2 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 #include "opt_ip6fw.h"
35 #include "opt_inet6.h"
36 #include "opt_ipsec.h"
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/malloc.h>
42 #include <sys/domain.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
45 #include <sys/errno.h>
47 #include <sys/kernel.h>
48 #include <sys/syslog.h>
51 #include <net/route.h>
56 #include <netinet/in.h>
57 #include <netinet/in_var.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/ip.h>
60 #include <netinet/ip_var.h>
61 #include <netinet6/in6_var.h>
62 #include <netinet/ip6.h>
63 #include <netinet6/ip6_var.h>
64 #include <netinet/icmp6.h>
65 #include <netinet6/nd6.h>
67 #include <netinet/in_pcb.h>
70 #include <netinet6/ipsec.h>
72 #include <netinet6/ipsec6.h>
74 #include <netkey/key.h>
77 #include <netinet6/ip6_fw.h>
79 #include <net/net_osdep.h>
81 #include <netinet6/ip6protosw.h>
83 struct route_in6 ip6_forward_rt;
86 * Forward a packet. If some error occurs return the sender
87 * an icmp packet. Note we can't always generate a meaningful
88 * icmp message because icmp doesn't have a large enough repertoire
91 * If not forwarding, just drop the packet. This could be confusing
92 * if ipforwarding was zero but some routing protocol was advancing
93 * us as a gateway to somewhere. However, we must let the routing
94 * protocol deal with that.
103 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
104 struct sockaddr_in6 *dst;
106 int error, type = 0, code = 0;
107 struct mbuf *mcopy = NULL;
108 struct ifnet *origifp; /* maybe unnecessary */
110 struct packet_filter_hook *pfh;
113 #endif /* PFIL_HOOKS */
115 struct secpolicy *sp = NULL;
120 * Check AH/ESP integrity.
123 * Don't increment ip6s_cantforward because this is the check
124 * before forwarding packet actually.
126 if (ipsec6_in_reject(m, NULL)) {
127 ipsec6stat.in_polvio++;
134 * Do not forward packets to multicast destination (should be handled
136 * Do not forward packets with unspecified source. It was discussed
137 * in July 2000, on ipngwg mailing list.
139 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
140 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
141 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
142 ip6stat.ip6s_cantforward++;
143 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
144 if (ip6_log_time + ip6_log_interval < time_second) {
145 ip6_log_time = time_second;
148 "from %s to %s nxt %d received on %s\n",
149 ip6_sprintf(&ip6->ip6_src),
150 ip6_sprintf(&ip6->ip6_dst),
152 if_name(m->m_pkthdr.rcvif));
158 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
159 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
160 icmp6_error(m, ICMP6_TIME_EXCEEDED,
161 ICMP6_TIME_EXCEED_TRANSIT, 0);
164 ip6->ip6_hlim -= IPV6_HLIMDEC;
167 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
168 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
169 * we need to generate an ICMP6 message to the src.
170 * Thanks to M_EXT, in most cases copy will not occur.
172 * It is important to save it before IPsec processing as IPsec
173 * processing may modify the mbuf.
175 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
178 /* get a security policy for this packet */
179 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
182 ipsec6stat.out_inval++;
183 ip6stat.ip6s_cantforward++;
186 /* XXX: what icmp ? */
198 switch (sp->policy) {
199 case IPSEC_POLICY_DISCARD:
201 * This packet is just discarded.
203 ipsec6stat.out_polvio++;
204 ip6stat.ip6s_cantforward++;
208 /* XXX: what icmp ? */
216 case IPSEC_POLICY_BYPASS:
217 case IPSEC_POLICY_NONE:
218 /* no need to do IPsec. */
222 case IPSEC_POLICY_IPSEC:
223 if (sp->req == NULL) {
224 /* XXX should be panic ? */
225 printf("ip6_forward: No IPsec request specified.\n");
226 ip6stat.ip6s_cantforward++;
230 /* XXX: what icmp ? */
241 case IPSEC_POLICY_ENTRUST:
243 /* should be panic ?? */
244 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
250 struct ipsec_output_state state;
253 * All the extension headers will become inaccessible
254 * (since they can be encrypted).
255 * Don't panic, we need no more updates to extension headers
256 * on inner IPv6 packet (since they are now encapsulated).
258 * IPv6 [ESP|AH] IPv6 [extension headers] payload
260 bzero(&state, sizeof(state));
262 state.ro = NULL; /* update at ipsec6_output_tunnel() */
263 state.dst = NULL; /* update at ipsec6_output_tunnel() */
265 error = ipsec6_output_tunnel(&state, sp, 0);
271 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
280 printf("ip6_output (ipsec): error code %d\n", error);
283 /* don't show these error codes to the user */
286 ip6stat.ip6s_cantforward++;
289 /* XXX: what icmp ? */
301 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
304 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
306 if (ip6_forward_rt.ro_rt == 0 ||
307 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
308 if (ip6_forward_rt.ro_rt) {
309 RTFREE(ip6_forward_rt.ro_rt);
310 ip6_forward_rt.ro_rt = 0;
312 /* this probably fails but give it a try again */
313 rtalloc_ign((struct route *)&ip6_forward_rt,
317 if (ip6_forward_rt.ro_rt == 0) {
318 ip6stat.ip6s_noroute++;
319 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
321 icmp6_error(mcopy, ICMP6_DST_UNREACH,
322 ICMP6_DST_UNREACH_NOROUTE, 0);
327 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
328 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
329 if (ip6_forward_rt.ro_rt) {
330 RTFREE(ip6_forward_rt.ro_rt);
331 ip6_forward_rt.ro_rt = 0;
333 bzero(dst, sizeof(*dst));
334 dst->sin6_len = sizeof(struct sockaddr_in6);
335 dst->sin6_family = AF_INET6;
336 dst->sin6_addr = ip6->ip6_dst;
338 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
339 if (ip6_forward_rt.ro_rt == 0) {
340 ip6stat.ip6s_noroute++;
341 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
343 icmp6_error(mcopy, ICMP6_DST_UNREACH,
344 ICMP6_DST_UNREACH_NOROUTE, 0);
350 rt = ip6_forward_rt.ro_rt;
353 * Scope check: if a packet can't be delivered to its destination
354 * for the reason that the destination is beyond the scope of the
355 * source address, discard the packet and return an icmp6 destination
356 * unreachable error with Code 2 (beyond scope of source address).
357 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1]
359 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
360 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
361 ip6stat.ip6s_cantforward++;
362 ip6stat.ip6s_badscope++;
363 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
365 if (ip6_log_time + ip6_log_interval < time_second) {
366 ip6_log_time = time_second;
369 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
370 ip6_sprintf(&ip6->ip6_src),
371 ip6_sprintf(&ip6->ip6_dst),
373 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
376 icmp6_error(mcopy, ICMP6_DST_UNREACH,
377 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
382 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
383 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
387 struct secpolicy *sp;
392 mtu = rt->rt_ifp->if_mtu;
395 * When we do IPsec tunnel ingress, we need to play
396 * with if_mtu value (decrement IPsec header size
397 * from mtu value). The code is much simpler than v4
398 * case, as we have the outgoing interface for
399 * encapsulated packet as "rt->rt_ifp".
401 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
402 IP_FORWARDING, &ipsecerror);
404 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
405 IPSEC_DIR_OUTBOUND, NULL);
406 if (ipsechdrsiz < mtu)
411 * if mtu becomes less than minimum MTU,
412 * tell minimum MTU (and I'll need to fragment it).
417 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
423 if (rt->rt_flags & RTF_GATEWAY)
424 dst = (struct sockaddr_in6 *)rt->rt_gateway;
427 * If we are to forward the packet using the same interface
428 * as one we got the packet from, perhaps we should send a redirect
429 * to sender to shortcut a hop.
430 * Only send redirect if source is sending directly to us,
431 * and if packet was not source routed (or has any options).
432 * Also, don't send redirect if forwarding using a route
433 * modified by a redirect.
435 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
436 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
437 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
439 * If the incoming interface is equal to the outgoing
440 * one, and the link attached to the interface is
441 * point-to-point, then it will be highly probable
442 * that a routing loop occurs. Thus, we immediately
443 * drop the packet and send an ICMPv6 error message.
445 * type/code is based on suggestion by Rich Draves.
446 * not sure if it is the best pick.
448 icmp6_error(mcopy, ICMP6_DST_UNREACH,
449 ICMP6_DST_UNREACH_ADDR, 0);
457 * Check with the firewall...
459 if (ip6_fw_enable && ip6_fw_chk_ptr) {
461 /* If ipfw says divert, we have to just drop packet */
462 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
471 * Fake scoped addresses. Note that even link-local source or
472 * destinaion can appear, if the originating node just sends the
473 * packet to us (without address resolution for the destination).
474 * Since both icmp6_error and icmp6_redirect_output fill the embedded
475 * link identifiers, we can do this stuff after making a copy for
476 * returning an error.
478 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
480 * See corresponding comments in ip6_output.
481 * XXX: but is it possible that ip6_forward() sends a packet
482 * to a loopback interface? I don't think so, and thus
483 * I bark here. (jinmei@kame.net)
484 * XXX: it is common to route invalid packets to loopback.
485 * also, the codepath will be visited on use of ::1 in
491 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
494 printf("ip6_forward: outgoing interface is loopback. "
495 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
496 ip6_sprintf(&ip6->ip6_src),
497 ip6_sprintf(&ip6->ip6_dst),
498 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
499 if_name(rt->rt_ifp));
502 /* we can just use rcvif in forwarding. */
503 origifp = m->m_pkthdr.rcvif;
506 origifp = rt->rt_ifp;
507 #ifndef SCOPEDROUTING
509 * clear embedded scope identifiers if necessary.
510 * in6_clearscope will touch the addresses only when necessary.
512 in6_clearscope(&ip6->ip6_src);
513 in6_clearscope(&ip6->ip6_dst);
518 * Run through list of hooks for output packets.
521 pfh = pfil_hook_get(PFIL_OUT, &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh);
522 for (; pfh; pfh = pfh->pfil_link.tqe_next)
523 if (pfh->pfil_func) {
524 rv = pfh->pfil_func(ip6, sizeof(*ip6),
527 error = EHOSTUNREACH;
533 ip6 = mtod(m, struct ip6_hdr *);
535 #endif /* PFIL_HOOKS */
537 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
539 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
540 ip6stat.ip6s_cantforward++;
542 ip6stat.ip6s_forward++;
543 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
545 ip6stat.ip6s_redirectsent++;
557 if (type == ND_REDIRECT) {
558 icmp6_redirect_output(mcopy, rt);
565 /* xxx MTU is constant in PPP? */
569 /* Tell source to slow down like source quench in IP? */
572 case ENETUNREACH: /* shouldn't happen, checked above */
577 type = ICMP6_DST_UNREACH;
578 code = ICMP6_DST_UNREACH_ADDR;
581 icmp6_error(mcopy, type, code, 0);