xref: /netbsd-src/sys/net/if_stf.c (revision 404fbe5fb94ca1e054339640cabb2801ce52dd30)
1 /*	$NetBSD: if_stf.c,v 1.68 2008/11/07 00:20:13 dyoung 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 1.68 2008/11/07 00:20:13 dyoung 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/proc.h>
90 #include <sys/protosw.h>
91 #include <sys/queue.h>
92 #include <sys/syslog.h>
93 #include <sys/kauth.h>
94 
95 #include <sys/cpu.h>
96 
97 #include <net/if.h>
98 #include <net/route.h>
99 #include <net/netisr.h>
100 #include <net/if_types.h>
101 #include <net/if_stf.h>
102 
103 #include <netinet/in.h>
104 #include <netinet/in_systm.h>
105 #include <netinet/ip.h>
106 #include <netinet/ip_var.h>
107 #include <netinet/in_var.h>
108 
109 #include <netinet/ip6.h>
110 #include <netinet6/ip6_var.h>
111 #include <netinet6/in6_gif.h>
112 #include <netinet6/in6_var.h>
113 #include <netinet/ip_ecn.h>
114 
115 #include <netinet/ip_encap.h>
116 
117 #include <machine/stdarg.h>
118 
119 #include <net/net_osdep.h>
120 
121 #include "bpfilter.h"
122 #include "stf.h"
123 #include "gif.h"	/*XXX*/
124 
125 #if NBPFILTER > 0
126 #include <net/bpf.h>
127 #endif
128 
129 #if NGIF > 0
130 #include <net/if_gif.h>
131 #endif
132 
133 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
134 #define GET_V4(x)	((const struct in_addr *)(&(x)->s6_addr16[1]))
135 
136 struct stf_softc {
137 	struct ifnet	sc_if;	   /* common area */
138 	struct route	sc_ro;
139 	const struct encaptab *encap_cookie;
140 	LIST_ENTRY(stf_softc) sc_list;
141 };
142 
143 static LIST_HEAD(, stf_softc) stf_softc_list;
144 
145 static int	stf_clone_create(struct if_clone *, int);
146 static int	stf_clone_destroy(struct ifnet *);
147 
148 struct if_clone stf_cloner =
149     IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
150 
151 #if NGIF > 0
152 extern int ip_gif_ttl;	/*XXX*/
153 #else
154 static int ip_gif_ttl = 40;	/*XXX*/
155 #endif
156 
157 extern struct domain inetdomain;
158 static const struct protosw in_stf_protosw =
159 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
160   in_stf_input, rip_output,	0,		rip_ctloutput,
161   rip_usrreq,
162   0,            0,              0,              0
163 };
164 
165 void	stfattach(int);
166 
167 static int stf_encapcheck(struct mbuf *, int, int, void *);
168 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
169 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
170 	struct rtentry *);
171 static int isrfc1918addr(const struct in_addr *);
172 static int stf_checkaddr4(struct stf_softc *, const struct in_addr *,
173 	struct ifnet *);
174 static int stf_checkaddr6(struct stf_softc *, const struct in6_addr *,
175 	struct ifnet *);
176 static void stf_rtrequest(int, struct rtentry *, const struct rt_addrinfo *);
177 static int stf_ioctl(struct ifnet *, u_long, void *);
178 
179 /* ARGSUSED */
180 void
181 stfattach(int count)
182 {
183 
184 	LIST_INIT(&stf_softc_list);
185 	if_clone_attach(&stf_cloner);
186 }
187 
188 static int
189 stf_clone_create(struct if_clone *ifc, int unit)
190 {
191 	struct stf_softc *sc;
192 
193 	if (LIST_FIRST(&stf_softc_list) != NULL) {
194 		/* Only one stf interface is allowed. */
195 		return (EEXIST);
196 	}
197 
198 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT|M_ZERO);
199 
200 	if_initname(&sc->sc_if, ifc->ifc_name, unit);
201 
202 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
203 	    stf_encapcheck, &in_stf_protosw, sc);
204 	if (sc->encap_cookie == NULL) {
205 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
206 		free(sc, M_DEVBUF);
207 		return (EIO);	/* XXX */
208 	}
209 
210 	sc->sc_if.if_mtu    = STF_MTU;
211 	sc->sc_if.if_flags  = 0;
212 	sc->sc_if.if_ioctl  = stf_ioctl;
213 	sc->sc_if.if_output = stf_output;
214 	sc->sc_if.if_type   = IFT_STF;
215 	sc->sc_if.if_dlt    = DLT_NULL;
216 	if_attach(&sc->sc_if);
217 	if_alloc_sadl(&sc->sc_if);
218 #if NBPFILTER > 0
219 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
220 #endif
221 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
222 	return (0);
223 }
224 
225 static int
226 stf_clone_destroy(struct ifnet *ifp)
227 {
228 	struct stf_softc *sc = (void *) ifp;
229 
230 	LIST_REMOVE(sc, sc_list);
231 	encap_detach(sc->encap_cookie);
232 #if NBPFILTER > 0
233 	bpfdetach(ifp);
234 #endif
235 	if_detach(ifp);
236 	rtcache_free(&sc->sc_ro);
237 	free(sc, M_DEVBUF);
238 
239 	return (0);
240 }
241 
242 static int
243 stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
244 {
245 	struct ip ip;
246 	struct in6_ifaddr *ia6;
247 	struct stf_softc *sc;
248 	struct in_addr a, b;
249 
250 	sc = (struct stf_softc *)arg;
251 	if (sc == NULL)
252 		return 0;
253 
254 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
255 		return 0;
256 
257 	/* IFF_LINK0 means "no decapsulation" */
258 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
259 		return 0;
260 
261 	if (proto != IPPROTO_IPV6)
262 		return 0;
263 
264 	m_copydata(m, 0, sizeof(ip), (void *)&ip);
265 
266 	if (ip.ip_v != 4)
267 		return 0;
268 
269 	ia6 = stf_getsrcifa6(&sc->sc_if);
270 	if (ia6 == NULL)
271 		return 0;
272 
273 	/*
274 	 * check if IPv4 dst matches the IPv4 address derived from the
275 	 * local 6to4 address.
276 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
277 	 */
278 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
279 	    sizeof(ip.ip_dst)) != 0)
280 		return 0;
281 
282 	/*
283 	 * check if IPv4 src matches the IPv4 address derived from the
284 	 * local 6to4 address masked by prefixmask.
285 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
286 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
287 	 */
288 	memset(&a, 0, sizeof(a));
289 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
290 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
291 	b = ip.ip_src;
292 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
293 	if (a.s_addr != b.s_addr)
294 		return 0;
295 
296 	/* stf interface makes single side match only */
297 	return 32;
298 }
299 
300 static struct in6_ifaddr *
301 stf_getsrcifa6(struct ifnet *ifp)
302 {
303 	struct ifaddr *ifa;
304 	struct in_ifaddr *ia4;
305 	struct sockaddr_in6 *sin6;
306 	struct in_addr in;
307 
308 	IFADDR_FOREACH(ifa, ifp)
309 	{
310 		if (ifa->ifa_addr == NULL)
311 			continue;
312 		if (ifa->ifa_addr->sa_family != AF_INET6)
313 			continue;
314 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
315 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
316 			continue;
317 
318 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
319 		INADDR_TO_IA(in, ia4);
320 		if (ia4 == NULL)
321 			continue;
322 
323 		return (struct in6_ifaddr *)ifa;
324 	}
325 
326 	return NULL;
327 }
328 
329 static int
330 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
331     struct rtentry *rt0)
332 {
333 	struct rtentry *rt;
334 	struct stf_softc *sc;
335 	const struct sockaddr_in6 *dst6;
336 	const struct in_addr *in4;
337 	uint8_t tos;
338 	struct ip *ip;
339 	struct ip6_hdr *ip6;
340 	struct in6_ifaddr *ia6;
341 	union {
342 		struct sockaddr		dst;
343 		struct sockaddr_in	dst4;
344 	} u;
345 
346 	sc = (struct stf_softc*)ifp;
347 	dst6 = (const struct sockaddr_in6 *)dst;
348 
349 	/* just in case */
350 	if ((ifp->if_flags & IFF_UP) == 0) {
351 		m_freem(m);
352 		return ENETDOWN;
353 	}
354 
355 	/*
356 	 * If we don't have an ip4 address that match my inner ip6 address,
357 	 * we shouldn't generate output.  Without this check, we'll end up
358 	 * using wrong IPv4 source.
359 	 */
360 	ia6 = stf_getsrcifa6(ifp);
361 	if (ia6 == NULL) {
362 		m_freem(m);
363 		ifp->if_oerrors++;
364 		return ENETDOWN;
365 	}
366 
367 	if (m->m_len < sizeof(*ip6)) {
368 		m = m_pullup(m, sizeof(*ip6));
369 		if (m == NULL) {
370 			ifp->if_oerrors++;
371 			return ENOBUFS;
372 		}
373 	}
374 	ip6 = mtod(m, struct ip6_hdr *);
375 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
376 
377 	/*
378 	 * Pickup the right outer dst addr from the list of candidates.
379 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
380 	 */
381 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
382 		in4 = GET_V4(&ip6->ip6_dst);
383 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
384 		in4 = GET_V4(&dst6->sin6_addr);
385 	else {
386 		m_freem(m);
387 		ifp->if_oerrors++;
388 		return ENETUNREACH;
389 	}
390 
391 #if NBPFILTER > 0
392 	if (ifp->if_bpf)
393 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
394 #endif /*NBPFILTER > 0*/
395 
396 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
397 	if (m && m->m_len < sizeof(struct ip))
398 		m = m_pullup(m, sizeof(struct ip));
399 	if (m == NULL) {
400 		ifp->if_oerrors++;
401 		return ENOBUFS;
402 	}
403 	ip = mtod(m, struct ip *);
404 
405 	memset(ip, 0, sizeof(*ip));
406 
407 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
408 	    &ip->ip_src, sizeof(ip->ip_src));
409 	bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
410 	ip->ip_p = IPPROTO_IPV6;
411 	ip->ip_ttl = ip_gif_ttl;	/*XXX*/
412 	ip->ip_len = htons(m->m_pkthdr.len);
413 	if (ifp->if_flags & IFF_LINK1)
414 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
415 	else
416 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
417 
418 	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
419 	if ((rt = rtcache_lookup(&sc->sc_ro, &u.dst)) == NULL) {
420 		m_freem(m);
421 		ifp->if_oerrors++;
422 		return ENETUNREACH;
423 	}
424 
425 	/* If the route constitutes infinite encapsulation, punt. */
426 	if (rt->rt_ifp == ifp) {
427 		rtcache_free(&sc->sc_ro);
428 		m_freem(m);
429 		ifp->if_oerrors++;
430 		return ENETUNREACH;
431 	}
432 
433 	ifp->if_opackets++;
434 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
435 }
436 
437 static int
438 isrfc1918addr(const struct in_addr *in)
439 {
440 	/*
441 	 * returns 1 if private address range:
442 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
443 	 */
444 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
445 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
446 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
447 		return 1;
448 
449 	return 0;
450 }
451 
452 static int
453 stf_checkaddr4(struct stf_softc *sc, const struct in_addr *in,
454     struct ifnet *inifp /*incoming interface*/)
455 {
456 	struct in_ifaddr *ia4;
457 
458 	/*
459 	 * reject packets with the following address:
460 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
461 	 */
462 	if (IN_MULTICAST(in->s_addr))
463 		return -1;
464 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
465 	case 0: case 127: case 255:
466 		return -1;
467 	}
468 
469 	/*
470 	 * reject packets with private address range.
471 	 * (requirement from RFC3056 section 2 1st paragraph)
472 	 */
473 	if (isrfc1918addr(in))
474 		return -1;
475 
476 	/*
477 	 * reject packet with IPv4 link-local (169.254.0.0/16),
478 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
479 	 */
480 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
481 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
482 		return -1;
483 
484 	/*
485 	 * reject packets with broadcast
486 	 */
487 	TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
488 	{
489 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
490 			continue;
491 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
492 			return -1;
493 	}
494 
495 	/*
496 	 * perform ingress filter
497 	 */
498 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
499 		struct sockaddr_in sin;
500 		struct rtentry *rt;
501 
502 		memset(&sin, 0, sizeof(sin));
503 		sin.sin_family = AF_INET;
504 		sin.sin_len = sizeof(struct sockaddr_in);
505 		sin.sin_addr = *in;
506 		rt = rtalloc1((struct sockaddr *)&sin, 0);
507 		if (!rt || rt->rt_ifp != inifp) {
508 #if 0
509 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
510 			    "due to ingress filter\n", if_name(&sc->sc_if),
511 			    (uint32_t)ntohl(sin.sin_addr.s_addr));
512 #endif
513 			if (rt)
514 				rtfree(rt);
515 			return -1;
516 		}
517 		rtfree(rt);
518 	}
519 
520 	return 0;
521 }
522 
523 static int
524 stf_checkaddr6(struct stf_softc *sc, const struct in6_addr *in6,
525     struct ifnet *inifp /*incoming interface*/)
526 {
527 
528 	/*
529 	 * check 6to4 addresses
530 	 */
531 	if (IN6_IS_ADDR_6TO4(in6))
532 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
533 
534 	/*
535 	 * reject anything that look suspicious.  the test is implemented
536 	 * in ip6_input too, but we check here as well to
537 	 * (1) reject bad packets earlier, and
538 	 * (2) to be safe against future ip6_input change.
539 	 */
540 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
541 		return -1;
542 
543 	/*
544 	 * reject link-local and site-local unicast
545 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
546 	 */
547 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
548 		return -1;
549 
550 	/*
551 	 * reject node-local and link-local multicast
552 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
553 	 */
554 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
555 		return -1;
556 
557 	return 0;
558 }
559 
560 void
561 in_stf_input(struct mbuf *m, ...)
562 {
563 	int off, proto;
564 	struct stf_softc *sc;
565 	struct ip *ip;
566 	struct ip6_hdr *ip6;
567 	uint8_t otos, itos;
568 	int s, isr;
569 	struct ifqueue *ifq = NULL;
570 	struct ifnet *ifp;
571 	va_list ap;
572 
573 	va_start(ap, m);
574 	off = va_arg(ap, int);
575 	proto = va_arg(ap, int);
576 	va_end(ap);
577 
578 	if (proto != IPPROTO_IPV6) {
579 		m_freem(m);
580 		return;
581 	}
582 
583 	ip = mtod(m, struct ip *);
584 
585 	sc = (struct stf_softc *)encap_getarg(m);
586 
587 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
588 		m_freem(m);
589 		return;
590 	}
591 
592 	ifp = &sc->sc_if;
593 
594 	/*
595 	 * perform sanity check against outer src/dst.
596 	 * for source, perform ingress filter as well.
597 	 */
598 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
599 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
600 		m_freem(m);
601 		return;
602 	}
603 
604 	otos = ip->ip_tos;
605 	m_adj(m, off);
606 
607 	if (m->m_len < sizeof(*ip6)) {
608 		m = m_pullup(m, sizeof(*ip6));
609 		if (!m)
610 			return;
611 	}
612 	ip6 = mtod(m, struct ip6_hdr *);
613 
614 	/*
615 	 * perform sanity check against inner src/dst.
616 	 * for source, perform ingress filter as well.
617 	 */
618 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
619 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
620 		m_freem(m);
621 		return;
622 	}
623 
624 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
625 	if ((ifp->if_flags & IFF_LINK1) != 0)
626 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
627 	else
628 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
629 	ip6->ip6_flow &= ~htonl(0xff << 20);
630 	ip6->ip6_flow |= htonl((uint32_t)itos << 20);
631 
632 	m->m_pkthdr.rcvif = ifp;
633 
634 #if NBPFILTER > 0
635 	if (ifp->if_bpf)
636 		bpf_mtap_af(ifp->if_bpf, AF_INET6, m);
637 #endif /*NBPFILTER > 0*/
638 
639 	/*
640 	 * Put the packet to the network layer input queue according to the
641 	 * specified address family.
642 	 * See net/if_gif.c for possible issues with packet processing
643 	 * reorder due to extra queueing.
644 	 */
645 	ifq = &ip6intrq;
646 	isr = NETISR_IPV6;
647 
648 	s = splnet();
649 	if (IF_QFULL(ifq)) {
650 		IF_DROP(ifq);	/* update statistics */
651 		m_freem(m);
652 		splx(s);
653 		return;
654 	}
655 	IF_ENQUEUE(ifq, m);
656 	schednetisr(isr);
657 	ifp->if_ipackets++;
658 	ifp->if_ibytes += m->m_pkthdr.len;
659 	splx(s);
660 }
661 
662 /* ARGSUSED */
663 static void
664 stf_rtrequest(int cmd, struct rtentry *rt,
665     const struct rt_addrinfo *info)
666 {
667 	if (rt != NULL) {
668 		struct stf_softc *sc;
669 
670 		sc = LIST_FIRST(&stf_softc_list);
671 		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
672 	}
673 }
674 
675 static int
676 stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
677 {
678 	struct lwp		*l = curlwp;	/* XXX */
679 	struct ifaddr		*ifa;
680 	struct ifreq		*ifr = data;
681 	struct sockaddr_in6	*sin6;
682 	int			error;
683 
684 	error = 0;
685 	switch (cmd) {
686 	case SIOCINITIFADDR:
687 		ifa = (struct ifaddr *)data;
688 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
689 			error = EAFNOSUPPORT;
690 			break;
691 		}
692 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
693 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
694 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
695 			ifa->ifa_rtrequest = stf_rtrequest;
696 			ifp->if_flags |= IFF_UP;
697 		} else
698 			error = EINVAL;
699 		break;
700 
701 	case SIOCADDMULTI:
702 	case SIOCDELMULTI:
703 		if (ifr != NULL &&
704 		    ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
705 			;
706 		else
707 			error = EAFNOSUPPORT;
708 		break;
709 
710 	case SIOCSIFMTU:
711 		if ((error = kauth_authorize_generic(l->l_cred,
712 		    KAUTH_GENERIC_ISSUSER, NULL)) != 0)
713 			break;
714 		if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
715 			return EINVAL;
716 		else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
717 			error = 0;
718 		break;
719 
720 	default:
721 		error = ifioctl_common(ifp, cmd, data);
722 		break;
723 	}
724 
725 	return error;
726 }
727