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, see 27 * <http://www.gnu.org/licenses/>. 28 * 29 * Please send any bug reports or fixes you make to the 30 * email address(es): 31 * lksctp developers <linux-sctp@vger.kernel.org> 32 * 33 * Written or modified by: 34 * La Monte H.P. Yarroll <piggy@acm.org> 35 * Karl Knutson <karl@athena.chicago.il.us> 36 * Xingang Guo <xingang.guo@intel.com> 37 * Jon Grimm <jgrimm@us.ibm.com> 38 * Hui Huang <hui.huang@nokia.com> 39 * Daisy Chang <daisyc@us.ibm.com> 40 * Sridhar Samudrala <sri@us.ibm.com> 41 * Ardelle Fan <ardelle.fan@intel.com> 42 */ 43 44 #include <linux/types.h> 45 #include <linux/list.h> /* For struct list_head */ 46 #include <linux/socket.h> 47 #include <linux/ip.h> 48 #include <linux/time.h> /* For struct timeval */ 49 #include <linux/slab.h> 50 #include <net/ip.h> 51 #include <net/icmp.h> 52 #include <net/snmp.h> 53 #include <net/sock.h> 54 #include <net/xfrm.h> 55 #include <net/sctp/sctp.h> 56 #include <net/sctp/sm.h> 57 #include <net/sctp/checksum.h> 58 #include <net/net_namespace.h> 59 60 /* Forward declarations for internal helpers. */ 61 static int sctp_rcv_ootb(struct sk_buff *); 62 static struct sctp_association *__sctp_rcv_lookup(struct net *net, 63 struct sk_buff *skb, 64 const union sctp_addr *paddr, 65 const union sctp_addr *laddr, 66 struct sctp_transport **transportp); 67 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, 68 const union sctp_addr *laddr); 69 static struct sctp_association *__sctp_lookup_association( 70 struct net *net, 71 const union sctp_addr *local, 72 const union sctp_addr *peer, 73 struct sctp_transport **pt); 74 75 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 76 77 78 /* Calculate the SCTP checksum of an SCTP packet. */ 79 static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb) 80 { 81 struct sctphdr *sh = sctp_hdr(skb); 82 __le32 cmp = sh->checksum; 83 __le32 val = sctp_compute_cksum(skb, 0); 84 85 if (val != cmp) { 86 /* CRC failure, dump it. */ 87 SCTP_INC_STATS_BH(net, SCTP_MIB_CHECKSUMERRORS); 88 return -1; 89 } 90 return 0; 91 } 92 93 struct sctp_input_cb { 94 union { 95 struct inet_skb_parm h4; 96 #if IS_ENABLED(CONFIG_IPV6) 97 struct inet6_skb_parm h6; 98 #endif 99 } header; 100 struct sctp_chunk *chunk; 101 }; 102 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) 103 104 /* 105 * This is the routine which IP calls when receiving an SCTP packet. 106 */ 107 int sctp_rcv(struct sk_buff *skb) 108 { 109 struct sock *sk; 110 struct sctp_association *asoc; 111 struct sctp_endpoint *ep = NULL; 112 struct sctp_ep_common *rcvr; 113 struct sctp_transport *transport = NULL; 114 struct sctp_chunk *chunk; 115 struct sctphdr *sh; 116 union sctp_addr src; 117 union sctp_addr dest; 118 int family; 119 struct sctp_af *af; 120 struct net *net = dev_net(skb->dev); 121 122 if (skb->pkt_type != PACKET_HOST) 123 goto discard_it; 124 125 SCTP_INC_STATS_BH(net, SCTP_MIB_INSCTPPACKS); 126 127 if (skb_linearize(skb)) 128 goto discard_it; 129 130 sh = sctp_hdr(skb); 131 132 /* Pull up the IP and SCTP headers. */ 133 __skb_pull(skb, skb_transport_offset(skb)); 134 if (skb->len < sizeof(struct sctphdr)) 135 goto discard_it; 136 137 skb->csum_valid = 0; /* Previous value not applicable */ 138 if (skb_csum_unnecessary(skb)) 139 __skb_decr_checksum_unnecessary(skb); 140 else if (!sctp_checksum_disable && sctp_rcv_checksum(net, skb) < 0) 141 goto discard_it; 142 skb->csum_valid = 1; 143 144 skb_pull(skb, sizeof(struct sctphdr)); 145 146 /* Make sure we at least have chunk headers worth of data left. */ 147 if (skb->len < sizeof(struct sctp_chunkhdr)) 148 goto discard_it; 149 150 family = ipver2af(ip_hdr(skb)->version); 151 af = sctp_get_af_specific(family); 152 if (unlikely(!af)) 153 goto discard_it; 154 155 /* Initialize local addresses for lookups. */ 156 af->from_skb(&src, skb, 1); 157 af->from_skb(&dest, skb, 0); 158 159 /* If the packet is to or from a non-unicast address, 160 * silently discard the packet. 161 * 162 * This is not clearly defined in the RFC except in section 163 * 8.4 - OOTB handling. However, based on the book "Stream Control 164 * Transmission Protocol" 2.1, "It is important to note that the 165 * IP address of an SCTP transport address must be a routable 166 * unicast address. In other words, IP multicast addresses and 167 * IP broadcast addresses cannot be used in an SCTP transport 168 * address." 169 */ 170 if (!af->addr_valid(&src, NULL, skb) || 171 !af->addr_valid(&dest, NULL, skb)) 172 goto discard_it; 173 174 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport); 175 176 if (!asoc) 177 ep = __sctp_rcv_lookup_endpoint(net, &dest); 178 179 /* Retrieve the common input handling substructure. */ 180 rcvr = asoc ? &asoc->base : &ep->base; 181 sk = rcvr->sk; 182 183 /* 184 * If a frame arrives on an interface and the receiving socket is 185 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 186 */ 187 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) { 188 if (asoc) { 189 sctp_association_put(asoc); 190 asoc = NULL; 191 } else { 192 sctp_endpoint_put(ep); 193 ep = NULL; 194 } 195 sk = net->sctp.ctl_sock; 196 ep = sctp_sk(sk)->ep; 197 sctp_endpoint_hold(ep); 198 rcvr = &ep->base; 199 } 200 201 /* 202 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 203 * An SCTP packet is called an "out of the blue" (OOTB) 204 * packet if it is correctly formed, i.e., passed the 205 * receiver's checksum check, but the receiver is not 206 * able to identify the association to which this 207 * packet belongs. 208 */ 209 if (!asoc) { 210 if (sctp_rcv_ootb(skb)) { 211 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES); 212 goto discard_release; 213 } 214 } 215 216 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 217 goto discard_release; 218 nf_reset(skb); 219 220 if (sk_filter(sk, skb)) 221 goto discard_release; 222 223 /* Create an SCTP packet structure. */ 224 chunk = sctp_chunkify(skb, asoc, sk); 225 if (!chunk) 226 goto discard_release; 227 SCTP_INPUT_CB(skb)->chunk = chunk; 228 229 /* Remember what endpoint is to handle this packet. */ 230 chunk->rcvr = rcvr; 231 232 /* Remember the SCTP header. */ 233 chunk->sctp_hdr = sh; 234 235 /* Set the source and destination addresses of the incoming chunk. */ 236 sctp_init_addrs(chunk, &src, &dest); 237 238 /* Remember where we came from. */ 239 chunk->transport = transport; 240 241 /* Acquire access to the sock lock. Note: We are safe from other 242 * bottom halves on this lock, but a user may be in the lock too, 243 * so check if it is busy. 244 */ 245 bh_lock_sock(sk); 246 247 if (sk != rcvr->sk) { 248 /* Our cached sk is different from the rcvr->sk. This is 249 * because migrate()/accept() may have moved the association 250 * to a new socket and released all the sockets. So now we 251 * are holding a lock on the old socket while the user may 252 * be doing something with the new socket. Switch our veiw 253 * of the current sk. 254 */ 255 bh_unlock_sock(sk); 256 sk = rcvr->sk; 257 bh_lock_sock(sk); 258 } 259 260 if (sock_owned_by_user(sk)) { 261 if (sctp_add_backlog(sk, skb)) { 262 bh_unlock_sock(sk); 263 sctp_chunk_free(chunk); 264 skb = NULL; /* sctp_chunk_free already freed the skb */ 265 goto discard_release; 266 } 267 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG); 268 } else { 269 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ); 270 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 271 } 272 273 bh_unlock_sock(sk); 274 275 /* 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 return 0; 282 283 discard_it: 284 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS); 285 kfree_skb(skb); 286 return 0; 287 288 discard_release: 289 /* Release the asoc/ep ref we took in the lookup calls. */ 290 if (asoc) 291 sctp_association_put(asoc); 292 else 293 sctp_endpoint_put(ep); 294 295 goto discard_it; 296 } 297 298 /* Process the backlog queue of the socket. Every skb on 299 * the backlog holds a ref on an association or endpoint. 300 * We hold this ref throughout the state machine to make 301 * sure that the structure we need is still around. 302 */ 303 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 304 { 305 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 306 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 307 struct sctp_ep_common *rcvr = NULL; 308 int backloged = 0; 309 310 rcvr = chunk->rcvr; 311 312 /* If the rcvr is dead then the association or endpoint 313 * has been deleted and we can safely drop the chunk 314 * and refs that we are holding. 315 */ 316 if (rcvr->dead) { 317 sctp_chunk_free(chunk); 318 goto done; 319 } 320 321 if (unlikely(rcvr->sk != sk)) { 322 /* In this case, the association moved from one socket to 323 * another. We are currently sitting on the backlog of the 324 * old socket, so we need to move. 325 * However, since we are here in the process context we 326 * need to take make sure that the user doesn't own 327 * the new socket when we process the packet. 328 * If the new socket is user-owned, queue the chunk to the 329 * backlog of the new socket without dropping any refs. 330 * Otherwise, we can safely push the chunk on the inqueue. 331 */ 332 333 sk = rcvr->sk; 334 bh_lock_sock(sk); 335 336 if (sock_owned_by_user(sk)) { 337 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) 338 sctp_chunk_free(chunk); 339 else 340 backloged = 1; 341 } else 342 sctp_inq_push(inqueue, chunk); 343 344 bh_unlock_sock(sk); 345 346 /* If the chunk was backloged again, don't drop refs */ 347 if (backloged) 348 return 0; 349 } else { 350 sctp_inq_push(inqueue, chunk); 351 } 352 353 done: 354 /* Release the refs we took in sctp_add_backlog */ 355 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 356 sctp_association_put(sctp_assoc(rcvr)); 357 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 358 sctp_endpoint_put(sctp_ep(rcvr)); 359 else 360 BUG(); 361 362 return 0; 363 } 364 365 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 366 { 367 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 368 struct sctp_ep_common *rcvr = chunk->rcvr; 369 int ret; 370 371 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); 372 if (!ret) { 373 /* Hold the assoc/ep while hanging on the backlog queue. 374 * This way, we know structures we need will not disappear 375 * from us 376 */ 377 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 378 sctp_association_hold(sctp_assoc(rcvr)); 379 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 380 sctp_endpoint_hold(sctp_ep(rcvr)); 381 else 382 BUG(); 383 } 384 return ret; 385 386 } 387 388 /* Handle icmp frag needed error. */ 389 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 390 struct sctp_transport *t, __u32 pmtu) 391 { 392 if (!t || (t->pathmtu <= pmtu)) 393 return; 394 395 if (sock_owned_by_user(sk)) { 396 asoc->pmtu_pending = 1; 397 t->pmtu_pending = 1; 398 return; 399 } 400 401 if (t->param_flags & SPP_PMTUD_ENABLE) { 402 /* Update transports view of the MTU */ 403 sctp_transport_update_pmtu(sk, t, pmtu); 404 405 /* Update association pmtu. */ 406 sctp_assoc_sync_pmtu(sk, asoc); 407 } 408 409 /* Retransmit with the new pmtu setting. 410 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 411 * Needed will never be sent, but if a message was sent before 412 * PMTU discovery was disabled that was larger than the PMTU, it 413 * would not be fragmented, so it must be re-transmitted fragmented. 414 */ 415 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 416 } 417 418 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, 419 struct sk_buff *skb) 420 { 421 struct dst_entry *dst; 422 423 if (!t) 424 return; 425 dst = sctp_transport_dst_check(t); 426 if (dst) 427 dst->ops->redirect(dst, sk, skb); 428 } 429 430 /* 431 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 432 * 433 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 434 * or a "Protocol Unreachable" treat this message as an abort 435 * with the T bit set. 436 * 437 * This function sends an event to the state machine, which will abort the 438 * association. 439 * 440 */ 441 void sctp_icmp_proto_unreachable(struct sock *sk, 442 struct sctp_association *asoc, 443 struct sctp_transport *t) 444 { 445 if (sock_owned_by_user(sk)) { 446 if (timer_pending(&t->proto_unreach_timer)) 447 return; 448 else { 449 if (!mod_timer(&t->proto_unreach_timer, 450 jiffies + (HZ/20))) 451 sctp_association_hold(asoc); 452 } 453 } else { 454 struct net *net = sock_net(sk); 455 456 pr_debug("%s: unrecognized next header type " 457 "encountered!\n", __func__); 458 459 if (del_timer(&t->proto_unreach_timer)) 460 sctp_association_put(asoc); 461 462 sctp_do_sm(net, SCTP_EVENT_T_OTHER, 463 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 464 asoc->state, asoc->ep, asoc, t, 465 GFP_ATOMIC); 466 } 467 } 468 469 /* Common lookup code for icmp/icmpv6 error handler. */ 470 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, 471 struct sctphdr *sctphdr, 472 struct sctp_association **app, 473 struct sctp_transport **tpp) 474 { 475 union sctp_addr saddr; 476 union sctp_addr daddr; 477 struct sctp_af *af; 478 struct sock *sk = NULL; 479 struct sctp_association *asoc; 480 struct sctp_transport *transport = NULL; 481 struct sctp_init_chunk *chunkhdr; 482 __u32 vtag = ntohl(sctphdr->vtag); 483 int len = skb->len - ((void *)sctphdr - (void *)skb->data); 484 485 *app = NULL; *tpp = NULL; 486 487 af = sctp_get_af_specific(family); 488 if (unlikely(!af)) { 489 return NULL; 490 } 491 492 /* Initialize local addresses for lookups. */ 493 af->from_skb(&saddr, skb, 1); 494 af->from_skb(&daddr, skb, 0); 495 496 /* Look for an association that matches the incoming ICMP error 497 * packet. 498 */ 499 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport); 500 if (!asoc) 501 return NULL; 502 503 sk = asoc->base.sk; 504 505 /* RFC 4960, Appendix C. ICMP Handling 506 * 507 * ICMP6) An implementation MUST validate that the Verification Tag 508 * contained in the ICMP message matches the Verification Tag of 509 * the peer. If the Verification Tag is not 0 and does NOT 510 * match, discard the ICMP message. If it is 0 and the ICMP 511 * message contains enough bytes to verify that the chunk type is 512 * an INIT chunk and that the Initiate Tag matches the tag of the 513 * peer, continue with ICMP7. If the ICMP message is too short 514 * or the chunk type or the Initiate Tag does not match, silently 515 * discard the packet. 516 */ 517 if (vtag == 0) { 518 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr); 519 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) 520 + sizeof(__be32) || 521 chunkhdr->chunk_hdr.type != SCTP_CID_INIT || 522 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { 523 goto out; 524 } 525 } else if (vtag != asoc->c.peer_vtag) { 526 goto out; 527 } 528 529 bh_lock_sock(sk); 530 531 /* If too many ICMPs get dropped on busy 532 * servers this needs to be solved differently. 533 */ 534 if (sock_owned_by_user(sk)) 535 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 536 537 *app = asoc; 538 *tpp = transport; 539 return sk; 540 541 out: 542 sctp_association_put(asoc); 543 return NULL; 544 } 545 546 /* Common cleanup code for icmp/icmpv6 error handler. */ 547 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 548 { 549 bh_unlock_sock(sk); 550 sctp_association_put(asoc); 551 } 552 553 /* 554 * This routine is called by the ICMP module when it gets some 555 * sort of error condition. If err < 0 then the socket should 556 * be closed and the error returned to the user. If err > 0 557 * it's just the icmp type << 8 | icmp code. After adjustment 558 * header points to the first 8 bytes of the sctp header. We need 559 * to find the appropriate port. 560 * 561 * The locking strategy used here is very "optimistic". When 562 * someone else accesses the socket the ICMP is just dropped 563 * and for some paths there is no check at all. 564 * A more general error queue to queue errors for later handling 565 * is probably better. 566 * 567 */ 568 void sctp_v4_err(struct sk_buff *skb, __u32 info) 569 { 570 const struct iphdr *iph = (const struct iphdr *)skb->data; 571 const int ihlen = iph->ihl * 4; 572 const int type = icmp_hdr(skb)->type; 573 const int code = icmp_hdr(skb)->code; 574 struct sock *sk; 575 struct sctp_association *asoc = NULL; 576 struct sctp_transport *transport; 577 struct inet_sock *inet; 578 __u16 saveip, savesctp; 579 int err; 580 struct net *net = dev_net(skb->dev); 581 582 /* Fix up skb to look at the embedded net header. */ 583 saveip = skb->network_header; 584 savesctp = skb->transport_header; 585 skb_reset_network_header(skb); 586 skb_set_transport_header(skb, ihlen); 587 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 588 /* Put back, the original values. */ 589 skb->network_header = saveip; 590 skb->transport_header = savesctp; 591 if (!sk) { 592 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 593 return; 594 } 595 /* Warning: The sock lock is held. Remember to call 596 * sctp_err_finish! 597 */ 598 599 switch (type) { 600 case ICMP_PARAMETERPROB: 601 err = EPROTO; 602 break; 603 case ICMP_DEST_UNREACH: 604 if (code > NR_ICMP_UNREACH) 605 goto out_unlock; 606 607 /* PMTU discovery (RFC1191) */ 608 if (ICMP_FRAG_NEEDED == code) { 609 sctp_icmp_frag_needed(sk, asoc, transport, info); 610 goto out_unlock; 611 } else { 612 if (ICMP_PROT_UNREACH == code) { 613 sctp_icmp_proto_unreachable(sk, asoc, 614 transport); 615 goto out_unlock; 616 } 617 } 618 err = icmp_err_convert[code].errno; 619 break; 620 case ICMP_TIME_EXCEEDED: 621 /* Ignore any time exceeded errors due to fragment reassembly 622 * timeouts. 623 */ 624 if (ICMP_EXC_FRAGTIME == code) 625 goto out_unlock; 626 627 err = EHOSTUNREACH; 628 break; 629 case ICMP_REDIRECT: 630 sctp_icmp_redirect(sk, transport, skb); 631 /* Fall through to out_unlock. */ 632 default: 633 goto out_unlock; 634 } 635 636 inet = inet_sk(sk); 637 if (!sock_owned_by_user(sk) && inet->recverr) { 638 sk->sk_err = err; 639 sk->sk_error_report(sk); 640 } else { /* Only an error on timeout */ 641 sk->sk_err_soft = err; 642 } 643 644 out_unlock: 645 sctp_err_finish(sk, asoc); 646 } 647 648 /* 649 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 650 * 651 * This function scans all the chunks in the OOTB packet to determine if 652 * the packet should be discarded right away. If a response might be needed 653 * for this packet, or, if further processing is possible, the packet will 654 * be queued to a proper inqueue for the next phase of handling. 655 * 656 * Output: 657 * Return 0 - If further processing is needed. 658 * Return 1 - If the packet can be discarded right away. 659 */ 660 static int sctp_rcv_ootb(struct sk_buff *skb) 661 { 662 sctp_chunkhdr_t *ch; 663 __u8 *ch_end; 664 665 ch = (sctp_chunkhdr_t *) skb->data; 666 667 /* Scan through all the chunks in the packet. */ 668 do { 669 /* Break out if chunk length is less then minimal. */ 670 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 671 break; 672 673 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 674 if (ch_end > skb_tail_pointer(skb)) 675 break; 676 677 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 678 * receiver MUST silently discard the OOTB packet and take no 679 * further action. 680 */ 681 if (SCTP_CID_ABORT == ch->type) 682 goto discard; 683 684 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 685 * chunk, the receiver should silently discard the packet 686 * and take no further action. 687 */ 688 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 689 goto discard; 690 691 /* RFC 4460, 2.11.2 692 * This will discard packets with INIT chunk bundled as 693 * subsequent chunks in the packet. When INIT is first, 694 * the normal INIT processing will discard the chunk. 695 */ 696 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 697 goto discard; 698 699 ch = (sctp_chunkhdr_t *) ch_end; 700 } while (ch_end < skb_tail_pointer(skb)); 701 702 return 0; 703 704 discard: 705 return 1; 706 } 707 708 /* Insert endpoint into the hash table. */ 709 static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 710 { 711 struct net *net = sock_net(ep->base.sk); 712 struct sctp_ep_common *epb; 713 struct sctp_hashbucket *head; 714 715 epb = &ep->base; 716 717 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 718 head = &sctp_ep_hashtable[epb->hashent]; 719 720 write_lock(&head->lock); 721 hlist_add_head(&epb->node, &head->chain); 722 write_unlock(&head->lock); 723 } 724 725 /* Add an endpoint to the hash. Local BH-safe. */ 726 void sctp_hash_endpoint(struct sctp_endpoint *ep) 727 { 728 local_bh_disable(); 729 __sctp_hash_endpoint(ep); 730 local_bh_enable(); 731 } 732 733 /* Remove endpoint from the hash table. */ 734 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 735 { 736 struct net *net = sock_net(ep->base.sk); 737 struct sctp_hashbucket *head; 738 struct sctp_ep_common *epb; 739 740 epb = &ep->base; 741 742 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 743 744 head = &sctp_ep_hashtable[epb->hashent]; 745 746 write_lock(&head->lock); 747 hlist_del_init(&epb->node); 748 write_unlock(&head->lock); 749 } 750 751 /* Remove endpoint from the hash. Local BH-safe. */ 752 void sctp_unhash_endpoint(struct sctp_endpoint *ep) 753 { 754 local_bh_disable(); 755 __sctp_unhash_endpoint(ep); 756 local_bh_enable(); 757 } 758 759 /* Look up an endpoint. */ 760 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, 761 const union sctp_addr *laddr) 762 { 763 struct sctp_hashbucket *head; 764 struct sctp_ep_common *epb; 765 struct sctp_endpoint *ep; 766 int hash; 767 768 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port)); 769 head = &sctp_ep_hashtable[hash]; 770 read_lock(&head->lock); 771 sctp_for_each_hentry(epb, &head->chain) { 772 ep = sctp_ep(epb); 773 if (sctp_endpoint_is_match(ep, net, laddr)) 774 goto hit; 775 } 776 777 ep = sctp_sk(net->sctp.ctl_sock)->ep; 778 779 hit: 780 sctp_endpoint_hold(ep); 781 read_unlock(&head->lock); 782 return ep; 783 } 784 785 /* rhashtable for transport */ 786 struct sctp_hash_cmp_arg { 787 const union sctp_addr *laddr; 788 const union sctp_addr *paddr; 789 const struct net *net; 790 }; 791 792 static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, 793 const void *ptr) 794 { 795 const struct sctp_hash_cmp_arg *x = arg->key; 796 const struct sctp_transport *t = ptr; 797 struct sctp_association *asoc = t->asoc; 798 const struct net *net = x->net; 799 800 if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port)) 801 return 1; 802 if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) 803 return 1; 804 if (!net_eq(sock_net(asoc->base.sk), net)) 805 return 1; 806 if (!sctp_bind_addr_match(&asoc->base.bind_addr, 807 x->laddr, sctp_sk(asoc->base.sk))) 808 return 1; 809 810 return 0; 811 } 812 813 static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed) 814 { 815 const struct sctp_transport *t = data; 816 const union sctp_addr *paddr = &t->ipaddr; 817 const struct net *net = sock_net(t->asoc->base.sk); 818 u16 lport = htons(t->asoc->base.bind_addr.port); 819 u32 addr; 820 821 if (paddr->sa.sa_family == AF_INET6) 822 addr = jhash(&paddr->v6.sin6_addr, 16, seed); 823 else 824 addr = paddr->v4.sin_addr.s_addr; 825 826 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | 827 (__force __u32)lport, net_hash_mix(net), seed); 828 } 829 830 static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed) 831 { 832 const struct sctp_hash_cmp_arg *x = data; 833 const union sctp_addr *paddr = x->paddr; 834 const struct net *net = x->net; 835 u16 lport = x->laddr->v4.sin_port; 836 u32 addr; 837 838 if (paddr->sa.sa_family == AF_INET6) 839 addr = jhash(&paddr->v6.sin6_addr, 16, seed); 840 else 841 addr = paddr->v4.sin_addr.s_addr; 842 843 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | 844 (__force __u32)lport, net_hash_mix(net), seed); 845 } 846 847 static const struct rhashtable_params sctp_hash_params = { 848 .head_offset = offsetof(struct sctp_transport, node), 849 .hashfn = sctp_hash_key, 850 .obj_hashfn = sctp_hash_obj, 851 .obj_cmpfn = sctp_hash_cmp, 852 .automatic_shrinking = true, 853 }; 854 855 int sctp_transport_hashtable_init(void) 856 { 857 return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params); 858 } 859 860 void sctp_transport_hashtable_destroy(void) 861 { 862 rhashtable_destroy(&sctp_transport_hashtable); 863 } 864 865 void sctp_hash_transport(struct sctp_transport *t) 866 { 867 struct sctp_sockaddr_entry *addr; 868 struct sctp_hash_cmp_arg arg; 869 870 addr = list_entry(t->asoc->base.bind_addr.address_list.next, 871 struct sctp_sockaddr_entry, list); 872 arg.laddr = &addr->a; 873 arg.paddr = &t->ipaddr; 874 arg.net = sock_net(t->asoc->base.sk); 875 876 reinsert: 877 if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg, 878 &t->node, sctp_hash_params) == -EBUSY) 879 goto reinsert; 880 } 881 882 void sctp_unhash_transport(struct sctp_transport *t) 883 { 884 rhashtable_remove_fast(&sctp_transport_hashtable, &t->node, 885 sctp_hash_params); 886 } 887 888 struct sctp_transport *sctp_addrs_lookup_transport( 889 struct net *net, 890 const union sctp_addr *laddr, 891 const union sctp_addr *paddr) 892 { 893 struct sctp_hash_cmp_arg arg = { 894 .laddr = laddr, 895 .paddr = paddr, 896 .net = net, 897 }; 898 899 return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg, 900 sctp_hash_params); 901 } 902 903 struct sctp_transport *sctp_epaddr_lookup_transport( 904 const struct sctp_endpoint *ep, 905 const union sctp_addr *paddr) 906 { 907 struct sctp_sockaddr_entry *addr; 908 struct net *net = sock_net(ep->base.sk); 909 910 addr = list_entry(ep->base.bind_addr.address_list.next, 911 struct sctp_sockaddr_entry, list); 912 913 return sctp_addrs_lookup_transport(net, &addr->a, paddr); 914 } 915 916 /* Look up an association. */ 917 static struct sctp_association *__sctp_lookup_association( 918 struct net *net, 919 const union sctp_addr *local, 920 const union sctp_addr *peer, 921 struct sctp_transport **pt) 922 { 923 struct sctp_transport *t; 924 925 t = sctp_addrs_lookup_transport(net, local, peer); 926 if (!t || t->dead || t->asoc->temp) 927 return NULL; 928 929 sctp_association_hold(t->asoc); 930 *pt = t; 931 932 return t->asoc; 933 } 934 935 /* Look up an association. protected by RCU read lock */ 936 static 937 struct sctp_association *sctp_lookup_association(struct net *net, 938 const union sctp_addr *laddr, 939 const union sctp_addr *paddr, 940 struct sctp_transport **transportp) 941 { 942 struct sctp_association *asoc; 943 944 rcu_read_lock(); 945 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 946 rcu_read_unlock(); 947 948 return asoc; 949 } 950 951 /* Is there an association matching the given local and peer addresses? */ 952 int sctp_has_association(struct net *net, 953 const union sctp_addr *laddr, 954 const union sctp_addr *paddr) 955 { 956 struct sctp_association *asoc; 957 struct sctp_transport *transport; 958 959 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { 960 sctp_association_put(asoc); 961 return 1; 962 } 963 964 return 0; 965 } 966 967 /* 968 * SCTP Implementors Guide, 2.18 Handling of address 969 * parameters within the INIT or INIT-ACK. 970 * 971 * D) When searching for a matching TCB upon reception of an INIT 972 * or INIT-ACK chunk the receiver SHOULD use not only the 973 * source address of the packet (containing the INIT or 974 * INIT-ACK) but the receiver SHOULD also use all valid 975 * address parameters contained within the chunk. 976 * 977 * 2.18.3 Solution description 978 * 979 * This new text clearly specifies to an implementor the need 980 * to look within the INIT or INIT-ACK. Any implementation that 981 * does not do this, may not be able to establish associations 982 * in certain circumstances. 983 * 984 */ 985 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, 986 struct sk_buff *skb, 987 const union sctp_addr *laddr, struct sctp_transport **transportp) 988 { 989 struct sctp_association *asoc; 990 union sctp_addr addr; 991 union sctp_addr *paddr = &addr; 992 struct sctphdr *sh = sctp_hdr(skb); 993 union sctp_params params; 994 sctp_init_chunk_t *init; 995 struct sctp_transport *transport; 996 struct sctp_af *af; 997 998 /* 999 * This code will NOT touch anything inside the chunk--it is 1000 * strictly READ-ONLY. 1001 * 1002 * RFC 2960 3 SCTP packet Format 1003 * 1004 * Multiple chunks can be bundled into one SCTP packet up to 1005 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 1006 * COMPLETE chunks. These chunks MUST NOT be bundled with any 1007 * other chunk in a packet. See Section 6.10 for more details 1008 * on chunk bundling. 1009 */ 1010 1011 /* Find the start of the TLVs and the end of the chunk. This is 1012 * the region we search for address parameters. 1013 */ 1014 init = (sctp_init_chunk_t *)skb->data; 1015 1016 /* Walk the parameters looking for embedded addresses. */ 1017 sctp_walk_params(params, init, init_hdr.params) { 1018 1019 /* Note: Ignoring hostname addresses. */ 1020 af = sctp_get_af_specific(param_type2af(params.p->type)); 1021 if (!af) 1022 continue; 1023 1024 af->from_addr_param(paddr, params.addr, sh->source, 0); 1025 1026 asoc = __sctp_lookup_association(net, laddr, paddr, &transport); 1027 if (asoc) 1028 return asoc; 1029 } 1030 1031 return NULL; 1032 } 1033 1034 /* ADD-IP, Section 5.2 1035 * When an endpoint receives an ASCONF Chunk from the remote peer 1036 * special procedures may be needed to identify the association the 1037 * ASCONF Chunk is associated with. To properly find the association 1038 * the following procedures SHOULD be followed: 1039 * 1040 * D2) If the association is not found, use the address found in the 1041 * Address Parameter TLV combined with the port number found in the 1042 * SCTP common header. If found proceed to rule D4. 1043 * 1044 * D2-ext) If more than one ASCONF Chunks are packed together, use the 1045 * address found in the ASCONF Address Parameter TLV of each of the 1046 * subsequent ASCONF Chunks. If found, proceed to rule D4. 1047 */ 1048 static struct sctp_association *__sctp_rcv_asconf_lookup( 1049 struct net *net, 1050 sctp_chunkhdr_t *ch, 1051 const union sctp_addr *laddr, 1052 __be16 peer_port, 1053 struct sctp_transport **transportp) 1054 { 1055 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; 1056 struct sctp_af *af; 1057 union sctp_addr_param *param; 1058 union sctp_addr paddr; 1059 1060 /* Skip over the ADDIP header and find the Address parameter */ 1061 param = (union sctp_addr_param *)(asconf + 1); 1062 1063 af = sctp_get_af_specific(param_type2af(param->p.type)); 1064 if (unlikely(!af)) 1065 return NULL; 1066 1067 af->from_addr_param(&paddr, param, peer_port, 0); 1068 1069 return __sctp_lookup_association(net, laddr, &paddr, transportp); 1070 } 1071 1072 1073 /* SCTP-AUTH, Section 6.3: 1074 * If the receiver does not find a STCB for a packet containing an AUTH 1075 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second 1076 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing 1077 * association. 1078 * 1079 * This means that any chunks that can help us identify the association need 1080 * to be looked at to find this association. 1081 */ 1082 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, 1083 struct sk_buff *skb, 1084 const union sctp_addr *laddr, 1085 struct sctp_transport **transportp) 1086 { 1087 struct sctp_association *asoc = NULL; 1088 sctp_chunkhdr_t *ch; 1089 int have_auth = 0; 1090 unsigned int chunk_num = 1; 1091 __u8 *ch_end; 1092 1093 /* Walk through the chunks looking for AUTH or ASCONF chunks 1094 * to help us find the association. 1095 */ 1096 ch = (sctp_chunkhdr_t *) skb->data; 1097 do { 1098 /* Break out if chunk length is less then minimal. */ 1099 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 1100 break; 1101 1102 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 1103 if (ch_end > skb_tail_pointer(skb)) 1104 break; 1105 1106 switch (ch->type) { 1107 case SCTP_CID_AUTH: 1108 have_auth = chunk_num; 1109 break; 1110 1111 case SCTP_CID_COOKIE_ECHO: 1112 /* If a packet arrives containing an AUTH chunk as 1113 * a first chunk, a COOKIE-ECHO chunk as the second 1114 * chunk, and possibly more chunks after them, and 1115 * the receiver does not have an STCB for that 1116 * packet, then authentication is based on 1117 * the contents of the COOKIE- ECHO chunk. 1118 */ 1119 if (have_auth == 1 && chunk_num == 2) 1120 return NULL; 1121 break; 1122 1123 case SCTP_CID_ASCONF: 1124 if (have_auth || net->sctp.addip_noauth) 1125 asoc = __sctp_rcv_asconf_lookup( 1126 net, ch, laddr, 1127 sctp_hdr(skb)->source, 1128 transportp); 1129 default: 1130 break; 1131 } 1132 1133 if (asoc) 1134 break; 1135 1136 ch = (sctp_chunkhdr_t *) ch_end; 1137 chunk_num++; 1138 } while (ch_end < skb_tail_pointer(skb)); 1139 1140 return asoc; 1141 } 1142 1143 /* 1144 * There are circumstances when we need to look inside the SCTP packet 1145 * for information to help us find the association. Examples 1146 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1147 * chunks. 1148 */ 1149 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, 1150 struct sk_buff *skb, 1151 const union sctp_addr *laddr, 1152 struct sctp_transport **transportp) 1153 { 1154 sctp_chunkhdr_t *ch; 1155 1156 ch = (sctp_chunkhdr_t *) skb->data; 1157 1158 /* The code below will attempt to walk the chunk and extract 1159 * parameter information. Before we do that, we need to verify 1160 * that the chunk length doesn't cause overflow. Otherwise, we'll 1161 * walk off the end. 1162 */ 1163 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 1164 return NULL; 1165 1166 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1167 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) 1168 return __sctp_rcv_init_lookup(net, skb, laddr, transportp); 1169 1170 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); 1171 } 1172 1173 /* Lookup an association for an inbound skb. */ 1174 static struct sctp_association *__sctp_rcv_lookup(struct net *net, 1175 struct sk_buff *skb, 1176 const union sctp_addr *paddr, 1177 const union sctp_addr *laddr, 1178 struct sctp_transport **transportp) 1179 { 1180 struct sctp_association *asoc; 1181 1182 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 1183 1184 /* Further lookup for INIT/INIT-ACK packets. 1185 * SCTP Implementors Guide, 2.18 Handling of address 1186 * parameters within the INIT or INIT-ACK. 1187 */ 1188 if (!asoc) 1189 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); 1190 1191 return asoc; 1192 } 1193