1 /* $FreeBSD: src/sys/netinet6/ip6_forward.c,v 1.4.2.7 2003/01/24 05:11:35 sam Exp $ */
2 /* $DragonFly: src/sys/netinet6/ip6_forward.c,v 1.6 2003/12/02 08:00:22 asmodai Exp $ */
3 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include "opt_ip6fw.h"
36 #include "opt_inet6.h"
37 #include "opt_ipsec.h"
38 #include "opt_pfil_hooks.h"
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/malloc.h>
44 #include <sys/domain.h>
45 #include <sys/protosw.h>
46 #include <sys/socket.h>
47 #include <sys/errno.h>
49 #include <sys/kernel.h>
50 #include <sys/syslog.h>
53 #include <net/route.h>
58 #include <netinet/in.h>
59 #include <netinet/in_var.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/ip.h>
62 #include <netinet/ip_var.h>
63 #include <netinet6/in6_var.h>
64 #include <netinet/ip6.h>
65 #include <netinet6/ip6_var.h>
66 #include <netinet/icmp6.h>
67 #include <netinet6/nd6.h>
69 #include <netinet/in_pcb.h>
72 #include <netinet6/ipsec.h>
74 #include <netinet6/ipsec6.h>
76 #include <netproto/key/key.h>
82 #include <netipsec/key.h>
84 #endif /* FAST_IPSEC */
86 #include <net/ip6fw/ip6_fw.h>
88 #include <net/net_osdep.h>
90 struct route_in6 ip6_forward_rt;
93 * Forward a packet. If some error occurs return the sender
94 * an icmp packet. Note we can't always generate a meaningful
95 * icmp message because icmp doesn't have a large enough repertoire
98 * If not forwarding, just drop the packet. This could be confusing
99 * if ipforwarding was zero but some routing protocol was advancing
100 * us as a gateway to somewhere. However, we must let the routing
101 * protocol deal with that.
106 ip6_forward(m, srcrt)
110 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
111 struct sockaddr_in6 *dst;
113 int error, type = 0, code = 0;
114 struct mbuf *mcopy = NULL;
115 struct ifnet *origifp; /* maybe unnecessary */
117 struct secpolicy *sp = NULL;
122 * Check AH/ESP integrity.
125 * Don't increment ip6s_cantforward because this is the check
126 * before forwarding packet actually.
128 if (ipsec6_in_reject(m, NULL)) {
129 #if !defined(FAST_IPSEC)
130 ipsec6stat.in_polvio++;
138 * Do not forward packets to multicast destination (should be handled
140 * Do not forward packets with unspecified source. It was discussed
141 * in July 2000, on ipngwg mailing list.
143 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
144 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
145 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
146 ip6stat.ip6s_cantforward++;
147 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
148 if (ip6_log_time + ip6_log_interval < time_second) {
149 ip6_log_time = time_second;
152 "from %s to %s nxt %d received on %s\n",
153 ip6_sprintf(&ip6->ip6_src),
154 ip6_sprintf(&ip6->ip6_dst),
156 if_name(m->m_pkthdr.rcvif));
162 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
163 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
164 icmp6_error(m, ICMP6_TIME_EXCEEDED,
165 ICMP6_TIME_EXCEED_TRANSIT, 0);
168 ip6->ip6_hlim -= IPV6_HLIMDEC;
171 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
172 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
173 * we need to generate an ICMP6 message to the src.
174 * Thanks to M_EXT, in most cases copy will not occur.
176 * It is important to save it before IPsec processing as IPsec
177 * processing may modify the mbuf.
179 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
182 /* get a security policy for this packet */
183 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
186 ipsec6stat.out_inval++;
187 ip6stat.ip6s_cantforward++;
190 /* XXX: what icmp ? */
202 switch (sp->policy) {
203 case IPSEC_POLICY_DISCARD:
205 * This packet is just discarded.
207 ipsec6stat.out_polvio++;
208 ip6stat.ip6s_cantforward++;
212 /* XXX: what icmp ? */
220 case IPSEC_POLICY_BYPASS:
221 case IPSEC_POLICY_NONE:
222 /* no need to do IPsec. */
226 case IPSEC_POLICY_IPSEC:
227 if (sp->req == NULL) {
228 /* XXX should be panic ? */
229 printf("ip6_forward: No IPsec request specified.\n");
230 ip6stat.ip6s_cantforward++;
234 /* XXX: what icmp ? */
245 case IPSEC_POLICY_ENTRUST:
247 /* should be panic ?? */
248 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
254 struct ipsec_output_state state;
257 * All the extension headers will become inaccessible
258 * (since they can be encrypted).
259 * Don't panic, we need no more updates to extension headers
260 * on inner IPv6 packet (since they are now encapsulated).
262 * IPv6 [ESP|AH] IPv6 [extension headers] payload
264 bzero(&state, sizeof(state));
266 state.ro = NULL; /* update at ipsec6_output_tunnel() */
267 state.dst = NULL; /* update at ipsec6_output_tunnel() */
269 error = ipsec6_output_tunnel(&state, sp, 0);
275 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
284 printf("ip6_output (ipsec): error code %d\n", error);
287 /* don't show these error codes to the user */
290 ip6stat.ip6s_cantforward++;
293 /* XXX: what icmp ? */
305 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
308 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
310 if (ip6_forward_rt.ro_rt == 0 ||
311 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
312 if (ip6_forward_rt.ro_rt) {
313 RTFREE(ip6_forward_rt.ro_rt);
314 ip6_forward_rt.ro_rt = 0;
316 /* this probably fails but give it a try again */
317 rtalloc_ign((struct route *)&ip6_forward_rt,
321 if (ip6_forward_rt.ro_rt == 0) {
322 ip6stat.ip6s_noroute++;
323 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
325 icmp6_error(mcopy, ICMP6_DST_UNREACH,
326 ICMP6_DST_UNREACH_NOROUTE, 0);
331 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
332 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
333 if (ip6_forward_rt.ro_rt) {
334 RTFREE(ip6_forward_rt.ro_rt);
335 ip6_forward_rt.ro_rt = 0;
337 bzero(dst, sizeof(*dst));
338 dst->sin6_len = sizeof(struct sockaddr_in6);
339 dst->sin6_family = AF_INET6;
340 dst->sin6_addr = ip6->ip6_dst;
342 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
343 if (ip6_forward_rt.ro_rt == 0) {
344 ip6stat.ip6s_noroute++;
345 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
347 icmp6_error(mcopy, ICMP6_DST_UNREACH,
348 ICMP6_DST_UNREACH_NOROUTE, 0);
354 rt = ip6_forward_rt.ro_rt;
357 * Scope check: if a packet can't be delivered to its destination
358 * for the reason that the destination is beyond the scope of the
359 * source address, discard the packet and return an icmp6 destination
360 * unreachable error with Code 2 (beyond scope of source address).
361 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
363 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
364 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
365 ip6stat.ip6s_cantforward++;
366 ip6stat.ip6s_badscope++;
367 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
369 if (ip6_log_time + ip6_log_interval < time_second) {
370 ip6_log_time = time_second;
373 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
374 ip6_sprintf(&ip6->ip6_src),
375 ip6_sprintf(&ip6->ip6_dst),
377 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
380 icmp6_error(mcopy, ICMP6_DST_UNREACH,
381 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
386 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
387 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
391 struct secpolicy *sp;
396 mtu = rt->rt_ifp->if_mtu;
399 * When we do IPsec tunnel ingress, we need to play
400 * with if_mtu value (decrement IPsec header size
401 * from mtu value). The code is much simpler than v4
402 * case, as we have the outgoing interface for
403 * encapsulated packet as "rt->rt_ifp".
405 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
406 IP_FORWARDING, &ipsecerror);
408 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
409 IPSEC_DIR_OUTBOUND, NULL);
410 if (ipsechdrsiz < mtu)
415 * if mtu becomes less than minimum MTU,
416 * tell minimum MTU (and I'll need to fragment it).
421 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
427 if (rt->rt_flags & RTF_GATEWAY)
428 dst = (struct sockaddr_in6 *)rt->rt_gateway;
431 * If we are to forward the packet using the same interface
432 * as one we got the packet from, perhaps we should send a redirect
433 * to sender to shortcut a hop.
434 * Only send redirect if source is sending directly to us,
435 * and if packet was not source routed (or has any options).
436 * Also, don't send redirect if forwarding using a route
437 * modified by a redirect.
439 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
440 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
441 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
443 * If the incoming interface is equal to the outgoing
444 * one, and the link attached to the interface is
445 * point-to-point, then it will be highly probable
446 * that a routing loop occurs. Thus, we immediately
447 * drop the packet and send an ICMPv6 error message.
449 * type/code is based on suggestion by Rich Draves.
450 * not sure if it is the best pick.
452 icmp6_error(mcopy, ICMP6_DST_UNREACH,
453 ICMP6_DST_UNREACH_ADDR, 0);
461 * Check with the firewall...
463 if (ip6_fw_enable && ip6_fw_chk_ptr) {
465 /* If ipfw says divert, we have to just drop packet */
466 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
475 * Fake scoped addresses. Note that even link-local source or
476 * destinaion can appear, if the originating node just sends the
477 * packet to us (without address resolution for the destination).
478 * Since both icmp6_error and icmp6_redirect_output fill the embedded
479 * link identifiers, we can do this stuff after making a copy for
480 * returning an error.
482 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
484 * See corresponding comments in ip6_output.
485 * XXX: but is it possible that ip6_forward() sends a packet
486 * to a loopback interface? I don't think so, and thus
487 * I bark here. (jinmei@kame.net)
488 * XXX: it is common to route invalid packets to loopback.
489 * also, the codepath will be visited on use of ::1 in
495 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
498 printf("ip6_forward: outgoing interface is loopback. "
499 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
500 ip6_sprintf(&ip6->ip6_src),
501 ip6_sprintf(&ip6->ip6_dst),
502 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
503 if_name(rt->rt_ifp));
506 /* we can just use rcvif in forwarding. */
507 origifp = m->m_pkthdr.rcvif;
510 origifp = rt->rt_ifp;
511 #ifndef SCOPEDROUTING
513 * clear embedded scope identifiers if necessary.
514 * in6_clearscope will touch the addresses only when necessary.
516 in6_clearscope(&ip6->ip6_src);
517 in6_clearscope(&ip6->ip6_dst);
522 * Run through list of hooks for output packets.
524 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT);
529 ip6 = mtod(m, struct ip6_hdr *);
530 #endif /* PFIL_HOOKS */
532 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
534 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
535 ip6stat.ip6s_cantforward++;
537 ip6stat.ip6s_forward++;
538 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
540 ip6stat.ip6s_redirectsent++;
554 if (type == ND_REDIRECT) {
555 icmp6_redirect_output(mcopy, rt);
562 /* xxx MTU is constant in PPP? */
566 /* Tell source to slow down like source quench in IP? */
569 case ENETUNREACH: /* shouldn't happen, checked above */
574 type = ICMP6_DST_UNREACH;
575 code = ICMP6_DST_UNREACH_ADDR;
578 icmp6_error(mcopy, type, code, 0);