The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_forward.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/11.0/sys/netinet6/ip6_forward.c 301717 2016-06-09 05:48:34Z ae $");
   34 
   35 #include "opt_inet.h"
   36 #include "opt_inet6.h"
   37 #include "opt_ipsec.h"
   38 #include "opt_ipstealth.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/malloc.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/domain.h>
   45 #include <sys/protosw.h>
   46 #include <sys/socket.h>
   47 #include <sys/errno.h>
   48 #include <sys/time.h>
   49 #include <sys/kernel.h>
   50 #include <sys/syslog.h>
   51 
   52 #include <net/if.h>
   53 #include <net/if_var.h>
   54 #include <net/netisr.h>
   55 #include <net/route.h>
   56 #include <net/pfil.h>
   57 
   58 #include <netinet/in.h>
   59 #include <netinet/in_var.h>
   60 #include <netinet/in_systm.h>
   61 #include <netinet/ip.h>
   62 #include <netinet/ip_var.h>
   63 #include <netinet6/in6_var.h>
   64 #include <netinet/ip6.h>
   65 #include <netinet6/ip6_var.h>
   66 #include <netinet6/scope6_var.h>
   67 #include <netinet/icmp6.h>
   68 #include <netinet6/nd6.h>
   69 
   70 #include <netinet/in_pcb.h>
   71 
   72 #ifdef IPSEC
   73 #include <netinet6/ip6_ipsec.h>
   74 #include <netipsec/ipsec.h>
   75 #include <netipsec/ipsec6.h>
   76 #include <netipsec/key.h>
   77 #endif /* IPSEC */
   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 void
   92 ip6_forward(struct mbuf *m, int srcrt)
   93 {
   94         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
   95         struct sockaddr_in6 *dst = NULL;
   96         struct rtentry *rt = NULL;
   97         struct route_in6 rin6;
   98         int error, type = 0, code = 0;
   99         struct mbuf *mcopy = NULL;
  100         struct ifnet *origifp;  /* maybe unnecessary */
  101         u_int32_t inzone, outzone;
  102         struct in6_addr src_in6, dst_in6, odst;
  103 #ifdef IPSEC
  104         struct secpolicy *sp = NULL;
  105 #endif
  106 #ifdef SCTP
  107         int sw_csum;
  108 #endif
  109         struct m_tag *fwd_tag;
  110         char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
  111 
  112         /*
  113          * Do not forward packets to multicast destination (should be handled
  114          * by ip6_mforward().
  115          * Do not forward packets with unspecified source.  It was discussed
  116          * in July 2000, on the ipngwg mailing list.
  117          */
  118         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
  119             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
  120             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
  121                 IP6STAT_INC(ip6s_cantforward);
  122                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  123                 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
  124                         V_ip6_log_time = time_uptime;
  125                         log(LOG_DEBUG,
  126                             "cannot forward "
  127                             "from %s to %s nxt %d received on %s\n",
  128                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  129                             ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  130                             ip6->ip6_nxt,
  131                             if_name(m->m_pkthdr.rcvif));
  132                 }
  133                 m_freem(m);
  134                 return;
  135         }
  136 #ifdef IPSEC
  137         /*
  138          * Check if this packet has an active SA and needs to be dropped
  139          * instead of forwarded.
  140          */
  141         if (ip6_ipsec_fwd(m) != 0) {
  142                 IP6STAT_INC(ip6s_cantforward);
  143                 m_freem(m);
  144                 return;
  145         }
  146 #endif /* IPSEC */
  147 
  148 #ifdef IPSTEALTH
  149         if (!V_ip6stealth) {
  150 #endif
  151         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
  152                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  153                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
  154                                 ICMP6_TIME_EXCEED_TRANSIT, 0);
  155                 return;
  156         }
  157         ip6->ip6_hlim -= IPV6_HLIMDEC;
  158 
  159 #ifdef IPSTEALTH
  160         }
  161 #endif
  162 
  163         /*
  164          * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
  165          * size of IPv6 + ICMPv6 headers) bytes of the packet in case
  166          * we need to generate an ICMP6 message to the src.
  167          * Thanks to M_EXT, in most cases copy will not occur.
  168          *
  169          * It is important to save it before IPsec processing as IPsec
  170          * processing may modify the mbuf.
  171          */
  172         mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
  173 
  174 #ifdef IPSEC
  175         /* get a security policy for this packet */
  176         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, &error);
  177         if (sp == NULL) {
  178                 IPSEC6STAT_INC(ips_out_inval);
  179                 IP6STAT_INC(ip6s_cantforward);
  180                 if (mcopy) {
  181 #if 0
  182                         /* XXX: what icmp ? */
  183 #else
  184                         m_freem(mcopy);
  185 #endif
  186                 }
  187                 m_freem(m);
  188                 return;
  189         }
  190 
  191         error = 0;
  192 
  193         /* check policy */
  194         switch (sp->policy) {
  195         case IPSEC_POLICY_DISCARD:
  196                 /*
  197                  * This packet is just discarded.
  198                  */
  199                 IPSEC6STAT_INC(ips_out_polvio);
  200                 IP6STAT_INC(ip6s_cantforward);
  201                 KEY_FREESP(&sp);
  202                 if (mcopy) {
  203 #if 0
  204                         /* XXX: what icmp ? */
  205 #else
  206                         m_freem(mcopy);
  207 #endif
  208                 }
  209                 m_freem(m);
  210                 return;
  211 
  212         case IPSEC_POLICY_BYPASS:
  213         case IPSEC_POLICY_NONE:
  214                 /* no need to do IPsec. */
  215                 KEY_FREESP(&sp);
  216                 goto skip_ipsec;
  217 
  218         case IPSEC_POLICY_IPSEC:
  219                 if (sp->req == NULL) {
  220                         /* XXX should be panic ? */
  221                         printf("ip6_forward: No IPsec request specified.\n");
  222                         IP6STAT_INC(ip6s_cantforward);
  223                         KEY_FREESP(&sp);
  224                         if (mcopy) {
  225 #if 0
  226                                 /* XXX: what icmp ? */
  227 #else
  228                                 m_freem(mcopy);
  229 #endif
  230                         }
  231                         m_freem(m);
  232                         return;
  233                 }
  234                 /* do IPsec */
  235                 break;
  236 
  237         case IPSEC_POLICY_ENTRUST:
  238         default:
  239                 /* should be panic ?? */
  240                 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
  241                 KEY_FREESP(&sp);
  242                 goto skip_ipsec;
  243         }
  244 
  245     {
  246         struct ipsecrequest *isr = NULL;
  247 
  248         /*
  249          * when the kernel forwards a packet, it is not proper to apply
  250          * IPsec transport mode to the packet. This check avoid from this.
  251          * at present, if there is even a transport mode SA request in the
  252          * security policy, the kernel does not apply IPsec to the packet.
  253          * this check is not enough because the following case is valid.
  254          *      ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
  255          */
  256         for (isr = sp->req; isr; isr = isr->next) {
  257                 if (isr->saidx.mode == IPSEC_MODE_ANY)
  258                         goto doipsectunnel;
  259                 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
  260                         goto doipsectunnel;
  261         }
  262 
  263         /*
  264          * if there's no need for tunnel mode IPsec, skip.
  265          */
  266         if (!isr)
  267                 goto skip_ipsec;
  268 
  269     doipsectunnel:
  270         /*
  271          * All the extension headers will become inaccessible
  272          * (since they can be encrypted).
  273          * Don't panic, we need no more updates to extension headers
  274          * on inner IPv6 packet (since they are now encapsulated).
  275          *
  276          * IPv6 [ESP|AH] IPv6 [extension headers] payload
  277          */
  278 
  279         /*
  280          * If we need to encapsulate the packet, do it here
  281          * ipsec6_proces_packet will send the packet using ip6_output
  282          */
  283         error = ipsec6_process_packet(m, sp->req);
  284         /* Release SP if an error occurred */
  285         if (error != 0)
  286                 KEY_FREESP(&sp);
  287         if (error == EJUSTRETURN) {
  288                 /*
  289                  * We had a SP with a level of 'use' and no SA. We
  290                  * will just continue to process the packet without
  291                  * IPsec processing.
  292                  */
  293                 error = 0;
  294                 goto skip_ipsec;
  295         }
  296 
  297         if (error) {
  298                 /* mbuf is already reclaimed in ipsec6_process_packet. */
  299                 switch (error) {
  300                 case EHOSTUNREACH:
  301                 case ENETUNREACH:
  302                 case EMSGSIZE:
  303                 case ENOBUFS:
  304                 case ENOMEM:
  305                         break;
  306                 default:
  307                         printf("ip6_output (ipsec): error code %d\n", error);
  308                         /* FALLTHROUGH */
  309                 case ENOENT:
  310                         /* don't show these error codes to the user */
  311                         break;
  312                 }
  313                 IP6STAT_INC(ip6s_cantforward);
  314                 if (mcopy) {
  315 #if 0
  316                         /* XXX: what icmp ? */
  317 #else
  318                         m_freem(mcopy);
  319 #endif
  320                 }
  321                 return;
  322         } else {
  323                 /*
  324                  * In the FAST IPSec case we have already
  325                  * re-injected the packet and it has been freed
  326                  * by the ipsec_done() function.  So, just clean
  327                  * up after ourselves.
  328                  */
  329                 m = NULL;
  330                 goto freecopy;
  331         }
  332     }
  333 skip_ipsec:
  334 #endif
  335 again:
  336         bzero(&rin6, sizeof(struct route_in6));
  337         dst = (struct sockaddr_in6 *)&rin6.ro_dst;
  338         dst->sin6_len = sizeof(struct sockaddr_in6);
  339         dst->sin6_family = AF_INET6;
  340         dst->sin6_addr = ip6->ip6_dst;
  341 again2:
  342         rin6.ro_rt = in6_rtalloc1((struct sockaddr *)dst, 0, 0, M_GETFIB(m));
  343         rt = rin6.ro_rt;
  344         if (rin6.ro_rt != NULL)
  345                 RT_UNLOCK(rin6.ro_rt);
  346         else {
  347                 IP6STAT_INC(ip6s_noroute);
  348                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
  349                 if (mcopy) {
  350                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  351                         ICMP6_DST_UNREACH_NOROUTE, 0);
  352                 }
  353                 goto bad;
  354         }
  355 
  356         /*
  357          * Source scope check: if a packet can't be delivered to its
  358          * destination for the reason that the destination is beyond the scope
  359          * of the source address, discard the packet and return an icmp6
  360          * destination unreachable error with Code 2 (beyond scope of source
  361          * address).  We use a local copy of ip6_src, since in6_setscope()
  362          * will possibly modify its first argument.
  363          * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
  364          */
  365         src_in6 = ip6->ip6_src;
  366         if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
  367                 /* XXX: this should not happen */
  368                 IP6STAT_INC(ip6s_cantforward);
  369                 IP6STAT_INC(ip6s_badscope);
  370                 goto bad;
  371         }
  372         if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
  373                 IP6STAT_INC(ip6s_cantforward);
  374                 IP6STAT_INC(ip6s_badscope);
  375                 goto bad;
  376         }
  377         if (inzone != outzone) {
  378                 IP6STAT_INC(ip6s_cantforward);
  379                 IP6STAT_INC(ip6s_badscope);
  380                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
  381 
  382                 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
  383                         V_ip6_log_time = time_uptime;
  384                         log(LOG_DEBUG,
  385                             "cannot forward "
  386                             "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  387                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  388                             ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  389                             ip6->ip6_nxt,
  390                             if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
  391                 }
  392                 if (mcopy)
  393                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  394                                     ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
  395                 goto bad;
  396         }
  397 
  398         /*
  399          * Destination scope check: if a packet is going to break the scope
  400          * zone of packet's destination address, discard it.  This case should
  401          * usually be prevented by appropriately-configured routing table, but
  402          * we need an explicit check because we may mistakenly forward the
  403          * packet to a different zone by (e.g.) a default route.
  404          */
  405         dst_in6 = ip6->ip6_dst;
  406         if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
  407             in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
  408             inzone != outzone) {
  409                 IP6STAT_INC(ip6s_cantforward);
  410                 IP6STAT_INC(ip6s_badscope);
  411                 goto bad;
  412         }
  413 
  414         if (rt->rt_flags & RTF_GATEWAY)
  415                 dst = (struct sockaddr_in6 *)rt->rt_gateway;
  416 
  417         /*
  418          * If we are to forward the packet using the same interface
  419          * as one we got the packet from, perhaps we should send a redirect
  420          * to sender to shortcut a hop.
  421          * Only send redirect if source is sending directly to us,
  422          * and if packet was not source routed (or has any options).
  423          * Also, don't send redirect if forwarding using a route
  424          * modified by a redirect.
  425          */
  426         if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
  427             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
  428                 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
  429                         /*
  430                          * If the incoming interface is equal to the outgoing
  431                          * one, and the link attached to the interface is
  432                          * point-to-point, then it will be highly probable
  433                          * that a routing loop occurs. Thus, we immediately
  434                          * drop the packet and send an ICMPv6 error message.
  435                          *
  436                          * type/code is based on suggestion by Rich Draves.
  437                          * not sure if it is the best pick.
  438                          */
  439                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  440                                     ICMP6_DST_UNREACH_ADDR, 0);
  441                         goto bad;
  442                 }
  443                 type = ND_REDIRECT;
  444         }
  445 
  446         /*
  447          * Fake scoped addresses. Note that even link-local source or
  448          * destinaion can appear, if the originating node just sends the
  449          * packet to us (without address resolution for the destination).
  450          * Since both icmp6_error and icmp6_redirect_output fill the embedded
  451          * link identifiers, we can do this stuff after making a copy for
  452          * returning an error.
  453          */
  454         if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
  455                 /*
  456                  * See corresponding comments in ip6_output.
  457                  * XXX: but is it possible that ip6_forward() sends a packet
  458                  *      to a loopback interface? I don't think so, and thus
  459                  *      I bark here. (jinmei@kame.net)
  460                  * XXX: it is common to route invalid packets to loopback.
  461                  *      also, the codepath will be visited on use of ::1 in
  462                  *      rthdr. (itojun)
  463                  */
  464 #if 1
  465                 if (0)
  466 #else
  467                 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
  468 #endif
  469                 {
  470                         printf("ip6_forward: outgoing interface is loopback. "
  471                                "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  472                                ip6_sprintf(ip6bufs, &ip6->ip6_src),
  473                                ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  474                                ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
  475                                if_name(rt->rt_ifp));
  476                 }
  477 
  478                 /* we can just use rcvif in forwarding. */
  479                 origifp = m->m_pkthdr.rcvif;
  480         }
  481         else
  482                 origifp = rt->rt_ifp;
  483         /*
  484          * clear embedded scope identifiers if necessary.
  485          * in6_clearscope will touch the addresses only when necessary.
  486          */
  487         in6_clearscope(&ip6->ip6_src);
  488         in6_clearscope(&ip6->ip6_dst);
  489 
  490         /* Jump over all PFIL processing if hooks are not active. */
  491         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  492                 goto pass;
  493 
  494         odst = ip6->ip6_dst;
  495         /* Run through list of hooks for output packets. */
  496         error = pfil_run_hooks(&V_inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
  497         if (error != 0 || m == NULL)
  498                 goto freecopy;          /* consumed by filter */
  499         ip6 = mtod(m, struct ip6_hdr *);
  500 
  501         /* See if destination IP address was changed by packet filter. */
  502         if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
  503                 m->m_flags |= M_SKIP_FIREWALL;
  504                 /* If destination is now ourself drop to ip6_input(). */
  505                 if (in6_localip(&ip6->ip6_dst))
  506                         m->m_flags |= M_FASTFWD_OURS;
  507                 else {
  508                         RTFREE(rt);
  509                         goto again;     /* Redo the routing table lookup. */
  510                 }
  511         }
  512 
  513         /* See if local, if yes, send it to netisr. */
  514         if (m->m_flags & M_FASTFWD_OURS) {
  515                 if (m->m_pkthdr.rcvif == NULL)
  516                         m->m_pkthdr.rcvif = V_loif;
  517                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
  518                         m->m_pkthdr.csum_flags |=
  519                             CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
  520                         m->m_pkthdr.csum_data = 0xffff;
  521                 }
  522 #ifdef SCTP
  523                 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
  524                         m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  525 #endif
  526                 error = netisr_queue(NETISR_IPV6, m);
  527                 goto out;
  528         }
  529         /* Or forward to some other address? */
  530         if ((m->m_flags & M_IP6_NEXTHOP) &&
  531             (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
  532                 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
  533                 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in6));
  534                 m->m_flags |= M_SKIP_FIREWALL;
  535                 m->m_flags &= ~M_IP6_NEXTHOP;
  536                 m_tag_delete(m, fwd_tag);
  537                 RTFREE(rt);
  538                 goto again2;
  539         }
  540 
  541 pass:
  542         /* See if the size was changed by the packet filter. */
  543         if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
  544                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
  545                 if (mcopy) {
  546                         u_long mtu;
  547 #ifdef IPSEC
  548                         size_t ipsechdrsiz;
  549 #endif /* IPSEC */
  550 
  551                         mtu = IN6_LINKMTU(rt->rt_ifp);
  552 #ifdef IPSEC
  553                         /*
  554                          * When we do IPsec tunnel ingress, we need to play
  555                          * with the link value (decrement IPsec header size
  556                          * from mtu value).  The code is much simpler than v4
  557                          * case, as we have the outgoing interface for
  558                          * encapsulated packet as "rt->rt_ifp".
  559                          */
  560                         ipsechdrsiz = ipsec_hdrsiz(mcopy, IPSEC_DIR_OUTBOUND,
  561                             NULL);
  562                         if (ipsechdrsiz < mtu)
  563                                 mtu -= ipsechdrsiz;
  564                         /*
  565                          * if mtu becomes less than minimum MTU,
  566                          * tell minimum MTU (and I'll need to fragment it).
  567                          */
  568                         if (mtu < IPV6_MMTU)
  569                                 mtu = IPV6_MMTU;
  570 #endif /* IPSEC */
  571                         icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
  572                 }
  573                 goto bad;
  574         }
  575 
  576         error = nd6_output_ifp(rt->rt_ifp, origifp, m, dst, NULL);
  577         if (error) {
  578                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
  579                 IP6STAT_INC(ip6s_cantforward);
  580         } else {
  581                 IP6STAT_INC(ip6s_forward);
  582                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
  583                 if (type)
  584                         IP6STAT_INC(ip6s_redirectsent);
  585                 else {
  586                         if (mcopy)
  587                                 goto freecopy;
  588                 }
  589         }
  590 
  591         if (mcopy == NULL)
  592                 goto out;
  593         switch (error) {
  594         case 0:
  595                 if (type == ND_REDIRECT) {
  596                         icmp6_redirect_output(mcopy, rt);
  597                         goto out;
  598                 }
  599                 goto freecopy;
  600 
  601         case EMSGSIZE:
  602                 /* xxx MTU is constant in PPP? */
  603                 goto freecopy;
  604 
  605         case ENOBUFS:
  606                 /* Tell source to slow down like source quench in IP? */
  607                 goto freecopy;
  608 
  609         case ENETUNREACH:       /* shouldn't happen, checked above */
  610         case EHOSTUNREACH:
  611         case ENETDOWN:
  612         case EHOSTDOWN:
  613         default:
  614                 type = ICMP6_DST_UNREACH;
  615                 code = ICMP6_DST_UNREACH_ADDR;
  616                 break;
  617         }
  618         icmp6_error(mcopy, type, code, 0);
  619         goto out;
  620 
  621  freecopy:
  622         m_freem(mcopy);
  623         goto out;
  624 bad:
  625         m_freem(m);
  626 out:
  627         if (rt != NULL)
  628                 RTFREE(rt);
  629 }

Cache object: f392a3c986e0373a228bfcae0b6b760d


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