xref: /netbsd-src/sys/net/if_stf.c (revision 946379e7b37692fc43f68eb0d1c10daa0a7f3b6c)
1 /*	$NetBSD: if_stf.c,v 1.82 2015/08/24 22:21:26 pooka 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 1.82 2015/08/24 22:21:26 pooka Exp $");
79 
80 #ifdef _KERNEL_OPT
81 #include "opt_inet.h"
82 #endif
83 
84 #ifndef INET6
85 	#error "pseudo-device stf requires options INET6"
86 #endif
87 
88 #include <sys/param.h>
89 #include <sys/systm.h>
90 #include <sys/socket.h>
91 #include <sys/sockio.h>
92 #include <sys/mbuf.h>
93 #include <sys/errno.h>
94 #include <sys/ioctl.h>
95 #include <sys/proc.h>
96 #include <sys/protosw.h>
97 #include <sys/queue.h>
98 #include <sys/syslog.h>
99 
100 #include <sys/cpu.h>
101 
102 #include <net/if.h>
103 #include <net/route.h>
104 #include <net/netisr.h>
105 #include <net/if_types.h>
106 #include <net/if_stf.h>
107 
108 #include <netinet/in.h>
109 #include <netinet/in_systm.h>
110 #include <netinet/ip.h>
111 #include <netinet/ip_var.h>
112 #include <netinet/in_var.h>
113 
114 #include <netinet/ip6.h>
115 #include <netinet6/ip6_var.h>
116 #include <netinet6/in6_gif.h>
117 #include <netinet6/in6_var.h>
118 #include <netinet/ip_ecn.h>
119 
120 #include <netinet/ip_encap.h>
121 
122 #include <net/net_osdep.h>
123 
124 #include "stf.h"
125 #include "gif.h"	/*XXX*/
126 
127 #include <net/bpf.h>
128 
129 #if NGIF > 0
130 #include <net/if_gif.h>
131 #endif
132 
133 #include "ioconf.h"
134 
135 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
136 #define GET_V4(x)	((const struct in_addr *)(&(x)->s6_addr16[1]))
137 
138 struct stf_softc {
139 	struct ifnet	sc_if;	   /* common area */
140 	struct route	sc_ro;
141 	const struct encaptab *encap_cookie;
142 	LIST_ENTRY(stf_softc) sc_list;
143 };
144 
145 static LIST_HEAD(, stf_softc) stf_softc_list;
146 
147 static int	stf_clone_create(struct if_clone *, int);
148 static int	stf_clone_destroy(struct ifnet *);
149 
150 struct if_clone stf_cloner =
151     IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy);
152 
153 #if NGIF > 0
154 extern int ip_gif_ttl;	/*XXX*/
155 #else
156 static int ip_gif_ttl = 40;	/*XXX*/
157 #endif
158 
159 extern struct domain inetdomain;
160 
161 static const struct protosw in_stf_protosw =
162 {
163 	.pr_type	= SOCK_RAW,
164 	.pr_domain	= &inetdomain,
165 	.pr_protocol	= IPPROTO_IPV6,
166 	.pr_flags	= PR_ATOMIC|PR_ADDR,
167 	.pr_input	= in_stf_input,
168 	.pr_output	= rip_output,
169 	.pr_ctlinput	= NULL,
170 	.pr_ctloutput	= rip_ctloutput,
171 	.pr_usrreqs	= &rip_usrreqs,
172 };
173 
174 static int stf_encapcheck(struct mbuf *, int, int, void *);
175 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
176 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
177 	struct rtentry *);
178 static int isrfc1918addr(const struct in_addr *);
179 static int stf_checkaddr4(struct stf_softc *, const struct in_addr *,
180 	struct ifnet *);
181 static int stf_checkaddr6(struct stf_softc *, const struct in6_addr *,
182 	struct ifnet *);
183 static void stf_rtrequest(int, struct rtentry *, const struct rt_addrinfo *);
184 static int stf_ioctl(struct ifnet *, u_long, void *);
185 
186 /* ARGSUSED */
187 void
188 stfattach(int count)
189 {
190 
191 	LIST_INIT(&stf_softc_list);
192 	if_clone_attach(&stf_cloner);
193 }
194 
195 static int
196 stf_clone_create(struct if_clone *ifc, int unit)
197 {
198 	struct stf_softc *sc;
199 
200 	if (LIST_FIRST(&stf_softc_list) != NULL) {
201 		/* Only one stf interface is allowed. */
202 		return (EEXIST);
203 	}
204 
205 	sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT|M_ZERO);
206 
207 	if_initname(&sc->sc_if, ifc->ifc_name, unit);
208 
209 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
210 	    stf_encapcheck, &in_stf_protosw, sc);
211 	if (sc->encap_cookie == NULL) {
212 		printf("%s: unable to attach encap\n", if_name(&sc->sc_if));
213 		free(sc, M_DEVBUF);
214 		return (EIO);	/* XXX */
215 	}
216 
217 	sc->sc_if.if_mtu    = STF_MTU;
218 	sc->sc_if.if_flags  = 0;
219 	sc->sc_if.if_ioctl  = stf_ioctl;
220 	sc->sc_if.if_output = stf_output;
221 	sc->sc_if.if_type   = IFT_STF;
222 	sc->sc_if.if_dlt    = DLT_NULL;
223 	if_attach(&sc->sc_if);
224 	if_alloc_sadl(&sc->sc_if);
225 	bpf_attach(&sc->sc_if, DLT_NULL, sizeof(u_int));
226 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
227 	return (0);
228 }
229 
230 static int
231 stf_clone_destroy(struct ifnet *ifp)
232 {
233 	struct stf_softc *sc = (void *) ifp;
234 
235 	LIST_REMOVE(sc, sc_list);
236 	encap_detach(sc->encap_cookie);
237 	bpf_detach(ifp);
238 	if_detach(ifp);
239 	rtcache_free(&sc->sc_ro);
240 	free(sc, M_DEVBUF);
241 
242 	return (0);
243 }
244 
245 static int
246 stf_encapcheck(struct mbuf *m, int off, int proto, void *arg)
247 {
248 	struct ip ip;
249 	struct in6_ifaddr *ia6;
250 	struct stf_softc *sc;
251 	struct in_addr a, b;
252 
253 	sc = (struct stf_softc *)arg;
254 	if (sc == NULL)
255 		return 0;
256 
257 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
258 		return 0;
259 
260 	/* IFF_LINK0 means "no decapsulation" */
261 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
262 		return 0;
263 
264 	if (proto != IPPROTO_IPV6)
265 		return 0;
266 
267 	m_copydata(m, 0, sizeof(ip), (void *)&ip);
268 
269 	if (ip.ip_v != 4)
270 		return 0;
271 
272 	ia6 = stf_getsrcifa6(&sc->sc_if);
273 	if (ia6 == NULL)
274 		return 0;
275 
276 	/*
277 	 * check if IPv4 dst matches the IPv4 address derived from the
278 	 * local 6to4 address.
279 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
280 	 */
281 	if (memcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
282 	    sizeof(ip.ip_dst)) != 0)
283 		return 0;
284 
285 	/*
286 	 * check if IPv4 src matches the IPv4 address derived from the
287 	 * local 6to4 address masked by prefixmask.
288 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
289 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
290 	 */
291 	memset(&a, 0, sizeof(a));
292 	a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
293 	a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
294 	b = ip.ip_src;
295 	b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
296 	if (a.s_addr != b.s_addr)
297 		return 0;
298 
299 	/* stf interface makes single side match only */
300 	return 32;
301 }
302 
303 static struct in6_ifaddr *
304 stf_getsrcifa6(struct ifnet *ifp)
305 {
306 	struct ifaddr *ifa;
307 	struct in_ifaddr *ia4;
308 	struct sockaddr_in6 *sin6;
309 	struct in_addr in;
310 
311 	IFADDR_FOREACH(ifa, ifp)
312 	{
313 		if (ifa->ifa_addr == NULL)
314 			continue;
315 		if (ifa->ifa_addr->sa_family != AF_INET6)
316 			continue;
317 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
318 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
319 			continue;
320 
321 		memcpy(&in, GET_V4(&sin6->sin6_addr), sizeof(in));
322 		INADDR_TO_IA(in, ia4);
323 		if (ia4 == NULL)
324 			continue;
325 
326 		return (struct in6_ifaddr *)ifa;
327 	}
328 
329 	return NULL;
330 }
331 
332 static int
333 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
334     struct rtentry *rt0)
335 {
336 	struct rtentry *rt;
337 	struct stf_softc *sc;
338 	const struct sockaddr_in6 *dst6;
339 	const struct in_addr *in4;
340 	uint8_t tos;
341 	struct ip *ip;
342 	struct ip6_hdr *ip6;
343 	struct in6_ifaddr *ia6;
344 	union {
345 		struct sockaddr		dst;
346 		struct sockaddr_in	dst4;
347 	} u;
348 
349 	sc = (struct stf_softc*)ifp;
350 	dst6 = (const struct sockaddr_in6 *)dst;
351 
352 	/* just in case */
353 	if ((ifp->if_flags & IFF_UP) == 0) {
354 		m_freem(m);
355 		return ENETDOWN;
356 	}
357 
358 	/*
359 	 * If we don't have an ip4 address that match my inner ip6 address,
360 	 * we shouldn't generate output.  Without this check, we'll end up
361 	 * using wrong IPv4 source.
362 	 */
363 	ia6 = stf_getsrcifa6(ifp);
364 	if (ia6 == NULL) {
365 		m_freem(m);
366 		ifp->if_oerrors++;
367 		return ENETDOWN;
368 	}
369 
370 	if (m->m_len < sizeof(*ip6)) {
371 		m = m_pullup(m, sizeof(*ip6));
372 		if (m == NULL) {
373 			ifp->if_oerrors++;
374 			return ENOBUFS;
375 		}
376 	}
377 	ip6 = mtod(m, struct ip6_hdr *);
378 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
379 
380 	/*
381 	 * Pickup the right outer dst addr from the list of candidates.
382 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
383 	 */
384 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
385 		in4 = GET_V4(&ip6->ip6_dst);
386 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
387 		in4 = GET_V4(&dst6->sin6_addr);
388 	else {
389 		m_freem(m);
390 		ifp->if_oerrors++;
391 		return ENETUNREACH;
392 	}
393 
394 	bpf_mtap_af(ifp, AF_INET6, m);
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 	memcpy(&ip->ip_dst, in4, 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 	ifp->if_obytes += m->m_pkthdr.len - sizeof(struct ip);
435 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
436 }
437 
438 static int
439 isrfc1918addr(const struct in_addr *in)
440 {
441 	/*
442 	 * returns 1 if private address range:
443 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
444 	 */
445 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
446 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
447 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
448 		return 1;
449 
450 	return 0;
451 }
452 
453 static int
454 stf_checkaddr4(struct stf_softc *sc, const struct in_addr *in,
455     struct ifnet *inifp /*incoming interface*/)
456 {
457 	struct in_ifaddr *ia4;
458 
459 	/*
460 	 * reject packets with the following address:
461 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
462 	 */
463 	if (IN_MULTICAST(in->s_addr))
464 		return -1;
465 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
466 	case 0: case 127: case 255:
467 		return -1;
468 	}
469 
470 	/*
471 	 * reject packets with private address range.
472 	 * (requirement from RFC3056 section 2 1st paragraph)
473 	 */
474 	if (isrfc1918addr(in))
475 		return -1;
476 
477 	/*
478 	 * reject packet with IPv4 link-local (169.254.0.0/16),
479 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
480 	 */
481 	if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 &&
482 	    ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254)
483 		return -1;
484 
485 	/*
486 	 * reject packets with broadcast
487 	 */
488 	TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list)
489 	{
490 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
491 			continue;
492 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
493 			return -1;
494 	}
495 
496 	/*
497 	 * perform ingress filter
498 	 */
499 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
500 		struct sockaddr_in sin;
501 		struct rtentry *rt;
502 
503 		memset(&sin, 0, sizeof(sin));
504 		sin.sin_family = AF_INET;
505 		sin.sin_len = sizeof(struct sockaddr_in);
506 		sin.sin_addr = *in;
507 		rt = rtalloc1((struct sockaddr *)&sin, 0);
508 		if (!rt || rt->rt_ifp != inifp) {
509 #if 0
510 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
511 			    "due to ingress filter\n", if_name(&sc->sc_if),
512 			    (uint32_t)ntohl(sin.sin_addr.s_addr));
513 #endif
514 			if (rt)
515 				rtfree(rt);
516 			return -1;
517 		}
518 		rtfree(rt);
519 	}
520 
521 	return 0;
522 }
523 
524 static int
525 stf_checkaddr6(struct stf_softc *sc, const struct in6_addr *in6,
526     struct ifnet *inifp /*incoming interface*/)
527 {
528 
529 	/*
530 	 * check 6to4 addresses
531 	 */
532 	if (IN6_IS_ADDR_6TO4(in6))
533 		return stf_checkaddr4(sc, GET_V4(in6), inifp);
534 
535 	/*
536 	 * reject anything that look suspicious.  the test is implemented
537 	 * in ip6_input too, but we check here as well to
538 	 * (1) reject bad packets earlier, and
539 	 * (2) to be safe against future ip6_input change.
540 	 */
541 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
542 		return -1;
543 
544 	/*
545 	 * reject link-local and site-local unicast
546 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
547 	 */
548 	if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6))
549 		return -1;
550 
551 	/*
552 	 * reject node-local and link-local multicast
553 	 * as suggested in draft-savola-v6ops-6to4-security-00.txt
554 	 */
555 	if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6))
556 		return -1;
557 
558 	return 0;
559 }
560 
561 void
562 in_stf_input(struct mbuf *m, ...)
563 {
564 	int s, off, proto;
565 	struct stf_softc *sc;
566 	struct ip *ip;
567 	struct ip6_hdr *ip6;
568 	uint8_t otos, itos;
569 	struct ifnet *ifp;
570 	size_t pktlen;
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 	pktlen = m->m_pkthdr.len;
633 	m->m_pkthdr.rcvif = ifp;
634 
635 	bpf_mtap_af(ifp, AF_INET6, m);
636 
637 	/*
638 	 * Put the packet to the network layer input queue according to the
639 	 * specified address family.
640 	 * See net/if_gif.c for possible issues with packet processing
641 	 * reorder due to extra queueing.
642 	 */
643 
644 	s = splnet();
645 	if (__predict_true(pktq_enqueue(ip6_pktq, m, 0))) {
646 		ifp->if_ipackets++;
647 		ifp->if_ibytes += pktlen;
648 	} else {
649 		m_freem(m);
650 	}
651 	splx(s);
652 }
653 
654 /* ARGSUSED */
655 static void
656 stf_rtrequest(int cmd, struct rtentry *rt,
657     const struct rt_addrinfo *info)
658 {
659 	if (rt != NULL) {
660 		struct stf_softc *sc;
661 
662 		sc = LIST_FIRST(&stf_softc_list);
663 		rt->rt_rmx.rmx_mtu = (sc != NULL) ? sc->sc_if.if_mtu : STF_MTU;
664 	}
665 }
666 
667 static int
668 stf_ioctl(struct ifnet *ifp, u_long cmd, void *data)
669 {
670 	struct ifaddr		*ifa;
671 	struct ifreq		*ifr = data;
672 	struct sockaddr_in6	*sin6;
673 	int			error;
674 
675 	error = 0;
676 	switch (cmd) {
677 	case SIOCINITIFADDR:
678 		ifa = (struct ifaddr *)data;
679 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
680 			error = EAFNOSUPPORT;
681 			break;
682 		}
683 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
684 		if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr) &&
685 		    !isrfc1918addr(GET_V4(&sin6->sin6_addr))) {
686 			ifa->ifa_rtrequest = stf_rtrequest;
687 			ifp->if_flags |= IFF_UP;
688 		} else
689 			error = EINVAL;
690 		break;
691 
692 	case SIOCADDMULTI:
693 	case SIOCDELMULTI:
694 		if (ifr != NULL &&
695 		    ifreq_getaddr(cmd, ifr)->sa_family == AF_INET6)
696 			;
697 		else
698 			error = EAFNOSUPPORT;
699 		break;
700 
701 	case SIOCSIFMTU:
702 		if (ifr->ifr_mtu < STF_MTU_MIN || ifr->ifr_mtu > STF_MTU_MAX)
703 			return EINVAL;
704 		else if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
705 			error = 0;
706 		break;
707 
708 	default:
709 		error = ifioctl_common(ifp, cmd, data);
710 		break;
711 	}
712 
713 	return error;
714 }
715