1 /* $FreeBSD: releng/5.1/sys/netinet6/ip6_forward.c 105199 2002-10-16 02:25:05Z sam $ */
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
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/malloc.h>
41 #include <sys/mbuf.h>
42 #include <sys/domain.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
45 #include <sys/errno.h>
46 #include <sys/time.h>
47 #include <sys/kernel.h>
48 #include <sys/syslog.h>
49
50 #include <net/if.h>
51 #include <net/route.h>
52 #ifdef PFIL_HOOKS
53 #include <net/pfil.h>
54 #endif
55
56 #include <netinet/in.h>
57 #include <netinet/in_var.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/ip.h>
60 #include <netinet/ip_var.h>
61 #include <netinet6/in6_var.h>
62 #include <netinet/ip6.h>
63 #include <netinet6/ip6_var.h>
64 #include <netinet/icmp6.h>
65 #include <netinet6/nd6.h>
66
67 #include <netinet/in_pcb.h>
68
69 #ifdef IPSEC
70 #include <netinet6/ipsec.h>
71 #ifdef INET6
72 #include <netinet6/ipsec6.h>
73 #endif
74 #include <netkey/key.h>
75 #endif /* IPSEC */
76
77 #ifdef FAST_IPSEC
78 #include <netipsec/ipsec.h>
79 #include <netipsec/ipsec6.h>
80 #include <netipsec/key.h>
81 #define IPSEC
82 #endif /* FAST_IPSEC */
83
84 #include <netinet6/ip6_fw.h>
85
86 #include <net/net_osdep.h>
87
88 #include <netinet6/ip6protosw.h>
89
90 struct route_in6 ip6_forward_rt;
91
92 /*
93 * Forward a packet. If some error occurs return the sender
94 * an icmp packet. Note we can't always generate a meaningful
95 * icmp message because icmp doesn't have a large enough repertoire
96 * of codes and types.
97 *
98 * If not forwarding, just drop the packet. This could be confusing
99 * if ipforwarding was zero but some routing protocol was advancing
100 * us as a gateway to somewhere. However, we must let the routing
101 * protocol deal with that.
102 *
103 */
104
105 void
106 ip6_forward(m, srcrt)
107 struct mbuf *m;
108 int srcrt;
109 {
110 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
111 struct sockaddr_in6 *dst;
112 struct rtentry *rt;
113 int error, type = 0, code = 0;
114 struct mbuf *mcopy = NULL;
115 struct ifnet *origifp; /* maybe unnecessary */
116 #ifdef PFIL_HOOKS
117 struct packet_filter_hook *pfh;
118 struct mbuf *m1;
119 int rv;
120 #endif /* PFIL_HOOKS */
121 #ifdef IPSEC
122 struct secpolicy *sp = NULL;
123 #endif
124
125 #ifdef IPSEC
126 /*
127 * Check AH/ESP integrity.
128 */
129 /*
130 * Don't increment ip6s_cantforward because this is the check
131 * before forwarding packet actually.
132 */
133 if (ipsec6_in_reject(m, NULL)) {
134 #if !defined(FAST_IPSEC)
135 ipsec6stat.in_polvio++;
136 #endif
137 m_freem(m);
138 return;
139 }
140 #endif /* IPSEC */
141
142 /*
143 * Do not forward packets to multicast destination (should be handled
144 * by ip6_mforward().
145 * Do not forward packets with unspecified source. It was discussed
146 * in July 2000, on ipngwg mailing list.
147 */
148 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
149 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
150 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
151 ip6stat.ip6s_cantforward++;
152 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
153 if (ip6_log_time + ip6_log_interval < time_second) {
154 ip6_log_time = time_second;
155 log(LOG_DEBUG,
156 "cannot forward "
157 "from %s to %s nxt %d received on %s\n",
158 ip6_sprintf(&ip6->ip6_src),
159 ip6_sprintf(&ip6->ip6_dst),
160 ip6->ip6_nxt,
161 if_name(m->m_pkthdr.rcvif));
162 }
163 m_freem(m);
164 return;
165 }
166
167 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
168 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
169 icmp6_error(m, ICMP6_TIME_EXCEEDED,
170 ICMP6_TIME_EXCEED_TRANSIT, 0);
171 return;
172 }
173 ip6->ip6_hlim -= IPV6_HLIMDEC;
174
175 /*
176 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
177 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
178 * we need to generate an ICMP6 message to the src.
179 * Thanks to M_EXT, in most cases copy will not occur.
180 *
181 * It is important to save it before IPsec processing as IPsec
182 * processing may modify the mbuf.
183 */
184 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
185
186 #ifdef IPSEC
187 /* get a security policy for this packet */
188 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
189 &error);
190 if (sp == NULL) {
191 ipsec6stat.out_inval++;
192 ip6stat.ip6s_cantforward++;
193 if (mcopy) {
194 #if 0
195 /* XXX: what icmp ? */
196 #else
197 m_freem(mcopy);
198 #endif
199 }
200 m_freem(m);
201 return;
202 }
203
204 error = 0;
205
206 /* check policy */
207 switch (sp->policy) {
208 case IPSEC_POLICY_DISCARD:
209 /*
210 * This packet is just discarded.
211 */
212 ipsec6stat.out_polvio++;
213 ip6stat.ip6s_cantforward++;
214 key_freesp(sp);
215 if (mcopy) {
216 #if 0
217 /* XXX: what icmp ? */
218 #else
219 m_freem(mcopy);
220 #endif
221 }
222 m_freem(m);
223 return;
224
225 case IPSEC_POLICY_BYPASS:
226 case IPSEC_POLICY_NONE:
227 /* no need to do IPsec. */
228 key_freesp(sp);
229 goto skip_ipsec;
230
231 case IPSEC_POLICY_IPSEC:
232 if (sp->req == NULL) {
233 /* XXX should be panic ? */
234 printf("ip6_forward: No IPsec request specified.\n");
235 ip6stat.ip6s_cantforward++;
236 key_freesp(sp);
237 if (mcopy) {
238 #if 0
239 /* XXX: what icmp ? */
240 #else
241 m_freem(mcopy);
242 #endif
243 }
244 m_freem(m);
245 return;
246 }
247 /* do IPsec */
248 break;
249
250 case IPSEC_POLICY_ENTRUST:
251 default:
252 /* should be panic ?? */
253 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
254 key_freesp(sp);
255 goto skip_ipsec;
256 }
257
258 {
259 struct ipsec_output_state state;
260
261 /*
262 * All the extension headers will become inaccessible
263 * (since they can be encrypted).
264 * Don't panic, we need no more updates to extension headers
265 * on inner IPv6 packet (since they are now encapsulated).
266 *
267 * IPv6 [ESP|AH] IPv6 [extension headers] payload
268 */
269 bzero(&state, sizeof(state));
270 state.m = m;
271 state.ro = NULL; /* update at ipsec6_output_tunnel() */
272 state.dst = NULL; /* update at ipsec6_output_tunnel() */
273
274 error = ipsec6_output_tunnel(&state, sp, 0);
275
276 m = state.m;
277 key_freesp(sp);
278
279 if (error) {
280 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
281 switch (error) {
282 case EHOSTUNREACH:
283 case ENETUNREACH:
284 case EMSGSIZE:
285 case ENOBUFS:
286 case ENOMEM:
287 break;
288 default:
289 printf("ip6_output (ipsec): error code %d\n", error);
290 /* fall through */
291 case ENOENT:
292 /* don't show these error codes to the user */
293 break;
294 }
295 ip6stat.ip6s_cantforward++;
296 if (mcopy) {
297 #if 0
298 /* XXX: what icmp ? */
299 #else
300 m_freem(mcopy);
301 #endif
302 }
303 m_freem(m);
304 return;
305 }
306 }
307 skip_ipsec:
308 #endif /* IPSEC */
309
310 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
311 if (!srcrt) {
312 /*
313 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
314 */
315 if (ip6_forward_rt.ro_rt == 0 ||
316 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
317 if (ip6_forward_rt.ro_rt) {
318 RTFREE(ip6_forward_rt.ro_rt);
319 ip6_forward_rt.ro_rt = 0;
320 }
321 /* this probably fails but give it a try again */
322 rtalloc_ign((struct route *)&ip6_forward_rt,
323 RTF_PRCLONING);
324 }
325
326 if (ip6_forward_rt.ro_rt == 0) {
327 ip6stat.ip6s_noroute++;
328 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
329 if (mcopy) {
330 icmp6_error(mcopy, ICMP6_DST_UNREACH,
331 ICMP6_DST_UNREACH_NOROUTE, 0);
332 }
333 m_freem(m);
334 return;
335 }
336 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
337 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
338 if (ip6_forward_rt.ro_rt) {
339 RTFREE(ip6_forward_rt.ro_rt);
340 ip6_forward_rt.ro_rt = 0;
341 }
342 bzero(dst, sizeof(*dst));
343 dst->sin6_len = sizeof(struct sockaddr_in6);
344 dst->sin6_family = AF_INET6;
345 dst->sin6_addr = ip6->ip6_dst;
346
347 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
348 if (ip6_forward_rt.ro_rt == 0) {
349 ip6stat.ip6s_noroute++;
350 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
351 if (mcopy) {
352 icmp6_error(mcopy, ICMP6_DST_UNREACH,
353 ICMP6_DST_UNREACH_NOROUTE, 0);
354 }
355 m_freem(m);
356 return;
357 }
358 }
359 rt = ip6_forward_rt.ro_rt;
360
361 /*
362 * Scope check: if a packet can't be delivered to its destination
363 * for the reason that the destination is beyond the scope of the
364 * source address, discard the packet and return an icmp6 destination
365 * unreachable error with Code 2 (beyond scope of source address).
366 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
367 */
368 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
369 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
370 ip6stat.ip6s_cantforward++;
371 ip6stat.ip6s_badscope++;
372 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
373
374 if (ip6_log_time + ip6_log_interval < time_second) {
375 ip6_log_time = time_second;
376 log(LOG_DEBUG,
377 "cannot forward "
378 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
379 ip6_sprintf(&ip6->ip6_src),
380 ip6_sprintf(&ip6->ip6_dst),
381 ip6->ip6_nxt,
382 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
383 }
384 if (mcopy)
385 icmp6_error(mcopy, ICMP6_DST_UNREACH,
386 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
387 m_freem(m);
388 return;
389 }
390
391 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
392 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
393 if (mcopy) {
394 u_long mtu;
395 #ifdef IPSEC
396 struct secpolicy *sp;
397 int ipsecerror;
398 size_t ipsechdrsiz;
399 #endif
400
401 mtu = rt->rt_ifp->if_mtu;
402 #ifdef IPSEC
403 /*
404 * When we do IPsec tunnel ingress, we need to play
405 * with if_mtu value (decrement IPsec header size
406 * from mtu value). The code is much simpler than v4
407 * case, as we have the outgoing interface for
408 * encapsulated packet as "rt->rt_ifp".
409 */
410 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
411 IP_FORWARDING, &ipsecerror);
412 if (sp) {
413 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
414 IPSEC_DIR_OUTBOUND, NULL);
415 if (ipsechdrsiz < mtu)
416 mtu -= ipsechdrsiz;
417 }
418
419 /*
420 * if mtu becomes less than minimum MTU,
421 * tell minimum MTU (and I'll need to fragment it).
422 */
423 if (mtu < IPV6_MMTU)
424 mtu = IPV6_MMTU;
425 #endif
426 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
427 }
428 m_freem(m);
429 return;
430 }
431
432 if (rt->rt_flags & RTF_GATEWAY)
433 dst = (struct sockaddr_in6 *)rt->rt_gateway;
434
435 /*
436 * If we are to forward the packet using the same interface
437 * as one we got the packet from, perhaps we should send a redirect
438 * to sender to shortcut a hop.
439 * Only send redirect if source is sending directly to us,
440 * and if packet was not source routed (or has any options).
441 * Also, don't send redirect if forwarding using a route
442 * modified by a redirect.
443 */
444 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
445 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
446 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
447 /*
448 * If the incoming interface is equal to the outgoing
449 * one, and the link attached to the interface is
450 * point-to-point, then it will be highly probable
451 * that a routing loop occurs. Thus, we immediately
452 * drop the packet and send an ICMPv6 error message.
453 *
454 * type/code is based on suggestion by Rich Draves.
455 * not sure if it is the best pick.
456 */
457 icmp6_error(mcopy, ICMP6_DST_UNREACH,
458 ICMP6_DST_UNREACH_ADDR, 0);
459 m_freem(m);
460 return;
461 }
462 type = ND_REDIRECT;
463 }
464
465 /*
466 * Check with the firewall...
467 */
468 if (ip6_fw_enable && ip6_fw_chk_ptr) {
469 u_short port = 0;
470 /* If ipfw says divert, we have to just drop packet */
471 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
472 m_freem(m);
473 goto freecopy;
474 }
475 if (!m)
476 goto freecopy;
477 }
478
479 /*
480 * Fake scoped addresses. Note that even link-local source or
481 * destinaion can appear, if the originating node just sends the
482 * packet to us (without address resolution for the destination).
483 * Since both icmp6_error and icmp6_redirect_output fill the embedded
484 * link identifiers, we can do this stuff after making a copy for
485 * returning an error.
486 */
487 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
488 /*
489 * See corresponding comments in ip6_output.
490 * XXX: but is it possible that ip6_forward() sends a packet
491 * to a loopback interface? I don't think so, and thus
492 * I bark here. (jinmei@kame.net)
493 * XXX: it is common to route invalid packets to loopback.
494 * also, the codepath will be visited on use of ::1 in
495 * rthdr. (itojun)
496 */
497 #if 1
498 if (0)
499 #else
500 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
501 #endif
502 {
503 printf("ip6_forward: outgoing interface is loopback. "
504 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
505 ip6_sprintf(&ip6->ip6_src),
506 ip6_sprintf(&ip6->ip6_dst),
507 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
508 if_name(rt->rt_ifp));
509 }
510
511 /* we can just use rcvif in forwarding. */
512 origifp = m->m_pkthdr.rcvif;
513 }
514 else
515 origifp = rt->rt_ifp;
516 #ifndef SCOPEDROUTING
517 /*
518 * clear embedded scope identifiers if necessary.
519 * in6_clearscope will touch the addresses only when necessary.
520 */
521 in6_clearscope(&ip6->ip6_src);
522 in6_clearscope(&ip6->ip6_dst);
523 #endif
524
525 #ifdef PFIL_HOOKS
526 /*
527 * Run through list of hooks for output packets.
528 */
529 m1 = m;
530 pfh = pfil_hook_get(PFIL_OUT, &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh);
531 for (; pfh; pfh = pfh->pfil_link.tqe_next)
532 if (pfh->pfil_func) {
533 rv = pfh->pfil_func(ip6, sizeof(*ip6),
534 rt->rt_ifp, 1, &m1);
535 if (rv) {
536 error = EHOSTUNREACH;
537 goto freecopy;
538 }
539 m = m1;
540 if (m == NULL)
541 goto freecopy;
542 ip6 = mtod(m, struct ip6_hdr *);
543 }
544 #endif /* PFIL_HOOKS */
545
546 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
547 if (error) {
548 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
549 ip6stat.ip6s_cantforward++;
550 } else {
551 ip6stat.ip6s_forward++;
552 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
553 if (type)
554 ip6stat.ip6s_redirectsent++;
555 else {
556 if (mcopy)
557 goto freecopy;
558 }
559 }
560 if (mcopy == NULL)
561 return;
562 switch (error) {
563 case 0:
564 #if 1
565 if (type == ND_REDIRECT) {
566 icmp6_redirect_output(mcopy, rt);
567 return;
568 }
569 #endif
570 goto freecopy;
571
572 case EMSGSIZE:
573 /* xxx MTU is constant in PPP? */
574 goto freecopy;
575
576 case ENOBUFS:
577 /* Tell source to slow down like source quench in IP? */
578 goto freecopy;
579
580 case ENETUNREACH: /* shouldn't happen, checked above */
581 case EHOSTUNREACH:
582 case ENETDOWN:
583 case EHOSTDOWN:
584 default:
585 type = ICMP6_DST_UNREACH;
586 code = ICMP6_DST_UNREACH_ADDR;
587 break;
588 }
589 icmp6_error(mcopy, type, code, 0);
590 return;
591
592 freecopy:
593 m_freem(mcopy);
594 return;
595 }
Cache object: 305f494673b3d7e6e244476e624eb74c
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