2 /* $KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $ */
5 * SPDX-License-Identifier: BSD-3-Clause
7 * Copyright (C) 2000 WIDE Project.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the project nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * 6to4 interface, based on RFC3056.
38 * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
39 * There is no address mapping defined from IPv6 multicast address to IPv4
40 * address. Therefore, we do not have IFF_MULTICAST on the interface.
42 * Due to the lack of address mapping for link-local addresses, we cannot
43 * throw packets toward link-local addresses (fe80::x). Also, we cannot throw
44 * packets to link-local multicast addresses (ff02::x).
46 * Here are interesting symptoms due to the lack of link-local address:
48 * Unicast routing exchange:
49 * - RIPng: Impossible. Uses link-local multicast packet toward ff02::9,
50 * and link-local addresses as nexthop.
51 * - OSPFv6: Impossible. OSPFv6 assumes that there's link-local address
52 * assigned to the link, and makes use of them. Also, HELLO packets use
53 * link-local multicast addresses (ff02::5 and ff02::6).
54 * - BGP4+: Maybe. You can only use global address as nexthop, and global
55 * address as TCP endpoint address.
57 * Multicast routing protocols:
58 * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
59 * Adjacent PIM routers must be configured manually (is it really spec-wise
60 * correct thing to do?).
63 * - Redirects cannot be used due to the lack of link-local address.
65 * stf interface does not have, and will not need, a link-local address.
66 * It seems to have no real benefit and does not help the above symptoms much.
67 * Even if we assign link-locals to interface, we cannot really
68 * use link-local unicast/multicast on top of 6to4 cloud (since there's no
69 * encapsulation defined for link-local address), and the above analysis does
70 * not change. RFC3056 does not mandate the assignment of link-local address
73 * 6to4 interface has security issues. Refer to
74 * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
75 * for details. The code tries to filter out some of malicious packets.
76 * Note that there is no way to be 100% secure.
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/socket.h>
82 #include <sys/sockio.h>
84 #include <sys/errno.h>
85 #include <sys/kernel.h>
87 #include <sys/module.h>
89 #include <sys/queue.h>
90 #include <sys/rmlock.h>
91 #include <sys/sysctl.h>
92 #include <machine/cpu.h>
94 #include <sys/malloc.h>
97 #include <net/if_var.h>
98 #include <net/if_clone.h>
99 #include <net/route.h>
100 #include <net/netisr.h>
101 #include <net/if_types.h>
102 #include <net/vnet.h>
104 #include <netinet/in.h>
105 #include <netinet/in_fib.h>
106 #include <netinet/in_systm.h>
107 #include <netinet/ip.h>
108 #include <netinet/ip_var.h>
109 #include <netinet/in_var.h>
111 #include <netinet/ip6.h>
112 #include <netinet6/ip6_var.h>
113 #include <netinet6/in6_var.h>
114 #include <netinet/ip_ecn.h>
116 #include <netinet/ip_encap.h>
118 #include <machine/stdarg.h>
122 #include <security/mac/mac_framework.h>
124 SYSCTL_DECL(_net_link);
125 static SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface");
127 static int stf_permit_rfc1918 = 0;
128 SYSCTL_INT(_net_link_stf, OID_AUTO, permit_rfc1918, CTLFLAG_RWTUN,
129 &stf_permit_rfc1918, 0, "Permit the use of private IPv4 addresses");
133 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
136 * XXX: Return a pointer with 16-bit aligned. Don't cast it to
137 * struct in_addr *; use bcopy() instead.
139 #define GET_V4(x) (&(x)->s6_addr16[1])
142 struct ifnet *sc_ifp;
144 const struct encaptab *encap_cookie;
146 #define STF2IFP(sc) ((sc)->sc_ifp)
148 static const char stfname[] = "stf";
150 static MALLOC_DEFINE(M_STF, stfname, "6to4 Tunnel Interface");
151 static const int ip_stf_ttl = 40;
153 static int in_stf_input(struct mbuf *, int, int, void *);
154 static char *stfnames[] = {"stf0", "stf", "6to4", NULL};
156 static int stfmodevent(module_t, int, void *);
157 static int stf_encapcheck(const struct mbuf *, int, int, void *);
158 static int stf_getsrcifa6(struct ifnet *, struct in6_addr *, struct in6_addr *);
159 static int stf_output(struct ifnet *, struct mbuf *, const struct sockaddr *,
161 static int isrfc1918addr(struct in_addr *);
162 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
164 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
166 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
168 static int stf_clone_match(struct if_clone *, const char *);
169 static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t);
170 static int stf_clone_destroy(struct if_clone *, struct ifnet *);
171 static struct if_clone *stf_cloner;
173 static const struct encap_config ipv4_encap_cfg = {
174 .proto = IPPROTO_IPV6,
175 .min_length = sizeof(struct ip),
176 .exact_match = (sizeof(in_addr_t) << 3) + 8,
177 .check = stf_encapcheck,
178 .input = in_stf_input
182 stf_clone_match(struct if_clone *ifc, const char *name)
186 for(i = 0; stfnames[i] != NULL; i++) {
187 if (strcmp(stfnames[i], name) == 0)
195 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
198 int err, unit, wildcard;
199 struct stf_softc *sc;
202 err = ifc_name2unit(name, &unit);
205 wildcard = (unit < 0);
208 * We can only have one unit, but since unit allocation is
209 * already locked, we use it to keep from allocating extra
213 err = ifc_alloc_unit(ifc, &unit);
217 sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
218 ifp = STF2IFP(sc) = if_alloc(IFT_STF);
221 ifc_free_unit(ifc, unit);
225 sc->sc_fibnum = curthread->td_proc->p_fibnum;
228 * Set the name manually rather then using if_initname because
229 * we don't conform to the default naming convention for interfaces.
230 * In the wildcard case, we need to update the name.
233 for (dp = name; *dp != '\0'; dp++);
234 if (snprintf(dp, len - (dp-name), "%d", unit) >
235 len - (dp-name) - 1) {
237 * This can only be a programmer error and
238 * there's no straightforward way to recover if
241 panic("if_clone_create(): interface name too long");
244 strlcpy(ifp->if_xname, name, IFNAMSIZ);
245 ifp->if_dname = stfname;
246 ifp->if_dunit = IF_DUNIT_NONE;
248 sc->encap_cookie = ip_encap_attach(&ipv4_encap_cfg, sc, M_WAITOK);
249 if (sc->encap_cookie == NULL) {
250 if_printf(ifp, "attach failed\n");
252 ifc_free_unit(ifc, unit);
256 ifp->if_mtu = IPV6_MMTU;
257 ifp->if_ioctl = stf_ioctl;
258 ifp->if_output = stf_output;
259 ifp->if_snd.ifq_maxlen = ifqmaxlen;
261 bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
266 stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp)
268 struct stf_softc *sc = ifp->if_softc;
271 err = ip_encap_detach(sc->encap_cookie);
272 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
278 ifc_free_unit(ifc, STFUNIT);
284 stfmodevent(module_t mod, int type, void *data)
289 stf_cloner = if_clone_advanced(stfname, 0, stf_clone_match,
290 stf_clone_create, stf_clone_destroy);
293 if_clone_detach(stf_cloner);
302 static moduledata_t stf_mod = {
308 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
311 stf_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
314 struct stf_softc *sc;
315 struct in_addr a, b, mask;
316 struct in6_addr addr6, mask6;
318 sc = (struct stf_softc *)arg;
322 if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
325 /* IFF_LINK0 means "no decapsulation" */
326 if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
329 if (proto != IPPROTO_IPV6)
332 m_copydata(m, 0, sizeof(ip), (caddr_t)&ip);
337 if (stf_getsrcifa6(STF2IFP(sc), &addr6, &mask6) != 0)
341 * check if IPv4 dst matches the IPv4 address derived from the
342 * local 6to4 address.
343 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
345 if (bcmp(GET_V4(&addr6), &ip.ip_dst, sizeof(ip.ip_dst)) != 0)
349 * check if IPv4 src matches the IPv4 address derived from the
350 * local 6to4 address masked by prefixmask.
351 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
352 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
354 bzero(&a, sizeof(a));
355 bcopy(GET_V4(&addr6), &a, sizeof(a));
356 bcopy(GET_V4(&mask6), &mask, sizeof(mask));
357 a.s_addr &= mask.s_addr;
359 b.s_addr &= mask.s_addr;
360 if (a.s_addr != b.s_addr)
363 /* stf interface makes single side match only */
368 stf_getsrcifa6(struct ifnet *ifp, struct in6_addr *addr, struct in6_addr *mask)
370 struct rm_priotracker in_ifa_tracker;
372 struct in_ifaddr *ia4;
373 struct in6_ifaddr *ia6;
374 struct sockaddr_in6 *sin6;
379 CK_STAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
380 if (ia->ifa_addr->sa_family != AF_INET6)
382 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
383 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
386 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
387 IN_IFADDR_RLOCK(&in_ifa_tracker);
388 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
389 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
391 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
395 ia6 = (struct in6_ifaddr *)ia;
397 *addr = sin6->sin6_addr;
398 *mask = ia6->ia_prefixmask.sin6_addr;
406 stf_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
409 struct stf_softc *sc;
410 const struct sockaddr_in6 *dst6;
416 struct in6_addr addr6, mask6;
420 error = mac_ifnet_check_transmit(ifp, m);
428 dst6 = (const struct sockaddr_in6 *)dst;
431 if ((ifp->if_flags & IFF_UP) == 0) {
433 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
438 * If we don't have an ip4 address that match my inner ip6 address,
439 * we shouldn't generate output. Without this check, we'll end up
440 * using wrong IPv4 source.
442 if (stf_getsrcifa6(ifp, &addr6, &mask6) != 0) {
444 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
448 if (m->m_len < sizeof(*ip6)) {
449 m = m_pullup(m, sizeof(*ip6));
451 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
455 ip6 = mtod(m, struct ip6_hdr *);
456 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
459 * Pickup the right outer dst addr from the list of candidates.
460 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
463 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
464 ptr = GET_V4(&ip6->ip6_dst);
465 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
466 ptr = GET_V4(&dst6->sin6_addr);
469 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
472 bcopy(ptr, &in4, sizeof(in4));
474 if (bpf_peers_present(ifp->if_bpf)) {
476 * We need to prepend the address family as
477 * a four byte field. Cons up a dummy header
478 * to pacify bpf. This is safe because bpf
479 * will only read from the mbuf (i.e., it won't
480 * try to free it or keep a pointer a to it).
483 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
486 M_PREPEND(m, sizeof(struct ip), M_NOWAIT);
488 if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
491 ip = mtod(m, struct ip *);
493 bzero(ip, sizeof(*ip));
495 bcopy(GET_V4(&addr6), &ip->ip_src, sizeof(ip->ip_src));
496 bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
497 ip->ip_p = IPPROTO_IPV6;
498 ip->ip_ttl = ip_stf_ttl;
499 ip->ip_len = htons(m->m_pkthdr.len);
500 if (ifp->if_flags & IFF_LINK1)
501 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
503 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
505 M_SETFIB(m, sc->sc_fibnum);
506 if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
507 error = ip_output(m, NULL, NULL, 0, NULL, NULL);
513 isrfc1918addr(struct in_addr *in)
516 * returns 1 if private address range:
517 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
519 if (stf_permit_rfc1918 == 0 && (
520 (ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
521 (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
522 (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168))
529 stf_checkaddr4(struct stf_softc *sc, struct in_addr *in, struct ifnet *inifp)
531 struct rm_priotracker in_ifa_tracker;
532 struct in_ifaddr *ia4;
535 * reject packets with the following address:
536 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
538 if (IN_MULTICAST(ntohl(in->s_addr)))
540 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
541 case 0: case 127: case 255:
546 * reject packets with private address range.
547 * (requirement from RFC3056 section 2 1st paragraph)
549 if (isrfc1918addr(in))
553 * reject packets with broadcast
555 IN_IFADDR_RLOCK(&in_ifa_tracker);
556 CK_STAILQ_FOREACH(ia4, &V_in_ifaddrhead, ia_link) {
557 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
559 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
560 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
564 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
567 * perform ingress filter
569 if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
570 struct nhop4_basic nh4;
572 if (fib4_lookup_nh_basic(sc->sc_fibnum, *in, 0, 0, &nh4) != 0)
575 if (nh4.nh_ifp != inifp)
583 stf_checkaddr6(struct stf_softc *sc, struct in6_addr *in6, struct ifnet *inifp)
586 * check 6to4 addresses
588 if (IN6_IS_ADDR_6TO4(in6)) {
590 bcopy(GET_V4(in6), &in4, sizeof(in4));
591 return stf_checkaddr4(sc, &in4, inifp);
595 * reject anything that look suspicious. the test is implemented
596 * in ip6_input too, but we check here as well to
597 * (1) reject bad packets earlier, and
598 * (2) to be safe against future ip6_input change.
600 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
607 in_stf_input(struct mbuf *m, int off, int proto, void *arg)
609 struct stf_softc *sc = arg;
617 if (proto != IPPROTO_IPV6) {
619 return (IPPROTO_DONE);
622 ip = mtod(m, struct ip *);
623 if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
625 return (IPPROTO_DONE);
631 mac_ifnet_create_mbuf(ifp, m);
635 * perform sanity check against outer src/dst.
636 * for source, perform ingress filter as well.
638 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
639 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
641 return (IPPROTO_DONE);
647 if (m->m_len < sizeof(*ip6)) {
648 m = m_pullup(m, sizeof(*ip6));
650 return (IPPROTO_DONE);
652 ip6 = mtod(m, struct ip6_hdr *);
655 * perform sanity check against inner src/dst.
656 * for source, perform ingress filter as well.
658 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
659 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
661 return (IPPROTO_DONE);
664 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
665 if ((ifp->if_flags & IFF_LINK1) != 0)
666 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
668 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
669 ip6->ip6_flow &= ~htonl(0xff << 20);
670 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
672 m->m_pkthdr.rcvif = ifp;
674 if (bpf_peers_present(ifp->if_bpf)) {
676 * We need to prepend the address family as
677 * a four byte field. Cons up a dummy header
678 * to pacify bpf. This is safe because bpf
679 * will only read from the mbuf (i.e., it won't
680 * try to free it or keep a pointer a to it).
682 u_int32_t af = AF_INET6;
683 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
687 * Put the packet to the network layer input queue according to the
688 * specified address family.
689 * See net/if_gif.c for possible issues with packet processing
690 * reorder due to extra queueing.
692 if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
693 if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
694 M_SETFIB(m, ifp->if_fib);
695 netisr_dispatch(NETISR_IPV6, m);
696 return (IPPROTO_DONE);
700 stf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
704 struct sockaddr_in6 *sin6;
711 ifa = (struct ifaddr *)data;
712 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
713 error = EAFNOSUPPORT;
716 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
717 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
721 bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
722 if (isrfc1918addr(&addr)) {
727 ifp->if_flags |= IFF_UP;
728 ifp->if_drv_flags |= IFF_DRV_RUNNING;
733 ifr = (struct ifreq *)data;
734 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
737 error = EAFNOSUPPORT;
744 ifr = (struct ifreq *)data;
746 /* RFC 4213 3.2 ideal world MTU */
747 if (mtu < IPV6_MINMTU || mtu > IF_MAXMTU - 20)