FreeBSD/Linux Kernel Cross Reference
sys/net/if_stf.c

     /*      $NetBSD: if_stf.c,v 1.67 2008/10/24 17:07:33 dyoung Exp $       */
     /*      $KAME: if_stf.c,v 1.62 2001/06/07 22:32:16 itojun Exp $ */
     
     /*
      * Copyright (C) 2000 WIDE Project.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the project nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /*
     * 6to4 interface, based on RFC3056.
     *
     * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
     * There is no address mapping defined from IPv6 multicast address to IPv4
     * address.  Therefore, we do not have IFF_MULTICAST on the interface.
     *
     * Due to the lack of address mapping for link-local addresses, we cannot
     * throw packets toward link-local addresses (fe80::x).  Also, we cannot throw
     * packets to link-local multicast addresses (ff02::x).
     *
     * Here are interesting symptoms due to the lack of link-local address:
     *
     * Unicast routing exchange:
     * - RIPng: Impossible.  Uses link-local multicast packet toward ff02::9,
     *   and link-local addresses as nexthop.
     * - OSPFv6: Impossible.  OSPFv6 assumes that there's link-local address
     *   assigned to the link, and makes use of them.  Also, HELLO packets use
     *   link-local multicast addresses (ff02::5 and ff02::6).
     * - BGP4+: Maybe.  You can only use global address as nexthop, and global
     *   address as TCP endpoint address.
     *
     * Multicast routing protocols:
     * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
     *   Adjacent PIM routers must be configured manually (is it really spec-wise
     *   correct thing to do?).
     *
     * ICMPv6:
     * - Redirects cannot be used due to the lack of link-local address.
     *
     * stf interface does not have, and will not need, a link-local address.
     * It seems to have no real benefit and does not help the above symptoms much.
     * Even if we assign link-locals to interface, we cannot really
     * use link-local unicast/multicast on top of 6to4 cloud (since there's no
     * encapsulation defined for link-local address), and the above analysis does
     * not change.  RFC3056 does not mandate the assignment of link-local address
     * either.
     *
     * 6to4 interface has security issues.  Refer to
     * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
     * for details.  The code tries to filter out some of malicious packets.
     * Note that there is no way to be 100% secure.
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: if_stf.c,v 1.67 2008/10/24 17:07:33 dyoung Exp $");
    
    #include "opt_inet.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/socket.h>
    #include <sys/sockio.h>
    #include <sys/mbuf.h>
    #include <sys/errno.h>
    #include <sys/ioctl.h>
    #include <sys/proc.h>
    #include <sys/protosw.h>
    #include <sys/queue.h>
    #include <sys/syslog.h>
    #include <sys/kauth.h>
    
    #include <sys/cpu.h>
    
    #include <net/if.h>
    #include <net/route.h>
    #include <net/netisr.h>
   #include <net/if_types.h>
   #include <net/if_stf.h>
   
   #include <netinet/in.h>
   #include <netinet/in_systm.h>
   #include <netinet/ip.h>
   #include <netinet/ip_var.h>
   #include <netinet/in_var.h>
   
   #include <netinet/ip6.h>
   #include <netinet6/ip6_var.h>
   #include <netinet6/in6_gif.h>
   #include <netinet6/in6_var.h>
   #include <netinet/ip_ecn.h>
   
   #include <netinet/ip_encap.h>
   
   #include <machine/stdarg.h>
   
   #include <net/net_osdep.h>
   
   #include "bpfilter.h"
   #include "stf.h"
   #include "gif.h"        /*XXX*/
   
   #if NBPFILTER > 0
   #include <net/bpf.h>
   #endif
   
   #if NGIF > 0
   #include <net/if_gif.h>
   #endif
   
   #define IN6_IS_ADDR_6TO4(x)     (ntohs((x)->s6_addr16[0]) == 0x2002)
   #define GET_V4(x)       ((const struct in_addr *)(&(x)->s6_addr16[1]))
   
   struct stf_softc {
           struct ifnet    sc_if;     /* common area */
           struct route    sc_ro;
           const struct encaptab *encap_cookie;
           LIST_ENTRY(stf_softc) sc_list;
   };
   
   static LIST_HEAD(, stf_softc) stf_softc_list;
   
   static int      stf_clone_create(struct if_clone *, int);
   static int      stf_clone_destroy(struct ifnet *);
   
   struct if_clone stf_cloner =
       IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
   
   #if NGIF > 0
   extern int ip_gif_ttl;  /*XXX*/
   #else
   static int ip_gif_ttl = 40;     /*XXX*/
   #endif
   
   extern struct domain inetdomain;
   static const struct protosw in_stf_protosw =
   { SOCK_RAW,     &inetdomain,    IPPROTO_IPV6,   PR_ATOMIC|PR_ADDR,
     in_stf_input, rip_output,     0,              rip_ctloutput,
     rip_usrreq,
     0,            0,              0,              0
   };
   
   void    stfattach(int);
   
   static int stf_encapcheck(struct mbuf *, int, int, void *);
   static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
   static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
           struct rtentry *);
   static int isrfc1918addr(const struct in_addr *);
   static int stf_checkaddr4(struct stf_softc *, const struct in_addr *,
           struct ifnet *);
   static int stf_checkaddr6(struct stf_softc *, const struct in6_addr *,
           struct ifnet *);
   static void stf_rtrequest(int, struct rtentry *, const struct rt_addrinfo *);
   static int stf_ioctl(struct ifnet *, u_long, void *);
   
   /* ARGSUSED */
   void
   stfattach(int count)
   {
   
           LIST_INIT(&stf_softc_list);
           if_clone_attach(&stf_cloner);
   }
   
   static int
   stf_clone_create(struct if_clone *ifc, int unit)
   {
           struct stf_softc *sc;
   
           if (LIST_FIRST(&stf_softc_list) != NULL) {
                   /* Only one stf interface is allowed. */
                   return (EEXIST);
           }
   
           sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT|M_ZERO);
   
           if_initname(&sc->sc_if, ifc->ifc_name, unit);
   
           sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
               stf_encapcheck, &in_stf_protosw, sc);
           if (sc->encap_cookie == NULL) {
                   printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
                   free(sc, M_DEVBUF);
                   return (EIO);   /* XXX */
           }
   
           sc->sc_if.if_mtu    = STF_MTU;
           sc->sc_if.if_flags  = 0;
           sc->sc_if.if_ioctl  = stf_ioctl;
           sc->sc_if.if_output = stf_output;
           sc->sc_if.if_type   = IFT_STF;
           sc->sc_if.if_dlt    = DLT_NULL;
           if_attach(&sc->sc_if);
           if_alloc_sadl(&sc->sc_if);
   #if NBPFILTER > 0
           bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
   #endif
           LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
           return (0);
   }
   
   static int
   stf_clone_destroy(struct ifnet *ifp)
   {
           struct stf_softc *sc = (void *) ifp;
   
           LIST_REMOVE(sc, sc_list);
           encap_detach(sc->encap_cookie);
   #if NBPFILTER > 0
           bpfdetach(ifp);
   #endif
           if_detach(ifp);
           rtcache_free(&sc->sc_ro);
           free(sc, M_DEVBUF);
   
           return (0);
   }
   
   static int
   stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
   {
           struct ip ip;
           struct in6_ifaddr *ia6;
           struct stf_softc *sc;
           struct in_addr a, b;
   
           sc = (struct stf_softc *)arg;
           if (sc == NULL)
                   return 0;
   
           if ((sc->sc_if.if_flags & IFF_UP) == 0)
                   return 0;
   
           /* IFF_LINK0 means "no decapsulation" */
           if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
                   return 0;
   
           if (proto != IPPROTO_IPV6)
                   return 0;
   
           m_copydata(m, 0, sizeof(ip), (void *)&ip);
   
           if (ip.ip_v != 4)
                   return 0;
   
           ia6 = stf_getsrcifa6(&sc->sc_if);
           if (ia6 == NULL)
                   return 0;
   
           /*
            * check if IPv4 dst matches the IPv4 address derived from the
            * local 6to4 address.
            * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
            */
           if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
               sizeof(ip.ip_dst)) != 0)
                   return 0;
   
           /*
            * check if IPv4 src matches the IPv4 address derived from the
            * local 6to4 address masked by prefixmask.
            * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
            * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
            */
           memset(&a, 0, sizeof(a));
           a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
           a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
           b = ip.ip_src;
           b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
           if (a.s_addr != b.s_addr)
                   return 0;
   
           /* stf interface makes single side match only */
           return 32;
   }
   
   static struct in6_ifaddr *
   stf_getsrcifa6(struct ifnet *ifp)
   {
           struct ifaddr *ifa;
           struct in_ifaddr *ia4;
           struct sockaddr_in6 *sin6;
           struct in_addr in;
   
           IFADDR_FOREACH(ifa, ifp)
           {
                   if (ifa->ifa_addr == NULL)
                           continue;
                   if (ifa->ifa_addr->sa_family != AF_INET6)
                           continue;
                   sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
                   if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
                           continue;
   
                   bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
                   INADDR_TO_IA(in, ia4);
                   if (ia4 == NULL)
                           continue;
   
                   return (struct in6_ifaddr *)ifa;
           }
   
           return NULL;
   }
   
   static int
   stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
       struct rtentry *rt0)
   {
           struct rtentry *rt;
           struct stf_softc *sc;
           const struct sockaddr_in6 *dst6;
           const struct in_addr *in4;
           uint8_t tos;
           struct ip *ip;
           struct ip6_hdr *ip6;
           struct in6_ifaddr *ia6;
           union {
                   struct sockaddr         dst;
                   struct sockaddr_in      dst4;
           } u;
   
           sc = (struct stf_softc*)ifp;
           dst6 = (const struct sockaddr_in6 *)dst;
   
           /* just in case */
           if ((ifp->if_flags & IFF_UP) == 0) {
                   m_freem(m);
                   return ENETDOWN;
           }
   
           /*
            * If we don't have an ip4 address that match my inner ip6 address,
            * we shouldn't generate output.  Without this check, we'll end up
            * using wrong IPv4 source.
            */
           ia6 = stf_getsrcifa6(ifp);
           if (ia6 == NULL) {
                   m_freem(m);
                   ifp->if_oerrors++;
                   return ENETDOWN;
           }
   
           if (m->m_len < sizeof(*ip6)) {
                   m = m_pullup(m, sizeof(*ip6));
                   if (m == NULL) {
                           ifp->if_oerrors++;
                           return ENOBUFS;
                   }
           }
           ip6 = mtod(m, struct ip6_hdr *);
           tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
   
           /*
            * Pickup the right outer dst addr from the list of candidates.
            * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
            */
           if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
                   in4 = GET_V4(&ip6->ip6_dst);
           else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
                   in4 = GET_V4(&dst6->sin6_addr);
           else {
                   m_freem(m);
                   ifp->if_oerrors++;
                   return ENETUNREACH;
           }
   
   #if NBPFILTER > 0
           if (ifp->if_bpf)
                   bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
   #endif /*NBPFILTER > 0*/
   
           M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
           if (m && m->m_len < sizeof(struct ip))
                   m = m_pullup(m, sizeof(struct ip));
           if (m == NULL) {
                   ifp->if_oerrors++;
                   return ENOBUFS;
           }
           ip = mtod(m, struct ip *);
   
           memset(ip, 0, sizeof(*ip));
   
           bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
               &ip->ip_src, sizeof(ip->ip_src));
           bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
           ip->ip_p = IPPROTO_IPV6;
           ip->ip_ttl = ip_gif_ttl;        /*XXX*/
           ip->ip_len = htons(m->m_pkthdr.len);
           if (ifp->if_flags & IFF_LINK1)
                   ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
           else
                   ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
   
           sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
           if ((rt = rtcache_lookup(&sc->sc_ro, &u.dst)) == NULL) {
                   m_freem(m);
                   ifp->if_oerrors++;
                   return ENETUNREACH;
           }
   
           /* If the route constitutes infinite encapsulation, punt. */
           if (rt->rt_ifp == ifp) {
                   rtcache_free(&sc->sc_ro);
                   m_freem(m);
                   ifp->if_oerrors++;
                   return ENETUNREACH;
           }
   
           ifp->if_opackets++;
           return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
   }
   
   static int
   isrfc1918addr(const struct in_addr *in)
   {
           /*
            * returns 1 if private address range:
            * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
            */
           if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
               (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
               (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
                   return 1;
   
           return 0;
   }
   
   static int
   stf_checkaddr4(struct stf_softc *sc, const struct in_addr *in,
       struct ifnet *inifp /*incoming interface*/)
   {
           struct in_ifaddr *ia4;
   
           /*
            * reject packets with the following address:
            * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
            */
           if (IN_MULTICAST(in->s_addr))
                   return -1;
           switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
           case 0: case 127: case 255:
                   return -1;
           }
   
           /*
            * reject packets with private address range.
            * (requirement from RFC3056 section 2 1st paragraph)
            */
           if (isrfc1918addr(in))
                   return -1;
   
           /*
            * reject packet with IPv4 link-local (169.254.0.0/16),
            * as suggested in draft-savola-v6ops-6to4-security-00.txt
            */
           if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
               ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
                   return -1;
   
           /*
            * reject packets with broadcast
            */
           TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
           {
                   if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
                           continue;
                   if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
                           return -1;
           }
   
           /*
            * perform ingress filter
            */
           if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
                   struct sockaddr_in sin;
                   struct rtentry *rt;
   
                   memset(&sin, 0, sizeof(sin));
                   sin.sin_family = AF_INET;
                   sin.sin_len = sizeof(struct sockaddr_in);
                   sin.sin_addr = *in;
                   rt = rtalloc1((struct sockaddr *)&sin, 0);
                   if (!rt || rt->rt_ifp != inifp) {
   #if 0
                           log(LOG_WARNING, "%s: packet from 0x%x dropped "
                               "due to ingress filter\n", if_name(&sc->sc_if),
                               (uint32_t)ntohl(sin.sin_addr.s_addr));
   #endif
                           if (rt)
                                   rtfree(rt);
                           return -1;
                   }
                   rtfree(rt);
           }
   
           return 0;
   }
   
   static int
   stf_checkaddr6(struct stf_softc *sc, const struct in6_addr *in6,
       struct ifnet *inifp /*incoming interface*/)
   {
   
           /*
            * check 6to4 addresses
            */
           if (IN6_IS_ADDR_6TO4(in6))
                   return stf_checkaddr4(sc, GET_V4(in6), inifp);
   
           /*
            * reject anything that look suspicious.  the test is implemented
            * in ip6_input too, but we check here as well to
            * (1) reject bad packets earlier, and
            * (2) to be safe against future ip6_input change.
            */
           if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
                   return -1;
   
           /*
            * reject link-local and site-local unicast
            * as suggested in draft-savola-v6ops-6to4-security-00.txt
            */
           if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
                   return -1;
   
           /*
            * reject node-local and link-local multicast
            * as suggested in draft-savola-v6ops-6to4-security-00.txt
            */
           if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
                   return -1;
   
           return 0;
   }
   
   void
   in_stf_input(struct mbuf *m, ...)
   {
           int off, proto;
           struct stf_softc *sc;
           struct ip *ip;
           struct ip6_hdr *ip6;
           uint8_t otos, itos;
           int s, isr;
           struct ifqueue *ifq = NULL;
           struct ifnet *ifp;
           va_list ap;
   
           va_start(ap, m);
           off = va_arg(ap, int);
           proto = va_arg(ap, int);
           va_end(ap);
   
           if (proto != IPPROTO_IPV6) {
                   m_freem(m);
                   return;
           }
   
           ip = mtod(m, struct ip *);
   
           sc = (struct stf_softc *)encap_getarg(m);
   
           if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
                   m_freem(m);
                   return;
           }
   
           ifp = &sc->sc_if;
   
           /*
            * perform sanity check against outer src/dst.
            * for source, perform ingress filter as well.
            */
           if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
               stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
                   m_freem(m);
                   return;
           }
   
           otos = ip->ip_tos;
           m_adj(m, off);
   
           if (m->m_len < sizeof(*ip6)) {
                   m = m_pullup(m, sizeof(*ip6));
                   if (!m)
                           return;
           }
           ip6 = mtod(m, struct ip6_hdr *);
   
           /*
            * perform sanity check against inner src/dst.
            * for source, perform ingress filter as well.
            */
           if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
               stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
                   m_freem(m);
                   return;
           }
   
           itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
           if ((ifp->if_flags & IFF_LINK1) != 0)
                   ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
           else
                   ip_ecn_egress(ECN_NOCARE, &otos, &itos);
           ip6->ip6_flow &= ~htonl(0xff << 20);
           ip6->ip6_flow |= htonl((uint32_t)itos << 20);
   
           m->m_pkthdr.rcvif = ifp;
   
   #if NBPFILTER > 0
           if (ifp->if_bpf)
                   bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
   #endif /*NBPFILTER > 0*/
   
           /*
            * Put the packet to the network layer input queue according to the
            * specified address family.
            * See net/if_gif.c for possible issues with packet processing
            * reorder due to extra queueing.
            */
           ifq = &ip6intrq;
           isr = NETISR_IPV6;
   
           s = splnet();
           if (IF_QFULL(ifq)) {
                   IF_DROP(ifq);   /* update statistics */
                   m_freem(m);
                   splx(s);
                   return;
           }
           IF_ENQUEUE(ifq, m);
           schednetisr(isr);
           ifp->if_ipackets++;
           ifp->if_ibytes += m->m_pkthdr.len;
           splx(s);
   }
   
   /* ARGSUSED */
   static void
   stf_rtrequest(int cmd, struct rtentry *rt,
       const struct rt_addrinfo *info)
   {
           if (rt != NULL) {
                   struct stf_softc *sc;
   
                   sc = LIST_FIRST(&stf_softc_list);
                   rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
           }
   }
   
   static int
   stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
   {
           struct lwp              *l = curlwp;    /* XXX */
           struct ifaddr           *ifa;
           struct ifreq            *ifr = data;
           struct sockaddr_in6     *sin6;
           int                     error;
   
           error = 0;
           switch (cmd) {
           case SIOCSIFADDR:
                   ifa = (struct ifaddr *)data;
                   if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
                           error = EAFNOSUPPORT;
                           break;
                   }
                   sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
                   if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
                       !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
                           ifa->ifa_rtrequest = stf_rtrequest;
                           ifp->if_flags |= IFF_UP;
                   } else
                           error = EINVAL;
                   break;
   
           case SIOCADDMULTI:
           case SIOCDELMULTI:
                   if (ifr != NULL &&
                       ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
                           ;
                   else
                           error = EAFNOSUPPORT;
                   break;
   
           case SIOCSIFMTU:
                   if ((error = kauth_authorize_generic(l->l_cred,
                       KAUTH_GENERIC_ISSUSER, NULL)) != 0)
                           break;
                   if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
                           return EINVAL;
                   else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
                           error = 0;
                   break;
   
           default:
                   error = EINVAL;
                   break;
           }
   
           return error;
   }

Cache object: 3ed38e0f0c78bdca23d1b7d82f18065e