1 /* $FreeBSD: releng/5.2/sys/netinet6/ip6_forward.c 122921 2003-11-20 19:47:31Z andre $ */
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_pfil_hooks.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 #ifdef PFIL_HOOKS
54 #include <net/pfil.h>
55 #endif
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 <netinet/icmp6.h>
66 #include <netinet6/nd6.h>
67
68 #include <netinet/in_pcb.h>
69
70 #ifdef IPSEC
71 #include <netinet6/ipsec.h>
72 #ifdef INET6
73 #include <netinet6/ipsec6.h>
74 #endif
75 #include <netkey/key.h>
76 #endif /* IPSEC */
77
78 #ifdef FAST_IPSEC
79 #include <netipsec/ipsec.h>
80 #include <netipsec/ipsec6.h>
81 #include <netipsec/key.h>
82 #define IPSEC
83 #endif /* FAST_IPSEC */
84
85 #include <netinet6/ip6_fw.h>
86
87 #include <net/net_osdep.h>
88
89 #include <netinet6/ip6protosw.h>
90
91 struct route_in6 ip6_forward_rt;
92
93 /*
94 * Forward a packet. If some error occurs return the sender
95 * an icmp packet. Note we can't always generate a meaningful
96 * icmp message because icmp doesn't have a large enough repertoire
97 * of codes and types.
98 *
99 * If not forwarding, just drop the packet. This could be confusing
100 * if ipforwarding was zero but some routing protocol was advancing
101 * us as a gateway to somewhere. However, we must let the routing
102 * protocol deal with that.
103 *
104 */
105
106 void
107 ip6_forward(m, srcrt)
108 struct mbuf *m;
109 int srcrt;
110 {
111 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
112 struct sockaddr_in6 *dst = NULL;
113 struct rtentry *rt = NULL;
114 int error, type = 0, code = 0;
115 struct mbuf *mcopy = NULL;
116 struct ifnet *origifp; /* maybe unnecessary */
117 u_int32_t srczone, dstzone;
118 #ifdef IPSEC
119 struct secpolicy *sp = NULL;
120 int ipsecrt = 0;
121 #endif
122
123 #ifdef IPSEC
124 /*
125 * Check AH/ESP integrity.
126 */
127 /*
128 * Don't increment ip6s_cantforward because this is the check
129 * before forwarding packet actually.
130 */
131 if (ipsec6_in_reject(m, NULL)) {
132 #if !defined(FAST_IPSEC)
133 ipsec6stat.in_polvio++;
134 #endif
135 m_freem(m);
136 return;
137 }
138 #endif /* IPSEC */
139
140 /*
141 * Do not forward packets to multicast destination (should be handled
142 * by ip6_mforward().
143 * Do not forward packets with unspecified source. It was discussed
144 * in July 2000, on the ipngwg mailing list.
145 */
146 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
147 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
148 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
149 ip6stat.ip6s_cantforward++;
150 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
151 if (ip6_log_time + ip6_log_interval < time_second) {
152 ip6_log_time = time_second;
153 log(LOG_DEBUG,
154 "cannot forward "
155 "from %s to %s nxt %d received on %s\n",
156 ip6_sprintf(&ip6->ip6_src),
157 ip6_sprintf(&ip6->ip6_dst),
158 ip6->ip6_nxt,
159 if_name(m->m_pkthdr.rcvif));
160 }
161 m_freem(m);
162 return;
163 }
164
165 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
166 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
167 icmp6_error(m, ICMP6_TIME_EXCEEDED,
168 ICMP6_TIME_EXCEED_TRANSIT, 0);
169 return;
170 }
171 ip6->ip6_hlim -= IPV6_HLIMDEC;
172
173 /*
174 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
175 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
176 * we need to generate an ICMP6 message to the src.
177 * Thanks to M_EXT, in most cases copy will not occur.
178 *
179 * It is important to save it before IPsec processing as IPsec
180 * processing may modify the mbuf.
181 */
182 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
183
184 #ifdef IPSEC
185 /* get a security policy for this packet */
186 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
187 IP_FORWARDING, &error);
188 if (sp == NULL) {
189 ipsec6stat.out_inval++;
190 ip6stat.ip6s_cantforward++;
191 if (mcopy) {
192 #if 0
193 /* XXX: what icmp ? */
194 #else
195 m_freem(mcopy);
196 #endif
197 }
198 m_freem(m);
199 return;
200 }
201
202 error = 0;
203
204 /* check policy */
205 switch (sp->policy) {
206 case IPSEC_POLICY_DISCARD:
207 /*
208 * This packet is just discarded.
209 */
210 ipsec6stat.out_polvio++;
211 ip6stat.ip6s_cantforward++;
212 key_freesp(sp);
213 if (mcopy) {
214 #if 0
215 /* XXX: what icmp ? */
216 #else
217 m_freem(mcopy);
218 #endif
219 }
220 m_freem(m);
221 return;
222
223 case IPSEC_POLICY_BYPASS:
224 case IPSEC_POLICY_NONE:
225 /* no need to do IPsec. */
226 key_freesp(sp);
227 goto skip_ipsec;
228
229 case IPSEC_POLICY_IPSEC:
230 if (sp->req == NULL) {
231 /* XXX should be panic ? */
232 printf("ip6_forward: No IPsec request specified.\n");
233 ip6stat.ip6s_cantforward++;
234 key_freesp(sp);
235 if (mcopy) {
236 #if 0
237 /* XXX: what icmp ? */
238 #else
239 m_freem(mcopy);
240 #endif
241 }
242 m_freem(m);
243 return;
244 }
245 /* do IPsec */
246 break;
247
248 case IPSEC_POLICY_ENTRUST:
249 default:
250 /* should be panic ?? */
251 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
252 key_freesp(sp);
253 goto skip_ipsec;
254 }
255
256 {
257 struct ipsecrequest *isr = NULL;
258 struct ipsec_output_state state;
259
260 /*
261 * when the kernel forwards a packet, it is not proper to apply
262 * IPsec transport mode to the packet is not proper. this check
263 * avoid from this.
264 * at present, if there is even a transport mode SA request in the
265 * security policy, the kernel does not apply IPsec to the packet.
266 * this check is not enough because the following case is valid.
267 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
268 */
269 for (isr = sp->req; isr; isr = isr->next) {
270 if (isr->saidx.mode == IPSEC_MODE_TRANSPORT)
271 goto skip_ipsec;
272 }
273
274 /*
275 * All the extension headers will become inaccessible
276 * (since they can be encrypted).
277 * Don't panic, we need no more updates to extension headers
278 * on inner IPv6 packet (since they are now encapsulated).
279 *
280 * IPv6 [ESP|AH] IPv6 [extension headers] payload
281 */
282 bzero(&state, sizeof(state));
283 state.m = m;
284 state.ro = NULL; /* update at ipsec6_output_tunnel() */
285 state.dst = NULL; /* update at ipsec6_output_tunnel() */
286
287 error = ipsec6_output_tunnel(&state, sp, 0);
288
289 m = state.m;
290 key_freesp(sp);
291
292 if (error) {
293 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
294 switch (error) {
295 case EHOSTUNREACH:
296 case ENETUNREACH:
297 case EMSGSIZE:
298 case ENOBUFS:
299 case ENOMEM:
300 break;
301 default:
302 printf("ip6_output (ipsec): error code %d\n", error);
303 /* FALLTHROUGH */
304 case ENOENT:
305 /* don't show these error codes to the user */
306 break;
307 }
308 ip6stat.ip6s_cantforward++;
309 if (mcopy) {
310 #if 0
311 /* XXX: what icmp ? */
312 #else
313 m_freem(mcopy);
314 #endif
315 }
316 m_freem(m);
317 return;
318 }
319
320 /* adjust pointer */
321 ip6 = mtod(m, struct ip6_hdr *);
322 dst = (struct sockaddr_in6 *)state.dst;
323 rt = state.ro ? state.ro->ro_rt : NULL;
324 if (dst != NULL && rt != NULL)
325 ipsecrt = 1;
326 }
327 skip_ipsec:
328 #endif /* IPSEC */
329
330 #ifdef IPSEC
331 if (ipsecrt)
332 goto skip_routing;
333 #endif
334
335 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
336 if (!srcrt) {
337 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
338 if (ip6_forward_rt.ro_rt == 0 ||
339 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
340 if (ip6_forward_rt.ro_rt) {
341 RTFREE(ip6_forward_rt.ro_rt);
342 ip6_forward_rt.ro_rt = 0;
343 }
344
345 /* this probably fails but give it a try again */
346 rtalloc((struct route *)&ip6_forward_rt);
347 }
348
349 if (ip6_forward_rt.ro_rt == 0) {
350 ip6stat.ip6s_noroute++;
351 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
352 if (mcopy) {
353 icmp6_error(mcopy, ICMP6_DST_UNREACH,
354 ICMP6_DST_UNREACH_NOROUTE, 0);
355 }
356 m_freem(m);
357 return;
358 }
359 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
360 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
361 if (ip6_forward_rt.ro_rt) {
362 RTFREE(ip6_forward_rt.ro_rt);
363 ip6_forward_rt.ro_rt = 0;
364 }
365 bzero(dst, sizeof(*dst));
366 dst->sin6_len = sizeof(struct sockaddr_in6);
367 dst->sin6_family = AF_INET6;
368 dst->sin6_addr = ip6->ip6_dst;
369
370 rtalloc((struct route *)&ip6_forward_rt);
371 if (ip6_forward_rt.ro_rt == 0) {
372 ip6stat.ip6s_noroute++;
373 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
374 if (mcopy) {
375 icmp6_error(mcopy, ICMP6_DST_UNREACH,
376 ICMP6_DST_UNREACH_NOROUTE, 0);
377 }
378 m_freem(m);
379 return;
380 }
381 }
382 rt = ip6_forward_rt.ro_rt;
383 #ifdef IPSEC
384 skip_routing:;
385 #endif
386
387 /*
388 * Scope check: if a packet can't be delivered to its destination
389 * for the reason that the destination is beyond the scope of the
390 * source address, discard the packet and return an icmp6 destination
391 * unreachable error with Code 2 (beyond scope of source address).
392 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
393 */
394 if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
395 in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone)) {
396 /* XXX: this should not happen */
397 ip6stat.ip6s_cantforward++;
398 ip6stat.ip6s_badscope++;
399 m_freem(m);
400 return;
401 }
402 if (srczone != dstzone
403 #ifdef IPSEC
404 && !ipsecrt
405 #endif
406 ) {
407 ip6stat.ip6s_cantforward++;
408 ip6stat.ip6s_badscope++;
409 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
410
411 if (ip6_log_time + ip6_log_interval < time_second) {
412 ip6_log_time = time_second;
413 log(LOG_DEBUG,
414 "cannot forward "
415 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
416 ip6_sprintf(&ip6->ip6_src),
417 ip6_sprintf(&ip6->ip6_dst),
418 ip6->ip6_nxt,
419 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
420 }
421 if (mcopy)
422 icmp6_error(mcopy, ICMP6_DST_UNREACH,
423 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
424 m_freem(m);
425 return;
426 }
427
428 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
429 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
430 if (mcopy) {
431 u_long mtu;
432 #ifdef IPSEC
433 struct secpolicy *sp;
434 int ipsecerror;
435 size_t ipsechdrsiz;
436 #endif
437
438 mtu = IN6_LINKMTU(rt->rt_ifp);
439 #ifdef IPSEC
440 /*
441 * When we do IPsec tunnel ingress, we need to play
442 * with the link value (decrement IPsec header size
443 * from mtu value). The code is much simpler than v4
444 * case, as we have the outgoing interface for
445 * encapsulated packet as "rt->rt_ifp".
446 */
447 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
448 IP_FORWARDING, &ipsecerror);
449 if (sp) {
450 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
451 IPSEC_DIR_OUTBOUND, NULL);
452 if (ipsechdrsiz < mtu)
453 mtu -= ipsechdrsiz;
454 }
455
456 /*
457 * if mtu becomes less than minimum MTU,
458 * tell minimum MTU (and I'll need to fragment it).
459 */
460 if (mtu < IPV6_MMTU)
461 mtu = IPV6_MMTU;
462 #endif
463 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
464 }
465 m_freem(m);
466 return;
467 }
468
469 if (rt->rt_flags & RTF_GATEWAY)
470 dst = (struct sockaddr_in6 *)rt->rt_gateway;
471
472 /*
473 * If we are to forward the packet using the same interface
474 * as one we got the packet from, perhaps we should send a redirect
475 * to sender to shortcut a hop.
476 * Only send redirect if source is sending directly to us,
477 * and if packet was not source routed (or has any options).
478 * Also, don't send redirect if forwarding using a route
479 * modified by a redirect.
480 */
481 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
482 #ifdef IPSEC
483 !ipsecrt &&
484 #endif
485 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
486 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
487 /*
488 * If the incoming interface is equal to the outgoing
489 * one, and the link attached to the interface is
490 * point-to-point, then it will be highly probable
491 * that a routing loop occurs. Thus, we immediately
492 * drop the packet and send an ICMPv6 error message.
493 *
494 * type/code is based on suggestion by Rich Draves.
495 * not sure if it is the best pick.
496 */
497 icmp6_error(mcopy, ICMP6_DST_UNREACH,
498 ICMP6_DST_UNREACH_ADDR, 0);
499 m_freem(m);
500 return;
501 }
502 type = ND_REDIRECT;
503 }
504
505 /*
506 * Check with the firewall...
507 */
508 if (ip6_fw_enable && ip6_fw_chk_ptr) {
509 u_short port = 0;
510 /* If ipfw says divert, we have to just drop packet */
511 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
512 m_freem(m);
513 goto freecopy;
514 }
515 if (!m)
516 goto freecopy;
517 }
518
519 /*
520 * Fake scoped addresses. Note that even link-local source or
521 * destinaion can appear, if the originating node just sends the
522 * packet to us (without address resolution for the destination).
523 * Since both icmp6_error and icmp6_redirect_output fill the embedded
524 * link identifiers, we can do this stuff after making a copy for
525 * returning an error.
526 */
527 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
528 /*
529 * See corresponding comments in ip6_output.
530 * XXX: but is it possible that ip6_forward() sends a packet
531 * to a loopback interface? I don't think so, and thus
532 * I bark here. (jinmei@kame.net)
533 * XXX: it is common to route invalid packets to loopback.
534 * also, the codepath will be visited on use of ::1 in
535 * rthdr. (itojun)
536 */
537 #if 1
538 if (0)
539 #else
540 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
541 #endif
542 {
543 printf("ip6_forward: outgoing interface is loopback. "
544 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
545 ip6_sprintf(&ip6->ip6_src),
546 ip6_sprintf(&ip6->ip6_dst),
547 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
548 if_name(rt->rt_ifp));
549 }
550
551 /* we can just use rcvif in forwarding. */
552 origifp = m->m_pkthdr.rcvif;
553 }
554 else
555 origifp = rt->rt_ifp;
556 /*
557 * clear embedded scope identifiers if necessary.
558 * in6_clearscope will touch the addresses only when necessary.
559 */
560 in6_clearscope(&ip6->ip6_src);
561 in6_clearscope(&ip6->ip6_dst);
562
563 #ifdef PFIL_HOOKS
564 /*
565 * Run through list of hooks for output packets.
566 */
567 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT);
568 if (error != 0)
569 goto senderr;
570 if (m == NULL)
571 goto freecopy;
572 ip6 = mtod(m, struct ip6_hdr *);
573 #endif /* PFIL_HOOKS */
574
575 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
576 if (error) {
577 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
578 ip6stat.ip6s_cantforward++;
579 } else {
580 ip6stat.ip6s_forward++;
581 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
582 if (type)
583 ip6stat.ip6s_redirectsent++;
584 else {
585 if (mcopy)
586 goto freecopy;
587 }
588 }
589
590 #ifdef PFIL_HOOKS
591 senderr:
592 #endif
593 if (mcopy == NULL)
594 return;
595 switch (error) {
596 case 0:
597 if (type == ND_REDIRECT) {
598 icmp6_redirect_output(mcopy, rt);
599 return;
600 }
601 goto freecopy;
602
603 case EMSGSIZE:
604 /* xxx MTU is constant in PPP? */
605 goto freecopy;
606
607 case ENOBUFS:
608 /* Tell source to slow down like source quench in IP? */
609 goto freecopy;
610
611 case ENETUNREACH: /* shouldn't happen, checked above */
612 case EHOSTUNREACH:
613 case ENETDOWN:
614 case EHOSTDOWN:
615 default:
616 type = ICMP6_DST_UNREACH;
617 code = ICMP6_DST_UNREACH_ADDR;
618 break;
619 }
620 icmp6_error(mcopy, type, code, 0);
621 return;
622
623 freecopy:
624 m_freem(mcopy);
625 return;
626 }
Cache object: 39f41e3ea8cffbd9728df72796823535
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