xref: /freebsd/sys/net/if_stf.c (revision ad30f8e79bd1007cc2476e491bd21b4f5e389e0a) 
1 /*	$FreeBSD$	*/
2 /*	$KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi 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 "opt_inet.h"
78 #include "opt_inet6.h"
79 
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/socket.h>
83 #include <sys/sockio.h>
84 #include <sys/mbuf.h>
85 #include <sys/errno.h>
86 #include <sys/kernel.h>
87 #include <sys/module.h>
88 #include <sys/protosw.h>
89 #include <sys/proc.h>
90 #include <sys/queue.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_clone.h>
98 #include <net/route.h>
99 #include <net/netisr.h>
100 #include <net/if_types.h>
101 #include <net/if_stf.h>
102 #include <net/vnet.h>
103 
104 #include <netinet/in.h>
105 #include <netinet/in_systm.h>
106 #include <netinet/ip.h>
107 #include <netinet/ip_var.h>
108 #include <netinet/in_var.h>
109 
110 #include <netinet/ip6.h>
111 #include <netinet6/ip6_var.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/bpf.h>
120 
121 #include <security/mac/mac_framework.h>
122 
123 SYSCTL_DECL(_net_link);
124 SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface");
125 
126 static int stf_route_cache = 1;
127 SYSCTL_INT(_net_link_stf, OID_AUTO, route_cache, CTLFLAG_RW,
128     &stf_route_cache, 0, "Caching of IPv4 routes for 6to4 Output");
129 
130 #define STFNAME		"stf"
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)	((caddr_t)(&(x)->s6_addr16[1]))
140 
141 struct stf_softc {
142 	struct ifnet	*sc_ifp;
143 	union {
144 		struct route  __sc_ro4;
145 		struct route_in6 __sc_ro6; /* just for safety */
146 	} __sc_ro46;
147 #define sc_ro	__sc_ro46.__sc_ro4
148 	struct mtx	sc_ro_mtx;
149 	u_int	sc_fibnum;
150 	const struct encaptab *encap_cookie;
151 };
152 #define STF2IFP(sc)	((sc)->sc_ifp)
153 
154 /*
155  * Note that mutable fields in the softc are not currently locked.
156  * We do lock sc_ro in stf_output though.
157  */
158 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
159 static const int ip_stf_ttl = 40;
160 
161 extern  struct domain inetdomain;
162 struct protosw in_stf_protosw = {
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 =		(pr_output_t *)rip_output,
169 	.pr_ctloutput =		rip_ctloutput,
170 	.pr_usrreqs =		&rip_usrreqs
171 };
172 
173 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
174 
175 static int stfmodevent(module_t, int, void *);
176 static int stf_encapcheck(const struct mbuf *, int, int, void *);
177 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
178 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
179 	struct route *);
180 static int isrfc1918addr(struct in_addr *);
181 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
182 	struct ifnet *);
183 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
184 	struct ifnet *);
185 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
186 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
187 
188 static int stf_clone_match(struct if_clone *, const char *);
189 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
190 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
191 struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0,
192     NULL, stf_clone_match, stf_clone_create, stf_clone_destroy);
193 
194 static int
195 stf_clone_match(struct if_clone *ifc, const char *name)
196 {
197 	int i;
198 
199 	for(i = 0; stfnames[i] != NULL; i++) {
200 		if (strcmp(stfnames[i], name) == 0)
201 			return (1);
202 	}
203 
204 	return (0);
205 }
206 
207 static int
208 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
209 {
210 	int err, unit;
211 	struct stf_softc *sc;
212 	struct ifnet *ifp;
213 
214 	/*
215 	 * We can only have one unit, but since unit allocation is
216 	 * already locked, we use it to keep from allocating extra
217 	 * interfaces.
218 	 */
219 	unit = STFUNIT;
220 	err = ifc_alloc_unit(ifc, &unit);
221 	if (err != 0)
222 		return (err);
223 
224 	sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
225 	ifp = STF2IFP(sc) = if_alloc(IFT_STF);
226 	if (ifp == NULL) {
227 		free(sc, M_STF);
228 		ifc_free_unit(ifc, unit);
229 		return (ENOSPC);
230 	}
231 	ifp->if_softc = sc;
232 	sc->sc_fibnum = curthread->td_proc->p_fibnum;
233 
234 	/*
235 	 * Set the name manually rather then using if_initname because
236 	 * we don't conform to the default naming convention for interfaces.
237 	 */
238 	strlcpy(ifp->if_xname, name, IFNAMSIZ);
239 	ifp->if_dname = ifc->ifc_name;
240 	ifp->if_dunit = IF_DUNIT_NONE;
241 
242 	mtx_init(&(sc)->sc_ro_mtx, "stf ro", NULL, MTX_DEF);
243 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
244 	    stf_encapcheck, &in_stf_protosw, sc);
245 	if (sc->encap_cookie == NULL) {
246 		if_printf(ifp, "attach failed\n");
247 		free(sc, M_STF);
248 		ifc_free_unit(ifc, unit);
249 		return (ENOMEM);
250 	}
251 
252 	ifp->if_mtu    = IPV6_MMTU;
253 	ifp->if_ioctl  = stf_ioctl;
254 	ifp->if_output = stf_output;
255 	ifp->if_snd.ifq_maxlen = ifqmaxlen;
256 	if_attach(ifp);
257 	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
258 	return (0);
259 }
260 
261 static int
262 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
263 {
264 	struct stf_softc *sc = ifp->if_softc;
265 	int err;
266 
267 	err = encap_detach(sc->encap_cookie);
268 	KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
269 	mtx_destroy(&(sc)->sc_ro_mtx);
270 	bpfdetach(ifp);
271 	if_detach(ifp);
272 	if_free(ifp);
273 
274 	free(sc, M_STF);
275 	ifc_free_unit(ifc, STFUNIT);
276 
277 	return (0);
278 }
279 
280 static int
281 stfmodevent(mod, type, data)
282 	module_t mod;
283 	int type;
284 	void *data;
285 {
286 
287 	switch (type) {
288 	case MOD_LOAD:
289 		if_clone_attach(&stf_cloner);
290 		break;
291 	case MOD_UNLOAD:
292 		if_clone_detach(&stf_cloner);
293 		break;
294 	default:
295 		return (EOPNOTSUPP);
296 	}
297 
298 	return (0);
299 }
300 
301 static moduledata_t stf_mod = {
302 	"if_stf",
303 	stfmodevent,
304 	0
305 };
306 
307 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
308 
309 static int
310 stf_encapcheck(m, off, proto, arg)
311 	const struct mbuf *m;
312 	int off;
313 	int proto;
314 	void *arg;
315 {
316 	struct ip ip;
317 	struct in6_ifaddr *ia6;
318 	struct stf_softc *sc;
319 	struct in_addr a, b, mask;
320 
321 	sc = (struct stf_softc *)arg;
322 	if (sc == NULL)
323 		return 0;
324 
325 	if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
326 		return 0;
327 
328 	/* IFF_LINK0 means "no decapsulation" */
329 	if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
330 		return 0;
331 
332 	if (proto != IPPROTO_IPV6)
333 		return 0;
334 
335 	/* LINTED const cast */
336 	m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
337 
338 	if (ip.ip_v != 4)
339 		return 0;
340 
341 	ia6 = stf_getsrcifa6(STF2IFP(sc));
342 	if (ia6 == NULL)
343 		return 0;
344 
345 	/*
346 	 * check if IPv4 dst matches the IPv4 address derived from the
347 	 * local 6to4 address.
348 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
349 	 */
350 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
351 	    sizeof(ip.ip_dst)) != 0) {
352 		ifa_free(&ia6->ia_ifa);
353 		return 0;
354 	}
355 
356 	/*
357 	 * check if IPv4 src matches the IPv4 address derived from the
358 	 * local 6to4 address masked by prefixmask.
359 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
360 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
361 	 */
362 	bzero(&a, sizeof(a));
363 	bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
364 	bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
365 	ifa_free(&ia6->ia_ifa);
366 	a.s_addr &= mask.s_addr;
367 	b = ip.ip_src;
368 	b.s_addr &= mask.s_addr;
369 	if (a.s_addr != b.s_addr)
370 		return 0;
371 
372 	/* stf interface makes single side match only */
373 	return 32;
374 }
375 
376 static struct in6_ifaddr *
377 stf_getsrcifa6(ifp)
378 	struct ifnet *ifp;
379 {
380 	struct ifaddr *ia;
381 	struct in_ifaddr *ia4;
382 	struct sockaddr_in6 *sin6;
383 	struct in_addr in;
384 
385 	if_addr_rlock(ifp);
386 	TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
387 		if (ia->ifa_addr->sa_family != AF_INET6)
388 			continue;
389 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
390 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
391 			continue;
392 
393 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
394 		LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
395 			if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
396 				break;
397 		if (ia4 == NULL)
398 			continue;
399 
400 		ifa_ref(ia);
401 		if_addr_runlock(ifp);
402 		return (struct in6_ifaddr *)ia;
403 	}
404 	if_addr_runlock(ifp);
405 
406 	return NULL;
407 }
408 
409 static int
410 stf_output(ifp, m, dst, ro)
411 	struct ifnet *ifp;
412 	struct mbuf *m;
413 	struct sockaddr *dst;
414 	struct route *ro;
415 {
416 	struct stf_softc *sc;
417 	struct sockaddr_in6 *dst6;
418 	struct route *cached_route;
419 	struct in_addr in4;
420 	caddr_t ptr;
421 	struct sockaddr_in *dst4;
422 	u_int8_t tos;
423 	struct ip *ip;
424 	struct ip6_hdr *ip6;
425 	struct in6_ifaddr *ia6;
426 	u_int32_t af;
427 	int error;
428 
429 #ifdef MAC
430 	error = mac_ifnet_check_transmit(ifp, m);
431 	if (error) {
432 		m_freem(m);
433 		return (error);
434 	}
435 #endif
436 
437 	sc = ifp->if_softc;
438 	dst6 = (struct sockaddr_in6 *)dst;
439 
440 	/* just in case */
441 	if ((ifp->if_flags & IFF_UP) == 0) {
442 		m_freem(m);
443 		ifp->if_oerrors++;
444 		return ENETDOWN;
445 	}
446 
447 	/*
448 	 * If we don't have an ip4 address that match my inner ip6 address,
449 	 * we shouldn't generate output.  Without this check, we'll end up
450 	 * using wrong IPv4 source.
451 	 */
452 	ia6 = stf_getsrcifa6(ifp);
453 	if (ia6 == NULL) {
454 		m_freem(m);
455 		ifp->if_oerrors++;
456 		return ENETDOWN;
457 	}
458 
459 	if (m->m_len < sizeof(*ip6)) {
460 		m = m_pullup(m, sizeof(*ip6));
461 		if (!m) {
462 			ifa_free(&ia6->ia_ifa);
463 			ifp->if_oerrors++;
464 			return ENOBUFS;
465 		}
466 	}
467 	ip6 = mtod(m, struct ip6_hdr *);
468 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
469 
470 	/*
471 	 * BPF writes need to be handled specially.
472 	 * This is a null operation, nothing here checks dst->sa_family.
473 	 */
474 	if (dst->sa_family == AF_UNSPEC) {
475 		bcopy(dst->sa_data, &af, sizeof(af));
476 		dst->sa_family = af;
477 	}
478 
479 	/*
480 	 * Pickup the right outer dst addr from the list of candidates.
481 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
482 	 */
483 	ptr = NULL;
484 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
485 		ptr = GET_V4(&ip6->ip6_dst);
486 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
487 		ptr = GET_V4(&dst6->sin6_addr);
488 	else {
489 		ifa_free(&ia6->ia_ifa);
490 		m_freem(m);
491 		ifp->if_oerrors++;
492 		return ENETUNREACH;
493 	}
494 	bcopy(ptr, &in4, sizeof(in4));
495 
496 	if (bpf_peers_present(ifp->if_bpf)) {
497 		/*
498 		 * We need to prepend the address family as
499 		 * a four byte field.  Cons up a dummy header
500 		 * to pacify bpf.  This is safe because bpf
501 		 * will only read from the mbuf (i.e., it won't
502 		 * try to free it or keep a pointer a to it).
503 		 */
504 		af = AF_INET6;
505 		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
506 	}
507 
508 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
509 	if (m && m->m_len < sizeof(struct ip))
510 		m = m_pullup(m, sizeof(struct ip));
511 	if (m == NULL) {
512 		ifa_free(&ia6->ia_ifa);
513 		ifp->if_oerrors++;
514 		return ENOBUFS;
515 	}
516 	ip = mtod(m, struct ip *);
517 
518 	bzero(ip, sizeof(*ip));
519 
520 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
521 	    &ip->ip_src, sizeof(ip->ip_src));
522 	ifa_free(&ia6->ia_ifa);
523 	bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
524 	ip->ip_p = IPPROTO_IPV6;
525 	ip->ip_ttl = ip_stf_ttl;
526 	ip->ip_len = m->m_pkthdr.len;	/*host order*/
527 	if (ifp->if_flags & IFF_LINK1)
528 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
529 	else
530 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
531 
532 	if (!stf_route_cache) {
533 		cached_route = NULL;
534 		goto sendit;
535 	}
536 
537 	/*
538 	 * Do we have a cached route?
539 	 */
540 	mtx_lock(&(sc)->sc_ro_mtx);
541 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
542 	if (dst4->sin_family != AF_INET ||
543 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
544 		/* cache route doesn't match */
545 		dst4->sin_family = AF_INET;
546 		dst4->sin_len = sizeof(struct sockaddr_in);
547 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
548 		if (sc->sc_ro.ro_rt) {
549 			RTFREE(sc->sc_ro.ro_rt);
550 			sc->sc_ro.ro_rt = NULL;
551 		}
552 	}
553 
554 	if (sc->sc_ro.ro_rt == NULL) {
555 		rtalloc_fib(&sc->sc_ro, sc->sc_fibnum);
556 		if (sc->sc_ro.ro_rt == NULL) {
557 			m_freem(m);
558 			mtx_unlock(&(sc)->sc_ro_mtx);
559 			ifp->if_oerrors++;
560 			return ENETUNREACH;
561 		}
562 	}
563 	cached_route = &sc->sc_ro;
564 
565 sendit:
566 	M_SETFIB(m, sc->sc_fibnum);
567 	ifp->if_opackets++;
568 	error = ip_output(m, NULL, cached_route, 0, NULL, NULL);
569 
570 	if (cached_route != NULL)
571 		mtx_unlock(&(sc)->sc_ro_mtx);
572 	return error;
573 }
574 
575 static int
576 isrfc1918addr(in)
577 	struct in_addr *in;
578 {
579 	/*
580 	 * returns 1 if private address range:
581 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
582 	 */
583 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
584 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
585 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
586 		return 1;
587 
588 	return 0;
589 }
590 
591 static int
592 stf_checkaddr4(sc, in, inifp)
593 	struct stf_softc *sc;
594 	struct in_addr *in;
595 	struct ifnet *inifp;	/* incoming interface */
596 {
597 	struct in_ifaddr *ia4;
598 
599 	/*
600 	 * reject packets with the following address:
601 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
602 	 */
603 	if (IN_MULTICAST(ntohl(in->s_addr)))
604 		return -1;
605 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
606 	case 0: case 127: case 255:
607 		return -1;
608 	}
609 
610 	/*
611 	 * reject packets with private address range.
612 	 * (requirement from RFC3056 section 2 1st paragraph)
613 	 */
614 	if (isrfc1918addr(in))
615 		return -1;
616 
617 	/*
618 	 * reject packets with broadcast
619 	 */
620 	IN_IFADDR_RLOCK();
621 	for (ia4 = TAILQ_FIRST(&V_in_ifaddrhead);
622 	     ia4;
623 	     ia4 = TAILQ_NEXT(ia4, ia_link))
624 	{
625 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
626 			continue;
627 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
628 			IN_IFADDR_RUNLOCK();
629 			return -1;
630 		}
631 	}
632 	IN_IFADDR_RUNLOCK();
633 
634 	/*
635 	 * perform ingress filter
636 	 */
637 	if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
638 		struct sockaddr_in sin;
639 		struct rtentry *rt;
640 
641 		bzero(&sin, sizeof(sin));
642 		sin.sin_family = AF_INET;
643 		sin.sin_len = sizeof(struct sockaddr_in);
644 		sin.sin_addr = *in;
645 		rt = rtalloc1_fib((struct sockaddr *)&sin, 0,
646 		    0UL, sc->sc_fibnum);
647 		if (!rt || rt->rt_ifp != inifp) {
648 #if 0
649 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
650 			    "due to ingress filter\n", if_name(STF2IFP(sc)),
651 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
652 #endif
653 			if (rt)
654 				RTFREE_LOCKED(rt);
655 			return -1;
656 		}
657 		RTFREE_LOCKED(rt);
658 	}
659 
660 	return 0;
661 }
662 
663 static int
664 stf_checkaddr6(sc, in6, inifp)
665 	struct stf_softc *sc;
666 	struct in6_addr *in6;
667 	struct ifnet *inifp;	/* incoming interface */
668 {
669 	/*
670 	 * check 6to4 addresses
671 	 */
672 	if (IN6_IS_ADDR_6TO4(in6)) {
673 		struct in_addr in4;
674 		bcopy(GET_V4(in6), &in4, sizeof(in4));
675 		return stf_checkaddr4(sc, &in4, inifp);
676 	}
677 
678 	/*
679 	 * reject anything that look suspicious.  the test is implemented
680 	 * in ip6_input too, but we check here as well to
681 	 * (1) reject bad packets earlier, and
682 	 * (2) to be safe against future ip6_input change.
683 	 */
684 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
685 		return -1;
686 
687 	return 0;
688 }
689 
690 void
691 in_stf_input(m, off)
692 	struct mbuf *m;
693 	int off;
694 {
695 	int proto;
696 	struct stf_softc *sc;
697 	struct ip *ip;
698 	struct ip6_hdr *ip6;
699 	u_int8_t otos, itos;
700 	struct ifnet *ifp;
701 
702 	proto = mtod(m, struct ip *)->ip_p;
703 
704 	if (proto != IPPROTO_IPV6) {
705 		m_freem(m);
706 		return;
707 	}
708 
709 	ip = mtod(m, struct ip *);
710 
711 	sc = (struct stf_softc *)encap_getarg(m);
712 
713 	if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
714 		m_freem(m);
715 		return;
716 	}
717 
718 	ifp = STF2IFP(sc);
719 
720 #ifdef MAC
721 	mac_ifnet_create_mbuf(ifp, m);
722 #endif
723 
724 	/*
725 	 * perform sanity check against outer src/dst.
726 	 * for source, perform ingress filter as well.
727 	 */
728 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
729 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
730 		m_freem(m);
731 		return;
732 	}
733 
734 	otos = ip->ip_tos;
735 	m_adj(m, off);
736 
737 	if (m->m_len < sizeof(*ip6)) {
738 		m = m_pullup(m, sizeof(*ip6));
739 		if (!m)
740 			return;
741 	}
742 	ip6 = mtod(m, struct ip6_hdr *);
743 
744 	/*
745 	 * perform sanity check against inner src/dst.
746 	 * for source, perform ingress filter as well.
747 	 */
748 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
749 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
750 		m_freem(m);
751 		return;
752 	}
753 
754 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
755 	if ((ifp->if_flags & IFF_LINK1) != 0)
756 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
757 	else
758 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
759 	ip6->ip6_flow &= ~htonl(0xff << 20);
760 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
761 
762 	m->m_pkthdr.rcvif = ifp;
763 
764 	if (bpf_peers_present(ifp->if_bpf)) {
765 		/*
766 		 * We need to prepend the address family as
767 		 * a four byte field.  Cons up a dummy header
768 		 * to pacify bpf.  This is safe because bpf
769 		 * will only read from the mbuf (i.e., it won't
770 		 * try to free it or keep a pointer a to it).
771 		 */
772 		u_int32_t af = AF_INET6;
773 		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
774 	}
775 
776 	/*
777 	 * Put the packet to the network layer input queue according to the
778 	 * specified address family.
779 	 * See net/if_gif.c for possible issues with packet processing
780 	 * reorder due to extra queueing.
781 	 */
782 	ifp->if_ipackets++;
783 	ifp->if_ibytes += m->m_pkthdr.len;
784 	netisr_dispatch(NETISR_IPV6, m);
785 }
786 
787 /* ARGSUSED */
788 static void
789 stf_rtrequest(cmd, rt, info)
790 	int cmd;
791 	struct rtentry *rt;
792 	struct rt_addrinfo *info;
793 {
794 	RT_LOCK_ASSERT(rt);
795 	rt->rt_rmx.rmx_mtu = IPV6_MMTU;
796 }
797 
798 static int
799 stf_ioctl(ifp, cmd, data)
800 	struct ifnet *ifp;
801 	u_long cmd;
802 	caddr_t data;
803 {
804 	struct ifaddr *ifa;
805 	struct ifreq *ifr;
806 	struct sockaddr_in6 *sin6;
807 	struct in_addr addr;
808 	int error;
809 
810 	error = 0;
811 	switch (cmd) {
812 	case SIOCSIFADDR:
813 		ifa = (struct ifaddr *)data;
814 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
815 			error = EAFNOSUPPORT;
816 			break;
817 		}
818 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
819 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
820 			error = EINVAL;
821 			break;
822 		}
823 		bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
824 		if (isrfc1918addr(&addr)) {
825 			error = EINVAL;
826 			break;
827 		}
828 
829 		ifa->ifa_rtrequest = stf_rtrequest;
830 		ifp->if_flags |= IFF_UP;
831 		break;
832 
833 	case SIOCADDMULTI:
834 	case SIOCDELMULTI:
835 		ifr = (struct ifreq *)data;
836 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
837 			;
838 		else
839 			error = EAFNOSUPPORT;
840 		break;
841 
842 	default:
843 		error = EINVAL;
844 		break;
845 	}
846 
847 	return error;
848 }
849