xref: /freebsd/sys/net/if_stf.c (revision 2f513db72b034fd5ef7f080b11be5c711c15186a)
1 /*	$FreeBSD$	*/
2 /*	$KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $	*/
3 
4 /*-
5  * SPDX-License-Identifier: BSD-3-Clause
6  *
7  * Copyright (C) 2000 WIDE Project.
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the project nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 /*
36  * 6to4 interface, based on RFC3056.
37  *
38  * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
39  * There is no address mapping defined from IPv6 multicast address to IPv4
40  * address.  Therefore, we do not have IFF_MULTICAST on the interface.
41  *
42  * Due to the lack of address mapping for link-local addresses, we cannot
43  * throw packets toward link-local addresses (fe80::x).  Also, we cannot throw
44  * packets to link-local multicast addresses (ff02::x).
45  *
46  * Here are interesting symptoms due to the lack of link-local address:
47  *
48  * Unicast routing exchange:
49  * - RIPng: Impossible.  Uses link-local multicast packet toward ff02::9,
50  *   and link-local addresses as nexthop.
51  * - OSPFv6: Impossible.  OSPFv6 assumes that there's link-local address
52  *   assigned to the link, and makes use of them.  Also, HELLO packets use
53  *   link-local multicast addresses (ff02::5 and ff02::6).
54  * - BGP4+: Maybe.  You can only use global address as nexthop, and global
55  *   address as TCP endpoint address.
56  *
57  * Multicast routing protocols:
58  * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
59  *   Adjacent PIM routers must be configured manually (is it really spec-wise
60  *   correct thing to do?).
61  *
62  * ICMPv6:
63  * - Redirects cannot be used due to the lack of link-local address.
64  *
65  * stf interface does not have, and will not need, a link-local address.
66  * It seems to have no real benefit and does not help the above symptoms much.
67  * Even if we assign link-locals to interface, we cannot really
68  * use link-local unicast/multicast on top of 6to4 cloud (since there's no
69  * encapsulation defined for link-local address), and the above analysis does
70  * not change.  RFC3056 does not mandate the assignment of link-local address
71  * either.
72  *
73  * 6to4 interface has security issues.  Refer to
74  * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
75  * for details.  The code tries to filter out some of malicious packets.
76  * Note that there is no way to be 100% secure.
77  */
78 
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/socket.h>
82 #include <sys/sockio.h>
83 #include <sys/mbuf.h>
84 #include <sys/errno.h>
85 #include <sys/kernel.h>
86 #include <sys/lock.h>
87 #include <sys/module.h>
88 #include <sys/proc.h>
89 #include <sys/queue.h>
90 #include <sys/rmlock.h>
91 #include <sys/sysctl.h>
92 #include <machine/cpu.h>
93 
94 #include <sys/malloc.h>
95 
96 #include <net/if.h>
97 #include <net/if_var.h>
98 #include <net/if_clone.h>
99 #include <net/route.h>
100 #include <net/netisr.h>
101 #include <net/if_types.h>
102 #include <net/vnet.h>
103 
104 #include <netinet/in.h>
105 #include <netinet/in_fib.h>
106 #include <netinet/in_systm.h>
107 #include <netinet/ip.h>
108 #include <netinet/ip_var.h>
109 #include <netinet/in_var.h>
110 
111 #include <netinet/ip6.h>
112 #include <netinet6/ip6_var.h>
113 #include <netinet6/in6_var.h>
114 #include <netinet/ip_ecn.h>
115 
116 #include <netinet/ip_encap.h>
117 
118 #include <machine/stdarg.h>
119 
120 #include <net/bpf.h>
121 
122 #include <security/mac/mac_framework.h>
123 
124 SYSCTL_DECL(_net_link);
125 static SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface");
126 
127 static int stf_permit_rfc1918 = 0;
128 SYSCTL_INT(_net_link_stf, OID_AUTO, permit_rfc1918, CTLFLAG_RWTUN,
129     &stf_permit_rfc1918, 0, "Permit the use of private IPv4 addresses");
130 
131 #define STFUNIT		0
132 
133 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
134 
135 /*
136  * XXX: Return a pointer with 16-bit aligned.  Don't cast it to
137  * struct in_addr *; use bcopy() instead.
138  */
139 #define GET_V4(x)	(&(x)->s6_addr16[1])
140 
141 struct stf_softc {
142 	struct ifnet	*sc_ifp;
143 	u_int	sc_fibnum;
144 	const struct encaptab *encap_cookie;
145 };
146 #define STF2IFP(sc)	((sc)->sc_ifp)
147 
148 static const char stfname[] = "stf";
149 
150 static MALLOC_DEFINE(M_STF, stfname, "6to4 Tunnel Interface");
151 static const int ip_stf_ttl = 40;
152 
153 static int in_stf_input(struct mbuf *, int, int, void *);
154 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
155 
156 static int stfmodevent(module_t, int, void *);
157 static int stf_encapcheck(const struct mbuf *, int, int, void *);
158 static int stf_getsrcifa6(struct ifnet *, struct in6_addr *, struct in6_addr *);
159 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
160 	struct route *);
161 static int isrfc1918addr(struct in_addr *);
162 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
163 	struct ifnet *);
164 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
165 	struct ifnet *);
166 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
167 
168 static int stf_clone_match(struct if_clone *, const char *);
169 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
170 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
171 static struct if_clone *stf_cloner;
172 
173 static const struct encap_config ipv4_encap_cfg = {
174 	.proto = IPPROTO_IPV6,
175 	.min_length = sizeof(struct ip),
176 	.exact_match = (sizeof(in_addr_t) << 3) + 8,
177 	.check = stf_encapcheck,
178 	.input = in_stf_input
179 };
180 
181 static int
182 stf_clone_match(struct if_clone *ifc, const char *name)
183 {
184 	int i;
185 
186 	for(i = 0; stfnames[i] != NULL; i++) {
187 		if (strcmp(stfnames[i], name) == 0)
188 			return (1);
189 	}
190 
191 	return (0);
192 }
193 
194 static int
195 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
196 {
197 	char *dp;
198 	int err, unit, wildcard;
199 	struct stf_softc *sc;
200 	struct ifnet *ifp;
201 
202 	err = ifc_name2unit(name, &unit);
203 	if (err != 0)
204 		return (err);
205 	wildcard = (unit < 0);
206 
207 	/*
208 	 * We can only have one unit, but since unit allocation is
209 	 * already locked, we use it to keep from allocating extra
210 	 * interfaces.
211 	 */
212 	unit = STFUNIT;
213 	err = ifc_alloc_unit(ifc, &unit);
214 	if (err != 0)
215 		return (err);
216 
217 	sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
218 	ifp = STF2IFP(sc) = if_alloc(IFT_STF);
219 	if (ifp == NULL) {
220 		free(sc, M_STF);
221 		ifc_free_unit(ifc, unit);
222 		return (ENOSPC);
223 	}
224 	ifp->if_softc = sc;
225 	sc->sc_fibnum = curthread->td_proc->p_fibnum;
226 
227 	/*
228 	 * Set the name manually rather then using if_initname because
229 	 * we don't conform to the default naming convention for interfaces.
230 	 * In the wildcard case, we need to update the name.
231 	 */
232 	if (wildcard) {
233 		for (dp = name; *dp != '\0'; dp++);
234 		if (snprintf(dp, len - (dp-name), "%d", unit) >
235 		    len - (dp-name) - 1) {
236 			/*
237 			 * This can only be a programmer error and
238 			 * there's no straightforward way to recover if
239 			 * it happens.
240 			 */
241 			panic("if_clone_create(): interface name too long");
242 		}
243 	}
244 	strlcpy(ifp->if_xname, name, IFNAMSIZ);
245 	ifp->if_dname = stfname;
246 	ifp->if_dunit = IF_DUNIT_NONE;
247 
248 	sc->encap_cookie = ip_encap_attach(&ipv4_encap_cfg, sc, M_WAITOK);
249 	if (sc->encap_cookie == NULL) {
250 		if_printf(ifp, "attach failed\n");
251 		free(sc, M_STF);
252 		ifc_free_unit(ifc, unit);
253 		return (ENOMEM);
254 	}
255 
256 	ifp->if_mtu    = IPV6_MMTU;
257 	ifp->if_ioctl  = stf_ioctl;
258 	ifp->if_output = stf_output;
259 	ifp->if_snd.ifq_maxlen = ifqmaxlen;
260 	if_attach(ifp);
261 	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
262 	return (0);
263 }
264 
265 static int
266 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
267 {
268 	struct stf_softc *sc = ifp->if_softc;
269 	int err __unused;
270 
271 	err = ip_encap_detach(sc->encap_cookie);
272 	KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
273 	bpfdetach(ifp);
274 	if_detach(ifp);
275 	if_free(ifp);
276 
277 	free(sc, M_STF);
278 	ifc_free_unit(ifc, STFUNIT);
279 
280 	return (0);
281 }
282 
283 static int
284 stfmodevent(module_t mod, int type, void *data)
285 {
286 
287 	switch (type) {
288 	case MOD_LOAD:
289 		stf_cloner = if_clone_advanced(stfname, 0, stf_clone_match,
290 		    stf_clone_create, stf_clone_destroy);
291 		break;
292 	case MOD_UNLOAD:
293 		if_clone_detach(stf_cloner);
294 		break;
295 	default:
296 		return (EOPNOTSUPP);
297 	}
298 
299 	return (0);
300 }
301 
302 static moduledata_t stf_mod = {
303 	"if_stf",
304 	stfmodevent,
305 	0
306 };
307 
308 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
309 
310 static int
311 stf_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
312 {
313 	struct ip ip;
314 	struct stf_softc *sc;
315 	struct in_addr a, b, mask;
316 	struct in6_addr addr6, mask6;
317 
318 	sc = (struct stf_softc *)arg;
319 	if (sc == NULL)
320 		return 0;
321 
322 	if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
323 		return 0;
324 
325 	/* IFF_LINK0 means "no decapsulation" */
326 	if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
327 		return 0;
328 
329 	if (proto != IPPROTO_IPV6)
330 		return 0;
331 
332 	m_copydata(m, 0, sizeof(ip), (caddr_t)&ip);
333 
334 	if (ip.ip_v != 4)
335 		return 0;
336 
337 	if (stf_getsrcifa6(STF2IFP(sc), &addr6, &mask6) != 0)
338 		return (0);
339 
340 	/*
341 	 * check if IPv4 dst matches the IPv4 address derived from the
342 	 * local 6to4 address.
343 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
344 	 */
345 	if (bcmp(GET_V4(&addr6), &ip.ip_dst, sizeof(ip.ip_dst)) != 0)
346 		return 0;
347 
348 	/*
349 	 * check if IPv4 src matches the IPv4 address derived from the
350 	 * local 6to4 address masked by prefixmask.
351 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
352 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
353 	 */
354 	bzero(&a, sizeof(a));
355 	bcopy(GET_V4(&addr6), &a, sizeof(a));
356 	bcopy(GET_V4(&mask6), &mask, sizeof(mask));
357 	a.s_addr &= mask.s_addr;
358 	b = ip.ip_src;
359 	b.s_addr &= mask.s_addr;
360 	if (a.s_addr != b.s_addr)
361 		return 0;
362 
363 	/* stf interface makes single side match only */
364 	return 32;
365 }
366 
367 static int
368 stf_getsrcifa6(struct ifnet *ifp, struct in6_addr *addr, struct in6_addr *mask)
369 {
370 	struct rm_priotracker in_ifa_tracker;
371 	struct ifaddr *ia;
372 	struct in_ifaddr *ia4;
373 	struct in6_ifaddr *ia6;
374 	struct sockaddr_in6 *sin6;
375 	struct in_addr in;
376 
377 	NET_EPOCH_ASSERT();
378 
379 	CK_STAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
380 		if (ia->ifa_addr->sa_family != AF_INET6)
381 			continue;
382 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
383 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
384 			continue;
385 
386 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
387 		IN_IFADDR_RLOCK(&in_ifa_tracker);
388 		LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
389 			if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
390 				break;
391 		IN_IFADDR_RUNLOCK(&in_ifa_tracker);
392 		if (ia4 == NULL)
393 			continue;
394 
395 		ia6 = (struct in6_ifaddr *)ia;
396 
397 		*addr = sin6->sin6_addr;
398 		*mask = ia6->ia_prefixmask.sin6_addr;
399 		return (0);
400 	}
401 
402 	return (ENOENT);
403 }
404 
405 static int
406 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
407     struct route *ro)
408 {
409 	struct stf_softc *sc;
410 	const struct sockaddr_in6 *dst6;
411 	struct in_addr in4;
412 	const void *ptr;
413 	u_int8_t tos;
414 	struct ip *ip;
415 	struct ip6_hdr *ip6;
416 	struct in6_addr addr6, mask6;
417 	int error;
418 
419 #ifdef MAC
420 	error = mac_ifnet_check_transmit(ifp, m);
421 	if (error) {
422 		m_freem(m);
423 		return (error);
424 	}
425 #endif
426 
427 	sc = ifp->if_softc;
428 	dst6 = (const struct sockaddr_in6 *)dst;
429 
430 	/* just in case */
431 	if ((ifp->if_flags & IFF_UP) == 0) {
432 		m_freem(m);
433 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
434 		return ENETDOWN;
435 	}
436 
437 	/*
438 	 * If we don't have an ip4 address that match my inner ip6 address,
439 	 * we shouldn't generate output.  Without this check, we'll end up
440 	 * using wrong IPv4 source.
441 	 */
442 	if (stf_getsrcifa6(ifp, &addr6, &mask6) != 0) {
443 		m_freem(m);
444 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
445 		return ENETDOWN;
446 	}
447 
448 	if (m->m_len < sizeof(*ip6)) {
449 		m = m_pullup(m, sizeof(*ip6));
450 		if (!m) {
451 			if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
452 			return ENOBUFS;
453 		}
454 	}
455 	ip6 = mtod(m, struct ip6_hdr *);
456 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
457 
458 	/*
459 	 * Pickup the right outer dst addr from the list of candidates.
460 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
461 	 */
462 	ptr = NULL;
463 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
464 		ptr = GET_V4(&ip6->ip6_dst);
465 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
466 		ptr = GET_V4(&dst6->sin6_addr);
467 	else {
468 		m_freem(m);
469 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
470 		return ENETUNREACH;
471 	}
472 	bcopy(ptr, &in4, sizeof(in4));
473 
474 	if (bpf_peers_present(ifp->if_bpf)) {
475 		/*
476 		 * We need to prepend the address family as
477 		 * a four byte field.  Cons up a dummy header
478 		 * to pacify bpf.  This is safe because bpf
479 		 * will only read from the mbuf (i.e., it won't
480 		 * try to free it or keep a pointer a to it).
481 		 */
482 		u_int af = AF_INET6;
483 		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
484 	}
485 
486 	M_PREPEND(m, sizeof(struct ip), M_NOWAIT);
487 	if (m == NULL) {
488 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
489 		return ENOBUFS;
490 	}
491 	ip = mtod(m, struct ip *);
492 
493 	bzero(ip, sizeof(*ip));
494 
495 	bcopy(GET_V4(&addr6), &ip->ip_src, sizeof(ip->ip_src));
496 	bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
497 	ip->ip_p = IPPROTO_IPV6;
498 	ip->ip_ttl = ip_stf_ttl;
499 	ip->ip_len = htons(m->m_pkthdr.len);
500 	if (ifp->if_flags & IFF_LINK1)
501 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
502 	else
503 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
504 
505 	M_SETFIB(m, sc->sc_fibnum);
506 	if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
507 	error = ip_output(m, NULL, NULL, 0, NULL, NULL);
508 
509 	return error;
510 }
511 
512 static int
513 isrfc1918addr(struct in_addr *in)
514 {
515 	/*
516 	 * returns 1 if private address range:
517 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
518 	 */
519 	if (stf_permit_rfc1918 == 0 && (
520 	    (ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
521 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
522 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168))
523 		return 1;
524 
525 	return 0;
526 }
527 
528 static int
529 stf_checkaddr4(struct stf_softc *sc, struct in_addr *in, struct ifnet *inifp)
530 {
531 	struct rm_priotracker in_ifa_tracker;
532 	struct in_ifaddr *ia4;
533 
534 	/*
535 	 * reject packets with the following address:
536 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
537 	 */
538 	if (IN_MULTICAST(ntohl(in->s_addr)))
539 		return -1;
540 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
541 	case 0: case 127: case 255:
542 		return -1;
543 	}
544 
545 	/*
546 	 * reject packets with private address range.
547 	 * (requirement from RFC3056 section 2 1st paragraph)
548 	 */
549 	if (isrfc1918addr(in))
550 		return -1;
551 
552 	/*
553 	 * reject packets with broadcast
554 	 */
555 	IN_IFADDR_RLOCK(&in_ifa_tracker);
556 	CK_STAILQ_FOREACH(ia4, &V_in_ifaddrhead, ia_link) {
557 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
558 			continue;
559 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
560 			IN_IFADDR_RUNLOCK(&in_ifa_tracker);
561 			return -1;
562 		}
563 	}
564 	IN_IFADDR_RUNLOCK(&in_ifa_tracker);
565 
566 	/*
567 	 * perform ingress filter
568 	 */
569 	if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
570 		struct nhop4_basic nh4;
571 
572 		if (fib4_lookup_nh_basic(sc->sc_fibnum, *in, 0, 0, &nh4) != 0)
573 			return (-1);
574 
575 		if (nh4.nh_ifp != inifp)
576 			return (-1);
577 	}
578 
579 	return 0;
580 }
581 
582 static int
583 stf_checkaddr6(struct stf_softc *sc, struct in6_addr *in6, struct ifnet *inifp)
584 {
585 	/*
586 	 * check 6to4 addresses
587 	 */
588 	if (IN6_IS_ADDR_6TO4(in6)) {
589 		struct in_addr in4;
590 		bcopy(GET_V4(in6), &in4, sizeof(in4));
591 		return stf_checkaddr4(sc, &in4, inifp);
592 	}
593 
594 	/*
595 	 * reject anything that look suspicious.  the test is implemented
596 	 * in ip6_input too, but we check here as well to
597 	 * (1) reject bad packets earlier, and
598 	 * (2) to be safe against future ip6_input change.
599 	 */
600 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
601 		return -1;
602 
603 	return 0;
604 }
605 
606 static int
607 in_stf_input(struct mbuf *m, int off, int proto, void *arg)
608 {
609 	struct stf_softc *sc = arg;
610 	struct ip *ip;
611 	struct ip6_hdr *ip6;
612 	u_int8_t otos, itos;
613 	struct ifnet *ifp;
614 
615 	NET_EPOCH_ASSERT();
616 
617 	if (proto != IPPROTO_IPV6) {
618 		m_freem(m);
619 		return (IPPROTO_DONE);
620 	}
621 
622 	ip = mtod(m, struct ip *);
623 	if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
624 		m_freem(m);
625 		return (IPPROTO_DONE);
626 	}
627 
628 	ifp = STF2IFP(sc);
629 
630 #ifdef MAC
631 	mac_ifnet_create_mbuf(ifp, m);
632 #endif
633 
634 	/*
635 	 * perform sanity check against outer src/dst.
636 	 * for source, perform ingress filter as well.
637 	 */
638 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
639 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
640 		m_freem(m);
641 		return (IPPROTO_DONE);
642 	}
643 
644 	otos = ip->ip_tos;
645 	m_adj(m, off);
646 
647 	if (m->m_len < sizeof(*ip6)) {
648 		m = m_pullup(m, sizeof(*ip6));
649 		if (!m)
650 			return (IPPROTO_DONE);
651 	}
652 	ip6 = mtod(m, struct ip6_hdr *);
653 
654 	/*
655 	 * perform sanity check against inner src/dst.
656 	 * for source, perform ingress filter as well.
657 	 */
658 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
659 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
660 		m_freem(m);
661 		return (IPPROTO_DONE);
662 	}
663 
664 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
665 	if ((ifp->if_flags & IFF_LINK1) != 0)
666 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
667 	else
668 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
669 	ip6->ip6_flow &= ~htonl(0xff << 20);
670 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
671 
672 	m->m_pkthdr.rcvif = ifp;
673 
674 	if (bpf_peers_present(ifp->if_bpf)) {
675 		/*
676 		 * We need to prepend the address family as
677 		 * a four byte field.  Cons up a dummy header
678 		 * to pacify bpf.  This is safe because bpf
679 		 * will only read from the mbuf (i.e., it won't
680 		 * try to free it or keep a pointer a to it).
681 		 */
682 		u_int32_t af = AF_INET6;
683 		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
684 	}
685 
686 	/*
687 	 * Put the packet to the network layer input queue according to the
688 	 * specified address family.
689 	 * See net/if_gif.c for possible issues with packet processing
690 	 * reorder due to extra queueing.
691 	 */
692 	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
693 	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
694 	M_SETFIB(m, ifp->if_fib);
695 	netisr_dispatch(NETISR_IPV6, m);
696 	return (IPPROTO_DONE);
697 }
698 
699 static int
700 stf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
701 {
702 	struct ifaddr *ifa;
703 	struct ifreq *ifr;
704 	struct sockaddr_in6 *sin6;
705 	struct in_addr addr;
706 	int error, mtu;
707 
708 	error = 0;
709 	switch (cmd) {
710 	case SIOCSIFADDR:
711 		ifa = (struct ifaddr *)data;
712 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
713 			error = EAFNOSUPPORT;
714 			break;
715 		}
716 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
717 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
718 			error = EINVAL;
719 			break;
720 		}
721 		bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
722 		if (isrfc1918addr(&addr)) {
723 			error = EINVAL;
724 			break;
725 		}
726 
727 		ifp->if_flags |= IFF_UP;
728 		ifp->if_drv_flags |= IFF_DRV_RUNNING;
729 		break;
730 
731 	case SIOCADDMULTI:
732 	case SIOCDELMULTI:
733 		ifr = (struct ifreq *)data;
734 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
735 			;
736 		else
737 			error = EAFNOSUPPORT;
738 		break;
739 
740 	case SIOCGIFMTU:
741 		break;
742 
743 	case SIOCSIFMTU:
744 		ifr = (struct ifreq *)data;
745 		mtu = ifr->ifr_mtu;
746 		/* RFC 4213 3.2 ideal world MTU */
747 		if (mtu < IPV6_MINMTU || mtu > IF_MAXMTU - 20)
748 			return (EINVAL);
749 		ifp->if_mtu = mtu;
750 		break;
751 
752 	default:
753 		error = EINVAL;
754 		break;
755 	}
756 
757 	return error;
758 }
759