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/10.4/sys/netinet6/ip6_forward.c 284576 2015-06-18 20:57:21Z kp $");
   34 
   35 #include "opt_inet.h"
   36 #include "opt_inet6.h"
   37 #include "opt_ipfw.h"
   38 #include "opt_ipsec.h"
   39 #include "opt_ipstealth.h"
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/malloc.h>
   44 #include <sys/mbuf.h>
   45 #include <sys/domain.h>
   46 #include <sys/protosw.h>
   47 #include <sys/socket.h>
   48 #include <sys/errno.h>
   49 #include <sys/time.h>
   50 #include <sys/kernel.h>
   51 #include <sys/syslog.h>
   52 
   53 #include <net/if.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 <netipsec/ipsec.h>
   74 #include <netipsec/ipsec6.h>
   75 #include <netipsec/key.h>
   76 #endif /* IPSEC */
   77 
   78 #include <netinet6/ip6protosw.h>
   79 
   80 /*
   81  * Forward a packet.  If some error occurs return the sender
   82  * an icmp packet.  Note we can't always generate a meaningful
   83  * icmp message because icmp doesn't have a large enough repertoire
   84  * of codes and types.
   85  *
   86  * If not forwarding, just drop the packet.  This could be confusing
   87  * if ipforwarding was zero but some routing protocol was advancing
   88  * us as a gateway to somewhere.  However, we must let the routing
   89  * protocol deal with that.
   90  *
   91  */
   92 void
   93 ip6_forward(struct mbuf *m, int srcrt)
   94 {
   95         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
   96         struct sockaddr_in6 *dst = NULL;
   97         struct rtentry *rt = NULL;
   98         struct route_in6 rin6;
   99         int error, type = 0, code = 0;
  100         struct mbuf *mcopy = NULL;
  101         struct ifnet *origifp;  /* maybe unnecessary */
  102         u_int32_t inzone, outzone;
  103         struct in6_addr src_in6, dst_in6, odst;
  104 #ifdef IPSEC
  105         struct secpolicy *sp = NULL;
  106         int ipsecrt = 0;
  107 #endif
  108 #ifdef SCTP
  109         int sw_csum;
  110 #endif
  111         struct m_tag *fwd_tag;
  112         char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
  113 
  114 #ifdef IPSEC
  115         /*
  116          * Check AH/ESP integrity.
  117          */
  118         /*
  119          * Don't increment ip6s_cantforward because this is the check
  120          * before forwarding packet actually.
  121          */
  122         if (ipsec6_in_reject(m, NULL)) {
  123                 IPSEC6STAT_INC(ips_in_polvio);
  124                 m_freem(m);
  125                 return;
  126         }
  127 #endif /* IPSEC */
  128 
  129         /*
  130          * Do not forward packets to multicast destination (should be handled
  131          * by ip6_mforward().
  132          * Do not forward packets with unspecified source.  It was discussed
  133          * in July 2000, on the ipngwg mailing list.
  134          */
  135         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
  136             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
  137             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
  138                 IP6STAT_INC(ip6s_cantforward);
  139                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  140                 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
  141                         V_ip6_log_time = time_uptime;
  142                         log(LOG_DEBUG,
  143                             "cannot forward "
  144                             "from %s to %s nxt %d received on %s\n",
  145                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  146                             ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  147                             ip6->ip6_nxt,
  148                             if_name(m->m_pkthdr.rcvif));
  149                 }
  150                 m_freem(m);
  151                 return;
  152         }
  153 
  154 #ifdef IPSTEALTH
  155         if (!V_ip6stealth) {
  156 #endif
  157         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
  158                 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
  159                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
  160                                 ICMP6_TIME_EXCEED_TRANSIT, 0);
  161                 return;
  162         }
  163         ip6->ip6_hlim -= IPV6_HLIMDEC;
  164 
  165 #ifdef IPSTEALTH
  166         }
  167 #endif
  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 #ifdef IPSEC
  181         /* get a security policy for this packet */
  182         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
  183             IP_FORWARDING, &error);
  184         if (sp == NULL) {
  185                 IPSEC6STAT_INC(ips_out_inval);
  186                 IP6STAT_INC(ip6s_cantforward);
  187                 if (mcopy) {
  188 #if 0
  189                         /* XXX: what icmp ? */
  190 #else
  191                         m_freem(mcopy);
  192 #endif
  193                 }
  194                 m_freem(m);
  195                 return;
  196         }
  197 
  198         error = 0;
  199 
  200         /* check policy */
  201         switch (sp->policy) {
  202         case IPSEC_POLICY_DISCARD:
  203                 /*
  204                  * This packet is just discarded.
  205                  */
  206                 IPSEC6STAT_INC(ips_out_polvio);
  207                 IP6STAT_INC(ip6s_cantforward);
  208                 KEY_FREESP(&sp);
  209                 if (mcopy) {
  210 #if 0
  211                         /* XXX: what icmp ? */
  212 #else
  213                         m_freem(mcopy);
  214 #endif
  215                 }
  216                 m_freem(m);
  217                 return;
  218 
  219         case IPSEC_POLICY_BYPASS:
  220         case IPSEC_POLICY_NONE:
  221                 /* no need to do IPsec. */
  222                 KEY_FREESP(&sp);
  223                 goto skip_ipsec;
  224 
  225         case IPSEC_POLICY_IPSEC:
  226                 if (sp->req == NULL) {
  227                         /* XXX should be panic ? */
  228                         printf("ip6_forward: No IPsec request specified.\n");
  229                         IP6STAT_INC(ip6s_cantforward);
  230                         KEY_FREESP(&sp);
  231                         if (mcopy) {
  232 #if 0
  233                                 /* XXX: what icmp ? */
  234 #else
  235                                 m_freem(mcopy);
  236 #endif
  237                         }
  238                         m_freem(m);
  239                         return;
  240                 }
  241                 /* do IPsec */
  242                 break;
  243 
  244         case IPSEC_POLICY_ENTRUST:
  245         default:
  246                 /* should be panic ?? */
  247                 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
  248                 KEY_FREESP(&sp);
  249                 goto skip_ipsec;
  250         }
  251 
  252     {
  253         struct ipsecrequest *isr = NULL;
  254 
  255         /*
  256          * when the kernel forwards a packet, it is not proper to apply
  257          * IPsec transport mode to the packet is not proper.  this check
  258          * avoid from this.
  259          * at present, if there is even a transport mode SA request in the
  260          * security policy, the kernel does not apply IPsec to the packet.
  261          * this check is not enough because the following case is valid.
  262          *      ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
  263          */
  264         for (isr = sp->req; isr; isr = isr->next) {
  265                 if (isr->saidx.mode == IPSEC_MODE_ANY)
  266                         goto doipsectunnel;
  267                 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
  268                         goto doipsectunnel;
  269         }
  270 
  271         /*
  272          * if there's no need for tunnel mode IPsec, skip.
  273          */
  274         if (!isr)
  275                 goto skip_ipsec;
  276 
  277     doipsectunnel:
  278         /*
  279          * All the extension headers will become inaccessible
  280          * (since they can be encrypted).
  281          * Don't panic, we need no more updates to extension headers
  282          * on inner IPv6 packet (since they are now encapsulated).
  283          *
  284          * IPv6 [ESP|AH] IPv6 [extension headers] payload
  285          */
  286 
  287         /*
  288          * If we need to encapsulate the packet, do it here
  289          * ipsec6_proces_packet will send the packet using ip6_output
  290          */
  291         error = ipsec6_process_packet(m, sp->req);
  292 
  293         KEY_FREESP(&sp);
  294 
  295         if (error == EJUSTRETURN) {
  296                 /*
  297                  * We had a SP with a level of 'use' and no SA. We
  298                  * will just continue to process the packet without
  299                  * IPsec processing.
  300                  */
  301                 error = 0;
  302                 goto skip_ipsec;
  303         }
  304 
  305         if (error) {
  306                 /* mbuf is already reclaimed in ipsec6_process_packet. */
  307                 switch (error) {
  308                 case EHOSTUNREACH:
  309                 case ENETUNREACH:
  310                 case EMSGSIZE:
  311                 case ENOBUFS:
  312                 case ENOMEM:
  313                         break;
  314                 default:
  315                         printf("ip6_output (ipsec): error code %d\n", error);
  316                         /* FALLTHROUGH */
  317                 case ENOENT:
  318                         /* don't show these error codes to the user */
  319                         break;
  320                 }
  321                 IP6STAT_INC(ip6s_cantforward);
  322                 if (mcopy) {
  323 #if 0
  324                         /* XXX: what icmp ? */
  325 #else
  326                         m_freem(mcopy);
  327 #endif
  328                 }
  329                 return;
  330         } else {
  331                 /*
  332                  * In the FAST IPSec case we have already
  333                  * re-injected the packet and it has been freed
  334                  * by the ipsec_done() function.  So, just clean
  335                  * up after ourselves.
  336                  */
  337                 m = NULL;
  338                 goto freecopy;
  339         }
  340     }
  341 skip_ipsec:
  342 #endif
  343 again:
  344         bzero(&rin6, sizeof(struct route_in6));
  345         dst = (struct sockaddr_in6 *)&rin6.ro_dst;
  346         dst->sin6_len = sizeof(struct sockaddr_in6);
  347         dst->sin6_family = AF_INET6;
  348         dst->sin6_addr = ip6->ip6_dst;
  349 again2:
  350         rin6.ro_rt = in6_rtalloc1((struct sockaddr *)dst, 0, 0, M_GETFIB(m));
  351         if (rin6.ro_rt != NULL)
  352                 RT_UNLOCK(rin6.ro_rt);
  353         else {
  354                 IP6STAT_INC(ip6s_noroute);
  355                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
  356                 if (mcopy) {
  357                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  358                         ICMP6_DST_UNREACH_NOROUTE, 0);
  359                 }
  360                 goto bad;
  361         }
  362         rt = rin6.ro_rt;
  363 
  364         /*
  365          * Source scope check: if a packet can't be delivered to its
  366          * destination for the reason that the destination is beyond the scope
  367          * of the source address, discard the packet and return an icmp6
  368          * destination unreachable error with Code 2 (beyond scope of source
  369          * address).  We use a local copy of ip6_src, since in6_setscope()
  370          * will possibly modify its first argument.
  371          * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
  372          */
  373         src_in6 = ip6->ip6_src;
  374         if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
  375                 /* XXX: this should not happen */
  376                 IP6STAT_INC(ip6s_cantforward);
  377                 IP6STAT_INC(ip6s_badscope);
  378                 goto bad;
  379         }
  380         if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
  381                 IP6STAT_INC(ip6s_cantforward);
  382                 IP6STAT_INC(ip6s_badscope);
  383                 goto bad;
  384         }
  385         if (inzone != outzone
  386 #ifdef IPSEC
  387             && !ipsecrt
  388 #endif
  389             ) {
  390                 IP6STAT_INC(ip6s_cantforward);
  391                 IP6STAT_INC(ip6s_badscope);
  392                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
  393 
  394                 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
  395                         V_ip6_log_time = time_uptime;
  396                         log(LOG_DEBUG,
  397                             "cannot forward "
  398                             "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  399                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  400                             ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  401                             ip6->ip6_nxt,
  402                             if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
  403                 }
  404                 if (mcopy)
  405                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  406                                     ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
  407                 goto bad;
  408         }
  409 
  410         /*
  411          * Destination scope check: if a packet is going to break the scope
  412          * zone of packet's destination address, discard it.  This case should
  413          * usually be prevented by appropriately-configured routing table, but
  414          * we need an explicit check because we may mistakenly forward the
  415          * packet to a different zone by (e.g.) a default route.
  416          */
  417         dst_in6 = ip6->ip6_dst;
  418         if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
  419             in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
  420             inzone != outzone) {
  421                 IP6STAT_INC(ip6s_cantforward);
  422                 IP6STAT_INC(ip6s_badscope);
  423                 goto bad;
  424         }
  425 
  426         if (rt->rt_flags & RTF_GATEWAY)
  427                 dst = (struct sockaddr_in6 *)rt->rt_gateway;
  428 
  429         /*
  430          * If we are to forward the packet using the same interface
  431          * as one we got the packet from, perhaps we should send a redirect
  432          * to sender to shortcut a hop.
  433          * Only send redirect if source is sending directly to us,
  434          * and if packet was not source routed (or has any options).
  435          * Also, don't send redirect if forwarding using a route
  436          * modified by a redirect.
  437          */
  438         if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
  439 #ifdef IPSEC
  440             !ipsecrt &&
  441 #endif /* IPSEC */
  442             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
  443                 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
  444                         /*
  445                          * If the incoming interface is equal to the outgoing
  446                          * one, and the link attached to the interface is
  447                          * point-to-point, then it will be highly probable
  448                          * that a routing loop occurs. Thus, we immediately
  449                          * drop the packet and send an ICMPv6 error message.
  450                          *
  451                          * type/code is based on suggestion by Rich Draves.
  452                          * not sure if it is the best pick.
  453                          */
  454                         icmp6_error(mcopy, ICMP6_DST_UNREACH,
  455                                     ICMP6_DST_UNREACH_ADDR, 0);
  456                         goto bad;
  457                 }
  458                 type = ND_REDIRECT;
  459         }
  460 
  461         /*
  462          * Fake scoped addresses. Note that even link-local source or
  463          * destinaion can appear, if the originating node just sends the
  464          * packet to us (without address resolution for the destination).
  465          * Since both icmp6_error and icmp6_redirect_output fill the embedded
  466          * link identifiers, we can do this stuff after making a copy for
  467          * returning an error.
  468          */
  469         if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
  470                 /*
  471                  * See corresponding comments in ip6_output.
  472                  * XXX: but is it possible that ip6_forward() sends a packet
  473                  *      to a loopback interface? I don't think so, and thus
  474                  *      I bark here. (jinmei@kame.net)
  475                  * XXX: it is common to route invalid packets to loopback.
  476                  *      also, the codepath will be visited on use of ::1 in
  477                  *      rthdr. (itojun)
  478                  */
  479 #if 1
  480                 if (0)
  481 #else
  482                 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
  483 #endif
  484                 {
  485                         printf("ip6_forward: outgoing interface is loopback. "
  486                                "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
  487                                ip6_sprintf(ip6bufs, &ip6->ip6_src),
  488                                ip6_sprintf(ip6bufd, &ip6->ip6_dst),
  489                                ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
  490                                if_name(rt->rt_ifp));
  491                 }
  492 
  493                 /* we can just use rcvif in forwarding. */
  494                 origifp = m->m_pkthdr.rcvif;
  495         }
  496         else
  497                 origifp = rt->rt_ifp;
  498         /*
  499          * clear embedded scope identifiers if necessary.
  500          * in6_clearscope will touch the addresses only when necessary.
  501          */
  502         in6_clearscope(&ip6->ip6_src);
  503         in6_clearscope(&ip6->ip6_dst);
  504 
  505         /* Jump over all PFIL processing if hooks are not active. */
  506         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  507                 goto pass;
  508 
  509         odst = ip6->ip6_dst;
  510         /* Run through list of hooks for output packets. */
  511         error = pfil_run_hooks(&V_inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
  512         if (error != 0 || m == NULL)
  513                 goto freecopy;          /* consumed by filter */
  514         ip6 = mtod(m, struct ip6_hdr *);
  515 
  516         /* See if destination IP address was changed by packet filter. */
  517         if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
  518                 m->m_flags |= M_SKIP_FIREWALL;
  519                 /* If destination is now ourself drop to ip6_input(). */
  520                 if (in6_localip(&ip6->ip6_dst))
  521                         m->m_flags |= M_FASTFWD_OURS;
  522                 else
  523                         goto again;     /* Redo the routing table lookup. */
  524         }
  525 
  526         /* See if local, if yes, send it to netisr. */
  527         if (m->m_flags & M_FASTFWD_OURS) {
  528                 if (m->m_pkthdr.rcvif == NULL)
  529                         m->m_pkthdr.rcvif = V_loif;
  530                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
  531                         m->m_pkthdr.csum_flags |=
  532                             CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
  533                         m->m_pkthdr.csum_data = 0xffff;
  534                 }
  535 #ifdef SCTP
  536                 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
  537                         m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
  538 #endif
  539                 error = netisr_queue(NETISR_IPV6, m);
  540                 goto out;
  541         }
  542         /* Or forward to some other address? */
  543         if ((m->m_flags & M_IP6_NEXTHOP) &&
  544             (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
  545                 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
  546                 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in6));
  547                 m->m_flags |= M_SKIP_FIREWALL;
  548                 m->m_flags &= ~M_IP6_NEXTHOP;
  549                 m_tag_delete(m, fwd_tag);
  550                 goto again2;
  551         }
  552 
  553 pass:
  554         /* See if the size was changed by the packet filter. */
  555         if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
  556                 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
  557                 if (mcopy) {
  558                         u_long mtu;
  559 #ifdef IPSEC
  560                         struct secpolicy *sp;
  561                         int ipsecerror;
  562                         size_t ipsechdrsiz;
  563 #endif /* IPSEC */
  564 
  565                         mtu = IN6_LINKMTU(rt->rt_ifp);
  566 #ifdef IPSEC
  567                         /*
  568                          * When we do IPsec tunnel ingress, we need to play
  569                          * with the link value (decrement IPsec header size
  570                          * from mtu value).  The code is much simpler than v4
  571                          * case, as we have the outgoing interface for
  572                          * encapsulated packet as "rt->rt_ifp".
  573                          */
  574                         sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
  575                                 IP_FORWARDING, &ipsecerror);
  576                         if (sp) {
  577                                 ipsechdrsiz = ipsec_hdrsiz(mcopy,
  578                                         IPSEC_DIR_OUTBOUND, NULL);
  579                                 if (ipsechdrsiz < mtu)
  580                                         mtu -= ipsechdrsiz;
  581                         }
  582 
  583                         /*
  584                          * if mtu becomes less than minimum MTU,
  585                          * tell minimum MTU (and I'll need to fragment it).
  586                          */
  587                         if (mtu < IPV6_MMTU)
  588                                 mtu = IPV6_MMTU;
  589 #endif /* IPSEC */
  590                         icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
  591                 }
  592                 goto bad;
  593         }
  594 
  595         error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
  596         if (error) {
  597                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
  598                 IP6STAT_INC(ip6s_cantforward);
  599         } else {
  600                 IP6STAT_INC(ip6s_forward);
  601                 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
  602                 if (type)
  603                         IP6STAT_INC(ip6s_redirectsent);
  604                 else {
  605                         if (mcopy)
  606                                 goto freecopy;
  607                 }
  608         }
  609 
  610         if (mcopy == NULL)
  611                 goto out;
  612         switch (error) {
  613         case 0:
  614                 if (type == ND_REDIRECT) {
  615                         icmp6_redirect_output(mcopy, rt);
  616                         goto out;
  617                 }
  618                 goto freecopy;
  619 
  620         case EMSGSIZE:
  621                 /* xxx MTU is constant in PPP? */
  622                 goto freecopy;
  623 
  624         case ENOBUFS:
  625                 /* Tell source to slow down like source quench in IP? */
  626                 goto freecopy;
  627 
  628         case ENETUNREACH:       /* shouldn't happen, checked above */
  629         case EHOSTUNREACH:
  630         case ENETDOWN:
  631         case EHOSTDOWN:
  632         default:
  633                 type = ICMP6_DST_UNREACH;
  634                 code = ICMP6_DST_UNREACH_ADDR;
  635                 break;
  636         }
  637         icmp6_error(mcopy, type, code, 0);
  638         goto out;
  639 
  640  freecopy:
  641         m_freem(mcopy);
  642         goto out;
  643 bad:
  644         m_freem(m);
  645 out:
  646         if (rt != NULL
  647 #ifdef IPSEC
  648             && !ipsecrt
  649 #endif
  650             )
  651                 RTFREE(rt);
  652 }

Cache object: 48aa80506394a73295c4cc2eea513233


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