1 /* $FreeBSD: src/sys/netinet6/ip6_forward.c,v 1.25.2.4 2005/08/18 09:39:35 suz Exp $ */
2 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
3
4 /*-
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
19 *
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)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include "opt_ip6fw.h"
34 #include "opt_inet.h"
35 #include "opt_inet6.h"
36 #include "opt_ipsec.h"
37 #include "opt_ipstealth.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/malloc.h>
42 #include <sys/mbuf.h>
43 #include <sys/domain.h>
44 #include <sys/protosw.h>
45 #include <sys/socket.h>
46 #include <sys/errno.h>
47 #include <sys/time.h>
48 #include <sys/kernel.h>
49 #include <sys/syslog.h>
50
51 #include <net/if.h>
52 #include <net/route.h>
53 #include <net/pfil.h>
54
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>
65
66 #include <netinet/in_pcb.h>
67
68 #ifdef IPSEC
69 #include <netinet6/ipsec.h>
70 #ifdef INET6
71 #include <netinet6/ipsec6.h>
72 #endif
73 #include <netkey/key.h>
74 #endif /* IPSEC */
75
76 #ifdef FAST_IPSEC
77 #include <netipsec/ipsec.h>
78 #include <netipsec/ipsec6.h>
79 #include <netipsec/key.h>
80 #define IPSEC
81 #endif /* FAST_IPSEC */
82
83 #include <netinet6/ip6_fw.h>
84
85 #include <net/net_osdep.h>
86
87 #include <netinet6/ip6protosw.h>
88
89 struct route_in6 ip6_forward_rt;
90
91 /*
92 * Forward a packet. If some error occurs return the sender
93 * an icmp packet. Note we can't always generate a meaningful
94 * icmp message because icmp doesn't have a large enough repertoire
95 * of codes and types.
96 *
97 * If not forwarding, just drop the packet. This could be confusing
98 * if ipforwarding was zero but some routing protocol was advancing
99 * us as a gateway to somewhere. However, we must let the routing
100 * protocol deal with that.
101 *
102 */
103
104 void
105 ip6_forward(m, srcrt)
106 struct mbuf *m;
107 int srcrt;
108 {
109 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
110 struct sockaddr_in6 *dst = NULL;
111 struct rtentry *rt = NULL;
112 int error, type = 0, code = 0;
113 struct mbuf *mcopy = NULL;
114 struct ifnet *origifp; /* maybe unnecessary */
115 u_int32_t srczone, dstzone;
116 #ifdef IPSEC
117 struct secpolicy *sp = NULL;
118 int ipsecrt = 0;
119 #endif
120
121 #ifdef IPSEC
122 /*
123 * Check AH/ESP integrity.
124 */
125 /*
126 * Don't increment ip6s_cantforward because this is the check
127 * before forwarding packet actually.
128 */
129 if (ipsec6_in_reject(m, NULL)) {
130 #if !defined(FAST_IPSEC)
131 ipsec6stat.in_polvio++;
132 #endif
133 m_freem(m);
134 return;
135 }
136 #endif /* IPSEC */
137
138 /*
139 * Do not forward packets to multicast destination (should be handled
140 * by ip6_mforward().
141 * Do not forward packets with unspecified source. It was discussed
142 * in July 2000, on the ipngwg mailing list.
143 */
144 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
145 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
146 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
147 ip6stat.ip6s_cantforward++;
148 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
149 if (ip6_log_time + ip6_log_interval < time_second) {
150 ip6_log_time = time_second;
151 log(LOG_DEBUG,
152 "cannot forward "
153 "from %s to %s nxt %d received on %s\n",
154 ip6_sprintf(&ip6->ip6_src),
155 ip6_sprintf(&ip6->ip6_dst),
156 ip6->ip6_nxt,
157 if_name(m->m_pkthdr.rcvif));
158 }
159 m_freem(m);
160 return;
161 }
162
163 #ifdef IPSTEALTH
164 if (!ip6stealth) {
165 #endif
166 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
167 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
168 icmp6_error(m, ICMP6_TIME_EXCEEDED,
169 ICMP6_TIME_EXCEED_TRANSIT, 0);
170 return;
171 }
172 ip6->ip6_hlim -= IPV6_HLIMDEC;
173
174 #ifdef IPSTEALTH
175 }
176 #endif
177
178 /*
179 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
180 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
181 * we need to generate an ICMP6 message to the src.
182 * Thanks to M_EXT, in most cases copy will not occur.
183 *
184 * It is important to save it before IPsec processing as IPsec
185 * processing may modify the mbuf.
186 */
187 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
188
189 #ifdef IPSEC
190 /* get a security policy for this packet */
191 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
192 IP_FORWARDING, &error);
193 if (sp == NULL) {
194 ipsec6stat.out_inval++;
195 ip6stat.ip6s_cantforward++;
196 if (mcopy) {
197 #if 0
198 /* XXX: what icmp ? */
199 #else
200 m_freem(mcopy);
201 #endif
202 }
203 m_freem(m);
204 return;
205 }
206
207 error = 0;
208
209 /* check policy */
210 switch (sp->policy) {
211 case IPSEC_POLICY_DISCARD:
212 /*
213 * This packet is just discarded.
214 */
215 ipsec6stat.out_polvio++;
216 ip6stat.ip6s_cantforward++;
217 key_freesp(sp);
218 if (mcopy) {
219 #if 0
220 /* XXX: what icmp ? */
221 #else
222 m_freem(mcopy);
223 #endif
224 }
225 m_freem(m);
226 return;
227
228 case IPSEC_POLICY_BYPASS:
229 case IPSEC_POLICY_NONE:
230 /* no need to do IPsec. */
231 key_freesp(sp);
232 goto skip_ipsec;
233
234 case IPSEC_POLICY_IPSEC:
235 if (sp->req == NULL) {
236 /* XXX should be panic ? */
237 printf("ip6_forward: No IPsec request specified.\n");
238 ip6stat.ip6s_cantforward++;
239 key_freesp(sp);
240 if (mcopy) {
241 #if 0
242 /* XXX: what icmp ? */
243 #else
244 m_freem(mcopy);
245 #endif
246 }
247 m_freem(m);
248 return;
249 }
250 /* do IPsec */
251 break;
252
253 case IPSEC_POLICY_ENTRUST:
254 default:
255 /* should be panic ?? */
256 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
257 key_freesp(sp);
258 goto skip_ipsec;
259 }
260
261 {
262 struct ipsecrequest *isr = NULL;
263 struct ipsec_output_state state;
264
265 /*
266 * when the kernel forwards a packet, it is not proper to apply
267 * IPsec transport mode to the packet is not proper. this check
268 * avoid from this.
269 * at present, if there is even a transport mode SA request in the
270 * security policy, the kernel does not apply IPsec to the packet.
271 * this check is not enough because the following case is valid.
272 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
273 */
274 for (isr = sp->req; isr; isr = isr->next) {
275 if (isr->saidx.mode == IPSEC_MODE_ANY)
276 goto doipsectunnel;
277 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
278 goto doipsectunnel;
279 }
280
281 /*
282 * if there's no need for tunnel mode IPsec, skip.
283 */
284 if (!isr)
285 goto skip_ipsec;
286
287 doipsectunnel:
288 /*
289 * All the extension headers will become inaccessible
290 * (since they can be encrypted).
291 * Don't panic, we need no more updates to extension headers
292 * on inner IPv6 packet (since they are now encapsulated).
293 *
294 * IPv6 [ESP|AH] IPv6 [extension headers] payload
295 */
296 bzero(&state, sizeof(state));
297 state.m = m;
298 state.ro = NULL; /* update at ipsec6_output_tunnel() */
299 state.dst = NULL; /* update at ipsec6_output_tunnel() */
300
301 error = ipsec6_output_tunnel(&state, sp, 0);
302
303 m = state.m;
304 key_freesp(sp);
305
306 if (error) {
307 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
308 switch (error) {
309 case EHOSTUNREACH:
310 case ENETUNREACH:
311 case EMSGSIZE:
312 case ENOBUFS:
313 case ENOMEM:
314 break;
315 default:
316 printf("ip6_output (ipsec): error code %d\n", error);
317 /* FALLTHROUGH */
318 case ENOENT:
319 /* don't show these error codes to the user */
320 break;
321 }
322 ip6stat.ip6s_cantforward++;
323 if (mcopy) {
324 #if 0
325 /* XXX: what icmp ? */
326 #else
327 m_freem(mcopy);
328 #endif
329 }
330 m_freem(m);
331 return;
332 }
333
334 if (ip6 != mtod(m, struct ip6_hdr *)) {
335 /*
336 * now tunnel mode headers are added. we are originating
337 * packet instead of forwarding the packet.
338 */
339 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
340 NULL);
341 goto freecopy;
342 }
343
344 /* adjust pointer */
345 dst = (struct sockaddr_in6 *)state.dst;
346 rt = state.ro ? state.ro->ro_rt : NULL;
347 if (dst != NULL && rt != NULL)
348 ipsecrt = 1;
349 }
350 skip_ipsec:
351 #endif /* IPSEC */
352
353 #ifdef IPSEC
354 if (ipsecrt)
355 goto skip_routing;
356 #endif
357
358 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
359 if (!srcrt) {
360 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
361 if (ip6_forward_rt.ro_rt == 0 ||
362 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
363 if (ip6_forward_rt.ro_rt) {
364 RTFREE(ip6_forward_rt.ro_rt);
365 ip6_forward_rt.ro_rt = 0;
366 }
367
368 /* this probably fails but give it a try again */
369 rtalloc((struct route *)&ip6_forward_rt);
370 }
371
372 if (ip6_forward_rt.ro_rt == 0) {
373 ip6stat.ip6s_noroute++;
374 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
375 if (mcopy) {
376 icmp6_error(mcopy, ICMP6_DST_UNREACH,
377 ICMP6_DST_UNREACH_NOROUTE, 0);
378 }
379 m_freem(m);
380 return;
381 }
382 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
383 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
384 if (ip6_forward_rt.ro_rt) {
385 RTFREE(ip6_forward_rt.ro_rt);
386 ip6_forward_rt.ro_rt = 0;
387 }
388 bzero(dst, sizeof(*dst));
389 dst->sin6_len = sizeof(struct sockaddr_in6);
390 dst->sin6_family = AF_INET6;
391 dst->sin6_addr = ip6->ip6_dst;
392
393 rtalloc((struct route *)&ip6_forward_rt);
394 if (ip6_forward_rt.ro_rt == 0) {
395 ip6stat.ip6s_noroute++;
396 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
397 if (mcopy) {
398 icmp6_error(mcopy, ICMP6_DST_UNREACH,
399 ICMP6_DST_UNREACH_NOROUTE, 0);
400 }
401 m_freem(m);
402 return;
403 }
404 }
405 rt = ip6_forward_rt.ro_rt;
406 #ifdef IPSEC
407 skip_routing:;
408 #endif
409
410 /*
411 * Scope check: if a packet can't be delivered to its destination
412 * for the reason that the destination is beyond the scope of the
413 * source address, discard the packet and return an icmp6 destination
414 * unreachable error with Code 2 (beyond scope of source address).
415 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
416 */
417 if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
418 in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone)) {
419 /* XXX: this should not happen */
420 ip6stat.ip6s_cantforward++;
421 ip6stat.ip6s_badscope++;
422 m_freem(m);
423 return;
424 }
425 if (srczone != dstzone
426 #ifdef IPSEC
427 && !ipsecrt
428 #endif
429 ) {
430 ip6stat.ip6s_cantforward++;
431 ip6stat.ip6s_badscope++;
432 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
433
434 if (ip6_log_time + ip6_log_interval < time_second) {
435 ip6_log_time = time_second;
436 log(LOG_DEBUG,
437 "cannot forward "
438 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
439 ip6_sprintf(&ip6->ip6_src),
440 ip6_sprintf(&ip6->ip6_dst),
441 ip6->ip6_nxt,
442 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
443 }
444 if (mcopy)
445 icmp6_error(mcopy, ICMP6_DST_UNREACH,
446 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
447 m_freem(m);
448 return;
449 }
450
451 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
452 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
453 if (mcopy) {
454 u_long mtu;
455 #ifdef IPSEC
456 struct secpolicy *sp;
457 int ipsecerror;
458 size_t ipsechdrsiz;
459 #endif
460
461 mtu = IN6_LINKMTU(rt->rt_ifp);
462 #ifdef IPSEC
463 /*
464 * When we do IPsec tunnel ingress, we need to play
465 * with the link value (decrement IPsec header size
466 * from mtu value). The code is much simpler than v4
467 * case, as we have the outgoing interface for
468 * encapsulated packet as "rt->rt_ifp".
469 */
470 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
471 IP_FORWARDING, &ipsecerror);
472 if (sp) {
473 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
474 IPSEC_DIR_OUTBOUND, NULL);
475 if (ipsechdrsiz < mtu)
476 mtu -= ipsechdrsiz;
477 }
478
479 /*
480 * if mtu becomes less than minimum MTU,
481 * tell minimum MTU (and I'll need to fragment it).
482 */
483 if (mtu < IPV6_MMTU)
484 mtu = IPV6_MMTU;
485 #endif
486 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
487 }
488 m_freem(m);
489 return;
490 }
491
492 if (rt->rt_flags & RTF_GATEWAY)
493 dst = (struct sockaddr_in6 *)rt->rt_gateway;
494
495 /*
496 * If we are to forward the packet using the same interface
497 * as one we got the packet from, perhaps we should send a redirect
498 * to sender to shortcut a hop.
499 * Only send redirect if source is sending directly to us,
500 * and if packet was not source routed (or has any options).
501 * Also, don't send redirect if forwarding using a route
502 * modified by a redirect.
503 */
504 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
505 #ifdef IPSEC
506 !ipsecrt &&
507 #endif
508 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
509 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
510 /*
511 * If the incoming interface is equal to the outgoing
512 * one, and the link attached to the interface is
513 * point-to-point, then it will be highly probable
514 * that a routing loop occurs. Thus, we immediately
515 * drop the packet and send an ICMPv6 error message.
516 *
517 * type/code is based on suggestion by Rich Draves.
518 * not sure if it is the best pick.
519 */
520 icmp6_error(mcopy, ICMP6_DST_UNREACH,
521 ICMP6_DST_UNREACH_ADDR, 0);
522 m_freem(m);
523 return;
524 }
525 type = ND_REDIRECT;
526 }
527
528 /*
529 * Check with the firewall...
530 */
531 if (ip6_fw_enable && ip6_fw_chk_ptr) {
532 u_short port = 0;
533 /* If ipfw says divert, we have to just drop packet */
534 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
535 m_freem(m);
536 goto freecopy;
537 }
538 if (!m)
539 goto freecopy;
540 }
541
542 /*
543 * Fake scoped addresses. Note that even link-local source or
544 * destinaion can appear, if the originating node just sends the
545 * packet to us (without address resolution for the destination).
546 * Since both icmp6_error and icmp6_redirect_output fill the embedded
547 * link identifiers, we can do this stuff after making a copy for
548 * returning an error.
549 */
550 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
551 /*
552 * See corresponding comments in ip6_output.
553 * XXX: but is it possible that ip6_forward() sends a packet
554 * to a loopback interface? I don't think so, and thus
555 * I bark here. (jinmei@kame.net)
556 * XXX: it is common to route invalid packets to loopback.
557 * also, the codepath will be visited on use of ::1 in
558 * rthdr. (itojun)
559 */
560 #if 1
561 if (0)
562 #else
563 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
564 #endif
565 {
566 printf("ip6_forward: outgoing interface is loopback. "
567 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
568 ip6_sprintf(&ip6->ip6_src),
569 ip6_sprintf(&ip6->ip6_dst),
570 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
571 if_name(rt->rt_ifp));
572 }
573
574 /* we can just use rcvif in forwarding. */
575 origifp = m->m_pkthdr.rcvif;
576 }
577 else
578 origifp = rt->rt_ifp;
579 /*
580 * clear embedded scope identifiers if necessary.
581 * in6_clearscope will touch the addresses only when necessary.
582 */
583 in6_clearscope(&ip6->ip6_src);
584 in6_clearscope(&ip6->ip6_dst);
585
586 /* Jump over all PFIL processing if hooks are not active. */
587 if (inet6_pfil_hook.ph_busy_count == -1)
588 goto pass;
589
590 /* Run through list of hooks for output packets. */
591 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
592 if (error != 0)
593 goto senderr;
594 if (m == NULL)
595 goto freecopy;
596 ip6 = mtod(m, struct ip6_hdr *);
597
598 pass:
599 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
600 if (error) {
601 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
602 ip6stat.ip6s_cantforward++;
603 } else {
604 ip6stat.ip6s_forward++;
605 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
606 if (type)
607 ip6stat.ip6s_redirectsent++;
608 else {
609 if (mcopy)
610 goto freecopy;
611 }
612 }
613
614 senderr:
615 if (mcopy == NULL)
616 return;
617 switch (error) {
618 case 0:
619 if (type == ND_REDIRECT) {
620 icmp6_redirect_output(mcopy, rt);
621 return;
622 }
623 goto freecopy;
624
625 case EMSGSIZE:
626 /* xxx MTU is constant in PPP? */
627 goto freecopy;
628
629 case ENOBUFS:
630 /* Tell source to slow down like source quench in IP? */
631 goto freecopy;
632
633 case ENETUNREACH: /* shouldn't happen, checked above */
634 case EHOSTUNREACH:
635 case ENETDOWN:
636 case EHOSTDOWN:
637 default:
638 type = ICMP6_DST_UNREACH;
639 code = ICMP6_DST_UNREACH_ADDR;
640 break;
641 }
642 icmp6_error(mcopy, type, code, 0);
643 return;
644
645 freecopy:
646 m_freem(mcopy);
647 return;
648 }
Cache object: c52961f3dd620acef34935c33c2ba1b4
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