Expand PMF_FN_* macros.

[netbsd-mini2440.git] / sys / net / if_stf.c

/*      $NetBSD: if_stf.c,v 1.72 2009/04/18 14:58:05 tsutsui 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 1.72 2009/04/18 14:58:05 tsutsui 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 (memcmp(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;

                memcpy(&in, GET_V4(&sin6->sin6_addr), 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));
        memcpy(&ip->ip_dst, in4, 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++;
        ifp->if_obytes += m->m_pkthdr.len - sizeof(struct ip);
        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 SIOCINITIFADDR:
                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:
                error = kauth_authorize_network(l->l_cred,
                    KAUTH_NETWORK_INTERFACE,
                    KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp, KAUTH_ARG(cmd),
                    NULL);
                if (error)
                        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 = ifioctl_common(ifp, cmd, data);
                break;
        }

        return error;
}