xref: /freebsd/sys/net/if_stf.c (revision eacee0ff7ec955b32e09515246bd97b6edcd2b0f)
1 /*	$FreeBSD$	*/
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 "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/bus.h>	/* XXX: Shouldn't really be required! */
90 #include <sys/rman.h>
91 #include <machine/cpu.h>
92 
93 #include <sys/malloc.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_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 <net/bpf.h>
119 
120 #define STFNAME		"stf"
121 #define STF_MAXUNIT	0	/* only one is currently allowed */
122 
123 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
124 #define GET_V4(x)	((struct in_addr *)(&(x)->s6_addr16[1]))
125 
126 struct stf_softc {
127 	struct ifnet	sc_if;	   /* common area */
128 	union {
129 		struct route  __sc_ro4;
130 		struct route_in6 __sc_ro6; /* just for safety */
131 	} __sc_ro46;
132 #define sc_ro	__sc_ro46.__sc_ro4
133 	const struct encaptab *encap_cookie;
134 	struct resource *r_unit;	/* resource allocated for this unit */
135 	LIST_ENTRY(stf_softc) sc_list;	/* all stf's are linked */
136 };
137 
138 static LIST_HEAD(, stf_softc) stf_softc_list;
139 
140 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
141 static struct rman stfunits[1];
142 static int ip_stf_ttl = 40;
143 
144 extern  struct domain inetdomain;
145 struct protosw in_stf_protosw =
146 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
147   in_stf_input, rip_output,	0,		rip_ctloutput,
148   0,
149   0,            0,              0,              0,
150   &rip_usrreqs
151 };
152 
153 static int stfmodevent __P((module_t, int, void *));
154 static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
155 static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
156 static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
157 	struct rtentry *));
158 static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
159 	struct ifnet *));
160 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
161 	struct ifnet *));
162 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
163 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
164 
165 int	stf_clone_create __P((struct if_clone *, int *));
166 void	stf_clone_destroy __P((struct ifnet *));
167 
168 struct if_clone stf_cloner =
169     IF_CLONE_INITIALIZER(STFNAME, stf_clone_create, stf_clone_destroy);
170 
171 int
172 stf_clone_create(ifc, unit)
173 	struct if_clone *ifc;
174 	int *unit;
175 {
176 	struct resource *r;
177 	struct stf_softc *sc;
178 
179 	if (*unit > STF_MAXUNIT)
180 		return (ENXIO);
181 
182 	if (*unit < 0) {
183 		 r = rman_reserve_resource(stfunits, 0, STF_MAXUNIT, 1,
184 		     RF_ALLOCATED | RF_ACTIVE, NULL);
185 		 if (r == NULL)
186 			return (ENOSPC);
187 		 *unit = rman_get_start(r);
188 	} else {
189 		r = rman_reserve_resource(stfunits, *unit, *unit, 1,
190 		    RF_ALLOCATED | RF_ACTIVE, NULL);
191 		if (r == NULL)
192 			 return (EEXIST);
193 	}
194 
195 	sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
196 	sc->sc_if.if_name = STFNAME;
197 	sc->sc_if.if_unit = *unit;
198 	sc->r_unit = r;
199 
200 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
201 	    stf_encapcheck, &in_stf_protosw, sc);
202 	if (sc->encap_cookie == NULL) {
203 		printf("%s: attach failed\n", if_name(&sc->sc_if));
204 		free(sc, M_STF);
205 		return (ENOMEM);
206 	}
207 
208 	sc->sc_if.if_mtu    = IPV6_MMTU;
209 	sc->sc_if.if_ioctl  = stf_ioctl;
210 	sc->sc_if.if_output = stf_output;
211 	sc->sc_if.if_type   = IFT_STF;
212 	sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
213 	if_attach(&sc->sc_if);
214 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
215 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
216 	return (0);
217 }
218 
219 void
220 stf_clone_destroy(ifp)
221 	struct ifnet *ifp;
222 {
223 	int err;
224 	struct stf_softc *sc = (void *) ifp;
225 
226 	LIST_REMOVE(sc, sc_list);
227 	err = encap_detach(sc->encap_cookie);
228 	KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
229 	bpfdetach(ifp);
230 	if_detach(ifp);
231 
232 	err = rman_release_resource(sc->r_unit);
233 	KASSERT(err == 0, ("Unexpected error freeing resource"));
234 
235 	free(sc, M_STF);
236 }
237 
238 static int
239 stfmodevent(mod, type, data)
240 	module_t mod;
241 	int type;
242 	void *data;
243 {
244 	int err;
245 
246 	switch (type) {
247 	case MOD_LOAD:
248 		stfunits->rm_type = RMAN_ARRAY;
249 		stfunits->rm_descr = "configurable if_stf units";
250 		err = rman_init(stfunits);
251 		if (err != 0)
252 			return (err);
253 		err = rman_manage_region(stfunits, 0, STF_MAXUNIT);
254 		if (err != 0) {
255 			printf("%s: stfunits: rman_manage_region: Failed %d\n",
256 			    STFNAME, err);
257 			rman_fini(stfunits);
258 			return (err);
259 		}
260 		LIST_INIT(&stf_softc_list);
261 		if_clone_attach(&stf_cloner);
262 
263 		break;
264 	case MOD_UNLOAD:
265 		if_clone_detach(&stf_cloner);
266 
267 		while (!LIST_EMPTY(&stf_softc_list))
268 			stf_clone_destroy(&LIST_FIRST(&stf_softc_list)->sc_if);
269 
270 		err = rman_fini(stfunits);
271 		KASSERT(err == 0, ("Unexpected error freeing resource"));
272 
273 		break;
274 	}
275 
276 	return (0);
277 }
278 
279 static moduledata_t stf_mod = {
280 	"if_stf",
281 	stfmodevent,
282 	0
283 };
284 
285 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
286 
287 static int
288 stf_encapcheck(m, off, proto, arg)
289 	const struct mbuf *m;
290 	int off;
291 	int proto;
292 	void *arg;
293 {
294 	struct ip ip;
295 	struct in6_ifaddr *ia6;
296 	struct stf_softc *sc;
297 	struct in_addr a, b;
298 
299 	sc = (struct stf_softc *)arg;
300 	if (sc == NULL)
301 		return 0;
302 
303 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
304 		return 0;
305 
306 	/* IFF_LINK0 means "no decapsulation" */
307 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
308 		return 0;
309 
310 	if (proto != IPPROTO_IPV6)
311 		return 0;
312 
313 	/* LINTED const cast */
314 	m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
315 
316 	if (ip.ip_v != 4)
317 		return 0;
318 
319 	ia6 = stf_getsrcifa6(&sc->sc_if);
320 	if (ia6 == NULL)
321 		return 0;
322 
323 	/*
324 	 * check if IPv4 dst matches the IPv4 address derived from the
325 	 * local 6to4 address.
326 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
327 	 */
328 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
329 	    sizeof(ip.ip_dst)) != 0)
330 		return 0;
331 
332 	/*
333 	 * check if IPv4 src matches the IPv4 address derived from the
334 	 * local 6to4 address masked by prefixmask.
335 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
336 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
337 	 */
338 	bzero(&a, sizeof(a));
339 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
340 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
341 	b = ip.ip_src;
342 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
343 	if (a.s_addr != b.s_addr)
344 		return 0;
345 
346 	/* stf interface makes single side match only */
347 	return 32;
348 }
349 
350 static struct in6_ifaddr *
351 stf_getsrcifa6(ifp)
352 	struct ifnet *ifp;
353 {
354 	struct ifaddr *ia;
355 	struct in_ifaddr *ia4;
356 	struct sockaddr_in6 *sin6;
357 	struct in_addr in;
358 
359 	for (ia = TAILQ_FIRST(&ifp->if_addrlist);
360 	     ia;
361 	     ia = TAILQ_NEXT(ia, ifa_list))
362 	{
363 		if (ia->ifa_addr == NULL)
364 			continue;
365 		if (ia->ifa_addr->sa_family != AF_INET6)
366 			continue;
367 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
368 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
369 			continue;
370 
371 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
372 		LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
373 			if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
374 				break;
375 		if (ia4 == NULL)
376 			continue;
377 
378 		return (struct in6_ifaddr *)ia;
379 	}
380 
381 	return NULL;
382 }
383 
384 static int
385 stf_output(ifp, m, dst, rt)
386 	struct ifnet *ifp;
387 	struct mbuf *m;
388 	struct sockaddr *dst;
389 	struct rtentry *rt;
390 {
391 	struct stf_softc *sc;
392 	struct sockaddr_in6 *dst6;
393 	struct in_addr *in4;
394 	struct sockaddr_in *dst4;
395 	u_int8_t tos;
396 	struct ip *ip;
397 	struct ip6_hdr *ip6;
398 	struct in6_ifaddr *ia6;
399 
400 	sc = (struct stf_softc*)ifp;
401 	dst6 = (struct sockaddr_in6 *)dst;
402 
403 	/* just in case */
404 	if ((ifp->if_flags & IFF_UP) == 0) {
405 		m_freem(m);
406 		return ENETDOWN;
407 	}
408 
409 	/*
410 	 * If we don't have an ip4 address that match my inner ip6 address,
411 	 * we shouldn't generate output.  Without this check, we'll end up
412 	 * using wrong IPv4 source.
413 	 */
414 	ia6 = stf_getsrcifa6(ifp);
415 	if (ia6 == NULL) {
416 		m_freem(m);
417 		return ENETDOWN;
418 	}
419 
420 	if (m->m_len < sizeof(*ip6)) {
421 		m = m_pullup(m, sizeof(*ip6));
422 		if (!m)
423 			return ENOBUFS;
424 	}
425 	ip6 = mtod(m, struct ip6_hdr *);
426 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
427 
428 	/*
429 	 * Pickup the right outer dst addr from the list of candidates.
430 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
431 	 */
432 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
433 		in4 = GET_V4(&ip6->ip6_dst);
434 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
435 		in4 = GET_V4(&dst6->sin6_addr);
436 	else {
437 		m_freem(m);
438 		return ENETUNREACH;
439 	}
440 
441 #if NBPFILTER > 0
442 	if (ifp->if_bpf) {
443 		/*
444 		 * We need to prepend the address family as
445 		 * a four byte field.  Cons up a dummy header
446 		 * to pacify bpf.  This is safe because bpf
447 		 * will only read from the mbuf (i.e., it won't
448 		 * try to free it or keep a pointer a to it).
449 		 */
450 		struct mbuf m0;
451 		u_int32_t af = AF_INET6;
452 
453 		m0.m_next = m;
454 		m0.m_len = 4;
455 		m0.m_data = (char *)&af;
456 
457 #ifdef HAVE_OLD_BPF
458 		bpf_mtap(ifp, &m0);
459 #else
460 		bpf_mtap(ifp->if_bpf, &m0);
461 #endif
462 	}
463 #endif /*NBPFILTER > 0*/
464 
465 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
466 	if (m && m->m_len < sizeof(struct ip))
467 		m = m_pullup(m, sizeof(struct ip));
468 	if (m == NULL)
469 		return ENOBUFS;
470 	ip = mtod(m, struct ip *);
471 
472 	bzero(ip, sizeof(*ip));
473 
474 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
475 	    &ip->ip_src, sizeof(ip->ip_src));
476 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
477 	ip->ip_p = IPPROTO_IPV6;
478 	ip->ip_ttl = ip_stf_ttl;
479 	ip->ip_len = m->m_pkthdr.len;	/*host order*/
480 	if (ifp->if_flags & IFF_LINK1)
481 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
482 	else
483 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
484 
485 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
486 	if (dst4->sin_family != AF_INET ||
487 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
488 		/* cache route doesn't match */
489 		dst4->sin_family = AF_INET;
490 		dst4->sin_len = sizeof(struct sockaddr_in);
491 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
492 		if (sc->sc_ro.ro_rt) {
493 			RTFREE(sc->sc_ro.ro_rt);
494 			sc->sc_ro.ro_rt = NULL;
495 		}
496 	}
497 
498 	if (sc->sc_ro.ro_rt == NULL) {
499 		rtalloc(&sc->sc_ro);
500 		if (sc->sc_ro.ro_rt == NULL) {
501 			m_freem(m);
502 			return ENETUNREACH;
503 		}
504 	}
505 
506 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL);
507 }
508 
509 static int
510 stf_checkaddr4(sc, in, inifp)
511 	struct stf_softc *sc;
512 	struct in_addr *in;
513 	struct ifnet *inifp;	/* incoming interface */
514 {
515 	struct in_ifaddr *ia4;
516 
517 	/*
518 	 * reject packets with the following address:
519 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
520 	 */
521 	if (IN_MULTICAST(ntohl(in->s_addr)))
522 		return -1;
523 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
524 	case 0: case 127: case 255:
525 		return -1;
526 	}
527 
528 	/*
529 	 * reject packets with broadcast
530 	 */
531 	for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
532 	     ia4;
533 	     ia4 = TAILQ_NEXT(ia4, ia_link))
534 	{
535 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
536 			continue;
537 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
538 			return -1;
539 	}
540 
541 	/*
542 	 * perform ingress filter
543 	 */
544 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
545 		struct sockaddr_in sin;
546 		struct rtentry *rt;
547 
548 		bzero(&sin, sizeof(sin));
549 		sin.sin_family = AF_INET;
550 		sin.sin_len = sizeof(struct sockaddr_in);
551 		sin.sin_addr = *in;
552 		rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
553 		if (!rt || rt->rt_ifp != inifp) {
554 #if 0
555 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
556 			    "due to ingress filter\n", if_name(&sc->sc_if),
557 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
558 #endif
559 			if (rt)
560 				rtfree(rt);
561 			return -1;
562 		}
563 		rtfree(rt);
564 	}
565 
566 	return 0;
567 }
568 
569 static int
570 stf_checkaddr6(sc, in6, inifp)
571 	struct stf_softc *sc;
572 	struct in6_addr *in6;
573 	struct ifnet *inifp;	/* incoming interface */
574 {
575 	/*
576 	 * check 6to4 addresses
577 	 */
578 	if (IN6_IS_ADDR_6TO4(in6))
579 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
580 
581 	/*
582 	 * reject anything that look suspicious.  the test is implemented
583 	 * in ip6_input too, but we check here as well to
584 	 * (1) reject bad packets earlier, and
585 	 * (2) to be safe against future ip6_input change.
586 	 */
587 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
588 		return -1;
589 
590 	return 0;
591 }
592 
593 void
594 in_stf_input(m, off)
595 	struct mbuf *m;
596 	int off;
597 {
598 	int proto;
599 	struct stf_softc *sc;
600 	struct ip *ip;
601 	struct ip6_hdr *ip6;
602 	u_int8_t otos, itos;
603 	int len, isr;
604 	struct ifqueue *ifq = NULL;
605 	struct ifnet *ifp;
606 
607 	proto = mtod(m, struct ip *)->ip_p;
608 
609 	if (proto != IPPROTO_IPV6) {
610 		m_freem(m);
611 		return;
612 	}
613 
614 	ip = mtod(m, struct ip *);
615 
616 	sc = (struct stf_softc *)encap_getarg(m);
617 
618 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
619 		m_freem(m);
620 		return;
621 	}
622 
623 	ifp = &sc->sc_if;
624 
625 	/*
626 	 * perform sanity check against outer src/dst.
627 	 * for source, perform ingress filter as well.
628 	 */
629 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
630 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
631 		m_freem(m);
632 		return;
633 	}
634 
635 	otos = ip->ip_tos;
636 	m_adj(m, off);
637 
638 	if (m->m_len < sizeof(*ip6)) {
639 		m = m_pullup(m, sizeof(*ip6));
640 		if (!m)
641 			return;
642 	}
643 	ip6 = mtod(m, struct ip6_hdr *);
644 
645 	/*
646 	 * perform sanity check against inner src/dst.
647 	 * for source, perform ingress filter as well.
648 	 */
649 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
650 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
651 		m_freem(m);
652 		return;
653 	}
654 
655 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
656 	if ((ifp->if_flags & IFF_LINK1) != 0)
657 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
658 	else
659 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
660 	ip6->ip6_flow &= ~htonl(0xff << 20);
661 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
662 
663 	m->m_pkthdr.rcvif = ifp;
664 
665 	if (ifp->if_bpf) {
666 		/*
667 		 * We need to prepend the address family as
668 		 * a four byte field.  Cons up a dummy header
669 		 * to pacify bpf.  This is safe because bpf
670 		 * will only read from the mbuf (i.e., it won't
671 		 * try to free it or keep a pointer a to it).
672 		 */
673 		struct mbuf m0;
674 		u_int32_t af = AF_INET6;
675 
676 		m0.m_next = m;
677 		m0.m_len = 4;
678 		m0.m_data = (char *)&af;
679 
680 #ifdef HAVE_OLD_BPF
681 		bpf_mtap(ifp, &m0);
682 #else
683 		bpf_mtap(ifp->if_bpf, &m0);
684 #endif
685 	}
686 
687 	/*
688 	 * Put the packet to the network layer input queue according to the
689 	 * specified address family.
690 	 * See net/if_gif.c for possible issues with packet processing
691 	 * reorder due to extra queueing.
692 	 */
693 	ifq = &ip6intrq;
694 	isr = NETISR_IPV6;
695 
696 	len = m->m_pkthdr.len;
697 	if (! IF_HANDOFF(ifq, m, NULL))
698 		return;
699 	schednetisr(isr);
700 	ifp->if_ipackets++;
701 	ifp->if_ibytes += len;
702 }
703 
704 /* ARGSUSED */
705 static void
706 stf_rtrequest(cmd, rt, info)
707 	int cmd;
708 	struct rtentry *rt;
709 	struct rt_addrinfo *info;
710 {
711 
712 	if (rt)
713 		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
714 }
715 
716 static int
717 stf_ioctl(ifp, cmd, data)
718 	struct ifnet *ifp;
719 	u_long cmd;
720 	caddr_t data;
721 {
722 	struct ifaddr *ifa;
723 	struct ifreq *ifr;
724 	struct sockaddr_in6 *sin6;
725 	int error;
726 
727 	error = 0;
728 	switch (cmd) {
729 	case SIOCSIFADDR:
730 		ifa = (struct ifaddr *)data;
731 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
732 			error = EAFNOSUPPORT;
733 			break;
734 		}
735 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
736 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
737 			ifa->ifa_rtrequest = stf_rtrequest;
738 			ifp->if_flags |= IFF_UP;
739 		} else
740 			error = EINVAL;
741 		break;
742 
743 	case SIOCADDMULTI:
744 	case SIOCDELMULTI:
745 		ifr = (struct ifreq *)data;
746 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
747 			;
748 		else
749 			error = EAFNOSUPPORT;
750 		break;
751 
752 	default:
753 		error = EINVAL;
754 		break;
755 	}
756 
757 	return error;
758 }
759