct sk_buff *); 66 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 67 const union sctp_addr *laddr, 68 const union sctp_addr *paddr, 69 struct sctp_transport **transportp); 70 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr); 71 static struct sctp_association *__sctp_lookup_association( 72 const union sctp_addr *local, 73 const union sctp_addr *peer, 74 struct sctp_transport **pt); 75 76 77 /* Calculate the SCTP checksum of an SCTP packet. */ 78 static inline int sctp_rcv_checksum(struct sk_buff *skb) 79 { 80 struct sctphdr *sh; 81 __u32 cmp, val; 82 struct sk_buff *list = skb_shinfo(skb)->frag_list; 83 84 sh = (struct sctphdr *) skb->h.raw; 85 cmp = ntohl(sh->checksum); 86 87 val = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); 88 89 for (; list; list = list->next) 90 val = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), 91 val); 92 93 val = sctp_end_cksum(val); 94 95 if (val != cmp) { 96 /* CRC failure, dump it. */ 97 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); 98 return -1; 99 } 100 return 0; 101 } 102 103 /* The free routine for skbuffs that sctp receives */ 104 static void sctp_rfree(struct sk_buff *skb) 105 { 106 atomic_sub(sizeof(struct sctp_chunk),&skb->sk->sk_rmem_alloc); 107 sock_rfree(skb); 108 } 109 110 /* The ownership wrapper routine to do receive buffer accounting */ 111 static void sctp_rcv_set_owner_r(struct sk_buff *skb, struct sock *sk) 112 { 113 skb_set_owner_r(skb,sk); 114 skb->destructor = sctp_rfree; 115 atomic_add(sizeof(struct sctp_chunk),&sk->sk_rmem_alloc); 116 } 117 118 struct sctp_input_cb { 119 union { 120 struct inet_skb_parm h4; 121 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 122 struct inet6_skb_parm h6; 123 #endif 124 } header; 125 struct sctp_chunk *chunk; 126 }; 127 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 128 129 /* 130 * This is the routine which IP calls when receiving an SCTP packet. 131 */ 132 int sctp_rcv(struct sk_buff *skb) 133 { 134 struct sock *sk; 135 struct sctp_association *asoc; 136 struct sctp_endpoint *ep = NULL; 137 struct sctp_ep_common *rcvr; 138 struct sctp_transport *transport = NULL; 139 struct sctp_chunk *chunk; 140 struct sctphdr *sh; 141 union sctp_addr src; 142 union sctp_addr dest; 143 int family; 144 struct sctp_af *af; 145 int ret = 0; 146 147 if (skb->pkt_type!=PACKET_HOST) 148 goto discard_it; 149 150 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); 151 152 sh = (struct sctphdr *) skb->h.raw; 153 154 /* Pull up the IP and SCTP headers. */ 155 __skb_pull(skb, skb->h.raw - skb->data); 156 if (skb->len < sizeof(struct sctphdr)) 157 goto discard_it; 158 if (sctp_rcv_checksum(skb) < 0) 159 goto discard_it; 160 161 skb_pull(skb, sizeof(struct sctphdr)); 162 163 /* Make sure we at least have chunk headers worth of data left. */ 164 if (skb->len < sizeof(struct sctp_chunkhdr)) 165 goto discard_it; 166 167 family = ipver2af(skb->nh.iph->version); 168 af = sctp_get_af_specific(family); 169 if (unlikely(!af)) 170 goto discard_it; 171 172 /* Initialize local addresses for lookups. */ 173 af->from_skb(&src, skb, 1); 174 af->from_skb(&dest, skb, 0); 175 176 /* If the packet is to or from a non-unicast address, 177 * silently discard the packet. 178 * 179 * This is not clearly defined in the RFC except in section 180 * 8.4 - OOTB handling. However, based on the book "Stream Control 181 * Transmission Protocol" 2.1, "It is important to note that the 182 * IP address of an SCTP transport address must be a routable 183 * unicast address. In other words, IP multicast addresses and 184 * IP broadcast addresses cannot be used in an SCTP transport 185 * address." 186 */ 187 if (!af->addr_valid(&src, NULL) || !af->addr_valid(&dest, NULL)) 188 goto discard_it; 189 190 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); 191 192 if (!asoc) 193 ep = __sctp_rcv_lookup_endpoint(&dest); 194 195 /* Retrieve the common input handling substructure. */ 196 rcvr = asoc ? &asoc->base : &ep->base; 197 sk = rcvr->sk; 198 199 /* 200 * If a frame arrives on an interface and the receiving socket is 201 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 202 */ 203 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) 204 { 205 sock_put(sk); 206 if (asoc) { 207 sctp_association_put(asoc); 208 asoc = NULL; 209 } else { 210 sctp_endpoint_put(ep); 211 ep = NULL; 212 } 213 sk = sctp_get_ctl_sock(); 214 ep = sctp_sk(sk)->ep; 215 sctp_endpoint_hold(ep); 216 sock_hold(sk); 217 rcvr = &ep->base; 218 } 219 220 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) 221 goto discard_release; 222 223 /* 224 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 225 * An SCTP packet is called an "out of the blue" (OOTB) 226 * packet if it is correctly formed, i.e., passed the 227 * receiver's checksum check, but the receiver is not 228 * able to identify the association to which this 229 * packet belongs. 230 */ 231 if (!asoc) { 232 if (sctp_rcv_ootb(skb)) { 233 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); 234 goto discard_release; 235 } 236 } 237 238 /* SCTP seems to always need a timestamp right now (FIXME) */ 239 if (skb->tstamp.off_sec == 0) { 240 __net_timestamp(skb); 241 sock_enable_timestamp(sk); 242 } 243 244 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 245 goto discard_release; 246 247 ret = sk_filter(sk, skb, 1); 248 if (ret) 249 goto discard_release; 250 251 /* Create an SCTP packet structure. */ 252 chunk = sctp_chunkify(skb, asoc, sk); 253 if (!chunk) { 254 ret = -ENOMEM; 255 goto discard_release; 256 } 257 SCTP_INPUT_CB(skb)->chunk = chunk; 258 259 sctp_rcv_set_owner_r(skb,sk); 260 261 /* Remember what endpoint is to handle this packet. */ 262 chunk->rcvr = rcvr; 263 264 /* Remember the SCTP header. */ 265 chunk->sctp_hdr = sh; 266 267 /* Set the source and destination addresses of the incoming chunk. */ 268 sctp_init_addrs(chunk, &src, &dest); 269 270 /* Remember where we came from. */ 271 chunk->transport = transport; 272 273 /* Acquire access to the sock lock. Note: We are safe from other 274 * bottom halves on this lock, but a user may be in the lock too, 275 * so check if it is busy. 276 */ 277 sctp_bh_lock_sock(sk); 278 279 if (sock_owned_by_user(sk)) 280 sk_add_backlog(sk, skb); 281 else 282 sctp_backlog_rcv(sk, skb); 283 284 /* Release the sock and any reference counts we took in the 285 * lookup calls. 286 */ 287 sctp_bh_unlock_sock(sk); 288 if (asoc) 289 sctp_association_put(asoc); 290 else 291 sctp_endpoint_put(ep); 292 sock_put(sk); 293 return ret; 294 295 discard_it: 296 kfree_skb(skb); 297 return ret; 298 299 discard_release: 300 /* Release any structures we may be holding. */ 301 sock_put(sk); 302 if (asoc) 303 sctp_association_put(asoc); 304 else 305 sctp_endpoint_put(ep); 306 307 goto discard_it; 308 } 309 310 /* Handle second half of inbound skb processing. If the sock was busy, 311 * we may have need to delay processing until later when the sock is 312 * released (on the backlog). If not busy, we call this routine 313 * directly from the bottom half. 314 */ 315 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 316 { 317 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 318 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 319 320 sctp_inq_push(inqueue, chunk); 321 return 0; 322 } 323 324 /* Handle icmp frag needed error. */ 325 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 326 struct sctp_transport *t, __u32 pmtu) 327 { 328 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { 329 printk(KERN_WARNING "%s: Reported pmtu %d too low, " 330 "using default minimum of %d\n", __FUNCTION__, pmtu, 331 SCTP_DEFAULT_MINSEGMENT); 332 pmtu = SCTP_DEFAULT_MINSEGMENT; 333 } 334 335 if (!sock_owned_by_user(sk) && t && (t->pmtu != pmtu)) { 336 t->pmtu = pmtu; 337 sctp_assoc_sync_pmtu(asoc); 338 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 339 } 340 } 341 342 /* 343 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 344 * 345 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 346 * or a "Protocol Unreachable" treat this message as an abort 347 * with the T bit set. 348 * 349 * This function sends an event to the state machine, which will abort the 350 * association. 351 * 352 */ 353 void sctp_icmp_proto_unreachable(struct sock *sk, 354 struct sctp_association *asoc, 355 struct sctp_transport *t) 356 { 357 SCTP_DEBUG_PRINTK("%s\n", __FUNCTION__); 358 359 sctp_do_sm(SCTP_EVENT_T_OTHER, 360 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 361 asoc->state, asoc->ep, asoc, t, 362 GFP_ATOMIC); 363 364 } 365 366 /* Common lookup code for icmp/icmpv6 error handler. */ 367 struct sock *sctp_err_lookup(int family, struct sk_buff *skb, 368 struct sctphdr *sctphdr, 369 struct sctp_association **app, 370 struct sctp_transport **tpp) 371 { 372 union sctp_addr saddr; 373 union sctp_addr daddr; 374 struct sctp_af *af; 375 struct sock *sk = NULL; 376 struct sctp_association *asoc = NULL; 377 struct sctp_transport *transport = NULL; 378 379 *app = NULL; *tpp = NULL; 380 381 af = sctp_get_af_specific(family); 382 if (unlikely(!af)) { 383 return NULL; 384 } 385 386 /* Initialize local addresses for lookups. */ 387 af->from_skb(&saddr, skb, 1); 388 af->from_skb(&daddr, skb, 0); 389 390 /* Look for an association that matches the incoming ICMP error 391 * packet. 392 */ 393 asoc = __sctp_lookup_association(&saddr, &daddr, &transport); 394 if (!asoc) 395 return NULL; 396 397 sk = asoc->base.sk; 398 399 if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) { 400 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 401 goto out; 402 } 403 404 sctp_bh_lock_sock(sk); 405 406 /* If too many ICMPs get dropped on busy 407 * servers this needs to be solved differently. 408 */ 409 if (sock_owned_by_user(sk)) 410 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); 411 412 *app = asoc; 413 *tpp = transport; 414 return sk; 415 416 out: 417 sock_put(sk); 418 if (asoc) 419 sctp_association_put(asoc); 420 return NULL; 421 } 422 423 /* Common cleanup code for icmp/icmpv6 error handler. */ 424 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 425 { 426 sctp_bh_unlock_sock(sk); 427 sock_put(sk); 428 if (asoc) 429 sctp_association_put(asoc); 430 } 431 432 /* 433 * This routine is called by the ICMP module when it gets some 434 * sort of error condition. If err < 0 then the socket should 435 * be closed and the error returned to the user. If err > 0 436 * it's just the icmp type << 8 | icmp code. After adjustment 437 * header points to the first 8 bytes of the sctp header. We need 438 * to find the appropriate port. 439 * 440 * The locking strategy used here is very "optimistic". When 441 * someone else accesses the socket the ICMP is just dropped 442 * and for some paths there is no check at all. 443 * A more general error queue to queue errors for later handling 444 * is probably better. 445 * 446 */ 447 void sctp_v4_err(struct sk_buff *skb, __u32 info) 448 { 449 struct iphdr *iph = (struct iphdr *)skb->data; 450 struct sctphdr *sh = (struct sctphdr *)(skb->data + (iph->ihl <<2)); 451 int type = skb->h.icmph->type; 452 int code = skb->h.icmph->code; 453 struct sock *sk; 454 struct sctp_association *asoc; 455 struct sctp_transport *transport; 456 struct inet_sock *inet; 457 char *saveip, *savesctp; 458 int err; 459 460 if (skb->len < ((iph->ihl << 2) + 8)) { 461 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 462 return; 463 } 464 465 /* Fix up skb to look at the embedded net header. */ 466 saveip = skb->nh.raw; 467 savesctp = skb->h.raw; 468 skb->nh.iph = iph; 469 skb->h.raw = (char *)sh; 470 sk = sctp_err_lookup(AF_INET, skb, sh, &asoc, &transport); 471 /* Put back, the original pointers. */ 472 skb->nh.raw = saveip; 473 skb->h.raw = savesctp; 474 if (!sk) { 475 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 476 return; 477 } 478 /* Warning: The sock lock is held. Remember to call 479 * sctp_err_finish! 480 */ 481 482 switch (type) { 483 case ICMP_PARAMETERPROB: 484 err = EPROTO; 485 break; 486 case ICMP_DEST_UNREACH: 487 if (code > NR_ICMP_UNREACH) 488 goto out_unlock; 489 490 /* PMTU discovery (RFC1191) */ 491 if (ICMP_FRAG_NEEDED == code) { 492 sctp_icmp_frag_needed(sk, asoc, transport, info); 493 goto out_unlock; 494 } 495 else { 496 if (ICMP_PROT_UNREACH == code) { 497 sctp_icmp_proto_unreachable(sk, asoc, 498 transport); 499 goto out_unlock; 500 } 501 } 502 err = icmp_err_convert[code].errno; 503 break; 504 case ICMP_TIME_EXCEEDED: 505 /* Ignore any time exceeded errors due to fragment reassembly 506 * timeouts. 507 */ 508 if (ICMP_EXC_FRAGTIME == code) 509 goto out_unlock; 510 511 err = EHOSTUNREACH; 512 break; 513 default: 514 goto out_unlock; 515 } 516 517 inet = inet_sk(sk); 518 if (!sock_owned_by_user(sk) && inet->recverr) { 519 sk->sk_err = err; 520 sk->sk_error_report(sk); 521 } else { /* Only an error on timeout */ 522 sk->sk_err_soft = err; 523 } 524 525 out_unlock: 526 sctp_err_finish(sk, asoc); 527 } 528 529 /* 530 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 531 * 532 * This function scans all the chunks in the OOTB packet to determine if 533 * the packet should be discarded right away. If a response might be needed 534 * for this packet, or, if further processing is possible, the packet will 535 * be queued to a proper inqueue for the next phase of handling. 536 * 537 * Output: 538 * Return 0 - If further processing is needed. 539 * Return 1 - If the packet can be discarded right away. 540 */ 541 int sctp_rcv_ootb(struct sk_buff *skb) 542 { 543 sctp_chunkhdr_t *ch; 544 __u8 *ch_end; 545 sctp_errhdr_t *err; 546 547 ch = (sctp_chunkhdr_t *) skb->data; 548 ch_end = ((__u8 *) ch) + WORD_ROUND(ntohs(ch->length)); 549 550 /* Scan through all the chunks in the packet. */ 551 while (ch_end > (__u8 *)ch && ch_end < skb->tail) { 552 553 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 554 * receiver MUST silently discard the OOTB packet and take no 555 * further action. 556 */ 557 if (SCTP_CID_ABORT == ch->type) 558 goto discard; 559 560 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 561 * chunk, the receiver should silently discard the packet 562 * and take no further action. 563 */ 564 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 565 goto discard; 566 567 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR 568 * or a COOKIE ACK the SCTP Packet should be silently 569 * discarded. 570 */ 571 if (SCTP_CID_COOKIE_ACK == ch->type) 572 goto discard; 573 574 if (SCTP_CID_ERROR == ch->type) { 575 sctp_walk_errors(err, ch) { 576 if (SCTP_ERROR_STALE_COOKIE == err->cause) 577 goto discard; 578 } 579 } 580 581 ch = (sctp_chunkhdr_t *) ch_end; 582 ch_end = ((__u8 *) ch) + WORD_ROUND(ntohs(ch->length)); 583 } 584 585 return 0; 586 587 discard: 588 return 1; 589 } 590 591 /* Insert endpoint into the hash table. */ 592 static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 593 { 594 struct sctp_ep_common **epp; 595 struct sctp_ep_common *epb; 596 struct sctp_hashbucket *head; 597 598 epb = &ep->base; 599 600 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 601 head = &sctp_ep_hashtable[epb->hashent]; 602 603 sctp_write_lock(&head->lock); 604 epp = &head->chain; 605 epb->next = *epp; 606 if (epb->next) 607 (*epp)->pprev = &epb->next; 608 *epp = epb; 609 epb->pprev = epp; 610 sctp_write_unlock(&head->lock); 611 } 612 613 /* Add an endpoint to the hash. Local BH-safe. */ 614 void sctp_hash_endpoint(struct sctp_endpoint *ep) 615 { 616 sctp_local_bh_disable(); 617 __sctp_hash_endpoint(ep); 618 sctp_local_bh_enable(); 619 } 620 621 /* Remove endpoint from the hash table. */ 622 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 623 { 624 struct sctp_hashbucket *head; 625 struct sctp_ep_common *epb; 626 627 epb = &ep->base; 628 629 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 630 631 head = &sctp_ep_hashtable[epb->hashent]; 632 633 sctp_write_lock(&head->lock); 634 635 if (epb->pprev) { 636 if (epb->next) 637 epb->next->pprev = epb->pprev; 638 *epb->pprev = epb->next; 639 epb->pprev = NULL; 640 } 641 642 sctp_write_unlock(&head->lock); 643 } 644 645 /* Remove endpoint from the hash. Local BH-safe. */ 646 void sctp_unhash_endpoint(struct sctp_endpoint *ep) 647 { 648 sctp_local_bh_disable(); 649 __sctp_unhash_endpoint(ep); 650 sctp_local_bh_enable(); 651 } 652 653 /* Look up an endpoint. */ 654 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr) 655 { 656 struct sctp_hashbucket *head; 657 struct sctp_ep_common *epb; 658 struct sctp_endpoint *ep; 659 int hash; 660 661 hash = sctp_ep_hashfn(laddr->v4.sin_port); 662 head = &sctp_ep_hashtable[hash]; 663 read_lock(&head->lock); 664 for (epb = head->chain; epb; epb = epb->next) { 665 ep = sctp_ep(epb); 666 if (sctp_endpoint_is_match(ep, laddr)) 667 goto hit; 668 } 669 670 ep = sctp_sk((sctp_get_ctl_sock()))->ep; 671 epb = &ep->base; 672 673 hit: 674 sctp_endpoint_hold(ep); 675 sock_hold(epb->sk); 676 read_unlock(&head->lock); 677 return ep; 678 } 679 680 /* Insert association into the hash table. */ 681 static void __sctp_hash_established(struct sctp_association *asoc) 682 { 683 struct sctp_ep_common **epp; 684 struct sctp_ep_common *epb; 685 struct sctp_hashbucket *head; 686 687 epb = &asoc->base; 688 689 /* Calculate which chain this entry will belong to. */ 690 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port); 691 692 head = &sctp_assoc_hashtable[epb->hashent]; 693 694 sctp_write_lock(&head->lock); 695 epp = &head->chain; 696 epb->next = *epp; 697 if (epb->next) 698 (*epp)->pprev = &epb->next; 699 *epp = epb; 700 epb->pprev = epp; 701 sctp_write_unlock(&head->lock); 702 } 703 704 /* Add an association to the hash. Local BH-safe. */ 705 void sctp_hash_established(struct sctp_association *asoc) 706 { 707 sctp_local_bh_disable(); 708 __sctp_hash_established(asoc); 709 sctp_local_bh_enable(); 710 } 711 712 /* Remove association from the hash table. */ 713 static void __sctp_unhash_established(struct sctp_association *asoc) 714 { 715 struct sctp_hashbucket *head; 716 struct sctp_ep_common *epb; 717 718 epb = &asoc->base; 719 720 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, 721 asoc->peer.port); 722 723 head = &sctp_assoc_hashtable[epb->hashent]; 724 725 sctp_write_lock(&head->lock); 726 727 if (epb->pprev) { 728 if (epb->next) 729 epb->next->pprev = epb->pprev; 730 *epb->pprev = epb->next; 731 epb->pprev = NULL; 732 } 733 734 sctp_write_unlock(&head->lock); 735 } 736 737 /* Remove association from the hash table. Local BH-safe. */ 738 void sctp_unhash_established(struct sctp_association *asoc) 739 { 740 sctp_local_bh_disable(); 741 __sctp_unhash_established(asoc); 742 sctp_local_bh_enable(); 743 } 744 745 /* Look up an association. */ 746 static struct sctp_association *__sctp_lookup_association( 747 const union sctp_addr *local, 748 const union sctp_addr *peer, 749 struct sctp_transport **pt) 750 { 751 struct sctp_hashbucket *head; 752 struct sctp_ep_common *epb; 753 struct sctp_association *asoc; 754 struct sctp_transport *transport; 755 int hash; 756 757 /* Optimize here for direct hit, only listening connections can 758 * have wildcards anyways. 759 */ 760 hash = sctp_assoc_hashfn(local->v4.sin_port, peer->v4.sin_port); 761 head = &sctp_assoc_hashtable[hash]; 762 read_lock(&head->lock); 763 for (epb = head->chain; epb; epb = epb->next) { 764 asoc = sctp_assoc(epb); 765 transport = sctp_assoc_is_match(asoc, local, peer); 766 if (transport) 767 goto hit; 768 } 769 770 read_unlock(&head->lock); 771 772 return NULL; 773 774 hit: 775 *pt = transport; 776 sctp_association_hold(asoc); 777 sock_hold(epb->sk); 778 read_unlock(&head->lock); 779 return asoc; 780 } 781 782 /* Look up an association. BH-safe. */ 783 SCTP_STATIC 784 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr, 785 const union sctp_addr *paddr, 786 struct sctp_transport **transportp) 787 { 788 struct sctp_association *asoc; 789 790 sctp_local_bh_disable(); 791 asoc = __sctp_lookup_association(laddr, paddr, transportp); 792 sctp_local_bh_enable(); 793 794 return asoc; 795 } 796 797 /* Is there an association matching the given local and peer addresses? */ 798 int sctp_has_association(const union sctp_addr *laddr, 799 const union sctp_addr *paddr) 800 { 801 struct sctp_association *asoc; 802 struct sctp_transport *transport; 803 804 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) { 805 sock_put(asoc->base.sk); 806 sctp_association_put(asoc); 807 return 1; 808 } 809 810 return 0; 811 } 812 813 /* 814 * SCTP Implementors Guide, 2.18 Handling of address 815 * parameters within the INIT or INIT-ACK. 816 * 817 * D) When searching for a matching TCB upon reception of an INIT 818 * or INIT-ACK chunk the receiver SHOULD use not only the 819 * source address of the packet (containing the INIT or 820 * INIT-ACK) but the receiver SHOULD also use all valid 821 * address parameters contained within the chunk. 822 * 823 * 2.18.3 Solution description 824 * 825 * This new text clearly specifies to an implementor the need 826 * to look within the INIT or INIT-ACK. Any implementation that 827 * does not do this, may not be able to establish associations 828 * in certain circumstances. 829 * 830 */ 831 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb, 832 const union sctp_addr *laddr, struct sctp_transport **transportp) 833 { 834 struct sctp_association *asoc; 835 union sctp_addr addr; 836 union sctp_addr *paddr = &addr; 837 struct sctphdr *sh = (struct sctphdr *) skb->h.raw; 838 sctp_chunkhdr_t *ch; 839 union sctp_params params; 840 sctp_init_chunk_t *init; 841 struct sctp_transport *transport; 842 struct sctp_af *af; 843 844 ch = (sctp_chunkhdr_t *) skb->data; 845 846 /* If this is INIT/INIT-ACK look inside the chunk too. */ 847 switch (ch->type) { 848 case SCTP_CID_INIT: 849 case SCTP_CID_INIT_ACK: 850 break; 851 default: 852 return NULL; 853 } 854 855 /* The code below will attempt to walk the chunk and extract 856 * parameter information. Before we do that, we need to verify 857 * that the chunk length doesn't cause overflow. Otherwise, we'll 858 * walk off the end. 859 */ 860 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 861 return NULL; 862 863 /* 864 * This code will NOT touch anything inside the chunk--it is 865 * strictly READ-ONLY. 866 * 867 * RFC 2960 3 SCTP packet Format 868 * 869 * Multiple chunks can be bundled into one SCTP packet up to 870 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 871 * COMPLETE chunks. These chunks MUST NOT be bundled with any 872 * other chunk in a packet. See Section 6.10 for more details 873 * on chunk bundling. 874 */ 875 876 /* Find the start of the TLVs and the end of the chunk. This is 877 * the region we search for address parameters. 878 */ 879 init = (sctp_init_chunk_t *)skb->data; 880 881 /* Walk the parameters looking for embedded addresses. */ 882 sctp_walk_params(params, init, init_hdr.params) { 883 884 /* Note: Ignoring hostname addresses. */ 885 af = sctp_get_af_specific(param_type2af(params.p->type)); 886 if (!af) 887 continue; 888 889 af->from_addr_param(paddr, params.addr, ntohs(sh->source), 0); 890 891 asoc = __sctp_lookup_association(laddr, paddr, &transport); 892 if (asoc) 893 return asoc; 894 } 895 896 return NULL; 897 } 898 899 /* Lookup an association for an inbound skb. */ 900 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 901 const union sctp_addr *paddr, 902 const union sctp_addr *laddr, 903 struct sctp_transport **transportp) 904 { 905 struct sctp_association *asoc; 906 907 asoc = __sctp_lookup_association(laddr, paddr, transportp); 908 909 /* Further lookup for INIT/INIT-ACK packets. 910 * SCTP Implementors Guide, 2.18 Handling of address 911 * parameters within the INIT or INIT-ACK. 912 */ 913 if (!asoc) 914 asoc = __sctp_rcv_init_lookup(skb, laddr, transportp); 915 916 return asoc; 917 } 918