| 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. */ |
| 48 | static int sctp_rcv_ootb(struct sk_buff *); |
| 49 | static 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); |
| 55 | static 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); |
| 60 | static 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 | |
| 67 | static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); |
| 68 | |
| 69 | |
| 70 | /* Calculate the SCTP checksum of an SCTP packet. */ |
| 71 | static 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 | */ |
| 88 | int 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 | |
| 256 | discard_it: |
| 257 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); |
| 258 | kfree_skb(skb); |
| 259 | return 0; |
| 260 | |
| 261 | discard_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 | */ |
| 276 | int 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 | |
| 335 | done: |
| 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 | |
| 347 | static 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. */ |
| 372 | void 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 | |
| 408 | void 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 | */ |
| 431 | void 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 (timer_delete(&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. */ |
| 460 | struct 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 | |
| 535 | out: |
| 536 | sctp_transport_put(transport); |
| 537 | return NULL; |
| 538 | } |
| 539 | |
| 540 | /* Common cleanup code for icmp/icmpv6 error handler. */ |
| 541 | void 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 | |
| 548 | static 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 | */ |
| 607 | int 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 | |
| 638 | int 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 | */ |
| 680 | static 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 | |
| 728 | discard: |
| 729 | return 1; |
| 730 | } |
| 731 | |
| 732 | /* Insert endpoint into the hash table. */ |
| 733 | static 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 | int err = 0; |
| 739 | |
| 740 | ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port); |
| 741 | head = &sctp_ep_hashtable[ep->hashent]; |
| 742 | |
| 743 | write_lock(&head->lock); |
| 744 | if (sk->sk_reuseport) { |
| 745 | bool any = sctp_is_ep_boundall(sk); |
| 746 | struct sctp_endpoint *ep2; |
| 747 | struct list_head *list; |
| 748 | int cnt = 0; |
| 749 | |
| 750 | err = 1; |
| 751 | |
| 752 | list_for_each(list, &ep->base.bind_addr.address_list) |
| 753 | cnt++; |
| 754 | |
| 755 | sctp_for_each_hentry(ep2, &head->chain) { |
| 756 | struct sock *sk2 = ep2->base.sk; |
| 757 | |
| 758 | if (!net_eq(sock_net(sk2), net) || sk2 == sk || |
| 759 | !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) || |
| 760 | !sk2->sk_reuseport) |
| 761 | continue; |
| 762 | |
| 763 | err = sctp_bind_addrs_check(sctp_sk(sk2), |
| 764 | sctp_sk(sk), cnt); |
| 765 | if (!err) { |
| 766 | err = reuseport_add_sock(sk, sk2, any); |
| 767 | if (err) |
| 768 | goto out; |
| 769 | break; |
| 770 | } else if (err < 0) { |
| 771 | goto out; |
| 772 | } |
| 773 | } |
| 774 | |
| 775 | if (err) { |
| 776 | err = reuseport_alloc(sk, any); |
| 777 | if (err) |
| 778 | goto out; |
| 779 | } |
| 780 | } |
| 781 | |
| 782 | hlist_add_head(&ep->node, &head->chain); |
| 783 | out: |
| 784 | write_unlock(&head->lock); |
| 785 | return err; |
| 786 | } |
| 787 | |
| 788 | /* Add an endpoint to the hash. Local BH-safe. */ |
| 789 | int sctp_hash_endpoint(struct sctp_endpoint *ep) |
| 790 | { |
| 791 | int err; |
| 792 | |
| 793 | local_bh_disable(); |
| 794 | err = __sctp_hash_endpoint(ep); |
| 795 | local_bh_enable(); |
| 796 | |
| 797 | return err; |
| 798 | } |
| 799 | |
| 800 | /* Remove endpoint from the hash table. */ |
| 801 | static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) |
| 802 | { |
| 803 | struct sock *sk = ep->base.sk; |
| 804 | struct sctp_hashbucket *head; |
| 805 | |
| 806 | ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port); |
| 807 | |
| 808 | head = &sctp_ep_hashtable[ep->hashent]; |
| 809 | |
| 810 | write_lock(&head->lock); |
| 811 | if (rcu_access_pointer(sk->sk_reuseport_cb)) |
| 812 | reuseport_detach_sock(sk); |
| 813 | hlist_del_init(&ep->node); |
| 814 | write_unlock(&head->lock); |
| 815 | } |
| 816 | |
| 817 | /* Remove endpoint from the hash. Local BH-safe. */ |
| 818 | void sctp_unhash_endpoint(struct sctp_endpoint *ep) |
| 819 | { |
| 820 | local_bh_disable(); |
| 821 | __sctp_unhash_endpoint(ep); |
| 822 | local_bh_enable(); |
| 823 | } |
| 824 | |
| 825 | static inline __u32 sctp_hashfn(const struct net *net, __be16 lport, |
| 826 | const union sctp_addr *paddr, __u32 seed) |
| 827 | { |
| 828 | __u32 addr; |
| 829 | |
| 830 | if (paddr->sa.sa_family == AF_INET6) |
| 831 | addr = jhash(&paddr->v6.sin6_addr, 16, seed); |
| 832 | else |
| 833 | addr = (__force __u32)paddr->v4.sin_addr.s_addr; |
| 834 | |
| 835 | return jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 | |
| 836 | (__force __u32)lport, net_hash_mix(net), seed); |
| 837 | } |
| 838 | |
| 839 | /* Look up an endpoint. */ |
| 840 | static struct sctp_endpoint *__sctp_rcv_lookup_endpoint( |
| 841 | struct net *net, struct sk_buff *skb, |
| 842 | const union sctp_addr *laddr, |
| 843 | const union sctp_addr *paddr, |
| 844 | int dif, int sdif) |
| 845 | { |
| 846 | struct sctp_hashbucket *head; |
| 847 | struct sctp_endpoint *ep; |
| 848 | struct sock *sk; |
| 849 | __be16 lport; |
| 850 | int hash; |
| 851 | |
| 852 | lport = laddr->v4.sin_port; |
| 853 | hash = sctp_ep_hashfn(net, ntohs(lport)); |
| 854 | head = &sctp_ep_hashtable[hash]; |
| 855 | read_lock(&head->lock); |
| 856 | sctp_for_each_hentry(ep, &head->chain) { |
| 857 | if (sctp_endpoint_is_match(ep, net, laddr, dif, sdif)) |
| 858 | goto hit; |
| 859 | } |
| 860 | |
| 861 | ep = sctp_sk(net->sctp.ctl_sock)->ep; |
| 862 | |
| 863 | hit: |
| 864 | sk = ep->base.sk; |
| 865 | if (sk->sk_reuseport) { |
| 866 | __u32 phash = sctp_hashfn(net, lport, paddr, 0); |
| 867 | |
| 868 | sk = reuseport_select_sock(sk, phash, skb, |
| 869 | sizeof(struct sctphdr)); |
| 870 | if (sk) |
| 871 | ep = sctp_sk(sk)->ep; |
| 872 | } |
| 873 | sctp_endpoint_hold(ep); |
| 874 | read_unlock(&head->lock); |
| 875 | return ep; |
| 876 | } |
| 877 | |
| 878 | /* rhashtable for transport */ |
| 879 | struct sctp_hash_cmp_arg { |
| 880 | const union sctp_addr *paddr; |
| 881 | const struct net *net; |
| 882 | __be16 lport; |
| 883 | }; |
| 884 | |
| 885 | static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, |
| 886 | const void *ptr) |
| 887 | { |
| 888 | struct sctp_transport *t = (struct sctp_transport *)ptr; |
| 889 | const struct sctp_hash_cmp_arg *x = arg->key; |
| 890 | int err = 1; |
| 891 | |
| 892 | if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) |
| 893 | return err; |
| 894 | if (!sctp_transport_hold(t)) |
| 895 | return err; |
| 896 | |
| 897 | if (!net_eq(t->asoc->base.net, x->net)) |
| 898 | goto out; |
| 899 | if (x->lport != htons(t->asoc->base.bind_addr.port)) |
| 900 | goto out; |
| 901 | |
| 902 | err = 0; |
| 903 | out: |
| 904 | sctp_transport_put(t); |
| 905 | return err; |
| 906 | } |
| 907 | |
| 908 | static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed) |
| 909 | { |
| 910 | const struct sctp_transport *t = data; |
| 911 | |
| 912 | return sctp_hashfn(t->asoc->base.net, |
| 913 | htons(t->asoc->base.bind_addr.port), |
| 914 | &t->ipaddr, seed); |
| 915 | } |
| 916 | |
| 917 | static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed) |
| 918 | { |
| 919 | const struct sctp_hash_cmp_arg *x = data; |
| 920 | |
| 921 | return sctp_hashfn(x->net, x->lport, x->paddr, seed); |
| 922 | } |
| 923 | |
| 924 | static const struct rhashtable_params sctp_hash_params = { |
| 925 | .head_offset = offsetof(struct sctp_transport, node), |
| 926 | .hashfn = sctp_hash_key, |
| 927 | .obj_hashfn = sctp_hash_obj, |
| 928 | .obj_cmpfn = sctp_hash_cmp, |
| 929 | .automatic_shrinking = true, |
| 930 | }; |
| 931 | |
| 932 | int sctp_transport_hashtable_init(void) |
| 933 | { |
| 934 | return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params); |
| 935 | } |
| 936 | |
| 937 | void sctp_transport_hashtable_destroy(void) |
| 938 | { |
| 939 | rhltable_destroy(&sctp_transport_hashtable); |
| 940 | } |
| 941 | |
| 942 | int sctp_hash_transport(struct sctp_transport *t) |
| 943 | { |
| 944 | struct sctp_transport *transport; |
| 945 | struct rhlist_head *tmp, *list; |
| 946 | struct sctp_hash_cmp_arg arg; |
| 947 | int err; |
| 948 | |
| 949 | if (t->asoc->temp) |
| 950 | return 0; |
| 951 | |
| 952 | arg.net = t->asoc->base.net; |
| 953 | arg.paddr = &t->ipaddr; |
| 954 | arg.lport = htons(t->asoc->base.bind_addr.port); |
| 955 | |
| 956 | rcu_read_lock(); |
| 957 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, |
| 958 | sctp_hash_params); |
| 959 | |
| 960 | rhl_for_each_entry_rcu(transport, tmp, list, node) |
| 961 | if (transport->asoc->ep == t->asoc->ep) { |
| 962 | rcu_read_unlock(); |
| 963 | return -EEXIST; |
| 964 | } |
| 965 | rcu_read_unlock(); |
| 966 | |
| 967 | err = rhltable_insert_key(&sctp_transport_hashtable, &arg, |
| 968 | &t->node, sctp_hash_params); |
| 969 | if (err) |
| 970 | pr_err_once("insert transport fail, errno %d\n", err); |
| 971 | |
| 972 | return err; |
| 973 | } |
| 974 | |
| 975 | void sctp_unhash_transport(struct sctp_transport *t) |
| 976 | { |
| 977 | if (t->asoc->temp) |
| 978 | return; |
| 979 | |
| 980 | rhltable_remove(&sctp_transport_hashtable, &t->node, |
| 981 | sctp_hash_params); |
| 982 | } |
| 983 | |
| 984 | bool sctp_sk_bound_dev_eq(struct net *net, int bound_dev_if, int dif, int sdif) |
| 985 | { |
| 986 | bool l3mdev_accept = true; |
| 987 | |
| 988 | #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) |
| 989 | l3mdev_accept = !!READ_ONCE(net->sctp.l3mdev_accept); |
| 990 | #endif |
| 991 | return inet_bound_dev_eq(l3mdev_accept, bound_dev_if, dif, sdif); |
| 992 | } |
| 993 | |
| 994 | /* return a transport with holding it */ |
| 995 | struct sctp_transport *sctp_addrs_lookup_transport( |
| 996 | struct net *net, |
| 997 | const union sctp_addr *laddr, |
| 998 | const union sctp_addr *paddr, |
| 999 | int dif, int sdif) |
| 1000 | { |
| 1001 | struct rhlist_head *tmp, *list; |
| 1002 | struct sctp_transport *t; |
| 1003 | int bound_dev_if; |
| 1004 | struct sctp_hash_cmp_arg arg = { |
| 1005 | .paddr = paddr, |
| 1006 | .net = net, |
| 1007 | .lport = laddr->v4.sin_port, |
| 1008 | }; |
| 1009 | |
| 1010 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, |
| 1011 | sctp_hash_params); |
| 1012 | |
| 1013 | rhl_for_each_entry_rcu(t, tmp, list, node) { |
| 1014 | if (!sctp_transport_hold(t)) |
| 1015 | continue; |
| 1016 | |
| 1017 | bound_dev_if = READ_ONCE(t->asoc->base.sk->sk_bound_dev_if); |
| 1018 | if (sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) && |
| 1019 | sctp_bind_addr_match(&t->asoc->base.bind_addr, |
| 1020 | laddr, sctp_sk(t->asoc->base.sk))) |
| 1021 | return t; |
| 1022 | sctp_transport_put(t); |
| 1023 | } |
| 1024 | |
| 1025 | return NULL; |
| 1026 | } |
| 1027 | |
| 1028 | /* return a transport without holding it, as it's only used under sock lock */ |
| 1029 | struct sctp_transport *sctp_epaddr_lookup_transport( |
| 1030 | const struct sctp_endpoint *ep, |
| 1031 | const union sctp_addr *paddr) |
| 1032 | { |
| 1033 | struct rhlist_head *tmp, *list; |
| 1034 | struct sctp_transport *t; |
| 1035 | struct sctp_hash_cmp_arg arg = { |
| 1036 | .paddr = paddr, |
| 1037 | .net = ep->base.net, |
| 1038 | .lport = htons(ep->base.bind_addr.port), |
| 1039 | }; |
| 1040 | |
| 1041 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, |
| 1042 | sctp_hash_params); |
| 1043 | |
| 1044 | rhl_for_each_entry_rcu(t, tmp, list, node) |
| 1045 | if (ep == t->asoc->ep) |
| 1046 | return t; |
| 1047 | |
| 1048 | return NULL; |
| 1049 | } |
| 1050 | |
| 1051 | /* Look up an association. */ |
| 1052 | static struct sctp_association *__sctp_lookup_association( |
| 1053 | struct net *net, |
| 1054 | const union sctp_addr *local, |
| 1055 | const union sctp_addr *peer, |
| 1056 | struct sctp_transport **pt, |
| 1057 | int dif, int sdif) |
| 1058 | { |
| 1059 | struct sctp_transport *t; |
| 1060 | struct sctp_association *asoc = NULL; |
| 1061 | |
| 1062 | t = sctp_addrs_lookup_transport(net, local, peer, dif, sdif); |
| 1063 | if (!t) |
| 1064 | goto out; |
| 1065 | |
| 1066 | asoc = t->asoc; |
| 1067 | *pt = t; |
| 1068 | |
| 1069 | out: |
| 1070 | return asoc; |
| 1071 | } |
| 1072 | |
| 1073 | /* Look up an association. protected by RCU read lock */ |
| 1074 | static |
| 1075 | struct sctp_association *sctp_lookup_association(struct net *net, |
| 1076 | const union sctp_addr *laddr, |
| 1077 | const union sctp_addr *paddr, |
| 1078 | struct sctp_transport **transportp, |
| 1079 | int dif, int sdif) |
| 1080 | { |
| 1081 | struct sctp_association *asoc; |
| 1082 | |
| 1083 | rcu_read_lock(); |
| 1084 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); |
| 1085 | rcu_read_unlock(); |
| 1086 | |
| 1087 | return asoc; |
| 1088 | } |
| 1089 | |
| 1090 | /* Is there an association matching the given local and peer addresses? */ |
| 1091 | bool sctp_has_association(struct net *net, |
| 1092 | const union sctp_addr *laddr, |
| 1093 | const union sctp_addr *paddr, |
| 1094 | int dif, int sdif) |
| 1095 | { |
| 1096 | struct sctp_transport *transport; |
| 1097 | |
| 1098 | if (sctp_lookup_association(net, laddr, paddr, &transport, dif, sdif)) { |
| 1099 | sctp_transport_put(transport); |
| 1100 | return true; |
| 1101 | } |
| 1102 | |
| 1103 | return false; |
| 1104 | } |
| 1105 | |
| 1106 | /* |
| 1107 | * SCTP Implementors Guide, 2.18 Handling of address |
| 1108 | * parameters within the INIT or INIT-ACK. |
| 1109 | * |
| 1110 | * D) When searching for a matching TCB upon reception of an INIT |
| 1111 | * or INIT-ACK chunk the receiver SHOULD use not only the |
| 1112 | * source address of the packet (containing the INIT or |
| 1113 | * INIT-ACK) but the receiver SHOULD also use all valid |
| 1114 | * address parameters contained within the chunk. |
| 1115 | * |
| 1116 | * 2.18.3 Solution description |
| 1117 | * |
| 1118 | * This new text clearly specifies to an implementor the need |
| 1119 | * to look within the INIT or INIT-ACK. Any implementation that |
| 1120 | * does not do this, may not be able to establish associations |
| 1121 | * in certain circumstances. |
| 1122 | * |
| 1123 | */ |
| 1124 | static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, |
| 1125 | struct sk_buff *skb, |
| 1126 | const union sctp_addr *laddr, struct sctp_transport **transportp, |
| 1127 | int dif, int sdif) |
| 1128 | { |
| 1129 | struct sctp_association *asoc; |
| 1130 | union sctp_addr addr; |
| 1131 | union sctp_addr *paddr = &addr; |
| 1132 | struct sctphdr *sh = sctp_hdr(skb); |
| 1133 | union sctp_params params; |
| 1134 | struct sctp_init_chunk *init; |
| 1135 | struct sctp_af *af; |
| 1136 | |
| 1137 | /* |
| 1138 | * This code will NOT touch anything inside the chunk--it is |
| 1139 | * strictly READ-ONLY. |
| 1140 | * |
| 1141 | * RFC 2960 3 SCTP packet Format |
| 1142 | * |
| 1143 | * Multiple chunks can be bundled into one SCTP packet up to |
| 1144 | * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN |
| 1145 | * COMPLETE chunks. These chunks MUST NOT be bundled with any |
| 1146 | * other chunk in a packet. See Section 6.10 for more details |
| 1147 | * on chunk bundling. |
| 1148 | */ |
| 1149 | |
| 1150 | /* Find the start of the TLVs and the end of the chunk. This is |
| 1151 | * the region we search for address parameters. |
| 1152 | */ |
| 1153 | init = (struct sctp_init_chunk *)skb->data; |
| 1154 | |
| 1155 | /* Walk the parameters looking for embedded addresses. */ |
| 1156 | sctp_walk_params(params, init) { |
| 1157 | |
| 1158 | /* Note: Ignoring hostname addresses. */ |
| 1159 | af = sctp_get_af_specific(param_type2af(params.p->type)); |
| 1160 | if (!af) |
| 1161 | continue; |
| 1162 | |
| 1163 | if (!af->from_addr_param(paddr, params.addr, sh->source, 0)) |
| 1164 | continue; |
| 1165 | |
| 1166 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); |
| 1167 | if (asoc) |
| 1168 | return asoc; |
| 1169 | } |
| 1170 | |
| 1171 | return NULL; |
| 1172 | } |
| 1173 | |
| 1174 | /* ADD-IP, Section 5.2 |
| 1175 | * When an endpoint receives an ASCONF Chunk from the remote peer |
| 1176 | * special procedures may be needed to identify the association the |
| 1177 | * ASCONF Chunk is associated with. To properly find the association |
| 1178 | * the following procedures SHOULD be followed: |
| 1179 | * |
| 1180 | * D2) If the association is not found, use the address found in the |
| 1181 | * Address Parameter TLV combined with the port number found in the |
| 1182 | * SCTP common header. If found proceed to rule D4. |
| 1183 | * |
| 1184 | * D2-ext) If more than one ASCONF Chunks are packed together, use the |
| 1185 | * address found in the ASCONF Address Parameter TLV of each of the |
| 1186 | * subsequent ASCONF Chunks. If found, proceed to rule D4. |
| 1187 | */ |
| 1188 | static struct sctp_association *__sctp_rcv_asconf_lookup( |
| 1189 | struct net *net, |
| 1190 | struct sctp_chunkhdr *ch, |
| 1191 | const union sctp_addr *laddr, |
| 1192 | __be16 peer_port, |
| 1193 | struct sctp_transport **transportp, |
| 1194 | int dif, int sdif) |
| 1195 | { |
| 1196 | struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch; |
| 1197 | struct sctp_af *af; |
| 1198 | union sctp_addr_param *param; |
| 1199 | union sctp_addr paddr; |
| 1200 | |
| 1201 | if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr)) |
| 1202 | return NULL; |
| 1203 | |
| 1204 | /* Skip over the ADDIP header and find the Address parameter */ |
| 1205 | param = (union sctp_addr_param *)(asconf + 1); |
| 1206 | |
| 1207 | af = sctp_get_af_specific(param_type2af(param->p.type)); |
| 1208 | if (unlikely(!af)) |
| 1209 | return NULL; |
| 1210 | |
| 1211 | if (!af->from_addr_param(&paddr, param, peer_port, 0)) |
| 1212 | return NULL; |
| 1213 | |
| 1214 | return __sctp_lookup_association(net, laddr, &paddr, transportp, dif, sdif); |
| 1215 | } |
| 1216 | |
| 1217 | |
| 1218 | /* SCTP-AUTH, Section 6.3: |
| 1219 | * If the receiver does not find a STCB for a packet containing an AUTH |
| 1220 | * chunk as the first chunk and not a COOKIE-ECHO chunk as the second |
| 1221 | * chunk, it MUST use the chunks after the AUTH chunk to look up an existing |
| 1222 | * association. |
| 1223 | * |
| 1224 | * This means that any chunks that can help us identify the association need |
| 1225 | * to be looked at to find this association. |
| 1226 | */ |
| 1227 | static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, |
| 1228 | struct sk_buff *skb, |
| 1229 | const union sctp_addr *laddr, |
| 1230 | struct sctp_transport **transportp, |
| 1231 | int dif, int sdif) |
| 1232 | { |
| 1233 | struct sctp_association *asoc = NULL; |
| 1234 | struct sctp_chunkhdr *ch; |
| 1235 | int have_auth = 0; |
| 1236 | unsigned int chunk_num = 1; |
| 1237 | __u8 *ch_end; |
| 1238 | |
| 1239 | /* Walk through the chunks looking for AUTH or ASCONF chunks |
| 1240 | * to help us find the association. |
| 1241 | */ |
| 1242 | ch = (struct sctp_chunkhdr *)skb->data; |
| 1243 | do { |
| 1244 | /* Break out if chunk length is less then minimal. */ |
| 1245 | if (ntohs(ch->length) < sizeof(*ch)) |
| 1246 | break; |
| 1247 | |
| 1248 | ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); |
| 1249 | if (ch_end > skb_tail_pointer(skb)) |
| 1250 | break; |
| 1251 | |
| 1252 | switch (ch->type) { |
| 1253 | case SCTP_CID_AUTH: |
| 1254 | have_auth = chunk_num; |
| 1255 | break; |
| 1256 | |
| 1257 | case SCTP_CID_COOKIE_ECHO: |
| 1258 | /* If a packet arrives containing an AUTH chunk as |
| 1259 | * a first chunk, a COOKIE-ECHO chunk as the second |
| 1260 | * chunk, and possibly more chunks after them, and |
| 1261 | * the receiver does not have an STCB for that |
| 1262 | * packet, then authentication is based on |
| 1263 | * the contents of the COOKIE- ECHO chunk. |
| 1264 | */ |
| 1265 | if (have_auth == 1 && chunk_num == 2) |
| 1266 | return NULL; |
| 1267 | break; |
| 1268 | |
| 1269 | case SCTP_CID_ASCONF: |
| 1270 | if (have_auth || net->sctp.addip_noauth) |
| 1271 | asoc = __sctp_rcv_asconf_lookup( |
| 1272 | net, ch, laddr, |
| 1273 | sctp_hdr(skb)->source, |
| 1274 | transportp, dif, sdif); |
| 1275 | break; |
| 1276 | default: |
| 1277 | break; |
| 1278 | } |
| 1279 | |
| 1280 | if (asoc) |
| 1281 | break; |
| 1282 | |
| 1283 | ch = (struct sctp_chunkhdr *)ch_end; |
| 1284 | chunk_num++; |
| 1285 | } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb)); |
| 1286 | |
| 1287 | return asoc; |
| 1288 | } |
| 1289 | |
| 1290 | /* |
| 1291 | * There are circumstances when we need to look inside the SCTP packet |
| 1292 | * for information to help us find the association. Examples |
| 1293 | * include looking inside of INIT/INIT-ACK chunks or after the AUTH |
| 1294 | * chunks. |
| 1295 | */ |
| 1296 | static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, |
| 1297 | struct sk_buff *skb, |
| 1298 | const union sctp_addr *laddr, |
| 1299 | struct sctp_transport **transportp, |
| 1300 | int dif, int sdif) |
| 1301 | { |
| 1302 | struct sctp_chunkhdr *ch; |
| 1303 | |
| 1304 | /* We do not allow GSO frames here as we need to linearize and |
| 1305 | * then cannot guarantee frame boundaries. This shouldn't be an |
| 1306 | * issue as packets hitting this are mostly INIT or INIT-ACK and |
| 1307 | * those cannot be on GSO-style anyway. |
| 1308 | */ |
| 1309 | if (skb_is_gso(skb) && skb_is_gso_sctp(skb)) |
| 1310 | return NULL; |
| 1311 | |
| 1312 | ch = (struct sctp_chunkhdr *)skb->data; |
| 1313 | |
| 1314 | /* The code below will attempt to walk the chunk and extract |
| 1315 | * parameter information. Before we do that, we need to verify |
| 1316 | * that the chunk length doesn't cause overflow. Otherwise, we'll |
| 1317 | * walk off the end. |
| 1318 | */ |
| 1319 | if (SCTP_PAD4(ntohs(ch->length)) > skb->len) |
| 1320 | return NULL; |
| 1321 | |
| 1322 | /* If this is INIT/INIT-ACK look inside the chunk too. */ |
| 1323 | if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) |
| 1324 | return __sctp_rcv_init_lookup(net, skb, laddr, transportp, dif, sdif); |
| 1325 | |
| 1326 | return __sctp_rcv_walk_lookup(net, skb, laddr, transportp, dif, sdif); |
| 1327 | } |
| 1328 | |
| 1329 | /* Lookup an association for an inbound skb. */ |
| 1330 | static struct sctp_association *__sctp_rcv_lookup(struct net *net, |
| 1331 | struct sk_buff *skb, |
| 1332 | const union sctp_addr *paddr, |
| 1333 | const union sctp_addr *laddr, |
| 1334 | struct sctp_transport **transportp, |
| 1335 | int dif, int sdif) |
| 1336 | { |
| 1337 | struct sctp_association *asoc; |
| 1338 | |
| 1339 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif); |
| 1340 | if (asoc) |
| 1341 | goto out; |
| 1342 | |
| 1343 | /* Further lookup for INIT/INIT-ACK packets. |
| 1344 | * SCTP Implementors Guide, 2.18 Handling of address |
| 1345 | * parameters within the INIT or INIT-ACK. |
| 1346 | */ |
| 1347 | asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp, dif, sdif); |
| 1348 | if (asoc) |
| 1349 | goto out; |
| 1350 | |
| 1351 | if (paddr->sa.sa_family == AF_INET) |
| 1352 | pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n", |
| 1353 | &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port), |
| 1354 | &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port)); |
| 1355 | else |
| 1356 | pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n", |
| 1357 | &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port), |
| 1358 | &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port)); |
| 1359 | |
| 1360 | out: |
| 1361 | return asoc; |
| 1362 | } |