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, |
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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 |
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 | #include <net/sockaddr_utils.h> |
129 | |
130 | /* |
131 | * Forward a packet. If some error occurs return the sender |
132 | * an icmp packet. Note we can't always generate a meaningful |
133 | * icmp message because icmp doesn't have a large enough repertoire |
134 | * of codes and types. |
135 | * |
136 | * If not forwarding, just drop the packet. This could be confusing |
137 | * if ipforwarding was zero but some routing protocol was advancing |
138 | * us as a gateway to somewhere. However, we must let the routing |
139 | * protocol deal with that. |
140 | * |
141 | */ |
142 | |
143 | struct mbuf * |
144 | ip6_forward(struct mbuf *m, struct route_in6 *ip6forward_rt, |
145 | int srcrt) |
146 | { |
147 | struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); |
148 | struct sockaddr_in6 *dst; |
149 | struct rtentry *rt; |
150 | int error, type = 0, code = 0; |
151 | boolean_t proxy = FALSE; |
152 | struct mbuf *mcopy = NULL; |
153 | struct ifnet *ifp, *rcvifp, *origifp; /* maybe unnecessary */ |
154 | u_int32_t inzone, outzone, len = 0, pktcnt = 0; |
155 | struct in6_addr src_in6, dst_in6; |
156 | uint64_t curtime = net_uptime(); |
157 | #if IPSEC |
158 | struct secpolicy *sp = NULL; |
159 | #endif |
160 | unsigned int ifscope = IFSCOPE_NONE; |
161 | uint32_t mpktlen = 0; |
162 | |
163 | /* |
164 | * In the prefix proxying case, the route to the proxied node normally |
165 | * gets created by nd6_prproxy_ns_output(), as part of forwarding a |
166 | * NS (NUD/AR) packet to the proxied node. In the event that such |
167 | * packet did not arrive in time before the correct route gets created, |
168 | * ip6_input() would have performed a rtalloc() which most likely will |
169 | * create the wrong cloned route; this route points back to the same |
170 | * interface as the inbound interface, since the parent non-scoped |
171 | * prefix route points there. Therefore we check if that is the case |
172 | * and perform the necessary fixup to get the correct route installed. |
173 | */ |
174 | if (!srcrt && nd6_prproxy && |
175 | (rt = ip6forward_rt->ro_rt) != NULL && (rt->rt_flags & RTF_PROXY)) { |
176 | nd6_proxy_find_fwdroute(m->m_pkthdr.rcvif, ip6forward_rt); |
177 | if ((rt = ip6forward_rt->ro_rt) != NULL) { |
178 | ifscope = rt->rt_ifp->if_index; |
179 | } |
180 | } |
181 | |
182 | #if PF |
183 | adjust_scope_and_pktlen(m, ifscope_p: &ifscope, mpktlen_p: &mpktlen); |
184 | |
185 | /* |
186 | * If the caller provides a route which is on a different interface |
187 | * than the one specified for scoped forwarding, discard the route |
188 | * and do a lookup below. |
189 | */ |
190 | if (ifscope != IFSCOPE_NONE && (rt = ip6forward_rt->ro_rt) != NULL) { |
191 | RT_LOCK(rt); |
192 | if (rt->rt_ifp->if_index != ifscope) { |
193 | RT_UNLOCK(rt); |
194 | ROUTE_RELEASE(ip6forward_rt); |
195 | rt = NULL; |
196 | } else { |
197 | RT_UNLOCK(rt); |
198 | } |
199 | } |
200 | #endif /* PF */ |
201 | |
202 | #if IPSEC |
203 | /* |
204 | * Check AH/ESP integrity. |
205 | */ |
206 | /* |
207 | * Don't increment ip6s_cantforward because this is the check |
208 | * before forwarding packet actually. |
209 | */ |
210 | if (ipsec_bypass == 0) { |
211 | if (ipsec6_in_reject(m, NULL)) { |
212 | IPSEC_STAT_INCREMENT(ipsec6stat.in_polvio); |
213 | m_freem(m); |
214 | return NULL; |
215 | } |
216 | } |
217 | #endif /*IPSEC*/ |
218 | |
219 | /* |
220 | * Do not forward packets to multicast destination. |
221 | * Do not forward packets with unspecified source. It was discussed |
222 | * in July 2000, on ipngwg mailing list. |
223 | */ |
224 | if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 || |
225 | IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
226 | IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { |
227 | ip6stat.ip6s_cantforward++; |
228 | /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ |
229 | if (ip6_log_time + ip6_log_interval < curtime) { |
230 | ip6_log_time = curtime; |
231 | log(LOG_DEBUG, |
232 | "cannot forward " |
233 | "from %s to %s nxt %d received on %s\n" , |
234 | ip6_sprintf(&ip6->ip6_src), |
235 | ip6_sprintf(&ip6->ip6_dst), |
236 | ip6->ip6_nxt, |
237 | if_name(m->m_pkthdr.rcvif)); |
238 | } |
239 | m_freem(m); |
240 | return NULL; |
241 | } |
242 | |
243 | if (ip6->ip6_hlim <= IPV6_HLIMDEC) { |
244 | /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ |
245 | icmp6_error_flag(m, ICMP6_TIME_EXCEEDED, |
246 | ICMP6_TIME_EXCEED_TRANSIT, 0, 0); |
247 | return NULL; |
248 | } |
249 | |
250 | /* |
251 | * See if the destination is a proxied address, and if so pretend |
252 | * that it's for us. This is mostly to handle NUD probes against |
253 | * the proxied addresses. We filter for ICMPv6 here and will let |
254 | * icmp6_input handle the rest. |
255 | */ |
256 | if (!srcrt && nd6_prproxy) { |
257 | VERIFY(!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)); |
258 | proxy = nd6_prproxy_isours(m, ip6, ip6forward_rt, ifscope); |
259 | /* |
260 | * Don't update hop limit while proxying; RFC 4389 4.1. |
261 | * Also skip IPsec forwarding path processing as this |
262 | * packet is not to be forwarded. |
263 | */ |
264 | if (proxy) { |
265 | goto skip_ipsec; |
266 | } |
267 | } |
268 | |
269 | ip6->ip6_hlim -= IPV6_HLIMDEC; |
270 | |
271 | /* |
272 | * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - |
273 | * size of IPv6 + ICMPv6 headers) bytes of the packet in case |
274 | * we need to generate an ICMP6 message to the src. |
275 | * Thanks to M_EXT, in most cases copy will not occur. |
276 | * |
277 | * It is important to save it before IPsec processing as IPsec |
278 | * processing may modify the mbuf. |
279 | */ |
280 | mcopy = m_copym_mode(m, 0, imin(a: m->m_pkthdr.len, ICMPV6_PLD_MAXLEN), |
281 | M_DONTWAIT, NULL, NULL, M_COPYM_COPY_HDR); |
282 | #if IPSEC |
283 | if (ipsec_bypass != 0) { |
284 | goto skip_ipsec; |
285 | } |
286 | /* get a security policy for this packet */ |
287 | sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING, |
288 | &error); |
289 | if (sp == NULL) { |
290 | IPSEC_STAT_INCREMENT(ipsec6stat.out_inval); |
291 | ip6stat.ip6s_cantforward++; |
292 | if (mcopy) { |
293 | #if 0 |
294 | /* XXX: what icmp ? */ |
295 | #else |
296 | m_freem(mcopy); |
297 | #endif |
298 | } |
299 | m_freem(m); |
300 | return NULL; |
301 | } |
302 | |
303 | error = 0; |
304 | |
305 | /* check policy */ |
306 | switch (sp->policy) { |
307 | case IPSEC_POLICY_DISCARD: |
308 | case IPSEC_POLICY_GENERATE: |
309 | /* |
310 | * This packet is just discarded. |
311 | */ |
312 | IPSEC_STAT_INCREMENT(ipsec6stat.out_polvio); |
313 | ip6stat.ip6s_cantforward++; |
314 | key_freesp(sp, KEY_SADB_UNLOCKED); |
315 | if (mcopy) { |
316 | #if 0 |
317 | /* XXX: what icmp ? */ |
318 | #else |
319 | m_freem(mcopy); |
320 | #endif |
321 | } |
322 | m_freem(m); |
323 | return NULL; |
324 | |
325 | case IPSEC_POLICY_BYPASS: |
326 | case IPSEC_POLICY_NONE: |
327 | /* no need to do IPsec. */ |
328 | key_freesp(sp, KEY_SADB_UNLOCKED); |
329 | goto skip_ipsec; |
330 | |
331 | case IPSEC_POLICY_IPSEC: |
332 | if (sp->req == NULL) { |
333 | /* XXX should be panic ? */ |
334 | printf("ip6_forward: No IPsec request specified.\n" ); |
335 | ip6stat.ip6s_cantforward++; |
336 | key_freesp(sp, KEY_SADB_UNLOCKED); |
337 | if (mcopy) { |
338 | #if 0 |
339 | /* XXX: what icmp ? */ |
340 | #else |
341 | m_freem(mcopy); |
342 | #endif |
343 | } |
344 | m_freem(m); |
345 | return NULL; |
346 | } |
347 | /* do IPsec */ |
348 | break; |
349 | |
350 | case IPSEC_POLICY_ENTRUST: |
351 | default: |
352 | /* should be panic ?? */ |
353 | printf("ip6_forward: Invalid policy found. %d\n" , sp->policy); |
354 | key_freesp(sp, KEY_SADB_UNLOCKED); |
355 | goto skip_ipsec; |
356 | } |
357 | |
358 | { |
359 | struct ipsec_output_state state; |
360 | |
361 | /* |
362 | * All the extension headers will become inaccessible |
363 | * (since they can be encrypted). |
364 | * Don't panic, we need no more updates to extension headers |
365 | * on inner IPv6 packet (since they are now encapsulated). |
366 | * |
367 | * IPv6 [ESP|AH] IPv6 [extension headers] payload |
368 | */ |
369 | bzero(s: &state, n: sizeof(state)); |
370 | state.m = m; |
371 | state.dst = NULL; /* update at ipsec6_output_tunnel() */ |
372 | |
373 | error = ipsec6_output_tunnel(&state, sp, 0); |
374 | key_freesp(sp, KEY_SADB_UNLOCKED); |
375 | if (state.tunneled == 4) { |
376 | ROUTE_RELEASE(&state.ro); |
377 | return NULL; /* packet is gone - sent over IPv4 */ |
378 | } |
379 | |
380 | m = state.m; |
381 | ROUTE_RELEASE(&state.ro); |
382 | |
383 | if (error) { |
384 | /* mbuf is already reclaimed in ipsec6_output_tunnel. */ |
385 | switch (error) { |
386 | case EHOSTUNREACH: |
387 | case ENETUNREACH: |
388 | case EMSGSIZE: |
389 | case ENOBUFS: |
390 | case ENOMEM: |
391 | break; |
392 | default: |
393 | printf("ip6_output (ipsec): error code %d\n" , error); |
394 | OS_FALLTHROUGH; |
395 | case ENOENT: |
396 | /* don't show these error codes to the user */ |
397 | break; |
398 | } |
399 | ip6stat.ip6s_cantforward++; |
400 | if (mcopy) { |
401 | #if 0 |
402 | /* XXX: what icmp ? */ |
403 | #else |
404 | m_freem(mcopy); |
405 | #endif |
406 | } |
407 | m_freem(m); |
408 | return NULL; |
409 | } |
410 | } |
411 | #endif /* IPSEC */ |
412 | skip_ipsec: |
413 | |
414 | dst = SIN6(&ip6forward_rt->ro_dst); |
415 | if ((rt = ip6forward_rt->ro_rt) != NULL) { |
416 | RT_LOCK(rt); |
417 | /* Take an extra ref for ourselves */ |
418 | RT_ADDREF_LOCKED(rt); |
419 | } |
420 | |
421 | VERIFY(rt == NULL || rt == ip6forward_rt->ro_rt); |
422 | if (!srcrt) { |
423 | /* |
424 | * ip6forward_rt->ro_dst.sin6_addr is equal to ip6->ip6_dst |
425 | */ |
426 | if (ROUTE_UNUSABLE(ip6forward_rt)) { |
427 | if (rt != NULL) { |
428 | /* Release extra ref */ |
429 | RT_REMREF_LOCKED(rt); |
430 | RT_UNLOCK(rt); |
431 | } |
432 | ROUTE_RELEASE(ip6forward_rt); |
433 | |
434 | /* this probably fails but give it a try again */ |
435 | rtalloc_scoped_ign((struct route *)ip6forward_rt, |
436 | RTF_PRCLONING, ifscope); |
437 | if ((rt = ip6forward_rt->ro_rt) != NULL) { |
438 | RT_LOCK(rt); |
439 | /* Take an extra ref for ourselves */ |
440 | RT_ADDREF_LOCKED(rt); |
441 | } |
442 | } |
443 | |
444 | if (rt == NULL) { |
445 | ip6stat.ip6s_noroute++; |
446 | in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); |
447 | if (mcopy) { |
448 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
449 | ICMP6_DST_UNREACH_NOROUTE, 0); |
450 | } |
451 | m_freem(m); |
452 | return NULL; |
453 | } |
454 | RT_LOCK_ASSERT_HELD(rt); |
455 | } else if (ROUTE_UNUSABLE(ip6forward_rt) || |
456 | !in6_are_addr_equal_scoped(&ip6->ip6_dst, &dst->sin6_addr, ip6_input_getdstifscope(m), dst->sin6_scope_id)) { |
457 | if (rt != NULL) { |
458 | /* Release extra ref */ |
459 | RT_REMREF_LOCKED(rt); |
460 | RT_UNLOCK(rt); |
461 | } |
462 | ROUTE_RELEASE(ip6forward_rt); |
463 | |
464 | SOCKADDR_ZERO(dst, sizeof(*dst)); |
465 | dst->sin6_len = sizeof(struct sockaddr_in6); |
466 | dst->sin6_family = AF_INET6; |
467 | dst->sin6_addr = ip6->ip6_dst; |
468 | |
469 | rtalloc_scoped_ign((struct route *)ip6forward_rt, |
470 | RTF_PRCLONING, ifscope); |
471 | if ((rt = ip6forward_rt->ro_rt) == NULL) { |
472 | ip6stat.ip6s_noroute++; |
473 | in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); |
474 | if (mcopy) { |
475 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
476 | ICMP6_DST_UNREACH_NOROUTE, 0); |
477 | } |
478 | m_freem(m); |
479 | return NULL; |
480 | } |
481 | RT_LOCK(rt); |
482 | /* Take an extra ref for ourselves */ |
483 | RT_ADDREF_LOCKED(rt); |
484 | } |
485 | |
486 | /* |
487 | * Source scope check: if a packet can't be delivered to its |
488 | * destination for the reason that the destination is beyond the scope |
489 | * of the source address, discard the packet and return an icmp6 |
490 | * destination unreachable error with Code 2 (beyond scope of source |
491 | * address) unless we are proxying (source address is link local |
492 | * for NUDs.) We use a local copy of ip6_src, since in6_setscope() |
493 | * will possibly modify its first argument. |
494 | * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1] |
495 | */ |
496 | src_in6 = ip6->ip6_src; |
497 | if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) { |
498 | RT_REMREF_LOCKED(rt); |
499 | RT_UNLOCK(rt); |
500 | /* XXX: this should not happen */ |
501 | ip6stat.ip6s_cantforward++; |
502 | ip6stat.ip6s_badscope++; |
503 | m_freem(m); |
504 | return NULL; |
505 | } |
506 | if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) { |
507 | RT_REMREF_LOCKED(rt); |
508 | RT_UNLOCK(rt); |
509 | ip6stat.ip6s_cantforward++; |
510 | ip6stat.ip6s_badscope++; |
511 | m_freem(m); |
512 | return NULL; |
513 | } |
514 | |
515 | if (inzone != outzone && !proxy) { |
516 | ip6stat.ip6s_cantforward++; |
517 | ip6stat.ip6s_badscope++; |
518 | in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); |
519 | |
520 | if (ip6_log_time + ip6_log_interval < curtime) { |
521 | ip6_log_time = curtime; |
522 | log(LOG_DEBUG, |
523 | "cannot forward " |
524 | "src %s, dst %s, nxt %d, rcvif %s, outif %s\n" , |
525 | ip6_sprintf(&ip6->ip6_src), |
526 | ip6_sprintf(&ip6->ip6_dst), |
527 | ip6->ip6_nxt, |
528 | if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); |
529 | } |
530 | /* Release extra ref */ |
531 | RT_REMREF_LOCKED(rt); |
532 | RT_UNLOCK(rt); |
533 | if (mcopy) { |
534 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
535 | ICMP6_DST_UNREACH_BEYONDSCOPE, 0); |
536 | } |
537 | m_freem(m); |
538 | return NULL; |
539 | } |
540 | |
541 | /* |
542 | * Destination scope check: if a packet is going to break the scope |
543 | * zone of packet's destination address, discard it. This case should |
544 | * usually be prevented by appropriately-configured routing table, but |
545 | * we need an explicit check because we may mistakenly forward the |
546 | * packet to a different zone by (e.g.) a default route. |
547 | */ |
548 | dst_in6 = ip6->ip6_dst; |
549 | if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 || |
550 | in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 || |
551 | inzone != outzone) { |
552 | RT_REMREF_LOCKED(rt); |
553 | RT_UNLOCK(rt); |
554 | ip6stat.ip6s_cantforward++; |
555 | ip6stat.ip6s_badscope++; |
556 | m_freem(m); |
557 | return NULL; |
558 | } |
559 | |
560 | if (mpktlen == 0) { |
561 | mpktlen = m->m_pkthdr.len; |
562 | } |
563 | |
564 | if (mpktlen > rt->rt_ifp->if_mtu) { |
565 | in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); |
566 | if (mcopy) { |
567 | uint32_t mtu; |
568 | #if IPSEC |
569 | struct secpolicy *sp2; |
570 | int ipsecerror; |
571 | size_t ipsechdrsiz; |
572 | #endif |
573 | |
574 | mtu = rt->rt_ifp->if_mtu; |
575 | #if IPSEC |
576 | /* |
577 | * When we do IPsec tunnel ingress, we need to play |
578 | * with the link value (decrement IPsec header size |
579 | * from mtu value). The code is much simpler than v4 |
580 | * case, as we have the outgoing interface for |
581 | * encapsulated packet as "rt->rt_ifp". |
582 | */ |
583 | sp2 = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, |
584 | IP_FORWARDING, &ipsecerror); |
585 | if (sp2) { |
586 | ipsechdrsiz = ipsec6_hdrsiz(mcopy, |
587 | IPSEC_DIR_OUTBOUND, NULL); |
588 | if (ipsechdrsiz < mtu) { |
589 | mtu -= ipsechdrsiz; |
590 | } |
591 | key_freesp(sp2, KEY_SADB_UNLOCKED); |
592 | } |
593 | /* |
594 | * if mtu becomes less than minimum MTU, |
595 | * tell minimum MTU (and I'll need to fragment it). |
596 | */ |
597 | if (mtu < IPV6_MMTU) { |
598 | mtu = IPV6_MMTU; |
599 | } |
600 | #endif |
601 | /* Release extra ref */ |
602 | RT_REMREF_LOCKED(rt); |
603 | RT_UNLOCK(rt); |
604 | icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); |
605 | } else { |
606 | /* Release extra ref */ |
607 | RT_REMREF_LOCKED(rt); |
608 | RT_UNLOCK(rt); |
609 | } |
610 | m_freem(m); |
611 | return NULL; |
612 | } |
613 | |
614 | if (rt->rt_flags & RTF_GATEWAY) { |
615 | dst = SIN6(rt->rt_gateway); |
616 | } |
617 | |
618 | /* |
619 | * If we are to forward the packet using the same interface |
620 | * as one we got the packet from, perhaps we should send a redirect |
621 | * to sender to shortcut a hop. |
622 | * Only send redirect if source is sending directly to us, |
623 | * and if packet was not source routed (or has any options). |
624 | * Also, don't send redirect if forwarding using a route |
625 | * modified by a redirect. |
626 | */ |
627 | if (!proxy && |
628 | ip6_sendredirects && rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && |
629 | (rt->rt_flags & (RTF_DYNAMIC | RTF_MODIFIED)) == 0) { |
630 | if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { |
631 | /* |
632 | * If the incoming interface is equal to the outgoing |
633 | * one, and the link attached to the interface is |
634 | * point-to-point, then it will be highly probable |
635 | * that a routing loop occurs. Thus, we immediately |
636 | * drop the packet and send an ICMPv6 error message. |
637 | * |
638 | * type/code is based on suggestion by Rich Draves. |
639 | * not sure if it is the best pick. |
640 | */ |
641 | RT_REMREF_LOCKED(rt); /* Release extra ref */ |
642 | RT_UNLOCK(rt); |
643 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
644 | ICMP6_DST_UNREACH_ADDR, 0); |
645 | m_freem(m); |
646 | return NULL; |
647 | } |
648 | type = ND_REDIRECT; |
649 | } |
650 | /* |
651 | * Fake scoped addresses. Note that even link-local source or |
652 | * destinaion can appear, if the originating node just sends the |
653 | * packet to us (without address resolution for the destination). |
654 | * Since both icmp6_error and icmp6_redirect_output fill the embedded |
655 | * link identifiers, we can do this stuff after making a copy for |
656 | * returning an error. |
657 | */ |
658 | if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { |
659 | /* |
660 | * See corresponding comments in ip6_output. |
661 | * XXX: but is it possible that ip6_forward() sends a packet |
662 | * to a loopback interface? I don't think so, and thus |
663 | * I bark here. (jinmei@kame.net) |
664 | * XXX: it is common to route invalid packets to loopback. |
665 | * also, the codepath will be visited on use of ::1 in |
666 | * rthdr. (itojun) |
667 | */ |
668 | #if 1 |
669 | if ((0)) |
670 | #else |
671 | if ((rt->rt_flags & (RTF_BLACKHOLE | RTF_REJECT)) == 0) |
672 | #endif |
673 | { |
674 | printf("ip6_forward: outgoing interface is loopback. " |
675 | "src %s, dst %s, nxt %d, rcvif %s, outif %s\n" , |
676 | ip6_sprintf(&ip6->ip6_src), |
677 | ip6_sprintf(&ip6->ip6_dst), |
678 | ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), |
679 | if_name(rt->rt_ifp)); |
680 | } |
681 | |
682 | /* we can just use rcvif in forwarding. */ |
683 | origifp = rcvifp = m->m_pkthdr.rcvif; |
684 | } else if (nd6_prproxy) { |
685 | /* |
686 | * In the prefix proxying case, we need to inform nd6_output() |
687 | * about the inbound interface, so that any subsequent NS |
688 | * packets generated by nd6_prproxy_ns_output() will not be |
689 | * sent back to that same interface. |
690 | */ |
691 | origifp = rcvifp = m->m_pkthdr.rcvif; |
692 | } else { |
693 | rcvifp = m->m_pkthdr.rcvif; |
694 | origifp = rt->rt_ifp; |
695 | } |
696 | /* |
697 | * clear embedded scope identifiers if necessary. |
698 | * in6_clearscope will touch the addresses only when necessary. |
699 | */ |
700 | in6_clearscope(&ip6->ip6_src); |
701 | in6_clearscope(&ip6->ip6_dst); |
702 | |
703 | ifp = rt->rt_ifp; |
704 | /* Drop the lock but retain the extra ref */ |
705 | RT_UNLOCK(rt); |
706 | |
707 | /* |
708 | * If this is to be processed locally, let ip6_input have it. |
709 | */ |
710 | if (proxy) { |
711 | VERIFY(m->m_pkthdr.pkt_flags & PKTF_PROXY_DST); |
712 | /* Release extra ref */ |
713 | RT_REMREF(rt); |
714 | if (mcopy != NULL) { |
715 | m_freem(mcopy); |
716 | } |
717 | return m; |
718 | } |
719 | |
720 | /* Mark this packet as being forwarded from another interface */ |
721 | m->m_pkthdr.pkt_flags |= PKTF_FORWARDED; |
722 | |
723 | #if PF |
724 | if (PF_IS_ENABLED) { |
725 | /* |
726 | * PF refragments any packet which it reassembled due to scrub |
727 | * rules, in which case it will set the PF_TAG_REFRAGMENTED |
728 | * flag in PF mbuf tag. |
729 | */ |
730 | #if DUMMYNET |
731 | struct ip_fw_args args; |
732 | struct pf_mtag *pf_mtag; |
733 | |
734 | bzero(s: &args, n: sizeof(args)); |
735 | |
736 | args.fwa_oif = ifp; |
737 | args.fwa_oflags = 0; |
738 | args.fwa_ro6 = ip6forward_rt; |
739 | args.fwa_ro6_pmtu = ip6forward_rt; |
740 | args.fwa_mtu = rt->rt_ifp->if_mtu; |
741 | args.fwa_dst6 = dst; |
742 | args.fwa_origifp = origifp; |
743 | /* Invoke outbound packet filter */ |
744 | error = pf_af_hook(ifp, NULL, &m, AF_INET6, FALSE, &args); |
745 | #else /* !DUMMYNET */ |
746 | error = pf_af_hook(ifp, NULL, &m, AF_INET6, FALSE, NULL); |
747 | #endif /* !DUMMYNET */ |
748 | if (error != 0 || m == NULL) { |
749 | if (m != NULL) { |
750 | panic("%s: unexpected packet %p" , __func__, m); |
751 | /* NOTREACHED */ |
752 | } |
753 | /* Already freed by callee */ |
754 | goto senderr; |
755 | } |
756 | |
757 | pf_mtag = pf_find_mtag(m); |
758 | /* |
759 | * refragmented packets from PF. |
760 | */ |
761 | if ((pf_mtag->pftag_flags & PF_TAG_REFRAGMENTED) != 0) { |
762 | struct mbuf *t; |
763 | |
764 | pf_mtag->pftag_flags &= ~PF_TAG_REFRAGMENTED; |
765 | /* for statistics */ |
766 | t = m; |
767 | while (t != NULL) { |
768 | pktcnt++; |
769 | len += m_pktlen(t); |
770 | t = t->m_nextpkt; |
771 | } |
772 | |
773 | /* |
774 | * nd6_output() frees packetchain in both success and |
775 | * failure cases. |
776 | */ |
777 | error = nd6_output(ifp, origifp, m, dst, rt, NULL); |
778 | m = NULL; |
779 | goto sent; |
780 | } |
781 | /* |
782 | * We do not use ip6 header again in the code below, |
783 | * however still adding the bit here so that any new |
784 | * code in future doesn't end up working with the |
785 | * wrong pointer |
786 | */ |
787 | ip6 = mtod(m, struct ip6_hdr *); |
788 | } |
789 | #endif /* PF */ |
790 | |
791 | len = m_pktlen(m); |
792 | pktcnt = 1; |
793 | error = nd6_output(ifp, origifp, m, dst, rt, NULL); |
794 | sent: |
795 | if (error) { |
796 | in6_ifstat_add(ifp, ifs6_out_discard, pktcnt); |
797 | ip6stat.ip6s_cantforward += pktcnt; |
798 | } else { |
799 | /* |
800 | * Increment stats on the source interface; the ones |
801 | * for destination interface has been taken care of |
802 | * during output above by virtue of PKTF_FORWARDED. |
803 | */ |
804 | rcvifp->if_fpackets += pktcnt; |
805 | rcvifp->if_fbytes += len; |
806 | |
807 | ip6stat.ip6s_forward += pktcnt; |
808 | in6_ifstat_add(ifp, ifs6_out_forward, pktcnt); |
809 | if (type) { |
810 | ip6stat.ip6s_redirectsent++; |
811 | } else { |
812 | if (mcopy) { |
813 | goto freecopy; |
814 | } |
815 | } |
816 | } |
817 | #if PF |
818 | senderr: |
819 | #endif /* PF */ |
820 | if (mcopy == NULL) { |
821 | /* Release extra ref */ |
822 | RT_REMREF(rt); |
823 | return NULL; |
824 | } |
825 | switch (error) { |
826 | case 0: |
827 | #if 1 |
828 | if (type == ND_REDIRECT) { |
829 | icmp6_redirect_output(mcopy, rt); |
830 | /* Release extra ref */ |
831 | RT_REMREF(rt); |
832 | return NULL; |
833 | } |
834 | #endif |
835 | goto freecopy; |
836 | |
837 | case EMSGSIZE: |
838 | /* xxx MTU is constant in PPP? */ |
839 | goto freecopy; |
840 | |
841 | case ENOBUFS: |
842 | /* Tell source to slow down like source quench in IP? */ |
843 | goto freecopy; |
844 | |
845 | case ENETUNREACH: /* shouldn't happen, checked above */ |
846 | case EHOSTUNREACH: |
847 | case ENETDOWN: |
848 | case EHOSTDOWN: |
849 | default: |
850 | type = ICMP6_DST_UNREACH; |
851 | code = ICMP6_DST_UNREACH_ADDR; |
852 | break; |
853 | } |
854 | icmp6_error(mcopy, type, code, 0); |
855 | /* Release extra ref */ |
856 | RT_REMREF(rt); |
857 | return NULL; |
858 | |
859 | freecopy: |
860 | m_freem(mcopy); |
861 | /* Release extra ref */ |
862 | RT_REMREF(rt); |
863 | return NULL; |
864 | } |
865 | |