/* $OpenBSD: ip6_forward.c,v 1.52 2011/03/24 20:09:45 bluhm Exp $ */ /* $KAME: ip6_forward.c,v 1.75 2001/06/29 12:42:13 jinmei Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 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. */ #include "pf.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if NPF > 0 #include #endif #ifdef IPSEC #include #include #include #include #include #include #endif struct route_in6 ip6_forward_rt; /* * Forward a packet. If some error occurs return the sender * an icmp packet. Note we can't always generate a meaningful * icmp message because icmp doesn't have a large enough repertoire * of codes and types. * * If not forwarding, just drop the packet. This could be confusing * if ipforwarding was zero but some routing protocol was advancing * us as a gateway to somewhere. However, we must let the routing * protocol deal with that. * */ void ip6_forward(struct mbuf *m, int srcrt) { struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); struct sockaddr_in6 *dst; struct rtentry *rt; int error = 0, type = 0, code = 0; struct mbuf *mcopy = NULL; struct ifnet *origifp; /* maybe unnecessary */ #ifdef IPSEC u_int8_t sproto = 0; struct m_tag *mtag; union sockaddr_union sdst; struct tdb_ident *tdbi; u_int32_t sspi; struct tdb *tdb; int s; #if NPF > 0 struct ifnet *encif; #endif #endif /* IPSEC */ u_int rtableid = 0; /* * Do not forward packets to multicast destination (should be handled * by ip6_mforward(). * Do not forward packets with unspecified source. It was discussed * in July 2000, on ipngwg mailing list. */ if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { ip6stat.ip6s_cantforward++; /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ if (ip6_log_time + ip6_log_interval < time_second) { ip6_log_time = time_second; log(LOG_DEBUG, "cannot forward " "from %s to %s nxt %d received on %s\n", ip6_sprintf(&ip6->ip6_src), ip6_sprintf(&ip6->ip6_dst), ip6->ip6_nxt, m->m_pkthdr.rcvif->if_xname); } m_freem(m); return; } if (ip6->ip6_hlim <= IPV6_HLIMDEC) { /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ icmp6_error(m, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT, 0); return; } ip6->ip6_hlim -= IPV6_HLIMDEC; #if NPF > 0 reroute: #endif #ifdef IPSEC if (!ipsec_in_use) goto done_spd; s = splnet(); /* * Check if there was an outgoing SA bound to the flow * from a transport protocol. */ /* Do we have any pending SAs to apply ? */ mtag = m_tag_find(m, PACKET_TAG_IPSEC_PENDING_TDB, NULL); if (mtag != NULL) { #ifdef DIAGNOSTIC if (mtag->m_tag_len != sizeof (struct tdb_ident)) panic("ip6_forward: tag of length %d (should be %d", mtag->m_tag_len, sizeof (struct tdb_ident)); #endif tdbi = (struct tdb_ident *)(mtag + 1); tdb = gettdb(tdbi->rdomain, tdbi->spi, &tdbi->dst, tdbi->proto); if (tdb == NULL) error = -EINVAL; m_tag_delete(m, mtag); } else tdb = ipsp_spd_lookup(m, AF_INET6, sizeof(struct ip6_hdr), &error, IPSP_DIRECTION_OUT, NULL, NULL); if (tdb == NULL) { splx(s); if (error == 0) { /* * No IPsec processing required, we'll just send the * packet out. */ sproto = 0; /* Fall through to routing/multicast handling */ } else { /* * -EINVAL is used to indicate that the packet should * be silently dropped, typically because we've asked * key management for an SA. */ if (error == -EINVAL) /* Should silently drop packet */ error = 0; goto freecopy; } } else { /* Loop detection */ for (mtag = m_tag_first(m); mtag != NULL; mtag = m_tag_next(m, mtag)) { if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE && mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED) continue; tdbi = (struct tdb_ident *)(mtag + 1); if (tdbi->spi == tdb->tdb_spi && tdbi->proto == tdb->tdb_sproto && tdbi->rdomain == tdb->tdb_rdomain && !bcmp(&tdbi->dst, &tdb->tdb_dst, sizeof(union sockaddr_union))) { splx(s); sproto = 0; /* mark as no-IPsec-needed */ goto done_spd; } } /* We need to do IPsec */ bcopy(&tdb->tdb_dst, &sdst, sizeof(sdst)); sspi = tdb->tdb_spi; sproto = tdb->tdb_sproto; splx(s); } /* Fall through to the routing/multicast handling code */ done_spd: #endif /* IPSEC */ #if NPF > 0 rtableid = m->m_pkthdr.rdomain; #endif /* * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - * size of IPv6 + ICMPv6 headers) bytes of the packet in case * we need to generate an ICMP6 message to the src. * Thanks to M_EXT, in most cases copy will not occur. * * It is important to save it before IPsec processing as IPsec * processing may modify the mbuf. */ mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); dst = &ip6_forward_rt.ro_dst; if (!srcrt) { /* * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */ if (ip6_forward_rt.ro_rt == 0 || (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0 || ip6_forward_rt.ro_tableid != rtableid) { if (ip6_forward_rt.ro_rt) { RTFREE(ip6_forward_rt.ro_rt); ip6_forward_rt.ro_rt = 0; } /* this probably fails but give it a try again */ ip6_forward_rt.ro_tableid = rtableid; rtalloc_mpath((struct route *)&ip6_forward_rt, &ip6->ip6_src.s6_addr32[0]); } if (ip6_forward_rt.ro_rt == 0) { ip6stat.ip6s_noroute++; /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ if (mcopy) { icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE, 0); } m_freem(m); return; } } else if (ip6_forward_rt.ro_rt == 0 || (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0 || !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr) || ip6_forward_rt.ro_tableid != rtableid) { if (ip6_forward_rt.ro_rt) { RTFREE(ip6_forward_rt.ro_rt); ip6_forward_rt.ro_rt = 0; } bzero(dst, sizeof(*dst)); dst->sin6_len = sizeof(struct sockaddr_in6); dst->sin6_family = AF_INET6; dst->sin6_addr = ip6->ip6_dst; ip6_forward_rt.ro_tableid = rtableid; rtalloc_mpath((struct route *)&ip6_forward_rt, &ip6->ip6_src.s6_addr32[0]); if (ip6_forward_rt.ro_rt == 0) { ip6stat.ip6s_noroute++; /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ if (mcopy) { icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE, 0); } m_freem(m); return; } } rt = ip6_forward_rt.ro_rt; /* * Scope check: if a packet can't be delivered to its destination * for the reason that the destination is beyond the scope of the * source address, discard the packet and return an icmp6 destination * unreachable error with Code 2 (beyond scope of source address). * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] */ if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { ip6stat.ip6s_cantforward++; ip6stat.ip6s_badscope++; in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); if (ip6_log_time + ip6_log_interval < time_second) { ip6_log_time = time_second; log(LOG_DEBUG, "cannot forward " "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", ip6_sprintf(&ip6->ip6_src), ip6_sprintf(&ip6->ip6_dst), ip6->ip6_nxt, m->m_pkthdr.rcvif->if_xname, rt->rt_ifp->if_xname); } if (mcopy) icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_BEYONDSCOPE, 0); m_freem(m); goto freert; } #ifdef IPSEC /* * Check if the packet needs encapsulation. * ipsp_process_packet will never come back to here. * XXX ipsp_process_packet() calls ip6_output(), and there'll be no * PMTU notification. is it okay? */ if (sproto != 0) { s = splnet(); tdb = gettdb(rtable_l2(m->m_pkthdr.rdomain), sspi, &sdst, sproto); if (tdb == NULL) { splx(s); error = EHOSTUNREACH; m_freem(m); goto senderr; /*XXX*/ } #if NPF > 0 if ((encif = enc_getif(tdb->tdb_rdomain, tdb->tdb_tap)) == NULL || pf_test6(PF_FWD, encif, &m, NULL) != PF_PASS) { splx(s); error = EHOSTUNREACH; m_freem(m); goto senderr; } if (m == NULL) { splx(s); goto senderr; } ip6 = mtod(m, struct ip6_hdr *); /* * PF_TAG_REROUTE handling or not... * Packet is entering IPsec so the routing is * already overruled by the IPsec policy. * Until now the change was not reconsidered. * What's the behaviour? */ #endif m->m_flags &= ~(M_BCAST | M_MCAST); /* just in case */ /* Callee frees mbuf */ error = ipsp_process_packet(m, tdb, AF_INET6, 0); splx(s); m_freem(mcopy); goto freert; } #endif /* IPSEC */ if (rt->rt_flags & RTF_GATEWAY) dst = (struct sockaddr_in6 *)rt->rt_gateway; /* * If we are to forward the packet using the same interface * as one we got the packet from, perhaps we should send a redirect * to sender to shortcut a hop. * Only send redirect if source is sending directly to us, * and if packet was not source routed (or has any options). * Also, don't send redirect if forwarding using a route * modified by a redirect. */ if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && ip6_sendredirects && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) && nd6_is_addr_neighbor((struct sockaddr_in6 *)&ip6_forward_rt.ro_dst, rt->rt_ifp)) { /* * If the incoming interface is equal to the outgoing * one, the link attached to the interface is * point-to-point, and the IPv6 destination is * regarded as on-link on the link, then it will be * highly probable that the destination address does * not exist on the link and that the packet is going * to loop. Thus, we immediately drop the packet and * send an ICMPv6 error message. * For other routing loops, we dare to let the packet * go to the loop, so that a remote diagnosing host * can detect the loop by traceroute. * type/code is based on suggestion by Rich Draves. * not sure if it is the best pick. */ if (mcopy) icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 0); m_freem(m); goto freert; } type = ND_REDIRECT; } /* * Fake scoped addresses. Note that even link-local source or * destinaion can appear, if the originating node just sends the * packet to us (without address resolution for the destination). * Since both icmp6_error and icmp6_redirect_output fill the embedded * link identifiers, we can do this stuff after making a copy for * returning an error. */ if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { /* * See corresponding comments in ip6_output. * XXX: but is it possible that ip6_forward() sends a packet * to a loopback interface? I don't think so, and thus * I bark here. (jinmei@kame.net) * XXX: it is common to route invalid packets to loopback. * also, the codepath will be visited on use of ::1 in * rthdr. (itojun) */ #if 1 if (0) #else if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) #endif { printf("ip6_forward: outgoing interface is loopback. " "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", ip6_sprintf(&ip6->ip6_src), ip6_sprintf(&ip6->ip6_dst), ip6->ip6_nxt, m->m_pkthdr.rcvif->if_xname, rt->rt_ifp->if_xname); } /* we can just use rcvif in forwarding. */ origifp = m->m_pkthdr.rcvif; } else origifp = rt->rt_ifp; if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) ip6->ip6_src.s6_addr16[1] = 0; if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) ip6->ip6_dst.s6_addr16[1] = 0; #if NPF > 0 if (pf_test6(PF_FWD, rt->rt_ifp, &m, NULL) != PF_PASS) { m_freem(m); goto senderr; } if (m == NULL) goto senderr; ip6 = mtod(m, struct ip6_hdr *); if ((m->m_pkthdr.pf.flags & (PF_TAG_REROUTE | PF_TAG_GENERATED)) == (PF_TAG_REROUTE | PF_TAG_GENERATED)) { /* already rerun the route lookup, go on */ m->m_pkthdr.pf.flags &= ~(PF_TAG_GENERATED | PF_TAG_REROUTE); } else if (m->m_pkthdr.pf.flags & PF_TAG_REROUTE) { /* tag as generated to skip over pf_test on rerun */ m->m_pkthdr.pf.flags |= PF_TAG_GENERATED; srcrt = 1; goto reroute; } #endif /* Check the size after pf_test6 to give pf a chance to refragment. */ if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) { in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); if (mcopy) { u_long mtu; mtu = IN6_LINKMTU(rt->rt_ifp); icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); } m_freem(m); goto freert; } error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); if (error) { in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); ip6stat.ip6s_cantforward++; } else { ip6stat.ip6s_forward++; in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); if (type) ip6stat.ip6s_redirectsent++; else { if (mcopy) goto freecopy; } } #if NPF > 0 || defined(IPSEC) senderr: #endif if (mcopy == NULL) goto freert; switch (error) { case 0: if (type == ND_REDIRECT) { icmp6_redirect_output(mcopy, rt); goto freert; } goto freecopy; case EMSGSIZE: /* xxx MTU is constant in PPP? */ goto freecopy; case ENOBUFS: /* Tell source to slow down like source quench in IP? */ goto freecopy; case ENETUNREACH: /* shouldn't happen, checked above */ case EHOSTUNREACH: case ENETDOWN: case EHOSTDOWN: default: type = ICMP6_DST_UNREACH; code = ICMP6_DST_UNREACH_ADDR; break; } icmp6_error(mcopy, type, code, 0); goto freert; freecopy: m_freem(mcopy); freert: #ifndef SMALL_KERNEL if (ip6_multipath && ip6_forward_rt.ro_rt && (ip6_forward_rt.ro_rt->rt_flags & RTF_MPATH)) { RTFREE(ip6_forward_rt.ro_rt); ip6_forward_rt.ro_rt = 0; } #endif return; }