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(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 union sctp_addr src; 116 union sctp_addr dest; 117 int family; 118 struct sctp_af *af; 119 struct net *net = dev_net(skb->dev); 120 121 if (skb->pkt_type != PACKET_HOST) 122 goto discard_it; 123 124 __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS); 125 126 if (skb_linearize(skb)) 127 goto discard_it; 128 129 /* Pull up the IP and SCTP headers. */ 130 __skb_pull(skb, skb_transport_offset(skb)); 131 if (skb->len < sizeof(struct sctphdr)) 132 goto discard_it; 133 134 skb->csum_valid = 0; /* Previous value not applicable */ 135 if (skb_csum_unnecessary(skb)) 136 __skb_decr_checksum_unnecessary(skb); 137 else if (!sctp_checksum_disable && sctp_rcv_checksum(net, skb) < 0) 138 goto discard_it; 139 skb->csum_valid = 1; 140 141 skb_pull(skb, sizeof(struct sctphdr)); 142 143 /* Make sure we at least have chunk headers worth of data left. */ 144 if (skb->len < sizeof(struct sctp_chunkhdr)) 145 goto discard_it; 146 147 family = ipver2af(ip_hdr(skb)->version); 148 af = sctp_get_af_specific(family); 149 if (unlikely(!af)) 150 goto discard_it; 151 152 /* Initialize local addresses for lookups. */ 153 af->from_skb(&src, skb, 1); 154 af->from_skb(&dest, skb, 0); 155 156 /* If the packet is to or from a non-unicast address, 157 * silently discard the packet. 158 * 159 * This is not clearly defined in the RFC except in section 160 * 8.4 - OOTB handling. However, based on the book "Stream Control 161 * Transmission Protocol" 2.1, "It is important to note that the 162 * IP address of an SCTP transport address must be a routable 163 * unicast address. In other words, IP multicast addresses and 164 * IP broadcast addresses cannot be used in an SCTP transport 165 * address." 166 */ 167 if (!af->addr_valid(&src, NULL, skb) || 168 !af->addr_valid(&dest, NULL, skb)) 169 goto discard_it; 170 171 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport); 172 173 if (!asoc) 174 ep = __sctp_rcv_lookup_endpoint(net, &dest); 175 176 /* Retrieve the common input handling substructure. */ 177 rcvr = asoc ? &asoc->base : &ep->base; 178 sk = rcvr->sk; 179 180 /* 181 * If a frame arrives on an interface and the receiving socket is 182 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB 183 */ 184 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) { 185 if (asoc) { 186 sctp_association_put(asoc); 187 asoc = NULL; 188 } else { 189 sctp_endpoint_put(ep); 190 ep = NULL; 191 } 192 sk = net->sctp.ctl_sock; 193 ep = sctp_sk(sk)->ep; 194 sctp_endpoint_hold(ep); 195 rcvr = &ep->base; 196 } 197 198 /* 199 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 200 * An SCTP packet is called an "out of the blue" (OOTB) 201 * packet if it is correctly formed, i.e., passed the 202 * receiver's checksum check, but the receiver is not 203 * able to identify the association to which this 204 * packet belongs. 205 */ 206 if (!asoc) { 207 if (sctp_rcv_ootb(skb)) { 208 __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); 209 goto discard_release; 210 } 211 } 212 213 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 214 goto discard_release; 215 nf_reset(skb); 216 217 if (sk_filter(sk, skb)) 218 goto discard_release; 219 220 /* Create an SCTP packet structure. */ 221 chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC); 222 if (!chunk) 223 goto discard_release; 224 SCTP_INPUT_CB(skb)->chunk = chunk; 225 226 /* Remember what endpoint is to handle this packet. */ 227 chunk->rcvr = rcvr; 228 229 /* Remember the SCTP header. */ 230 chunk->sctp_hdr = sctp_hdr(skb); 231 232 /* Set the source and destination addresses of the incoming chunk. */ 233 sctp_init_addrs(chunk, &src, &dest); 234 235 /* Remember where we came from. */ 236 chunk->transport = transport; 237 238 /* Acquire access to the sock lock. Note: We are safe from other 239 * bottom halves on this lock, but a user may be in the lock too, 240 * so check if it is busy. 241 */ 242 bh_lock_sock(sk); 243 244 if (sk != rcvr->sk) { 245 /* Our cached sk is different from the rcvr->sk. This is 246 * because migrate()/accept() may have moved the association 247 * to a new socket and released all the sockets. So now we 248 * are holding a lock on the old socket while the user may 249 * be doing something with the new socket. Switch our veiw 250 * of the current sk. 251 */ 252 bh_unlock_sock(sk); 253 sk = rcvr->sk; 254 bh_lock_sock(sk); 255 } 256 257 if (sock_owned_by_user(sk)) { 258 if (sctp_add_backlog(sk, skb)) { 259 bh_unlock_sock(sk); 260 sctp_chunk_free(chunk); 261 skb = NULL; /* sctp_chunk_free already freed the skb */ 262 goto discard_release; 263 } 264 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG); 265 } else { 266 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ); 267 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 268 } 269 270 bh_unlock_sock(sk); 271 272 /* Release the asoc/ep ref we took in the lookup calls. */ 273 if (asoc) 274 sctp_association_put(asoc); 275 else 276 sctp_endpoint_put(ep); 277 278 return 0; 279 280 discard_it: 281 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); 282 kfree_skb(skb); 283 return 0; 284 285 discard_release: 286 /* Release the asoc/ep ref we took in the lookup calls. */ 287 if (asoc) 288 sctp_association_put(asoc); 289 else 290 sctp_endpoint_put(ep); 291 292 goto discard_it; 293 } 294 295 /* Process the backlog queue of the socket. Every skb on 296 * the backlog holds a ref on an association or endpoint. 297 * We hold this ref throughout the state machine to make 298 * sure that the structure we need is still around. 299 */ 300 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 301 { 302 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 303 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 304 struct sctp_ep_common *rcvr = NULL; 305 int backloged = 0; 306 307 rcvr = chunk->rcvr; 308 309 /* If the rcvr is dead then the association or endpoint 310 * has been deleted and we can safely drop the chunk 311 * and refs that we are holding. 312 */ 313 if (rcvr->dead) { 314 sctp_chunk_free(chunk); 315 goto done; 316 } 317 318 if (unlikely(rcvr->sk != sk)) { 319 /* In this case, the association moved from one socket to 320 * another. We are currently sitting on the backlog of the 321 * old socket, so we need to move. 322 * However, since we are here in the process context we 323 * need to take make sure that the user doesn't own 324 * the new socket when we process the packet. 325 * If the new socket is user-owned, queue the chunk to the 326 * backlog of the new socket without dropping any refs. 327 * Otherwise, we can safely push the chunk on the inqueue. 328 */ 329 330 sk = rcvr->sk; 331 bh_lock_sock(sk); 332 333 if (sock_owned_by_user(sk)) { 334 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) 335 sctp_chunk_free(chunk); 336 else 337 backloged = 1; 338 } else 339 sctp_inq_push(inqueue, chunk); 340 341 bh_unlock_sock(sk); 342 343 /* If the chunk was backloged again, don't drop refs */ 344 if (backloged) 345 return 0; 346 } else { 347 sctp_inq_push(inqueue, chunk); 348 } 349 350 done: 351 /* Release the refs we took in sctp_add_backlog */ 352 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 353 sctp_association_put(sctp_assoc(rcvr)); 354 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 355 sctp_endpoint_put(sctp_ep(rcvr)); 356 else 357 BUG(); 358 359 return 0; 360 } 361 362 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 363 { 364 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 365 struct sctp_ep_common *rcvr = chunk->rcvr; 366 int ret; 367 368 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); 369 if (!ret) { 370 /* Hold the assoc/ep while hanging on the backlog queue. 371 * This way, we know structures we need will not disappear 372 * from us 373 */ 374 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 375 sctp_association_hold(sctp_assoc(rcvr)); 376 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 377 sctp_endpoint_hold(sctp_ep(rcvr)); 378 else 379 BUG(); 380 } 381 return ret; 382 383 } 384 385 /* Handle icmp frag needed error. */ 386 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 387 struct sctp_transport *t, __u32 pmtu) 388 { 389 if (!t || (t->pathmtu <= pmtu)) 390 return; 391 392 if (sock_owned_by_user(sk)) { 393 asoc->pmtu_pending = 1; 394 t->pmtu_pending = 1; 395 return; 396 } 397 398 if (t->param_flags & SPP_PMTUD_ENABLE) { 399 /* Update transports view of the MTU */ 400 sctp_transport_update_pmtu(sk, t, pmtu); 401 402 /* Update association pmtu. */ 403 sctp_assoc_sync_pmtu(sk, asoc); 404 } 405 406 /* Retransmit with the new pmtu setting. 407 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation 408 * Needed will never be sent, but if a message was sent before 409 * PMTU discovery was disabled that was larger than the PMTU, it 410 * would not be fragmented, so it must be re-transmitted fragmented. 411 */ 412 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 413 } 414 415 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, 416 struct sk_buff *skb) 417 { 418 struct dst_entry *dst; 419 420 if (!t) 421 return; 422 dst = sctp_transport_dst_check(t); 423 if (dst) 424 dst->ops->redirect(dst, sk, skb); 425 } 426 427 /* 428 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 429 * 430 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 431 * or a "Protocol Unreachable" treat this message as an abort 432 * with the T bit set. 433 * 434 * This function sends an event to the state machine, which will abort the 435 * association. 436 * 437 */ 438 void sctp_icmp_proto_unreachable(struct sock *sk, 439 struct sctp_association *asoc, 440 struct sctp_transport *t) 441 { 442 if (sock_owned_by_user(sk)) { 443 if (timer_pending(&t->proto_unreach_timer)) 444 return; 445 else { 446 if (!mod_timer(&t->proto_unreach_timer, 447 jiffies + (HZ/20))) 448 sctp_association_hold(asoc); 449 } 450 } else { 451 struct net *net = sock_net(sk); 452 453 pr_debug("%s: unrecognized next header type " 454 "encountered!\n", __func__); 455 456 if (del_timer(&t->proto_unreach_timer)) 457 sctp_association_put(asoc); 458 459 sctp_do_sm(net, SCTP_EVENT_T_OTHER, 460 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 461 asoc->state, asoc->ep, asoc, t, 462 GFP_ATOMIC); 463 } 464 } 465 466 /* Common lookup code for icmp/icmpv6 error handler. */ 467 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, 468 struct sctphdr *sctphdr, 469 struct sctp_association **app, 470 struct sctp_transport **tpp) 471 { 472 union sctp_addr saddr; 473 union sctp_addr daddr; 474 struct sctp_af *af; 475 struct sock *sk = NULL; 476 struct sctp_association *asoc; 477 struct sctp_transport *transport = NULL; 478 struct sctp_init_chunk *chunkhdr; 479 __u32 vtag = ntohl(sctphdr->vtag); 480 int len = skb->len - ((void *)sctphdr - (void *)skb->data); 481 482 *app = NULL; *tpp = NULL; 483 484 af = sctp_get_af_specific(family); 485 if (unlikely(!af)) { 486 return NULL; 487 } 488 489 /* Initialize local addresses for lookups. */ 490 af->from_skb(&saddr, skb, 1); 491 af->from_skb(&daddr, skb, 0); 492 493 /* Look for an association that matches the incoming ICMP error 494 * packet. 495 */ 496 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport); 497 if (!asoc) 498 return NULL; 499 500 sk = asoc->base.sk; 501 502 /* RFC 4960, Appendix C. ICMP Handling 503 * 504 * ICMP6) An implementation MUST validate that the Verification Tag 505 * contained in the ICMP message matches the Verification Tag of 506 * the peer. If the Verification Tag is not 0 and does NOT 507 * match, discard the ICMP message. If it is 0 and the ICMP 508 * message contains enough bytes to verify that the chunk type is 509 * an INIT chunk and that the Initiate Tag matches the tag of the 510 * peer, continue with ICMP7. If the ICMP message is too short 511 * or the chunk type or the Initiate Tag does not match, silently 512 * discard the packet. 513 */ 514 if (vtag == 0) { 515 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr); 516 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) 517 + sizeof(__be32) || 518 chunkhdr->chunk_hdr.type != SCTP_CID_INIT || 519 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { 520 goto out; 521 } 522 } else if (vtag != asoc->c.peer_vtag) { 523 goto out; 524 } 525 526 bh_lock_sock(sk); 527 528 /* If too many ICMPs get dropped on busy 529 * servers this needs to be solved differently. 530 */ 531 if (sock_owned_by_user(sk)) 532 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 533 534 *app = asoc; 535 *tpp = transport; 536 return sk; 537 538 out: 539 sctp_association_put(asoc); 540 return NULL; 541 } 542 543 /* Common cleanup code for icmp/icmpv6 error handler. */ 544 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) 545 { 546 bh_unlock_sock(sk); 547 sctp_association_put(asoc); 548 } 549 550 /* 551 * This routine is called by the ICMP module when it gets some 552 * sort of error condition. If err < 0 then the socket should 553 * be closed and the error returned to the user. If err > 0 554 * it's just the icmp type << 8 | icmp code. After adjustment 555 * header points to the first 8 bytes of the sctp header. We need 556 * to find the appropriate port. 557 * 558 * The locking strategy used here is very "optimistic". When 559 * someone else accesses the socket the ICMP is just dropped 560 * and for some paths there is no check at all. 561 * A more general error queue to queue errors for later handling 562 * is probably better. 563 * 564 */ 565 void sctp_v4_err(struct sk_buff *skb, __u32 info) 566 { 567 const struct iphdr *iph = (const struct iphdr *)skb->data; 568 const int ihlen = iph->ihl * 4; 569 const int type = icmp_hdr(skb)->type; 570 const int code = icmp_hdr(skb)->code; 571 struct sock *sk; 572 struct sctp_association *asoc = NULL; 573 struct sctp_transport *transport; 574 struct inet_sock *inet; 575 __u16 saveip, savesctp; 576 int err; 577 struct net *net = dev_net(skb->dev); 578 579 /* Fix up skb to look at the embedded net header. */ 580 saveip = skb->network_header; 581 savesctp = skb->transport_header; 582 skb_reset_network_header(skb); 583 skb_set_transport_header(skb, ihlen); 584 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 585 /* Put back, the original values. */ 586 skb->network_header = saveip; 587 skb->transport_header = savesctp; 588 if (!sk) { 589 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 590 return; 591 } 592 /* Warning: The sock lock is held. Remember to call 593 * sctp_err_finish! 594 */ 595 596 switch (type) { 597 case ICMP_PARAMETERPROB: 598 err = EPROTO; 599 break; 600 case ICMP_DEST_UNREACH: 601 if (code > NR_ICMP_UNREACH) 602 goto out_unlock; 603 604 /* PMTU discovery (RFC1191) */ 605 if (ICMP_FRAG_NEEDED == code) { 606 sctp_icmp_frag_needed(sk, asoc, transport, 607 WORD_TRUNC(info)); 608 goto out_unlock; 609 } else { 610 if (ICMP_PROT_UNREACH == code) { 611 sctp_icmp_proto_unreachable(sk, asoc, 612 transport); 613 goto out_unlock; 614 } 615 } 616 err = icmp_err_convert[code].errno; 617 break; 618 case ICMP_TIME_EXCEEDED: 619 /* Ignore any time exceeded errors due to fragment reassembly 620 * timeouts. 621 */ 622 if (ICMP_EXC_FRAGTIME == code) 623 goto out_unlock; 624 625 err = EHOSTUNREACH; 626 break; 627 case ICMP_REDIRECT: 628 sctp_icmp_redirect(sk, transport, skb); 629 /* Fall through to out_unlock. */ 630 default: 631 goto out_unlock; 632 } 633 634 inet = inet_sk(sk); 635 if (!sock_owned_by_user(sk) && inet->recverr) { 636 sk->sk_err = err; 637 sk->sk_error_report(sk); 638 } else { /* Only an error on timeout */ 639 sk->sk_err_soft = err; 640 } 641 642 out_unlock: 643 sctp_err_finish(sk, asoc); 644 } 645 646 /* 647 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 648 * 649 * This function scans all the chunks in the OOTB packet to determine if 650 * the packet should be discarded right away. If a response might be needed 651 * for this packet, or, if further processing is possible, the packet will 652 * be queued to a proper inqueue for the next phase of handling. 653 * 654 * Output: 655 * Return 0 - If further processing is needed. 656 * Return 1 - If the packet can be discarded right away. 657 */ 658 static int sctp_rcv_ootb(struct sk_buff *skb) 659 { 660 sctp_chunkhdr_t *ch; 661 __u8 *ch_end; 662 663 ch = (sctp_chunkhdr_t *) skb->data; 664 665 /* Scan through all the chunks in the packet. */ 666 do { 667 /* Break out if chunk length is less then minimal. */ 668 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 669 break; 670 671 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 672 if (ch_end > skb_tail_pointer(skb)) 673 break; 674 675 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 676 * receiver MUST silently discard the OOTB packet and take no 677 * further action. 678 */ 679 if (SCTP_CID_ABORT == ch->type) 680 goto discard; 681 682 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 683 * chunk, the receiver should silently discard the packet 684 * and take no further action. 685 */ 686 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 687 goto discard; 688 689 /* RFC 4460, 2.11.2 690 * This will discard packets with INIT chunk bundled as 691 * subsequent chunks in the packet. When INIT is first, 692 * the normal INIT processing will discard the chunk. 693 */ 694 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 695 goto discard; 696 697 ch = (sctp_chunkhdr_t *) ch_end; 698 } while (ch_end < skb_tail_pointer(skb)); 699 700 return 0; 701 702 discard: 703 return 1; 704 } 705 706 /* Insert endpoint into the hash table. */ 707 static void __sctp_hash_endpoint(struct sctp_endpoint *ep) 708 { 709 struct net *net = sock_net(ep->base.sk); 710 struct sctp_ep_common *epb; 711 struct sctp_hashbucket *head; 712 713 epb = &ep->base; 714 715 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 716 head = &sctp_ep_hashtable[epb->hashent]; 717 718 write_lock(&head->lock); 719 hlist_add_head(&epb->node, &head->chain); 720 write_unlock(&head->lock); 721 } 722 723 /* Add an endpoint to the hash. Local BH-safe. */ 724 void sctp_hash_endpoint(struct sctp_endpoint *ep) 725 { 726 local_bh_disable(); 727 __sctp_hash_endpoint(ep); 728 local_bh_enable(); 729 } 730 731 /* Remove endpoint from the hash table. */ 732 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 733 { 734 struct net *net = sock_net(ep->base.sk); 735 struct sctp_hashbucket *head; 736 struct sctp_ep_common *epb; 737 738 epb = &ep->base; 739 740 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); 741 742 head = &sctp_ep_hashtable[epb->hashent]; 743 744 write_lock(&head->lock); 745 hlist_del_init(&epb->node); 746 write_unlock(&head->lock); 747 } 748 749 /* Remove endpoint from the hash. Local BH-safe. */ 750 void sctp_unhash_endpoint(struct sctp_endpoint *ep) 751 { 752 local_bh_disable(); 753 __sctp_unhash_endpoint(ep); 754 local_bh_enable(); 755 } 756 757 /* Look up an endpoint. */ 758 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, 759 const union sctp_addr *laddr) 760 { 761 struct sctp_hashbucket *head; 762 struct sctp_ep_common *epb; 763 struct sctp_endpoint *ep; 764 int hash; 765 766 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port)); 767 head = &sctp_ep_hashtable[hash]; 768 read_lock(&head->lock); 769 sctp_for_each_hentry(epb, &head->chain) { 770 ep = sctp_ep(epb); 771 if (sctp_endpoint_is_match(ep, net, laddr)) 772 goto hit; 773 } 774 775 ep = sctp_sk(net->sctp.ctl_sock)->ep; 776 777 hit: 778 sctp_endpoint_hold(ep); 779 read_unlock(&head->lock); 780 return ep; 781 } 782 783 /* rhashtable for transport */ 784 struct sctp_hash_cmp_arg { 785 const struct sctp_endpoint *ep; 786 const union sctp_addr *laddr; 787 const union sctp_addr *paddr; 788 const struct net *net; 789 }; 790 791 static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, 792 const void *ptr) 793 { 794 const struct sctp_hash_cmp_arg *x = arg->key; 795 const struct sctp_transport *t = ptr; 796 struct sctp_association *asoc = t->asoc; 797 const struct net *net = x->net; 798 799 if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) 800 return 1; 801 if (!net_eq(sock_net(asoc->base.sk), net)) 802 return 1; 803 if (x->ep) { 804 if (x->ep != asoc->ep) 805 return 1; 806 } else { 807 if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port)) 808 return 1; 809 if (!sctp_bind_addr_match(&asoc->base.bind_addr, 810 x->laddr, sctp_sk(asoc->base.sk))) 811 return 1; 812 } 813 814 return 0; 815 } 816 817 static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed) 818 { 819 const struct sctp_transport *t = data; 820 const union sctp_addr *paddr = &t->ipaddr; 821 const struct net *net = sock_net(t->asoc->base.sk); 822 u16 lport = htons(t->asoc->base.bind_addr.port); 823 u32 addr; 824 825 if (paddr->sa.sa_family == AF_INET6) 826 addr = jhash(&paddr->v6.sin6_addr, 16, seed); 827 else 828 addr = paddr->v4.sin_addr.s_addr; 829 830 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | 831 (__force __u32)lport, net_hash_mix(net), seed); 832 } 833 834 static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed) 835 { 836 const struct sctp_hash_cmp_arg *x = data; 837 const union sctp_addr *paddr = x->paddr; 838 const struct net *net = x->net; 839 u16 lport; 840 u32 addr; 841 842 lport = x->ep ? htons(x->ep->base.bind_addr.port) : 843 x->laddr->v4.sin_port; 844 if (paddr->sa.sa_family == AF_INET6) 845 addr = jhash(&paddr->v6.sin6_addr, 16, seed); 846 else 847 addr = paddr->v4.sin_addr.s_addr; 848 849 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | 850 (__force __u32)lport, net_hash_mix(net), seed); 851 } 852 853 static const struct rhashtable_params sctp_hash_params = { 854 .head_offset = offsetof(struct sctp_transport, node), 855 .hashfn = sctp_hash_key, 856 .obj_hashfn = sctp_hash_obj, 857 .obj_cmpfn = sctp_hash_cmp, 858 .automatic_shrinking = true, 859 }; 860 861 int sctp_transport_hashtable_init(void) 862 { 863 return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params); 864 } 865 866 void sctp_transport_hashtable_destroy(void) 867 { 868 rhashtable_destroy(&sctp_transport_hashtable); 869 } 870 871 void sctp_hash_transport(struct sctp_transport *t) 872 { 873 struct sctp_hash_cmp_arg arg; 874 875 if (t->asoc->temp) 876 return; 877 878 arg.ep = t->asoc->ep; 879 arg.paddr = &t->ipaddr; 880 arg.net = sock_net(t->asoc->base.sk); 881 882 reinsert: 883 if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg, 884 &t->node, sctp_hash_params) == -EBUSY) 885 goto reinsert; 886 } 887 888 void sctp_unhash_transport(struct sctp_transport *t) 889 { 890 if (t->asoc->temp) 891 return; 892 893 rhashtable_remove_fast(&sctp_transport_hashtable, &t->node, 894 sctp_hash_params); 895 } 896 897 struct sctp_transport *sctp_addrs_lookup_transport( 898 struct net *net, 899 const union sctp_addr *laddr, 900 const union sctp_addr *paddr) 901 { 902 struct sctp_hash_cmp_arg arg = { 903 .ep = NULL, 904 .laddr = laddr, 905 .paddr = paddr, 906 .net = net, 907 }; 908 909 return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg, 910 sctp_hash_params); 911 } 912 913 struct sctp_transport *sctp_epaddr_lookup_transport( 914 const struct sctp_endpoint *ep, 915 const union sctp_addr *paddr) 916 { 917 struct net *net = sock_net(ep->base.sk); 918 struct sctp_hash_cmp_arg arg = { 919 .ep = ep, 920 .paddr = paddr, 921 .net = net, 922 }; 923 924 return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg, 925 sctp_hash_params); 926 } 927 928 /* Look up an association. */ 929 static struct sctp_association *__sctp_lookup_association( 930 struct net *net, 931 const union sctp_addr *local, 932 const union sctp_addr *peer, 933 struct sctp_transport **pt) 934 { 935 struct sctp_transport *t; 936 struct sctp_association *asoc = NULL; 937 938 t = sctp_addrs_lookup_transport(net, local, peer); 939 if (!t || !sctp_transport_hold(t)) 940 goto out; 941 942 asoc = t->asoc; 943 sctp_association_hold(asoc); 944 *pt = t; 945 946 sctp_transport_put(t); 947 948 out: 949 return asoc; 950 } 951 952 /* Look up an association. protected by RCU read lock */ 953 static 954 struct sctp_association *sctp_lookup_association(struct net *net, 955 const union sctp_addr *laddr, 956 const union sctp_addr *paddr, 957 struct sctp_transport **transportp) 958 { 959 struct sctp_association *asoc; 960 961 rcu_read_lock(); 962 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 963 rcu_read_unlock(); 964 965 return asoc; 966 } 967 968 /* Is there an association matching the given local and peer addresses? */ 969 int sctp_has_association(struct net *net, 970 const union sctp_addr *laddr, 971 const union sctp_addr *paddr) 972 { 973 struct sctp_association *asoc; 974 struct sctp_transport *transport; 975 976 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { 977 sctp_association_put(asoc); 978 return 1; 979 } 980 981 return 0; 982 } 983 984 /* 985 * SCTP Implementors Guide, 2.18 Handling of address 986 * parameters within the INIT or INIT-ACK. 987 * 988 * D) When searching for a matching TCB upon reception of an INIT 989 * or INIT-ACK chunk the receiver SHOULD use not only the 990 * source address of the packet (containing the INIT or 991 * INIT-ACK) but the receiver SHOULD also use all valid 992 * address parameters contained within the chunk. 993 * 994 * 2.18.3 Solution description 995 * 996 * This new text clearly specifies to an implementor the need 997 * to look within the INIT or INIT-ACK. Any implementation that 998 * does not do this, may not be able to establish associations 999 * in certain circumstances. 1000 * 1001 */ 1002 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, 1003 struct sk_buff *skb, 1004 const union sctp_addr *laddr, struct sctp_transport **transportp) 1005 { 1006 struct sctp_association *asoc; 1007 union sctp_addr addr; 1008 union sctp_addr *paddr = &addr; 1009 struct sctphdr *sh = sctp_hdr(skb); 1010 union sctp_params params; 1011 sctp_init_chunk_t *init; 1012 struct sctp_transport *transport; 1013 struct sctp_af *af; 1014 1015 /* 1016 * This code will NOT touch anything inside the chunk--it is 1017 * strictly READ-ONLY. 1018 * 1019 * RFC 2960 3 SCTP packet Format 1020 * 1021 * Multiple chunks can be bundled into one SCTP packet up to 1022 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 1023 * COMPLETE chunks. These chunks MUST NOT be bundled with any 1024 * other chunk in a packet. See Section 6.10 for more details 1025 * on chunk bundling. 1026 */ 1027 1028 /* Find the start of the TLVs and the end of the chunk. This is 1029 * the region we search for address parameters. 1030 */ 1031 init = (sctp_init_chunk_t *)skb->data; 1032 1033 /* Walk the parameters looking for embedded addresses. */ 1034 sctp_walk_params(params, init, init_hdr.params) { 1035 1036 /* Note: Ignoring hostname addresses. */ 1037 af = sctp_get_af_specific(param_type2af(params.p->type)); 1038 if (!af) 1039 continue; 1040 1041 af->from_addr_param(paddr, params.addr, sh->source, 0); 1042 1043 asoc = __sctp_lookup_association(net, laddr, paddr, &transport); 1044 if (asoc) 1045 return asoc; 1046 } 1047 1048 return NULL; 1049 } 1050 1051 /* ADD-IP, Section 5.2 1052 * When an endpoint receives an ASCONF Chunk from the remote peer 1053 * special procedures may be needed to identify the association the 1054 * ASCONF Chunk is associated with. To properly find the association 1055 * the following procedures SHOULD be followed: 1056 * 1057 * D2) If the association is not found, use the address found in the 1058 * Address Parameter TLV combined with the port number found in the 1059 * SCTP common header. If found proceed to rule D4. 1060 * 1061 * D2-ext) If more than one ASCONF Chunks are packed together, use the 1062 * address found in the ASCONF Address Parameter TLV of each of the 1063 * subsequent ASCONF Chunks. If found, proceed to rule D4. 1064 */ 1065 static struct sctp_association *__sctp_rcv_asconf_lookup( 1066 struct net *net, 1067 sctp_chunkhdr_t *ch, 1068 const union sctp_addr *laddr, 1069 __be16 peer_port, 1070 struct sctp_transport **transportp) 1071 { 1072 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; 1073 struct sctp_af *af; 1074 union sctp_addr_param *param; 1075 union sctp_addr paddr; 1076 1077 /* Skip over the ADDIP header and find the Address parameter */ 1078 param = (union sctp_addr_param *)(asconf + 1); 1079 1080 af = sctp_get_af_specific(param_type2af(param->p.type)); 1081 if (unlikely(!af)) 1082 return NULL; 1083 1084 af->from_addr_param(&paddr, param, peer_port, 0); 1085 1086 return __sctp_lookup_association(net, laddr, &paddr, transportp); 1087 } 1088 1089 1090 /* SCTP-AUTH, Section 6.3: 1091 * If the receiver does not find a STCB for a packet containing an AUTH 1092 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second 1093 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing 1094 * association. 1095 * 1096 * This means that any chunks that can help us identify the association need 1097 * to be looked at to find this association. 1098 */ 1099 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, 1100 struct sk_buff *skb, 1101 const union sctp_addr *laddr, 1102 struct sctp_transport **transportp) 1103 { 1104 struct sctp_association *asoc = NULL; 1105 sctp_chunkhdr_t *ch; 1106 int have_auth = 0; 1107 unsigned int chunk_num = 1; 1108 __u8 *ch_end; 1109 1110 /* Walk through the chunks looking for AUTH or ASCONF chunks 1111 * to help us find the association. 1112 */ 1113 ch = (sctp_chunkhdr_t *) skb->data; 1114 do { 1115 /* Break out if chunk length is less then minimal. */ 1116 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) 1117 break; 1118 1119 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 1120 if (ch_end > skb_tail_pointer(skb)) 1121 break; 1122 1123 switch (ch->type) { 1124 case SCTP_CID_AUTH: 1125 have_auth = chunk_num; 1126 break; 1127 1128 case SCTP_CID_COOKIE_ECHO: 1129 /* If a packet arrives containing an AUTH chunk as 1130 * a first chunk, a COOKIE-ECHO chunk as the second 1131 * chunk, and possibly more chunks after them, and 1132 * the receiver does not have an STCB for that 1133 * packet, then authentication is based on 1134 * the contents of the COOKIE- ECHO chunk. 1135 */ 1136 if (have_auth == 1 && chunk_num == 2) 1137 return NULL; 1138 break; 1139 1140 case SCTP_CID_ASCONF: 1141 if (have_auth || net->sctp.addip_noauth) 1142 asoc = __sctp_rcv_asconf_lookup( 1143 net, ch, laddr, 1144 sctp_hdr(skb)->source, 1145 transportp); 1146 default: 1147 break; 1148 } 1149 1150 if (asoc) 1151 break; 1152 1153 ch = (sctp_chunkhdr_t *) ch_end; 1154 chunk_num++; 1155 } while (ch_end < skb_tail_pointer(skb)); 1156 1157 return asoc; 1158 } 1159 1160 /* 1161 * There are circumstances when we need to look inside the SCTP packet 1162 * for information to help us find the association. Examples 1163 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1164 * chunks. 1165 */ 1166 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, 1167 struct sk_buff *skb, 1168 const union sctp_addr *laddr, 1169 struct sctp_transport **transportp) 1170 { 1171 sctp_chunkhdr_t *ch; 1172 1173 ch = (sctp_chunkhdr_t *) skb->data; 1174 1175 /* The code below will attempt to walk the chunk and extract 1176 * parameter information. Before we do that, we need to verify 1177 * that the chunk length doesn't cause overflow. Otherwise, we'll 1178 * walk off the end. 1179 */ 1180 if (WORD_ROUND(ntohs(ch->length)) > skb->len) 1181 return NULL; 1182 1183 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1184 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) 1185 return __sctp_rcv_init_lookup(net, skb, laddr, transportp); 1186 1187 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); 1188 } 1189 1190 /* Lookup an association for an inbound skb. */ 1191 static struct sctp_association *__sctp_rcv_lookup(struct net *net, 1192 struct sk_buff *skb, 1193 const union sctp_addr *paddr, 1194 const union sctp_addr *laddr, 1195 struct sctp_transport **transportp) 1196 { 1197 struct sctp_association *asoc; 1198 1199 asoc = __sctp_lookup_association(net, laddr, paddr, transportp); 1200 1201 /* Further lookup for INIT/INIT-ACK packets. 1202 * SCTP Implementors Guide, 2.18 Handling of address 1203 * parameters within the INIT or INIT-ACK. 1204 */ 1205 if (!asoc) 1206 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); 1207 1208 return asoc; 1209 } 1210