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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9 * modification, are permitted provided that the following conditions
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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"
81 #include <sys/param.h>
82 #include <sys/systm.h>
83 #include <sys/socket.h>
84 #include <sys/sockio.h>
86 #include <sys/errno.h>
87 #include <sys/kernel.h>
88 #include <sys/module.h>
89 #include <sys/protosw.h>
90 #include <sys/queue.h>
91 #include <machine/cpu.h>
93 #include <sys/malloc.h>
96 #include <net/if_clone.h>
97 #include <net/route.h>
98 #include <net/netisr.h>
99 #include <net/if_types.h>
100 #include <net/if_stf.h>
102 #include <netinet/in.h>
103 #include <netinet/in_systm.h>
104 #include <netinet/ip.h>
105 #include <netinet/ip_var.h>
106 #include <netinet/in_var.h>
108 #include <netinet/ip6.h>
109 #include <netinet6/ip6_var.h>
110 #include <netinet6/in6_var.h>
111 #include <netinet/ip_ecn.h>
113 #include <netinet/ip_encap.h>
115 #include <machine/stdarg.h>
119 #include <security/mac/mac_framework.h>
121 #define STFNAME "stf"
124 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
127 * XXX: Return a pointer with 16-bit aligned. Don't cast it to
128 * struct in_addr *; use bcopy() instead.
130 #define GET_V4(x) ((caddr_t)(&(x)->s6_addr16[1]))
133 struct ifnet *sc_ifp;
135 struct route __sc_ro4;
136 struct route_in6 __sc_ro6; /* just for safety */
138 #define sc_ro __sc_ro46.__sc_ro4
139 const struct encaptab *encap_cookie;
141 #define STF2IFP(sc) ((sc)->sc_ifp)
144 * XXXRW: Note that mutable fields in the softc are not currently locked:
145 * in particular, sc_ro needs to be protected from concurrent entrance
148 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
149 static const int ip_stf_ttl = 40;
151 extern struct domain inetdomain;
152 struct protosw in_stf_protosw = {
154 .pr_domain = &inetdomain,
155 .pr_protocol = IPPROTO_IPV6,
156 .pr_flags = PR_ATOMIC|PR_ADDR,
157 .pr_input = in_stf_input,
158 .pr_output = (pr_output_t *)rip_output,
159 .pr_ctloutput = rip_ctloutput,
160 .pr_usrreqs = &rip_usrreqs
163 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
165 static int stfmodevent(module_t, int, void *);
166 static int stf_encapcheck(const struct mbuf *, int, int, void *);
167 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
168 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
170 static int isrfc1918addr(struct in_addr *);
171 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
173 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
175 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
176 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
178 static int stf_clone_match(struct if_clone *, const char *);
179 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
180 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
181 struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0,
182 NULL, stf_clone_match, stf_clone_create, stf_clone_destroy);
185 stf_clone_match(struct if_clone *ifc, const char *name)
189 for(i = 0; stfnames[i] != NULL; i++) {
190 if (strcmp(stfnames[i], name) == 0)
198 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
201 struct stf_softc *sc;
205 * We can only have one unit, but since unit allocation is
206 * already locked, we use it to keep from allocating extra
210 err = ifc_alloc_unit(ifc, &unit);
214 sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
215 ifp = STF2IFP(sc) = if_alloc(IFT_STF);
218 ifc_free_unit(ifc, unit);
224 * Set the name manually rather then using if_initname because
225 * we don't conform to the default naming convention for interfaces.
227 strlcpy(ifp->if_xname, name, IFNAMSIZ);
228 ifp->if_dname = ifc->ifc_name;
229 ifp->if_dunit = IF_DUNIT_NONE;
231 sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
232 stf_encapcheck, &in_stf_protosw, sc);
233 if (sc->encap_cookie == NULL) {
234 if_printf(ifp, "attach failed\n");
236 ifc_free_unit(ifc, unit);
240 ifp->if_mtu = IPV6_MMTU;
241 ifp->if_ioctl = stf_ioctl;
242 ifp->if_output = stf_output;
243 ifp->if_snd.ifq_maxlen = IFQ_MAXLEN;
245 bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
250 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
252 struct stf_softc *sc = ifp->if_softc;
255 err = encap_detach(sc->encap_cookie);
256 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
262 ifc_free_unit(ifc, STFUNIT);
268 stfmodevent(mod, type, data)
276 if_clone_attach(&stf_cloner);
279 if_clone_detach(&stf_cloner);
288 static moduledata_t stf_mod = {
294 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
297 stf_encapcheck(m, off, proto, arg)
298 const struct mbuf *m;
304 struct in6_ifaddr *ia6;
305 struct stf_softc *sc;
306 struct in_addr a, b, mask;
308 sc = (struct stf_softc *)arg;
312 if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
315 /* IFF_LINK0 means "no decapsulation" */
316 if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
319 if (proto != IPPROTO_IPV6)
322 /* LINTED const cast */
323 m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
328 ia6 = stf_getsrcifa6(STF2IFP(sc));
333 * check if IPv4 dst matches the IPv4 address derived from the
334 * local 6to4 address.
335 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
337 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
338 sizeof(ip.ip_dst)) != 0)
342 * check if IPv4 src matches the IPv4 address derived from the
343 * local 6to4 address masked by prefixmask.
344 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
345 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
347 bzero(&a, sizeof(a));
348 bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
349 bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
350 a.s_addr &= mask.s_addr;
352 b.s_addr &= mask.s_addr;
353 if (a.s_addr != b.s_addr)
356 /* stf interface makes single side match only */
360 static struct in6_ifaddr *
365 struct in_ifaddr *ia4;
366 struct sockaddr_in6 *sin6;
369 TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list) {
370 if (ia->ifa_addr->sa_family != AF_INET6)
372 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
373 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
376 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
377 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
378 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
383 return (struct in6_ifaddr *)ia;
390 stf_output(ifp, m, dst, rt)
393 struct sockaddr *dst;
396 struct stf_softc *sc;
397 struct sockaddr_in6 *dst6;
400 struct sockaddr_in *dst4;
404 struct in6_ifaddr *ia6;
409 error = mac_check_ifnet_transmit(ifp, m);
417 dst6 = (struct sockaddr_in6 *)dst;
420 if ((ifp->if_flags & IFF_UP) == 0) {
427 * If we don't have an ip4 address that match my inner ip6 address,
428 * we shouldn't generate output. Without this check, we'll end up
429 * using wrong IPv4 source.
431 ia6 = stf_getsrcifa6(ifp);
438 if (m->m_len < sizeof(*ip6)) {
439 m = m_pullup(m, sizeof(*ip6));
445 ip6 = mtod(m, struct ip6_hdr *);
446 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
449 * BPF writes need to be handled specially.
450 * This is a null operation, nothing here checks dst->sa_family.
452 if (dst->sa_family == AF_UNSPEC) {
453 bcopy(dst->sa_data, &af, sizeof(af));
458 * Pickup the right outer dst addr from the list of candidates.
459 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
462 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
463 ptr = GET_V4(&ip6->ip6_dst);
464 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
465 ptr = GET_V4(&dst6->sin6_addr);
471 bcopy(ptr, &in4, sizeof(in4));
473 if (bpf_peers_present(ifp->if_bpf)) {
475 * We need to prepend the address family as
476 * a four byte field. Cons up a dummy header
477 * to pacify bpf. This is safe because bpf
478 * will only read from the mbuf (i.e., it won't
479 * try to free it or keep a pointer a to it).
482 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
485 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
486 if (m && m->m_len < sizeof(struct ip))
487 m = m_pullup(m, sizeof(struct ip));
492 ip = mtod(m, struct ip *);
494 bzero(ip, sizeof(*ip));
496 bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
497 &ip->ip_src, sizeof(ip->ip_src));
498 bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
499 ip->ip_p = IPPROTO_IPV6;
500 ip->ip_ttl = ip_stf_ttl;
501 ip->ip_len = m->m_pkthdr.len; /*host order*/
502 if (ifp->if_flags & IFF_LINK1)
503 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
505 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
508 * XXXRW: Locking of sc_ro required.
510 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
511 if (dst4->sin_family != AF_INET ||
512 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
513 /* cache route doesn't match */
514 dst4->sin_family = AF_INET;
515 dst4->sin_len = sizeof(struct sockaddr_in);
516 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
517 if (sc->sc_ro.ro_rt) {
518 RTFREE(sc->sc_ro.ro_rt);
519 sc->sc_ro.ro_rt = NULL;
523 if (sc->sc_ro.ro_rt == NULL) {
525 if (sc->sc_ro.ro_rt == NULL) {
533 return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
541 * returns 1 if private address range:
542 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
544 if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
545 (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
546 (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
553 stf_checkaddr4(sc, in, inifp)
554 struct stf_softc *sc;
556 struct ifnet *inifp; /* incoming interface */
558 struct in_ifaddr *ia4;
561 * reject packets with the following address:
562 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
564 if (IN_MULTICAST(ntohl(in->s_addr)))
566 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
567 case 0: case 127: case 255:
572 * reject packets with private address range.
573 * (requirement from RFC3056 section 2 1st paragraph)
575 if (isrfc1918addr(in))
579 * reject packets with broadcast
581 for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
583 ia4 = TAILQ_NEXT(ia4, ia_link))
585 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
587 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
592 * perform ingress filter
594 if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
595 struct sockaddr_in sin;
598 bzero(&sin, sizeof(sin));
599 sin.sin_family = AF_INET;
600 sin.sin_len = sizeof(struct sockaddr_in);
602 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
603 if (!rt || rt->rt_ifp != inifp) {
605 log(LOG_WARNING, "%s: packet from 0x%x dropped "
606 "due to ingress filter\n", if_name(STF2IFP(sc)),
607 (u_int32_t)ntohl(sin.sin_addr.s_addr));
620 stf_checkaddr6(sc, in6, inifp)
621 struct stf_softc *sc;
622 struct in6_addr *in6;
623 struct ifnet *inifp; /* incoming interface */
626 * check 6to4 addresses
628 if (IN6_IS_ADDR_6TO4(in6)) {
630 bcopy(GET_V4(in6), &in4, sizeof(in4));
631 return stf_checkaddr4(sc, &in4, inifp);
635 * reject anything that look suspicious. the test is implemented
636 * in ip6_input too, but we check here as well to
637 * (1) reject bad packets earlier, and
638 * (2) to be safe against future ip6_input change.
640 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
652 struct stf_softc *sc;
658 proto = mtod(m, struct ip *)->ip_p;
660 if (proto != IPPROTO_IPV6) {
665 ip = mtod(m, struct ip *);
667 sc = (struct stf_softc *)encap_getarg(m);
669 if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
677 mac_create_mbuf_from_ifnet(ifp, m);
681 * perform sanity check against outer src/dst.
682 * for source, perform ingress filter as well.
684 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
685 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
693 if (m->m_len < sizeof(*ip6)) {
694 m = m_pullup(m, sizeof(*ip6));
698 ip6 = mtod(m, struct ip6_hdr *);
701 * perform sanity check against inner src/dst.
702 * for source, perform ingress filter as well.
704 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
705 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
710 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
711 if ((ifp->if_flags & IFF_LINK1) != 0)
712 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
714 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
715 ip6->ip6_flow &= ~htonl(0xff << 20);
716 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
718 m->m_pkthdr.rcvif = ifp;
720 if (bpf_peers_present(ifp->if_bpf)) {
722 * We need to prepend the address family as
723 * a four byte field. Cons up a dummy header
724 * to pacify bpf. This is safe because bpf
725 * will only read from the mbuf (i.e., it won't
726 * try to free it or keep a pointer a to it).
728 u_int32_t af = AF_INET6;
729 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
733 * Put the packet to the network layer input queue according to the
734 * specified address family.
735 * See net/if_gif.c for possible issues with packet processing
736 * reorder due to extra queueing.
739 ifp->if_ibytes += m->m_pkthdr.len;
740 netisr_dispatch(NETISR_IPV6, m);
745 stf_rtrequest(cmd, rt, info)
748 struct rt_addrinfo *info;
751 rt->rt_rmx.rmx_mtu = IPV6_MMTU;
755 stf_ioctl(ifp, cmd, data)
762 struct sockaddr_in6 *sin6;
769 ifa = (struct ifaddr *)data;
770 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
771 error = EAFNOSUPPORT;
774 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
775 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
779 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
780 if (isrfc1918addr(&addr)) {
785 ifa->ifa_rtrequest = stf_rtrequest;
786 ifp->if_flags |= IFF_UP;
791 ifr = (struct ifreq *)data;
792 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
795 error = EAFNOSUPPORT;