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 1.5 2003/08/23 11:02:45 rob 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>
54 #include <netinet/in.h>
55 #include <netinet/in_var.h>
56 #include <netinet/in_systm.h>
57 #include <netinet/ip.h>
58 #include <netinet/ip_var.h>
59 #include <netinet6/in6_var.h>
60 #include <netinet/ip6.h>
61 #include <netinet6/ip6_var.h>
62 #include <netinet/icmp6.h>
63 #include <netinet6/nd6.h>
65 #include <netinet/in_pcb.h>
68 #include <netinet6/ipsec.h>
70 #include <netinet6/ipsec6.h>
72 #include <netproto/key/key.h>
78 #include <netipsec/key.h>
80 #endif /* FAST_IPSEC */
82 #include <net/ip6fw/ip6_fw.h>
84 #include <net/net_osdep.h>
86 extern int (*fr_checkp) (struct ip *, int, struct ifnet *, int, struct mbuf **);
88 struct route_in6 ip6_forward_rt;
91 * Forward a packet. If some error occurs return the sender
92 * an icmp packet. Note we can't always generate a meaningful
93 * icmp message because icmp doesn't have a large enough repertoire
96 * If not forwarding, just drop the packet. This could be confusing
97 * if ipforwarding was zero but some routing protocol was advancing
98 * us as a gateway to somewhere. However, we must let the routing
99 * protocol deal with that.
104 ip6_forward(m, srcrt)
108 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
109 struct sockaddr_in6 *dst;
111 int error, type = 0, code = 0;
112 struct mbuf *mcopy = NULL;
113 struct ifnet *origifp; /* maybe unnecessary */
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 #if !defined(FAST_IPSEC)
128 ipsec6stat.in_polvio++;
136 * Do not forward packets to multicast destination (should be handled
138 * Do not forward packets with unspecified source. It was discussed
139 * in July 2000, on ipngwg mailing list.
141 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
142 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
143 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
144 ip6stat.ip6s_cantforward++;
145 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
146 if (ip6_log_time + ip6_log_interval < time_second) {
147 ip6_log_time = time_second;
150 "from %s to %s nxt %d received on %s\n",
151 ip6_sprintf(&ip6->ip6_src),
152 ip6_sprintf(&ip6->ip6_dst),
154 if_name(m->m_pkthdr.rcvif));
160 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
161 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
162 icmp6_error(m, ICMP6_TIME_EXCEEDED,
163 ICMP6_TIME_EXCEED_TRANSIT, 0);
166 ip6->ip6_hlim -= IPV6_HLIMDEC;
169 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
170 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
171 * we need to generate an ICMP6 message to the src.
172 * Thanks to M_EXT, in most cases copy will not occur.
174 * It is important to save it before IPsec processing as IPsec
175 * processing may modify the mbuf.
177 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
180 /* get a security policy for this packet */
181 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
184 ipsec6stat.out_inval++;
185 ip6stat.ip6s_cantforward++;
188 /* XXX: what icmp ? */
200 switch (sp->policy) {
201 case IPSEC_POLICY_DISCARD:
203 * This packet is just discarded.
205 ipsec6stat.out_polvio++;
206 ip6stat.ip6s_cantforward++;
210 /* XXX: what icmp ? */
218 case IPSEC_POLICY_BYPASS:
219 case IPSEC_POLICY_NONE:
220 /* no need to do IPsec. */
224 case IPSEC_POLICY_IPSEC:
225 if (sp->req == NULL) {
226 /* XXX should be panic ? */
227 printf("ip6_forward: No IPsec request specified.\n");
228 ip6stat.ip6s_cantforward++;
232 /* XXX: what icmp ? */
243 case IPSEC_POLICY_ENTRUST:
245 /* should be panic ?? */
246 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
252 struct ipsec_output_state state;
255 * All the extension headers will become inaccessible
256 * (since they can be encrypted).
257 * Don't panic, we need no more updates to extension headers
258 * on inner IPv6 packet (since they are now encapsulated).
260 * IPv6 [ESP|AH] IPv6 [extension headers] payload
262 bzero(&state, sizeof(state));
264 state.ro = NULL; /* update at ipsec6_output_tunnel() */
265 state.dst = NULL; /* update at ipsec6_output_tunnel() */
267 error = ipsec6_output_tunnel(&state, sp, 0);
273 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
282 printf("ip6_output (ipsec): error code %d\n", error);
285 /* don't show these error codes to the user */
288 ip6stat.ip6s_cantforward++;
291 /* XXX: what icmp ? */
303 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
306 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
308 if (ip6_forward_rt.ro_rt == 0 ||
309 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
310 if (ip6_forward_rt.ro_rt) {
311 RTFREE(ip6_forward_rt.ro_rt);
312 ip6_forward_rt.ro_rt = 0;
314 /* this probably fails but give it a try again */
315 rtalloc_ign((struct route *)&ip6_forward_rt,
319 if (ip6_forward_rt.ro_rt == 0) {
320 ip6stat.ip6s_noroute++;
321 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
323 icmp6_error(mcopy, ICMP6_DST_UNREACH,
324 ICMP6_DST_UNREACH_NOROUTE, 0);
329 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
330 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
331 if (ip6_forward_rt.ro_rt) {
332 RTFREE(ip6_forward_rt.ro_rt);
333 ip6_forward_rt.ro_rt = 0;
335 bzero(dst, sizeof(*dst));
336 dst->sin6_len = sizeof(struct sockaddr_in6);
337 dst->sin6_family = AF_INET6;
338 dst->sin6_addr = ip6->ip6_dst;
340 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
341 if (ip6_forward_rt.ro_rt == 0) {
342 ip6stat.ip6s_noroute++;
343 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
345 icmp6_error(mcopy, ICMP6_DST_UNREACH,
346 ICMP6_DST_UNREACH_NOROUTE, 0);
352 rt = ip6_forward_rt.ro_rt;
355 * Scope check: if a packet can't be delivered to its destination
356 * for the reason that the destination is beyond the scope of the
357 * source address, discard the packet and return an icmp6 destination
358 * unreachable error with Code 2 (beyond scope of source address).
359 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
361 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
362 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
363 ip6stat.ip6s_cantforward++;
364 ip6stat.ip6s_badscope++;
365 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
367 if (ip6_log_time + ip6_log_interval < time_second) {
368 ip6_log_time = time_second;
371 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
372 ip6_sprintf(&ip6->ip6_src),
373 ip6_sprintf(&ip6->ip6_dst),
375 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
378 icmp6_error(mcopy, ICMP6_DST_UNREACH,
379 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
384 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
385 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
389 struct secpolicy *sp;
394 mtu = rt->rt_ifp->if_mtu;
397 * When we do IPsec tunnel ingress, we need to play
398 * with if_mtu value (decrement IPsec header size
399 * from mtu value). The code is much simpler than v4
400 * case, as we have the outgoing interface for
401 * encapsulated packet as "rt->rt_ifp".
403 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
404 IP_FORWARDING, &ipsecerror);
406 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
407 IPSEC_DIR_OUTBOUND, NULL);
408 if (ipsechdrsiz < mtu)
413 * if mtu becomes less than minimum MTU,
414 * tell minimum MTU (and I'll need to fragment it).
419 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
425 if (rt->rt_flags & RTF_GATEWAY)
426 dst = (struct sockaddr_in6 *)rt->rt_gateway;
429 * If we are to forward the packet using the same interface
430 * as one we got the packet from, perhaps we should send a redirect
431 * to sender to shortcut a hop.
432 * Only send redirect if source is sending directly to us,
433 * and if packet was not source routed (or has any options).
434 * Also, don't send redirect if forwarding using a route
435 * modified by a redirect.
437 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
438 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
439 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
441 * If the incoming interface is equal to the outgoing
442 * one, and the link attached to the interface is
443 * point-to-point, then it will be highly probable
444 * that a routing loop occurs. Thus, we immediately
445 * drop the packet and send an ICMPv6 error message.
447 * type/code is based on suggestion by Rich Draves.
448 * not sure if it is the best pick.
450 icmp6_error(mcopy, ICMP6_DST_UNREACH,
451 ICMP6_DST_UNREACH_ADDR, 0);
459 * Check with the firewall...
461 if (ip6_fw_enable && ip6_fw_chk_ptr) {
463 /* If ipfw says divert, we have to just drop packet */
464 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
473 * Fake scoped addresses. Note that even link-local source or
474 * destinaion can appear, if the originating node just sends the
475 * packet to us (without address resolution for the destination).
476 * Since both icmp6_error and icmp6_redirect_output fill the embedded
477 * link identifiers, we can do this stuff after making a copy for
478 * returning an error.
480 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
482 * See corresponding comments in ip6_output.
483 * XXX: but is it possible that ip6_forward() sends a packet
484 * to a loopback interface? I don't think so, and thus
485 * I bark here. (jinmei@kame.net)
486 * XXX: it is common to route invalid packets to loopback.
487 * also, the codepath will be visited on use of ::1 in
493 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
496 printf("ip6_forward: outgoing interface is loopback. "
497 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
498 ip6_sprintf(&ip6->ip6_src),
499 ip6_sprintf(&ip6->ip6_dst),
500 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
501 if_name(rt->rt_ifp));
504 /* we can just use rcvif in forwarding. */
505 origifp = m->m_pkthdr.rcvif;
508 origifp = rt->rt_ifp;
509 #ifndef SCOPEDROUTING
511 * clear embedded scope identifiers if necessary.
512 * in6_clearscope will touch the addresses only when necessary.
514 in6_clearscope(&ip6->ip6_src);
515 in6_clearscope(&ip6->ip6_dst);
519 * Check if we want to allow this packet to be processed.
520 * Consider it to be bad if not.
525 if ((*fr_checkp)((struct ip *)ip6, sizeof(*ip6),
526 rt->rt_ifp, 1, &m1) != 0)
531 ip6 = mtod(m, struct ip6_hdr *);
534 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
536 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
537 ip6stat.ip6s_cantforward++;
539 ip6stat.ip6s_forward++;
540 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
542 ip6stat.ip6s_redirectsent++;
553 if (type == ND_REDIRECT) {
554 icmp6_redirect_output(mcopy, rt);
561 /* xxx MTU is constant in PPP? */
565 /* Tell source to slow down like source quench in IP? */
568 case ENETUNREACH: /* shouldn't happen, checked above */
573 type = ICMP6_DST_UNREACH;
574 code = ICMP6_DST_UNREACH_ADDR;
577 icmp6_error(mcopy, type, code, 0);