1 /* $FreeBSD: src/sys/net/if_stf.c,v 1.1.2.11 2003/01/23 21:06:44 sam Exp $ */
2 /* $DragonFly: src/sys/net/stf/if_stf.c,v 1.2 2003/06/17 04:28:48 dillon Exp $ */
3 /* $KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $ */
6 * Copyright (C) 2000 WIDE Project.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * 6to4 interface, based on RFC3056.
37 * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
38 * There is no address mapping defined from IPv6 multicast address to IPv4
39 * address. Therefore, we do not have IFF_MULTICAST on the interface.
41 * Due to the lack of address mapping for link-local addresses, we cannot
42 * throw packets toward link-local addresses (fe80::x). Also, we cannot throw
43 * packets to link-local multicast addresses (ff02::x).
45 * Here are interesting symptoms due to the lack of link-local address:
47 * Unicast routing exchange:
48 * - RIPng: Impossible. Uses link-local multicast packet toward ff02::9,
49 * and link-local addresses as nexthop.
50 * - OSPFv6: Impossible. OSPFv6 assumes that there's link-local address
51 * assigned to the link, and makes use of them. Also, HELLO packets use
52 * link-local multicast addresses (ff02::5 and ff02::6).
53 * - BGP4+: Maybe. You can only use global address as nexthop, and global
54 * address as TCP endpoint address.
56 * Multicast routing protocols:
57 * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
58 * Adjacent PIM routers must be configured manually (is it really spec-wise
59 * correct thing to do?).
62 * - Redirects cannot be used due to the lack of link-local address.
64 * stf interface does not have, and will not need, a link-local address.
65 * It seems to have no real benefit and does not help the above symptoms much.
66 * Even if we assign link-locals to interface, we cannot really
67 * use link-local unicast/multicast on top of 6to4 cloud (since there's no
68 * encapsulation defined for link-local address), and the above analysis does
69 * not change. RFC3056 does not mandate the assignment of link-local address
72 * 6to4 interface has security issues. Refer to
73 * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
74 * for details. The code tries to filter out some of malicious packets.
75 * Note that there is no way to be 100% secure.
79 #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/protosw.h>
88 #include <sys/kernel.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/ipprotosw.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/in_var.h>
106 #include <netinet/ip6.h>
107 #include <netinet6/ip6_var.h>
108 #include <netinet6/in6_var.h>
109 #include <netinet/ip_ecn.h>
111 #include <netinet/ip_encap.h>
113 #include <machine/stdarg.h>
115 #include <net/net_osdep.h>
119 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002)
120 #define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1]))
123 struct ifnet sc_if; /* common area */
125 struct route __sc_ro4;
126 struct route_in6 __sc_ro6; /* just for safety */
128 #define sc_ro __sc_ro46.__sc_ro4
129 const struct encaptab *encap_cookie;
132 static struct stf_softc *stf;
134 static MALLOC_DEFINE(M_STF, "stf", "6to4 Tunnel Interface");
135 static int ip_stf_ttl = 40;
137 extern struct domain inetdomain;
138 struct ipprotosw in_stf_protosw =
139 { SOCK_RAW, &inetdomain, IPPROTO_IPV6, PR_ATOMIC|PR_ADDR,
140 in_stf_input, rip_output, 0, rip_ctloutput,
146 static int stfmodevent __P((module_t, int, void *));
147 static int stf_encapcheck __P((const struct mbuf *, int, int, void *));
148 static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *));
149 static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *,
151 static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *,
153 static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *,
155 static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *));
156 static int stf_ioctl __P((struct ifnet *, u_long, caddr_t));
159 stfmodevent(mod, type, data)
164 struct stf_softc *sc;
166 const struct encaptab *p;
170 stf = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK);
171 bzero(stf, sizeof(struct stf_softc));
174 bzero(sc, sizeof(*sc));
175 sc->sc_if.if_name = "stf";
176 sc->sc_if.if_unit = 0;
178 p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck,
179 &in_stf_protosw, sc);
181 printf("%s: attach failed\n", if_name(&sc->sc_if));
184 sc->encap_cookie = p;
186 sc->sc_if.if_mtu = IPV6_MMTU;
187 sc->sc_if.if_flags = 0;
188 sc->sc_if.if_ioctl = stf_ioctl;
189 sc->sc_if.if_output = stf_output;
190 sc->sc_if.if_type = IFT_STF;
192 /* turn off ingress filter */
193 sc->sc_if.if_flags |= IFF_LINK2;
195 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
196 if_attach(&sc->sc_if);
198 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
200 bpfattach(&sc->sc_if.if_bpf, &sc->sc_if, DLT_NULL, sizeof(u_int));
205 bpfdetach(&sc->sc_if);
206 if_detach(&sc->sc_if);
207 err = encap_detach(sc->encap_cookie);
208 KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
216 static moduledata_t stf_mod = {
222 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
225 stf_encapcheck(m, off, proto, arg)
226 const struct mbuf *m;
232 struct in6_ifaddr *ia6;
233 struct stf_softc *sc;
236 sc = (struct stf_softc *)arg;
240 if ((sc->sc_if.if_flags & IFF_UP) == 0)
243 /* IFF_LINK0 means "no decapsulation" */
244 if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
247 if (proto != IPPROTO_IPV6)
250 /* LINTED const cast */
251 m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip);
256 ia6 = stf_getsrcifa6(&sc->sc_if);
261 * check if IPv4 dst matches the IPv4 address derived from the
262 * local 6to4 address.
263 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
265 if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
266 sizeof(ip.ip_dst)) != 0)
270 * check if IPv4 src matches the IPv4 address derived from the
271 * local 6to4 address masked by prefixmask.
272 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
273 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
275 bzero(&a, sizeof(a));
276 a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr;
277 a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
279 b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr;
280 if (a.s_addr != b.s_addr)
283 /* stf interface makes single side match only */
287 static struct in6_ifaddr *
292 struct in_ifaddr *ia4;
293 struct sockaddr_in6 *sin6;
296 TAILQ_FOREACH(ia, &ifp->if_addrlist, ifa_list) {
297 if (ia->ifa_addr == NULL)
299 if (ia->ifa_addr->sa_family != AF_INET6)
301 sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
302 if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
305 bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
306 LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
307 if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
312 return (struct in6_ifaddr *)ia;
319 stf_output(ifp, m, dst, rt)
322 struct sockaddr *dst;
325 struct stf_softc *sc;
326 struct sockaddr_in6 *dst6;
328 struct sockaddr_in *dst4;
332 struct in6_ifaddr *ia6;
334 sc = (struct stf_softc*)ifp;
335 dst6 = (struct sockaddr_in6 *)dst;
338 if ((ifp->if_flags & IFF_UP) == 0) {
344 * If we don't have an ip4 address that match my inner ip6 address,
345 * we shouldn't generate output. Without this check, we'll end up
346 * using wrong IPv4 source.
348 ia6 = stf_getsrcifa6(ifp);
354 if (m->m_len < sizeof(*ip6)) {
355 m = m_pullup(m, sizeof(*ip6));
359 ip6 = mtod(m, struct ip6_hdr *);
360 tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
363 * Pickup the right outer dst addr from the list of candidates.
364 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
366 if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
367 in4 = GET_V4(&ip6->ip6_dst);
368 else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
369 in4 = GET_V4(&dst6->sin6_addr);
378 * We need to prepend the address family as
379 * a four byte field. Cons up a dummy header
380 * to pacify bpf. This is safe because bpf
381 * will only read from the mbuf (i.e., it won't
382 * try to free it or keep a pointer a to it).
385 u_int32_t af = AF_INET6;
389 m0.m_data = (char *)⁡
394 bpf_mtap(ifp->if_bpf, &m0);
397 #endif /*NBPFILTER > 0*/
399 M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
400 if (m && m->m_len < sizeof(struct ip))
401 m = m_pullup(m, sizeof(struct ip));
404 ip = mtod(m, struct ip *);
406 bzero(ip, sizeof(*ip));
408 bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
409 &ip->ip_src, sizeof(ip->ip_src));
410 bcopy(in4, &ip->ip_dst, sizeof(ip->ip_dst));
411 ip->ip_p = IPPROTO_IPV6;
412 ip->ip_ttl = ip_stf_ttl;
413 ip->ip_len = m->m_pkthdr.len; /*host order*/
414 if (ifp->if_flags & IFF_LINK1)
415 ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
417 ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
419 dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
420 if (dst4->sin_family != AF_INET ||
421 bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
422 /* cache route doesn't match */
423 dst4->sin_family = AF_INET;
424 dst4->sin_len = sizeof(struct sockaddr_in);
425 bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
426 if (sc->sc_ro.ro_rt) {
427 RTFREE(sc->sc_ro.ro_rt);
428 sc->sc_ro.ro_rt = NULL;
432 if (sc->sc_ro.ro_rt == NULL) {
434 if (sc->sc_ro.ro_rt == NULL) {
440 return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
444 stf_checkaddr4(sc, in, inifp)
445 struct stf_softc *sc;
447 struct ifnet *inifp; /* incoming interface */
449 struct in_ifaddr *ia4;
452 * reject packets with the following address:
453 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
455 if (IN_MULTICAST(ntohl(in->s_addr)))
457 switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
458 case 0: case 127: case 255:
463 * reject packets with broadcast
465 for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
467 ia4 = TAILQ_NEXT(ia4, ia_link))
469 if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
471 if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
476 * perform ingress filter
478 if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
479 struct sockaddr_in sin;
482 bzero(&sin, sizeof(sin));
483 sin.sin_family = AF_INET;
484 sin.sin_len = sizeof(struct sockaddr_in);
486 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
487 if (!rt || rt->rt_ifp != inifp) {
489 log(LOG_WARNING, "%s: packet from 0x%x dropped "
490 "due to ingress filter\n", if_name(&sc->sc_if),
491 (u_int32_t)ntohl(sin.sin_addr.s_addr));
504 stf_checkaddr6(sc, in6, inifp)
505 struct stf_softc *sc;
506 struct in6_addr *in6;
507 struct ifnet *inifp; /* incoming interface */
510 * check 6to4 addresses
512 if (IN6_IS_ADDR_6TO4(in6))
513 return stf_checkaddr4(sc, GET_V4(in6), inifp);
516 * reject anything that look suspicious. the test is implemented
517 * in ip6_input too, but we check here as well to
518 * (1) reject bad packets earlier, and
519 * (2) to be safe against future ip6_input change.
521 if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
529 in_stf_input(struct mbuf *m, ...)
531 in_stf_input(m, va_alist)
536 struct stf_softc *sc;
541 struct ifqueue *ifq = NULL;
546 off = va_arg(ap, int);
547 proto = va_arg(ap, int);
550 if (proto != IPPROTO_IPV6) {
555 ip = mtod(m, struct ip *);
557 sc = (struct stf_softc *)encap_getarg(m);
559 if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
567 * perform sanity check against outer src/dst.
568 * for source, perform ingress filter as well.
570 if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
571 stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
579 if (m->m_len < sizeof(*ip6)) {
580 m = m_pullup(m, sizeof(*ip6));
584 ip6 = mtod(m, struct ip6_hdr *);
587 * perform sanity check against inner src/dst.
588 * for source, perform ingress filter as well.
590 if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
591 stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
596 itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
597 if ((ifp->if_flags & IFF_LINK1) != 0)
598 ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
600 ip_ecn_egress(ECN_NOCARE, &otos, &itos);
601 ip6->ip6_flow &= ~htonl(0xff << 20);
602 ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
604 m->m_pkthdr.rcvif = ifp;
608 * We need to prepend the address family as
609 * a four byte field. Cons up a dummy header
610 * to pacify bpf. This is safe because bpf
611 * will only read from the mbuf (i.e., it won't
612 * try to free it or keep a pointer a to it).
615 u_int32_t af = AF_INET6;
619 m0.m_data = (char *)⁡
624 bpf_mtap(ifp->if_bpf, &m0);
629 * Put the packet to the network layer input queue according to the
630 * specified address family.
631 * See net/if_gif.c for possible issues with packet processing
632 * reorder due to extra queueing.
639 IF_DROP(ifq); /* update statistics */
647 ifp->if_ibytes += m->m_pkthdr.len;
653 stf_rtrequest(cmd, rt, info)
656 struct rt_addrinfo *info;
660 rt->rt_rmx.rmx_mtu = IPV6_MMTU;
664 stf_ioctl(ifp, cmd, data)
671 struct sockaddr_in6 *sin6;
677 ifa = (struct ifaddr *)data;
678 if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
679 error = EAFNOSUPPORT;
682 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
683 if (IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
684 ifa->ifa_rtrequest = stf_rtrequest;
685 ifp->if_flags |= IFF_UP;
692 ifr = (struct ifreq *)data;
693 if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
696 error = EAFNOSUPPORT;