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 /*      $NetBSD: ip6_forward.c,v 1.65.12.1 2009/11/14 09:45:53 sborrill Exp $   */
    2 /*      $KAME: ip6_forward.c,v 1.109 2002/09/11 08:10:17 sakane 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 #include <sys/cdefs.h>
   34 __KERNEL_RCSID(0, "$NetBSD: ip6_forward.c,v 1.65.12.1 2009/11/14 09:45:53 sborrill Exp $");
   35 
   36 #include "opt_ipsec.h"
   37 #include "opt_pfil_hooks.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/malloc.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/domain.h>
   44 #include <sys/protosw.h>
   45 #include <sys/socket.h>
   46 #include <sys/errno.h>
   47 #include <sys/time.h>
   48 #include <sys/kernel.h>
   49 #include <sys/syslog.h>
   50 
   51 #include <net/if.h>
   52 #include <net/route.h>
   53 
   54 #include <netinet/in.h>
   55 #include <netinet/in_var.h>
   56 #include <netinet/ip_var.h>
   57 #include <netinet/ip6.h>
   58 #include <netinet6/ip6_var.h>
   59 #include <netinet6/ip6_private.h>
   60 #include <netinet6/scope6_var.h>
   61 #include <netinet/icmp6.h>
   62 #include <netinet6/nd6.h>
   63 
   64 #ifdef IPSEC
   65 #include <netinet6/ipsec.h>
   66 #include <netinet6/ipsec_private.h>
   67 #include <netkey/key.h>
   68 #endif /* IPSEC */
   69 
   70 #ifdef FAST_IPSEC
   71 #include <netipsec/ipsec.h>
   72 #include <netipsec/ipsec6.h>
   73 #include <netipsec/key.h>
   74 #include <netipsec/xform.h>
   75 #endif /* FAST_IPSEC */
   76 
   77 #ifdef PFIL_HOOKS
   78 #include <net/pfil.h>
   79 #endif
   80 
   81 #include <net/net_osdep.h>
   82 
   83 struct  route ip6_forward_rt;
   84 
   85 #ifdef PFIL_HOOKS
   86 extern struct pfil_head inet6_pfil_hook;        /* XXX */
   87 #endif
   88 
   89 /*
   90  * Forward a packet.  If some error occurs return the sender
   91  * an icmp packet.  Note we can't always generate a meaningful
   92  * icmp message because icmp doesn't have a large enough repertoire
   93  * of codes and types.
   94  *
   95  * If not forwarding, just drop the packet.  This could be confusing
   96  * if ipforwarding was zero but some routing protocol was advancing
   97  * us as a gateway to somewhere.  However, we must let the routing
   98  * protocol deal with that.
   99  *
  100  */
  101 
  102 void
  103 ip6_forward(struct mbuf *m, int srcrt)
  104 {
  105         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
  106         const struct sockaddr_in6 *dst;
  107         struct rtentry *rt;
  108         int error = 0, type = 0, code = 0;
  109         struct mbuf *mcopy = NULL;
  110         struct ifnet *origifp;  /* maybe unnecessary */
  111         u_int32_t inzone, outzone;
  112         struct in6_addr src_in6, dst_in6;
  113 #ifdef IPSEC
  114         struct secpolicy *sp = NULL;
  115         int ipsecrt = 0;
  116 #endif
  117 #ifdef FAST_IPSEC
  118     struct secpolicy *sp = NULL;
  119     int needipsec = 0;
  120     int s;
  121 #endif
  122 
  123         /*
  124          * Clear any in-bound checksum flags for this packet.
  125          */
  126         m->m_pkthdr.csum_flags = 0;
  127 
  128 #ifdef IPSEC
  129         /*
  130          * Check AH/ESP integrity.
  131          */
  132         /*
  133          * Don't increment ip6s_cantforward because this is the check
  134          * before forwarding packet actually.
  135          */
  136         if (ipsec6_in_reject(m, NULL)) {
  137                 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO);
  138                 m_freem(m);
  139                 return;
  140         }
  141 #endif /* IPSEC */
  142 
  143         /*
  144          * Do not forward packets to multicast destination (should be handled
  145          * by ip6_mforward().
  146          * Do not forward packets with unspecified source.  It was discussed
  147          * in July 2000, on ipngwg mailing list.
  148          */
  149         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
  150             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
  151             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
  152                 IP6_STATINC(IP6_STAT_CANTFORWARD);
  153                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  154                 if (ip6_log_time + ip6_log_interval < time_second) {
  155                         ip6_log_time = time_second;
  156                         log(LOG_DEBUG,
  157                             "cannot forward "
  158                             "from %s to %s nxt %d received on %s\n",
  159                             ip6_sprintf(&ip6->ip6_src),
  160                             ip6_sprintf(&ip6->ip6_dst),
  161                             ip6->ip6_nxt,
  162                             if_name(m->m_pkthdr.rcvif));
  163                 }
  164                 m_freem(m);
  165                 return;
  166         }
  167 
  168         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
  169                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  170                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
  171                                 ICMP6_TIME_EXCEED_TRANSIT, 0);
  172                 return;
  173         }
  174         ip6->ip6_hlim -= IPV6_HLIMDEC;
  175 
  176         /*
  177          * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
  178          * size of IPv6 + ICMPv6 headers) bytes of the packet in case
  179          * we need to generate an ICMP6 message to the src.
  180          * Thanks to M_EXT, in most cases copy will not occur.
  181          *
  182          * It is important to save it before IPsec processing as IPsec
  183          * processing may modify the mbuf.
  184          */
  185         mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
  186 
  187 #ifdef IPSEC
  188         /* get a security policy for this packet */
  189         sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
  190             IP_FORWARDING, &error);
  191         if (sp == NULL) {
  192                 IPSEC6_STATINC(IPSEC_STAT_OUT_INVAL);
  193                 IP6_STATINC(IP6_STAT_CANTFORWARD);
  194                 if (mcopy) {
  195 #if 0
  196                         /* XXX: what icmp ? */
  197 #else
  198                         m_freem(mcopy);
  199 #endif
  200                 }
  201                 m_freem(m);
  202                 return;
  203         }
  204 
  205         error = 0;
  206 
  207         /* check policy */
  208         switch (sp->policy) {
  209         case IPSEC_POLICY_DISCARD:
  210                 /*
  211                  * This packet is just discarded.
  212                  */
  213                 IPSEC6_STATINC(IPSEC_STAT_OUT_POLVIO);
  214                 IP6_STATINC(IP6_STAT_CANTFORWARD);
  215                 key_freesp(sp);
  216                 if (mcopy) {
  217 #if 0
  218                         /* XXX: what icmp ? */
  219 #else
  220                         m_freem(mcopy);
  221 #endif
  222                 }
  223                 m_freem(m);
  224                 return;
  225 
  226         case IPSEC_POLICY_BYPASS:
  227         case IPSEC_POLICY_NONE:
  228                 /* no need to do IPsec. */
  229                 key_freesp(sp);
  230                 goto skip_ipsec;
  231 
  232         case IPSEC_POLICY_IPSEC:
  233                 if (sp->req == NULL) {
  234                         /* XXX should be panic ? */
  235                         printf("ip6_forward: No IPsec request specified.\n");
  236                         IP6_STATINC(IP6_STAT_CANTFORWARD);
  237                         key_freesp(sp);
  238                         if (mcopy) {
  239 #if 0
  240                                 /* XXX: what icmp ? */
  241 #else
  242                                 m_freem(mcopy);
  243 #endif
  244                         }
  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                 goto skip_ipsec;
  257         }
  258 
  259     {
  260         struct ipsecrequest *isr = NULL;
  261         struct ipsec_output_state state;
  262 
  263         /*
  264          * when the kernel forwards a packet, it is not proper to apply
  265          * IPsec transport mode to the packet is not proper.  this check
  266          * avoid from this.
  267          * at present, if there is even a transport mode SA request in the
  268          * security policy, the kernel does not apply IPsec to the packet.
  269          * this check is not enough because the following case is valid.
  270          *      ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
  271          */
  272         for (isr = sp->req; isr; isr = isr->next) {
  273                 if (isr->saidx.mode == IPSEC_MODE_ANY)
  274                         goto doipsectunnel;
  275                 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
  276                         goto doipsectunnel;
  277         }
  278 
  279         /*
  280          * if there's no need for tunnel mode IPsec, skip.
  281          */
  282         if (!isr)
  283                 goto skip_ipsec;
  284 
  285     doipsectunnel:
  286         /*
  287          * All the extension headers will become inaccessible
  288          * (since they can be encrypted).
  289          * Don't panic, we need no more updates to extension headers
  290          * on inner IPv6 packet (since they are now encapsulated).
  291          *
  292          * IPv6 [ESP|AH] IPv6 [extension headers] payload
  293          */
  294         bzero(&state, sizeof(state));
  295         state.m = m;
  296         state.ro = NULL;        /* update at ipsec6_output_tunnel() */
  297         state.dst = NULL;       /* update at ipsec6_output_tunnel() */
  298 
  299         error = ipsec6_output_tunnel(&state, sp, 0);
  300 
  301         m = state.m;
  302         key_freesp(sp);
  303 
  304         if (error) {
  305                 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
  306                 switch (error) {
  307                 case EHOSTUNREACH:
  308                 case ENETUNREACH:
  309                 case EMSGSIZE:
  310                 case ENOBUFS:
  311                 case ENOMEM:
  312                         break;
  313                 default:
  314                         printf("ip6_forward (ipsec): error code %d\n", error);
  315                         /* FALLTHROUGH */
  316                 case ENOENT:
  317                         /* don't show these error codes to the user */
  318                         break;
  319                 }
  320                 IP6_STATINC(IP6_STAT_CANTFORWARD);
  321                 if (mcopy) {
  322 #if 0
  323                         /* XXX: what icmp ? */
  324 #else
  325                         m_freem(mcopy);
  326 #endif
  327                 }
  328                 m_freem(m);
  329                 return;
  330         }
  331 
  332         if (ip6 != mtod(m, struct ip6_hdr *)) {
  333                 /*
  334                  * now tunnel mode headers are added.  we are originating
  335                  * packet instead of forwarding the packet.
  336                  */
  337                 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
  338                     NULL);
  339                 goto freecopy;
  340         }
  341 
  342         /* adjust pointer */
  343         rt = state.ro ? rtcache_validate(state.ro) : NULL;
  344         dst = (const struct sockaddr_in6 *)state.dst;
  345         if (dst != NULL && rt != NULL) {
  346                 ipsecrt = 1;
  347                 goto skip_routing;
  348         }
  349     }
  350     skip_ipsec:
  351 #endif /* IPSEC */
  352 #ifdef FAST_IPSEC
  353         /* Check the security policy (SP) for the packet */
  354 
  355         sp = ipsec6_check_policy(m,NULL,0,&needipsec,&error);
  356         if (error != 0) {
  357                 /*
  358                  * Hack: -EINVAL is used to signal that a packet
  359                  * should be silently discarded.  This is typically
  360                  * because we asked key management for an SA and
  361                  * it was delayed (e.g. kicked up to IKE).
  362                  */
  363         if (error == -EINVAL)
  364                 error = 0;
  365         goto freecopy;
  366         }
  367 #endif /* FAST_IPSEC */
  368 
  369         if (srcrt) {
  370                 union {
  371                         struct sockaddr         dst;
  372                         struct sockaddr_in6     dst6;
  373                 } u;
  374 
  375                 sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
  376                 if ((rt = rtcache_lookup(&ip6_forward_rt, &u.dst)) == NULL) {
  377                         IP6_STATINC(IP6_STAT_NOROUTE);
  378                         /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
  379                         if (mcopy) {
  380                                 icmp6_error(mcopy, ICMP6_DST_UNREACH,
  381                                             ICMP6_DST_UNREACH_NOROUTE, 0);
  382                         }
  383                         m_freem(m);
  384                         return;
  385                 }
  386         } else if ((rt = rtcache_validate(&ip6_forward_rt)) == NULL &&
  387                    (rt = rtcache_update(&ip6_forward_rt, 1)) == NULL) {
  388                 /*
  389                  * rtcache_getdst(ip6_forward_rt)->sin6_addr was equal to
  390                  * ip6->ip6_dst
  391                  */
  392                 IP6_STATINC(IP6_STAT_NOROUTE);
  393                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
  394                 if (mcopy) {
  395                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  396                             ICMP6_DST_UNREACH_NOROUTE, 0);
  397                 }
  398                 m_freem(m);
  399                 return;
  400         }
  401         dst = satocsin6(rtcache_getdst(&ip6_forward_rt));
  402 #ifdef IPSEC
  403     skip_routing:;
  404 #endif /* IPSEC */
  405 
  406         /*
  407          * Source scope check: if a packet can't be delivered to its
  408          * destination for the reason that the destination is beyond the scope
  409          * of the source address, discard the packet and return an icmp6
  410          * destination unreachable error with Code 2 (beyond scope of source
  411          * address).  We use a local copy of ip6_src, since in6_setscope()
  412          * will possibly modify its first argument.
  413          * [draft-ietf-ipngwg-icmp-v3-07, Section 3.1]
  414          */
  415         src_in6 = ip6->ip6_src;
  416         if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
  417                 /* XXX: this should not happen */
  418                 uint64_t *ip6s = IP6_STAT_GETREF();
  419                 ip6s[IP6_STAT_CANTFORWARD]++;
  420                 ip6s[IP6_STAT_BADSCOPE]++;
  421                 IP6_STAT_PUTREF();
  422                 m_freem(m);
  423                 return;
  424         }
  425         if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
  426                 uint64_t *ip6s = IP6_STAT_GETREF();
  427                 ip6s[IP6_STAT_CANTFORWARD]++;
  428                 ip6s[IP6_STAT_BADSCOPE]++;
  429                 IP6_STAT_PUTREF();
  430                 m_freem(m);
  431                 return;
  432         }
  433         if (inzone != outzone
  434 #ifdef IPSEC
  435             && !ipsecrt
  436 #endif
  437             ) {
  438                 uint64_t *ip6s = IP6_STAT_GETREF();
  439                 ip6s[IP6_STAT_CANTFORWARD]++;
  440                 ip6s[IP6_STAT_BADSCOPE]++;
  441                 IP6_STAT_PUTREF();
  442                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
  443 
  444                 if (ip6_log_time + ip6_log_interval < time_second) {
  445                         ip6_log_time = time_second;
  446                         log(LOG_DEBUG,
  447                             "cannot forward "
  448                             "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  449                             ip6_sprintf(&ip6->ip6_src),
  450                             ip6_sprintf(&ip6->ip6_dst),
  451                             ip6->ip6_nxt,
  452                             if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
  453                 }
  454                 if (mcopy)
  455                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  456                                     ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
  457                 m_freem(m);
  458                 return;
  459         }
  460 #ifdef FAST_IPSEC
  461     /*
  462      * If we need to encapsulate the packet, do it here
  463      * ipsec6_proces_packet will send the packet using ip6_output 
  464      */
  465         if (needipsec) {
  466                 s = splsoftnet();
  467                 error = ipsec6_process_packet(m,sp->req);
  468                 splx(s);
  469                 if (mcopy)
  470                         goto freecopy;
  471     }
  472 #endif   
  473 
  474 
  475 
  476         /*
  477          * Destination scope check: if a packet is going to break the scope
  478          * zone of packet's destination address, discard it.  This case should
  479          * usually be prevented by appropriately-configured routing table, but
  480          * we need an explicit check because we may mistakenly forward the
  481          * packet to a different zone by (e.g.) a default route.
  482          */
  483         dst_in6 = ip6->ip6_dst;
  484         if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
  485             in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
  486             inzone != outzone) {
  487                 uint64_t *ip6s = IP6_STAT_GETREF();
  488                 ip6s[IP6_STAT_CANTFORWARD]++;
  489                 ip6s[IP6_STAT_BADSCOPE]++;
  490                 IP6_STAT_PUTREF();
  491                 m_freem(m);
  492                 return;
  493         }
  494 
  495         if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
  496                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
  497                 if (mcopy) {
  498                         u_long mtu;
  499 #ifdef IPSEC
  500                         struct secpolicy *xsp;
  501                         int ipsecerror;
  502                         size_t ipsechdrsiz;
  503 #endif
  504 
  505                         mtu = IN6_LINKMTU(rt->rt_ifp);
  506 #ifdef IPSEC
  507                         /*
  508                          * When we do IPsec tunnel ingress, we need to play
  509                          * with the link value (decrement IPsec header size
  510                          * from mtu value).  The code is much simpler than v4
  511                          * case, as we have the outgoing interface for
  512                          * encapsulated packet as "rt->rt_ifp".
  513                          */
  514                         xsp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
  515                                 IP_FORWARDING, &ipsecerror);
  516                         if (xsp) {
  517                                 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
  518                                         IPSEC_DIR_OUTBOUND, NULL);
  519                                 if (ipsechdrsiz < mtu)
  520                                         mtu -= ipsechdrsiz;
  521                         }
  522 
  523                         /*
  524                          * if mtu becomes less than minimum MTU,
  525                          * tell minimum MTU (and I'll need to fragment it).
  526                          */
  527                         if (mtu < IPV6_MMTU)
  528                                 mtu = IPV6_MMTU;
  529 #endif
  530                         icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
  531                 }
  532                 m_freem(m);
  533                 return;
  534         }
  535 
  536         if (rt->rt_flags & RTF_GATEWAY)
  537                 dst = (struct sockaddr_in6 *)rt->rt_gateway;
  538 
  539         /*
  540          * If we are to forward the packet using the same interface
  541          * as one we got the packet from, perhaps we should send a redirect
  542          * to sender to shortcut a hop.
  543          * Only send redirect if source is sending directly to us,
  544          * and if packet was not source routed (or has any options).
  545          * Also, don't send redirect if forwarding using a route
  546          * modified by a redirect.
  547          */
  548         if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && ip6_sendredirects &&
  549 #ifdef IPSEC
  550             !ipsecrt &&
  551 #endif
  552             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
  553                 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) &&
  554                     nd6_is_addr_neighbor(
  555                         satocsin6(rtcache_getdst(&ip6_forward_rt)),
  556                         rt->rt_ifp)) {
  557                         /*
  558                          * If the incoming interface is equal to the outgoing
  559                          * one, the link attached to the interface is
  560                          * point-to-point, and the IPv6 destination is
  561                          * regarded as on-link on the link, then it will be
  562                          * highly probable that the destination address does
  563                          * not exist on the link and that the packet is going
  564                          * to loop.  Thus, we immediately drop the packet and
  565                          * send an ICMPv6 error message.
  566                          * For other routing loops, we dare to let the packet
  567                          * go to the loop, so that a remote diagnosing host
  568                          * can detect the loop by traceroute.
  569                          * type/code is based on suggestion by Rich Draves.
  570                          * not sure if it is the best pick.
  571                          */
  572                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  573                                     ICMP6_DST_UNREACH_ADDR, 0);
  574                         m_freem(m);
  575                         return;
  576                 }
  577                 type = ND_REDIRECT;
  578         }
  579 
  580         /*
  581          * Fake scoped addresses. Note that even link-local source or
  582          * destinaion can appear, if the originating node just sends the
  583          * packet to us (without address resolution for the destination).
  584          * Since both icmp6_error and icmp6_redirect_output fill the embedded
  585          * link identifiers, we can do this stuff after making a copy for
  586          * returning an error.
  587          */
  588         if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
  589                 /*
  590                  * See corresponding comments in ip6_output.
  591                  * XXX: but is it possible that ip6_forward() sends a packet
  592                  *      to a loopback interface? I don't think so, and thus
  593                  *      I bark here. (jinmei@kame.net)
  594                  * XXX: it is common to route invalid packets to loopback.
  595                  *      also, the codepath will be visited on use of ::1 in
  596                  *      rthdr. (itojun)
  597                  */
  598 #if 1
  599                 if (0)
  600 #else
  601                 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
  602 #endif
  603                 {
  604                         printf("ip6_forward: outgoing interface is loopback. "
  605                                "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  606                                ip6_sprintf(&ip6->ip6_src),
  607                                ip6_sprintf(&ip6->ip6_dst),
  608                                ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
  609                                if_name(rt->rt_ifp));
  610                 }
  611 
  612                 /* we can just use rcvif in forwarding. */
  613                 origifp = m->m_pkthdr.rcvif;
  614         }
  615         else
  616                 origifp = rt->rt_ifp;
  617         /*
  618          * clear embedded scope identifiers if necessary.
  619          * in6_clearscope will touch the addresses only when necessary.
  620          */
  621         in6_clearscope(&ip6->ip6_src);
  622         in6_clearscope(&ip6->ip6_dst);
  623 
  624 #ifdef PFIL_HOOKS
  625         /*
  626          * Run through list of hooks for output packets.
  627          */
  628         if ((error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp,
  629             PFIL_OUT)) != 0)
  630                 goto senderr;
  631         if (m == NULL)
  632                 goto freecopy;
  633         ip6 = mtod(m, struct ip6_hdr *);
  634 #endif /* PFIL_HOOKS */
  635 
  636         error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
  637         if (error) {
  638                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
  639                 IP6_STATINC(IP6_STAT_CANTFORWARD);
  640         } else {
  641                 IP6_STATINC(IP6_STAT_FORWARD);
  642                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
  643                 if (type)
  644                         IP6_STATINC(IP6_STAT_REDIRECTSENT);
  645                 else {
  646 #ifdef GATEWAY
  647                         if (m->m_flags & M_CANFASTFWD)
  648                                 ip6flow_create(&ip6_forward_rt, m);
  649 #endif
  650                         if (mcopy)
  651                                 goto freecopy;
  652                 }
  653         }
  654 
  655 #ifdef PFIL_HOOKS
  656  senderr:
  657 #endif
  658         if (mcopy == NULL)
  659                 return;
  660         switch (error) {
  661         case 0:
  662                 if (type == ND_REDIRECT) {
  663                         icmp6_redirect_output(mcopy, rt);
  664                         return;
  665                 }
  666                 goto freecopy;
  667 
  668         case EMSGSIZE:
  669                 /* xxx MTU is constant in PPP? */
  670                 goto freecopy;
  671 
  672         case ENOBUFS:
  673                 /* Tell source to slow down like source quench in IP? */
  674                 goto freecopy;
  675 
  676         case ENETUNREACH:       /* shouldn't happen, checked above */
  677         case EHOSTUNREACH:
  678         case ENETDOWN:
  679         case EHOSTDOWN:
  680         default:
  681                 type = ICMP6_DST_UNREACH;
  682                 code = ICMP6_DST_UNREACH_ADDR;
  683                 break;
  684         }
  685         icmp6_error(mcopy, type, code, 0);
  686         return;
  687 
  688  freecopy:
  689         m_freem(mcopy);
  690         return;
  691 }

Cache object: 18c85722a7078645c63351aa8e54b00a


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