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 IS_ENABLED(CONFIG_IPV6)
 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, sk->sk_rcvbuf))
 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, sk->sk_rcvbuf);
 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(sk, t, pmtu);
 412
 413                /* Update association pmtu. */
 414                sctp_assoc_sync_pmtu(sk, 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
 426void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
 427                        struct sk_buff *skb)
 428{
 429        struct dst_entry *dst;
 430
 431        if (!t)
 432                return;
 433        dst = sctp_transport_dst_check(t);
 434        if (dst)
 435                dst->ops->redirect(dst, sk, skb);
 436}
 437
 438/*
 439 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
 440 *
 441 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
 442 *        or a "Protocol Unreachable" treat this message as an abort
 443 *        with the T bit set.
 444 *
 445 * This function sends an event to the state machine, which will abort the
 446 * association.
 447 *
 448 */
 449void sctp_icmp_proto_unreachable(struct sock *sk,
 450                           struct sctp_association *asoc,
 451                           struct sctp_transport *t)
 452{
 453        SCTP_DEBUG_PRINTK("%s\n",  __func__);
 454
 455        if (sock_owned_by_user(sk)) {
 456                if (timer_pending(&t->proto_unreach_timer))
 457                        return;
 458                else {
 459                        if (!mod_timer(&t->proto_unreach_timer,
 460                                                jiffies + (HZ/20)))
 461                                sctp_association_hold(asoc);
 462                }
 463                        
 464        } else {
 465                if (timer_pending(&t->proto_unreach_timer) &&
 466                    del_timer(&t->proto_unreach_timer))
 467                        sctp_association_put(asoc);
 468
 469                sctp_do_sm(SCTP_EVENT_T_OTHER,
 470                           SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
 471                           asoc->state, asoc->ep, asoc, t,
 472                           GFP_ATOMIC);
 473        }
 474}
 475
 476/* Common lookup code for icmp/icmpv6 error handler. */
 477struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
 478                             struct sctphdr *sctphdr,
 479                             struct sctp_association **app,
 480                             struct sctp_transport **tpp)
 481{
 482        union sctp_addr saddr;
 483        union sctp_addr daddr;
 484        struct sctp_af *af;
 485        struct sock *sk = NULL;
 486        struct sctp_association *asoc;
 487        struct sctp_transport *transport = NULL;
 488        struct sctp_init_chunk *chunkhdr;
 489        __u32 vtag = ntohl(sctphdr->vtag);
 490        int len = skb->len - ((void *)sctphdr - (void *)skb->data);
 491
 492        *app = NULL; *tpp = NULL;
 493
 494        af = sctp_get_af_specific(family);
 495        if (unlikely(!af)) {
 496                return NULL;
 497        }
 498
 499        /* Initialize local addresses for lookups. */
 500        af->from_skb(&saddr, skb, 1);
 501        af->from_skb(&daddr, skb, 0);
 502
 503        /* Look for an association that matches the incoming ICMP error
 504         * packet.
 505         */
 506        asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
 507        if (!asoc)
 508                return NULL;
 509
 510        sk = asoc->base.sk;
 511
 512        /* RFC 4960, Appendix C. ICMP Handling
 513         *
 514         * ICMP6) An implementation MUST validate that the Verification Tag
 515         * contained in the ICMP message matches the Verification Tag of
 516         * the peer.  If the Verification Tag is not 0 and does NOT
 517         * match, discard the ICMP message.  If it is 0 and the ICMP
 518         * message contains enough bytes to verify that the chunk type is
 519         * an INIT chunk and that the Initiate Tag matches the tag of the
 520         * peer, continue with ICMP7.  If the ICMP message is too short
 521         * or the chunk type or the Initiate Tag does not match, silently
 522         * discard the packet.
 523         */
 524        if (vtag == 0) {
 525                chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
 526                if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
 527                          + sizeof(__be32) ||
 528                    chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
 529                    ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
 530                        goto out;
 531                }
 532        } else if (vtag != asoc->c.peer_vtag) {
 533                goto out;
 534        }
 535
 536        sctp_bh_lock_sock(sk);
 537
 538        /* If too many ICMPs get dropped on busy
 539         * servers this needs to be solved differently.
 540         */
 541        if (sock_owned_by_user(sk))
 542                NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
 543
 544        *app = asoc;
 545        *tpp = transport;
 546        return sk;
 547
 548out:
 549        if (asoc)
 550                sctp_association_put(asoc);
 551        return NULL;
 552}
 553
 554/* Common cleanup code for icmp/icmpv6 error handler. */
 555void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
 556{
 557        sctp_bh_unlock_sock(sk);
 558        if (asoc)
 559                sctp_association_put(asoc);
 560}
 561
 562/*
 563 * This routine is called by the ICMP module when it gets some
 564 * sort of error condition.  If err < 0 then the socket should
 565 * be closed and the error returned to the user.  If err > 0
 566 * it's just the icmp type << 8 | icmp code.  After adjustment
 567 * header points to the first 8 bytes of the sctp header.  We need
 568 * to find the appropriate port.
 569 *
 570 * The locking strategy used here is very "optimistic". When
 571 * someone else accesses the socket the ICMP is just dropped
 572 * and for some paths there is no check at all.
 573 * A more general error queue to queue errors for later handling
 574 * is probably better.
 575 *
 576 */
 577void sctp_v4_err(struct sk_buff *skb, __u32 info)
 578{
 579        const struct iphdr *iph = (const struct iphdr *)skb->data;
 580        const int ihlen = iph->ihl * 4;
 581        const int type = icmp_hdr(skb)->type;
 582        const int code = icmp_hdr(skb)->code;
 583        struct sock *sk;
 584        struct sctp_association *asoc = NULL;
 585        struct sctp_transport *transport;
 586        struct inet_sock *inet;
 587        sk_buff_data_t saveip, savesctp;
 588        int err;
 589
 590        if (skb->len < ihlen + 8) {
 591                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 592                return;
 593        }
 594
 595        /* Fix up skb to look at the embedded net header. */
 596        saveip = skb->network_header;
 597        savesctp = skb->transport_header;
 598        skb_reset_network_header(skb);
 599        skb_set_transport_header(skb, ihlen);
 600        sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
 601        /* Put back, the original values. */
 602        skb->network_header = saveip;
 603        skb->transport_header = savesctp;
 604        if (!sk) {
 605                ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
 606                return;
 607        }
 608        /* Warning:  The sock lock is held.  Remember to call
 609         * sctp_err_finish!
 610         */
 611
 612        switch (type) {
 613        case ICMP_PARAMETERPROB:
 614                err = EPROTO;
 615                break;
 616        case ICMP_DEST_UNREACH:
 617                if (code > NR_ICMP_UNREACH)
 618                        goto out_unlock;
 619
 620                /* PMTU discovery (RFC1191) */
 621                if (ICMP_FRAG_NEEDED == code) {
 622                        sctp_icmp_frag_needed(sk, asoc, transport, info);
 623                        goto out_unlock;
 624                }
 625                else {
 626                        if (ICMP_PROT_UNREACH == code) {
 627                                sctp_icmp_proto_unreachable(sk, asoc,
 628                                                            transport);
 629                                goto out_unlock;
 630                        }
 631                }
 632                err = icmp_err_convert[code].errno;
 633                break;
 634        case ICMP_TIME_EXCEEDED:
 635                /* Ignore any time exceeded errors due to fragment reassembly
 636                 * timeouts.
 637                 */
 638                if (ICMP_EXC_FRAGTIME == code)
 639                        goto out_unlock;
 640
 641                err = EHOSTUNREACH;
 642                break;
 643        case ICMP_REDIRECT:
 644                sctp_icmp_redirect(sk, transport, skb);
 645                err = 0;
 646                break;
 647        default:
 648                goto out_unlock;
 649        }
 650
 651        inet = inet_sk(sk);
 652        if (!sock_owned_by_user(sk) && inet->recverr) {
 653                sk->sk_err = err;
 654                sk->sk_error_report(sk);
 655        } else {  /* Only an error on timeout */
 656                sk->sk_err_soft = err;
 657        }
 658
 659out_unlock:
 660        sctp_err_finish(sk, asoc);
 661}
 662
 663/*
 664 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 665 *
 666 * This function scans all the chunks in the OOTB packet to determine if
 667 * the packet should be discarded right away.  If a response might be needed
 668 * for this packet, or, if further processing is possible, the packet will
 669 * be queued to a proper inqueue for the next phase of handling.
 670 *
 671 * Output:
 672 * Return 0 - If further processing is needed.
 673 * Return 1 - If the packet can be discarded right away.
 674 */
 675static int sctp_rcv_ootb(struct sk_buff *skb)
 676{
 677        sctp_chunkhdr_t *ch;
 678        __u8 *ch_end;
 679
 680        ch = (sctp_chunkhdr_t *) skb->data;
 681
 682        /* Scan through all the chunks in the packet.  */
 683        do {
 684                /* Break out if chunk length is less then minimal. */
 685                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
 686                        break;
 687
 688                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 689                if (ch_end > skb_tail_pointer(skb))
 690                        break;
 691
 692                /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
 693                 * receiver MUST silently discard the OOTB packet and take no
 694                 * further action.
 695                 */
 696                if (SCTP_CID_ABORT == ch->type)
 697                        goto discard;
 698
 699                /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
 700                 * chunk, the receiver should silently discard the packet
 701                 * and take no further action.
 702                 */
 703                if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
 704                        goto discard;
 705
 706                /* RFC 4460, 2.11.2
 707                 * This will discard packets with INIT chunk bundled as
 708                 * subsequent chunks in the packet.  When INIT is first,
 709                 * the normal INIT processing will discard the chunk.
 710                 */
 711                if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
 712                        goto discard;
 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        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
 756
 757        head = &sctp_ep_hashtable[epb->hashent];
 758
 759        sctp_write_lock(&head->lock);
 760        hlist_del_init(&epb->node);
 761        sctp_write_unlock(&head->lock);
 762}
 763
 764/* Remove endpoint from the hash.  Local BH-safe. */
 765void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 766{
 767        sctp_local_bh_disable();
 768        __sctp_unhash_endpoint(ep);
 769        sctp_local_bh_enable();
 770}
 771
 772/* Look up an endpoint. */
 773static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
 774{
 775        struct sctp_hashbucket *head;
 776        struct sctp_ep_common *epb;
 777        struct sctp_endpoint *ep;
 778        struct hlist_node *node;
 779        int hash;
 780
 781        hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
 782        head = &sctp_ep_hashtable[hash];
 783        read_lock(&head->lock);
 784        sctp_for_each_hentry(epb, node, &head->chain) {
 785                ep = sctp_ep(epb);
 786                if (sctp_endpoint_is_match(ep, laddr))
 787                        goto hit;
 788        }
 789
 790        ep = sctp_sk((sctp_get_ctl_sock()))->ep;
 791
 792hit:
 793        sctp_endpoint_hold(ep);
 794        read_unlock(&head->lock);
 795        return ep;
 796}
 797
 798/* Insert association into the hash table.  */
 799static void __sctp_hash_established(struct sctp_association *asoc)
 800{
 801        struct sctp_ep_common *epb;
 802        struct sctp_hashbucket *head;
 803
 804        epb = &asoc->base;
 805
 806        /* Calculate which chain this entry will belong to. */
 807        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
 808
 809        head = &sctp_assoc_hashtable[epb->hashent];
 810
 811        sctp_write_lock(&head->lock);
 812        hlist_add_head(&epb->node, &head->chain);
 813        sctp_write_unlock(&head->lock);
 814}
 815
 816/* Add an association to the hash. Local BH-safe. */
 817void sctp_hash_established(struct sctp_association *asoc)
 818{
 819        if (asoc->temp)
 820                return;
 821
 822        sctp_local_bh_disable();
 823        __sctp_hash_established(asoc);
 824        sctp_local_bh_enable();
 825}
 826
 827/* Remove association from the hash table.  */
 828static void __sctp_unhash_established(struct sctp_association *asoc)
 829{
 830        struct sctp_hashbucket *head;
 831        struct sctp_ep_common *epb;
 832
 833        epb = &asoc->base;
 834
 835        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
 836                                         asoc->peer.port);
 837
 838        head = &sctp_assoc_hashtable[epb->hashent];
 839
 840        sctp_write_lock(&head->lock);
 841        hlist_del_init(&epb->node);
 842        sctp_write_unlock(&head->lock);
 843}
 844
 845/* Remove association from the hash table.  Local BH-safe. */
 846void sctp_unhash_established(struct sctp_association *asoc)
 847{
 848        if (asoc->temp)
 849                return;
 850
 851        sctp_local_bh_disable();
 852        __sctp_unhash_established(asoc);
 853        sctp_local_bh_enable();
 854}
 855
 856/* Look up an association. */
 857static struct sctp_association *__sctp_lookup_association(
 858                                        const union sctp_addr *local,
 859                                        const union sctp_addr *peer,
 860                                        struct sctp_transport **pt)
 861{
 862        struct sctp_hashbucket *head;
 863        struct sctp_ep_common *epb;
 864        struct sctp_association *asoc;
 865        struct sctp_transport *transport;
 866        struct hlist_node *node;
 867        int hash;
 868
 869        /* Optimize here for direct hit, only listening connections can
 870         * have wildcards anyways.
 871         */
 872        hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
 873        head = &sctp_assoc_hashtable[hash];
 874        read_lock(&head->lock);
 875        sctp_for_each_hentry(epb, node, &head->chain) {
 876                asoc = sctp_assoc(epb);
 877                transport = sctp_assoc_is_match(asoc, local, peer);
 878                if (transport)
 879                        goto hit;
 880        }
 881
 882        read_unlock(&head->lock);
 883
 884        return NULL;
 885
 886hit:
 887        *pt = transport;
 888        sctp_association_hold(asoc);
 889        read_unlock(&head->lock);
 890        return asoc;
 891}
 892
 893/* Look up an association. BH-safe. */
 894SCTP_STATIC
 895struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
 896                                                 const union sctp_addr *paddr,
 897                                            struct sctp_transport **transportp)
 898{
 899        struct sctp_association *asoc;
 900
 901        sctp_local_bh_disable();
 902        asoc = __sctp_lookup_association(laddr, paddr, transportp);
 903        sctp_local_bh_enable();
 904
 905        return asoc;
 906}
 907
 908/* Is there an association matching the given local and peer addresses? */
 909int sctp_has_association(const union sctp_addr *laddr,
 910                         const union sctp_addr *paddr)
 911{
 912        struct sctp_association *asoc;
 913        struct sctp_transport *transport;
 914
 915        if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
 916                sctp_association_put(asoc);
 917                return 1;
 918        }
 919
 920        return 0;
 921}
 922
 923/*
 924 * SCTP Implementors Guide, 2.18 Handling of address
 925 * parameters within the INIT or INIT-ACK.
 926 *
 927 * D) When searching for a matching TCB upon reception of an INIT
 928 *    or INIT-ACK chunk the receiver SHOULD use not only the
 929 *    source address of the packet (containing the INIT or
 930 *    INIT-ACK) but the receiver SHOULD also use all valid
 931 *    address parameters contained within the chunk.
 932 *
 933 * 2.18.3 Solution description
 934 *
 935 * This new text clearly specifies to an implementor the need
 936 * to look within the INIT or INIT-ACK. Any implementation that
 937 * does not do this, may not be able to establish associations
 938 * in certain circumstances.
 939 *
 940 */
 941static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
 942        const union sctp_addr *laddr, struct sctp_transport **transportp)
 943{
 944        struct sctp_association *asoc;
 945        union sctp_addr addr;
 946        union sctp_addr *paddr = &addr;
 947        struct sctphdr *sh = sctp_hdr(skb);
 948        union sctp_params params;
 949        sctp_init_chunk_t *init;
 950        struct sctp_transport *transport;
 951        struct sctp_af *af;
 952
 953        /*
 954         * This code will NOT touch anything inside the chunk--it is
 955         * strictly READ-ONLY.
 956         *
 957         * RFC 2960 3  SCTP packet Format
 958         *
 959         * Multiple chunks can be bundled into one SCTP packet up to
 960         * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
 961         * COMPLETE chunks.  These chunks MUST NOT be bundled with any
 962         * other chunk in a packet.  See Section 6.10 for more details
 963         * on chunk bundling.
 964         */
 965
 966        /* Find the start of the TLVs and the end of the chunk.  This is
 967         * the region we search for address parameters.
 968         */
 969        init = (sctp_init_chunk_t *)skb->data;
 970
 971        /* Walk the parameters looking for embedded addresses. */
 972        sctp_walk_params(params, init, init_hdr.params) {
 973
 974                /* Note: Ignoring hostname addresses. */
 975                af = sctp_get_af_specific(param_type2af(params.p->type));
 976                if (!af)
 977                        continue;
 978
 979                af->from_addr_param(paddr, params.addr, sh->source, 0);
 980
 981                asoc = __sctp_lookup_association(laddr, paddr, &transport);
 982                if (asoc)
 983                        return asoc;
 984        }
 985
 986        return NULL;
 987}
 988
 989/* ADD-IP, Section 5.2
 990 * When an endpoint receives an ASCONF Chunk from the remote peer
 991 * special procedures may be needed to identify the association the
 992 * ASCONF Chunk is associated with. To properly find the association
 993 * the following procedures SHOULD be followed:
 994 *
 995 * D2) If the association is not found, use the address found in the
 996 * Address Parameter TLV combined with the port number found in the
 997 * SCTP common header. If found proceed to rule D4.
 998 *
 999 * D2-ext) If more than one ASCONF Chunks are packed together, use the
1000 * address found in the ASCONF Address Parameter TLV of each of the
1001 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1002 */
1003static struct sctp_association *__sctp_rcv_asconf_lookup(
1004                                        sctp_chunkhdr_t *ch,
1005                                        const union sctp_addr *laddr,
1006                                        __be16 peer_port,
1007                                        struct sctp_transport **transportp)
1008{
1009        sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1010        struct sctp_af *af;
1011        union sctp_addr_param *param;
1012        union sctp_addr paddr;
1013
1014        /* Skip over the ADDIP header and find the Address parameter */
1015        param = (union sctp_addr_param *)(asconf + 1);
1016
1017        af = sctp_get_af_specific(param_type2af(param->p.type));
1018        if (unlikely(!af))
1019                return NULL;
1020
1021        af->from_addr_param(&paddr, param, peer_port, 0);
1022
1023        return __sctp_lookup_association(laddr, &paddr, transportp);
1024}
1025
1026
1027/* SCTP-AUTH, Section 6.3:
1028*    If the receiver does not find a STCB for a packet containing an AUTH
1029*    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1030*    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1031*    association.
1032*
1033* This means that any chunks that can help us identify the association need
1034* to be looked at to find this association.
1035*/
1036static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1037                                      const union sctp_addr *laddr,
1038                                      struct sctp_transport **transportp)
1039{
1040        struct sctp_association *asoc = NULL;
1041        sctp_chunkhdr_t *ch;
1042        int have_auth = 0;
1043        unsigned int chunk_num = 1;
1044        __u8 *ch_end;
1045
1046        /* Walk through the chunks looking for AUTH or ASCONF chunks
1047         * to help us find the association.
1048         */
1049        ch = (sctp_chunkhdr_t *) skb->data;
1050        do {
1051                /* Break out if chunk length is less then minimal. */
1052                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1053                        break;
1054
1055                ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1056                if (ch_end > skb_tail_pointer(skb))
1057                        break;
1058
1059                switch(ch->type) {
1060                    case SCTP_CID_AUTH:
1061                            have_auth = chunk_num;
1062                            break;
1063
1064                    case SCTP_CID_COOKIE_ECHO:
1065                            /* If a packet arrives containing an AUTH chunk as
1066                             * a first chunk, a COOKIE-ECHO chunk as the second
1067                             * chunk, and possibly more chunks after them, and
1068                             * the receiver does not have an STCB for that
1069                             * packet, then authentication is based on
1070                             * the contents of the COOKIE- ECHO chunk.
1071                             */
1072                            if (have_auth == 1 && chunk_num == 2)
1073                                    return NULL;
1074                            break;
1075
1076                    case SCTP_CID_ASCONF:
1077                            if (have_auth || sctp_addip_noauth)
1078                                    asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1079                                                        sctp_hdr(skb)->source,
1080                                                        transportp);
1081                    default:
1082                            break;
1083                }
1084
1085                if (asoc)
1086                        break;
1087
1088                ch = (sctp_chunkhdr_t *) ch_end;
1089                chunk_num++;
1090        } while (ch_end < skb_tail_pointer(skb));
1091
1092        return asoc;
1093}
1094
1095/*
1096 * There are circumstances when we need to look inside the SCTP packet
1097 * for information to help us find the association.   Examples
1098 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1099 * chunks.
1100 */
1101static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1102                                      const union sctp_addr *laddr,
1103                                      struct sctp_transport **transportp)
1104{
1105        sctp_chunkhdr_t *ch;
1106
1107        ch = (sctp_chunkhdr_t *) skb->data;
1108
1109        /* The code below will attempt to walk the chunk and extract
1110         * parameter information.  Before we do that, we need to verify
1111         * that the chunk length doesn't cause overflow.  Otherwise, we'll
1112         * walk off the end.
1113         */
1114        if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1115                return NULL;
1116
1117        /* If this is INIT/INIT-ACK look inside the chunk too. */
1118        switch (ch->type) {
1119        case SCTP_CID_INIT:
1120        case SCTP_CID_INIT_ACK:
1121                return __sctp_rcv_init_lookup(skb, laddr, transportp);
1122                break;
1123
1124        default:
1125                return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1126                break;
1127        }
1128
1129
1130        return NULL;
1131}
1132
1133/* Lookup an association for an inbound skb. */
1134static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1135                                      const union sctp_addr *paddr,
1136                                      const union sctp_addr *laddr,
1137                                      struct sctp_transport **transportp)
1138{
1139        struct sctp_association *asoc;
1140
1141        asoc = __sctp_lookup_association(laddr, paddr, transportp);
1142
1143        /* Further lookup for INIT/INIT-ACK packets.
1144         * SCTP Implementors Guide, 2.18 Handling of address
1145         * parameters within the INIT or INIT-ACK.
1146         */
1147        if (!asoc)
1148                asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1149
1150        return asoc;
1151}
1152
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