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 1.13 2006/12/22 23:57:53 swildner 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"
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/malloc.h>
43 #include <sys/domain.h>
44 #include <sys/protosw.h>
45 #include <sys/socket.h>
46 #include <sys/errno.h>
48 #include <sys/kernel.h>
49 #include <sys/syslog.h>
52 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_var.h>
57 #include <netinet/in_systm.h>
58 #include <netinet/ip.h>
59 #include <netinet/ip_var.h>
60 #include <netinet6/in6_var.h>
61 #include <netinet/ip6.h>
62 #include <netinet6/ip6_var.h>
63 #include <netinet/icmp6.h>
64 #include <netinet6/nd6.h>
66 #include <netinet/in_pcb.h>
69 #include <netinet6/ipsec.h>
71 #include <netinet6/ipsec6.h>
73 #include <netproto/key/key.h>
77 #include <netproto/ipsec/ipsec.h>
78 #include <netproto/ipsec/ipsec6.h>
79 #include <netproto/ipsec/key.h>
81 #endif /* FAST_IPSEC */
83 #include <net/ip6fw/ip6_fw.h>
85 #include <net/net_osdep.h>
87 struct route_in6 ip6_forward_rt;
90 * Forward a packet. If some error occurs return the sender
91 * an icmp packet. Note we can't always generate a meaningful
92 * icmp message because icmp doesn't have a large enough repertoire
95 * If not forwarding, just drop the packet. This could be confusing
96 * if ipforwarding was zero but some routing protocol was advancing
97 * us as a gateway to somewhere. However, we must let the routing
98 * protocol deal with that.
103 ip6_forward(struct mbuf *m, int srcrt)
105 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
106 struct sockaddr_in6 *dst;
108 int error, type = 0, code = 0;
109 struct mbuf *mcopy = NULL;
110 struct ifnet *origifp; /* maybe unnecessary */
112 struct secpolicy *sp = NULL;
117 * Check AH/ESP integrity.
120 * Don't increment ip6s_cantforward because this is the check
121 * before forwarding packet actually.
123 if (ipsec6_in_reject(m, NULL)) {
124 #if !defined(FAST_IPSEC)
125 ipsec6stat.in_polvio++;
133 * Do not forward packets to multicast destination (should be handled
135 * Do not forward packets with unspecified source. It was discussed
136 * in July 2000, on the ipngwg mailing list.
138 if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 ||
139 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
140 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
141 ip6stat.ip6s_cantforward++;
142 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
143 if (ip6_log_time + ip6_log_interval < time_uptime) {
144 ip6_log_time = time_uptime;
147 "from %s to %s nxt %d received on %s\n",
148 ip6_sprintf(&ip6->ip6_src),
149 ip6_sprintf(&ip6->ip6_dst),
151 if_name(m->m_pkthdr.rcvif));
157 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
158 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
159 icmp6_error(m, ICMP6_TIME_EXCEEDED,
160 ICMP6_TIME_EXCEED_TRANSIT, 0);
163 ip6->ip6_hlim -= IPV6_HLIMDEC;
166 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
167 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
168 * we need to generate an ICMP6 message to the src.
169 * Thanks to M_EXT, in most cases copy will not occur.
171 * It is important to save it before IPsec processing as IPsec
172 * processing may modify the mbuf.
174 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
177 /* get a security policy for this packet */
178 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
181 ipsec6stat.out_inval++;
182 ip6stat.ip6s_cantforward++;
185 /* XXX: what icmp ? */
197 switch (sp->policy) {
198 case IPSEC_POLICY_DISCARD:
200 * This packet is just discarded.
202 ipsec6stat.out_polvio++;
203 ip6stat.ip6s_cantforward++;
207 /* XXX: what icmp ? */
215 case IPSEC_POLICY_BYPASS:
216 case IPSEC_POLICY_NONE:
217 /* no need to do IPsec. */
221 case IPSEC_POLICY_IPSEC:
222 if (sp->req == NULL) {
223 /* XXX should be panic ? */
224 kprintf("ip6_forward: No IPsec request specified.\n");
225 ip6stat.ip6s_cantforward++;
229 /* XXX: what icmp ? */
240 case IPSEC_POLICY_ENTRUST:
242 /* should be panic ?? */
243 kprintf("ip6_forward: Invalid policy found. %d\n", sp->policy);
249 struct ipsec_output_state state;
252 * All the extension headers will become inaccessible
253 * (since they can be encrypted).
254 * Don't panic, we need no more updates to extension headers
255 * on inner IPv6 packet (since they are now encapsulated).
257 * IPv6 [ESP|AH] IPv6 [extension headers] payload
259 bzero(&state, sizeof(state));
261 state.ro = NULL; /* update at ipsec6_output_tunnel() */
262 state.dst = NULL; /* update at ipsec6_output_tunnel() */
264 error = ipsec6_output_tunnel(&state, sp, 0);
270 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
279 kprintf("ip6_output (ipsec): error code %d\n", error);
282 /* don't show these error codes to the user */
285 ip6stat.ip6s_cantforward++;
288 /* XXX: what icmp ? */
300 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
302 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
303 if (ip6_forward_rt.ro_rt == NULL ||
304 !(ip6_forward_rt.ro_rt->rt_flags & RTF_UP)) {
305 if (ip6_forward_rt.ro_rt) {
306 RTFREE(ip6_forward_rt.ro_rt);
307 ip6_forward_rt.ro_rt = 0;
310 /* this probably fails but give it a try again */
311 rtalloc_ign((struct route *)&ip6_forward_rt,
315 if (ip6_forward_rt.ro_rt == NULL) {
316 ip6stat.ip6s_noroute++;
317 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
319 icmp6_error(mcopy, ICMP6_DST_UNREACH,
320 ICMP6_DST_UNREACH_NOROUTE, 0);
325 } else if ((rt = ip6_forward_rt.ro_rt) == NULL ||
326 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
327 if (ip6_forward_rt.ro_rt) {
328 RTFREE(ip6_forward_rt.ro_rt);
329 ip6_forward_rt.ro_rt = 0;
331 bzero(dst, sizeof(*dst));
332 dst->sin6_len = sizeof(struct sockaddr_in6);
333 dst->sin6_family = AF_INET6;
334 dst->sin6_addr = ip6->ip6_dst;
336 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
337 if (ip6_forward_rt.ro_rt == NULL) {
338 ip6stat.ip6s_noroute++;
339 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
341 icmp6_error(mcopy, ICMP6_DST_UNREACH,
342 ICMP6_DST_UNREACH_NOROUTE, 0);
348 rt = ip6_forward_rt.ro_rt;
351 * Scope check: if a packet can't be delivered to its destination
352 * for the reason that the destination is beyond the scope of the
353 * source address, discard the packet and return an icmp6 destination
354 * unreachable error with Code 2 (beyond scope of source address).
355 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
357 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
358 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
359 ip6stat.ip6s_cantforward++;
360 ip6stat.ip6s_badscope++;
361 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
363 if (ip6_log_time + ip6_log_interval < time_uptime) {
364 ip6_log_time = time_uptime;
367 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
368 ip6_sprintf(&ip6->ip6_src),
369 ip6_sprintf(&ip6->ip6_dst),
371 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
374 icmp6_error(mcopy, ICMP6_DST_UNREACH,
375 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
380 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
381 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
385 struct secpolicy *sp;
390 mtu = rt->rt_ifp->if_mtu;
393 * When we do IPsec tunnel ingress, we need to play
394 * with if_mtu value (decrement IPsec header size
395 * from mtu value). The code is much simpler than v4
396 * case, as we have the outgoing interface for
397 * encapsulated packet as "rt->rt_ifp".
399 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
400 IP_FORWARDING, &ipsecerror);
402 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
403 IPSEC_DIR_OUTBOUND, NULL);
404 if (ipsechdrsiz < mtu)
409 * if mtu becomes less than minimum MTU,
410 * tell minimum MTU (and I'll need to fragment it).
415 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
421 if (rt->rt_flags & RTF_GATEWAY)
422 dst = (struct sockaddr_in6 *)rt->rt_gateway;
425 * If we are to forward the packet using the same interface
426 * as one we got the packet from, perhaps we should send a redirect
427 * to sender to shortcut a hop.
428 * Only send redirect if source is sending directly to us,
429 * and if packet was not source routed (or has any options).
430 * Also, don't send redirect if forwarding using a route
431 * modified by a redirect.
433 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
434 (rt->rt_flags & (RTF_DYNAMIC | RTF_MODIFIED)) == 0) {
435 if (rt->rt_ifp->if_flags & IFF_POINTOPOINT) {
437 * If the incoming interface is equal to the outgoing
438 * one, and the link attached to the interface is
439 * point-to-point, then it will be highly probable
440 * that a routing loop occurs. Thus, we immediately
441 * drop the packet and send an ICMPv6 error message.
443 * type/code is based on suggestion by Rich Draves.
444 * not sure if it is the best pick.
446 icmp6_error(mcopy, ICMP6_DST_UNREACH,
447 ICMP6_DST_UNREACH_ADDR, 0);
455 * Check with the firewall...
457 if (ip6_fw_enable && ip6_fw_chk_ptr) {
459 /* If ipfw says divert, we have to just drop packet */
460 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
469 * Fake scoped addresses. Note that even link-local source or
470 * destinaion can appear, if the originating node just sends the
471 * packet to us (without address resolution for the destination).
472 * Since both icmp6_error and icmp6_redirect_output fill the embedded
473 * link identifiers, we can do this stuff after making a copy for
474 * returning an error.
476 if (rt->rt_ifp->if_flags & IFF_LOOPBACK) {
478 * See corresponding comments in ip6_output.
479 * XXX: but is it possible that ip6_forward() sends a packet
480 * to a loopback interface? I don't think so, and thus
481 * I bark here. (jinmei@kame.net)
482 * XXX: it is common to route invalid packets to loopback.
483 * also, the codepath will be visited on use of ::1 in
489 if ((rt->rt_flags & (RTF_BLACKHOLE | RTF_REJECT)) == 0)
492 kprintf("ip6_forward: outgoing interface is loopback. "
493 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
494 ip6_sprintf(&ip6->ip6_src),
495 ip6_sprintf(&ip6->ip6_dst),
496 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
497 if_name(rt->rt_ifp));
500 /* we can just use rcvif in forwarding. */
501 origifp = m->m_pkthdr.rcvif;
504 origifp = rt->rt_ifp;
506 * clear embedded scope identifiers if necessary.
507 * in6_clearscope will touch the addresses only when necessary.
509 in6_clearscope(&ip6->ip6_src);
510 in6_clearscope(&ip6->ip6_dst);
513 * Run through list of hooks for output packets.
515 if (pfil_has_hooks(&inet6_pfil_hook)) {
516 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp,
522 ip6 = mtod(m, struct ip6_hdr *);
525 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
527 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
528 ip6stat.ip6s_cantforward++;
530 ip6stat.ip6s_forward++;
531 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
533 ip6stat.ip6s_redirectsent++;
544 if (type == ND_REDIRECT) {
545 icmp6_redirect_output(mcopy, rt);
551 /* xxx MTU is constant in PPP? */
555 /* Tell source to slow down like source quench in IP? */
558 case ENETUNREACH: /* shouldn't happen, checked above */
563 type = ICMP6_DST_UNREACH;
564 code = ICMP6_DST_UNREACH_ADDR;
567 icmp6_error(mcopy, type, code, 0);