net/sctp/input.c

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This source file includes following definitions.
sctp_rcv_checksum
sctp_rcv
sctp_backlog_rcv
sctp_add_backlog
sctp_icmp_frag_needed
sctp_icmp_redirect
sctp_icmp_proto_unreachable
sctp_err_lookup
sctp_err_finish
sctp_v4_err
sctp_rcv_ootb
__sctp_hash_endpoint
sctp_hash_endpoint
__sctp_unhash_endpoint
sctp_unhash_endpoint
sctp_hashfn
__sctp_rcv_lookup_endpoint
sctp_hash_cmp
sctp_hash_obj
sctp_hash_key
sctp_transport_hashtable_init
sctp_transport_hashtable_destroy
sctp_hash_transport
sctp_unhash_transport
sctp_addrs_lookup_transport
sctp_epaddr_lookup_transport
__sctp_lookup_association
sctp_lookup_association
sctp_has_association
__sctp_rcv_init_lookup
__sctp_rcv_asconf_lookup
__sctp_rcv_walk_lookup
__sctp_rcv_lookup_harder
__sctp_rcv_lookup
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* SCTP kernel implementation
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 International Business Machines, Corp.
   6  * Copyright (c) 2001 Intel Corp.
   7  * Copyright (c) 2001 Nokia, Inc.
   8  * Copyright (c) 2001 La Monte H.P. Yarroll
   9  *
  10  * This file is part of the SCTP kernel implementation
  11  *
  12  * These functions handle all input from the IP layer into SCTP.
  13  *
  14  * Please send any bug reports or fixes you make to the
  15  * email address(es):
  16  *    lksctp developers <linux-sctp@vger.kernel.org>
  17  *
  18  * Written or modified by:
  19  *    La Monte H.P. Yarroll <piggy@acm.org>
  20  *    Karl Knutson <karl@athena.chicago.il.us>
  21  *    Xingang Guo <xingang.guo@intel.com>
  22  *    Jon Grimm <jgrimm@us.ibm.com>
  23  *    Hui Huang <hui.huang@nokia.com>
  24  *    Daisy Chang <daisyc@us.ibm.com>
  25  *    Sridhar Samudrala <sri@us.ibm.com>
  26  *    Ardelle Fan <ardelle.fan@intel.com>
  27  */
  28 
  29 #include <linux/types.h>
  30 #include <linux/list.h> /* For struct list_head */
  31 #include <linux/socket.h>
  32 #include <linux/ip.h>
  33 #include <linux/time.h> /* For struct timeval */
  34 #include <linux/slab.h>
  35 #include <net/ip.h>
  36 #include <net/icmp.h>
  37 #include <net/snmp.h>
  38 #include <net/sock.h>
  39 #include <net/xfrm.h>
  40 #include <net/sctp/sctp.h>
  41 #include <net/sctp/sm.h>
  42 #include <net/sctp/checksum.h>
  43 #include <net/net_namespace.h>
  44 #include <linux/rhashtable.h>
  45 #include <net/sock_reuseport.h>
  46 
  47 /* Forward declarations for internal helpers. */
  48 static int sctp_rcv_ootb(struct sk_buff *);
  49 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
  50                                       struct sk_buff *skb,
  51                                       const union sctp_addr *paddr,
  52                                       const union sctp_addr *laddr,
  53                                       struct sctp_transport **transportp);
  54 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
  55                                         struct net *net, struct sk_buff *skb,
  56                                         const union sctp_addr *laddr,
  57                                         const union sctp_addr *daddr);
  58 static struct sctp_association *__sctp_lookup_association(
  59                                         struct net *net,
  60                                         const union sctp_addr *local,
  61                                         const union sctp_addr *peer,
  62                                         struct sctp_transport **pt);
  63 
  64 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
  65 
  66 
  67 /* Calculate the SCTP checksum of an SCTP packet.  */
  68 static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
  69 {
  70         struct sctphdr *sh = sctp_hdr(skb);
  71         __le32 cmp = sh->checksum;
  72         __le32 val = sctp_compute_cksum(skb, 0);
  73 
  74         if (val != cmp) {
  75                 /* CRC failure, dump it. */
  76                 __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
  77                 return -1;
  78         }
  79         return 0;
  80 }
  81 
  82 /*
  83  * This is the routine which IP calls when receiving an SCTP packet.
  84  */
  85 int sctp_rcv(struct sk_buff *skb)
  86 {
  87         struct sock *sk;
  88         struct sctp_association *asoc;
  89         struct sctp_endpoint *ep = NULL;
  90         struct sctp_ep_common *rcvr;
  91         struct sctp_transport *transport = NULL;
  92         struct sctp_chunk *chunk;
  93         union sctp_addr src;
  94         union sctp_addr dest;
  95         int family;
  96         struct sctp_af *af;
  97         struct net *net = dev_net(skb->dev);
  98         bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb);
  99 
 100         if (skb->pkt_type != PACKET_HOST)
 101                 goto discard_it;
 102 
 103         __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
 104 
 105         /* If packet is too small to contain a single chunk, let's not
 106          * waste time on it anymore.
 107          */
 108         if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
 109                        skb_transport_offset(skb))
 110                 goto discard_it;
 111 
 112         /* If the packet is fragmented and we need to do crc checking,
 113          * it's better to just linearize it otherwise crc computing
 114          * takes longer.
 115          */
 116         if ((!is_gso && skb_linearize(skb)) ||
 117             !pskb_may_pull(skb, sizeof(struct sctphdr)))
 118                 goto discard_it;
 119 
 120         /* Pull up the IP header. */
 121         __skb_pull(skb, skb_transport_offset(skb));
 122 
 123         skb->csum_valid = 0; /* Previous value not applicable */
 124         if (skb_csum_unnecessary(skb))
 125                 __skb_decr_checksum_unnecessary(skb);
 126         else if (!sctp_checksum_disable &&
 127                  !is_gso &&
 128                  sctp_rcv_checksum(net, skb) < 0)
 129                 goto discard_it;
 130         skb->csum_valid = 1;
 131 
 132         __skb_pull(skb, sizeof(struct sctphdr));
 133 
 134         family = ipver2af(ip_hdr(skb)->version);
 135         af = sctp_get_af_specific(family);
 136         if (unlikely(!af))
 137                 goto discard_it;
 138         SCTP_INPUT_CB(skb)->af = af;
 139 
 140         /* Initialize local addresses for lookups. */
 141         af->from_skb(&src, skb, 1);
 142         af->from_skb(&dest, skb, 0);
 143 
 144         /* If the packet is to or from a non-unicast address,
 145          * silently discard the packet.
 146          *
 147          * This is not clearly defined in the RFC except in section
 148          * 8.4 - OOTB handling.  However, based on the book "Stream Control
 149          * Transmission Protocol" 2.1, "It is important to note that the
 150          * IP address of an SCTP transport address must be a routable
 151          * unicast address.  In other words, IP multicast addresses and
 152          * IP broadcast addresses cannot be used in an SCTP transport
 153          * address."
 154          */
 155         if (!af->addr_valid(&src, NULL, skb) ||
 156             !af->addr_valid(&dest, NULL, skb))
 157                 goto discard_it;
 158 
 159         asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
 160 
 161         if (!asoc)
 162                 ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src);
 163 
 164         /* Retrieve the common input handling substructure. */
 165         rcvr = asoc ? &asoc->base : &ep->base;
 166         sk = rcvr->sk;
 167 
 168         /*
 169          * If a frame arrives on an interface and the receiving socket is
 170          * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
 171          */
 172         if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
 173                 if (transport) {
 174                         sctp_transport_put(transport);
 175                         asoc = NULL;
 176                         transport = NULL;
 177                 } else {
 178                         sctp_endpoint_put(ep);
 179                         ep = NULL;
 180                 }
 181                 sk = net->sctp.ctl_sock;
 182                 ep = sctp_sk(sk)->ep;
 183                 sctp_endpoint_hold(ep);
 184                 rcvr = &ep->base;
 185         }
 186 
 187         /*
 188          * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 189          * An SCTP packet is called an "out of the blue" (OOTB)
 190          * packet if it is correctly formed, i.e., passed the
 191          * receiver's checksum check, but the receiver is not
 192          * able to identify the association to which this
 193          * packet belongs.
 194          */
 195         if (!asoc) {
 196                 if (sctp_rcv_ootb(skb)) {
 197                         __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
 198                         goto discard_release;
 199                 }
 200         }
 201 
 202         if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
 203                 goto discard_release;
 204         nf_reset_ct(skb);
 205 
 206         if (sk_filter(sk, skb))
 207                 goto discard_release;
 208 
 209         /* Create an SCTP packet structure. */
 210         chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
 211         if (!chunk)
 212                 goto discard_release;
 213         SCTP_INPUT_CB(skb)->chunk = chunk;
 214 
 215         /* Remember what endpoint is to handle this packet. */
 216         chunk->rcvr = rcvr;
 217 
 218         /* Remember the SCTP header. */
 219         chunk->sctp_hdr = sctp_hdr(skb);
 220 
 221         /* Set the source and destination addresses of the incoming chunk.  */
 222         sctp_init_addrs(chunk, &src, &dest);
 223 
 224         /* Remember where we came from.  */
 225         chunk->transport = transport;
 226 
 227         /* Acquire access to the sock lock. Note: We are safe from other
 228          * bottom halves on this lock, but a user may be in the lock too,
 229          * so check if it is busy.
 230          */
 231         bh_lock_sock(sk);
 232 
 233         if (sk != rcvr->sk) {
 234                 /* Our cached sk is different from the rcvr->sk.  This is
 235                  * because migrate()/accept() may have moved the association
 236                  * to a new socket and released all the sockets.  So now we
 237                  * are holding a lock on the old socket while the user may
 238                  * be doing something with the new socket.  Switch our veiw
 239                  * of the current sk.
 240                  */
 241                 bh_unlock_sock(sk);
 242                 sk = rcvr->sk;
 243                 bh_lock_sock(sk);
 244         }
 245 
 246         if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
 247                 if (sctp_add_backlog(sk, skb)) {
 248                         bh_unlock_sock(sk);
 249                         sctp_chunk_free(chunk);
 250                         skb = NULL; /* sctp_chunk_free already freed the skb */
 251                         goto discard_release;
 252                 }
 253                 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
 254         } else {
 255                 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
 256                 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
 257         }
 258 
 259         bh_unlock_sock(sk);
 260 
 261         /* Release the asoc/ep ref we took in the lookup calls. */
 262         if (transport)
 263                 sctp_transport_put(transport);
 264         else
 265                 sctp_endpoint_put(ep);
 266 
 267         return 0;
 268 
 269 discard_it:
 270         __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
 271         kfree_skb(skb);
 272         return 0;
 273 
 274 discard_release:
 275         /* Release the asoc/ep ref we took in the lookup calls. */
 276         if (transport)
 277                 sctp_transport_put(transport);
 278         else
 279                 sctp_endpoint_put(ep);
 280 
 281         goto discard_it;
 282 }
 283 
 284 /* Process the backlog queue of the socket.  Every skb on
 285  * the backlog holds a ref on an association or endpoint.
 286  * We hold this ref throughout the state machine to make
 287  * sure that the structure we need is still around.
 288  */
 289 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 290 {
 291         struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 292         struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
 293         struct sctp_transport *t = chunk->transport;
 294         struct sctp_ep_common *rcvr = NULL;
 295         int backloged = 0;
 296 
 297         rcvr = chunk->rcvr;
 298 
 299         /* If the rcvr is dead then the association or endpoint
 300          * has been deleted and we can safely drop the chunk
 301          * and refs that we are holding.
 302          */
 303         if (rcvr->dead) {
 304                 sctp_chunk_free(chunk);
 305                 goto done;
 306         }
 307 
 308         if (unlikely(rcvr->sk != sk)) {
 309                 /* In this case, the association moved from one socket to
 310                  * another.  We are currently sitting on the backlog of the
 311                  * old socket, so we need to move.
 312                  * However, since we are here in the process context we
 313                  * need to take make sure that the user doesn't own
 314                  * the new socket when we process the packet.
 315                  * If the new socket is user-owned, queue the chunk to the
 316                  * backlog of the new socket without dropping any refs.
 317                  * Otherwise, we can safely push the chunk on the inqueue.
 318                  */
 319 
 320                 sk = rcvr->sk;
 321                 local_bh_disable();
 322                 bh_lock_sock(sk);
 323 
 324                 if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
 325                         if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
 326                                 sctp_chunk_free(chunk);
 327                         else
 328                                 backloged = 1;
 329                 } else
 330                         sctp_inq_push(inqueue, chunk);
 331 
 332                 bh_unlock_sock(sk);
 333                 local_bh_enable();
 334 
 335                 /* If the chunk was backloged again, don't drop refs */
 336                 if (backloged)
 337                         return 0;
 338         } else {
 339                 if (!sctp_newsk_ready(sk)) {
 340                         if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
 341                                 return 0;
 342                         sctp_chunk_free(chunk);
 343                 } else {
 344                         sctp_inq_push(inqueue, chunk);
 345                 }
 346         }
 347 
 348 done:
 349         /* Release the refs we took in sctp_add_backlog */
 350         if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 351                 sctp_transport_put(t);
 352         else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 353                 sctp_endpoint_put(sctp_ep(rcvr));
 354         else
 355                 BUG();
 356 
 357         return 0;
 358 }
 359 
 360 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 361 {
 362         struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
 363         struct sctp_transport *t = chunk->transport;
 364         struct sctp_ep_common *rcvr = chunk->rcvr;
 365         int ret;
 366 
 367         ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
 368         if (!ret) {
 369                 /* Hold the assoc/ep while hanging on the backlog queue.
 370                  * This way, we know structures we need will not disappear
 371                  * from us
 372                  */
 373                 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
 374                         sctp_transport_hold(t);
 375                 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
 376                         sctp_endpoint_hold(sctp_ep(rcvr));
 377                 else
 378                         BUG();
 379         }
 380         return ret;
 381 
 382 }
 383 
 384 /* Handle icmp frag needed error. */
 385 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
 386                            struct sctp_transport *t, __u32 pmtu)
 387 {
 388         if (!t || (t->pathmtu <= pmtu))
 389                 return;
 390 
 391         if (sock_owned_by_user(sk)) {
 392                 atomic_set(&t->mtu_info, pmtu);
 393                 asoc->pmtu_pending = 1;
 394                 t->pmtu_pending = 1;
 395                 return;
 396         }
 397 
 398         if (!(t->param_flags & SPP_PMTUD_ENABLE))
 399                 /* We can't allow retransmitting in such case, as the
 400                  * retransmission would be sized just as before, and thus we
 401                  * would get another icmp, and retransmit again.
 402                  */
 403                 return;
 404 
 405         /* Update transports view of the MTU. Return if no update was needed.
 406          * If an update wasn't needed/possible, it also doesn't make sense to
 407          * try to retransmit now.
 408          */
 409         if (!sctp_transport_update_pmtu(t, pmtu))
 410                 return;
 411 
 412         /* Update association pmtu. */
 413         sctp_assoc_sync_pmtu(asoc);
 414 
 415         /* Retransmit with the new pmtu setting. */
 416         sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 417 }
 418 
 419 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
 420                         struct sk_buff *skb)
 421 {
 422         struct dst_entry *dst;
 423 
 424         if (sock_owned_by_user(sk) || !t)
 425                 return;
 426         dst = sctp_transport_dst_check(t);
 427         if (dst)
 428                 dst->ops->redirect(dst, sk, skb);
 429 }
 430 
 431 /*
 432  * SCTP Implementer's Guide, 2.37 ICMP handling procedures
 433  *
 434  * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
 435  *        or a "Protocol Unreachable" treat this message as an abort
 436  *        with the T bit set.
 437  *
 438  * This function sends an event to the state machine, which will abort the
 439  * association.
 440  *
 441  */
 442 void sctp_icmp_proto_unreachable(struct sock *sk,
 443                            struct sctp_association *asoc,
 444                            struct sctp_transport *t)
 445 {
 446         if (sock_owned_by_user(sk)) {
 447                 if (timer_pending(&t->proto_unreach_timer))
 448                         return;
 449                 else {
 450                         if (!mod_timer(&t->proto_unreach_timer,
 451                                                 jiffies + (HZ/20)))
 452                                 sctp_association_hold(asoc);
 453                 }
 454         } else {
 455                 struct net *net = sock_net(sk);
 456 
 457                 pr_debug("%s: unrecognized next header type "
 458                          "encountered!\n", __func__);
 459 
 460                 if (del_timer(&t->proto_unreach_timer))
 461                         sctp_association_put(asoc);
 462 
 463                 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
 464                            SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
 465                            asoc->state, asoc->ep, asoc, t,
 466                            GFP_ATOMIC);
 467         }
 468 }
 469 
 470 /* Common lookup code for icmp/icmpv6 error handler. */
 471 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
 472                              struct sctphdr *sctphdr,
 473                              struct sctp_association **app,
 474                              struct sctp_transport **tpp)
 475 {
 476         struct sctp_init_chunk *chunkhdr, _chunkhdr;
 477         union sctp_addr saddr;
 478         union sctp_addr daddr;
 479         struct sctp_af *af;
 480         struct sock *sk = NULL;
 481         struct sctp_association *asoc;
 482         struct sctp_transport *transport = NULL;
 483         __u32 vtag = ntohl(sctphdr->vtag);
 484 
 485         *app = NULL; *tpp = NULL;
 486 
 487         af = sctp_get_af_specific(family);
 488         if (unlikely(!af)) {
 489                 return NULL;
 490         }
 491 
 492         /* Initialize local addresses for lookups. */
 493         af->from_skb(&saddr, skb, 1);
 494         af->from_skb(&daddr, skb, 0);
 495 
 496         /* Look for an association that matches the incoming ICMP error
 497          * packet.
 498          */
 499         asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
 500         if (!asoc)
 501                 return NULL;
 502 
 503         sk = asoc->base.sk;
 504 
 505         /* RFC 4960, Appendix C. ICMP Handling
 506          *
 507          * ICMP6) An implementation MUST validate that the Verification Tag
 508          * contained in the ICMP message matches the Verification Tag of
 509          * the peer.  If the Verification Tag is not 0 and does NOT
 510          * match, discard the ICMP message.  If it is 0 and the ICMP
 511          * message contains enough bytes to verify that the chunk type is
 512          * an INIT chunk and that the Initiate Tag matches the tag of the
 513          * peer, continue with ICMP7.  If the ICMP message is too short
 514          * or the chunk type or the Initiate Tag does not match, silently
 515          * discard the packet.
 516          */
 517         if (vtag == 0) {
 518                 /* chunk header + first 4 octects of init header */
 519                 chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
 520                                               sizeof(struct sctphdr),
 521                                               sizeof(struct sctp_chunkhdr) +
 522                                               sizeof(__be32), &_chunkhdr);
 523                 if (!chunkhdr ||
 524                     chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
 525                     ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
 526                         goto out;
 527 
 528         } else if (vtag != asoc->c.peer_vtag) {
 529                 goto out;
 530         }
 531 
 532         bh_lock_sock(sk);
 533 
 534         /* If too many ICMPs get dropped on busy
 535          * servers this needs to be solved differently.
 536          */
 537         if (sock_owned_by_user(sk))
 538                 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 539 
 540         *app = asoc;
 541         *tpp = transport;
 542         return sk;
 543 
 544 out:
 545         sctp_transport_put(transport);
 546         return NULL;
 547 }
 548 
 549 /* Common cleanup code for icmp/icmpv6 error handler. */
 550 void sctp_err_finish(struct sock *sk, struct sctp_transport *t)
 551 {
 552         bh_unlock_sock(sk);
 553         sctp_transport_put(t);
 554 }
 555 
 556 /*
 557  * This routine is called by the ICMP module when it gets some
 558  * sort of error condition.  If err < 0 then the socket should
 559  * be closed and the error returned to the user.  If err > 0
 560  * it's just the icmp type << 8 | icmp code.  After adjustment
 561  * header points to the first 8 bytes of the sctp header.  We need
 562  * to find the appropriate port.
 563  *
 564  * The locking strategy used here is very "optimistic". When
 565  * someone else accesses the socket the ICMP is just dropped
 566  * and for some paths there is no check at all.
 567  * A more general error queue to queue errors for later handling
 568  * is probably better.
 569  *
 570  */
 571 int sctp_v4_err(struct sk_buff *skb, __u32 info)
 572 {
 573         const struct iphdr *iph = (const struct iphdr *)skb->data;
 574         const int ihlen = iph->ihl * 4;
 575         const int type = icmp_hdr(skb)->type;
 576         const int code = icmp_hdr(skb)->code;
 577         struct sock *sk;
 578         struct sctp_association *asoc = NULL;
 579         struct sctp_transport *transport;
 580         struct inet_sock *inet;
 581         __u16 saveip, savesctp;
 582         int err;
 583         struct net *net = dev_net(skb->dev);
 584 
 585         /* Fix up skb to look at the embedded net header. */
 586         saveip = skb->network_header;
 587         savesctp = skb->transport_header;
 588         skb_reset_network_header(skb);
 589         skb_set_transport_header(skb, ihlen);
 590         sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
 591         /* Put back, the original values. */
 592         skb->network_header = saveip;
 593         skb->transport_header = savesctp;
 594         if (!sk) {
 595                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 596                 return -ENOENT;
 597         }
 598         /* Warning:  The sock lock is held.  Remember to call
 599          * sctp_err_finish!
 600          */
 601 
 602         switch (type) {
 603         case ICMP_PARAMETERPROB:
 604                 err = EPROTO;
 605                 break;
 606         case ICMP_DEST_UNREACH:
 607                 if (code > NR_ICMP_UNREACH)
 608                         goto out_unlock;
 609 
 610                 /* PMTU discovery (RFC1191) */
 611                 if (ICMP_FRAG_NEEDED == code) {
 612                         sctp_icmp_frag_needed(sk, asoc, transport,
 613                                               SCTP_TRUNC4(info));
 614                         goto out_unlock;
 615                 } else {
 616                         if (ICMP_PROT_UNREACH == code) {
 617                                 sctp_icmp_proto_unreachable(sk, asoc,
 618                                                             transport);
 619                                 goto out_unlock;
 620                         }
 621                 }
 622                 err = icmp_err_convert[code].errno;
 623                 break;
 624         case ICMP_TIME_EXCEEDED:
 625                 /* Ignore any time exceeded errors due to fragment reassembly
 626                  * timeouts.
 627                  */
 628                 if (ICMP_EXC_FRAGTIME == code)
 629                         goto out_unlock;
 630 
 631                 err = EHOSTUNREACH;
 632                 break;
 633         case ICMP_REDIRECT:
 634                 sctp_icmp_redirect(sk, transport, skb);
 635                 /* Fall through to out_unlock. */
 636         default:
 637                 goto out_unlock;
 638         }
 639 
 640         inet = inet_sk(sk);
 641         if (!sock_owned_by_user(sk) && inet->recverr) {
 642                 sk->sk_err = err;
 643                 sk->sk_error_report(sk);
 644         } else {  /* Only an error on timeout */
 645                 sk->sk_err_soft = err;
 646         }
 647 
 648 out_unlock:
 649         sctp_err_finish(sk, transport);
 650         return 0;
 651 }
 652 
 653 /*
 654  * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
 655  *
 656  * This function scans all the chunks in the OOTB packet to determine if
 657  * the packet should be discarded right away.  If a response might be needed
 658  * for this packet, or, if further processing is possible, the packet will
 659  * be queued to a proper inqueue for the next phase of handling.
 660  *
 661  * Output:
 662  * Return 0 - If further processing is needed.
 663  * Return 1 - If the packet can be discarded right away.
 664  */
 665 static int sctp_rcv_ootb(struct sk_buff *skb)
 666 {
 667         struct sctp_chunkhdr *ch, _ch;
 668         int ch_end, offset = 0;
 669 
 670         /* Scan through all the chunks in the packet.  */
 671         do {
 672                 /* Make sure we have at least the header there */
 673                 if (offset + sizeof(_ch) > skb->len)
 674                         break;
 675 
 676                 ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
 677 
 678                 /* Break out if chunk length is less then minimal. */
 679                 if (ntohs(ch->length) < sizeof(_ch))
 680                         break;
 681 
 682                 ch_end = offset + SCTP_PAD4(ntohs(ch->length));
 683                 if (ch_end > skb->len)
 684                         break;
 685 
 686                 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
 687                  * receiver MUST silently discard the OOTB packet and take no
 688                  * further action.
 689                  */
 690                 if (SCTP_CID_ABORT == ch->type)
 691                         goto discard;
 692 
 693                 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
 694                  * chunk, the receiver should silently discard the packet
 695                  * and take no further action.
 696                  */
 697                 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
 698                         goto discard;
 699 
 700                 /* RFC 4460, 2.11.2
 701                  * This will discard packets with INIT chunk bundled as
 702                  * subsequent chunks in the packet.  When INIT is first,
 703                  * the normal INIT processing will discard the chunk.
 704                  */
 705                 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
 706                         goto discard;
 707 
 708                 offset = ch_end;
 709         } while (ch_end < skb->len);
 710 
 711         return 0;
 712 
 713 discard:
 714         return 1;
 715 }
 716 
 717 /* Insert endpoint into the hash table.  */
 718 static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
 719 {
 720         struct sock *sk = ep->base.sk;
 721         struct net *net = sock_net(sk);
 722         struct sctp_hashbucket *head;
 723         struct sctp_ep_common *epb;
 724 
 725         epb = &ep->base;
 726         epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
 727         head = &sctp_ep_hashtable[epb->hashent];
 728 
 729         if (sk->sk_reuseport) {
 730                 bool any = sctp_is_ep_boundall(sk);
 731                 struct sctp_ep_common *epb2;
 732                 struct list_head *list;
 733                 int cnt = 0, err = 1;
 734 
 735                 list_for_each(list, &ep->base.bind_addr.address_list)
 736                         cnt++;
 737 
 738                 sctp_for_each_hentry(epb2, &head->chain) {
 739                         struct sock *sk2 = epb2->sk;
 740 
 741                         if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
 742                             !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
 743                             !sk2->sk_reuseport)
 744                                 continue;
 745 
 746                         err = sctp_bind_addrs_check(sctp_sk(sk2),
 747                                                     sctp_sk(sk), cnt);
 748                         if (!err) {
 749                                 err = reuseport_add_sock(sk, sk2, any);
 750                                 if (err)
 751                                         return err;
 752                                 break;
 753                         } else if (err < 0) {
 754                                 return err;
 755                         }
 756                 }
 757 
 758                 if (err) {
 759                         err = reuseport_alloc(sk, any);
 760                         if (err)
 761                                 return err;
 762                 }
 763         }
 764 
 765         write_lock(&head->lock);
 766         hlist_add_head(&epb->node, &head->chain);
 767         write_unlock(&head->lock);
 768         return 0;
 769 }
 770 
 771 /* Add an endpoint to the hash. Local BH-safe. */
 772 int sctp_hash_endpoint(struct sctp_endpoint *ep)
 773 {
 774         int err;
 775 
 776         local_bh_disable();
 777         err = __sctp_hash_endpoint(ep);
 778         local_bh_enable();
 779 
 780         return err;
 781 }
 782 
 783 /* Remove endpoint from the hash table.  */
 784 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
 785 {
 786         struct sock *sk = ep->base.sk;
 787         struct sctp_hashbucket *head;
 788         struct sctp_ep_common *epb;
 789 
 790         epb = &ep->base;
 791 
 792         epb->hashent = sctp_ep_hashfn(sock_net(sk), epb->bind_addr.port);
 793 
 794         head = &sctp_ep_hashtable[epb->hashent];
 795 
 796         if (rcu_access_pointer(sk->sk_reuseport_cb))
 797                 reuseport_detach_sock(sk);
 798 
 799         write_lock(&head->lock);
 800         hlist_del_init(&epb->node);
 801         write_unlock(&head->lock);
 802 }
 803 
 804 /* Remove endpoint from the hash.  Local BH-safe. */
 805 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 806 {
 807         local_bh_disable();
 808         __sctp_unhash_endpoint(ep);
 809         local_bh_enable();
 810 }
 811 
 812 static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
 813                                 const union sctp_addr *paddr, __u32 seed)
 814 {
 815         __u32 addr;
 816 
 817         if (paddr->sa.sa_family == AF_INET6)
 818                 addr = jhash(&paddr->v6.sin6_addr, 16, seed);
 819         else
 820                 addr = (__force __u32)paddr->v4.sin_addr.s_addr;
 821 
 822         return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
 823                              (__force __u32)lport, net_hash_mix(net), seed);
 824 }
 825 
 826 /* Look up an endpoint. */
 827 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
 828                                         struct net *net, struct sk_buff *skb,
 829                                         const union sctp_addr *laddr,
 830                                         const union sctp_addr *paddr)
 831 {
 832         struct sctp_hashbucket *head;
 833         struct sctp_ep_common *epb;
 834         struct sctp_endpoint *ep;
 835         struct sock *sk;
 836         __be16 lport;
 837         int hash;
 838 
 839         lport = laddr->v4.sin_port;
 840         hash = sctp_ep_hashfn(net, ntohs(lport));
 841         head = &sctp_ep_hashtable[hash];
 842         read_lock(&head->lock);
 843         sctp_for_each_hentry(epb, &head->chain) {
 844                 ep = sctp_ep(epb);
 845                 if (sctp_endpoint_is_match(ep, net, laddr))
 846                         goto hit;
 847         }
 848 
 849         ep = sctp_sk(net->sctp.ctl_sock)->ep;
 850 
 851 hit:
 852         sk = ep->base.sk;
 853         if (sk->sk_reuseport) {
 854                 __u32 phash = sctp_hashfn(net, lport, paddr, 0);
 855 
 856                 sk = reuseport_select_sock(sk, phash, skb,
 857                                            sizeof(struct sctphdr));
 858                 if (sk)
 859                         ep = sctp_sk(sk)->ep;
 860         }
 861         sctp_endpoint_hold(ep);
 862         read_unlock(&head->lock);
 863         return ep;
 864 }
 865 
 866 /* rhashtable for transport */
 867 struct sctp_hash_cmp_arg {
 868         const union sctp_addr   *paddr;
 869         const struct net        *net;
 870         __be16                  lport;
 871 };
 872 
 873 static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
 874                                 const void *ptr)
 875 {
 876         struct sctp_transport *t = (struct sctp_transport *)ptr;
 877         const struct sctp_hash_cmp_arg *x = arg->key;
 878         int err = 1;
 879 
 880         if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
 881                 return err;
 882         if (!sctp_transport_hold(t))
 883                 return err;
 884 
 885         if (!net_eq(t->asoc->base.net, x->net))
 886                 goto out;
 887         if (x->lport != htons(t->asoc->base.bind_addr.port))
 888                 goto out;
 889 
 890         err = 0;
 891 out:
 892         sctp_transport_put(t);
 893         return err;
 894 }
 895 
 896 static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
 897 {
 898         const struct sctp_transport *t = data;
 899 
 900         return sctp_hashfn(t->asoc->base.net,
 901                            htons(t->asoc->base.bind_addr.port),
 902                            &t->ipaddr, seed);
 903 }
 904 
 905 static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
 906 {
 907         const struct sctp_hash_cmp_arg *x = data;
 908 
 909         return sctp_hashfn(x->net, x->lport, x->paddr, seed);
 910 }
 911 
 912 static const struct rhashtable_params sctp_hash_params = {
 913         .head_offset            = offsetof(struct sctp_transport, node),
 914         .hashfn                 = sctp_hash_key,
 915         .obj_hashfn             = sctp_hash_obj,
 916         .obj_cmpfn              = sctp_hash_cmp,
 917         .automatic_shrinking    = true,
 918 };
 919 
 920 int sctp_transport_hashtable_init(void)
 921 {
 922         return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
 923 }
 924 
 925 void sctp_transport_hashtable_destroy(void)
 926 {
 927         rhltable_destroy(&sctp_transport_hashtable);
 928 }
 929 
 930 int sctp_hash_transport(struct sctp_transport *t)
 931 {
 932         struct sctp_transport *transport;
 933         struct rhlist_head *tmp, *list;
 934         struct sctp_hash_cmp_arg arg;
 935         int err;
 936 
 937         if (t->asoc->temp)
 938                 return 0;
 939 
 940         arg.net   = sock_net(t->asoc->base.sk);
 941         arg.paddr = &t->ipaddr;
 942         arg.lport = htons(t->asoc->base.bind_addr.port);
 943 
 944         rcu_read_lock();
 945         list = rhltable_lookup(&sctp_transport_hashtable, &arg,
 946                                sctp_hash_params);
 947 
 948         rhl_for_each_entry_rcu(transport, tmp, list, node)
 949                 if (transport->asoc->ep == t->asoc->ep) {
 950                         rcu_read_unlock();
 951                         return -EEXIST;
 952                 }
 953         rcu_read_unlock();
 954 
 955         err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
 956                                   &t->node, sctp_hash_params);
 957         if (err)
 958                 pr_err_once("insert transport fail, errno %d\n", err);
 959 
 960         return err;
 961 }
 962 
 963 void sctp_unhash_transport(struct sctp_transport *t)
 964 {
 965         if (t->asoc->temp)
 966                 return;
 967 
 968         rhltable_remove(&sctp_transport_hashtable, &t->node,
 969                         sctp_hash_params);
 970 }
 971 
 972 /* return a transport with holding it */
 973 struct sctp_transport *sctp_addrs_lookup_transport(
 974                                 struct net *net,
 975                                 const union sctp_addr *laddr,
 976                                 const union sctp_addr *paddr)
 977 {
 978         struct rhlist_head *tmp, *list;
 979         struct sctp_transport *t;
 980         struct sctp_hash_cmp_arg arg = {
 981                 .paddr = paddr,
 982                 .net   = net,
 983                 .lport = laddr->v4.sin_port,
 984         };
 985 
 986         list = rhltable_lookup(&sctp_transport_hashtable, &arg,
 987                                sctp_hash_params);
 988 
 989         rhl_for_each_entry_rcu(t, tmp, list, node) {
 990                 if (!sctp_transport_hold(t))
 991                         continue;
 992 
 993                 if (sctp_bind_addr_match(&t->asoc->base.bind_addr,
 994                                          laddr, sctp_sk(t->asoc->base.sk)))
 995                         return t;
 996                 sctp_transport_put(t);
 997         }
 998 
 999         return NULL;
1000 }
1001 
1002 /* return a transport without holding it, as it's only used under sock lock */
1003 struct sctp_transport *sctp_epaddr_lookup_transport(
1004                                 const struct sctp_endpoint *ep,
1005                                 const union sctp_addr *paddr)
1006 {
1007         struct net *net = sock_net(ep->base.sk);
1008         struct rhlist_head *tmp, *list;
1009         struct sctp_transport *t;
1010         struct sctp_hash_cmp_arg arg = {
1011                 .paddr = paddr,
1012                 .net   = net,
1013                 .lport = htons(ep->base.bind_addr.port),
1014         };
1015 
1016         list = rhltable_lookup(&sctp_transport_hashtable, &arg,
1017                                sctp_hash_params);
1018 
1019         rhl_for_each_entry_rcu(t, tmp, list, node)
1020                 if (ep == t->asoc->ep)
1021                         return t;
1022 
1023         return NULL;
1024 }
1025 
1026 /* Look up an association. */
1027 static struct sctp_association *__sctp_lookup_association(
1028                                         struct net *net,
1029                                         const union sctp_addr *local,
1030                                         const union sctp_addr *peer,
1031                                         struct sctp_transport **pt)
1032 {
1033         struct sctp_transport *t;
1034         struct sctp_association *asoc = NULL;
1035 
1036         t = sctp_addrs_lookup_transport(net, local, peer);
1037         if (!t)
1038                 goto out;
1039 
1040         asoc = t->asoc;
1041         *pt = t;
1042 
1043 out:
1044         return asoc;
1045 }
1046 
1047 /* Look up an association. protected by RCU read lock */
1048 static
1049 struct sctp_association *sctp_lookup_association(struct net *net,
1050                                                  const union sctp_addr *laddr,
1051                                                  const union sctp_addr *paddr,
1052                                                  struct sctp_transport **transportp)
1053 {
1054         struct sctp_association *asoc;
1055 
1056         rcu_read_lock();
1057         asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1058         rcu_read_unlock();
1059 
1060         return asoc;
1061 }
1062 
1063 /* Is there an association matching the given local and peer addresses? */
1064 bool sctp_has_association(struct net *net,
1065                           const union sctp_addr *laddr,
1066                           const union sctp_addr *paddr)
1067 {
1068         struct sctp_transport *transport;
1069 
1070         if (sctp_lookup_association(net, laddr, paddr, &transport)) {
1071                 sctp_transport_put(transport);
1072                 return true;
1073         }
1074 
1075         return false;
1076 }
1077 
1078 /*
1079  * SCTP Implementors Guide, 2.18 Handling of address
1080  * parameters within the INIT or INIT-ACK.
1081  *
1082  * D) When searching for a matching TCB upon reception of an INIT
1083  *    or INIT-ACK chunk the receiver SHOULD use not only the
1084  *    source address of the packet (containing the INIT or
1085  *    INIT-ACK) but the receiver SHOULD also use all valid
1086  *    address parameters contained within the chunk.
1087  *
1088  * 2.18.3 Solution description
1089  *
1090  * This new text clearly specifies to an implementor the need
1091  * to look within the INIT or INIT-ACK. Any implementation that
1092  * does not do this, may not be able to establish associations
1093  * in certain circumstances.
1094  *
1095  */
1096 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
1097         struct sk_buff *skb,
1098         const union sctp_addr *laddr, struct sctp_transport **transportp)
1099 {
1100         struct sctp_association *asoc;
1101         union sctp_addr addr;
1102         union sctp_addr *paddr = &addr;
1103         struct sctphdr *sh = sctp_hdr(skb);
1104         union sctp_params params;
1105         struct sctp_init_chunk *init;
1106         struct sctp_af *af;
1107 
1108         /*
1109          * This code will NOT touch anything inside the chunk--it is
1110          * strictly READ-ONLY.
1111          *
1112          * RFC 2960 3  SCTP packet Format
1113          *
1114          * Multiple chunks can be bundled into one SCTP packet up to
1115          * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
1116          * COMPLETE chunks.  These chunks MUST NOT be bundled with any
1117          * other chunk in a packet.  See Section 6.10 for more details
1118          * on chunk bundling.
1119          */
1120 
1121         /* Find the start of the TLVs and the end of the chunk.  This is
1122          * the region we search for address parameters.
1123          */
1124         init = (struct sctp_init_chunk *)skb->data;
1125 
1126         /* Walk the parameters looking for embedded addresses. */
1127         sctp_walk_params(params, init, init_hdr.params) {
1128 
1129                 /* Note: Ignoring hostname addresses. */
1130                 af = sctp_get_af_specific(param_type2af(params.p->type));
1131                 if (!af)
1132                         continue;
1133 
1134                 af->from_addr_param(paddr, params.addr, sh->source, 0);
1135 
1136                 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1137                 if (asoc)
1138                         return asoc;
1139         }
1140 
1141         return NULL;
1142 }
1143 
1144 /* ADD-IP, Section 5.2
1145  * When an endpoint receives an ASCONF Chunk from the remote peer
1146  * special procedures may be needed to identify the association the
1147  * ASCONF Chunk is associated with. To properly find the association
1148  * the following procedures SHOULD be followed:
1149  *
1150  * D2) If the association is not found, use the address found in the
1151  * Address Parameter TLV combined with the port number found in the
1152  * SCTP common header. If found proceed to rule D4.
1153  *
1154  * D2-ext) If more than one ASCONF Chunks are packed together, use the
1155  * address found in the ASCONF Address Parameter TLV of each of the
1156  * subsequent ASCONF Chunks. If found, proceed to rule D4.
1157  */
1158 static struct sctp_association *__sctp_rcv_asconf_lookup(
1159                                         struct net *net,
1160                                         struct sctp_chunkhdr *ch,
1161                                         const union sctp_addr *laddr,
1162                                         __be16 peer_port,
1163                                         struct sctp_transport **transportp)
1164 {
1165         struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch;
1166         struct sctp_af *af;
1167         union sctp_addr_param *param;
1168         union sctp_addr paddr;
1169 
1170         /* Skip over the ADDIP header and find the Address parameter */
1171         param = (union sctp_addr_param *)(asconf + 1);
1172 
1173         af = sctp_get_af_specific(param_type2af(param->p.type));
1174         if (unlikely(!af))
1175                 return NULL;
1176 
1177         af->from_addr_param(&paddr, param, peer_port, 0);
1178 
1179         return __sctp_lookup_association(net, laddr, &paddr, transportp);
1180 }
1181 
1182 
1183 /* SCTP-AUTH, Section 6.3:
1184 *    If the receiver does not find a STCB for a packet containing an AUTH
1185 *    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1186 *    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1187 *    association.
1188 *
1189 * This means that any chunks that can help us identify the association need
1190 * to be looked at to find this association.
1191 */
1192 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1193                                       struct sk_buff *skb,
1194                                       const union sctp_addr *laddr,
1195                                       struct sctp_transport **transportp)
1196 {
1197         struct sctp_association *asoc = NULL;
1198         struct sctp_chunkhdr *ch;
1199         int have_auth = 0;
1200         unsigned int chunk_num = 1;
1201         __u8 *ch_end;
1202 
1203         /* Walk through the chunks looking for AUTH or ASCONF chunks
1204          * to help us find the association.
1205          */
1206         ch = (struct sctp_chunkhdr *)skb->data;
1207         do {
1208                 /* Break out if chunk length is less then minimal. */
1209                 if (ntohs(ch->length) < sizeof(*ch))
1210                         break;
1211 
1212                 ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
1213                 if (ch_end > skb_tail_pointer(skb))
1214                         break;
1215 
1216                 switch (ch->type) {
1217                 case SCTP_CID_AUTH:
1218                         have_auth = chunk_num;
1219                         break;
1220 
1221                 case SCTP_CID_COOKIE_ECHO:
1222                         /* If a packet arrives containing an AUTH chunk as
1223                          * a first chunk, a COOKIE-ECHO chunk as the second
1224                          * chunk, and possibly more chunks after them, and
1225                          * the receiver does not have an STCB for that
1226                          * packet, then authentication is based on
1227                          * the contents of the COOKIE- ECHO chunk.
1228                          */
1229                         if (have_auth == 1 && chunk_num == 2)
1230                                 return NULL;
1231                         break;
1232 
1233                 case SCTP_CID_ASCONF:
1234                         if (have_auth || net->sctp.addip_noauth)
1235                                 asoc = __sctp_rcv_asconf_lookup(
1236                                                 net, ch, laddr,
1237                                                 sctp_hdr(skb)->source,
1238                                                 transportp);
1239                 default:
1240                         break;
1241                 }
1242 
1243                 if (asoc)
1244                         break;
1245 
1246                 ch = (struct sctp_chunkhdr *)ch_end;
1247                 chunk_num++;
1248         } while (ch_end < skb_tail_pointer(skb));
1249 
1250         return asoc;
1251 }
1252 
1253 /*
1254  * There are circumstances when we need to look inside the SCTP packet
1255  * for information to help us find the association.   Examples
1256  * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1257  * chunks.
1258  */
1259 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1260                                       struct sk_buff *skb,
1261                                       const union sctp_addr *laddr,
1262                                       struct sctp_transport **transportp)
1263 {
1264         struct sctp_chunkhdr *ch;
1265 
1266         /* We do not allow GSO frames here as we need to linearize and
1267          * then cannot guarantee frame boundaries. This shouldn't be an
1268          * issue as packets hitting this are mostly INIT or INIT-ACK and
1269          * those cannot be on GSO-style anyway.
1270          */
1271         if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
1272                 return NULL;
1273 
1274         ch = (struct sctp_chunkhdr *)skb->data;
1275 
1276         /* The code below will attempt to walk the chunk and extract
1277          * parameter information.  Before we do that, we need to verify
1278          * that the chunk length doesn't cause overflow.  Otherwise, we'll
1279          * walk off the end.
1280          */
1281         if (SCTP_PAD4(ntohs(ch->length)) > skb->len)
1282                 return NULL;
1283 
1284         /* If this is INIT/INIT-ACK look inside the chunk too. */
1285         if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1286                 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1287 
1288         return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1289 }
1290 
1291 /* Lookup an association for an inbound skb. */
1292 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1293                                       struct sk_buff *skb,
1294                                       const union sctp_addr *paddr,
1295                                       const union sctp_addr *laddr,
1296                                       struct sctp_transport **transportp)
1297 {
1298         struct sctp_association *asoc;
1299 
1300         asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1301         if (asoc)
1302                 goto out;
1303 
1304         /* Further lookup for INIT/INIT-ACK packets.
1305          * SCTP Implementors Guide, 2.18 Handling of address
1306          * parameters within the INIT or INIT-ACK.
1307          */
1308         asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
1309         if (asoc)
1310                 goto out;
1311 
1312         if (paddr->sa.sa_family == AF_INET)
1313                 pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n",
1314                          &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port),
1315                          &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port));
1316         else
1317                 pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n",
1318                          &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port),
1319                          &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port));
1320 
1321 out:
1322         return asoc;
1323 }
/* [<][>][^][v][top][bottom][index][help] */
root/net/sctp/input.c

DEFINITIONS
