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 1.13 2006/12/22 23:57:53 swildner Exp $ */
3 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
4
5 /*
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
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.
20 *
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
31 * SUCH DAMAGE.
32 */
33
34 #include "opt_ip6fw.h"
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_ipsec.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 <netproto/key/key.h>
74 #endif /* IPSEC */
75
76 #ifdef FAST_IPSEC
77 #include <netproto/ipsec/ipsec.h>
78 #include <netproto/ipsec/ipsec6.h>
79 #include <netproto/ipsec/key.h>
80 #define IPSEC
81 #endif /* FAST_IPSEC */
82
83 #include <net/ip6fw/ip6_fw.h>
84
85 #include <net/net_osdep.h>
86
87 struct route_in6 ip6_forward_rt;
88
89 /*
90 * Forward a packet. If some error occurs return the sender
91 * an icmp packet. Note we can't always generate a meaningful
92 * icmp message because icmp doesn't have a large enough repertoire
93 * of codes and types.
94 *
95 * If not forwarding, just drop the packet. This could be confusing
96 * if ipforwarding was zero but some routing protocol was advancing
97 * us as a gateway to somewhere. However, we must let the routing
98 * protocol deal with that.
99 *
100 */
101
102 void
103 ip6_forward(struct mbuf *m, int srcrt)
104 {
105 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
106 struct sockaddr_in6 *dst;
107 struct rtentry *rt;
108 int error, type = 0, code = 0;
109 struct mbuf *mcopy = NULL;
110 struct ifnet *origifp; /* maybe unnecessary */
111 #ifdef IPSEC
112 struct secpolicy *sp = NULL;
113 #endif
114
115 #ifdef IPSEC
116 /*
117 * Check AH/ESP integrity.
118 */
119 /*
120 * Don't increment ip6s_cantforward because this is the check
121 * before forwarding packet actually.
122 */
123 if (ipsec6_in_reject(m, NULL)) {
124 #if !defined(FAST_IPSEC)
125 ipsec6stat.in_polvio++;
126 #endif
127 m_freem(m);
128 return;
129 }
130 #endif /* IPSEC */
131
132 /*
133 * Do not forward packets to multicast destination (should be handled
134 * by ip6_mforward().
135 * Do not forward packets with unspecified source. It was discussed
136 * in July 2000, on ipngwg mailing list.
137 */
138 if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 ||
139 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
140 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
141 ip6stat.ip6s_cantforward++;
142 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
143 if (ip6_log_time + ip6_log_interval < time_uptime) {
144 ip6_log_time = time_uptime;
145 log(LOG_DEBUG,
146 "cannot forward "
147 "from %s to %s nxt %d received on %s\n",
148 ip6_sprintf(&ip6->ip6_src),
149 ip6_sprintf(&ip6->ip6_dst),
150 ip6->ip6_nxt,
151 if_name(m->m_pkthdr.rcvif));
152 }
153 m_freem(m);
154 return;
155 }
156
157 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
158 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
159 icmp6_error(m, ICMP6_TIME_EXCEEDED,
160 ICMP6_TIME_EXCEED_TRANSIT, 0);
161 return;
162 }
163 ip6->ip6_hlim -= IPV6_HLIMDEC;
164
165 /*
166 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
167 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
168 * we need to generate an ICMP6 message to the src.
169 * Thanks to M_EXT, in most cases copy will not occur.
170 *
171 * It is important to save it before IPsec processing as IPsec
172 * processing may modify the mbuf.
173 */
174 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
175
176 #ifdef IPSEC
177 /* get a security policy for this packet */
178 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
179 &error);
180 if (sp == NULL) {
181 ipsec6stat.out_inval++;
182 ip6stat.ip6s_cantforward++;
183 if (mcopy) {
184 #if 0
185 /* XXX: what icmp ? */
186 #else
187 m_freem(mcopy);
188 #endif
189 }
190 m_freem(m);
191 return;
192 }
193
194 error = 0;
195
196 /* check policy */
197 switch (sp->policy) {
198 case IPSEC_POLICY_DISCARD:
199 /*
200 * This packet is just discarded.
201 */
202 ipsec6stat.out_polvio++;
203 ip6stat.ip6s_cantforward++;
204 key_freesp(sp);
205 if (mcopy) {
206 #if 0
207 /* XXX: what icmp ? */
208 #else
209 m_freem(mcopy);
210 #endif
211 }
212 m_freem(m);
213 return;
214
215 case IPSEC_POLICY_BYPASS:
216 case IPSEC_POLICY_NONE:
217 /* no need to do IPsec. */
218 key_freesp(sp);
219 goto skip_ipsec;
220
221 case IPSEC_POLICY_IPSEC:
222 if (sp->req == NULL) {
223 /* XXX should be panic ? */
224 kprintf("ip6_forward: No IPsec request specified.\n");
225 ip6stat.ip6s_cantforward++;
226 key_freesp(sp);
227 if (mcopy) {
228 #if 0
229 /* XXX: what icmp ? */
230 #else
231 m_freem(mcopy);
232 #endif
233 }
234 m_freem(m);
235 return;
236 }
237 /* do IPsec */
238 break;
239
240 case IPSEC_POLICY_ENTRUST:
241 default:
242 /* should be panic ?? */
243 kprintf("ip6_forward: Invalid policy found. %d\n", sp->policy);
244 key_freesp(sp);
245 goto skip_ipsec;
246 }
247
248 {
249 struct ipsec_output_state state;
250
251 /*
252 * All the extension headers will become inaccessible
253 * (since they can be encrypted).
254 * Don't panic, we need no more updates to extension headers
255 * on inner IPv6 packet (since they are now encapsulated).
256 *
257 * IPv6 [ESP|AH] IPv6 [extension headers] payload
258 */
259 bzero(&state, sizeof(state));
260 state.m = m;
261 state.ro = NULL; /* update at ipsec6_output_tunnel() */
262 state.dst = NULL; /* update at ipsec6_output_tunnel() */
263
264 error = ipsec6_output_tunnel(&state, sp, 0);
265
266 m = state.m;
267 key_freesp(sp);
268
269 if (error) {
270 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
271 switch (error) {
272 case EHOSTUNREACH:
273 case ENETUNREACH:
274 case EMSGSIZE:
275 case ENOBUFS:
276 case ENOMEM:
277 break;
278 default:
279 kprintf("ip6_output (ipsec): error code %d\n", error);
280 /* fall through */
281 case ENOENT:
282 /* don't show these error codes to the user */
283 break;
284 }
285 ip6stat.ip6s_cantforward++;
286 if (mcopy) {
287 #if 0
288 /* XXX: what icmp ? */
289 #else
290 m_freem(mcopy);
291 #endif
292 }
293 m_freem(m);
294 return;
295 }
296 }
297 skip_ipsec:
298 #endif /* IPSEC */
299
300 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
301 if (!srcrt) {
302 /*
303 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst
304 */
305 if (ip6_forward_rt.ro_rt == NULL ||
306 !(ip6_forward_rt.ro_rt->rt_flags & RTF_UP)) {
307 if (ip6_forward_rt.ro_rt) {
308 RTFREE(ip6_forward_rt.ro_rt);
309 ip6_forward_rt.ro_rt = 0;
310 }
311 /* this probably fails but give it a try again */
312 rtalloc_ign((struct route *)&ip6_forward_rt,
313 RTF_PRCLONING);
314 }
315
316 if (ip6_forward_rt.ro_rt == NULL) {
317 ip6stat.ip6s_noroute++;
318 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
319 if (mcopy) {
320 icmp6_error(mcopy, ICMP6_DST_UNREACH,
321 ICMP6_DST_UNREACH_NOROUTE, 0);
322 }
323 m_freem(m);
324 return;
325 }
326 } else if ((rt = ip6_forward_rt.ro_rt) == NULL ||
327 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
328 if (ip6_forward_rt.ro_rt) {
329 RTFREE(ip6_forward_rt.ro_rt);
330 ip6_forward_rt.ro_rt = 0;
331 }
332 bzero(dst, sizeof(*dst));
333 dst->sin6_len = sizeof(struct sockaddr_in6);
334 dst->sin6_family = AF_INET6;
335 dst->sin6_addr = ip6->ip6_dst;
336
337 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
338 if (ip6_forward_rt.ro_rt == NULL) {
339 ip6stat.ip6s_noroute++;
340 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
341 if (mcopy) {
342 icmp6_error(mcopy, ICMP6_DST_UNREACH,
343 ICMP6_DST_UNREACH_NOROUTE, 0);
344 }
345 m_freem(m);
346 return;
347 }
348 }
349 rt = ip6_forward_rt.ro_rt;
350
351 /*
352 * Scope check: if a packet can't be delivered to its destination
353 * for the reason that the destination is beyond the scope of the
354 * source address, discard the packet and return an icmp6 destination
355 * unreachable error with Code 2 (beyond scope of source address).
356 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
357 */
358 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
359 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
360 ip6stat.ip6s_cantforward++;
361 ip6stat.ip6s_badscope++;
362 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
363
364 if (ip6_log_time + ip6_log_interval < time_uptime) {
365 ip6_log_time = time_uptime;
366 log(LOG_DEBUG,
367 "cannot forward "
368 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
369 ip6_sprintf(&ip6->ip6_src),
370 ip6_sprintf(&ip6->ip6_dst),
371 ip6->ip6_nxt,
372 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
373 }
374 if (mcopy)
375 icmp6_error(mcopy, ICMP6_DST_UNREACH,
376 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
377 m_freem(m);
378 return;
379 }
380
381 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) {
382 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
383 if (mcopy) {
384 u_long mtu;
385 #ifdef IPSEC
386 struct secpolicy *sp;
387 int ipsecerror;
388 size_t ipsechdrsiz;
389 #endif
390
391 mtu = rt->rt_ifp->if_mtu;
392 #ifdef IPSEC
393 /*
394 * When we do IPsec tunnel ingress, we need to play
395 * with if_mtu value (decrement IPsec header size
396 * from mtu value). The code is much simpler than v4
397 * case, as we have the outgoing interface for
398 * encapsulated packet as "rt->rt_ifp".
399 */
400 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
401 IP_FORWARDING, &ipsecerror);
402 if (sp) {
403 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
404 IPSEC_DIR_OUTBOUND, NULL);
405 if (ipsechdrsiz < mtu)
406 mtu -= ipsechdrsiz;
407 }
408
409 /*
410 * if mtu becomes less than minimum MTU,
411 * tell minimum MTU (and I'll need to fragment it).
412 */
413 if (mtu < IPV6_MMTU)
414 mtu = IPV6_MMTU;
415 #endif
416 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
417 }
418 m_freem(m);
419 return;
420 }
421
422 if (rt->rt_flags & RTF_GATEWAY)
423 dst = (struct sockaddr_in6 *)rt->rt_gateway;
424
425 /*
426 * If we are to forward the packet using the same interface
427 * as one we got the packet from, perhaps we should send a redirect
428 * to sender to shortcut a hop.
429 * Only send redirect if source is sending directly to us,
430 * and if packet was not source routed (or has any options).
431 * Also, don't send redirect if forwarding using a route
432 * modified by a redirect.
433 */
434 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
435 (rt->rt_flags & (RTF_DYNAMIC | RTF_MODIFIED)) == 0) {
436 if (rt->rt_ifp->if_flags & IFF_POINTOPOINT) {
437 /*
438 * If the incoming interface is equal to the outgoing
439 * one, and the link attached to the interface is
440 * point-to-point, then it will be highly probable
441 * that a routing loop occurs. Thus, we immediately
442 * drop the packet and send an ICMPv6 error message.
443 *
444 * type/code is based on suggestion by Rich Draves.
445 * not sure if it is the best pick.
446 */
447 icmp6_error(mcopy, ICMP6_DST_UNREACH,
448 ICMP6_DST_UNREACH_ADDR, 0);
449 m_freem(m);
450 return;
451 }
452 type = ND_REDIRECT;
453 }
454
455 /*
456 * Check with the firewall...
457 */
458 if (ip6_fw_enable && ip6_fw_chk_ptr) {
459 u_short port = 0;
460 /* If ipfw says divert, we have to just drop packet */
461 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
462 m_freem(m);
463 goto freecopy;
464 }
465 if (!m)
466 goto freecopy;
467 }
468
469 /*
470 * Fake scoped addresses. Note that even link-local source or
471 * destinaion can appear, if the originating node just sends the
472 * packet to us (without address resolution for the destination).
473 * Since both icmp6_error and icmp6_redirect_output fill the embedded
474 * link identifiers, we can do this stuff after making a copy for
475 * returning an error.
476 */
477 if (rt->rt_ifp->if_flags & IFF_LOOPBACK) {
478 /*
479 * See corresponding comments in ip6_output.
480 * XXX: but is it possible that ip6_forward() sends a packet
481 * to a loopback interface? I don't think so, and thus
482 * I bark here. (jinmei@kame.net)
483 * XXX: it is common to route invalid packets to loopback.
484 * also, the codepath will be visited on use of ::1 in
485 * rthdr. (itojun)
486 */
487 #if 1
488 if (0)
489 #else
490 if ((rt->rt_flags & (RTF_BLACKHOLE | RTF_REJECT)) == 0)
491 #endif
492 {
493 kprintf("ip6_forward: outgoing interface is loopback. "
494 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
495 ip6_sprintf(&ip6->ip6_src),
496 ip6_sprintf(&ip6->ip6_dst),
497 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
498 if_name(rt->rt_ifp));
499 }
500
501 /* we can just use rcvif in forwarding. */
502 origifp = m->m_pkthdr.rcvif;
503 }
504 else
505 origifp = rt->rt_ifp;
506 /*
507 * clear embedded scope identifiers if necessary.
508 * in6_clearscope will touch the addresses only when necessary.
509 */
510 in6_clearscope(&ip6->ip6_src);
511 in6_clearscope(&ip6->ip6_dst);
512
513 /*
514 * Run through list of hooks for output packets.
515 */
516 if (pfil_has_hooks(&inet6_pfil_hook)) {
517 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp,
518 PFIL_OUT);
519 if (error != 0)
520 goto senderr;
521 if (m == NULL)
522 goto freecopy;
523 ip6 = mtod(m, struct ip6_hdr *);
524 }
525
526 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
527 if (error) {
528 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
529 ip6stat.ip6s_cantforward++;
530 } else {
531 ip6stat.ip6s_forward++;
532 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
533 if (type)
534 ip6stat.ip6s_redirectsent++;
535 else {
536 if (mcopy)
537 goto freecopy;
538 }
539 }
540 senderr:
541 if (mcopy == NULL)
542 return;
543 switch (error) {
544 case 0:
545 #if 1
546 if (type == ND_REDIRECT) {
547 icmp6_redirect_output(mcopy, rt);
548 return;
549 }
550 #endif
551 goto freecopy;
552
553 case EMSGSIZE:
554 /* xxx MTU is constant in PPP? */
555 goto freecopy;
556
557 case ENOBUFS:
558 /* Tell source to slow down like source quench in IP? */
559 goto freecopy;
560
561 case ENETUNREACH: /* shouldn't happen, checked above */
562 case EHOSTUNREACH:
563 case ENETDOWN:
564 case EHOSTDOWN:
565 default:
566 type = ICMP6_DST_UNREACH;
567 code = ICMP6_DST_UNREACH_ADDR;
568 break;
569 }
570 icmp6_error(mcopy, type, code, 0);
571 return;
572
573 freecopy:
574 m_freem(mcopy);
575 return;
576 }
Cache object: 2acaec987b26ee5c1095c2fc6b4d8a77
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