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

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    1 /*      $FreeBSD$       */
    2 /*      $KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $        */
    3 
    4 /*-
    5  * Copyright (C) 2000 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  * 6to4 interface, based on RFC3056.
   35  *
   36  * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
   37  * There is no address mapping defined from IPv6 multicast address to IPv4
   38  * address.  Therefore, we do not have IFF_MULTICAST on the interface.
   39  *
   40  * Due to the lack of address mapping for link-local addresses, we cannot
   41  * throw packets toward link-local addresses (fe80::x).  Also, we cannot throw
   42  * packets to link-local multicast addresses (ff02::x).
   43  *
   44  * Here are interesting symptoms due to the lack of link-local address:
   45  *
   46  * Unicast routing exchange:
   47  * - RIPng: Impossible.  Uses link-local multicast packet toward ff02::9,
   48  *   and link-local addresses as nexthop.
   49  * - OSPFv6: Impossible.  OSPFv6 assumes that there's link-local address
   50  *   assigned to the link, and makes use of them.  Also, HELLO packets use
   51  *   link-local multicast addresses (ff02::5 and ff02::6).
   52  * - BGP4+: Maybe.  You can only use global address as nexthop, and global
   53  *   address as TCP endpoint address.
   54  *
   55  * Multicast routing protocols:
   56  * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
   57  *   Adjacent PIM routers must be configured manually (is it really spec-wise
   58  *   correct thing to do?).
   59  *
   60  * ICMPv6:
   61  * - Redirects cannot be used due to the lack of link-local address.
   62  *
   63  * stf interface does not have, and will not need, a link-local address.  
   64  * It seems to have no real benefit and does not help the above symptoms much.
   65  * Even if we assign link-locals to interface, we cannot really
   66  * use link-local unicast/multicast on top of 6to4 cloud (since there's no
   67  * encapsulation defined for link-local address), and the above analysis does
   68  * not change.  RFC3056 does not mandate the assignment of link-local address
   69  * either.
   70  *
   71  * 6to4 interface has security issues.  Refer to
   72  * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
   73  * for details.  The code tries to filter out some of malicious packets.
   74  * Note that there is no way to be 100% secure.
   75  */
   76 
   77 #include "opt_inet.h"
   78 #include "opt_inet6.h"
   79 #include "opt_mac.h"
   80 
   81 #include <sys/param.h>
   82 #include <sys/systm.h>
   83 #include <sys/socket.h>
   84 #include <sys/sockio.h>
   85 #include <sys/mac.h>
   86 #include <sys/mbuf.h>
   87 #include <sys/errno.h>
   88 #include <sys/kernel.h>
   89 #include <sys/module.h>
   90 #include <sys/protosw.h>
   91 #include <sys/queue.h>
   92 #include <machine/cpu.h>
   93 
   94 #include <sys/malloc.h>
   95 
   96 #include <net/if.h>
   97 #include <net/if_clone.h>
   98 #include <net/route.h>
   99 #include <net/netisr.h>
  100 #include <net/if_types.h>
  101 #include <net/if_stf.h>
  102 
  103 #include <netinet/in.h>
  104 #include <netinet/in_systm.h>
  105 #include <netinet/ip.h>
  106 #include <netinet/ip_var.h>
  107 #include <netinet/in_var.h>
  108 
  109 #include <netinet/ip6.h>
  110 #include <netinet6/ip6_var.h>
  111 #include <netinet6/in6_var.h>
  112 #include <netinet/ip_ecn.h>
  113 
  114 #include <netinet/ip_encap.h>
  115 
  116 #include <machine/stdarg.h>
  117 
  118 #include <net/net_osdep.h>
  119 
  120 #include <net/bpf.h>
  121 
  122 #define STFNAME         "stf"
  123 #define STFUNIT         0
  124 
  125 #define IN6_IS_ADDR_6TO4(x)     (ntohs((x)->s6_addr16[0]) == 0x2002)
  126 
  127 /*
  128  * XXX: Return a pointer with 16-bit aligned.  Don't cast it to
  129  * struct in_addr *; use bcopy() instead.
  130  */
  131 #define GET_V4(x)       ((caddr_t)(&(x)->s6_addr16[1]))
  132 
  133 struct stf_softc {
  134         struct ifnet    *sc_ifp;
  135         union {
  136                 struct route  __sc_ro4;
  137                 struct route_in6 __sc_ro6; /* just for safety */
  138         } __sc_ro46;
  139 #define sc_ro   __sc_ro46.__sc_ro4
  140         const struct encaptab *encap_cookie;
  141         LIST_ENTRY(stf_softc) sc_list;  /* all stf's are linked */
  142 };
  143 #define STF2IFP(sc)     ((sc)->sc_ifp)
  144 
  145 /*
  146  * All mutable global variables in if_stf.c are protected by stf_mtx.
  147  * XXXRW: Note that mutable fields in the softc are not currently locked:
  148  * in particular, sc_ro needs to be protected from concurrent entrance
  149  * of stf_output().
  150  */
  151 static struct mtx stf_mtx;
  152 static LIST_HEAD(, stf_softc) stf_softc_list;
  153 
  154 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
  155 static const int ip_stf_ttl = 40;
  156 
  157 extern  struct domain inetdomain;
  158 struct protosw in_stf_protosw = {
  159         .pr_type =              SOCK_RAW,
  160         .pr_domain =            &inetdomain,
  161         .pr_protocol =          IPPROTO_IPV6,
  162         .pr_flags =             PR_ATOMIC|PR_ADDR,
  163         .pr_input =             in_stf_input,
  164         .pr_output =            (pr_output_t *)rip_output,
  165         .pr_ctloutput =         rip_ctloutput,
  166         .pr_usrreqs =           &rip_usrreqs
  167 };
  168 
  169 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
  170 
  171 static int stfmodevent(module_t, int, void *);
  172 static int stf_encapcheck(const struct mbuf *, int, int, void *);
  173 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
  174 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
  175         struct rtentry *);
  176 static int isrfc1918addr(struct in_addr *);
  177 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
  178         struct ifnet *);
  179 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
  180         struct ifnet *);
  181 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
  182 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
  183 
  184 static int stf_clone_match(struct if_clone *, const char *);
  185 static int stf_clone_create(struct if_clone *, char *, size_t);
  186 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
  187 struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0,
  188     NULL, stf_clone_match, stf_clone_create, stf_clone_destroy);
  189 
  190 static int
  191 stf_clone_match(struct if_clone *ifc, const char *name)
  192 {
  193         int i;
  194 
  195         for(i = 0; stfnames[i] != NULL; i++) {
  196                 if (strcmp(stfnames[i], name) == 0)
  197                         return (1);
  198         }
  199 
  200         return (0);
  201 }
  202 
  203 static int
  204 stf_clone_create(struct if_clone *ifc, char *name, size_t len)
  205 {
  206         int err, unit;
  207         struct stf_softc *sc;
  208         struct ifnet *ifp;
  209 
  210         /*
  211          * We can only have one unit, but since unit allocation is
  212          * already locked, we use it to keep from allocating extra
  213          * interfaces.
  214          */
  215         unit = STFUNIT;
  216         err = ifc_alloc_unit(ifc, &unit);
  217         if (err != 0)
  218                 return (err);
  219 
  220         sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
  221         ifp = STF2IFP(sc) = if_alloc(IFT_STF);
  222         if (ifp == NULL) {
  223                 free(sc, M_STF);
  224                 ifc_free_unit(ifc, unit);
  225                 return (ENOSPC);
  226         }
  227         ifp->if_softc = sc;
  228 
  229         /*
  230          * Set the name manually rather then using if_initname because
  231          * we don't conform to the default naming convention for interfaces.
  232          */
  233         strlcpy(ifp->if_xname, name, IFNAMSIZ);
  234         ifp->if_dname = ifc->ifc_name;
  235         ifp->if_dunit = IF_DUNIT_NONE;
  236 
  237         sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
  238             stf_encapcheck, &in_stf_protosw, sc);
  239         if (sc->encap_cookie == NULL) {
  240                 if_printf(ifp, "attach failed\n");
  241                 free(sc, M_STF);
  242                 ifc_free_unit(ifc, unit);
  243                 return (ENOMEM);
  244         }
  245 
  246         ifp->if_mtu    = IPV6_MMTU;
  247         ifp->if_ioctl  = stf_ioctl;
  248         ifp->if_output = stf_output;
  249         ifp->if_snd.ifq_maxlen = IFQ_MAXLEN;
  250         if_attach(ifp);
  251         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  252         mtx_lock(&stf_mtx);
  253         LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
  254         mtx_unlock(&stf_mtx);
  255         return (0);
  256 }
  257 
  258 static void
  259 stf_destroy(struct stf_softc *sc)
  260 {
  261         int err;
  262 
  263         err = encap_detach(sc->encap_cookie);
  264         KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
  265         bpfdetach(STF2IFP(sc));
  266         if_detach(STF2IFP(sc));
  267         if_free(STF2IFP(sc));
  268 
  269         free(sc, M_STF);
  270 }
  271 
  272 static int
  273 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
  274 {
  275         struct stf_softc *sc = ifp->if_softc;
  276 
  277         mtx_lock(&stf_mtx);
  278         LIST_REMOVE(sc, sc_list);
  279         mtx_unlock(&stf_mtx);
  280 
  281         stf_destroy(sc);
  282         ifc_free_unit(ifc, STFUNIT);
  283 
  284         return (0);
  285 }
  286 
  287 static int
  288 stfmodevent(mod, type, data)
  289         module_t mod;
  290         int type;
  291         void *data;
  292 {
  293         struct stf_softc *sc;
  294 
  295         switch (type) {
  296         case MOD_LOAD:
  297                 mtx_init(&stf_mtx, "stf_mtx", NULL, MTX_DEF);
  298                 LIST_INIT(&stf_softc_list);
  299                 if_clone_attach(&stf_cloner);
  300 
  301                 break;
  302         case MOD_UNLOAD:
  303                 if_clone_detach(&stf_cloner);
  304 
  305                 mtx_lock(&stf_mtx);
  306                 while ((sc = LIST_FIRST(&stf_softc_list)) != NULL) {
  307                         LIST_REMOVE(sc, sc_list);
  308                         mtx_unlock(&stf_mtx);
  309                         stf_destroy(sc);
  310                         mtx_lock(&stf_mtx);
  311                 }
  312                 mtx_unlock(&stf_mtx);
  313                 mtx_destroy(&stf_mtx);
  314                 break;
  315         default:
  316                 return (EOPNOTSUPP);
  317         }
  318 
  319         return (0);
  320 }
  321 
  322 static moduledata_t stf_mod = {
  323         "if_stf",
  324         stfmodevent,
  325         0
  326 };
  327 
  328 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  329 
  330 static int
  331 stf_encapcheck(m, off, proto, arg)
  332         const struct mbuf *m;
  333         int off;
  334         int proto;
  335         void *arg;
  336 {
  337         struct ip ip;
  338         struct in6_ifaddr *ia6;
  339         struct stf_softc *sc;
  340         struct in_addr a, b, mask;
  341 
  342         sc = (struct stf_softc *)arg;
  343         if (sc == NULL)
  344                 return 0;
  345 
  346         if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
  347                 return 0;
  348 
  349         /* IFF_LINK0 means "no decapsulation" */
  350         if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
  351                 return 0;
  352 
  353         if (proto != IPPROTO_IPV6)
  354                 return 0;
  355 
  356         /* LINTED const cast */
  357         m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
  358 
  359         if (ip.ip_v != 4)
  360                 return 0;
  361 
  362         ia6 = stf_getsrcifa6(STF2IFP(sc));
  363         if (ia6 == NULL)
  364                 return 0;
  365 
  366         /*
  367          * check if IPv4 dst matches the IPv4 address derived from the
  368          * local 6to4 address.
  369          * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
  370          */
  371         if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
  372             sizeof(ip.ip_dst)) != 0)
  373                 return 0;
  374 
  375         /*
  376          * check if IPv4 src matches the IPv4 address derived from the
  377          * local 6to4 address masked by prefixmask.
  378          * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
  379          * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
  380          */
  381         bzero(&a, sizeof(a));
  382         bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
  383         bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
  384         a.s_addr &= mask.s_addr;
  385         b = ip.ip_src;
  386         b.s_addr &= mask.s_addr;
  387         if (a.s_addr != b.s_addr)
  388                 return 0;
  389 
  390         /* stf interface makes single side match only */
  391         return 32;
  392 }
  393 
  394 static struct in6_ifaddr *
  395 stf_getsrcifa6(ifp)
  396         struct ifnet *ifp;
  397 {
  398         struct ifaddr *ia;
  399         struct in_ifaddr *ia4;
  400         struct sockaddr_in6 *sin6;
  401         struct in_addr in;
  402 
  403         for (ia = TAILQ_FIRST(&ifp->if_addrlist);
  404              ia;
  405              ia = TAILQ_NEXT(ia, ifa_list))
  406         {
  407                 if (ia->ifa_addr == NULL)
  408                         continue;
  409                 if (ia->ifa_addr->sa_family != AF_INET6)
  410                         continue;
  411                 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
  412                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
  413                         continue;
  414 
  415                 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
  416                 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
  417                         if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
  418                                 break;
  419                 if (ia4 == NULL)
  420                         continue;
  421 
  422                 return (struct in6_ifaddr *)ia;
  423         }
  424 
  425         return NULL;
  426 }
  427 
  428 static int
  429 stf_output(ifp, m, dst, rt)
  430         struct ifnet *ifp;
  431         struct mbuf *m;
  432         struct sockaddr *dst;
  433         struct rtentry *rt;
  434 {
  435         struct stf_softc *sc;
  436         struct sockaddr_in6 *dst6;
  437         struct in_addr in4;
  438         caddr_t ptr;
  439         struct sockaddr_in *dst4;
  440         u_int8_t tos;
  441         struct ip *ip;
  442         struct ip6_hdr *ip6;
  443         struct in6_ifaddr *ia6;
  444         u_int32_t af;
  445 #ifdef MAC
  446         int error;
  447 
  448         error = mac_check_ifnet_transmit(ifp, m);
  449         if (error) {
  450                 m_freem(m);
  451                 return (error);
  452         }
  453 #endif
  454 
  455         sc = ifp->if_softc;
  456         dst6 = (struct sockaddr_in6 *)dst;
  457 
  458         /* just in case */
  459         if ((ifp->if_flags & IFF_UP) == 0) {
  460                 m_freem(m);
  461                 ifp->if_oerrors++;
  462                 return ENETDOWN;
  463         }
  464 
  465         /*
  466          * If we don't have an ip4 address that match my inner ip6 address,
  467          * we shouldn't generate output.  Without this check, we'll end up
  468          * using wrong IPv4 source.
  469          */
  470         ia6 = stf_getsrcifa6(ifp);
  471         if (ia6 == NULL) {
  472                 m_freem(m);
  473                 ifp->if_oerrors++;
  474                 return ENETDOWN;
  475         }
  476 
  477         if (m->m_len < sizeof(*ip6)) {
  478                 m = m_pullup(m, sizeof(*ip6));
  479                 if (!m) {
  480                         ifp->if_oerrors++;
  481                         return ENOBUFS;
  482                 }
  483         }
  484         ip6 = mtod(m, struct ip6_hdr *);
  485         tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  486 
  487         /*
  488          * BPF writes need to be handled specially.
  489          * This is a null operation, nothing here checks dst->sa_family.
  490          */
  491         if (dst->sa_family == AF_UNSPEC) {
  492                 bcopy(dst->sa_data, &af, sizeof(af));
  493                 dst->sa_family = af;
  494         }
  495 
  496         /*
  497          * Pickup the right outer dst addr from the list of candidates.
  498          * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
  499          */
  500         ptr = NULL;
  501         if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
  502                 ptr = GET_V4(&ip6->ip6_dst);
  503         else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
  504                 ptr = GET_V4(&dst6->sin6_addr);
  505         else {
  506                 m_freem(m);
  507                 ifp->if_oerrors++;
  508                 return ENETUNREACH;
  509         }
  510         bcopy(ptr, &in4, sizeof(in4));
  511 
  512         if (bpf_peers_present(ifp->if_bpf)) {
  513                 /*
  514                  * We need to prepend the address family as
  515                  * a four byte field.  Cons up a dummy header
  516                  * to pacify bpf.  This is safe because bpf
  517                  * will only read from the mbuf (i.e., it won't
  518                  * try to free it or keep a pointer a to it).
  519                  */
  520                 af = AF_INET6;
  521                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  522         }
  523 
  524         M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
  525         if (m && m->m_len < sizeof(struct ip))
  526                 m = m_pullup(m, sizeof(struct ip));
  527         if (m == NULL) {
  528                 ifp->if_oerrors++;
  529                 return ENOBUFS;
  530         }
  531         ip = mtod(m, struct ip *);
  532 
  533         bzero(ip, sizeof(*ip));
  534 
  535         bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
  536             &ip->ip_src, sizeof(ip->ip_src));
  537         bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
  538         ip->ip_p = IPPROTO_IPV6;
  539         ip->ip_ttl = ip_stf_ttl;
  540         ip->ip_len = m->m_pkthdr.len;   /*host order*/
  541         if (ifp->if_flags & IFF_LINK1)
  542                 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
  543         else
  544                 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
  545 
  546         /*
  547          * XXXRW: Locking of sc_ro required.
  548          */
  549         dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
  550         if (dst4->sin_family != AF_INET ||
  551             bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
  552                 /* cache route doesn't match */
  553                 dst4->sin_family = AF_INET;
  554                 dst4->sin_len = sizeof(struct sockaddr_in);
  555                 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
  556                 if (sc->sc_ro.ro_rt) {
  557                         RTFREE(sc->sc_ro.ro_rt);
  558                         sc->sc_ro.ro_rt = NULL;
  559                 }
  560         }
  561 
  562         if (sc->sc_ro.ro_rt == NULL) {
  563                 rtalloc(&sc->sc_ro);
  564                 if (sc->sc_ro.ro_rt == NULL) {
  565                         m_freem(m);
  566                         ifp->if_oerrors++;
  567                         return ENETUNREACH;
  568                 }
  569         }
  570 
  571         ifp->if_opackets++;
  572         return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
  573 }
  574 
  575 static int
  576 isrfc1918addr(in)
  577         struct in_addr *in;
  578 {
  579         /*
  580          * returns 1 if private address range:
  581          * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
  582          */
  583         if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
  584             (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
  585             (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
  586                 return 1;
  587 
  588         return 0;
  589 }
  590 
  591 static int
  592 stf_checkaddr4(sc, in, inifp)
  593         struct stf_softc *sc;
  594         struct in_addr *in;
  595         struct ifnet *inifp;    /* incoming interface */
  596 {
  597         struct in_ifaddr *ia4;
  598 
  599         /*
  600          * reject packets with the following address:
  601          * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
  602          */
  603         if (IN_MULTICAST(ntohl(in->s_addr)))
  604                 return -1;
  605         switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
  606         case 0: case 127: case 255:
  607                 return -1;
  608         }
  609 
  610         /*
  611          * reject packets with private address range.
  612          * (requirement from RFC3056 section 2 1st paragraph)
  613          */
  614         if (isrfc1918addr(in))
  615                 return -1;
  616 
  617         /*
  618          * reject packets with broadcast
  619          */
  620         for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
  621              ia4;
  622              ia4 = TAILQ_NEXT(ia4, ia_link))
  623         {
  624                 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
  625                         continue;
  626                 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
  627                         return -1;
  628         }
  629 
  630         /*
  631          * perform ingress filter
  632          */
  633         if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
  634                 struct sockaddr_in sin;
  635                 struct rtentry *rt;
  636 
  637                 bzero(&sin, sizeof(sin));
  638                 sin.sin_family = AF_INET;
  639                 sin.sin_len = sizeof(struct sockaddr_in);
  640                 sin.sin_addr = *in;
  641                 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
  642                 if (!rt || rt->rt_ifp != inifp) {
  643 #if 0
  644                         log(LOG_WARNING, "%s: packet from 0x%x dropped "
  645                             "due to ingress filter\n", if_name(STF2IFP(sc)),
  646                             (u_int32_t)ntohl(sin.sin_addr.s_addr));
  647 #endif
  648                         if (rt)
  649                                 RTFREE_LOCKED(rt);
  650                         return -1;
  651                 }
  652                 RTFREE_LOCKED(rt);
  653         }
  654 
  655         return 0;
  656 }
  657 
  658 static int
  659 stf_checkaddr6(sc, in6, inifp)
  660         struct stf_softc *sc;
  661         struct in6_addr *in6;
  662         struct ifnet *inifp;    /* incoming interface */
  663 {
  664         /*
  665          * check 6to4 addresses
  666          */
  667         if (IN6_IS_ADDR_6TO4(in6)) {
  668                 struct in_addr in4;
  669                 bcopy(GET_V4(in6), &in4, sizeof(in4));
  670                 return stf_checkaddr4(sc, &in4, inifp);
  671         }
  672 
  673         /*
  674          * reject anything that look suspicious.  the test is implemented
  675          * in ip6_input too, but we check here as well to
  676          * (1) reject bad packets earlier, and
  677          * (2) to be safe against future ip6_input change.
  678          */
  679         if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
  680                 return -1;
  681 
  682         return 0;
  683 }
  684 
  685 void
  686 in_stf_input(m, off)
  687         struct mbuf *m;
  688         int off;
  689 {
  690         int proto;
  691         struct stf_softc *sc;
  692         struct ip *ip;
  693         struct ip6_hdr *ip6;
  694         u_int8_t otos, itos;
  695         struct ifnet *ifp;
  696 
  697         proto = mtod(m, struct ip *)->ip_p;
  698 
  699         if (proto != IPPROTO_IPV6) {
  700                 m_freem(m);
  701                 return;
  702         }
  703 
  704         ip = mtod(m, struct ip *);
  705 
  706         sc = (struct stf_softc *)encap_getarg(m);
  707 
  708         if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
  709                 m_freem(m);
  710                 return;
  711         }
  712 
  713         ifp = STF2IFP(sc);
  714 
  715 #ifdef MAC
  716         mac_create_mbuf_from_ifnet(ifp, m);
  717 #endif
  718 
  719         /*
  720          * perform sanity check against outer src/dst.
  721          * for source, perform ingress filter as well.
  722          */
  723         if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
  724             stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
  725                 m_freem(m);
  726                 return;
  727         }
  728 
  729         otos = ip->ip_tos;
  730         m_adj(m, off);
  731 
  732         if (m->m_len < sizeof(*ip6)) {
  733                 m = m_pullup(m, sizeof(*ip6));
  734                 if (!m)
  735                         return;
  736         }
  737         ip6 = mtod(m, struct ip6_hdr *);
  738 
  739         /*
  740          * perform sanity check against inner src/dst.
  741          * for source, perform ingress filter as well.
  742          */
  743         if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
  744             stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
  745                 m_freem(m);
  746                 return;
  747         }
  748 
  749         itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  750         if ((ifp->if_flags & IFF_LINK1) != 0)
  751                 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
  752         else
  753                 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
  754         ip6->ip6_flow &= ~htonl(0xff << 20);
  755         ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
  756 
  757         m->m_pkthdr.rcvif = ifp;
  758         
  759         if (bpf_peers_present(ifp->if_bpf)) {
  760                 /*
  761                  * We need to prepend the address family as
  762                  * a four byte field.  Cons up a dummy header
  763                  * to pacify bpf.  This is safe because bpf
  764                  * will only read from the mbuf (i.e., it won't
  765                  * try to free it or keep a pointer a to it).
  766                  */
  767                 u_int32_t af = AF_INET6;
  768                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  769         }
  770 
  771         /*
  772          * Put the packet to the network layer input queue according to the
  773          * specified address family.
  774          * See net/if_gif.c for possible issues with packet processing
  775          * reorder due to extra queueing.
  776          */
  777         ifp->if_ipackets++;
  778         ifp->if_ibytes += m->m_pkthdr.len;
  779         netisr_dispatch(NETISR_IPV6, m);
  780 }
  781 
  782 /* ARGSUSED */
  783 static void
  784 stf_rtrequest(cmd, rt, info)
  785         int cmd;
  786         struct rtentry *rt;
  787         struct rt_addrinfo *info;
  788 {
  789         RT_LOCK_ASSERT(rt);
  790         rt->rt_rmx.rmx_mtu = IPV6_MMTU;
  791 }
  792 
  793 static int
  794 stf_ioctl(ifp, cmd, data)
  795         struct ifnet *ifp;
  796         u_long cmd;
  797         caddr_t data;
  798 {
  799         struct ifaddr *ifa;
  800         struct ifreq *ifr;
  801         struct sockaddr_in6 *sin6;
  802         struct in_addr addr;
  803         int error;
  804 
  805         error = 0;
  806         switch (cmd) {
  807         case SIOCSIFADDR:
  808                 ifa = (struct ifaddr *)data;
  809                 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
  810                         error = EAFNOSUPPORT;
  811                         break;
  812                 }
  813                 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
  814                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
  815                         error = EINVAL;
  816                         break;
  817                 }
  818                 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
  819                 if (isrfc1918addr(&addr)) {
  820                         error = EINVAL;
  821                         break;
  822                 }
  823 
  824                 ifa->ifa_rtrequest = stf_rtrequest;
  825                 ifp->if_flags |= IFF_UP;
  826                 break;
  827 
  828         case SIOCADDMULTI:
  829         case SIOCDELMULTI:
  830                 ifr = (struct ifreq *)data;
  831                 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
  832                         ;
  833                 else
  834                         error = EAFNOSUPPORT;
  835                 break;
  836 
  837         default:
  838                 error = EINVAL;
  839                 break;
  840         }
  841 
  842         return error;
  843 }

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