/* $FreeBSD: src/sys/net/if_stf.c,v 1.1.2.11 2003/01/23 21:06:44 sam Exp $ */ /* $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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "if_stf.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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 */ struct route *route_pcpu; const struct encaptab *encap_cookie; }; static struct stf_softc *stf; static MALLOC_DEFINE(M_STF, "stf", "6to4 Tunnel Interface"); static 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 = rip_output, .pr_ctlinput = NULL, .pr_ctloutput = rip_ctloutput, .pr_usrreqs = &rip_usrreqs }; 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 rtentry *); 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 *); static int stf_ioctl (struct ifnet *, u_long, caddr_t, struct ucred *); static int stfmodevent(module_t mod, int type, void *data) { struct stf_softc *sc; int err, cpu; const struct encaptab *p; switch (type) { case MOD_LOAD: stf = kmalloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO); sc = stf; bzero(sc, sizeof(*sc)); if_initname(&(sc->sc_if), "stf", 0); p = encap_attach_func(AF_INET, IPPROTO_IPV6, stf_encapcheck, (void *)&in_stf_protosw, sc); if (p == NULL) { kprintf("%s: attach failed\n", if_name(&sc->sc_if)); return (ENOMEM); } sc->encap_cookie = p; sc->route_pcpu = kmalloc(netisr_ncpus * sizeof(struct route), M_STF, M_WAITOK | M_ZERO); 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; #if 0 /* turn off ingress filter */ sc->sc_if.if_flags |= IFF_LINK2; #endif ifq_set_maxlen(&sc->sc_if.if_snd, IFQ_MAXLEN); if_attach(&sc->sc_if, NULL); bpfattach(&sc->sc_if, DLT_NULL, sizeof(uint32_t)); /* * 6to4 interface is very special: no multicast, no linklocal. * RFC2529 specifies how to make linklocals, but there's no * use and it is rather harmful to have one. * * NOTE: ND_IFINFO() is only available after if_attach(). */ ND_IFINFO(&sc->sc_if)->flags &= ~ND6_IFF_AUTO_LINKLOCAL; ND_IFINFO(&sc->sc_if)->flags |= ND6_IFF_NO_DAD; break; case MOD_UNLOAD: sc = stf; bpfdetach(&sc->sc_if); if_detach(&sc->sc_if); err = encap_detach(sc->encap_cookie); KASSERT(err == 0, ("Unexpected error detaching encap_cookie")); for (cpu = 0; cpu < netisr_ncpus; ++cpu) { if (sc->route_pcpu[cpu].ro_rt != NULL) { rtfree_async(sc->route_pcpu[cpu].ro_rt); sc->route_pcpu[cpu].ro_rt = NULL; } } kfree(sc->route_pcpu, M_STF); kfree(sc, M_STF); break; } 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(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; m_copydata(m, 0, sizeof(ip), &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 */ bzero(&a, 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(struct ifnet *ifp) { struct ifaddr_container *ifac; struct sockaddr_in6 *sin6; struct in_addr in; TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) { struct ifaddr *ia = ifac->ifa; struct in_ifaddr_container *iac; if (ia->ifa_addr == NULL) continue; 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(iac, INADDR_HASH(in.s_addr), ia_hash) { if (iac->ia->ia_addr.sin_addr.s_addr == in.s_addr) break; } if (iac == NULL) continue; return (struct in6_ifaddr *)ia; } return NULL; } static int stf_output_serialized(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; struct route *ro; static const uint32_t af = AF_INET6; ASSERT_NETISR_NCPUS(mycpuid); 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); return ENETDOWN; } if (m->m_len < sizeof(*ip6)) { m = m_pullup(m, sizeof(*ip6)); if (!m) 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); return ENETUNREACH; } if (ifp->if_bpf) { bpf_gettoken(); if (ifp->if_bpf) bpf_ptap(ifp->if_bpf, m, &af, sizeof(af)); bpf_reltoken(); } M_PREPEND(m, sizeof(struct ip), M_NOWAIT); if (m && m->m_len < sizeof(struct ip)) m = m_pullup(m, sizeof(struct ip)); if (m == NULL) 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 = htons(m->m_pkthdr.len); /* network 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); ro = &sc->route_pcpu[mycpuid]; dst4 = (struct sockaddr_in *)&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 (ro->ro_rt) { RTFREE(ro->ro_rt); ro->ro_rt = NULL; } } if (ro->ro_rt != NULL && (ro->ro_rt->rt_flags & RTF_UP) == 0) { RTFREE(ro->ro_rt); ro->ro_rt = NULL; } if (ro->ro_rt == NULL) { rtalloc(ro); if (ro->ro_rt == NULL) { m_freem(m); return ENETUNREACH; } } return ip_output(m, NULL, ro, IP_DEBUGROUTE, NULL, NULL); } static int stf_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, struct rtentry *rt) { struct ifaltq_subque *ifsq = ifq_get_subq_default(&ifp->if_snd); int error; ifsq_serialize_hw(ifsq); error = stf_output_serialized(ifp, m, dst, rt); ifsq_deserialize_hw(ifsq); return error; } /* * Parameters: * inifp: incoming interface */ static int stf_checkaddr4(struct stf_softc *sc, struct in_addr *in, struct ifnet *inifp) { struct in_ifaddr_container *iac; /* * 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 broadcast */ TAILQ_FOREACH(iac, &in_ifaddrheads[mycpuid], ia_link) { struct in_ifaddr *ia4 = iac->ia; 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; bzero(&sin, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_len = sizeof(struct sockaddr_in); sin.sin_addr = *in; rt = rtpurelookup((struct sockaddr *)&sin); 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; } /* * Parameters: * inifp: incoming interface */ static int stf_checkaddr6(struct stf_softc *sc, struct in6_addr *in6, struct ifnet *inifp) { /* * 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; return 0; } int in_stf_input(struct mbuf **mp, int *offp, int proto) { struct mbuf *m; struct stf_softc *sc; struct ip *ip; struct ip6_hdr *ip6; u_int8_t otos, itos; struct ifnet *ifp; int off; static const uint32_t af = AF_INET6; m = *mp; off = *offp; if (proto != IPPROTO_IPV6) { m_freem(m); return(IPPROTO_DONE); } 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(IPPROTO_DONE); } 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(IPPROTO_DONE); } otos = ip->ip_tos; m_adj(m, off); if (m->m_len < sizeof(*ip6)) { m = m_pullup(m, sizeof(*ip6)); if (!m) return(IPPROTO_DONE); } 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(IPPROTO_DONE); } 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 (ifp->if_bpf) { bpf_gettoken(); if (ifp->if_bpf) bpf_ptap(ifp->if_bpf, m, &af, sizeof(af)); bpf_reltoken(); } /* * 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. */ IFNET_STAT_INC(ifp, ipackets, 1); IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len); m->m_flags &= ~M_HASH; netisr_queue(NETISR_IPV6, m); return(IPPROTO_DONE); } /* ARGSUSED */ static void stf_rtrequest(int cmd, struct rtentry *rt) { if (rt) rt->rt_rmx.rmx_mtu = IPV6_MMTU; } static int stf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr) { 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)) { 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; }