xref: /netbsd/sys/net/if_stf.c (revision bf9ec67e)
1 /*	$NetBSD: if_stf.c,v 1.23 2001/12/21 03:21:50 itojun 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 1.23 2001/12/21 03:21:50 itojun 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 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 stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
172 	struct ifnet *));
173 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
174 	struct ifnet *));
175 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
176 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
177 
178 /* ARGSUSED */
179 void
180 stfattach(count)
181 	int count;
182 {
183 
184 	LIST_INIT(&stf_softc_list);
185 	if_clone_attach(&stf_cloner);
186 }
187 
188 int
189 stf_clone_create(ifc, unit)
190 	struct if_clone *ifc;
191 	int unit;
192 {
193 	struct stf_softc *sc;
194 
195 	if (LIST_FIRST(&stf_softc_list) != NULL) {
196 		/* Only one stf interface is allowed. */
197 		return (EEXIST);
198 	}
199 
200 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT);
201 	memset(sc, 0, sizeof(struct stf_softc));
202 
203 	sprintf(sc->sc_if.if_xname, "%s%d", ifc->ifc_name, unit);
204 
205 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
206 	    stf_encapcheck, &in_stf_protosw, sc);
207 	if (sc->encap_cookie == NULL) {
208 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
209 		free(sc, M_DEVBUF);
210 		return (EIO);	/* XXX */
211 	}
212 
213 	sc->sc_if.if_mtu    = IPV6_MMTU;
214 	sc->sc_if.if_flags  = 0;
215 	sc->sc_if.if_ioctl  = stf_ioctl;
216 	sc->sc_if.if_output = stf_output;
217 	sc->sc_if.if_type   = IFT_STF;
218 	sc->sc_if.if_dlt    = DLT_NULL;
219 	if_attach(&sc->sc_if);
220 	if_alloc_sadl(&sc->sc_if);
221 #if NBPFILTER > 0
222 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
223 #endif
224 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
225 	return (0);
226 }
227 
228 void
229 stf_clone_destroy(ifp)
230 	struct ifnet *ifp;
231 {
232 	struct stf_softc *sc = (void *) ifp;
233 
234 	LIST_REMOVE(sc, sc_list);
235 	encap_detach(sc->encap_cookie);
236 #if NBPFILTER > 0
237 	bpfdetach(ifp);
238 #endif
239 	if_detach(ifp);
240 	free(sc, M_DEVBUF);
241 }
242 
243 static int
244 stf_encapcheck(m, off, proto, arg)
245 	const struct mbuf *m;
246 	int off;
247 	int proto;
248 	void *arg;
249 {
250 	struct ip ip;
251 	struct in6_ifaddr *ia6;
252 	struct stf_softc *sc;
253 	struct in_addr a, b;
254 
255 	sc = (struct stf_softc *)arg;
256 	if (sc == NULL)
257 		return 0;
258 
259 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
260 		return 0;
261 
262 	/* IFF_LINK0 means "no decapsulation" */
263 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
264 		return 0;
265 
266 	if (proto != IPPROTO_IPV6)
267 		return 0;
268 
269 	/* LINTED const cast */
270 	m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
271 
272 	if (ip.ip_v != 4)
273 		return 0;
274 
275 	ia6 = stf_getsrcifa6(&sc->sc_if);
276 	if (ia6 == NULL)
277 		return 0;
278 
279 	/*
280 	 * check if IPv4 dst matches the IPv4 address derived from the
281 	 * local 6to4 address.
282 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
283 	 */
284 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
285 	    sizeof(ip.ip_dst)) != 0)
286 		return 0;
287 
288 	/*
289 	 * check if IPv4 src matches the IPv4 address derived from the
290 	 * local 6to4 address masked by prefixmask.
291 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
292 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
293 	 */
294 	memset(&a, 0, sizeof(a));
295 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
296 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
297 	b = ip.ip_src;
298 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
299 	if (a.s_addr != b.s_addr)
300 		return 0;
301 
302 	/* stf interface makes single side match only */
303 	return 32;
304 }
305 
306 static struct in6_ifaddr *
307 stf_getsrcifa6(ifp)
308 	struct ifnet *ifp;
309 {
310 	struct ifaddr *ia;
311 	struct in_ifaddr *ia4;
312 	struct sockaddr_in6 *sin6;
313 	struct in_addr in;
314 
315 	TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list)
316 	{
317 		if (ia->ifa_addr == NULL)
318 			continue;
319 		if (ia->ifa_addr->sa_family != AF_INET6)
320 			continue;
321 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
322 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
323 			continue;
324 
325 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
326 		INADDR_TO_IA(in, ia4);
327 		if (ia4 == NULL)
328 			continue;
329 
330 		return (struct in6_ifaddr *)ia;
331 	}
332 
333 	return NULL;
334 }
335 
336 static int
337 stf_output(ifp, m, dst, rt)
338 	struct ifnet *ifp;
339 	struct mbuf *m;
340 	struct sockaddr *dst;
341 	struct rtentry *rt;
342 {
343 	struct stf_softc *sc;
344 	struct sockaddr_in6 *dst6;
345 	struct in_addr *in4;
346 	struct sockaddr_in *dst4;
347 	u_int8_t tos;
348 	struct ip *ip;
349 	struct ip6_hdr *ip6;
350 	struct in6_ifaddr *ia6;
351 
352 	sc = (struct stf_softc*)ifp;
353 	dst6 = (struct sockaddr_in6 *)dst;
354 
355 	/* just in case */
356 	if ((ifp->if_flags & IFF_UP) == 0) {
357 		m_freem(m);
358 		return ENETDOWN;
359 	}
360 
361 	/*
362 	 * If we don't have an ip4 address that match my inner ip6 address,
363 	 * we shouldn't generate output.  Without this check, we'll end up
364 	 * using wrong IPv4 source.
365 	 */
366 	ia6 = stf_getsrcifa6(ifp);
367 	if (ia6 == NULL) {
368 		m_freem(m);
369 		return ENETDOWN;
370 	}
371 
372 	if (m->m_len < sizeof(*ip6)) {
373 		m = m_pullup(m, sizeof(*ip6));
374 		if (!m)
375 			return ENOBUFS;
376 	}
377 	ip6 = mtod(m, struct ip6_hdr *);
378 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
379 
380 	/*
381 	 * Pickup the right outer dst addr from the list of candidates.
382 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
383 	 */
384 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
385 		in4 = GET_V4(&ip6->ip6_dst);
386 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
387 		in4 = GET_V4(&dst6->sin6_addr);
388 	else {
389 		m_freem(m);
390 		return ENETUNREACH;
391 	}
392 
393 #if NBPFILTER > 0
394 	if (ifp->if_bpf) {
395 		/*
396 		 * We need to prepend the address family as
397 		 * a four byte field.  Cons up a dummy header
398 		 * to pacify bpf.  This is safe because bpf
399 		 * will only read from the mbuf (i.e., it won't
400 		 * try to free it or keep a pointer a to it).
401 		 */
402 		struct mbuf m0;
403 		u_int32_t af = AF_INET6;
404 
405 		m0.m_next = m;
406 		m0.m_len = 4;
407 		m0.m_data = (char *)&af;
408 
409 #ifdef HAVE_OLD_BPF
410 		bpf_mtap(ifp, &m0);
411 #else
412 		bpf_mtap(ifp->if_bpf, &m0);
413 #endif
414 	}
415 #endif /*NBPFILTER > 0*/
416 
417 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
418 	if (m && m->m_len < sizeof(struct ip))
419 		m = m_pullup(m, sizeof(struct ip));
420 	if (m == NULL)
421 		return ENOBUFS;
422 	ip = mtod(m, struct ip *);
423 
424 	memset(ip, 0, sizeof(*ip));
425 
426 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
427 	    &ip->ip_src, sizeof(ip->ip_src));
428 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
429 	ip->ip_p = IPPROTO_IPV6;
430 	ip->ip_ttl = ip_gif_ttl;	/*XXX*/
431 	ip->ip_len = m->m_pkthdr.len;	/*host order*/
432 	if (ifp->if_flags & IFF_LINK1)
433 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
434 	else
435 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
436 
437 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
438 	if (dst4->sin_family != AF_INET ||
439 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
440 		/* cache route doesn't match */
441 		dst4->sin_family = AF_INET;
442 		dst4->sin_len = sizeof(struct sockaddr_in);
443 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
444 		if (sc->sc_ro.ro_rt) {
445 			RTFREE(sc->sc_ro.ro_rt);
446 			sc->sc_ro.ro_rt = NULL;
447 		}
448 	}
449 
450 	if (sc->sc_ro.ro_rt == NULL) {
451 		rtalloc(&sc->sc_ro);
452 		if (sc->sc_ro.ro_rt == NULL) {
453 			m_freem(m);
454 			return ENETUNREACH;
455 		}
456 	}
457 
458 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL);
459 }
460 
461 static int
462 stf_checkaddr4(sc, in, inifp)
463 	struct stf_softc *sc;
464 	struct in_addr *in;
465 	struct ifnet *inifp;	/* incoming interface */
466 {
467 	struct in_ifaddr *ia4;
468 
469 	/*
470 	 * reject packets with the following address:
471 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
472 	 */
473 	if (IN_MULTICAST(in->s_addr))
474 		return -1;
475 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
476 	case 0: case 127: case 255:
477 		return -1;
478 	}
479 
480 	/*
481 	 * reject packets with broadcast
482 	 */
483 	TAILQ_FOREACH(ia4, &in_ifaddr, ia_list)
484 	{
485 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
486 			continue;
487 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
488 			return -1;
489 	}
490 
491 	/*
492 	 * perform ingress filter
493 	 */
494 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
495 		struct sockaddr_in sin;
496 		struct rtentry *rt;
497 
498 		memset(&sin, 0, sizeof(sin));
499 		sin.sin_family = AF_INET;
500 		sin.sin_len = sizeof(struct sockaddr_in);
501 		sin.sin_addr = *in;
502 		rt = rtalloc1((struct sockaddr *)&sin, 0);
503 		if (!rt || rt->rt_ifp != inifp) {
504 #if 0
505 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
506 			    "due to ingress filter\n", if_name(&sc->sc_if),
507 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
508 #endif
509 			if (rt)
510 				rtfree(rt);
511 			return -1;
512 		}
513 		rtfree(rt);
514 	}
515 
516 	return 0;
517 }
518 
519 static int
520 stf_checkaddr6(sc, in6, inifp)
521 	struct stf_softc *sc;
522 	struct in6_addr *in6;
523 	struct ifnet *inifp;	/* incoming interface */
524 {
525 	/*
526 	 * check 6to4 addresses
527 	 */
528 	if (IN6_IS_ADDR_6TO4(in6))
529 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
530 
531 	/*
532 	 * reject anything that look suspicious.  the test is implemented
533 	 * in ip6_input too, but we check here as well to
534 	 * (1) reject bad packets earlier, and
535 	 * (2) to be safe against future ip6_input change.
536 	 */
537 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
538 		return -1;
539 
540 	return 0;
541 }
542 
543 void
544 #if __STDC__
545 in_stf_input(struct mbuf *m, ...)
546 #else
547 in_stf_input(m, va_alist)
548 	struct mbuf *m;
549 #endif
550 {
551 	int off, proto;
552 	struct stf_softc *sc;
553 	struct ip *ip;
554 	struct ip6_hdr *ip6;
555 	u_int8_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((u_int32_t)itos << 20);
619 
620 	m->m_pkthdr.rcvif = ifp;
621 
622 #if NBPFILTER > 0
623 	if (ifp->if_bpf) {
624 		/*
625 		 * We need to prepend the address family as
626 		 * a four byte field.  Cons up a dummy header
627 		 * to pacify bpf.  This is safe because bpf
628 		 * will only read from the mbuf (i.e., it won't
629 		 * try to free it or keep a pointer a to it).
630 		 */
631 		struct mbuf m0;
632 		u_int32_t af = AF_INET6;
633 
634 		m0.m_next = m;
635 		m0.m_len = 4;
636 		m0.m_data = (char *)&af;
637 
638 #ifdef HAVE_OLD_BPF
639 		bpf_mtap(ifp, &m0);
640 #else
641 		bpf_mtap(ifp->if_bpf, &m0);
642 #endif
643 	}
644 #endif /*NBPFILTER > 0*/
645 
646 	/*
647 	 * Put the packet to the network layer input queue according to the
648 	 * specified address family.
649 	 * See net/if_gif.c for possible issues with packet processing
650 	 * reorder due to extra queueing.
651 	 */
652 	ifq = &ip6intrq;
653 	isr = NETISR_IPV6;
654 
655 	s = splnet();
656 	if (IF_QFULL(ifq)) {
657 		IF_DROP(ifq);	/* update statistics */
658 		m_freem(m);
659 		splx(s);
660 		return;
661 	}
662 	IF_ENQUEUE(ifq, m);
663 	schednetisr(isr);
664 	ifp->if_ipackets++;
665 	ifp->if_ibytes += m->m_pkthdr.len;
666 	splx(s);
667 }
668 
669 /* ARGSUSED */
670 static void
671 stf_rtrequest(cmd, rt, info)
672 	int cmd;
673 	struct rtentry *rt;
674 	struct rt_addrinfo *info;
675 {
676 
677 	if (rt)
678 		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
679 }
680 
681 static int
682 stf_ioctl(ifp, cmd, data)
683 	struct ifnet *ifp;
684 	u_long cmd;
685 	caddr_t data;
686 {
687 	struct ifaddr *ifa;
688 	struct ifreq *ifr;
689 	struct sockaddr_in6 *sin6;
690 	int error;
691 
692 	error = 0;
693 	switch (cmd) {
694 	case SIOCSIFADDR:
695 		ifa = (struct ifaddr *)data;
696 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
697 			error = EAFNOSUPPORT;
698 			break;
699 		}
700 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
701 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
702 			ifa->ifa_rtrequest = stf_rtrequest;
703 			ifp->if_flags |= IFF_UP;
704 		} else
705 			error = EINVAL;
706 		break;
707 
708 	case SIOCADDMULTI:
709 	case SIOCDELMULTI:
710 		ifr = (struct ifreq *)data;
711 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
712 			;
713 		else
714 			error = EAFNOSUPPORT;
715 		break;
716 
717 	default:
718 		error = EINVAL;
719 		break;
720 	}
721 
722 	return error;
723 }
724