diff options
Diffstat (limited to 'sys/netinet6/ip6_forward.c')
| -rw-r--r-- | sys/netinet6/ip6_forward.c | 595 |
1 files changed, 595 insertions, 0 deletions
diff --git a/sys/netinet6/ip6_forward.c b/sys/netinet6/ip6_forward.c new file mode 100644 index 0000000..1e6dde8 --- /dev/null +++ b/sys/netinet6/ip6_forward.c @@ -0,0 +1,595 @@ +/* $FreeBSD$ */ +/* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun 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 "opt_ip6fw.h" +#include "opt_inet.h" +#include "opt_inet6.h" +#include "opt_ipsec.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/domain.h> +#include <sys/protosw.h> +#include <sys/socket.h> +#include <sys/errno.h> +#include <sys/time.h> +#include <sys/kernel.h> +#include <sys/syslog.h> + +#include <net/if.h> +#include <net/route.h> +#ifdef PFIL_HOOKS +#include <net/pfil.h> +#endif + +#include <netinet/in.h> +#include <netinet/in_var.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet6/in6_var.h> +#include <netinet/ip6.h> +#include <netinet6/ip6_var.h> +#include <netinet/icmp6.h> +#include <netinet6/nd6.h> + +#include <netinet/in_pcb.h> + +#ifdef IPSEC +#include <netinet6/ipsec.h> +#ifdef INET6 +#include <netinet6/ipsec6.h> +#endif +#include <netkey/key.h> +#endif /* IPSEC */ + +#ifdef FAST_IPSEC +#include <netipsec/ipsec.h> +#include <netipsec/ipsec6.h> +#include <netipsec/key.h> +#define IPSEC +#endif /* FAST_IPSEC */ + +#include <netinet6/ip6_fw.h> + +#include <net/net_osdep.h> + +#include <netinet6/ip6protosw.h> + +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(m, srcrt) + struct mbuf *m; + int srcrt; +{ + struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); + struct sockaddr_in6 *dst; + struct rtentry *rt; + int error, type = 0, code = 0; + struct mbuf *mcopy = NULL; + struct ifnet *origifp; /* maybe unnecessary */ +#ifdef PFIL_HOOKS + struct packet_filter_hook *pfh; + struct mbuf *m1; + int rv; +#endif /* PFIL_HOOKS */ +#ifdef IPSEC + struct secpolicy *sp = NULL; +#endif + +#ifdef IPSEC + /* + * Check AH/ESP integrity. + */ + /* + * Don't increment ip6s_cantforward because this is the check + * before forwarding packet actually. + */ + if (ipsec6_in_reject(m, NULL)) { +#if !defined(FAST_IPSEC) + ipsec6stat.in_polvio++; +#endif + m_freem(m); + return; + } +#endif /* IPSEC */ + + /* + * 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, + if_name(m->m_pkthdr.rcvif)); + } + 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; + + /* + * 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)); + +#ifdef IPSEC + /* get a security policy for this packet */ + sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING, + &error); + if (sp == NULL) { + ipsec6stat.out_inval++; + ip6stat.ip6s_cantforward++; + if (mcopy) { +#if 0 + /* XXX: what icmp ? */ +#else + m_freem(mcopy); +#endif + } + m_freem(m); + return; + } + + error = 0; + + /* check policy */ + switch (sp->policy) { + case IPSEC_POLICY_DISCARD: + /* + * This packet is just discarded. + */ + ipsec6stat.out_polvio++; + ip6stat.ip6s_cantforward++; + key_freesp(sp); + if (mcopy) { +#if 0 + /* XXX: what icmp ? */ +#else + m_freem(mcopy); +#endif + } + m_freem(m); + return; + + case IPSEC_POLICY_BYPASS: + case IPSEC_POLICY_NONE: + /* no need to do IPsec. */ + key_freesp(sp); + goto skip_ipsec; + + case IPSEC_POLICY_IPSEC: + if (sp->req == NULL) { + /* XXX should be panic ? */ + printf("ip6_forward: No IPsec request specified.\n"); + ip6stat.ip6s_cantforward++; + key_freesp(sp); + if (mcopy) { +#if 0 + /* XXX: what icmp ? */ +#else + m_freem(mcopy); +#endif + } + m_freem(m); + return; + } + /* do IPsec */ + break; + + case IPSEC_POLICY_ENTRUST: + default: + /* should be panic ?? */ + printf("ip6_forward: Invalid policy found. %d\n", sp->policy); + key_freesp(sp); + goto skip_ipsec; + } + + { + struct ipsec_output_state state; + + /* + * All the extension headers will become inaccessible + * (since they can be encrypted). + * Don't panic, we need no more updates to extension headers + * on inner IPv6 packet (since they are now encapsulated). + * + * IPv6 [ESP|AH] IPv6 [extension headers] payload + */ + bzero(&state, sizeof(state)); + state.m = m; + state.ro = NULL; /* update at ipsec6_output_tunnel() */ + state.dst = NULL; /* update at ipsec6_output_tunnel() */ + + error = ipsec6_output_tunnel(&state, sp, 0); + + m = state.m; + key_freesp(sp); + + if (error) { + /* mbuf is already reclaimed in ipsec6_output_tunnel. */ + switch (error) { + case EHOSTUNREACH: + case ENETUNREACH: + case EMSGSIZE: + case ENOBUFS: + case ENOMEM: + break; + default: + printf("ip6_output (ipsec): error code %d\n", error); + /* fall through */ + case ENOENT: + /* don't show these error codes to the user */ + break; + } + ip6stat.ip6s_cantforward++; + if (mcopy) { +#if 0 + /* XXX: what icmp ? */ +#else + m_freem(mcopy); +#endif + } + m_freem(m); + return; + } + } + skip_ipsec: +#endif /* IPSEC */ + + dst = (struct sockaddr_in6 *)&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) { + 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 */ + rtalloc_ign((struct route *)&ip6_forward_rt, + RTF_PRCLONING); + } + + if (ip6_forward_rt.ro_rt == 0) { + ip6stat.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); + } + m_freem(m); + return; + } + } else if ((rt = ip6_forward_rt.ro_rt) == 0 || + !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { + 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; + + rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); + if (ip6_forward_rt.ro_rt == 0) { + ip6stat.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); + } + 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-v3-02.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, + if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); + } + if (mcopy) + icmp6_error(mcopy, ICMP6_DST_UNREACH, + ICMP6_DST_UNREACH_BEYONDSCOPE, 0); + m_freem(m); + return; + } + + if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { + in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); + if (mcopy) { + u_long mtu; +#ifdef IPSEC + struct secpolicy *sp; + int ipsecerror; + size_t ipsechdrsiz; +#endif + + mtu = rt->rt_ifp->if_mtu; +#ifdef IPSEC + /* + * When we do IPsec tunnel ingress, we need to play + * with if_mtu value (decrement IPsec header size + * from mtu value). The code is much simpler than v4 + * case, as we have the outgoing interface for + * encapsulated packet as "rt->rt_ifp". + */ + sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, + IP_FORWARDING, &ipsecerror); + if (sp) { + ipsechdrsiz = ipsec6_hdrsiz(mcopy, + IPSEC_DIR_OUTBOUND, NULL); + if (ipsechdrsiz < mtu) + mtu -= ipsechdrsiz; + } + + /* + * if mtu becomes less than minimum MTU, + * tell minimum MTU (and I'll need to fragment it). + */ + if (mtu < IPV6_MMTU) + mtu = IPV6_MMTU; +#endif + icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); + } + m_freem(m); + return; + } + + 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 && + (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { + if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { + /* + * If the incoming interface is equal to the outgoing + * one, and the link attached to the interface is + * point-to-point, then it will be highly probable + * that a routing loop occurs. Thus, we immediately + * drop the packet and send an ICMPv6 error message. + * + * type/code is based on suggestion by Rich Draves. + * not sure if it is the best pick. + */ + icmp6_error(mcopy, ICMP6_DST_UNREACH, + ICMP6_DST_UNREACH_ADDR, 0); + m_freem(m); + return; + } + type = ND_REDIRECT; + } + + /* + * Check with the firewall... + */ + if (ip6_fw_enable && ip6_fw_chk_ptr) { + u_short port = 0; + /* If ipfw says divert, we have to just drop packet */ + if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { + m_freem(m); + goto freecopy; + } + if (!m) + goto freecopy; + } + + /* + * 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, if_name(m->m_pkthdr.rcvif), + if_name(rt->rt_ifp)); + } + + /* we can just use rcvif in forwarding. */ + origifp = m->m_pkthdr.rcvif; + } + else + origifp = rt->rt_ifp; +#ifndef SCOPEDROUTING + /* + * 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); +#endif + +#ifdef PFIL_HOOKS + /* + * Run through list of hooks for output packets. + */ + m1 = m; + pfh = pfil_hook_get(PFIL_OUT, &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh); + for (; pfh; pfh = pfh->pfil_link.tqe_next) + if (pfh->pfil_func) { + rv = pfh->pfil_func(ip6, sizeof(*ip6), + rt->rt_ifp, 1, &m1); + if (rv) { + error = EHOSTUNREACH; + goto freecopy; + } + m = m1; + if (m == NULL) + goto freecopy; + ip6 = mtod(m, struct ip6_hdr *); + } +#endif /* PFIL_HOOKS */ + + 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 (mcopy == NULL) + return; + switch (error) { + case 0: +#if 1 + if (type == ND_REDIRECT) { + icmp6_redirect_output(mcopy, rt); + return; + } +#endif + 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); + return; + + freecopy: + m_freem(mcopy); + return; +} |
