/*- * SPDX-License-Identifier: BSD-3-Clause * * 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. * * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include "opt_inet6.h" #include "opt_ipsec.h" #include "opt_ipstealth.h" #include "opt_sctp.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 /* * 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 nhop_object *nh = NULL; int error, type = 0, code = 0; struct mbuf *mcopy = NULL; struct ifnet *origifp; /* maybe unnecessary */ u_int32_t inzone, outzone; struct in6_addr odst; struct m_tag *fwd_tag; char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN]; /* * 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 the 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_INC(ip6s_cantforward); /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ if (V_ip6_log_cannot_forward && ip6_log_ratelimit()) { log(LOG_DEBUG, "cannot forward " "from %s to %s nxt %d received on %s\n", ip6_sprintf(ip6bufs, &ip6->ip6_src), ip6_sprintf(ip6bufd, &ip6->ip6_dst), ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif)); } m_freem(m); return; } if ( #ifdef IPSTEALTH V_ip6stealth == 0 && #endif 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; } /* * 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_copym(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN), M_NOWAIT); #ifdef IPSTEALTH if (V_ip6stealth == 0) #endif ip6->ip6_hlim -= IPV6_HLIMDEC; #if defined(IPSEC) || defined(IPSEC_SUPPORT) if (IPSEC_ENABLED(ipv6)) { if ((error = IPSEC_FORWARD(ipv6, m)) != 0) { /* mbuf consumed by IPsec */ m_freem(mcopy); if (error != EINPROGRESS) IP6STAT_INC(ip6s_cantforward); return; } /* No IPsec processing required */ } #endif /* * ip6_forward() operates with IPv6 addresses with deembedded scope. * * There are 3 sources of IPv6 destination address: * * 1) ip6_input(), where ip6_dst contains deembedded address. * In order to deal with forwarding of link-local packets, * calculate the scope based on input interface (RFC 4007, clause 9). * 2) packet filters changing ip6_dst directly. It would embed scope * for LL addresses, so in6_localip() performs properly. * 3) packet filters attaching PACKET_TAG_IPFORWARD would embed * scope for the nexthop. */ bzero(&dst, sizeof(struct sockaddr_in6)); dst.sin6_family = AF_INET6; dst.sin6_addr = ip6->ip6_dst; dst.sin6_scope_id = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif); again: nh = fib6_lookup(M_GETFIB(m), &dst.sin6_addr, dst.sin6_scope_id, NHR_REF, m->m_pkthdr.flowid); if (nh == NULL) { IP6STAT_INC(ip6s_noroute); in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); if (mcopy) { icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE, 0); } goto bad; } if (nh->nh_flags & (NHF_BLACKHOLE | NHF_REJECT)) { IP6STAT_INC(ip6s_cantforward); if ((nh->nh_flags & NHF_REJECT) && (mcopy != NULL)) { icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_REJECT, 0); } goto bad; } /* * Source 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-v3-04.txt, Section 3.1] */ outzone = in6_get_unicast_scopeid(&ip6->ip6_src, nh->nh_ifp); inzone = in6_get_unicast_scopeid(&ip6->ip6_src, m->m_pkthdr.rcvif); if (inzone != outzone) { IP6STAT_INC(ip6s_cantforward); IP6STAT_INC(ip6s_badscope); in6_ifstat_inc(nh->nh_ifp, ifs6_in_discard); if (V_ip6_log_cannot_forward && ip6_log_ratelimit()) { log(LOG_DEBUG, "cannot forward " "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", ip6_sprintf(ip6bufs, &ip6->ip6_src), ip6_sprintf(ip6bufd, &ip6->ip6_dst), ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), if_name(nh->nh_ifp)); } if (mcopy) icmp6_error(mcopy, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_BEYONDSCOPE, 0); goto bad; } /* * Destination scope check: if a packet is going to break the scope * zone of packet's destination address, discard it. This case should * usually be prevented by appropriately-configured routing table, but * we need an explicit check because we may mistakenly forward the * packet to a different zone by (e.g.) a default route. */ inzone = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif); outzone = in6_get_unicast_scopeid(&ip6->ip6_dst, nh->nh_ifp); if (inzone != outzone) { IP6STAT_INC(ip6s_cantforward); IP6STAT_INC(ip6s_badscope); goto bad; } if (nh->nh_flags & NHF_GATEWAY) { /* Store gateway address in deembedded form */ dst.sin6_addr = nh->gw6_sa.sin6_addr; dst.sin6_scope_id = ntohs(in6_getscope(&dst.sin6_addr)); in6_clearscope(&dst.sin6_addr); } /* * 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 (V_ip6_sendredirects && nh->nh_ifp == m->m_pkthdr.rcvif && !srcrt && (nh->nh_flags & NHF_REDIRECT) == 0) 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 ((nh->nh_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(ip6bufs, &ip6->ip6_src), ip6_sprintf(ip6bufd, &ip6->ip6_dst), ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), if_name(nh->nh_ifp)); } /* we can just use rcvif in forwarding. */ origifp = m->m_pkthdr.rcvif; } else origifp = nh->nh_ifp; /* * clear embedded scope identifiers if necessary. * in6_clearscope will touch the addresses only when necessary. */ in6_clearscope(&ip6->ip6_src); in6_clearscope(&ip6->ip6_dst); /* Jump over all PFIL processing if hooks are not active. */ if (!PFIL_HOOKED_OUT(V_inet6_pfil_head)) goto pass; odst = ip6->ip6_dst; /* Run through list of hooks for forwarded packets. */ if (pfil_mbuf_out(V_inet6_pfil_head, &m, nh->nh_ifp, NULL) != PFIL_PASS) goto freecopy; ip6 = mtod(m, struct ip6_hdr *); /* See if destination IP address was changed by packet filter. */ if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) { m->m_flags |= M_SKIP_FIREWALL; /* If destination is now ourself drop to ip6_input(). */ if (in6_localip(&ip6->ip6_dst)) m->m_flags |= M_FASTFWD_OURS; else { NH_FREE(nh); /* Update address and scopeid. Assume scope is embedded */ dst.sin6_scope_id = ntohs(in6_getscope(&ip6->ip6_dst)); dst.sin6_addr = ip6->ip6_dst; in6_clearscope(&dst.sin6_addr); goto again; /* Redo the routing table lookup. */ } } /* See if local, if yes, send it to netisr. */ if (m->m_flags & M_FASTFWD_OURS) { if (m->m_pkthdr.rcvif == NULL) m->m_pkthdr.rcvif = V_loif; if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) { m->m_pkthdr.csum_flags |= CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR; m->m_pkthdr.csum_data = 0xffff; } #if defined(SCTP) || defined(SCTP_SUPPORT) if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID; #endif error = netisr_queue(NETISR_IPV6, m); goto out; } /* Or forward to some other address? */ if ((m->m_flags & M_IP6_NEXTHOP) && (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) { struct sockaddr_in6 *gw6 = (struct sockaddr_in6 *)(fwd_tag + 1); /* Update address and scopeid. Assume scope is embedded */ dst.sin6_scope_id = ntohs(in6_getscope(&gw6->sin6_addr)); dst.sin6_addr = gw6->sin6_addr; in6_clearscope(&dst.sin6_addr); m->m_flags |= M_SKIP_FIREWALL; m->m_flags &= ~M_IP6_NEXTHOP; m_tag_delete(m, fwd_tag); NH_FREE(nh); goto again; } pass: /* See if the size was changed by the packet filter. */ /* TODO: change to nh->nh_mtu */ if (m->m_pkthdr.len > IN6_LINKMTU(nh->nh_ifp)) { in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig); if (mcopy) icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, IN6_LINKMTU(nh->nh_ifp)); goto bad; } /* Currently LLE layer stores embedded IPv6 addresses */ if (IN6_IS_SCOPE_LINKLOCAL(&dst.sin6_addr)) { in6_set_unicast_scopeid(&dst.sin6_addr, dst.sin6_scope_id); dst.sin6_scope_id = 0; } error = nd6_output_ifp(nh->nh_ifp, origifp, m, &dst, NULL); if (error) { in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard); IP6STAT_INC(ip6s_cantforward); } else { IP6STAT_INC(ip6s_forward); in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward); if (type) IP6STAT_INC(ip6s_redirectsent); else { if (mcopy) goto freecopy; } } if (mcopy == NULL) goto out; switch (error) { case 0: if (type == ND_REDIRECT) { icmp6_redirect_output(mcopy, nh); goto out; } 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 out; freecopy: m_freem(mcopy); goto out; bad: m_freem(m); out: if (nh != NULL) NH_FREE(nh); }