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: releng/11.1/sys/net/if_stf.c 292331 2015-12-16 09:18:20Z melifaro $   */
    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 <sys/param.h>
   78 #include <sys/systm.h>
   79 #include <sys/socket.h>
   80 #include <sys/sockio.h>
   81 #include <sys/mbuf.h>
   82 #include <sys/errno.h>
   83 #include <sys/kernel.h>
   84 #include <sys/lock.h>
   85 #include <sys/module.h>
   86 #include <sys/protosw.h>
   87 #include <sys/proc.h>
   88 #include <sys/queue.h>
   89 #include <sys/rmlock.h>
   90 #include <sys/sysctl.h>
   91 #include <machine/cpu.h>
   92 
   93 #include <sys/malloc.h>
   94 
   95 #include <net/if.h>
   96 #include <net/if_var.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/vnet.h>
  102 
  103 #include <netinet/in.h>
  104 #include <netinet/in_fib.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 static SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface");
  125 
  126 static int stf_permit_rfc1918 = 0;
  127 SYSCTL_INT(_net_link_stf, OID_AUTO, permit_rfc1918, CTLFLAG_RWTUN,
  128     &stf_permit_rfc1918, 0, "Permit the use of private IPv4 addresses");
  129 
  130 #define STFUNIT         0
  131 
  132 #define IN6_IS_ADDR_6TO4(x)     (ntohs((x)->s6_addr16[0]) == 0x2002)
  133 
  134 /*
  135  * XXX: Return a pointer with 16-bit aligned.  Don't cast it to
  136  * struct in_addr *; use bcopy() instead.
  137  */
  138 #define GET_V4(x)       (&(x)->s6_addr16[1])
  139 
  140 struct stf_softc {
  141         struct ifnet    *sc_ifp;
  142         struct mtx      sc_ro_mtx;
  143         u_int   sc_fibnum;
  144         const struct encaptab *encap_cookie;
  145 };
  146 #define STF2IFP(sc)     ((sc)->sc_ifp)
  147 
  148 static const char stfname[] = "stf";
  149 
  150 /*
  151  * Note that mutable fields in the softc are not currently locked.
  152  * We do lock sc_ro in stf_output though.
  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 static int in_stf_input(struct mbuf **, int *, int);
  159 static struct protosw in_stf_protosw = {
  160         .pr_type =              SOCK_RAW,
  161         .pr_domain =            &inetdomain,
  162         .pr_protocol =          IPPROTO_IPV6,
  163         .pr_flags =             PR_ATOMIC|PR_ADDR,
  164         .pr_input =             in_stf_input,
  165         .pr_output =            rip_output,
  166         .pr_ctloutput =         rip_ctloutput,
  167         .pr_usrreqs =           &rip_usrreqs
  168 };
  169 
  170 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
  171 
  172 static int stfmodevent(module_t, int, void *);
  173 static int stf_encapcheck(const struct mbuf *, int, int, void *);
  174 static int stf_getsrcifa6(struct ifnet *, struct in6_addr *, struct in6_addr *);
  175 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
  176         struct route *);
  177 static int isrfc1918addr(struct in_addr *);
  178 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
  179         struct ifnet *);
  180 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
  181         struct ifnet *);
  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, caddr_t);
  186 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
  187 static struct if_clone *stf_cloner;
  188 
  189 static int
  190 stf_clone_match(struct if_clone *ifc, const char *name)
  191 {
  192         int i;
  193 
  194         for(i = 0; stfnames[i] != NULL; i++) {
  195                 if (strcmp(stfnames[i], name) == 0)
  196                         return (1);
  197         }
  198 
  199         return (0);
  200 }
  201 
  202 static int
  203 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
  204 {
  205         int err, unit;
  206         struct stf_softc *sc;
  207         struct ifnet *ifp;
  208 
  209         /*
  210          * We can only have one unit, but since unit allocation is
  211          * already locked, we use it to keep from allocating extra
  212          * interfaces.
  213          */
  214         unit = STFUNIT;
  215         err = ifc_alloc_unit(ifc, &unit);
  216         if (err != 0)
  217                 return (err);
  218 
  219         sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
  220         ifp = STF2IFP(sc) = if_alloc(IFT_STF);
  221         if (ifp == NULL) {
  222                 free(sc, M_STF);
  223                 ifc_free_unit(ifc, unit);
  224                 return (ENOSPC);
  225         }
  226         ifp->if_softc = sc;
  227         sc->sc_fibnum = curthread->td_proc->p_fibnum;
  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 = stfname;
  235         ifp->if_dunit = IF_DUNIT_NONE;
  236 
  237         mtx_init(&(sc)->sc_ro_mtx, "stf ro", NULL, MTX_DEF);
  238         sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
  239             stf_encapcheck, &in_stf_protosw, sc);
  240         if (sc->encap_cookie == NULL) {
  241                 if_printf(ifp, "attach failed\n");
  242                 free(sc, M_STF);
  243                 ifc_free_unit(ifc, unit);
  244                 return (ENOMEM);
  245         }
  246 
  247         ifp->if_mtu    = IPV6_MMTU;
  248         ifp->if_ioctl  = stf_ioctl;
  249         ifp->if_output = stf_output;
  250         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  251         if_attach(ifp);
  252         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  253         return (0);
  254 }
  255 
  256 static int
  257 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
  258 {
  259         struct stf_softc *sc = ifp->if_softc;
  260         int err;
  261 
  262         err = encap_detach(sc->encap_cookie);
  263         KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
  264         mtx_destroy(&(sc)->sc_ro_mtx);
  265         bpfdetach(ifp);
  266         if_detach(ifp);
  267         if_free(ifp);
  268 
  269         free(sc, M_STF);
  270         ifc_free_unit(ifc, STFUNIT);
  271 
  272         return (0);
  273 }
  274 
  275 static int
  276 stfmodevent(module_t mod, int type, void *data)
  277 {
  278 
  279         switch (type) {
  280         case MOD_LOAD:
  281                 stf_cloner = if_clone_advanced(stfname, 0, stf_clone_match,
  282                     stf_clone_create, stf_clone_destroy);
  283                 break;
  284         case MOD_UNLOAD:
  285                 if_clone_detach(stf_cloner);
  286                 break;
  287         default:
  288                 return (EOPNOTSUPP);
  289         }
  290 
  291         return (0);
  292 }
  293 
  294 static moduledata_t stf_mod = {
  295         "if_stf",
  296         stfmodevent,
  297         0
  298 };
  299 
  300 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  301 
  302 static int
  303 stf_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
  304 {
  305         struct ip ip;
  306         struct stf_softc *sc;
  307         struct in_addr a, b, mask;
  308         struct in6_addr addr6, mask6;
  309 
  310         sc = (struct stf_softc *)arg;
  311         if (sc == NULL)
  312                 return 0;
  313 
  314         if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
  315                 return 0;
  316 
  317         /* IFF_LINK0 means "no decapsulation" */
  318         if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
  319                 return 0;
  320 
  321         if (proto != IPPROTO_IPV6)
  322                 return 0;
  323 
  324         /* LINTED const cast */
  325         m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
  326 
  327         if (ip.ip_v != 4)
  328                 return 0;
  329 
  330         if (stf_getsrcifa6(STF2IFP(sc), &addr6, &mask6) != 0)
  331                 return (0);
  332 
  333         /*
  334          * check if IPv4 dst matches the IPv4 address derived from the
  335          * local 6to4 address.
  336          * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
  337          */
  338         if (bcmp(GET_V4(&addr6), &ip.ip_dst, sizeof(ip.ip_dst)) != 0)
  339                 return 0;
  340 
  341         /*
  342          * check if IPv4 src matches the IPv4 address derived from the
  343          * local 6to4 address masked by prefixmask.
  344          * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
  345          * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
  346          */
  347         bzero(&a, sizeof(a));
  348         bcopy(GET_V4(&addr6), &a, sizeof(a));
  349         bcopy(GET_V4(&mask6), &mask, sizeof(mask));
  350         a.s_addr &= mask.s_addr;
  351         b = ip.ip_src;
  352         b.s_addr &= mask.s_addr;
  353         if (a.s_addr != b.s_addr)
  354                 return 0;
  355 
  356         /* stf interface makes single side match only */
  357         return 32;
  358 }
  359 
  360 static int
  361 stf_getsrcifa6(struct ifnet *ifp, struct in6_addr *addr, struct in6_addr *mask)
  362 {
  363         struct ifaddr *ia;
  364         struct in_ifaddr *ia4;
  365         struct in6_ifaddr *ia6;
  366         struct sockaddr_in6 *sin6;
  367         struct in_addr in;
  368 
  369         if_addr_rlock(ifp);
  370         TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
  371                 if (ia->ifa_addr->sa_family != AF_INET6)
  372                         continue;
  373                 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
  374                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
  375                         continue;
  376 
  377                 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
  378                 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
  379                         if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
  380                                 break;
  381                 if (ia4 == NULL)
  382                         continue;
  383 
  384                 ia6 = (struct in6_ifaddr *)ia;
  385 
  386                 *addr = sin6->sin6_addr;
  387                 *mask = ia6->ia_prefixmask.sin6_addr;
  388                 if_addr_runlock(ifp);
  389                 return (0);
  390         }
  391         if_addr_runlock(ifp);
  392 
  393         return (ENOENT);
  394 }
  395 
  396 static int
  397 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
  398     struct route *ro)
  399 {
  400         struct stf_softc *sc;
  401         const struct sockaddr_in6 *dst6;
  402         struct in_addr in4;
  403         const void *ptr;
  404         u_int8_t tos;
  405         struct ip *ip;
  406         struct ip6_hdr *ip6;
  407         struct in6_addr addr6, mask6;
  408         int error;
  409 
  410 #ifdef MAC
  411         error = mac_ifnet_check_transmit(ifp, m);
  412         if (error) {
  413                 m_freem(m);
  414                 return (error);
  415         }
  416 #endif
  417 
  418         sc = ifp->if_softc;
  419         dst6 = (const struct sockaddr_in6 *)dst;
  420 
  421         /* just in case */
  422         if ((ifp->if_flags & IFF_UP) == 0) {
  423                 m_freem(m);
  424                 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
  425                 return ENETDOWN;
  426         }
  427 
  428         /*
  429          * If we don't have an ip4 address that match my inner ip6 address,
  430          * we shouldn't generate output.  Without this check, we'll end up
  431          * using wrong IPv4 source.
  432          */
  433         if (stf_getsrcifa6(ifp, &addr6, &mask6) != 0) {
  434                 m_freem(m);
  435                 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
  436                 return ENETDOWN;
  437         }
  438 
  439         if (m->m_len < sizeof(*ip6)) {
  440                 m = m_pullup(m, sizeof(*ip6));
  441                 if (!m) {
  442                         if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
  443                         return ENOBUFS;
  444                 }
  445         }
  446         ip6 = mtod(m, struct ip6_hdr *);
  447         tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  448 
  449         /*
  450          * Pickup the right outer dst addr from the list of candidates.
  451          * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
  452          */
  453         ptr = NULL;
  454         if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
  455                 ptr = GET_V4(&ip6->ip6_dst);
  456         else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
  457                 ptr = GET_V4(&dst6->sin6_addr);
  458         else {
  459                 m_freem(m);
  460                 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
  461                 return ENETUNREACH;
  462         }
  463         bcopy(ptr, &in4, sizeof(in4));
  464 
  465         if (bpf_peers_present(ifp->if_bpf)) {
  466                 /*
  467                  * We need to prepend the address family as
  468                  * a four byte field.  Cons up a dummy header
  469                  * to pacify bpf.  This is safe because bpf
  470                  * will only read from the mbuf (i.e., it won't
  471                  * try to free it or keep a pointer a to it).
  472                  */
  473                 u_int af = AF_INET6;
  474                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  475         }
  476 
  477         M_PREPEND(m, sizeof(struct ip), M_NOWAIT);
  478         if (m == NULL) {
  479                 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
  480                 return ENOBUFS;
  481         }
  482         ip = mtod(m, struct ip *);
  483 
  484         bzero(ip, sizeof(*ip));
  485 
  486         bcopy(GET_V4(&addr6), &ip->ip_src, sizeof(ip->ip_src));
  487         bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
  488         ip->ip_p = IPPROTO_IPV6;
  489         ip->ip_ttl = ip_stf_ttl;
  490         ip->ip_len = htons(m->m_pkthdr.len);
  491         if (ifp->if_flags & IFF_LINK1)
  492                 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
  493         else
  494                 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
  495 
  496         M_SETFIB(m, sc->sc_fibnum);
  497         if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
  498         error = ip_output(m, NULL, NULL, 0, NULL, NULL);
  499 
  500         return error;
  501 }
  502 
  503 static int
  504 isrfc1918addr(struct in_addr *in)
  505 {
  506         /*
  507          * returns 1 if private address range:
  508          * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
  509          */
  510         if (stf_permit_rfc1918 == 0 && (
  511             (ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
  512             (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
  513             (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168))
  514                 return 1;
  515 
  516         return 0;
  517 }
  518 
  519 static int
  520 stf_checkaddr4(struct stf_softc *sc, struct in_addr *in, struct ifnet *inifp)
  521 {
  522         struct rm_priotracker in_ifa_tracker;
  523         struct in_ifaddr *ia4;
  524 
  525         /*
  526          * reject packets with the following address:
  527          * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
  528          */
  529         if (IN_MULTICAST(ntohl(in->s_addr)))
  530                 return -1;
  531         switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
  532         case 0: case 127: case 255:
  533                 return -1;
  534         }
  535 
  536         /*
  537          * reject packets with private address range.
  538          * (requirement from RFC3056 section 2 1st paragraph)
  539          */
  540         if (isrfc1918addr(in))
  541                 return -1;
  542 
  543         /*
  544          * reject packets with broadcast
  545          */
  546         IN_IFADDR_RLOCK(&in_ifa_tracker);
  547         TAILQ_FOREACH(ia4, &V_in_ifaddrhead, ia_link) {
  548                 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
  549                         continue;
  550                 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
  551                         IN_IFADDR_RUNLOCK(&in_ifa_tracker);
  552                         return -1;
  553                 }
  554         }
  555         IN_IFADDR_RUNLOCK(&in_ifa_tracker);
  556 
  557         /*
  558          * perform ingress filter
  559          */
  560         if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
  561                 struct nhop4_basic nh4;
  562 
  563                 if (fib4_lookup_nh_basic(sc->sc_fibnum, *in, 0, 0, &nh4) != 0)
  564                         return (-1);
  565 
  566                 if (nh4.nh_ifp != inifp)
  567                         return (-1);
  568         }
  569 
  570         return 0;
  571 }
  572 
  573 static int
  574 stf_checkaddr6(struct stf_softc *sc, struct in6_addr *in6, struct ifnet *inifp)
  575 {
  576         /*
  577          * check 6to4 addresses
  578          */
  579         if (IN6_IS_ADDR_6TO4(in6)) {
  580                 struct in_addr in4;
  581                 bcopy(GET_V4(in6), &in4, sizeof(in4));
  582                 return stf_checkaddr4(sc, &in4, inifp);
  583         }
  584 
  585         /*
  586          * reject anything that look suspicious.  the test is implemented
  587          * in ip6_input too, but we check here as well to
  588          * (1) reject bad packets earlier, and
  589          * (2) to be safe against future ip6_input change.
  590          */
  591         if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
  592                 return -1;
  593 
  594         return 0;
  595 }
  596 
  597 static int
  598 in_stf_input(struct mbuf **mp, int *offp, int proto)
  599 {
  600         struct stf_softc *sc;
  601         struct ip *ip;
  602         struct ip6_hdr *ip6;
  603         struct mbuf *m;
  604         u_int8_t otos, itos;
  605         struct ifnet *ifp;
  606         int off;
  607 
  608         m = *mp;
  609         off = *offp;
  610 
  611         if (proto != IPPROTO_IPV6) {
  612                 m_freem(m);
  613                 return (IPPROTO_DONE);
  614         }
  615 
  616         ip = mtod(m, struct ip *);
  617 
  618         sc = (struct stf_softc *)encap_getarg(m);
  619 
  620         if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
  621                 m_freem(m);
  622                 return (IPPROTO_DONE);
  623         }
  624 
  625         ifp = STF2IFP(sc);
  626 
  627 #ifdef MAC
  628         mac_ifnet_create_mbuf(ifp, m);
  629 #endif
  630 
  631         /*
  632          * perform sanity check against outer src/dst.
  633          * for source, perform ingress filter as well.
  634          */
  635         if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
  636             stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
  637                 m_freem(m);
  638                 return (IPPROTO_DONE);
  639         }
  640 
  641         otos = ip->ip_tos;
  642         m_adj(m, off);
  643 
  644         if (m->m_len < sizeof(*ip6)) {
  645                 m = m_pullup(m, sizeof(*ip6));
  646                 if (!m)
  647                         return (IPPROTO_DONE);
  648         }
  649         ip6 = mtod(m, struct ip6_hdr *);
  650 
  651         /*
  652          * perform sanity check against inner src/dst.
  653          * for source, perform ingress filter as well.
  654          */
  655         if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
  656             stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
  657                 m_freem(m);
  658                 return (IPPROTO_DONE);
  659         }
  660 
  661         itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
  662         if ((ifp->if_flags & IFF_LINK1) != 0)
  663                 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
  664         else
  665                 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
  666         ip6->ip6_flow &= ~htonl(0xff << 20);
  667         ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
  668 
  669         m->m_pkthdr.rcvif = ifp;
  670         
  671         if (bpf_peers_present(ifp->if_bpf)) {
  672                 /*
  673                  * We need to prepend the address family as
  674                  * a four byte field.  Cons up a dummy header
  675                  * to pacify bpf.  This is safe because bpf
  676                  * will only read from the mbuf (i.e., it won't
  677                  * try to free it or keep a pointer a to it).
  678                  */
  679                 u_int32_t af = AF_INET6;
  680                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
  681         }
  682 
  683         /*
  684          * Put the packet to the network layer input queue according to the
  685          * specified address family.
  686          * See net/if_gif.c for possible issues with packet processing
  687          * reorder due to extra queueing.
  688          */
  689         if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
  690         if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
  691         M_SETFIB(m, ifp->if_fib);
  692         netisr_dispatch(NETISR_IPV6, m);
  693         return (IPPROTO_DONE);
  694 }
  695 
  696 static int
  697 stf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
  698 {
  699         struct ifaddr *ifa;
  700         struct ifreq *ifr;
  701         struct sockaddr_in6 *sin6;
  702         struct in_addr addr;
  703         int error, mtu;
  704 
  705         error = 0;
  706         switch (cmd) {
  707         case SIOCSIFADDR:
  708                 ifa = (struct ifaddr *)data;
  709                 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
  710                         error = EAFNOSUPPORT;
  711                         break;
  712                 }
  713                 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
  714                 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
  715                         error = EINVAL;
  716                         break;
  717                 }
  718                 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
  719                 if (isrfc1918addr(&addr)) {
  720                         error = EINVAL;
  721                         break;
  722                 }
  723 
  724                 ifp->if_flags |= IFF_UP;
  725                 break;
  726 
  727         case SIOCADDMULTI:
  728         case SIOCDELMULTI:
  729                 ifr = (struct ifreq *)data;
  730                 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
  731                         ;
  732                 else
  733                         error = EAFNOSUPPORT;
  734                 break;
  735 
  736         case SIOCGIFMTU:
  737                 break;
  738 
  739         case SIOCSIFMTU:
  740                 ifr = (struct ifreq *)data;
  741                 mtu = ifr->ifr_mtu;
  742                 /* RFC 4213 3.2 ideal world MTU */
  743                 if (mtu < IPV6_MINMTU || mtu > IF_MAXMTU - 20)
  744                         return (EINVAL);
  745                 ifp->if_mtu = mtu;
  746                 break;
  747 
  748         default:
  749                 error = EINVAL;
  750                 break;
  751         }
  752 
  753         return error;
  754 }

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