1 /* $FreeBSD: src/sys/net/if_stf.c,v 1.1.2.11 2003/01/23 21:06:44 sam Exp $ */
2 /* $KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $ */
5 * Copyright (C) 2000 WIDE Project.
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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/protosw.h>
87 #include <sys/kernel.h>
88 #include <machine/cpu.h>
90 #include <sys/malloc.h>
93 #include <net/route.h>
94 #include <net/netisr.h>
95 #include <net/if_types.h>
96 #include <net/if_stf.h>
98 #include <netinet/in.h>
99 #include <netinet/in_systm.h>
100 #include <netinet/ip.h>
101 #include <netinet/ipprotosw.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 IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
119 #define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1]))
122 struct ifnet sc_if; /* common area */
124 struct route __sc_ro4;
125 struct route_in6 __sc_ro6; /* just for safety */
127 #define sc_ro __sc_ro46.__sc_ro4
128 const struct encaptab *encap_cookie;
131 static struct stf_softc *stf;
133 static MALLOC_DEFINE(M_STF, "stf", "6to4 Tunnel Interface");
134 static int ip_stf_ttl = 40;
136 extern struct domain inetdomain;
137 struct ipprotosw in_stf_protosw =
138 { SOCK_RAW, &inetdomain, IPPROTO_IPV6, PR_ATOMIC|PR_ADDR,
139 in_stf_input, rip_output, 0, rip_ctloutput,
145 static int stfmodevent __P((module_t, int, void *));
146 static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
147 static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
148 static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
150 static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
152 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
154 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
155 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
158 stfmodevent(mod, type, data)
163 struct stf_softc *sc;
165 const struct encaptab *p;
169 stf = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK);
170 bzero(stf, sizeof(struct stf_softc));
173 bzero(sc, sizeof(*sc));
174 sc->sc_if.if_name = "stf";
175 sc->sc_if.if_unit = 0;
177 p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck,
178 &in_stf_protosw, sc);
180 printf("%s: attach failed\n", if_name(&sc->sc_if));
183 sc->encap_cookie = p;
185 sc->sc_if.if_mtu = IPV6_MMTU;
186 sc->sc_if.if_flags = 0;
187 sc->sc_if.if_ioctl = stf_ioctl;
188 sc->sc_if.if_output = stf_output;
189 sc->sc_if.if_type = IFT_STF;
191 /* turn off ingress filter */
192 sc->sc_if.if_flags |= IFF_LINK2;
194 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
195 if_attach(&sc->sc_if);
197 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
199 bpfattach(&sc->sc_if.if_bpf, &sc->sc_if, DLT_NULL, sizeof(u_int));
204 bpfdetach(&sc->sc_if);
205 if_detach(&sc->sc_if);
206 err = encap_detach(sc->encap_cookie);
207 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
215 static moduledata_t stf_mod = {
221 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
224 stf_encapcheck(m, off, proto, arg)
225 const struct mbuf *m;
231 struct in6_ifaddr *ia6;
232 struct stf_softc *sc;
235 sc = (struct stf_softc *)arg;
239 if ((sc->sc_if.if_flags & IFF_UP) == 0)
242 /* IFF_LINK0 means "no decapsulation" */
243 if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
246 if (proto != IPPROTO_IPV6)
249 /* LINTED const cast */
250 m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
255 ia6 = stf_getsrcifa6(&sc->sc_if);
260 * check if IPv4 dst matches the IPv4 address derived from the
261 * local 6to4 address.
262 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
264 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
265 sizeof(ip.ip_dst)) != 0)
269 * check if IPv4 src matches the IPv4 address derived from the
270 * local 6to4 address masked by prefixmask.
271 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
272 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
274 bzero(&a, sizeof(a));
275 a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
276 a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
278 b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
279 if (a.s_addr != b.s_addr)
282 /* stf interface makes single side match only */
286 static struct in6_ifaddr *
291 struct in_ifaddr *ia4;
292 struct sockaddr_in6 *sin6;
295 TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list) {
296 if (ia->ifa_addr == NULL)
298 if (ia->ifa_addr->sa_family != AF_INET6)
300 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
301 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
304 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
305 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
306 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
311 return (struct in6_ifaddr *)ia;
318 stf_output(ifp, m, dst, rt)
321 struct sockaddr *dst;
324 struct stf_softc *sc;
325 struct sockaddr_in6 *dst6;
327 struct sockaddr_in *dst4;
331 struct in6_ifaddr *ia6;
333 sc = (struct stf_softc*)ifp;
334 dst6 = (struct sockaddr_in6 *)dst;
337 if ((ifp->if_flags & IFF_UP) == 0) {
343 * If we don't have an ip4 address that match my inner ip6 address,
344 * we shouldn't generate output. Without this check, we'll end up
345 * using wrong IPv4 source.
347 ia6 = stf_getsrcifa6(ifp);
353 if (m->m_len < sizeof(*ip6)) {
354 m = m_pullup(m, sizeof(*ip6));
358 ip6 = mtod(m, struct ip6_hdr *);
359 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
362 * Pickup the right outer dst addr from the list of candidates.
363 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
365 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
366 in4 = GET_V4(&ip6->ip6_dst);
367 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
368 in4 = GET_V4(&dst6->sin6_addr);
377 * We need to prepend the address family as
378 * a four byte field. Cons up a dummy header
379 * to pacify bpf. This is safe because bpf
380 * will only read from the mbuf (i.e., it won't
381 * try to free it or keep a pointer a to it).
384 u_int32_t af = AF_INET6;
388 m0.m_data = (char *)⁡
393 bpf_mtap(ifp->if_bpf, &m0);
396 #endif /*NBPFILTER > 0*/
398 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
399 if (m && m->m_len < sizeof(struct ip))
400 m = m_pullup(m, sizeof(struct ip));
403 ip = mtod(m, struct ip *);
405 bzero(ip, sizeof(*ip));
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_stf_ttl;
412 ip->ip_len = m->m_pkthdr.len; /*host order*/
413 if (ifp->if_flags & IFF_LINK1)
414 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
416 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
418 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
419 if (dst4->sin_family != AF_INET ||
420 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
421 /* cache route doesn't match */
422 dst4->sin_family = AF_INET;
423 dst4->sin_len = sizeof(struct sockaddr_in);
424 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
425 if (sc->sc_ro.ro_rt) {
426 RTFREE(sc->sc_ro.ro_rt);
427 sc->sc_ro.ro_rt = NULL;
431 if (sc->sc_ro.ro_rt == NULL) {
433 if (sc->sc_ro.ro_rt == NULL) {
439 return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
443 stf_checkaddr4(sc, in, inifp)
444 struct stf_softc *sc;
446 struct ifnet *inifp; /* incoming interface */
448 struct in_ifaddr *ia4;
451 * reject packets with the following address:
452 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
454 if (IN_MULTICAST(ntohl(in->s_addr)))
456 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
457 case 0: case 127: case 255:
462 * reject packets with broadcast
464 for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
466 ia4 = TAILQ_NEXT(ia4, ia_link))
468 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
470 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
475 * perform ingress filter
477 if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
478 struct sockaddr_in sin;
481 bzero(&sin, sizeof(sin));
482 sin.sin_family = AF_INET;
483 sin.sin_len = sizeof(struct sockaddr_in);
485 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
486 if (!rt || rt->rt_ifp != inifp) {
488 log(LOG_WARNING, "%s: packet from 0x%x dropped "
489 "due to ingress filter\n", if_name(&sc->sc_if),
490 (u_int32_t)ntohl(sin.sin_addr.s_addr));
503 stf_checkaddr6(sc, in6, inifp)
504 struct stf_softc *sc;
505 struct in6_addr *in6;
506 struct ifnet *inifp; /* incoming interface */
509 * check 6to4 addresses
511 if (IN6_IS_ADDR_6TO4(in6))
512 return stf_checkaddr4(sc, GET_V4(in6), inifp);
515 * reject anything that look suspicious. the test is implemented
516 * in ip6_input too, but we check here as well to
517 * (1) reject bad packets earlier, and
518 * (2) to be safe against future ip6_input change.
520 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
528 in_stf_input(struct mbuf *m, ...)
530 in_stf_input(m, va_alist)
535 struct stf_softc *sc;
540 struct ifqueue *ifq = NULL;
545 off = va_arg(ap, int);
546 proto = va_arg(ap, int);
549 if (proto != IPPROTO_IPV6) {
554 ip = mtod(m, struct ip *);
556 sc = (struct stf_softc *)encap_getarg(m);
558 if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
566 * perform sanity check against outer src/dst.
567 * for source, perform ingress filter as well.
569 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
570 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
578 if (m->m_len < sizeof(*ip6)) {
579 m = m_pullup(m, sizeof(*ip6));
583 ip6 = mtod(m, struct ip6_hdr *);
586 * perform sanity check against inner src/dst.
587 * for source, perform ingress filter as well.
589 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
590 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
595 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
596 if ((ifp->if_flags & IFF_LINK1) != 0)
597 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
599 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
600 ip6->ip6_flow &= ~htonl(0xff << 20);
601 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
603 m->m_pkthdr.rcvif = ifp;
607 * We need to prepend the address family as
608 * a four byte field. Cons up a dummy header
609 * to pacify bpf. This is safe because bpf
610 * will only read from the mbuf (i.e., it won't
611 * try to free it or keep a pointer a to it).
614 u_int32_t af = AF_INET6;
618 m0.m_data = (char *)⁡
623 bpf_mtap(ifp->if_bpf, &m0);
628 * Put the packet to the network layer input queue according to the
629 * specified address family.
630 * See net/if_gif.c for possible issues with packet processing
631 * reorder due to extra queueing.
638 IF_DROP(ifq); /* update statistics */
646 ifp->if_ibytes += m->m_pkthdr.len;
652 stf_rtrequest(cmd, rt, info)
655 struct rt_addrinfo *info;
659 rt->rt_rmx.rmx_mtu = IPV6_MMTU;
663 stf_ioctl(ifp, cmd, data)
670 struct sockaddr_in6 *sin6;
676 ifa = (struct ifaddr *)data;
677 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
678 error = EAFNOSUPPORT;
681 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
682 if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
683 ifa->ifa_rtrequest = stf_rtrequest;
684 ifp->if_flags |= IFF_UP;
691 ifr = (struct ifreq *)data;
692 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
695 error = EAFNOSUPPORT;