2 /* $KAME: if_stf.c,v 1.62 2001/06/07 22:32:16 itojun Exp $ */
5 * Copyright (C) 2000 WIDE Project.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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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
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17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
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
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27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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34 * 6to4 interface, based on RFC3056.
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.
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).
44 * Here are interesting symptoms due to the lack of link-local address:
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.
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?).
61 * - Redirects cannot be used due to the lack of link-local address.
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
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.
78 #include "opt_inet6.h"
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/socket.h>
83 #include <sys/sockio.h>
85 #include <sys/errno.h>
86 #include <sys/kernel.h>
87 #include <sys/protosw.h>
88 #include <sys/queue.h>
89 #include <machine/cpu.h>
91 #include <sys/malloc.h>
94 #include <net/route.h>
95 #include <net/netisr.h>
96 #include <net/if_types.h>
97 #include <net/if_stf.h>
99 #include <netinet/in.h>
100 #include <netinet/in_systm.h>
101 #include <netinet/ip.h>
102 #include <netinet/ip_var.h>
103 #include <netinet/in_var.h>
105 #include <netinet/ip6.h>
106 #include <netinet6/ip6_var.h>
107 #include <netinet6/in6_var.h>
108 #include <netinet/ip_ecn.h>
110 #include <netinet/ip_encap.h>
112 #include <machine/stdarg.h>
114 #include <net/net_osdep.h>
118 #define STFNAME "stf"
120 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
121 #define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1]))
124 struct ifnet sc_if; /* common area */
126 struct route __sc_ro4;
127 struct route_in6 __sc_ro6; /* just for safety */
129 #define sc_ro __sc_ro46.__sc_ro4
130 const struct encaptab *encap_cookie;
131 LIST_ENTRY(stf_softc) sc_list; /* all stf's are linked */
134 static LIST_HEAD(, stf_softc) stf_softc_list;
136 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
137 static int ip_stf_ttl = 40;
139 extern struct domain inetdomain;
140 struct protosw in_stf_protosw =
141 { SOCK_RAW, &inetdomain, IPPROTO_IPV6, PR_ATOMIC|PR_ADDR,
142 in_stf_input, (pr_output_t*)rip_output, 0, rip_ctloutput,
148 static int stfmodevent(module_t, int, void *);
149 static int stf_encapcheck(const struct mbuf *, int, int, void *);
150 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
151 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
153 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
155 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
157 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
158 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
160 int stf_clone_create(struct if_clone *, int);
161 int stf_clone_destroy(struct ifnet *);
163 /* only one clone is currently allowed */
164 struct if_clone stf_cloner =
165 IF_CLONE_INITIALIZER(STFNAME, stf_clone_create, stf_clone_destroy, 0);
168 stf_clone_create(ifc, unit)
169 struct if_clone *ifc;
172 struct stf_softc *sc;
174 sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
175 sc->sc_if.if_name = STFNAME;
176 sc->sc_if.if_unit = unit;
178 sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
179 stf_encapcheck, &in_stf_protosw, sc);
180 if (sc->encap_cookie == NULL) {
181 printf("%s: attach failed\n", if_name(&sc->sc_if));
186 sc->sc_if.if_mtu = IPV6_MMTU;
187 sc->sc_if.if_ioctl = stf_ioctl;
188 sc->sc_if.if_output = stf_output;
189 sc->sc_if.if_type = IFT_STF;
190 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
191 if_attach(&sc->sc_if);
192 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
193 LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
198 stf_clone_destroy(ifp)
202 struct stf_softc *sc = (void *) ifp;
204 LIST_REMOVE(sc, sc_list);
205 err = encap_detach(sc->encap_cookie);
206 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
215 stfmodevent(mod, type, data)
223 LIST_INIT(&stf_softc_list);
224 if_clone_attach(&stf_cloner);
228 if_clone_detach(&stf_cloner);
230 while (!LIST_EMPTY(&stf_softc_list))
231 stf_clone_destroy(&LIST_FIRST(&stf_softc_list)->sc_if);
238 static moduledata_t stf_mod = {
244 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
247 stf_encapcheck(m, off, proto, arg)
248 const struct mbuf *m;
254 struct in6_ifaddr *ia6;
255 struct stf_softc *sc;
258 sc = (struct stf_softc *)arg;
262 if ((sc->sc_if.if_flags & IFF_UP) == 0)
265 /* IFF_LINK0 means "no decapsulation" */
266 if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
269 if (proto != IPPROTO_IPV6)
272 /* LINTED const cast */
273 m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
278 ia6 = stf_getsrcifa6(&sc->sc_if);
283 * check if IPv4 dst matches the IPv4 address derived from the
284 * local 6to4 address.
285 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
287 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
288 sizeof(ip.ip_dst)) != 0)
292 * check if IPv4 src matches the IPv4 address derived from the
293 * local 6to4 address masked by prefixmask.
294 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
295 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
297 bzero(&a, sizeof(a));
298 a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
299 a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
301 b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
302 if (a.s_addr != b.s_addr)
305 /* stf interface makes single side match only */
309 static struct in6_ifaddr *
314 struct in_ifaddr *ia4;
315 struct sockaddr_in6 *sin6;
318 for (ia = TAILQ_FIRST(&ifp->if_addrlist);
320 ia = TAILQ_NEXT(ia, ifa_list))
322 if (ia->ifa_addr == NULL)
324 if (ia->ifa_addr->sa_family != AF_INET6)
326 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
327 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
330 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
331 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
332 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
337 return (struct in6_ifaddr *)ia;
344 stf_output(ifp, m, dst, rt)
347 struct sockaddr *dst;
350 struct stf_softc *sc;
351 struct sockaddr_in6 *dst6;
353 struct sockaddr_in *dst4;
357 struct in6_ifaddr *ia6;
359 sc = (struct stf_softc*)ifp;
360 dst6 = (struct sockaddr_in6 *)dst;
363 if ((ifp->if_flags & IFF_UP) == 0) {
369 * If we don't have an ip4 address that match my inner ip6 address,
370 * we shouldn't generate output. Without this check, we'll end up
371 * using wrong IPv4 source.
373 ia6 = stf_getsrcifa6(ifp);
379 if (m->m_len < sizeof(*ip6)) {
380 m = m_pullup(m, sizeof(*ip6));
384 ip6 = mtod(m, struct ip6_hdr *);
385 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
388 * Pickup the right outer dst addr from the list of candidates.
389 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
391 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
392 in4 = GET_V4(&ip6->ip6_dst);
393 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
394 in4 = GET_V4(&dst6->sin6_addr);
403 * We need to prepend the address family as
404 * a four byte field. Cons up a dummy header
405 * to pacify bpf. This is safe because bpf
406 * will only read from the mbuf (i.e., it won't
407 * try to free it or keep a pointer a to it).
410 u_int32_t af = AF_INET6;
414 m0.m_data = (char *)⁡
419 bpf_mtap(ifp->if_bpf, &m0);
422 #endif /*NBPFILTER > 0*/
424 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
425 if (m && m->m_len < sizeof(struct ip))
426 m = m_pullup(m, sizeof(struct ip));
429 ip = mtod(m, struct ip *);
431 bzero(ip, sizeof(*ip));
433 bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
434 &ip->ip_src, sizeof(ip->ip_src));
435 bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
436 ip->ip_p = IPPROTO_IPV6;
437 ip->ip_ttl = ip_stf_ttl;
438 ip->ip_len = m->m_pkthdr.len; /*host order*/
439 if (ifp->if_flags & IFF_LINK1)
440 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
442 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
444 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
445 if (dst4->sin_family != AF_INET ||
446 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
447 /* cache route doesn't match */
448 dst4->sin_family = AF_INET;
449 dst4->sin_len = sizeof(struct sockaddr_in);
450 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
451 if (sc->sc_ro.ro_rt) {
452 RTFREE(sc->sc_ro.ro_rt);
453 sc->sc_ro.ro_rt = NULL;
457 if (sc->sc_ro.ro_rt == NULL) {
459 if (sc->sc_ro.ro_rt == NULL) {
465 return ip_output(m, NULL, &sc->sc_ro, 0, NULL);
469 stf_checkaddr4(sc, in, inifp)
470 struct stf_softc *sc;
472 struct ifnet *inifp; /* incoming interface */
474 struct in_ifaddr *ia4;
477 * reject packets with the following address:
478 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
480 if (IN_MULTICAST(ntohl(in->s_addr)))
482 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
483 case 0: case 127: case 255:
488 * reject packets with broadcast
490 for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
492 ia4 = TAILQ_NEXT(ia4, ia_link))
494 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
496 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
501 * perform ingress filter
503 if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
504 struct sockaddr_in sin;
507 bzero(&sin, sizeof(sin));
508 sin.sin_family = AF_INET;
509 sin.sin_len = sizeof(struct sockaddr_in);
511 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
512 if (!rt || rt->rt_ifp != inifp) {
514 log(LOG_WARNING, "%s: packet from 0x%x dropped "
515 "due to ingress filter\n", if_name(&sc->sc_if),
516 (u_int32_t)ntohl(sin.sin_addr.s_addr));
529 stf_checkaddr6(sc, in6, inifp)
530 struct stf_softc *sc;
531 struct in6_addr *in6;
532 struct ifnet *inifp; /* incoming interface */
535 * check 6to4 addresses
537 if (IN6_IS_ADDR_6TO4(in6))
538 return stf_checkaddr4(sc, GET_V4(in6), inifp);
541 * reject anything that look suspicious. the test is implemented
542 * in ip6_input too, but we check here as well to
543 * (1) reject bad packets earlier, and
544 * (2) to be safe against future ip6_input change.
546 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
558 struct stf_softc *sc;
563 struct ifqueue *ifq = NULL;
566 proto = mtod(m, struct ip *)->ip_p;
568 if (proto != IPPROTO_IPV6) {
573 ip = mtod(m, struct ip *);
575 sc = (struct stf_softc *)encap_getarg(m);
577 if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
585 * perform sanity check against outer src/dst.
586 * for source, perform ingress filter as well.
588 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
589 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
597 if (m->m_len < sizeof(*ip6)) {
598 m = m_pullup(m, sizeof(*ip6));
602 ip6 = mtod(m, struct ip6_hdr *);
605 * perform sanity check against inner src/dst.
606 * for source, perform ingress filter as well.
608 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
609 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
614 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
615 if ((ifp->if_flags & IFF_LINK1) != 0)
616 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
618 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
619 ip6->ip6_flow &= ~htonl(0xff << 20);
620 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
622 m->m_pkthdr.rcvif = ifp;
626 * We need to prepend the address family as
627 * a four byte field. Cons up a dummy header
628 * to pacify bpf. This is safe because bpf
629 * will only read from the mbuf (i.e., it won't
630 * try to free it or keep a pointer a to it).
633 u_int32_t af = AF_INET6;
637 m0.m_data = (char *)⁡
642 bpf_mtap(ifp->if_bpf, &m0);
647 * Put the packet to the network layer input queue according to the
648 * specified address family.
649 * See net/if_gif.c for possible issues with packet processing
650 * reorder due to extra queueing.
655 len = m->m_pkthdr.len;
656 if (! IF_HANDOFF(ifq, m, NULL))
660 ifp->if_ibytes += len;
665 stf_rtrequest(cmd, rt, info)
668 struct rt_addrinfo *info;
672 rt->rt_rmx.rmx_mtu = IPV6_MMTU;
676 stf_ioctl(ifp, cmd, data)
683 struct sockaddr_in6 *sin6;
689 ifa = (struct ifaddr *)data;
690 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
691 error = EAFNOSUPPORT;
694 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
695 if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
696 ifa->ifa_rtrequest = stf_rtrequest;
697 ifp->if_flags |= IFF_UP;
704 ifr = (struct ifreq *)data;
705 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
708 error = EAFNOSUPPORT;