1 | /* $NetBSD: ip6_forward.c,v 1.81 2016/08/31 09:14:47 ozaki-r Exp $ */ |
2 | /* $KAME: ip6_forward.c,v 1.109 2002/09/11 08:10:17 sakane Exp $ */ |
3 | |
4 | /* |
5 | * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. |
6 | * All rights reserved. |
7 | * |
8 | * Redistribution and use in source and binary forms, with or without |
9 | * modification, are permitted provided that the following conditions |
10 | * are met: |
11 | * 1. Redistributions of source code must retain the above copyright |
12 | * notice, this list of conditions and the following disclaimer. |
13 | * 2. Redistributions in binary form must reproduce the above copyright |
14 | * notice, this list of conditions and the following disclaimer in the |
15 | * documentation and/or other materials provided with the distribution. |
16 | * 3. Neither the name of the project nor the names of its contributors |
17 | * may be used to endorse or promote products derived from this software |
18 | * without specific prior written permission. |
19 | * |
20 | * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND |
21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE |
24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
30 | * SUCH DAMAGE. |
31 | */ |
32 | |
33 | #include <sys/cdefs.h> |
34 | __KERNEL_RCSID(0, "$NetBSD: ip6_forward.c,v 1.81 2016/08/31 09:14:47 ozaki-r Exp $" ); |
35 | |
36 | #ifdef _KERNEL_OPT |
37 | #include "opt_gateway.h" |
38 | #include "opt_ipsec.h" |
39 | #endif |
40 | |
41 | #include <sys/param.h> |
42 | #include <sys/systm.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/percpu.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/ip_var.h> |
60 | #include <netinet/ip6.h> |
61 | #include <netinet6/ip6_var.h> |
62 | #include <netinet6/ip6_private.h> |
63 | #include <netinet6/scope6_var.h> |
64 | #include <netinet/icmp6.h> |
65 | #include <netinet6/nd6.h> |
66 | |
67 | #ifdef IPSEC |
68 | #include <netipsec/ipsec.h> |
69 | #include <netipsec/ipsec6.h> |
70 | #include <netipsec/key.h> |
71 | #include <netipsec/xform.h> |
72 | #endif /* IPSEC */ |
73 | |
74 | #include <net/net_osdep.h> |
75 | |
76 | extern percpu_t *ip6_forward_rt_percpu; |
77 | |
78 | extern pfil_head_t *inet6_pfil_hook; /* XXX */ |
79 | |
80 | static void __printflike(4, 5) |
81 | ip6_cantforward(const struct ip6_hdr *ip6, const struct ifnet *srcifp, |
82 | const struct ifnet *dstifp, const char *fmt, ...) |
83 | { |
84 | char sbuf[INET6_ADDRSTRLEN], dbuf[INET6_ADDRSTRLEN]; |
85 | char reason[256]; |
86 | va_list ap; |
87 | uint64_t *ip6s; |
88 | |
89 | /* update statistics */ |
90 | ip6s = IP6_STAT_GETREF(); |
91 | ip6s[IP6_STAT_CANTFORWARD]++; |
92 | if (dstifp) |
93 | ip6s[IP6_STAT_BADSCOPE]++; |
94 | IP6_STAT_PUTREF(); |
95 | |
96 | if (dstifp) |
97 | in6_ifstat_inc(dstifp, ifs6_in_discard); |
98 | |
99 | if (ip6_log_time + ip6_log_interval >= time_uptime) |
100 | return; |
101 | ip6_log_time = time_uptime; |
102 | |
103 | va_start(ap, fmt); |
104 | vsnprintf(reason, sizeof(reason), fmt, ap); |
105 | va_end(ap); |
106 | |
107 | log(LOG_DEBUG, "Cannot forward from %s@%s to %s@%s nxt %d (%s)\n" , |
108 | IN6_PRINT(sbuf, &ip6->ip6_src), srcifp ? if_name(srcifp) : "?" , |
109 | IN6_PRINT(dbuf, &ip6->ip6_dst), dstifp ? if_name(dstifp) : "?" , |
110 | ip6->ip6_nxt, reason); |
111 | } |
112 | |
113 | /* |
114 | * Forward a packet. If some error occurs return the sender |
115 | * an icmp packet. Note we can't always generate a meaningful |
116 | * icmp message because icmp doesn't have a large enough repertoire |
117 | * of codes and types. |
118 | * |
119 | * If not forwarding, just drop the packet. This could be confusing |
120 | * if ipforwarding was zero but some routing protocol was advancing |
121 | * us as a gateway to somewhere. However, we must let the routing |
122 | * protocol deal with that. |
123 | * |
124 | */ |
125 | |
126 | void |
127 | ip6_forward(struct mbuf *m, int srcrt) |
128 | { |
129 | struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); |
130 | const struct sockaddr_in6 *dst; |
131 | struct rtentry *rt; |
132 | int error = 0, type = 0, code = 0; |
133 | struct mbuf *mcopy = NULL; |
134 | struct ifnet *origifp; /* maybe unnecessary */ |
135 | uint32_t inzone, outzone; |
136 | struct in6_addr src_in6, dst_in6; |
137 | struct ifnet *rcvif = NULL; |
138 | struct psref psref; |
139 | struct route *ro; |
140 | #ifdef IPSEC |
141 | int needipsec = 0; |
142 | struct secpolicy *sp = NULL; |
143 | #endif |
144 | |
145 | /* |
146 | * Clear any in-bound checksum flags for this packet. |
147 | */ |
148 | m->m_pkthdr.csum_flags = 0; |
149 | |
150 | rcvif = m_get_rcvif_psref(m, &psref); |
151 | if (__predict_false(rcvif == NULL)) |
152 | goto drop; |
153 | |
154 | /* |
155 | * Do not forward packets to multicast destination (should be handled |
156 | * by ip6_mforward(). |
157 | * Do not forward packets with unspecified source. It was discussed |
158 | * in July 2000, on ipngwg mailing list. |
159 | */ |
160 | if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || |
161 | IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
162 | IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { |
163 | ip6_cantforward(ip6, rcvif, NULL, |
164 | ((m->m_flags & (M_BCAST|M_MCAST)) != 0) ? "bcast/mcast" : |
165 | IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ? "mcast/dst" : |
166 | "unspec/src" ); |
167 | goto drop; |
168 | } |
169 | |
170 | if (ip6->ip6_hlim <= IPV6_HLIMDEC) { |
171 | /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ |
172 | icmp6_error(m, ICMP6_TIME_EXCEEDED, |
173 | ICMP6_TIME_EXCEED_TRANSIT, 0); |
174 | goto out; |
175 | } |
176 | ip6->ip6_hlim -= IPV6_HLIMDEC; |
177 | |
178 | /* |
179 | * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - |
180 | * size of IPv6 + ICMPv6 headers) bytes of the packet in case |
181 | * we need to generate an ICMP6 message to the src. |
182 | * Thanks to M_EXT, in most cases copy will not occur. |
183 | * |
184 | * It is important to save it before IPsec processing as IPsec |
185 | * processing may modify the mbuf. |
186 | */ |
187 | mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); |
188 | |
189 | #ifdef IPSEC |
190 | if (ipsec_used) { |
191 | /* Check the security policy (SP) for the packet */ |
192 | |
193 | sp = ipsec6_check_policy(m, NULL, 0, &needipsec, &error); |
194 | if (error != 0) { |
195 | /* |
196 | * Hack: -EINVAL is used to signal that a packet |
197 | * should be silently discarded. This is typically |
198 | * because we asked key management for an SA and |
199 | * it was delayed (e.g. kicked up to IKE). |
200 | */ |
201 | if (error == -EINVAL) |
202 | error = 0; |
203 | goto freecopy; |
204 | } |
205 | } |
206 | #endif /* IPSEC */ |
207 | |
208 | ro = percpu_getref(ip6_forward_rt_percpu); |
209 | if (srcrt) { |
210 | union { |
211 | struct sockaddr dst; |
212 | struct sockaddr_in6 dst6; |
213 | } u; |
214 | |
215 | sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0); |
216 | if ((rt = rtcache_lookup(ro, &u.dst)) == NULL) { |
217 | IP6_STATINC(IP6_STAT_NOROUTE); |
218 | /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ |
219 | if (mcopy) { |
220 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
221 | ICMP6_DST_UNREACH_NOROUTE, 0); |
222 | } |
223 | percpu_putref(ip6_forward_rt_percpu); |
224 | goto drop; |
225 | } |
226 | } else if ((rt = rtcache_validate(ro)) == NULL && |
227 | (rt = rtcache_update(ro, 1)) == NULL) { |
228 | /* |
229 | * rtcache_getdst(ip6_forward_rt)->sin6_addr was equal to |
230 | * ip6->ip6_dst |
231 | */ |
232 | IP6_STATINC(IP6_STAT_NOROUTE); |
233 | /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ |
234 | if (mcopy) { |
235 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
236 | ICMP6_DST_UNREACH_NOROUTE, 0); |
237 | } |
238 | percpu_putref(ip6_forward_rt_percpu); |
239 | goto drop; |
240 | } |
241 | dst = satocsin6(rtcache_getdst(ro)); |
242 | percpu_putref(ip6_forward_rt_percpu); |
243 | |
244 | /* |
245 | * Source scope check: if a packet can't be delivered to its |
246 | * destination for the reason that the destination is beyond the scope |
247 | * of the source address, discard the packet and return an icmp6 |
248 | * destination unreachable error with Code 2 (beyond scope of source |
249 | * address). We use a local copy of ip6_src, since in6_setscope() |
250 | * will possibly modify its first argument. |
251 | * [draft-ietf-ipngwg-icmp-v3-07, Section 3.1] |
252 | */ |
253 | src_in6 = ip6->ip6_src; |
254 | inzone = outzone = ~0; |
255 | if (in6_setscope(&src_in6, rt->rt_ifp, &outzone) != 0 || |
256 | in6_setscope(&src_in6, rcvif, &inzone) != 0 || |
257 | inzone != outzone) { |
258 | ip6_cantforward(ip6, rcvif, rt->rt_ifp, |
259 | "src[%s] inzone %d outzone %d" , |
260 | in6_getscopename(&ip6->ip6_src), inzone, outzone); |
261 | if (mcopy) |
262 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
263 | ICMP6_DST_UNREACH_BEYONDSCOPE, 0); |
264 | goto drop; |
265 | } |
266 | |
267 | #ifdef IPSEC |
268 | /* |
269 | * If we need to encapsulate the packet, do it here |
270 | * ipsec6_proces_packet will send the packet using ip6_output |
271 | */ |
272 | if (needipsec) { |
273 | int s = splsoftnet(); |
274 | error = ipsec6_process_packet(m, sp->req); |
275 | splx(s); |
276 | if (mcopy) |
277 | goto freecopy; |
278 | } |
279 | #endif |
280 | |
281 | /* |
282 | * Destination scope check: if a packet is going to break the scope |
283 | * zone of packet's destination address, discard it. This case should |
284 | * usually be prevented by appropriately-configured routing table, but |
285 | * we need an explicit check because we may mistakenly forward the |
286 | * packet to a different zone by (e.g.) a default route. |
287 | */ |
288 | dst_in6 = ip6->ip6_dst; |
289 | inzone = outzone = ~0; |
290 | if (in6_setscope(&dst_in6, rcvif, &inzone) != 0 || |
291 | in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 || |
292 | inzone != outzone) { |
293 | ip6_cantforward(ip6, rcvif, rt->rt_ifp, |
294 | "dst[%s] inzone %d outzone %d" , |
295 | in6_getscopename(&ip6->ip6_dst), inzone, outzone); |
296 | if (mcopy) |
297 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
298 | ICMP6_DST_UNREACH_BEYONDSCOPE, 0); |
299 | goto drop; |
300 | } |
301 | |
302 | if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) { |
303 | in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); |
304 | if (mcopy) { |
305 | u_long mtu; |
306 | |
307 | mtu = IN6_LINKMTU(rt->rt_ifp); |
308 | icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); |
309 | } |
310 | goto drop; |
311 | } |
312 | |
313 | if (rt->rt_flags & RTF_GATEWAY) |
314 | dst = (struct sockaddr_in6 *)rt->rt_gateway; |
315 | |
316 | /* |
317 | * If we are to forward the packet using the same interface |
318 | * as one we got the packet from, perhaps we should send a redirect |
319 | * to sender to shortcut a hop. |
320 | * Only send redirect if source is sending directly to us, |
321 | * and if packet was not source routed (or has any options). |
322 | * Also, don't send redirect if forwarding using a route |
323 | * modified by a redirect. |
324 | */ |
325 | if (rt->rt_ifp == rcvif && !srcrt && ip6_sendredirects && |
326 | (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { |
327 | ro = percpu_getref(ip6_forward_rt_percpu); |
328 | if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) && |
329 | nd6_is_addr_neighbor(satocsin6(rtcache_getdst(ro)), |
330 | rt->rt_ifp)) { |
331 | percpu_putref(ip6_forward_rt_percpu); |
332 | /* |
333 | * If the incoming interface is equal to the outgoing |
334 | * one, the link attached to the interface is |
335 | * point-to-point, and the IPv6 destination is |
336 | * regarded as on-link on the link, then it will be |
337 | * highly probable that the destination address does |
338 | * not exist on the link and that the packet is going |
339 | * to loop. Thus, we immediately drop the packet and |
340 | * send an ICMPv6 error message. |
341 | * For other routing loops, we dare to let the packet |
342 | * go to the loop, so that a remote diagnosing host |
343 | * can detect the loop by traceroute. |
344 | * type/code is based on suggestion by Rich Draves. |
345 | * not sure if it is the best pick. |
346 | */ |
347 | icmp6_error(mcopy, ICMP6_DST_UNREACH, |
348 | ICMP6_DST_UNREACH_ADDR, 0); |
349 | goto drop; |
350 | } |
351 | percpu_putref(ip6_forward_rt_percpu); |
352 | type = ND_REDIRECT; |
353 | } |
354 | |
355 | /* |
356 | * Fake scoped addresses. Note that even link-local source or |
357 | * destinaion can appear, if the originating node just sends the |
358 | * packet to us (without address resolution for the destination). |
359 | * Since both icmp6_error and icmp6_redirect_output fill the embedded |
360 | * link identifiers, we can do this stuff after making a copy for |
361 | * returning an error. |
362 | */ |
363 | if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { |
364 | /* |
365 | * See corresponding comments in ip6_output. |
366 | * XXX: but is it possible that ip6_forward() sends a packet |
367 | * to a loopback interface? I don't think so, and thus |
368 | * I bark here. (jinmei@kame.net) |
369 | * XXX: it is common to route invalid packets to loopback. |
370 | * also, the codepath will be visited on use of ::1 in |
371 | * rthdr. (itojun) |
372 | */ |
373 | #if 1 |
374 | if (0) |
375 | #else |
376 | if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) |
377 | #endif |
378 | { |
379 | printf("ip6_forward: outgoing interface is loopback. " |
380 | "src %s, dst %s, nxt %d, rcvif %s, outif %s\n" , |
381 | ip6_sprintf(&ip6->ip6_src), |
382 | ip6_sprintf(&ip6->ip6_dst), |
383 | ip6->ip6_nxt, if_name(rcvif), |
384 | if_name(rt->rt_ifp)); |
385 | } |
386 | |
387 | /* we can just use rcvif in forwarding. */ |
388 | origifp = rcvif; |
389 | } |
390 | else |
391 | origifp = rt->rt_ifp; |
392 | /* |
393 | * clear embedded scope identifiers if necessary. |
394 | * in6_clearscope will touch the addresses only when necessary. |
395 | */ |
396 | in6_clearscope(&ip6->ip6_src); |
397 | in6_clearscope(&ip6->ip6_dst); |
398 | |
399 | /* |
400 | * Run through list of hooks for output packets. |
401 | */ |
402 | if ((error = pfil_run_hooks(inet6_pfil_hook, &m, rt->rt_ifp, |
403 | PFIL_OUT)) != 0) |
404 | goto senderr; |
405 | if (m == NULL) |
406 | goto freecopy; |
407 | ip6 = mtod(m, struct ip6_hdr *); |
408 | |
409 | error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); |
410 | if (error) { |
411 | in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); |
412 | IP6_STATINC(IP6_STAT_CANTFORWARD); |
413 | } else { |
414 | IP6_STATINC(IP6_STAT_FORWARD); |
415 | in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); |
416 | if (type) |
417 | IP6_STATINC(IP6_STAT_REDIRECTSENT); |
418 | else { |
419 | #ifdef GATEWAY |
420 | ro = percpu_getref(ip6_forward_rt_percpu); |
421 | if (m->m_flags & M_CANFASTFWD) |
422 | ip6flow_create(ro, m); |
423 | percpu_putref(ip6_forward_rt_percpu); |
424 | #endif |
425 | if (mcopy) |
426 | goto freecopy; |
427 | } |
428 | } |
429 | |
430 | senderr: |
431 | if (mcopy == NULL) |
432 | goto out; |
433 | switch (error) { |
434 | case 0: |
435 | if (type == ND_REDIRECT) { |
436 | icmp6_redirect_output(mcopy, rt); |
437 | goto out; |
438 | } |
439 | goto freecopy; |
440 | |
441 | case EMSGSIZE: |
442 | /* xxx MTU is constant in PPP? */ |
443 | goto freecopy; |
444 | |
445 | case ENOBUFS: |
446 | /* Tell source to slow down like source quench in IP? */ |
447 | goto freecopy; |
448 | |
449 | case ENETUNREACH: /* shouldn't happen, checked above */ |
450 | case EHOSTUNREACH: |
451 | case ENETDOWN: |
452 | case EHOSTDOWN: |
453 | default: |
454 | type = ICMP6_DST_UNREACH; |
455 | code = ICMP6_DST_UNREACH_ADDR; |
456 | break; |
457 | } |
458 | icmp6_error(mcopy, type, code, 0); |
459 | goto out; |
460 | |
461 | freecopy: |
462 | m_freem(mcopy); |
463 | goto out; |
464 | drop: |
465 | m_freem(m); |
466 | out: |
467 | if (rcvif != NULL) |
468 | m_put_rcvif_psref(rcvif, &psref); |
469 | return; |
470 | } |
471 | |