/* $NetBSD: if_stf.c,v 1.44 2005/01/25 17:22:08 matt Exp $ */ /* $KAME: if_stf.c,v 1.62 2001/06/07 22:32:16 itojun 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 __KERNEL_RCSID(0, "$NetBSD: if_stf.c,v 1.44 2005/01/25 17:22:08 matt Exp $"); #include "opt_inet.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 "bpfilter.h" #include "stf.h" #include "gif.h" /*XXX*/ #if NBPFILTER > 0 #include #endif #if NGIF > 0 #include #endif #define IN6_IS_ADDR_6TO4(x) (ntohs((x)->s6_addr16[0]) == 0x2002) #define GET_V4(x) ((struct in_addr *)(&(x)->s6_addr16[1])) struct stf_softc { struct ifnet sc_if; /* common area */ union { struct route __sc_ro4; struct route_in6 __sc_ro6; /* just for safety */ } __sc_ro46; #define sc_ro __sc_ro46.__sc_ro4 const struct encaptab *encap_cookie; LIST_ENTRY(stf_softc) sc_list; }; LIST_HEAD(, stf_softc) stf_softc_list; int stf_clone_create __P((struct if_clone *, int)); int stf_clone_destroy __P((struct ifnet *)); struct if_clone stf_cloner = IF_CLONE_INITIALIZER("stf", stf_clone_create, stf_clone_destroy); #if NGIF > 0 extern int ip_gif_ttl; /*XXX*/ #else static int ip_gif_ttl = 40; /*XXX*/ #endif extern struct domain inetdomain; const struct protosw in_stf_protosw = { SOCK_RAW, &inetdomain, IPPROTO_IPV6, PR_ATOMIC|PR_ADDR, in_stf_input, rip_output, 0, rip_ctloutput, rip_usrreq, 0, 0, 0, 0 }; void stfattach __P((int)); static int stf_encapcheck __P((const struct mbuf *, int, int, void *)); static struct in6_ifaddr *stf_getsrcifa6 __P((struct ifnet *)); static int stf_output __P((struct ifnet *, struct mbuf *, struct sockaddr *, struct rtentry *)); static int isrfc1918addr __P((struct in_addr *)); static int stf_checkaddr4 __P((struct stf_softc *, struct in_addr *, struct ifnet *)); static int stf_checkaddr6 __P((struct stf_softc *, struct in6_addr *, struct ifnet *)); static void stf_rtrequest __P((int, struct rtentry *, struct rt_addrinfo *)); static int stf_ioctl __P((struct ifnet *, u_long, caddr_t)); /* ARGSUSED */ void stfattach(count) int count; { LIST_INIT(&stf_softc_list); if_clone_attach(&stf_cloner); } int stf_clone_create(ifc, unit) struct if_clone *ifc; int unit; { struct stf_softc *sc; if (LIST_FIRST(&stf_softc_list) != NULL) { /* Only one stf interface is allowed. */ return (EEXIST); } sc = malloc(sizeof(struct stf_softc), M_DEVBUF, M_WAIT); memset(sc, 0, sizeof(struct stf_softc)); snprintf(sc->sc_if.if_xname, sizeof(sc->sc_if.if_xname), "%s%d", ifc->ifc_name, unit); sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck, &in_stf_protosw, sc); if (sc->encap_cookie == NULL) { printf("%s: unable to attach encap\n", if_name(&sc->sc_if)); free(sc, M_DEVBUF); return (EIO); /* XXX */ } sc->sc_if.if_mtu = IPV6_MMTU; sc->sc_if.if_flags = 0; sc->sc_if.if_ioctl = stf_ioctl; sc->sc_if.if_output = stf_output; sc->sc_if.if_type = IFT_STF; sc->sc_if.if_dlt = DLT_NULL; if_attach(&sc->sc_if); if_alloc_sadl(&sc->sc_if); #if NBPFILTER > 0 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int)); #endif LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list); return (0); } int stf_clone_destroy(ifp) struct ifnet *ifp; { struct stf_softc *sc = (void *) ifp; LIST_REMOVE(sc, sc_list); encap_detach(sc->encap_cookie); #if NBPFILTER > 0 bpfdetach(ifp); #endif if_detach(ifp); free(sc, M_DEVBUF); return (0); } 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; sc = (struct stf_softc *)arg; if (sc == NULL) return 0; if ((sc->sc_if.if_flags & IFF_UP) == 0) return 0; /* IFF_LINK0 means "no decapsulation" */ if ((sc->sc_if.if_flags & IFF_LINK0) != 0) return 0; if (proto != IPPROTO_IPV6) return 0; /* LINTED const cast */ m_copydata((struct mbuf *)m, 0, sizeof(ip), (caddr_t)&ip); if (ip.ip_v != 4) return 0; ia6 = stf_getsrcifa6(&sc->sc_if); 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 */ memset(&a, 0, sizeof(a)); a.s_addr = GET_V4(&ia6->ia_addr.sin6_addr)->s_addr; a.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->s_addr; b = ip.ip_src; b.s_addr &= GET_V4(&ia6->ia_prefixmask.sin6_addr)->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; { struct ifaddr *ifa; struct in_ifaddr *ia4; struct sockaddr_in6 *sin6; struct in_addr in; IFADDR_FOREACH(ifa, ifp) { if (ifa->ifa_addr == NULL) continue; if (ifa->ifa_addr->sa_family != AF_INET6) continue; sin6 = (struct sockaddr_in6 *)ifa->ifa_addr; if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) continue; bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in)); INADDR_TO_IA(in, ia4); if (ia4 == NULL) continue; return (struct in6_ifaddr *)ifa; } return NULL; } static int stf_output(ifp, m, dst, rt) struct ifnet *ifp; struct mbuf *m; struct sockaddr *dst; struct rtentry *rt; { struct stf_softc *sc; struct sockaddr_in6 *dst6; struct in_addr *in4; struct sockaddr_in *dst4; u_int8_t tos; struct ip *ip; struct ip6_hdr *ip6; struct in6_ifaddr *ia6; sc = (struct stf_softc*)ifp; dst6 = (struct sockaddr_in6 *)dst; /* just in case */ if ((ifp->if_flags & IFF_UP) == 0) { m_freem(m); 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 == NULL) { ifp->if_oerrors++; return ENOBUFS; } } ip6 = mtod(m, struct ip6_hdr *); tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; /* * 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. */ if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst)) in4 = GET_V4(&ip6->ip6_dst); else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr)) in4 = GET_V4(&dst6->sin6_addr); else { m_freem(m); ifp->if_oerrors++; return ENETUNREACH; } #if NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap_af(ifp->if_bpf, AF_INET6, m); #endif /*NBPFILTER > 0*/ 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 *); memset(ip, 0, 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_gif_ttl; /*XXX*/ ip->ip_len = htons(m->m_pkthdr.len); 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); 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(&sc->sc_ro); if (sc->sc_ro.ro_rt == NULL) { m_freem(m); ifp->if_oerrors++; return ENETUNREACH; } } ifp->if_opackets++; return ip_output(m, NULL, &sc->sc_ro, 0, (struct ip_moptions *)NULL, (struct socket *)NULL); } 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 */ { 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(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 packet with IPv4 link-local (169.254.0.0/16), * as suggested in draft-savola-v6ops-6to4-security-00.txt */ if (((ntohl(in->s_addr) & 0xff000000) >> 24) == 169 && ((ntohl(in->s_addr) & 0x00ff0000) >> 16) == 254) return -1; /* * reject packets with broadcast */ TAILQ_FOREACH(ia4, &in_ifaddrhead, ia_list) { 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 && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) { struct sockaddr_in sin; struct rtentry *rt; memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_len = sizeof(struct sockaddr_in); sin.sin_addr = *in; rt = rtalloc1((struct sockaddr *)&sin, 0); if (!rt || rt->rt_ifp != inifp) { #if 0 log(LOG_WARNING, "%s: packet from 0x%x dropped " "due to ingress filter\n", if_name(&sc->sc_if), (u_int32_t)ntohl(sin.sin_addr.s_addr)); #endif if (rt) rtfree(rt); return -1; } rtfree(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)) return stf_checkaddr4(sc, GET_V4(in6), 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; /* * reject link-local and site-local unicast * as suggested in draft-savola-v6ops-6to4-security-00.txt */ if (IN6_IS_ADDR_LINKLOCAL(in6) || IN6_IS_ADDR_SITELOCAL(in6)) return -1; /* * reject node-local and link-local multicast * as suggested in draft-savola-v6ops-6to4-security-00.txt */ if (IN6_IS_ADDR_MC_NODELOCAL(in6) || IN6_IS_ADDR_MC_LINKLOCAL(in6)) return -1; return 0; } void in_stf_input(struct mbuf *m, ...) { int off, proto; struct stf_softc *sc; struct ip *ip; struct ip6_hdr *ip6; u_int8_t otos, itos; int s, isr; struct ifqueue *ifq = NULL; struct ifnet *ifp; va_list ap; va_start(ap, m); off = va_arg(ap, int); proto = va_arg(ap, int); va_end(ap); if (proto != IPPROTO_IPV6) { m_freem(m); return; } ip = mtod(m, struct ip *); sc = (struct stf_softc *)encap_getarg(m); if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) { m_freem(m); return; } ifp = &sc->sc_if; /* * 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 NBPFILTER > 0 if (ifp->if_bpf) bpf_mtap_af(ifp->if_bpf, AF_INET6, m); #endif /*NBPFILTER > 0*/ /* * 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. */ ifq = &ip6intrq; isr = NETISR_IPV6; s = splnet(); if (IF_QFULL(ifq)) { IF_DROP(ifq); /* update statistics */ m_freem(m); splx(s); return; } IF_ENQUEUE(ifq, m); schednetisr(isr); ifp->if_ipackets++; ifp->if_ibytes += m->m_pkthdr.len; splx(s); } /* ARGSUSED */ static void stf_rtrequest(cmd, rt, info) int cmd; struct rtentry *rt; struct rt_addrinfo *info; { if (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; 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) && !isrfc1918addr(GET_V4(&sin6->sin6_addr))) { ifa->ifa_rtrequest = stf_rtrequest; ifp->if_flags |= IFF_UP; } else error = EINVAL; 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; }