xref: /netbsd-src/sys/net/if_stf.c (revision 796c32c94f6e154afc9de0f63da35c91bb739b45)
1 /*	$NetBSD: if_stf.c,v 1.103 2017/11/15 10:42:41 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 1.103 2017/11/15 10:42:41 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 	error = if_attach(&sc->sc_if);
242 	if (error != 0) {
243 		aprint_error("%s: if_initialize failed(%d)\n",
244 		    if_name(&sc->sc_if), error);
245 		encap_lock_enter();
246 		encap_detach(sc->encap_cookie);
247 		encap_lock_exit();
248 		free(sc, M_DEVBUF);
249 		return error;
250 	}
251 	if_alloc_sadl(&sc->sc_if);
252 	bpf_attach(&sc->sc_if, DLT_NULL, sizeof(u_int));
253 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
254 	return 0;
255 }
256 
257 static int
258 stf_clone_destroy(struct ifnet *ifp)
259 {
260 	struct stf_softc *sc = (void *) ifp;
261 
262 	encap_lock_enter();
263 	LIST_REMOVE(sc, sc_list);
264 	encap_detach(sc->encap_cookie);
265 	encap_lock_exit();
266 	bpf_detach(ifp);
267 	if_detach(ifp);
268 	rtcache_free(&sc->sc_ro);
269 	free(sc, M_DEVBUF);
270 
271 	return 0;
272 }
273 
274 static int
275 stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
276 {
277 	struct ip ip;
278 	struct in6_ifaddr *ia6;
279 	struct stf_softc *sc;
280 	struct in_addr a, b;
281 
282 	sc = (struct stf_softc *)arg;
283 	if (sc == NULL)
284 		return 0;
285 
286 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
287 		return 0;
288 
289 	/* IFF_LINK0 means "no decapsulation" */
290 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
291 		return 0;
292 
293 	if (proto != IPPROTO_IPV6)
294 		return 0;
295 
296 	m_copydata(m, 0, sizeof(ip), (void *)&ip);
297 
298 	if (ip.ip_v != 4)
299 		return 0;
300 
301 	ia6 = stf_getsrcifa6(&sc->sc_if);
302 	if (ia6 == NULL)
303 		return 0;
304 
305 	/*
306 	 * check if IPv4 dst matches the IPv4 address derived from the
307 	 * local 6to4 address.
308 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
309 	 */
310 	if (memcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
311 	    sizeof(ip.ip_dst)) != 0)
312 		return 0;
313 
314 	/*
315 	 * check if IPv4 src matches the IPv4 address derived from the
316 	 * local 6to4 address masked by prefixmask.
317 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
318 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
319 	 */
320 	memset(&a, 0, sizeof(a));
321 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
322 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
323 	b = ip.ip_src;
324 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
325 	if (a.s_addr != b.s_addr)
326 		return 0;
327 
328 	/* stf interface makes single side match only */
329 	return 32;
330 }
331 
332 static struct in6_ifaddr *
333 stf_getsrcifa6(struct ifnet *ifp)
334 {
335 	struct ifaddr *ifa;
336 	struct in_ifaddr *ia4;
337 	struct sockaddr_in6 *sin6;
338 	struct in_addr in;
339 	int s;
340 
341 	s = pserialize_read_enter();
342 	IFADDR_READER_FOREACH(ifa, ifp) {
343 		if (ifa->ifa_addr->sa_family != AF_INET6)
344 			continue;
345 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
346 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
347 			continue;
348 
349 		memcpy(&in, GET_V4(&sin6->sin6_addr), sizeof(in));
350 		ia4 = in_get_ia(in);
351 		if (ia4 == NULL)
352 			continue;
353 
354 		pserialize_read_exit(s);
355 		/* TODO NOMPSAFE */
356 		return (struct in6_ifaddr *)ifa;
357 	}
358 	pserialize_read_exit(s);
359 
360 	return NULL;
361 }
362 
363 static int
364 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
365     const struct rtentry *rt0)
366 {
367 	struct rtentry *rt;
368 	struct stf_softc *sc;
369 	const struct sockaddr_in6 *dst6;
370 	const struct in_addr *in4;
371 	uint8_t tos;
372 	struct ip *ip;
373 	struct ip6_hdr *ip6;
374 	struct in6_ifaddr *ia6;
375 	union {
376 		struct sockaddr		dst;
377 		struct sockaddr_in	dst4;
378 	} u;
379 
380 	sc = (struct stf_softc*)ifp;
381 	dst6 = (const struct sockaddr_in6 *)dst;
382 
383 	/* just in case */
384 	if ((ifp->if_flags & IFF_UP) == 0) {
385 		m_freem(m);
386 		return ENETDOWN;
387 	}
388 
389 	/*
390 	 * If we don't have an ip4 address that match my inner ip6 address,
391 	 * we shouldn't generate output.  Without this check, we'll end up
392 	 * using wrong IPv4 source.
393 	 */
394 	ia6 = stf_getsrcifa6(ifp);
395 	if (ia6 == NULL) {
396 		m_freem(m);
397 		ifp->if_oerrors++;
398 		return ENETDOWN;
399 	}
400 
401 	if (m->m_len < sizeof(*ip6)) {
402 		m = m_pullup(m, sizeof(*ip6));
403 		if (m == NULL) {
404 			ifp->if_oerrors++;
405 			return ENOBUFS;
406 		}
407 	}
408 	ip6 = mtod(m, struct ip6_hdr *);
409 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
410 
411 	/*
412 	 * Pickup the right outer dst addr from the list of candidates.
413 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
414 	 */
415 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
416 		in4 = GET_V4(&ip6->ip6_dst);
417 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
418 		in4 = GET_V4(&dst6->sin6_addr);
419 	else {
420 		m_freem(m);
421 		ifp->if_oerrors++;
422 		return ENETUNREACH;
423 	}
424 
425 	bpf_mtap_af(ifp, AF_INET6, m);
426 
427 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
428 	if (m && m->m_len < sizeof(struct ip))
429 		m = m_pullup(m, sizeof(struct ip));
430 	if (m == NULL) {
431 		ifp->if_oerrors++;
432 		return ENOBUFS;
433 	}
434 	ip = mtod(m, struct ip *);
435 
436 	memset(ip, 0, sizeof(*ip));
437 
438 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
439 	    &ip->ip_src, sizeof(ip->ip_src));
440 	memcpy(&ip->ip_dst, in4, sizeof(ip->ip_dst));
441 	ip->ip_p = IPPROTO_IPV6;
442 	ip->ip_ttl = ip_stf_ttl;
443 	ip->ip_len = htons(m->m_pkthdr.len);
444 	if (ifp->if_flags & IFF_LINK1)
445 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
446 	else
447 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
448 
449 	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
450 	if ((rt = rtcache_lookup(&sc->sc_ro, &u.dst)) == NULL) {
451 		m_freem(m);
452 		ifp->if_oerrors++;
453 		return ENETUNREACH;
454 	}
455 
456 	/* If the route constitutes infinite encapsulation, punt. */
457 	if (rt->rt_ifp == ifp) {
458 		rtcache_unref(rt, &sc->sc_ro);
459 		rtcache_free(&sc->sc_ro);
460 		m_freem(m);
461 		ifp->if_oerrors++;
462 		return ENETUNREACH;
463 	}
464 	rtcache_unref(rt, &sc->sc_ro);
465 
466 	ifp->if_opackets++;
467 	ifp->if_obytes += m->m_pkthdr.len - sizeof(struct ip);
468 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
469 }
470 
471 static int
472 isrfc1918addr(const struct in_addr *in)
473 {
474 	/*
475 	 * returns 1 if private address range:
476 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
477 	 */
478 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
479 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
480 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
481 		return 1;
482 
483 	return 0;
484 }
485 
486 static int
487 stf_checkaddr4(struct stf_softc *sc, const 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(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 packet with IPv4 link-local (169.254.0.0/16),
512 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
513 	 */
514 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
515 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
516 		return -1;
517 
518 	/*
519 	 * reject packets with broadcast
520 	 */
521 	IN_ADDRLIST_READER_FOREACH(ia4) {
522 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
523 			continue;
524 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
525 			return -1;
526 	}
527 
528 	/*
529 	 * perform ingress filter
530 	 */
531 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
532 		struct sockaddr_in sin;
533 		struct rtentry *rt;
534 
535 		memset(&sin, 0, sizeof(sin));
536 		sin.sin_family = AF_INET;
537 		sin.sin_len = sizeof(struct sockaddr_in);
538 		sin.sin_addr = *in;
539 		rt = rtalloc1((struct sockaddr *)&sin, 0);
540 		if (!rt || rt->rt_ifp != inifp) {
541 #if 0
542 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
543 			    "due to ingress filter\n", if_name(&sc->sc_if),
544 			    (uint32_t)ntohl(sin.sin_addr.s_addr));
545 #endif
546 			if (rt)
547 				rt_unref(rt);
548 			return -1;
549 		}
550 		rt_unref(rt);
551 	}
552 
553 	return 0;
554 }
555 
556 static int
557 stf_checkaddr6(struct stf_softc *sc, const struct in6_addr *in6,
558     struct ifnet *inifp /*incoming interface*/)
559 {
560 
561 	/*
562 	 * check 6to4 addresses
563 	 */
564 	if (IN6_IS_ADDR_6TO4(in6))
565 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
566 
567 	/*
568 	 * reject anything that look suspicious.  the test is implemented
569 	 * in ip6_input too, but we check here as well to
570 	 * (1) reject bad packets earlier, and
571 	 * (2) to be safe against future ip6_input change.
572 	 */
573 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
574 		return -1;
575 
576 	/*
577 	 * reject link-local and site-local unicast
578 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
579 	 */
580 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
581 		return -1;
582 
583 	/*
584 	 * reject node-local and link-local multicast
585 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
586 	 */
587 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
588 		return -1;
589 
590 	return 0;
591 }
592 
593 void
594 in_stf_input(struct mbuf *m, int off, int proto, void *eparg)
595 {
596 	int s;
597 	struct stf_softc *sc = eparg;
598 	struct ip *ip;
599 	struct ip6_hdr *ip6;
600 	uint8_t otos, itos;
601 	struct ifnet *ifp;
602 	size_t pktlen;
603 
604 	KASSERT(sc != NULL);
605 
606 	if (proto != IPPROTO_IPV6) {
607 		m_freem(m);
608 		return;
609 	}
610 
611 	ip = mtod(m, struct ip *);
612 
613 	if ((sc->sc_if.if_flags & IFF_UP) == 0) {
614 		m_freem(m);
615 		return;
616 	}
617 
618 	ifp = &sc->sc_if;
619 
620 	/*
621 	 * perform sanity check against outer src/dst.
622 	 * for source, perform ingress filter as well.
623 	 */
624 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
625 	    stf_checkaddr4(sc, &ip->ip_src, m_get_rcvif_NOMPSAFE(m)) < 0) {
626 		m_freem(m);
627 		return;
628 	}
629 
630 	otos = ip->ip_tos;
631 	m_adj(m, off);
632 
633 	if (m->m_len < sizeof(*ip6)) {
634 		m = m_pullup(m, sizeof(*ip6));
635 		if (!m)
636 			return;
637 	}
638 	ip6 = mtod(m, struct ip6_hdr *);
639 
640 	/*
641 	 * perform sanity check against inner src/dst.
642 	 * for source, perform ingress filter as well.
643 	 */
644 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
645 	    stf_checkaddr6(sc, &ip6->ip6_src, m_get_rcvif_NOMPSAFE(m)) < 0) {
646 		m_freem(m);
647 		return;
648 	}
649 
650 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
651 	if ((ifp->if_flags & IFF_LINK1) != 0)
652 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
653 	else
654 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
655 	ip6->ip6_flow &= ~htonl(0xff << 20);
656 	ip6->ip6_flow |= htonl((uint32_t)itos << 20);
657 
658 	pktlen = m->m_pkthdr.len;
659 	m_set_rcvif(m, ifp);
660 
661 	bpf_mtap_af(ifp, AF_INET6, m);
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 
670 	s = splnet();
671 	if (__predict_true(pktq_enqueue(ip6_pktq, m, 0))) {
672 		ifp->if_ipackets++;
673 		ifp->if_ibytes += pktlen;
674 	} else {
675 		m_freem(m);
676 	}
677 	splx(s);
678 
679 	return;
680 }
681 
682 /* ARGSUSED */
683 static void
684 stf_rtrequest(int cmd, struct rtentry *rt,
685     const struct rt_addrinfo *info)
686 {
687 	if (rt != NULL) {
688 		struct stf_softc *sc;
689 
690 		sc = LIST_FIRST(&stf_softc_list);
691 		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
692 	}
693 }
694 
695 static int
696 stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
697 {
698 	struct ifaddr		*ifa;
699 	struct ifreq		*ifr = data;
700 	struct sockaddr_in6	*sin6;
701 	int			error;
702 
703 	error = 0;
704 	switch (cmd) {
705 	case SIOCINITIFADDR:
706 		ifa = (struct ifaddr *)data;
707 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
708 			error = EAFNOSUPPORT;
709 			break;
710 		}
711 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
712 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
713 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
714 			ifa->ifa_rtrequest = stf_rtrequest;
715 			ifp->if_flags |= IFF_UP;
716 		} else
717 			error = EINVAL;
718 		break;
719 
720 	case SIOCADDMULTI:
721 	case SIOCDELMULTI:
722 		if (ifr != NULL &&
723 		    ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
724 			;
725 		else
726 			error = EAFNOSUPPORT;
727 		break;
728 
729 	case SIOCSIFMTU:
730 		if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
731 			return EINVAL;
732 		else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
733 			error = 0;
734 		break;
735 
736 	default:
737 		error = ifioctl_common(ifp, cmd, data);
738 		break;
739 	}
740 
741 	return error;
742 }
743 
744 /*
745  * Module infrastructure
746  */
747 #include "if_module.h"
748 
749 IF_MODULE(MODULE_CLASS_DRIVER, stf, "")
750