xref: /netbsd-src/sys/net/if_stf.c (revision 23c8222edbfb0f0932d88a8351d3a0cf817dfb9e)
1 /*	$NetBSD: if_stf.c,v 1.40 2004/08/19 20:58:24 christos 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 1.40 2004/08/19 20:58:24 christos 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/protosw.h>
90 #include <sys/queue.h>
91 #include <sys/syslog.h>
92 #include <machine/cpu.h>
93 
94 #include <net/if.h>
95 #include <net/route.h>
96 #include <net/netisr.h>
97 #include <net/if_types.h>
98 #include <net/if_stf.h>
99 
100 #include <netinet/in.h>
101 #include <netinet/in_systm.h>
102 #include <netinet/ip.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/in_var.h>
105 
106 #include <netinet/ip6.h>
107 #include <netinet6/ip6_var.h>
108 #include <netinet6/in6_gif.h>
109 #include <netinet6/in6_var.h>
110 #include <netinet/ip_ecn.h>
111 
112 #include <netinet/ip_encap.h>
113 
114 #include <machine/stdarg.h>
115 
116 #include <net/net_osdep.h>
117 
118 #include "bpfilter.h"
119 #include "stf.h"
120 #include "gif.h"	/*XXX*/
121 
122 #if NBPFILTER > 0
123 #include <net/bpf.h>
124 #endif
125 
126 #if NGIF > 0
127 #include <net/if_gif.h>
128 #endif
129 
130 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
131 #define GET_V4(x)	((struct in_addr *)(&(x)->s6_addr16[1]))
132 
133 struct stf_softc {
134 	struct ifnet	sc_if;	   /* common area */
135 	union {
136 		struct route  __sc_ro4;
137 		struct route_in6 __sc_ro6; /* just for safety */
138 	} __sc_ro46;
139 #define sc_ro	__sc_ro46.__sc_ro4
140 	const struct encaptab *encap_cookie;
141 	LIST_ENTRY(stf_softc) sc_list;
142 };
143 
144 LIST_HEAD(, stf_softc) stf_softc_list;
145 
146 int	stf_clone_create __P((struct if_clone *, int));
147 void	stf_clone_destroy __P((struct ifnet *));
148 
149 struct if_clone stf_cloner =
150     IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
151 
152 #if NGIF > 0
153 extern int ip_gif_ttl;	/*XXX*/
154 #else
155 static int ip_gif_ttl = 40;	/*XXX*/
156 #endif
157 
158 extern struct domain inetdomain;
159 const struct protosw in_stf_protosw =
160 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
161   in_stf_input, rip_output,	0,		rip_ctloutput,
162   rip_usrreq,
163   0,            0,              0,              0
164 };
165 
166 void stfattach __P((int));
167 static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
168 static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
169 static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
170 	struct rtentry *));
171 static int isrfc1918addr __P((struct in_addr *));
172 static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
173 	struct ifnet *));
174 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
175 	struct ifnet *));
176 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
177 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
178 
179 /* ARGSUSED */
180 void
181 stfattach(count)
182 	int count;
183 {
184 
185 	LIST_INIT(&stf_softc_list);
186 	if_clone_attach(&stf_cloner);
187 }
188 
189 int
190 stf_clone_create(ifc, unit)
191 	struct if_clone *ifc;
192 	int unit;
193 {
194 	struct stf_softc *sc;
195 
196 	if (LIST_FIRST(&stf_softc_list) != NULL) {
197 		/* Only one stf interface is allowed. */
198 		return (EEXIST);
199 	}
200 
201 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT);
202 	memset(sc, 0, sizeof(struct stf_softc));
203 
204 	snprintf(sc->sc_if.if_xname, sizeof(sc->sc_if.if_xname), "%s%d",
205 	    ifc->ifc_name, unit);
206 
207 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
208 	    stf_encapcheck, &in_stf_protosw, sc);
209 	if (sc->encap_cookie == NULL) {
210 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
211 		free(sc, M_DEVBUF);
212 		return (EIO);	/* XXX */
213 	}
214 
215 	sc->sc_if.if_mtu    = IPV6_MMTU;
216 	sc->sc_if.if_flags  = 0;
217 	sc->sc_if.if_ioctl  = stf_ioctl;
218 	sc->sc_if.if_output = stf_output;
219 	sc->sc_if.if_type   = IFT_STF;
220 	sc->sc_if.if_dlt    = DLT_NULL;
221 	if_attach(&sc->sc_if);
222 	if_alloc_sadl(&sc->sc_if);
223 #if NBPFILTER > 0
224 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
225 #endif
226 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
227 	return (0);
228 }
229 
230 void
231 stf_clone_destroy(ifp)
232 	struct ifnet *ifp;
233 {
234 	struct stf_softc *sc = (void *) ifp;
235 
236 	LIST_REMOVE(sc, sc_list);
237 	encap_detach(sc->encap_cookie);
238 #if NBPFILTER > 0
239 	bpfdetach(ifp);
240 #endif
241 	if_detach(ifp);
242 	free(sc, M_DEVBUF);
243 }
244 
245 static int
246 stf_encapcheck(m, off, proto, arg)
247 	const struct mbuf *m;
248 	int off;
249 	int proto;
250 	void *arg;
251 {
252 	struct ip ip;
253 	struct in6_ifaddr *ia6;
254 	struct stf_softc *sc;
255 	struct in_addr a, b;
256 
257 	sc = (struct stf_softc *)arg;
258 	if (sc == NULL)
259 		return 0;
260 
261 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
262 		return 0;
263 
264 	/* IFF_LINK0 means "no decapsulation" */
265 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
266 		return 0;
267 
268 	if (proto != IPPROTO_IPV6)
269 		return 0;
270 
271 	/* LINTED const cast */
272 	m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
273 
274 	if (ip.ip_v != 4)
275 		return 0;
276 
277 	ia6 = stf_getsrcifa6(&sc->sc_if);
278 	if (ia6 == NULL)
279 		return 0;
280 
281 	/*
282 	 * check if IPv4 dst matches the IPv4 address derived from the
283 	 * local 6to4 address.
284 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
285 	 */
286 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
287 	    sizeof(ip.ip_dst)) != 0)
288 		return 0;
289 
290 	/*
291 	 * check if IPv4 src matches the IPv4 address derived from the
292 	 * local 6to4 address masked by prefixmask.
293 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
294 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
295 	 */
296 	memset(&a, 0, sizeof(a));
297 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
298 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
299 	b = ip.ip_src;
300 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
301 	if (a.s_addr != b.s_addr)
302 		return 0;
303 
304 	/* stf interface makes single side match only */
305 	return 32;
306 }
307 
308 static struct in6_ifaddr *
309 stf_getsrcifa6(ifp)
310 	struct ifnet *ifp;
311 {
312 	struct ifaddr *ia;
313 	struct in_ifaddr *ia4;
314 	struct sockaddr_in6 *sin6;
315 	struct in_addr in;
316 
317 	TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list)
318 	{
319 		if (ia->ifa_addr == NULL)
320 			continue;
321 		if (ia->ifa_addr->sa_family != AF_INET6)
322 			continue;
323 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
324 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
325 			continue;
326 
327 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
328 		INADDR_TO_IA(in, ia4);
329 		if (ia4 == NULL)
330 			continue;
331 
332 		return (struct in6_ifaddr *)ia;
333 	}
334 
335 	return NULL;
336 }
337 
338 static int
339 stf_output(ifp, m, dst, rt)
340 	struct ifnet *ifp;
341 	struct mbuf *m;
342 	struct sockaddr *dst;
343 	struct rtentry *rt;
344 {
345 	struct stf_softc *sc;
346 	struct sockaddr_in6 *dst6;
347 	struct in_addr *in4;
348 	struct sockaddr_in *dst4;
349 	u_int8_t tos;
350 	struct ip *ip;
351 	struct ip6_hdr *ip6;
352 	struct in6_ifaddr *ia6;
353 
354 	sc = (struct stf_softc*)ifp;
355 	dst6 = (struct sockaddr_in6 *)dst;
356 
357 	/* just in case */
358 	if ((ifp->if_flags & IFF_UP) == 0) {
359 		m_freem(m);
360 		return ENETDOWN;
361 	}
362 
363 	/*
364 	 * If we don't have an ip4 address that match my inner ip6 address,
365 	 * we shouldn't generate output.  Without this check, we'll end up
366 	 * using wrong IPv4 source.
367 	 */
368 	ia6 = stf_getsrcifa6(ifp);
369 	if (ia6 == NULL) {
370 		m_freem(m);
371 		ifp->if_oerrors++;
372 		return ENETDOWN;
373 	}
374 
375 	if (m->m_len < sizeof(*ip6)) {
376 		m = m_pullup(m, sizeof(*ip6));
377 		if (m == NULL) {
378 			ifp->if_oerrors++;
379 			return ENOBUFS;
380 		}
381 	}
382 	ip6 = mtod(m, struct ip6_hdr *);
383 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
384 
385 	/*
386 	 * Pickup the right outer dst addr from the list of candidates.
387 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
388 	 */
389 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
390 		in4 = GET_V4(&ip6->ip6_dst);
391 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
392 		in4 = GET_V4(&dst6->sin6_addr);
393 	else {
394 		m_freem(m);
395 		ifp->if_oerrors++;
396 		return ENETUNREACH;
397 	}
398 
399 #if NBPFILTER > 0
400 	if (ifp->if_bpf)
401 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
402 #endif /*NBPFILTER > 0*/
403 
404 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
405 	if (m && m->m_len < sizeof(struct ip))
406 		m = m_pullup(m, sizeof(struct ip));
407 	if (m == NULL) {
408 		ifp->if_oerrors++;
409 		return ENOBUFS;
410 	}
411 	ip = mtod(m, struct ip *);
412 
413 	memset(ip, 0, sizeof(*ip));
414 
415 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
416 	    &ip->ip_src, sizeof(ip->ip_src));
417 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
418 	ip->ip_p = IPPROTO_IPV6;
419 	ip->ip_ttl = ip_gif_ttl;	/*XXX*/
420 	ip->ip_len = htons(m->m_pkthdr.len);
421 	if (ifp->if_flags & IFF_LINK1)
422 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
423 	else
424 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
425 
426 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
427 	if (dst4->sin_family != AF_INET ||
428 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
429 		/* cache route doesn't match */
430 		dst4->sin_family = AF_INET;
431 		dst4->sin_len = sizeof(struct sockaddr_in);
432 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
433 		if (sc->sc_ro.ro_rt) {
434 			RTFREE(sc->sc_ro.ro_rt);
435 			sc->sc_ro.ro_rt = NULL;
436 		}
437 	}
438 
439 	if (sc->sc_ro.ro_rt == NULL) {
440 		rtalloc(&sc->sc_ro);
441 		if (sc->sc_ro.ro_rt == NULL) {
442 			m_freem(m);
443 			ifp->if_oerrors++;
444 			return ENETUNREACH;
445 		}
446 	}
447 
448 	ifp->if_opackets++;
449 	return ip_output(m, NULL, &sc->sc_ro, 0,
450 	    (struct ip_moptions *)NULL, (struct socket *)NULL);
451 }
452 
453 static int
454 isrfc1918addr(in)
455 	struct in_addr *in;
456 {
457 	/*
458 	 * returns 1 if private address range:
459 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
460 	 */
461 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
462 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
463 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
464 		return 1;
465 
466 	return 0;
467 }
468 
469 static int
470 stf_checkaddr4(sc, in, inifp)
471 	struct stf_softc *sc;
472 	struct in_addr *in;
473 	struct ifnet *inifp;	/* incoming interface */
474 {
475 	struct in_ifaddr *ia4;
476 
477 	/*
478 	 * reject packets with the following address:
479 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
480 	 */
481 	if (IN_MULTICAST(in->s_addr))
482 		return -1;
483 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
484 	case 0: case 127: case 255:
485 		return -1;
486 	}
487 
488 	/*
489 	 * reject packets with private address range.
490 	 * (requirement from RFC3056 section 2 1st paragraph)
491 	 */
492 	if (isrfc1918addr(in))
493 		return -1;
494 
495 	/*
496 	 * reject packet with IPv4 link-local (169.254.0.0/16),
497 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
498 	 */
499 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
500 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
501 		return -1;
502 
503 	/*
504 	 * reject packets with broadcast
505 	 */
506 	TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
507 	{
508 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
509 			continue;
510 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
511 			return -1;
512 	}
513 
514 	/*
515 	 * perform ingress filter
516 	 */
517 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
518 		struct sockaddr_in sin;
519 		struct rtentry *rt;
520 
521 		memset(&sin, 0, sizeof(sin));
522 		sin.sin_family = AF_INET;
523 		sin.sin_len = sizeof(struct sockaddr_in);
524 		sin.sin_addr = *in;
525 		rt = rtalloc1((struct sockaddr *)&sin, 0);
526 		if (!rt || rt->rt_ifp != inifp) {
527 #if 0
528 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
529 			    "due to ingress filter\n", if_name(&sc->sc_if),
530 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
531 #endif
532 			if (rt)
533 				rtfree(rt);
534 			return -1;
535 		}
536 		rtfree(rt);
537 	}
538 
539 	return 0;
540 }
541 
542 static int
543 stf_checkaddr6(sc, in6, inifp)
544 	struct stf_softc *sc;
545 	struct in6_addr *in6;
546 	struct ifnet *inifp;	/* incoming interface */
547 {
548 
549 	/*
550 	 * check 6to4 addresses
551 	 */
552 	if (IN6_IS_ADDR_6TO4(in6))
553 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
554 
555 	/*
556 	 * reject anything that look suspicious.  the test is implemented
557 	 * in ip6_input too, but we check here as well to
558 	 * (1) reject bad packets earlier, and
559 	 * (2) to be safe against future ip6_input change.
560 	 */
561 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
562 		return -1;
563 
564 	/*
565 	 * reject link-local and site-local unicast
566 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
567 	 */
568 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
569 		return -1;
570 
571 	/*
572 	 * reject node-local and link-local multicast
573 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
574 	 */
575 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
576 		return -1;
577 
578 	return 0;
579 }
580 
581 void
582 in_stf_input(struct mbuf *m, ...)
583 {
584 	int off, proto;
585 	struct stf_softc *sc;
586 	struct ip *ip;
587 	struct ip6_hdr *ip6;
588 	u_int8_t otos, itos;
589 	int s, isr;
590 	struct ifqueue *ifq = NULL;
591 	struct ifnet *ifp;
592 	va_list ap;
593 
594 	va_start(ap, m);
595 	off = va_arg(ap, int);
596 	proto = va_arg(ap, int);
597 	va_end(ap);
598 
599 	if (proto != IPPROTO_IPV6) {
600 		m_freem(m);
601 		return;
602 	}
603 
604 	ip = mtod(m, struct ip *);
605 
606 	sc = (struct stf_softc *)encap_getarg(m);
607 
608 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
609 		m_freem(m);
610 		return;
611 	}
612 
613 	ifp = &sc->sc_if;
614 
615 	/*
616 	 * perform sanity check against outer src/dst.
617 	 * for source, perform ingress filter as well.
618 	 */
619 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
620 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
621 		m_freem(m);
622 		return;
623 	}
624 
625 	otos = ip->ip_tos;
626 	m_adj(m, off);
627 
628 	if (m->m_len < sizeof(*ip6)) {
629 		m = m_pullup(m, sizeof(*ip6));
630 		if (!m)
631 			return;
632 	}
633 	ip6 = mtod(m, struct ip6_hdr *);
634 
635 	/*
636 	 * perform sanity check against inner src/dst.
637 	 * for source, perform ingress filter as well.
638 	 */
639 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
640 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
641 		m_freem(m);
642 		return;
643 	}
644 
645 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
646 	if ((ifp->if_flags & IFF_LINK1) != 0)
647 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
648 	else
649 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
650 	ip6->ip6_flow &= ~htonl(0xff << 20);
651 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
652 
653 	m->m_pkthdr.rcvif = ifp;
654 
655 #if NBPFILTER > 0
656 	if (ifp->if_bpf)
657 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
658 #endif /*NBPFILTER > 0*/
659 
660 	/*
661 	 * Put the packet to the network layer input queue according to the
662 	 * specified address family.
663 	 * See net/if_gif.c for possible issues with packet processing
664 	 * reorder due to extra queueing.
665 	 */
666 	ifq = &ip6intrq;
667 	isr = NETISR_IPV6;
668 
669 	s = splnet();
670 	if (IF_QFULL(ifq)) {
671 		IF_DROP(ifq);	/* update statistics */
672 		m_freem(m);
673 		splx(s);
674 		return;
675 	}
676 	IF_ENQUEUE(ifq, m);
677 	schednetisr(isr);
678 	ifp->if_ipackets++;
679 	ifp->if_ibytes += m->m_pkthdr.len;
680 	splx(s);
681 }
682 
683 /* ARGSUSED */
684 static void
685 stf_rtrequest(cmd, rt, info)
686 	int cmd;
687 	struct rtentry *rt;
688 	struct rt_addrinfo *info;
689 {
690 
691 	if (rt)
692 		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
693 }
694 
695 static int
696 stf_ioctl(ifp, cmd, data)
697 	struct ifnet *ifp;
698 	u_long cmd;
699 	caddr_t data;
700 {
701 	struct ifaddr *ifa;
702 	struct ifreq *ifr;
703 	struct sockaddr_in6 *sin6;
704 	int error;
705 
706 	error = 0;
707 	switch (cmd) {
708 	case SIOCSIFADDR:
709 		ifa = (struct ifaddr *)data;
710 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
711 			error = EAFNOSUPPORT;
712 			break;
713 		}
714 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
715 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
716 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
717 			ifa->ifa_rtrequest = stf_rtrequest;
718 			ifp->if_flags |= IFF_UP;
719 		} else
720 			error = EINVAL;
721 		break;
722 
723 	case SIOCADDMULTI:
724 	case SIOCDELMULTI:
725 		ifr = (struct ifreq *)data;
726 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
727 			;
728 		else
729 			error = EAFNOSUPPORT;
730 		break;
731 
732 	default:
733 		error = EINVAL;
734 		break;
735 	}
736 
737 	return error;
738 }
739