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>
91 #include <sys/queue.h>
92 #include <machine/cpu.h>
94 #include <sys/malloc.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>
103 #include <netinet/in.h>
104 #include <netinet/in_systm.h>
105 #include <netinet/ip.h>
106 #include <netinet/ip_var.h>
107 #include <netinet/in_var.h>
109 #include <netinet/ip6.h>
110 #include <netinet6/ip6_var.h>
111 #include <netinet6/in6_var.h>
112 #include <netinet/ip_ecn.h>
114 #include <netinet/ip_encap.h>
116 #include <machine/stdarg.h>
120 #include <security/mac/mac_framework.h>
122 #define STFNAME "stf"
125 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
128 * XXX: Return a pointer with 16-bit aligned. Don't cast it to
129 * struct in_addr *; use bcopy() instead.
131 #define GET_V4(x) ((caddr_t)(&(x)->s6_addr16[1]))
134 struct ifnet *sc_ifp;
136 struct route __sc_ro4;
137 struct route_in6 __sc_ro6; /* just for safety */
139 #define sc_ro __sc_ro46.__sc_ro4
141 const struct encaptab *encap_cookie;
143 #define STF2IFP(sc) ((sc)->sc_ifp)
146 * XXXRW: Note that mutable fields in the softc are not currently locked:
147 * in particular, sc_ro needs to be protected from concurrent entrance
150 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
151 static const int ip_stf_ttl = 40;
153 extern struct domain inetdomain;
154 struct protosw in_stf_protosw = {
156 .pr_domain = &inetdomain,
157 .pr_protocol = IPPROTO_IPV6,
158 .pr_flags = PR_ATOMIC|PR_ADDR,
159 .pr_input = in_stf_input,
160 .pr_output = (pr_output_t *)rip_output,
161 .pr_ctloutput = rip_ctloutput,
162 .pr_usrreqs = &rip_usrreqs
165 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
167 static int stfmodevent(module_t, int, void *);
168 static int stf_encapcheck(const struct mbuf *, int, int, void *);
169 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
170 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
172 static int isrfc1918addr(struct in_addr *);
173 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
175 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
177 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
178 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
180 static int stf_clone_match(struct if_clone *, const char *);
181 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
182 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
183 struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0,
184 NULL, stf_clone_match, stf_clone_create, stf_clone_destroy);
187 stf_clone_match(struct if_clone *ifc, const char *name)
191 for(i = 0; stfnames[i] != NULL; i++) {
192 if (strcmp(stfnames[i], name) == 0)
200 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
203 struct stf_softc *sc;
207 * We can only have one unit, but since unit allocation is
208 * already locked, we use it to keep from allocating extra
212 err = ifc_alloc_unit(ifc, &unit);
216 sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
217 ifp = STF2IFP(sc) = if_alloc(IFT_STF);
220 ifc_free_unit(ifc, unit);
224 sc->sc_fibnum = curthread->td_proc->p_fibnum;
227 * Set the name manually rather then using if_initname because
228 * we don't conform to the default naming convention for interfaces.
230 strlcpy(ifp->if_xname, name, IFNAMSIZ);
231 ifp->if_dname = ifc->ifc_name;
232 ifp->if_dunit = IF_DUNIT_NONE;
234 sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
235 stf_encapcheck, &in_stf_protosw, sc);
236 if (sc->encap_cookie == NULL) {
237 if_printf(ifp, "attach failed\n");
239 ifc_free_unit(ifc, unit);
243 ifp->if_mtu = IPV6_MMTU;
244 ifp->if_ioctl = stf_ioctl;
245 ifp->if_output = stf_output;
246 ifp->if_snd.ifq_maxlen = IFQ_MAXLEN;
248 bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
253 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
255 struct stf_softc *sc = ifp->if_softc;
258 err = encap_detach(sc->encap_cookie);
259 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
265 ifc_free_unit(ifc, STFUNIT);
271 stfmodevent(mod, type, data)
279 if_clone_attach(&stf_cloner);
282 if_clone_detach(&stf_cloner);
291 static moduledata_t stf_mod = {
297 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
300 stf_encapcheck(m, off, proto, arg)
301 const struct mbuf *m;
307 struct in6_ifaddr *ia6;
308 struct stf_softc *sc;
309 struct in_addr a, b, mask;
311 sc = (struct stf_softc *)arg;
315 if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
318 /* IFF_LINK0 means "no decapsulation" */
319 if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
322 if (proto != IPPROTO_IPV6)
325 /* LINTED const cast */
326 m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
331 ia6 = stf_getsrcifa6(STF2IFP(sc));
336 * check if IPv4 dst matches the IPv4 address derived from the
337 * local 6to4 address.
338 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
340 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
341 sizeof(ip.ip_dst)) != 0)
345 * check if IPv4 src matches the IPv4 address derived from the
346 * local 6to4 address masked by prefixmask.
347 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
348 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
350 bzero(&a, sizeof(a));
351 bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
352 bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
353 a.s_addr &= mask.s_addr;
355 b.s_addr &= mask.s_addr;
356 if (a.s_addr != b.s_addr)
359 /* stf interface makes single side match only */
363 static struct in6_ifaddr *
368 struct in_ifaddr *ia4;
369 struct sockaddr_in6 *sin6;
372 TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list) {
373 if (ia->ifa_addr->sa_family != AF_INET6)
375 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
376 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
379 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
380 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
381 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
386 return (struct in6_ifaddr *)ia;
393 stf_output(ifp, m, dst, rt)
396 struct sockaddr *dst;
399 struct stf_softc *sc;
400 struct sockaddr_in6 *dst6;
403 struct sockaddr_in *dst4;
407 struct in6_ifaddr *ia6;
412 error = mac_ifnet_check_transmit(ifp, m);
420 dst6 = (struct sockaddr_in6 *)dst;
423 if ((ifp->if_flags & IFF_UP) == 0) {
430 * If we don't have an ip4 address that match my inner ip6 address,
431 * we shouldn't generate output. Without this check, we'll end up
432 * using wrong IPv4 source.
434 ia6 = stf_getsrcifa6(ifp);
441 if (m->m_len < sizeof(*ip6)) {
442 m = m_pullup(m, sizeof(*ip6));
448 ip6 = mtod(m, struct ip6_hdr *);
449 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
452 * BPF writes need to be handled specially.
453 * This is a null operation, nothing here checks dst->sa_family.
455 if (dst->sa_family == AF_UNSPEC) {
456 bcopy(dst->sa_data, &af, sizeof(af));
461 * Pickup the right outer dst addr from the list of candidates.
462 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
465 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
466 ptr = GET_V4(&ip6->ip6_dst);
467 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
468 ptr = GET_V4(&dst6->sin6_addr);
474 bcopy(ptr, &in4, sizeof(in4));
476 if (bpf_peers_present(ifp->if_bpf)) {
478 * We need to prepend the address family as
479 * a four byte field. Cons up a dummy header
480 * to pacify bpf. This is safe because bpf
481 * will only read from the mbuf (i.e., it won't
482 * try to free it or keep a pointer a to it).
485 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
488 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
489 if (m && m->m_len < sizeof(struct ip))
490 m = m_pullup(m, sizeof(struct ip));
495 ip = mtod(m, struct ip *);
497 bzero(ip, sizeof(*ip));
499 bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
500 &ip->ip_src, sizeof(ip->ip_src));
501 bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
502 ip->ip_p = IPPROTO_IPV6;
503 ip->ip_ttl = ip_stf_ttl;
504 ip->ip_len = m->m_pkthdr.len; /*host order*/
505 if (ifp->if_flags & IFF_LINK1)
506 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
508 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
511 * XXXRW: Locking of sc_ro required.
513 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
514 if (dst4->sin_family != AF_INET ||
515 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
516 /* cache route doesn't match */
517 dst4->sin_family = AF_INET;
518 dst4->sin_len = sizeof(struct sockaddr_in);
519 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
520 if (sc->sc_ro.ro_rt) {
521 RTFREE(sc->sc_ro.ro_rt);
522 sc->sc_ro.ro_rt = NULL;
526 if (sc->sc_ro.ro_rt == NULL) {
527 rtalloc_fib(&sc->sc_ro, sc->sc_fibnum);
528 if (sc->sc_ro.ro_rt == NULL) {
535 M_SETFIB(m, sc->sc_fibnum);
537 return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
545 * returns 1 if private address range:
546 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
548 if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
549 (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
550 (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
557 stf_checkaddr4(sc, in, inifp)
558 struct stf_softc *sc;
560 struct ifnet *inifp; /* incoming interface */
562 struct in_ifaddr *ia4;
565 * reject packets with the following address:
566 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
568 if (IN_MULTICAST(ntohl(in->s_addr)))
570 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
571 case 0: case 127: case 255:
576 * reject packets with private address range.
577 * (requirement from RFC3056 section 2 1st paragraph)
579 if (isrfc1918addr(in))
583 * reject packets with broadcast
585 for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
587 ia4 = TAILQ_NEXT(ia4, ia_link))
589 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
591 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
596 * perform ingress filter
598 if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
599 struct sockaddr_in sin;
602 bzero(&sin, sizeof(sin));
603 sin.sin_family = AF_INET;
604 sin.sin_len = sizeof(struct sockaddr_in);
606 rt = rtalloc1_fib((struct sockaddr *)&sin, 0,
608 if (!rt || rt->rt_ifp != inifp) {
610 log(LOG_WARNING, "%s: packet from 0x%x dropped "
611 "due to ingress filter\n", if_name(STF2IFP(sc)),
612 (u_int32_t)ntohl(sin.sin_addr.s_addr));
625 stf_checkaddr6(sc, in6, inifp)
626 struct stf_softc *sc;
627 struct in6_addr *in6;
628 struct ifnet *inifp; /* incoming interface */
631 * check 6to4 addresses
633 if (IN6_IS_ADDR_6TO4(in6)) {
635 bcopy(GET_V4(in6), &in4, sizeof(in4));
636 return stf_checkaddr4(sc, &in4, inifp);
640 * reject anything that look suspicious. the test is implemented
641 * in ip6_input too, but we check here as well to
642 * (1) reject bad packets earlier, and
643 * (2) to be safe against future ip6_input change.
645 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
657 struct stf_softc *sc;
663 proto = mtod(m, struct ip *)->ip_p;
665 if (proto != IPPROTO_IPV6) {
670 ip = mtod(m, struct ip *);
672 sc = (struct stf_softc *)encap_getarg(m);
674 if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
682 mac_ifnet_create_mbuf(ifp, m);
686 * perform sanity check against outer src/dst.
687 * for source, perform ingress filter as well.
689 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
690 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
698 if (m->m_len < sizeof(*ip6)) {
699 m = m_pullup(m, sizeof(*ip6));
703 ip6 = mtod(m, struct ip6_hdr *);
706 * perform sanity check against inner src/dst.
707 * for source, perform ingress filter as well.
709 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
710 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
715 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
716 if ((ifp->if_flags & IFF_LINK1) != 0)
717 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
719 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
720 ip6->ip6_flow &= ~htonl(0xff << 20);
721 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
723 m->m_pkthdr.rcvif = ifp;
725 if (bpf_peers_present(ifp->if_bpf)) {
727 * We need to prepend the address family as
728 * a four byte field. Cons up a dummy header
729 * to pacify bpf. This is safe because bpf
730 * will only read from the mbuf (i.e., it won't
731 * try to free it or keep a pointer a to it).
733 u_int32_t af = AF_INET6;
734 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
738 * Put the packet to the network layer input queue according to the
739 * specified address family.
740 * See net/if_gif.c for possible issues with packet processing
741 * reorder due to extra queueing.
744 ifp->if_ibytes += m->m_pkthdr.len;
745 netisr_dispatch(NETISR_IPV6, m);
750 stf_rtrequest(cmd, rt, info)
753 struct rt_addrinfo *info;
756 rt->rt_rmx.rmx_mtu = IPV6_MMTU;
760 stf_ioctl(ifp, cmd, data)
767 struct sockaddr_in6 *sin6;
774 ifa = (struct ifaddr *)data;
775 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
776 error = EAFNOSUPPORT;
779 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
780 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
784 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
785 if (isrfc1918addr(&addr)) {
790 ifa->ifa_rtrequest = stf_rtrequest;
791 ifp->if_flags |= IFF_UP;
796 ifr = (struct ifreq *)data;
797 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
800 error = EAFNOSUPPORT;