1// SPDX-License-Identifier: GPL-2.0-or-later 2/* SCTP kernel implementation 3 * Copyright (c) 1999-2000 Cisco, Inc. 4 * Copyright (c) 1999-2001 Motorola, Inc. 5 * Copyright (c) 2001-2003 International Business Machines, Corp. 6 * Copyright (c) 2001 Intel Corp. 7 * Copyright (c) 2001 Nokia, Inc. 8 * Copyright (c) 2001 La Monte H.P. Yarroll 9 * 10 * This file is part of the SCTP kernel implementation 11 * 12 * These functions handle all input from the IP layer into SCTP. 13 * 14 * Please send any bug reports or fixes you make to the 15 * email address(es): 16 * lksctp developers <linux-sctp@vger.kernel.org> 17 * 18 * Written or modified by: 19 * La Monte H.P. Yarroll <piggy@acm.org> 20 * Karl Knutson <karl@athena.chicago.il.us> 21 * Xingang Guo <xingang.guo@intel.com> 22 * Jon Grimm <jgrimm@us.ibm.com> 23 * Hui Huang <hui.huang@nokia.com> 24 * Daisy Chang <daisyc@us.ibm.com> 25 * Sridhar Samudrala <sri@us.ibm.com> 26 * Ardelle Fan <ardelle.fan@intel.com> 27 */ 28 29#include <linux/types.h> 30#include <linux/list.h> /* For struct list_head */ 31#include <linux/socket.h> 32#include <linux/ip.h> 33#include <linux/time.h> /* For struct timeval */ 34#include <linux/slab.h> 35#include <net/ip.h> 36#include <net/icmp.h> 37#include <net/snmp.h> 38#include <net/sock.h> 39#include <net/xfrm.h> 40#include <net/sctp/sctp.h> 41#include <net/sctp/sm.h> 42#include <net/sctp/checksum.h> 43#include <net/net_namespace.h> 44#include <linux/rhashtable.h> 45#include <net/sock_reuseport.h> 46 47/* Forward declarations for internal helpers. */ 48static int sctp_rcv_ootb(struct sk_buff *); 49static struct sctp_association *__sctp_rcv_lookup(struct net *net, 50 struct sk_buff *skb, 51 const union sctp_addr *paddr, 52 const union sctp_addr *laddr, 53 struct sctp_transport **transportp, 54 int dif, int sdif); 55static struct sctp_endpoint *__sctp_rcv_lookup_endpoint( 56 struct net *net, struct sk_buff *skb, 57 const union sctp_addr *laddr, 58 const union sctp_addr *daddr, 59 int dif, int sdif); 60static struct sctp_association *__sctp_lookup_association( 61 struct net *net, 62 const union sctp_addr *local, 63 const union sctp_addr *peer, 64 struct sctp_transport **pt, 65 int dif, int sdif); 66 67static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); 68 69 70/* Calculate the SCTP checksum of an SCTP packet. */ 71static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb) 72{ 73 struct sctphdr *sh = sctp_hdr(skb); 74 __le32 cmp = sh->checksum; 75 __le32 val = sctp_compute_cksum(skb, 0); 76 77 if (val != cmp) { 78 /* CRC failure, dump it. */ 79 __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS); 80 return -1; 81 } 82 return 0; 83} 84 85/* 86 * This is the routine which IP calls when receiving an SCTP packet. 87 */ 88int sctp_rcv(struct sk_buff *skb) 89{ 90 struct sock *sk; 91 struct sctp_association *asoc; 92 struct sctp_endpoint *ep = NULL; 93 struct sctp_ep_common *rcvr; 94 struct sctp_transport *transport = NULL; 95 struct sctp_chunk *chunk; 96 union sctp_addr src; 97 union sctp_addr dest; 98 int family; 99 struct sctp_af *af; 100 struct net *net = dev_net(skb->dev); 101 bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb); 102 int dif, sdif; 103 104 if (skb->pkt_type != PACKET_HOST) 105 goto discard_it; 106 107 __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS); 108 109 /* If packet is too small to contain a single chunk, let's not 110 * waste time on it anymore. 111 */ 112 if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + 113 skb_transport_offset(skb)) 114 goto discard_it; 115 116 /* If the packet is fragmented and we need to do crc checking, 117 * it's better to just linearize it otherwise crc computing 118 * takes longer. 119 */ 120 if ((!is_gso && skb_linearize(skb)) || 121 !pskb_may_pull(skb, sizeof(struct sctphdr))) 122 goto discard_it; 123 124 /* Pull up the IP header. */ 125 __skb_pull(skb, skb_transport_offset(skb)); 126 127 skb->csum_valid = 0; /* Previous value not applicable */ 128 if (skb_csum_unnecessary(skb)) 129 __skb_decr_checksum_unnecessary(skb); 130 else if (!sctp_checksum_disable && 131 !is_gso && 132 sctp_rcv_checksum(net, skb) < 0) 133 goto discard_it; 134 skb->csum_valid = 1; 135 136 __skb_pull(skb, sizeof(struct sctphdr)); 137 138 family = ipver2af(ip_hdr(skb)->version); 139 af = sctp_get_af_specific(family); 140 if (unlikely(!af)) 141 goto discard_it; 142 SCTP_INPUT_CB(skb)->af = af; 143 144 /* Initialize local addresses for lookups. */ 145 af->from_skb(&src, skb, 1); 146 af->from_skb(&dest, skb, 0); 147 dif = af->skb_iif(skb); 148 sdif = af->skb_sdif(skb); 149 150 /* If the packet is to or from a non-unicast address, 151 * silently discard the packet. 152 * 153 * This is not clearly defined in the RFC except in section 154 * 8.4 - OOTB handling. However, based on the book "Stream Control 155 * Transmission Protocol" 2.1, "It is important to note that the 156 * IP address of an SCTP transport address must be a routable 157 * unicast address. In other words, IP multicast addresses and 158 * IP broadcast addresses cannot be used in an SCTP transport 159 * address." 160 */ 161 if (!af->addr_valid(&src, NULL, skb) || 162 !af->addr_valid(&dest, NULL, skb)) 163 goto discard_it; 164 165 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport, dif, sdif); 166 167 if (!asoc) 168 ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src, dif, sdif); 169 170 /* Retrieve the common input handling substructure. */ 171 rcvr = asoc ? &asoc->base : &ep->base; 172 sk = rcvr->sk; 173 174 /* 175 * RFC 2960, 8.4 - Handle "Out of the blue" Packets. 176 * An SCTP packet is called an "out of the blue" (OOTB) 177 * packet if it is correctly formed, i.e., passed the 178 * receiver's checksum check, but the receiver is not 179 * able to identify the association to which this 180 * packet belongs. 181 */ 182 if (!asoc) { 183 if (sctp_rcv_ootb(skb)) { 184 __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); 185 goto discard_release; 186 } 187 } 188 189 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) 190 goto discard_release; 191 nf_reset_ct(skb); 192 193 if (sk_filter(sk, skb)) 194 goto discard_release; 195 196 /* Create an SCTP packet structure. */ 197 chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC); 198 if (!chunk) 199 goto discard_release; 200 SCTP_INPUT_CB(skb)->chunk = chunk; 201 202 /* Remember what endpoint is to handle this packet. */ 203 chunk->rcvr = rcvr; 204 205 /* Remember the SCTP header. */ 206 chunk->sctp_hdr = sctp_hdr(skb); 207 208 /* Set the source and destination addresses of the incoming chunk. */ 209 sctp_init_addrs(chunk, &src, &dest); 210 211 /* Remember where we came from. */ 212 chunk->transport = transport; 213 214 /* Acquire access to the sock lock. Note: We are safe from other 215 * bottom halves on this lock, but a user may be in the lock too, 216 * so check if it is busy. 217 */ 218 bh_lock_sock(sk); 219 220 if (sk != rcvr->sk) { 221 /* Our cached sk is different from the rcvr->sk. This is 222 * because migrate()/accept() may have moved the association 223 * to a new socket and released all the sockets. So now we 224 * are holding a lock on the old socket while the user may 225 * be doing something with the new socket. Switch our veiw 226 * of the current sk. 227 */ 228 bh_unlock_sock(sk); 229 sk = rcvr->sk; 230 bh_lock_sock(sk); 231 } 232 233 if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) { 234 if (sctp_add_backlog(sk, skb)) { 235 bh_unlock_sock(sk); 236 sctp_chunk_free(chunk); 237 skb = NULL; /* sctp_chunk_free already freed the skb */ 238 goto discard_release; 239 } 240 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG); 241 } else { 242 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ); 243 sctp_inq_push(&chunk->rcvr->inqueue, chunk); 244 } 245 246 bh_unlock_sock(sk); 247 248 /* Release the asoc/ep ref we took in the lookup calls. */ 249 if (transport) 250 sctp_transport_put(transport); 251 else 252 sctp_endpoint_put(ep); 253 254 return 0; 255 256discard_it: 257 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); 258 kfree_skb(skb); 259 return 0; 260 261discard_release: 262 /* Release the asoc/ep ref we took in the lookup calls. */ 263 if (transport) 264 sctp_transport_put(transport); 265 else 266 sctp_endpoint_put(ep); 267 268 goto discard_it; 269} 270 271/* Process the backlog queue of the socket. Every skb on 272 * the backlog holds a ref on an association or endpoint. 273 * We hold this ref throughout the state machine to make 274 * sure that the structure we need is still around. 275 */ 276int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) 277{ 278 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 279 struct sctp_inq *inqueue = &chunk->rcvr->inqueue; 280 struct sctp_transport *t = chunk->transport; 281 struct sctp_ep_common *rcvr = NULL; 282 int backloged = 0; 283 284 rcvr = chunk->rcvr; 285 286 /* If the rcvr is dead then the association or endpoint 287 * has been deleted and we can safely drop the chunk 288 * and refs that we are holding. 289 */ 290 if (rcvr->dead) { 291 sctp_chunk_free(chunk); 292 goto done; 293 } 294 295 if (unlikely(rcvr->sk != sk)) { 296 /* In this case, the association moved from one socket to 297 * another. We are currently sitting on the backlog of the 298 * old socket, so we need to move. 299 * However, since we are here in the process context we 300 * need to take make sure that the user doesn't own 301 * the new socket when we process the packet. 302 * If the new socket is user-owned, queue the chunk to the 303 * backlog of the new socket without dropping any refs. 304 * Otherwise, we can safely push the chunk on the inqueue. 305 */ 306 307 sk = rcvr->sk; 308 local_bh_disable(); 309 bh_lock_sock(sk); 310 311 if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) { 312 if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf))) 313 sctp_chunk_free(chunk); 314 else 315 backloged = 1; 316 } else 317 sctp_inq_push(inqueue, chunk); 318 319 bh_unlock_sock(sk); 320 local_bh_enable(); 321 322 /* If the chunk was backloged again, don't drop refs */ 323 if (backloged) 324 return 0; 325 } else { 326 if (!sctp_newsk_ready(sk)) { 327 if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf))) 328 return 0; 329 sctp_chunk_free(chunk); 330 } else { 331 sctp_inq_push(inqueue, chunk); 332 } 333 } 334 335done: 336 /* Release the refs we took in sctp_add_backlog */ 337 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 338 sctp_transport_put(t); 339 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 340 sctp_endpoint_put(sctp_ep(rcvr)); 341 else 342 BUG(); 343 344 return 0; 345} 346 347static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) 348{ 349 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; 350 struct sctp_transport *t = chunk->transport; 351 struct sctp_ep_common *rcvr = chunk->rcvr; 352 int ret; 353 354 ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)); 355 if (!ret) { 356 /* Hold the assoc/ep while hanging on the backlog queue. 357 * This way, we know structures we need will not disappear 358 * from us 359 */ 360 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) 361 sctp_transport_hold(t); 362 else if (SCTP_EP_TYPE_SOCKET == rcvr->type) 363 sctp_endpoint_hold(sctp_ep(rcvr)); 364 else 365 BUG(); 366 } 367 return ret; 368 369} 370 371/* Handle icmp frag needed error. */ 372void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, 373 struct sctp_transport *t, __u32 pmtu) 374{ 375 if (!t || 376 (t->pathmtu <= pmtu && 377 t->pl.probe_size + sctp_transport_pl_hlen(t) <= pmtu)) 378 return; 379 380 if (sock_owned_by_user(sk)) { 381 atomic_set(&t->mtu_info, pmtu); 382 asoc->pmtu_pending = 1; 383 t->pmtu_pending = 1; 384 return; 385 } 386 387 if (!(t->param_flags & SPP_PMTUD_ENABLE)) 388 /* We can't allow retransmitting in such case, as the 389 * retransmission would be sized just as before, and thus we 390 * would get another icmp, and retransmit again. 391 */ 392 return; 393 394 /* Update transports view of the MTU. Return if no update was needed. 395 * If an update wasn't needed/possible, it also doesn't make sense to 396 * try to retransmit now. 397 */ 398 if (!sctp_transport_update_pmtu(t, pmtu)) 399 return; 400 401 /* Update association pmtu. */ 402 sctp_assoc_sync_pmtu(asoc); 403 404 /* Retransmit with the new pmtu setting. */ 405 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); 406} 407 408void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, 409 struct sk_buff *skb) 410{ 411 struct dst_entry *dst; 412 413 if (sock_owned_by_user(sk) || !t) 414 return; 415 dst = sctp_transport_dst_check(t); 416 if (dst) 417 dst->ops->redirect(dst, sk, skb); 418} 419 420/* 421 * SCTP Implementer's Guide, 2.37 ICMP handling procedures 422 * 423 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" 424 * or a "Protocol Unreachable" treat this message as an abort 425 * with the T bit set. 426 * 427 * This function sends an event to the state machine, which will abort the 428 * association. 429 * 430 */ 431void sctp_icmp_proto_unreachable(struct sock *sk, 432 struct sctp_association *asoc, 433 struct sctp_transport *t) 434{ 435 if (sock_owned_by_user(sk)) { 436 if (timer_pending(&t->proto_unreach_timer)) 437 return; 438 else { 439 if (!mod_timer(&t->proto_unreach_timer, 440 jiffies + (HZ/20))) 441 sctp_transport_hold(t); 442 } 443 } else { 444 struct net *net = sock_net(sk); 445 446 pr_debug("%s: unrecognized next header type " 447 "encountered!\n", __func__); 448 449 if (del_timer(&t->proto_unreach_timer)) 450 sctp_transport_put(t); 451 452 sctp_do_sm(net, SCTP_EVENT_T_OTHER, 453 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), 454 asoc->state, asoc->ep, asoc, t, 455 GFP_ATOMIC); 456 } 457} 458 459/* Common lookup code for icmp/icmpv6 error handler. */ 460struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, 461 struct sctphdr *sctphdr, 462 struct sctp_association **app, 463 struct sctp_transport **tpp) 464{ 465 struct sctp_init_chunk *chunkhdr, _chunkhdr; 466 union sctp_addr saddr; 467 union sctp_addr daddr; 468 struct sctp_af *af; 469 struct sock *sk = NULL; 470 struct sctp_association *asoc; 471 struct sctp_transport *transport = NULL; 472 __u32 vtag = ntohl(sctphdr->vtag); 473 int sdif = inet_sdif(skb); 474 int dif = inet_iif(skb); 475 476 *app = NULL; *tpp = NULL; 477 478 af = sctp_get_af_specific(family); 479 if (unlikely(!af)) { 480 return NULL; 481 } 482 483 /* Initialize local addresses for lookups. */ 484 af->from_skb(&saddr, skb, 1); 485 af->from_skb(&daddr, skb, 0); 486 487 /* Look for an association that matches the incoming ICMP error 488 * packet. 489 */ 490 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport, dif, sdif); 491 if (!asoc) 492 return NULL; 493 494 sk = asoc->base.sk; 495 496 /* RFC 4960, Appendix C. ICMP Handling 497 * 498 * ICMP6) An implementation MUST validate that the Verification Tag 499 * contained in the ICMP message matches the Verification Tag of 500 * the peer. If the Verification Tag is not 0 and does NOT 501 * match, discard the ICMP message. If it is 0 and the ICMP 502 * message contains enough bytes to verify that the chunk type is 503 * an INIT chunk and that the Initiate Tag matches the tag of the 504 * peer, continue with ICMP7. If the ICMP message is too short 505 * or the chunk type or the Initiate Tag does not match, silently 506 * discard the packet. 507 */ 508 if (vtag == 0) { 509 /* chunk header + first 4 octects of init header */ 510 chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) + 511 sizeof(struct sctphdr), 512 sizeof(struct sctp_chunkhdr) + 513 sizeof(__be32), &_chunkhdr); 514 if (!chunkhdr || 515 chunkhdr->chunk_hdr.type != SCTP_CID_INIT || 516 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) 517 goto out; 518 519 } else if (vtag != asoc->c.peer_vtag) { 520 goto out; 521 } 522 523 bh_lock_sock(sk); 524 525 /* If too many ICMPs get dropped on busy 526 * servers this needs to be solved differently. 527 */ 528 if (sock_owned_by_user(sk)) 529 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 530 531 *app = asoc; 532 *tpp = transport; 533 return sk; 534 535out: 536 sctp_transport_put(transport); 537 return NULL; 538} 539 540/* Common cleanup code for icmp/icmpv6 error handler. */ 541void sctp_err_finish(struct sock *sk, struct sctp_transport *t) 542 __releases(&((__sk)->sk_lock.slock)) 543{ 544 bh_unlock_sock(sk); 545 sctp_transport_put(t); 546} 547 548static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb, 549 __u8 type, __u8 code, __u32 info) 550{ 551 struct sctp_association *asoc = t->asoc; 552 struct sock *sk = asoc->base.sk; 553 int err = 0; 554 555 switch (type) { 556 case ICMP_PARAMETERPROB: 557 err = EPROTO; 558 break; 559 case ICMP_DEST_UNREACH: 560 if (code > NR_ICMP_UNREACH) 561 return; 562 if (code == ICMP_FRAG_NEEDED) { 563 sctp_icmp_frag_needed(sk, asoc, t, SCTP_TRUNC4(info)); 564 return; 565 } 566 if (code == ICMP_PROT_UNREACH) { 567 sctp_icmp_proto_unreachable(sk, asoc, t); 568 return; 569 } 570 err = icmp_err_convert[code].errno; 571 break; 572 case ICMP_TIME_EXCEEDED: 573 if (code == ICMP_EXC_FRAGTIME) 574 return; 575 576 err = EHOSTUNREACH; 577 break; 578 case ICMP_REDIRECT: 579 sctp_icmp_redirect(sk, t, skb); 580 return; 581 default: 582 return; 583 } 584 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) { 585 sk->sk_err = err; 586 sk_error_report(sk); 587 } else { /* Only an error on timeout */ 588 WRITE_ONCE(sk->sk_err_soft, err); 589 } 590} 591 592/* 593 * This routine is called by the ICMP module when it gets some 594 * sort of error condition. If err < 0 then the socket should 595 * be closed and the error returned to the user. If err > 0 596 * it's just the icmp type << 8 | icmp code. After adjustment 597 * header points to the first 8 bytes of the sctp header. We need 598 * to find the appropriate port. 599 * 600 * The locking strategy used here is very "optimistic". When 601 * someone else accesses the socket the ICMP is just dropped 602 * and for some paths there is no check at all. 603 * A more general error queue to queue errors for later handling 604 * is probably better. 605 * 606 */ 607int sctp_v4_err(struct sk_buff *skb, __u32 info) 608{ 609 const struct iphdr *iph = (const struct iphdr *)skb->data; 610 const int type = icmp_hdr(skb)->type; 611 const int code = icmp_hdr(skb)->code; 612 struct net *net = dev_net(skb->dev); 613 struct sctp_transport *transport; 614 struct sctp_association *asoc; 615 __u16 saveip, savesctp; 616 struct sock *sk; 617 618 /* Fix up skb to look at the embedded net header. */ 619 saveip = skb->network_header; 620 savesctp = skb->transport_header; 621 skb_reset_network_header(skb); 622 skb_set_transport_header(skb, iph->ihl * 4); 623 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport); 624 /* Put back, the original values. */ 625 skb->network_header = saveip; 626 skb->transport_header = savesctp; 627 if (!sk) { 628 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 629 return -ENOENT; 630 } 631 632 sctp_v4_err_handle(transport, skb, type, code, info); 633 sctp_err_finish(sk, transport); 634 635 return 0; 636} 637 638int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb) 639{ 640 struct net *net = dev_net(skb->dev); 641 struct sctp_association *asoc; 642 struct sctp_transport *t; 643 struct icmphdr *hdr; 644 __u32 info = 0; 645 646 skb->transport_header += sizeof(struct udphdr); 647 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &t); 648 if (!sk) { 649 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 650 return -ENOENT; 651 } 652 653 skb->transport_header -= sizeof(struct udphdr); 654 hdr = (struct icmphdr *)(skb_network_header(skb) - sizeof(struct icmphdr)); 655 if (hdr->type == ICMP_REDIRECT) { 656 /* can't be handled without outer iphdr known, leave it to udp_err */ 657 sctp_err_finish(sk, t); 658 return 0; 659 } 660 if (hdr->type == ICMP_DEST_UNREACH && hdr->code == ICMP_FRAG_NEEDED) 661 info = ntohs(hdr->un.frag.mtu); 662 sctp_v4_err_handle(t, skb, hdr->type, hdr->code, info); 663 664 sctp_err_finish(sk, t); 665 return 1; 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 struct sctp_chunkhdr *ch, _ch; 683 int ch_end, offset = 0; 684 685 /* Scan through all the chunks in the packet. */ 686 do { 687 /* Make sure we have at least the header there */ 688 if (offset + sizeof(_ch) > skb->len) 689 break; 690 691 ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch); 692 693 /* Break out if chunk length is less then minimal. */ 694 if (!ch || ntohs(ch->length) < sizeof(_ch)) 695 break; 696 697 ch_end = offset + SCTP_PAD4(ntohs(ch->length)); 698 if (ch_end > skb->len) 699 break; 700 701 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the 702 * receiver MUST silently discard the OOTB packet and take no 703 * further action. 704 */ 705 if (SCTP_CID_ABORT == ch->type) 706 goto discard; 707 708 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE 709 * chunk, the receiver should silently discard the packet 710 * and take no further action. 711 */ 712 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) 713 goto discard; 714 715 /* RFC 4460, 2.11.2 716 * This will discard packets with INIT chunk bundled as 717 * subsequent chunks in the packet. When INIT is first, 718 * the normal INIT processing will discard the chunk. 719 */ 720 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) 721 goto discard; 722 723 offset = ch_end; 724 } while (ch_end < skb->len); 725 726 return 0; 727 728discard: 729 return 1; 730} 731 732/* Insert endpoint into the hash table. */ 733static int __sctp_hash_endpoint(struct sctp_endpoint *ep) 734{ 735 struct sock *sk = ep->base.sk; 736 struct net *net = sock_net(sk); 737 struct sctp_hashbucket *head; 738 739 ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port); 740 head = &sctp_ep_hashtable[ep->hashent]; 741 742 if (sk->sk_reuseport) { 743 bool any = sctp_is_ep_boundall(sk); 744 struct sctp_endpoint *ep2; 745 struct list_head *list; 746 int cnt = 0, err = 1; 747 748 list_for_each(list, &ep->base.bind_addr.address_list) 749 cnt++; 750 751 sctp_for_each_hentry(ep2, &head->chain) { 752 struct sock *sk2 = ep2->base.sk; 753 754 if (!net_eq(sock_net(sk2), net) || sk2 == sk || 755 !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) || 756 !sk2->sk_reuseport) 757 continue; 758 759 err = sctp_bind_addrs_check(sctp_sk(sk2), 760 sctp_sk(sk), cnt); 761 if (!err) { 762 err = reuseport_add_sock(sk, sk2, any); 763 if (err) 764 return err; 765 break; 766 } else if (err < 0) { 767 return err; 768 } 769 } 770 771 if (err) { 772 err = reuseport_alloc(sk, any); 773 if (err) 774 return err; 775 } 776 } 777 778 write_lock(&head->lock); 779 hlist_add_head(&ep->node, &head->chain); 780 write_unlock(&head->lock); 781 return 0; 782} 783 784/* Add an endpoint to the hash. Local BH-safe. */ 785int sctp_hash_endpoint(struct sctp_endpoint *ep) 786{ 787 int err; 788 789 local_bh_disable(); 790 err = __sctp_hash_endpoint(ep); 791 local_bh_enable(); 792 793 return err; 794} 795 796/* Remove endpoint from the hash table. */ 797static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) 798{ 799 struct sock *sk = ep->base.sk; 800 struct sctp_hashbucket *head; 801 802 ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port); 803 804 head = &sctp_ep_hashtable[ep->hashent]; 805 806 if (rcu_access_pointer(sk->sk_reuseport_cb)) 807 reuseport_detach_sock(sk); 808 809 write_lock(&head->lock); 810 hlist_del_init(&ep->node); 811 write_unlock(&head->lock); 812} 813 814/* Remove endpoint from the hash. Local BH-safe. */ 815void sctp_unhash_endpoint(struct sctp_endpoint *ep) 816{ 817 local_bh_disable(); 818 __sctp_unhash_endpoint(ep); 819 local_bh_enable(); 820} 821 822static inline __u32 sctp_hashfn(const struct net *net, __be16 lport, 823 const union sctp_addr *paddr, __u32 seed) 824{ 825 __u32 addr; 826 827 if (paddr->sa.sa_family == AF_INET6) 828 addr = jhash(&paddr->v6.sin6_addr, 16, seed); 829 else 830 addr = (__force __u32)paddr->v4.sin_addr.s_addr; 831 832 return jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 | 833 (__force __u32)lport, net_hash_mix(net), seed); 834} 835 836/* Look up an endpoint. */ 837static struct sctp_endpoint *__sctp_rcv_lookup_endpoint( 838 struct net *net, struct sk_buff *skb, 839 const union sctp_addr *laddr, 840 const union sctp_addr *paddr, 841 int dif, int sdif) 842{ 843 struct sctp_hashbucket *head; 844 struct sctp_endpoint *ep; 845 struct sock *sk; 846 __be16 lport; 847 int hash; 848 849 lport = laddr->v4.sin_port; 850 hash = sctp_ep_hashfn(net, ntohs(lport)); 851 head = &sctp_ep_hashtable[hash]; 852 read_lock(&head->lock); 853 sctp_for_each_hentry(ep, &head->chain) { 854 if (sctp_endpoint_is_match(ep, net, laddr, dif, sdif)) 855 goto hit; 856 } 857 858 ep = sctp_sk(net->sctp.ctl_sock)->ep; 859 860hit: 861 sk = ep->base.sk; 862 if (sk->sk_reuseport) { 863 __u32 phash = sctp_hashfn(net, lport, paddr, 0); 864 865 sk = reuseport_select_sock(sk, phash, skb, 866 sizeof(struct sctphdr)); 867 if (sk) 868 ep = sctp_sk(sk)->ep; 869 } 870 sctp_endpoint_hold(ep); 871 read_unlock(&head->lock); 872 return ep; 873} 874 875/* rhashtable for transport */ 876struct sctp_hash_cmp_arg { 877 const union sctp_addr *paddr; 878 const struct net *net; 879 __be16 lport; 880}; 881 882static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, 883 const void *ptr) 884{ 885 struct sctp_transport *t = (struct sctp_transport *)ptr; 886 const struct sctp_hash_cmp_arg *x = arg->key; 887 int err = 1; 888 889 if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) 890 return err; 891 if (!sctp_transport_hold(t)) 892 return err; 893 894 if (!net_eq(t->asoc->base.net, x->net)) 895 goto out; 896 if (x->lport != htons(t->asoc->base.bind_addr.port)) 897 goto out; 898 899 err = 0; 900out: 901 sctp_transport_put(t); 902 return err; 903} 904 905static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed) 906{ 907 const struct sctp_transport *t = data; 908 909 return sctp_hashfn(t->asoc->base.net, 910 htons(t->asoc->base.bind_addr.port), 911 &t->ipaddr, seed); 912} 913 914static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed) 915{ 916 const struct sctp_hash_cmp_arg *x = data; 917 918 return sctp_hashfn(x->net, x->lport, x->paddr, seed); 919} 920 921static const struct rhashtable_params sctp_hash_params = { 922 .head_offset = offsetof(struct sctp_transport, node), 923 .hashfn = sctp_hash_key, 924 .obj_hashfn = sctp_hash_obj, 925 .obj_cmpfn = sctp_hash_cmp, 926 .automatic_shrinking = true, 927}; 928 929int sctp_transport_hashtable_init(void) 930{ 931 return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params); 932} 933 934void sctp_transport_hashtable_destroy(void) 935{ 936 rhltable_destroy(&sctp_transport_hashtable); 937} 938 939int sctp_hash_transport(struct sctp_transport *t) 940{ 941 struct sctp_transport *transport; 942 struct rhlist_head *tmp, *list; 943 struct sctp_hash_cmp_arg arg; 944 int err; 945 946 if (t->asoc->temp) 947 return 0; 948 949 arg.net = t->asoc->base.net; 950 arg.paddr = &t->ipaddr; 951 arg.lport = htons(t->asoc->base.bind_addr.port); 952 953 rcu_read_lock(); 954 list = rhltable_lookup(&sctp_transport_hashtable, &arg, 955 sctp_hash_params); 956 957 rhl_for_each_entry_rcu(transport, tmp, list, node) 958 if (transport->asoc->ep == t->asoc->ep) { 959 rcu_read_unlock(); 960 return -EEXIST; 961 } 962 rcu_read_unlock(); 963 964 err = rhltable_insert_key(&sctp_transport_hashtable, &arg, 965 &t->node, sctp_hash_params); 966 if (err) 967 pr_err_once("insert transport fail, errno %d\n", err); 968 969 return err; 970} 971 972void sctp_unhash_transport(struct sctp_transport *t) 973{ 974 if (t->asoc->temp) 975 return; 976 977 rhltable_remove(&sctp_transport_hashtable, &t->node, 978 sctp_hash_params); 979} 980 981bool sctp_sk_bound_dev_eq(struct net *net, int bound_dev_if, int dif, int sdif) 982{ 983 bool l3mdev_accept = true; 984 985#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 986 l3mdev_accept = !!READ_ONCE(net->sctp.l3mdev_accept); 987#endif 988 return inet_bound_dev_eq(l3mdev_accept, bound_dev_if, dif, sdif); 989} 990 991/* return a transport with holding it */ 992struct sctp_transport *sctp_addrs_lookup_transport( 993 struct net *net, 994 const union sctp_addr *laddr, 995 const union sctp_addr *paddr, 996 int dif, int sdif) 997{ 998 struct rhlist_head *tmp, *list; 999 struct sctp_transport *t; 1000 int bound_dev_if; 1001 struct sctp_hash_cmp_arg arg = { 1002 .paddr = paddr, 1003 .net = net, 1004 .lport = laddr->v4.sin_port, 1005 }; 1006 1007 list = rhltable_lookup(&sctp_transport_hashtable, &arg, 1008 sctp_hash_params); 1009 1010 rhl_for_each_entry_rcu(t, tmp, list, node) { 1011 if (!sctp_transport_hold(t)) 1012 continue; 1013 1014 bound_dev_if = READ_ONCE(t->asoc->base.sk->sk_bound_dev_if); 1015 if (sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) && 1016 sctp_bind_addr_match(&t->asoc->base.bind_addr, 1017 laddr, sctp_sk(t->asoc->base.sk))) 1018 return t; 1019 sctp_transport_put(t); 1020 } 1021 1022 return NULL; 1023} 1024 1025/* return a transport without holding it, as it's only used under sock lock */ 1026struct sctp_transport *sctp_epaddr_lookup_transport( 1027 const struct sctp_endpoint *ep, 1028 const union sctp_addr *paddr) 1029{ 1030 struct rhlist_head *tmp, *list; 1031 struct sctp_transport *t; 1032 struct sctp_hash_cmp_arg arg = { 1033 .paddr = paddr, 1034 .net = ep->base.net, 1035 .lport = htons(ep->base.bind_addr.port), 1036 }; 1037 1038 list = rhltable_lookup(&sctp_transport_hashtable, &arg, 1039 sctp_hash_params); 1040 1041 rhl_for_each_entry_rcu(t, tmp, list, node) 1042 if (ep == t->asoc->ep) 1043 return t; 1044 1045 return NULL; 1046} 1047 1048/* Look up an association. */ 1049static struct sctp_association *__sctp_lookup_association( 1050 struct net *net, 1051 const union sctp_addr *local, 1052 const union sctp_addr *peer, 1053 struct sctp_transport **pt, 1054 int dif, int sdif) 1055{ 1056 struct sctp_transport *t; 1057 struct sctp_association *asoc = NULL; 1058 1059 t = sctp_addrs_lookup_transport(net, local, peer, dif, sdif); 1060 if (!t) 1061 goto out; 1062 1063 asoc = t->asoc; 1064 *pt = t; 1065 1066out: 1067 return asoc; 1068} 1069 1070/* Look up an association. protected by RCU read lock */ 1071static 1072struct sctp_association *sctp_lookup_association(struct net *net, 1073 const union sctp_addr *laddr, 1074 const union sctp_addr *paddr, 1075 struct sctp_transport **transportp, 1076 int dif, int sdif) 1077{ 1078 struct sctp_association *asoc; 1079 1080 rcu_read_lock(); 1081 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); 1082 rcu_read_unlock(); 1083 1084 return asoc; 1085} 1086 1087/* Is there an association matching the given local and peer addresses? */ 1088bool sctp_has_association(struct net *net, 1089 const union sctp_addr *laddr, 1090 const union sctp_addr *paddr, 1091 int dif, int sdif) 1092{ 1093 struct sctp_transport *transport; 1094 1095 if (sctp_lookup_association(net, laddr, paddr, &transport, dif, sdif)) { 1096 sctp_transport_put(transport); 1097 return true; 1098 } 1099 1100 return false; 1101} 1102 1103/* 1104 * SCTP Implementors Guide, 2.18 Handling of address 1105 * parameters within the INIT or INIT-ACK. 1106 * 1107 * D) When searching for a matching TCB upon reception of an INIT 1108 * or INIT-ACK chunk the receiver SHOULD use not only the 1109 * source address of the packet (containing the INIT or 1110 * INIT-ACK) but the receiver SHOULD also use all valid 1111 * address parameters contained within the chunk. 1112 * 1113 * 2.18.3 Solution description 1114 * 1115 * This new text clearly specifies to an implementor the need 1116 * to look within the INIT or INIT-ACK. Any implementation that 1117 * does not do this, may not be able to establish associations 1118 * in certain circumstances. 1119 * 1120 */ 1121static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, 1122 struct sk_buff *skb, 1123 const union sctp_addr *laddr, struct sctp_transport **transportp, 1124 int dif, int sdif) 1125{ 1126 struct sctp_association *asoc; 1127 union sctp_addr addr; 1128 union sctp_addr *paddr = &addr; 1129 struct sctphdr *sh = sctp_hdr(skb); 1130 union sctp_params params; 1131 struct sctp_init_chunk *init; 1132 struct sctp_af *af; 1133 1134 /* 1135 * This code will NOT touch anything inside the chunk--it is 1136 * strictly READ-ONLY. 1137 * 1138 * RFC 2960 3 SCTP packet Format 1139 * 1140 * Multiple chunks can be bundled into one SCTP packet up to 1141 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN 1142 * COMPLETE chunks. These chunks MUST NOT be bundled with any 1143 * other chunk in a packet. See Section 6.10 for more details 1144 * on chunk bundling. 1145 */ 1146 1147 /* Find the start of the TLVs and the end of the chunk. This is 1148 * the region we search for address parameters. 1149 */ 1150 init = (struct sctp_init_chunk *)skb->data; 1151 1152 /* Walk the parameters looking for embedded addresses. */ 1153 sctp_walk_params(params, init) { 1154 1155 /* Note: Ignoring hostname addresses. */ 1156 af = sctp_get_af_specific(param_type2af(params.p->type)); 1157 if (!af) 1158 continue; 1159 1160 if (!af->from_addr_param(paddr, params.addr, sh->source, 0)) 1161 continue; 1162 1163 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); 1164 if (asoc) 1165 return asoc; 1166 } 1167 1168 return NULL; 1169} 1170 1171/* ADD-IP, Section 5.2 1172 * When an endpoint receives an ASCONF Chunk from the remote peer 1173 * special procedures may be needed to identify the association the 1174 * ASCONF Chunk is associated with. To properly find the association 1175 * the following procedures SHOULD be followed: 1176 * 1177 * D2) If the association is not found, use the address found in the 1178 * Address Parameter TLV combined with the port number found in the 1179 * SCTP common header. If found proceed to rule D4. 1180 * 1181 * D2-ext) If more than one ASCONF Chunks are packed together, use the 1182 * address found in the ASCONF Address Parameter TLV of each of the 1183 * subsequent ASCONF Chunks. If found, proceed to rule D4. 1184 */ 1185static struct sctp_association *__sctp_rcv_asconf_lookup( 1186 struct net *net, 1187 struct sctp_chunkhdr *ch, 1188 const union sctp_addr *laddr, 1189 __be16 peer_port, 1190 struct sctp_transport **transportp, 1191 int dif, int sdif) 1192{ 1193 struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch; 1194 struct sctp_af *af; 1195 union sctp_addr_param *param; 1196 union sctp_addr paddr; 1197 1198 if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr)) 1199 return NULL; 1200 1201 /* Skip over the ADDIP header and find the Address parameter */ 1202 param = (union sctp_addr_param *)(asconf + 1); 1203 1204 af = sctp_get_af_specific(param_type2af(param->p.type)); 1205 if (unlikely(!af)) 1206 return NULL; 1207 1208 if (!af->from_addr_param(&paddr, param, peer_port, 0)) 1209 return NULL; 1210 1211 return __sctp_lookup_association(net, laddr, &paddr, transportp, dif, sdif); 1212} 1213 1214 1215/* SCTP-AUTH, Section 6.3: 1216* If the receiver does not find a STCB for a packet containing an AUTH 1217* chunk as the first chunk and not a COOKIE-ECHO chunk as the second 1218* chunk, it MUST use the chunks after the AUTH chunk to look up an existing 1219* association. 1220* 1221* This means that any chunks that can help us identify the association need 1222* to be looked at to find this association. 1223*/ 1224static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, 1225 struct sk_buff *skb, 1226 const union sctp_addr *laddr, 1227 struct sctp_transport **transportp, 1228 int dif, int sdif) 1229{ 1230 struct sctp_association *asoc = NULL; 1231 struct sctp_chunkhdr *ch; 1232 int have_auth = 0; 1233 unsigned int chunk_num = 1; 1234 __u8 *ch_end; 1235 1236 /* Walk through the chunks looking for AUTH or ASCONF chunks 1237 * to help us find the association. 1238 */ 1239 ch = (struct sctp_chunkhdr *)skb->data; 1240 do { 1241 /* Break out if chunk length is less then minimal. */ 1242 if (ntohs(ch->length) < sizeof(*ch)) 1243 break; 1244 1245 ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); 1246 if (ch_end > skb_tail_pointer(skb)) 1247 break; 1248 1249 switch (ch->type) { 1250 case SCTP_CID_AUTH: 1251 have_auth = chunk_num; 1252 break; 1253 1254 case SCTP_CID_COOKIE_ECHO: 1255 /* If a packet arrives containing an AUTH chunk as 1256 * a first chunk, a COOKIE-ECHO chunk as the second 1257 * chunk, and possibly more chunks after them, and 1258 * the receiver does not have an STCB for that 1259 * packet, then authentication is based on 1260 * the contents of the COOKIE- ECHO chunk. 1261 */ 1262 if (have_auth == 1 && chunk_num == 2) 1263 return NULL; 1264 break; 1265 1266 case SCTP_CID_ASCONF: 1267 if (have_auth || net->sctp.addip_noauth) 1268 asoc = __sctp_rcv_asconf_lookup( 1269 net, ch, laddr, 1270 sctp_hdr(skb)->source, 1271 transportp, dif, sdif); 1272 break; 1273 default: 1274 break; 1275 } 1276 1277 if (asoc) 1278 break; 1279 1280 ch = (struct sctp_chunkhdr *)ch_end; 1281 chunk_num++; 1282 } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb)); 1283 1284 return asoc; 1285} 1286 1287/* 1288 * There are circumstances when we need to look inside the SCTP packet 1289 * for information to help us find the association. Examples 1290 * include looking inside of INIT/INIT-ACK chunks or after the AUTH 1291 * chunks. 1292 */ 1293static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, 1294 struct sk_buff *skb, 1295 const union sctp_addr *laddr, 1296 struct sctp_transport **transportp, 1297 int dif, int sdif) 1298{ 1299 struct sctp_chunkhdr *ch; 1300 1301 /* We do not allow GSO frames here as we need to linearize and 1302 * then cannot guarantee frame boundaries. This shouldn't be an 1303 * issue as packets hitting this are mostly INIT or INIT-ACK and 1304 * those cannot be on GSO-style anyway. 1305 */ 1306 if (skb_is_gso(skb) && skb_is_gso_sctp(skb)) 1307 return NULL; 1308 1309 ch = (struct sctp_chunkhdr *)skb->data; 1310 1311 /* The code below will attempt to walk the chunk and extract 1312 * parameter information. Before we do that, we need to verify 1313 * that the chunk length doesn't cause overflow. Otherwise, we'll 1314 * walk off the end. 1315 */ 1316 if (SCTP_PAD4(ntohs(ch->length)) > skb->len) 1317 return NULL; 1318 1319 /* If this is INIT/INIT-ACK look inside the chunk too. */ 1320 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) 1321 return __sctp_rcv_init_lookup(net, skb, laddr, transportp, dif, sdif); 1322 1323 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp, dif, sdif); 1324} 1325 1326/* Lookup an association for an inbound skb. */ 1327static struct sctp_association *__sctp_rcv_lookup(struct net *net, 1328 struct sk_buff *skb, 1329 const union sctp_addr *paddr, 1330 const union sctp_addr *laddr, 1331 struct sctp_transport **transportp, 1332 int dif, int sdif) 1333{ 1334 struct sctp_association *asoc; 1335 1336 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); 1337 if (asoc) 1338 goto out; 1339 1340 /* Further lookup for INIT/INIT-ACK packets. 1341 * SCTP Implementors Guide, 2.18 Handling of address 1342 * parameters within the INIT or INIT-ACK. 1343 */ 1344 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp, dif, sdif); 1345 if (asoc) 1346 goto out; 1347 1348 if (paddr->sa.sa_family == AF_INET) 1349 pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n", 1350 &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port), 1351 &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port)); 1352 else 1353 pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n", 1354 &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port), 1355 &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port)); 1356 1357out: 1358 return asoc; 1359} 1360