bsd/netinet6/ip6_forward.c

   1 /*      $FreeBSD: src/sys/netinet6/ip6_forward.c,v 1.16 2002/10/16 02:25:05 sam Exp $   */
   2 /*      $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $    */
   3
   4 /*
   5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the project nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/malloc.h>
  37 #include <sys/mbuf.h>
  38 #include <sys/domain.h>
  39 #include <sys/protosw.h>
  40 #include <sys/socket.h>
  41 #include <sys/errno.h>
  42 #include <sys/time.h>
  43 #include <sys/kernel.h>
  44 #include <sys/syslog.h>
  45
  46 #include <net/if.h>
  47 #include <net/route.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/in_var.h>
  51 #include <netinet/in_systm.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet6/in6_var.h>
  55 #include <netinet/ip6.h>
  56 #include <netinet6/ip6_var.h>
  57 #include <netinet/icmp6.h>
  58 #include <netinet6/nd6.h>
  59
  60 #include <netinet/in_pcb.h>
  61
  62 #if IPSEC
  63 #include <netinet6/ipsec.h>
  64 #if INET6
  65 #include <netinet6/ipsec6.h>
  66 #endif
  67 #include <netkey/key.h>
  68 extern int ipsec_bypass;
  69 extern lck_mtx_t *sadb_mutex;
  70 extern lck_mtx_t *ip6_mutex;
  71 #endif /* IPSEC */
  72
  73 #include <netinet6/ip6_fw.h>
  74
  75 #include <net/net_osdep.h>
  76
  77 struct  route_in6 ip6_forward_rt;
  78
  79 /*
  80  * Forward a packet.  If some error occurs return the sender
  81  * an icmp packet.  Note we can't always generate a meaningful
  82  * icmp message because icmp doesn't have a large enough repertoire
  83  * of codes and types.
  84  *
  85  * If not forwarding, just drop the packet.  This could be confusing
  86  * if ipforwarding was zero but some routing protocol was advancing
  87  * us as a gateway to somewhere.  However, we must let the routing
  88  * protocol deal with that.
  89  *
  90  */
  91
  92 void
  93 ip6_forward(m, srcrt, locked)
  94         struct mbuf *m;
  95         int srcrt;
  96         int locked;
  97 {
  98         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  99         struct sockaddr_in6 *dst;
 100         struct rtentry *rt;
 101         int error, type = 0, code = 0;
 102         struct mbuf *mcopy = NULL;
 103         struct ifnet *origifp;  /* maybe unnecessary */
 104 #if IPSEC
 105         struct secpolicy *sp = NULL;
 106 #endif
 107         struct timeval timenow;
 108
 109         getmicrotime(&timenow);
 110
 111
 112 #if IPSEC
 113         /*
 114          * Check AH/ESP integrity.
 115          */
 116         /*
 117          * Don't increment ip6s_cantforward because this is the check
 118          * before forwarding packet actually.
 119          */
 120         if (ipsec_bypass == 0) {
 121                 lck_mtx_lock(sadb_mutex);
 122                 if (ipsec6_in_reject(m, NULL)) {
 123                         ipsec6stat.in_polvio++;
 124                         lck_mtx_unlock(sadb_mutex);
 125                         m_freem(m);
 126                         return;
 127                 }
 128                 lck_mtx_unlock(sadb_mutex);
 129         }
 130 #endif /*IPSEC*/
 131
 132         /*
 133          * Do not forward packets to multicast destination (should be handled
 134          * by ip6_mforward().
 135          * Do not forward packets with unspecified source.  It was discussed
 136          * in July 2000, on ipngwg mailing list.
 137          */
 138         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
 139             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
 140             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
 141                 ip6stat.ip6s_cantforward++;
 142                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
 143                 if (ip6_log_time + ip6_log_interval < timenow.tv_sec) {
 144                         ip6_log_time = timenow.tv_sec;
 145                         log(LOG_DEBUG,
 146                             "cannot forward "
 147                             "from %s to %s nxt %d received on %s\n",
 148                             ip6_sprintf(&ip6->ip6_src),
 149                             ip6_sprintf(&ip6->ip6_dst),
 150                             ip6->ip6_nxt,
 151                             if_name(m->m_pkthdr.rcvif));
 152                 }
 153                 m_freem(m);
 154                 return;
 155         }
 156
 157         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
 158                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
 159                 if (locked)
 160                         lck_mtx_unlock(ip6_mutex);
 161                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
 162                                 ICMP6_TIME_EXCEED_TRANSIT, 0);
 163                 if (locked)
 164                         lck_mtx_lock(ip6_mutex);
 165                 return;
 166         }
 167         ip6->ip6_hlim -= IPV6_HLIMDEC;
 168
 169         /*
 170          * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
 171          * size of IPv6 + ICMPv6 headers) bytes of the packet in case
 172          * we need to generate an ICMP6 message to the src.
 173          * Thanks to M_EXT, in most cases copy will not occur.
 174          *
 175          * It is important to save it before IPsec processing as IPsec
 176          * processing may modify the mbuf.
 177          */
 178         mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
 179
 180 #if IPSEC
 181         if (ipsec_bypass != 0)
 182                 goto skip_ipsec;
 183         lck_mtx_lock(sadb_mutex);
 184         /* get a security policy for this packet */
 185         sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
 186             &error);
 187         if (sp == NULL) {
 188                 ipsec6stat.out_inval++;
 189                 ip6stat.ip6s_cantforward++;
 190                 if (mcopy) {
 191 #if 0
 192                         /* XXX: what icmp ? */
 193 #else
 194                         m_freem(mcopy);
 195 #endif
 196                 }
 197                 lck_mtx_unlock(sadb_mutex);
 198                 m_freem(m);
 199                 return;
 200         }
 201
 202         error = 0;
 203
 204         /* check policy */
 205         switch (sp->policy) {
 206         case IPSEC_POLICY_DISCARD:
 207                 /*
 208                  * This packet is just discarded.
 209                  */
 210                 ipsec6stat.out_polvio++;
 211                 ip6stat.ip6s_cantforward++;
 212                 key_freesp(sp);
 213                 if (mcopy) {
 214 #if 0
 215                         /* XXX: what icmp ? */
 216 #else
 217                         m_freem(mcopy);
 218 #endif
 219                 }
 220                 lck_mtx_unlock(sadb_mutex);
 221                 m_freem(m);
 222                 return;
 223
 224         case IPSEC_POLICY_BYPASS:
 225         case IPSEC_POLICY_NONE:
 226                 /* no need to do IPsec. */
 227                 key_freesp(sp);
 228                 lck_mtx_unlock(sadb_mutex);
 229                 goto skip_ipsec;
 230
 231         case IPSEC_POLICY_IPSEC:
 232                 if (sp->req == NULL) {
 233                         /* XXX should be panic ? */
 234                         printf("ip6_forward: No IPsec request specified.\n");
 235                         ip6stat.ip6s_cantforward++;
 236                         key_freesp(sp);
 237                         if (mcopy) {
 238 #if 0
 239                                 /* XXX: what icmp ? */
 240 #else
 241                                 m_freem(mcopy);
 242 #endif
 243                         }
 244                         lck_mtx_unlock(sadb_mutex);
 245                         m_freem(m);
 246                         return;
 247                 }
 248                 /* do IPsec */
 249                 break;
 250
 251         case IPSEC_POLICY_ENTRUST:
 252         default:
 253                 /* should be panic ?? */
 254                 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
 255                 key_freesp(sp);
 256                 lck_mtx_unlock(sadb_mutex);
 257                 goto skip_ipsec;
 258         }
 259
 260     {
 261         struct ipsec_output_state state;
 262
 263         /*
 264          * All the extension headers will become inaccessible
 265          * (since they can be encrypted).
 266          * Don't panic, we need no more updates to extension headers
 267          * on inner IPv6 packet (since they are now encapsulated).
 268          *
 269          * IPv6 [ESP|AH] IPv6 [extension headers] payload
 270          */
 271         bzero(&state, sizeof(state));
 272         state.m = m;
 273         state.ro = NULL;        /* update at ipsec6_output_tunnel() */
 274         state.dst = NULL;       /* update at ipsec6_output_tunnel() */
 275
 276         error = ipsec6_output_tunnel(&state, sp, 0);
 277
 278         m = state.m;
 279         key_freesp(sp);
 280
 281         if (error) {
 282                 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
 283                 switch (error) {
 284                 case EHOSTUNREACH:
 285                 case ENETUNREACH:
 286                 case EMSGSIZE:
 287                 case ENOBUFS:
 288                 case ENOMEM:
 289                         break;
 290                 default:
 291                         printf("ip6_output (ipsec): error code %d\n", error);
 292                         /* fall through */
 293                 case ENOENT:
 294                         /* don't show these error codes to the user */
 295                         break;
 296                 }
 297                 ip6stat.ip6s_cantforward++;
 298                 if (mcopy) {
 299 #if 0
 300                         /* XXX: what icmp ? */
 301 #else
 302                         m_freem(mcopy);
 303 #endif
 304                 }
 305                 lck_mtx_unlock(sadb_mutex);
 306                 m_freem(m);
 307                 return;
 308         }
 309     }
 310         lck_mtx_unlock(sadb_mutex);
 311     skip_ipsec:
 312 #endif /* IPSEC */
 313
 314         dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
 315         if (!srcrt) {
 316                 /*
 317                  * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
 318                  */
 319                 if (ip6_forward_rt.ro_rt == 0 ||
 320                     (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
 321                         if (ip6_forward_rt.ro_rt) {
 322                                 rtfree(ip6_forward_rt.ro_rt);
 323                                 ip6_forward_rt.ro_rt = 0;
 324                         }
 325                         /* this probably fails but give it a try again */
 326                         rtalloc_ign((struct route *)&ip6_forward_rt,
 327                                     RTF_PRCLONING);
 328                 }
 329
 330                 if (ip6_forward_rt.ro_rt == 0) {
 331                         ip6stat.ip6s_noroute++;
 332                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
 333                         if (mcopy) {
 334                                 if (locked)
 335                                         lck_mtx_unlock(ip6_mutex);
 336                                 icmp6_error(mcopy, ICMP6_DST_UNREACH,
 337                                             ICMP6_DST_UNREACH_NOROUTE, 0);
 338                                 if (locked)
 339                                         lck_mtx_lock(ip6_mutex);
 340                         }
 341                         m_freem(m);
 342                         return;
 343                 }
 344         } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
 345                  !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
 346                 if (ip6_forward_rt.ro_rt) {
 347                         rtfree(ip6_forward_rt.ro_rt);
 348                         ip6_forward_rt.ro_rt = 0;
 349                 }
 350                 bzero(dst, sizeof(*dst));
 351                 dst->sin6_len = sizeof(struct sockaddr_in6);
 352                 dst->sin6_family = AF_INET6;
 353                 dst->sin6_addr = ip6->ip6_dst;
 354
 355                 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
 356                 if (ip6_forward_rt.ro_rt == 0) {
 357                         ip6stat.ip6s_noroute++;
 358                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
 359                         if (mcopy) {
 360                                 if (locked)
 361                                         lck_mtx_unlock(ip6_mutex);
 362                                 icmp6_error(mcopy, ICMP6_DST_UNREACH,
 363                                             ICMP6_DST_UNREACH_NOROUTE, 0);
 364                                 if (locked)
 365                                         lck_mtx_lock(ip6_mutex);
 366                         }
 367                         m_freem(m);
 368                         return;
 369                 }
 370         }
 371         rt = ip6_forward_rt.ro_rt;
 372
 373         /*
 374          * Scope check: if a packet can't be delivered to its destination
 375          * for the reason that the destination is beyond the scope of the
 376          * source address, discard the packet and return an icmp6 destination
 377          * unreachable error with Code 2 (beyond scope of source address).
 378          * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
 379          */
 380         if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
 381             in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
 382                 ip6stat.ip6s_cantforward++;
 383                 ip6stat.ip6s_badscope++;
 384                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
 385
 386                 if (ip6_log_time + ip6_log_interval < timenow.tv_sec) {
 387                         ip6_log_time = timenow.tv_sec;
 388                         log(LOG_DEBUG,
 389                             "cannot forward "
 390                             "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
 391                             ip6_sprintf(&ip6->ip6_src),
 392                             ip6_sprintf(&ip6->ip6_dst),
 393                             ip6->ip6_nxt,
 394                             if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
 395                 }
 396                 if (mcopy) {
 397                         if (locked)
 398                                 lck_mtx_unlock(ip6_mutex);
 399                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
 400                                     ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
 401                         if (locked)
 402                                 lck_mtx_lock(ip6_mutex);
 403                 }
 404                 m_freem(m);
 405                 return;
 406         }
 407
 408         if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
 409                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
 410                 if (mcopy) {
 411                         u_long mtu;
 412 #if IPSEC
 413                         struct secpolicy *sp;
 414                         int ipsecerror;
 415                         size_t ipsechdrsiz;
 416 #endif
 417
 418                         mtu = rt->rt_ifp->if_mtu;
 419 #if IPSEC
 420                         /*
 421                          * When we do IPsec tunnel ingress, we need to play
 422                          * with if_mtu value (decrement IPsec header size
 423                          * from mtu value).  The code is much simpler than v4
 424                          * case, as we have the outgoing interface for
 425                          * encapsulated packet as "rt->rt_ifp".
 426                          */
 427                         lck_mtx_lock(sadb_mutex);
 428                         sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
 429                                 IP_FORWARDING, &ipsecerror);
 430                         if (sp) {
 431                                 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
 432                                         IPSEC_DIR_OUTBOUND, NULL);
 433                                 if (ipsechdrsiz < mtu)
 434                                         mtu -= ipsechdrsiz;
 435                         }
 436                         lck_mtx_unlock(sadb_mutex);
 437                         /*
 438                          * if mtu becomes less than minimum MTU,
 439                          * tell minimum MTU (and I'll need to fragment it).
 440                          */
 441                         if (mtu < IPV6_MMTU)
 442                                 mtu = IPV6_MMTU;
 443 #endif
 444                         if (locked)
 445                                 lck_mtx_unlock(ip6_mutex);
 446                         icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
 447                         if (locked)
 448                                 lck_mtx_lock(ip6_mutex);
 449                 }
 450                 m_freem(m);
 451                 return;
 452         }
 453
 454         if (rt->rt_flags & RTF_GATEWAY)
 455                 dst = (struct sockaddr_in6 *)rt->rt_gateway;
 456
 457         /*
 458          * If we are to forward the packet using the same interface
 459          * as one we got the packet from, perhaps we should send a redirect
 460          * to sender to shortcut a hop.
 461          * Only send redirect if source is sending directly to us,
 462          * and if packet was not source routed (or has any options).
 463          * Also, don't send redirect if forwarding using a route
 464          * modified by a redirect.
 465          */
 466         if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
 467             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
 468                 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
 469                         /*
 470                          * If the incoming interface is equal to the outgoing
 471                          * one, and the link attached to the interface is
 472                          * point-to-point, then it will be highly probable
 473                          * that a routing loop occurs. Thus, we immediately
 474                          * drop the packet and send an ICMPv6 error message.
 475                          *
 476                          * type/code is based on suggestion by Rich Draves.
 477                          * not sure if it is the best pick.
 478                          */
 479                         if (locked)
 480                                 lck_mtx_unlock(ip6_mutex);
 481                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
 482                                     ICMP6_DST_UNREACH_ADDR, 0);
 483                         if (locked)
 484                                 lck_mtx_lock(ip6_mutex);
 485                         m_freem(m);
 486                         return;
 487                 }
 488                 type = ND_REDIRECT;
 489         }
 490
 491         /*
 492          * Check with the firewall...
 493          */
 494         if (ip6_fw_enable && ip6_fw_chk_ptr) {
 495                 u_short port = 0;
 496                 /* If ipfw says divert, we have to just drop packet */
 497                 if (ip6_fw_chk_ptr(&ip6, rt->rt_ifp, &port, &m)) {
 498                         m_freem(m);
 499                         goto freecopy;
 500                 }
 501                 if (!m)
 502                         goto freecopy;
 503         }
 504
 505         /*
 506          * Fake scoped addresses. Note that even link-local source or
 507          * destinaion can appear, if the originating node just sends the
 508          * packet to us (without address resolution for the destination).
 509          * Since both icmp6_error and icmp6_redirect_output fill the embedded
 510          * link identifiers, we can do this stuff after making a copy for
 511          * returning an error.
 512          */
 513         if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
 514                 /*
 515                  * See corresponding comments in ip6_output.
 516                  * XXX: but is it possible that ip6_forward() sends a packet
 517                  *      to a loopback interface? I don't think so, and thus
 518                  *      I bark here. (jinmei@kame.net)
 519                  * XXX: it is common to route invalid packets to loopback.
 520                  *      also, the codepath will be visited on use of ::1 in
 521                  *      rthdr. (itojun)
 522                  */
 523 #if 1
 524                 if (0)
 525 #else
 526                 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
 527 #endif
 528                 {
 529                         printf("ip6_forward: outgoing interface is loopback. "
 530                                 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
 531                                 ip6_sprintf(&ip6->ip6_src),
 532                                 ip6_sprintf(&ip6->ip6_dst),
 533                                 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
 534                                 if_name(rt->rt_ifp));
 535                 }
 536
 537                 /* we can just use rcvif in forwarding. */
 538                 origifp = m->m_pkthdr.rcvif;
 539         }
 540         else
 541                 origifp = rt->rt_ifp;
 542 #ifndef SCOPEDROUTING
 543         /*
 544          * clear embedded scope identifiers if necessary.
 545          * in6_clearscope will touch the addresses only when necessary.
 546          */
 547         in6_clearscope(&ip6->ip6_src);
 548         in6_clearscope(&ip6->ip6_dst);
 549 #endif
 550
 551         error = nd6_output(rt->rt_ifp, origifp, m, dst, rt, locked);
 552         if (error) {
 553                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
 554                 ip6stat.ip6s_cantforward++;
 555         } else {
 556                 ip6stat.ip6s_forward++;
 557                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
 558                 if (type)
 559                         ip6stat.ip6s_redirectsent++;
 560                 else {
 561                         if (mcopy)
 562                                 goto freecopy;
 563                 }
 564         }
 565         if (mcopy == NULL)
 566                 return;
 567
 568         switch (error) {
 569         case 0:
 570 #if 1
 571                 if (type == ND_REDIRECT) {
 572                         icmp6_redirect_output(mcopy, rt);
 573                         return;
 574                 }
 575 #endif
 576                 goto freecopy;
 577
 578         case EMSGSIZE:
 579                 /* xxx MTU is constant in PPP? */
 580                 goto freecopy;
 581
 582         case ENOBUFS:
 583                 /* Tell source to slow down like source quench in IP? */
 584                 goto freecopy;
 585
 586         case ENETUNREACH:       /* shouldn't happen, checked above */
 587         case EHOSTUNREACH:
 588         case ENETDOWN:
 589         case EHOSTDOWN:
 590         default:
 591                 type = ICMP6_DST_UNREACH;
 592                 code = ICMP6_DST_UNREACH_ADDR;
 593                 break;
 594         }
 595         if (locked)
 596                 lck_mtx_unlock(ip6_mutex);
 597         icmp6_error(mcopy, type, code, 0);
 598         if (locked)
 599                 lck_mtx_lock(ip6_mutex);
 600         return;
 601
 602  freecopy:
 603         m_freem(mcopy);
 604         return;
 605 }