The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_input.c

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    1 /*      $FreeBSD: releng/6.0/sys/netinet6/ip6_input.c 151159 2005-10-09 05:21:18Z ume $ */
    2 /*      $KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei 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  * Copyright (c) 1982, 1986, 1988, 1993
   35  *      The Regents of the University of California.  All rights reserved.
   36  *
   37  * Redistribution and use in source and binary forms, with or without
   38  * modification, are permitted provided that the following conditions
   39  * are met:
   40  * 1. Redistributions of source code must retain the above copyright
   41  *    notice, this list of conditions and the following disclaimer.
   42  * 2. Redistributions in binary form must reproduce the above copyright
   43  *    notice, this list of conditions and the following disclaimer in the
   44  *    documentation and/or other materials provided with the distribution.
   45  * 4. Neither the name of the University nor the names of its contributors
   46  *    may be used to endorse or promote products derived from this software
   47  *    without specific prior written permission.
   48  *
   49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   59  * SUCH DAMAGE.
   60  *
   61  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
   62  */
   63 
   64 #include "opt_ip6fw.h"
   65 #include "opt_inet.h"
   66 #include "opt_inet6.h"
   67 #include "opt_ipsec.h"
   68 
   69 #include <sys/param.h>
   70 #include <sys/systm.h>
   71 #include <sys/malloc.h>
   72 #include <sys/mbuf.h>
   73 #include <sys/proc.h>
   74 #include <sys/domain.h>
   75 #include <sys/protosw.h>
   76 #include <sys/socket.h>
   77 #include <sys/socketvar.h>
   78 #include <sys/errno.h>
   79 #include <sys/time.h>
   80 #include <sys/kernel.h>
   81 #include <sys/syslog.h>
   82 
   83 #include <net/if.h>
   84 #include <net/if_types.h>
   85 #include <net/if_dl.h>
   86 #include <net/route.h>
   87 #include <net/netisr.h>
   88 #include <net/pfil.h>
   89 
   90 #include <netinet/in.h>
   91 #include <netinet/in_systm.h>
   92 #ifdef INET
   93 #include <netinet/ip.h>
   94 #include <netinet/ip_icmp.h>
   95 #endif /* INET */
   96 #include <netinet/ip6.h>
   97 #include <netinet6/in6_var.h>
   98 #include <netinet6/ip6_var.h>
   99 #include <netinet/in_pcb.h>
  100 #include <netinet/icmp6.h>
  101 #include <netinet6/scope6_var.h>
  102 #include <netinet6/in6_ifattach.h>
  103 #include <netinet6/nd6.h>
  104 
  105 #ifdef IPSEC
  106 #include <netinet6/ipsec.h>
  107 #ifdef INET6
  108 #include <netinet6/ipsec6.h>
  109 #endif
  110 #endif
  111 
  112 #ifdef FAST_IPSEC
  113 #include <netipsec/ipsec.h>
  114 #include <netipsec/ipsec6.h>
  115 #define IPSEC
  116 #endif /* FAST_IPSEC */
  117 
  118 #include <netinet6/ip6_fw.h>
  119 
  120 #include <netinet6/ip6protosw.h>
  121 
  122 #include <net/net_osdep.h>
  123 
  124 extern struct domain inet6domain;
  125 
  126 u_char ip6_protox[IPPROTO_MAX];
  127 static struct ifqueue ip6intrq;
  128 static int ip6qmaxlen = IFQ_MAXLEN;
  129 struct in6_ifaddr *in6_ifaddr;
  130 
  131 extern struct callout in6_tmpaddrtimer_ch;
  132 
  133 int ip6_forward_srcrt;                  /* XXX */
  134 int ip6_sourcecheck;                    /* XXX */
  135 int ip6_sourcecheck_interval;           /* XXX */
  136 
  137 int ip6_ours_check_algorithm;
  138 
  139 struct pfil_head inet6_pfil_hook;
  140 
  141 /* firewall hooks */
  142 ip6_fw_chk_t *ip6_fw_chk_ptr;
  143 ip6_fw_ctl_t *ip6_fw_ctl_ptr;
  144 int ip6_fw_enable = 1;
  145 
  146 struct ip6stat ip6stat;
  147 
  148 static void ip6_init2 __P((void *));
  149 static struct ip6aux *ip6_setdstifaddr __P((struct mbuf *, struct in6_ifaddr *));
  150 static int ip6_hopopts_input __P((u_int32_t *, u_int32_t *, struct mbuf **, int *));
  151 #ifdef PULLDOWN_TEST
  152 static struct mbuf *ip6_pullexthdr __P((struct mbuf *, size_t, int));
  153 #endif
  154 
  155 /*
  156  * IP6 initialization: fill in IP6 protocol switch table.
  157  * All protocols not implemented in kernel go to raw IP6 protocol handler.
  158  */
  159 void
  160 ip6_init()
  161 {
  162         struct ip6protosw *pr;
  163         int i;
  164 
  165 #ifdef DIAGNOSTIC
  166         if (sizeof(struct protosw) != sizeof(struct ip6protosw))
  167                 panic("sizeof(protosw) != sizeof(ip6protosw)");
  168 #endif
  169         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  170         if (pr == 0)
  171                 panic("ip6_init");
  172 
  173         /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
  174         for (i = 0; i < IPPROTO_MAX; i++)
  175                 ip6_protox[i] = pr - inet6sw;
  176         /*
  177          * Cycle through IP protocols and put them into the appropriate place
  178          * in ip6_protox[].
  179          */
  180         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  181             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++)
  182                 if (pr->pr_domain->dom_family == PF_INET6 &&
  183                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  184                         /* Be careful to only index valid IP protocols. */
  185                         if (pr->pr_protocol < IPPROTO_MAX)
  186                                 ip6_protox[pr->pr_protocol] = pr - inet6sw;
  187                 }
  188 
  189         /* Initialize packet filter hooks. */
  190         inet6_pfil_hook.ph_type = PFIL_TYPE_AF;
  191         inet6_pfil_hook.ph_af = AF_INET6;
  192         if ((i = pfil_head_register(&inet6_pfil_hook)) != 0)
  193                 printf("%s: WARNING: unable to register pfil hook, "
  194                         "error %d\n", __func__, i);
  195 
  196         ip6intrq.ifq_maxlen = ip6qmaxlen;
  197         mtx_init(&ip6intrq.ifq_mtx, "ip6_inq", NULL, MTX_DEF);
  198         netisr_register(NETISR_IPV6, ip6_input, &ip6intrq, 0);
  199         scope6_init();
  200         addrsel_policy_init();
  201         nd6_init();
  202         frag6_init();
  203         ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
  204 }
  205 
  206 static void
  207 ip6_init2(dummy)
  208         void *dummy;
  209 {
  210 
  211         /* nd6_timer_init */
  212         callout_init(&nd6_timer_ch, 0);
  213         callout_reset(&nd6_timer_ch, hz, nd6_timer, NULL);
  214 
  215         /* timer for regeneranation of temporary addresses randomize ID */
  216         callout_init(&in6_tmpaddrtimer_ch, 0);
  217         callout_reset(&in6_tmpaddrtimer_ch,
  218                       (ip6_temp_preferred_lifetime - ip6_desync_factor -
  219                        ip6_temp_regen_advance) * hz,
  220                       in6_tmpaddrtimer, NULL);
  221 }
  222 
  223 /* cheat */
  224 /* This must be after route_init(), which is now SI_ORDER_THIRD */
  225 SYSINIT(netinet6init2, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ip6_init2, NULL);
  226 
  227 extern struct   route_in6 ip6_forward_rt;
  228 
  229 void
  230 ip6_input(m)
  231         struct mbuf *m;
  232 {
  233         struct ip6_hdr *ip6;
  234         int off = sizeof(struct ip6_hdr), nest;
  235         u_int32_t plen;
  236         u_int32_t rtalert = ~0;
  237         int nxt, ours = 0;
  238         struct ifnet *deliverifp = NULL;
  239         struct sockaddr_in6 sa6;
  240         u_int32_t srczone, dstzone;
  241         struct in6_addr odst;
  242         int srcrt = 0;
  243 
  244         GIANT_REQUIRED;                 /* XXX for now */
  245 #ifdef IPSEC
  246         /*
  247          * should the inner packet be considered authentic?
  248          * see comment in ah4_input().
  249          */
  250         if (m) {
  251                 m->m_flags &= ~M_AUTHIPHDR;
  252                 m->m_flags &= ~M_AUTHIPDGM;
  253         }
  254 #endif
  255 
  256         /*
  257          * make sure we don't have onion peering information into m_tag.
  258          */
  259         ip6_delaux(m);
  260 
  261         /*
  262          * mbuf statistics
  263          */
  264         if (m->m_flags & M_EXT) {
  265                 if (m->m_next)
  266                         ip6stat.ip6s_mext2m++;
  267                 else
  268                         ip6stat.ip6s_mext1++;
  269         } else {
  270 #define M2MMAX  (sizeof(ip6stat.ip6s_m2m)/sizeof(ip6stat.ip6s_m2m[0]))
  271                 if (m->m_next) {
  272                         if (m->m_flags & M_LOOP) {
  273                                 ip6stat.ip6s_m2m[loif[0].if_index]++; /* XXX */
  274                         } else if (m->m_pkthdr.rcvif->if_index < M2MMAX)
  275                                 ip6stat.ip6s_m2m[m->m_pkthdr.rcvif->if_index]++;
  276                         else
  277                                 ip6stat.ip6s_m2m[0]++;
  278                 } else
  279                         ip6stat.ip6s_m1++;
  280 #undef M2MMAX
  281         }
  282 
  283         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_receive);
  284         ip6stat.ip6s_total++;
  285 
  286 #ifndef PULLDOWN_TEST
  287         /*
  288          * L2 bridge code and some other code can return mbuf chain
  289          * that does not conform to KAME requirement.  too bad.
  290          * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
  291          */
  292         if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
  293                 struct mbuf *n;
  294 
  295                 MGETHDR(n, M_DONTWAIT, MT_HEADER);
  296                 if (n)
  297                         M_MOVE_PKTHDR(n, m);
  298                 if (n && n->m_pkthdr.len > MHLEN) {
  299                         MCLGET(n, M_DONTWAIT);
  300                         if ((n->m_flags & M_EXT) == 0) {
  301                                 m_freem(n);
  302                                 n = NULL;
  303                         }
  304                 }
  305                 if (n == NULL) {
  306                         m_freem(m);
  307                         return; /* ENOBUFS */
  308                 }
  309 
  310                 m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
  311                 n->m_len = n->m_pkthdr.len;
  312                 m_freem(m);
  313                 m = n;
  314         }
  315         IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), /* nothing */);
  316 #endif
  317 
  318         if (m->m_len < sizeof(struct ip6_hdr)) {
  319                 struct ifnet *inifp;
  320                 inifp = m->m_pkthdr.rcvif;
  321                 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
  322                         ip6stat.ip6s_toosmall++;
  323                         in6_ifstat_inc(inifp, ifs6_in_hdrerr);
  324                         return;
  325                 }
  326         }
  327 
  328         ip6 = mtod(m, struct ip6_hdr *);
  329 
  330         if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
  331                 ip6stat.ip6s_badvers++;
  332                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  333                 goto bad;
  334         }
  335 
  336         ip6stat.ip6s_nxthist[ip6->ip6_nxt]++;
  337 
  338         /*
  339          * Check against address spoofing/corruption.
  340          */
  341         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
  342             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
  343                 /*
  344                  * XXX: "badscope" is not very suitable for a multicast source.
  345                  */
  346                 ip6stat.ip6s_badscope++;
  347                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  348                 goto bad;
  349         }
  350         if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
  351             !(m->m_flags & M_LOOP)) {
  352                 /*
  353                  * In this case, the packet should come from the loopback
  354                  * interface.  However, we cannot just check the if_flags,
  355                  * because ip6_mloopback() passes the "actual" interface
  356                  * as the outgoing/incoming interface.
  357                  */
  358                 ip6stat.ip6s_badscope++;
  359                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  360                 goto bad;
  361         }
  362 
  363 #ifdef ALTQ
  364         if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
  365                 /* packet is dropped by traffic conditioner */
  366                 return;
  367         }
  368 #endif
  369         /*
  370          * The following check is not documented in specs.  A malicious
  371          * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
  372          * and bypass security checks (act as if it was from 127.0.0.1 by using
  373          * IPv6 src ::ffff:127.0.0.1).  Be cautious.
  374          *
  375          * This check chokes if we are in an SIIT cloud.  As none of BSDs
  376          * support IPv4-less kernel compilation, we cannot support SIIT
  377          * environment at all.  So, it makes more sense for us to reject any
  378          * malicious packets for non-SIIT environment, than try to do a
  379          * partial support for SIIT environment.
  380          */
  381         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  382             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  383                 ip6stat.ip6s_badscope++;
  384                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  385                 goto bad;
  386         }
  387 #if 0
  388         /*
  389          * Reject packets with IPv4 compatible addresses (auto tunnel).
  390          *
  391          * The code forbids auto tunnel relay case in RFC1933 (the check is
  392          * stronger than RFC1933).  We may want to re-enable it if mech-xx
  393          * is revised to forbid relaying case.
  394          */
  395         if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
  396             IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
  397                 ip6stat.ip6s_badscope++;
  398                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  399                 goto bad;
  400         }
  401 #endif
  402 
  403         /*
  404          * Drop packets if the link ID portion is already filled.
  405          * XXX: this is technically not a good behavior.  But, we internally
  406          * use the field to disambiguate link-local addresses, so we cannot
  407          * be generous against those a bit strange addresses.
  408          */
  409         if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
  410                 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src) &&
  411                     ip6->ip6_src.s6_addr16[1]) {
  412                         ip6stat.ip6s_badscope++;
  413                         goto bad;
  414                 }
  415                 if ((IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) ||
  416                      IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) &&
  417                     ip6->ip6_dst.s6_addr16[1]) {
  418                         ip6stat.ip6s_badscope++;
  419                         goto bad;
  420                 }
  421         }
  422 
  423         /*
  424          * Run through list of hooks for input packets.
  425          *
  426          * NB: Beware of the destination address changing
  427          *     (e.g. by NAT rewriting).  When this happens,
  428          *     tell ip6_forward to do the right thing.
  429          */
  430         odst = ip6->ip6_dst;
  431 
  432         /* Jump over all PFIL processing if hooks are not active. */
  433         if (inet6_pfil_hook.ph_busy_count == -1)
  434                 goto passin;
  435 
  436         if (pfil_run_hooks(&inet6_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL))
  437                 return;
  438         if (m == NULL)                  /* consumed by filter */
  439                 return;
  440         ip6 = mtod(m, struct ip6_hdr *);
  441         srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
  442 
  443 passin:
  444         /*
  445          * Check with the firewall...
  446          */
  447         if (ip6_fw_enable && ip6_fw_chk_ptr) {
  448                 u_short port = 0;
  449                 /* If ipfw says divert, we have to just drop packet */
  450                 /* use port as a dummy argument */
  451                 if ((*ip6_fw_chk_ptr)(&ip6, NULL, &port, &m)) {
  452                         m_freem(m);
  453                         m = NULL;
  454                 }
  455                 if (!m)
  456                         return;
  457         }
  458 
  459         /*
  460          * construct source and destination address structures with
  461          * disambiguating their scope zones (if there is ambiguity).
  462          * XXX: sin6_family and sin6_len will NOT be referred to, but we fill
  463          * in these fields just in case.
  464          */
  465         if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
  466             in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_dst, &dstzone)) {
  467                 /*
  468                  * Note that these generic checks cover cases that src or
  469                  * dst are the loopback address and the receiving interface
  470                  * is not loopback.
  471                  */
  472                 ip6stat.ip6s_badscope++;
  473                 goto bad;
  474         }
  475 
  476         bzero(&sa6, sizeof(sa6));
  477         sa6.sin6_family = AF_INET6;
  478         sa6.sin6_len = sizeof(struct sockaddr_in6);
  479 
  480         sa6.sin6_addr = ip6->ip6_src;
  481         sa6.sin6_scope_id = srczone;
  482         if (in6_embedscope(&ip6->ip6_src, &sa6, NULL, NULL)) {
  483                 /* XXX: should not happen */
  484                 ip6stat.ip6s_badscope++;
  485                 goto bad;
  486         }
  487 
  488         sa6.sin6_addr = ip6->ip6_dst;
  489         sa6.sin6_scope_id = dstzone;
  490         if (in6_embedscope(&ip6->ip6_dst, &sa6, NULL, NULL)) {
  491                 /* XXX: should not happen */
  492                 ip6stat.ip6s_badscope++;
  493                 goto bad;
  494         }
  495 
  496         /* XXX: ff01::%ifN awareness is not merged, yet. */
  497         if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_src))
  498                 ip6->ip6_src.s6_addr16[1] = 0;
  499         if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst))
  500                 ip6->ip6_dst.s6_addr16[1] = 0;
  501 
  502         /*
  503          * Multicast check
  504          */
  505         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  506                 struct in6_multi *in6m = 0;
  507 
  508                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mcast);
  509                 /*
  510                  * See if we belong to the destination multicast group on the
  511                  * arrival interface.
  512                  */
  513                 IN6_LOOKUP_MULTI(ip6->ip6_dst, m->m_pkthdr.rcvif, in6m);
  514                 if (in6m)
  515                         ours = 1;
  516                 else if (!ip6_mrouter) {
  517                         ip6stat.ip6s_notmember++;
  518                         ip6stat.ip6s_cantforward++;
  519                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  520                         goto bad;
  521                 }
  522                 deliverifp = m->m_pkthdr.rcvif;
  523                 goto hbhcheck;
  524         }
  525 
  526         /*
  527          *  Unicast check
  528          */
  529         if (ip6_forward_rt.ro_rt != NULL &&
  530             (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) != 0 &&
  531             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  532             &((struct sockaddr_in6 *)(&ip6_forward_rt.ro_dst))->sin6_addr))
  533                 ip6stat.ip6s_forward_cachehit++;
  534         else {
  535                 struct sockaddr_in6 *dst6;
  536 
  537                 if (ip6_forward_rt.ro_rt) {
  538                         /* route is down or destination is different */
  539                         ip6stat.ip6s_forward_cachemiss++;
  540                         RTFREE(ip6_forward_rt.ro_rt);
  541                         ip6_forward_rt.ro_rt = 0;
  542                 }
  543 
  544                 bzero(&ip6_forward_rt.ro_dst, sizeof(struct sockaddr_in6));
  545                 dst6 = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
  546                 dst6->sin6_len = sizeof(struct sockaddr_in6);
  547                 dst6->sin6_family = AF_INET6;
  548                 dst6->sin6_addr = ip6->ip6_dst;
  549 
  550                 rtalloc((struct route *)&ip6_forward_rt);
  551         }
  552 
  553 #define rt6_key(r) ((struct sockaddr_in6 *)((r)->rt_nodes->rn_key))
  554 
  555         /*
  556          * Accept the packet if the forwarding interface to the destination
  557          * according to the routing table is the loopback interface,
  558          * unless the associated route has a gateway.
  559          * Note that this approach causes to accept a packet if there is a
  560          * route to the loopback interface for the destination of the packet.
  561          * But we think it's even useful in some situations, e.g. when using
  562          * a special daemon which wants to intercept the packet.
  563          *
  564          * XXX: some OSes automatically make a cloned route for the destination
  565          * of an outgoing packet.  If the outgoing interface of the packet
  566          * is a loopback one, the kernel would consider the packet to be
  567          * accepted, even if we have no such address assinged on the interface.
  568          * We check the cloned flag of the route entry to reject such cases,
  569          * assuming that route entries for our own addresses are not made by
  570          * cloning (it should be true because in6_addloop explicitly installs
  571          * the host route).  However, we might have to do an explicit check
  572          * while it would be less efficient.  Or, should we rather install a
  573          * reject route for such a case?
  574          */
  575         if (ip6_forward_rt.ro_rt &&
  576             (ip6_forward_rt.ro_rt->rt_flags &
  577              (RTF_HOST|RTF_GATEWAY)) == RTF_HOST &&
  578 #ifdef RTF_WASCLONED
  579             !(ip6_forward_rt.ro_rt->rt_flags & RTF_WASCLONED) &&
  580 #endif
  581 #ifdef RTF_CLONED
  582             !(ip6_forward_rt.ro_rt->rt_flags & RTF_CLONED) &&
  583 #endif
  584 #if 0
  585             /*
  586              * The check below is redundant since the comparison of
  587              * the destination and the key of the rtentry has
  588              * already done through looking up the routing table.
  589              */
  590             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  591             &rt6_key(ip6_forward_rt.ro_rt)->sin6_addr)
  592 #endif
  593             ip6_forward_rt.ro_rt->rt_ifp->if_type == IFT_LOOP) {
  594                 struct in6_ifaddr *ia6 =
  595                         (struct in6_ifaddr *)ip6_forward_rt.ro_rt->rt_ifa;
  596 
  597                 /*
  598                  * record address information into m_tag.
  599                  */
  600                 (void)ip6_setdstifaddr(m, ia6);
  601 
  602                 /*
  603                  * packets to a tentative, duplicated, or somehow invalid
  604                  * address must not be accepted.
  605                  */
  606                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  607                         /* this address is ready */
  608                         ours = 1;
  609                         deliverifp = ia6->ia_ifp;       /* correct? */
  610                         /* Count the packet in the ip address stats */
  611                         ia6->ia_ifa.if_ipackets++;
  612                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  613                         goto hbhcheck;
  614                 } else {
  615                         /* address is not ready, so discard the packet. */
  616                         nd6log((LOG_INFO,
  617                             "ip6_input: packet to an unready address %s->%s\n",
  618                             ip6_sprintf(&ip6->ip6_src),
  619                             ip6_sprintf(&ip6->ip6_dst)));
  620 
  621                         goto bad;
  622                 }
  623         }
  624 
  625         /*
  626          * FAITH (Firewall Aided Internet Translator)
  627          */
  628         if (ip6_keepfaith) {
  629                 if (ip6_forward_rt.ro_rt && ip6_forward_rt.ro_rt->rt_ifp
  630                  && ip6_forward_rt.ro_rt->rt_ifp->if_type == IFT_FAITH) {
  631                         /* XXX do we need more sanity checks? */
  632                         ours = 1;
  633                         deliverifp = ip6_forward_rt.ro_rt->rt_ifp; /* faith */
  634                         goto hbhcheck;
  635                 }
  636         }
  637 
  638         /*
  639          * Now there is no reason to process the packet if it's not our own
  640          * and we're not a router.
  641          */
  642         if (!ip6_forwarding) {
  643                 ip6stat.ip6s_cantforward++;
  644                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  645                 goto bad;
  646         }
  647 
  648   hbhcheck:
  649         /*
  650          * record address information into m_tag, if we don't have one yet.
  651          * note that we are unable to record it, if the address is not listed
  652          * as our interface address (e.g. multicast addresses, addresses
  653          * within FAITH prefixes and such).
  654          */
  655         if (deliverifp && !ip6_getdstifaddr(m)) {
  656                 struct in6_ifaddr *ia6;
  657 
  658                 ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
  659                 if (ia6) {
  660                         if (!ip6_setdstifaddr(m, ia6)) {
  661                                 /*
  662                                  * XXX maybe we should drop the packet here,
  663                                  * as we could not provide enough information
  664                                  * to the upper layers.
  665                                  */
  666                         }
  667                 }
  668         }
  669 
  670         /*
  671          * Process Hop-by-Hop options header if it's contained.
  672          * m may be modified in ip6_hopopts_input().
  673          * If a JumboPayload option is included, plen will also be modified.
  674          */
  675         plen = (u_int32_t)ntohs(ip6->ip6_plen);
  676         if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
  677                 struct ip6_hbh *hbh;
  678 
  679                 if (ip6_hopopts_input(&plen, &rtalert, &m, &off)) {
  680 #if 0   /*touches NULL pointer*/
  681                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  682 #endif
  683                         return; /* m have already been freed */
  684                 }
  685 
  686                 /* adjust pointer */
  687                 ip6 = mtod(m, struct ip6_hdr *);
  688 
  689                 /*
  690                  * if the payload length field is 0 and the next header field
  691                  * indicates Hop-by-Hop Options header, then a Jumbo Payload
  692                  * option MUST be included.
  693                  */
  694                 if (ip6->ip6_plen == 0 && plen == 0) {
  695                         /*
  696                          * Note that if a valid jumbo payload option is
  697                          * contained, ip6_hopopts_input() must set a valid
  698                          * (non-zero) payload length to the variable plen.
  699                          */
  700                         ip6stat.ip6s_badoptions++;
  701                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  702                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  703                         icmp6_error(m, ICMP6_PARAM_PROB,
  704                                     ICMP6_PARAMPROB_HEADER,
  705                                     (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
  706                         return;
  707                 }
  708 #ifndef PULLDOWN_TEST
  709                 /* ip6_hopopts_input() ensures that mbuf is contiguous */
  710                 hbh = (struct ip6_hbh *)(ip6 + 1);
  711 #else
  712                 IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  713                         sizeof(struct ip6_hbh));
  714                 if (hbh == NULL) {
  715                         ip6stat.ip6s_tooshort++;
  716                         return;
  717                 }
  718 #endif
  719                 nxt = hbh->ip6h_nxt;
  720 
  721                 /*
  722                  * accept the packet if a router alert option is included
  723                  * and we act as an IPv6 router.
  724                  */
  725                 if (rtalert != ~0 && ip6_forwarding)
  726                         ours = 1;
  727         } else
  728                 nxt = ip6->ip6_nxt;
  729 
  730         /*
  731          * Check that the amount of data in the buffers
  732          * is as at least much as the IPv6 header would have us expect.
  733          * Trim mbufs if longer than we expect.
  734          * Drop packet if shorter than we expect.
  735          */
  736         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
  737                 ip6stat.ip6s_tooshort++;
  738                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  739                 goto bad;
  740         }
  741         if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
  742                 if (m->m_len == m->m_pkthdr.len) {
  743                         m->m_len = sizeof(struct ip6_hdr) + plen;
  744                         m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
  745                 } else
  746                         m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
  747         }
  748 
  749         /*
  750          * Forward if desirable.
  751          */
  752         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  753                 /*
  754                  * If we are acting as a multicast router, all
  755                  * incoming multicast packets are passed to the
  756                  * kernel-level multicast forwarding function.
  757                  * The packet is returned (relatively) intact; if
  758                  * ip6_mforward() returns a non-zero value, the packet
  759                  * must be discarded, else it may be accepted below.
  760                  */
  761                 if (ip6_mrouter && ip6_mforward(ip6, m->m_pkthdr.rcvif, m)) {
  762                         ip6stat.ip6s_cantforward++;
  763                         m_freem(m);
  764                         return;
  765                 }
  766                 if (!ours) {
  767                         m_freem(m);
  768                         return;
  769                 }
  770         } else if (!ours) {
  771                 ip6_forward(m, srcrt);
  772                 return;
  773         }
  774 
  775         ip6 = mtod(m, struct ip6_hdr *);
  776 
  777         /*
  778          * Malicious party may be able to use IPv4 mapped addr to confuse
  779          * tcp/udp stack and bypass security checks (act as if it was from
  780          * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
  781          *
  782          * For SIIT end node behavior, you may want to disable the check.
  783          * However, you will  become vulnerable to attacks using IPv4 mapped
  784          * source.
  785          */
  786         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  787             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  788                 ip6stat.ip6s_badscope++;
  789                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  790                 goto bad;
  791         }
  792 
  793         /*
  794          * Tell launch routine the next header
  795          */
  796         ip6stat.ip6s_delivered++;
  797         in6_ifstat_inc(deliverifp, ifs6_in_deliver);
  798         nest = 0;
  799 
  800         while (nxt != IPPROTO_DONE) {
  801                 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
  802                         ip6stat.ip6s_toomanyhdr++;
  803                         goto bad;
  804                 }
  805 
  806                 /*
  807                  * protection against faulty packet - there should be
  808                  * more sanity checks in header chain processing.
  809                  */
  810                 if (m->m_pkthdr.len < off) {
  811                         ip6stat.ip6s_tooshort++;
  812                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  813                         goto bad;
  814                 }
  815 
  816 #ifdef IPSEC
  817                 /*
  818                  * enforce IPsec policy checking if we are seeing last header.
  819                  * note that we do not visit this with protocols with pcb layer
  820                  * code - like udp/tcp/raw ip.
  821                  */
  822                 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  823                     ipsec6_in_reject(m, NULL)) {
  824                         ipsec6stat.in_polvio++;
  825                         goto bad;
  826                 }
  827 #endif
  828                 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
  829         }
  830         return;
  831  bad:
  832         m_freem(m);
  833 }
  834 
  835 /*
  836  * set/grab in6_ifaddr correspond to IPv6 destination address.
  837  * XXX backward compatibility wrapper
  838  */
  839 static struct ip6aux *
  840 ip6_setdstifaddr(m, ia6)
  841         struct mbuf *m;
  842         struct in6_ifaddr *ia6;
  843 {
  844         struct ip6aux *ip6a;
  845 
  846         ip6a = ip6_addaux(m);
  847         if (ip6a)
  848                 ip6a->ip6a_dstia6 = ia6;
  849         return ip6a;    /* NULL if failed to set */
  850 }
  851 
  852 struct in6_ifaddr *
  853 ip6_getdstifaddr(m)
  854         struct mbuf *m;
  855 {
  856         struct ip6aux *ip6a;
  857 
  858         ip6a = ip6_findaux(m);
  859         if (ip6a)
  860                 return ip6a->ip6a_dstia6;
  861         else
  862                 return NULL;
  863 }
  864 
  865 /*
  866  * Hop-by-Hop options header processing. If a valid jumbo payload option is
  867  * included, the real payload length will be stored in plenp.
  868  */
  869 static int
  870 ip6_hopopts_input(plenp, rtalertp, mp, offp)
  871         u_int32_t *plenp;
  872         u_int32_t *rtalertp;    /* XXX: should be stored more smart way */
  873         struct mbuf **mp;
  874         int *offp;
  875 {
  876         struct mbuf *m = *mp;
  877         int off = *offp, hbhlen;
  878         struct ip6_hbh *hbh;
  879         u_int8_t *opt;
  880 
  881         /* validation of the length of the header */
  882 #ifndef PULLDOWN_TEST
  883         IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
  884         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
  885         hbhlen = (hbh->ip6h_len + 1) << 3;
  886 
  887         IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
  888         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
  889 #else
  890         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
  891                 sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
  892         if (hbh == NULL) {
  893                 ip6stat.ip6s_tooshort++;
  894                 return -1;
  895         }
  896         hbhlen = (hbh->ip6h_len + 1) << 3;
  897         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  898                 hbhlen);
  899         if (hbh == NULL) {
  900                 ip6stat.ip6s_tooshort++;
  901                 return -1;
  902         }
  903 #endif
  904         off += hbhlen;
  905         hbhlen -= sizeof(struct ip6_hbh);
  906         opt = (u_int8_t *)hbh + sizeof(struct ip6_hbh);
  907 
  908         if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
  909                                 hbhlen, rtalertp, plenp) < 0)
  910                 return (-1);
  911 
  912         *offp = off;
  913         *mp = m;
  914         return (0);
  915 }
  916 
  917 /*
  918  * Search header for all Hop-by-hop options and process each option.
  919  * This function is separate from ip6_hopopts_input() in order to
  920  * handle a case where the sending node itself process its hop-by-hop
  921  * options header. In such a case, the function is called from ip6_output().
  922  *
  923  * The function assumes that hbh header is located right after the IPv6 header
  924  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
  925  * opthead + hbhlen is located in continuous memory region.
  926  */
  927 int
  928 ip6_process_hopopts(m, opthead, hbhlen, rtalertp, plenp)
  929         struct mbuf *m;
  930         u_int8_t *opthead;
  931         int hbhlen;
  932         u_int32_t *rtalertp;
  933         u_int32_t *plenp;
  934 {
  935         struct ip6_hdr *ip6;
  936         int optlen = 0;
  937         u_int8_t *opt = opthead;
  938         u_int16_t rtalert_val;
  939         u_int32_t jumboplen;
  940         const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
  941 
  942         for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
  943                 switch (*opt) {
  944                 case IP6OPT_PAD1:
  945                         optlen = 1;
  946                         break;
  947                 case IP6OPT_PADN:
  948                         if (hbhlen < IP6OPT_MINLEN) {
  949                                 ip6stat.ip6s_toosmall++;
  950                                 goto bad;
  951                         }
  952                         optlen = *(opt + 1) + 2;
  953                         break;
  954                 case IP6OPT_ROUTER_ALERT:
  955                         /* XXX may need check for alignment */
  956                         if (hbhlen < IP6OPT_RTALERT_LEN) {
  957                                 ip6stat.ip6s_toosmall++;
  958                                 goto bad;
  959                         }
  960                         if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
  961                                 /* XXX stat */
  962                                 icmp6_error(m, ICMP6_PARAM_PROB,
  963                                     ICMP6_PARAMPROB_HEADER,
  964                                     erroff + opt + 1 - opthead);
  965                                 return (-1);
  966                         }
  967                         optlen = IP6OPT_RTALERT_LEN;
  968                         bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
  969                         *rtalertp = ntohs(rtalert_val);
  970                         break;
  971                 case IP6OPT_JUMBO:
  972                         /* XXX may need check for alignment */
  973                         if (hbhlen < IP6OPT_JUMBO_LEN) {
  974                                 ip6stat.ip6s_toosmall++;
  975                                 goto bad;
  976                         }
  977                         if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
  978                                 /* XXX stat */
  979                                 icmp6_error(m, ICMP6_PARAM_PROB,
  980                                     ICMP6_PARAMPROB_HEADER,
  981                                     erroff + opt + 1 - opthead);
  982                                 return (-1);
  983                         }
  984                         optlen = IP6OPT_JUMBO_LEN;
  985 
  986                         /*
  987                          * IPv6 packets that have non 0 payload length
  988                          * must not contain a jumbo payload option.
  989                          */
  990                         ip6 = mtod(m, struct ip6_hdr *);
  991                         if (ip6->ip6_plen) {
  992                                 ip6stat.ip6s_badoptions++;
  993                                 icmp6_error(m, ICMP6_PARAM_PROB,
  994                                     ICMP6_PARAMPROB_HEADER,
  995                                     erroff + opt - opthead);
  996                                 return (-1);
  997                         }
  998 
  999                         /*
 1000                          * We may see jumbolen in unaligned location, so
 1001                          * we'd need to perform bcopy().
 1002                          */
 1003                         bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
 1004                         jumboplen = (u_int32_t)htonl(jumboplen);
 1005 
 1006 #if 1
 1007                         /*
 1008                          * if there are multiple jumbo payload options,
 1009                          * *plenp will be non-zero and the packet will be
 1010                          * rejected.
 1011                          * the behavior may need some debate in ipngwg -
 1012                          * multiple options does not make sense, however,
 1013                          * there's no explicit mention in specification.
 1014                          */
 1015                         if (*plenp != 0) {
 1016                                 ip6stat.ip6s_badoptions++;
 1017                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1018                                     ICMP6_PARAMPROB_HEADER,
 1019                                     erroff + opt + 2 - opthead);
 1020                                 return (-1);
 1021                         }
 1022 #endif
 1023 
 1024                         /*
 1025                          * jumbo payload length must be larger than 65535.
 1026                          */
 1027                         if (jumboplen <= IPV6_MAXPACKET) {
 1028                                 ip6stat.ip6s_badoptions++;
 1029                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1030                                     ICMP6_PARAMPROB_HEADER,
 1031                                     erroff + opt + 2 - opthead);
 1032                                 return (-1);
 1033                         }
 1034                         *plenp = jumboplen;
 1035 
 1036                         break;
 1037                 default:                /* unknown option */
 1038                         if (hbhlen < IP6OPT_MINLEN) {
 1039                                 ip6stat.ip6s_toosmall++;
 1040                                 goto bad;
 1041                         }
 1042                         optlen = ip6_unknown_opt(opt, m,
 1043                             erroff + opt - opthead);
 1044                         if (optlen == -1)
 1045                                 return (-1);
 1046                         optlen += 2;
 1047                         break;
 1048                 }
 1049         }
 1050 
 1051         return (0);
 1052 
 1053   bad:
 1054         m_freem(m);
 1055         return (-1);
 1056 }
 1057 
 1058 /*
 1059  * Unknown option processing.
 1060  * The third argument `off' is the offset from the IPv6 header to the option,
 1061  * which is necessary if the IPv6 header the and option header and IPv6 header
 1062  * is not continuous in order to return an ICMPv6 error.
 1063  */
 1064 int
 1065 ip6_unknown_opt(optp, m, off)
 1066         u_int8_t *optp;
 1067         struct mbuf *m;
 1068         int off;
 1069 {
 1070         struct ip6_hdr *ip6;
 1071 
 1072         switch (IP6OPT_TYPE(*optp)) {
 1073         case IP6OPT_TYPE_SKIP: /* ignore the option */
 1074                 return ((int)*(optp + 1));
 1075         case IP6OPT_TYPE_DISCARD:       /* silently discard */
 1076                 m_freem(m);
 1077                 return (-1);
 1078         case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
 1079                 ip6stat.ip6s_badoptions++;
 1080                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
 1081                 return (-1);
 1082         case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
 1083                 ip6stat.ip6s_badoptions++;
 1084                 ip6 = mtod(m, struct ip6_hdr *);
 1085                 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
 1086                     (m->m_flags & (M_BCAST|M_MCAST)))
 1087                         m_freem(m);
 1088                 else
 1089                         icmp6_error(m, ICMP6_PARAM_PROB,
 1090                                     ICMP6_PARAMPROB_OPTION, off);
 1091                 return (-1);
 1092         }
 1093 
 1094         m_freem(m);             /* XXX: NOTREACHED */
 1095         return (-1);
 1096 }
 1097 
 1098 /*
 1099  * Create the "control" list for this pcb.
 1100  * The function will not modify mbuf chain at all.
 1101  *
 1102  * with KAME mbuf chain restriction:
 1103  * The routine will be called from upper layer handlers like tcp6_input().
 1104  * Thus the routine assumes that the caller (tcp6_input) have already
 1105  * called IP6_EXTHDR_CHECK() and all the extension headers are located in the
 1106  * very first mbuf on the mbuf chain.
 1107  */
 1108 void
 1109 ip6_savecontrol(in6p, m, mp)
 1110         struct inpcb *in6p;
 1111         struct mbuf *m, **mp;
 1112 {
 1113 #define IS2292(x, y)    ((in6p->in6p_flags & IN6P_RFC2292) ? (x) : (y))
 1114         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1115 
 1116 #ifdef SO_TIMESTAMP
 1117         if ((in6p->in6p_socket->so_options & SO_TIMESTAMP) != 0) {
 1118                 struct timeval tv;
 1119 
 1120                 microtime(&tv);
 1121                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
 1122                     SCM_TIMESTAMP, SOL_SOCKET);
 1123                 if (*mp)
 1124                         mp = &(*mp)->m_next;
 1125         }
 1126 #endif
 1127 
 1128         if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION)
 1129                 return;
 1130 
 1131         /* RFC 2292 sec. 5 */
 1132         if ((in6p->in6p_flags & IN6P_PKTINFO) != 0) {
 1133                 struct in6_pktinfo pi6;
 1134 
 1135                 bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
 1136                 in6_clearscope(&pi6.ipi6_addr); /* XXX */
 1137                 pi6.ipi6_ifindex =
 1138                     (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
 1139 
 1140                 *mp = sbcreatecontrol((caddr_t) &pi6,
 1141                     sizeof(struct in6_pktinfo),
 1142                     IS2292(IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6);
 1143                 if (*mp)
 1144                         mp = &(*mp)->m_next;
 1145         }
 1146 
 1147         if ((in6p->in6p_flags & IN6P_HOPLIMIT) != 0) {
 1148                 int hlim = ip6->ip6_hlim & 0xff;
 1149 
 1150                 *mp = sbcreatecontrol((caddr_t) &hlim, sizeof(int),
 1151                     IS2292(IPV6_2292HOPLIMIT, IPV6_HOPLIMIT), IPPROTO_IPV6);
 1152                 if (*mp)
 1153                         mp = &(*mp)->m_next;
 1154         }
 1155 
 1156         if ((in6p->in6p_flags & IN6P_TCLASS) != 0) {
 1157                 u_int32_t flowinfo;
 1158                 int tclass;
 1159 
 1160                 flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
 1161                 flowinfo >>= 20;
 1162 
 1163                 tclass = flowinfo & 0xff;
 1164                 *mp = sbcreatecontrol((caddr_t) &tclass, sizeof(tclass),
 1165                     IPV6_TCLASS, IPPROTO_IPV6);
 1166                 if (*mp)
 1167                         mp = &(*mp)->m_next;
 1168         }
 1169 
 1170         /*
 1171          * IPV6_HOPOPTS socket option.  Recall that we required super-user
 1172          * privilege for the option (see ip6_ctloutput), but it might be too
 1173          * strict, since there might be some hop-by-hop options which can be
 1174          * returned to normal user.
 1175          * See also RFC 2292 section 6 (or RFC 3542 section 8).
 1176          */
 1177         if ((in6p->in6p_flags & IN6P_HOPOPTS) != 0) {
 1178                 /*
 1179                  * Check if a hop-by-hop options header is contatined in the
 1180                  * received packet, and if so, store the options as ancillary
 1181                  * data. Note that a hop-by-hop options header must be
 1182                  * just after the IPv6 header, which is assured through the
 1183                  * IPv6 input processing.
 1184                  */
 1185                 if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
 1186                         struct ip6_hbh *hbh;
 1187                         int hbhlen = 0;
 1188 #ifdef PULLDOWN_TEST
 1189                         struct mbuf *ext;
 1190 #endif
 1191 
 1192 #ifndef PULLDOWN_TEST
 1193                         hbh = (struct ip6_hbh *)(ip6 + 1);
 1194                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1195 #else
 1196                         ext = ip6_pullexthdr(m, sizeof(struct ip6_hdr),
 1197                             ip6->ip6_nxt);
 1198                         if (ext == NULL) {
 1199                                 ip6stat.ip6s_tooshort++;
 1200                                 return;
 1201                         }
 1202                         hbh = mtod(ext, struct ip6_hbh *);
 1203                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1204                         if (hbhlen != ext->m_len) {
 1205                                 m_freem(ext);
 1206                                 ip6stat.ip6s_tooshort++;
 1207                                 return;
 1208                         }
 1209 #endif
 1210 
 1211                         /*
 1212                          * XXX: We copy the whole header even if a
 1213                          * jumbo payload option is included, the option which
 1214                          * is to be removed before returning according to
 1215                          * RFC2292.
 1216                          * Note: this constraint is removed in RFC3542
 1217                          */
 1218                         *mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
 1219                             IS2292(IPV6_2292HOPOPTS, IPV6_HOPOPTS),
 1220                             IPPROTO_IPV6);
 1221                         if (*mp)
 1222                                 mp = &(*mp)->m_next;
 1223 #ifdef PULLDOWN_TEST
 1224                         m_freem(ext);
 1225 #endif
 1226                 }
 1227         }
 1228 
 1229         if ((in6p->in6p_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
 1230                 int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
 1231 
 1232                 /*
 1233                  * Search for destination options headers or routing
 1234                  * header(s) through the header chain, and stores each
 1235                  * header as ancillary data.
 1236                  * Note that the order of the headers remains in
 1237                  * the chain of ancillary data.
 1238                  */
 1239                 while (1) {     /* is explicit loop prevention necessary? */
 1240                         struct ip6_ext *ip6e = NULL;
 1241                         int elen;
 1242 #ifdef PULLDOWN_TEST
 1243                         struct mbuf *ext = NULL;
 1244 #endif
 1245 
 1246                         /*
 1247                          * if it is not an extension header, don't try to
 1248                          * pull it from the chain.
 1249                          */
 1250                         switch (nxt) {
 1251                         case IPPROTO_DSTOPTS:
 1252                         case IPPROTO_ROUTING:
 1253                         case IPPROTO_HOPOPTS:
 1254                         case IPPROTO_AH: /* is it possible? */
 1255                                 break;
 1256                         default:
 1257                                 goto loopend;
 1258                         }
 1259 
 1260 #ifndef PULLDOWN_TEST
 1261                         if (off + sizeof(*ip6e) > m->m_len)
 1262                                 goto loopend;
 1263                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
 1264                         if (nxt == IPPROTO_AH)
 1265                                 elen = (ip6e->ip6e_len + 2) << 2;
 1266                         else
 1267                                 elen = (ip6e->ip6e_len + 1) << 3;
 1268                         if (off + elen > m->m_len)
 1269                                 goto loopend;
 1270 #else
 1271                         ext = ip6_pullexthdr(m, off, nxt);
 1272                         if (ext == NULL) {
 1273                                 ip6stat.ip6s_tooshort++;
 1274                                 return;
 1275                         }
 1276                         ip6e = mtod(ext, struct ip6_ext *);
 1277                         if (nxt == IPPROTO_AH)
 1278                                 elen = (ip6e->ip6e_len + 2) << 2;
 1279                         else
 1280                                 elen = (ip6e->ip6e_len + 1) << 3;
 1281                         if (elen != ext->m_len) {
 1282                                 m_freem(ext);
 1283                                 ip6stat.ip6s_tooshort++;
 1284                                 return;
 1285                         }
 1286 #endif
 1287 
 1288                         switch (nxt) {
 1289                         case IPPROTO_DSTOPTS:
 1290                                 if (!(in6p->in6p_flags & IN6P_DSTOPTS))
 1291                                         break;
 1292 
 1293                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1294                                     IS2292(IPV6_2292DSTOPTS, IPV6_DSTOPTS),
 1295                                     IPPROTO_IPV6);
 1296                                 if (*mp)
 1297                                         mp = &(*mp)->m_next;
 1298                                 break;
 1299                         case IPPROTO_ROUTING:
 1300                                 if (!in6p->in6p_flags & IN6P_RTHDR)
 1301                                         break;
 1302 
 1303                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1304                                     IS2292(IPV6_2292RTHDR, IPV6_RTHDR),
 1305                                     IPPROTO_IPV6);
 1306                                 if (*mp)
 1307                                         mp = &(*mp)->m_next;
 1308                                 break;
 1309                         case IPPROTO_HOPOPTS:
 1310                         case IPPROTO_AH: /* is it possible? */
 1311                                 break;
 1312 
 1313                         default:
 1314                                 /*
 1315                                  * other cases have been filtered in the above.
 1316                                  * none will visit this case.  here we supply
 1317                                  * the code just in case (nxt overwritten or
 1318                                  * other cases).
 1319                                  */
 1320 #ifdef PULLDOWN_TEST
 1321                                 m_freem(ext);
 1322 #endif
 1323                                 goto loopend;
 1324 
 1325                         }
 1326 
 1327                         /* proceed with the next header. */
 1328                         off += elen;
 1329                         nxt = ip6e->ip6e_nxt;
 1330                         ip6e = NULL;
 1331 #ifdef PULLDOWN_TEST
 1332                         m_freem(ext);
 1333                         ext = NULL;
 1334 #endif
 1335                 }
 1336           loopend:
 1337                 ;
 1338         }
 1339 
 1340 #undef IS2292
 1341 }
 1342 
 1343 void
 1344 ip6_notify_pmtu(in6p, dst, mtu)
 1345         struct inpcb *in6p;
 1346         struct sockaddr_in6 *dst;
 1347         u_int32_t *mtu;
 1348 {
 1349         struct socket *so;
 1350         struct mbuf *m_mtu;
 1351         struct ip6_mtuinfo mtuctl;
 1352 
 1353         so =  in6p->inp_socket;
 1354 
 1355         if (mtu == NULL)
 1356                 return;
 1357 
 1358 #ifdef DIAGNOSTIC
 1359         if (so == NULL)         /* I believe this is impossible */
 1360                 panic("ip6_notify_pmtu: socket is NULL");
 1361 #endif
 1362 
 1363         bzero(&mtuctl, sizeof(mtuctl)); /* zero-clear for safety */
 1364         mtuctl.ip6m_mtu = *mtu;
 1365         mtuctl.ip6m_addr = *dst;
 1366         in6_recoverscope(&mtuctl.ip6m_addr, &mtuctl.ip6m_addr.sin6_addr, NULL);
 1367 
 1368         if ((m_mtu = sbcreatecontrol((caddr_t)&mtuctl, sizeof(mtuctl),
 1369             IPV6_PATHMTU, IPPROTO_IPV6)) == NULL)
 1370                 return;
 1371 
 1372         if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
 1373             == 0) {
 1374                 m_freem(m_mtu);
 1375                 /* XXX: should count statistics */
 1376         } else
 1377                 sorwakeup(so);
 1378 
 1379         return;
 1380 }
 1381 
 1382 #ifdef PULLDOWN_TEST
 1383 /*
 1384  * pull single extension header from mbuf chain.  returns single mbuf that
 1385  * contains the result, or NULL on error.
 1386  */
 1387 static struct mbuf *
 1388 ip6_pullexthdr(m, off, nxt)
 1389         struct mbuf *m;
 1390         size_t off;
 1391         int nxt;
 1392 {
 1393         struct ip6_ext ip6e;
 1394         size_t elen;
 1395         struct mbuf *n;
 1396 
 1397 #ifdef DIAGNOSTIC
 1398         switch (nxt) {
 1399         case IPPROTO_DSTOPTS:
 1400         case IPPROTO_ROUTING:
 1401         case IPPROTO_HOPOPTS:
 1402         case IPPROTO_AH: /* is it possible? */
 1403                 break;
 1404         default:
 1405                 printf("ip6_pullexthdr: invalid nxt=%d\n", nxt);
 1406         }
 1407 #endif
 1408 
 1409         m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1410         if (nxt == IPPROTO_AH)
 1411                 elen = (ip6e.ip6e_len + 2) << 2;
 1412         else
 1413                 elen = (ip6e.ip6e_len + 1) << 3;
 1414 
 1415         MGET(n, M_DONTWAIT, MT_DATA);
 1416         if (n && elen >= MLEN) {
 1417                 MCLGET(n, M_DONTWAIT);
 1418                 if ((n->m_flags & M_EXT) == 0) {
 1419                         m_free(n);
 1420                         n = NULL;
 1421                 }
 1422         }
 1423         if (!n)
 1424                 return NULL;
 1425 
 1426         n->m_len = 0;
 1427         if (elen >= M_TRAILINGSPACE(n)) {
 1428                 m_free(n);
 1429                 return NULL;
 1430         }
 1431 
 1432         m_copydata(m, off, elen, mtod(n, caddr_t));
 1433         n->m_len = elen;
 1434         return n;
 1435 }
 1436 #endif
 1437 
 1438 /*
 1439  * Get pointer to the previous header followed by the header
 1440  * currently processed.
 1441  * XXX: This function supposes that
 1442  *      M includes all headers,
 1443  *      the next header field and the header length field of each header
 1444  *      are valid, and
 1445  *      the sum of each header length equals to OFF.
 1446  * Because of these assumptions, this function must be called very
 1447  * carefully. Moreover, it will not be used in the near future when
 1448  * we develop `neater' mechanism to process extension headers.
 1449  */
 1450 char *
 1451 ip6_get_prevhdr(m, off)
 1452         struct mbuf *m;
 1453         int off;
 1454 {
 1455         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1456 
 1457         if (off == sizeof(struct ip6_hdr))
 1458                 return (&ip6->ip6_nxt);
 1459         else {
 1460                 int len, nxt;
 1461                 struct ip6_ext *ip6e = NULL;
 1462 
 1463                 nxt = ip6->ip6_nxt;
 1464                 len = sizeof(struct ip6_hdr);
 1465                 while (len < off) {
 1466                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + len);
 1467 
 1468                         switch (nxt) {
 1469                         case IPPROTO_FRAGMENT:
 1470                                 len += sizeof(struct ip6_frag);
 1471                                 break;
 1472                         case IPPROTO_AH:
 1473                                 len += (ip6e->ip6e_len + 2) << 2;
 1474                                 break;
 1475                         default:
 1476                                 len += (ip6e->ip6e_len + 1) << 3;
 1477                                 break;
 1478                         }
 1479                         nxt = ip6e->ip6e_nxt;
 1480                 }
 1481                 if (ip6e)
 1482                         return (&ip6e->ip6e_nxt);
 1483                 else
 1484                         return NULL;
 1485         }
 1486 }
 1487 
 1488 /*
 1489  * get next header offset.  m will be retained.
 1490  */
 1491 int
 1492 ip6_nexthdr(m, off, proto, nxtp)
 1493         struct mbuf *m;
 1494         int off;
 1495         int proto;
 1496         int *nxtp;
 1497 {
 1498         struct ip6_hdr ip6;
 1499         struct ip6_ext ip6e;
 1500         struct ip6_frag fh;
 1501 
 1502         /* just in case */
 1503         if (m == NULL)
 1504                 panic("ip6_nexthdr: m == NULL");
 1505         if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
 1506                 return -1;
 1507 
 1508         switch (proto) {
 1509         case IPPROTO_IPV6:
 1510                 if (m->m_pkthdr.len < off + sizeof(ip6))
 1511                         return -1;
 1512                 m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
 1513                 if (nxtp)
 1514                         *nxtp = ip6.ip6_nxt;
 1515                 off += sizeof(ip6);
 1516                 return off;
 1517 
 1518         case IPPROTO_FRAGMENT:
 1519                 /*
 1520                  * terminate parsing if it is not the first fragment,
 1521                  * it does not make sense to parse through it.
 1522                  */
 1523                 if (m->m_pkthdr.len < off + sizeof(fh))
 1524                         return -1;
 1525                 m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
 1526                 /* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
 1527                 if (fh.ip6f_offlg & IP6F_OFF_MASK)
 1528                         return -1;
 1529                 if (nxtp)
 1530                         *nxtp = fh.ip6f_nxt;
 1531                 off += sizeof(struct ip6_frag);
 1532                 return off;
 1533 
 1534         case IPPROTO_AH:
 1535                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1536                         return -1;
 1537                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1538                 if (nxtp)
 1539                         *nxtp = ip6e.ip6e_nxt;
 1540                 off += (ip6e.ip6e_len + 2) << 2;
 1541                 return off;
 1542 
 1543         case IPPROTO_HOPOPTS:
 1544         case IPPROTO_ROUTING:
 1545         case IPPROTO_DSTOPTS:
 1546                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1547                         return -1;
 1548                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1549                 if (nxtp)
 1550                         *nxtp = ip6e.ip6e_nxt;
 1551                 off += (ip6e.ip6e_len + 1) << 3;
 1552                 return off;
 1553 
 1554         case IPPROTO_NONE:
 1555         case IPPROTO_ESP:
 1556         case IPPROTO_IPCOMP:
 1557                 /* give up */
 1558                 return -1;
 1559 
 1560         default:
 1561                 return -1;
 1562         }
 1563 
 1564         return -1;
 1565 }
 1566 
 1567 /*
 1568  * get offset for the last header in the chain.  m will be kept untainted.
 1569  */
 1570 int
 1571 ip6_lasthdr(m, off, proto, nxtp)
 1572         struct mbuf *m;
 1573         int off;
 1574         int proto;
 1575         int *nxtp;
 1576 {
 1577         int newoff;
 1578         int nxt;
 1579 
 1580         if (!nxtp) {
 1581                 nxt = -1;
 1582                 nxtp = &nxt;
 1583         }
 1584         while (1) {
 1585                 newoff = ip6_nexthdr(m, off, proto, nxtp);
 1586                 if (newoff < 0)
 1587                         return off;
 1588                 else if (newoff < off)
 1589                         return -1;      /* invalid */
 1590                 else if (newoff == off)
 1591                         return newoff;
 1592 
 1593                 off = newoff;
 1594                 proto = *nxtp;
 1595         }
 1596 }
 1597 
 1598 struct ip6aux *
 1599 ip6_addaux(m)
 1600         struct mbuf *m;
 1601 {
 1602         struct m_tag *mtag;
 1603 
 1604         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1605         if (!mtag) {
 1606                 mtag = m_tag_get(PACKET_TAG_IPV6_INPUT, sizeof(struct ip6aux),
 1607                     M_NOWAIT);
 1608                 if (mtag) {
 1609                         m_tag_prepend(m, mtag);
 1610                         bzero(mtag + 1, sizeof(struct ip6aux));
 1611                 }
 1612         }
 1613         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1614 }
 1615 
 1616 struct ip6aux *
 1617 ip6_findaux(m)
 1618         struct mbuf *m;
 1619 {
 1620         struct m_tag *mtag;
 1621 
 1622         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1623         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1624 }
 1625 
 1626 void
 1627 ip6_delaux(m)
 1628         struct mbuf *m;
 1629 {
 1630         struct m_tag *mtag;
 1631 
 1632         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1633         if (mtag)
 1634                 m_tag_delete(m, mtag);
 1635 }
 1636 
 1637 /*
 1638  * System control for IP6
 1639  */
 1640 
 1641 u_char  inet6ctlerrmap[PRC_NCMDS] = {
 1642         0,              0,              0,              0,
 1643         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1644         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1645         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1646         0,              0,              0,              0,
 1647         ENOPROTOOPT
 1648 };

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