1/*-
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/netinet6/ip6_forward.c 185088 2008-11-19 09:39:34Z zec $");
34
35#include "opt_inet.h"
36#include "opt_inet6.h"
37#include "opt_ipsec.h"
38#include "opt_ipstealth.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/malloc.h>
43#include <sys/mbuf.h>
44#include <sys/domain.h>
45#include <sys/protosw.h>
46#include <sys/socket.h>
47#include <sys/errno.h>
48#include <sys/time.h>
49#include <sys/kernel.h>
50#include <sys/syslog.h>
51#include <sys/vimage.h>
52
53#include <net/if.h>
54#include <net/route.h>
55#include <net/pfil.h>
56
57#include <netinet/in.h>
58#include <netinet/in_var.h>
59#include <netinet/in_systm.h>
60#include <netinet/ip.h>
61#include <netinet/ip_var.h>
62#include <netinet6/in6_var.h>
63#include <netinet/ip6.h>
64#include <netinet6/ip6_var.h>
65#include <netinet6/scope6_var.h>
66#include <netinet/icmp6.h>
67#include <netinet6/nd6.h>
68
69#include <netinet/in_pcb.h>
70
71#ifdef IPSEC
72#include <netipsec/ipsec.h>
73#include <netipsec/ipsec6.h>
74#include <netipsec/key.h>
75#endif /* IPSEC */
76
77#include <netinet6/ip6protosw.h>
78
79#ifdef VIMAGE_GLOBALS
80struct route_in6 ip6_forward_rt;
81#endif
82
83/*
84 * Forward a packet. If some error occurs return the sender
85 * an icmp packet. Note we can't always generate a meaningful
86 * icmp message because icmp doesn't have a large enough repertoire
87 * of codes and types.
88 *
89 * If not forwarding, just drop the packet. This could be confusing
90 * if ipforwarding was zero but some routing protocol was advancing
91 * us as a gateway to somewhere. However, we must let the routing
92 * protocol deal with that.
93 *
94 */
95void
96ip6_forward(struct mbuf *m, int srcrt)
97{
98 INIT_VNET_INET6(curvnet);
99 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
100 struct sockaddr_in6 *dst = NULL;
101 struct rtentry *rt = NULL;
102 int error, type = 0, code = 0;
103 struct mbuf *mcopy = NULL;
104 struct ifnet *origifp; /* maybe unnecessary */
105 u_int32_t inzone, outzone;
106 struct in6_addr src_in6, dst_in6;
107#ifdef IPSEC
108 INIT_VNET_IPSEC(curvnet);
109 struct secpolicy *sp = NULL;
110 int ipsecrt = 0;
111#endif
112 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
113
114 /* GIANT_REQUIRED; */ /* XXX bz: ip6_forward_rt */
115
116#ifdef IPSEC
117 /*
118 * Check AH/ESP integrity.
119 */
120 /*
121 * Don't increment ip6s_cantforward because this is the check
122 * before forwarding packet actually.
123 */
124 if (ipsec6_in_reject(m, NULL)) {
125 V_ipsec6stat.in_polvio++;
126 m_freem(m);
127 return;
128 }
129#endif /* IPSEC */
130
131 /*
132 * Do not forward packets to multicast destination (should be handled
133 * by ip6_mforward().
134 * Do not forward packets with unspecified source. It was discussed
135 * in July 2000, on the ipngwg mailing list.
136 */
137 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
138 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
139 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
140 V_ip6stat.ip6s_cantforward++;
141 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
142 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
143 V_ip6_log_time = time_second;
144 log(LOG_DEBUG,
145 "cannot forward "
146 "from %s to %s nxt %d received on %s\n",
147 ip6_sprintf(ip6bufs, &ip6->ip6_src),
148 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
149 ip6->ip6_nxt,
150 if_name(m->m_pkthdr.rcvif));
151 }
152 m_freem(m);
153 return;
154 }
155
156#ifdef IPSTEALTH
157 if (!V_ip6stealth) {
158#endif
159 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
160 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
161 icmp6_error(m, ICMP6_TIME_EXCEEDED,
162 ICMP6_TIME_EXCEED_TRANSIT, 0);
163 return;
164 }
165 ip6->ip6_hlim -= IPV6_HLIMDEC;
166
167#ifdef IPSTEALTH
168 }
169#endif
170
171 /*
172 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
173 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
174 * we need to generate an ICMP6 message to the src.
175 * Thanks to M_EXT, in most cases copy will not occur.
176 *
177 * It is important to save it before IPsec processing as IPsec
178 * processing may modify the mbuf.
179 */
180 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
181
182#ifdef IPSEC
183 /* get a security policy for this packet */
184 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
185 IP_FORWARDING, &error);
186 if (sp == NULL) {
187 V_ipsec6stat.out_inval++;
188 V_ip6stat.ip6s_cantforward++;
189 if (mcopy) {
190#if 0
191 /* XXX: what icmp ? */
192#else
193 m_freem(mcopy);
194#endif
195 }
196 m_freem(m);
197 return;
198 }
199
200 error = 0;
201
202 /* check policy */
203 switch (sp->policy) {
204 case IPSEC_POLICY_DISCARD:
205 /*
206 * This packet is just discarded.
207 */
208 V_ipsec6stat.out_polvio++;
209 V_ip6stat.ip6s_cantforward++;
210 KEY_FREESP(&sp);
211 if (mcopy) {
212#if 0
213 /* XXX: what icmp ? */
214#else
215 m_freem(mcopy);
216#endif
217 }
218 m_freem(m);
219 return;
220
221 case IPSEC_POLICY_BYPASS:
222 case IPSEC_POLICY_NONE:
223 /* no need to do IPsec. */
224 KEY_FREESP(&sp);
225 goto skip_ipsec;
226
227 case IPSEC_POLICY_IPSEC:
228 if (sp->req == NULL) {
229 /* XXX should be panic ? */
230 printf("ip6_forward: No IPsec request specified.\n");
231 V_ip6stat.ip6s_cantforward++;
232 KEY_FREESP(&sp);
233 if (mcopy) {
234#if 0
235 /* XXX: what icmp ? */
236#else
237 m_freem(mcopy);
238#endif
239 }
240 m_freem(m);
241 return;
242 }
243 /* do IPsec */
244 break;
245
246 case IPSEC_POLICY_ENTRUST:
247 default:
248 /* should be panic ?? */
249 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
250 KEY_FREESP(&sp);
251 goto skip_ipsec;
252 }
253
254 {
255 struct ipsecrequest *isr = NULL;
256 struct ipsec_output_state state;
257
258 /*
259 * when the kernel forwards a packet, it is not proper to apply
260 * IPsec transport mode to the packet is not proper. this check
261 * avoid from this.
262 * at present, if there is even a transport mode SA request in the
263 * security policy, the kernel does not apply IPsec to the packet.
264 * this check is not enough because the following case is valid.
265 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
266 */
267 for (isr = sp->req; isr; isr = isr->next) {
268 if (isr->saidx.mode == IPSEC_MODE_ANY)
269 goto doipsectunnel;
270 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
271 goto doipsectunnel;
272 }
273
274 /*
275 * if there's no need for tunnel mode IPsec, skip.
276 */
277 if (!isr)
278 goto skip_ipsec;
279
280 doipsectunnel:
281 /*
282 * All the extension headers will become inaccessible
283 * (since they can be encrypted).
284 * Don't panic, we need no more updates to extension headers
285 * on inner IPv6 packet (since they are now encapsulated).
286 *
287 * IPv6 [ESP|AH] IPv6 [extension headers] payload
288 */
289 bzero(&state, sizeof(state));
290 state.m = m;
291 state.ro = NULL; /* update at ipsec6_output_tunnel() */
292 state.dst = NULL; /* update at ipsec6_output_tunnel() */
293
294 error = ipsec6_output_tunnel(&state, sp, 0);
295
296 m = state.m;
297 KEY_FREESP(&sp);
298
299 if (error) {
300 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
301 switch (error) {
302 case EHOSTUNREACH:
303 case ENETUNREACH:
304 case EMSGSIZE:
305 case ENOBUFS:
306 case ENOMEM:
307 break;
308 default:
309 printf("ip6_output (ipsec): error code %d\n", error);
310 /* FALLTHROUGH */
311 case ENOENT:
312 /* don't show these error codes to the user */
313 break;
314 }
315 V_ip6stat.ip6s_cantforward++;
316 if (mcopy) {
317#if 0
318 /* XXX: what icmp ? */
319#else
320 m_freem(mcopy);
321#endif
322 }
323 m_freem(m);
324 return;
325 } else {
326 /*
327 * In the FAST IPSec case we have already
328 * re-injected the packet and it has been freed
329 * by the ipsec_done() function. So, just clean
330 * up after ourselves.
331 */
332 m = NULL;
333 goto freecopy;
334 }
335
336 if ((m != NULL) && (ip6 != mtod(m, struct ip6_hdr *)) ){
337 /*
338 * now tunnel mode headers are added. we are originating
339 * packet instead of forwarding the packet.
340 */
341 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
342 NULL);
343 goto freecopy;
344 }
345
346 /* adjust pointer */
347 dst = (struct sockaddr_in6 *)state.dst;
348 rt = state.ro ? state.ro->ro_rt : NULL;
349 if (dst != NULL && rt != NULL)
350 ipsecrt = 1;
351 }
352 skip_ipsec:
353#endif /* IPSEC */
354
355#ifdef IPSEC
356 if (ipsecrt)
357 goto skip_routing;
358#endif
359
360 dst = (struct sockaddr_in6 *)&V_ip6_forward_rt.ro_dst;
361 if (!srcrt) {
362 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
363 if (V_ip6_forward_rt.ro_rt == 0 ||
364 (V_ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
365 if (V_ip6_forward_rt.ro_rt) {
366 RTFREE(V_ip6_forward_rt.ro_rt);
367 V_ip6_forward_rt.ro_rt = 0;
368 }
369
370 /* this probably fails but give it a try again */
371 rtalloc((struct route *)&V_ip6_forward_rt);
372 }
373
374 if (V_ip6_forward_rt.ro_rt == 0) {
375 V_ip6stat.ip6s_noroute++;
376 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
377 if (mcopy) {
378 icmp6_error(mcopy, ICMP6_DST_UNREACH,
379 ICMP6_DST_UNREACH_NOROUTE, 0);
380 }
381 m_freem(m);
382 return;
383 }
384 } else if ((rt = V_ip6_forward_rt.ro_rt) == 0 ||
385 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
386 if (V_ip6_forward_rt.ro_rt) {
387 RTFREE(V_ip6_forward_rt.ro_rt);
388 V_ip6_forward_rt.ro_rt = 0;
389 }
390 bzero(dst, sizeof(*dst));
391 dst->sin6_len = sizeof(struct sockaddr_in6);
392 dst->sin6_family = AF_INET6;
393 dst->sin6_addr = ip6->ip6_dst;
394
395 rtalloc((struct route *)&V_ip6_forward_rt);
396 if (V_ip6_forward_rt.ro_rt == 0) {
397 V_ip6stat.ip6s_noroute++;
398 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
399 if (mcopy) {
400 icmp6_error(mcopy, ICMP6_DST_UNREACH,
401 ICMP6_DST_UNREACH_NOROUTE, 0);
402 }
403 m_freem(m);
404 return;
405 }
406 }
407 rt = V_ip6_forward_rt.ro_rt;
408#ifdef IPSEC
409 skip_routing:;
410#endif
411
412 /*
413 * Source scope check: if a packet can't be delivered to its
414 * destination for the reason that the destination is beyond the scope
415 * of the source address, discard the packet and return an icmp6
416 * destination unreachable error with Code 2 (beyond scope of source
417 * address). We use a local copy of ip6_src, since in6_setscope()
418 * will possibly modify its first argument.
419 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
420 */
421 src_in6 = ip6->ip6_src;
422 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
423 /* XXX: this should not happen */
424 V_ip6stat.ip6s_cantforward++;
425 V_ip6stat.ip6s_badscope++;
426 m_freem(m);
427 return;
428 }
429 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
430 V_ip6stat.ip6s_cantforward++;
431 V_ip6stat.ip6s_badscope++;
432 m_freem(m);
433 return;
434 }
435 if (inzone != outzone
436#ifdef IPSEC
437 && !ipsecrt
438#endif
439 ) {
440 V_ip6stat.ip6s_cantforward++;
441 V_ip6stat.ip6s_badscope++;
442 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
443
444 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
445 V_ip6_log_time = time_second;
446 log(LOG_DEBUG,
447 "cannot forward "
448 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
449 ip6_sprintf(ip6bufs, &ip6->ip6_src),
450 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
451 ip6->ip6_nxt,
452 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
453 }
454 if (mcopy)
455 icmp6_error(mcopy, ICMP6_DST_UNREACH,
456 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
457 m_freem(m);
458 return;
459 }
460
461 /*
462 * Destination scope check: if a packet is going to break the scope
463 * zone of packet's destination address, discard it. This case should
464 * usually be prevented by appropriately-configured routing table, but
465 * we need an explicit check because we may mistakenly forward the
466 * packet to a different zone by (e.g.) a default route.
467 */
468 dst_in6 = ip6->ip6_dst;
469 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
470 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
471 inzone != outzone) {
472 V_ip6stat.ip6s_cantforward++;
473 V_ip6stat.ip6s_badscope++;
474 m_freem(m);
475 return;
476 }
477
478 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
479 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
480 if (mcopy) {
481 u_long mtu;
482#ifdef IPSEC
483 struct secpolicy *sp;
484 int ipsecerror;
485 size_t ipsechdrsiz;
486#endif /* IPSEC */
487
488 mtu = IN6_LINKMTU(rt->rt_ifp);
489#ifdef IPSEC
490 /*
491 * When we do IPsec tunnel ingress, we need to play
492 * with the link value (decrement IPsec header size
493 * from mtu value). The code is much simpler than v4
494 * case, as we have the outgoing interface for
495 * encapsulated packet as "rt->rt_ifp".
496 */
497 sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
498 IP_FORWARDING, &ipsecerror);
499 if (sp) {
500 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
501 IPSEC_DIR_OUTBOUND, NULL);
502 if (ipsechdrsiz < mtu)
503 mtu -= ipsechdrsiz;
504 }
505
506 /*
507 * if mtu becomes less than minimum MTU,
508 * tell minimum MTU (and I'll need to fragment it).
509 */
510 if (mtu < IPV6_MMTU)
511 mtu = IPV6_MMTU;
512#endif /* IPSEC */
513 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
514 }
515 m_freem(m);
516 return;
517 }
518
519 if (rt->rt_flags & RTF_GATEWAY)
520 dst = (struct sockaddr_in6 *)rt->rt_gateway;
521
522 /*
523 * If we are to forward the packet using the same interface
524 * as one we got the packet from, perhaps we should send a redirect
525 * to sender to shortcut a hop.
526 * Only send redirect if source is sending directly to us,
527 * and if packet was not source routed (or has any options).
528 * Also, don't send redirect if forwarding using a route
529 * modified by a redirect.
530 */
531 if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
532#ifdef IPSEC
533 !ipsecrt &&
534#endif /* IPSEC */
535 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
536 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
537 /*
538 * If the incoming interface is equal to the outgoing
539 * one, and the link attached to the interface is
540 * point-to-point, then it will be highly probable
541 * that a routing loop occurs. Thus, we immediately
542 * drop the packet and send an ICMPv6 error message.
543 *
544 * type/code is based on suggestion by Rich Draves.
545 * not sure if it is the best pick.
546 */
547 icmp6_error(mcopy, ICMP6_DST_UNREACH,
548 ICMP6_DST_UNREACH_ADDR, 0);
549 m_freem(m);
550 return;
551 }
552 type = ND_REDIRECT;
553 }
554
555 /*
556 * Fake scoped addresses. Note that even link-local source or
557 * destinaion can appear, if the originating node just sends the
558 * packet to us (without address resolution for the destination).
559 * Since both icmp6_error and icmp6_redirect_output fill the embedded
560 * link identifiers, we can do this stuff after making a copy for
561 * returning an error.
562 */
563 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
564 /*
565 * See corresponding comments in ip6_output.
566 * XXX: but is it possible that ip6_forward() sends a packet
567 * to a loopback interface? I don't think so, and thus
568 * I bark here. (jinmei@kame.net)
569 * XXX: it is common to route invalid packets to loopback.
570 * also, the codepath will be visited on use of ::1 in
571 * rthdr. (itojun)
572 */
573#if 1
574 if (0)
575#else
576 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
577#endif
578 {
579 printf("ip6_forward: outgoing interface is loopback. "
580 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
581 ip6_sprintf(ip6bufs, &ip6->ip6_src),
582 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
583 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
584 if_name(rt->rt_ifp));
585 }
586
587 /* we can just use rcvif in forwarding. */
588 origifp = m->m_pkthdr.rcvif;
589 }
590 else
591 origifp = rt->rt_ifp;
592 /*
593 * clear embedded scope identifiers if necessary.
594 * in6_clearscope will touch the addresses only when necessary.
595 */
596 in6_clearscope(&ip6->ip6_src);
597 in6_clearscope(&ip6->ip6_dst);
598
599 /* Jump over all PFIL processing if hooks are not active. */
600 if (!PFIL_HOOKED(&inet6_pfil_hook))
601 goto pass;
602
603 /* Run through list of hooks for output packets. */
604 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
605 if (error != 0)
606 goto senderr;
607 if (m == NULL)
608 goto freecopy;
609 ip6 = mtod(m, struct ip6_hdr *);
610
611pass:
612 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
613 if (error) {
614 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
615 V_ip6stat.ip6s_cantforward++;
616 } else {
617 V_ip6stat.ip6s_forward++;
618 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
619 if (type)
620 V_ip6stat.ip6s_redirectsent++;
621 else {
622 if (mcopy)
623 goto freecopy;
624 }
625 }
626
627senderr:
628 if (mcopy == NULL)
629 return;
630 switch (error) {
631 case 0:
632 if (type == ND_REDIRECT) {
633 icmp6_redirect_output(mcopy, rt);
634 return;
635 }
636 goto freecopy;
637
638 case EMSGSIZE:
639 /* xxx MTU is constant in PPP? */
640 goto freecopy;
641
642 case ENOBUFS:
643 /* Tell source to slow down like source quench in IP? */
644 goto freecopy;
645
646 case ENETUNREACH: /* shouldn't happen, checked above */
647 case EHOSTUNREACH:
648 case ENETDOWN:
649 case EHOSTDOWN:
650 default:
651 type = ICMP6_DST_UNREACH;
652 code = ICMP6_DST_UNREACH_ADDR;
653 break;
654 }
655 icmp6_error(mcopy, type, code, 0);
656 return;
657
658 freecopy:
659 m_freem(mcopy);
660 return;
661}
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/netinet6/ip6_forward.c 185088 2008-11-19 09:39:34Z zec $");
34
35#include "opt_inet.h"
36#include "opt_inet6.h"
37#include "opt_ipsec.h"
38#include "opt_ipstealth.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/malloc.h>
43#include <sys/mbuf.h>
44#include <sys/domain.h>
45#include <sys/protosw.h>
46#include <sys/socket.h>
47#include <sys/errno.h>
48#include <sys/time.h>
49#include <sys/kernel.h>
50#include <sys/syslog.h>
51#include <sys/vimage.h>
52
53#include <net/if.h>
54#include <net/route.h>
55#include <net/pfil.h>
56
57#include <netinet/in.h>
58#include <netinet/in_var.h>
59#include <netinet/in_systm.h>
60#include <netinet/ip.h>
61#include <netinet/ip_var.h>
62#include <netinet6/in6_var.h>
63#include <netinet/ip6.h>
64#include <netinet6/ip6_var.h>
65#include <netinet6/scope6_var.h>
66#include <netinet/icmp6.h>
67#include <netinet6/nd6.h>
68
69#include <netinet/in_pcb.h>
70
71#ifdef IPSEC
72#include <netipsec/ipsec.h>
73#include <netipsec/ipsec6.h>
74#include <netipsec/key.h>
75#endif /* IPSEC */
76
77#include <netinet6/ip6protosw.h>
78
79#ifdef VIMAGE_GLOBALS
80struct route_in6 ip6_forward_rt;
81#endif
82
83/*
84 * Forward a packet. If some error occurs return the sender
85 * an icmp packet. Note we can't always generate a meaningful
86 * icmp message because icmp doesn't have a large enough repertoire
87 * of codes and types.
88 *
89 * If not forwarding, just drop the packet. This could be confusing
90 * if ipforwarding was zero but some routing protocol was advancing
91 * us as a gateway to somewhere. However, we must let the routing
92 * protocol deal with that.
93 *
94 */
95void
96ip6_forward(struct mbuf *m, int srcrt)
97{
98 INIT_VNET_INET6(curvnet);
99 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
100 struct sockaddr_in6 *dst = NULL;
101 struct rtentry *rt = NULL;
102 int error, type = 0, code = 0;
103 struct mbuf *mcopy = NULL;
104 struct ifnet *origifp; /* maybe unnecessary */
105 u_int32_t inzone, outzone;
106 struct in6_addr src_in6, dst_in6;
107#ifdef IPSEC
108 INIT_VNET_IPSEC(curvnet);
109 struct secpolicy *sp = NULL;
110 int ipsecrt = 0;
111#endif
112 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
113
114 /* GIANT_REQUIRED; */ /* XXX bz: ip6_forward_rt */
115
116#ifdef IPSEC
117 /*
118 * Check AH/ESP integrity.
119 */
120 /*
121 * Don't increment ip6s_cantforward because this is the check
122 * before forwarding packet actually.
123 */
124 if (ipsec6_in_reject(m, NULL)) {
125 V_ipsec6stat.in_polvio++;
126 m_freem(m);
127 return;
128 }
129#endif /* IPSEC */
130
131 /*
132 * Do not forward packets to multicast destination (should be handled
133 * by ip6_mforward().
134 * Do not forward packets with unspecified source. It was discussed
135 * in July 2000, on the ipngwg mailing list.
136 */
137 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
138 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
139 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
140 V_ip6stat.ip6s_cantforward++;
141 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
142 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
143 V_ip6_log_time = time_second;
144 log(LOG_DEBUG,
145 "cannot forward "
146 "from %s to %s nxt %d received on %s\n",
147 ip6_sprintf(ip6bufs, &ip6->ip6_src),
148 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
149 ip6->ip6_nxt,
150 if_name(m->m_pkthdr.rcvif));
151 }
152 m_freem(m);
153 return;
154 }
155
156#ifdef IPSTEALTH
157 if (!V_ip6stealth) {
158#endif
159 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
160 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
161 icmp6_error(m, ICMP6_TIME_EXCEEDED,
162 ICMP6_TIME_EXCEED_TRANSIT, 0);
163 return;
164 }
165 ip6->ip6_hlim -= IPV6_HLIMDEC;
166
167#ifdef IPSTEALTH
168 }
169#endif
170
171 /*
172 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
173 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
174 * we need to generate an ICMP6 message to the src.
175 * Thanks to M_EXT, in most cases copy will not occur.
176 *
177 * It is important to save it before IPsec processing as IPsec
178 * processing may modify the mbuf.
179 */
180 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
181
182#ifdef IPSEC
183 /* get a security policy for this packet */
184 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
185 IP_FORWARDING, &error);
186 if (sp == NULL) {
187 V_ipsec6stat.out_inval++;
188 V_ip6stat.ip6s_cantforward++;
189 if (mcopy) {
190#if 0
191 /* XXX: what icmp ? */
192#else
193 m_freem(mcopy);
194#endif
195 }
196 m_freem(m);
197 return;
198 }
199
200 error = 0;
201
202 /* check policy */
203 switch (sp->policy) {
204 case IPSEC_POLICY_DISCARD:
205 /*
206 * This packet is just discarded.
207 */
208 V_ipsec6stat.out_polvio++;
209 V_ip6stat.ip6s_cantforward++;
210 KEY_FREESP(&sp);
211 if (mcopy) {
212#if 0
213 /* XXX: what icmp ? */
214#else
215 m_freem(mcopy);
216#endif
217 }
218 m_freem(m);
219 return;
220
221 case IPSEC_POLICY_BYPASS:
222 case IPSEC_POLICY_NONE:
223 /* no need to do IPsec. */
224 KEY_FREESP(&sp);
225 goto skip_ipsec;
226
227 case IPSEC_POLICY_IPSEC:
228 if (sp->req == NULL) {
229 /* XXX should be panic ? */
230 printf("ip6_forward: No IPsec request specified.\n");
231 V_ip6stat.ip6s_cantforward++;
232 KEY_FREESP(&sp);
233 if (mcopy) {
234#if 0
235 /* XXX: what icmp ? */
236#else
237 m_freem(mcopy);
238#endif
239 }
240 m_freem(m);
241 return;
242 }
243 /* do IPsec */
244 break;
245
246 case IPSEC_POLICY_ENTRUST:
247 default:
248 /* should be panic ?? */
249 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
250 KEY_FREESP(&sp);
251 goto skip_ipsec;
252 }
253
254 {
255 struct ipsecrequest *isr = NULL;
256 struct ipsec_output_state state;
257
258 /*
259 * when the kernel forwards a packet, it is not proper to apply
260 * IPsec transport mode to the packet is not proper. this check
261 * avoid from this.
262 * at present, if there is even a transport mode SA request in the
263 * security policy, the kernel does not apply IPsec to the packet.
264 * this check is not enough because the following case is valid.
265 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
266 */
267 for (isr = sp->req; isr; isr = isr->next) {
268 if (isr->saidx.mode == IPSEC_MODE_ANY)
269 goto doipsectunnel;
270 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
271 goto doipsectunnel;
272 }
273
274 /*
275 * if there's no need for tunnel mode IPsec, skip.
276 */
277 if (!isr)
278 goto skip_ipsec;
279
280 doipsectunnel:
281 /*
282 * All the extension headers will become inaccessible
283 * (since they can be encrypted).
284 * Don't panic, we need no more updates to extension headers
285 * on inner IPv6 packet (since they are now encapsulated).
286 *
287 * IPv6 [ESP|AH] IPv6 [extension headers] payload
288 */
289 bzero(&state, sizeof(state));
290 state.m = m;
291 state.ro = NULL; /* update at ipsec6_output_tunnel() */
292 state.dst = NULL; /* update at ipsec6_output_tunnel() */
293
294 error = ipsec6_output_tunnel(&state, sp, 0);
295
296 m = state.m;
297 KEY_FREESP(&sp);
298
299 if (error) {
300 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
301 switch (error) {
302 case EHOSTUNREACH:
303 case ENETUNREACH:
304 case EMSGSIZE:
305 case ENOBUFS:
306 case ENOMEM:
307 break;
308 default:
309 printf("ip6_output (ipsec): error code %d\n", error);
310 /* FALLTHROUGH */
311 case ENOENT:
312 /* don't show these error codes to the user */
313 break;
314 }
315 V_ip6stat.ip6s_cantforward++;
316 if (mcopy) {
317#if 0
318 /* XXX: what icmp ? */
319#else
320 m_freem(mcopy);
321#endif
322 }
323 m_freem(m);
324 return;
325 } else {
326 /*
327 * In the FAST IPSec case we have already
328 * re-injected the packet and it has been freed
329 * by the ipsec_done() function. So, just clean
330 * up after ourselves.
331 */
332 m = NULL;
333 goto freecopy;
334 }
335
336 if ((m != NULL) && (ip6 != mtod(m, struct ip6_hdr *)) ){
337 /*
338 * now tunnel mode headers are added. we are originating
339 * packet instead of forwarding the packet.
340 */
341 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
342 NULL);
343 goto freecopy;
344 }
345
346 /* adjust pointer */
347 dst = (struct sockaddr_in6 *)state.dst;
348 rt = state.ro ? state.ro->ro_rt : NULL;
349 if (dst != NULL && rt != NULL)
350 ipsecrt = 1;
351 }
352 skip_ipsec:
353#endif /* IPSEC */
354
355#ifdef IPSEC
356 if (ipsecrt)
357 goto skip_routing;
358#endif
359
360 dst = (struct sockaddr_in6 *)&V_ip6_forward_rt.ro_dst;
361 if (!srcrt) {
362 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
363 if (V_ip6_forward_rt.ro_rt == 0 ||
364 (V_ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
365 if (V_ip6_forward_rt.ro_rt) {
366 RTFREE(V_ip6_forward_rt.ro_rt);
367 V_ip6_forward_rt.ro_rt = 0;
368 }
369
370 /* this probably fails but give it a try again */
371 rtalloc((struct route *)&V_ip6_forward_rt);
372 }
373
374 if (V_ip6_forward_rt.ro_rt == 0) {
375 V_ip6stat.ip6s_noroute++;
376 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
377 if (mcopy) {
378 icmp6_error(mcopy, ICMP6_DST_UNREACH,
379 ICMP6_DST_UNREACH_NOROUTE, 0);
380 }
381 m_freem(m);
382 return;
383 }
384 } else if ((rt = V_ip6_forward_rt.ro_rt) == 0 ||
385 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
386 if (V_ip6_forward_rt.ro_rt) {
387 RTFREE(V_ip6_forward_rt.ro_rt);
388 V_ip6_forward_rt.ro_rt = 0;
389 }
390 bzero(dst, sizeof(*dst));
391 dst->sin6_len = sizeof(struct sockaddr_in6);
392 dst->sin6_family = AF_INET6;
393 dst->sin6_addr = ip6->ip6_dst;
394
395 rtalloc((struct route *)&V_ip6_forward_rt);
396 if (V_ip6_forward_rt.ro_rt == 0) {
397 V_ip6stat.ip6s_noroute++;
398 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
399 if (mcopy) {
400 icmp6_error(mcopy, ICMP6_DST_UNREACH,
401 ICMP6_DST_UNREACH_NOROUTE, 0);
402 }
403 m_freem(m);
404 return;
405 }
406 }
407 rt = V_ip6_forward_rt.ro_rt;
408#ifdef IPSEC
409 skip_routing:;
410#endif
411
412 /*
413 * Source scope check: if a packet can't be delivered to its
414 * destination for the reason that the destination is beyond the scope
415 * of the source address, discard the packet and return an icmp6
416 * destination unreachable error with Code 2 (beyond scope of source
417 * address). We use a local copy of ip6_src, since in6_setscope()
418 * will possibly modify its first argument.
419 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
420 */
421 src_in6 = ip6->ip6_src;
422 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
423 /* XXX: this should not happen */
424 V_ip6stat.ip6s_cantforward++;
425 V_ip6stat.ip6s_badscope++;
426 m_freem(m);
427 return;
428 }
429 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
430 V_ip6stat.ip6s_cantforward++;
431 V_ip6stat.ip6s_badscope++;
432 m_freem(m);
433 return;
434 }
435 if (inzone != outzone
436#ifdef IPSEC
437 && !ipsecrt
438#endif
439 ) {
440 V_ip6stat.ip6s_cantforward++;
441 V_ip6stat.ip6s_badscope++;
442 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
443
444 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
445 V_ip6_log_time = time_second;
446 log(LOG_DEBUG,
447 "cannot forward "
448 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
449 ip6_sprintf(ip6bufs, &ip6->ip6_src),
450 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
451 ip6->ip6_nxt,
452 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
453 }
454 if (mcopy)
455 icmp6_error(mcopy, ICMP6_DST_UNREACH,
456 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
457 m_freem(m);
458 return;
459 }
460
461 /*
462 * Destination scope check: if a packet is going to break the scope
463 * zone of packet's destination address, discard it. This case should
464 * usually be prevented by appropriately-configured routing table, but
465 * we need an explicit check because we may mistakenly forward the
466 * packet to a different zone by (e.g.) a default route.
467 */
468 dst_in6 = ip6->ip6_dst;
469 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
470 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
471 inzone != outzone) {
472 V_ip6stat.ip6s_cantforward++;
473 V_ip6stat.ip6s_badscope++;
474 m_freem(m);
475 return;
476 }
477
478 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
479 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
480 if (mcopy) {
481 u_long mtu;
482#ifdef IPSEC
483 struct secpolicy *sp;
484 int ipsecerror;
485 size_t ipsechdrsiz;
486#endif /* IPSEC */
487
488 mtu = IN6_LINKMTU(rt->rt_ifp);
489#ifdef IPSEC
490 /*
491 * When we do IPsec tunnel ingress, we need to play
492 * with the link value (decrement IPsec header size
493 * from mtu value). The code is much simpler than v4
494 * case, as we have the outgoing interface for
495 * encapsulated packet as "rt->rt_ifp".
496 */
497 sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
498 IP_FORWARDING, &ipsecerror);
499 if (sp) {
500 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
501 IPSEC_DIR_OUTBOUND, NULL);
502 if (ipsechdrsiz < mtu)
503 mtu -= ipsechdrsiz;
504 }
505
506 /*
507 * if mtu becomes less than minimum MTU,
508 * tell minimum MTU (and I'll need to fragment it).
509 */
510 if (mtu < IPV6_MMTU)
511 mtu = IPV6_MMTU;
512#endif /* IPSEC */
513 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
514 }
515 m_freem(m);
516 return;
517 }
518
519 if (rt->rt_flags & RTF_GATEWAY)
520 dst = (struct sockaddr_in6 *)rt->rt_gateway;
521
522 /*
523 * If we are to forward the packet using the same interface
524 * as one we got the packet from, perhaps we should send a redirect
525 * to sender to shortcut a hop.
526 * Only send redirect if source is sending directly to us,
527 * and if packet was not source routed (or has any options).
528 * Also, don't send redirect if forwarding using a route
529 * modified by a redirect.
530 */
531 if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
532#ifdef IPSEC
533 !ipsecrt &&
534#endif /* IPSEC */
535 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
536 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
537 /*
538 * If the incoming interface is equal to the outgoing
539 * one, and the link attached to the interface is
540 * point-to-point, then it will be highly probable
541 * that a routing loop occurs. Thus, we immediately
542 * drop the packet and send an ICMPv6 error message.
543 *
544 * type/code is based on suggestion by Rich Draves.
545 * not sure if it is the best pick.
546 */
547 icmp6_error(mcopy, ICMP6_DST_UNREACH,
548 ICMP6_DST_UNREACH_ADDR, 0);
549 m_freem(m);
550 return;
551 }
552 type = ND_REDIRECT;
553 }
554
555 /*
556 * Fake scoped addresses. Note that even link-local source or
557 * destinaion can appear, if the originating node just sends the
558 * packet to us (without address resolution for the destination).
559 * Since both icmp6_error and icmp6_redirect_output fill the embedded
560 * link identifiers, we can do this stuff after making a copy for
561 * returning an error.
562 */
563 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
564 /*
565 * See corresponding comments in ip6_output.
566 * XXX: but is it possible that ip6_forward() sends a packet
567 * to a loopback interface? I don't think so, and thus
568 * I bark here. (jinmei@kame.net)
569 * XXX: it is common to route invalid packets to loopback.
570 * also, the codepath will be visited on use of ::1 in
571 * rthdr. (itojun)
572 */
573#if 1
574 if (0)
575#else
576 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
577#endif
578 {
579 printf("ip6_forward: outgoing interface is loopback. "
580 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
581 ip6_sprintf(ip6bufs, &ip6->ip6_src),
582 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
583 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
584 if_name(rt->rt_ifp));
585 }
586
587 /* we can just use rcvif in forwarding. */
588 origifp = m->m_pkthdr.rcvif;
589 }
590 else
591 origifp = rt->rt_ifp;
592 /*
593 * clear embedded scope identifiers if necessary.
594 * in6_clearscope will touch the addresses only when necessary.
595 */
596 in6_clearscope(&ip6->ip6_src);
597 in6_clearscope(&ip6->ip6_dst);
598
599 /* Jump over all PFIL processing if hooks are not active. */
600 if (!PFIL_HOOKED(&inet6_pfil_hook))
601 goto pass;
602
603 /* Run through list of hooks for output packets. */
604 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
605 if (error != 0)
606 goto senderr;
607 if (m == NULL)
608 goto freecopy;
609 ip6 = mtod(m, struct ip6_hdr *);
610
611pass:
612 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
613 if (error) {
614 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
615 V_ip6stat.ip6s_cantforward++;
616 } else {
617 V_ip6stat.ip6s_forward++;
618 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
619 if (type)
620 V_ip6stat.ip6s_redirectsent++;
621 else {
622 if (mcopy)
623 goto freecopy;
624 }
625 }
626
627senderr:
628 if (mcopy == NULL)
629 return;
630 switch (error) {
631 case 0:
632 if (type == ND_REDIRECT) {
633 icmp6_redirect_output(mcopy, rt);
634 return;
635 }
636 goto freecopy;
637
638 case EMSGSIZE:
639 /* xxx MTU is constant in PPP? */
640 goto freecopy;
641
642 case ENOBUFS:
643 /* Tell source to slow down like source quench in IP? */
644 goto freecopy;
645
646 case ENETUNREACH: /* shouldn't happen, checked above */
647 case EHOSTUNREACH:
648 case ENETDOWN:
649 case EHOSTDOWN:
650 default:
651 type = ICMP6_DST_UNREACH;
652 code = ICMP6_DST_UNREACH_ADDR;
653 break;
654 }
655 icmp6_error(mcopy, type, code, 0);
656 return;
657
658 freecopy:
659 m_freem(mcopy);
660 return;
661}