input.c revision 2ce955035081112cf1590c961da8d94324142b5e
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 <linux/slab.h> 57#include <net/ip.h> 58#include <net/icmp.h> 59#include <net/snmp.h> 60#include <net/sock.h> 61#include <net/xfrm.h> 62#include <net/sctp/sctp.h> 63#include <net/sctp/sm.h> 64#include <net/sctp/checksum.h> 65#include <net/net_namespace.h> 66 67/* Forward declarations for internal helpers. */ 68static int sctp_rcv_ootb(struct sk_buff *); 69static struct sctp_association *__sctp_rcv_lookup(struct net *net, 70 struct sk_buff *skb, 71 const union sctp_addr *laddr, 72 const union sctp_addr *paddr, 73 struct sctp_transport **transportp); 74static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, 75 const union sctp_addr *laddr); 76static struct sctp_association *__sctp_lookup_association( 77 struct net *net, 78 const union sctp_addr *local, 79 const union sctp_addr *peer, 80 struct sctp_transport **pt); 81 82static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 83 84 85/* Calculate the SCTP checksum of an SCTP packet. */ 86static inline int sctp_rcv_checksum(struct sk_buff *skb) 87{ 88 struct sctphdr *sh = sctp_hdr(skb); 89 __le32 cmp = sh->checksum; 90 struct sk_buff *list; 91 __le32 val; 92 __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); 93 94 skb_walk_frags(skb, list) 95 tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), 96 tmp); 97 98 val = sctp_end_cksum(tmp); 99 100 if (val != cmp) { 101 /* CRC failure, dump it. */ 102 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); 103 return -1; 104 } 105 return 0; 106} 107 108struct sctp_input_cb { 109 union { 110 struct inet_skb_parm h4; 111#if IS_ENABLED(CONFIG_IPV6) 112 struct inet6_skb_parm h6; 113#endif 114 } header; 115 struct sctp_chunk *chunk; 116}; 117#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 118 119/* 120 * This is the routine which IP calls when receiving an SCTP packet. 121 */ 122int sctp_rcv(struct sk_buff *skb) 123{ 124 struct sock *sk; 125 struct sctp_association *asoc; 126 struct sctp_endpoint *ep = NULL; 127 struct sctp_ep_common *rcvr; 128 struct sctp_transport *transport = NULL; 129 struct sctp_chunk *chunk; 130 struct sctphdr *sh; 131 union sctp_addr src; 132 union sctp_addr dest; 133 int family; 134 struct sctp_af *af; 135 struct net *net = dev_net(skb->dev); 136 137 if (skb->pkt_type!=PACKET_HOST) 138 goto discard_it; 139 140 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); 141 142 if (skb_linearize(skb)) 143 goto discard_it; 144 145 sh = sctp_hdr(skb); 146 147 /* Pull up the IP and SCTP headers. */ 148 __skb_pull(skb, skb_transport_offset(skb)); 149 if (skb->len < sizeof(struct sctphdr)) 150 goto discard_it; 151 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) && 152 sctp_rcv_checksum(skb) < 0) 153 goto discard_it; 154 155 skb_pull(skb, sizeof(struct sctphdr)); 156 157 /* Make sure we at least have chunk headers worth of data left. */ 158 if (skb->len < sizeof(struct sctp_chunkhdr)) 159 goto discard_it; 160 161 family = ipver2af(ip_hdr(skb)->version); 162 af = sctp_get_af_specific(family); 163 if (unlikely(!af)) 164 goto discard_it; 165 166 /* Initialize local addresses for lookups. */ 167 af->from_skb(&src, skb, 1); 168 af->from_skb(&dest, skb, 0); 169 170 /* If the packet is to or from a non-unicast address, 171 * silently discard the packet. 172 * 173 * This is not clearly defined in the RFC except in section 174 * 8.4 - OOTB handling. However, based on the book "Stream Control 175 * Transmission Protocol" 2.1, "It is important to note that the 176 * IP address of an SCTP transport address must be a routable 177 * unicast address. In other words, IP multicast addresses and 178 * IP broadcast addresses cannot be used in an SCTP transport 179 * address." 180 */ 181 if (!af->addr_valid(&src, NULL, skb) || 182 !af->addr_valid(&dest, NULL, skb)) 183 goto discard_it; 184 185 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport); 186 187 if (!asoc) 188 ep = __sctp_rcv_lookup_endpoint(net, &dest); 189 190 /* Retrieve the common input handling substructure. */ 191 rcvr = asoc ? &asoc->base : &ep->base; 192 sk = rcvr->sk; 193 194 /* 195 * If a frame arrives on an interface and the receiving socket is 196 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 197 */ 198 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) 199 { 200 if (asoc) { 201 sctp_association_put(asoc); 202 asoc = NULL; 203 } else { 204 sctp_endpoint_put(ep); 205 ep = NULL; 206 } 207 sk = net->sctp.ctl_sock; 208 ep = sctp_sk(sk)->ep; 209 sctp_endpoint_hold(ep); 210 rcvr = &ep->base; 211 } 212 213 /* 214 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 215 * An SCTP packet is called an "out of the blue" (OOTB) 216 * packet if it is correctly formed, i.e., passed the 217 * receiver's checksum check, but the receiver is not 218 * able to identify the association to which this 219 * packet belongs. 220 */ 221 if (!asoc) { 222 if (sctp_rcv_ootb(skb)) { 223 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); 224 goto discard_release; 225 } 226 } 227 228 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 229 goto discard_release; 230 nf_reset(skb); 231 232 if (sk_filter(sk, skb)) 233 goto discard_release; 234 235 /* Create an SCTP packet structure. */ 236 chunk = sctp_chunkify(skb, asoc, sk); 237 if (!chunk) 238 goto discard_release; 239 SCTP_INPUT_CB(skb)->chunk = chunk; 240 241 /* Remember what endpoint is to handle this packet. */ 242 chunk->rcvr = rcvr; 243 244 /* Remember the SCTP header. */ 245 chunk->sctp_hdr = sh; 246 247 /* Set the source and destination addresses of the incoming chunk. */ 248 sctp_init_addrs(chunk, &src, &dest); 249 250 /* Remember where we came from. */ 251 chunk->transport = transport; 252 253 /* Acquire access to the sock lock. Note: We are safe from other 254 * bottom halves on this lock, but a user may be in the lock too, 255 * so check if it is busy. 256 */ 257 sctp_bh_lock_sock(sk); 258 259 if (sk != rcvr->sk) { 260 /* Our cached sk is different from the rcvr->sk. This is 261 * because migrate()/accept() may have moved the association 262 * to a new socket and released all the sockets. So now we 263 * are holding a lock on the old socket while the user may 264 * be doing something with the new socket. Switch our veiw 265 * of the current sk. 266 */ 267 sctp_bh_unlock_sock(sk); 268 sk = rcvr->sk; 269 sctp_bh_lock_sock(sk); 270 } 271 272 if (sock_owned_by_user(sk)) { 273 if (sctp_add_backlog(sk, skb)) { 274 sctp_bh_unlock_sock(sk); 275 sctp_chunk_free(chunk); 276 skb = NULL; /* sctp_chunk_free already freed the skb */ 277 goto discard_release; 278 } 279 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG); 280 } else { 281 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ); 282 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 283 } 284 285 sctp_bh_unlock_sock(sk); 286 287 /* Release the asoc/ep ref we took in the lookup calls. */ 288 if (asoc) 289 sctp_association_put(asoc); 290 else 291 sctp_endpoint_put(ep); 292 293 return 0; 294 295discard_it: 296 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS); 297 kfree_skb(skb); 298 return 0; 299 300discard_release: 301 /* Release the asoc/ep ref we took in the lookup calls. */ 302 if (asoc) 303 sctp_association_put(asoc); 304 else 305 sctp_endpoint_put(ep); 306 307 goto discard_it; 308} 309 310/* Process the backlog queue of the socket. Every skb on 311 * the backlog holds a ref on an association or endpoint. 312 * We hold this ref throughout the state machine to make 313 * sure that the structure we need is still around. 314 */ 315int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 316{ 317 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 318 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 319 struct sctp_ep_common *rcvr = NULL; 320 int backloged = 0; 321 322 rcvr = chunk->rcvr; 323 324 /* If the rcvr is dead then the association or endpoint 325 * has been deleted and we can safely drop the chunk 326 * and refs that we are holding. 327 */ 328 if (rcvr->dead) { 329 sctp_chunk_free(chunk); 330 goto done; 331 } 332 333 if (unlikely(rcvr->sk != sk)) { 334 /* In this case, the association moved from one socket to 335 * another. We are currently sitting on the backlog of the 336 * old socket, so we need to move. 337 * However, since we are here in the process context we 338 * need to take make sure that the user doesn't own 339 * the new socket when we process the packet. 340 * If the new socket is user-owned, queue the chunk to the 341 * backlog of the new socket without dropping any refs. 342 * Otherwise, we can safely push the chunk on the inqueue. 343 */ 344 345 sk = rcvr->sk; 346 sctp_bh_lock_sock(sk); 347 348 if (sock_owned_by_user(sk)) { 349 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) 350 sctp_chunk_free(chunk); 351 else 352 backloged = 1; 353 } else 354 sctp_inq_push(inqueue, chunk); 355 356 sctp_bh_unlock_sock(sk); 357 358 /* If the chunk was backloged again, don't drop refs */ 359 if (backloged) 360 return 0; 361 } else { 362 sctp_inq_push(inqueue, chunk); 363 } 364 365done: 366 /* Release the refs we took in sctp_add_backlog */ 367 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 368 sctp_association_put(sctp_assoc(rcvr)); 369 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 370 sctp_endpoint_put(sctp_ep(rcvr)); 371 else 372 BUG(); 373 374 return 0; 375} 376 377static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 378{ 379 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 380 struct sctp_ep_common *rcvr = chunk->rcvr; 381 int ret; 382 383 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); 384 if (!ret) { 385 /* Hold the assoc/ep while hanging on the backlog queue. 386 * This way, we know structures we need will not disappear 387 * from us 388 */ 389 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 390 sctp_association_hold(sctp_assoc(rcvr)); 391 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 392 sctp_endpoint_hold(sctp_ep(rcvr)); 393 else 394 BUG(); 395 } 396 return ret; 397 398} 399 400/* Handle icmp frag needed error. */ 401void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 402 struct sctp_transport *t, __u32 pmtu) 403{ 404 if (!t || (t->pathmtu <= pmtu)) 405 return; 406 407 if (sock_owned_by_user(sk)) { 408 asoc->pmtu_pending = 1; 409 t->pmtu_pending = 1; 410 return; 411 } 412 413 if (t->param_flags & SPP_PMTUD_ENABLE) { 414 /* Update transports view of the MTU */ 415 sctp_transport_update_pmtu(sk, t, pmtu); 416 417 /* Update association pmtu. */ 418 sctp_assoc_sync_pmtu(sk, asoc); 419 } 420 421 /* Retransmit with the new pmtu setting. 422 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 423 * Needed will never be sent, but if a message was sent before 424 * PMTU discovery was disabled that was larger than the PMTU, it 425 * would not be fragmented, so it must be re-transmitted fragmented. 426 */ 427 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 428} 429 430void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, 431 struct sk_buff *skb) 432{ 433 struct dst_entry *dst; 434 435 if (!t) 436 return; 437 dst = sctp_transport_dst_check(t); 438 if (dst) 439 dst->ops->redirect(dst, sk, skb); 440} 441 442/* 443 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 444 * 445 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 446 * or a "Protocol Unreachable" treat this message as an abort 447 * with the T bit set. 448 * 449 * This function sends an event to the state machine, which will abort the 450 * association. 451 * 452 */ 453void sctp_icmp_proto_unreachable(struct sock *sk, 454 struct sctp_association *asoc, 455 struct sctp_transport *t) 456{ 457 SCTP_DEBUG_PRINTK("%s\n", __func__); 458 459 if (sock_owned_by_user(sk)) { 460 if (timer_pending(&t->proto_unreach_timer)) 461 return; 462 else { 463 if (!mod_timer(&t->proto_unreach_timer, 464 jiffies + (HZ/20))) 465 sctp_association_hold(asoc); 466 } 467 468 } else { 469 if (timer_pending(&t->proto_unreach_timer) && 470 del_timer(&t->proto_unreach_timer)) 471 sctp_association_put(asoc); 472 473 sctp_do_sm(SCTP_EVENT_T_OTHER, 474 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 475 asoc->state, asoc->ep, asoc, t, 476 GFP_ATOMIC); 477 } 478} 479 480/* Common lookup code for icmp/icmpv6 error handler. */ 481struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, 482 struct sctphdr *sctphdr, 483 struct sctp_association **app, 484 struct sctp_transport **tpp) 485{ 486 union sctp_addr saddr; 487 union sctp_addr daddr; 488 struct sctp_af *af; 489 struct sock *sk = NULL; 490 struct sctp_association *asoc; 491 struct sctp_transport *transport = NULL; 492 struct sctp_init_chunk *chunkhdr; 493 __u32 vtag = ntohl(sctphdr->vtag); 494 int len = skb->len - ((void *)sctphdr - (void *)skb->data); 495 496 *app = NULL; *tpp = NULL; 497 498 af = sctp_get_af_specific(family); 499 if (unlikely(!af)) { 500 return NULL; 501 } 502 503 /* Initialize local addresses for lookups. */ 504 af->from_skb(&saddr, skb, 1); 505 af->from_skb(&daddr, skb, 0); 506 507 /* Look for an association that matches the incoming ICMP error 508 * packet. 509 */ 510 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport); 511 if (!asoc) 512 return NULL; 513 514 sk = asoc->base.sk; 515 516 /* RFC 4960, Appendix C. ICMP Handling 517 * 518 * ICMP6) An implementation MUST validate that the Verification Tag 519 * contained in the ICMP message matches the Verification Tag of 520 * the peer. If the Verification Tag is not 0 and does NOT 521 * match, discard the ICMP message. If it is 0 and the ICMP 522 * message contains enough bytes to verify that the chunk type is 523 * an INIT chunk and that the Initiate Tag matches the tag of the 524 * peer, continue with ICMP7. If the ICMP message is too short 525 * or the chunk type or the Initiate Tag does not match, silently 526 * discard the packet. 527 */ 528 if (vtag == 0) { 529 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr); 530 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) 531 + sizeof(__be32) || 532 chunkhdr->chunk_hdr.type != SCTP_CID_INIT || 533 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { 534 goto out; 535 } 536 } else if (vtag != asoc->c.peer_vtag) { 537 goto out; 538 } 539 540 sctp_bh_lock_sock(sk); 541 542 /* If too many ICMPs get dropped on busy 543 * servers this needs to be solved differently. 544 */ 545 if (sock_owned_by_user(sk)) 546 NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS); 547 548 *app = asoc; 549 *tpp = transport; 550 return sk; 551 552out: 553 if (asoc) 554 sctp_association_put(asoc); 555 return NULL; 556} 557 558/* Common cleanup code for icmp/icmpv6 error handler. */ 559void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 560{ 561 sctp_bh_unlock_sock(sk); 562 if (asoc) 563 sctp_association_put(asoc); 564} 565 566/* 567 * This routine is called by the ICMP module when it gets some 568 * sort of error condition. If err < 0 then the socket should 569 * be closed and the error returned to the user. If err > 0 570 * it's just the icmp type << 8 | icmp code. After adjustment 571 * header points to the first 8 bytes of the sctp header. We need 572 * to find the appropriate port. 573 * 574 * The locking strategy used here is very "optimistic". When 575 * someone else accesses the socket the ICMP is just dropped 576 * and for some paths there is no check at all. 577 * A more general error queue to queue errors for later handling 578 * is probably better. 579 * 580 */ 581void sctp_v4_err(struct sk_buff *skb, __u32 info) 582{ 583 const struct iphdr *iph = (const struct iphdr *)skb->data; 584 const int ihlen = iph->ihl * 4; 585 const int type = icmp_hdr(skb)->type; 586 const int code = icmp_hdr(skb)->code; 587 struct sock *sk; 588 struct sctp_association *asoc = NULL; 589 struct sctp_transport *transport; 590 struct inet_sock *inet; 591 sk_buff_data_t saveip, savesctp; 592 int err; 593 struct net *net = dev_net(skb->dev); 594 595 if (skb->len < ihlen + 8) { 596 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); 597 return; 598 } 599 600 /* Fix up skb to look at the embedded net header. */ 601 saveip = skb->network_header; 602 savesctp = skb->transport_header; 603 skb_reset_network_header(skb); 604 skb_set_transport_header(skb, ihlen); 605 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 606 /* Put back, the original values. */ 607 skb->network_header = saveip; 608 skb->transport_header = savesctp; 609 if (!sk) { 610 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); 611 return; 612 } 613 /* Warning: The sock lock is held. Remember to call 614 * sctp_err_finish! 615 */ 616 617 switch (type) { 618 case ICMP_PARAMETERPROB: 619 err = EPROTO; 620 break; 621 case ICMP_DEST_UNREACH: 622 if (code > NR_ICMP_UNREACH) 623 goto out_unlock; 624 625 /* PMTU discovery (RFC1191) */ 626 if (ICMP_FRAG_NEEDED == code) { 627 sctp_icmp_frag_needed(sk, asoc, transport, info); 628 goto out_unlock; 629 } 630 else { 631 if (ICMP_PROT_UNREACH == code) { 632 sctp_icmp_proto_unreachable(sk, asoc, 633 transport); 634 goto out_unlock; 635 } 636 } 637 err = icmp_err_convert[code].errno; 638 break; 639 case ICMP_TIME_EXCEEDED: 640 /* Ignore any time exceeded errors due to fragment reassembly 641 * timeouts. 642 */ 643 if (ICMP_EXC_FRAGTIME == code) 644 goto out_unlock; 645 646 err = EHOSTUNREACH; 647 break; 648 case ICMP_REDIRECT: 649 sctp_icmp_redirect(sk, transport, skb); 650 err = 0; 651 break; 652 default: 653 goto out_unlock; 654 } 655 656 inet = inet_sk(sk); 657 if (!sock_owned_by_user(sk) && inet->recverr) { 658 sk->sk_err = err; 659 sk->sk_error_report(sk); 660 } else { /* Only an error on timeout */ 661 sk->sk_err_soft = err; 662 } 663 664out_unlock: 665 sctp_err_finish(sk, asoc); 666} 667 668/* 669 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 670 * 671 * This function scans all the chunks in the OOTB packet to determine if 672 * the packet should be discarded right away. If a response might be needed 673 * for this packet, or, if further processing is possible, the packet will 674 * be queued to a proper inqueue for the next phase of handling. 675 * 676 * Output: 677 * Return 0 - If further processing is needed. 678 * Return 1 - If the packet can be discarded right away. 679 */ 680static int sctp_rcv_ootb(struct sk_buff *skb) 681{ 682 sctp_chunkhdr_t *ch; 683 __u8 *ch_end; 684 685 ch = (sctp_chunkhdr_t *) skb->data; 686 687 /* Scan through all the chunks in the packet. */ 688 do { 689 /* Break out if chunk length is less then minimal. */ 690 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 691 break; 692 693 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 694 if (ch_end > skb_tail_pointer(skb)) 695 break; 696 697 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 698 * receiver MUST silently discard the OOTB packet and take no 699 * further action. 700 */ 701 if (SCTP_CID_ABORT == ch->type) 702 goto discard; 703 704 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 705 * chunk, the receiver should silently discard the packet 706 * and take no further action. 707 */ 708 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 709 goto discard; 710 711 /* RFC 4460, 2.11.2 712 * This will discard packets with INIT chunk bundled as 713 * subsequent chunks in the packet. When INIT is first, 714 * the normal INIT processing will discard the chunk. 715 */ 716 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 717 goto discard; 718 719 ch = (sctp_chunkhdr_t *) ch_end; 720 } while (ch_end < skb_tail_pointer(skb)); 721 722 return 0; 723 724discard: 725 return 1; 726} 727 728/* Insert endpoint into the hash table. */ 729static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 730{ 731 struct net *net = sock_net(ep->base.sk); 732 struct sctp_ep_common *epb; 733 struct sctp_hashbucket *head; 734 735 epb = &ep->base; 736 737 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 738 head = &sctp_ep_hashtable[epb->hashent]; 739 740 sctp_write_lock(&head->lock); 741 hlist_add_head(&epb->node, &head->chain); 742 sctp_write_unlock(&head->lock); 743} 744 745/* Add an endpoint to the hash. Local BH-safe. */ 746void sctp_hash_endpoint(struct sctp_endpoint *ep) 747{ 748 sctp_local_bh_disable(); 749 __sctp_hash_endpoint(ep); 750 sctp_local_bh_enable(); 751} 752 753/* Remove endpoint from the hash table. */ 754static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 755{ 756 struct net *net = sock_net(ep->base.sk); 757 struct sctp_hashbucket *head; 758 struct sctp_ep_common *epb; 759 760 epb = &ep->base; 761 762 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 763 764 head = &sctp_ep_hashtable[epb->hashent]; 765 766 sctp_write_lock(&head->lock); 767 hlist_del_init(&epb->node); 768 sctp_write_unlock(&head->lock); 769} 770 771/* Remove endpoint from the hash. Local BH-safe. */ 772void sctp_unhash_endpoint(struct sctp_endpoint *ep) 773{ 774 sctp_local_bh_disable(); 775 __sctp_unhash_endpoint(ep); 776 sctp_local_bh_enable(); 777} 778 779/* Look up an endpoint. */ 780static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, 781 const union sctp_addr *laddr) 782{ 783 struct sctp_hashbucket *head; 784 struct sctp_ep_common *epb; 785 struct sctp_endpoint *ep; 786 struct hlist_node *node; 787 int hash; 788 789 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port)); 790 head = &sctp_ep_hashtable[hash]; 791 read_lock(&head->lock); 792 sctp_for_each_hentry(epb, node, &head->chain) { 793 ep = sctp_ep(epb); 794 if (sctp_endpoint_is_match(ep, net, laddr)) 795 goto hit; 796 } 797 798 ep = sctp_sk(net->sctp.ctl_sock)->ep; 799 800hit: 801 sctp_endpoint_hold(ep); 802 read_unlock(&head->lock); 803 return ep; 804} 805 806/* Insert association into the hash table. */ 807static void __sctp_hash_established(struct sctp_association *asoc) 808{ 809 struct net *net = sock_net(asoc->base.sk); 810 struct sctp_ep_common *epb; 811 struct sctp_hashbucket *head; 812 813 epb = &asoc->base; 814 815 /* Calculate which chain this entry will belong to. */ 816 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port, 817 asoc->peer.port); 818 819 head = &sctp_assoc_hashtable[epb->hashent]; 820 821 sctp_write_lock(&head->lock); 822 hlist_add_head(&epb->node, &head->chain); 823 sctp_write_unlock(&head->lock); 824} 825 826/* Add an association to the hash. Local BH-safe. */ 827void sctp_hash_established(struct sctp_association *asoc) 828{ 829 if (asoc->temp) 830 return; 831 832 sctp_local_bh_disable(); 833 __sctp_hash_established(asoc); 834 sctp_local_bh_enable(); 835} 836 837/* Remove association from the hash table. */ 838static void __sctp_unhash_established(struct sctp_association *asoc) 839{ 840 struct net *net = sock_net(asoc->base.sk); 841 struct sctp_hashbucket *head; 842 struct sctp_ep_common *epb; 843 844 epb = &asoc->base; 845 846 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port, 847 asoc->peer.port); 848 849 head = &sctp_assoc_hashtable[epb->hashent]; 850 851 sctp_write_lock(&head->lock); 852 hlist_del_init(&epb->node); 853 sctp_write_unlock(&head->lock); 854} 855 856/* Remove association from the hash table. Local BH-safe. */ 857void sctp_unhash_established(struct sctp_association *asoc) 858{ 859 if (asoc->temp) 860 return; 861 862 sctp_local_bh_disable(); 863 __sctp_unhash_established(asoc); 864 sctp_local_bh_enable(); 865} 866 867/* Look up an association. */ 868static struct sctp_association *__sctp_lookup_association( 869 struct net *net, 870 const union sctp_addr *local, 871 const union sctp_addr *peer, 872 struct sctp_transport **pt) 873{ 874 struct sctp_hashbucket *head; 875 struct sctp_ep_common *epb; 876 struct sctp_association *asoc; 877 struct sctp_transport *transport; 878 struct hlist_node *node; 879 int hash; 880 881 /* Optimize here for direct hit, only listening connections can 882 * have wildcards anyways. 883 */ 884 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port), 885 ntohs(peer->v4.sin_port)); 886 head = &sctp_assoc_hashtable[hash]; 887 read_lock(&head->lock); 888 sctp_for_each_hentry(epb, node, &head->chain) { 889 asoc = sctp_assoc(epb); 890 transport = sctp_assoc_is_match(asoc, net, local, peer); 891 if (transport) 892 goto hit; 893 } 894 895 read_unlock(&head->lock); 896 897 return NULL; 898 899hit: 900 *pt = transport; 901 sctp_association_hold(asoc); 902 read_unlock(&head->lock); 903 return asoc; 904} 905 906/* Look up an association. BH-safe. */ 907SCTP_STATIC 908struct sctp_association *sctp_lookup_association(struct net *net, 909 const union sctp_addr *laddr, 910 const union sctp_addr *paddr, 911 struct sctp_transport **transportp) 912{ 913 struct sctp_association *asoc; 914 915 sctp_local_bh_disable(); 916 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 917 sctp_local_bh_enable(); 918 919 return asoc; 920} 921 922/* Is there an association matching the given local and peer addresses? */ 923int sctp_has_association(struct net *net, 924 const union sctp_addr *laddr, 925 const union sctp_addr *paddr) 926{ 927 struct sctp_association *asoc; 928 struct sctp_transport *transport; 929 930 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { 931 sctp_association_put(asoc); 932 return 1; 933 } 934 935 return 0; 936} 937 938/* 939 * SCTP Implementors Guide, 2.18 Handling of address 940 * parameters within the INIT or INIT-ACK. 941 * 942 * D) When searching for a matching TCB upon reception of an INIT 943 * or INIT-ACK chunk the receiver SHOULD use not only the 944 * source address of the packet (containing the INIT or 945 * INIT-ACK) but the receiver SHOULD also use all valid 946 * address parameters contained within the chunk. 947 * 948 * 2.18.3 Solution description 949 * 950 * This new text clearly specifies to an implementor the need 951 * to look within the INIT or INIT-ACK. Any implementation that 952 * does not do this, may not be able to establish associations 953 * in certain circumstances. 954 * 955 */ 956static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, 957 struct sk_buff *skb, 958 const union sctp_addr *laddr, struct sctp_transport **transportp) 959{ 960 struct sctp_association *asoc; 961 union sctp_addr addr; 962 union sctp_addr *paddr = &addr; 963 struct sctphdr *sh = sctp_hdr(skb); 964 union sctp_params params; 965 sctp_init_chunk_t *init; 966 struct sctp_transport *transport; 967 struct sctp_af *af; 968 969 /* 970 * This code will NOT touch anything inside the chunk--it is 971 * strictly READ-ONLY. 972 * 973 * RFC 2960 3 SCTP packet Format 974 * 975 * Multiple chunks can be bundled into one SCTP packet up to 976 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 977 * COMPLETE chunks. These chunks MUST NOT be bundled with any 978 * other chunk in a packet. See Section 6.10 for more details 979 * on chunk bundling. 980 */ 981 982 /* Find the start of the TLVs and the end of the chunk. This is 983 * the region we search for address parameters. 984 */ 985 init = (sctp_init_chunk_t *)skb->data; 986 987 /* Walk the parameters looking for embedded addresses. */ 988 sctp_walk_params(params, init, init_hdr.params) { 989 990 /* Note: Ignoring hostname addresses. */ 991 af = sctp_get_af_specific(param_type2af(params.p->type)); 992 if (!af) 993 continue; 994 995 af->from_addr_param(paddr, params.addr, sh->source, 0); 996 997 asoc = __sctp_lookup_association(net, laddr, paddr, &transport); 998 if (asoc) 999 return asoc; 1000 } 1001 1002 return NULL; 1003} 1004 1005/* ADD-IP, Section 5.2 1006 * When an endpoint receives an ASCONF Chunk from the remote peer 1007 * special procedures may be needed to identify the association the 1008 * ASCONF Chunk is associated with. To properly find the association 1009 * the following procedures SHOULD be followed: 1010 * 1011 * D2) If the association is not found, use the address found in the 1012 * Address Parameter TLV combined with the port number found in the 1013 * SCTP common header. If found proceed to rule D4. 1014 * 1015 * D2-ext) If more than one ASCONF Chunks are packed together, use the 1016 * address found in the ASCONF Address Parameter TLV of each of the 1017 * subsequent ASCONF Chunks. If found, proceed to rule D4. 1018 */ 1019static struct sctp_association *__sctp_rcv_asconf_lookup( 1020 struct net *net, 1021 sctp_chunkhdr_t *ch, 1022 const union sctp_addr *laddr, 1023 __be16 peer_port, 1024 struct sctp_transport **transportp) 1025{ 1026 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; 1027 struct sctp_af *af; 1028 union sctp_addr_param *param; 1029 union sctp_addr paddr; 1030 1031 /* Skip over the ADDIP header and find the Address parameter */ 1032 param = (union sctp_addr_param *)(asconf + 1); 1033 1034 af = sctp_get_af_specific(param_type2af(param->p.type)); 1035 if (unlikely(!af)) 1036 return NULL; 1037 1038 af->from_addr_param(&paddr, param, peer_port, 0); 1039 1040 return __sctp_lookup_association(net, laddr, &paddr, transportp); 1041} 1042 1043 1044/* SCTP-AUTH, Section 6.3: 1045* If the receiver does not find a STCB for a packet containing an AUTH 1046* chunk as the first chunk and not a COOKIE-ECHO chunk as the second 1047* chunk, it MUST use the chunks after the AUTH chunk to look up an existing 1048* association. 1049* 1050* This means that any chunks that can help us identify the association need 1051* to be looked at to find this association. 1052*/ 1053static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, 1054 struct sk_buff *skb, 1055 const union sctp_addr *laddr, 1056 struct sctp_transport **transportp) 1057{ 1058 struct sctp_association *asoc = NULL; 1059 sctp_chunkhdr_t *ch; 1060 int have_auth = 0; 1061 unsigned int chunk_num = 1; 1062 __u8 *ch_end; 1063 1064 /* Walk through the chunks looking for AUTH or ASCONF chunks 1065 * to help us find the association. 1066 */ 1067 ch = (sctp_chunkhdr_t *) skb->data; 1068 do { 1069 /* Break out if chunk length is less then minimal. */ 1070 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 1071 break; 1072 1073 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 1074 if (ch_end > skb_tail_pointer(skb)) 1075 break; 1076 1077 switch(ch->type) { 1078 case SCTP_CID_AUTH: 1079 have_auth = chunk_num; 1080 break; 1081 1082 case SCTP_CID_COOKIE_ECHO: 1083 /* If a packet arrives containing an AUTH chunk as 1084 * a first chunk, a COOKIE-ECHO chunk as the second 1085 * chunk, and possibly more chunks after them, and 1086 * the receiver does not have an STCB for that 1087 * packet, then authentication is based on 1088 * the contents of the COOKIE- ECHO chunk. 1089 */ 1090 if (have_auth == 1 && chunk_num == 2) 1091 return NULL; 1092 break; 1093 1094 case SCTP_CID_ASCONF: 1095 if (have_auth || sctp_addip_noauth) 1096 asoc = __sctp_rcv_asconf_lookup( 1097 net, ch, laddr, 1098 sctp_hdr(skb)->source, 1099 transportp); 1100 default: 1101 break; 1102 } 1103 1104 if (asoc) 1105 break; 1106 1107 ch = (sctp_chunkhdr_t *) ch_end; 1108 chunk_num++; 1109 } while (ch_end < skb_tail_pointer(skb)); 1110 1111 return asoc; 1112} 1113 1114/* 1115 * There are circumstances when we need to look inside the SCTP packet 1116 * for information to help us find the association. Examples 1117 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1118 * chunks. 1119 */ 1120static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, 1121 struct sk_buff *skb, 1122 const union sctp_addr *laddr, 1123 struct sctp_transport **transportp) 1124{ 1125 sctp_chunkhdr_t *ch; 1126 1127 ch = (sctp_chunkhdr_t *) skb->data; 1128 1129 /* The code below will attempt to walk the chunk and extract 1130 * parameter information. Before we do that, we need to verify 1131 * that the chunk length doesn't cause overflow. Otherwise, we'll 1132 * walk off the end. 1133 */ 1134 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 1135 return NULL; 1136 1137 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1138 switch (ch->type) { 1139 case SCTP_CID_INIT: 1140 case SCTP_CID_INIT_ACK: 1141 return __sctp_rcv_init_lookup(net, skb, laddr, transportp); 1142 break; 1143 1144 default: 1145 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); 1146 break; 1147 } 1148 1149 1150 return NULL; 1151} 1152 1153/* Lookup an association for an inbound skb. */ 1154static struct sctp_association *__sctp_rcv_lookup(struct net *net, 1155 struct sk_buff *skb, 1156 const union sctp_addr *paddr, 1157 const union sctp_addr *laddr, 1158 struct sctp_transport **transportp) 1159{ 1160 struct sctp_association *asoc; 1161 1162 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 1163 1164 /* Further lookup for INIT/INIT-ACK packets. 1165 * SCTP Implementors Guide, 2.18 Handling of address 1166 * parameters within the INIT or INIT-ACK. 1167 */ 1168 if (!asoc) 1169 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); 1170 1171 return asoc; 1172} 1173