1/* $FreeBSD: head/sys/netinet6/ip6_forward.c 121283 2003-10-20 15:27:48Z ume $ */
|
| 1/* $FreeBSD: head/sys/netinet6/ip6_forward.c 121315 2003-10-21 20:05:32Z ume $ */ |
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
91struct 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
106void
107ip6_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;
113 struct rtentry *rt;
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#endif
121
122#ifdef IPSEC
123 /*
124 * Check AH/ESP integrity.
125 */
126 /*
127 * Don't increment ip6s_cantforward because this is the check
128 * before forwarding packet actually.
129 */
130 if (ipsec6_in_reject(m, NULL)) {
131#if !defined(FAST_IPSEC)
132 ipsec6stat.in_polvio++;
133#endif
134 m_freem(m);
135 return;
136 }
137#endif /* IPSEC */
138
139 /*
140 * Do not forward packets to multicast destination (should be handled
141 * by ip6_mforward().
142 * Do not forward packets with unspecified source. It was discussed
143 * in July 2000, on the ipngwg mailing list.
144 */
145 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
146 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
147 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
148 ip6stat.ip6s_cantforward++;
149 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
150 if (ip6_log_time + ip6_log_interval < time_second) {
151 ip6_log_time = time_second;
152 log(LOG_DEBUG,
153 "cannot forward "
154 "from %s to %s nxt %d received on %s\n",
155 ip6_sprintf(&ip6->ip6_src),
156 ip6_sprintf(&ip6->ip6_dst),
157 ip6->ip6_nxt,
158 if_name(m->m_pkthdr.rcvif));
159 }
160 m_freem(m);
161 return;
162 }
163
164 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
165 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
166 icmp6_error(m, ICMP6_TIME_EXCEEDED,
167 ICMP6_TIME_EXCEED_TRANSIT, 0);
168 return;
169 }
170 ip6->ip6_hlim -= IPV6_HLIMDEC;
171
172 /*
173 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
174 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
175 * we need to generate an ICMP6 message to the src.
176 * Thanks to M_EXT, in most cases copy will not occur.
177 *
178 * It is important to save it before IPsec processing as IPsec
179 * processing may modify the mbuf.
180 */
181 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
182
183#ifdef IPSEC
184 /* get a security policy for this packet */
185 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
186 IP_FORWARDING, &error);
187 if (sp == NULL) {
188 ipsec6stat.out_inval++;
189 ip6stat.ip6s_cantforward++;
190 if (mcopy) {
191#if 0
192 /* XXX: what icmp ? */
193#else
194 m_freem(mcopy);
195#endif
196 }
197 m_freem(m);
198 return;
199 }
200
201 error = 0;
202
203 /* check policy */
204 switch (sp->policy) {
205 case IPSEC_POLICY_DISCARD:
206 /*
207 * This packet is just discarded.
208 */
209 ipsec6stat.out_polvio++;
210 ip6stat.ip6s_cantforward++;
211 key_freesp(sp);
212 if (mcopy) {
213#if 0
214 /* XXX: what icmp ? */
215#else
216 m_freem(mcopy);
217#endif
218 }
219 m_freem(m);
220 return;
221
222 case IPSEC_POLICY_BYPASS:
223 case IPSEC_POLICY_NONE:
224 /* no need to do IPsec. */
225 key_freesp(sp);
226 goto skip_ipsec;
227
228 case IPSEC_POLICY_IPSEC:
229 if (sp->req == NULL) {
230 /* XXX should be panic ? */
231 printf("ip6_forward: No IPsec request specified.\n");
232 ip6stat.ip6s_cantforward++;
233 key_freesp(sp);
234 if (mcopy) {
235#if 0
236 /* XXX: what icmp ? */
237#else
238 m_freem(mcopy);
239#endif
240 }
241 m_freem(m);
242 return;
243 }
244 /* do IPsec */
245 break;
246
247 case IPSEC_POLICY_ENTRUST:
248 default:
249 /* should be panic ?? */
250 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
251 key_freesp(sp);
252 goto skip_ipsec;
253 }
254
255 {
256 struct ipsec_output_state state;
257
258 /*
259 * All the extension headers will become inaccessible
260 * (since they can be encrypted).
261 * Don't panic, we need no more updates to extension headers
262 * on inner IPv6 packet (since they are now encapsulated).
263 *
264 * IPv6 [ESP|AH] IPv6 [extension headers] payload
265 */
266 bzero(&state, sizeof(state));
267 state.m = m;
268 state.ro = NULL; /* update at ipsec6_output_tunnel() */
269 state.dst = NULL; /* update at ipsec6_output_tunnel() */
270
271 error = ipsec6_output_tunnel(&state, sp, 0);
272
273 m = state.m;
274 key_freesp(sp);
275
276 if (error) {
277 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
278 switch (error) {
279 case EHOSTUNREACH:
280 case ENETUNREACH:
281 case EMSGSIZE:
282 case ENOBUFS:
283 case ENOMEM:
284 break;
285 default:
286 printf("ip6_output (ipsec): error code %d\n", error);
287 /* FALLTHROUGH */
288 case ENOENT:
289 /* don't show these error codes to the user */
290 break;
291 }
292 ip6stat.ip6s_cantforward++;
293 if (mcopy) {
294#if 0
295 /* XXX: what icmp ? */
296#else
297 m_freem(mcopy);
298#endif
299 }
300 m_freem(m);
301 return;
302 }
303 }
304 skip_ipsec:
305#endif /* IPSEC */
306
307 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
308 if (!srcrt) {
309 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
310 if (ip6_forward_rt.ro_rt == 0 ||
311 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
312 if (ip6_forward_rt.ro_rt) {
313 RTFREE(ip6_forward_rt.ro_rt);
314 ip6_forward_rt.ro_rt = 0;
315 }
316
317 /* this probably fails but give it a try again */
318 rtalloc_ign((struct route *)&ip6_forward_rt,
319 RTF_PRCLONING);
320 }
321
322 if (ip6_forward_rt.ro_rt == 0) {
323 ip6stat.ip6s_noroute++;
324 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
325 if (mcopy) {
326 icmp6_error(mcopy, ICMP6_DST_UNREACH,
327 ICMP6_DST_UNREACH_NOROUTE, 0);
328 }
329 m_freem(m);
330 return;
331 }
332 } else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
333 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
334 if (ip6_forward_rt.ro_rt) {
335 RTFREE(ip6_forward_rt.ro_rt);
336 ip6_forward_rt.ro_rt = 0;
337 }
338 bzero(dst, sizeof(*dst));
339 dst->sin6_len = sizeof(struct sockaddr_in6);
340 dst->sin6_family = AF_INET6;
341 dst->sin6_addr = ip6->ip6_dst;
342
343 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING);
344 if (ip6_forward_rt.ro_rt == 0) {
345 ip6stat.ip6s_noroute++;
346 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
347 if (mcopy) {
348 icmp6_error(mcopy, ICMP6_DST_UNREACH,
349 ICMP6_DST_UNREACH_NOROUTE, 0);
350 }
351 m_freem(m);
352 return;
353 }
354 }
355 rt = ip6_forward_rt.ro_rt;
356
357 /*
358 * Scope check: if a packet can't be delivered to its destination
359 * for the reason that the destination is beyond the scope of the
360 * source address, discard the packet and return an icmp6 destination
361 * unreachable error with Code 2 (beyond scope of source address).
362 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
363 */
|
363 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) !=
364 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) {
|
364 if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
365 in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone) ||
366 srczone != dstzone) { |
367 ip6stat.ip6s_cantforward++;
368 ip6stat.ip6s_badscope++;
369 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
370
371 if (ip6_log_time + ip6_log_interval < time_second) {
372 ip6_log_time = time_second;
373 log(LOG_DEBUG,
374 "cannot forward "
375 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
376 ip6_sprintf(&ip6->ip6_src),
377 ip6_sprintf(&ip6->ip6_dst),
378 ip6->ip6_nxt,
379 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
380 }
381 if (mcopy)
382 icmp6_error(mcopy, ICMP6_DST_UNREACH,
383 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
384 m_freem(m);
385 return;
386 }
387
388 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
389 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
390 if (mcopy) {
391 u_long mtu;
392#ifdef IPSEC
393 struct secpolicy *sp;
394 int ipsecerror;
395 size_t ipsechdrsiz;
396#endif
397
398 mtu = IN6_LINKMTU(rt->rt_ifp);
399#ifdef IPSEC
400 /*
401 * When we do IPsec tunnel ingress, we need to play
402 * with if_mtu value (decrement IPsec header size
403 * from mtu value). The code is much simpler than v4
404 * case, as we have the outgoing interface for
405 * encapsulated packet as "rt->rt_ifp".
406 */
407 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
408 IP_FORWARDING, &ipsecerror);
409 if (sp) {
410 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
411 IPSEC_DIR_OUTBOUND, NULL);
412 if (ipsechdrsiz < mtu)
413 mtu -= ipsechdrsiz;
414 }
415
416 /*
417 * if mtu becomes less than minimum MTU,
418 * tell minimum MTU (and I'll need to fragment it).
419 */
420 if (mtu < IPV6_MMTU)
421 mtu = IPV6_MMTU;
422#endif
423 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
424 }
425 m_freem(m);
426 return;
427 }
428
429 if (rt->rt_flags & RTF_GATEWAY)
430 dst = (struct sockaddr_in6 *)rt->rt_gateway;
431
432 /*
433 * If we are to forward the packet using the same interface
434 * as one we got the packet from, perhaps we should send a redirect
435 * to sender to shortcut a hop.
436 * Only send redirect if source is sending directly to us,
437 * and if packet was not source routed (or has any options).
438 * Also, don't send redirect if forwarding using a route
439 * modified by a redirect.
440 */
441 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
442 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
443 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
444 /*
445 * If the incoming interface is equal to the outgoing
446 * one, and the link attached to the interface is
447 * point-to-point, then it will be highly probable
448 * that a routing loop occurs. Thus, we immediately
449 * drop the packet and send an ICMPv6 error message.
450 *
451 * type/code is based on suggestion by Rich Draves.
452 * not sure if it is the best pick.
453 */
454 icmp6_error(mcopy, ICMP6_DST_UNREACH,
455 ICMP6_DST_UNREACH_ADDR, 0);
456 m_freem(m);
457 return;
458 }
459 type = ND_REDIRECT;
460 }
461
462 /*
463 * Check with the firewall...
464 */
465 if (ip6_fw_enable && ip6_fw_chk_ptr) {
466 u_short port = 0;
467 /* If ipfw says divert, we have to just drop packet */
468 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
469 m_freem(m);
470 goto freecopy;
471 }
472 if (!m)
473 goto freecopy;
474 }
475
476 /*
477 * Fake scoped addresses. Note that even link-local source or
478 * destinaion can appear, if the originating node just sends the
479 * packet to us (without address resolution for the destination).
480 * Since both icmp6_error and icmp6_redirect_output fill the embedded
481 * link identifiers, we can do this stuff after making a copy for
482 * returning an error.
483 */
484 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
485 /*
486 * See corresponding comments in ip6_output.
487 * XXX: but is it possible that ip6_forward() sends a packet
488 * to a loopback interface? I don't think so, and thus
489 * I bark here. (jinmei@kame.net)
490 * XXX: it is common to route invalid packets to loopback.
491 * also, the codepath will be visited on use of ::1 in
492 * rthdr. (itojun)
493 */
494#if 1
495 if (0)
496#else
497 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
498#endif
499 {
500 printf("ip6_forward: outgoing interface is loopback. "
501 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
502 ip6_sprintf(&ip6->ip6_src),
503 ip6_sprintf(&ip6->ip6_dst),
504 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
505 if_name(rt->rt_ifp));
506 }
507
508 /* we can just use rcvif in forwarding. */
509 origifp = m->m_pkthdr.rcvif;
510 }
511 else
512 origifp = rt->rt_ifp;
513 /*
514 * clear embedded scope identifiers if necessary.
515 * in6_clearscope will touch the addresses only when necessary.
516 */
517 in6_clearscope(&ip6->ip6_src);
518 in6_clearscope(&ip6->ip6_dst);
519
520#ifdef PFIL_HOOKS
521 /*
522 * Run through list of hooks for output packets.
523 */
524 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT);
525 if (error != 0)
526 goto senderr;
527 if (m == NULL)
528 goto freecopy;
529 ip6 = mtod(m, struct ip6_hdr *);
530#endif /* PFIL_HOOKS */
531
532 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
533 if (error) {
534 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
535 ip6stat.ip6s_cantforward++;
536 } else {
537 ip6stat.ip6s_forward++;
538 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
539 if (type)
540 ip6stat.ip6s_redirectsent++;
541 else {
542 if (mcopy)
543 goto freecopy;
544 }
545 }
546
547#ifdef PFIL_HOOKS
548senderr:
549#endif
550 if (mcopy == NULL)
551 return;
552 switch (error) {
553 case 0:
554 if (type == ND_REDIRECT) {
555 icmp6_redirect_output(mcopy, rt);
556 return;
557 }
558 goto freecopy;
559
560 case EMSGSIZE:
561 /* xxx MTU is constant in PPP? */
562 goto freecopy;
563
564 case ENOBUFS:
565 /* Tell source to slow down like source quench in IP? */
566 goto freecopy;
567
568 case ENETUNREACH: /* shouldn't happen, checked above */
569 case EHOSTUNREACH:
570 case ENETDOWN:
571 case EHOSTDOWN:
572 default:
573 type = ICMP6_DST_UNREACH;
574 code = ICMP6_DST_UNREACH_ADDR;
575 break;
576 }
577 icmp6_error(mcopy, type, code, 0);
578 return;
579
580 freecopy:
581 m_freem(mcopy);
582 return;
583}
|