input.c revision a3a858ff18a72a8d388e31ab0d98f7e944841a62
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#include <net/net_namespace.h> 65 66/* Forward declarations for internal helpers. */ 67static int sctp_rcv_ootb(struct sk_buff *); 68static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 69 const union sctp_addr *laddr, 70 const union sctp_addr *paddr, 71 struct sctp_transport **transportp); 72static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr); 73static struct sctp_association *__sctp_lookup_association( 74 const union sctp_addr *local, 75 const union sctp_addr *peer, 76 struct sctp_transport **pt); 77 78static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 79 80 81/* Calculate the SCTP checksum of an SCTP packet. */ 82static inline int sctp_rcv_checksum(struct sk_buff *skb) 83{ 84 struct sctphdr *sh = sctp_hdr(skb); 85 __le32 cmp = sh->checksum; 86 struct sk_buff *list; 87 __le32 val; 88 __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); 89 90 skb_walk_frags(skb, list) 91 tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), 92 tmp); 93 94 val = sctp_end_cksum(tmp); 95 96 if (val != cmp) { 97 /* CRC failure, dump it. */ 98 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); 99 return -1; 100 } 101 return 0; 102} 103 104struct sctp_input_cb { 105 union { 106 struct inet_skb_parm h4; 107#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 108 struct inet6_skb_parm h6; 109#endif 110 } header; 111 struct sctp_chunk *chunk; 112}; 113#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 114 115/* 116 * This is the routine which IP calls when receiving an SCTP packet. 117 */ 118int sctp_rcv(struct sk_buff *skb) 119{ 120 struct sock *sk; 121 struct sctp_association *asoc; 122 struct sctp_endpoint *ep = NULL; 123 struct sctp_ep_common *rcvr; 124 struct sctp_transport *transport = NULL; 125 struct sctp_chunk *chunk; 126 struct sctphdr *sh; 127 union sctp_addr src; 128 union sctp_addr dest; 129 int family; 130 struct sctp_af *af; 131 132 if (skb->pkt_type!=PACKET_HOST) 133 goto discard_it; 134 135 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); 136 137 if (skb_linearize(skb)) 138 goto discard_it; 139 140 sh = sctp_hdr(skb); 141 142 /* Pull up the IP and SCTP headers. */ 143 __skb_pull(skb, skb_transport_offset(skb)); 144 if (skb->len < sizeof(struct sctphdr)) 145 goto discard_it; 146 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) && 147 sctp_rcv_checksum(skb) < 0) 148 goto discard_it; 149 150 skb_pull(skb, sizeof(struct sctphdr)); 151 152 /* Make sure we at least have chunk headers worth of data left. */ 153 if (skb->len < sizeof(struct sctp_chunkhdr)) 154 goto discard_it; 155 156 family = ipver2af(ip_hdr(skb)->version); 157 af = sctp_get_af_specific(family); 158 if (unlikely(!af)) 159 goto discard_it; 160 161 /* Initialize local addresses for lookups. */ 162 af->from_skb(&src, skb, 1); 163 af->from_skb(&dest, skb, 0); 164 165 /* If the packet is to or from a non-unicast address, 166 * silently discard the packet. 167 * 168 * This is not clearly defined in the RFC except in section 169 * 8.4 - OOTB handling. However, based on the book "Stream Control 170 * Transmission Protocol" 2.1, "It is important to note that the 171 * IP address of an SCTP transport address must be a routable 172 * unicast address. In other words, IP multicast addresses and 173 * IP broadcast addresses cannot be used in an SCTP transport 174 * address." 175 */ 176 if (!af->addr_valid(&src, NULL, skb) || 177 !af->addr_valid(&dest, NULL, skb)) 178 goto discard_it; 179 180 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); 181 182 if (!asoc) 183 ep = __sctp_rcv_lookup_endpoint(&dest); 184 185 /* Retrieve the common input handling substructure. */ 186 rcvr = asoc ? &asoc->base : &ep->base; 187 sk = rcvr->sk; 188 189 /* 190 * If a frame arrives on an interface and the receiving socket is 191 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 192 */ 193 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) 194 { 195 if (asoc) { 196 sctp_association_put(asoc); 197 asoc = NULL; 198 } else { 199 sctp_endpoint_put(ep); 200 ep = NULL; 201 } 202 sk = sctp_get_ctl_sock(); 203 ep = sctp_sk(sk)->ep; 204 sctp_endpoint_hold(ep); 205 rcvr = &ep->base; 206 } 207 208 /* 209 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 210 * An SCTP packet is called an "out of the blue" (OOTB) 211 * packet if it is correctly formed, i.e., passed the 212 * receiver's checksum check, but the receiver is not 213 * able to identify the association to which this 214 * packet belongs. 215 */ 216 if (!asoc) { 217 if (sctp_rcv_ootb(skb)) { 218 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); 219 goto discard_release; 220 } 221 } 222 223 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 224 goto discard_release; 225 nf_reset(skb); 226 227 if (sk_filter(sk, skb)) 228 goto discard_release; 229 230 /* Create an SCTP packet structure. */ 231 chunk = sctp_chunkify(skb, asoc, sk); 232 if (!chunk) 233 goto discard_release; 234 SCTP_INPUT_CB(skb)->chunk = chunk; 235 236 /* Remember what endpoint is to handle this packet. */ 237 chunk->rcvr = rcvr; 238 239 /* Remember the SCTP header. */ 240 chunk->sctp_hdr = sh; 241 242 /* Set the source and destination addresses of the incoming chunk. */ 243 sctp_init_addrs(chunk, &src, &dest); 244 245 /* Remember where we came from. */ 246 chunk->transport = transport; 247 248 /* Acquire access to the sock lock. Note: We are safe from other 249 * bottom halves on this lock, but a user may be in the lock too, 250 * so check if it is busy. 251 */ 252 sctp_bh_lock_sock(sk); 253 254 if (sk != rcvr->sk) { 255 /* Our cached sk is different from the rcvr->sk. This is 256 * because migrate()/accept() may have moved the association 257 * to a new socket and released all the sockets. So now we 258 * are holding a lock on the old socket while the user may 259 * be doing something with the new socket. Switch our veiw 260 * of the current sk. 261 */ 262 sctp_bh_unlock_sock(sk); 263 sk = rcvr->sk; 264 sctp_bh_lock_sock(sk); 265 } 266 267 if (sock_owned_by_user(sk)) { 268 if (sctp_add_backlog(sk, skb)) { 269 sctp_bh_unlock_sock(sk); 270 sctp_chunk_free(chunk); 271 skb = NULL; /* sctp_chunk_free already freed the skb */ 272 goto discard_release; 273 } 274 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG); 275 } else { 276 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ); 277 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 278 } 279 280 sctp_bh_unlock_sock(sk); 281 282 /* Release the asoc/ep ref we took in the lookup calls. */ 283 if (asoc) 284 sctp_association_put(asoc); 285 else 286 sctp_endpoint_put(ep); 287 288 return 0; 289 290discard_it: 291 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS); 292 kfree_skb(skb); 293 return 0; 294 295discard_release: 296 /* Release the asoc/ep ref we took in the lookup calls. */ 297 if (asoc) 298 sctp_association_put(asoc); 299 else 300 sctp_endpoint_put(ep); 301 302 goto discard_it; 303} 304 305/* Process the backlog queue of the socket. Every skb on 306 * the backlog holds a ref on an association or endpoint. 307 * We hold this ref throughout the state machine to make 308 * sure that the structure we need is still around. 309 */ 310int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 311{ 312 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 313 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 314 struct sctp_ep_common *rcvr = NULL; 315 int backloged = 0; 316 317 rcvr = chunk->rcvr; 318 319 /* If the rcvr is dead then the association or endpoint 320 * has been deleted and we can safely drop the chunk 321 * and refs that we are holding. 322 */ 323 if (rcvr->dead) { 324 sctp_chunk_free(chunk); 325 goto done; 326 } 327 328 if (unlikely(rcvr->sk != sk)) { 329 /* In this case, the association moved from one socket to 330 * another. We are currently sitting on the backlog of the 331 * old socket, so we need to move. 332 * However, since we are here in the process context we 333 * need to take make sure that the user doesn't own 334 * the new socket when we process the packet. 335 * If the new socket is user-owned, queue the chunk to the 336 * backlog of the new socket without dropping any refs. 337 * Otherwise, we can safely push the chunk on the inqueue. 338 */ 339 340 sk = rcvr->sk; 341 sctp_bh_lock_sock(sk); 342 343 if (sock_owned_by_user(sk)) { 344 if (sk_add_backlog(sk, skb)) 345 sctp_chunk_free(chunk); 346 else 347 backloged = 1; 348 } else 349 sctp_inq_push(inqueue, chunk); 350 351 sctp_bh_unlock_sock(sk); 352 353 /* If the chunk was backloged again, don't drop refs */ 354 if (backloged) 355 return 0; 356 } else { 357 sctp_inq_push(inqueue, chunk); 358 } 359 360done: 361 /* Release the refs we took in sctp_add_backlog */ 362 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 363 sctp_association_put(sctp_assoc(rcvr)); 364 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 365 sctp_endpoint_put(sctp_ep(rcvr)); 366 else 367 BUG(); 368 369 return 0; 370} 371 372static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 373{ 374 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 375 struct sctp_ep_common *rcvr = chunk->rcvr; 376 int ret; 377 378 ret = sk_add_backlog(sk, skb); 379 if (!ret) { 380 /* Hold the assoc/ep while hanging on the backlog queue. 381 * This way, we know structures we need will not disappear 382 * from us 383 */ 384 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 385 sctp_association_hold(sctp_assoc(rcvr)); 386 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 387 sctp_endpoint_hold(sctp_ep(rcvr)); 388 else 389 BUG(); 390 } 391 return ret; 392 393} 394 395/* Handle icmp frag needed error. */ 396void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 397 struct sctp_transport *t, __u32 pmtu) 398{ 399 if (!t || (t->pathmtu <= pmtu)) 400 return; 401 402 if (sock_owned_by_user(sk)) { 403 asoc->pmtu_pending = 1; 404 t->pmtu_pending = 1; 405 return; 406 } 407 408 if (t->param_flags & SPP_PMTUD_ENABLE) { 409 /* Update transports view of the MTU */ 410 sctp_transport_update_pmtu(t, pmtu); 411 412 /* Update association pmtu. */ 413 sctp_assoc_sync_pmtu(asoc); 414 } 415 416 /* Retransmit with the new pmtu setting. 417 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 418 * Needed will never be sent, but if a message was sent before 419 * PMTU discovery was disabled that was larger than the PMTU, it 420 * would not be fragmented, so it must be re-transmitted fragmented. 421 */ 422 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 423} 424 425/* 426 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 427 * 428 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 429 * or a "Protocol Unreachable" treat this message as an abort 430 * with the T bit set. 431 * 432 * This function sends an event to the state machine, which will abort the 433 * association. 434 * 435 */ 436void sctp_icmp_proto_unreachable(struct sock *sk, 437 struct sctp_association *asoc, 438 struct sctp_transport *t) 439{ 440 SCTP_DEBUG_PRINTK("%s\n", __func__); 441 442 sctp_do_sm(SCTP_EVENT_T_OTHER, 443 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 444 asoc->state, asoc->ep, asoc, t, 445 GFP_ATOMIC); 446 447} 448 449/* Common lookup code for icmp/icmpv6 error handler. */ 450struct sock *sctp_err_lookup(int family, struct sk_buff *skb, 451 struct sctphdr *sctphdr, 452 struct sctp_association **app, 453 struct sctp_transport **tpp) 454{ 455 union sctp_addr saddr; 456 union sctp_addr daddr; 457 struct sctp_af *af; 458 struct sock *sk = NULL; 459 struct sctp_association *asoc; 460 struct sctp_transport *transport = NULL; 461 struct sctp_init_chunk *chunkhdr; 462 __u32 vtag = ntohl(sctphdr->vtag); 463 int len = skb->len - ((void *)sctphdr - (void *)skb->data); 464 465 *app = NULL; *tpp = NULL; 466 467 af = sctp_get_af_specific(family); 468 if (unlikely(!af)) { 469 return NULL; 470 } 471 472 /* Initialize local addresses for lookups. */ 473 af->from_skb(&saddr, skb, 1); 474 af->from_skb(&daddr, skb, 0); 475 476 /* Look for an association that matches the incoming ICMP error 477 * packet. 478 */ 479 asoc = __sctp_lookup_association(&saddr, &daddr, &transport); 480 if (!asoc) 481 return NULL; 482 483 sk = asoc->base.sk; 484 485 /* RFC 4960, Appendix C. ICMP Handling 486 * 487 * ICMP6) An implementation MUST validate that the Verification Tag 488 * contained in the ICMP message matches the Verification Tag of 489 * the peer. If the Verification Tag is not 0 and does NOT 490 * match, discard the ICMP message. If it is 0 and the ICMP 491 * message contains enough bytes to verify that the chunk type is 492 * an INIT chunk and that the Initiate Tag matches the tag of the 493 * peer, continue with ICMP7. If the ICMP message is too short 494 * or the chunk type or the Initiate Tag does not match, silently 495 * discard the packet. 496 */ 497 if (vtag == 0) { 498 chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr 499 + sizeof(struct sctphdr)); 500 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) 501 + sizeof(__be32) || 502 chunkhdr->chunk_hdr.type != SCTP_CID_INIT || 503 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { 504 goto out; 505 } 506 } else if (vtag != asoc->c.peer_vtag) { 507 goto out; 508 } 509 510 sctp_bh_lock_sock(sk); 511 512 /* If too many ICMPs get dropped on busy 513 * servers this needs to be solved differently. 514 */ 515 if (sock_owned_by_user(sk)) 516 NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS); 517 518 *app = asoc; 519 *tpp = transport; 520 return sk; 521 522out: 523 if (asoc) 524 sctp_association_put(asoc); 525 return NULL; 526} 527 528/* Common cleanup code for icmp/icmpv6 error handler. */ 529void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 530{ 531 sctp_bh_unlock_sock(sk); 532 if (asoc) 533 sctp_association_put(asoc); 534} 535 536/* 537 * This routine is called by the ICMP module when it gets some 538 * sort of error condition. If err < 0 then the socket should 539 * be closed and the error returned to the user. If err > 0 540 * it's just the icmp type << 8 | icmp code. After adjustment 541 * header points to the first 8 bytes of the sctp header. We need 542 * to find the appropriate port. 543 * 544 * The locking strategy used here is very "optimistic". When 545 * someone else accesses the socket the ICMP is just dropped 546 * and for some paths there is no check at all. 547 * A more general error queue to queue errors for later handling 548 * is probably better. 549 * 550 */ 551void sctp_v4_err(struct sk_buff *skb, __u32 info) 552{ 553 struct iphdr *iph = (struct iphdr *)skb->data; 554 const int ihlen = iph->ihl * 4; 555 const int type = icmp_hdr(skb)->type; 556 const int code = icmp_hdr(skb)->code; 557 struct sock *sk; 558 struct sctp_association *asoc = NULL; 559 struct sctp_transport *transport; 560 struct inet_sock *inet; 561 sk_buff_data_t saveip, savesctp; 562 int err; 563 564 if (skb->len < ihlen + 8) { 565 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); 566 return; 567 } 568 569 /* Fix up skb to look at the embedded net header. */ 570 saveip = skb->network_header; 571 savesctp = skb->transport_header; 572 skb_reset_network_header(skb); 573 skb_set_transport_header(skb, ihlen); 574 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 575 /* Put back, the original values. */ 576 skb->network_header = saveip; 577 skb->transport_header = savesctp; 578 if (!sk) { 579 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); 580 return; 581 } 582 /* Warning: The sock lock is held. Remember to call 583 * sctp_err_finish! 584 */ 585 586 switch (type) { 587 case ICMP_PARAMETERPROB: 588 err = EPROTO; 589 break; 590 case ICMP_DEST_UNREACH: 591 if (code > NR_ICMP_UNREACH) 592 goto out_unlock; 593 594 /* PMTU discovery (RFC1191) */ 595 if (ICMP_FRAG_NEEDED == code) { 596 sctp_icmp_frag_needed(sk, asoc, transport, info); 597 goto out_unlock; 598 } 599 else { 600 if (ICMP_PROT_UNREACH == code) { 601 sctp_icmp_proto_unreachable(sk, asoc, 602 transport); 603 goto out_unlock; 604 } 605 } 606 err = icmp_err_convert[code].errno; 607 break; 608 case ICMP_TIME_EXCEEDED: 609 /* Ignore any time exceeded errors due to fragment reassembly 610 * timeouts. 611 */ 612 if (ICMP_EXC_FRAGTIME == code) 613 goto out_unlock; 614 615 err = EHOSTUNREACH; 616 break; 617 default: 618 goto out_unlock; 619 } 620 621 inet = inet_sk(sk); 622 if (!sock_owned_by_user(sk) && inet->recverr) { 623 sk->sk_err = err; 624 sk->sk_error_report(sk); 625 } else { /* Only an error on timeout */ 626 sk->sk_err_soft = err; 627 } 628 629out_unlock: 630 sctp_err_finish(sk, asoc); 631} 632 633/* 634 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 635 * 636 * This function scans all the chunks in the OOTB packet to determine if 637 * the packet should be discarded right away. If a response might be needed 638 * for this packet, or, if further processing is possible, the packet will 639 * be queued to a proper inqueue for the next phase of handling. 640 * 641 * Output: 642 * Return 0 - If further processing is needed. 643 * Return 1 - If the packet can be discarded right away. 644 */ 645static int sctp_rcv_ootb(struct sk_buff *skb) 646{ 647 sctp_chunkhdr_t *ch; 648 __u8 *ch_end; 649 sctp_errhdr_t *err; 650 651 ch = (sctp_chunkhdr_t *) skb->data; 652 653 /* Scan through all the chunks in the packet. */ 654 do { 655 /* Break out if chunk length is less then minimal. */ 656 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 657 break; 658 659 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 660 if (ch_end > skb_tail_pointer(skb)) 661 break; 662 663 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 664 * receiver MUST silently discard the OOTB packet and take no 665 * further action. 666 */ 667 if (SCTP_CID_ABORT == ch->type) 668 goto discard; 669 670 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 671 * chunk, the receiver should silently discard the packet 672 * and take no further action. 673 */ 674 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 675 goto discard; 676 677 /* RFC 4460, 2.11.2 678 * This will discard packets with INIT chunk bundled as 679 * subsequent chunks in the packet. When INIT is first, 680 * the normal INIT processing will discard the chunk. 681 */ 682 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 683 goto discard; 684 685 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR 686 * or a COOKIE ACK the SCTP Packet should be silently 687 * discarded. 688 */ 689 if (SCTP_CID_COOKIE_ACK == ch->type) 690 goto discard; 691 692 if (SCTP_CID_ERROR == ch->type) { 693 sctp_walk_errors(err, ch) { 694 if (SCTP_ERROR_STALE_COOKIE == err->cause) 695 goto discard; 696 } 697 } 698 699 ch = (sctp_chunkhdr_t *) ch_end; 700 } while (ch_end < skb_tail_pointer(skb)); 701 702 return 0; 703 704discard: 705 return 1; 706} 707 708/* Insert endpoint into the hash table. */ 709static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 710{ 711 struct sctp_ep_common *epb; 712 struct sctp_hashbucket *head; 713 714 epb = &ep->base; 715 716 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 717 head = &sctp_ep_hashtable[epb->hashent]; 718 719 sctp_write_lock(&head->lock); 720 hlist_add_head(&epb->node, &head->chain); 721 sctp_write_unlock(&head->lock); 722} 723 724/* Add an endpoint to the hash. Local BH-safe. */ 725void sctp_hash_endpoint(struct sctp_endpoint *ep) 726{ 727 sctp_local_bh_disable(); 728 __sctp_hash_endpoint(ep); 729 sctp_local_bh_enable(); 730} 731 732/* Remove endpoint from the hash table. */ 733static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 734{ 735 struct sctp_hashbucket *head; 736 struct sctp_ep_common *epb; 737 738 epb = &ep->base; 739 740 if (hlist_unhashed(&epb->node)) 741 return; 742 743 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); 744 745 head = &sctp_ep_hashtable[epb->hashent]; 746 747 sctp_write_lock(&head->lock); 748 __hlist_del(&epb->node); 749 sctp_write_unlock(&head->lock); 750} 751 752/* Remove endpoint from the hash. Local BH-safe. */ 753void sctp_unhash_endpoint(struct sctp_endpoint *ep) 754{ 755 sctp_local_bh_disable(); 756 __sctp_unhash_endpoint(ep); 757 sctp_local_bh_enable(); 758} 759 760/* Look up an endpoint. */ 761static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr) 762{ 763 struct sctp_hashbucket *head; 764 struct sctp_ep_common *epb; 765 struct sctp_endpoint *ep; 766 struct hlist_node *node; 767 int hash; 768 769 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port)); 770 head = &sctp_ep_hashtable[hash]; 771 read_lock(&head->lock); 772 sctp_for_each_hentry(epb, node, &head->chain) { 773 ep = sctp_ep(epb); 774 if (sctp_endpoint_is_match(ep, laddr)) 775 goto hit; 776 } 777 778 ep = sctp_sk((sctp_get_ctl_sock()))->ep; 779 780hit: 781 sctp_endpoint_hold(ep); 782 read_unlock(&head->lock); 783 return ep; 784} 785 786/* Insert association into the hash table. */ 787static void __sctp_hash_established(struct sctp_association *asoc) 788{ 789 struct sctp_ep_common *epb; 790 struct sctp_hashbucket *head; 791 792 epb = &asoc->base; 793 794 /* Calculate which chain this entry will belong to. */ 795 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port); 796 797 head = &sctp_assoc_hashtable[epb->hashent]; 798 799 sctp_write_lock(&head->lock); 800 hlist_add_head(&epb->node, &head->chain); 801 sctp_write_unlock(&head->lock); 802} 803 804/* Add an association to the hash. Local BH-safe. */ 805void sctp_hash_established(struct sctp_association *asoc) 806{ 807 if (asoc->temp) 808 return; 809 810 sctp_local_bh_disable(); 811 __sctp_hash_established(asoc); 812 sctp_local_bh_enable(); 813} 814 815/* Remove association from the hash table. */ 816static void __sctp_unhash_established(struct sctp_association *asoc) 817{ 818 struct sctp_hashbucket *head; 819 struct sctp_ep_common *epb; 820 821 epb = &asoc->base; 822 823 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, 824 asoc->peer.port); 825 826 head = &sctp_assoc_hashtable[epb->hashent]; 827 828 sctp_write_lock(&head->lock); 829 __hlist_del(&epb->node); 830 sctp_write_unlock(&head->lock); 831} 832 833/* Remove association from the hash table. Local BH-safe. */ 834void sctp_unhash_established(struct sctp_association *asoc) 835{ 836 if (asoc->temp) 837 return; 838 839 sctp_local_bh_disable(); 840 __sctp_unhash_established(asoc); 841 sctp_local_bh_enable(); 842} 843 844/* Look up an association. */ 845static struct sctp_association *__sctp_lookup_association( 846 const union sctp_addr *local, 847 const union sctp_addr *peer, 848 struct sctp_transport **pt) 849{ 850 struct sctp_hashbucket *head; 851 struct sctp_ep_common *epb; 852 struct sctp_association *asoc; 853 struct sctp_transport *transport; 854 struct hlist_node *node; 855 int hash; 856 857 /* Optimize here for direct hit, only listening connections can 858 * have wildcards anyways. 859 */ 860 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port)); 861 head = &sctp_assoc_hashtable[hash]; 862 read_lock(&head->lock); 863 sctp_for_each_hentry(epb, node, &head->chain) { 864 asoc = sctp_assoc(epb); 865 transport = sctp_assoc_is_match(asoc, local, peer); 866 if (transport) 867 goto hit; 868 } 869 870 read_unlock(&head->lock); 871 872 return NULL; 873 874hit: 875 *pt = transport; 876 sctp_association_hold(asoc); 877 read_unlock(&head->lock); 878 return asoc; 879} 880 881/* Look up an association. BH-safe. */ 882SCTP_STATIC 883struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr, 884 const union sctp_addr *paddr, 885 struct sctp_transport **transportp) 886{ 887 struct sctp_association *asoc; 888 889 sctp_local_bh_disable(); 890 asoc = __sctp_lookup_association(laddr, paddr, transportp); 891 sctp_local_bh_enable(); 892 893 return asoc; 894} 895 896/* Is there an association matching the given local and peer addresses? */ 897int sctp_has_association(const union sctp_addr *laddr, 898 const union sctp_addr *paddr) 899{ 900 struct sctp_association *asoc; 901 struct sctp_transport *transport; 902 903 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) { 904 sctp_association_put(asoc); 905 return 1; 906 } 907 908 return 0; 909} 910 911/* 912 * SCTP Implementors Guide, 2.18 Handling of address 913 * parameters within the INIT or INIT-ACK. 914 * 915 * D) When searching for a matching TCB upon reception of an INIT 916 * or INIT-ACK chunk the receiver SHOULD use not only the 917 * source address of the packet (containing the INIT or 918 * INIT-ACK) but the receiver SHOULD also use all valid 919 * address parameters contained within the chunk. 920 * 921 * 2.18.3 Solution description 922 * 923 * This new text clearly specifies to an implementor the need 924 * to look within the INIT or INIT-ACK. Any implementation that 925 * does not do this, may not be able to establish associations 926 * in certain circumstances. 927 * 928 */ 929static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb, 930 const union sctp_addr *laddr, struct sctp_transport **transportp) 931{ 932 struct sctp_association *asoc; 933 union sctp_addr addr; 934 union sctp_addr *paddr = &addr; 935 struct sctphdr *sh = sctp_hdr(skb); 936 sctp_chunkhdr_t *ch; 937 union sctp_params params; 938 sctp_init_chunk_t *init; 939 struct sctp_transport *transport; 940 struct sctp_af *af; 941 942 ch = (sctp_chunkhdr_t *) skb->data; 943 944 /* 945 * This code will NOT touch anything inside the chunk--it is 946 * strictly READ-ONLY. 947 * 948 * RFC 2960 3 SCTP packet Format 949 * 950 * Multiple chunks can be bundled into one SCTP packet up to 951 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 952 * COMPLETE chunks. These chunks MUST NOT be bundled with any 953 * other chunk in a packet. See Section 6.10 for more details 954 * on chunk bundling. 955 */ 956 957 /* Find the start of the TLVs and the end of the chunk. This is 958 * the region we search for address parameters. 959 */ 960 init = (sctp_init_chunk_t *)skb->data; 961 962 /* Walk the parameters looking for embedded addresses. */ 963 sctp_walk_params(params, init, init_hdr.params) { 964 965 /* Note: Ignoring hostname addresses. */ 966 af = sctp_get_af_specific(param_type2af(params.p->type)); 967 if (!af) 968 continue; 969 970 af->from_addr_param(paddr, params.addr, sh->source, 0); 971 972 asoc = __sctp_lookup_association(laddr, paddr, &transport); 973 if (asoc) 974 return asoc; 975 } 976 977 return NULL; 978} 979 980/* ADD-IP, Section 5.2 981 * When an endpoint receives an ASCONF Chunk from the remote peer 982 * special procedures may be needed to identify the association the 983 * ASCONF Chunk is associated with. To properly find the association 984 * the following procedures SHOULD be followed: 985 * 986 * D2) If the association is not found, use the address found in the 987 * Address Parameter TLV combined with the port number found in the 988 * SCTP common header. If found proceed to rule D4. 989 * 990 * D2-ext) If more than one ASCONF Chunks are packed together, use the 991 * address found in the ASCONF Address Parameter TLV of each of the 992 * subsequent ASCONF Chunks. If found, proceed to rule D4. 993 */ 994static struct sctp_association *__sctp_rcv_asconf_lookup( 995 sctp_chunkhdr_t *ch, 996 const union sctp_addr *laddr, 997 __be16 peer_port, 998 struct sctp_transport **transportp) 999{ 1000 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; 1001 struct sctp_af *af; 1002 union sctp_addr_param *param; 1003 union sctp_addr paddr; 1004 1005 /* Skip over the ADDIP header and find the Address parameter */ 1006 param = (union sctp_addr_param *)(asconf + 1); 1007 1008 af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type)); 1009 if (unlikely(!af)) 1010 return NULL; 1011 1012 af->from_addr_param(&paddr, param, peer_port, 0); 1013 1014 return __sctp_lookup_association(laddr, &paddr, transportp); 1015} 1016 1017 1018/* SCTP-AUTH, Section 6.3: 1019* If the receiver does not find a STCB for a packet containing an AUTH 1020* chunk as the first chunk and not a COOKIE-ECHO chunk as the second 1021* chunk, it MUST use the chunks after the AUTH chunk to look up an existing 1022* association. 1023* 1024* This means that any chunks that can help us identify the association need 1025* to be looked at to find this assocation. 1026*/ 1027static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb, 1028 const union sctp_addr *laddr, 1029 struct sctp_transport **transportp) 1030{ 1031 struct sctp_association *asoc = NULL; 1032 sctp_chunkhdr_t *ch; 1033 int have_auth = 0; 1034 unsigned int chunk_num = 1; 1035 __u8 *ch_end; 1036 1037 /* Walk through the chunks looking for AUTH or ASCONF chunks 1038 * to help us find the association. 1039 */ 1040 ch = (sctp_chunkhdr_t *) skb->data; 1041 do { 1042 /* Break out if chunk length is less then minimal. */ 1043 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 1044 break; 1045 1046 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 1047 if (ch_end > skb_tail_pointer(skb)) 1048 break; 1049 1050 switch(ch->type) { 1051 case SCTP_CID_AUTH: 1052 have_auth = chunk_num; 1053 break; 1054 1055 case SCTP_CID_COOKIE_ECHO: 1056 /* If a packet arrives containing an AUTH chunk as 1057 * a first chunk, a COOKIE-ECHO chunk as the second 1058 * chunk, and possibly more chunks after them, and 1059 * the receiver does not have an STCB for that 1060 * packet, then authentication is based on 1061 * the contents of the COOKIE- ECHO chunk. 1062 */ 1063 if (have_auth == 1 && chunk_num == 2) 1064 return NULL; 1065 break; 1066 1067 case SCTP_CID_ASCONF: 1068 if (have_auth || sctp_addip_noauth) 1069 asoc = __sctp_rcv_asconf_lookup(ch, laddr, 1070 sctp_hdr(skb)->source, 1071 transportp); 1072 default: 1073 break; 1074 } 1075 1076 if (asoc) 1077 break; 1078 1079 ch = (sctp_chunkhdr_t *) ch_end; 1080 chunk_num++; 1081 } while (ch_end < skb_tail_pointer(skb)); 1082 1083 return asoc; 1084} 1085 1086/* 1087 * There are circumstances when we need to look inside the SCTP packet 1088 * for information to help us find the association. Examples 1089 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1090 * chunks. 1091 */ 1092static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb, 1093 const union sctp_addr *laddr, 1094 struct sctp_transport **transportp) 1095{ 1096 sctp_chunkhdr_t *ch; 1097 1098 ch = (sctp_chunkhdr_t *) skb->data; 1099 1100 /* The code below will attempt to walk the chunk and extract 1101 * parameter information. Before we do that, we need to verify 1102 * that the chunk length doesn't cause overflow. Otherwise, we'll 1103 * walk off the end. 1104 */ 1105 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 1106 return NULL; 1107 1108 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1109 switch (ch->type) { 1110 case SCTP_CID_INIT: 1111 case SCTP_CID_INIT_ACK: 1112 return __sctp_rcv_init_lookup(skb, laddr, transportp); 1113 break; 1114 1115 default: 1116 return __sctp_rcv_walk_lookup(skb, laddr, transportp); 1117 break; 1118 } 1119 1120 1121 return NULL; 1122} 1123 1124/* Lookup an association for an inbound skb. */ 1125static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, 1126 const union sctp_addr *paddr, 1127 const union sctp_addr *laddr, 1128 struct sctp_transport **transportp) 1129{ 1130 struct sctp_association *asoc; 1131 1132 asoc = __sctp_lookup_association(laddr, paddr, transportp); 1133 1134 /* Further lookup for INIT/INIT-ACK packets. 1135 * SCTP Implementors Guide, 2.18 Handling of address 1136 * parameters within the INIT or INIT-ACK. 1137 */ 1138 if (!asoc) 1139 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp); 1140 1141 return asoc; 1142} 1143