xref: /dragonfly/sys/net/stf/if_stf.c (revision ed5d5720) 
1 /*	$FreeBSD: src/sys/net/if_stf.c,v 1.1.2.11 2003/01/23 21:06:44 sam Exp $	*/
2 /*	$DragonFly: src/sys/net/stf/if_stf.c,v 1.25 2008/10/27 02:56:30 sephe Exp $	*/
3 /*	$KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $	*/
4 
5 /*
6  * Copyright (C) 2000 WIDE Project.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the project nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /*
35  * 6to4 interface, based on RFC3056.
36  *
37  * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
38  * There is no address mapping defined from IPv6 multicast address to IPv4
39  * address.  Therefore, we do not have IFF_MULTICAST on the interface.
40  *
41  * Due to the lack of address mapping for link-local addresses, we cannot
42  * throw packets toward link-local addresses (fe80::x).  Also, we cannot throw
43  * packets to link-local multicast addresses (ff02::x).
44  *
45  * Here are interesting symptoms due to the lack of link-local address:
46  *
47  * Unicast routing exchange:
48  * - RIPng: Impossible.  Uses link-local multicast packet toward ff02::9,
49  *   and link-local addresses as nexthop.
50  * - OSPFv6: Impossible.  OSPFv6 assumes that there's link-local address
51  *   assigned to the link, and makes use of them.  Also, HELLO packets use
52  *   link-local multicast addresses (ff02::5 and ff02::6).
53  * - BGP4+: Maybe.  You can only use global address as nexthop, and global
54  *   address as TCP endpoint address.
55  *
56  * Multicast routing protocols:
57  * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
58  *   Adjacent PIM routers must be configured manually (is it really spec-wise
59  *   correct thing to do?).
60  *
61  * ICMPv6:
62  * - Redirects cannot be used due to the lack of link-local address.
63  *
64  * stf interface does not have, and will not need, a link-local address.
65  * It seems to have no real benefit and does not help the above symptoms much.
66  * Even if we assign link-locals to interface, we cannot really
67  * use link-local unicast/multicast on top of 6to4 cloud (since there's no
68  * encapsulation defined for link-local address), and the above analysis does
69  * not change.  RFC3056 does not mandate the assignment of link-local address
70  * either.
71  *
72  * 6to4 interface has security issues.  Refer to
73  * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
74  * for details.  The code tries to filter out some of malicious packets.
75  * Note that there is no way to be 100% secure.
76  */
77 
78 #include "opt_inet.h"
79 #include "opt_inet6.h"
80 
81 #include <sys/param.h>
82 #include <sys/systm.h>
83 #include <sys/socket.h>
84 #include <sys/sockio.h>
85 #include <sys/mbuf.h>
86 #include <sys/errno.h>
87 #include <sys/protosw.h>
88 #include <sys/kernel.h>
89 #include <machine/cpu.h>
90 
91 #include <sys/malloc.h>
92 
93 #include <net/if.h>
94 #include <net/route.h>
95 #include <net/netisr.h>
96 #include <net/if_types.h>
97 #include "if_stf.h"
98 
99 #include <netinet/in.h>
100 #include <netinet/in_systm.h>
101 #include <netinet/ip.h>
102 #include <netinet/ip_var.h>
103 #include <netinet/in_var.h>
104 
105 #include <netinet/ip6.h>
106 #include <netinet6/ip6_var.h>
107 #include <netinet6/in6_var.h>
108 #include <netinet/ip_ecn.h>
109 
110 #include <netinet/ip_encap.h>
111 
112 #include <machine/stdarg.h>
113 
114 #include <net/net_osdep.h>
115 
116 #include <net/bpf.h>
117 
118 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
119 #define GET_V4(x)	((struct in_addr *)(&(x)->s6_addr16[1]))
120 
121 struct stf_softc {
122 	struct ifnet	sc_if;	   /* common area */
123 	union {
124 		struct route  __sc_ro4;
125 		struct route_in6 __sc_ro6; /* just for safety */
126 	} __sc_ro46;
127 #define sc_ro	__sc_ro46.__sc_ro4
128 	const struct encaptab *encap_cookie;
129 };
130 
131 static struct stf_softc *stf;
132 
133 static MALLOC_DEFINE(M_STF, "stf", "6to4 Tunnel Interface");
134 static int ip_stf_ttl = 40;
135 
136 extern  struct domain inetdomain;
137 struct protosw in_stf_protosw =
138 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
139   in_stf_input, rip_output,	0,		rip_ctloutput,
140   NULL,		NULL,
141   0,            0,              0,              0,
142   &rip_usrreqs
143 };
144 
145 static int stfmodevent (module_t, int, void *);
146 static int stf_encapcheck (const struct mbuf *, int, int, void *);
147 static struct in6_ifaddr *stf_getsrcifa6 (struct ifnet *);
148 static int stf_output (struct ifnet *, struct mbuf *, struct sockaddr *,
149 	struct rtentry *);
150 static int stf_checkaddr4 (struct stf_softc *, struct in_addr *,
151 	struct ifnet *);
152 static int stf_checkaddr6 (struct stf_softc *, struct in6_addr *,
153 	struct ifnet *);
154 static void stf_rtrequest (int, struct rtentry *, struct rt_addrinfo *);
155 static int stf_ioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
156 
157 static int
158 stfmodevent(module_t mod, int type, void *data)
159 {
160 	struct stf_softc *sc;
161 	int err;
162 	const struct encaptab *p;
163 
164 	switch (type) {
165 	case MOD_LOAD:
166 		stf = kmalloc(sizeof(struct stf_softc), M_STF,
167 		    M_WAITOK | M_ZERO);
168 		sc = stf;
169 
170 		bzero(sc, sizeof(*sc));
171 		if_initname(&(sc->sc_if), "stf", 0);
172 
173 		p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck,
174 		    (void *)&in_stf_protosw, sc);
175 		if (p == NULL) {
176 			kprintf("%s: attach failed\n", if_name(&sc->sc_if));
177 			return (ENOMEM);
178 		}
179 		sc->encap_cookie = p;
180 
181 		sc->sc_if.if_mtu    = IPV6_MMTU;
182 		sc->sc_if.if_flags  = 0;
183 		sc->sc_if.if_ioctl  = stf_ioctl;
184 		sc->sc_if.if_output = stf_output;
185 		sc->sc_if.if_type   = IFT_STF;
186 #if 0
187 		/* turn off ingress filter */
188 		sc->sc_if.if_flags  |= IFF_LINK2;
189 #endif
190 		sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
191 		if_attach(&sc->sc_if, NULL);
192 		bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
193 		break;
194 	case MOD_UNLOAD:
195 		sc = stf;
196 		bpfdetach(&sc->sc_if);
197 		if_detach(&sc->sc_if);
198 		err = encap_detach(sc->encap_cookie);
199 		KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
200 		kfree(sc, M_STF);
201 		break;
202 	}
203 
204 	return (0);
205 }
206 
207 static moduledata_t stf_mod = {
208 	"if_stf",
209 	stfmodevent,
210 	0
211 };
212 
213 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
214 
215 static int
216 stf_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
217 {
218 	struct ip ip;
219 	struct in6_ifaddr *ia6;
220 	struct stf_softc *sc;
221 	struct in_addr a, b;
222 
223 	sc = (struct stf_softc *)arg;
224 	if (sc == NULL)
225 		return 0;
226 
227 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
228 		return 0;
229 
230 	/* IFF_LINK0 means "no decapsulation" */
231 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
232 		return 0;
233 
234 	if (proto != IPPROTO_IPV6)
235 		return 0;
236 
237 	m_copydata(m, 0, sizeof(ip), (caddr_t)&ip);
238 
239 	if (ip.ip_v != 4)
240 		return 0;
241 
242 	ia6 = stf_getsrcifa6(&sc->sc_if);
243 	if (ia6 == NULL)
244 		return 0;
245 
246 	/*
247 	 * check if IPv4 dst matches the IPv4 address derived from the
248 	 * local 6to4 address.
249 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
250 	 */
251 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
252 	    sizeof(ip.ip_dst)) != 0)
253 		return 0;
254 
255 	/*
256 	 * check if IPv4 src matches the IPv4 address derived from the
257 	 * local 6to4 address masked by prefixmask.
258 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
259 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
260 	 */
261 	bzero(&a, sizeof(a));
262 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
263 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
264 	b = ip.ip_src;
265 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
266 	if (a.s_addr != b.s_addr)
267 		return 0;
268 
269 	/* stf interface makes single side match only */
270 	return 32;
271 }
272 
273 static struct in6_ifaddr *
274 stf_getsrcifa6(struct ifnet *ifp)
275 {
276 	struct ifaddr_container *ifac;
277 	struct sockaddr_in6 *sin6;
278 	struct in_addr in;
279 
280 	TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
281 		struct ifaddr *ia = ifac->ifa;
282 		struct in_ifaddr_container *iac;
283 
284 		if (ia->ifa_addr == NULL)
285 			continue;
286 		if (ia->ifa_addr->sa_family != AF_INET6)
287 			continue;
288 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
289 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
290 			continue;
291 
292 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
293 		LIST_FOREACH(iac, INADDR_HASH(in.s_addr), ia_hash) {
294 			if (iac->ia->ia_addr.sin_addr.s_addr == in.s_addr)
295 				break;
296 		}
297 		if (iac == NULL)
298 			continue;
299 
300 		return (struct in6_ifaddr *)ia;
301 	}
302 
303 	return NULL;
304 }
305 
306 static int
307 stf_output_serialized(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
308 		      struct rtentry *rt)
309 {
310 	struct stf_softc *sc;
311 	struct sockaddr_in6 *dst6;
312 	struct in_addr *in4;
313 	struct sockaddr_in *dst4;
314 	u_int8_t tos;
315 	struct ip *ip;
316 	struct ip6_hdr *ip6;
317 	struct in6_ifaddr *ia6;
318 	static const uint32_t af = AF_INET6;
319 
320 	sc = (struct stf_softc*)ifp;
321 	dst6 = (struct sockaddr_in6 *)dst;
322 
323 	/* just in case */
324 	if ((ifp->if_flags & IFF_UP) == 0) {
325 		m_freem(m);
326 		return ENETDOWN;
327 	}
328 
329 	/*
330 	 * If we don't have an ip4 address that match my inner ip6 address,
331 	 * we shouldn't generate output.  Without this check, we'll end up
332 	 * using wrong IPv4 source.
333 	 */
334 	ia6 = stf_getsrcifa6(ifp);
335 	if (ia6 == NULL) {
336 		m_freem(m);
337 		return ENETDOWN;
338 	}
339 
340 	if (m->m_len < sizeof(*ip6)) {
341 		m = m_pullup(m, sizeof(*ip6));
342 		if (!m)
343 			return ENOBUFS;
344 	}
345 	ip6 = mtod(m, struct ip6_hdr *);
346 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
347 
348 	/*
349 	 * Pickup the right outer dst addr from the list of candidates.
350 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
351 	 */
352 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
353 		in4 = GET_V4(&ip6->ip6_dst);
354 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
355 		in4 = GET_V4(&dst6->sin6_addr);
356 	else {
357 		m_freem(m);
358 		return ENETUNREACH;
359 	}
360 
361 	if (ifp->if_bpf)
362 		bpf_ptap(ifp->if_bpf, m, &af, sizeof(af));
363 
364 	M_PREPEND(m, sizeof(struct ip), MB_DONTWAIT);
365 	if (m && m->m_len < sizeof(struct ip))
366 		m = m_pullup(m, sizeof(struct ip));
367 	if (m == NULL)
368 		return ENOBUFS;
369 	ip = mtod(m, struct ip *);
370 
371 	bzero(ip, sizeof(*ip));
372 
373 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
374 	    &ip->ip_src, sizeof(ip->ip_src));
375 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
376 	ip->ip_p = IPPROTO_IPV6;
377 	ip->ip_ttl = ip_stf_ttl;
378 	ip->ip_len = m->m_pkthdr.len;	/*host order*/
379 	if (ifp->if_flags & IFF_LINK1)
380 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
381 	else
382 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
383 
384 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
385 	if (dst4->sin_family != AF_INET ||
386 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
387 		/* cache route doesn't match */
388 		dst4->sin_family = AF_INET;
389 		dst4->sin_len = sizeof(struct sockaddr_in);
390 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
391 		if (sc->sc_ro.ro_rt) {
392 			RTFREE(sc->sc_ro.ro_rt);
393 			sc->sc_ro.ro_rt = NULL;
394 		}
395 	}
396 
397 	if (sc->sc_ro.ro_rt == NULL) {
398 		rtalloc(&sc->sc_ro);
399 		if (sc->sc_ro.ro_rt == NULL) {
400 			m_freem(m);
401 			return ENETUNREACH;
402 		}
403 	}
404 
405 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
406 }
407 
408 static int
409 stf_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
410 	   struct rtentry *rt)
411 {
412 	int error;
413 
414 	lwkt_serialize_enter(ifp->if_serializer);
415 	error = stf_output_serialized(ifp, m, dst, rt);
416 	lwkt_serialize_exit(ifp->if_serializer);
417 
418 	return error;
419 }
420 
421 /*
422  * Parameters:
423  *	inifp:	incoming interface
424  */
425 static int
426 stf_checkaddr4(struct stf_softc *sc, struct in_addr *in, struct ifnet *inifp)
427 {
428 	struct in_ifaddr_container *iac;
429 
430 	/*
431 	 * reject packets with the following address:
432 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
433 	 */
434 	if (IN_MULTICAST(ntohl(in->s_addr)))
435 		return -1;
436 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
437 	case 0: case 127: case 255:
438 		return -1;
439 	}
440 
441 	/*
442 	 * reject packets with broadcast
443 	 */
444 	TAILQ_FOREACH(iac, &in_ifaddrheads[mycpuid], ia_link) {
445 		struct in_ifaddr *ia4 = iac->ia;
446 
447 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
448 			continue;
449 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
450 			return -1;
451 	}
452 
453 	/*
454 	 * perform ingress filter
455 	 */
456 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
457 		struct sockaddr_in sin;
458 		struct rtentry *rt;
459 
460 		bzero(&sin, sizeof(sin));
461 		sin.sin_family = AF_INET;
462 		sin.sin_len = sizeof(struct sockaddr_in);
463 		sin.sin_addr = *in;
464 		rt = rtpurelookup((struct sockaddr *)&sin);
465 		if (!rt || rt->rt_ifp != inifp) {
466 #if 0
467 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
468 			    "due to ingress filter\n", if_name(&sc->sc_if),
469 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
470 #endif
471 			if (rt)
472 				rtfree(rt);
473 			return -1;
474 		}
475 		rtfree(rt);
476 	}
477 
478 	return 0;
479 }
480 
481 /*
482  * Parameters:
483  *	inifp:	incoming interface
484  */
485 static int
486 stf_checkaddr6(struct stf_softc *sc, struct in6_addr *in6, struct ifnet *inifp)
487 {
488 	/*
489 	 * check 6to4 addresses
490 	 */
491 	if (IN6_IS_ADDR_6TO4(in6))
492 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
493 
494 	/*
495 	 * reject anything that look suspicious.  the test is implemented
496 	 * in ip6_input too, but we check here as well to
497 	 * (1) reject bad packets earlier, and
498 	 * (2) to be safe against future ip6_input change.
499 	 */
500 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
501 		return -1;
502 
503 	return 0;
504 }
505 
506 void
507 in_stf_input(struct mbuf *m, ...)
508 {
509 	struct stf_softc *sc;
510 	struct ip *ip;
511 	struct ip6_hdr *ip6;
512 	u_int8_t otos, itos;
513 	struct ifnet *ifp;
514 	int off, proto;
515 	static const uint32_t af = AF_INET6;
516 	__va_list ap;
517 
518 	__va_start(ap, m);
519 	off = __va_arg(ap, int);
520 	proto = __va_arg(ap, int);
521 	__va_end(ap);
522 
523 	if (proto != IPPROTO_IPV6) {
524 		m_freem(m);
525 		return;
526 	}
527 
528 	ip = mtod(m, struct ip *);
529 
530 	sc = (struct stf_softc *)encap_getarg(m);
531 
532 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
533 		m_freem(m);
534 		return;
535 	}
536 
537 	ifp = &sc->sc_if;
538 
539 	/*
540 	 * perform sanity check against outer src/dst.
541 	 * for source, perform ingress filter as well.
542 	 */
543 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
544 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
545 		m_freem(m);
546 		return;
547 	}
548 
549 	otos = ip->ip_tos;
550 	m_adj(m, off);
551 
552 	if (m->m_len < sizeof(*ip6)) {
553 		m = m_pullup(m, sizeof(*ip6));
554 		if (!m)
555 			return;
556 	}
557 	ip6 = mtod(m, struct ip6_hdr *);
558 
559 	/*
560 	 * perform sanity check against inner src/dst.
561 	 * for source, perform ingress filter as well.
562 	 */
563 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
564 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
565 		m_freem(m);
566 		return;
567 	}
568 
569 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
570 	if ((ifp->if_flags & IFF_LINK1) != 0)
571 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
572 	else
573 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
574 	ip6->ip6_flow &= ~htonl(0xff << 20);
575 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
576 
577 	m->m_pkthdr.rcvif = ifp;
578 
579 	if (ifp->if_bpf)
580 		bpf_ptap(ifp->if_bpf, m, &af, sizeof(af));
581 
582 	/*
583 	 * Put the packet to the network layer input queue according to the
584 	 * specified address family.
585 	 * See net/if_gif.c for possible issues with packet processing
586 	 * reorder due to extra queueing.
587 	 */
588 	ifp->if_ipackets++;
589 	ifp->if_ibytes += m->m_pkthdr.len;
590 	netisr_dispatch(NETISR_IPV6, m);
591 }
592 
593 /* ARGSUSED */
594 static void
595 stf_rtrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
596 {
597 
598 	if (rt)
599 		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
600 }
601 
602 static int
603 stf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
604 {
605 	struct ifaddr *ifa;
606 	struct ifreq *ifr;
607 	struct sockaddr_in6 *sin6;
608 	int error;
609 
610 	error = 0;
611 	switch (cmd) {
612 	case SIOCSIFADDR:
613 		ifa = (struct ifaddr *)data;
614 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
615 			error = EAFNOSUPPORT;
616 			break;
617 		}
618 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
619 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
620 			ifa->ifa_rtrequest = stf_rtrequest;
621 			ifp->if_flags |= IFF_UP;
622 		} else
623 			error = EINVAL;
624 		break;
625 
626 	case SIOCADDMULTI:
627 	case SIOCDELMULTI:
628 		ifr = (struct ifreq *)data;
629 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
630 			;
631 		else
632 			error = EAFNOSUPPORT;
633 		break;
634 
635 	default:
636 		error = EINVAL;
637 		break;
638 	}
639 
640 	return error;
641 }
642