1 /* SCTP kernel 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 implementation 10 * 11 * These functions handle all input from the IP layer into SCTP. 12 * 13 * This SCTP 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 * This SCTP 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 #include <net/sctp/checksum.h> 64 65 /* Forward declarations for internal helpers. */ 66 static int sctp_rcv_ootb(struct sk_buff *); 67 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 68 const union sctp_addr *laddr, 69 const union sctp_addr *paddr, 70 struct sctp_transport **transportp); 71 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr); 72 static struct sctp_association *__sctp_lookup_association( 73 const union sctp_addr *local, 74 const union sctp_addr *peer, 75 struct sctp_transport **pt); 76 77 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 78 79 80 /* Calculate the SCTP checksum of an SCTP packet. */ 81 static inline int sctp_rcv_checksum(struct sk_buff *skb) 82 { 83 struct sk_buff *list = skb_shinfo(skb)->frag_list; 84 struct sctphdr *sh = sctp_hdr(skb); 85 __u32 cmp = ntohl(sh->checksum); 86 __u32 val = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); 87 88 for (; list; list = list->next) 89 val = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), 90 val); 91 92 val = sctp_end_cksum(val); 93 94 if (val != cmp) { 95 /* CRC failure, dump it. */ 96 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); 97 return -1; 98 } 99 return 0; 100 } 101 102 struct sctp_input_cb { 103 union { 104 struct inet_skb_parm h4; 105 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 106 struct inet6_skb_parm h6; 107 #endif 108 } header; 109 struct sctp_chunk *chunk; 110 }; 111 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 112 113 /* 114 * This is the routine which IP calls when receiving an SCTP packet. 115 */ 116 int sctp_rcv(struct sk_buff *skb) 117 { 118 struct sock *sk; 119 struct sctp_association *asoc; 120 struct sctp_endpoint *ep = NULL; 121 struct sctp_ep_common *rcvr; 122 struct sctp_transport *transport = NULL; 123 struct sctp_chunk *chunk; 124 struct sctphdr *sh; 125 union sctp_addr src; 126 union sctp_addr dest; 127 int family; 128 struct sctp_af *af; 129 130 if (skb->pkt_type!=PACKET_HOST) 131 goto discard_it; 132 133 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); 134 135 if (skb_linearize(skb)) 136 goto discard_it; 137 138 sh = sctp_hdr(skb); 139 140 /* Pull up the IP and SCTP headers. */ 141 __skb_pull(skb, skb_transport_offset(skb)); 142 if (skb->len < sizeof(struct sctphdr)) 143 goto discard_it; 144 if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0) 145 goto discard_it; 146 147 skb_pull(skb, sizeof(struct sctphdr)); 148 149 /* Make sure we at least have chunk headers worth of data left. */ 150 if (skb->len < sizeof(struct sctp_chunkhdr)) 151 goto discard_it; 152 153 family = ipver2af(ip_hdr(skb)->version); 154 af = sctp_get_af_specific(family); 155 if (unlikely(!af)) 156 goto discard_it; 157 158 /* Initialize local addresses for lookups. */ 159 af->from_skb(&src, skb, 1); 160 af->from_skb(&dest, skb, 0); 161 162 /* If the packet is to or from a non-unicast address, 163 * silently discard the packet. 164 * 165 * This is not clearly defined in the RFC except in section 166 * 8.4 - OOTB handling. However, based on the book "Stream Control 167 * Transmission Protocol" 2.1, "It is important to note that the 168 * IP address of an SCTP transport address must be a routable 169 * unicast address. In other words, IP multicast addresses and 170 * IP broadcast addresses cannot be used in an SCTP transport 171 * address." 172 */ 173 if (!af->addr_valid(&src, NULL, skb) || 174 !af->addr_valid(&dest, NULL, skb)) 175 goto discard_it; 176 177 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); 178 179 if (!asoc) 180 ep = __sctp_rcv_lookup_endpoint(&dest); 181 182 /* Retrieve the common input handling substructure. */ 183 rcvr = asoc ? &asoc->base : &ep->base; 184 sk = rcvr->sk; 185 186 /* 187 * If a frame arrives on an interface and the receiving socket is 188 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 189 */ 190 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) 191 { 192 if (asoc) { 193 sctp_association_put(asoc); 194 asoc = NULL; 195 } else { 196 sctp_endpoint_put(ep); 197 ep = NULL; 198 } 199 sk = sctp_get_ctl_sock(); 200 ep = sctp_sk(sk)->ep; 201 sctp_endpoint_hold(ep); 202 rcvr = &ep->base; 203 } 204 205 /* 206 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 207 * An SCTP packet is called an "out of the blue" (OOTB) 208 * packet if it is correctly formed, i.e., passed the 209 * receiver's checksum check, but the receiver is not 210 * able to identify the association to which this 211 * packet belongs. 212 */ 213 if (!asoc) { 214 if (sctp_rcv_ootb(skb)) { 215 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); 216 goto discard_release; 217 } 218 } 219 220 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 221 goto discard_release; 222 nf_reset(skb); 223 224 if (sk_filter(sk, skb)) 225 goto discard_release; 226 227 /* Create an SCTP packet structure. */ 228 chunk = sctp_chunkify(skb, asoc, sk); 229 if (!chunk) 230 goto discard_release; 231 SCTP_INPUT_CB(skb)->chunk = chunk; 232 233 /* Remember what endpoint is to handle this packet. */ 234 chunk->rcvr = rcvr; 235 236 /* Remember the SCTP header. */ 237 chunk->sctp_hdr = sh; 238 239 /* Set the source and destination addresses of the incoming chunk. */ 240 sctp_init_addrs(chunk, &src, &dest); 241 242 /* Remember where we came from. */ 243 chunk->transport = transport; 244 245 /* Acquire access to the sock lock. Note: We are safe from other 246 * bottom halves on this lock, but a user may be in the lock too, 247 * so check if it is busy. 248 */ 249 sctp_bh_lock_sock(sk); 250 251 if (sock_owned_by_user(sk)) { 252 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG); 253 sctp_add_backlog(sk, skb); 254 } else { 255 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ); 256 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 257 } 258 259 sctp_bh_unlock_sock(sk); 260 261 /* Release the asoc/ep ref we took in the lookup calls. */ 262 if (asoc) 263 sctp_association_put(asoc); 264 else 265 sctp_endpoint_put(ep); 266 267 return 0; 268 269 discard_it: 270 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS); 271 kfree_skb(skb); 272 return 0; 273 274 discard_release: 275 /* Release the asoc/ep ref we took in the lookup calls. */ 276 if (asoc) 277 sctp_association_put(asoc); 278 else 279 sctp_endpoint_put(ep); 280 281 goto discard_it; 282 } 283 284 /* Process the backlog queue of the socket. Every skb on 285 * the backlog holds a ref on an association or endpoint. 286 * We hold this ref throughout the state machine to make 287 * sure that the structure we need is still around. 288 */ 289 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 290 { 291 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 292 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 293 struct sctp_ep_common *rcvr = NULL; 294 int backloged = 0; 295 296 rcvr = chunk->rcvr; 297 298 /* If the rcvr is dead then the association or endpoint 299 * has been deleted and we can safely drop the chunk 300 * and refs that we are holding. 301 */ 302 if (rcvr->dead) { 303 sctp_chunk_free(chunk); 304 goto done; 305 } 306 307 if (unlikely(rcvr->sk != sk)) { 308 /* In this case, the association moved from one socket to 309 * another. We are currently sitting on the backlog of the 310 * old socket, so we need to move. 311 * However, since we are here in the process context we 312 * need to take make sure that the user doesn't own 313 * the new socket when we process the packet. 314 * If the new socket is user-owned, queue the chunk to the 315 * backlog of the new socket without dropping any refs. 316 * Otherwise, we can safely push the chunk on the inqueue. 317 */ 318 319 sk = rcvr->sk; 320 sctp_bh_lock_sock(sk); 321 322 if (sock_owned_by_user(sk)) { 323 sk_add_backlog(sk, skb); 324 backloged = 1; 325 } else 326 sctp_inq_push(inqueue, chunk); 327 328 sctp_bh_unlock_sock(sk); 329 330 /* If the chunk was backloged again, don't drop refs */ 331 if (backloged) 332 return 0; 333 } else { 334 sctp_inq_push(inqueue, chunk); 335 } 336 337 done: 338 /* Release the refs we took in sctp_add_backlog */ 339 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 340 sctp_association_put(sctp_assoc(rcvr)); 341 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 342 sctp_endpoint_put(sctp_ep(rcvr)); 343 else 344 BUG(); 345 346 return 0; 347 } 348 349 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 350 { 351 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 352 struct sctp_ep_common *rcvr = chunk->rcvr; 353 354 /* Hold the assoc/ep while hanging on the backlog queue. 355 * This way, we know structures we need will not disappear from us 356 */ 357 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 358 sctp_association_hold(sctp_assoc(rcvr)); 359 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 360 sctp_endpoint_hold(sctp_ep(rcvr)); 361 else 362 BUG(); 363 364 sk_add_backlog(sk, skb); 365 } 366 367 /* Handle icmp frag needed error. */ 368 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 369 struct sctp_transport *t, __u32 pmtu) 370 { 371 if (!t || (t->pathmtu == pmtu)) 372 return; 373 374 if (sock_owned_by_user(sk)) { 375 asoc->pmtu_pending = 1; 376 t->pmtu_pending = 1; 377 return; 378 } 379 380 if (t->param_flags & SPP_PMTUD_ENABLE) { 381 /* Update transports view of the MTU */ 382 sctp_transport_update_pmtu(t, pmtu); 383 384 /* Update association pmtu. */ 385 sctp_assoc_sync_pmtu(asoc); 386 } 387 388 /* Retransmit with the new pmtu setting. 389 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 390 * Needed will never be sent, but if a message was sent before 391 * PMTU discovery was disabled that was larger than the PMTU, it 392 * would not be fragmented, so it must be re-transmitted fragmented. 393 */ 394 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 395 } 396 397 /* 398 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 399 * 400 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 401 * or a "Protocol Unreachable" treat this message as an abort 402 * with the T bit set. 403 * 404 * This function sends an event to the state machine, which will abort the 405 * association. 406 * 407 */ 408 void sctp_icmp_proto_unreachable(struct sock *sk, 409 struct sctp_association *asoc, 410 struct sctp_transport *t) 411 { 412 SCTP_DEBUG_PRINTK("%s\n", __func__); 413 414 sctp_do_sm(SCTP_EVENT_T_OTHER, 415 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 416 asoc->state, asoc->ep, asoc, t, 417 GFP_ATOMIC); 418 419 } 420 421 /* Common lookup code for icmp/icmpv6 error handler. */ 422 struct sock *sctp_err_lookup(int family, struct sk_buff *skb, 423 struct sctphdr *sctphdr, 424 struct sctp_association **app, 425 struct sctp_transport **tpp) 426 { 427 union sctp_addr saddr; 428 union sctp_addr daddr; 429 struct sctp_af *af; 430 struct sock *sk = NULL; 431 struct sctp_association *asoc; 432 struct sctp_transport *transport = NULL; 433 434 *app = NULL; *tpp = NULL; 435 436 af = sctp_get_af_specific(family); 437 if (unlikely(!af)) { 438 return NULL; 439 } 440 441 /* Initialize local addresses for lookups. */ 442 af->from_skb(&saddr, skb, 1); 443 af->from_skb(&daddr, skb, 0); 444 445 /* Look for an association that matches the incoming ICMP error 446 * packet. 447 */ 448 asoc = __sctp_lookup_association(&saddr, &daddr, &transport); 449 if (!asoc) 450 return NULL; 451 452 sk = asoc->base.sk; 453 454 if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) { 455 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 456 goto out; 457 } 458 459 sctp_bh_lock_sock(sk); 460 461 /* If too many ICMPs get dropped on busy 462 * servers this needs to be solved differently. 463 */ 464 if (sock_owned_by_user(sk)) 465 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); 466 467 *app = asoc; 468 *tpp = transport; 469 return sk; 470 471 out: 472 if (asoc) 473 sctp_association_put(asoc); 474 return NULL; 475 } 476 477 /* Common cleanup code for icmp/icmpv6 error handler. */ 478 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 479 { 480 sctp_bh_unlock_sock(sk); 481 if (asoc) 482 sctp_association_put(asoc); 483 } 484 485 /* 486 * This routine is called by the ICMP module when it gets some 487 * sort of error condition. If err < 0 then the socket should 488 * be closed and the error returned to the user. If err > 0 489 * it's just the icmp type << 8 | icmp code. After adjustment 490 * header points to the first 8 bytes of the sctp header. We need 491 * to find the appropriate port. 492 * 493 * The locking strategy used here is very "optimistic". When 494 * someone else accesses the socket the ICMP is just dropped 495 * and for some paths there is no check at all. 496 * A more general error queue to queue errors for later handling 497 * is probably better. 498 * 499 */ 500 void sctp_v4_err(struct sk_buff *skb, __u32 info) 501 { 502 struct iphdr *iph = (struct iphdr *)skb->data; 503 const int ihlen = iph->ihl * 4; 504 const int type = icmp_hdr(skb)->type; 505 const int code = icmp_hdr(skb)->code; 506 struct sock *sk; 507 struct sctp_association *asoc = NULL; 508 struct sctp_transport *transport; 509 struct inet_sock *inet; 510 sk_buff_data_t saveip, savesctp; 511 int err; 512 513 if (skb->len < ihlen + 8) { 514 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 515 return; 516 } 517 518 /* Fix up skb to look at the embedded net header. */ 519 saveip = skb->network_header; 520 savesctp = skb->transport_header; 521 skb_reset_network_header(skb); 522 skb_set_transport_header(skb, ihlen); 523 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 524 /* Put back, the original values. */ 525 skb->network_header = saveip; 526 skb->transport_header = savesctp; 527 if (!sk) { 528 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 529 return; 530 } 531 /* Warning: The sock lock is held. Remember to call 532 * sctp_err_finish! 533 */ 534 535 switch (type) { 536 case ICMP_PARAMETERPROB: 537 err = EPROTO; 538 break; 539 case ICMP_DEST_UNREACH: 540 if (code > NR_ICMP_UNREACH) 541 goto out_unlock; 542 543 /* PMTU discovery (RFC1191) */ 544 if (ICMP_FRAG_NEEDED == code) { 545 sctp_icmp_frag_needed(sk, asoc, transport, info); 546 goto out_unlock; 547 } 548 else { 549 if (ICMP_PROT_UNREACH == code) { 550 sctp_icmp_proto_unreachable(sk, asoc, 551 transport); 552 goto out_unlock; 553 } 554 } 555 err = icmp_err_convert[code].errno; 556 break; 557 case ICMP_TIME_EXCEEDED: 558 /* Ignore any time exceeded errors due to fragment reassembly 559 * timeouts. 560 */ 561 if (ICMP_EXC_FRAGTIME == code) 562 goto out_unlock; 563 564 err = EHOSTUNREACH; 565 break; 566 default: 567 goto out_unlock; 568 } 569 570 inet = inet_sk(sk); 571 if (!sock_owned_by_user(sk) && inet->recverr) { 572 sk->sk_err = err; 573 sk->sk_error_report(sk); 574 } else { /* Only an error on timeout */ 575 sk->sk_err_soft = err; 576 } 577 578 out_unlock: 579 sctp_err_finish(sk, asoc); 580 } 581 582 /* 583 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 584 * 585 * This function scans all the chunks in the OOTB packet to determine if 586 * the packet should be discarded right away. If a response might be needed 587 * for this packet, or, if further processing is possible, the packet will 588 * be queued to a proper inqueue for the next phase of handling. 589 * 590 * Output: 591 * Return 0 - If further processing is needed. 592 * Return 1 - If the packet can be discarded right away. 593 */ 594 static int sctp_rcv_ootb(struct sk_buff *skb) 595 { 596 sctp_chunkhdr_t *ch; 597 __u8 *ch_end; 598 sctp_errhdr_t *err; 599 600 ch = (sctp_chunkhdr_t *) skb->data; 601 602 /* Scan through all the chunks in the packet. */ 603 do { 604 /* Break out if chunk length is less then minimal. */ 605 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 606 break; 607 608 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 609 if (ch_end > skb_tail_pointer(skb)) 610 break; 611 612 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 613 * receiver MUST silently discard the OOTB packet and take no 614 * further action. 615 */ 616 if (SCTP_CID_ABORT == ch->type) 617 goto discard; 618 619 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 620 * chunk, the receiver should silently discard the packet 621 * and take no further action. 622 */ 623 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 624 goto discard; 625 626 /* RFC 4460, 2.11.2 627 * This will discard packets with INIT chunk bundled as 628 * subsequent chunks in the packet. When INIT is first, 629 * the normal INIT processing will discard the chunk. 630 */ 631 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 632 goto discard; 633 634 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR 635 * or a COOKIE ACK the SCTP Packet should be silently 636 * discarded. 637 */ 638 if (SCTP_CID_COOKIE_ACK == ch->type) 639 goto discard; 640 641 if (SCTP_CID_ERROR == ch->type) { 642 sctp_walk_errors(err, ch) { 643 if (SCTP_ERROR_STALE_COOKIE == err->cause) 644 goto discard; 645 } 646 } 647 648 ch = (sctp_chunkhdr_t *) ch_end; 649 } while (ch_end < skb_tail_pointer(skb)); 650 651 return 0; 652 653 discard: 654 return 1; 655 } 656 657 /* Insert endpoint into the hash table. */ 658 static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 659 { 660 struct sctp_ep_common *epb; 661 struct sctp_hashbucket *head; 662 663 epb = &ep->base; 664 665 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 666 head = &sctp_ep_hashtable[epb->hashent]; 667 668 sctp_write_lock(&head->lock); 669 hlist_add_head(&epb->node, &head->chain); 670 sctp_write_unlock(&head->lock); 671 } 672 673 /* Add an endpoint to the hash. Local BH-safe. */ 674 void sctp_hash_endpoint(struct sctp_endpoint *ep) 675 { 676 sctp_local_bh_disable(); 677 __sctp_hash_endpoint(ep); 678 sctp_local_bh_enable(); 679 } 680 681 /* Remove endpoint from the hash table. */ 682 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 683 { 684 struct sctp_hashbucket *head; 685 struct sctp_ep_common *epb; 686 687 epb = &ep->base; 688 689 if (hlist_unhashed(&epb->node)) 690 return; 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 __hlist_del(&epb->node); 698 sctp_write_unlock(&head->lock); 699 } 700 701 /* Remove endpoint from the hash. Local BH-safe. */ 702 void sctp_unhash_endpoint(struct sctp_endpoint *ep) 703 { 704 sctp_local_bh_disable(); 705 __sctp_unhash_endpoint(ep); 706 sctp_local_bh_enable(); 707 } 708 709 /* Look up an endpoint. */ 710 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr) 711 { 712 struct sctp_hashbucket *head; 713 struct sctp_ep_common *epb; 714 struct sctp_endpoint *ep; 715 struct hlist_node *node; 716 int hash; 717 718 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port)); 719 head = &sctp_ep_hashtable[hash]; 720 read_lock(&head->lock); 721 sctp_for_each_hentry(epb, node, &head->chain) { 722 ep = sctp_ep(epb); 723 if (sctp_endpoint_is_match(ep, laddr)) 724 goto hit; 725 } 726 727 ep = sctp_sk((sctp_get_ctl_sock()))->ep; 728 729 hit: 730 sctp_endpoint_hold(ep); 731 read_unlock(&head->lock); 732 return ep; 733 } 734 735 /* Insert association into the hash table. */ 736 static void __sctp_hash_established(struct sctp_association *asoc) 737 { 738 struct sctp_ep_common *epb; 739 struct sctp_hashbucket *head; 740 741 epb = &asoc->base; 742 743 /* Calculate which chain this entry will belong to. */ 744 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port); 745 746 head = &sctp_assoc_hashtable[epb->hashent]; 747 748 sctp_write_lock(&head->lock); 749 hlist_add_head(&epb->node, &head->chain); 750 sctp_write_unlock(&head->lock); 751 } 752 753 /* Add an association to the hash. Local BH-safe. */ 754 void sctp_hash_established(struct sctp_association *asoc) 755 { 756 if (asoc->temp) 757 return; 758 759 sctp_local_bh_disable(); 760 __sctp_hash_established(asoc); 761 sctp_local_bh_enable(); 762 } 763 764 /* Remove association from the hash table. */ 765 static void __sctp_unhash_established(struct sctp_association *asoc) 766 { 767 struct sctp_hashbucket *head; 768 struct sctp_ep_common *epb; 769 770 epb = &asoc->base; 771 772 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, 773 asoc->peer.port); 774 775 head = &sctp_assoc_hashtable[epb->hashent]; 776 777 sctp_write_lock(&head->lock); 778 __hlist_del(&epb->node); 779 sctp_write_unlock(&head->lock); 780 } 781 782 /* Remove association from the hash table. Local BH-safe. */ 783 void sctp_unhash_established(struct sctp_association *asoc) 784 { 785 if (asoc->temp) 786 return; 787 788 sctp_local_bh_disable(); 789 __sctp_unhash_established(asoc); 790 sctp_local_bh_enable(); 791 } 792 793 /* Look up an association. */ 794 static struct sctp_association *__sctp_lookup_association( 795 const union sctp_addr *local, 796 const union sctp_addr *peer, 797 struct sctp_transport **pt) 798 { 799 struct sctp_hashbucket *head; 800 struct sctp_ep_common *epb; 801 struct sctp_association *asoc; 802 struct sctp_transport *transport; 803 struct hlist_node *node; 804 int hash; 805 806 /* Optimize here for direct hit, only listening connections can 807 * have wildcards anyways. 808 */ 809 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port)); 810 head = &sctp_assoc_hashtable[hash]; 811 read_lock(&head->lock); 812 sctp_for_each_hentry(epb, node, &head->chain) { 813 asoc = sctp_assoc(epb); 814 transport = sctp_assoc_is_match(asoc, local, peer); 815 if (transport) 816 goto hit; 817 } 818 819 read_unlock(&head->lock); 820 821 return NULL; 822 823 hit: 824 *pt = transport; 825 sctp_association_hold(asoc); 826 read_unlock(&head->lock); 827 return asoc; 828 } 829 830 /* Look up an association. BH-safe. */ 831 SCTP_STATIC 832 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr, 833 const union sctp_addr *paddr, 834 struct sctp_transport **transportp) 835 { 836 struct sctp_association *asoc; 837 838 sctp_local_bh_disable(); 839 asoc = __sctp_lookup_association(laddr, paddr, transportp); 840 sctp_local_bh_enable(); 841 842 return asoc; 843 } 844 845 /* Is there an association matching the given local and peer addresses? */ 846 int sctp_has_association(const union sctp_addr *laddr, 847 const union sctp_addr *paddr) 848 { 849 struct sctp_association *asoc; 850 struct sctp_transport *transport; 851 852 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) { 853 sctp_association_put(asoc); 854 return 1; 855 } 856 857 return 0; 858 } 859 860 /* 861 * SCTP Implementors Guide, 2.18 Handling of address 862 * parameters within the INIT or INIT-ACK. 863 * 864 * D) When searching for a matching TCB upon reception of an INIT 865 * or INIT-ACK chunk the receiver SHOULD use not only the 866 * source address of the packet (containing the INIT or 867 * INIT-ACK) but the receiver SHOULD also use all valid 868 * address parameters contained within the chunk. 869 * 870 * 2.18.3 Solution description 871 * 872 * This new text clearly specifies to an implementor the need 873 * to look within the INIT or INIT-ACK. Any implementation that 874 * does not do this, may not be able to establish associations 875 * in certain circumstances. 876 * 877 */ 878 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb, 879 const union sctp_addr *laddr, struct sctp_transport **transportp) 880 { 881 struct sctp_association *asoc; 882 union sctp_addr addr; 883 union sctp_addr *paddr = &addr; 884 struct sctphdr *sh = sctp_hdr(skb); 885 sctp_chunkhdr_t *ch; 886 union sctp_params params; 887 sctp_init_chunk_t *init; 888 struct sctp_transport *transport; 889 struct sctp_af *af; 890 891 ch = (sctp_chunkhdr_t *) skb->data; 892 893 /* 894 * This code will NOT touch anything inside the chunk--it is 895 * strictly READ-ONLY. 896 * 897 * RFC 2960 3 SCTP packet Format 898 * 899 * Multiple chunks can be bundled into one SCTP packet up to 900 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 901 * COMPLETE chunks. These chunks MUST NOT be bundled with any 902 * other chunk in a packet. See Section 6.10 for more details 903 * on chunk bundling. 904 */ 905 906 /* Find the start of the TLVs and the end of the chunk. This is 907 * the region we search for address parameters. 908 */ 909 init = (sctp_init_chunk_t *)skb->data; 910 911 /* Walk the parameters looking for embedded addresses. */ 912 sctp_walk_params(params, init, init_hdr.params) { 913 914 /* Note: Ignoring hostname addresses. */ 915 af = sctp_get_af_specific(param_type2af(params.p->type)); 916 if (!af) 917 continue; 918 919 af->from_addr_param(paddr, params.addr, sh->source, 0); 920 921 asoc = __sctp_lookup_association(laddr, paddr, &transport); 922 if (asoc) 923 return asoc; 924 } 925 926 return NULL; 927 } 928 929 /* ADD-IP, Section 5.2 930 * When an endpoint receives an ASCONF Chunk from the remote peer 931 * special procedures may be needed to identify the association the 932 * ASCONF Chunk is associated with. To properly find the association 933 * the following procedures SHOULD be followed: 934 * 935 * D2) If the association is not found, use the address found in the 936 * Address Parameter TLV combined with the port number found in the 937 * SCTP common header. If found proceed to rule D4. 938 * 939 * D2-ext) If more than one ASCONF Chunks are packed together, use the 940 * address found in the ASCONF Address Parameter TLV of each of the 941 * subsequent ASCONF Chunks. If found, proceed to rule D4. 942 */ 943 static struct sctp_association *__sctp_rcv_asconf_lookup( 944 sctp_chunkhdr_t *ch, 945 const union sctp_addr *laddr, 946 __be16 peer_port, 947 struct sctp_transport **transportp) 948 { 949 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; 950 struct sctp_af *af; 951 union sctp_addr_param *param; 952 union sctp_addr paddr; 953 954 /* Skip over the ADDIP header and find the Address parameter */ 955 param = (union sctp_addr_param *)(asconf + 1); 956 957 af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type)); 958 if (unlikely(!af)) 959 return NULL; 960 961 af->from_addr_param(&paddr, param, peer_port, 0); 962 963 return __sctp_lookup_association(laddr, &paddr, transportp); 964 } 965 966 967 /* SCTP-AUTH, Section 6.3: 968 * If the receiver does not find a STCB for a packet containing an AUTH 969 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second 970 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing 971 * association. 972 * 973 * This means that any chunks that can help us identify the association need 974 * to be looked at to find this assocation. 975 */ 976 static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb, 977 const union sctp_addr *laddr, 978 struct sctp_transport **transportp) 979 { 980 struct sctp_association *asoc = NULL; 981 sctp_chunkhdr_t *ch; 982 int have_auth = 0; 983 unsigned int chunk_num = 1; 984 __u8 *ch_end; 985 986 /* Walk through the chunks looking for AUTH or ASCONF chunks 987 * to help us find the association. 988 */ 989 ch = (sctp_chunkhdr_t *) skb->data; 990 do { 991 /* Break out if chunk length is less then minimal. */ 992 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 993 break; 994 995 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 996 if (ch_end > skb_tail_pointer(skb)) 997 break; 998 999 switch(ch->type) { 1000 case SCTP_CID_AUTH: 1001 have_auth = chunk_num; 1002 break; 1003 1004 case SCTP_CID_COOKIE_ECHO: 1005 /* If a packet arrives containing an AUTH chunk as 1006 * a first chunk, a COOKIE-ECHO chunk as the second 1007 * chunk, and possibly more chunks after them, and 1008 * the receiver does not have an STCB for that 1009 * packet, then authentication is based on 1010 * the contents of the COOKIE- ECHO chunk. 1011 */ 1012 if (have_auth == 1 && chunk_num == 2) 1013 return NULL; 1014 break; 1015 1016 case SCTP_CID_ASCONF: 1017 if (have_auth || sctp_addip_noauth) 1018 asoc = __sctp_rcv_asconf_lookup(ch, laddr, 1019 sctp_hdr(skb)->source, 1020 transportp); 1021 default: 1022 break; 1023 } 1024 1025 if (asoc) 1026 break; 1027 1028 ch = (sctp_chunkhdr_t *) ch_end; 1029 chunk_num++; 1030 } while (ch_end < skb_tail_pointer(skb)); 1031 1032 return asoc; 1033 } 1034 1035 /* 1036 * There are circumstances when we need to look inside the SCTP packet 1037 * for information to help us find the association. Examples 1038 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1039 * chunks. 1040 */ 1041 static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb, 1042 const union sctp_addr *laddr, 1043 struct sctp_transport **transportp) 1044 { 1045 sctp_chunkhdr_t *ch; 1046 1047 ch = (sctp_chunkhdr_t *) skb->data; 1048 1049 /* The code below will attempt to walk the chunk and extract 1050 * parameter information. Before we do that, we need to verify 1051 * that the chunk length doesn't cause overflow. Otherwise, we'll 1052 * walk off the end. 1053 */ 1054 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 1055 return NULL; 1056 1057 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1058 switch (ch->type) { 1059 case SCTP_CID_INIT: 1060 case SCTP_CID_INIT_ACK: 1061 return __sctp_rcv_init_lookup(skb, laddr, transportp); 1062 break; 1063 1064 default: 1065 return __sctp_rcv_walk_lookup(skb, laddr, transportp); 1066 break; 1067 } 1068 1069 1070 return NULL; 1071 } 1072 1073 /* Lookup an association for an inbound skb. */ 1074 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 1075 const union sctp_addr *paddr, 1076 const union sctp_addr *laddr, 1077 struct sctp_transport **transportp) 1078 { 1079 struct sctp_association *asoc; 1080 1081 asoc = __sctp_lookup_association(laddr, paddr, transportp); 1082 1083 /* Further lookup for INIT/INIT-ACK packets. 1084 * SCTP Implementors Guide, 2.18 Handling of address 1085 * parameters within the INIT or INIT-ACK. 1086 */ 1087 if (!asoc) 1088 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp); 1089 1090 return asoc; 1091 } 1092