1/*-
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/netinet6/ip6_forward.c 188306 2009-02-08 09:27:07Z bz $");
34
35#include "opt_inet.h"
36#include "opt_inet6.h"
37#include "opt_ipsec.h"
38#include "opt_ipstealth.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/malloc.h>
43#include <sys/mbuf.h>
44#include <sys/domain.h>
45#include <sys/protosw.h>
46#include <sys/socket.h>
47#include <sys/errno.h>
48#include <sys/time.h>
49#include <sys/kernel.h>
50#include <sys/syslog.h>
51#include <sys/vimage.h>
52
53#include <net/if.h>
54#include <net/route.h>
55#include <net/pfil.h>
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 <netinet6/scope6_var.h>
66#include <netinet/icmp6.h>
67#include <netinet6/nd6.h>
68#include <netinet6/vinet6.h>
69
70#include <netinet/in_pcb.h>
71
72#ifdef IPSEC
73#include <netipsec/ipsec.h>
74#include <netipsec/ipsec6.h>
75#include <netipsec/key.h>
76#endif /* IPSEC */
77
78#include <netinet6/ip6protosw.h>
79
80/*
81 * Forward a packet. If some error occurs return the sender
82 * an icmp packet. Note we can't always generate a meaningful
83 * icmp message because icmp doesn't have a large enough repertoire
84 * of codes and types.
85 *
86 * If not forwarding, just drop the packet. This could be confusing
87 * if ipforwarding was zero but some routing protocol was advancing
88 * us as a gateway to somewhere. However, we must let the routing
89 * protocol deal with that.
90 *
91 */
92void
93ip6_forward(struct mbuf *m, int srcrt)
94{
95 INIT_VNET_INET6(curvnet);
96 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
97 struct sockaddr_in6 *dst = NULL;
98 struct rtentry *rt = NULL;
99 struct route_in6 rin6;
100 int error, type = 0, code = 0;
101 struct mbuf *mcopy = NULL;
102 struct ifnet *origifp; /* maybe unnecessary */
103 u_int32_t inzone, outzone;
104 struct in6_addr src_in6, dst_in6;
105#ifdef IPSEC
106 INIT_VNET_IPSEC(curvnet);
107 struct secpolicy *sp = NULL;
108 int ipsecrt = 0;
109#endif
110 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
111
112#ifdef IPSEC
113 /*
114 * Check AH/ESP integrity.
115 */
116 /*
117 * Don't increment ip6s_cantforward because this is the check
118 * before forwarding packet actually.
119 */
120 if (ipsec6_in_reject(m, NULL)) {
121 V_ipsec6stat.in_polvio++;
122 m_freem(m);
123 return;
124 }
125#endif /* IPSEC */
126
127 /*
128 * Do not forward packets to multicast destination (should be handled
129 * by ip6_mforward().
130 * Do not forward packets with unspecified source. It was discussed
131 * in July 2000, on the ipngwg mailing list.
132 */
133 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
134 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
135 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
136 V_ip6stat.ip6s_cantforward++;
137 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
138 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
139 V_ip6_log_time = time_second;
140 log(LOG_DEBUG,
141 "cannot forward "
142 "from %s to %s nxt %d received on %s\n",
143 ip6_sprintf(ip6bufs, &ip6->ip6_src),
144 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
145 ip6->ip6_nxt,
146 if_name(m->m_pkthdr.rcvif));
147 }
148 m_freem(m);
149 return;
150 }
151
152#ifdef IPSTEALTH
153 if (!V_ip6stealth) {
154#endif
155 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
156 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
157 icmp6_error(m, ICMP6_TIME_EXCEEDED,
158 ICMP6_TIME_EXCEED_TRANSIT, 0);
159 return;
160 }
161 ip6->ip6_hlim -= IPV6_HLIMDEC;
162
163#ifdef IPSTEALTH
164 }
165#endif
166
167 /*
168 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
169 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
170 * we need to generate an ICMP6 message to the src.
171 * Thanks to M_EXT, in most cases copy will not occur.
172 *
173 * It is important to save it before IPsec processing as IPsec
174 * processing may modify the mbuf.
175 */
176 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
177
178#ifdef IPSEC
179 /* get a security policy for this packet */
180 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
181 IP_FORWARDING, &error);
182 if (sp == NULL) {
183 V_ipsec6stat.out_inval++;
184 V_ip6stat.ip6s_cantforward++;
185 if (mcopy) {
186#if 0
187 /* XXX: what icmp ? */
188#else
189 m_freem(mcopy);
190#endif
191 }
192 m_freem(m);
193 return;
194 }
195
196 error = 0;
197
198 /* check policy */
199 switch (sp->policy) {
200 case IPSEC_POLICY_DISCARD:
201 /*
202 * This packet is just discarded.
203 */
204 V_ipsec6stat.out_polvio++;
205 V_ip6stat.ip6s_cantforward++;
206 KEY_FREESP(&sp);
207 if (mcopy) {
208#if 0
209 /* XXX: what icmp ? */
210#else
211 m_freem(mcopy);
212#endif
213 }
214 m_freem(m);
215 return;
216
217 case IPSEC_POLICY_BYPASS:
218 case IPSEC_POLICY_NONE:
219 /* no need to do IPsec. */
220 KEY_FREESP(&sp);
221 goto skip_ipsec;
222
223 case IPSEC_POLICY_IPSEC:
224 if (sp->req == NULL) {
225 /* XXX should be panic ? */
226 printf("ip6_forward: No IPsec request specified.\n");
227 V_ip6stat.ip6s_cantforward++;
228 KEY_FREESP(&sp);
229 if (mcopy) {
230#if 0
231 /* XXX: what icmp ? */
232#else
233 m_freem(mcopy);
234#endif
235 }
236 m_freem(m);
237 return;
238 }
239 /* do IPsec */
240 break;
241
242 case IPSEC_POLICY_ENTRUST:
243 default:
244 /* should be panic ?? */
245 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
246 KEY_FREESP(&sp);
247 goto skip_ipsec;
248 }
249
250 {
251 struct ipsecrequest *isr = NULL;
252 struct ipsec_output_state state;
253
254 /*
255 * when the kernel forwards a packet, it is not proper to apply
256 * IPsec transport mode to the packet is not proper. this check
257 * avoid from this.
258 * at present, if there is even a transport mode SA request in the
259 * security policy, the kernel does not apply IPsec to the packet.
260 * this check is not enough because the following case is valid.
261 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
262 */
263 for (isr = sp->req; isr; isr = isr->next) {
264 if (isr->saidx.mode == IPSEC_MODE_ANY)
265 goto doipsectunnel;
266 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
267 goto doipsectunnel;
268 }
269
270 /*
271 * if there's no need for tunnel mode IPsec, skip.
272 */
273 if (!isr)
274 goto skip_ipsec;
275
276 doipsectunnel:
277 /*
278 * All the extension headers will become inaccessible
279 * (since they can be encrypted).
280 * Don't panic, we need no more updates to extension headers
281 * on inner IPv6 packet (since they are now encapsulated).
282 *
283 * IPv6 [ESP|AH] IPv6 [extension headers] payload
284 */
285 bzero(&state, sizeof(state));
286 state.m = m;
287 state.ro = NULL; /* update at ipsec6_output_tunnel() */
288 state.dst = NULL; /* update at ipsec6_output_tunnel() */
289
290 error = ipsec6_output_tunnel(&state, sp, 0);
291
292 m = state.m;
293 KEY_FREESP(&sp);
294
295 if (error) {
296 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
297 switch (error) {
298 case EHOSTUNREACH:
299 case ENETUNREACH:
300 case EMSGSIZE:
301 case ENOBUFS:
302 case ENOMEM:
303 break;
304 default:
305 printf("ip6_output (ipsec): error code %d\n", error);
306 /* FALLTHROUGH */
307 case ENOENT:
308 /* don't show these error codes to the user */
309 break;
310 }
311 V_ip6stat.ip6s_cantforward++;
312 if (mcopy) {
313#if 0
314 /* XXX: what icmp ? */
315#else
316 m_freem(mcopy);
317#endif
318 }
319 m_freem(m);
320 return;
321 } else {
322 /*
323 * In the FAST IPSec case we have already
324 * re-injected the packet and it has been freed
325 * by the ipsec_done() function. So, just clean
326 * up after ourselves.
327 */
328 m = NULL;
329 goto freecopy;
330 }
331
332 if ((m != NULL) && (ip6 != mtod(m, struct ip6_hdr *)) ){
333 /*
334 * now tunnel mode headers are added. we are originating
335 * packet instead of forwarding the packet.
336 */
337 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
338 NULL);
339 goto freecopy;
340 }
341
342 /* adjust pointer */
343 dst = (struct sockaddr_in6 *)state.dst;
344 rt = state.ro ? state.ro->ro_rt : NULL;
345 if (dst != NULL && rt != NULL)
346 ipsecrt = 1;
347 }
348 if (ipsecrt)
349 goto skip_routing;
350skip_ipsec:
351#endif
352
353 bzero(&rin6, sizeof(struct route_in6));
354 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
355 dst->sin6_len = sizeof(struct sockaddr_in6);
356 dst->sin6_family = AF_INET6;
357 dst->sin6_addr = ip6->ip6_dst;
358
359 rin6.ro_rt = rtalloc1((struct sockaddr *)dst, 0, 0);
360 if (rin6.ro_rt != NULL)
361 RT_UNLOCK(rin6.ro_rt);
362 else {
363 V_ip6stat.ip6s_noroute++;
364 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
365 if (mcopy) {
366 icmp6_error(mcopy, ICMP6_DST_UNREACH,
367 ICMP6_DST_UNREACH_NOROUTE, 0);
368 }
369 goto bad;
370 }
371 rt = rin6.ro_rt;
372#ifdef IPSEC
373skip_routing:
374#endif
375
376 /*
377 * Source scope check: if a packet can't be delivered to its
378 * destination for the reason that the destination is beyond the scope
379 * of the source address, discard the packet and return an icmp6
380 * destination unreachable error with Code 2 (beyond scope of source
381 * address). We use a local copy of ip6_src, since in6_setscope()
382 * will possibly modify its first argument.
383 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
384 */
385 src_in6 = ip6->ip6_src;
386 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
387 /* XXX: this should not happen */
388 V_ip6stat.ip6s_cantforward++;
389 V_ip6stat.ip6s_badscope++;
390 goto bad;
391 }
392 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
393 V_ip6stat.ip6s_cantforward++;
394 V_ip6stat.ip6s_badscope++;
395 goto bad;
396 }
397 if (inzone != outzone
398#ifdef IPSEC
399 && !ipsecrt
400#endif
401 ) {
402 V_ip6stat.ip6s_cantforward++;
403 V_ip6stat.ip6s_badscope++;
404 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
405
406 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
407 V_ip6_log_time = time_second;
408 log(LOG_DEBUG,
409 "cannot forward "
410 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
411 ip6_sprintf(ip6bufs, &ip6->ip6_src),
412 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
413 ip6->ip6_nxt,
414 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
415 }
416 if (mcopy)
417 icmp6_error(mcopy, ICMP6_DST_UNREACH,
418 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
419 goto bad;
420 }
421
422 /*
423 * Destination scope check: if a packet is going to break the scope
424 * zone of packet's destination address, discard it. This case should
425 * usually be prevented by appropriately-configured routing table, but
426 * we need an explicit check because we may mistakenly forward the
427 * packet to a different zone by (e.g.) a default route.
428 */
429 dst_in6 = ip6->ip6_dst;
430 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
431 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
432 inzone != outzone) {
433 V_ip6stat.ip6s_cantforward++;
434 V_ip6stat.ip6s_badscope++;
435 goto bad;
436 }
437
438 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
439 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
440 if (mcopy) {
441 u_long mtu;
442#ifdef IPSEC
443 struct secpolicy *sp;
444 int ipsecerror;
445 size_t ipsechdrsiz;
446#endif /* IPSEC */
447
448 mtu = IN6_LINKMTU(rt->rt_ifp);
449#ifdef IPSEC
450 /*
451 * When we do IPsec tunnel ingress, we need to play
452 * with the link value (decrement IPsec header size
453 * from mtu value). The code is much simpler than v4
454 * case, as we have the outgoing interface for
455 * encapsulated packet as "rt->rt_ifp".
456 */
457 sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
458 IP_FORWARDING, &ipsecerror);
459 if (sp) {
460 ipsechdrsiz = ipsec_hdrsiz(mcopy,
461 IPSEC_DIR_OUTBOUND, NULL);
462 if (ipsechdrsiz < mtu)
463 mtu -= ipsechdrsiz;
464 }
465
466 /*
467 * if mtu becomes less than minimum MTU,
468 * tell minimum MTU (and I'll need to fragment it).
469 */
470 if (mtu < IPV6_MMTU)
471 mtu = IPV6_MMTU;
472#endif /* IPSEC */
473 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
474 }
475 goto bad;
476 }
477
478 if (rt->rt_flags & RTF_GATEWAY)
479 dst = (struct sockaddr_in6 *)rt->rt_gateway;
480
481 /*
482 * If we are to forward the packet using the same interface
483 * as one we got the packet from, perhaps we should send a redirect
484 * to sender to shortcut a hop.
485 * Only send redirect if source is sending directly to us,
486 * and if packet was not source routed (or has any options).
487 * Also, don't send redirect if forwarding using a route
488 * modified by a redirect.
489 */
490 if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
491#ifdef IPSEC
492 !ipsecrt &&
493#endif /* IPSEC */
494 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
495 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
496 /*
497 * If the incoming interface is equal to the outgoing
498 * one, and the link attached to the interface is
499 * point-to-point, then it will be highly probable
500 * that a routing loop occurs. Thus, we immediately
501 * drop the packet and send an ICMPv6 error message.
502 *
503 * type/code is based on suggestion by Rich Draves.
504 * not sure if it is the best pick.
505 */
506 icmp6_error(mcopy, ICMP6_DST_UNREACH,
507 ICMP6_DST_UNREACH_ADDR, 0);
508 goto bad;
509 }
510 type = ND_REDIRECT;
511 }
512
513 /*
514 * Fake scoped addresses. Note that even link-local source or
515 * destinaion can appear, if the originating node just sends the
516 * packet to us (without address resolution for the destination).
517 * Since both icmp6_error and icmp6_redirect_output fill the embedded
518 * link identifiers, we can do this stuff after making a copy for
519 * returning an error.
520 */
521 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
522 /*
523 * See corresponding comments in ip6_output.
524 * XXX: but is it possible that ip6_forward() sends a packet
525 * to a loopback interface? I don't think so, and thus
526 * I bark here. (jinmei@kame.net)
527 * XXX: it is common to route invalid packets to loopback.
528 * also, the codepath will be visited on use of ::1 in
529 * rthdr. (itojun)
530 */
531#if 1
532 if (0)
533#else
534 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
535#endif
536 {
537 printf("ip6_forward: outgoing interface is loopback. "
538 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
539 ip6_sprintf(ip6bufs, &ip6->ip6_src),
540 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
541 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
542 if_name(rt->rt_ifp));
543 }
544
545 /* we can just use rcvif in forwarding. */
546 origifp = m->m_pkthdr.rcvif;
547 }
548 else
549 origifp = rt->rt_ifp;
550 /*
551 * clear embedded scope identifiers if necessary.
552 * in6_clearscope will touch the addresses only when necessary.
553 */
554 in6_clearscope(&ip6->ip6_src);
555 in6_clearscope(&ip6->ip6_dst);
556
557 /* Jump over all PFIL processing if hooks are not active. */
558 if (!PFIL_HOOKED(&inet6_pfil_hook))
559 goto pass;
560
561 /* Run through list of hooks for output packets. */
562 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
563 if (error != 0)
564 goto senderr;
565 if (m == NULL)
566 goto freecopy;
567 ip6 = mtod(m, struct ip6_hdr *);
568
569pass:
570 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
571 if (error) {
572 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
573 V_ip6stat.ip6s_cantforward++;
574 } else {
575 V_ip6stat.ip6s_forward++;
576 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
577 if (type)
578 V_ip6stat.ip6s_redirectsent++;
579 else {
580 if (mcopy)
581 goto freecopy;
582 }
583 }
584
585senderr:
586 if (mcopy == NULL)
587 goto out;
588 switch (error) {
589 case 0:
590 if (type == ND_REDIRECT) {
591 icmp6_redirect_output(mcopy, rt);
592 goto out;
593 }
594 goto freecopy;
595
596 case EMSGSIZE:
597 /* xxx MTU is constant in PPP? */
598 goto freecopy;
599
600 case ENOBUFS:
601 /* Tell source to slow down like source quench in IP? */
602 goto freecopy;
603
604 case ENETUNREACH: /* shouldn't happen, checked above */
605 case EHOSTUNREACH:
606 case ENETDOWN:
607 case EHOSTDOWN:
608 default:
609 type = ICMP6_DST_UNREACH;
610 code = ICMP6_DST_UNREACH_ADDR;
611 break;
612 }
613 icmp6_error(mcopy, type, code, 0);
614 goto out;
615
616 freecopy:
617 m_freem(mcopy);
618 goto out;
619bad:
620 m_freem(m);
621out:
622 if (rt != NULL
623#ifdef IPSEC
624 && !ipsecrt
625#endif
626 )
627 RTFREE(rt);
628}
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/netinet6/ip6_forward.c 188306 2009-02-08 09:27:07Z bz $");
34
35#include "opt_inet.h"
36#include "opt_inet6.h"
37#include "opt_ipsec.h"
38#include "opt_ipstealth.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/malloc.h>
43#include <sys/mbuf.h>
44#include <sys/domain.h>
45#include <sys/protosw.h>
46#include <sys/socket.h>
47#include <sys/errno.h>
48#include <sys/time.h>
49#include <sys/kernel.h>
50#include <sys/syslog.h>
51#include <sys/vimage.h>
52
53#include <net/if.h>
54#include <net/route.h>
55#include <net/pfil.h>
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 <netinet6/scope6_var.h>
66#include <netinet/icmp6.h>
67#include <netinet6/nd6.h>
68#include <netinet6/vinet6.h>
69
70#include <netinet/in_pcb.h>
71
72#ifdef IPSEC
73#include <netipsec/ipsec.h>
74#include <netipsec/ipsec6.h>
75#include <netipsec/key.h>
76#endif /* IPSEC */
77
78#include <netinet6/ip6protosw.h>
79
80/*
81 * Forward a packet. If some error occurs return the sender
82 * an icmp packet. Note we can't always generate a meaningful
83 * icmp message because icmp doesn't have a large enough repertoire
84 * of codes and types.
85 *
86 * If not forwarding, just drop the packet. This could be confusing
87 * if ipforwarding was zero but some routing protocol was advancing
88 * us as a gateway to somewhere. However, we must let the routing
89 * protocol deal with that.
90 *
91 */
92void
93ip6_forward(struct mbuf *m, int srcrt)
94{
95 INIT_VNET_INET6(curvnet);
96 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
97 struct sockaddr_in6 *dst = NULL;
98 struct rtentry *rt = NULL;
99 struct route_in6 rin6;
100 int error, type = 0, code = 0;
101 struct mbuf *mcopy = NULL;
102 struct ifnet *origifp; /* maybe unnecessary */
103 u_int32_t inzone, outzone;
104 struct in6_addr src_in6, dst_in6;
105#ifdef IPSEC
106 INIT_VNET_IPSEC(curvnet);
107 struct secpolicy *sp = NULL;
108 int ipsecrt = 0;
109#endif
110 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
111
112#ifdef IPSEC
113 /*
114 * Check AH/ESP integrity.
115 */
116 /*
117 * Don't increment ip6s_cantforward because this is the check
118 * before forwarding packet actually.
119 */
120 if (ipsec6_in_reject(m, NULL)) {
121 V_ipsec6stat.in_polvio++;
122 m_freem(m);
123 return;
124 }
125#endif /* IPSEC */
126
127 /*
128 * Do not forward packets to multicast destination (should be handled
129 * by ip6_mforward().
130 * Do not forward packets with unspecified source. It was discussed
131 * in July 2000, on the ipngwg mailing list.
132 */
133 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
134 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
135 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
136 V_ip6stat.ip6s_cantforward++;
137 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
138 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
139 V_ip6_log_time = time_second;
140 log(LOG_DEBUG,
141 "cannot forward "
142 "from %s to %s nxt %d received on %s\n",
143 ip6_sprintf(ip6bufs, &ip6->ip6_src),
144 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
145 ip6->ip6_nxt,
146 if_name(m->m_pkthdr.rcvif));
147 }
148 m_freem(m);
149 return;
150 }
151
152#ifdef IPSTEALTH
153 if (!V_ip6stealth) {
154#endif
155 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
156 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
157 icmp6_error(m, ICMP6_TIME_EXCEEDED,
158 ICMP6_TIME_EXCEED_TRANSIT, 0);
159 return;
160 }
161 ip6->ip6_hlim -= IPV6_HLIMDEC;
162
163#ifdef IPSTEALTH
164 }
165#endif
166
167 /*
168 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
169 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
170 * we need to generate an ICMP6 message to the src.
171 * Thanks to M_EXT, in most cases copy will not occur.
172 *
173 * It is important to save it before IPsec processing as IPsec
174 * processing may modify the mbuf.
175 */
176 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
177
178#ifdef IPSEC
179 /* get a security policy for this packet */
180 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
181 IP_FORWARDING, &error);
182 if (sp == NULL) {
183 V_ipsec6stat.out_inval++;
184 V_ip6stat.ip6s_cantforward++;
185 if (mcopy) {
186#if 0
187 /* XXX: what icmp ? */
188#else
189 m_freem(mcopy);
190#endif
191 }
192 m_freem(m);
193 return;
194 }
195
196 error = 0;
197
198 /* check policy */
199 switch (sp->policy) {
200 case IPSEC_POLICY_DISCARD:
201 /*
202 * This packet is just discarded.
203 */
204 V_ipsec6stat.out_polvio++;
205 V_ip6stat.ip6s_cantforward++;
206 KEY_FREESP(&sp);
207 if (mcopy) {
208#if 0
209 /* XXX: what icmp ? */
210#else
211 m_freem(mcopy);
212#endif
213 }
214 m_freem(m);
215 return;
216
217 case IPSEC_POLICY_BYPASS:
218 case IPSEC_POLICY_NONE:
219 /* no need to do IPsec. */
220 KEY_FREESP(&sp);
221 goto skip_ipsec;
222
223 case IPSEC_POLICY_IPSEC:
224 if (sp->req == NULL) {
225 /* XXX should be panic ? */
226 printf("ip6_forward: No IPsec request specified.\n");
227 V_ip6stat.ip6s_cantforward++;
228 KEY_FREESP(&sp);
229 if (mcopy) {
230#if 0
231 /* XXX: what icmp ? */
232#else
233 m_freem(mcopy);
234#endif
235 }
236 m_freem(m);
237 return;
238 }
239 /* do IPsec */
240 break;
241
242 case IPSEC_POLICY_ENTRUST:
243 default:
244 /* should be panic ?? */
245 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
246 KEY_FREESP(&sp);
247 goto skip_ipsec;
248 }
249
250 {
251 struct ipsecrequest *isr = NULL;
252 struct ipsec_output_state state;
253
254 /*
255 * when the kernel forwards a packet, it is not proper to apply
256 * IPsec transport mode to the packet is not proper. this check
257 * avoid from this.
258 * at present, if there is even a transport mode SA request in the
259 * security policy, the kernel does not apply IPsec to the packet.
260 * this check is not enough because the following case is valid.
261 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
262 */
263 for (isr = sp->req; isr; isr = isr->next) {
264 if (isr->saidx.mode == IPSEC_MODE_ANY)
265 goto doipsectunnel;
266 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
267 goto doipsectunnel;
268 }
269
270 /*
271 * if there's no need for tunnel mode IPsec, skip.
272 */
273 if (!isr)
274 goto skip_ipsec;
275
276 doipsectunnel:
277 /*
278 * All the extension headers will become inaccessible
279 * (since they can be encrypted).
280 * Don't panic, we need no more updates to extension headers
281 * on inner IPv6 packet (since they are now encapsulated).
282 *
283 * IPv6 [ESP|AH] IPv6 [extension headers] payload
284 */
285 bzero(&state, sizeof(state));
286 state.m = m;
287 state.ro = NULL; /* update at ipsec6_output_tunnel() */
288 state.dst = NULL; /* update at ipsec6_output_tunnel() */
289
290 error = ipsec6_output_tunnel(&state, sp, 0);
291
292 m = state.m;
293 KEY_FREESP(&sp);
294
295 if (error) {
296 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
297 switch (error) {
298 case EHOSTUNREACH:
299 case ENETUNREACH:
300 case EMSGSIZE:
301 case ENOBUFS:
302 case ENOMEM:
303 break;
304 default:
305 printf("ip6_output (ipsec): error code %d\n", error);
306 /* FALLTHROUGH */
307 case ENOENT:
308 /* don't show these error codes to the user */
309 break;
310 }
311 V_ip6stat.ip6s_cantforward++;
312 if (mcopy) {
313#if 0
314 /* XXX: what icmp ? */
315#else
316 m_freem(mcopy);
317#endif
318 }
319 m_freem(m);
320 return;
321 } else {
322 /*
323 * In the FAST IPSec case we have already
324 * re-injected the packet and it has been freed
325 * by the ipsec_done() function. So, just clean
326 * up after ourselves.
327 */
328 m = NULL;
329 goto freecopy;
330 }
331
332 if ((m != NULL) && (ip6 != mtod(m, struct ip6_hdr *)) ){
333 /*
334 * now tunnel mode headers are added. we are originating
335 * packet instead of forwarding the packet.
336 */
337 ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
338 NULL);
339 goto freecopy;
340 }
341
342 /* adjust pointer */
343 dst = (struct sockaddr_in6 *)state.dst;
344 rt = state.ro ? state.ro->ro_rt : NULL;
345 if (dst != NULL && rt != NULL)
346 ipsecrt = 1;
347 }
348 if (ipsecrt)
349 goto skip_routing;
350skip_ipsec:
351#endif
352
353 bzero(&rin6, sizeof(struct route_in6));
354 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
355 dst->sin6_len = sizeof(struct sockaddr_in6);
356 dst->sin6_family = AF_INET6;
357 dst->sin6_addr = ip6->ip6_dst;
358
359 rin6.ro_rt = rtalloc1((struct sockaddr *)dst, 0, 0);
360 if (rin6.ro_rt != NULL)
361 RT_UNLOCK(rin6.ro_rt);
362 else {
363 V_ip6stat.ip6s_noroute++;
364 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
365 if (mcopy) {
366 icmp6_error(mcopy, ICMP6_DST_UNREACH,
367 ICMP6_DST_UNREACH_NOROUTE, 0);
368 }
369 goto bad;
370 }
371 rt = rin6.ro_rt;
372#ifdef IPSEC
373skip_routing:
374#endif
375
376 /*
377 * Source scope check: if a packet can't be delivered to its
378 * destination for the reason that the destination is beyond the scope
379 * of the source address, discard the packet and return an icmp6
380 * destination unreachable error with Code 2 (beyond scope of source
381 * address). We use a local copy of ip6_src, since in6_setscope()
382 * will possibly modify its first argument.
383 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
384 */
385 src_in6 = ip6->ip6_src;
386 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
387 /* XXX: this should not happen */
388 V_ip6stat.ip6s_cantforward++;
389 V_ip6stat.ip6s_badscope++;
390 goto bad;
391 }
392 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
393 V_ip6stat.ip6s_cantforward++;
394 V_ip6stat.ip6s_badscope++;
395 goto bad;
396 }
397 if (inzone != outzone
398#ifdef IPSEC
399 && !ipsecrt
400#endif
401 ) {
402 V_ip6stat.ip6s_cantforward++;
403 V_ip6stat.ip6s_badscope++;
404 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
405
406 if (V_ip6_log_time + V_ip6_log_interval < time_second) {
407 V_ip6_log_time = time_second;
408 log(LOG_DEBUG,
409 "cannot forward "
410 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
411 ip6_sprintf(ip6bufs, &ip6->ip6_src),
412 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
413 ip6->ip6_nxt,
414 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
415 }
416 if (mcopy)
417 icmp6_error(mcopy, ICMP6_DST_UNREACH,
418 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
419 goto bad;
420 }
421
422 /*
423 * Destination scope check: if a packet is going to break the scope
424 * zone of packet's destination address, discard it. This case should
425 * usually be prevented by appropriately-configured routing table, but
426 * we need an explicit check because we may mistakenly forward the
427 * packet to a different zone by (e.g.) a default route.
428 */
429 dst_in6 = ip6->ip6_dst;
430 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
431 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
432 inzone != outzone) {
433 V_ip6stat.ip6s_cantforward++;
434 V_ip6stat.ip6s_badscope++;
435 goto bad;
436 }
437
438 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
439 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
440 if (mcopy) {
441 u_long mtu;
442#ifdef IPSEC
443 struct secpolicy *sp;
444 int ipsecerror;
445 size_t ipsechdrsiz;
446#endif /* IPSEC */
447
448 mtu = IN6_LINKMTU(rt->rt_ifp);
449#ifdef IPSEC
450 /*
451 * When we do IPsec tunnel ingress, we need to play
452 * with the link value (decrement IPsec header size
453 * from mtu value). The code is much simpler than v4
454 * case, as we have the outgoing interface for
455 * encapsulated packet as "rt->rt_ifp".
456 */
457 sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
458 IP_FORWARDING, &ipsecerror);
459 if (sp) {
460 ipsechdrsiz = ipsec_hdrsiz(mcopy,
461 IPSEC_DIR_OUTBOUND, NULL);
462 if (ipsechdrsiz < mtu)
463 mtu -= ipsechdrsiz;
464 }
465
466 /*
467 * if mtu becomes less than minimum MTU,
468 * tell minimum MTU (and I'll need to fragment it).
469 */
470 if (mtu < IPV6_MMTU)
471 mtu = IPV6_MMTU;
472#endif /* IPSEC */
473 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
474 }
475 goto bad;
476 }
477
478 if (rt->rt_flags & RTF_GATEWAY)
479 dst = (struct sockaddr_in6 *)rt->rt_gateway;
480
481 /*
482 * If we are to forward the packet using the same interface
483 * as one we got the packet from, perhaps we should send a redirect
484 * to sender to shortcut a hop.
485 * Only send redirect if source is sending directly to us,
486 * and if packet was not source routed (or has any options).
487 * Also, don't send redirect if forwarding using a route
488 * modified by a redirect.
489 */
490 if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
491#ifdef IPSEC
492 !ipsecrt &&
493#endif /* IPSEC */
494 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
495 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
496 /*
497 * If the incoming interface is equal to the outgoing
498 * one, and the link attached to the interface is
499 * point-to-point, then it will be highly probable
500 * that a routing loop occurs. Thus, we immediately
501 * drop the packet and send an ICMPv6 error message.
502 *
503 * type/code is based on suggestion by Rich Draves.
504 * not sure if it is the best pick.
505 */
506 icmp6_error(mcopy, ICMP6_DST_UNREACH,
507 ICMP6_DST_UNREACH_ADDR, 0);
508 goto bad;
509 }
510 type = ND_REDIRECT;
511 }
512
513 /*
514 * Fake scoped addresses. Note that even link-local source or
515 * destinaion can appear, if the originating node just sends the
516 * packet to us (without address resolution for the destination).
517 * Since both icmp6_error and icmp6_redirect_output fill the embedded
518 * link identifiers, we can do this stuff after making a copy for
519 * returning an error.
520 */
521 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
522 /*
523 * See corresponding comments in ip6_output.
524 * XXX: but is it possible that ip6_forward() sends a packet
525 * to a loopback interface? I don't think so, and thus
526 * I bark here. (jinmei@kame.net)
527 * XXX: it is common to route invalid packets to loopback.
528 * also, the codepath will be visited on use of ::1 in
529 * rthdr. (itojun)
530 */
531#if 1
532 if (0)
533#else
534 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
535#endif
536 {
537 printf("ip6_forward: outgoing interface is loopback. "
538 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
539 ip6_sprintf(ip6bufs, &ip6->ip6_src),
540 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
541 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
542 if_name(rt->rt_ifp));
543 }
544
545 /* we can just use rcvif in forwarding. */
546 origifp = m->m_pkthdr.rcvif;
547 }
548 else
549 origifp = rt->rt_ifp;
550 /*
551 * clear embedded scope identifiers if necessary.
552 * in6_clearscope will touch the addresses only when necessary.
553 */
554 in6_clearscope(&ip6->ip6_src);
555 in6_clearscope(&ip6->ip6_dst);
556
557 /* Jump over all PFIL processing if hooks are not active. */
558 if (!PFIL_HOOKED(&inet6_pfil_hook))
559 goto pass;
560
561 /* Run through list of hooks for output packets. */
562 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
563 if (error != 0)
564 goto senderr;
565 if (m == NULL)
566 goto freecopy;
567 ip6 = mtod(m, struct ip6_hdr *);
568
569pass:
570 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
571 if (error) {
572 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
573 V_ip6stat.ip6s_cantforward++;
574 } else {
575 V_ip6stat.ip6s_forward++;
576 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
577 if (type)
578 V_ip6stat.ip6s_redirectsent++;
579 else {
580 if (mcopy)
581 goto freecopy;
582 }
583 }
584
585senderr:
586 if (mcopy == NULL)
587 goto out;
588 switch (error) {
589 case 0:
590 if (type == ND_REDIRECT) {
591 icmp6_redirect_output(mcopy, rt);
592 goto out;
593 }
594 goto freecopy;
595
596 case EMSGSIZE:
597 /* xxx MTU is constant in PPP? */
598 goto freecopy;
599
600 case ENOBUFS:
601 /* Tell source to slow down like source quench in IP? */
602 goto freecopy;
603
604 case ENETUNREACH: /* shouldn't happen, checked above */
605 case EHOSTUNREACH:
606 case ENETDOWN:
607 case EHOSTDOWN:
608 default:
609 type = ICMP6_DST_UNREACH;
610 code = ICMP6_DST_UNREACH_ADDR;
611 break;
612 }
613 icmp6_error(mcopy, type, code, 0);
614 goto out;
615
616 freecopy:
617 m_freem(mcopy);
618 goto out;
619bad:
620 m_freem(m);
621out:
622 if (rt != NULL
623#ifdef IPSEC
624 && !ipsecrt
625#endif
626 )
627 RTFREE(rt);
628}