if_stf.c revision 103475
1/*	$FreeBSD: head/sys/net/if_stf.c 103475 2002-09-17 10:45:51Z ume $	*/
2/*	$KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi 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 "opt_inet.h"
78#include "opt_inet6.h"
79
80#include <sys/param.h>
81#include <sys/systm.h>
82#include <sys/socket.h>
83#include <sys/sockio.h>
84#include <sys/mbuf.h>
85#include <sys/errno.h>
86#include <sys/kernel.h>
87#include <sys/protosw.h>
88#include <sys/queue.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 <net/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 STFNAME		"stf"
119
120#define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
121#define GET_V4(x)	((struct in_addr *)(&(x)->s6_addr16[1]))
122
123struct stf_softc {
124	struct ifnet	sc_if;	   /* common area */
125	union {
126		struct route  __sc_ro4;
127		struct route_in6 __sc_ro6; /* just for safety */
128	} __sc_ro46;
129#define sc_ro	__sc_ro46.__sc_ro4
130	const struct encaptab *encap_cookie;
131	LIST_ENTRY(stf_softc) sc_list;	/* all stf's are linked */
132};
133
134static LIST_HEAD(, stf_softc) stf_softc_list;
135
136static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
137static int ip_stf_ttl = 40;
138
139extern  struct domain inetdomain;
140struct protosw in_stf_protosw =
141{ SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
142  in_stf_input,	(pr_output_t*)rip_output, 0,	rip_ctloutput,
143  0,
144  0,            0,              0,              0,
145  &rip_usrreqs
146};
147
148static int stfmodevent(module_t, int, void *);
149static int stf_encapcheck(const struct mbuf *, int, int, void *);
150static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
151static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
152	struct rtentry *);
153static int isrfc1918addr(struct in_addr *);
154static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
155	struct ifnet *);
156static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
157	struct ifnet *);
158static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
159static int stf_ioctl(struct ifnet *, u_long, caddr_t);
160
161int	stf_clone_create(struct if_clone *, int);
162void	stf_clone_destroy(struct ifnet *);
163
164/* only one clone is currently allowed */
165struct if_clone stf_cloner =
166    IF_CLONE_INITIALIZER(STFNAME, stf_clone_create, stf_clone_destroy, 0, 0);
167
168int
169stf_clone_create(ifc, unit)
170	struct if_clone *ifc;
171	int unit;
172{
173	struct stf_softc *sc;
174
175	sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
176	sc->sc_if.if_name = STFNAME;
177	sc->sc_if.if_unit = unit;
178
179	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
180	    stf_encapcheck, &in_stf_protosw, sc);
181	if (sc->encap_cookie == NULL) {
182		printf("%s: attach failed\n", if_name(&sc->sc_if));
183		free(sc, M_STF);
184		return (ENOMEM);
185	}
186
187	sc->sc_if.if_mtu    = IPV6_MMTU;
188	sc->sc_if.if_ioctl  = stf_ioctl;
189	sc->sc_if.if_output = stf_output;
190	sc->sc_if.if_type   = IFT_STF;
191	sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
192	if_attach(&sc->sc_if);
193	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
194	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
195	return (0);
196}
197
198void
199stf_clone_destroy(ifp)
200	struct ifnet *ifp;
201{
202	int err;
203	struct stf_softc *sc = (void *) ifp;
204
205	LIST_REMOVE(sc, sc_list);
206	err = encap_detach(sc->encap_cookie);
207	KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
208	bpfdetach(ifp);
209	if_detach(ifp);
210
211	free(sc, M_STF);
212}
213
214static int
215stfmodevent(mod, type, data)
216	module_t mod;
217	int type;
218	void *data;
219{
220
221	switch (type) {
222	case MOD_LOAD:
223		LIST_INIT(&stf_softc_list);
224		if_clone_attach(&stf_cloner);
225
226		break;
227	case MOD_UNLOAD:
228		if_clone_detach(&stf_cloner);
229
230		while (!LIST_EMPTY(&stf_softc_list))
231			stf_clone_destroy(&LIST_FIRST(&stf_softc_list)->sc_if);
232		break;
233	}
234
235	return (0);
236}
237
238static moduledata_t stf_mod = {
239	"if_stf",
240	stfmodevent,
241	0
242};
243
244DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
245
246static int
247stf_encapcheck(m, off, proto, arg)
248	const struct mbuf *m;
249	int off;
250	int proto;
251	void *arg;
252{
253	struct ip ip;
254	struct in6_ifaddr *ia6;
255	struct stf_softc *sc;
256	struct in_addr a, b;
257
258	sc = (struct stf_softc *)arg;
259	if (sc == NULL)
260		return 0;
261
262	if ((sc->sc_if.if_flags & IFF_UP) == 0)
263		return 0;
264
265	/* IFF_LINK0 means "no decapsulation" */
266	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
267		return 0;
268
269	if (proto != IPPROTO_IPV6)
270		return 0;
271
272	/* LINTED const cast */
273	m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
274
275	if (ip.ip_v != 4)
276		return 0;
277
278	ia6 = stf_getsrcifa6(&sc->sc_if);
279	if (ia6 == NULL)
280		return 0;
281
282	/*
283	 * check if IPv4 dst matches the IPv4 address derived from the
284	 * local 6to4 address.
285	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
286	 */
287	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
288	    sizeof(ip.ip_dst)) != 0)
289		return 0;
290
291	/*
292	 * check if IPv4 src matches the IPv4 address derived from the
293	 * local 6to4 address masked by prefixmask.
294	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
295	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
296	 */
297	bzero(&a, sizeof(a));
298	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
299	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
300	b = ip.ip_src;
301	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
302	if (a.s_addr != b.s_addr)
303		return 0;
304
305	/* stf interface makes single side match only */
306	return 32;
307}
308
309static struct in6_ifaddr *
310stf_getsrcifa6(ifp)
311	struct ifnet *ifp;
312{
313	struct ifaddr *ia;
314	struct in_ifaddr *ia4;
315	struct sockaddr_in6 *sin6;
316	struct in_addr in;
317
318	for (ia = TAILQ_FIRST(&ifp->if_addrlist);
319	     ia;
320	     ia = TAILQ_NEXT(ia, ifa_list))
321	{
322		if (ia->ifa_addr == NULL)
323			continue;
324		if (ia->ifa_addr->sa_family != AF_INET6)
325			continue;
326		sin6 = (struct sockaddr_in6 *)ia->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		LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
332			if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
333				break;
334		if (ia4 == NULL)
335			continue;
336
337		return (struct in6_ifaddr *)ia;
338	}
339
340	return NULL;
341}
342
343static int
344stf_output(ifp, m, dst, rt)
345	struct ifnet *ifp;
346	struct mbuf *m;
347	struct sockaddr *dst;
348	struct rtentry *rt;
349{
350	struct stf_softc *sc;
351	struct sockaddr_in6 *dst6;
352	struct in_addr *in4;
353	struct sockaddr_in *dst4;
354	u_int8_t tos;
355	struct ip *ip;
356	struct ip6_hdr *ip6;
357	struct in6_ifaddr *ia6;
358
359	sc = (struct stf_softc*)ifp;
360	dst6 = (struct sockaddr_in6 *)dst;
361
362	/* just in case */
363	if ((ifp->if_flags & IFF_UP) == 0) {
364		m_freem(m);
365		return ENETDOWN;
366	}
367
368	/*
369	 * If we don't have an ip4 address that match my inner ip6 address,
370	 * we shouldn't generate output.  Without this check, we'll end up
371	 * using wrong IPv4 source.
372	 */
373	ia6 = stf_getsrcifa6(ifp);
374	if (ia6 == NULL) {
375		m_freem(m);
376		return ENETDOWN;
377	}
378
379	if (m->m_len < sizeof(*ip6)) {
380		m = m_pullup(m, sizeof(*ip6));
381		if (!m)
382			return ENOBUFS;
383	}
384	ip6 = mtod(m, struct ip6_hdr *);
385	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
386
387	/*
388	 * Pickup the right outer dst addr from the list of candidates.
389	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
390	 */
391	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
392		in4 = GET_V4(&ip6->ip6_dst);
393	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
394		in4 = GET_V4(&dst6->sin6_addr);
395	else {
396		m_freem(m);
397		return ENETUNREACH;
398	}
399
400#if NBPFILTER > 0
401	if (ifp->if_bpf) {
402		/*
403		 * We need to prepend the address family as
404		 * a four byte field.  Cons up a dummy header
405		 * to pacify bpf.  This is safe because bpf
406		 * will only read from the mbuf (i.e., it won't
407		 * try to free it or keep a pointer a to it).
408		 */
409		struct mbuf m0;
410		u_int32_t af = AF_INET6;
411
412		m0.m_next = m;
413		m0.m_len = 4;
414		m0.m_data = (char *)&af;
415
416#ifdef HAVE_OLD_BPF
417		bpf_mtap(ifp, &m0);
418#else
419		bpf_mtap(ifp->if_bpf, &m0);
420#endif
421	}
422#endif /*NBPFILTER > 0*/
423
424	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
425	if (m && m->m_len < sizeof(struct ip))
426		m = m_pullup(m, sizeof(struct ip));
427	if (m == NULL)
428		return ENOBUFS;
429	ip = mtod(m, struct ip *);
430
431	bzero(ip, sizeof(*ip));
432
433	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
434	    &ip->ip_src, sizeof(ip->ip_src));
435	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
436	ip->ip_p = IPPROTO_IPV6;
437	ip->ip_ttl = ip_stf_ttl;
438	ip->ip_len = m->m_pkthdr.len;	/*host order*/
439	if (ifp->if_flags & IFF_LINK1)
440		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
441	else
442		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
443
444	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
445	if (dst4->sin_family != AF_INET ||
446	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
447		/* cache route doesn't match */
448		dst4->sin_family = AF_INET;
449		dst4->sin_len = sizeof(struct sockaddr_in);
450		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
451		if (sc->sc_ro.ro_rt) {
452			RTFREE(sc->sc_ro.ro_rt);
453			sc->sc_ro.ro_rt = NULL;
454		}
455	}
456
457	if (sc->sc_ro.ro_rt == NULL) {
458		rtalloc(&sc->sc_ro);
459		if (sc->sc_ro.ro_rt == NULL) {
460			m_freem(m);
461			return ENETUNREACH;
462		}
463	}
464
465	return ip_output(m, NULL, &sc->sc_ro, 0, NULL);
466}
467
468static int
469isrfc1918addr(in)
470	struct in_addr *in;
471{
472	/*
473	 * returns 1 if private address range:
474	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
475	 */
476	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
477	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
478	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
479		return 1;
480
481	return 0;
482}
483
484static int
485stf_checkaddr4(sc, in, inifp)
486	struct stf_softc *sc;
487	struct in_addr *in;
488	struct ifnet *inifp;	/* incoming interface */
489{
490	struct in_ifaddr *ia4;
491
492	/*
493	 * reject packets with the following address:
494	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
495	 */
496	if (IN_MULTICAST(ntohl(in->s_addr)))
497		return -1;
498	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
499	case 0: case 127: case 255:
500		return -1;
501	}
502
503	/*
504	 * reject packets with private address range.
505	 * (requirement from RFC3056 section 2 1st paragraph)
506	 */
507	if (isrfc1918addr(in))
508		return -1;
509
510	/*
511	 * reject packets with broadcast
512	 */
513	for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
514	     ia4;
515	     ia4 = TAILQ_NEXT(ia4, ia_link))
516	{
517		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
518			continue;
519		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
520			return -1;
521	}
522
523	/*
524	 * perform ingress filter
525	 */
526	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
527		struct sockaddr_in sin;
528		struct rtentry *rt;
529
530		bzero(&sin, sizeof(sin));
531		sin.sin_family = AF_INET;
532		sin.sin_len = sizeof(struct sockaddr_in);
533		sin.sin_addr = *in;
534		rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
535		if (!rt || rt->rt_ifp != inifp) {
536#if 0
537			log(LOG_WARNING, "%s: packet from 0x%x dropped "
538			    "due to ingress filter\n", if_name(&sc->sc_if),
539			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
540#endif
541			if (rt)
542				rtfree(rt);
543			return -1;
544		}
545		rtfree(rt);
546	}
547
548	return 0;
549}
550
551static int
552stf_checkaddr6(sc, in6, inifp)
553	struct stf_softc *sc;
554	struct in6_addr *in6;
555	struct ifnet *inifp;	/* incoming interface */
556{
557	/*
558	 * check 6to4 addresses
559	 */
560	if (IN6_IS_ADDR_6TO4(in6))
561		return stf_checkaddr4(sc, GET_V4(in6), inifp);
562
563	/*
564	 * reject anything that look suspicious.  the test is implemented
565	 * in ip6_input too, but we check here as well to
566	 * (1) reject bad packets earlier, and
567	 * (2) to be safe against future ip6_input change.
568	 */
569	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
570		return -1;
571
572	return 0;
573}
574
575void
576in_stf_input(m, off)
577	struct mbuf *m;
578	int off;
579{
580	int proto;
581	struct stf_softc *sc;
582	struct ip *ip;
583	struct ip6_hdr *ip6;
584	u_int8_t otos, itos;
585	int len, isr;
586	struct ifqueue *ifq = NULL;
587	struct ifnet *ifp;
588
589	proto = mtod(m, struct ip *)->ip_p;
590
591	if (proto != IPPROTO_IPV6) {
592		m_freem(m);
593		return;
594	}
595
596	ip = mtod(m, struct ip *);
597
598	sc = (struct stf_softc *)encap_getarg(m);
599
600	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
601		m_freem(m);
602		return;
603	}
604
605	ifp = &sc->sc_if;
606
607	/*
608	 * perform sanity check against outer src/dst.
609	 * for source, perform ingress filter as well.
610	 */
611	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
612	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
613		m_freem(m);
614		return;
615	}
616
617	otos = ip->ip_tos;
618	m_adj(m, off);
619
620	if (m->m_len < sizeof(*ip6)) {
621		m = m_pullup(m, sizeof(*ip6));
622		if (!m)
623			return;
624	}
625	ip6 = mtod(m, struct ip6_hdr *);
626
627	/*
628	 * perform sanity check against inner src/dst.
629	 * for source, perform ingress filter as well.
630	 */
631	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
632	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
633		m_freem(m);
634		return;
635	}
636
637	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
638	if ((ifp->if_flags & IFF_LINK1) != 0)
639		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
640	else
641		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
642	ip6->ip6_flow &= ~htonl(0xff << 20);
643	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
644
645	m->m_pkthdr.rcvif = ifp;
646
647	if (ifp->if_bpf) {
648		/*
649		 * We need to prepend the address family as
650		 * a four byte field.  Cons up a dummy header
651		 * to pacify bpf.  This is safe because bpf
652		 * will only read from the mbuf (i.e., it won't
653		 * try to free it or keep a pointer a to it).
654		 */
655		struct mbuf m0;
656		u_int32_t af = AF_INET6;
657
658		m0.m_next = m;
659		m0.m_len = 4;
660		m0.m_data = (char *)&af;
661
662#ifdef HAVE_OLD_BPF
663		bpf_mtap(ifp, &m0);
664#else
665		bpf_mtap(ifp->if_bpf, &m0);
666#endif
667	}
668
669	/*
670	 * Put the packet to the network layer input queue according to the
671	 * specified address family.
672	 * See net/if_gif.c for possible issues with packet processing
673	 * reorder due to extra queueing.
674	 */
675	ifq = &ip6intrq;
676	isr = NETISR_IPV6;
677
678	len = m->m_pkthdr.len;
679	if (! IF_HANDOFF(ifq, m, NULL))
680		return;
681	schednetisr(isr);
682	ifp->if_ipackets++;
683	ifp->if_ibytes += len;
684}
685
686/* ARGSUSED */
687static void
688stf_rtrequest(cmd, rt, info)
689	int cmd;
690	struct rtentry *rt;
691	struct rt_addrinfo *info;
692{
693
694	if (rt)
695		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
696}
697
698static int
699stf_ioctl(ifp, cmd, data)
700	struct ifnet *ifp;
701	u_long cmd;
702	caddr_t data;
703{
704	struct ifaddr *ifa;
705	struct ifreq *ifr;
706	struct sockaddr_in6 *sin6;
707	int error;
708
709	error = 0;
710	switch (cmd) {
711	case SIOCSIFADDR:
712		ifa = (struct ifaddr *)data;
713		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
714			error = EAFNOSUPPORT;
715			break;
716		}
717		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
718		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
719		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
720			ifa->ifa_rtrequest = stf_rtrequest;
721			ifp->if_flags |= IFF_UP;
722		} else
723			error = EINVAL;
724		break;
725
726	case SIOCADDMULTI:
727	case SIOCDELMULTI:
728		ifr = (struct ifreq *)data;
729		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
730			;
731		else
732			error = EAFNOSUPPORT;
733		break;
734
735	default:
736		error = EINVAL;
737		break;
738	}
739
740	return error;
741}
742