xref: /netbsd-src/sys/net/if_stf.c (revision d909946ca08dceb44d7d0f22ec9488679695d976)
1 /*	$NetBSD: if_stf.c,v 1.99 2016/08/18 11:38:58 knakahara 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 1.99 2016/08/18 11:38:58 knakahara Exp $");
79 
80 #ifdef _KERNEL_OPT
81 #include "opt_inet.h"
82 #include "stf.h"
83 #endif
84 
85 #ifndef INET6
86 	#error "pseudo-device stf requires options INET6"
87 #endif
88 
89 #include <sys/param.h>
90 #include <sys/systm.h>
91 #include <sys/socket.h>
92 #include <sys/sockio.h>
93 #include <sys/mbuf.h>
94 #include <sys/errno.h>
95 #include <sys/ioctl.h>
96 #include <sys/proc.h>
97 #include <sys/queue.h>
98 #include <sys/syslog.h>
99 #include <sys/device.h>
100 #include <sys/module.h>
101 
102 #include <sys/cpu.h>
103 
104 #include <net/if.h>
105 #include <net/route.h>
106 #include <net/netisr.h>
107 #include <net/if_types.h>
108 #include <net/if_stf.h>
109 
110 #include <netinet/in.h>
111 #include <netinet/in_systm.h>
112 #include <netinet/ip.h>
113 #include <netinet/ip_var.h>
114 #include <netinet/in_var.h>
115 
116 #include <netinet/ip6.h>
117 #include <netinet6/ip6_var.h>
118 #include <netinet6/in6_var.h>
119 #include <netinet/ip_ecn.h>
120 
121 #include <netinet/ip_encap.h>
122 
123 #include <net/net_osdep.h>
124 
125 #include <net/bpf.h>
126 
127 #include "ioconf.h"
128 
129 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
130 #define GET_V4(x)	((const struct in_addr *)(&(x)->s6_addr16[1]))
131 
132 struct stf_softc {
133 	struct ifnet	sc_if;	   /* common area */
134 	struct route	sc_ro;
135 	const struct encaptab *encap_cookie;
136 	LIST_ENTRY(stf_softc) sc_list;
137 };
138 
139 static LIST_HEAD(, stf_softc) stf_softc_list;
140 
141 static int	stf_clone_create(struct if_clone *, int);
142 static int	stf_clone_destroy(struct ifnet *);
143 
144 struct if_clone stf_cloner =
145     IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
146 
147 static int ip_stf_ttl = STF_TTL;
148 
149 extern struct domain inetdomain;
150 
151 static const struct encapsw in_stf_encapsw =
152 {
153 	.encapsw4 = {
154 		.pr_input	= in_stf_input,
155 		.pr_ctlinput	= NULL,
156 	}
157 };
158 
159 static int stf_encapcheck(struct mbuf *, int, int, void *);
160 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
161 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
162 	const struct rtentry *);
163 static int isrfc1918addr(const struct in_addr *);
164 static int stf_checkaddr4(struct stf_softc *, const struct in_addr *,
165 	struct ifnet *);
166 static int stf_checkaddr6(struct stf_softc *, const struct in6_addr *,
167 	struct ifnet *);
168 static void stf_rtrequest(int, struct rtentry *, const struct rt_addrinfo *);
169 static int stf_ioctl(struct ifnet *, u_long, void *);
170 
171 /* ARGSUSED */
172 void
173 stfattach(int count)
174 {
175 
176 	/*
177 	 * Nothing to do here, initialization is handled by the
178 	 * module initialization code in stfinit() below).
179 	 */
180 }
181 
182 static void
183 stfinit(void)
184 {
185 
186 	LIST_INIT(&stf_softc_list);
187 	if_clone_attach(&stf_cloner);
188 }
189 
190 static int
191 stfdetach(void)
192 {
193 	int error = 0;
194 
195 	if (!LIST_EMPTY(&stf_softc_list))
196 		error = EBUSY;
197 
198 	if (error == 0)
199 		if_clone_detach(&stf_cloner);
200 
201 	return error;
202 }
203 
204 static int
205 stf_clone_create(struct if_clone *ifc, int unit)
206 {
207 	struct stf_softc *sc;
208 	int error;
209 
210 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT|M_ZERO);
211 	if_initname(&sc->sc_if, ifc->ifc_name, unit);
212 
213 	error = encap_lock_enter();
214 	if (error) {
215 		free(sc, M_DEVBUF);
216 		return error;
217 	}
218 
219 	if (LIST_FIRST(&stf_softc_list) != NULL) {
220 		/* Only one stf interface is allowed. */
221 		encap_lock_exit();
222 		free(sc, M_DEVBUF);
223 		return (EEXIST);
224 	}
225 
226 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
227 	    stf_encapcheck, &in_stf_encapsw, sc);
228 	encap_lock_exit();
229 	if (sc->encap_cookie == NULL) {
230 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
231 		free(sc, M_DEVBUF);
232 		return (EIO);	/* XXX */
233 	}
234 
235 	sc->sc_if.if_mtu    = STF_MTU;
236 	sc->sc_if.if_flags  = 0;
237 	sc->sc_if.if_ioctl  = stf_ioctl;
238 	sc->sc_if.if_output = stf_output;
239 	sc->sc_if.if_type   = IFT_STF;
240 	sc->sc_if.if_dlt    = DLT_NULL;
241 	if_attach(&sc->sc_if);
242 	if_alloc_sadl(&sc->sc_if);
243 	bpf_attach(&sc->sc_if, DLT_NULL, sizeof(u_int));
244 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
245 	return (0);
246 }
247 
248 static int
249 stf_clone_destroy(struct ifnet *ifp)
250 {
251 	struct stf_softc *sc = (void *) ifp;
252 
253 	encap_lock_enter();
254 	LIST_REMOVE(sc, sc_list);
255 	encap_detach(sc->encap_cookie);
256 	encap_lock_exit();
257 	bpf_detach(ifp);
258 	if_detach(ifp);
259 	rtcache_free(&sc->sc_ro);
260 	free(sc, M_DEVBUF);
261 
262 	return (0);
263 }
264 
265 static int
266 stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
267 {
268 	struct ip ip;
269 	struct in6_ifaddr *ia6;
270 	struct stf_softc *sc;
271 	struct in_addr a, b;
272 
273 	sc = (struct stf_softc *)arg;
274 	if (sc == NULL)
275 		return 0;
276 
277 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
278 		return 0;
279 
280 	/* IFF_LINK0 means "no decapsulation" */
281 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
282 		return 0;
283 
284 	if (proto != IPPROTO_IPV6)
285 		return 0;
286 
287 	m_copydata(m, 0, sizeof(ip), (void *)&ip);
288 
289 	if (ip.ip_v != 4)
290 		return 0;
291 
292 	ia6 = stf_getsrcifa6(&sc->sc_if);
293 	if (ia6 == NULL)
294 		return 0;
295 
296 	/*
297 	 * check if IPv4 dst matches the IPv4 address derived from the
298 	 * local 6to4 address.
299 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
300 	 */
301 	if (memcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
302 	    sizeof(ip.ip_dst)) != 0)
303 		return 0;
304 
305 	/*
306 	 * check if IPv4 src matches the IPv4 address derived from the
307 	 * local 6to4 address masked by prefixmask.
308 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
309 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
310 	 */
311 	memset(&a, 0, sizeof(a));
312 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
313 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
314 	b = ip.ip_src;
315 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
316 	if (a.s_addr != b.s_addr)
317 		return 0;
318 
319 	/* stf interface makes single side match only */
320 	return 32;
321 }
322 
323 static struct in6_ifaddr *
324 stf_getsrcifa6(struct ifnet *ifp)
325 {
326 	struct ifaddr *ifa;
327 	struct in_ifaddr *ia4;
328 	struct sockaddr_in6 *sin6;
329 	struct in_addr in;
330 	int s;
331 
332 	s = pserialize_read_enter();
333 	IFADDR_READER_FOREACH(ifa, ifp) {
334 		if (ifa->ifa_addr->sa_family != AF_INET6)
335 			continue;
336 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
337 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
338 			continue;
339 
340 		memcpy(&in, GET_V4(&sin6->sin6_addr), sizeof(in));
341 		ia4 = in_get_ia(in);
342 		if (ia4 == NULL)
343 			continue;
344 
345 		pserialize_read_exit(s);
346 		/* TODO NOMPSAFE */
347 		return (struct in6_ifaddr *)ifa;
348 	}
349 	pserialize_read_exit(s);
350 
351 	return NULL;
352 }
353 
354 static int
355 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
356     const struct rtentry *rt0)
357 {
358 	struct rtentry *rt;
359 	struct stf_softc *sc;
360 	const struct sockaddr_in6 *dst6;
361 	const struct in_addr *in4;
362 	uint8_t tos;
363 	struct ip *ip;
364 	struct ip6_hdr *ip6;
365 	struct in6_ifaddr *ia6;
366 	union {
367 		struct sockaddr		dst;
368 		struct sockaddr_in	dst4;
369 	} u;
370 
371 	sc = (struct stf_softc*)ifp;
372 	dst6 = (const struct sockaddr_in6 *)dst;
373 
374 	/* just in case */
375 	if ((ifp->if_flags & IFF_UP) == 0) {
376 		m_freem(m);
377 		return ENETDOWN;
378 	}
379 
380 	/*
381 	 * If we don't have an ip4 address that match my inner ip6 address,
382 	 * we shouldn't generate output.  Without this check, we'll end up
383 	 * using wrong IPv4 source.
384 	 */
385 	ia6 = stf_getsrcifa6(ifp);
386 	if (ia6 == NULL) {
387 		m_freem(m);
388 		ifp->if_oerrors++;
389 		return ENETDOWN;
390 	}
391 
392 	if (m->m_len < sizeof(*ip6)) {
393 		m = m_pullup(m, sizeof(*ip6));
394 		if (m == NULL) {
395 			ifp->if_oerrors++;
396 			return ENOBUFS;
397 		}
398 	}
399 	ip6 = mtod(m, struct ip6_hdr *);
400 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
401 
402 	/*
403 	 * Pickup the right outer dst addr from the list of candidates.
404 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
405 	 */
406 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
407 		in4 = GET_V4(&ip6->ip6_dst);
408 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
409 		in4 = GET_V4(&dst6->sin6_addr);
410 	else {
411 		m_freem(m);
412 		ifp->if_oerrors++;
413 		return ENETUNREACH;
414 	}
415 
416 	bpf_mtap_af(ifp, AF_INET6, m);
417 
418 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
419 	if (m && m->m_len < sizeof(struct ip))
420 		m = m_pullup(m, sizeof(struct ip));
421 	if (m == NULL) {
422 		ifp->if_oerrors++;
423 		return ENOBUFS;
424 	}
425 	ip = mtod(m, struct ip *);
426 
427 	memset(ip, 0, sizeof(*ip));
428 
429 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
430 	    &ip->ip_src, sizeof(ip->ip_src));
431 	memcpy(&ip->ip_dst, in4, sizeof(ip->ip_dst));
432 	ip->ip_p = IPPROTO_IPV6;
433 	ip->ip_ttl = ip_stf_ttl;
434 	ip->ip_len = htons(m->m_pkthdr.len);
435 	if (ifp->if_flags & IFF_LINK1)
436 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
437 	else
438 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
439 
440 	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
441 	if ((rt = rtcache_lookup(&sc->sc_ro, &u.dst)) == NULL) {
442 		m_freem(m);
443 		ifp->if_oerrors++;
444 		return ENETUNREACH;
445 	}
446 
447 	/* If the route constitutes infinite encapsulation, punt. */
448 	if (rt->rt_ifp == ifp) {
449 		rtcache_free(&sc->sc_ro);
450 		m_freem(m);
451 		ifp->if_oerrors++;
452 		return ENETUNREACH;
453 	}
454 
455 	ifp->if_opackets++;
456 	ifp->if_obytes += m->m_pkthdr.len - sizeof(struct ip);
457 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
458 }
459 
460 static int
461 isrfc1918addr(const struct in_addr *in)
462 {
463 	/*
464 	 * returns 1 if private address range:
465 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
466 	 */
467 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
468 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
469 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
470 		return 1;
471 
472 	return 0;
473 }
474 
475 static int
476 stf_checkaddr4(struct stf_softc *sc, const struct in_addr *in,
477     struct ifnet *inifp /*incoming interface*/)
478 {
479 	struct in_ifaddr *ia4;
480 
481 	/*
482 	 * reject packets with the following address:
483 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
484 	 */
485 	if (IN_MULTICAST(in->s_addr))
486 		return -1;
487 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
488 	case 0: case 127: case 255:
489 		return -1;
490 	}
491 
492 	/*
493 	 * reject packets with private address range.
494 	 * (requirement from RFC3056 section 2 1st paragraph)
495 	 */
496 	if (isrfc1918addr(in))
497 		return -1;
498 
499 	/*
500 	 * reject packet with IPv4 link-local (169.254.0.0/16),
501 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
502 	 */
503 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
504 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
505 		return -1;
506 
507 	/*
508 	 * reject packets with broadcast
509 	 */
510 	IN_ADDRLIST_READER_FOREACH(ia4) {
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 			    (uint32_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(struct stf_softc *sc, const struct in6_addr *in6,
547     struct ifnet *inifp /*incoming interface*/)
548 {
549 
550 	/*
551 	 * check 6to4 addresses
552 	 */
553 	if (IN6_IS_ADDR_6TO4(in6))
554 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
555 
556 	/*
557 	 * reject anything that look suspicious.  the test is implemented
558 	 * in ip6_input too, but we check here as well to
559 	 * (1) reject bad packets earlier, and
560 	 * (2) to be safe against future ip6_input change.
561 	 */
562 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
563 		return -1;
564 
565 	/*
566 	 * reject link-local and site-local unicast
567 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
568 	 */
569 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
570 		return -1;
571 
572 	/*
573 	 * reject node-local and link-local multicast
574 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
575 	 */
576 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
577 		return -1;
578 
579 	return 0;
580 }
581 
582 void
583 in_stf_input(struct mbuf *m, int off, int proto)
584 {
585 	int s;
586 	struct stf_softc *sc;
587 	struct ip *ip;
588 	struct ip6_hdr *ip6;
589 	uint8_t otos, itos;
590 	struct ifnet *ifp;
591 	size_t pktlen;
592 
593 	if (proto != IPPROTO_IPV6) {
594 		m_freem(m);
595 		return;
596 	}
597 
598 	ip = mtod(m, struct ip *);
599 
600 	sc = (struct stf_softc *)encap_getarg(m);
601 
602 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
603 		m_freem(m);
604 		return;
605 	}
606 
607 	ifp = &sc->sc_if;
608 
609 	/*
610 	 * perform sanity check against outer src/dst.
611 	 * for source, perform ingress filter as well.
612 	 */
613 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
614 	    stf_checkaddr4(sc, &ip->ip_src, m_get_rcvif_NOMPSAFE(m)) < 0) {
615 		m_freem(m);
616 		return;
617 	}
618 
619 	otos = ip->ip_tos;
620 	m_adj(m, off);
621 
622 	if (m->m_len < sizeof(*ip6)) {
623 		m = m_pullup(m, sizeof(*ip6));
624 		if (!m)
625 			return;
626 	}
627 	ip6 = mtod(m, struct ip6_hdr *);
628 
629 	/*
630 	 * perform sanity check against inner src/dst.
631 	 * for source, perform ingress filter as well.
632 	 */
633 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
634 	    stf_checkaddr6(sc, &ip6->ip6_src, m_get_rcvif_NOMPSAFE(m)) < 0) {
635 		m_freem(m);
636 		return;
637 	}
638 
639 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
640 	if ((ifp->if_flags & IFF_LINK1) != 0)
641 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
642 	else
643 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
644 	ip6->ip6_flow &= ~htonl(0xff << 20);
645 	ip6->ip6_flow |= htonl((uint32_t)itos << 20);
646 
647 	pktlen = m->m_pkthdr.len;
648 	m_set_rcvif(m, ifp);
649 
650 	bpf_mtap_af(ifp, AF_INET6, m);
651 
652 	/*
653 	 * Put the packet to the network layer input queue according to the
654 	 * specified address family.
655 	 * See net/if_gif.c for possible issues with packet processing
656 	 * reorder due to extra queueing.
657 	 */
658 
659 	s = splnet();
660 	if (__predict_true(pktq_enqueue(ip6_pktq, m, 0))) {
661 		ifp->if_ipackets++;
662 		ifp->if_ibytes += pktlen;
663 	} else {
664 		m_freem(m);
665 	}
666 	splx(s);
667 
668 	return;
669 }
670 
671 /* ARGSUSED */
672 static void
673 stf_rtrequest(int cmd, struct rtentry *rt,
674     const struct rt_addrinfo *info)
675 {
676 	if (rt != NULL) {
677 		struct stf_softc *sc;
678 
679 		sc = LIST_FIRST(&stf_softc_list);
680 		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
681 	}
682 }
683 
684 static int
685 stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
686 {
687 	struct ifaddr		*ifa;
688 	struct ifreq		*ifr = data;
689 	struct sockaddr_in6	*sin6;
690 	int			error;
691 
692 	error = 0;
693 	switch (cmd) {
694 	case SIOCINITIFADDR:
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 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
703 			ifa->ifa_rtrequest = stf_rtrequest;
704 			ifp->if_flags |= IFF_UP;
705 		} else
706 			error = EINVAL;
707 		break;
708 
709 	case SIOCADDMULTI:
710 	case SIOCDELMULTI:
711 		if (ifr != NULL &&
712 		    ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
713 			;
714 		else
715 			error = EAFNOSUPPORT;
716 		break;
717 
718 	case SIOCSIFMTU:
719 		if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
720 			return EINVAL;
721 		else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
722 			error = 0;
723 		break;
724 
725 	default:
726 		error = ifioctl_common(ifp, cmd, data);
727 		break;
728 	}
729 
730 	return error;
731 }
732 
733 /*
734  * Module infrastructure
735  */
736 #include "if_module.h"
737 
738 IF_MODULE(MODULE_CLASS_DRIVER, stf, "")
739