The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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sys/net/if_stf.c

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    1 /*      $FreeBSD: stable/8/sys/net/if_stf.c 231380 2012-02-10 13:15:11Z bz $    */
    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 
   80 #include <sys/param.h>
   81 #include <sys/systm.h>
   82 #include <sys/socket.h>
   83 #include <sys/sockio.h>
   84 #include <sys/mbuf.h>
   85 #include <sys/errno.h>
   86 #include <sys/kernel.h>
   87 #include <sys/module.h>
   88 #include <sys/protosw.h>
   89 #include <sys/proc.h>
   90 #include <sys/queue.h>
   91 #include <sys/sysctl.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 #include <net/vnet.h>
  103 
  104 #include <netinet/in.h>
  105 #include <netinet/in_systm.h>
  106 #include <netinet/ip.h>
  107 #include <netinet/ip_var.h>
  108 #include <netinet/in_var.h>
  109 
  110 #include <netinet/ip6.h>
  111 #include <netinet6/ip6_var.h>
  112 #include <netinet6/in6_var.h>
  113 #include <netinet/ip_ecn.h>
  114 
  115 #include <netinet/ip_encap.h>
  116 
  117 #include <machine/stdarg.h>
  118 
  119 #include <net/bpf.h>
  120 
  121 #include <security/mac/mac_framework.h>
  122 
  123 SYSCTL_DECL(_net_link);
  124 SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface");
  125 
  126 static int stf_route_cache = 1;
  127 SYSCTL_INT(_net_link_stf, OID_AUTO, route_cache, CTLFLAG_RW,
  128     &stf_route_cache, 0, "Caching of IPv4 routes for 6to4 Output");
  129 
  130 #define STFNAME         "stf"
  131 #define STFUNIT         0
  132 
  133 #define IN6_IS_ADDR_6TO4(x)     (ntohs((x)->s6_addr16[0]) == 0x2002)
  134 
  135 /*
  136  * XXX: Return a pointer with 16-bit aligned.  Don't cast it to
  137  * struct in_addr *; use bcopy() instead.
  138  */
  139 #define GET_V4(x)       ((caddr_t)(&(x)->s6_addr16[1]))
  140 
  141 struct stf_softc {
  142         struct ifnet    *sc_ifp;
  143         union {
  144                 struct route  __sc_ro4;
  145                 struct route_in6 __sc_ro6; /* just for safety */
  146         } __sc_ro46;
  147 #define sc_ro   __sc_ro46.__sc_ro4
  148         struct mtx      sc_ro_mtx;
  149         u_int   sc_fibnum;
  150         const struct encaptab *encap_cookie;
  151 };
  152 #define STF2IFP(sc)     ((sc)->sc_ifp)
  153 
  154 /*
  155  * Note that mutable fields in the softc are not currently locked.
  156  * We do lock sc_ro in stf_output though.
  157  */
  158 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
  159 static const int ip_stf_ttl = 40;
  160 
  161 extern  struct domain inetdomain;
  162 struct protosw in_stf_protosw = {
  163         .pr_type =              SOCK_RAW,
  164         .pr_domain =            &inetdomain,
  165         .pr_protocol =          IPPROTO_IPV6,
  166         .pr_flags =             PR_ATOMIC|PR_ADDR,
  167         .pr_input =             in_stf_input,
  168         .pr_output =            (pr_output_t *)rip_output,
  169         .pr_ctloutput =         rip_ctloutput,
  170         .pr_usrreqs =           &rip_usrreqs
  171 };
  172 
  173 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
  174 
  175 static int stfmodevent(module_t, int, void *);
  176 static int stf_encapcheck(const struct mbuf *, int, int, void *);
  177 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
  178 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
  179         struct route *);
  180 static int isrfc1918addr(struct in_addr *);
  181 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
  182         struct ifnet *);
  183 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
  184         struct ifnet *);
  185 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
  186 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
  187 
  188 static int stf_clone_match(struct if_clone *, const char *);
  189 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
  190 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
  191 struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0,
  192     NULL, stf_clone_match, stf_clone_create, stf_clone_destroy);
  193 
  194 static int
  195 stf_clone_match(struct if_clone *ifc, const char *name)
  196 {
  197         int i;
  198 
  199         for(i = 0; stfnames[i] != NULL; i++) {
  200                 if (strcmp(stfnames[i], name) == 0)
  201                         return (1);
  202         }
  203 
  204         return (0);
  205 }
  206 
  207 static int
  208 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
  209 {
  210         int err, unit;
  211         struct stf_softc *sc;
  212         struct ifnet *ifp;
  213 
  214         /*
  215          * We can only have one unit, but since unit allocation is
  216          * already locked, we use it to keep from allocating extra
  217          * interfaces.
  218          */
  219         unit = STFUNIT;
  220         err = ifc_alloc_unit(ifc, &unit);
  221         if (err != 0)
  222                 return (err);
  223 
  224         sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
  225         ifp = STF2IFP(sc) = if_alloc(IFT_STF);
  226         if (ifp == NULL) {
  227                 free(sc, M_STF);
  228                 ifc_free_unit(ifc, unit);
  229                 return (ENOSPC);
  230         }
  231         ifp->if_softc = sc;
  232         sc->sc_fibnum = curthread->td_proc->p_fibnum;
  233 
  234         /*
  235          * Set the name manually rather then using if_initname because
  236          * we don't conform to the default naming convention for interfaces.
  237          */
  238         strlcpy(ifp->if_xname, name, IFNAMSIZ);
  239         ifp->if_dname = ifc->ifc_name;
  240         ifp->if_dunit = IF_DUNIT_NONE;
  241 
  242         mtx_init(&(sc)->sc_ro_mtx, "stf ro", NULL, MTX_DEF);
  243         sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
  244             stf_encapcheck, &in_stf_protosw, sc);
  245         if (sc->encap_cookie == NULL) {
  246                 if_printf(ifp, "attach failed\n");
  247                 free(sc, M_STF);
  248                 ifc_free_unit(ifc, unit);
  249                 return (ENOMEM);
  250         }
  251 
  252         ifp->if_mtu    = IPV6_MMTU;
  253         ifp->if_ioctl  = stf_ioctl;
  254         ifp->if_output = stf_output;
  255         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  256         if_attach(ifp);
  257         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  258         return (0);
  259 }
  260 
  261 static int
  262 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
  263 {
  264         struct stf_softc *sc = ifp->if_softc;
  265         int err;
  266 
  267         err = encap_detach(sc->encap_cookie);
  268         KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
  269         mtx_destroy(&(sc)->sc_ro_mtx);
  270         bpfdetach(ifp);
  271         if_detach(ifp);
  272         if_free(ifp);
  273 
  274         free(sc, M_STF);
  275         ifc_free_unit(ifc, STFUNIT);
  276 
  277         return (0);
  278 }
  279 
  280 static int
  281 stfmodevent(mod, type, data)
  282         module_t mod;
  283         int type;
  284         void *data;
  285 {
  286 
  287         switch (type) {
  288         case MOD_LOAD:
  289                 if_clone_attach(&stf_cloner);
  290                 break;
  291         case MOD_UNLOAD:
  292                 if_clone_detach(&stf_cloner);
  293                 break;
  294         default:
  295                 return (EOPNOTSUPP);
  296         }
  297 
  298         return (0);
  299 }
  300 
  301 static moduledata_t stf_mod = {
  302         "if_stf",
  303         stfmodevent,
  304         0
  305 };
  306 
  307 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  308 
  309 static int
  310 stf_encapcheck(m, off, proto, arg)
  311         const struct mbuf *m;
  312         int off;
  313         int proto;
  314         void *arg;
  315 {
  316         struct ip ip;
  317         struct in6_ifaddr *ia6;
  318         struct stf_softc *sc;
  319         struct in_addr a, b, mask;
  320 
  321         sc = (struct stf_softc *)arg;
  322         if (sc == NULL)
  323                 return 0;
  324 
  325         if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
  326                 return 0;
  327 
  328         /* IFF_LINK0 means "no decapsulation" */
  329         if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
  330                 return 0;
  331 
  332         if (proto != IPPROTO_IPV6)
  333                 return 0;
  334 
  335         /* LINTED const cast */
  336         m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
  337 
  338         if (ip.ip_v != 4)
  339                 return 0;
  340 
  341         ia6 = stf_getsrcifa6(STF2IFP(sc));
  342         if (ia6 == NULL)
  343                 return 0;
  344 
  345         /*
  346          * check if IPv4 dst matches the IPv4 address derived from the
  347          * local 6to4 address.
  348          * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
  349          */
  350         if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
  351             sizeof(ip.ip_dst)) != 0) {
  352                 ifa_free(&ia6->ia_ifa);
  353                 return 0;
  354         }
  355 
  356         /*
  357          * check if IPv4 src matches the IPv4 address derived from the
  358          * local 6to4 address masked by prefixmask.
  359          * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
  360          * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
  361          */
  362         bzero(&a, sizeof(a));
  363         bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
  364         bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
  365         ifa_free(&ia6->ia_ifa);
  366         a.s_addr &= mask.s_addr;
  367         b = ip.ip_src;
  368         b.s_addr &= mask.s_addr;
  369         if (a.s_addr != b.s_addr)
  370                 return 0;
  371 
  372         /* stf interface makes single side match only */
  373         return 32;
  374 }
  375 
  376 static struct in6_ifaddr *
  377 stf_getsrcifa6(ifp)
  378         struct ifnet *ifp;
  379 {
  380         struct ifaddr *ia;
  381         struct in_ifaddr *ia4;
  382         struct sockaddr_in6 *sin6;
  383         struct in_addr in;
  384 
  385         if_addr_rlock(ifp);
  386         TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
  387                 if (ia->ifa_addr->sa_family != AF_INET6)
  388                         continue;
  389                 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
  390                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
  391                         continue;
  392 
  393                 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
  394                 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
  395                         if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
  396                                 break;
  397                 if (ia4 == NULL)
  398                         continue;
  399 
  400                 ifa_ref(ia);
  401                 if_addr_runlock(ifp);
  402                 return (struct in6_ifaddr *)ia;
  403         }
  404         if_addr_runlock(ifp);
  405 
  406         return NULL;
  407 }
  408 
  409 static int
  410 stf_output(ifp, m, dst, ro)
  411         struct ifnet *ifp;
  412         struct mbuf *m;
  413         struct sockaddr *dst;
  414         struct route *ro;
  415 {
  416         struct stf_softc *sc;
  417         struct sockaddr_in6 *dst6;
  418         struct route *cached_route;
  419         struct in_addr in4;
  420         caddr_t ptr;
  421         struct sockaddr_in *dst4;
  422         u_int8_t tos;
  423         struct ip *ip;
  424         struct ip6_hdr *ip6;
  425         struct in6_ifaddr *ia6;
  426         u_int32_t af;
  427         int error;
  428 
  429 #ifdef MAC
  430         error = mac_ifnet_check_transmit(ifp, m);
  431         if (error) {
  432                 m_freem(m);
  433                 return (error);
  434         }
  435 #endif
  436 
  437         sc = ifp->if_softc;
  438         dst6 = (struct sockaddr_in6 *)dst;
  439 
  440         /* just in case */
  441         if ((ifp->if_flags & IFF_UP) == 0) {
  442                 m_freem(m);
  443                 ifp->if_oerrors++;
  444                 return ENETDOWN;
  445         }
  446 
  447         /*
  448          * If we don't have an ip4 address that match my inner ip6 address,
  449          * we shouldn't generate output.  Without this check, we'll end up
  450          * using wrong IPv4 source.
  451          */
  452         ia6 = stf_getsrcifa6(ifp);
  453         if (ia6 == NULL) {
  454                 m_freem(m);
  455                 ifp->if_oerrors++;
  456                 return ENETDOWN;
  457         }
  458 
  459         if (m->m_len < sizeof(*ip6)) {
  460                 m = m_pullup(m, sizeof(*ip6));
  461                 if (!m) {
  462                         ifa_free(&ia6->ia_ifa);
  463                         ifp->if_oerrors++;
  464                         return ENOBUFS;
  465                 }
  466         }
  467         ip6 = mtod(m, struct ip6_hdr *);
  468         tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  469 
  470         /*
  471          * BPF writes need to be handled specially.
  472          * This is a null operation, nothing here checks dst->sa_family.
  473          */
  474         if (dst->sa_family == AF_UNSPEC) {
  475                 bcopy(dst->sa_data, &af, sizeof(af));
  476                 dst->sa_family = af;
  477         }
  478 
  479         /*
  480          * Pickup the right outer dst addr from the list of candidates.
  481          * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
  482          */
  483         ptr = NULL;
  484         if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
  485                 ptr = GET_V4(&ip6->ip6_dst);
  486         else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
  487                 ptr = GET_V4(&dst6->sin6_addr);
  488         else {
  489                 ifa_free(&ia6->ia_ifa);
  490                 m_freem(m);
  491                 ifp->if_oerrors++;
  492                 return ENETUNREACH;
  493         }
  494         bcopy(ptr, &in4, sizeof(in4));
  495 
  496         if (bpf_peers_present(ifp->if_bpf)) {
  497                 /*
  498                  * We need to prepend the address family as
  499                  * a four byte field.  Cons up a dummy header
  500                  * to pacify bpf.  This is safe because bpf
  501                  * will only read from the mbuf (i.e., it won't
  502                  * try to free it or keep a pointer a to it).
  503                  */
  504                 af = AF_INET6;
  505                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  506         }
  507 
  508         M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
  509         if (m && m->m_len < sizeof(struct ip))
  510                 m = m_pullup(m, sizeof(struct ip));
  511         if (m == NULL) {
  512                 ifa_free(&ia6->ia_ifa);
  513                 ifp->if_oerrors++;
  514                 return ENOBUFS;
  515         }
  516         ip = mtod(m, struct ip *);
  517 
  518         bzero(ip, sizeof(*ip));
  519 
  520         bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
  521             &ip->ip_src, sizeof(ip->ip_src));
  522         ifa_free(&ia6->ia_ifa);
  523         bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
  524         ip->ip_p = IPPROTO_IPV6;
  525         ip->ip_ttl = ip_stf_ttl;
  526         ip->ip_len = m->m_pkthdr.len;   /*host order*/
  527         if (ifp->if_flags & IFF_LINK1)
  528                 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
  529         else
  530                 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
  531 
  532         if (!stf_route_cache) {
  533                 cached_route = NULL;
  534                 goto sendit;
  535         }
  536 
  537         /*
  538          * Do we have a cached route?
  539          */
  540         mtx_lock(&(sc)->sc_ro_mtx);
  541         dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
  542         if (dst4->sin_family != AF_INET ||
  543             bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
  544                 /* cache route doesn't match */
  545                 dst4->sin_family = AF_INET;
  546                 dst4->sin_len = sizeof(struct sockaddr_in);
  547                 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
  548                 if (sc->sc_ro.ro_rt) {
  549                         RTFREE(sc->sc_ro.ro_rt);
  550                         sc->sc_ro.ro_rt = NULL;
  551                 }
  552         }
  553 
  554         if (sc->sc_ro.ro_rt == NULL) {
  555                 rtalloc_fib(&sc->sc_ro, sc->sc_fibnum);
  556                 if (sc->sc_ro.ro_rt == NULL) {
  557                         m_freem(m);
  558                         mtx_unlock(&(sc)->sc_ro_mtx);
  559                         ifp->if_oerrors++;
  560                         return ENETUNREACH;
  561                 }
  562         }
  563         cached_route = &sc->sc_ro;
  564 
  565 sendit:
  566         M_SETFIB(m, sc->sc_fibnum);
  567         ifp->if_opackets++;
  568         error = ip_output(m, NULL, cached_route, 0, NULL, NULL);
  569 
  570         if (cached_route != NULL)
  571                 mtx_unlock(&(sc)->sc_ro_mtx);
  572         return error;
  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         IN_IFADDR_RLOCK();
  621         for (ia4 = TAILQ_FIRST(&V_in_ifaddrhead);
  622              ia4;
  623              ia4 = TAILQ_NEXT(ia4, ia_link))
  624         {
  625                 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
  626                         continue;
  627                 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
  628                         IN_IFADDR_RUNLOCK();
  629                         return -1;
  630                 }
  631         }
  632         IN_IFADDR_RUNLOCK();
  633 
  634         /*
  635          * perform ingress filter
  636          */
  637         if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
  638                 struct sockaddr_in sin;
  639                 struct rtentry *rt;
  640 
  641                 bzero(&sin, sizeof(sin));
  642                 sin.sin_family = AF_INET;
  643                 sin.sin_len = sizeof(struct sockaddr_in);
  644                 sin.sin_addr = *in;
  645                 rt = rtalloc1_fib((struct sockaddr *)&sin, 0,
  646                     0UL, sc->sc_fibnum);
  647                 if (!rt || rt->rt_ifp != inifp) {
  648 #if 0
  649                         log(LOG_WARNING, "%s: packet from 0x%x dropped "
  650                             "due to ingress filter\n", if_name(STF2IFP(sc)),
  651                             (u_int32_t)ntohl(sin.sin_addr.s_addr));
  652 #endif
  653                         if (rt)
  654                                 RTFREE_LOCKED(rt);
  655                         return -1;
  656                 }
  657                 RTFREE_LOCKED(rt);
  658         }
  659 
  660         return 0;
  661 }
  662 
  663 static int
  664 stf_checkaddr6(sc, in6, inifp)
  665         struct stf_softc *sc;
  666         struct in6_addr *in6;
  667         struct ifnet *inifp;    /* incoming interface */
  668 {
  669         /*
  670          * check 6to4 addresses
  671          */
  672         if (IN6_IS_ADDR_6TO4(in6)) {
  673                 struct in_addr in4;
  674                 bcopy(GET_V4(in6), &in4, sizeof(in4));
  675                 return stf_checkaddr4(sc, &in4, inifp);
  676         }
  677 
  678         /*
  679          * reject anything that look suspicious.  the test is implemented
  680          * in ip6_input too, but we check here as well to
  681          * (1) reject bad packets earlier, and
  682          * (2) to be safe against future ip6_input change.
  683          */
  684         if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
  685                 return -1;
  686 
  687         return 0;
  688 }
  689 
  690 void
  691 in_stf_input(m, off)
  692         struct mbuf *m;
  693         int off;
  694 {
  695         int proto;
  696         struct stf_softc *sc;
  697         struct ip *ip;
  698         struct ip6_hdr *ip6;
  699         u_int8_t otos, itos;
  700         struct ifnet *ifp;
  701 
  702         proto = mtod(m, struct ip *)->ip_p;
  703 
  704         if (proto != IPPROTO_IPV6) {
  705                 m_freem(m);
  706                 return;
  707         }
  708 
  709         ip = mtod(m, struct ip *);
  710 
  711         sc = (struct stf_softc *)encap_getarg(m);
  712 
  713         if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
  714                 m_freem(m);
  715                 return;
  716         }
  717 
  718         ifp = STF2IFP(sc);
  719 
  720 #ifdef MAC
  721         mac_ifnet_create_mbuf(ifp, m);
  722 #endif
  723 
  724         /*
  725          * perform sanity check against outer src/dst.
  726          * for source, perform ingress filter as well.
  727          */
  728         if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
  729             stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
  730                 m_freem(m);
  731                 return;
  732         }
  733 
  734         otos = ip->ip_tos;
  735         m_adj(m, off);
  736 
  737         if (m->m_len < sizeof(*ip6)) {
  738                 m = m_pullup(m, sizeof(*ip6));
  739                 if (!m)
  740                         return;
  741         }
  742         ip6 = mtod(m, struct ip6_hdr *);
  743 
  744         /*
  745          * perform sanity check against inner src/dst.
  746          * for source, perform ingress filter as well.
  747          */
  748         if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
  749             stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
  750                 m_freem(m);
  751                 return;
  752         }
  753 
  754         itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  755         if ((ifp->if_flags & IFF_LINK1) != 0)
  756                 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
  757         else
  758                 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
  759         ip6->ip6_flow &= ~htonl(0xff << 20);
  760         ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
  761 
  762         m->m_pkthdr.rcvif = ifp;
  763         
  764         if (bpf_peers_present(ifp->if_bpf)) {
  765                 /*
  766                  * We need to prepend the address family as
  767                  * a four byte field.  Cons up a dummy header
  768                  * to pacify bpf.  This is safe because bpf
  769                  * will only read from the mbuf (i.e., it won't
  770                  * try to free it or keep a pointer a to it).
  771                  */
  772                 u_int32_t af = AF_INET6;
  773                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  774         }
  775 
  776         /*
  777          * Put the packet to the network layer input queue according to the
  778          * specified address family.
  779          * See net/if_gif.c for possible issues with packet processing
  780          * reorder due to extra queueing.
  781          */
  782         ifp->if_ipackets++;
  783         ifp->if_ibytes += m->m_pkthdr.len;
  784         M_SETFIB(m, ifp->if_fib);
  785         netisr_dispatch(NETISR_IPV6, m);
  786 }
  787 
  788 /* ARGSUSED */
  789 static void
  790 stf_rtrequest(cmd, rt, info)
  791         int cmd;
  792         struct rtentry *rt;
  793         struct rt_addrinfo *info;
  794 {
  795         RT_LOCK_ASSERT(rt);
  796         rt->rt_rmx.rmx_mtu = IPV6_MMTU;
  797 }
  798 
  799 static int
  800 stf_ioctl(ifp, cmd, data)
  801         struct ifnet *ifp;
  802         u_long cmd;
  803         caddr_t data;
  804 {
  805         struct ifaddr *ifa;
  806         struct ifreq *ifr;
  807         struct sockaddr_in6 *sin6;
  808         struct in_addr addr;
  809         int error;
  810 
  811         error = 0;
  812         switch (cmd) {
  813         case SIOCSIFADDR:
  814                 ifa = (struct ifaddr *)data;
  815                 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
  816                         error = EAFNOSUPPORT;
  817                         break;
  818                 }
  819                 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
  820                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
  821                         error = EINVAL;
  822                         break;
  823                 }
  824                 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
  825                 if (isrfc1918addr(&addr)) {
  826                         error = EINVAL;
  827                         break;
  828                 }
  829 
  830                 ifa->ifa_rtrequest = stf_rtrequest;
  831                 ifp->if_flags |= IFF_UP;
  832                 break;
  833 
  834         case SIOCADDMULTI:
  835         case SIOCDELMULTI:
  836                 ifr = (struct ifreq *)data;
  837                 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
  838                         ;
  839                 else
  840                         error = EAFNOSUPPORT;
  841                 break;
  842 
  843         default:
  844                 error = EINVAL;
  845                 break;
  846         }
  847 
  848         return error;
  849 }

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