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 <linux/slab.h>
  57#include <net/ip.h>
  58#include <net/icmp.h>
  59#include <net/snmp.h>
  60#include <net/sock.h>
  61#include <net/xfrm.h>
  62#include <net/sctp/sctp.h>
  63#include <net/sctp/sm.h>
  64#include <net/sctp/checksum.h>
  65#include <net/net_namespace.h>
  66
  67/* Forward declarations for internal helpers. */
  68static int sctp_rcv_ootb(struct sk_buff *);
  69static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
  70                                      const union sctp_addr *laddr,
  71                                      const union sctp_addr *paddr,
  72                                      struct sctp_transport **transportp);
  73static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
  74static struct sctp_association *__sctp_lookup_association(
  75                                        const union sctp_addr *local,
  76                                        const union sctp_addr *peer,
  77                                        struct sctp_transport **pt);
  78
  79static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
  80
  81
  82/* Calculate the SCTP checksum of an SCTP packet.  */
  83static inline int sctp_rcv_checksum(struct sk_buff *skb)
  84{
  85        struct sctphdr *sh = sctp_hdr(skb);
  86        __le32 cmp = sh->checksum;
  87        struct sk_buff *list;
  88        __le32 val;
  89        __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
  90
  91        skb_walk_frags(skb, list)
  92                tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
  93                                        tmp);
  94
  95        val = sctp_end_cksum(tmp);
  96
  97        if (val != cmp) {
  98                /* CRC failure, dump it. */
  99                SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
 100                return -1;
 101        }
 102        return 0;
 103}
 104
 105struct sctp_input_cb {
 106        union {
 107                struct inet_skb_parm    h4;
 108#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 109                struct inet6_skb_parm   h6;
 110#endif
 111        } header;
 112        struct sctp_chunk *chunk;
 113};
 114#define SCTP_INPUT_CB(__skb)    ((struct sctp_input_cb *)&((__skb)->cb[0]))
 115
 116/*
 117 * This is the routine which IP calls when receiving an SCTP packet.
 118 */
 119int sctp_rcv(struct sk_buff *skb)
 120{
 121        struct sock *sk;
 122        struct sctp_association *asoc;
 123        struct sctp_endpoint *ep = NULL;
 124        struct sctp_ep_common *rcvr;
 125        struct sctp_transport *transport = NULL;
 126        struct sctp_chunk *chunk;
 127        struct sctphdr *sh;
 128        union sctp_addr src;
 129        union sctp_addr dest;
 130        int family;
 131        struct sctp_af *af;
 132
 133        if (skb->pkt_type!=PACKET_HOST)
 134                goto discard_it;
 135
 136        SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
 137
 138        if (skb_linearize(skb))
 139                goto discard_it;
 140
 141        sh = sctp_hdr(skb);
 142
 143        /* Pull up the IP and SCTP headers. */
 144        __skb_pull(skb, skb_transport_offset(skb));
 145        if (skb->len < sizeof(struct sctphdr))
 146                goto discard_it;
 147        if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
 148                  sctp_rcv_checksum(skb) < 0)
 149                goto discard_it;
 150
 151        skb_pull(skb, sizeof(struct sctphdr));
 152
 153        /* Make sure we at least have chunk headers worth of data left. */
 154        if (skb->len < sizeof(struct sctp_chunkhdr))
 155                goto discard_it;
 156
 157        family = ipver2af(ip_hdr(skb)->version);
 158        af = sctp_get_af_specific(family);
 159        if (unlikely(!af))
 160                goto discard_it;
 161
 162        /* Initialize local addresses for lookups. */
 163        af->from_skb(&src, skb, 1);
 164        af->from_skb(&dest, skb, 0);
 165
 166        /* If the packet is to or from a non-unicast address,
 167         * silently discard the packet.
 168         *
 169         * This is not clearly defined in the RFC except in section
 170         * 8.4 - OOTB handling.  However, based on the book "Stream Control
 171         * Transmission Protocol" 2.1, "It is important to note that the
 172         * IP address of an SCTP transport address must be a routable
 173         * unicast address.  In other words, IP multicast addresses and
 174         * IP broadcast addresses cannot be used in an SCTP transport
 175         * address."
 176         */
 177        if (!af->addr_valid(&src, NULL, skb) ||
 178            !af->addr_valid(&dest, NULL, skb))
 179                goto discard_it;
 180
 181        asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
 182
 183        if (!asoc)
 184                ep = __sctp_rcv_lookup_endpoint(&dest);
 185
 186        /* Retrieve the common input handling substructure. */
 187        rcvr = asoc ? &asoc->base : &ep->base;
 188        sk = rcvr->sk;
 189
 190        /*
 191         * If a frame arrives on an interface and the receiving socket is
 192         * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
 193         */
 194        if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
 195        {
 196                if (asoc) {
 197                        sctp_association_put(asoc);
 198                        asoc = NULL;
 199                } else {
 200                        sctp_endpoint_put(ep);
 201                        ep = NULL;
 202                }
 203                sk = sctp_get_ctl_sock();
 204                ep = sctp_sk(sk)->ep;
 205                sctp_endpoint_hold(ep);
 206                rcvr = &ep->base;
 207        }
 208
 209        /*
 210         * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 211         * An SCTP packet is called an "out of the blue" (OOTB)
 212         * packet if it is correctly formed, i.e., passed the
 213         * receiver's checksum check, but the receiver is not
 214         * able to identify the association to which this
 215         * packet belongs.
 216         */
 217        if (!asoc) {
 218                if (sctp_rcv_ootb(skb)) {
 219                        SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
 220                        goto discard_release;
 221                }
 222        }
 223
 224        if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
 225                goto discard_release;
 226        nf_reset(skb);
 227
 228        if (sk_filter(sk, skb))
 229                goto discard_release;
 230
 231        /* Create an SCTP packet structure. */
 232        chunk = sctp_chunkify(skb, asoc, sk);
 233        if (!chunk)
 234                goto discard_release;
 235        SCTP_INPUT_CB(skb)->chunk = chunk;
 236
 237        /* Remember what endpoint is to handle this packet. */
 238        chunk->rcvr = rcvr;
 239
 240        /* Remember the SCTP header. */
 241        chunk->sctp_hdr = sh;
 242
 243        /* Set the source and destination addresses of the incoming chunk.  */
 244        sctp_init_addrs(chunk, &src, &dest);
 245
 246        /* Remember where we came from.  */
 247        chunk->transport = transport;
 248
 249        /* Acquire access to the sock lock. Note: We are safe from other
 250         * bottom halves on this lock, but a user may be in the lock too,
 251         * so check if it is busy.
 252         */
 253        sctp_bh_lock_sock(sk);
 254
 255        if (sk != rcvr->sk) {
 256                /* Our cached sk is different from the rcvr->sk.  This is
 257                 * because migrate()/accept() may have moved the association
 258                 * to a new socket and released all the sockets.  So now we
 259                 * are holding a lock on the old socket while the user may
 260                 * be doing something with the new socket.  Switch our veiw
 261                 * of the current sk.
 262                 */
 263                sctp_bh_unlock_sock(sk);
 264                sk = rcvr->sk;
 265                sctp_bh_lock_sock(sk);
 266        }
 267
 268        if (sock_owned_by_user(sk)) {
 269                if (sctp_add_backlog(sk, skb)) {
 270                        sctp_bh_unlock_sock(sk);
 271                        sctp_chunk_free(chunk);
 272                        skb = NULL; /* sctp_chunk_free already freed the skb */
 273                        goto discard_release;
 274                }
 275                SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
 276        } else {
 277                SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
 278                sctp_inq_push(&chunk->rcvr->inqueue, chunk);
 279        }
 280
 281        sctp_bh_unlock_sock(sk);
 282
 283        /* Release the asoc/ep ref we took in the lookup calls. */
 284        if (asoc)
 285                sctp_association_put(asoc);
 286        else
 287                sctp_endpoint_put(ep);
 288
 289        return 0;
 290
 291discard_it:
 292        SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
 293        kfree_skb(skb);
 294        return 0;
 295
 296discard_release:
 297        /* Release the asoc/ep ref we took in the lookup calls. */
 298        if (asoc)
 299                sctp_association_put(asoc);
 300        else
 301                sctp_endpoint_put(ep);
 302
 303        goto discard_it;
 304}
 305
 306/* Process the backlog queue of the socket.  Every skb on
 307 * the backlog holds a ref on an association or endpoint.
 308 * We hold this ref throughout the state machine to make
 309 * sure that the structure we need is still around.
 310 */
 311int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 312{
 313        struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 314        struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
 315        struct sctp_ep_common *rcvr = NULL;
 316        int backloged = 0;
 317
 318        rcvr = chunk->rcvr;
 319
 320        /* If the rcvr is dead then the association or endpoint
 321         * has been deleted and we can safely drop the chunk
 322         * and refs that we are holding.
 323         */
 324        if (rcvr->dead) {
 325                sctp_chunk_free(chunk);
 326                goto done;
 327        }
 328
 329        if (unlikely(rcvr->sk != sk)) {
 330                /* In this case, the association moved from one socket to
 331                 * another.  We are currently sitting on the backlog of the
 332                 * old socket, so we need to move.
 333                 * However, since we are here in the process context we
 334                 * need to take make sure that the user doesn't own
 335                 * the new socket when we process the packet.
 336                 * If the new socket is user-owned, queue the chunk to the
 337                 * backlog of the new socket without dropping any refs.
 338                 * Otherwise, we can safely push the chunk on the inqueue.
 339                 */
 340
 341                sk = rcvr->sk;
 342                sctp_bh_lock_sock(sk);
 343
 344                if (sock_owned_by_user(sk)) {
 345                        if (sk_add_backlog(sk, skb))
 346                                sctp_chunk_free(chunk);
 347                        else
 348                                backloged = 1;
 349                } else
 350                        sctp_inq_push(inqueue, chunk);
 351
 352                sctp_bh_unlock_sock(sk);
 353
 354                /* If the chunk was backloged again, don't drop refs */
 355                if (backloged)
 356                        return 0;
 357        } else {
 358                sctp_inq_push(inqueue, chunk);
 359        }
 360
 361done:
 362        /* Release the refs we took in sctp_add_backlog */
 363        if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 364                sctp_association_put(sctp_assoc(rcvr));
 365        else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 366                sctp_endpoint_put(sctp_ep(rcvr));
 367        else
 368                BUG();
 369
 370        return 0;
 371}
 372
 373static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 374{
 375        struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 376        struct sctp_ep_common *rcvr = chunk->rcvr;
 377        int ret;
 378
 379        ret = sk_add_backlog(sk, skb);
 380        if (!ret) {
 381                /* Hold the assoc/ep while hanging on the backlog queue.
 382                 * This way, we know structures we need will not disappear
 383                 * from us
 384                 */
 385                if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 386                        sctp_association_hold(sctp_assoc(rcvr));
 387                else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 388                        sctp_endpoint_hold(sctp_ep(rcvr));
 389                else
 390                        BUG();
 391        }
 392        return ret;
 393
 394}
 395
 396/* Handle icmp frag needed error. */
 397void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
 398                           struct sctp_transport *t, __u32 pmtu)
 399{
 400        if (!t || (t->pathmtu <= pmtu))
 401                return;
 402
 403        if (sock_owned_by_user(sk)) {
 404                asoc->pmtu_pending = 1;
 405                t->pmtu_pending = 1;
 406                return;
 407        }
 408
 409        if (t->param_flags & SPP_PMTUD_ENABLE) {
 410                /* Update transports view of the MTU */
 411                sctp_transport_update_pmtu(t, pmtu);
 412
 413                /* Update association pmtu. */
 414                sctp_assoc_sync_pmtu(asoc);
 415        }
 416
 417        /* Retransmit with the new pmtu setting.
 418         * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
 419         * Needed will never be sent, but if a message was sent before
 420         * PMTU discovery was disabled that was larger than the PMTU, it
 421         * would not be fragmented, so it must be re-transmitted fragmented.
 422         */
 423        sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 424}
 425
 426/*
 427 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
 428 *
 429 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
 430 *        or a "Protocol Unreachable" treat this message as an abort
 431 *        with the T bit set.
 432 *
 433 * This function sends an event to the state machine, which will abort the
 434 * association.
 435 *
 436 */
 437void sctp_icmp_proto_unreachable(struct sock *sk,
 438                           struct sctp_association *asoc,
 439                           struct sctp_transport *t)
 440{
 441        SCTP_DEBUG_PRINTK("%s\n",  __func__);
 442
 443        if (sock_owned_by_user(sk)) {
 444                if (timer_pending(&t->proto_unreach_timer))
 445                        return;
 446                else {
 447                        if (!mod_timer(&t->proto_unreach_timer,
 448                                                jiffies + (HZ/20)))
 449                                sctp_association_hold(asoc);
 450                }
 451                        
 452        } else {
 453                if (timer_pending(&t->proto_unreach_timer) &&
 454                    del_timer(&t->proto_unreach_timer))
 455                        sctp_association_put(asoc);
 456
 457                sctp_do_sm(SCTP_EVENT_T_OTHER,
 458                           SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
 459                           asoc->state, asoc->ep, asoc, t,
 460                           GFP_ATOMIC);
 461        }
 462}
 463
 464/* Common lookup code for icmp/icmpv6 error handler. */
 465struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
 466                             struct sctphdr *sctphdr,
 467                             struct sctp_association **app,
 468                             struct sctp_transport **tpp)
 469{
 470        union sctp_addr saddr;
 471        union sctp_addr daddr;
 472        struct sctp_af *af;
 473        struct sock *sk = NULL;
 474        struct sctp_association *asoc;
 475        struct sctp_transport *transport = NULL;
 476        struct sctp_init_chunk *chunkhdr;
 477        __u32 vtag = ntohl(sctphdr->vtag);
 478        int len = skb->len - ((void *)sctphdr - (void *)skb->data);
 479
 480        *app = NULL; *tpp = NULL;
 481
 482        af = sctp_get_af_specific(family);
 483        if (unlikely(!af)) {
 484                return NULL;
 485        }
 486
 487        /* Initialize local addresses for lookups. */
 488        af->from_skb(&saddr, skb, 1);
 489        af->from_skb(&daddr, skb, 0);
 490
 491        /* Look for an association that matches the incoming ICMP error
 492         * packet.
 493         */
 494        asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
 495        if (!asoc)
 496                return NULL;
 497
 498        sk = asoc->base.sk;
 499
 500        /* RFC 4960, Appendix C. ICMP Handling
 501         *
 502         * ICMP6) An implementation MUST validate that the Verification Tag
 503         * contained in the ICMP message matches the Verification Tag of
 504         * the peer.  If the Verification Tag is not 0 and does NOT
 505         * match, discard the ICMP message.  If it is 0 and the ICMP
 506         * message contains enough bytes to verify that the chunk type is
 507         * an INIT chunk and that the Initiate Tag matches the tag of the
 508         * peer, continue with ICMP7.  If the ICMP message is too short
 509         * or the chunk type or the Initiate Tag does not match, silently
 510         * discard the packet.
 511         */
 512        if (vtag == 0) {
 513                chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr
 514                                + sizeof(struct sctphdr));
 515                if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
 516                          + sizeof(__be32) ||
 517                    chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
 518                    ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
 519                        goto out;
 520                }
 521        } else if (vtag != asoc->c.peer_vtag) {
 522                goto out;
 523        }
 524
 525        sctp_bh_lock_sock(sk);
 526
 527        /* If too many ICMPs get dropped on busy
 528         * servers this needs to be solved differently.
 529         */
 530        if (sock_owned_by_user(sk))
 531                NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
 532
 533        *app = asoc;
 534        *tpp = transport;
 535        return sk;
 536
 537out:
 538        if (asoc)
 539                sctp_association_put(asoc);
 540        return NULL;
 541}
 542
 543/* Common cleanup code for icmp/icmpv6 error handler. */
 544void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
 545{
 546        sctp_bh_unlock_sock(sk);
 547        if (asoc)
 548                sctp_association_put(asoc);
 549}
 550
 551/*
 552 * This routine is called by the ICMP module when it gets some
 553 * sort of error condition.  If err < 0 then the socket should
 554 * be closed and the error returned to the user.  If err > 0
 555 * it's just the icmp type << 8 | icmp code.  After adjustment
 556 * header points to the first 8 bytes of the sctp header.  We need
 557 * to find the appropriate port.
 558 *
 559 * The locking strategy used here is very "optimistic". When
 560 * someone else accesses the socket the ICMP is just dropped
 561 * and for some paths there is no check at all.
 562 * A more general error queue to queue errors for later handling
 563 * is probably better.
 564 *
 565 */
 566void sctp_v4_err(struct sk_buff *skb, __u32 info)
 567{
 568        struct iphdr *iph = (struct iphdr *)skb->data;
 569        const int ihlen = iph->ihl * 4;
 570        const int type = icmp_hdr(skb)->type;
 571        const int code = icmp_hdr(skb)->code;
 572        struct sock *sk;
 573        struct sctp_association *asoc = NULL;
 574        struct sctp_transport *transport;
 575        struct inet_sock *inet;
 576        sk_buff_data_t saveip, savesctp;
 577        int err;
 578
 579        if (skb->len < ihlen + 8) {
 580                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 581                return;
 582        }
 583
 584        /* Fix up skb to look at the embedded net header. */
 585        saveip = skb->network_header;
 586        savesctp = skb->transport_header;
 587        skb_reset_network_header(skb);
 588        skb_set_transport_header(skb, ihlen);
 589        sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
 590        /* Put back, the original values. */
 591        skb->network_header = saveip;
 592        skb->transport_header = savesctp;
 593        if (!sk) {
 594                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 595                return;
 596        }
 597        /* Warning:  The sock lock is held.  Remember to call
 598         * sctp_err_finish!
 599         */
 600
 601        switch (type) {
 602        case ICMP_PARAMETERPROB:
 603                err = EPROTO;
 604                break;
 605        case ICMP_DEST_UNREACH:
 606                if (code > NR_ICMP_UNREACH)
 607                        goto out_unlock;
 608
 609                /* PMTU discovery (RFC1191) */
 610                if (ICMP_FRAG_NEEDED == code) {
 611                        sctp_icmp_frag_needed(sk, asoc, transport, info);
 612                        goto out_unlock;
 613                }
 614                else {
 615                        if (ICMP_PROT_UNREACH == code) {
 616                                sctp_icmp_proto_unreachable(sk, asoc,
 617                                                            transport);
 618                                goto out_unlock;
 619                        }
 620                }
 621                err = icmp_err_convert[code].errno;
 622                break;
 623        case ICMP_TIME_EXCEEDED:
 624                /* Ignore any time exceeded errors due to fragment reassembly
 625                 * timeouts.
 626                 */
 627                if (ICMP_EXC_FRAGTIME == code)
 628                        goto out_unlock;
 629
 630                err = EHOSTUNREACH;
 631                break;
 632        default:
 633                goto out_unlock;
 634        }
 635
 636        inet = inet_sk(sk);
 637        if (!sock_owned_by_user(sk) && inet->recverr) {
 638                sk->sk_err = err;
 639                sk->sk_error_report(sk);
 640        } else {  /* Only an error on timeout */
 641                sk->sk_err_soft = err;
 642        }
 643
 644out_unlock:
 645        sctp_err_finish(sk, asoc);
 646}
 647
 648/*
 649 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 650 *
 651 * This function scans all the chunks in the OOTB packet to determine if
 652 * the packet should be discarded right away.  If a response might be needed
 653 * for this packet, or, if further processing is possible, the packet will
 654 * be queued to a proper inqueue for the next phase of handling.
 655 *
 656 * Output:
 657 * Return 0 - If further processing is needed.
 658 * Return 1 - If the packet can be discarded right away.
 659 */
 660static int sctp_rcv_ootb(struct sk_buff *skb)
 661{
 662        sctp_chunkhdr_t *ch;
 663        __u8 *ch_end;
 664        sctp_errhdr_t *err;
 665
 666        ch = (sctp_chunkhdr_t *) skb->data;
 667
 668        /* Scan through all the chunks in the packet.  */
 669        do {
 670                /* Break out if chunk length is less then minimal. */
 671                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
 672                        break;
 673
 674                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 675                if (ch_end > skb_tail_pointer(skb))
 676                        break;
 677
 678                /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
 679                 * receiver MUST silently discard the OOTB packet and take no
 680                 * further action.
 681                 */
 682                if (SCTP_CID_ABORT == ch->type)
 683                        goto discard;
 684
 685                /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
 686                 * chunk, the receiver should silently discard the packet
 687                 * and take no further action.
 688                 */
 689                if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
 690                        goto discard;
 691
 692                /* RFC 4460, 2.11.2
 693                 * This will discard packets with INIT chunk bundled as
 694                 * subsequent chunks in the packet.  When INIT is first,
 695                 * the normal INIT processing will discard the chunk.
 696                 */
 697                if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
 698                        goto discard;
 699
 700                /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
 701                 * or a COOKIE ACK the SCTP Packet should be silently
 702                 * discarded.
 703                 */
 704                if (SCTP_CID_COOKIE_ACK == ch->type)
 705                        goto discard;
 706
 707                if (SCTP_CID_ERROR == ch->type) {
 708                        sctp_walk_errors(err, ch) {
 709                                if (SCTP_ERROR_STALE_COOKIE == err->cause)
 710                                        goto discard;
 711                        }
 712                }
 713
 714                ch = (sctp_chunkhdr_t *) ch_end;
 715        } while (ch_end < skb_tail_pointer(skb));
 716
 717        return 0;
 718
 719discard:
 720        return 1;
 721}
 722
 723/* Insert endpoint into the hash table.  */
 724static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
 725{
 726        struct sctp_ep_common *epb;
 727        struct sctp_hashbucket *head;
 728
 729        epb = &ep->base;
 730
 731        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
 732        head = &sctp_ep_hashtable[epb->hashent];
 733
 734        sctp_write_lock(&head->lock);
 735        hlist_add_head(&epb->node, &head->chain);
 736        sctp_write_unlock(&head->lock);
 737}
 738
 739/* Add an endpoint to the hash. Local BH-safe. */
 740void sctp_hash_endpoint(struct sctp_endpoint *ep)
 741{
 742        sctp_local_bh_disable();
 743        __sctp_hash_endpoint(ep);
 744        sctp_local_bh_enable();
 745}
 746
 747/* Remove endpoint from the hash table.  */
 748static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
 749{
 750        struct sctp_hashbucket *head;
 751        struct sctp_ep_common *epb;
 752
 753        epb = &ep->base;
 754
 755        if (hlist_unhashed(&epb->node))
 756                return;
 757
 758        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
 759
 760        head = &sctp_ep_hashtable[epb->hashent];
 761
 762        sctp_write_lock(&head->lock);
 763        __hlist_del(&epb->node);
 764        sctp_write_unlock(&head->lock);
 765}
 766
 767/* Remove endpoint from the hash.  Local BH-safe. */
 768void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 769{
 770        sctp_local_bh_disable();
 771        __sctp_unhash_endpoint(ep);
 772        sctp_local_bh_enable();
 773}
 774
 775/* Look up an endpoint. */
 776static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
 777{
 778        struct sctp_hashbucket *head;
 779        struct sctp_ep_common *epb;
 780        struct sctp_endpoint *ep;
 781        struct hlist_node *node;
 782        int hash;
 783
 784        hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
 785        head = &sctp_ep_hashtable[hash];
 786        read_lock(&head->lock);
 787        sctp_for_each_hentry(epb, node, &head->chain) {
 788                ep = sctp_ep(epb);
 789                if (sctp_endpoint_is_match(ep, laddr))
 790                        goto hit;
 791        }
 792
 793        ep = sctp_sk((sctp_get_ctl_sock()))->ep;
 794
 795hit:
 796        sctp_endpoint_hold(ep);
 797        read_unlock(&head->lock);
 798        return ep;
 799}
 800
 801/* Insert association into the hash table.  */
 802static void __sctp_hash_established(struct sctp_association *asoc)
 803{
 804        struct sctp_ep_common *epb;
 805        struct sctp_hashbucket *head;
 806
 807        epb = &asoc->base;
 808
 809        /* Calculate which chain this entry will belong to. */
 810        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
 811
 812        head = &sctp_assoc_hashtable[epb->hashent];
 813
 814        sctp_write_lock(&head->lock);
 815        hlist_add_head(&epb->node, &head->chain);
 816        sctp_write_unlock(&head->lock);
 817}
 818
 819/* Add an association to the hash. Local BH-safe. */
 820void sctp_hash_established(struct sctp_association *asoc)
 821{
 822        if (asoc->temp)
 823                return;
 824
 825        sctp_local_bh_disable();
 826        __sctp_hash_established(asoc);
 827        sctp_local_bh_enable();
 828}
 829
 830/* Remove association from the hash table.  */
 831static void __sctp_unhash_established(struct sctp_association *asoc)
 832{
 833        struct sctp_hashbucket *head;
 834        struct sctp_ep_common *epb;
 835
 836        epb = &asoc->base;
 837
 838        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
 839                                         asoc->peer.port);
 840
 841        head = &sctp_assoc_hashtable[epb->hashent];
 842
 843        sctp_write_lock(&head->lock);
 844        __hlist_del(&epb->node);
 845        sctp_write_unlock(&head->lock);
 846}
 847
 848/* Remove association from the hash table.  Local BH-safe. */
 849void sctp_unhash_established(struct sctp_association *asoc)
 850{
 851        if (asoc->temp)
 852                return;
 853
 854        sctp_local_bh_disable();
 855        __sctp_unhash_established(asoc);
 856        sctp_local_bh_enable();
 857}
 858
 859/* Look up an association. */
 860static struct sctp_association *__sctp_lookup_association(
 861                                        const union sctp_addr *local,
 862                                        const union sctp_addr *peer,
 863                                        struct sctp_transport **pt)
 864{
 865        struct sctp_hashbucket *head;
 866        struct sctp_ep_common *epb;
 867        struct sctp_association *asoc;
 868        struct sctp_transport *transport;
 869        struct hlist_node *node;
 870        int hash;
 871
 872        /* Optimize here for direct hit, only listening connections can
 873         * have wildcards anyways.
 874         */
 875        hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
 876        head = &sctp_assoc_hashtable[hash];
 877        read_lock(&head->lock);
 878        sctp_for_each_hentry(epb, node, &head->chain) {
 879                asoc = sctp_assoc(epb);
 880                transport = sctp_assoc_is_match(asoc, local, peer);
 881                if (transport)
 882                        goto hit;
 883        }
 884
 885        read_unlock(&head->lock);
 886
 887        return NULL;
 888
 889hit:
 890        *pt = transport;
 891        sctp_association_hold(asoc);
 892        read_unlock(&head->lock);
 893        return asoc;
 894}
 895
 896/* Look up an association. BH-safe. */
 897SCTP_STATIC
 898struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
 899                                                 const union sctp_addr *paddr,
 900                                            struct sctp_transport **transportp)
 901{
 902        struct sctp_association *asoc;
 903
 904        sctp_local_bh_disable();
 905        asoc = __sctp_lookup_association(laddr, paddr, transportp);
 906        sctp_local_bh_enable();
 907
 908        return asoc;
 909}
 910
 911/* Is there an association matching the given local and peer addresses? */
 912int sctp_has_association(const union sctp_addr *laddr,
 913                         const union sctp_addr *paddr)
 914{
 915        struct sctp_association *asoc;
 916        struct sctp_transport *transport;
 917
 918        if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
 919                sctp_association_put(asoc);
 920                return 1;
 921        }
 922
 923        return 0;
 924}
 925
 926/*
 927 * SCTP Implementors Guide, 2.18 Handling of address
 928 * parameters within the INIT or INIT-ACK.
 929 *
 930 * D) When searching for a matching TCB upon reception of an INIT
 931 *    or INIT-ACK chunk the receiver SHOULD use not only the
 932 *    source address of the packet (containing the INIT or
 933 *    INIT-ACK) but the receiver SHOULD also use all valid
 934 *    address parameters contained within the chunk.
 935 *
 936 * 2.18.3 Solution description
 937 *
 938 * This new text clearly specifies to an implementor the need
 939 * to look within the INIT or INIT-ACK. Any implementation that
 940 * does not do this, may not be able to establish associations
 941 * in certain circumstances.
 942 *
 943 */
 944static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
 945        const union sctp_addr *laddr, struct sctp_transport **transportp)
 946{
 947        struct sctp_association *asoc;
 948        union sctp_addr addr;
 949        union sctp_addr *paddr = &addr;
 950        struct sctphdr *sh = sctp_hdr(skb);
 951        sctp_chunkhdr_t *ch;
 952        union sctp_params params;
 953        sctp_init_chunk_t *init;
 954        struct sctp_transport *transport;
 955        struct sctp_af *af;
 956
 957        ch = (sctp_chunkhdr_t *) skb->data;
 958
 959        /*
 960         * This code will NOT touch anything inside the chunk--it is
 961         * strictly READ-ONLY.
 962         *
 963         * RFC 2960 3  SCTP packet Format
 964         *
 965         * Multiple chunks can be bundled into one SCTP packet up to
 966         * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
 967         * COMPLETE chunks.  These chunks MUST NOT be bundled with any
 968         * other chunk in a packet.  See Section 6.10 for more details
 969         * on chunk bundling.
 970         */
 971
 972        /* Find the start of the TLVs and the end of the chunk.  This is
 973         * the region we search for address parameters.
 974         */
 975        init = (sctp_init_chunk_t *)skb->data;
 976
 977        /* Walk the parameters looking for embedded addresses. */
 978        sctp_walk_params(params, init, init_hdr.params) {
 979
 980                /* Note: Ignoring hostname addresses. */
 981                af = sctp_get_af_specific(param_type2af(params.p->type));
 982                if (!af)
 983                        continue;
 984
 985                af->from_addr_param(paddr, params.addr, sh->source, 0);
 986
 987                asoc = __sctp_lookup_association(laddr, paddr, &transport);
 988                if (asoc)
 989                        return asoc;
 990        }
 991
 992        return NULL;
 993}
 994
 995/* ADD-IP, Section 5.2
 996 * When an endpoint receives an ASCONF Chunk from the remote peer
 997 * special procedures may be needed to identify the association the
 998 * ASCONF Chunk is associated with. To properly find the association
 999 * the following procedures SHOULD be followed:
1000 *
1001 * D2) If the association is not found, use the address found in the
1002 * Address Parameter TLV combined with the port number found in the
1003 * SCTP common header. If found proceed to rule D4.
1004 *
1005 * D2-ext) If more than one ASCONF Chunks are packed together, use the
1006 * address found in the ASCONF Address Parameter TLV of each of the
1007 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1008 */
1009static struct sctp_association *__sctp_rcv_asconf_lookup(
1010                                        sctp_chunkhdr_t *ch,
1011                                        const union sctp_addr *laddr,
1012                                        __be16 peer_port,
1013                                        struct sctp_transport **transportp)
1014{
1015        sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1016        struct sctp_af *af;
1017        union sctp_addr_param *param;
1018        union sctp_addr paddr;
1019
1020        /* Skip over the ADDIP header and find the Address parameter */
1021        param = (union sctp_addr_param *)(asconf + 1);
1022
1023        af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type));
1024        if (unlikely(!af))
1025                return NULL;
1026
1027        af->from_addr_param(&paddr, param, peer_port, 0);
1028
1029        return __sctp_lookup_association(laddr, &paddr, transportp);
1030}
1031
1032
1033/* SCTP-AUTH, Section 6.3:
1034*    If the receiver does not find a STCB for a packet containing an AUTH
1035*    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1036*    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1037*    association.
1038*
1039* This means that any chunks that can help us identify the association need
1040* to be looked at to find this assocation.
1041*/
1042static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1043                                      const union sctp_addr *laddr,
1044                                      struct sctp_transport **transportp)
1045{
1046        struct sctp_association *asoc = NULL;
1047        sctp_chunkhdr_t *ch;
1048        int have_auth = 0;
1049        unsigned int chunk_num = 1;
1050        __u8 *ch_end;
1051
1052        /* Walk through the chunks looking for AUTH or ASCONF chunks
1053         * to help us find the association.
1054         */
1055        ch = (sctp_chunkhdr_t *) skb->data;
1056        do {
1057                /* Break out if chunk length is less then minimal. */
1058                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1059                        break;
1060
1061                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1062                if (ch_end > skb_tail_pointer(skb))
1063                        break;
1064
1065                switch(ch->type) {
1066                    case SCTP_CID_AUTH:
1067                            have_auth = chunk_num;
1068                            break;
1069
1070                    case SCTP_CID_COOKIE_ECHO:
1071                            /* If a packet arrives containing an AUTH chunk as
1072                             * a first chunk, a COOKIE-ECHO chunk as the second
1073                             * chunk, and possibly more chunks after them, and
1074                             * the receiver does not have an STCB for that
1075                             * packet, then authentication is based on
1076                             * the contents of the COOKIE- ECHO chunk.
1077                             */
1078                            if (have_auth == 1 && chunk_num == 2)
1079                                    return NULL;
1080                            break;
1081
1082                    case SCTP_CID_ASCONF:
1083                            if (have_auth || sctp_addip_noauth)
1084                                    asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1085                                                        sctp_hdr(skb)->source,
1086                                                        transportp);
1087                    default:
1088                            break;
1089                }
1090
1091                if (asoc)
1092                        break;
1093
1094                ch = (sctp_chunkhdr_t *) ch_end;
1095                chunk_num++;
1096        } while (ch_end < skb_tail_pointer(skb));
1097
1098        return asoc;
1099}
1100
1101/*
1102 * There are circumstances when we need to look inside the SCTP packet
1103 * for information to help us find the association.   Examples
1104 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1105 * chunks.
1106 */
1107static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1108                                      const union sctp_addr *laddr,
1109                                      struct sctp_transport **transportp)
1110{
1111        sctp_chunkhdr_t *ch;
1112
1113        ch = (sctp_chunkhdr_t *) skb->data;
1114
1115        /* The code below will attempt to walk the chunk and extract
1116         * parameter information.  Before we do that, we need to verify
1117         * that the chunk length doesn't cause overflow.  Otherwise, we'll
1118         * walk off the end.
1119         */
1120        if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1121                return NULL;
1122
1123        /* If this is INIT/INIT-ACK look inside the chunk too. */
1124        switch (ch->type) {
1125        case SCTP_CID_INIT:
1126        case SCTP_CID_INIT_ACK:
1127                return __sctp_rcv_init_lookup(skb, laddr, transportp);
1128                break;
1129
1130        default:
1131                return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1132                break;
1133        }
1134
1135
1136        return NULL;
1137}
1138
1139/* Lookup an association for an inbound skb. */
1140static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1141                                      const union sctp_addr *paddr,
1142                                      const union sctp_addr *laddr,
1143                                      struct sctp_transport **transportp)
1144{
1145        struct sctp_association *asoc;
1146
1147        asoc = __sctp_lookup_association(laddr, paddr, transportp);
1148
1149        /* Further lookup for INIT/INIT-ACK packets.
1150         * SCTP Implementors Guide, 2.18 Handling of address
1151         * parameters within the INIT or INIT-ACK.
1152         */
1153        if (!asoc)
1154                asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1155
1156        return asoc;
1157}
1158