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: releng/11.0/sys/netinet6/ip6_forward.c 301717 2016-06-09 05:48:34Z ae $");
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
52 #include <net/if.h>
53 #include <net/if_var.h>
54 #include <net/netisr.h>
55 #include <net/route.h>
56 #include <net/pfil.h>
57
58 #include <netinet/in.h>
59 #include <netinet/in_var.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/ip.h>
62 #include <netinet/ip_var.h>
63 #include <netinet6/in6_var.h>
64 #include <netinet/ip6.h>
65 #include <netinet6/ip6_var.h>
66 #include <netinet6/scope6_var.h>
67 #include <netinet/icmp6.h>
68 #include <netinet6/nd6.h>
69
70 #include <netinet/in_pcb.h>
71
72 #ifdef IPSEC
73 #include <netinet6/ip6_ipsec.h>
74 #include <netipsec/ipsec.h>
75 #include <netipsec/ipsec6.h>
76 #include <netipsec/key.h>
77 #endif /* IPSEC */
78
79 /*
80 * Forward a packet. If some error occurs return the sender
81 * an icmp packet. Note we can't always generate a meaningful
82 * icmp message because icmp doesn't have a large enough repertoire
83 * of codes and types.
84 *
85 * If not forwarding, just drop the packet. This could be confusing
86 * if ipforwarding was zero but some routing protocol was advancing
87 * us as a gateway to somewhere. However, we must let the routing
88 * protocol deal with that.
89 *
90 */
91 void
92 ip6_forward(struct mbuf *m, int srcrt)
93 {
94 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
95 struct sockaddr_in6 *dst = NULL;
96 struct rtentry *rt = NULL;
97 struct route_in6 rin6;
98 int error, type = 0, code = 0;
99 struct mbuf *mcopy = NULL;
100 struct ifnet *origifp; /* maybe unnecessary */
101 u_int32_t inzone, outzone;
102 struct in6_addr src_in6, dst_in6, odst;
103 #ifdef IPSEC
104 struct secpolicy *sp = NULL;
105 #endif
106 #ifdef SCTP
107 int sw_csum;
108 #endif
109 struct m_tag *fwd_tag;
110 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
111
112 /*
113 * Do not forward packets to multicast destination (should be handled
114 * by ip6_mforward().
115 * Do not forward packets with unspecified source. It was discussed
116 * in July 2000, on the ipngwg mailing list.
117 */
118 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
119 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
120 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
121 IP6STAT_INC(ip6s_cantforward);
122 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
123 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
124 V_ip6_log_time = time_uptime;
125 log(LOG_DEBUG,
126 "cannot forward "
127 "from %s to %s nxt %d received on %s\n",
128 ip6_sprintf(ip6bufs, &ip6->ip6_src),
129 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
130 ip6->ip6_nxt,
131 if_name(m->m_pkthdr.rcvif));
132 }
133 m_freem(m);
134 return;
135 }
136 #ifdef IPSEC
137 /*
138 * Check if this packet has an active SA and needs to be dropped
139 * instead of forwarded.
140 */
141 if (ip6_ipsec_fwd(m) != 0) {
142 IP6STAT_INC(ip6s_cantforward);
143 m_freem(m);
144 return;
145 }
146 #endif /* IPSEC */
147
148 #ifdef IPSTEALTH
149 if (!V_ip6stealth) {
150 #endif
151 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
152 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
153 icmp6_error(m, ICMP6_TIME_EXCEEDED,
154 ICMP6_TIME_EXCEED_TRANSIT, 0);
155 return;
156 }
157 ip6->ip6_hlim -= IPV6_HLIMDEC;
158
159 #ifdef IPSTEALTH
160 }
161 #endif
162
163 /*
164 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
165 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
166 * we need to generate an ICMP6 message to the src.
167 * Thanks to M_EXT, in most cases copy will not occur.
168 *
169 * It is important to save it before IPsec processing as IPsec
170 * processing may modify the mbuf.
171 */
172 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
173
174 #ifdef IPSEC
175 /* get a security policy for this packet */
176 sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, &error);
177 if (sp == NULL) {
178 IPSEC6STAT_INC(ips_out_inval);
179 IP6STAT_INC(ip6s_cantforward);
180 if (mcopy) {
181 #if 0
182 /* XXX: what icmp ? */
183 #else
184 m_freem(mcopy);
185 #endif
186 }
187 m_freem(m);
188 return;
189 }
190
191 error = 0;
192
193 /* check policy */
194 switch (sp->policy) {
195 case IPSEC_POLICY_DISCARD:
196 /*
197 * This packet is just discarded.
198 */
199 IPSEC6STAT_INC(ips_out_polvio);
200 IP6STAT_INC(ip6s_cantforward);
201 KEY_FREESP(&sp);
202 if (mcopy) {
203 #if 0
204 /* XXX: what icmp ? */
205 #else
206 m_freem(mcopy);
207 #endif
208 }
209 m_freem(m);
210 return;
211
212 case IPSEC_POLICY_BYPASS:
213 case IPSEC_POLICY_NONE:
214 /* no need to do IPsec. */
215 KEY_FREESP(&sp);
216 goto skip_ipsec;
217
218 case IPSEC_POLICY_IPSEC:
219 if (sp->req == NULL) {
220 /* XXX should be panic ? */
221 printf("ip6_forward: No IPsec request specified.\n");
222 IP6STAT_INC(ip6s_cantforward);
223 KEY_FREESP(&sp);
224 if (mcopy) {
225 #if 0
226 /* XXX: what icmp ? */
227 #else
228 m_freem(mcopy);
229 #endif
230 }
231 m_freem(m);
232 return;
233 }
234 /* do IPsec */
235 break;
236
237 case IPSEC_POLICY_ENTRUST:
238 default:
239 /* should be panic ?? */
240 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
241 KEY_FREESP(&sp);
242 goto skip_ipsec;
243 }
244
245 {
246 struct ipsecrequest *isr = NULL;
247
248 /*
249 * when the kernel forwards a packet, it is not proper to apply
250 * IPsec transport mode to the packet. This check avoid from this.
251 * at present, if there is even a transport mode SA request in the
252 * security policy, the kernel does not apply IPsec to the packet.
253 * this check is not enough because the following case is valid.
254 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
255 */
256 for (isr = sp->req; isr; isr = isr->next) {
257 if (isr->saidx.mode == IPSEC_MODE_ANY)
258 goto doipsectunnel;
259 if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
260 goto doipsectunnel;
261 }
262
263 /*
264 * if there's no need for tunnel mode IPsec, skip.
265 */
266 if (!isr)
267 goto skip_ipsec;
268
269 doipsectunnel:
270 /*
271 * All the extension headers will become inaccessible
272 * (since they can be encrypted).
273 * Don't panic, we need no more updates to extension headers
274 * on inner IPv6 packet (since they are now encapsulated).
275 *
276 * IPv6 [ESP|AH] IPv6 [extension headers] payload
277 */
278
279 /*
280 * If we need to encapsulate the packet, do it here
281 * ipsec6_proces_packet will send the packet using ip6_output
282 */
283 error = ipsec6_process_packet(m, sp->req);
284 /* Release SP if an error occurred */
285 if (error != 0)
286 KEY_FREESP(&sp);
287 if (error == EJUSTRETURN) {
288 /*
289 * We had a SP with a level of 'use' and no SA. We
290 * will just continue to process the packet without
291 * IPsec processing.
292 */
293 error = 0;
294 goto skip_ipsec;
295 }
296
297 if (error) {
298 /* mbuf is already reclaimed in ipsec6_process_packet. */
299 switch (error) {
300 case EHOSTUNREACH:
301 case ENETUNREACH:
302 case EMSGSIZE:
303 case ENOBUFS:
304 case ENOMEM:
305 break;
306 default:
307 printf("ip6_output (ipsec): error code %d\n", error);
308 /* FALLTHROUGH */
309 case ENOENT:
310 /* don't show these error codes to the user */
311 break;
312 }
313 IP6STAT_INC(ip6s_cantforward);
314 if (mcopy) {
315 #if 0
316 /* XXX: what icmp ? */
317 #else
318 m_freem(mcopy);
319 #endif
320 }
321 return;
322 } else {
323 /*
324 * In the FAST IPSec case we have already
325 * re-injected the packet and it has been freed
326 * by the ipsec_done() function. So, just clean
327 * up after ourselves.
328 */
329 m = NULL;
330 goto freecopy;
331 }
332 }
333 skip_ipsec:
334 #endif
335 again:
336 bzero(&rin6, sizeof(struct route_in6));
337 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
338 dst->sin6_len = sizeof(struct sockaddr_in6);
339 dst->sin6_family = AF_INET6;
340 dst->sin6_addr = ip6->ip6_dst;
341 again2:
342 rin6.ro_rt = in6_rtalloc1((struct sockaddr *)dst, 0, 0, M_GETFIB(m));
343 rt = rin6.ro_rt;
344 if (rin6.ro_rt != NULL)
345 RT_UNLOCK(rin6.ro_rt);
346 else {
347 IP6STAT_INC(ip6s_noroute);
348 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
349 if (mcopy) {
350 icmp6_error(mcopy, ICMP6_DST_UNREACH,
351 ICMP6_DST_UNREACH_NOROUTE, 0);
352 }
353 goto bad;
354 }
355
356 /*
357 * Source scope check: if a packet can't be delivered to its
358 * destination for the reason that the destination is beyond the scope
359 * of the source address, discard the packet and return an icmp6
360 * destination unreachable error with Code 2 (beyond scope of source
361 * address). We use a local copy of ip6_src, since in6_setscope()
362 * will possibly modify its first argument.
363 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
364 */
365 src_in6 = ip6->ip6_src;
366 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
367 /* XXX: this should not happen */
368 IP6STAT_INC(ip6s_cantforward);
369 IP6STAT_INC(ip6s_badscope);
370 goto bad;
371 }
372 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
373 IP6STAT_INC(ip6s_cantforward);
374 IP6STAT_INC(ip6s_badscope);
375 goto bad;
376 }
377 if (inzone != outzone) {
378 IP6STAT_INC(ip6s_cantforward);
379 IP6STAT_INC(ip6s_badscope);
380 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
381
382 if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
383 V_ip6_log_time = time_uptime;
384 log(LOG_DEBUG,
385 "cannot forward "
386 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
387 ip6_sprintf(ip6bufs, &ip6->ip6_src),
388 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
389 ip6->ip6_nxt,
390 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
391 }
392 if (mcopy)
393 icmp6_error(mcopy, ICMP6_DST_UNREACH,
394 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
395 goto bad;
396 }
397
398 /*
399 * Destination scope check: if a packet is going to break the scope
400 * zone of packet's destination address, discard it. This case should
401 * usually be prevented by appropriately-configured routing table, but
402 * we need an explicit check because we may mistakenly forward the
403 * packet to a different zone by (e.g.) a default route.
404 */
405 dst_in6 = ip6->ip6_dst;
406 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
407 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
408 inzone != outzone) {
409 IP6STAT_INC(ip6s_cantforward);
410 IP6STAT_INC(ip6s_badscope);
411 goto bad;
412 }
413
414 if (rt->rt_flags & RTF_GATEWAY)
415 dst = (struct sockaddr_in6 *)rt->rt_gateway;
416
417 /*
418 * If we are to forward the packet using the same interface
419 * as one we got the packet from, perhaps we should send a redirect
420 * to sender to shortcut a hop.
421 * Only send redirect if source is sending directly to us,
422 * and if packet was not source routed (or has any options).
423 * Also, don't send redirect if forwarding using a route
424 * modified by a redirect.
425 */
426 if (V_ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
427 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
428 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
429 /*
430 * If the incoming interface is equal to the outgoing
431 * one, and the link attached to the interface is
432 * point-to-point, then it will be highly probable
433 * that a routing loop occurs. Thus, we immediately
434 * drop the packet and send an ICMPv6 error message.
435 *
436 * type/code is based on suggestion by Rich Draves.
437 * not sure if it is the best pick.
438 */
439 icmp6_error(mcopy, ICMP6_DST_UNREACH,
440 ICMP6_DST_UNREACH_ADDR, 0);
441 goto bad;
442 }
443 type = ND_REDIRECT;
444 }
445
446 /*
447 * Fake scoped addresses. Note that even link-local source or
448 * destinaion can appear, if the originating node just sends the
449 * packet to us (without address resolution for the destination).
450 * Since both icmp6_error and icmp6_redirect_output fill the embedded
451 * link identifiers, we can do this stuff after making a copy for
452 * returning an error.
453 */
454 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
455 /*
456 * See corresponding comments in ip6_output.
457 * XXX: but is it possible that ip6_forward() sends a packet
458 * to a loopback interface? I don't think so, and thus
459 * I bark here. (jinmei@kame.net)
460 * XXX: it is common to route invalid packets to loopback.
461 * also, the codepath will be visited on use of ::1 in
462 * rthdr. (itojun)
463 */
464 #if 1
465 if (0)
466 #else
467 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
468 #endif
469 {
470 printf("ip6_forward: outgoing interface is loopback. "
471 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
472 ip6_sprintf(ip6bufs, &ip6->ip6_src),
473 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
474 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
475 if_name(rt->rt_ifp));
476 }
477
478 /* we can just use rcvif in forwarding. */
479 origifp = m->m_pkthdr.rcvif;
480 }
481 else
482 origifp = rt->rt_ifp;
483 /*
484 * clear embedded scope identifiers if necessary.
485 * in6_clearscope will touch the addresses only when necessary.
486 */
487 in6_clearscope(&ip6->ip6_src);
488 in6_clearscope(&ip6->ip6_dst);
489
490 /* Jump over all PFIL processing if hooks are not active. */
491 if (!PFIL_HOOKED(&V_inet6_pfil_hook))
492 goto pass;
493
494 odst = ip6->ip6_dst;
495 /* Run through list of hooks for output packets. */
496 error = pfil_run_hooks(&V_inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
497 if (error != 0 || m == NULL)
498 goto freecopy; /* consumed by filter */
499 ip6 = mtod(m, struct ip6_hdr *);
500
501 /* See if destination IP address was changed by packet filter. */
502 if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
503 m->m_flags |= M_SKIP_FIREWALL;
504 /* If destination is now ourself drop to ip6_input(). */
505 if (in6_localip(&ip6->ip6_dst))
506 m->m_flags |= M_FASTFWD_OURS;
507 else {
508 RTFREE(rt);
509 goto again; /* Redo the routing table lookup. */
510 }
511 }
512
513 /* See if local, if yes, send it to netisr. */
514 if (m->m_flags & M_FASTFWD_OURS) {
515 if (m->m_pkthdr.rcvif == NULL)
516 m->m_pkthdr.rcvif = V_loif;
517 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
518 m->m_pkthdr.csum_flags |=
519 CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
520 m->m_pkthdr.csum_data = 0xffff;
521 }
522 #ifdef SCTP
523 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
524 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
525 #endif
526 error = netisr_queue(NETISR_IPV6, m);
527 goto out;
528 }
529 /* Or forward to some other address? */
530 if ((m->m_flags & M_IP6_NEXTHOP) &&
531 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
532 dst = (struct sockaddr_in6 *)&rin6.ro_dst;
533 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in6));
534 m->m_flags |= M_SKIP_FIREWALL;
535 m->m_flags &= ~M_IP6_NEXTHOP;
536 m_tag_delete(m, fwd_tag);
537 RTFREE(rt);
538 goto again2;
539 }
540
541 pass:
542 /* See if the size was changed by the packet filter. */
543 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
544 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
545 if (mcopy) {
546 u_long mtu;
547 #ifdef IPSEC
548 size_t ipsechdrsiz;
549 #endif /* IPSEC */
550
551 mtu = IN6_LINKMTU(rt->rt_ifp);
552 #ifdef IPSEC
553 /*
554 * When we do IPsec tunnel ingress, we need to play
555 * with the link value (decrement IPsec header size
556 * from mtu value). The code is much simpler than v4
557 * case, as we have the outgoing interface for
558 * encapsulated packet as "rt->rt_ifp".
559 */
560 ipsechdrsiz = ipsec_hdrsiz(mcopy, IPSEC_DIR_OUTBOUND,
561 NULL);
562 if (ipsechdrsiz < mtu)
563 mtu -= ipsechdrsiz;
564 /*
565 * if mtu becomes less than minimum MTU,
566 * tell minimum MTU (and I'll need to fragment it).
567 */
568 if (mtu < IPV6_MMTU)
569 mtu = IPV6_MMTU;
570 #endif /* IPSEC */
571 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
572 }
573 goto bad;
574 }
575
576 error = nd6_output_ifp(rt->rt_ifp, origifp, m, dst, NULL);
577 if (error) {
578 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
579 IP6STAT_INC(ip6s_cantforward);
580 } else {
581 IP6STAT_INC(ip6s_forward);
582 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
583 if (type)
584 IP6STAT_INC(ip6s_redirectsent);
585 else {
586 if (mcopy)
587 goto freecopy;
588 }
589 }
590
591 if (mcopy == NULL)
592 goto out;
593 switch (error) {
594 case 0:
595 if (type == ND_REDIRECT) {
596 icmp6_redirect_output(mcopy, rt);
597 goto out;
598 }
599 goto freecopy;
600
601 case EMSGSIZE:
602 /* xxx MTU is constant in PPP? */
603 goto freecopy;
604
605 case ENOBUFS:
606 /* Tell source to slow down like source quench in IP? */
607 goto freecopy;
608
609 case ENETUNREACH: /* shouldn't happen, checked above */
610 case EHOSTUNREACH:
611 case ENETDOWN:
612 case EHOSTDOWN:
613 default:
614 type = ICMP6_DST_UNREACH;
615 code = ICMP6_DST_UNREACH_ADDR;
616 break;
617 }
618 icmp6_error(mcopy, type, code, 0);
619 goto out;
620
621 freecopy:
622 m_freem(mcopy);
623 goto out;
624 bad:
625 m_freem(m);
626 out:
627 if (rt != NULL)
628 RTFREE(rt);
629 }
Cache object: f392a3c986e0373a228bfcae0b6b760d
|