1 /*
2 * Copyright (c) 2009-2021 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29 /* $FreeBSD: src/sys/netinet6/ip6_forward.c,v 1.16 2002/10/16 02:25:05 sam Exp $ */
30 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
31
32 /*
33 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions
38 * are met:
39 * 1. Redistributions of source code must retain the above copyright
40 * notice, this list of conditions and the following disclaimer.
41 * 2. Redistributions in binary form must reproduce the above copyright
42 * notice, this list of conditions and the following disclaimer in the
43 * documentation and/or other materials provided with the distribution.
44 * 3. Neither the name of the project nor the names of its contributors
45 * may be used to endorse or promote products derived from this software
46 * without specific prior written permission.
47 *
48 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58 * SUCH DAMAGE.
59 */
60
61
62 #include <sys/param.h>
63 #include <sys/systm.h>
64 #include <sys/malloc.h>
65 #include <sys/mbuf.h>
66 #include <sys/domain.h>
67 #include <sys/protosw.h>
68 #include <sys/socket.h>
69 #include <sys/errno.h>
70 #include <sys/time.h>
71 #include <sys/kernel.h>
72 #include <sys/syslog.h>
73
74 #include <net/if.h>
75 #include <net/route.h>
76
77 #include <netinet/in.h>
78 #include <netinet/in_var.h>
79 #include <netinet/in_systm.h>
80 #include <netinet/ip.h>
81 #include <netinet/ip_var.h>
82 #include <netinet6/in6_var.h>
83 #include <netinet/ip6.h>
84 #include <netinet6/ip6_var.h>
85 #include <netinet/icmp6.h>
86 #include <netinet6/nd6.h>
87 #include <netinet6/scope6_var.h>
88
89 #include <netinet/in_pcb.h>
90
91 #if IPSEC
92 #include <netinet6/ipsec.h>
93 #include <netinet6/ipsec6.h>
94 #include <netkey/key.h>
95 extern int ipsec_bypass;
96 #endif /* IPSEC */
97
98 #include <net/net_osdep.h>
99
100 #if DUMMYNET
101 #include <netinet/ip_dummynet.h>
102 #endif /* DUMMYNET */
103
104 #if PF
105 #include <net/pfvar.h>
106 static void
adjust_scope_and_pktlen(struct mbuf * m,unsigned int * ifscope_p,uint32_t * mpktlen_p)107 adjust_scope_and_pktlen(struct mbuf *m,
108 unsigned int *ifscope_p, uint32_t *mpktlen_p)
109 {
110 struct pf_mtag *pf_mtag;
111 struct pf_fragment_tag *pf_ftagp;
112
113 pf_mtag = pf_find_mtag(m);
114 ASSERT(pf_mtag != NULL);
115 if (pf_mtag->pftag_rtableid != IFSCOPE_NONE) {
116 *ifscope_p = pf_mtag->pftag_rtableid;
117 }
118 pf_ftagp = pf_find_fragment_tag(m);
119 if (pf_ftagp != NULL) {
120 ASSERT(pf_mtag->pftag_flags & PF_TAG_REASSEMBLED);
121 *mpktlen_p = pf_ftagp->ft_maxlen;
122 ASSERT(*mpktlen_p);
123 }
124 }
125
126 #endif /* PF */
127
128 /*
129 * Forward a packet. If some error occurs return the sender
130 * an icmp packet. Note we can't always generate a meaningful
131 * icmp message because icmp doesn't have a large enough repertoire
132 * of codes and types.
133 *
134 * If not forwarding, just drop the packet. This could be confusing
135 * if ipforwarding was zero but some routing protocol was advancing
136 * us as a gateway to somewhere. However, we must let the routing
137 * protocol deal with that.
138 *
139 */
140
141 struct mbuf *
ip6_forward(struct mbuf * m,struct route_in6 * ip6forward_rt,int srcrt)142 ip6_forward(struct mbuf *m, struct route_in6 *ip6forward_rt,
143 int srcrt)
144 {
145 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
146 struct sockaddr_in6 *dst;
147 struct rtentry *rt;
148 int error, type = 0, code = 0;
149 boolean_t proxy = FALSE;
150 struct mbuf *mcopy = NULL;
151 struct ifnet *ifp, *rcvifp, *origifp; /* maybe unnecessary */
152 u_int32_t inzone, outzone, len = 0, pktcnt = 0;
153 struct in6_addr src_in6, dst_in6;
154 uint64_t curtime = net_uptime();
155 #if IPSEC
156 struct secpolicy *sp = NULL;
157 #endif
158 unsigned int ifscope = IFSCOPE_NONE;
159 uint32_t mpktlen = 0;
160
161 /*
162 * In the prefix proxying case, the route to the proxied node normally
163 * gets created by nd6_prproxy_ns_output(), as part of forwarding a
164 * NS (NUD/AR) packet to the proxied node. In the event that such
165 * packet did not arrive in time before the correct route gets created,
166 * ip6_input() would have performed a rtalloc() which most likely will
167 * create the wrong cloned route; this route points back to the same
168 * interface as the inbound interface, since the parent non-scoped
169 * prefix route points there. Therefore we check if that is the case
170 * and perform the necessary fixup to get the correct route installed.
171 */
172 if (!srcrt && nd6_prproxy &&
173 (rt = ip6forward_rt->ro_rt) != NULL && (rt->rt_flags & RTF_PROXY)) {
174 nd6_proxy_find_fwdroute(m->m_pkthdr.rcvif, ip6forward_rt);
175 if ((rt = ip6forward_rt->ro_rt) != NULL) {
176 ifscope = rt->rt_ifp->if_index;
177 }
178 }
179
180 #if PF
181 adjust_scope_and_pktlen(m, &ifscope, &mpktlen);
182
183 /*
184 * If the caller provides a route which is on a different interface
185 * than the one specified for scoped forwarding, discard the route
186 * and do a lookup below.
187 */
188 if (ifscope != IFSCOPE_NONE && (rt = ip6forward_rt->ro_rt) != NULL) {
189 RT_LOCK(rt);
190 if (rt->rt_ifp->if_index != ifscope) {
191 RT_UNLOCK(rt);
192 ROUTE_RELEASE(ip6forward_rt);
193 rt = NULL;
194 } else {
195 RT_UNLOCK(rt);
196 }
197 }
198 #endif /* PF */
199
200 #if IPSEC
201 /*
202 * Check AH/ESP integrity.
203 */
204 /*
205 * Don't increment ip6s_cantforward because this is the check
206 * before forwarding packet actually.
207 */
208 if (ipsec_bypass == 0) {
209 if (ipsec6_in_reject(m, NULL)) {
210 IPSEC_STAT_INCREMENT(ipsec6stat.in_polvio);
211 m_freem(m);
212 return NULL;
213 }
214 }
215 #endif /*IPSEC*/
216
217 /*
218 * Do not forward packets to multicast destination.
219 * Do not forward packets with unspecified source. It was discussed
220 * in July 2000, on ipngwg mailing list.
221 */
222 if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 ||
223 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
224 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
225 ip6stat.ip6s_cantforward++;
226 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
227 if (ip6_log_time + ip6_log_interval < curtime) {
228 ip6_log_time = curtime;
229 log(LOG_DEBUG,
230 "cannot forward "
231 "from %s to %s nxt %d received on %s\n",
232 ip6_sprintf(&ip6->ip6_src),
233 ip6_sprintf(&ip6->ip6_dst),
234 ip6->ip6_nxt,
235 if_name(m->m_pkthdr.rcvif));
236 }
237 m_freem(m);
238 return NULL;
239 }
240
241 if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
242 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
243 icmp6_error_flag(m, ICMP6_TIME_EXCEEDED,
244 ICMP6_TIME_EXCEED_TRANSIT, 0, 0);
245 return NULL;
246 }
247
248 /*
249 * See if the destination is a proxied address, and if so pretend
250 * that it's for us. This is mostly to handle NUD probes against
251 * the proxied addresses. We filter for ICMPv6 here and will let
252 * icmp6_input handle the rest.
253 */
254 if (!srcrt && nd6_prproxy) {
255 VERIFY(!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst));
256 proxy = nd6_prproxy_isours(m, ip6, ip6forward_rt, ifscope);
257 /*
258 * Don't update hop limit while proxying; RFC 4389 4.1.
259 * Also skip IPsec forwarding path processing as this
260 * packet is not to be forwarded.
261 */
262 if (proxy) {
263 goto skip_ipsec;
264 }
265 }
266
267 ip6->ip6_hlim -= IPV6_HLIMDEC;
268
269 /*
270 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
271 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
272 * we need to generate an ICMP6 message to the src.
273 * Thanks to M_EXT, in most cases copy will not occur.
274 *
275 * It is important to save it before IPsec processing as IPsec
276 * processing may modify the mbuf.
277 */
278 mcopy = m_copym_mode(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN),
279 M_DONTWAIT, M_COPYM_COPY_HDR);
280 #if IPSEC
281 if (ipsec_bypass != 0) {
282 goto skip_ipsec;
283 }
284 /* get a security policy for this packet */
285 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING,
286 &error);
287 if (sp == NULL) {
288 IPSEC_STAT_INCREMENT(ipsec6stat.out_inval);
289 ip6stat.ip6s_cantforward++;
290 if (mcopy) {
291 #if 0
292 /* XXX: what icmp ? */
293 #else
294 m_freem(mcopy);
295 #endif
296 }
297 m_freem(m);
298 return NULL;
299 }
300
301 error = 0;
302
303 /* check policy */
304 switch (sp->policy) {
305 case IPSEC_POLICY_DISCARD:
306 case IPSEC_POLICY_GENERATE:
307 /*
308 * This packet is just discarded.
309 */
310 IPSEC_STAT_INCREMENT(ipsec6stat.out_polvio);
311 ip6stat.ip6s_cantforward++;
312 key_freesp(sp, KEY_SADB_UNLOCKED);
313 if (mcopy) {
314 #if 0
315 /* XXX: what icmp ? */
316 #else
317 m_freem(mcopy);
318 #endif
319 }
320 m_freem(m);
321 return NULL;
322
323 case IPSEC_POLICY_BYPASS:
324 case IPSEC_POLICY_NONE:
325 /* no need to do IPsec. */
326 key_freesp(sp, KEY_SADB_UNLOCKED);
327 goto skip_ipsec;
328
329 case IPSEC_POLICY_IPSEC:
330 if (sp->req == NULL) {
331 /* XXX should be panic ? */
332 printf("ip6_forward: No IPsec request specified.\n");
333 ip6stat.ip6s_cantforward++;
334 key_freesp(sp, KEY_SADB_UNLOCKED);
335 if (mcopy) {
336 #if 0
337 /* XXX: what icmp ? */
338 #else
339 m_freem(mcopy);
340 #endif
341 }
342 m_freem(m);
343 return NULL;
344 }
345 /* do IPsec */
346 break;
347
348 case IPSEC_POLICY_ENTRUST:
349 default:
350 /* should be panic ?? */
351 printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
352 key_freesp(sp, KEY_SADB_UNLOCKED);
353 goto skip_ipsec;
354 }
355
356 {
357 struct ipsec_output_state state;
358
359 /*
360 * All the extension headers will become inaccessible
361 * (since they can be encrypted).
362 * Don't panic, we need no more updates to extension headers
363 * on inner IPv6 packet (since they are now encapsulated).
364 *
365 * IPv6 [ESP|AH] IPv6 [extension headers] payload
366 */
367 bzero(&state, sizeof(state));
368 state.m = m;
369 state.dst = NULL; /* update at ipsec6_output_tunnel() */
370
371 error = ipsec6_output_tunnel(&state, sp, 0);
372 key_freesp(sp, KEY_SADB_UNLOCKED);
373 if (state.tunneled == 4) {
374 ROUTE_RELEASE(&state.ro);
375 return NULL; /* packet is gone - sent over IPv4 */
376 }
377
378 m = state.m;
379 ROUTE_RELEASE(&state.ro);
380
381 if (error) {
382 /* mbuf is already reclaimed in ipsec6_output_tunnel. */
383 switch (error) {
384 case EHOSTUNREACH:
385 case ENETUNREACH:
386 case EMSGSIZE:
387 case ENOBUFS:
388 case ENOMEM:
389 break;
390 default:
391 printf("ip6_output (ipsec): error code %d\n", error);
392 OS_FALLTHROUGH;
393 case ENOENT:
394 /* don't show these error codes to the user */
395 break;
396 }
397 ip6stat.ip6s_cantforward++;
398 if (mcopy) {
399 #if 0
400 /* XXX: what icmp ? */
401 #else
402 m_freem(mcopy);
403 #endif
404 }
405 m_freem(m);
406 return NULL;
407 }
408 }
409 #endif /* IPSEC */
410 skip_ipsec:
411
412 dst = (struct sockaddr_in6 *)&ip6forward_rt->ro_dst;
413 if ((rt = ip6forward_rt->ro_rt) != NULL) {
414 RT_LOCK(rt);
415 /* Take an extra ref for ourselves */
416 RT_ADDREF_LOCKED(rt);
417 }
418
419 VERIFY(rt == NULL || rt == ip6forward_rt->ro_rt);
420 if (!srcrt) {
421 /*
422 * ip6forward_rt->ro_dst.sin6_addr is equal to ip6->ip6_dst
423 */
424 if (ROUTE_UNUSABLE(ip6forward_rt)) {
425 if (rt != NULL) {
426 /* Release extra ref */
427 RT_REMREF_LOCKED(rt);
428 RT_UNLOCK(rt);
429 }
430 ROUTE_RELEASE(ip6forward_rt);
431
432 /* this probably fails but give it a try again */
433 rtalloc_scoped_ign((struct route *)ip6forward_rt,
434 RTF_PRCLONING, ifscope);
435 if ((rt = ip6forward_rt->ro_rt) != NULL) {
436 RT_LOCK(rt);
437 /* Take an extra ref for ourselves */
438 RT_ADDREF_LOCKED(rt);
439 }
440 }
441
442 if (rt == NULL) {
443 ip6stat.ip6s_noroute++;
444 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
445 if (mcopy) {
446 icmp6_error(mcopy, ICMP6_DST_UNREACH,
447 ICMP6_DST_UNREACH_NOROUTE, 0);
448 }
449 m_freem(m);
450 return NULL;
451 }
452 RT_LOCK_ASSERT_HELD(rt);
453 } else if (ROUTE_UNUSABLE(ip6forward_rt) ||
454 !in6_are_addr_equal_scoped(&ip6->ip6_dst, &dst->sin6_addr, ip6_input_getdstifscope(m), dst->sin6_scope_id)) {
455 if (rt != NULL) {
456 /* Release extra ref */
457 RT_REMREF_LOCKED(rt);
458 RT_UNLOCK(rt);
459 }
460 ROUTE_RELEASE(ip6forward_rt);
461
462 bzero(dst, sizeof(*dst));
463 dst->sin6_len = sizeof(struct sockaddr_in6);
464 dst->sin6_family = AF_INET6;
465 dst->sin6_addr = ip6->ip6_dst;
466
467 rtalloc_scoped_ign((struct route *)ip6forward_rt,
468 RTF_PRCLONING, ifscope);
469 if ((rt = ip6forward_rt->ro_rt) == NULL) {
470 ip6stat.ip6s_noroute++;
471 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
472 if (mcopy) {
473 icmp6_error(mcopy, ICMP6_DST_UNREACH,
474 ICMP6_DST_UNREACH_NOROUTE, 0);
475 }
476 m_freem(m);
477 return NULL;
478 }
479 RT_LOCK(rt);
480 /* Take an extra ref for ourselves */
481 RT_ADDREF_LOCKED(rt);
482 }
483
484 /*
485 * Source scope check: if a packet can't be delivered to its
486 * destination for the reason that the destination is beyond the scope
487 * of the source address, discard the packet and return an icmp6
488 * destination unreachable error with Code 2 (beyond scope of source
489 * address) unless we are proxying (source address is link local
490 * for NUDs.) We use a local copy of ip6_src, since in6_setscope()
491 * will possibly modify its first argument.
492 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
493 */
494 src_in6 = ip6->ip6_src;
495 if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
496 RT_REMREF_LOCKED(rt);
497 RT_UNLOCK(rt);
498 /* XXX: this should not happen */
499 ip6stat.ip6s_cantforward++;
500 ip6stat.ip6s_badscope++;
501 m_freem(m);
502 return NULL;
503 }
504 if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
505 RT_REMREF_LOCKED(rt);
506 RT_UNLOCK(rt);
507 ip6stat.ip6s_cantforward++;
508 ip6stat.ip6s_badscope++;
509 m_freem(m);
510 return NULL;
511 }
512
513 if (inzone != outzone && !proxy) {
514 ip6stat.ip6s_cantforward++;
515 ip6stat.ip6s_badscope++;
516 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
517
518 if (ip6_log_time + ip6_log_interval < curtime) {
519 ip6_log_time = curtime;
520 log(LOG_DEBUG,
521 "cannot forward "
522 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
523 ip6_sprintf(&ip6->ip6_src),
524 ip6_sprintf(&ip6->ip6_dst),
525 ip6->ip6_nxt,
526 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
527 }
528 /* Release extra ref */
529 RT_REMREF_LOCKED(rt);
530 RT_UNLOCK(rt);
531 if (mcopy) {
532 icmp6_error(mcopy, ICMP6_DST_UNREACH,
533 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
534 }
535 m_freem(m);
536 return NULL;
537 }
538
539 /*
540 * Destination scope check: if a packet is going to break the scope
541 * zone of packet's destination address, discard it. This case should
542 * usually be prevented by appropriately-configured routing table, but
543 * we need an explicit check because we may mistakenly forward the
544 * packet to a different zone by (e.g.) a default route.
545 */
546 dst_in6 = ip6->ip6_dst;
547 if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
548 in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
549 inzone != outzone) {
550 RT_REMREF_LOCKED(rt);
551 RT_UNLOCK(rt);
552 ip6stat.ip6s_cantforward++;
553 ip6stat.ip6s_badscope++;
554 m_freem(m);
555 return NULL;
556 }
557
558 if (mpktlen == 0) {
559 mpktlen = m->m_pkthdr.len;
560 }
561
562 if (mpktlen > rt->rt_ifp->if_mtu) {
563 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
564 if (mcopy) {
565 uint32_t mtu;
566 #if IPSEC
567 struct secpolicy *sp2;
568 int ipsecerror;
569 size_t ipsechdrsiz;
570 #endif
571
572 mtu = rt->rt_ifp->if_mtu;
573 #if IPSEC
574 /*
575 * When we do IPsec tunnel ingress, we need to play
576 * with the link value (decrement IPsec header size
577 * from mtu value). The code is much simpler than v4
578 * case, as we have the outgoing interface for
579 * encapsulated packet as "rt->rt_ifp".
580 */
581 sp2 = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
582 IP_FORWARDING, &ipsecerror);
583 if (sp2) {
584 ipsechdrsiz = ipsec6_hdrsiz(mcopy,
585 IPSEC_DIR_OUTBOUND, NULL);
586 if (ipsechdrsiz < mtu) {
587 mtu -= ipsechdrsiz;
588 }
589 key_freesp(sp2, KEY_SADB_UNLOCKED);
590 }
591 /*
592 * if mtu becomes less than minimum MTU,
593 * tell minimum MTU (and I'll need to fragment it).
594 */
595 if (mtu < IPV6_MMTU) {
596 mtu = IPV6_MMTU;
597 }
598 #endif
599 /* Release extra ref */
600 RT_REMREF_LOCKED(rt);
601 RT_UNLOCK(rt);
602 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
603 } else {
604 /* Release extra ref */
605 RT_REMREF_LOCKED(rt);
606 RT_UNLOCK(rt);
607 }
608 m_freem(m);
609 return NULL;
610 }
611
612 if (rt->rt_flags & RTF_GATEWAY) {
613 dst = (struct sockaddr_in6 *)(void *)rt->rt_gateway;
614 }
615
616 /*
617 * If we are to forward the packet using the same interface
618 * as one we got the packet from, perhaps we should send a redirect
619 * to sender to shortcut a hop.
620 * Only send redirect if source is sending directly to us,
621 * and if packet was not source routed (or has any options).
622 * Also, don't send redirect if forwarding using a route
623 * modified by a redirect.
624 */
625 if (!proxy &&
626 ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
627 (rt->rt_flags & (RTF_DYNAMIC | RTF_MODIFIED)) == 0) {
628 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
629 /*
630 * If the incoming interface is equal to the outgoing
631 * one, and the link attached to the interface is
632 * point-to-point, then it will be highly probable
633 * that a routing loop occurs. Thus, we immediately
634 * drop the packet and send an ICMPv6 error message.
635 *
636 * type/code is based on suggestion by Rich Draves.
637 * not sure if it is the best pick.
638 */
639 RT_REMREF_LOCKED(rt); /* Release extra ref */
640 RT_UNLOCK(rt);
641 icmp6_error(mcopy, ICMP6_DST_UNREACH,
642 ICMP6_DST_UNREACH_ADDR, 0);
643 m_freem(m);
644 return NULL;
645 }
646 type = ND_REDIRECT;
647 }
648 /*
649 * Fake scoped addresses. Note that even link-local source or
650 * destinaion can appear, if the originating node just sends the
651 * packet to us (without address resolution for the destination).
652 * Since both icmp6_error and icmp6_redirect_output fill the embedded
653 * link identifiers, we can do this stuff after making a copy for
654 * returning an error.
655 */
656 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
657 /*
658 * See corresponding comments in ip6_output.
659 * XXX: but is it possible that ip6_forward() sends a packet
660 * to a loopback interface? I don't think so, and thus
661 * I bark here. ([email protected])
662 * XXX: it is common to route invalid packets to loopback.
663 * also, the codepath will be visited on use of ::1 in
664 * rthdr. (itojun)
665 */
666 #if 1
667 if ((0))
668 #else
669 if ((rt->rt_flags & (RTF_BLACKHOLE | RTF_REJECT)) == 0)
670 #endif
671 {
672 printf("ip6_forward: outgoing interface is loopback. "
673 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
674 ip6_sprintf(&ip6->ip6_src),
675 ip6_sprintf(&ip6->ip6_dst),
676 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
677 if_name(rt->rt_ifp));
678 }
679
680 /* we can just use rcvif in forwarding. */
681 origifp = rcvifp = m->m_pkthdr.rcvif;
682 } else if (nd6_prproxy) {
683 /*
684 * In the prefix proxying case, we need to inform nd6_output()
685 * about the inbound interface, so that any subsequent NS
686 * packets generated by nd6_prproxy_ns_output() will not be
687 * sent back to that same interface.
688 */
689 origifp = rcvifp = m->m_pkthdr.rcvif;
690 } else {
691 rcvifp = m->m_pkthdr.rcvif;
692 origifp = rt->rt_ifp;
693 }
694 /*
695 * clear embedded scope identifiers if necessary.
696 * in6_clearscope will touch the addresses only when necessary.
697 */
698 in6_clearscope(&ip6->ip6_src);
699 in6_clearscope(&ip6->ip6_dst);
700
701 ifp = rt->rt_ifp;
702 /* Drop the lock but retain the extra ref */
703 RT_UNLOCK(rt);
704
705 /*
706 * If this is to be processed locally, let ip6_input have it.
707 */
708 if (proxy) {
709 VERIFY(m->m_pkthdr.pkt_flags & PKTF_PROXY_DST);
710 /* Release extra ref */
711 RT_REMREF(rt);
712 if (mcopy != NULL) {
713 m_freem(mcopy);
714 }
715 return m;
716 }
717
718 /* Mark this packet as being forwarded from another interface */
719 m->m_pkthdr.pkt_flags |= PKTF_FORWARDED;
720
721 #if PF
722 if (PF_IS_ENABLED) {
723 /*
724 * PF refragments any packet which it reassembled due to scrub
725 * rules, in which case it will set the PF_TAG_REFRAGMENTED
726 * flag in PF mbuf tag.
727 */
728 #if DUMMYNET
729 struct ip_fw_args args;
730 struct pf_mtag *pf_mtag;
731
732 bzero(&args, sizeof(args));
733
734 args.fwa_oif = ifp;
735 args.fwa_oflags = 0;
736 args.fwa_ro6 = ip6forward_rt;
737 args.fwa_ro6_pmtu = ip6forward_rt;
738 args.fwa_mtu = rt->rt_ifp->if_mtu;
739 args.fwa_dst6 = dst;
740 args.fwa_origifp = origifp;
741 /* Invoke outbound packet filter */
742 error = pf_af_hook(ifp, NULL, &m, AF_INET6, FALSE, &args);
743 #else /* !DUMMYNET */
744 error = pf_af_hook(ifp, NULL, &m, AF_INET6, FALSE, NULL);
745 #endif /* !DUMMYNET */
746 if (error != 0 || m == NULL) {
747 if (m != NULL) {
748 panic("%s: unexpected packet %p", __func__, m);
749 /* NOTREACHED */
750 }
751 /* Already freed by callee */
752 goto senderr;
753 }
754
755 pf_mtag = pf_find_mtag(m);
756 /*
757 * refragmented packets from PF.
758 */
759 if ((pf_mtag->pftag_flags & PF_TAG_REFRAGMENTED) != 0) {
760 struct mbuf *t;
761
762 pf_mtag->pftag_flags &= ~PF_TAG_REFRAGMENTED;
763 /* for statistics */
764 t = m;
765 while (t != NULL) {
766 pktcnt++;
767 len += m_pktlen(t);
768 t = t->m_nextpkt;
769 }
770
771 /*
772 * nd6_output() frees packetchain in both success and
773 * failure cases.
774 */
775 error = nd6_output(ifp, origifp, m, dst, rt, NULL);
776 m = NULL;
777 goto sent;
778 }
779 /*
780 * We do not use ip6 header again in the code below,
781 * however still adding the bit here so that any new
782 * code in future doesn't end up working with the
783 * wrong pointer
784 */
785 ip6 = mtod(m, struct ip6_hdr *);
786 }
787 #endif /* PF */
788
789 len = m_pktlen(m);
790 pktcnt = 1;
791 error = nd6_output(ifp, origifp, m, dst, rt, NULL);
792 sent:
793 if (error) {
794 in6_ifstat_add(ifp, ifs6_out_discard, pktcnt);
795 ip6stat.ip6s_cantforward += pktcnt;
796 } else {
797 /*
798 * Increment stats on the source interface; the ones
799 * for destination interface has been taken care of
800 * during output above by virtue of PKTF_FORWARDED.
801 */
802 rcvifp->if_fpackets += pktcnt;
803 rcvifp->if_fbytes += len;
804
805 ip6stat.ip6s_forward += pktcnt;
806 in6_ifstat_add(ifp, ifs6_out_forward, pktcnt);
807 if (type) {
808 ip6stat.ip6s_redirectsent++;
809 } else {
810 if (mcopy) {
811 goto freecopy;
812 }
813 }
814 }
815 #if PF
816 senderr:
817 #endif /* PF */
818 if (mcopy == NULL) {
819 /* Release extra ref */
820 RT_REMREF(rt);
821 return NULL;
822 }
823 switch (error) {
824 case 0:
825 #if 1
826 if (type == ND_REDIRECT) {
827 icmp6_redirect_output(mcopy, rt);
828 /* Release extra ref */
829 RT_REMREF(rt);
830 return NULL;
831 }
832 #endif
833 goto freecopy;
834
835 case EMSGSIZE:
836 /* xxx MTU is constant in PPP? */
837 goto freecopy;
838
839 case ENOBUFS:
840 /* Tell source to slow down like source quench in IP? */
841 goto freecopy;
842
843 case ENETUNREACH: /* shouldn't happen, checked above */
844 case EHOSTUNREACH:
845 case ENETDOWN:
846 case EHOSTDOWN:
847 default:
848 type = ICMP6_DST_UNREACH;
849 code = ICMP6_DST_UNREACH_ADDR;
850 break;
851 }
852 icmp6_error(mcopy, type, code, 0);
853 /* Release extra ref */
854 RT_REMREF(rt);
855 return NULL;
856
857 freecopy:
858 m_freem(mcopy);
859 /* Release extra ref */
860 RT_REMREF(rt);
861 return NULL;
862 }
863