linux/net/sctp/input.c
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   1/* SCTP kernel implementation
   2 * Copyright (c) 1999-2000 Cisco, Inc.
   3 * Copyright (c) 1999-2001 Motorola, Inc.
   4 * Copyright (c) 2001-2003 International Business Machines, Corp.
   5 * Copyright (c) 2001 Intel Corp.
   6 * Copyright (c) 2001 Nokia, Inc.
   7 * Copyright (c) 2001 La Monte H.P. Yarroll
   8 *
   9 * This file is part of the SCTP kernel implementation
  10 *
  11 * These functions handle all input from the IP layer into SCTP.
  12 *
  13 * This SCTP implementation is free software;
  14 * you can redistribute it and/or modify it under the terms of
  15 * the GNU General Public License as published by
  16 * the Free Software Foundation; either version 2, or (at your option)
  17 * any later version.
  18 *
  19 * This SCTP implementation is distributed in the hope that it
  20 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  21 *                 ************************
  22 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  23 * See the GNU General Public License for more details.
  24 *
  25 * You should have received a copy of the GNU General Public License
  26 * along with GNU CC; see the file COPYING.  If not, write to
  27 * the Free Software Foundation, 59 Temple Place - Suite 330,
  28 * Boston, MA 02111-1307, USA.
  29 *
  30 * Please send any bug reports or fixes you make to the
  31 * email address(es):
  32 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  33 *
  34 * Or submit a bug report through the following website:
  35 *    http://www.sf.net/projects/lksctp
  36 *
  37 * Written or modified by:
  38 *    La Monte H.P. Yarroll <piggy@acm.org>
  39 *    Karl Knutson <karl@athena.chicago.il.us>
  40 *    Xingang Guo <xingang.guo@intel.com>
  41 *    Jon Grimm <jgrimm@us.ibm.com>
  42 *    Hui Huang <hui.huang@nokia.com>
  43 *    Daisy Chang <daisyc@us.ibm.com>
  44 *    Sridhar Samudrala <sri@us.ibm.com>
  45 *    Ardelle Fan <ardelle.fan@intel.com>
  46 *
  47 * Any bugs reported given to us we will try to fix... any fixes shared will
  48 * be incorporated into the next SCTP release.
  49 */
  50
  51#include <linux/types.h>
  52#include <linux/list.h> /* For struct list_head */
  53#include <linux/socket.h>
  54#include <linux/ip.h>
  55#include <linux/time.h> /* For struct timeval */
  56#include <net/ip.h>
  57#include <net/icmp.h>
  58#include <net/snmp.h>
  59#include <net/sock.h>
  60#include <net/xfrm.h>
  61#include <net/sctp/sctp.h>
  62#include <net/sctp/sm.h>
  63#include <net/sctp/checksum.h>
  64#include <net/net_namespace.h>
  65
  66/* Forward declarations for internal helpers. */
  67static int sctp_rcv_ootb(struct sk_buff *);
  68static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
  69                                      const union sctp_addr *laddr,
  70                                      const union sctp_addr *paddr,
  71                                      struct sctp_transport **transportp);
  72static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
  73static struct sctp_association *__sctp_lookup_association(
  74                                        const union sctp_addr *local,
  75                                        const union sctp_addr *peer,
  76                                        struct sctp_transport **pt);
  77
  78static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
  79
  80
  81/* Calculate the SCTP checksum of an SCTP packet.  */
  82static inline int sctp_rcv_checksum(struct sk_buff *skb)
  83{
  84        struct sk_buff *list = skb_shinfo(skb)->frag_list;
  85        struct sctphdr *sh = sctp_hdr(skb);
  86        __le32 cmp = sh->checksum;
  87        __le32 val;
  88        __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
  89
  90        for (; list; list = list->next)
  91                tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
  92                                        tmp);
  93
  94        val = sctp_end_cksum(tmp);
  95
  96        if (val != cmp) {
  97                /* CRC failure, dump it. */
  98                SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
  99                return -1;
 100        }
 101        return 0;
 102}
 103
 104struct sctp_input_cb {
 105        union {
 106                struct inet_skb_parm    h4;
 107#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 108                struct inet6_skb_parm   h6;
 109#endif
 110        } header;
 111        struct sctp_chunk *chunk;
 112};
 113#define SCTP_INPUT_CB(__skb)    ((struct sctp_input_cb *)&((__skb)->cb[0]))
 114
 115/*
 116 * This is the routine which IP calls when receiving an SCTP packet.
 117 */
 118int sctp_rcv(struct sk_buff *skb)
 119{
 120        struct sock *sk;
 121        struct sctp_association *asoc;
 122        struct sctp_endpoint *ep = NULL;
 123        struct sctp_ep_common *rcvr;
 124        struct sctp_transport *transport = NULL;
 125        struct sctp_chunk *chunk;
 126        struct sctphdr *sh;
 127        union sctp_addr src;
 128        union sctp_addr dest;
 129        int family;
 130        struct sctp_af *af;
 131
 132        if (skb->pkt_type!=PACKET_HOST)
 133                goto discard_it;
 134
 135        SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
 136
 137        if (skb_linearize(skb))
 138                goto discard_it;
 139
 140        sh = sctp_hdr(skb);
 141
 142        /* Pull up the IP and SCTP headers. */
 143        __skb_pull(skb, skb_transport_offset(skb));
 144        if (skb->len < sizeof(struct sctphdr))
 145                goto discard_it;
 146        if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
 147                  sctp_rcv_checksum(skb) < 0)
 148                goto discard_it;
 149
 150        skb_pull(skb, sizeof(struct sctphdr));
 151
 152        /* Make sure we at least have chunk headers worth of data left. */
 153        if (skb->len < sizeof(struct sctp_chunkhdr))
 154                goto discard_it;
 155
 156        family = ipver2af(ip_hdr(skb)->version);
 157        af = sctp_get_af_specific(family);
 158        if (unlikely(!af))
 159                goto discard_it;
 160
 161        /* Initialize local addresses for lookups. */
 162        af->from_skb(&src, skb, 1);
 163        af->from_skb(&dest, skb, 0);
 164
 165        /* If the packet is to or from a non-unicast address,
 166         * silently discard the packet.
 167         *
 168         * This is not clearly defined in the RFC except in section
 169         * 8.4 - OOTB handling.  However, based on the book "Stream Control
 170         * Transmission Protocol" 2.1, "It is important to note that the
 171         * IP address of an SCTP transport address must be a routable
 172         * unicast address.  In other words, IP multicast addresses and
 173         * IP broadcast addresses cannot be used in an SCTP transport
 174         * address."
 175         */
 176        if (!af->addr_valid(&src, NULL, skb) ||
 177            !af->addr_valid(&dest, NULL, skb))
 178                goto discard_it;
 179
 180        asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
 181
 182        if (!asoc)
 183                ep = __sctp_rcv_lookup_endpoint(&dest);
 184
 185        /* Retrieve the common input handling substructure. */
 186        rcvr = asoc ? &asoc->base : &ep->base;
 187        sk = rcvr->sk;
 188
 189        /*
 190         * If a frame arrives on an interface and the receiving socket is
 191         * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
 192         */
 193        if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
 194        {
 195                if (asoc) {
 196                        sctp_association_put(asoc);
 197                        asoc = NULL;
 198                } else {
 199                        sctp_endpoint_put(ep);
 200                        ep = NULL;
 201                }
 202                sk = sctp_get_ctl_sock();
 203                ep = sctp_sk(sk)->ep;
 204                sctp_endpoint_hold(ep);
 205                rcvr = &ep->base;
 206        }
 207
 208        /*
 209         * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 210         * An SCTP packet is called an "out of the blue" (OOTB)
 211         * packet if it is correctly formed, i.e., passed the
 212         * receiver's checksum check, but the receiver is not
 213         * able to identify the association to which this
 214         * packet belongs.
 215         */
 216        if (!asoc) {
 217                if (sctp_rcv_ootb(skb)) {
 218                        SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
 219                        goto discard_release;
 220                }
 221        }
 222
 223        if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
 224                goto discard_release;
 225        nf_reset(skb);
 226
 227        if (sk_filter(sk, skb))
 228                goto discard_release;
 229
 230        /* Create an SCTP packet structure. */
 231        chunk = sctp_chunkify(skb, asoc, sk);
 232        if (!chunk)
 233                goto discard_release;
 234        SCTP_INPUT_CB(skb)->chunk = chunk;
 235
 236        /* Remember what endpoint is to handle this packet. */
 237        chunk->rcvr = rcvr;
 238
 239        /* Remember the SCTP header. */
 240        chunk->sctp_hdr = sh;
 241
 242        /* Set the source and destination addresses of the incoming chunk.  */
 243        sctp_init_addrs(chunk, &src, &dest);
 244
 245        /* Remember where we came from.  */
 246        chunk->transport = transport;
 247
 248        /* Acquire access to the sock lock. Note: We are safe from other
 249         * bottom halves on this lock, but a user may be in the lock too,
 250         * so check if it is busy.
 251         */
 252        sctp_bh_lock_sock(sk);
 253
 254        if (sk != rcvr->sk) {
 255                /* Our cached sk is different from the rcvr->sk.  This is
 256                 * because migrate()/accept() may have moved the association
 257                 * to a new socket and released all the sockets.  So now we
 258                 * are holding a lock on the old socket while the user may
 259                 * be doing something with the new socket.  Switch our veiw
 260                 * of the current sk.
 261                 */
 262                sctp_bh_unlock_sock(sk);
 263                sk = rcvr->sk;
 264                sctp_bh_lock_sock(sk);
 265        }
 266
 267        if (sock_owned_by_user(sk)) {
 268                SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
 269                sctp_add_backlog(sk, skb);
 270        } else {
 271                SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
 272                sctp_inq_push(&chunk->rcvr->inqueue, chunk);
 273        }
 274
 275        sctp_bh_unlock_sock(sk);
 276
 277        /* Release the asoc/ep ref we took in the lookup calls. */
 278        if (asoc)
 279                sctp_association_put(asoc);
 280        else
 281                sctp_endpoint_put(ep);
 282
 283        return 0;
 284
 285discard_it:
 286        SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
 287        kfree_skb(skb);
 288        return 0;
 289
 290discard_release:
 291        /* Release the asoc/ep ref we took in the lookup calls. */
 292        if (asoc)
 293                sctp_association_put(asoc);
 294        else
 295                sctp_endpoint_put(ep);
 296
 297        goto discard_it;
 298}
 299
 300/* Process the backlog queue of the socket.  Every skb on
 301 * the backlog holds a ref on an association or endpoint.
 302 * We hold this ref throughout the state machine to make
 303 * sure that the structure we need is still around.
 304 */
 305int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 306{
 307        struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 308        struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
 309        struct sctp_ep_common *rcvr = NULL;
 310        int backloged = 0;
 311
 312        rcvr = chunk->rcvr;
 313
 314        /* If the rcvr is dead then the association or endpoint
 315         * has been deleted and we can safely drop the chunk
 316         * and refs that we are holding.
 317         */
 318        if (rcvr->dead) {
 319                sctp_chunk_free(chunk);
 320                goto done;
 321        }
 322
 323        if (unlikely(rcvr->sk != sk)) {
 324                /* In this case, the association moved from one socket to
 325                 * another.  We are currently sitting on the backlog of the
 326                 * old socket, so we need to move.
 327                 * However, since we are here in the process context we
 328                 * need to take make sure that the user doesn't own
 329                 * the new socket when we process the packet.
 330                 * If the new socket is user-owned, queue the chunk to the
 331                 * backlog of the new socket without dropping any refs.
 332                 * Otherwise, we can safely push the chunk on the inqueue.
 333                 */
 334
 335                sk = rcvr->sk;
 336                sctp_bh_lock_sock(sk);
 337
 338                if (sock_owned_by_user(sk)) {
 339                        sk_add_backlog(sk, skb);
 340                        backloged = 1;
 341                } else
 342                        sctp_inq_push(inqueue, chunk);
 343
 344                sctp_bh_unlock_sock(sk);
 345
 346                /* If the chunk was backloged again, don't drop refs */
 347                if (backloged)
 348                        return 0;
 349        } else {
 350                sctp_inq_push(inqueue, chunk);
 351        }
 352
 353done:
 354        /* Release the refs we took in sctp_add_backlog */
 355        if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 356                sctp_association_put(sctp_assoc(rcvr));
 357        else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 358                sctp_endpoint_put(sctp_ep(rcvr));
 359        else
 360                BUG();
 361
 362        return 0;
 363}
 364
 365static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 366{
 367        struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 368        struct sctp_ep_common *rcvr = chunk->rcvr;
 369
 370        /* Hold the assoc/ep while hanging on the backlog queue.
 371         * This way, we know structures we need will not disappear from us
 372         */
 373        if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 374                sctp_association_hold(sctp_assoc(rcvr));
 375        else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 376                sctp_endpoint_hold(sctp_ep(rcvr));
 377        else
 378                BUG();
 379
 380        sk_add_backlog(sk, skb);
 381}
 382
 383/* Handle icmp frag needed error. */
 384void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
 385                           struct sctp_transport *t, __u32 pmtu)
 386{
 387        if (!t || (t->pathmtu <= pmtu))
 388                return;
 389
 390        if (sock_owned_by_user(sk)) {
 391                asoc->pmtu_pending = 1;
 392                t->pmtu_pending = 1;
 393                return;
 394        }
 395
 396        if (t->param_flags & SPP_PMTUD_ENABLE) {
 397                /* Update transports view of the MTU */
 398                sctp_transport_update_pmtu(t, pmtu);
 399
 400                /* Update association pmtu. */
 401                sctp_assoc_sync_pmtu(asoc);
 402        }
 403
 404        /* Retransmit with the new pmtu setting.
 405         * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
 406         * Needed will never be sent, but if a message was sent before
 407         * PMTU discovery was disabled that was larger than the PMTU, it
 408         * would not be fragmented, so it must be re-transmitted fragmented.
 409         */
 410        sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 411}
 412
 413/*
 414 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
 415 *
 416 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
 417 *        or a "Protocol Unreachable" treat this message as an abort
 418 *        with the T bit set.
 419 *
 420 * This function sends an event to the state machine, which will abort the
 421 * association.
 422 *
 423 */
 424void sctp_icmp_proto_unreachable(struct sock *sk,
 425                           struct sctp_association *asoc,
 426                           struct sctp_transport *t)
 427{
 428        SCTP_DEBUG_PRINTK("%s\n",  __func__);
 429
 430        sctp_do_sm(SCTP_EVENT_T_OTHER,
 431                   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
 432                   asoc->state, asoc->ep, asoc, t,
 433                   GFP_ATOMIC);
 434
 435}
 436
 437/* Common lookup code for icmp/icmpv6 error handler. */
 438struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
 439                             struct sctphdr *sctphdr,
 440                             struct sctp_association **app,
 441                             struct sctp_transport **tpp)
 442{
 443        union sctp_addr saddr;
 444        union sctp_addr daddr;
 445        struct sctp_af *af;
 446        struct sock *sk = NULL;
 447        struct sctp_association *asoc;
 448        struct sctp_transport *transport = NULL;
 449        struct sctp_init_chunk *chunkhdr;
 450        __u32 vtag = ntohl(sctphdr->vtag);
 451        int len = skb->len - ((void *)sctphdr - (void *)skb->data);
 452
 453        *app = NULL; *tpp = NULL;
 454
 455        af = sctp_get_af_specific(family);
 456        if (unlikely(!af)) {
 457                return NULL;
 458        }
 459
 460        /* Initialize local addresses for lookups. */
 461        af->from_skb(&saddr, skb, 1);
 462        af->from_skb(&daddr, skb, 0);
 463
 464        /* Look for an association that matches the incoming ICMP error
 465         * packet.
 466         */
 467        asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
 468        if (!asoc)
 469                return NULL;
 470
 471        sk = asoc->base.sk;
 472
 473        /* RFC 4960, Appendix C. ICMP Handling
 474         *
 475         * ICMP6) An implementation MUST validate that the Verification Tag
 476         * contained in the ICMP message matches the Verification Tag of
 477         * the peer.  If the Verification Tag is not 0 and does NOT
 478         * match, discard the ICMP message.  If it is 0 and the ICMP
 479         * message contains enough bytes to verify that the chunk type is
 480         * an INIT chunk and that the Initiate Tag matches the tag of the
 481         * peer, continue with ICMP7.  If the ICMP message is too short
 482         * or the chunk type or the Initiate Tag does not match, silently
 483         * discard the packet.
 484         */
 485        if (vtag == 0) {
 486                chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr
 487                                + sizeof(struct sctphdr));
 488                if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
 489                          + sizeof(__be32) ||
 490                    chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
 491                    ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
 492                        goto out;
 493                }
 494        } else if (vtag != asoc->c.peer_vtag) {
 495                goto out;
 496        }
 497
 498        sctp_bh_lock_sock(sk);
 499
 500        /* If too many ICMPs get dropped on busy
 501         * servers this needs to be solved differently.
 502         */
 503        if (sock_owned_by_user(sk))
 504                NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
 505
 506        *app = asoc;
 507        *tpp = transport;
 508        return sk;
 509
 510out:
 511        if (asoc)
 512                sctp_association_put(asoc);
 513        return NULL;
 514}
 515
 516/* Common cleanup code for icmp/icmpv6 error handler. */
 517void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
 518{
 519        sctp_bh_unlock_sock(sk);
 520        if (asoc)
 521                sctp_association_put(asoc);
 522}
 523
 524/*
 525 * This routine is called by the ICMP module when it gets some
 526 * sort of error condition.  If err < 0 then the socket should
 527 * be closed and the error returned to the user.  If err > 0
 528 * it's just the icmp type << 8 | icmp code.  After adjustment
 529 * header points to the first 8 bytes of the sctp header.  We need
 530 * to find the appropriate port.
 531 *
 532 * The locking strategy used here is very "optimistic". When
 533 * someone else accesses the socket the ICMP is just dropped
 534 * and for some paths there is no check at all.
 535 * A more general error queue to queue errors for later handling
 536 * is probably better.
 537 *
 538 */
 539void sctp_v4_err(struct sk_buff *skb, __u32 info)
 540{
 541        struct iphdr *iph = (struct iphdr *)skb->data;
 542        const int ihlen = iph->ihl * 4;
 543        const int type = icmp_hdr(skb)->type;
 544        const int code = icmp_hdr(skb)->code;
 545        struct sock *sk;
 546        struct sctp_association *asoc = NULL;
 547        struct sctp_transport *transport;
 548        struct inet_sock *inet;
 549        sk_buff_data_t saveip, savesctp;
 550        int err;
 551
 552        if (skb->len < ihlen + 8) {
 553                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 554                return;
 555        }
 556
 557        /* Fix up skb to look at the embedded net header. */
 558        saveip = skb->network_header;
 559        savesctp = skb->transport_header;
 560        skb_reset_network_header(skb);
 561        skb_set_transport_header(skb, ihlen);
 562        sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
 563        /* Put back, the original values. */
 564        skb->network_header = saveip;
 565        skb->transport_header = savesctp;
 566        if (!sk) {
 567                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 568                return;
 569        }
 570        /* Warning:  The sock lock is held.  Remember to call
 571         * sctp_err_finish!
 572         */
 573
 574        switch (type) {
 575        case ICMP_PARAMETERPROB:
 576                err = EPROTO;
 577                break;
 578        case ICMP_DEST_UNREACH:
 579                if (code > NR_ICMP_UNREACH)
 580                        goto out_unlock;
 581
 582                /* PMTU discovery (RFC1191) */
 583                if (ICMP_FRAG_NEEDED == code) {
 584                        sctp_icmp_frag_needed(sk, asoc, transport, info);
 585                        goto out_unlock;
 586                }
 587                else {
 588                        if (ICMP_PROT_UNREACH == code) {
 589                                sctp_icmp_proto_unreachable(sk, asoc,
 590                                                            transport);
 591                                goto out_unlock;
 592                        }
 593                }
 594                err = icmp_err_convert[code].errno;
 595                break;
 596        case ICMP_TIME_EXCEEDED:
 597                /* Ignore any time exceeded errors due to fragment reassembly
 598                 * timeouts.
 599                 */
 600                if (ICMP_EXC_FRAGTIME == code)
 601                        goto out_unlock;
 602
 603                err = EHOSTUNREACH;
 604                break;
 605        default:
 606                goto out_unlock;
 607        }
 608
 609        inet = inet_sk(sk);
 610        if (!sock_owned_by_user(sk) && inet->recverr) {
 611                sk->sk_err = err;
 612                sk->sk_error_report(sk);
 613        } else {  /* Only an error on timeout */
 614                sk->sk_err_soft = err;
 615        }
 616
 617out_unlock:
 618        sctp_err_finish(sk, asoc);
 619}
 620
 621/*
 622 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 623 *
 624 * This function scans all the chunks in the OOTB packet to determine if
 625 * the packet should be discarded right away.  If a response might be needed
 626 * for this packet, or, if further processing is possible, the packet will
 627 * be queued to a proper inqueue for the next phase of handling.
 628 *
 629 * Output:
 630 * Return 0 - If further processing is needed.
 631 * Return 1 - If the packet can be discarded right away.
 632 */
 633static int sctp_rcv_ootb(struct sk_buff *skb)
 634{
 635        sctp_chunkhdr_t *ch;
 636        __u8 *ch_end;
 637        sctp_errhdr_t *err;
 638
 639        ch = (sctp_chunkhdr_t *) skb->data;
 640
 641        /* Scan through all the chunks in the packet.  */
 642        do {
 643                /* Break out if chunk length is less then minimal. */
 644                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
 645                        break;
 646
 647                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 648                if (ch_end > skb_tail_pointer(skb))
 649                        break;
 650
 651                /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
 652                 * receiver MUST silently discard the OOTB packet and take no
 653                 * further action.
 654                 */
 655                if (SCTP_CID_ABORT == ch->type)
 656                        goto discard;
 657
 658                /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
 659                 * chunk, the receiver should silently discard the packet
 660                 * and take no further action.
 661                 */
 662                if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
 663                        goto discard;
 664
 665                /* RFC 4460, 2.11.2
 666                 * This will discard packets with INIT chunk bundled as
 667                 * subsequent chunks in the packet.  When INIT is first,
 668                 * the normal INIT processing will discard the chunk.
 669                 */
 670                if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
 671                        goto discard;
 672
 673                /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
 674                 * or a COOKIE ACK the SCTP Packet should be silently
 675                 * discarded.
 676                 */
 677                if (SCTP_CID_COOKIE_ACK == ch->type)
 678                        goto discard;
 679
 680                if (SCTP_CID_ERROR == ch->type) {
 681                        sctp_walk_errors(err, ch) {
 682                                if (SCTP_ERROR_STALE_COOKIE == err->cause)
 683                                        goto discard;
 684                        }
 685                }
 686
 687                ch = (sctp_chunkhdr_t *) ch_end;
 688        } while (ch_end < skb_tail_pointer(skb));
 689
 690        return 0;
 691
 692discard:
 693        return 1;
 694}
 695
 696/* Insert endpoint into the hash table.  */
 697static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
 698{
 699        struct sctp_ep_common *epb;
 700        struct sctp_hashbucket *head;
 701
 702        epb = &ep->base;
 703
 704        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
 705        head = &sctp_ep_hashtable[epb->hashent];
 706
 707        sctp_write_lock(&head->lock);
 708        hlist_add_head(&epb->node, &head->chain);
 709        sctp_write_unlock(&head->lock);
 710}
 711
 712/* Add an endpoint to the hash. Local BH-safe. */
 713void sctp_hash_endpoint(struct sctp_endpoint *ep)
 714{
 715        sctp_local_bh_disable();
 716        __sctp_hash_endpoint(ep);
 717        sctp_local_bh_enable();
 718}
 719
 720/* Remove endpoint from the hash table.  */
 721static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
 722{
 723        struct sctp_hashbucket *head;
 724        struct sctp_ep_common *epb;
 725
 726        epb = &ep->base;
 727
 728        if (hlist_unhashed(&epb->node))
 729                return;
 730
 731        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
 732
 733        head = &sctp_ep_hashtable[epb->hashent];
 734
 735        sctp_write_lock(&head->lock);
 736        __hlist_del(&epb->node);
 737        sctp_write_unlock(&head->lock);
 738}
 739
 740/* Remove endpoint from the hash.  Local BH-safe. */
 741void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 742{
 743        sctp_local_bh_disable();
 744        __sctp_unhash_endpoint(ep);
 745        sctp_local_bh_enable();
 746}
 747
 748/* Look up an endpoint. */
 749static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
 750{
 751        struct sctp_hashbucket *head;
 752        struct sctp_ep_common *epb;
 753        struct sctp_endpoint *ep;
 754        struct hlist_node *node;
 755        int hash;
 756
 757        hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
 758        head = &sctp_ep_hashtable[hash];
 759        read_lock(&head->lock);
 760        sctp_for_each_hentry(epb, node, &head->chain) {
 761                ep = sctp_ep(epb);
 762                if (sctp_endpoint_is_match(ep, laddr))
 763                        goto hit;
 764        }
 765
 766        ep = sctp_sk((sctp_get_ctl_sock()))->ep;
 767
 768hit:
 769        sctp_endpoint_hold(ep);
 770        read_unlock(&head->lock);
 771        return ep;
 772}
 773
 774/* Insert association into the hash table.  */
 775static void __sctp_hash_established(struct sctp_association *asoc)
 776{
 777        struct sctp_ep_common *epb;
 778        struct sctp_hashbucket *head;
 779
 780        epb = &asoc->base;
 781
 782        /* Calculate which chain this entry will belong to. */
 783        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
 784
 785        head = &sctp_assoc_hashtable[epb->hashent];
 786
 787        sctp_write_lock(&head->lock);
 788        hlist_add_head(&epb->node, &head->chain);
 789        sctp_write_unlock(&head->lock);
 790}
 791
 792/* Add an association to the hash. Local BH-safe. */
 793void sctp_hash_established(struct sctp_association *asoc)
 794{
 795        if (asoc->temp)
 796                return;
 797
 798        sctp_local_bh_disable();
 799        __sctp_hash_established(asoc);
 800        sctp_local_bh_enable();
 801}
 802
 803/* Remove association from the hash table.  */
 804static void __sctp_unhash_established(struct sctp_association *asoc)
 805{
 806        struct sctp_hashbucket *head;
 807        struct sctp_ep_common *epb;
 808
 809        epb = &asoc->base;
 810
 811        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
 812                                         asoc->peer.port);
 813
 814        head = &sctp_assoc_hashtable[epb->hashent];
 815
 816        sctp_write_lock(&head->lock);
 817        __hlist_del(&epb->node);
 818        sctp_write_unlock(&head->lock);
 819}
 820
 821/* Remove association from the hash table.  Local BH-safe. */
 822void sctp_unhash_established(struct sctp_association *asoc)
 823{
 824        if (asoc->temp)
 825                return;
 826
 827        sctp_local_bh_disable();
 828        __sctp_unhash_established(asoc);
 829        sctp_local_bh_enable();
 830}
 831
 832/* Look up an association. */
 833static struct sctp_association *__sctp_lookup_association(
 834                                        const union sctp_addr *local,
 835                                        const union sctp_addr *peer,
 836                                        struct sctp_transport **pt)
 837{
 838        struct sctp_hashbucket *head;
 839        struct sctp_ep_common *epb;
 840        struct sctp_association *asoc;
 841        struct sctp_transport *transport;
 842        struct hlist_node *node;
 843        int hash;
 844
 845        /* Optimize here for direct hit, only listening connections can
 846         * have wildcards anyways.
 847         */
 848        hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
 849        head = &sctp_assoc_hashtable[hash];
 850        read_lock(&head->lock);
 851        sctp_for_each_hentry(epb, node, &head->chain) {
 852                asoc = sctp_assoc(epb);
 853                transport = sctp_assoc_is_match(asoc, local, peer);
 854                if (transport)
 855                        goto hit;
 856        }
 857
 858        read_unlock(&head->lock);
 859
 860        return NULL;
 861
 862hit:
 863        *pt = transport;
 864        sctp_association_hold(asoc);
 865        read_unlock(&head->lock);
 866        return asoc;
 867}
 868
 869/* Look up an association. BH-safe. */
 870SCTP_STATIC
 871struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
 872                                                 const union sctp_addr *paddr,
 873                                            struct sctp_transport **transportp)
 874{
 875        struct sctp_association *asoc;
 876
 877        sctp_local_bh_disable();
 878        asoc = __sctp_lookup_association(laddr, paddr, transportp);
 879        sctp_local_bh_enable();
 880
 881        return asoc;
 882}
 883
 884/* Is there an association matching the given local and peer addresses? */
 885int sctp_has_association(const union sctp_addr *laddr,
 886                         const union sctp_addr *paddr)
 887{
 888        struct sctp_association *asoc;
 889        struct sctp_transport *transport;
 890
 891        if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
 892                sctp_association_put(asoc);
 893                return 1;
 894        }
 895
 896        return 0;
 897}
 898
 899/*
 900 * SCTP Implementors Guide, 2.18 Handling of address
 901 * parameters within the INIT or INIT-ACK.
 902 *
 903 * D) When searching for a matching TCB upon reception of an INIT
 904 *    or INIT-ACK chunk the receiver SHOULD use not only the
 905 *    source address of the packet (containing the INIT or
 906 *    INIT-ACK) but the receiver SHOULD also use all valid
 907 *    address parameters contained within the chunk.
 908 *
 909 * 2.18.3 Solution description
 910 *
 911 * This new text clearly specifies to an implementor the need
 912 * to look within the INIT or INIT-ACK. Any implementation that
 913 * does not do this, may not be able to establish associations
 914 * in certain circumstances.
 915 *
 916 */
 917static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
 918        const union sctp_addr *laddr, struct sctp_transport **transportp)
 919{
 920        struct sctp_association *asoc;
 921        union sctp_addr addr;
 922        union sctp_addr *paddr = &addr;
 923        struct sctphdr *sh = sctp_hdr(skb);
 924        sctp_chunkhdr_t *ch;
 925        union sctp_params params;
 926        sctp_init_chunk_t *init;
 927        struct sctp_transport *transport;
 928        struct sctp_af *af;
 929
 930        ch = (sctp_chunkhdr_t *) skb->data;
 931
 932        /*
 933         * This code will NOT touch anything inside the chunk--it is
 934         * strictly READ-ONLY.
 935         *
 936         * RFC 2960 3  SCTP packet Format
 937         *
 938         * Multiple chunks can be bundled into one SCTP packet up to
 939         * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
 940         * COMPLETE chunks.  These chunks MUST NOT be bundled with any
 941         * other chunk in a packet.  See Section 6.10 for more details
 942         * on chunk bundling.
 943         */
 944
 945        /* Find the start of the TLVs and the end of the chunk.  This is
 946         * the region we search for address parameters.
 947         */
 948        init = (sctp_init_chunk_t *)skb->data;
 949
 950        /* Walk the parameters looking for embedded addresses. */
 951        sctp_walk_params(params, init, init_hdr.params) {
 952
 953                /* Note: Ignoring hostname addresses. */
 954                af = sctp_get_af_specific(param_type2af(params.p->type));
 955                if (!af)
 956                        continue;
 957
 958                af->from_addr_param(paddr, params.addr, sh->source, 0);
 959
 960                asoc = __sctp_lookup_association(laddr, paddr, &transport);
 961                if (asoc)
 962                        return asoc;
 963        }
 964
 965        return NULL;
 966}
 967
 968/* ADD-IP, Section 5.2
 969 * When an endpoint receives an ASCONF Chunk from the remote peer
 970 * special procedures may be needed to identify the association the
 971 * ASCONF Chunk is associated with. To properly find the association
 972 * the following procedures SHOULD be followed:
 973 *
 974 * D2) If the association is not found, use the address found in the
 975 * Address Parameter TLV combined with the port number found in the
 976 * SCTP common header. If found proceed to rule D4.
 977 *
 978 * D2-ext) If more than one ASCONF Chunks are packed together, use the
 979 * address found in the ASCONF Address Parameter TLV of each of the
 980 * subsequent ASCONF Chunks. If found, proceed to rule D4.
 981 */
 982static struct sctp_association *__sctp_rcv_asconf_lookup(
 983                                        sctp_chunkhdr_t *ch,
 984                                        const union sctp_addr *laddr,
 985                                        __be16 peer_port,
 986                                        struct sctp_transport **transportp)
 987{
 988        sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
 989        struct sctp_af *af;
 990        union sctp_addr_param *param;
 991        union sctp_addr paddr;
 992
 993        /* Skip over the ADDIP header and find the Address parameter */
 994        param = (union sctp_addr_param *)(asconf + 1);
 995
 996        af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type));
 997        if (unlikely(!af))
 998                return NULL;
 999
1000        af->from_addr_param(&paddr, param, peer_port, 0);
1001
1002        return __sctp_lookup_association(laddr, &paddr, transportp);
1003}
1004
1005
1006/* SCTP-AUTH, Section 6.3:
1007*    If the receiver does not find a STCB for a packet containing an AUTH
1008*    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1009*    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1010*    association.
1011*
1012* This means that any chunks that can help us identify the association need
1013* to be looked at to find this assocation.
1014*/
1015static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1016                                      const union sctp_addr *laddr,
1017                                      struct sctp_transport **transportp)
1018{
1019        struct sctp_association *asoc = NULL;
1020        sctp_chunkhdr_t *ch;
1021        int have_auth = 0;
1022        unsigned int chunk_num = 1;
1023        __u8 *ch_end;
1024
1025        /* Walk through the chunks looking for AUTH or ASCONF chunks
1026         * to help us find the association.
1027         */
1028        ch = (sctp_chunkhdr_t *) skb->data;
1029        do {
1030                /* Break out if chunk length is less then minimal. */
1031                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1032                        break;
1033
1034                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1035                if (ch_end > skb_tail_pointer(skb))
1036                        break;
1037
1038                switch(ch->type) {
1039                    case SCTP_CID_AUTH:
1040                            have_auth = chunk_num;
1041                            break;
1042
1043                    case SCTP_CID_COOKIE_ECHO:
1044                            /* If a packet arrives containing an AUTH chunk as
1045                             * a first chunk, a COOKIE-ECHO chunk as the second
1046                             * chunk, and possibly more chunks after them, and
1047                             * the receiver does not have an STCB for that
1048                             * packet, then authentication is based on
1049                             * the contents of the COOKIE- ECHO chunk.
1050                             */
1051                            if (have_auth == 1 && chunk_num == 2)
1052                                    return NULL;
1053                            break;
1054
1055                    case SCTP_CID_ASCONF:
1056                            if (have_auth || sctp_addip_noauth)
1057                                    asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1058                                                        sctp_hdr(skb)->source,
1059                                                        transportp);
1060                    default:
1061                            break;
1062                }
1063
1064                if (asoc)
1065                        break;
1066
1067                ch = (sctp_chunkhdr_t *) ch_end;
1068                chunk_num++;
1069        } while (ch_end < skb_tail_pointer(skb));
1070
1071        return asoc;
1072}
1073
1074/*
1075 * There are circumstances when we need to look inside the SCTP packet
1076 * for information to help us find the association.   Examples
1077 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1078 * chunks.
1079 */
1080static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1081                                      const union sctp_addr *laddr,
1082                                      struct sctp_transport **transportp)
1083{
1084        sctp_chunkhdr_t *ch;
1085
1086        ch = (sctp_chunkhdr_t *) skb->data;
1087
1088        /* The code below will attempt to walk the chunk and extract
1089         * parameter information.  Before we do that, we need to verify
1090         * that the chunk length doesn't cause overflow.  Otherwise, we'll
1091         * walk off the end.
1092         */
1093        if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1094                return NULL;
1095
1096        /* If this is INIT/INIT-ACK look inside the chunk too. */
1097        switch (ch->type) {
1098        case SCTP_CID_INIT:
1099        case SCTP_CID_INIT_ACK:
1100                return __sctp_rcv_init_lookup(skb, laddr, transportp);
1101                break;
1102
1103        default:
1104                return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1105                break;
1106        }
1107
1108
1109        return NULL;
1110}
1111
1112/* Lookup an association for an inbound skb. */
1113static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1114                                      const union sctp_addr *paddr,
1115                                      const union sctp_addr *laddr,
1116                                      struct sctp_transport **transportp)
1117{
1118        struct sctp_association *asoc;
1119
1120        asoc = __sctp_lookup_association(laddr, paddr, transportp);
1121
1122        /* Further lookup for INIT/INIT-ACK packets.
1123         * SCTP Implementors Guide, 2.18 Handling of address
1124         * parameters within the INIT or INIT-ACK.
1125         */
1126        if (!asoc)
1127                asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1128
1129        return asoc;
1130}
1131