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 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
   30  */
   31 
   32 /*-
   33  * Copyright (c) 1982, 1986, 1988, 1993
   34  *      The Regents of the University of California.  All rights reserved.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice, this list of conditions and the following disclaimer.
   41  * 2. Redistributions in binary form must reproduce the above copyright
   42  *    notice, this list of conditions and the following disclaimer in the
   43  *    documentation and/or other materials provided with the distribution.
   44  * 4. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD: releng/10.0/sys/netinet6/ip6_input.c 255523 2013-09-13 18:45:10Z trociny $");
   65 
   66 #include "opt_inet.h"
   67 #include "opt_inet6.h"
   68 #include "opt_ipfw.h"
   69 #include "opt_ipsec.h"
   70 #include "opt_kdtrace.h"
   71 #include "opt_route.h"
   72 
   73 #include <sys/param.h>
   74 #include <sys/systm.h>
   75 #include <sys/malloc.h>
   76 #include <sys/mbuf.h>
   77 #include <sys/proc.h>
   78 #include <sys/domain.h>
   79 #include <sys/protosw.h>
   80 #include <sys/sdt.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 #include <net/pfil.h>
   94 #include <net/vnet.h>
   95 
   96 #include <netinet/in.h>
   97 #include <netinet/in_kdtrace.h>
   98 #include <netinet/ip_var.h>
   99 #include <netinet/in_systm.h>
  100 #include <net/if_llatbl.h>
  101 #ifdef INET
  102 #include <netinet/ip.h>
  103 #include <netinet/ip_icmp.h>
  104 #endif /* INET */
  105 #include <netinet/ip6.h>
  106 #include <netinet6/in6_var.h>
  107 #include <netinet6/ip6_var.h>
  108 #include <netinet/in_pcb.h>
  109 #include <netinet/icmp6.h>
  110 #include <netinet6/scope6_var.h>
  111 #include <netinet6/in6_ifattach.h>
  112 #include <netinet6/nd6.h>
  113 
  114 #ifdef IPSEC
  115 #include <netipsec/ipsec.h>
  116 #include <netinet6/ip6_ipsec.h>
  117 #include <netipsec/ipsec6.h>
  118 #endif /* IPSEC */
  119 
  120 #include <netinet6/ip6protosw.h>
  121 
  122 #ifdef FLOWTABLE
  123 #include <net/flowtable.h>
  124 VNET_DECLARE(int, ip6_output_flowtable_size);
  125 #define V_ip6_output_flowtable_size     VNET(ip6_output_flowtable_size)
  126 #endif
  127 
  128 extern struct domain inet6domain;
  129 
  130 u_char ip6_protox[IPPROTO_MAX];
  131 VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
  132 VNET_DEFINE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
  133 VNET_DEFINE(u_long, in6_ifaddrhmask);
  134 
  135 static struct netisr_handler ip6_nh = {
  136         .nh_name = "ip6",
  137         .nh_handler = ip6_input,
  138         .nh_proto = NETISR_IPV6,
  139         .nh_policy = NETISR_POLICY_FLOW,
  140 };
  141 
  142 VNET_DECLARE(struct callout, in6_tmpaddrtimer_ch);
  143 #define V_in6_tmpaddrtimer_ch           VNET(in6_tmpaddrtimer_ch)
  144 
  145 VNET_DEFINE(struct pfil_head, inet6_pfil_hook);
  146 
  147 VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
  148 VNET_PCPUSTAT_SYSINIT(ip6stat);
  149 #ifdef VIMAGE
  150 VNET_PCPUSTAT_SYSUNINIT(ip6stat);
  151 #endif /* VIMAGE */
  152 
  153 struct rwlock in6_ifaddr_lock;
  154 RW_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
  155 
  156 static void ip6_init2(void *);
  157 static struct ip6aux *ip6_setdstifaddr(struct mbuf *, struct in6_ifaddr *);
  158 static struct ip6aux *ip6_addaux(struct mbuf *);
  159 static struct ip6aux *ip6_findaux(struct mbuf *m);
  160 static void ip6_delaux (struct mbuf *);
  161 static int ip6_hopopts_input(u_int32_t *, u_int32_t *, struct mbuf **, int *);
  162 #ifdef PULLDOWN_TEST
  163 static struct mbuf *ip6_pullexthdr(struct mbuf *, size_t, int);
  164 #endif
  165 
  166 /*
  167  * IP6 initialization: fill in IP6 protocol switch table.
  168  * All protocols not implemented in kernel go to raw IP6 protocol handler.
  169  */
  170 void
  171 ip6_init(void)
  172 {
  173         struct ip6protosw *pr;
  174         int i;
  175 
  176         TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
  177             &V_ip6_auto_linklocal);
  178         TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
  179         TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
  180 
  181         TAILQ_INIT(&V_in6_ifaddrhead);
  182         V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
  183             &V_in6_ifaddrhmask);
  184 
  185         /* Initialize packet filter hooks. */
  186         V_inet6_pfil_hook.ph_type = PFIL_TYPE_AF;
  187         V_inet6_pfil_hook.ph_af = AF_INET6;
  188         if ((i = pfil_head_register(&V_inet6_pfil_hook)) != 0)
  189                 printf("%s: WARNING: unable to register pfil hook, "
  190                         "error %d\n", __func__, i);
  191 
  192         scope6_init();
  193         addrsel_policy_init();
  194         nd6_init();
  195         frag6_init();
  196 
  197 #ifdef FLOWTABLE
  198         if (TUNABLE_INT_FETCH("net.inet6.ip6.output_flowtable_size",
  199                 &V_ip6_output_flowtable_size)) {
  200                 if (V_ip6_output_flowtable_size < 256)
  201                         V_ip6_output_flowtable_size = 256;
  202                 if (!powerof2(V_ip6_output_flowtable_size)) {
  203                         printf("flowtable must be power of 2 size\n");
  204                         V_ip6_output_flowtable_size = 2048;
  205                 }
  206         } else {
  207                 /*
  208                  * round up to the next power of 2
  209                  */
  210                 V_ip6_output_flowtable_size = 1 << fls((1024 + maxusers * 64)-1);
  211         }
  212         V_ip6_ft = flowtable_alloc("ipv6", V_ip6_output_flowtable_size, FL_IPV6|FL_PCPU);
  213 #endif  
  214         
  215         V_ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
  216 
  217         /* Skip global initialization stuff for non-default instances. */
  218         if (!IS_DEFAULT_VNET(curvnet))
  219                 return;
  220 
  221 #ifdef DIAGNOSTIC
  222         if (sizeof(struct protosw) != sizeof(struct ip6protosw))
  223                 panic("sizeof(protosw) != sizeof(ip6protosw)");
  224 #endif
  225         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  226         if (pr == NULL)
  227                 panic("ip6_init");
  228 
  229         /* Initialize the entire ip6_protox[] array to IPPROTO_RAW. */
  230         for (i = 0; i < IPPROTO_MAX; i++)
  231                 ip6_protox[i] = pr - inet6sw;
  232         /*
  233          * Cycle through IP protocols and put them into the appropriate place
  234          * in ip6_protox[].
  235          */
  236         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  237             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++)
  238                 if (pr->pr_domain->dom_family == PF_INET6 &&
  239                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  240                         /* Be careful to only index valid IP protocols. */
  241                         if (pr->pr_protocol < IPPROTO_MAX)
  242                                 ip6_protox[pr->pr_protocol] = pr - inet6sw;
  243                 }
  244 
  245         netisr_register(&ip6_nh);
  246 }
  247 
  248 /*
  249  * The protocol to be inserted into ip6_protox[] must be already registered
  250  * in inet6sw[], either statically or through pf_proto_register().
  251  */
  252 int
  253 ip6proto_register(short ip6proto)
  254 {
  255         struct ip6protosw *pr;
  256 
  257         /* Sanity checks. */
  258         if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
  259                 return (EPROTONOSUPPORT);
  260 
  261         /*
  262          * The protocol slot must not be occupied by another protocol
  263          * already.  An index pointing to IPPROTO_RAW is unused.
  264          */
  265         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  266         if (pr == NULL)
  267                 return (EPFNOSUPPORT);
  268         if (ip6_protox[ip6proto] != pr - inet6sw)       /* IPPROTO_RAW */
  269                 return (EEXIST);
  270 
  271         /*
  272          * Find the protocol position in inet6sw[] and set the index.
  273          */
  274         for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
  275             pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++) {
  276                 if (pr->pr_domain->dom_family == PF_INET6 &&
  277                     pr->pr_protocol && pr->pr_protocol == ip6proto) {
  278                         ip6_protox[pr->pr_protocol] = pr - inet6sw;
  279                         return (0);
  280                 }
  281         }
  282         return (EPROTONOSUPPORT);
  283 }
  284 
  285 int
  286 ip6proto_unregister(short ip6proto)
  287 {
  288         struct ip6protosw *pr;
  289 
  290         /* Sanity checks. */
  291         if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
  292                 return (EPROTONOSUPPORT);
  293 
  294         /* Check if the protocol was indeed registered. */
  295         pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
  296         if (pr == NULL)
  297                 return (EPFNOSUPPORT);
  298         if (ip6_protox[ip6proto] == pr - inet6sw)       /* IPPROTO_RAW */
  299                 return (ENOENT);
  300 
  301         /* Reset the protocol slot to IPPROTO_RAW. */
  302         ip6_protox[ip6proto] = pr - inet6sw;
  303         return (0);
  304 }
  305 
  306 #ifdef VIMAGE
  307 void
  308 ip6_destroy()
  309 {
  310         int i;
  311 
  312         if ((i = pfil_head_unregister(&V_inet6_pfil_hook)) != 0)
  313                 printf("%s: WARNING: unable to unregister pfil hook, "
  314                     "error %d\n", __func__, i);
  315         hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
  316         nd6_destroy();
  317         callout_drain(&V_in6_tmpaddrtimer_ch);
  318 }
  319 #endif
  320 
  321 static int
  322 ip6_init2_vnet(const void *unused __unused)
  323 {
  324 
  325         /* nd6_timer_init */
  326         callout_init(&V_nd6_timer_ch, 0);
  327         callout_reset(&V_nd6_timer_ch, hz, nd6_timer, curvnet);
  328 
  329         /* timer for regeneranation of temporary addresses randomize ID */
  330         callout_init(&V_in6_tmpaddrtimer_ch, 0);
  331         callout_reset(&V_in6_tmpaddrtimer_ch,
  332                       (V_ip6_temp_preferred_lifetime - V_ip6_desync_factor -
  333                        V_ip6_temp_regen_advance) * hz,
  334                       in6_tmpaddrtimer, curvnet);
  335 
  336         return (0);
  337 }
  338 
  339 static void
  340 ip6_init2(void *dummy)
  341 {
  342 
  343         ip6_init2_vnet(NULL);
  344 }
  345 
  346 /* cheat */
  347 /* This must be after route_init(), which is now SI_ORDER_THIRD */
  348 SYSINIT(netinet6init2, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ip6_init2, NULL);
  349 
  350 static int
  351 ip6_input_hbh(struct mbuf *m, uint32_t *plen, uint32_t *rtalert, int *off,
  352     int *nxt, int *ours)
  353 {
  354         struct ip6_hdr *ip6;
  355         struct ip6_hbh *hbh;
  356 
  357         if (ip6_hopopts_input(plen, rtalert, &m, off)) {
  358 #if 0   /*touches NULL pointer*/
  359                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  360 #endif
  361                 goto out;       /* m have already been freed */
  362         }
  363 
  364         /* adjust pointer */
  365         ip6 = mtod(m, struct ip6_hdr *);
  366 
  367         /*
  368          * if the payload length field is 0 and the next header field
  369          * indicates Hop-by-Hop Options header, then a Jumbo Payload
  370          * option MUST be included.
  371          */
  372         if (ip6->ip6_plen == 0 && *plen == 0) {
  373                 /*
  374                  * Note that if a valid jumbo payload option is
  375                  * contained, ip6_hopopts_input() must set a valid
  376                  * (non-zero) payload length to the variable plen.
  377                  */
  378                 IP6STAT_INC(ip6s_badoptions);
  379                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  380                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  381                 icmp6_error(m, ICMP6_PARAM_PROB,
  382                             ICMP6_PARAMPROB_HEADER,
  383                             (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
  384                 goto out;
  385         }
  386 #ifndef PULLDOWN_TEST
  387         /* ip6_hopopts_input() ensures that mbuf is contiguous */
  388         hbh = (struct ip6_hbh *)(ip6 + 1);
  389 #else
  390         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
  391                 sizeof(struct ip6_hbh));
  392         if (hbh == NULL) {
  393                 IP6STAT_INC(ip6s_tooshort);
  394                 goto out;
  395         }
  396 #endif
  397         *nxt = hbh->ip6h_nxt;
  398 
  399         /*
  400          * If we are acting as a router and the packet contains a
  401          * router alert option, see if we know the option value.
  402          * Currently, we only support the option value for MLD, in which
  403          * case we should pass the packet to the multicast routing
  404          * daemon.
  405          */
  406         if (*rtalert != ~0) {
  407                 switch (*rtalert) {
  408                 case IP6OPT_RTALERT_MLD:
  409                         if (V_ip6_forwarding)
  410                                 *ours = 1;
  411                         break;
  412                 default:
  413                         /*
  414                          * RFC2711 requires unrecognized values must be
  415                          * silently ignored.
  416                          */
  417                         break;
  418                 }
  419         }
  420 
  421         return (0);
  422 
  423 out:
  424         return (1);
  425 }
  426 
  427 void
  428 ip6_input(struct mbuf *m)
  429 {
  430         struct ip6_hdr *ip6;
  431         int off = sizeof(struct ip6_hdr), nest;
  432         u_int32_t plen;
  433         u_int32_t rtalert = ~0;
  434         int nxt, ours = 0;
  435         struct ifnet *deliverifp = NULL, *ifp = NULL;
  436         struct in6_addr odst;
  437         struct route_in6 rin6;
  438         int srcrt = 0;
  439         struct llentry *lle = NULL;
  440         struct sockaddr_in6 dst6, *dst;
  441 
  442         bzero(&rin6, sizeof(struct route_in6));
  443 #ifdef IPSEC
  444         /*
  445          * should the inner packet be considered authentic?
  446          * see comment in ah4_input().
  447          * NB: m cannot be NULL when passed to the input routine
  448          */
  449 
  450         m->m_flags &= ~M_AUTHIPHDR;
  451         m->m_flags &= ~M_AUTHIPDGM;
  452 
  453 #endif /* IPSEC */
  454 
  455         /*
  456          * make sure we don't have onion peering information into m_tag.
  457          */
  458         ip6_delaux(m);
  459 
  460         if (m->m_flags & M_FASTFWD_OURS) {
  461                 /*
  462                  * Firewall changed destination to local.
  463                  */
  464                 m->m_flags &= ~M_FASTFWD_OURS;
  465                 ours = 1;
  466                 deliverifp = m->m_pkthdr.rcvif;
  467                 ip6 = mtod(m, struct ip6_hdr *);
  468                 goto hbhcheck;
  469         }
  470 
  471         /*
  472          * mbuf statistics
  473          */
  474         if (m->m_flags & M_EXT) {
  475                 if (m->m_next)
  476                         IP6STAT_INC(ip6s_mext2m);
  477                 else
  478                         IP6STAT_INC(ip6s_mext1);
  479         } else {
  480                 if (m->m_next) {
  481                         if (m->m_flags & M_LOOP) {
  482                                 IP6STAT_INC(ip6s_m2m[V_loif->if_index]);
  483                         } else if (m->m_pkthdr.rcvif->if_index < IP6S_M2MMAX)
  484                                 IP6STAT_INC(
  485                                     ip6s_m2m[m->m_pkthdr.rcvif->if_index]);
  486                         else
  487                                 IP6STAT_INC(ip6s_m2m[0]);
  488                 } else
  489                         IP6STAT_INC(ip6s_m1);
  490         }
  491 
  492         /* drop the packet if IPv6 operation is disabled on the IF */
  493         if ((ND_IFINFO(m->m_pkthdr.rcvif)->flags & ND6_IFF_IFDISABLED)) {
  494                 m_freem(m);
  495                 return;
  496         }
  497 
  498         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_receive);
  499         IP6STAT_INC(ip6s_total);
  500 
  501 #ifndef PULLDOWN_TEST
  502         /*
  503          * L2 bridge code and some other code can return mbuf chain
  504          * that does not conform to KAME requirement.  too bad.
  505          * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
  506          */
  507         if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
  508                 struct mbuf *n;
  509 
  510                 if (m->m_pkthdr.len > MHLEN)
  511                         n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
  512                 else
  513                         n = m_gethdr(M_NOWAIT, MT_DATA);
  514                 if (n == NULL) {
  515                         m_freem(m);
  516                         return; /* ENOBUFS */
  517                 }
  518 
  519                 m_move_pkthdr(n, m);
  520                 m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
  521                 n->m_len = n->m_pkthdr.len;
  522                 m_freem(m);
  523                 m = n;
  524         }
  525         IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), /* nothing */);
  526 #endif
  527 
  528         if (m->m_len < sizeof(struct ip6_hdr)) {
  529                 struct ifnet *inifp;
  530                 inifp = m->m_pkthdr.rcvif;
  531                 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
  532                         IP6STAT_INC(ip6s_toosmall);
  533                         in6_ifstat_inc(inifp, ifs6_in_hdrerr);
  534                         return;
  535                 }
  536         }
  537 
  538         ip6 = mtod(m, struct ip6_hdr *);
  539 
  540         if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
  541                 IP6STAT_INC(ip6s_badvers);
  542                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
  543                 goto bad;
  544         }
  545 
  546         IP6STAT_INC(ip6s_nxthist[ip6->ip6_nxt]);
  547 
  548         IP_PROBE(receive, NULL, NULL, ip6, m->m_pkthdr.rcvif, NULL, ip6);
  549 
  550         /*
  551          * Check against address spoofing/corruption.
  552          */
  553         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
  554             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
  555                 /*
  556                  * XXX: "badscope" is not very suitable for a multicast source.
  557                  */
  558                 IP6STAT_INC(ip6s_badscope);
  559                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  560                 goto bad;
  561         }
  562         if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
  563             !(m->m_flags & M_LOOP)) {
  564                 /*
  565                  * In this case, the packet should come from the loopback
  566                  * interface.  However, we cannot just check the if_flags,
  567                  * because ip6_mloopback() passes the "actual" interface
  568                  * as the outgoing/incoming interface.
  569                  */
  570                 IP6STAT_INC(ip6s_badscope);
  571                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  572                 goto bad;
  573         }
  574 
  575 #ifdef ALTQ
  576         if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
  577                 /* packet is dropped by traffic conditioner */
  578                 return;
  579         }
  580 #endif
  581         /*
  582          * The following check is not documented in specs.  A malicious
  583          * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
  584          * and bypass security checks (act as if it was from 127.0.0.1 by using
  585          * IPv6 src ::ffff:127.0.0.1).  Be cautious.
  586          *
  587          * This check chokes if we are in an SIIT cloud.  As none of BSDs
  588          * support IPv4-less kernel compilation, we cannot support SIIT
  589          * environment at all.  So, it makes more sense for us to reject any
  590          * malicious packets for non-SIIT environment, than try to do a
  591          * partial support for SIIT environment.
  592          */
  593         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  594             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  595                 IP6STAT_INC(ip6s_badscope);
  596                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  597                 goto bad;
  598         }
  599 #if 0
  600         /*
  601          * Reject packets with IPv4 compatible addresses (auto tunnel).
  602          *
  603          * The code forbids auto tunnel relay case in RFC1933 (the check is
  604          * stronger than RFC1933).  We may want to re-enable it if mech-xx
  605          * is revised to forbid relaying case.
  606          */
  607         if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
  608             IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
  609                 IP6STAT_INC(ip6s_badscope);
  610                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  611                 goto bad;
  612         }
  613 #endif
  614 #ifdef IPSEC
  615         /*
  616          * Bypass packet filtering for packets previously handled by IPsec.
  617          */
  618         if (ip6_ipsec_filtertunnel(m))
  619                 goto passin;
  620 #endif /* IPSEC */
  621 
  622         /*
  623          * Run through list of hooks for input packets.
  624          *
  625          * NB: Beware of the destination address changing
  626          *     (e.g. by NAT rewriting).  When this happens,
  627          *     tell ip6_forward to do the right thing.
  628          */
  629         odst = ip6->ip6_dst;
  630 
  631         /* Jump over all PFIL processing if hooks are not active. */
  632         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  633                 goto passin;
  634 
  635         if (pfil_run_hooks(&V_inet6_pfil_hook, &m,
  636             m->m_pkthdr.rcvif, PFIL_IN, NULL))
  637                 return;
  638         if (m == NULL)                  /* consumed by filter */
  639                 return;
  640         ip6 = mtod(m, struct ip6_hdr *);
  641         srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
  642 
  643         if (m->m_flags & M_FASTFWD_OURS) {
  644                 m->m_flags &= ~M_FASTFWD_OURS;
  645                 ours = 1;
  646                 deliverifp = m->m_pkthdr.rcvif;
  647                 goto hbhcheck;
  648         }
  649         if ((m->m_flags & M_IP6_NEXTHOP) &&
  650             m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
  651                 /*
  652                  * Directly ship the packet on.  This allows forwarding
  653                  * packets originally destined to us to some other directly
  654                  * connected host.
  655                  */
  656                 ip6_forward(m, 1);
  657                 goto out;
  658         }
  659 
  660 passin:
  661         /*
  662          * Disambiguate address scope zones (if there is ambiguity).
  663          * We first make sure that the original source or destination address
  664          * is not in our internal form for scoped addresses.  Such addresses
  665          * are not necessarily invalid spec-wise, but we cannot accept them due
  666          * to the usage conflict.
  667          * in6_setscope() then also checks and rejects the cases where src or
  668          * dst are the loopback address and the receiving interface
  669          * is not loopback.
  670          */
  671         if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
  672                 IP6STAT_INC(ip6s_badscope); /* XXX */
  673                 goto bad;
  674         }
  675         if (in6_setscope(&ip6->ip6_src, m->m_pkthdr.rcvif, NULL) ||
  676             in6_setscope(&ip6->ip6_dst, m->m_pkthdr.rcvif, NULL)) {
  677                 IP6STAT_INC(ip6s_badscope);
  678                 goto bad;
  679         }
  680 
  681         /*
  682          * Multicast check. Assume packet is for us to avoid
  683          * prematurely taking locks.
  684          */
  685         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  686                 ours = 1;
  687                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mcast);
  688                 deliverifp = m->m_pkthdr.rcvif;
  689                 goto hbhcheck;
  690         }
  691 
  692         /*
  693          *  Unicast check
  694          */
  695 
  696         bzero(&dst6, sizeof(dst6));
  697         dst6.sin6_family = AF_INET6;
  698         dst6.sin6_len = sizeof(struct sockaddr_in6);
  699         dst6.sin6_addr = ip6->ip6_dst;
  700         ifp = m->m_pkthdr.rcvif;
  701         IF_AFDATA_RLOCK(ifp);
  702         lle = lla_lookup(LLTABLE6(ifp), 0,
  703              (struct sockaddr *)&dst6);
  704         IF_AFDATA_RUNLOCK(ifp);
  705         if ((lle != NULL) && (lle->la_flags & LLE_IFADDR)) {
  706                 struct ifaddr *ifa;
  707                 struct in6_ifaddr *ia6;
  708                 int bad;
  709 
  710                 bad = 1;
  711 #define sa_equal(a1, a2)                                                \
  712         (bcmp((a1), (a2), ((a1))->sin6_len) == 0)
  713                 IF_ADDR_RLOCK(ifp);
  714                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  715                         if (ifa->ifa_addr->sa_family != dst6.sin6_family)
  716                                 continue;
  717                         if (sa_equal(&dst6, ifa->ifa_addr))
  718                                 break;
  719                 }
  720                 KASSERT(ifa != NULL, ("%s: ifa not found for lle %p",
  721                     __func__, lle));
  722 #undef sa_equal
  723 
  724                 ia6 = (struct in6_ifaddr *)ifa;
  725                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  726                         /* Count the packet in the ip address stats */
  727                         ia6->ia_ifa.if_ipackets++;
  728                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  729 
  730                         /*
  731                          * record address information into m_tag.
  732                          */
  733                         (void)ip6_setdstifaddr(m, ia6);
  734 
  735                         bad = 0;
  736                 } else {
  737                         char ip6bufs[INET6_ADDRSTRLEN];
  738                         char ip6bufd[INET6_ADDRSTRLEN];
  739                         /* address is not ready, so discard the packet. */
  740                         nd6log((LOG_INFO,
  741                             "ip6_input: packet to an unready address %s->%s\n",
  742                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  743                             ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
  744                 }
  745                 IF_ADDR_RUNLOCK(ifp);
  746                 LLE_RUNLOCK(lle);
  747                 if (bad)
  748                         goto bad;
  749                 else {
  750                         ours = 1;
  751                         deliverifp = ifp;
  752                         goto hbhcheck;
  753                 }
  754         }
  755         if (lle != NULL)
  756                 LLE_RUNLOCK(lle);
  757 
  758         dst = &rin6.ro_dst;
  759         dst->sin6_len = sizeof(struct sockaddr_in6);
  760         dst->sin6_family = AF_INET6;
  761         dst->sin6_addr = ip6->ip6_dst;
  762         rin6.ro_rt = in6_rtalloc1((struct sockaddr *)dst, 0, 0, M_GETFIB(m));
  763         if (rin6.ro_rt)
  764                 RT_UNLOCK(rin6.ro_rt);
  765 
  766 #define rt6_key(r) ((struct sockaddr_in6 *)((r)->rt_nodes->rn_key))
  767 
  768         /*
  769          * Accept the packet if the forwarding interface to the destination
  770          * according to the routing table is the loopback interface,
  771          * unless the associated route has a gateway.
  772          * Note that this approach causes to accept a packet if there is a
  773          * route to the loopback interface for the destination of the packet.
  774          * But we think it's even useful in some situations, e.g. when using
  775          * a special daemon which wants to intercept the packet.
  776          *
  777          * XXX: some OSes automatically make a cloned route for the destination
  778          * of an outgoing packet.  If the outgoing interface of the packet
  779          * is a loopback one, the kernel would consider the packet to be
  780          * accepted, even if we have no such address assinged on the interface.
  781          * We check the cloned flag of the route entry to reject such cases,
  782          * assuming that route entries for our own addresses are not made by
  783          * cloning (it should be true because in6_addloop explicitly installs
  784          * the host route).  However, we might have to do an explicit check
  785          * while it would be less efficient.  Or, should we rather install a
  786          * reject route for such a case?
  787          */
  788         if (rin6.ro_rt &&
  789             (rin6.ro_rt->rt_flags &
  790              (RTF_HOST|RTF_GATEWAY)) == RTF_HOST &&
  791 #ifdef RTF_WASCLONED
  792             !(rin6.ro_rt->rt_flags & RTF_WASCLONED) &&
  793 #endif
  794 #ifdef RTF_CLONED
  795             !(rin6.ro_rt->rt_flags & RTF_CLONED) &&
  796 #endif
  797 #if 0
  798             /*
  799              * The check below is redundant since the comparison of
  800              * the destination and the key of the rtentry has
  801              * already done through looking up the routing table.
  802              */
  803             IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
  804             &rt6_key(rin6.ro_rt)->sin6_addr)
  805 #endif
  806             rin6.ro_rt->rt_ifp->if_type == IFT_LOOP) {
  807                 int free_ia6 = 0;
  808                 struct in6_ifaddr *ia6;
  809 
  810                 /*
  811                  * found the loopback route to the interface address
  812                  */
  813                 if (rin6.ro_rt->rt_gateway->sa_family == AF_LINK) {
  814                         struct sockaddr_in6 dest6;
  815 
  816                         bzero(&dest6, sizeof(dest6));
  817                         dest6.sin6_family = AF_INET6;
  818                         dest6.sin6_len = sizeof(dest6);
  819                         dest6.sin6_addr = ip6->ip6_dst;
  820                         ia6 = (struct in6_ifaddr *)
  821                             ifa_ifwithaddr((struct sockaddr *)&dest6);
  822                         if (ia6 == NULL)
  823                                 goto bad;
  824                         free_ia6 = 1;
  825                 }
  826                 else
  827                         ia6 = (struct in6_ifaddr *)rin6.ro_rt->rt_ifa;
  828 
  829                 /*
  830                  * record address information into m_tag.
  831                  */
  832                 (void)ip6_setdstifaddr(m, ia6);
  833 
  834                 /*
  835                  * packets to a tentative, duplicated, or somehow invalid
  836                  * address must not be accepted.
  837                  */
  838                 if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
  839                         /* this address is ready */
  840                         ours = 1;
  841                         deliverifp = ia6->ia_ifp;       /* correct? */
  842                         /* Count the packet in the ip address stats */
  843                         ia6->ia_ifa.if_ipackets++;
  844                         ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
  845                         if (ia6 != NULL && free_ia6 != 0)
  846                                 ifa_free(&ia6->ia_ifa);
  847                         goto hbhcheck;
  848                 } else {
  849                         char ip6bufs[INET6_ADDRSTRLEN];
  850                         char ip6bufd[INET6_ADDRSTRLEN];
  851                         /* address is not ready, so discard the packet. */
  852                         nd6log((LOG_INFO,
  853                             "ip6_input: packet to an unready address %s->%s\n",
  854                             ip6_sprintf(ip6bufs, &ip6->ip6_src),
  855                             ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
  856 
  857                         if (ia6 != NULL && free_ia6 != 0)
  858                                 ifa_free(&ia6->ia_ifa);
  859                         goto bad;
  860                 }
  861         }
  862 
  863         /*
  864          * FAITH (Firewall Aided Internet Translator)
  865          */
  866         if (V_ip6_keepfaith) {
  867                 if (rin6.ro_rt && rin6.ro_rt->rt_ifp &&
  868                     rin6.ro_rt->rt_ifp->if_type == IFT_FAITH) {
  869                         /* XXX do we need more sanity checks? */
  870                         ours = 1;
  871                         deliverifp = rin6.ro_rt->rt_ifp; /* faith */
  872                         goto hbhcheck;
  873                 }
  874         }
  875 
  876         /*
  877          * Now there is no reason to process the packet if it's not our own
  878          * and we're not a router.
  879          */
  880         if (!V_ip6_forwarding) {
  881                 IP6STAT_INC(ip6s_cantforward);
  882                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  883                 goto bad;
  884         }
  885 
  886   hbhcheck:
  887         /*
  888          * record address information into m_tag, if we don't have one yet.
  889          * note that we are unable to record it, if the address is not listed
  890          * as our interface address (e.g. multicast addresses, addresses
  891          * within FAITH prefixes and such).
  892          */
  893         if (deliverifp) {
  894                 struct in6_ifaddr *ia6;
  895 
  896                 if ((ia6 = ip6_getdstifaddr(m)) != NULL) {
  897                         ifa_free(&ia6->ia_ifa);
  898                 } else {
  899                         ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
  900                         if (ia6) {
  901                                 if (!ip6_setdstifaddr(m, ia6)) {
  902                                         /*
  903                                          * XXX maybe we should drop the packet here,
  904                                          * as we could not provide enough information
  905                                          * to the upper layers.
  906                                          */
  907                                 }
  908                                 ifa_free(&ia6->ia_ifa);
  909                         }
  910                 }
  911         }
  912 
  913         /*
  914          * Process Hop-by-Hop options header if it's contained.
  915          * m may be modified in ip6_hopopts_input().
  916          * If a JumboPayload option is included, plen will also be modified.
  917          */
  918         plen = (u_int32_t)ntohs(ip6->ip6_plen);
  919         if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
  920                 int error;
  921 
  922                 error = ip6_input_hbh(m, &plen, &rtalert, &off, &nxt, &ours);
  923                 if (error != 0)
  924                         goto out;
  925         } else
  926                 nxt = ip6->ip6_nxt;
  927 
  928         /*
  929          * Check that the amount of data in the buffers
  930          * is as at least much as the IPv6 header would have us expect.
  931          * Trim mbufs if longer than we expect.
  932          * Drop packet if shorter than we expect.
  933          */
  934         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
  935                 IP6STAT_INC(ip6s_tooshort);
  936                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  937                 goto bad;
  938         }
  939         if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
  940                 if (m->m_len == m->m_pkthdr.len) {
  941                         m->m_len = sizeof(struct ip6_hdr) + plen;
  942                         m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
  943                 } else
  944                         m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
  945         }
  946 
  947         /*
  948          * Forward if desirable.
  949          */
  950         if (V_ip6_mrouter &&
  951             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
  952                 /*
  953                  * If we are acting as a multicast router, all
  954                  * incoming multicast packets are passed to the
  955                  * kernel-level multicast forwarding function.
  956                  * The packet is returned (relatively) intact; if
  957                  * ip6_mforward() returns a non-zero value, the packet
  958                  * must be discarded, else it may be accepted below.
  959                  *
  960                  * XXX TODO: Check hlim and multicast scope here to avoid
  961                  * unnecessarily calling into ip6_mforward().
  962                  */
  963                 if (ip6_mforward &&
  964                     ip6_mforward(ip6, m->m_pkthdr.rcvif, m)) {
  965                         IP6STAT_INC(ip6s_cantforward);
  966                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
  967                         goto bad;
  968                 }
  969         } else if (!ours) {
  970                 ip6_forward(m, srcrt);
  971                 goto out;
  972         }
  973 
  974         ip6 = mtod(m, struct ip6_hdr *);
  975 
  976         /*
  977          * Malicious party may be able to use IPv4 mapped addr to confuse
  978          * tcp/udp stack and bypass security checks (act as if it was from
  979          * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
  980          *
  981          * For SIIT end node behavior, you may want to disable the check.
  982          * However, you will  become vulnerable to attacks using IPv4 mapped
  983          * source.
  984          */
  985         if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
  986             IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
  987                 IP6STAT_INC(ip6s_badscope);
  988                 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
  989                 goto bad;
  990         }
  991 
  992         /*
  993          * Tell launch routine the next header
  994          */
  995         IP6STAT_INC(ip6s_delivered);
  996         in6_ifstat_inc(deliverifp, ifs6_in_deliver);
  997         nest = 0;
  998 
  999         while (nxt != IPPROTO_DONE) {
 1000                 if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
 1001                         IP6STAT_INC(ip6s_toomanyhdr);
 1002                         goto bad;
 1003                 }
 1004 
 1005                 /*
 1006                  * protection against faulty packet - there should be
 1007                  * more sanity checks in header chain processing.
 1008                  */
 1009                 if (m->m_pkthdr.len < off) {
 1010                         IP6STAT_INC(ip6s_tooshort);
 1011                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
 1012                         goto bad;
 1013                 }
 1014 
 1015 #ifdef IPSEC
 1016                 /*
 1017                  * enforce IPsec policy checking if we are seeing last header.
 1018                  * note that we do not visit this with protocols with pcb layer
 1019                  * code - like udp/tcp/raw ip.
 1020                  */
 1021                 if (ip6_ipsec_input(m, nxt))
 1022                         goto bad;
 1023 #endif /* IPSEC */
 1024 
 1025                 /*
 1026                  * Use mbuf flags to propagate Router Alert option to
 1027                  * ICMPv6 layer, as hop-by-hop options have been stripped.
 1028                  */
 1029                 if (nxt == IPPROTO_ICMPV6 && rtalert != ~0)
 1030                         m->m_flags |= M_RTALERT_MLD;
 1031 
 1032                 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
 1033         }
 1034         goto out;
 1035 bad:
 1036         m_freem(m);
 1037 out:
 1038         if (rin6.ro_rt)
 1039                 RTFREE(rin6.ro_rt);
 1040 }
 1041 
 1042 /*
 1043  * set/grab in6_ifaddr correspond to IPv6 destination address.
 1044  * XXX backward compatibility wrapper
 1045  *
 1046  * XXXRW: We should bump the refcount on ia6 before sticking it in the m_tag,
 1047  * and then bump it when the tag is copied, and release it when the tag is
 1048  * freed.  Unfortunately, m_tags don't support deep copies (yet), so instead
 1049  * we just bump the ia refcount when we receive it.  This should be fixed.
 1050  */
 1051 static struct ip6aux *
 1052 ip6_setdstifaddr(struct mbuf *m, struct in6_ifaddr *ia6)
 1053 {
 1054         struct ip6aux *ip6a;
 1055 
 1056         ip6a = ip6_addaux(m);
 1057         if (ip6a)
 1058                 ip6a->ip6a_dstia6 = ia6;
 1059         return ip6a;    /* NULL if failed to set */
 1060 }
 1061 
 1062 struct in6_ifaddr *
 1063 ip6_getdstifaddr(struct mbuf *m)
 1064 {
 1065         struct ip6aux *ip6a;
 1066         struct in6_ifaddr *ia;
 1067 
 1068         ip6a = ip6_findaux(m);
 1069         if (ip6a) {
 1070                 ia = ip6a->ip6a_dstia6;
 1071                 ifa_ref(&ia->ia_ifa);
 1072                 return ia;
 1073         } else
 1074                 return NULL;
 1075 }
 1076 
 1077 /*
 1078  * Hop-by-Hop options header processing. If a valid jumbo payload option is
 1079  * included, the real payload length will be stored in plenp.
 1080  *
 1081  * rtalertp - XXX: should be stored more smart way
 1082  */
 1083 static int
 1084 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
 1085     struct mbuf **mp, int *offp)
 1086 {
 1087         struct mbuf *m = *mp;
 1088         int off = *offp, hbhlen;
 1089         struct ip6_hbh *hbh;
 1090         u_int8_t *opt;
 1091 
 1092         /* validation of the length of the header */
 1093 #ifndef PULLDOWN_TEST
 1094         IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
 1095         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
 1096         hbhlen = (hbh->ip6h_len + 1) << 3;
 1097 
 1098         IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
 1099         hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
 1100 #else
 1101         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
 1102                 sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
 1103         if (hbh == NULL) {
 1104                 IP6STAT_INC(ip6s_tooshort);
 1105                 return -1;
 1106         }
 1107         hbhlen = (hbh->ip6h_len + 1) << 3;
 1108         IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
 1109                 hbhlen);
 1110         if (hbh == NULL) {
 1111                 IP6STAT_INC(ip6s_tooshort);
 1112                 return -1;
 1113         }
 1114 #endif
 1115         off += hbhlen;
 1116         hbhlen -= sizeof(struct ip6_hbh);
 1117         opt = (u_int8_t *)hbh + sizeof(struct ip6_hbh);
 1118 
 1119         if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
 1120                                 hbhlen, rtalertp, plenp) < 0)
 1121                 return (-1);
 1122 
 1123         *offp = off;
 1124         *mp = m;
 1125         return (0);
 1126 }
 1127 
 1128 /*
 1129  * Search header for all Hop-by-hop options and process each option.
 1130  * This function is separate from ip6_hopopts_input() in order to
 1131  * handle a case where the sending node itself process its hop-by-hop
 1132  * options header. In such a case, the function is called from ip6_output().
 1133  *
 1134  * The function assumes that hbh header is located right after the IPv6 header
 1135  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
 1136  * opthead + hbhlen is located in contiguous memory region.
 1137  */
 1138 int
 1139 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
 1140     u_int32_t *rtalertp, u_int32_t *plenp)
 1141 {
 1142         struct ip6_hdr *ip6;
 1143         int optlen = 0;
 1144         u_int8_t *opt = opthead;
 1145         u_int16_t rtalert_val;
 1146         u_int32_t jumboplen;
 1147         const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
 1148 
 1149         for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
 1150                 switch (*opt) {
 1151                 case IP6OPT_PAD1:
 1152                         optlen = 1;
 1153                         break;
 1154                 case IP6OPT_PADN:
 1155                         if (hbhlen < IP6OPT_MINLEN) {
 1156                                 IP6STAT_INC(ip6s_toosmall);
 1157                                 goto bad;
 1158                         }
 1159                         optlen = *(opt + 1) + 2;
 1160                         break;
 1161                 case IP6OPT_ROUTER_ALERT:
 1162                         /* XXX may need check for alignment */
 1163                         if (hbhlen < IP6OPT_RTALERT_LEN) {
 1164                                 IP6STAT_INC(ip6s_toosmall);
 1165                                 goto bad;
 1166                         }
 1167                         if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
 1168                                 /* XXX stat */
 1169                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1170                                     ICMP6_PARAMPROB_HEADER,
 1171                                     erroff + opt + 1 - opthead);
 1172                                 return (-1);
 1173                         }
 1174                         optlen = IP6OPT_RTALERT_LEN;
 1175                         bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
 1176                         *rtalertp = ntohs(rtalert_val);
 1177                         break;
 1178                 case IP6OPT_JUMBO:
 1179                         /* XXX may need check for alignment */
 1180                         if (hbhlen < IP6OPT_JUMBO_LEN) {
 1181                                 IP6STAT_INC(ip6s_toosmall);
 1182                                 goto bad;
 1183                         }
 1184                         if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
 1185                                 /* XXX stat */
 1186                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1187                                     ICMP6_PARAMPROB_HEADER,
 1188                                     erroff + opt + 1 - opthead);
 1189                                 return (-1);
 1190                         }
 1191                         optlen = IP6OPT_JUMBO_LEN;
 1192 
 1193                         /*
 1194                          * IPv6 packets that have non 0 payload length
 1195                          * must not contain a jumbo payload option.
 1196                          */
 1197                         ip6 = mtod(m, struct ip6_hdr *);
 1198                         if (ip6->ip6_plen) {
 1199                                 IP6STAT_INC(ip6s_badoptions);
 1200                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1201                                     ICMP6_PARAMPROB_HEADER,
 1202                                     erroff + opt - opthead);
 1203                                 return (-1);
 1204                         }
 1205 
 1206                         /*
 1207                          * We may see jumbolen in unaligned location, so
 1208                          * we'd need to perform bcopy().
 1209                          */
 1210                         bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
 1211                         jumboplen = (u_int32_t)htonl(jumboplen);
 1212 
 1213 #if 1
 1214                         /*
 1215                          * if there are multiple jumbo payload options,
 1216                          * *plenp will be non-zero and the packet will be
 1217                          * rejected.
 1218                          * the behavior may need some debate in ipngwg -
 1219                          * multiple options does not make sense, however,
 1220                          * there's no explicit mention in specification.
 1221                          */
 1222                         if (*plenp != 0) {
 1223                                 IP6STAT_INC(ip6s_badoptions);
 1224                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1225                                     ICMP6_PARAMPROB_HEADER,
 1226                                     erroff + opt + 2 - opthead);
 1227                                 return (-1);
 1228                         }
 1229 #endif
 1230 
 1231                         /*
 1232                          * jumbo payload length must be larger than 65535.
 1233                          */
 1234                         if (jumboplen <= IPV6_MAXPACKET) {
 1235                                 IP6STAT_INC(ip6s_badoptions);
 1236                                 icmp6_error(m, ICMP6_PARAM_PROB,
 1237                                     ICMP6_PARAMPROB_HEADER,
 1238                                     erroff + opt + 2 - opthead);
 1239                                 return (-1);
 1240                         }
 1241                         *plenp = jumboplen;
 1242 
 1243                         break;
 1244                 default:                /* unknown option */
 1245                         if (hbhlen < IP6OPT_MINLEN) {
 1246                                 IP6STAT_INC(ip6s_toosmall);
 1247                                 goto bad;
 1248                         }
 1249                         optlen = ip6_unknown_opt(opt, m,
 1250                             erroff + opt - opthead);
 1251                         if (optlen == -1)
 1252                                 return (-1);
 1253                         optlen += 2;
 1254                         break;
 1255                 }
 1256         }
 1257 
 1258         return (0);
 1259 
 1260   bad:
 1261         m_freem(m);
 1262         return (-1);
 1263 }
 1264 
 1265 /*
 1266  * Unknown option processing.
 1267  * The third argument `off' is the offset from the IPv6 header to the option,
 1268  * which is necessary if the IPv6 header the and option header and IPv6 header
 1269  * is not contiguous in order to return an ICMPv6 error.
 1270  */
 1271 int
 1272 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
 1273 {
 1274         struct ip6_hdr *ip6;
 1275 
 1276         switch (IP6OPT_TYPE(*optp)) {
 1277         case IP6OPT_TYPE_SKIP: /* ignore the option */
 1278                 return ((int)*(optp + 1));
 1279         case IP6OPT_TYPE_DISCARD:       /* silently discard */
 1280                 m_freem(m);
 1281                 return (-1);
 1282         case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
 1283                 IP6STAT_INC(ip6s_badoptions);
 1284                 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
 1285                 return (-1);
 1286         case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
 1287                 IP6STAT_INC(ip6s_badoptions);
 1288                 ip6 = mtod(m, struct ip6_hdr *);
 1289                 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
 1290                     (m->m_flags & (M_BCAST|M_MCAST)))
 1291                         m_freem(m);
 1292                 else
 1293                         icmp6_error(m, ICMP6_PARAM_PROB,
 1294                                     ICMP6_PARAMPROB_OPTION, off);
 1295                 return (-1);
 1296         }
 1297 
 1298         m_freem(m);             /* XXX: NOTREACHED */
 1299         return (-1);
 1300 }
 1301 
 1302 /*
 1303  * Create the "control" list for this pcb.
 1304  * These functions will not modify mbuf chain at all.
 1305  *
 1306  * With KAME mbuf chain restriction:
 1307  * The routine will be called from upper layer handlers like tcp6_input().
 1308  * Thus the routine assumes that the caller (tcp6_input) have already
 1309  * called IP6_EXTHDR_CHECK() and all the extension headers are located in the
 1310  * very first mbuf on the mbuf chain.
 1311  *
 1312  * ip6_savecontrol_v4 will handle those options that are possible to be
 1313  * set on a v4-mapped socket.
 1314  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
 1315  * options and handle the v6-only ones itself.
 1316  */
 1317 struct mbuf **
 1318 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
 1319     int *v4only)
 1320 {
 1321         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1322 
 1323 #ifdef SO_TIMESTAMP
 1324         if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
 1325                 struct timeval tv;
 1326 
 1327                 microtime(&tv);
 1328                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
 1329                     SCM_TIMESTAMP, SOL_SOCKET);
 1330                 if (*mp)
 1331                         mp = &(*mp)->m_next;
 1332         }
 1333 #endif
 1334 
 1335 #define IS2292(inp, x, y)       (((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
 1336         /* RFC 2292 sec. 5 */
 1337         if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
 1338                 struct in6_pktinfo pi6;
 1339 
 1340                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1341 #ifdef INET
 1342                         struct ip *ip;
 1343 
 1344                         ip = mtod(m, struct ip *);
 1345                         pi6.ipi6_addr.s6_addr32[0] = 0;
 1346                         pi6.ipi6_addr.s6_addr32[1] = 0;
 1347                         pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
 1348                         pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
 1349 #else
 1350                         /* We won't hit this code */
 1351                         bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
 1352 #endif
 1353                 } else {        
 1354                         bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
 1355                         in6_clearscope(&pi6.ipi6_addr); /* XXX */
 1356                 }
 1357                 pi6.ipi6_ifindex =
 1358                     (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
 1359 
 1360                 *mp = sbcreatecontrol((caddr_t) &pi6,
 1361                     sizeof(struct in6_pktinfo),
 1362                     IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6);
 1363                 if (*mp)
 1364                         mp = &(*mp)->m_next;
 1365         }
 1366 
 1367         if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
 1368                 int hlim;
 1369 
 1370                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1371 #ifdef INET
 1372                         struct ip *ip;
 1373 
 1374                         ip = mtod(m, struct ip *);
 1375                         hlim = ip->ip_ttl;
 1376 #else
 1377                         /* We won't hit this code */
 1378                         hlim = 0;
 1379 #endif
 1380                 } else {
 1381                         hlim = ip6->ip6_hlim & 0xff;
 1382                 }
 1383                 *mp = sbcreatecontrol((caddr_t) &hlim, sizeof(int),
 1384                     IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
 1385                     IPPROTO_IPV6);
 1386                 if (*mp)
 1387                         mp = &(*mp)->m_next;
 1388         }
 1389 
 1390         if ((inp->inp_flags & IN6P_TCLASS) != 0) {
 1391                 int tclass;
 1392 
 1393                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1394 #ifdef INET
 1395                         struct ip *ip;
 1396 
 1397                         ip = mtod(m, struct ip *);
 1398                         tclass = ip->ip_tos;
 1399 #else
 1400                         /* We won't hit this code */
 1401                         tclass = 0;
 1402 #endif
 1403                 } else {
 1404                         u_int32_t flowinfo;
 1405 
 1406                         flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
 1407                         flowinfo >>= 20;
 1408                         tclass = flowinfo & 0xff;
 1409                 }
 1410                 *mp = sbcreatecontrol((caddr_t) &tclass, sizeof(int),
 1411                     IPV6_TCLASS, IPPROTO_IPV6);
 1412                 if (*mp)
 1413                         mp = &(*mp)->m_next;
 1414         }
 1415 
 1416         if (v4only != NULL) {
 1417                 if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
 1418                         *v4only = 1;
 1419                 } else {
 1420                         *v4only = 0;
 1421                 }
 1422         }
 1423 
 1424         return (mp);
 1425 }
 1426 
 1427 void
 1428 ip6_savecontrol(struct inpcb *in6p, struct mbuf *m, struct mbuf **mp)
 1429 {
 1430         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1431         int v4only = 0;
 1432 
 1433         mp = ip6_savecontrol_v4(in6p, m, mp, &v4only);
 1434         if (v4only)
 1435                 return;
 1436 
 1437         /*
 1438          * IPV6_HOPOPTS socket option.  Recall that we required super-user
 1439          * privilege for the option (see ip6_ctloutput), but it might be too
 1440          * strict, since there might be some hop-by-hop options which can be
 1441          * returned to normal user.
 1442          * See also RFC 2292 section 6 (or RFC 3542 section 8).
 1443          */
 1444         if ((in6p->inp_flags & IN6P_HOPOPTS) != 0) {
 1445                 /*
 1446                  * Check if a hop-by-hop options header is contatined in the
 1447                  * received packet, and if so, store the options as ancillary
 1448                  * data. Note that a hop-by-hop options header must be
 1449                  * just after the IPv6 header, which is assured through the
 1450                  * IPv6 input processing.
 1451                  */
 1452                 if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
 1453                         struct ip6_hbh *hbh;
 1454                         int hbhlen = 0;
 1455 #ifdef PULLDOWN_TEST
 1456                         struct mbuf *ext;
 1457 #endif
 1458 
 1459 #ifndef PULLDOWN_TEST
 1460                         hbh = (struct ip6_hbh *)(ip6 + 1);
 1461                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1462 #else
 1463                         ext = ip6_pullexthdr(m, sizeof(struct ip6_hdr),
 1464                             ip6->ip6_nxt);
 1465                         if (ext == NULL) {
 1466                                 IP6STAT_INC(ip6s_tooshort);
 1467                                 return;
 1468                         }
 1469                         hbh = mtod(ext, struct ip6_hbh *);
 1470                         hbhlen = (hbh->ip6h_len + 1) << 3;
 1471                         if (hbhlen != ext->m_len) {
 1472                                 m_freem(ext);
 1473                                 IP6STAT_INC(ip6s_tooshort);
 1474                                 return;
 1475                         }
 1476 #endif
 1477 
 1478                         /*
 1479                          * XXX: We copy the whole header even if a
 1480                          * jumbo payload option is included, the option which
 1481                          * is to be removed before returning according to
 1482                          * RFC2292.
 1483                          * Note: this constraint is removed in RFC3542
 1484                          */
 1485                         *mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
 1486                             IS2292(in6p, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
 1487                             IPPROTO_IPV6);
 1488                         if (*mp)
 1489                                 mp = &(*mp)->m_next;
 1490 #ifdef PULLDOWN_TEST
 1491                         m_freem(ext);
 1492 #endif
 1493                 }
 1494         }
 1495 
 1496         if ((in6p->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
 1497                 int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
 1498 
 1499                 /*
 1500                  * Search for destination options headers or routing
 1501                  * header(s) through the header chain, and stores each
 1502                  * header as ancillary data.
 1503                  * Note that the order of the headers remains in
 1504                  * the chain of ancillary data.
 1505                  */
 1506                 while (1) {     /* is explicit loop prevention necessary? */
 1507                         struct ip6_ext *ip6e = NULL;
 1508                         int elen;
 1509 #ifdef PULLDOWN_TEST
 1510                         struct mbuf *ext = NULL;
 1511 #endif
 1512 
 1513                         /*
 1514                          * if it is not an extension header, don't try to
 1515                          * pull it from the chain.
 1516                          */
 1517                         switch (nxt) {
 1518                         case IPPROTO_DSTOPTS:
 1519                         case IPPROTO_ROUTING:
 1520                         case IPPROTO_HOPOPTS:
 1521                         case IPPROTO_AH: /* is it possible? */
 1522                                 break;
 1523                         default:
 1524                                 goto loopend;
 1525                         }
 1526 
 1527 #ifndef PULLDOWN_TEST
 1528                         if (off + sizeof(*ip6e) > m->m_len)
 1529                                 goto loopend;
 1530                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
 1531                         if (nxt == IPPROTO_AH)
 1532                                 elen = (ip6e->ip6e_len + 2) << 2;
 1533                         else
 1534                                 elen = (ip6e->ip6e_len + 1) << 3;
 1535                         if (off + elen > m->m_len)
 1536                                 goto loopend;
 1537 #else
 1538                         ext = ip6_pullexthdr(m, off, nxt);
 1539                         if (ext == NULL) {
 1540                                 IP6STAT_INC(ip6s_tooshort);
 1541                                 return;
 1542                         }
 1543                         ip6e = mtod(ext, struct ip6_ext *);
 1544                         if (nxt == IPPROTO_AH)
 1545                                 elen = (ip6e->ip6e_len + 2) << 2;
 1546                         else
 1547                                 elen = (ip6e->ip6e_len + 1) << 3;
 1548                         if (elen != ext->m_len) {
 1549                                 m_freem(ext);
 1550                                 IP6STAT_INC(ip6s_tooshort);
 1551                                 return;
 1552                         }
 1553 #endif
 1554 
 1555                         switch (nxt) {
 1556                         case IPPROTO_DSTOPTS:
 1557                                 if (!(in6p->inp_flags & IN6P_DSTOPTS))
 1558                                         break;
 1559 
 1560                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1561                                     IS2292(in6p,
 1562                                         IPV6_2292DSTOPTS, IPV6_DSTOPTS),
 1563                                     IPPROTO_IPV6);
 1564                                 if (*mp)
 1565                                         mp = &(*mp)->m_next;
 1566                                 break;
 1567                         case IPPROTO_ROUTING:
 1568                                 if (!(in6p->inp_flags & IN6P_RTHDR))
 1569                                         break;
 1570 
 1571                                 *mp = sbcreatecontrol((caddr_t)ip6e, elen,
 1572                                     IS2292(in6p, IPV6_2292RTHDR, IPV6_RTHDR),
 1573                                     IPPROTO_IPV6);
 1574                                 if (*mp)
 1575                                         mp = &(*mp)->m_next;
 1576                                 break;
 1577                         case IPPROTO_HOPOPTS:
 1578                         case IPPROTO_AH: /* is it possible? */
 1579                                 break;
 1580 
 1581                         default:
 1582                                 /*
 1583                                  * other cases have been filtered in the above.
 1584                                  * none will visit this case.  here we supply
 1585                                  * the code just in case (nxt overwritten or
 1586                                  * other cases).
 1587                                  */
 1588 #ifdef PULLDOWN_TEST
 1589                                 m_freem(ext);
 1590 #endif
 1591                                 goto loopend;
 1592 
 1593                         }
 1594 
 1595                         /* proceed with the next header. */
 1596                         off += elen;
 1597                         nxt = ip6e->ip6e_nxt;
 1598                         ip6e = NULL;
 1599 #ifdef PULLDOWN_TEST
 1600                         m_freem(ext);
 1601                         ext = NULL;
 1602 #endif
 1603                 }
 1604           loopend:
 1605                 ;
 1606         }
 1607 }
 1608 #undef IS2292
 1609 
 1610 void
 1611 ip6_notify_pmtu(struct inpcb *in6p, struct sockaddr_in6 *dst, u_int32_t *mtu)
 1612 {
 1613         struct socket *so;
 1614         struct mbuf *m_mtu;
 1615         struct ip6_mtuinfo mtuctl;
 1616 
 1617         so =  in6p->inp_socket;
 1618 
 1619         if (mtu == NULL)
 1620                 return;
 1621 
 1622 #ifdef DIAGNOSTIC
 1623         if (so == NULL)         /* I believe this is impossible */
 1624                 panic("ip6_notify_pmtu: socket is NULL");
 1625 #endif
 1626 
 1627         bzero(&mtuctl, sizeof(mtuctl)); /* zero-clear for safety */
 1628         mtuctl.ip6m_mtu = *mtu;
 1629         mtuctl.ip6m_addr = *dst;
 1630         if (sa6_recoverscope(&mtuctl.ip6m_addr))
 1631                 return;
 1632 
 1633         if ((m_mtu = sbcreatecontrol((caddr_t)&mtuctl, sizeof(mtuctl),
 1634             IPV6_PATHMTU, IPPROTO_IPV6)) == NULL)
 1635                 return;
 1636 
 1637         if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
 1638             == 0) {
 1639                 m_freem(m_mtu);
 1640                 /* XXX: should count statistics */
 1641         } else
 1642                 sorwakeup(so);
 1643 
 1644         return;
 1645 }
 1646 
 1647 #ifdef PULLDOWN_TEST
 1648 /*
 1649  * pull single extension header from mbuf chain.  returns single mbuf that
 1650  * contains the result, or NULL on error.
 1651  */
 1652 static struct mbuf *
 1653 ip6_pullexthdr(struct mbuf *m, size_t off, int nxt)
 1654 {
 1655         struct ip6_ext ip6e;
 1656         size_t elen;
 1657         struct mbuf *n;
 1658 
 1659 #ifdef DIAGNOSTIC
 1660         switch (nxt) {
 1661         case IPPROTO_DSTOPTS:
 1662         case IPPROTO_ROUTING:
 1663         case IPPROTO_HOPOPTS:
 1664         case IPPROTO_AH: /* is it possible? */
 1665                 break;
 1666         default:
 1667                 printf("ip6_pullexthdr: invalid nxt=%d\n", nxt);
 1668         }
 1669 #endif
 1670 
 1671         m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1672         if (nxt == IPPROTO_AH)
 1673                 elen = (ip6e.ip6e_len + 2) << 2;
 1674         else
 1675                 elen = (ip6e.ip6e_len + 1) << 3;
 1676 
 1677         if (elen > MLEN)
 1678                 n = m_getcl(M_NOWAIT, MT_DATA, 0);
 1679         else
 1680                 n = m_get(M_NOWAIT, MT_DATA);
 1681         if (n == NULL)
 1682                 return NULL;
 1683 
 1684         m_copydata(m, off, elen, mtod(n, caddr_t));
 1685         n->m_len = elen;
 1686         return n;
 1687 }
 1688 #endif
 1689 
 1690 /*
 1691  * Get pointer to the previous header followed by the header
 1692  * currently processed.
 1693  * XXX: This function supposes that
 1694  *      M includes all headers,
 1695  *      the next header field and the header length field of each header
 1696  *      are valid, and
 1697  *      the sum of each header length equals to OFF.
 1698  * Because of these assumptions, this function must be called very
 1699  * carefully. Moreover, it will not be used in the near future when
 1700  * we develop `neater' mechanism to process extension headers.
 1701  */
 1702 char *
 1703 ip6_get_prevhdr(struct mbuf *m, int off)
 1704 {
 1705         struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
 1706 
 1707         if (off == sizeof(struct ip6_hdr))
 1708                 return (&ip6->ip6_nxt);
 1709         else {
 1710                 int len, nxt;
 1711                 struct ip6_ext *ip6e = NULL;
 1712 
 1713                 nxt = ip6->ip6_nxt;
 1714                 len = sizeof(struct ip6_hdr);
 1715                 while (len < off) {
 1716                         ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + len);
 1717 
 1718                         switch (nxt) {
 1719                         case IPPROTO_FRAGMENT:
 1720                                 len += sizeof(struct ip6_frag);
 1721                                 break;
 1722                         case IPPROTO_AH:
 1723                                 len += (ip6e->ip6e_len + 2) << 2;
 1724                                 break;
 1725                         default:
 1726                                 len += (ip6e->ip6e_len + 1) << 3;
 1727                                 break;
 1728                         }
 1729                         nxt = ip6e->ip6e_nxt;
 1730                 }
 1731                 if (ip6e)
 1732                         return (&ip6e->ip6e_nxt);
 1733                 else
 1734                         return NULL;
 1735         }
 1736 }
 1737 
 1738 /*
 1739  * get next header offset.  m will be retained.
 1740  */
 1741 int
 1742 ip6_nexthdr(struct mbuf *m, int off, int proto, int *nxtp)
 1743 {
 1744         struct ip6_hdr ip6;
 1745         struct ip6_ext ip6e;
 1746         struct ip6_frag fh;
 1747 
 1748         /* just in case */
 1749         if (m == NULL)
 1750                 panic("ip6_nexthdr: m == NULL");
 1751         if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
 1752                 return -1;
 1753 
 1754         switch (proto) {
 1755         case IPPROTO_IPV6:
 1756                 if (m->m_pkthdr.len < off + sizeof(ip6))
 1757                         return -1;
 1758                 m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
 1759                 if (nxtp)
 1760                         *nxtp = ip6.ip6_nxt;
 1761                 off += sizeof(ip6);
 1762                 return off;
 1763 
 1764         case IPPROTO_FRAGMENT:
 1765                 /*
 1766                  * terminate parsing if it is not the first fragment,
 1767                  * it does not make sense to parse through it.
 1768                  */
 1769                 if (m->m_pkthdr.len < off + sizeof(fh))
 1770                         return -1;
 1771                 m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
 1772                 /* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
 1773                 if (fh.ip6f_offlg & IP6F_OFF_MASK)
 1774                         return -1;
 1775                 if (nxtp)
 1776                         *nxtp = fh.ip6f_nxt;
 1777                 off += sizeof(struct ip6_frag);
 1778                 return off;
 1779 
 1780         case IPPROTO_AH:
 1781                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1782                         return -1;
 1783                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1784                 if (nxtp)
 1785                         *nxtp = ip6e.ip6e_nxt;
 1786                 off += (ip6e.ip6e_len + 2) << 2;
 1787                 return off;
 1788 
 1789         case IPPROTO_HOPOPTS:
 1790         case IPPROTO_ROUTING:
 1791         case IPPROTO_DSTOPTS:
 1792                 if (m->m_pkthdr.len < off + sizeof(ip6e))
 1793                         return -1;
 1794                 m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
 1795                 if (nxtp)
 1796                         *nxtp = ip6e.ip6e_nxt;
 1797                 off += (ip6e.ip6e_len + 1) << 3;
 1798                 return off;
 1799 
 1800         case IPPROTO_NONE:
 1801         case IPPROTO_ESP:
 1802         case IPPROTO_IPCOMP:
 1803                 /* give up */
 1804                 return -1;
 1805 
 1806         default:
 1807                 return -1;
 1808         }
 1809 
 1810         return -1;
 1811 }
 1812 
 1813 /*
 1814  * get offset for the last header in the chain.  m will be kept untainted.
 1815  */
 1816 int
 1817 ip6_lasthdr(struct mbuf *m, int off, int proto, int *nxtp)
 1818 {
 1819         int newoff;
 1820         int nxt;
 1821 
 1822         if (!nxtp) {
 1823                 nxt = -1;
 1824                 nxtp = &nxt;
 1825         }
 1826         while (1) {
 1827                 newoff = ip6_nexthdr(m, off, proto, nxtp);
 1828                 if (newoff < 0)
 1829                         return off;
 1830                 else if (newoff < off)
 1831                         return -1;      /* invalid */
 1832                 else if (newoff == off)
 1833                         return newoff;
 1834 
 1835                 off = newoff;
 1836                 proto = *nxtp;
 1837         }
 1838 }
 1839 
 1840 static struct ip6aux *
 1841 ip6_addaux(struct mbuf *m)
 1842 {
 1843         struct m_tag *mtag;
 1844 
 1845         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1846         if (!mtag) {
 1847                 mtag = m_tag_get(PACKET_TAG_IPV6_INPUT, sizeof(struct ip6aux),
 1848                     M_NOWAIT);
 1849                 if (mtag) {
 1850                         m_tag_prepend(m, mtag);
 1851                         bzero(mtag + 1, sizeof(struct ip6aux));
 1852                 }
 1853         }
 1854         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1855 }
 1856 
 1857 static struct ip6aux *
 1858 ip6_findaux(struct mbuf *m)
 1859 {
 1860         struct m_tag *mtag;
 1861 
 1862         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1863         return mtag ? (struct ip6aux *)(mtag + 1) : NULL;
 1864 }
 1865 
 1866 static void
 1867 ip6_delaux(struct mbuf *m)
 1868 {
 1869         struct m_tag *mtag;
 1870 
 1871         mtag = m_tag_find(m, PACKET_TAG_IPV6_INPUT, NULL);
 1872         if (mtag)
 1873                 m_tag_delete(m, mtag);
 1874 }
 1875 
 1876 /*
 1877  * System control for IP6
 1878  */
 1879 
 1880 u_char  inet6ctlerrmap[PRC_NCMDS] = {
 1881         0,              0,              0,              0,
 1882         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1883         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1884         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1885         0,              0,              0,              0,
 1886         ENOPROTOOPT
 1887 };

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