xref: /netbsd-src/sys/net/if_stf.c (revision 20e85ad185ab16980f1219a557c42e057edb42ea)
1 /*	$NetBSD: if_stf.c,v 1.46 2005/03/11 13:28:25 tron 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 1.46 2005/03/11 13:28:25 tron 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 #include <machine/cpu.h>
94 
95 #include <net/if.h>
96 #include <net/route.h>
97 #include <net/netisr.h>
98 #include <net/if_types.h>
99 #include <net/if_stf.h>
100 
101 #include <netinet/in.h>
102 #include <netinet/in_systm.h>
103 #include <netinet/ip.h>
104 #include <netinet/ip_var.h>
105 #include <netinet/in_var.h>
106 
107 #include <netinet/ip6.h>
108 #include <netinet6/ip6_var.h>
109 #include <netinet6/in6_gif.h>
110 #include <netinet6/in6_var.h>
111 #include <netinet/ip_ecn.h>
112 
113 #include <netinet/ip_encap.h>
114 
115 #include <machine/stdarg.h>
116 
117 #include <net/net_osdep.h>
118 
119 #include "bpfilter.h"
120 #include "stf.h"
121 #include "gif.h"	/*XXX*/
122 
123 #if NBPFILTER > 0
124 #include <net/bpf.h>
125 #endif
126 
127 #if NGIF > 0
128 #include <net/if_gif.h>
129 #endif
130 
131 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
132 #define GET_V4(x)	((struct in_addr *)(&(x)->s6_addr16[1]))
133 
134 struct stf_softc {
135 	struct ifnet	sc_if;	   /* common area */
136 	union {
137 		struct route  __sc_ro4;
138 		struct route_in6 __sc_ro6; /* just for safety */
139 	} __sc_ro46;
140 #define sc_ro	__sc_ro46.__sc_ro4
141 	const struct encaptab *encap_cookie;
142 	LIST_ENTRY(stf_softc) sc_list;
143 };
144 
145 LIST_HEAD(, stf_softc) stf_softc_list;
146 
147 int	stf_clone_create __P((struct if_clone *, int));
148 int	stf_clone_destroy __P((struct ifnet *));
149 
150 struct if_clone stf_cloner =
151     IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
152 
153 #if NGIF > 0
154 extern int ip_gif_ttl;	/*XXX*/
155 #else
156 static int ip_gif_ttl = 40;	/*XXX*/
157 #endif
158 
159 extern struct domain inetdomain;
160 const struct protosw in_stf_protosw =
161 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
162   in_stf_input, rip_output,	0,		rip_ctloutput,
163   rip_usrreq,
164   0,            0,              0,              0
165 };
166 
167 void stfattach __P((int));
168 static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
169 static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
170 static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
171 	struct rtentry *));
172 static int isrfc1918addr __P((struct in_addr *));
173 static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
174 	struct ifnet *));
175 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
176 	struct ifnet *));
177 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
178 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
179 
180 /* ARGSUSED */
181 void
182 stfattach(count)
183 	int count;
184 {
185 
186 	LIST_INIT(&stf_softc_list);
187 	if_clone_attach(&stf_cloner);
188 }
189 
190 int
191 stf_clone_create(ifc, unit)
192 	struct if_clone *ifc;
193 	int unit;
194 {
195 	struct stf_softc *sc;
196 
197 	if (LIST_FIRST(&stf_softc_list) != NULL) {
198 		/* Only one stf interface is allowed. */
199 		return (EEXIST);
200 	}
201 
202 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT);
203 	memset(sc, 0, sizeof(struct stf_softc));
204 
205 	snprintf(sc->sc_if.if_xname, sizeof(sc->sc_if.if_xname), "%s%d",
206 	    ifc->ifc_name, unit);
207 
208 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
209 	    stf_encapcheck, &in_stf_protosw, sc);
210 	if (sc->encap_cookie == NULL) {
211 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
212 		free(sc, M_DEVBUF);
213 		return (EIO);	/* XXX */
214 	}
215 
216 	sc->sc_if.if_mtu    = STF_MTU;
217 	sc->sc_if.if_flags  = 0;
218 	sc->sc_if.if_ioctl  = stf_ioctl;
219 	sc->sc_if.if_output = stf_output;
220 	sc->sc_if.if_type   = IFT_STF;
221 	sc->sc_if.if_dlt    = DLT_NULL;
222 	if_attach(&sc->sc_if);
223 	if_alloc_sadl(&sc->sc_if);
224 #if NBPFILTER > 0
225 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
226 #endif
227 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
228 	return (0);
229 }
230 
231 int
232 stf_clone_destroy(ifp)
233 	struct ifnet *ifp;
234 {
235 	struct stf_softc *sc = (void *) ifp;
236 
237 	LIST_REMOVE(sc, sc_list);
238 	encap_detach(sc->encap_cookie);
239 #if NBPFILTER > 0
240 	bpfdetach(ifp);
241 #endif
242 	if_detach(ifp);
243 	free(sc, M_DEVBUF);
244 
245 	return (0);
246 }
247 
248 static int
249 stf_encapcheck(m, off, proto, arg)
250 	const struct mbuf *m;
251 	int off;
252 	int proto;
253 	void *arg;
254 {
255 	struct ip ip;
256 	struct in6_ifaddr *ia6;
257 	struct stf_softc *sc;
258 	struct in_addr a, b;
259 
260 	sc = (struct stf_softc *)arg;
261 	if (sc == NULL)
262 		return 0;
263 
264 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
265 		return 0;
266 
267 	/* IFF_LINK0 means "no decapsulation" */
268 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
269 		return 0;
270 
271 	if (proto != IPPROTO_IPV6)
272 		return 0;
273 
274 	/* LINTED const cast */
275 	m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
276 
277 	if (ip.ip_v != 4)
278 		return 0;
279 
280 	ia6 = stf_getsrcifa6(&sc->sc_if);
281 	if (ia6 == NULL)
282 		return 0;
283 
284 	/*
285 	 * check if IPv4 dst matches the IPv4 address derived from the
286 	 * local 6to4 address.
287 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
288 	 */
289 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
290 	    sizeof(ip.ip_dst)) != 0)
291 		return 0;
292 
293 	/*
294 	 * check if IPv4 src matches the IPv4 address derived from the
295 	 * local 6to4 address masked by prefixmask.
296 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
297 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
298 	 */
299 	memset(&a, 0, sizeof(a));
300 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
301 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
302 	b = ip.ip_src;
303 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
304 	if (a.s_addr != b.s_addr)
305 		return 0;
306 
307 	/* stf interface makes single side match only */
308 	return 32;
309 }
310 
311 static struct in6_ifaddr *
312 stf_getsrcifa6(ifp)
313 	struct ifnet *ifp;
314 {
315 	struct ifaddr *ifa;
316 	struct in_ifaddr *ia4;
317 	struct sockaddr_in6 *sin6;
318 	struct in_addr in;
319 
320 	IFADDR_FOREACH(ifa, ifp)
321 	{
322 		if (ifa->ifa_addr == NULL)
323 			continue;
324 		if (ifa->ifa_addr->sa_family != AF_INET6)
325 			continue;
326 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
327 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
328 			continue;
329 
330 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
331 		INADDR_TO_IA(in, ia4);
332 		if (ia4 == NULL)
333 			continue;
334 
335 		return (struct in6_ifaddr *)ifa;
336 	}
337 
338 	return NULL;
339 }
340 
341 static int
342 stf_output(ifp, m, dst, rt)
343 	struct ifnet *ifp;
344 	struct mbuf *m;
345 	struct sockaddr *dst;
346 	struct rtentry *rt;
347 {
348 	struct stf_softc *sc;
349 	struct sockaddr_in6 *dst6;
350 	struct in_addr *in4;
351 	struct sockaddr_in *dst4;
352 	u_int8_t tos;
353 	struct ip *ip;
354 	struct ip6_hdr *ip6;
355 	struct in6_ifaddr *ia6;
356 
357 	sc = (struct stf_softc*)ifp;
358 	dst6 = (struct sockaddr_in6 *)dst;
359 
360 	/* just in case */
361 	if ((ifp->if_flags & IFF_UP) == 0) {
362 		m_freem(m);
363 		return ENETDOWN;
364 	}
365 
366 	/*
367 	 * If we don't have an ip4 address that match my inner ip6 address,
368 	 * we shouldn't generate output.  Without this check, we'll end up
369 	 * using wrong IPv4 source.
370 	 */
371 	ia6 = stf_getsrcifa6(ifp);
372 	if (ia6 == NULL) {
373 		m_freem(m);
374 		ifp->if_oerrors++;
375 		return ENETDOWN;
376 	}
377 
378 	if (m->m_len < sizeof(*ip6)) {
379 		m = m_pullup(m, sizeof(*ip6));
380 		if (m == NULL) {
381 			ifp->if_oerrors++;
382 			return ENOBUFS;
383 		}
384 	}
385 	ip6 = mtod(m, struct ip6_hdr *);
386 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
387 
388 	/*
389 	 * Pickup the right outer dst addr from the list of candidates.
390 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
391 	 */
392 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
393 		in4 = GET_V4(&ip6->ip6_dst);
394 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
395 		in4 = GET_V4(&dst6->sin6_addr);
396 	else {
397 		m_freem(m);
398 		ifp->if_oerrors++;
399 		return ENETUNREACH;
400 	}
401 
402 #if NBPFILTER > 0
403 	if (ifp->if_bpf)
404 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
405 #endif /*NBPFILTER > 0*/
406 
407 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
408 	if (m && m->m_len < sizeof(struct ip))
409 		m = m_pullup(m, sizeof(struct ip));
410 	if (m == NULL) {
411 		ifp->if_oerrors++;
412 		return ENOBUFS;
413 	}
414 	ip = mtod(m, struct ip *);
415 
416 	memset(ip, 0, sizeof(*ip));
417 
418 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
419 	    &ip->ip_src, sizeof(ip->ip_src));
420 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
421 	ip->ip_p = IPPROTO_IPV6;
422 	ip->ip_ttl = ip_gif_ttl;	/*XXX*/
423 	ip->ip_len = htons(m->m_pkthdr.len);
424 	if (ifp->if_flags & IFF_LINK1)
425 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
426 	else
427 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
428 
429 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
430 	if (dst4->sin_family != AF_INET ||
431 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
432 		/* cache route doesn't match */
433 		dst4->sin_family = AF_INET;
434 		dst4->sin_len = sizeof(struct sockaddr_in);
435 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
436 		if (sc->sc_ro.ro_rt) {
437 			RTFREE(sc->sc_ro.ro_rt);
438 			sc->sc_ro.ro_rt = NULL;
439 		}
440 	}
441 
442 	if (sc->sc_ro.ro_rt == NULL) {
443 		rtalloc(&sc->sc_ro);
444 		if (sc->sc_ro.ro_rt == NULL) {
445 			m_freem(m);
446 			ifp->if_oerrors++;
447 			return ENETUNREACH;
448 		}
449 	}
450 
451 	ifp->if_opackets++;
452 	return ip_output(m, NULL, &sc->sc_ro, 0,
453 	    (struct ip_moptions *)NULL, (struct socket *)NULL);
454 }
455 
456 static int
457 isrfc1918addr(in)
458 	struct in_addr *in;
459 {
460 	/*
461 	 * returns 1 if private address range:
462 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
463 	 */
464 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
465 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
466 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
467 		return 1;
468 
469 	return 0;
470 }
471 
472 static int
473 stf_checkaddr4(sc, in, inifp)
474 	struct stf_softc *sc;
475 	struct in_addr *in;
476 	struct ifnet *inifp;	/* incoming interface */
477 {
478 	struct in_ifaddr *ia4;
479 
480 	/*
481 	 * reject packets with the following address:
482 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
483 	 */
484 	if (IN_MULTICAST(in->s_addr))
485 		return -1;
486 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
487 	case 0: case 127: case 255:
488 		return -1;
489 	}
490 
491 	/*
492 	 * reject packets with private address range.
493 	 * (requirement from RFC3056 section 2 1st paragraph)
494 	 */
495 	if (isrfc1918addr(in))
496 		return -1;
497 
498 	/*
499 	 * reject packet with IPv4 link-local (169.254.0.0/16),
500 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
501 	 */
502 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
503 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
504 		return -1;
505 
506 	/*
507 	 * reject packets with broadcast
508 	 */
509 	TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
510 	{
511 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
512 			continue;
513 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
514 			return -1;
515 	}
516 
517 	/*
518 	 * perform ingress filter
519 	 */
520 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
521 		struct sockaddr_in sin;
522 		struct rtentry *rt;
523 
524 		memset(&sin, 0, sizeof(sin));
525 		sin.sin_family = AF_INET;
526 		sin.sin_len = sizeof(struct sockaddr_in);
527 		sin.sin_addr = *in;
528 		rt = rtalloc1((struct sockaddr *)&sin, 0);
529 		if (!rt || rt->rt_ifp != inifp) {
530 #if 0
531 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
532 			    "due to ingress filter\n", if_name(&sc->sc_if),
533 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
534 #endif
535 			if (rt)
536 				rtfree(rt);
537 			return -1;
538 		}
539 		rtfree(rt);
540 	}
541 
542 	return 0;
543 }
544 
545 static int
546 stf_checkaddr6(sc, in6, inifp)
547 	struct stf_softc *sc;
548 	struct in6_addr *in6;
549 	struct ifnet *inifp;	/* incoming interface */
550 {
551 
552 	/*
553 	 * check 6to4 addresses
554 	 */
555 	if (IN6_IS_ADDR_6TO4(in6))
556 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
557 
558 	/*
559 	 * reject anything that look suspicious.  the test is implemented
560 	 * in ip6_input too, but we check here as well to
561 	 * (1) reject bad packets earlier, and
562 	 * (2) to be safe against future ip6_input change.
563 	 */
564 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
565 		return -1;
566 
567 	/*
568 	 * reject link-local and site-local unicast
569 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
570 	 */
571 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
572 		return -1;
573 
574 	/*
575 	 * reject node-local and link-local multicast
576 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
577 	 */
578 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
579 		return -1;
580 
581 	return 0;
582 }
583 
584 void
585 in_stf_input(struct mbuf *m, ...)
586 {
587 	int off, proto;
588 	struct stf_softc *sc;
589 	struct ip *ip;
590 	struct ip6_hdr *ip6;
591 	u_int8_t otos, itos;
592 	int s, isr;
593 	struct ifqueue *ifq = NULL;
594 	struct ifnet *ifp;
595 	va_list ap;
596 
597 	va_start(ap, m);
598 	off = va_arg(ap, int);
599 	proto = va_arg(ap, int);
600 	va_end(ap);
601 
602 	if (proto != IPPROTO_IPV6) {
603 		m_freem(m);
604 		return;
605 	}
606 
607 	ip = mtod(m, struct ip *);
608 
609 	sc = (struct stf_softc *)encap_getarg(m);
610 
611 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
612 		m_freem(m);
613 		return;
614 	}
615 
616 	ifp = &sc->sc_if;
617 
618 	/*
619 	 * perform sanity check against outer src/dst.
620 	 * for source, perform ingress filter as well.
621 	 */
622 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
623 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
624 		m_freem(m);
625 		return;
626 	}
627 
628 	otos = ip->ip_tos;
629 	m_adj(m, off);
630 
631 	if (m->m_len < sizeof(*ip6)) {
632 		m = m_pullup(m, sizeof(*ip6));
633 		if (!m)
634 			return;
635 	}
636 	ip6 = mtod(m, struct ip6_hdr *);
637 
638 	/*
639 	 * perform sanity check against inner src/dst.
640 	 * for source, perform ingress filter as well.
641 	 */
642 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
643 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
644 		m_freem(m);
645 		return;
646 	}
647 
648 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
649 	if ((ifp->if_flags & IFF_LINK1) != 0)
650 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
651 	else
652 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
653 	ip6->ip6_flow &= ~htonl(0xff << 20);
654 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
655 
656 	m->m_pkthdr.rcvif = ifp;
657 
658 #if NBPFILTER > 0
659 	if (ifp->if_bpf)
660 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
661 #endif /*NBPFILTER > 0*/
662 
663 	/*
664 	 * Put the packet to the network layer input queue according to the
665 	 * specified address family.
666 	 * See net/if_gif.c for possible issues with packet processing
667 	 * reorder due to extra queueing.
668 	 */
669 	ifq = &ip6intrq;
670 	isr = NETISR_IPV6;
671 
672 	s = splnet();
673 	if (IF_QFULL(ifq)) {
674 		IF_DROP(ifq);	/* update statistics */
675 		m_freem(m);
676 		splx(s);
677 		return;
678 	}
679 	IF_ENQUEUE(ifq, m);
680 	schednetisr(isr);
681 	ifp->if_ipackets++;
682 	ifp->if_ibytes += m->m_pkthdr.len;
683 	splx(s);
684 }
685 
686 /* ARGSUSED */
687 static void
688 stf_rtrequest(cmd, rt, info)
689 	int cmd;
690 	struct rtentry *rt;
691 	struct rt_addrinfo *info;
692 {
693 	if (rt != NULL) {
694 		struct stf_softc *sc;
695 
696 		sc = LIST_FIRST(&stf_softc_list);
697 		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
698 	}
699 }
700 
701 static int
702 stf_ioctl(ifp, cmd, data)
703 	struct ifnet *ifp;
704 	u_long cmd;
705 	caddr_t data;
706 {
707 	struct proc 		*p = curproc;	/* XXX */
708 	struct ifaddr		*ifa;
709 	struct ifreq		*ifr;
710 	struct sockaddr_in6	*sin6;
711 	int			error;
712 	u_long			mtu;
713 
714 	error = 0;
715 	switch (cmd) {
716 	case SIOCSIFADDR:
717 		ifa = (struct ifaddr *)data;
718 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
719 			error = EAFNOSUPPORT;
720 			break;
721 		}
722 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
723 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
724 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
725 			ifa->ifa_rtrequest = stf_rtrequest;
726 			ifp->if_flags |= IFF_UP;
727 		} else
728 			error = EINVAL;
729 		break;
730 
731 	case SIOCADDMULTI:
732 	case SIOCDELMULTI:
733 		ifr = (struct ifreq *)data;
734 		if (ifr != NULL && ifr->ifr_addr.sa_family == AF_INET6)
735 			;
736 		else
737 			error = EAFNOSUPPORT;
738 		break;
739 
740 	case SIOCSIFMTU:
741 		if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
742 			break;
743 		ifr = (struct ifreq *)data;
744 		mtu = ifr->ifr_mtu;
745 		if (mtu < STF_MTU_MIN || mtu > STF_MTU_MAX)
746 			return EINVAL;
747 		ifp->if_mtu = mtu;
748 		break;
749 
750 	default:
751 		error = EINVAL;
752 		break;
753 	}
754 
755 	return error;
756 }
757