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 #include "opt_inet.h"
63 #include "opt_inet6.h"
64
65 #include <sys/param.h>
66 #include <sys/systm.h>
67 #include <sys/eventhandler.h>
68 #include <sys/kernel.h>
69 #include <sys/lock.h>
70 #include <sys/malloc.h>
71 #include <sys/mutex.h>
72 #include <sys/mbuf.h>
73 #include <sys/errno.h>
74 #include <sys/socket.h>
75
76 #include <net/if.h>
77 #include <net/if_var.h>
78
79 #include <netinet/in.h>
80 #include <netinet/ip_var.h>
81 #include <netinet/ip_encap.h>
82
83 #ifdef INET6
84 #include <netinet6/ip6_var.h>
85 #endif
86
87 static MALLOC_DEFINE(M_NETADDR, "encap_export_host",
88 "Export host address structure");
89
90 struct encaptab {
91 CK_LIST_ENTRY(encaptab) chain;
92 int proto;
93 int min_length;
94 int exact_match;
95 void *arg;
96
97 encap_lookup_t lookup;
98 encap_check_t check;
99 encap_input_t input;
100 };
101
102 struct srcaddrtab {
103 CK_LIST_ENTRY(srcaddrtab) chain;
104
105 encap_srcaddr_t srcaddr;
106 void *arg;
107 };
108
109 CK_LIST_HEAD(encaptab_head, encaptab);
110 CK_LIST_HEAD(srcaddrtab_head, srcaddrtab);
111 #ifdef INET
112 static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER();
113 static struct srcaddrtab_head ipv4_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
114 #endif
115 #ifdef INET6
116 static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER();
117 static struct srcaddrtab_head ipv6_srcaddrtab = CK_LIST_HEAD_INITIALIZER();
118 #endif
119
120 static struct mtx encapmtx, srcaddrmtx;
121 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
122 MTX_SYSINIT(srcaddrmtx, &srcaddrmtx, "srcaddrmtx", MTX_DEF);
123 #define ENCAP_WLOCK() mtx_lock(&encapmtx)
124 #define ENCAP_WUNLOCK() mtx_unlock(&encapmtx)
125 #define ENCAP_RLOCK_TRACKER struct epoch_tracker encap_et
126 #define ENCAP_RLOCK() NET_EPOCH_ENTER(encap_et)
127 #define ENCAP_RUNLOCK() NET_EPOCH_EXIT(encap_et)
128 #define ENCAP_WAIT() NET_EPOCH_WAIT()
129
130 #define SRCADDR_WLOCK() mtx_lock(&srcaddrmtx)
131 #define SRCADDR_WUNLOCK() mtx_unlock(&srcaddrmtx)
132 #define SRCADDR_RLOCK_TRACKER struct epoch_tracker srcaddr_et
133 #define SRCADDR_RLOCK() \
134 epoch_enter_preempt(net_epoch_preempt, &srcaddr_et)
135 #define SRCADDR_RUNLOCK() \
136 epoch_exit_preempt(net_epoch_preempt, &srcaddr_et)
137 #define SRCADDR_WAIT() epoch_wait_preempt(net_epoch_preempt)
138
139 /*
140 * ifaddr_event_ext handler.
141 *
142 * Tunnelling interfaces may request the kernel to notify when
143 * some interface addresses appears or disappears. Usually tunnelling
144 * interface must use an address configured on the local machine as
145 * ingress address to be able receive datagramms and do not send
146 * spoofed packets.
147 */
148 static void
srcaddr_change_event(void * arg __unused,struct ifnet * ifp,struct ifaddr * ifa,int event)149 srcaddr_change_event(void *arg __unused, struct ifnet *ifp,
150 struct ifaddr *ifa, int event)
151 {
152 SRCADDR_RLOCK_TRACKER;
153 struct srcaddrtab_head *head;
154 struct srcaddrtab *p;
155
156 /* Support for old ifaddr_event. */
157 EVENTHANDLER_INVOKE(ifaddr_event, ifp);
158
159 switch (ifa->ifa_addr->sa_family) {
160 #ifdef INET
161 case AF_INET:
162 head = &ipv4_srcaddrtab;
163 break;
164 #endif
165 #ifdef INET6
166 case AF_INET6:
167 head = &ipv6_srcaddrtab;
168 break;
169 #endif
170 default:
171 /* ignore event */
172 return;
173 }
174
175 SRCADDR_RLOCK();
176 CK_LIST_FOREACH(p, head, chain) {
177 (*p->srcaddr)(p->arg, ifa->ifa_addr, event);
178 }
179 SRCADDR_RUNLOCK();
180 }
181 EVENTHANDLER_DEFINE(ifaddr_event_ext, srcaddr_change_event, NULL, 0);
182
183 static struct srcaddrtab *
encap_register_srcaddr(struct srcaddrtab_head * head,encap_srcaddr_t func,void * arg,int mflags)184 encap_register_srcaddr(struct srcaddrtab_head *head, encap_srcaddr_t func,
185 void *arg, int mflags)
186 {
187 struct srcaddrtab *p, *tmp;
188
189 if (func == NULL)
190 return (NULL);
191 p = malloc(sizeof(*p), M_NETADDR, mflags);
192 if (p == NULL)
193 return (NULL);
194 p->srcaddr = func;
195 p->arg = arg;
196
197 SRCADDR_WLOCK();
198 CK_LIST_FOREACH(tmp, head, chain) {
199 if (func == tmp->srcaddr && arg == tmp->arg)
200 break;
201 }
202 if (tmp == NULL)
203 CK_LIST_INSERT_HEAD(head, p, chain);
204 SRCADDR_WUNLOCK();
205
206 if (tmp != NULL) {
207 free(p, M_NETADDR);
208 p = tmp;
209 }
210 return (p);
211 }
212
213 static int
encap_unregister_srcaddr(struct srcaddrtab_head * head,const struct srcaddrtab * cookie)214 encap_unregister_srcaddr(struct srcaddrtab_head *head,
215 const struct srcaddrtab *cookie)
216 {
217 struct srcaddrtab *p;
218
219 SRCADDR_WLOCK();
220 CK_LIST_FOREACH(p, head, chain) {
221 if (p == cookie) {
222 CK_LIST_REMOVE(p, chain);
223 SRCADDR_WUNLOCK();
224 SRCADDR_WAIT();
225 free(p, M_NETADDR);
226 return (0);
227 }
228 }
229 SRCADDR_WUNLOCK();
230 return (EINVAL);
231 }
232
233 static struct encaptab *
encap_attach(struct encaptab_head * head,const struct encap_config * cfg,void * arg,int mflags)234 encap_attach(struct encaptab_head *head, const struct encap_config *cfg,
235 void *arg, int mflags)
236 {
237 struct encaptab *ep, *tmp;
238
239 if (cfg == NULL || cfg->input == NULL ||
240 (cfg->check == NULL && cfg->lookup == NULL) ||
241 (cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) ||
242 (cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL))
243 return (NULL);
244
245 ep = malloc(sizeof(*ep), M_NETADDR, mflags);
246 if (ep == NULL)
247 return (NULL);
248
249 ep->proto = cfg->proto;
250 ep->min_length = cfg->min_length;
251 ep->exact_match = cfg->exact_match;
252 ep->arg = arg;
253 ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL;
254 ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL;
255 ep->input = cfg->input;
256
257 ENCAP_WLOCK();
258 CK_LIST_FOREACH(tmp, head, chain) {
259 if (tmp->exact_match <= ep->exact_match)
260 break;
261 }
262 if (tmp == NULL)
263 CK_LIST_INSERT_HEAD(head, ep, chain);
264 else
265 CK_LIST_INSERT_BEFORE(tmp, ep, chain);
266 ENCAP_WUNLOCK();
267 return (ep);
268 }
269
270 static int
encap_detach(struct encaptab_head * head,const struct encaptab * cookie)271 encap_detach(struct encaptab_head *head, const struct encaptab *cookie)
272 {
273 struct encaptab *ep;
274
275 ENCAP_WLOCK();
276 CK_LIST_FOREACH(ep, head, chain) {
277 if (ep == cookie) {
278 CK_LIST_REMOVE(ep, chain);
279 ENCAP_WUNLOCK();
280 ENCAP_WAIT();
281 free(ep, M_NETADDR);
282 return (0);
283 }
284 }
285 ENCAP_WUNLOCK();
286 return (EINVAL);
287 }
288
289 static int
encap_input(struct encaptab_head * head,struct mbuf * m,int off,int proto)290 encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto)
291 {
292 ENCAP_RLOCK_TRACKER;
293 struct encaptab *ep, *match;
294 void *arg;
295 int matchprio, ret;
296
297 match = NULL;
298 matchprio = 0;
299
300 ENCAP_RLOCK();
301 CK_LIST_FOREACH(ep, head, chain) {
302 if (ep->proto >= 0 && ep->proto != proto)
303 continue;
304 if (ep->min_length > m->m_pkthdr.len)
305 continue;
306 if (ep->exact_match == ENCAP_DRV_LOOKUP)
307 ret = (*ep->lookup)(m, off, proto, &arg);
308 else
309 ret = (*ep->check)(m, off, proto, ep->arg);
310 if (ret <= 0)
311 continue;
312 if (ret > matchprio) {
313 match = ep;
314 if (ep->exact_match != ENCAP_DRV_LOOKUP)
315 arg = ep->arg;
316 /*
317 * No need to continue the search, we got the
318 * exact match.
319 */
320 if (ret >= ep->exact_match)
321 break;
322 matchprio = ret;
323 }
324 }
325
326 if (match != NULL) {
327 /* found a match, "match" has the best one */
328 ret = (*match->input)(m, off, proto, arg);
329 ENCAP_RUNLOCK();
330 MPASS(ret == IPPROTO_DONE);
331 return (IPPROTO_DONE);
332 }
333 ENCAP_RUNLOCK();
334 return (0);
335 }
336
337 #ifdef INET
338 const struct srcaddrtab *
ip_encap_register_srcaddr(encap_srcaddr_t func,void * arg,int mflags)339 ip_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
340 {
341
342 return (encap_register_srcaddr(&ipv4_srcaddrtab, func, arg, mflags));
343 }
344
345 int
ip_encap_unregister_srcaddr(const struct srcaddrtab * cookie)346 ip_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
347 {
348
349 return (encap_unregister_srcaddr(&ipv4_srcaddrtab, cookie));
350 }
351
352 const struct encaptab *
ip_encap_attach(const struct encap_config * cfg,void * arg,int mflags)353 ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
354 {
355
356 return (encap_attach(&ipv4_encaptab, cfg, arg, mflags));
357 }
358
359 int
ip_encap_detach(const struct encaptab * cookie)360 ip_encap_detach(const struct encaptab *cookie)
361 {
362
363 return (encap_detach(&ipv4_encaptab, cookie));
364 }
365
366 int
encap4_input(struct mbuf ** mp,int * offp,int proto)367 encap4_input(struct mbuf **mp, int *offp, int proto)
368 {
369
370 if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
371 return (rip_input(mp, offp, proto));
372 return (IPPROTO_DONE);
373 }
374 #endif /* INET */
375
376 #ifdef INET6
377 const struct srcaddrtab *
ip6_encap_register_srcaddr(encap_srcaddr_t func,void * arg,int mflags)378 ip6_encap_register_srcaddr(encap_srcaddr_t func, void *arg, int mflags)
379 {
380
381 return (encap_register_srcaddr(&ipv6_srcaddrtab, func, arg, mflags));
382 }
383
384 int
ip6_encap_unregister_srcaddr(const struct srcaddrtab * cookie)385 ip6_encap_unregister_srcaddr(const struct srcaddrtab *cookie)
386 {
387
388 return (encap_unregister_srcaddr(&ipv6_srcaddrtab, cookie));
389 }
390
391 const struct encaptab *
ip6_encap_attach(const struct encap_config * cfg,void * arg,int mflags)392 ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
393 {
394
395 return (encap_attach(&ipv6_encaptab, cfg, arg, mflags));
396 }
397
398 int
ip6_encap_detach(const struct encaptab * cookie)399 ip6_encap_detach(const struct encaptab *cookie)
400 {
401
402 return (encap_detach(&ipv6_encaptab, cookie));
403 }
404
405 int
encap6_input(struct mbuf ** mp,int * offp,int proto)406 encap6_input(struct mbuf **mp, int *offp, int proto)
407 {
408
409 if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
410 return (rip6_input(mp, offp, proto));
411 return (IPPROTO_DONE);
412 }
413 #endif /* INET6 */
414