/* $FreeBSD$ */ /* $KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $ */ /*- * Copyright (C) 2000 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * 6to4 interface, based on RFC3056. * * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting. * There is no address mapping defined from IPv6 multicast address to IPv4 * address. Therefore, we do not have IFF_MULTICAST on the interface. * * Due to the lack of address mapping for link-local addresses, we cannot * throw packets toward link-local addresses (fe80::x). Also, we cannot throw * packets to link-local multicast addresses (ff02::x). * * Here are interesting symptoms due to the lack of link-local address: * * Unicast routing exchange: * - RIPng: Impossible. Uses link-local multicast packet toward ff02::9, * and link-local addresses as nexthop. * - OSPFv6: Impossible. OSPFv6 assumes that there's link-local address * assigned to the link, and makes use of them. Also, HELLO packets use * link-local multicast addresses (ff02::5 and ff02::6). * - BGP4+: Maybe. You can only use global address as nexthop, and global * address as TCP endpoint address. * * Multicast routing protocols: * - PIM: Hello packet cannot be used to discover adjacent PIM routers. * Adjacent PIM routers must be configured manually (is it really spec-wise * correct thing to do?). * * ICMPv6: * - Redirects cannot be used due to the lack of link-local address. * * stf interface does not have, and will not need, a link-local address. * It seems to have no real benefit and does not help the above symptoms much. * Even if we assign link-locals to interface, we cannot really * use link-local unicast/multicast on top of 6to4 cloud (since there's no * encapsulation defined for link-local address), and the above analysis does * not change. RFC3056 does not mandate the assignment of link-local address * either. * * 6to4 interface has security issues. Refer to * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt * for details. The code tries to filter out some of malicious packets. * Note that there is no way to be 100% secure. */ #include "opt_inet.h" #include "opt_inet6.h" #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include SYSCTL_DECL(_net_link); SYSCTL_NODE(_net_link, IFT_STF, stf, CTLFLAG_RW, 0, "6to4 Interface"); static int stf_route_cache = 1; SYSCTL_INT(_net_link_stf, OID_AUTO, route_cache, CTLFLAG_RW, &stf_route_cache, 0, "Caching of IPv4 routes for 6to4 Output"); #define STFNAME "stf" #define STFUNIT 0 #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002) /* * XXX: Return a pointer with 16-bit aligned. Don't cast it to * struct in_addr *; use bcopy() instead. */ #define GET_V4(x) ((caddr_t)(&(x)->s6_addr16[1])) struct stf_softc { struct ifnet *sc_ifp; union { struct route __sc_ro4; struct route_in6 __sc_ro6; /* just for safety */ } __sc_ro46; #define sc_ro __sc_ro46.__sc_ro4 struct mtx sc_ro_mtx; u_int sc_fibnum; const struct encaptab *encap_cookie; }; #define STF2IFP(sc) ((sc)->sc_ifp) /* * Note that mutable fields in the softc are not currently locked. * We do lock sc_ro in stf_output though. */ static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface"); static const int ip_stf_ttl = 40; extern struct domain inetdomain; struct protosw in_stf_protosw = { .pr_type = SOCK_RAW, .pr_domain = &inetdomain, .pr_protocol = IPPROTO_IPV6, .pr_flags = PR_ATOMIC|PR_ADDR, .pr_input = in_stf_input, .pr_output = (pr_output_t *)rip_output, .pr_ctloutput = rip_ctloutput, .pr_usrreqs = &rip_usrreqs }; static char *stfnames[] = {"stf0", "stf", "6to4", NULL}; static int stfmodevent(module_t, int, void *); static int stf_encapcheck(const struct mbuf *, int, int, void *); static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *); static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *, struct route *); static int isrfc1918addr(struct in_addr *); static int stf_checkaddr4(struct stf_softc *, struct in_addr *, struct ifnet *); static int stf_checkaddr6(struct stf_softc *, struct in6_addr *, struct ifnet *); static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *); static int stf_ioctl(struct ifnet *, u_long, caddr_t); static int stf_clone_match(struct if_clone *, const char *); static int stf_clone_create(struct if_clone *, char *, size_t, caddr_t); static int stf_clone_destroy(struct if_clone *, struct ifnet *); struct if_clone stf_cloner = IFC_CLONE_INITIALIZER(STFNAME, NULL, 0, NULL, stf_clone_match, stf_clone_create, stf_clone_destroy); static int stf_clone_match(struct if_clone *ifc, const char *name) { int i; for(i = 0; stfnames[i] != NULL; i++) { if (strcmp(stfnames[i], name) == 0) return (1); } return (0); } static int stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params) { int err, unit; struct stf_softc *sc; struct ifnet *ifp; /* * We can only have one unit, but since unit allocation is * already locked, we use it to keep from allocating extra * interfaces. */ unit = STFUNIT; err = ifc_alloc_unit(ifc, &unit); if (err != 0) return (err); sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO); ifp = STF2IFP(sc) = if_alloc(IFT_STF); if (ifp == NULL) { free(sc, M_STF); ifc_free_unit(ifc, unit); return (ENOSPC); } ifp->if_softc = sc; sc->sc_fibnum = curthread->td_proc->p_fibnum; /* * Set the name manually rather then using if_initname because * we don't conform to the default naming convention for interfaces. */ strlcpy(ifp->if_xname, name, IFNAMSIZ); ifp->if_dname = ifc->ifc_name; ifp->if_dunit = IF_DUNIT_NONE; mtx_init(&(sc)->sc_ro_mtx, "stf ro", NULL, MTX_DEF); sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck, &in_stf_protosw, sc); if (sc->encap_cookie == NULL) { if_printf(ifp, "attach failed\n"); free(sc, M_STF); ifc_free_unit(ifc, unit); return (ENOMEM); } ifp->if_mtu = IPV6_MMTU; ifp->if_ioctl = stf_ioctl; ifp->if_output = stf_output; ifp->if_snd.ifq_maxlen = IFQ_MAXLEN; if_attach(ifp); bpfattach(ifp, DLT_NULL, sizeof(u_int32_t)); return (0); } static int stf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp) { struct stf_softc *sc = ifp->if_softc; int err; err = encap_detach(sc->encap_cookie); KASSERT(err == 0, ("Unexpected error detaching encap_cookie")); mtx_destroy(&(sc)->sc_ro_mtx); bpfdetach(ifp); if_detach(ifp); if_free(ifp); free(sc, M_STF); ifc_free_unit(ifc, STFUNIT); return (0); } static int stfmodevent(mod, type, data) module_t mod; int type; void *data; { switch (type) { case MOD_LOAD: if_clone_attach(&stf_cloner); break; case MOD_UNLOAD: if_clone_detach(&stf_cloner); break; default: return (EOPNOTSUPP); } return (0); } static moduledata_t stf_mod = { "if_stf", stfmodevent, 0 }; DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); static int stf_encapcheck(m, off, proto, arg) const struct mbuf *m; int off; int proto; void *arg; { struct ip ip; struct in6_ifaddr *ia6; struct stf_softc *sc; struct in_addr a, b, mask; sc = (struct stf_softc *)arg; if (sc == NULL) return 0; if ((STF2IFP(sc)->if_flags & IFF_UP) == 0) return 0; /* IFF_LINK0 means "no decapsulation" */ if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0) return 0; if (proto != IPPROTO_IPV6) return 0; /* LINTED const cast */ m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip); if (ip.ip_v != 4) return 0; ia6 = stf_getsrcifa6(STF2IFP(sc)); if (ia6 == NULL) return 0; /* * check if IPv4 dst matches the IPv4 address derived from the * local 6to4 address. * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:... */ if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst, sizeof(ip.ip_dst)) != 0) return 0; /* * check if IPv4 src matches the IPv4 address derived from the * local 6to4 address masked by prefixmask. * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24 */ bzero(&a, sizeof(a)); bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a)); bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask)); a.s_addr &= mask.s_addr; b = ip.ip_src; b.s_addr &= mask.s_addr; if (a.s_addr != b.s_addr) return 0; /* stf interface makes single side match only */ return 32; } static struct in6_ifaddr * stf_getsrcifa6(ifp) struct ifnet *ifp; { INIT_VNET_INET(ifp->if_vnet); struct ifaddr *ia; struct in_ifaddr *ia4; struct sockaddr_in6 *sin6; struct in_addr in; IF_ADDR_LOCK(ifp); TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { if (ia->ifa_addr->sa_family != AF_INET6) continue; sin6 = (struct sockaddr_in6 *)ia->ifa_addr; if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) continue; bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in)); LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash) if (ia4->ia_addr.sin_addr.s_addr == in.s_addr) break; if (ia4 == NULL) continue; IF_ADDR_UNLOCK(ifp); return (struct in6_ifaddr *)ia; } IF_ADDR_UNLOCK(ifp); return NULL; } static int stf_output(ifp, m, dst, ro) struct ifnet *ifp; struct mbuf *m; struct sockaddr *dst; struct route *ro; { struct stf_softc *sc; struct sockaddr_in6 *dst6; struct route *cached_route; struct in_addr in4; caddr_t ptr; struct sockaddr_in *dst4; u_int8_t tos; struct ip *ip; struct ip6_hdr *ip6; struct in6_ifaddr *ia6; u_int32_t af; int error; #ifdef MAC error = mac_ifnet_check_transmit(ifp, m); if (error) { m_freem(m); return (error); } #endif sc = ifp->if_softc; dst6 = (struct sockaddr_in6 *)dst; /* just in case */ if ((ifp->if_flags & IFF_UP) == 0) { m_freem(m); ifp->if_oerrors++; return ENETDOWN; } /* * If we don't have an ip4 address that match my inner ip6 address, * we shouldn't generate output. Without this check, we'll end up * using wrong IPv4 source. */ ia6 = stf_getsrcifa6(ifp); if (ia6 == NULL) { m_freem(m); ifp->if_oerrors++; return ENETDOWN; } if (m->m_len < sizeof(*ip6)) { m = m_pullup(m, sizeof(*ip6)); if (!m) { ifp->if_oerrors++; return ENOBUFS; } } ip6 = mtod(m, struct ip6_hdr *); tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; /* * BPF writes need to be handled specially. * This is a null operation, nothing here checks dst->sa_family. */ if (dst->sa_family == AF_UNSPEC) { bcopy(dst->sa_data, &af, sizeof(af)); dst->sa_family = af; } /* * Pickup the right outer dst addr from the list of candidates. * ip6_dst has priority as it may be able to give us shorter IPv4 hops. */ ptr = NULL; if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst)) ptr = GET_V4(&ip6->ip6_dst); else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr)) ptr = GET_V4(&dst6->sin6_addr); else { m_freem(m); ifp->if_oerrors++; return ENETUNREACH; } bcopy(ptr, &in4, sizeof(in4)); if (bpf_peers_present(ifp->if_bpf)) { /* * We need to prepend the address family as * a four byte field. Cons up a dummy header * to pacify bpf. This is safe because bpf * will only read from the mbuf (i.e., it won't * try to free it or keep a pointer a to it). */ af = AF_INET6; bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m); } M_PREPEND(m, sizeof(struct ip), M_DONTWAIT); if (m && m->m_len < sizeof(struct ip)) m = m_pullup(m, sizeof(struct ip)); if (m == NULL) { ifp->if_oerrors++; return ENOBUFS; } ip = mtod(m, struct ip *); bzero(ip, sizeof(*ip)); bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr), &ip->ip_src, sizeof(ip->ip_src)); bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst)); ip->ip_p = IPPROTO_IPV6; ip->ip_ttl = ip_stf_ttl; ip->ip_len = m->m_pkthdr.len; /*host order*/ if (ifp->if_flags & IFF_LINK1) ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos); else ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos); if (!stf_route_cache) { cached_route = NULL; goto sendit; } /* * Do we have a cached route? */ mtx_lock(&(sc)->sc_ro_mtx); dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst; if (dst4->sin_family != AF_INET || bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) { /* cache route doesn't match */ dst4->sin_family = AF_INET; dst4->sin_len = sizeof(struct sockaddr_in); bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr)); if (sc->sc_ro.ro_rt) { RTFREE(sc->sc_ro.ro_rt); sc->sc_ro.ro_rt = NULL; } } if (sc->sc_ro.ro_rt == NULL) { rtalloc_fib(&sc->sc_ro, sc->sc_fibnum); if (sc->sc_ro.ro_rt == NULL) { m_freem(m); mtx_unlock(&(sc)->sc_ro_mtx); ifp->if_oerrors++; return ENETUNREACH; } } cached_route = &sc->sc_ro; sendit: M_SETFIB(m, sc->sc_fibnum); ifp->if_opackets++; error = ip_output(m, NULL, cached_route, 0, NULL, NULL); if (cached_route != NULL) mtx_unlock(&(sc)->sc_ro_mtx); return error; } static int isrfc1918addr(in) struct in_addr *in; { /* * returns 1 if private address range: * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 */ if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 || (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 || (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168) return 1; return 0; } static int stf_checkaddr4(sc, in, inifp) struct stf_softc *sc; struct in_addr *in; struct ifnet *inifp; /* incoming interface */ { INIT_VNET_INET(curvnet); struct in_ifaddr *ia4; /* * reject packets with the following address: * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8 */ if (IN_MULTICAST(ntohl(in->s_addr))) return -1; switch ((ntohl(in->s_addr) & 0xff000000) >> 24) { case 0: case 127: case 255: return -1; } /* * reject packets with private address range. * (requirement from RFC3056 section 2 1st paragraph) */ if (isrfc1918addr(in)) return -1; /* * reject packets with broadcast */ for (ia4 = TAILQ_FIRST(&V_in_ifaddrhead); ia4; ia4 = TAILQ_NEXT(ia4, ia_link)) { if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0) continue; if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) return -1; } /* * perform ingress filter */ if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) { struct sockaddr_in sin; struct rtentry *rt; bzero(&sin, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_len = sizeof(struct sockaddr_in); sin.sin_addr = *in; rt = rtalloc1_fib((struct sockaddr *)&sin, 0, 0UL, sc->sc_fibnum); if (!rt || rt->rt_ifp != inifp) { #if 0 log(LOG_WARNING, "%s: packet from 0x%x dropped " "due to ingress filter\n", if_name(STF2IFP(sc)), (u_int32_t)ntohl(sin.sin_addr.s_addr)); #endif if (rt) RTFREE_LOCKED(rt); return -1; } RTFREE_LOCKED(rt); } return 0; } static int stf_checkaddr6(sc, in6, inifp) struct stf_softc *sc; struct in6_addr *in6; struct ifnet *inifp; /* incoming interface */ { /* * check 6to4 addresses */ if (IN6_IS_ADDR_6TO4(in6)) { struct in_addr in4; bcopy(GET_V4(in6), &in4, sizeof(in4)); return stf_checkaddr4(sc, &in4, inifp); } /* * reject anything that look suspicious. the test is implemented * in ip6_input too, but we check here as well to * (1) reject bad packets earlier, and * (2) to be safe against future ip6_input change. */ if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6)) return -1; return 0; } void in_stf_input(m, off) struct mbuf *m; int off; { int proto; struct stf_softc *sc; struct ip *ip; struct ip6_hdr *ip6; u_int8_t otos, itos; struct ifnet *ifp; proto = mtod(m, struct ip *)->ip_p; if (proto != IPPROTO_IPV6) { m_freem(m); return; } ip = mtod(m, struct ip *); sc = (struct stf_softc *)encap_getarg(m); if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) { m_freem(m); return; } ifp = STF2IFP(sc); #ifdef MAC mac_ifnet_create_mbuf(ifp, m); #endif /* * perform sanity check against outer src/dst. * for source, perform ingress filter as well. */ if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 || stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) { m_freem(m); return; } otos = ip->ip_tos; m_adj(m, off); if (m->m_len < sizeof(*ip6)) { m = m_pullup(m, sizeof(*ip6)); if (!m) return; } ip6 = mtod(m, struct ip6_hdr *); /* * perform sanity check against inner src/dst. * for source, perform ingress filter as well. */ if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 || stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) { m_freem(m); return; } itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; if ((ifp->if_flags & IFF_LINK1) != 0) ip_ecn_egress(ECN_ALLOWED, &otos, &itos); else ip_ecn_egress(ECN_NOCARE, &otos, &itos); ip6->ip6_flow &= ~htonl(0xff << 20); ip6->ip6_flow |= htonl((u_int32_t)itos << 20); m->m_pkthdr.rcvif = ifp; if (bpf_peers_present(ifp->if_bpf)) { /* * We need to prepend the address family as * a four byte field. Cons up a dummy header * to pacify bpf. This is safe because bpf * will only read from the mbuf (i.e., it won't * try to free it or keep a pointer a to it). */ u_int32_t af = AF_INET6; bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m); } /* * Put the packet to the network layer input queue according to the * specified address family. * See net/if_gif.c for possible issues with packet processing * reorder due to extra queueing. */ ifp->if_ipackets++; ifp->if_ibytes += m->m_pkthdr.len; netisr_dispatch(NETISR_IPV6, m); } /* ARGSUSED */ static void stf_rtrequest(cmd, rt, info) int cmd; struct rtentry *rt; struct rt_addrinfo *info; { RT_LOCK_ASSERT(rt); rt->rt_rmx.rmx_mtu = IPV6_MMTU; } static int stf_ioctl(ifp, cmd, data) struct ifnet *ifp; u_long cmd; caddr_t data; { struct ifaddr *ifa; struct ifreq *ifr; struct sockaddr_in6 *sin6; struct in_addr addr; int error; error = 0; switch (cmd) { case SIOCSIFADDR: ifa = (struct ifaddr *)data; if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) { error = EAFNOSUPPORT; break; } sin6 = (struct sockaddr_in6 *)ifa->ifa_addr; if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) { error = EINVAL; break; } bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr)); if (isrfc1918addr(&addr)) { error = EINVAL; break; } ifa->ifa_rtrequest = stf_rtrequest; ifp->if_flags |= IFF_UP; break; case SIOCADDMULTI: case SIOCDELMULTI: ifr = (struct ifreq *)data; if (ifr && ifr->ifr_addr.sa_family == AF_INET6) ; else error = EAFNOSUPPORT; break; default: error = EINVAL; break; } return error; }