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 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 77 78 79 /* Calculate the SCTP checksum of an SCTP packet. */ 80 static inline int sctp_rcv_checksum(struct sk_buff *skb) 81 { 82 struct sk_buff *list = skb_shinfo(skb)->frag_list; 83 struct sctphdr *sh = sctp_hdr(skb); 84 __u32 cmp = ntohl(sh->checksum); 85 __u32 val = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); 86 87 for (; list; list = list->next) 88 val = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), 89 val); 90 91 val = sctp_end_cksum(val); 92 93 if (val != cmp) { 94 /* CRC failure, dump it. */ 95 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); 96 return -1; 97 } 98 return 0; 99 } 100 101 struct sctp_input_cb { 102 union { 103 struct inet_skb_parm h4; 104 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 105 struct inet6_skb_parm h6; 106 #endif 107 } header; 108 struct sctp_chunk *chunk; 109 }; 110 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 111 112 /* 113 * This is the routine which IP calls when receiving an SCTP packet. 114 */ 115 int sctp_rcv(struct sk_buff *skb) 116 { 117 struct sock *sk; 118 struct sctp_association *asoc; 119 struct sctp_endpoint *ep = NULL; 120 struct sctp_ep_common *rcvr; 121 struct sctp_transport *transport = NULL; 122 struct sctp_chunk *chunk; 123 struct sctphdr *sh; 124 union sctp_addr src; 125 union sctp_addr dest; 126 int family; 127 struct sctp_af *af; 128 129 if (skb->pkt_type!=PACKET_HOST) 130 goto discard_it; 131 132 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); 133 134 if (skb_linearize(skb)) 135 goto discard_it; 136 137 sh = sctp_hdr(skb); 138 139 /* Pull up the IP and SCTP headers. */ 140 __skb_pull(skb, skb_transport_offset(skb)); 141 if (skb->len < sizeof(struct sctphdr)) 142 goto discard_it; 143 if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0) 144 goto discard_it; 145 146 skb_pull(skb, sizeof(struct sctphdr)); 147 148 /* Make sure we at least have chunk headers worth of data left. */ 149 if (skb->len < sizeof(struct sctp_chunkhdr)) 150 goto discard_it; 151 152 family = ipver2af(ip_hdr(skb)->version); 153 af = sctp_get_af_specific(family); 154 if (unlikely(!af)) 155 goto discard_it; 156 157 /* Initialize local addresses for lookups. */ 158 af->from_skb(&src, skb, 1); 159 af->from_skb(&dest, skb, 0); 160 161 /* If the packet is to or from a non-unicast address, 162 * silently discard the packet. 163 * 164 * This is not clearly defined in the RFC except in section 165 * 8.4 - OOTB handling. However, based on the book "Stream Control 166 * Transmission Protocol" 2.1, "It is important to note that the 167 * IP address of an SCTP transport address must be a routable 168 * unicast address. In other words, IP multicast addresses and 169 * IP broadcast addresses cannot be used in an SCTP transport 170 * address." 171 */ 172 if (!af->addr_valid(&src, NULL, skb) || 173 !af->addr_valid(&dest, NULL, skb)) 174 goto discard_it; 175 176 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); 177 178 if (!asoc) 179 ep = __sctp_rcv_lookup_endpoint(&dest); 180 181 /* Retrieve the common input handling substructure. */ 182 rcvr = asoc ? &asoc->base : &ep->base; 183 sk = rcvr->sk; 184 185 /* 186 * If a frame arrives on an interface and the receiving socket is 187 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 188 */ 189 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) 190 { 191 if (asoc) { 192 sctp_association_put(asoc); 193 asoc = NULL; 194 } else { 195 sctp_endpoint_put(ep); 196 ep = NULL; 197 } 198 sk = sctp_get_ctl_sock(); 199 ep = sctp_sk(sk)->ep; 200 sctp_endpoint_hold(ep); 201 rcvr = &ep->base; 202 } 203 204 /* 205 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 206 * An SCTP packet is called an "out of the blue" (OOTB) 207 * packet if it is correctly formed, i.e., passed the 208 * receiver's checksum check, but the receiver is not 209 * able to identify the association to which this 210 * packet belongs. 211 */ 212 if (!asoc) { 213 if (sctp_rcv_ootb(skb)) { 214 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); 215 goto discard_release; 216 } 217 } 218 219 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 220 goto discard_release; 221 nf_reset(skb); 222 223 if (sk_filter(sk, skb)) 224 goto discard_release; 225 226 /* Create an SCTP packet structure. */ 227 chunk = sctp_chunkify(skb, asoc, sk); 228 if (!chunk) 229 goto discard_release; 230 SCTP_INPUT_CB(skb)->chunk = chunk; 231 232 /* Remember what endpoint is to handle this packet. */ 233 chunk->rcvr = rcvr; 234 235 /* Remember the SCTP header. */ 236 chunk->sctp_hdr = sh; 237 238 /* Set the source and destination addresses of the incoming chunk. */ 239 sctp_init_addrs(chunk, &src, &dest); 240 241 /* Remember where we came from. */ 242 chunk->transport = transport; 243 244 /* Acquire access to the sock lock. Note: We are safe from other 245 * bottom halves on this lock, but a user may be in the lock too, 246 * so check if it is busy. 247 */ 248 sctp_bh_lock_sock(sk); 249 250 if (sock_owned_by_user(sk)) { 251 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG); 252 sctp_add_backlog(sk, skb); 253 } else { 254 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ); 255 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 256 } 257 258 sctp_bh_unlock_sock(sk); 259 260 /* Release the asoc/ep ref we took in the lookup calls. */ 261 if (asoc) 262 sctp_association_put(asoc); 263 else 264 sctp_endpoint_put(ep); 265 266 return 0; 267 268 discard_it: 269 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS); 270 kfree_skb(skb); 271 return 0; 272 273 discard_release: 274 /* Release the asoc/ep ref we took in the lookup calls. */ 275 if (asoc) 276 sctp_association_put(asoc); 277 else 278 sctp_endpoint_put(ep); 279 280 goto discard_it; 281 } 282 283 /* Process the backlog queue of the socket. Every skb on 284 * the backlog holds a ref on an association or endpoint. 285 * We hold this ref throughout the state machine to make 286 * sure that the structure we need is still around. 287 */ 288 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 289 { 290 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 291 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 292 struct sctp_ep_common *rcvr = NULL; 293 int backloged = 0; 294 295 rcvr = chunk->rcvr; 296 297 /* If the rcvr is dead then the association or endpoint 298 * has been deleted and we can safely drop the chunk 299 * and refs that we are holding. 300 */ 301 if (rcvr->dead) { 302 sctp_chunk_free(chunk); 303 goto done; 304 } 305 306 if (unlikely(rcvr->sk != sk)) { 307 /* In this case, the association moved from one socket to 308 * another. We are currently sitting on the backlog of the 309 * old socket, so we need to move. 310 * However, since we are here in the process context we 311 * need to take make sure that the user doesn't own 312 * the new socket when we process the packet. 313 * If the new socket is user-owned, queue the chunk to the 314 * backlog of the new socket without dropping any refs. 315 * Otherwise, we can safely push the chunk on the inqueue. 316 */ 317 318 sk = rcvr->sk; 319 sctp_bh_lock_sock(sk); 320 321 if (sock_owned_by_user(sk)) { 322 sk_add_backlog(sk, skb); 323 backloged = 1; 324 } else 325 sctp_inq_push(inqueue, chunk); 326 327 sctp_bh_unlock_sock(sk); 328 329 /* If the chunk was backloged again, don't drop refs */ 330 if (backloged) 331 return 0; 332 } else { 333 sctp_inq_push(inqueue, chunk); 334 } 335 336 done: 337 /* Release the refs we took in sctp_add_backlog */ 338 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 339 sctp_association_put(sctp_assoc(rcvr)); 340 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 341 sctp_endpoint_put(sctp_ep(rcvr)); 342 else 343 BUG(); 344 345 return 0; 346 } 347 348 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 349 { 350 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 351 struct sctp_ep_common *rcvr = chunk->rcvr; 352 353 /* Hold the assoc/ep while hanging on the backlog queue. 354 * This way, we know structures we need will not disappear from us 355 */ 356 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 357 sctp_association_hold(sctp_assoc(rcvr)); 358 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 359 sctp_endpoint_hold(sctp_ep(rcvr)); 360 else 361 BUG(); 362 363 sk_add_backlog(sk, skb); 364 } 365 366 /* Handle icmp frag needed error. */ 367 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 368 struct sctp_transport *t, __u32 pmtu) 369 { 370 if (sock_owned_by_user(sk) || !t || (t->pathmtu == pmtu)) 371 return; 372 373 if (t->param_flags & SPP_PMTUD_ENABLE) { 374 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { 375 printk(KERN_WARNING "%s: Reported pmtu %d too low, " 376 "using default minimum of %d\n", 377 __FUNCTION__, pmtu, 378 SCTP_DEFAULT_MINSEGMENT); 379 /* Use default minimum segment size and disable 380 * pmtu discovery on this transport. 381 */ 382 t->pathmtu = SCTP_DEFAULT_MINSEGMENT; 383 t->param_flags = (t->param_flags & ~SPP_PMTUD) | 384 SPP_PMTUD_DISABLE; 385 } else { 386 t->pathmtu = pmtu; 387 } 388 389 /* Update association pmtu. */ 390 sctp_assoc_sync_pmtu(asoc); 391 } 392 393 /* Retransmit with the new pmtu setting. 394 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 395 * Needed will never be sent, but if a message was sent before 396 * PMTU discovery was disabled that was larger than the PMTU, it 397 * would not be fragmented, so it must be re-transmitted fragmented. 398 */ 399 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 400 } 401 402 /* 403 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 404 * 405 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 406 * or a "Protocol Unreachable" treat this message as an abort 407 * with the T bit set. 408 * 409 * This function sends an event to the state machine, which will abort the 410 * association. 411 * 412 */ 413 void sctp_icmp_proto_unreachable(struct sock *sk, 414 struct sctp_association *asoc, 415 struct sctp_transport *t) 416 { 417 SCTP_DEBUG_PRINTK("%s\n", __FUNCTION__); 418 419 sctp_do_sm(SCTP_EVENT_T_OTHER, 420 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 421 asoc->state, asoc->ep, asoc, t, 422 GFP_ATOMIC); 423 424 } 425 426 /* Common lookup code for icmp/icmpv6 error handler. */ 427 struct sock *sctp_err_lookup(int family, struct sk_buff *skb, 428 struct sctphdr *sctphdr, 429 struct sctp_association **app, 430 struct sctp_transport **tpp) 431 { 432 union sctp_addr saddr; 433 union sctp_addr daddr; 434 struct sctp_af *af; 435 struct sock *sk = NULL; 436 struct sctp_association *asoc; 437 struct sctp_transport *transport = NULL; 438 439 *app = NULL; *tpp = NULL; 440 441 af = sctp_get_af_specific(family); 442 if (unlikely(!af)) { 443 return NULL; 444 } 445 446 /* Initialize local addresses for lookups. */ 447 af->from_skb(&saddr, skb, 1); 448 af->from_skb(&daddr, skb, 0); 449 450 /* Look for an association that matches the incoming ICMP error 451 * packet. 452 */ 453 asoc = __sctp_lookup_association(&saddr, &daddr, &transport); 454 if (!asoc) 455 return NULL; 456 457 sk = asoc->base.sk; 458 459 if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) { 460 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 461 goto out; 462 } 463 464 sctp_bh_lock_sock(sk); 465 466 /* If too many ICMPs get dropped on busy 467 * servers this needs to be solved differently. 468 */ 469 if (sock_owned_by_user(sk)) 470 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); 471 472 *app = asoc; 473 *tpp = transport; 474 return sk; 475 476 out: 477 if (asoc) 478 sctp_association_put(asoc); 479 return NULL; 480 } 481 482 /* Common cleanup code for icmp/icmpv6 error handler. */ 483 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 484 { 485 sctp_bh_unlock_sock(sk); 486 if (asoc) 487 sctp_association_put(asoc); 488 } 489 490 /* 491 * This routine is called by the ICMP module when it gets some 492 * sort of error condition. If err < 0 then the socket should 493 * be closed and the error returned to the user. If err > 0 494 * it's just the icmp type << 8 | icmp code. After adjustment 495 * header points to the first 8 bytes of the sctp header. We need 496 * to find the appropriate port. 497 * 498 * The locking strategy used here is very "optimistic". When 499 * someone else accesses the socket the ICMP is just dropped 500 * and for some paths there is no check at all. 501 * A more general error queue to queue errors for later handling 502 * is probably better. 503 * 504 */ 505 void sctp_v4_err(struct sk_buff *skb, __u32 info) 506 { 507 struct iphdr *iph = (struct iphdr *)skb->data; 508 const int ihlen = iph->ihl * 4; 509 const int type = icmp_hdr(skb)->type; 510 const int code = icmp_hdr(skb)->code; 511 struct sock *sk; 512 struct sctp_association *asoc = NULL; 513 struct sctp_transport *transport; 514 struct inet_sock *inet; 515 sk_buff_data_t saveip, savesctp; 516 int err; 517 518 if (skb->len < ihlen + 8) { 519 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 520 return; 521 } 522 523 /* Fix up skb to look at the embedded net header. */ 524 saveip = skb->network_header; 525 savesctp = skb->transport_header; 526 skb_reset_network_header(skb); 527 skb_set_transport_header(skb, ihlen); 528 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 529 /* Put back, the original values. */ 530 skb->network_header = saveip; 531 skb->transport_header = savesctp; 532 if (!sk) { 533 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 534 return; 535 } 536 /* Warning: The sock lock is held. Remember to call 537 * sctp_err_finish! 538 */ 539 540 switch (type) { 541 case ICMP_PARAMETERPROB: 542 err = EPROTO; 543 break; 544 case ICMP_DEST_UNREACH: 545 if (code > NR_ICMP_UNREACH) 546 goto out_unlock; 547 548 /* PMTU discovery (RFC1191) */ 549 if (ICMP_FRAG_NEEDED == code) { 550 sctp_icmp_frag_needed(sk, asoc, transport, info); 551 goto out_unlock; 552 } 553 else { 554 if (ICMP_PROT_UNREACH == code) { 555 sctp_icmp_proto_unreachable(sk, asoc, 556 transport); 557 goto out_unlock; 558 } 559 } 560 err = icmp_err_convert[code].errno; 561 break; 562 case ICMP_TIME_EXCEEDED: 563 /* Ignore any time exceeded errors due to fragment reassembly 564 * timeouts. 565 */ 566 if (ICMP_EXC_FRAGTIME == code) 567 goto out_unlock; 568 569 err = EHOSTUNREACH; 570 break; 571 default: 572 goto out_unlock; 573 } 574 575 inet = inet_sk(sk); 576 if (!sock_owned_by_user(sk) && inet->recverr) { 577 sk->sk_err = err; 578 sk->sk_error_report(sk); 579 } else { /* Only an error on timeout */ 580 sk->sk_err_soft = err; 581 } 582 583 out_unlock: 584 sctp_err_finish(sk, asoc); 585 } 586 587 /* 588 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 589 * 590 * This function scans all the chunks in the OOTB packet to determine if 591 * the packet should be discarded right away. If a response might be needed 592 * for this packet, or, if further processing is possible, the packet will 593 * be queued to a proper inqueue for the next phase of handling. 594 * 595 * Output: 596 * Return 0 - If further processing is needed. 597 * Return 1 - If the packet can be discarded right away. 598 */ 599 int sctp_rcv_ootb(struct sk_buff *skb) 600 { 601 sctp_chunkhdr_t *ch; 602 __u8 *ch_end; 603 sctp_errhdr_t *err; 604 605 ch = (sctp_chunkhdr_t *) skb->data; 606 607 /* Scan through all the chunks in the packet. */ 608 do { 609 /* Break out if chunk length is less then minimal. */ 610 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 611 break; 612 613 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 614 if (ch_end > skb_tail_pointer(skb)) 615 break; 616 617 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 618 * receiver MUST silently discard the OOTB packet and take no 619 * further action. 620 */ 621 if (SCTP_CID_ABORT == ch->type) 622 goto discard; 623 624 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 625 * chunk, the receiver should silently discard the packet 626 * and take no further action. 627 */ 628 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 629 goto discard; 630 631 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR 632 * or a COOKIE ACK the SCTP Packet should be silently 633 * discarded. 634 */ 635 if (SCTP_CID_COOKIE_ACK == ch->type) 636 goto discard; 637 638 if (SCTP_CID_ERROR == ch->type) { 639 sctp_walk_errors(err, ch) { 640 if (SCTP_ERROR_STALE_COOKIE == err->cause) 641 goto discard; 642 } 643 } 644 645 ch = (sctp_chunkhdr_t *) ch_end; 646 } while (ch_end < skb_tail_pointer(skb)); 647 648 return 0; 649 650 discard: 651 return 1; 652 } 653 654 /* Insert endpoint into the hash table. */ 655 static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 656 { 657 struct sctp_ep_common **epp; 658 struct sctp_ep_common *epb; 659 struct sctp_hashbucket *head; 660 661 epb = &ep->base; 662 663 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 664 head = &sctp_ep_hashtable[epb->hashent]; 665 666 sctp_write_lock(&head->lock); 667 epp = &head->chain; 668 epb->next = *epp; 669 if (epb->next) 670 (*epp)->pprev = &epb->next; 671 *epp = epb; 672 epb->pprev = epp; 673 sctp_write_unlock(&head->lock); 674 } 675 676 /* Add an endpoint to the hash. Local BH-safe. */ 677 void sctp_hash_endpoint(struct sctp_endpoint *ep) 678 { 679 sctp_local_bh_disable(); 680 __sctp_hash_endpoint(ep); 681 sctp_local_bh_enable(); 682 } 683 684 /* Remove endpoint from the hash table. */ 685 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 686 { 687 struct sctp_hashbucket *head; 688 struct sctp_ep_common *epb; 689 690 epb = &ep->base; 691 692 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 693 694 head = &sctp_ep_hashtable[epb->hashent]; 695 696 sctp_write_lock(&head->lock); 697 698 if (epb->pprev) { 699 if (epb->next) 700 epb->next->pprev = epb->pprev; 701 *epb->pprev = epb->next; 702 epb->pprev = NULL; 703 } 704 705 sctp_write_unlock(&head->lock); 706 } 707 708 /* Remove endpoint from the hash. Local BH-safe. */ 709 void sctp_unhash_endpoint(struct sctp_endpoint *ep) 710 { 711 sctp_local_bh_disable(); 712 __sctp_unhash_endpoint(ep); 713 sctp_local_bh_enable(); 714 } 715 716 /* Look up an endpoint. */ 717 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr) 718 { 719 struct sctp_hashbucket *head; 720 struct sctp_ep_common *epb; 721 struct sctp_endpoint *ep; 722 int hash; 723 724 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port)); 725 head = &sctp_ep_hashtable[hash]; 726 read_lock(&head->lock); 727 for (epb = head->chain; epb; epb = epb->next) { 728 ep = sctp_ep(epb); 729 if (sctp_endpoint_is_match(ep, laddr)) 730 goto hit; 731 } 732 733 ep = sctp_sk((sctp_get_ctl_sock()))->ep; 734 epb = &ep->base; 735 736 hit: 737 sctp_endpoint_hold(ep); 738 read_unlock(&head->lock); 739 return ep; 740 } 741 742 /* Insert association into the hash table. */ 743 static void __sctp_hash_established(struct sctp_association *asoc) 744 { 745 struct sctp_ep_common **epp; 746 struct sctp_ep_common *epb; 747 struct sctp_hashbucket *head; 748 749 epb = &asoc->base; 750 751 /* Calculate which chain this entry will belong to. */ 752 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port); 753 754 head = &sctp_assoc_hashtable[epb->hashent]; 755 756 sctp_write_lock(&head->lock); 757 epp = &head->chain; 758 epb->next = *epp; 759 if (epb->next) 760 (*epp)->pprev = &epb->next; 761 *epp = epb; 762 epb->pprev = epp; 763 sctp_write_unlock(&head->lock); 764 } 765 766 /* Add an association to the hash. Local BH-safe. */ 767 void sctp_hash_established(struct sctp_association *asoc) 768 { 769 if (asoc->temp) 770 return; 771 772 sctp_local_bh_disable(); 773 __sctp_hash_established(asoc); 774 sctp_local_bh_enable(); 775 } 776 777 /* Remove association from the hash table. */ 778 static void __sctp_unhash_established(struct sctp_association *asoc) 779 { 780 struct sctp_hashbucket *head; 781 struct sctp_ep_common *epb; 782 783 epb = &asoc->base; 784 785 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, 786 asoc->peer.port); 787 788 head = &sctp_assoc_hashtable[epb->hashent]; 789 790 sctp_write_lock(&head->lock); 791 792 if (epb->pprev) { 793 if (epb->next) 794 epb->next->pprev = epb->pprev; 795 *epb->pprev = epb->next; 796 epb->pprev = NULL; 797 } 798 799 sctp_write_unlock(&head->lock); 800 } 801 802 /* Remove association from the hash table. Local BH-safe. */ 803 void sctp_unhash_established(struct sctp_association *asoc) 804 { 805 if (asoc->temp) 806 return; 807 808 sctp_local_bh_disable(); 809 __sctp_unhash_established(asoc); 810 sctp_local_bh_enable(); 811 } 812 813 /* Look up an association. */ 814 static struct sctp_association *__sctp_lookup_association( 815 const union sctp_addr *local, 816 const union sctp_addr *peer, 817 struct sctp_transport **pt) 818 { 819 struct sctp_hashbucket *head; 820 struct sctp_ep_common *epb; 821 struct sctp_association *asoc; 822 struct sctp_transport *transport; 823 int hash; 824 825 /* Optimize here for direct hit, only listening connections can 826 * have wildcards anyways. 827 */ 828 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port)); 829 head = &sctp_assoc_hashtable[hash]; 830 read_lock(&head->lock); 831 for (epb = head->chain; epb; epb = epb->next) { 832 asoc = sctp_assoc(epb); 833 transport = sctp_assoc_is_match(asoc, local, peer); 834 if (transport) 835 goto hit; 836 } 837 838 read_unlock(&head->lock); 839 840 return NULL; 841 842 hit: 843 *pt = transport; 844 sctp_association_hold(asoc); 845 read_unlock(&head->lock); 846 return asoc; 847 } 848 849 /* Look up an association. BH-safe. */ 850 SCTP_STATIC 851 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr, 852 const union sctp_addr *paddr, 853 struct sctp_transport **transportp) 854 { 855 struct sctp_association *asoc; 856 857 sctp_local_bh_disable(); 858 asoc = __sctp_lookup_association(laddr, paddr, transportp); 859 sctp_local_bh_enable(); 860 861 return asoc; 862 } 863 864 /* Is there an association matching the given local and peer addresses? */ 865 int sctp_has_association(const union sctp_addr *laddr, 866 const union sctp_addr *paddr) 867 { 868 struct sctp_association *asoc; 869 struct sctp_transport *transport; 870 871 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) { 872 sctp_association_put(asoc); 873 return 1; 874 } 875 876 return 0; 877 } 878 879 /* 880 * SCTP Implementors Guide, 2.18 Handling of address 881 * parameters within the INIT or INIT-ACK. 882 * 883 * D) When searching for a matching TCB upon reception of an INIT 884 * or INIT-ACK chunk the receiver SHOULD use not only the 885 * source address of the packet (containing the INIT or 886 * INIT-ACK) but the receiver SHOULD also use all valid 887 * address parameters contained within the chunk. 888 * 889 * 2.18.3 Solution description 890 * 891 * This new text clearly specifies to an implementor the need 892 * to look within the INIT or INIT-ACK. Any implementation that 893 * does not do this, may not be able to establish associations 894 * in certain circumstances. 895 * 896 */ 897 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb, 898 const union sctp_addr *laddr, struct sctp_transport **transportp) 899 { 900 struct sctp_association *asoc; 901 union sctp_addr addr; 902 union sctp_addr *paddr = &addr; 903 struct sctphdr *sh = sctp_hdr(skb); 904 sctp_chunkhdr_t *ch; 905 union sctp_params params; 906 sctp_init_chunk_t *init; 907 struct sctp_transport *transport; 908 struct sctp_af *af; 909 910 ch = (sctp_chunkhdr_t *) skb->data; 911 912 /* If this is INIT/INIT-ACK look inside the chunk too. */ 913 switch (ch->type) { 914 case SCTP_CID_INIT: 915 case SCTP_CID_INIT_ACK: 916 break; 917 default: 918 return NULL; 919 } 920 921 /* The code below will attempt to walk the chunk and extract 922 * parameter information. Before we do that, we need to verify 923 * that the chunk length doesn't cause overflow. Otherwise, we'll 924 * walk off the end. 925 */ 926 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 927 return NULL; 928 929 /* 930 * This code will NOT touch anything inside the chunk--it is 931 * strictly READ-ONLY. 932 * 933 * RFC 2960 3 SCTP packet Format 934 * 935 * Multiple chunks can be bundled into one SCTP packet up to 936 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 937 * COMPLETE chunks. These chunks MUST NOT be bundled with any 938 * other chunk in a packet. See Section 6.10 for more details 939 * on chunk bundling. 940 */ 941 942 /* Find the start of the TLVs and the end of the chunk. This is 943 * the region we search for address parameters. 944 */ 945 init = (sctp_init_chunk_t *)skb->data; 946 947 /* Walk the parameters looking for embedded addresses. */ 948 sctp_walk_params(params, init, init_hdr.params) { 949 950 /* Note: Ignoring hostname addresses. */ 951 af = sctp_get_af_specific(param_type2af(params.p->type)); 952 if (!af) 953 continue; 954 955 af->from_addr_param(paddr, params.addr, sh->source, 0); 956 957 asoc = __sctp_lookup_association(laddr, paddr, &transport); 958 if (asoc) 959 return asoc; 960 } 961 962 return NULL; 963 } 964 965 /* Lookup an association for an inbound skb. */ 966 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 967 const union sctp_addr *paddr, 968 const union sctp_addr *laddr, 969 struct sctp_transport **transportp) 970 { 971 struct sctp_association *asoc; 972 973 asoc = __sctp_lookup_association(laddr, paddr, transportp); 974 975 /* Further lookup for INIT/INIT-ACK packets. 976 * SCTP Implementors Guide, 2.18 Handling of address 977 * parameters within the INIT or INIT-ACK. 978 */ 979 if (!asoc) 980 asoc = __sctp_rcv_init_lookup(skb, laddr, transportp); 981 982 return asoc; 983 } 984