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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_input.c

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    1 /*      $FreeBSD: src/sys/netinet6/ip6_input.c,v 1.47 2003/03/12 06:08:48 sam Exp $     */
    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  * 3. All advertising materials mentioning features or use of this software
   46  *    must display the following acknowledgement:
   47  *      This product includes software developed by the University of
   48  *      California, Berkeley and its contributors.
   49  * 4. Neither the name of the University nor the names of its contributors
   50  *    may be used to endorse or promote products derived from this software
   51  *    without specific prior written permission.
   52  *
   53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   63  * SUCH DAMAGE.
   64  *
   65  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
   66  */
   67 
   68 #include "opt_ip6fw.h"
   69 #include "opt_inet.h"
   70 #include "opt_inet6.h"
   71 #include "opt_ipsec.h"
   72 #include "opt_pfil_hooks.h"
   73 
   74 #include <sys/param.h>
   75 #include <sys/systm.h>
   76 #include <sys/malloc.h>
   77 #include <sys/mbuf.h>
   78 #include <sys/proc.h>
   79 #include <sys/domain.h>
   80 #include <sys/protosw.h>
   81 #include <sys/socket.h>
   82 #include <sys/socketvar.h>
   83 #include <sys/errno.h>
   84 #include <sys/time.h>
   85 #include <sys/kernel.h>
   86 #include <sys/syslog.h>
   87 
   88 #include <net/if.h>
   89 #include <net/if_types.h>
   90 #include <net/if_dl.h>
   91 #include <net/route.h>
   92 #include <net/netisr.h>
   93 #ifdef PFIL_HOOKS
   94 #include <net/pfil.h>
   95 #endif
   96 
   97 #include <netinet/in.h>
   98 #include <netinet/in_systm.h>
   99 #ifdef INET
  100 #include <netinet/ip.h>
  101 #include <netinet/ip_icmp.h>
  102 #endif /* INET */
  103 #include <netinet/ip6.h>
  104 #include <netinet6/in6_var.h>
  105 #include <netinet6/ip6_var.h>
  106 #include <netinet/in_pcb.h>
  107 #include <netinet/icmp6.h>
  108 #include <netinet6/in6_ifattach.h>
  109 #include <netinet6/nd6.h>
  110 #include <netinet6/in6_prefix.h>
  111 
  112 #ifdef IPSEC
  113 #include <netinet6/ipsec.h>
  114 #ifdef INET6
  115 #include <netinet6/ipsec6.h>
  116 #endif
  117 #endif
  118 
  119 #ifdef FAST_IPSEC
  120 #include <netipsec/ipsec.h>
  121 #include <netipsec/ipsec6.h>
  122 #define IPSEC
  123 #endif /* FAST_IPSEC */
  124 
  125 #include <netinet6/ip6_fw.h>
  126 
  127 #include <netinet6/ip6protosw.h>
  128 
  129 #include <net/net_osdep.h>
  130 
  131 extern struct domain inet6domain;
  132 
  133 u_char ip6_protox[IPPROTO_MAX];
  134 static struct ifqueue ip6intrq;
  135 static int ip6qmaxlen = IFQ_MAXLEN;
  136 struct in6_ifaddr *in6_ifaddr;
  137 
  138 extern struct callout in6_tmpaddrtimer_ch;
  139 
  140 int ip6_forward_srcrt;                  /* XXX */
  141 int ip6_sourcecheck;                    /* XXX */
  142 int ip6_sourcecheck_interval;           /* XXX */
  143 
  144 int ip6_ours_check_algorithm;
  145 
  146 
  147 /* firewall hooks */
  148 ip6_fw_chk_t *ip6_fw_chk_ptr;
  149 ip6_fw_ctl_t *ip6_fw_ctl_ptr;
  150 int ip6_fw_enable = 1;
  151 
  152 struct ip6stat ip6stat;
  153 
  154 static void ip6_init2 __P((void *));
  155 static struct ip6aux *ip6_setdstifaddr __P((struct mbuf *, struct in6_ifaddr *));
  156 static int ip6_hopopts_input __P((u_int32_t *, u_int32_t *, struct mbuf **, int *));
  157 #ifdef PULLDOWN_TEST
  158 static struct mbuf *ip6_pullexthdr __P((struct mbuf *, size_t, int));
  159 #endif
  160 
  161 
  162 /*
  163  * IP6 initialization: fill in IP6 protocol switch table.
  164  * All protocols not implemented in kernel go to raw IP6 protocol handler.
  165  */
  166 void
  167 ip6_init()
  168 {
  169         struct ip6protosw *pr;
  170         int i;
  171         struct timeval tv;
  172 
  173 #ifdef DIAGNOSTIC
  174         if (sizeof(struct protosw) != sizeof(struct ip6protosw))
  175                 panic("sizeof(protosw) != sizeof(ip6protosw)");
  176 #endif
  177         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  178         if (pr == 0)
  179                 panic("ip6_init");
  180         for (i = 0; i < IPPROTO_MAX; i++)
  181                 ip6_protox[i] = pr - inet6sw;
  182         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  183             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++)
  184                 if (pr->pr_domain->dom_family == PF_INET6 &&
  185                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
  186                         ip6_protox[pr->pr_protocol] = pr - inet6sw;
  187         ip6intrq.ifq_maxlen = ip6qmaxlen;
  188         mtx_init(&ip6intrq.ifq_mtx, "ip6_inq", NULL, MTX_DEF);
  189         netisr_register(NETISR_IPV6, ip6_input, &ip6intrq);
  190         nd6_init();
  191         frag6_init();
  192         /*
  193          * in many cases, random() here does NOT return random number
  194          * as initialization during bootstrap time occur in fixed order.
  195          */
  196         microtime(&tv);
  197         ip6_flow_seq = random() ^ tv.tv_usec;
  198         microtime(&tv);
  199         ip6_desync_factor = (random() ^ tv.tv_usec) % MAX_TEMP_DESYNC_FACTOR;
  200 }
  201 
  202 static void
  203 ip6_init2(dummy)
  204         void *dummy;
  205 {
  206 
  207         /*
  208          * to route local address of p2p link to loopback,
  209          * assign loopback address first.
  210          */
  211         in6_ifattach(&loif[0], NULL);
  212 
  213         /* nd6_timer_init */
  214         callout_init(&nd6_timer_ch, 0);
  215         callout_reset(&nd6_timer_ch, hz, nd6_timer, NULL);
  216 
  217         /* router renumbering prefix list maintenance */
  218         callout_init(&in6_rr_timer_ch, 0);
  219         callout_reset(&in6_rr_timer_ch, hz, in6_rr_timer, NULL);
  220 
  221         /* timer for regeneranation of temporary addresses randomize ID */
  222         callout_reset(&in6_tmpaddrtimer_ch,
  223                       (ip6_temp_preferred_lifetime - ip6_desync_factor -
  224                        ip6_temp_regen_advance) * hz,
  225                       in6_tmpaddrtimer, NULL);
  226 }
  227 
  228 /* cheat */
  229 /* This must be after route_init(), which is now SI_ORDER_THIRD */
  230 SYSINIT(netinet6init2, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ip6_init2, NULL);
  231 
  232 extern struct   route_in6 ip6_forward_rt;
  233 
  234 void
  235 ip6_input(m)
  236         struct mbuf *m;
  237 {
  238         struct ip6_hdr *ip6;
  239         int off = sizeof(struct ip6_hdr), nest;
  240         u_int32_t plen;
  241         u_int32_t rtalert = ~0;
  242         int nxt, ours = 0;
  243         struct ifnet *deliverifp = NULL;
  244 #ifdef  PFIL_HOOKS
  245         struct packet_filter_hook *pfh;
  246         struct mbuf *m0;
  247         int rv;
  248 #endif  /* PFIL_HOOKS */
  249 
  250 #ifdef IPSEC
  251         /*
  252          * should the inner packet be considered authentic?
  253          * see comment in ah4_input().
  254          */
  255         if (m) {
  256                 m->m_flags &= ~M_AUTHIPHDR;
  257                 m->m_flags &= ~M_AUTHIPDGM;
  258         }
  259 #endif
  260 
  261         /*
  262          * make sure we don't have onion peering information into m_aux.
  263          */
  264         ip6_delaux(m);
  265 
  266         /*
  267          * mbuf statistics
  268          */
  269         if (m->m_flags & M_EXT) {
  270                 if (m->m_next)
  271                         ip6stat.ip6s_mext2m++;
  272                 else
  273                         ip6stat.ip6s_mext1++;
  274         } else {
  275 #define M2MMAX  (sizeof(ip6stat.ip6s_m2m)/sizeof(ip6stat.ip6s_m2m[0]))
  276                 if (m->m_next) {
  277                         if (m->m_flags & M_LOOP) {
  278                                 ip6stat.ip6s_m2m[loif[0].if_index]++;   /* XXX */
  279                         } else if (m->m_pkthdr.rcvif->if_index < M2MMAX)
  280                                 ip6stat.ip6s_m2m[m->m_pkthdr.rcvif->if_index]++;
  281                         else
  282                                 ip6stat.ip6s_m2m[0]++;
  283                 } else
  284                         ip6stat.ip6s_m1++;
  285 #undef M2MMAX
  286         }
  287 
  288         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_receive);
  289         ip6stat.ip6s_total++;
  290 
  291 #ifndef PULLDOWN_TEST
  292         /*
  293          * L2 bridge code and some other code can return mbuf chain
  294          * that does not conform to KAME requirement.  too bad.
  295          * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
  296          */
  297         if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
  298                 struct mbuf *n;
  299 
  300                 MGETHDR(n, M_DONTWAIT, MT_HEADER);
  301                 if (n)
  302                         M_MOVE_PKTHDR(n, m);
  303                 if (n && n->m_pkthdr.len > MHLEN) {
  304                         MCLGET(n, M_DONTWAIT);
  305                         if ((n->m_flags & M_EXT) == 0) {
  306                                 m_freem(n);
  307                                 n = NULL;
  308                         }
  309                 }
  310                 if (n == NULL) {
  311                         m_freem(m);
  312                         return; /*ENOBUFS*/
  313                 }
  314 
  315                 m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
  316                 n->m_len = n->m_pkthdr.len;
  317                 m_freem(m);
  318                 m = n;
  319         }
  320         IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), /*nothing*/);
  321 #endif
  322 
  323         if (m->m_len < sizeof(struct ip6_hdr)) {
  324                 struct ifnet *inifp;
  325                 inifp = m->m_pkthdr.rcvif;
  326                 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == 0) {
  327                         ip6stat.ip6s_toosmall++;
  328                         in6_ifstat_inc(inifp, ifs6_in_hdrerr);
  329                         return;
  330                 }
  331         }
  332 
  333         ip6 = mtod(m, struct ip6_hdr *);
  334 
  335         if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
  336                 ip6stat.ip6s_badvers++;
  337                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  338                 goto bad;
  339         }
  340 
  341 #ifdef PFIL_HOOKS
  342         /*
  343          * Run through list of hooks for input packets.  If there are any
  344          * filters which require that additional packets in the flow are
  345          * not fast-forwarded, they must clear the M_CANFASTFWD flag.
  346          * Note that filters must _never_ set this flag, as another filter
  347          * in the list may have previously cleared it.
  348          */
  349         m0 = m;
  350         pfh = pfil_hook_get(PFIL_IN, &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh);
  351         for (; pfh; pfh = pfh->pfil_link.tqe_next)
  352                 if (pfh->pfil_func) {
  353                         rv = pfh->pfil_func(ip6, sizeof(*ip6),
  354                                             m->m_pkthdr.rcvif, 0, &m0);
  355                         if (rv)
  356                                 return;
  357                         m = m0;
  358                         if (m == NULL)
  359                                 return;
  360                         ip6 = mtod(m, struct ip6_hdr *);
  361                 }
  362 #endif /* PFIL_HOOKS */
  363 
  364         ip6stat.ip6s_nxthist[ip6->ip6_nxt]++;
  365 
  366         /*
  367          * Check with the firewall...
  368          */
  369         if (ip6_fw_enable && ip6_fw_chk_ptr) {
  370                 u_short port = 0;
  371                 /* If ipfw says divert, we have to just drop packet */
  372                 /* use port as a dummy argument */
  373                 if ((*ip6_fw_chk_ptr)(&ip6, NULL, &port, &m)) {
  374                         m_freem(m);
  375                         m = NULL;
  376                 }
  377                 if (!m)
  378                         return;
  379         }
  380 
  381         /*
  382          * Check against address spoofing/corruption.
  383          */
  384         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
  385             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
  386                 /*
  387                  * XXX: "badscope" is not very suitable for a multicast source.
  388                  */
  389                 ip6stat.ip6s_badscope++;
  390                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  391                 goto bad;
  392         }
  393         if ((IN6_IS_ADDR_LOOPBACK(&ip6->ip6_src) ||
  394              IN6_IS_ADDR_LOOPBACK(&ip6->ip6_dst)) &&
  395             (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
  396                 ip6stat.ip6s_badscope++;
  397                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  398                 goto bad;
  399         }
  400 
  401         /*
  402          * The following check is not documented in specs.  A malicious
  403          * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
  404          * and bypass security checks (act as if it was from 127.0.0.1 by using
  405          * IPv6 src ::ffff:127.0.0.1).  Be cautious.
  406          *
  407          * This check chokes if we are in an SIIT cloud.  As none of BSDs
  408          * support IPv4-less kernel compilation, we cannot support SIIT
  409          * environment at all.  So, it makes more sense for us to reject any
  410          * malicious packets for non-SIIT environment, than try to do a
  411          * partical support for SIIT environment.
  412          */
  413         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  414             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  415                 ip6stat.ip6s_badscope++;
  416                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  417                 goto bad;
  418         }
  419 #if 0
  420         /*
  421          * Reject packets with IPv4 compatible addresses (auto tunnel).
  422          *
  423          * The code forbids auto tunnel relay case in RFC1933 (the check is
  424          * stronger than RFC1933).  We may want to re-enable it if mech-xx
  425          * is revised to forbid relaying case.
  426          */
  427         if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
  428             IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
  429                 ip6stat.ip6s_badscope++;
  430                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  431                 goto bad;
  432         }
  433 #endif
  434 
  435         /* drop packets if interface ID portion is already filled */
  436         if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
  437                 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src) &&
  438                     ip6->ip6_src.s6_addr16[1]) {
  439                         ip6stat.ip6s_badscope++;
  440                         goto bad;
  441                 }
  442                 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst) &&
  443                     ip6->ip6_dst.s6_addr16[1]) {
  444                         ip6stat.ip6s_badscope++;
  445                         goto bad;
  446                 }
  447         }
  448 
  449         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
  450                 ip6->ip6_src.s6_addr16[1]
  451                         = htons(m->m_pkthdr.rcvif->if_index);
  452         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
  453                 ip6->ip6_dst.s6_addr16[1]
  454                         = htons(m->m_pkthdr.rcvif->if_index);
  455 
  456 #if 0 /* this case seems to be unnecessary. (jinmei, 20010401) */
  457         /*
  458          * We use rt->rt_ifp to determine if the address is ours or not.
  459          * If rt_ifp is lo0, the address is ours.
  460          * The problem here is, rt->rt_ifp for fe80::%lo0/64 is set to lo0,
  461          * so any address under fe80::%lo0/64 will be mistakenly considered
  462          * local.  The special case is supplied to handle the case properly
  463          * by actually looking at interface addresses
  464          * (using in6ifa_ifpwithaddr).
  465          */
  466         if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) != 0 &&
  467             IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst)) {
  468                 if (!in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, &ip6->ip6_dst)) {
  469                         icmp6_error(m, ICMP6_DST_UNREACH,
  470                             ICMP6_DST_UNREACH_ADDR, 0);
  471                         /* m is already freed */
  472                         return;
  473                 }
  474 
  475                 ours = 1;
  476                 deliverifp = m->m_pkthdr.rcvif;
  477                 goto hbhcheck;
  478         }
  479 #endif
  480 
  481         /*
  482          * Multicast check
  483          */
  484         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  485                 struct  in6_multi *in6m = 0;
  486 
  487                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mcast);
  488                 /*
  489                  * See if we belong to the destination multicast group on the
  490                  * arrival interface.
  491                  */
  492                 IN6_LOOKUP_MULTI(ip6->ip6_dst, m->m_pkthdr.rcvif, in6m);
  493                 if (in6m)
  494                         ours = 1;
  495                 else if (!ip6_mrouter) {
  496                         ip6stat.ip6s_notmember++;
  497                         ip6stat.ip6s_cantforward++;
  498                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  499                         goto bad;
  500                 }
  501                 deliverifp = m->m_pkthdr.rcvif;
  502                 goto hbhcheck;
  503         }
  504 
  505         /*
  506          *  Unicast check
  507          */
  508         switch (ip6_ours_check_algorithm) {
  509         default:
  510                 /*
  511                  * XXX: I intentionally broke our indentation rule here,
  512                  *      since this switch-case is just for measurement and
  513                  *      therefore should soon be removed.
  514                  */
  515         if (ip6_forward_rt.ro_rt != NULL &&
  516             (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) != 0 && 
  517             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  518                                &((struct sockaddr_in6 *)(&ip6_forward_rt.ro_dst))->sin6_addr))
  519                 ip6stat.ip6s_forward_cachehit++;
  520         else {
  521                 struct sockaddr_in6 *dst6;
  522 
  523                 if (ip6_forward_rt.ro_rt) {
  524                         /* route is down or destination is different */
  525                         ip6stat.ip6s_forward_cachemiss++;
  526                         RTFREE(ip6_forward_rt.ro_rt);
  527                         ip6_forward_rt.ro_rt = 0;
  528                 }
  529 
  530                 bzero(&ip6_forward_rt.ro_dst, sizeof(struct sockaddr_in6));
  531                 dst6 = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
  532                 dst6->sin6_len = sizeof(struct sockaddr_in6);
  533                 dst6->sin6_family = AF_INET6;
  534                 dst6->sin6_addr = ip6->ip6_dst;
  535 #ifdef SCOPEDROUTING
  536                 ip6_forward_rt.ro_dst.sin6_scope_id =
  537                         in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_dst);
  538 #endif
  539 
  540                 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
  541         }
  542 
  543 #define rt6_key(r) ((struct sockaddr_in6 *)((r)->rt_nodes->rn_key))
  544 
  545         /*
  546          * Accept the packet if the forwarding interface to the destination
  547          * according to the routing table is the loopback interface,
  548          * unless the associated route has a gateway.
  549          * Note that this approach causes to accept a packet if there is a
  550          * route to the loopback interface for the destination of the packet.
  551          * But we think it's even useful in some situations, e.g. when using
  552          * a special daemon which wants to intercept the packet.
  553          *
  554          * XXX: some OSes automatically make a cloned route for the destination
  555          * of an outgoing packet.  If the outgoing interface of the packet
  556          * is a loopback one, the kernel would consider the packet to be
  557          * accepted, even if we have no such address assinged on the interface.
  558          * We check the cloned flag of the route entry to reject such cases,
  559          * assuming that route entries for our own addresses are not made by
  560          * cloning (it should be true because in6_addloop explicitly installs
  561          * the host route).  However, we might have to do an explicit check
  562          * while it would be less efficient.  Or, should we rather install a
  563          * reject route for such a case?
  564          */
  565         if (ip6_forward_rt.ro_rt &&
  566             (ip6_forward_rt.ro_rt->rt_flags &
  567              (RTF_HOST|RTF_GATEWAY)) == RTF_HOST &&
  568 #ifdef RTF_WASCLONED
  569             !(ip6_forward_rt.ro_rt->rt_flags & RTF_WASCLONED) &&
  570 #endif
  571 #ifdef RTF_CLONED
  572             !(ip6_forward_rt.ro_rt->rt_flags & RTF_CLONED) &&
  573 #endif
  574 #if 0
  575             /*
  576              * The check below is redundant since the comparison of
  577              * the destination and the key of the rtentry has
  578              * already done through looking up the routing table.
  579              */
  580             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  581                                 &rt6_key(ip6_forward_rt.ro_rt)->sin6_addr)
  582 #endif
  583             ip6_forward_rt.ro_rt->rt_ifp->if_type == IFT_LOOP) {
  584                 struct in6_ifaddr *ia6 =
  585                         (struct in6_ifaddr *)ip6_forward_rt.ro_rt->rt_ifa;
  586 
  587                 /*
  588                  * record address information into m_aux.
  589                  */
  590                 (void)ip6_setdstifaddr(m, ia6);
  591 
  592                 /*
  593                  * packets to a tentative, duplicated, or somehow invalid
  594                  * address must not be accepted.
  595                  */
  596                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  597                         /* this address is ready */
  598                         ours = 1;
  599                         deliverifp = ia6->ia_ifp;       /* correct? */
  600                         /* Count the packet in the ip address stats */
  601                         ia6->ia_ifa.if_ipackets++;
  602                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  603                         goto hbhcheck;
  604                 } else {
  605                         /* address is not ready, so discard the packet. */
  606                         nd6log((LOG_INFO,
  607                             "ip6_input: packet to an unready address %s->%s\n",
  608                             ip6_sprintf(&ip6->ip6_src),
  609                             ip6_sprintf(&ip6->ip6_dst)));
  610 
  611                         goto bad;
  612                 }
  613         }
  614         } /* XXX indentation (see above) */
  615 
  616         /*
  617          * FAITH(Firewall Aided Internet Translator)
  618          */
  619         if (ip6_keepfaith) {
  620                 if (ip6_forward_rt.ro_rt && ip6_forward_rt.ro_rt->rt_ifp
  621                  && ip6_forward_rt.ro_rt->rt_ifp->if_type == IFT_FAITH) {
  622                         /* XXX do we need more sanity checks? */
  623                         ours = 1;
  624                         deliverifp = ip6_forward_rt.ro_rt->rt_ifp; /* faith */
  625                         goto hbhcheck;
  626                 }
  627         }
  628 
  629         /*
  630          * Now there is no reason to process the packet if it's not our own
  631          * and we're not a router.
  632          */
  633         if (!ip6_forwarding) {
  634                 ip6stat.ip6s_cantforward++;
  635                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  636                 goto bad;
  637         }
  638 
  639   hbhcheck:
  640         /*
  641          * record address information into m_aux, if we don't have one yet.
  642          * note that we are unable to record it, if the address is not listed
  643          * as our interface address (e.g. multicast addresses, addresses
  644          * within FAITH prefixes and such).
  645          */
  646         if (deliverifp && !ip6_getdstifaddr(m)) {
  647                 struct in6_ifaddr *ia6;
  648 
  649                 ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
  650                 if (ia6) {
  651                         if (!ip6_setdstifaddr(m, ia6)) {
  652                                 /*
  653                                  * XXX maybe we should drop the packet here,
  654                                  * as we could not provide enough information
  655                                  * to the upper layers.
  656                                  */
  657                         }
  658                 }
  659         }
  660 
  661         /*
  662          * Process Hop-by-Hop options header if it's contained.
  663          * m may be modified in ip6_hopopts_input().
  664          * If a JumboPayload option is included, plen will also be modified.
  665          */
  666         plen = (u_int32_t)ntohs(ip6->ip6_plen);
  667         if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
  668                 struct ip6_hbh *hbh;
  669 
  670                 if (ip6_hopopts_input(&plen, &rtalert, &m, &off)) {
  671 #if 0   /*touches NULL pointer*/
  672                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  673 #endif
  674                         return; /* m have already been freed */
  675                 }
  676 
  677                 /* adjust pointer */
  678                 ip6 = mtod(m, struct ip6_hdr *);
  679 
  680                 /*
  681                  * if the payload length field is 0 and the next header field
  682                  * indicates Hop-by-Hop Options header, then a Jumbo Payload
  683                  * option MUST be included.
  684                  */
  685                 if (ip6->ip6_plen == 0 && plen == 0) {
  686                         /*
  687                          * Note that if a valid jumbo payload option is
  688                          * contained, ip6_hoptops_input() must set a valid
  689                          * (non-zero) payload length to the variable plen. 
  690                          */
  691                         ip6stat.ip6s_badoptions++;
  692                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  693                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  694                         icmp6_error(m, ICMP6_PARAM_PROB,
  695                                     ICMP6_PARAMPROB_HEADER,
  696                                     (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
  697                         return;
  698                 }
  699 #ifndef PULLDOWN_TEST
  700                 /* ip6_hopopts_input() ensures that mbuf is contiguous */
  701                 hbh = (struct ip6_hbh *)(ip6 + 1);
  702 #else
  703                 IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  704                         sizeof(struct ip6_hbh));
  705                 if (hbh == NULL) {
  706                         ip6stat.ip6s_tooshort++;
  707                         return;
  708                 }
  709 #endif
  710                 nxt = hbh->ip6h_nxt;
  711 
  712                 /*
  713                  * accept the packet if a router alert option is included
  714                  * and we act as an IPv6 router.
  715                  */
  716                 if (rtalert != ~0 && ip6_forwarding)
  717                         ours = 1;
  718         } else
  719                 nxt = ip6->ip6_nxt;
  720 
  721         /*
  722          * Check that the amount of data in the buffers
  723          * is as at least much as the IPv6 header would have us expect.
  724          * Trim mbufs if longer than we expect.
  725          * Drop packet if shorter than we expect.
  726          */
  727         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
  728                 ip6stat.ip6s_tooshort++;
  729                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  730                 goto bad;
  731         }
  732         if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
  733                 if (m->m_len == m->m_pkthdr.len) {
  734                         m->m_len = sizeof(struct ip6_hdr) + plen;
  735                         m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
  736                 } else
  737                         m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
  738         }
  739 
  740         /*
  741          * Forward if desirable.
  742          */
  743         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  744                 /*
  745                  * If we are acting as a multicast router, all
  746                  * incoming multicast packets are passed to the
  747                  * kernel-level multicast forwarding function.
  748                  * The packet is returned (relatively) intact; if
  749                  * ip6_mforward() returns a non-zero value, the packet
  750                  * must be discarded, else it may be accepted below.
  751                  */
  752                 if (ip6_mrouter && ip6_mforward(ip6, m->m_pkthdr.rcvif, m)) {
  753                         ip6stat.ip6s_cantforward++;
  754                         m_freem(m);
  755                         return;
  756                 }
  757                 if (!ours) {
  758                         m_freem(m);
  759                         return;
  760                 }
  761         } else if (!ours) {
  762                 ip6_forward(m, 0);
  763                 return;
  764         }       
  765 
  766         ip6 = mtod(m, struct ip6_hdr *);
  767 
  768         /*
  769          * Malicious party may be able to use IPv4 mapped addr to confuse
  770          * tcp/udp stack and bypass security checks (act as if it was from
  771          * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
  772          *
  773          * For SIIT end node behavior, you may want to disable the check.
  774          * However, you will  become vulnerable to attacks using IPv4 mapped
  775          * source.
  776          */
  777         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  778             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  779                 ip6stat.ip6s_badscope++;
  780                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  781                 goto bad;
  782         }
  783 
  784         /*
  785          * Tell launch routine the next header
  786          */
  787         ip6stat.ip6s_delivered++;
  788         in6_ifstat_inc(deliverifp, ifs6_in_deliver);
  789         nest = 0;
  790 
  791         while (nxt != IPPROTO_DONE) {
  792                 if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
  793                         ip6stat.ip6s_toomanyhdr++;
  794                         goto bad;
  795                 }
  796 
  797                 /*
  798                  * protection against faulty packet - there should be
  799                  * more sanity checks in header chain processing.
  800                  */
  801                 if (m->m_pkthdr.len < off) {
  802                         ip6stat.ip6s_tooshort++;
  803                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  804                         goto bad;
  805                 }
  806 
  807 #if 0
  808                 /*
  809                  * do we need to do it for every header?  yeah, other
  810                  * functions can play with it (like re-allocate and copy).
  811                  */
  812                 mhist = ip6_addaux(m);
  813                 if (mhist && M_TRAILINGSPACE(mhist) >= sizeof(nxt)) {
  814                         hist = mtod(mhist, caddr_t) + mhist->m_len;
  815                         bcopy(&nxt, hist, sizeof(nxt));
  816                         mhist->m_len += sizeof(nxt);
  817                 } else {
  818                         ip6stat.ip6s_toomanyhdr++;
  819                         goto bad;
  820                 }
  821 #endif
  822 
  823 #ifdef IPSEC
  824                 /*
  825                  * enforce IPsec policy checking if we are seeing last header.
  826                  * note that we do not visit this with protocols with pcb layer
  827                  * code - like udp/tcp/raw ip.
  828                  */
  829                 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  830                     ipsec6_in_reject(m, NULL)) {
  831                         ipsec6stat.in_polvio++;
  832                         goto bad;
  833                 }
  834 #endif
  835 
  836                 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
  837         }
  838         return;
  839  bad:
  840         m_freem(m);
  841 }
  842 
  843 /*
  844  * set/grab in6_ifaddr correspond to IPv6 destination address.
  845  * XXX backward compatibility wrapper
  846  */
  847 static struct ip6aux *
  848 ip6_setdstifaddr(m, ia6)
  849         struct mbuf *m;
  850         struct in6_ifaddr *ia6;
  851 {
  852         struct ip6aux *n;
  853 
  854         n = ip6_addaux(m);
  855         if (n)
  856                 n->ip6a_dstia6 = ia6;
  857         return n;       /* NULL if failed to set */
  858 }
  859 
  860 struct in6_ifaddr *
  861 ip6_getdstifaddr(m)
  862         struct mbuf *m;
  863 {
  864         struct ip6aux *n;
  865 
  866         n = ip6_findaux(m);
  867         if (n)
  868                 return n->ip6a_dstia6;
  869         else
  870                 return NULL;
  871 }
  872 
  873 /*
  874  * Hop-by-Hop options header processing. If a valid jumbo payload option is
  875  * included, the real payload length will be stored in plenp.
  876  */
  877 static int
  878 ip6_hopopts_input(plenp, rtalertp, mp, offp)
  879         u_int32_t *plenp;
  880         u_int32_t *rtalertp;    /* XXX: should be stored more smart way */
  881         struct mbuf **mp;
  882         int *offp;
  883 {
  884         struct mbuf *m = *mp;
  885         int off = *offp, hbhlen;
  886         struct ip6_hbh *hbh;
  887         u_int8_t *opt;
  888 
  889         /* validation of the length of the header */
  890 #ifndef PULLDOWN_TEST
  891         IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
  892         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
  893         hbhlen = (hbh->ip6h_len + 1) << 3;
  894 
  895         IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
  896         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
  897 #else
  898         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
  899                 sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
  900         if (hbh == NULL) {
  901                 ip6stat.ip6s_tooshort++;
  902                 return -1;
  903         }
  904         hbhlen = (hbh->ip6h_len + 1) << 3;
  905         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  906                 hbhlen);
  907         if (hbh == NULL) {
  908                 ip6stat.ip6s_tooshort++;
  909                 return -1;
  910         }
  911 #endif
  912         off += hbhlen;
  913         hbhlen -= sizeof(struct ip6_hbh);
  914         opt = (u_int8_t *)hbh + sizeof(struct ip6_hbh);
  915 
  916         if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
  917                                 hbhlen, rtalertp, plenp) < 0)
  918                 return(-1);
  919 
  920         *offp = off;
  921         *mp = m;
  922         return(0);
  923 }
  924 
  925 /*
  926  * Search header for all Hop-by-hop options and process each option.
  927  * This function is separate from ip6_hopopts_input() in order to
  928  * handle a case where the sending node itself process its hop-by-hop
  929  * options header. In such a case, the function is called from ip6_output().
  930  *
  931  * The function assumes that hbh header is located right after the IPv6 header
  932  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
  933  * opthead + hbhlen is located in continuous memory region.
  934  */
  935 int
  936 ip6_process_hopopts(m, opthead, hbhlen, rtalertp, plenp)
  937         struct mbuf *m;
  938         u_int8_t *opthead;
  939         int hbhlen;
  940         u_int32_t *rtalertp;
  941         u_int32_t *plenp;
  942 {
  943         struct ip6_hdr *ip6;
  944         int optlen = 0;
  945         u_int8_t *opt = opthead;
  946         u_int16_t rtalert_val;
  947         u_int32_t jumboplen;
  948         const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
  949 
  950         for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
  951                 switch (*opt) {
  952                 case IP6OPT_PAD1:
  953                         optlen = 1;
  954                         break;
  955                 case IP6OPT_PADN:
  956                         if (hbhlen < IP6OPT_MINLEN) {
  957                                 ip6stat.ip6s_toosmall++;
  958                                 goto bad;
  959                         }
  960                         optlen = *(opt + 1) + 2;
  961                         break;
  962                 case IP6OPT_RTALERT:
  963                         /* XXX may need check for alignment */
  964                         if (hbhlen < IP6OPT_RTALERT_LEN) {
  965                                 ip6stat.ip6s_toosmall++;
  966                                 goto bad;
  967                         }
  968                         if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
  969                                 /* XXX stat */
  970                                 icmp6_error(m, ICMP6_PARAM_PROB,
  971                                             ICMP6_PARAMPROB_HEADER,
  972                                             erroff + opt + 1 - opthead);
  973                                 return(-1);
  974                         }
  975                         optlen = IP6OPT_RTALERT_LEN;
  976                         bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
  977                         *rtalertp = ntohs(rtalert_val);
  978                         break;
  979                 case IP6OPT_JUMBO:
  980                         /* XXX may need check for alignment */
  981                         if (hbhlen < IP6OPT_JUMBO_LEN) {
  982                                 ip6stat.ip6s_toosmall++;
  983                                 goto bad;
  984                         }
  985                         if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
  986                                 /* XXX stat */
  987                                 icmp6_error(m, ICMP6_PARAM_PROB,
  988                                             ICMP6_PARAMPROB_HEADER,
  989                                             erroff + opt + 1 - opthead);
  990                                 return(-1);
  991                         }
  992                         optlen = IP6OPT_JUMBO_LEN;
  993 
  994                         /*
  995                          * IPv6 packets that have non 0 payload length
  996                          * must not contain a jumbo payload option.
  997                          */
  998                         ip6 = mtod(m, struct ip6_hdr *);
  999                         if (ip6->ip6_plen) {
 1000                                 ip6stat.ip6s_badoptions++;
 1001                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1002                                             ICMP6_PARAMPROB_HEADER,
 1003                                             erroff + opt - opthead);
 1004                                 return(-1);
 1005                         }
 1006 
 1007                         /*
 1008                          * We may see jumbolen in unaligned location, so
 1009                          * we'd need to perform bcopy().
 1010                          */
 1011                         bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
 1012                         jumboplen = (u_int32_t)htonl(jumboplen);
 1013 
 1014 #if 1
 1015                         /*
 1016                          * if there are multiple jumbo payload options,
 1017                          * *plenp will be non-zero and the packet will be
 1018                          * rejected.
 1019                          * the behavior may need some debate in ipngwg -
 1020                          * multiple options does not make sense, however,
 1021                          * there's no explicit mention in specification.
 1022                          */
 1023                         if (*plenp != 0) {
 1024                                 ip6stat.ip6s_badoptions++;
 1025                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1026                                             ICMP6_PARAMPROB_HEADER,
 1027                                             erroff + opt + 2 - opthead);
 1028                                 return(-1);
 1029                         }
 1030 #endif
 1031 
 1032                         /*
 1033                          * jumbo payload length must be larger than 65535.
 1034                          */
 1035                         if (jumboplen <= IPV6_MAXPACKET) {
 1036                                 ip6stat.ip6s_badoptions++;
 1037                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1038                                             ICMP6_PARAMPROB_HEADER,
 1039                                             erroff + opt + 2 - opthead);
 1040                                 return(-1);
 1041                         }
 1042                         *plenp = jumboplen;
 1043 
 1044                         break;
 1045                 default:                /* unknown option */
 1046                         if (hbhlen < IP6OPT_MINLEN) {
 1047                                 ip6stat.ip6s_toosmall++;
 1048                                 goto bad;
 1049                         }
 1050                         optlen = ip6_unknown_opt(opt, m,
 1051                             erroff + opt - opthead);
 1052                         if (optlen == -1)
 1053                                 return(-1);
 1054                         optlen += 2;
 1055                         break;
 1056                 }
 1057         }
 1058 
 1059         return(0);
 1060 
 1061   bad:
 1062         m_freem(m);
 1063         return(-1);
 1064 }
 1065 
 1066 /*
 1067  * Unknown option processing.
 1068  * The third argument `off' is the offset from the IPv6 header to the option,
 1069  * which is necessary if the IPv6 header the and option header and IPv6 header
 1070  * is not continuous in order to return an ICMPv6 error.
 1071  */
 1072 int
 1073 ip6_unknown_opt(optp, m, off)
 1074         u_int8_t *optp;
 1075         struct mbuf *m;
 1076         int off;
 1077 {
 1078         struct ip6_hdr *ip6;
 1079 
 1080         switch (IP6OPT_TYPE(*optp)) {
 1081         case IP6OPT_TYPE_SKIP: /* ignore the option */
 1082                 return((int)*(optp + 1));
 1083         case IP6OPT_TYPE_DISCARD:       /* silently discard */
 1084                 m_freem(m);
 1085                 return(-1);
 1086         case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
 1087                 ip6stat.ip6s_badoptions++;
 1088                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
 1089                 return(-1);
 1090         case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
 1091                 ip6stat.ip6s_badoptions++;
 1092                 ip6 = mtod(m, struct ip6_hdr *);
 1093                 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
 1094                     (m->m_flags & (M_BCAST|M_MCAST)))
 1095                         m_freem(m);
 1096                 else
 1097                         icmp6_error(m, ICMP6_PARAM_PROB,
 1098                                     ICMP6_PARAMPROB_OPTION, off);
 1099                 return(-1);
 1100         }
 1101 
 1102         m_freem(m);             /* XXX: NOTREACHED */
 1103         return(-1);
 1104 }
 1105 
 1106 /*
 1107  * Create the "control" list for this pcb.
 1108  * The function will not modify mbuf chain at all.
 1109  *
 1110  * with KAME mbuf chain restriction:
 1111  * The routine will be called from upper layer handlers like tcp6_input().
 1112  * Thus the routine assumes that the caller (tcp6_input) have already
 1113  * called IP6_EXTHDR_CHECK() and all the extension headers are located in the
 1114  * very first mbuf on the mbuf chain.
 1115  */
 1116 void
 1117 ip6_savecontrol(in6p, mp, ip6, m)
 1118         struct inpcb *in6p;
 1119         struct mbuf **mp;
 1120         struct ip6_hdr *ip6;
 1121         struct mbuf *m;
 1122 {
 1123 #if __FreeBSD_version >= 500000
 1124         struct thread *td = curthread;  /* XXX */
 1125 #else
 1126         struct proc *td = curproc;      /* XXX */
 1127 #endif
 1128         int privileged = 0;
 1129         int rthdr_exist = 0;
 1130 
 1131 
 1132         if (td && !suser(td))
 1133                 privileged++;
 1134 
 1135 #ifdef SO_TIMESTAMP
 1136         if ((in6p->in6p_socket->so_options & SO_TIMESTAMP) != 0) {
 1137                 struct timeval tv;
 1138 
 1139                 microtime(&tv);
 1140                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
 1141                                       SCM_TIMESTAMP, SOL_SOCKET);
 1142                 if (*mp) {
 1143                         mp = &(*mp)->m_next;
 1144                 }
 1145         }
 1146 #endif
 1147 
 1148         /* RFC 2292 sec. 5 */
 1149         if ((in6p->in6p_flags & IN6P_PKTINFO) != 0) {
 1150                 struct in6_pktinfo pi6;
 1151                 bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
 1152                 if (IN6_IS_SCOPE_LINKLOCAL(&pi6.ipi6_addr))
 1153                         pi6.ipi6_addr.s6_addr16[1] = 0;
 1154                 pi6.ipi6_ifindex = (m && m->m_pkthdr.rcvif)
 1155                                         ? m->m_pkthdr.rcvif->if_index
 1156                                         : 0;
 1157                 *mp = sbcreatecontrol((caddr_t) &pi6,
 1158                         sizeof(struct in6_pktinfo), IPV6_PKTINFO,
 1159                         IPPROTO_IPV6);
 1160                 if (*mp)
 1161                         mp = &(*mp)->m_next;
 1162         }
 1163 
 1164         if ((in6p->in6p_flags & IN6P_HOPLIMIT) != 0) {
 1165                 int hlim = ip6->ip6_hlim & 0xff;
 1166                 *mp = sbcreatecontrol((caddr_t) &hlim,
 1167                         sizeof(int), IPV6_HOPLIMIT, IPPROTO_IPV6);
 1168                 if (*mp)
 1169                         mp = &(*mp)->m_next;
 1170         }
 1171 
 1172         /*
 1173          * IPV6_HOPOPTS socket option. We require super-user privilege
 1174          * for the option, but it might be too strict, since there might
 1175          * be some hop-by-hop options which can be returned to normal user.
 1176          * See RFC 2292 section 6.
 1177          */
 1178         if ((in6p->in6p_flags & IN6P_HOPOPTS) != 0 && privileged) {
 1179                 /*
 1180                  * Check if a hop-by-hop options header is contatined in the
 1181                  * received packet, and if so, store the options as ancillary
 1182                  * data. Note that a hop-by-hop options header must be
 1183                  * just after the IPv6 header, which fact is assured through
 1184                  * the IPv6 input processing.
 1185                  */
 1186                 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1187                 if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
 1188                         struct ip6_hbh *hbh;
 1189                         int hbhlen = 0;
 1190 #ifdef PULLDOWN_TEST
 1191                         struct mbuf *ext;
 1192 #endif
 1193 
 1194 #ifndef PULLDOWN_TEST
 1195                         hbh = (struct ip6_hbh *)(ip6 + 1);
 1196                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1197 #else
 1198                         ext = ip6_pullexthdr(m, sizeof(struct ip6_hdr),
 1199                             ip6->ip6_nxt);
 1200                         if (ext == NULL) {
 1201                                 ip6stat.ip6s_tooshort++;
 1202                                 return;
 1203                         }
 1204                         hbh = mtod(ext, struct ip6_hbh *);
 1205                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1206                         if (hbhlen != ext->m_len) {
 1207                                 m_freem(ext);
 1208                                 ip6stat.ip6s_tooshort++;
 1209                                 return;
 1210                         }
 1211 #endif
 1212 
 1213                         /*
 1214                          * XXX: We copy whole the header even if a jumbo
 1215                          * payload option is included, which option is to
 1216                          * be removed before returning in the RFC 2292.
 1217                          * Note: this constraint is removed in 2292bis.
 1218                          */
 1219                         *mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
 1220                                               IPV6_HOPOPTS, IPPROTO_IPV6);
 1221                         if (*mp)
 1222                                 mp = &(*mp)->m_next;
 1223 #ifdef PULLDOWN_TEST
 1224                         m_freem(ext);
 1225 #endif
 1226                 }
 1227         }
 1228 
 1229         /* IPV6_DSTOPTS and IPV6_RTHDR socket options */
 1230         if ((in6p->in6p_flags & (IN6P_DSTOPTS | IN6P_RTHDRDSTOPTS)) != 0) {
 1231                 int proto, off, nxt;
 1232 
 1233                 /*
 1234                  * go through the header chain to see if a routing header is
 1235                  * contained in the packet. We need this information to store
 1236                  * destination options headers (if any) properly.
 1237                  * XXX: performance issue. We should record this info when
 1238                  * processing extension headers in incoming routine.
 1239                  * (todo) use m_aux? 
 1240                  */
 1241                 proto = IPPROTO_IPV6;
 1242                 off = 0;
 1243                 nxt = -1;
 1244                 while (1) {
 1245                         int newoff;
 1246 
 1247                         newoff = ip6_nexthdr(m, off, proto, &nxt);
 1248                         if (newoff < 0)
 1249                                 break;
 1250                         if (newoff < off) /* invalid, check for safety */
 1251                                 break;
 1252                         if ((proto = nxt) == IPPROTO_ROUTING) {
 1253                                 rthdr_exist = 1;
 1254                                 break;
 1255                         }
 1256                         off = newoff;
 1257                 }
 1258         }
 1259 
 1260         if ((in6p->in6p_flags &
 1261              (IN6P_RTHDR | IN6P_DSTOPTS | IN6P_RTHDRDSTOPTS)) != 0) {
 1262                 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1263                 int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
 1264 
 1265                 /*
 1266                  * Search for destination options headers or routing
 1267                  * header(s) through the header chain, and stores each
 1268                  * header as ancillary data.
 1269                  * Note that the order of the headers remains in
 1270                  * the chain of ancillary data.
 1271                  */
 1272                 while (1) {     /* is explicit loop prevention necessary? */
 1273                         struct ip6_ext *ip6e = NULL;
 1274                         int elen;
 1275 #ifdef PULLDOWN_TEST
 1276                         struct mbuf *ext = NULL;
 1277 #endif
 1278 
 1279                         /*
 1280                          * if it is not an extension header, don't try to
 1281                          * pull it from the chain.
 1282                          */
 1283                         switch (nxt) {
 1284                         case IPPROTO_DSTOPTS:
 1285                         case IPPROTO_ROUTING:
 1286                         case IPPROTO_HOPOPTS:
 1287                         case IPPROTO_AH: /* is it possible? */
 1288                                 break;
 1289                         default:
 1290                                 goto loopend;
 1291                         }
 1292 
 1293 #ifndef PULLDOWN_TEST
 1294                         if (off + sizeof(*ip6e) > m->m_len)
 1295                                 goto loopend;
 1296                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
 1297                         if (nxt == IPPROTO_AH)
 1298                                 elen = (ip6e->ip6e_len + 2) << 2;
 1299                         else
 1300                                 elen = (ip6e->ip6e_len + 1) << 3;
 1301                         if (off + elen > m->m_len)
 1302                                 goto loopend;
 1303 #else
 1304                         ext = ip6_pullexthdr(m, off, nxt);
 1305                         if (ext == NULL) {
 1306                                 ip6stat.ip6s_tooshort++;
 1307                                 return;
 1308                         }
 1309                         ip6e = mtod(ext, struct ip6_ext *);
 1310                         if (nxt == IPPROTO_AH)
 1311                                 elen = (ip6e->ip6e_len + 2) << 2;
 1312                         else
 1313                                 elen = (ip6e->ip6e_len + 1) << 3;
 1314                         if (elen != ext->m_len) {
 1315                                 m_freem(ext);
 1316                                 ip6stat.ip6s_tooshort++;
 1317                                 return;
 1318                         }
 1319 #endif
 1320 
 1321                         switch (nxt) {
 1322                         case IPPROTO_DSTOPTS:
 1323                                 if ((in6p->in6p_flags & IN6P_DSTOPTS) == 0)
 1324                                         break;
 1325 
 1326                                 /*
 1327                                  * We also require super-user privilege for
 1328                                  * the option.
 1329                                  * See the comments on IN6_HOPOPTS.
 1330                                  */
 1331                                 if (!privileged)
 1332                                         break;
 1333 
 1334                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1335                                                       IPV6_DSTOPTS,
 1336                                                       IPPROTO_IPV6);
 1337                                 if (*mp)
 1338                                         mp = &(*mp)->m_next;
 1339                                 break;
 1340                         case IPPROTO_ROUTING:
 1341                                 if (!in6p->in6p_flags & IN6P_RTHDR)
 1342                                         break;
 1343 
 1344                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1345                                                       IPV6_RTHDR,
 1346                                                       IPPROTO_IPV6);
 1347                                 if (*mp)
 1348                                         mp = &(*mp)->m_next;
 1349                                 break;
 1350                         case IPPROTO_HOPOPTS:
 1351                         case IPPROTO_AH: /* is it possible? */
 1352                                 break;
 1353 
 1354                         default:
 1355                                 /*
 1356                                  * other cases have been filtered in the above.
 1357                                  * none will visit this case.  here we supply
 1358                                  * the code just in case (nxt overwritten or
 1359                                  * other cases).
 1360                                  */
 1361 #ifdef PULLDOWN_TEST
 1362                                 m_freem(ext);
 1363 #endif
 1364                                 goto loopend;
 1365 
 1366                         }
 1367 
 1368                         /* proceed with the next header. */
 1369                         off += elen;
 1370                         nxt = ip6e->ip6e_nxt;
 1371                         ip6e = NULL;
 1372 #ifdef PULLDOWN_TEST
 1373                         m_freem(ext);
 1374                         ext = NULL;
 1375 #endif
 1376                 }
 1377           loopend:
 1378                 ;
 1379         }
 1380 
 1381 }
 1382 
 1383 #ifdef PULLDOWN_TEST
 1384 /*
 1385  * pull single extension header from mbuf chain.  returns single mbuf that
 1386  * contains the result, or NULL on error.
 1387  */
 1388 static struct mbuf *
 1389 ip6_pullexthdr(m, off, nxt)
 1390         struct mbuf *m;
 1391         size_t off;
 1392         int nxt;
 1393 {
 1394         struct ip6_ext ip6e;
 1395         size_t elen;
 1396         struct mbuf *n;
 1397 
 1398 #ifdef DIAGNOSTIC
 1399         switch (nxt) {
 1400         case IPPROTO_DSTOPTS:
 1401         case IPPROTO_ROUTING:
 1402         case IPPROTO_HOPOPTS:
 1403         case IPPROTO_AH: /* is it possible? */
 1404                 break;
 1405         default:
 1406                 printf("ip6_pullexthdr: invalid nxt=%d\n", nxt);
 1407         }
 1408 #endif
 1409 
 1410         m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1411         if (nxt == IPPROTO_AH)
 1412                 elen = (ip6e.ip6e_len + 2) << 2;
 1413         else
 1414                 elen = (ip6e.ip6e_len + 1) << 3;
 1415 
 1416         MGET(n, M_DONTWAIT, MT_DATA);
 1417         if (n && elen >= MLEN) {
 1418                 MCLGET(n, M_DONTWAIT);
 1419                 if ((n->m_flags & M_EXT) == 0) {
 1420                         m_free(n);
 1421                         n = NULL;
 1422                 }
 1423         }
 1424         if (!n)
 1425                 return NULL;
 1426 
 1427         n->m_len = 0;
 1428         if (elen >= M_TRAILINGSPACE(n)) {
 1429                 m_free(n);
 1430                 return NULL;
 1431         }
 1432 
 1433         m_copydata(m, off, elen, mtod(n, caddr_t));
 1434         n->m_len = elen;
 1435         return n;
 1436 }
 1437 #endif
 1438 
 1439 /*
 1440  * Get pointer to the previous header followed by the header
 1441  * currently processed.
 1442  * XXX: This function supposes that
 1443  *      M includes all headers,
 1444  *      the next header field and the header length field of each header
 1445  *      are valid, and
 1446  *      the sum of each header length equals to OFF.
 1447  * Because of these assumptions, this function must be called very
 1448  * carefully. Moreover, it will not be used in the near future when
 1449  * we develop `neater' mechanism to process extension headers.
 1450  */
 1451 char *
 1452 ip6_get_prevhdr(m, off)
 1453         struct mbuf *m;
 1454         int off;
 1455 {
 1456         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1457 
 1458         if (off == sizeof(struct ip6_hdr))
 1459                 return(&ip6->ip6_nxt);
 1460         else {
 1461                 int len, nxt;
 1462                 struct ip6_ext *ip6e = NULL;
 1463 
 1464                 nxt = ip6->ip6_nxt;
 1465                 len = sizeof(struct ip6_hdr);
 1466                 while (len < off) {
 1467                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + len);
 1468 
 1469                         switch (nxt) {
 1470                         case IPPROTO_FRAGMENT:
 1471                                 len += sizeof(struct ip6_frag);
 1472                                 break;
 1473                         case IPPROTO_AH:
 1474                                 len += (ip6e->ip6e_len + 2) << 2;
 1475                                 break;
 1476                         default:
 1477                                 len += (ip6e->ip6e_len + 1) << 3;
 1478                                 break;
 1479                         }
 1480                         nxt = ip6e->ip6e_nxt;
 1481                 }
 1482                 if (ip6e)
 1483                         return(&ip6e->ip6e_nxt);
 1484                 else
 1485                         return NULL;
 1486         }
 1487 }
 1488 
 1489 /*
 1490  * get next header offset.  m will be retained.
 1491  */
 1492 int
 1493 ip6_nexthdr(m, off, proto, nxtp)
 1494         struct mbuf *m;
 1495         int off;
 1496         int proto;
 1497         int *nxtp;
 1498 {
 1499         struct ip6_hdr ip6;
 1500         struct ip6_ext ip6e;
 1501         struct ip6_frag fh;
 1502 
 1503         /* just in case */
 1504         if (m == NULL)
 1505                 panic("ip6_nexthdr: m == NULL");
 1506         if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
 1507                 return -1;
 1508 
 1509         switch (proto) {
 1510         case IPPROTO_IPV6:
 1511                 if (m->m_pkthdr.len < off + sizeof(ip6))
 1512                         return -1;
 1513                 m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
 1514                 if (nxtp)
 1515                         *nxtp = ip6.ip6_nxt;
 1516                 off += sizeof(ip6);
 1517                 return off;
 1518 
 1519         case IPPROTO_FRAGMENT:
 1520                 /*
 1521                  * terminate parsing if it is not the first fragment,
 1522                  * it does not make sense to parse through it.
 1523                  */
 1524                 if (m->m_pkthdr.len < off + sizeof(fh))
 1525                         return -1;
 1526                 m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
 1527                 if ((ntohs(fh.ip6f_offlg) & IP6F_OFF_MASK) != 0)
 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 *tag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1603         if (!tag) {
 1604                 tag = m_tag_get(PACKET_TAG_IPV6_INPUT,
 1605                                 sizeof (struct ip6aux),
 1606                                 M_NOWAIT);
 1607                 if (tag)
 1608                         m_tag_prepend(m, tag);
 1609         }
 1610         if (tag)
 1611                 bzero(tag+1, sizeof (struct ip6aux));
 1612         return tag ? (struct ip6aux*)(tag+1) : NULL;
 1613 }
 1614 
 1615 struct ip6aux *
 1616 ip6_findaux(m)
 1617         struct mbuf *m;
 1618 {
 1619         struct m_tag *tag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1620         return tag ? (struct ip6aux*)(tag+1) : NULL;
 1621 }
 1622 
 1623 void
 1624 ip6_delaux(m)
 1625         struct mbuf *m;
 1626 {
 1627         struct m_tag *tag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1628         if (tag)
 1629                 m_tag_delete(m, tag);
 1630 }
 1631 
 1632 /*
 1633  * System control for IP6
 1634  */
 1635 
 1636 u_char  inet6ctlerrmap[PRC_NCMDS] = {
 1637         0,              0,              0,              0,
 1638         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1639         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1640         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1641         0,              0,              0,              0,
 1642         ENOPROTOOPT
 1643 };

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