1/*	$NetBSD: if_stf.c,v 1.76 2011/07/17 20:54:52 joerg Exp $	*/
2/*	$KAME: if_stf.c,v 1.62 2001/06/07 22:32:16 itojun 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/cdefs.h>
78__KERNEL_RCSID(0, "$NetBSD: if_stf.c,v 1.76 2011/07/17 20:54:52 joerg Exp $");
79
80#include "opt_inet.h"
81
82#include <sys/param.h>
83#include <sys/systm.h>
84#include <sys/socket.h>
85#include <sys/sockio.h>
86#include <sys/mbuf.h>
87#include <sys/errno.h>
88#include <sys/ioctl.h>
89#include <sys/proc.h>
90#include <sys/protosw.h>
91#include <sys/queue.h>
92#include <sys/syslog.h>
93
94#include <sys/cpu.h>
95
96#include <net/if.h>
97#include <net/route.h>
98#include <net/netisr.h>
99#include <net/if_types.h>
100#include <net/if_stf.h>
101
102#include <netinet/in.h>
103#include <netinet/in_systm.h>
104#include <netinet/ip.h>
105#include <netinet/ip_var.h>
106#include <netinet/in_var.h>
107
108#include <netinet/ip6.h>
109#include <netinet6/ip6_var.h>
110#include <netinet6/in6_gif.h>
111#include <netinet6/in6_var.h>
112#include <netinet/ip_ecn.h>
113
114#include <netinet/ip_encap.h>
115
116#include <net/net_osdep.h>
117
118#include "stf.h"
119#include "gif.h"	/*XXX*/
120
121#include <net/bpf.h>
122
123#if NGIF > 0
124#include <net/if_gif.h>
125#endif
126
127#define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
128#define GET_V4(x)	((const struct in_addr *)(&(x)->s6_addr16[1]))
129
130struct stf_softc {
131	struct ifnet	sc_if;	   /* common area */
132	struct route	sc_ro;
133	const struct encaptab *encap_cookie;
134	LIST_ENTRY(stf_softc) sc_list;
135};
136
137static LIST_HEAD(, stf_softc) stf_softc_list;
138
139static int	stf_clone_create(struct if_clone *, int);
140static int	stf_clone_destroy(struct ifnet *);
141
142struct if_clone stf_cloner =
143    IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
144
145#if NGIF > 0
146extern int ip_gif_ttl;	/*XXX*/
147#else
148static int ip_gif_ttl = 40;	/*XXX*/
149#endif
150
151extern struct domain inetdomain;
152static const struct protosw in_stf_protosw =
153{ SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
154  in_stf_input, rip_output,	0,		rip_ctloutput,
155  rip_usrreq,
156  0,            0,              0,              0
157};
158
159void	stfattach(int);
160
161static int stf_encapcheck(struct mbuf *, int, int, void *);
162static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
163static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
164	struct rtentry *);
165static int isrfc1918addr(const struct in_addr *);
166static int stf_checkaddr4(struct stf_softc *, const struct in_addr *,
167	struct ifnet *);
168static int stf_checkaddr6(struct stf_softc *, const struct in6_addr *,
169	struct ifnet *);
170static void stf_rtrequest(int, struct rtentry *, const struct rt_addrinfo *);
171static int stf_ioctl(struct ifnet *, u_long, void *);
172
173/* ARGSUSED */
174void
175stfattach(int count)
176{
177
178	LIST_INIT(&stf_softc_list);
179	if_clone_attach(&stf_cloner);
180}
181
182static int
183stf_clone_create(struct if_clone *ifc, int unit)
184{
185	struct stf_softc *sc;
186
187	if (LIST_FIRST(&stf_softc_list) != NULL) {
188		/* Only one stf interface is allowed. */
189		return (EEXIST);
190	}
191
192	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT|M_ZERO);
193
194	if_initname(&sc->sc_if, ifc->ifc_name, unit);
195
196	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
197	    stf_encapcheck, &in_stf_protosw, sc);
198	if (sc->encap_cookie == NULL) {
199		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
200		free(sc, M_DEVBUF);
201		return (EIO);	/* XXX */
202	}
203
204	sc->sc_if.if_mtu    = STF_MTU;
205	sc->sc_if.if_flags  = 0;
206	sc->sc_if.if_ioctl  = stf_ioctl;
207	sc->sc_if.if_output = stf_output;
208	sc->sc_if.if_type   = IFT_STF;
209	sc->sc_if.if_dlt    = DLT_NULL;
210	if_attach(&sc->sc_if);
211	if_alloc_sadl(&sc->sc_if);
212	bpf_attach(&sc->sc_if, DLT_NULL, sizeof(u_int));
213	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
214	return (0);
215}
216
217static int
218stf_clone_destroy(struct ifnet *ifp)
219{
220	struct stf_softc *sc = (void *) ifp;
221
222	LIST_REMOVE(sc, sc_list);
223	encap_detach(sc->encap_cookie);
224	bpf_detach(ifp);
225	if_detach(ifp);
226	rtcache_free(&sc->sc_ro);
227	free(sc, M_DEVBUF);
228
229	return (0);
230}
231
232static int
233stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
234{
235	struct ip ip;
236	struct in6_ifaddr *ia6;
237	struct stf_softc *sc;
238	struct in_addr a, b;
239
240	sc = (struct stf_softc *)arg;
241	if (sc == NULL)
242		return 0;
243
244	if ((sc->sc_if.if_flags & IFF_UP) == 0)
245		return 0;
246
247	/* IFF_LINK0 means "no decapsulation" */
248	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
249		return 0;
250
251	if (proto != IPPROTO_IPV6)
252		return 0;
253
254	m_copydata(m, 0, sizeof(ip), (void *)&ip);
255
256	if (ip.ip_v != 4)
257		return 0;
258
259	ia6 = stf_getsrcifa6(&sc->sc_if);
260	if (ia6 == NULL)
261		return 0;
262
263	/*
264	 * check if IPv4 dst matches the IPv4 address derived from the
265	 * local 6to4 address.
266	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
267	 */
268	if (memcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
269	    sizeof(ip.ip_dst)) != 0)
270		return 0;
271
272	/*
273	 * check if IPv4 src matches the IPv4 address derived from the
274	 * local 6to4 address masked by prefixmask.
275	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
276	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
277	 */
278	memset(&a, 0, sizeof(a));
279	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
280	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
281	b = ip.ip_src;
282	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
283	if (a.s_addr != b.s_addr)
284		return 0;
285
286	/* stf interface makes single side match only */
287	return 32;
288}
289
290static struct in6_ifaddr *
291stf_getsrcifa6(struct ifnet *ifp)
292{
293	struct ifaddr *ifa;
294	struct in_ifaddr *ia4;
295	struct sockaddr_in6 *sin6;
296	struct in_addr in;
297
298	IFADDR_FOREACH(ifa, ifp)
299	{
300		if (ifa->ifa_addr == NULL)
301			continue;
302		if (ifa->ifa_addr->sa_family != AF_INET6)
303			continue;
304		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
305		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
306			continue;
307
308		memcpy(&in, GET_V4(&sin6->sin6_addr), sizeof(in));
309		INADDR_TO_IA(in, ia4);
310		if (ia4 == NULL)
311			continue;
312
313		return (struct in6_ifaddr *)ifa;
314	}
315
316	return NULL;
317}
318
319static int
320stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
321    struct rtentry *rt0)
322{
323	struct rtentry *rt;
324	struct stf_softc *sc;
325	const struct sockaddr_in6 *dst6;
326	const struct in_addr *in4;
327	uint8_t tos;
328	struct ip *ip;
329	struct ip6_hdr *ip6;
330	struct in6_ifaddr *ia6;
331	union {
332		struct sockaddr		dst;
333		struct sockaddr_in	dst4;
334	} u;
335
336	sc = (struct stf_softc*)ifp;
337	dst6 = (const struct sockaddr_in6 *)dst;
338
339	/* just in case */
340	if ((ifp->if_flags & IFF_UP) == 0) {
341		m_freem(m);
342		return ENETDOWN;
343	}
344
345	/*
346	 * If we don't have an ip4 address that match my inner ip6 address,
347	 * we shouldn't generate output.  Without this check, we'll end up
348	 * using wrong IPv4 source.
349	 */
350	ia6 = stf_getsrcifa6(ifp);
351	if (ia6 == NULL) {
352		m_freem(m);
353		ifp->if_oerrors++;
354		return ENETDOWN;
355	}
356
357	if (m->m_len < sizeof(*ip6)) {
358		m = m_pullup(m, sizeof(*ip6));
359		if (m == NULL) {
360			ifp->if_oerrors++;
361			return ENOBUFS;
362		}
363	}
364	ip6 = mtod(m, struct ip6_hdr *);
365	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
366
367	/*
368	 * Pickup the right outer dst addr from the list of candidates.
369	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
370	 */
371	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
372		in4 = GET_V4(&ip6->ip6_dst);
373	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
374		in4 = GET_V4(&dst6->sin6_addr);
375	else {
376		m_freem(m);
377		ifp->if_oerrors++;
378		return ENETUNREACH;
379	}
380
381	bpf_mtap_af(ifp, AF_INET6, m);
382
383	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
384	if (m && m->m_len < sizeof(struct ip))
385		m = m_pullup(m, sizeof(struct ip));
386	if (m == NULL) {
387		ifp->if_oerrors++;
388		return ENOBUFS;
389	}
390	ip = mtod(m, struct ip *);
391
392	memset(ip, 0, sizeof(*ip));
393
394	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
395	    &ip->ip_src, sizeof(ip->ip_src));
396	memcpy(&ip->ip_dst, in4, sizeof(ip->ip_dst));
397	ip->ip_p = IPPROTO_IPV6;
398	ip->ip_ttl = ip_gif_ttl;	/*XXX*/
399	ip->ip_len = htons(m->m_pkthdr.len);
400	if (ifp->if_flags & IFF_LINK1)
401		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
402	else
403		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
404
405	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
406	if ((rt = rtcache_lookup(&sc->sc_ro, &u.dst)) == NULL) {
407		m_freem(m);
408		ifp->if_oerrors++;
409		return ENETUNREACH;
410	}
411
412	/* If the route constitutes infinite encapsulation, punt. */
413	if (rt->rt_ifp == ifp) {
414		rtcache_free(&sc->sc_ro);
415		m_freem(m);
416		ifp->if_oerrors++;
417		return ENETUNREACH;
418	}
419
420	ifp->if_opackets++;
421	ifp->if_obytes += m->m_pkthdr.len - sizeof(struct ip);
422	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
423}
424
425static int
426isrfc1918addr(const struct in_addr *in)
427{
428	/*
429	 * returns 1 if private address range:
430	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
431	 */
432	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
433	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
434	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
435		return 1;
436
437	return 0;
438}
439
440static int
441stf_checkaddr4(struct stf_softc *sc, const struct in_addr *in,
442    struct ifnet *inifp /*incoming interface*/)
443{
444	struct in_ifaddr *ia4;
445
446	/*
447	 * reject packets with the following address:
448	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
449	 */
450	if (IN_MULTICAST(in->s_addr))
451		return -1;
452	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
453	case 0: case 127: case 255:
454		return -1;
455	}
456
457	/*
458	 * reject packets with private address range.
459	 * (requirement from RFC3056 section 2 1st paragraph)
460	 */
461	if (isrfc1918addr(in))
462		return -1;
463
464	/*
465	 * reject packet with IPv4 link-local (169.254.0.0/16),
466	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
467	 */
468	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
469	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
470		return -1;
471
472	/*
473	 * reject packets with broadcast
474	 */
475	TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
476	{
477		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
478			continue;
479		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
480			return -1;
481	}
482
483	/*
484	 * perform ingress filter
485	 */
486	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
487		struct sockaddr_in sin;
488		struct rtentry *rt;
489
490		memset(&sin, 0, sizeof(sin));
491		sin.sin_family = AF_INET;
492		sin.sin_len = sizeof(struct sockaddr_in);
493		sin.sin_addr = *in;
494		rt = rtalloc1((struct sockaddr *)&sin, 0);
495		if (!rt || rt->rt_ifp != inifp) {
496#if 0
497			log(LOG_WARNING, "%s: packet from 0x%x dropped "
498			    "due to ingress filter\n", if_name(&sc->sc_if),
499			    (uint32_t)ntohl(sin.sin_addr.s_addr));
500#endif
501			if (rt)
502				rtfree(rt);
503			return -1;
504		}
505		rtfree(rt);
506	}
507
508	return 0;
509}
510
511static int
512stf_checkaddr6(struct stf_softc *sc, const struct in6_addr *in6,
513    struct ifnet *inifp /*incoming interface*/)
514{
515
516	/*
517	 * check 6to4 addresses
518	 */
519	if (IN6_IS_ADDR_6TO4(in6))
520		return stf_checkaddr4(sc, GET_V4(in6), inifp);
521
522	/*
523	 * reject anything that look suspicious.  the test is implemented
524	 * in ip6_input too, but we check here as well to
525	 * (1) reject bad packets earlier, and
526	 * (2) to be safe against future ip6_input change.
527	 */
528	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
529		return -1;
530
531	/*
532	 * reject link-local and site-local unicast
533	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
534	 */
535	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
536		return -1;
537
538	/*
539	 * reject node-local and link-local multicast
540	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
541	 */
542	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
543		return -1;
544
545	return 0;
546}
547
548void
549in_stf_input(struct mbuf *m, ...)
550{
551	int off, proto;
552	struct stf_softc *sc;
553	struct ip *ip;
554	struct ip6_hdr *ip6;
555	uint8_t otos, itos;
556	int s, isr;
557	struct ifqueue *ifq = NULL;
558	struct ifnet *ifp;
559	va_list ap;
560
561	va_start(ap, m);
562	off = va_arg(ap, int);
563	proto = va_arg(ap, int);
564	va_end(ap);
565
566	if (proto != IPPROTO_IPV6) {
567		m_freem(m);
568		return;
569	}
570
571	ip = mtod(m, struct ip *);
572
573	sc = (struct stf_softc *)encap_getarg(m);
574
575	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
576		m_freem(m);
577		return;
578	}
579
580	ifp = &sc->sc_if;
581
582	/*
583	 * perform sanity check against outer src/dst.
584	 * for source, perform ingress filter as well.
585	 */
586	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
587	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
588		m_freem(m);
589		return;
590	}
591
592	otos = ip->ip_tos;
593	m_adj(m, off);
594
595	if (m->m_len < sizeof(*ip6)) {
596		m = m_pullup(m, sizeof(*ip6));
597		if (!m)
598			return;
599	}
600	ip6 = mtod(m, struct ip6_hdr *);
601
602	/*
603	 * perform sanity check against inner src/dst.
604	 * for source, perform ingress filter as well.
605	 */
606	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
607	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
608		m_freem(m);
609		return;
610	}
611
612	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
613	if ((ifp->if_flags & IFF_LINK1) != 0)
614		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
615	else
616		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
617	ip6->ip6_flow &= ~htonl(0xff << 20);
618	ip6->ip6_flow |= htonl((uint32_t)itos << 20);
619
620	m->m_pkthdr.rcvif = ifp;
621
622	bpf_mtap_af(ifp, AF_INET6, m);
623
624	/*
625	 * Put the packet to the network layer input queue according to the
626	 * specified address family.
627	 * See net/if_gif.c for possible issues with packet processing
628	 * reorder due to extra queueing.
629	 */
630	ifq = &ip6intrq;
631	isr = NETISR_IPV6;
632
633	s = splnet();
634	if (IF_QFULL(ifq)) {
635		IF_DROP(ifq);	/* update statistics */
636		m_freem(m);
637		splx(s);
638		return;
639	}
640	IF_ENQUEUE(ifq, m);
641	schednetisr(isr);
642	ifp->if_ipackets++;
643	ifp->if_ibytes += m->m_pkthdr.len;
644	splx(s);
645}
646
647/* ARGSUSED */
648static void
649stf_rtrequest(int cmd, struct rtentry *rt,
650    const struct rt_addrinfo *info)
651{
652	if (rt != NULL) {
653		struct stf_softc *sc;
654
655		sc = LIST_FIRST(&stf_softc_list);
656		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
657	}
658}
659
660static int
661stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
662{
663	struct ifaddr		*ifa;
664	struct ifreq		*ifr = data;
665	struct sockaddr_in6	*sin6;
666	int			error;
667
668	error = 0;
669	switch (cmd) {
670	case SIOCINITIFADDR:
671		ifa = (struct ifaddr *)data;
672		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
673			error = EAFNOSUPPORT;
674			break;
675		}
676		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
677		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
678		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
679			ifa->ifa_rtrequest = stf_rtrequest;
680			ifp->if_flags |= IFF_UP;
681		} else
682			error = EINVAL;
683		break;
684
685	case SIOCADDMULTI:
686	case SIOCDELMULTI:
687		if (ifr != NULL &&
688		    ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
689			;
690		else
691			error = EAFNOSUPPORT;
692		break;
693
694	case SIOCSIFMTU:
695		if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
696			return EINVAL;
697		else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
698			error = 0;
699		break;
700
701	default:
702		error = ifioctl_common(ifp, cmd, data);
703		break;
704	}
705
706	return error;
707}
708