1 /* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7 * Copyright (c) 2018 Andrey V. Elsukov <ae@FreeBSD.org>
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the project nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34 /*
35 * My grandfather said that there's a devil inside tunnelling technology...
36 *
37 * We have surprisingly many protocols that want packets with IP protocol
38 * #4 or #41. Here's a list of protocols that want protocol #41:
39 * RFC1933 configured tunnel
40 * RFC1933 automatic tunnel
41 * RFC2401 IPsec tunnel
42 * RFC2473 IPv6 generic packet tunnelling
43 * RFC2529 6over4 tunnel
44 * mobile-ip6 (uses RFC2473)
45 * RFC3056 6to4 tunnel
46 * isatap tunnel
47 * Here's a list of protocol that want protocol #4:
48 * RFC1853 IPv4-in-IPv4 tunnelling
49 * RFC2003 IPv4 encapsulation within IPv4
50 * RFC2344 reverse tunnelling for mobile-ip4
51 * RFC2401 IPsec tunnel
52 * Well, what can I say. They impose different en/decapsulation mechanism
53 * from each other, so they need separate protocol handler. The only one
54 * we can easily determine by protocol # is IPsec, which always has
55 * AH/ESP/IPComp header right after outer IP header.
56 *
57 * So, clearly good old protosw does not work for protocol #4 and #41.
58 * The code will let you match protocol via src/dst address pair.
59 */
60
61 #include <sys/cdefs.h>
62 __FBSDID("$FreeBSD$");
63
64 #include "opt_inet.h"
65 #include "opt_inet6.h"
66
67 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <sys/eventhandler.h>
70 #include <sys/kernel.h>
71 #include <sys/lock.h>
72 #include <sys/malloc.h>
73 #include <sys/mutex.h>
74 #include <sys/mbuf.h>
75 #include <sys/errno.h>
76 #include <sys/socket.h>
77
78 #include <net/if.h>
79 #include <net/if_var.h>
80
81 #include <netinet/in.h>
82 #include <netinet/ip_var.h>
83 #include <netinet/ip_encap.h>
84
85 #ifdef INET6
86 #include <netinet6/ip6_var.h>
87 #endif
88
89 static MALLOC_DEFINE(M_NETADDR, "encap_export_host",
90 "Export host address structure");
91
92 struct encaptab {
93 CK_LIST_ENTRY(encaptab) chain;
94 int proto;
95 int min_length;
96 int exact_match;
97 void *arg;
98
99 encap_lookup_t lookup;
100 encap_check_t check;
101 encap_input_t input;
102 };
103
104 struct srcaddrtab {
105 CK_LIST_ENTRY(srcaddrtab) chain;
106
107 encap_srcaddr_t srcaddr;
108 void *arg;
109 };
110
111 CK_LIST_HEAD(encaptab_head, encaptab);
112 CK_LIST_HEAD(srcaddrtab_head, srcaddrtab);
113 #ifdef INET
114 static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER();
115 static struct srcaddrtab_head ipv4_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
116 #endif
117 #ifdef INET6
118 static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER();
119 static struct srcaddrtab_head ipv6_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
120 #endif
121
122 static struct mtx encapmtx, srcaddrmtx;
123 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
124 MTX_SYSINIT(srcaddrmtx, &srcaddrmtx, "srcaddrmtx", MTX_DEF);
125 #define ENCAP_WLOCK() mtx_lock(&encapmtx)
126 #define ENCAP_WUNLOCK() mtx_unlock(&encapmtx)
127 #define ENCAP_RLOCK_TRACKER struct epoch_tracker encap_et
128 #define ENCAP_RLOCK() \
129 epoch_enter_preempt(net_epoch_preempt, &encap_et)
130 #define ENCAP_RUNLOCK() \
131 epoch_exit_preempt(net_epoch_preempt, &encap_et)
132 #define ENCAP_WAIT() epoch_wait_preempt(net_epoch_preempt)
133
134 #define SRCADDR_WLOCK() mtx_lock(&srcaddrmtx)
135 #define SRCADDR_WUNLOCK() mtx_unlock(&srcaddrmtx)
136 #define SRCADDR_RLOCK_TRACKER struct epoch_tracker srcaddr_et
137 #define SRCADDR_RLOCK() \
138 epoch_enter_preempt(net_epoch_preempt, &srcaddr_et)
139 #define SRCADDR_RUNLOCK() \
140 epoch_exit_preempt(net_epoch_preempt, &srcaddr_et)
141 #define SRCADDR_WAIT() epoch_wait_preempt(net_epoch_preempt)
142
143 /*
144 * ifaddr_event_ext handler.
145 *
146 * Tunnelling interfaces may request the kernel to notify when
147 * some interface addresses appears or disappears. Usually tunnelling
148 * interface must use an address configured on the local machine as
149 * ingress address to be able receive datagramms and do not send
150 * spoofed packets.
151 */
152 static void
153 srcaddr_change_event(void *arg __unused, struct ifnet *ifp,
154 struct ifaddr *ifa, int event)
155 {
156 SRCADDR_RLOCK_TRACKER;
157 struct srcaddrtab_head *head;
158 struct srcaddrtab *p;
159
160 /* Support for old ifaddr_event. */
161 EVENTHANDLER_INVOKE(ifaddr_event, ifp);
162
163 switch (ifa->ifa_addr->sa_family) {
164 #ifdef INET
165 case AF_INET:
166 head = &ipv4_srcaddrtab;
167 break;
168 #endif
169 #ifdef INET6
170 case AF_INET6:
171 head = &ipv6_srcaddrtab;
172 break;
173 #endif
174 default:
175 /* ignore event */
176 return;
177 }
178
179 SRCADDR_RLOCK();
180 CK_LIST_FOREACH(p, head, chain) {
181 (*p->srcaddr)(p->arg, ifa->ifa_addr, event);
182 }
183 SRCADDR_RUNLOCK();
184 }
185 EVENTHANDLER_DEFINE(ifaddr_event_ext, srcaddr_change_event, NULL, 0);
186
187 static struct srcaddrtab *
188 encap_register_srcaddr(struct srcaddrtab_head *head, encap_srcaddr_t func,
189 void *arg, int mflags)
190 {
191 struct srcaddrtab *p, *tmp;
192
193 if (func == NULL)
194 return (NULL);
195 p = malloc(sizeof(*p), M_NETADDR, mflags);
196 if (p == NULL)
197 return (NULL);
198 p->srcaddr = func;
199 p->arg = arg;
200
201 SRCADDR_WLOCK();
202 CK_LIST_FOREACH(tmp, head, chain) {
203 if (func == tmp->srcaddr && arg == tmp->arg)
204 break;
205 }
206 if (tmp == NULL)
207 CK_LIST_INSERT_HEAD(head, p, chain);
208 SRCADDR_WUNLOCK();
209
210 if (tmp != NULL) {
211 free(p, M_NETADDR);
212 p = tmp;
213 }
214 return (p);
215 }
216
217 static int
218 encap_unregister_srcaddr(struct srcaddrtab_head *head,
219 const struct srcaddrtab *cookie)
220 {
221 struct srcaddrtab *p;
222
223 SRCADDR_WLOCK();
224 CK_LIST_FOREACH(p, head, chain) {
225 if (p == cookie) {
226 CK_LIST_REMOVE(p, chain);
227 SRCADDR_WUNLOCK();
228 SRCADDR_WAIT();
229 free(p, M_NETADDR);
230 return (0);
231 }
232 }
233 SRCADDR_WUNLOCK();
234 return (EINVAL);
235 }
236
237 static struct encaptab *
238 encap_attach(struct encaptab_head *head, const struct encap_config *cfg,
239 void *arg, int mflags)
240 {
241 struct encaptab *ep, *tmp;
242
243 if (cfg == NULL || cfg->input == NULL ||
244 (cfg->check == NULL && cfg->lookup == NULL) ||
245 (cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) ||
246 (cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL))
247 return (NULL);
248
249 ep = malloc(sizeof(*ep), M_NETADDR, mflags);
250 if (ep == NULL)
251 return (NULL);
252
253 ep->proto = cfg->proto;
254 ep->min_length = cfg->min_length;
255 ep->exact_match = cfg->exact_match;
256 ep->arg = arg;
257 ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL;
258 ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL;
259 ep->input = cfg->input;
260
261 ENCAP_WLOCK();
262 CK_LIST_FOREACH(tmp, head, chain) {
263 if (tmp->exact_match <= ep->exact_match)
264 break;
265 }
266 if (tmp == NULL)
267 CK_LIST_INSERT_HEAD(head, ep, chain);
268 else
269 CK_LIST_INSERT_BEFORE(tmp, ep, chain);
270 ENCAP_WUNLOCK();
271 return (ep);
272 }
273
274 static int
275 encap_detach(struct encaptab_head *head, const struct encaptab *cookie)
276 {
277 struct encaptab *ep;
278
279 ENCAP_WLOCK();
280 CK_LIST_FOREACH(ep, head, chain) {
281 if (ep == cookie) {
282 CK_LIST_REMOVE(ep, chain);
283 ENCAP_WUNLOCK();
284 ENCAP_WAIT();
285 free(ep, M_NETADDR);
286 return (0);
287 }
288 }
289 ENCAP_WUNLOCK();
290 return (EINVAL);
291 }
292
293 static int
294 encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto)
295 {
296 ENCAP_RLOCK_TRACKER;
297 struct encaptab *ep, *match;
298 void *arg;
299 int matchprio, ret;
300
301 match = NULL;
302 matchprio = 0;
303
304 ENCAP_RLOCK();
305 CK_LIST_FOREACH(ep, head, chain) {
306 if (ep->proto >= 0 && ep->proto != proto)
307 continue;
308 if (ep->min_length > m->m_pkthdr.len)
309 continue;
310 if (ep->exact_match == ENCAP_DRV_LOOKUP)
311 ret = (*ep->lookup)(m, off, proto, &arg);
312 else
313 ret = (*ep->check)(m, off, proto, ep->arg);
314 if (ret <= 0)
315 continue;
316 if (ret > matchprio) {
317 match = ep;
318 if (ep->exact_match != ENCAP_DRV_LOOKUP)
319 arg = ep->arg;
320 /*
321 * No need to continue the search, we got the
322 * exact match.
323 */
324 if (ret >= ep->exact_match)
325 break;
326 matchprio = ret;
327 }
328 }
329
330 if (match != NULL) {
331 /* found a match, "match" has the best one */
332 ret = (*match->input)(m, off, proto, arg);
333 ENCAP_RUNLOCK();
334 MPASS(ret == IPPROTO_DONE);
335 return (IPPROTO_DONE);
336 }
337 ENCAP_RUNLOCK();
338 return (0);
339 }
340
341 #ifdef INET
342 const struct srcaddrtab *
343 ip_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
344 {
345
346 return (encap_register_srcaddr(&ipv4_srcaddrtab, func, arg, mflags));
347 }
348
349 int
350 ip_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
351 {
352
353 return (encap_unregister_srcaddr(&ipv4_srcaddrtab, cookie));
354 }
355
356 const struct encaptab *
357 ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
358 {
359
360 return (encap_attach(&ipv4_encaptab, cfg, arg, mflags));
361 }
362
363 int
364 ip_encap_detach(const struct encaptab *cookie)
365 {
366
367 return (encap_detach(&ipv4_encaptab, cookie));
368 }
369
370 int
371 encap4_input(struct mbuf **mp, int *offp, int proto)
372 {
373
374 if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
375 return (rip_input(mp, offp, proto));
376 return (IPPROTO_DONE);
377 }
378 #endif /* INET */
379
380 #ifdef INET6
381 const struct srcaddrtab *
382 ip6_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
383 {
384
385 return (encap_register_srcaddr(&ipv6_srcaddrtab, func, arg, mflags));
386 }
387
388 int
389 ip6_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
390 {
391
392 return (encap_unregister_srcaddr(&ipv6_srcaddrtab, cookie));
393 }
394
395 const struct encaptab *
396 ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
397 {
398
399 return (encap_attach(&ipv6_encaptab, cfg, arg, mflags));
400 }
401
402 int
403 ip6_encap_detach(const struct encaptab *cookie)
404 {
405
406 return (encap_detach(&ipv6_encaptab, cookie));
407 }
408
409 int
410 encap6_input(struct mbuf **mp, int *offp, int proto)
411 {
412
413 if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
414 return (rip6_input(mp, offp, proto));
415 return (IPPROTO_DONE);
416 }
417 #endif /* INET6 */
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