1 /* $FreeBSD: releng/6.0/sys/netinet/ip_encap.c 139823 2005-01-07 01:45:51Z imp $ */
2 /* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun 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 * My grandfather said that there's a devil inside tunnelling technology...
34 *
35 * We have surprisingly many protocols that want packets with IP protocol
36 * #4 or #41. Here's a list of protocols that want protocol #41:
37 * RFC1933 configured tunnel
38 * RFC1933 automatic tunnel
39 * RFC2401 IPsec tunnel
40 * RFC2473 IPv6 generic packet tunnelling
41 * RFC2529 6over4 tunnel
42 * mobile-ip6 (uses RFC2473)
43 * RFC3056 6to4 tunnel
44 * isatap tunnel
45 * Here's a list of protocol that want protocol #4:
46 * RFC1853 IPv4-in-IPv4 tunnelling
47 * RFC2003 IPv4 encapsulation within IPv4
48 * RFC2344 reverse tunnelling for mobile-ip4
49 * RFC2401 IPsec tunnel
50 * Well, what can I say. They impose different en/decapsulation mechanism
51 * from each other, so they need separate protocol handler. The only one
52 * we can easily determine by protocol # is IPsec, which always has
53 * AH/ESP/IPComp header right after outer IP header.
54 *
55 * So, clearly good old protosw does not work for protocol #4 and #41.
56 * The code will let you match protocol via src/dst address pair.
57 */
58 /* XXX is M_NETADDR correct? */
59
60 #include "opt_mrouting.h"
61 #include "opt_inet.h"
62 #include "opt_inet6.h"
63
64 #include <sys/param.h>
65 #include <sys/systm.h>
66 #include <sys/socket.h>
67 #include <sys/sockio.h>
68 #include <sys/mbuf.h>
69 #include <sys/errno.h>
70 #include <sys/protosw.h>
71 #include <sys/queue.h>
72
73 #include <net/if.h>
74 #include <net/route.h>
75
76 #include <netinet/in.h>
77 #include <netinet/in_systm.h>
78 #include <netinet/ip.h>
79 #include <netinet/ip_var.h>
80 #include <netinet/ip_encap.h>
81
82 #ifdef INET6
83 #include <netinet/ip6.h>
84 #include <netinet6/ip6_var.h>
85 #include <netinet6/ip6protosw.h>
86 #endif
87
88 #include <machine/stdarg.h>
89
90 #include <net/net_osdep.h>
91
92 #include <sys/kernel.h>
93 #include <sys/malloc.h>
94 static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
95
96 static void encap_add(struct encaptab *);
97 static int mask_match(const struct encaptab *, const struct sockaddr *,
98 const struct sockaddr *);
99 static void encap_fillarg(struct mbuf *, const struct encaptab *);
100
101 /*
102 * All global variables in ip_encap.c are locked using encapmtx.
103 */
104 static struct mtx encapmtx;
105 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
106 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
107
108 /*
109 * We currently keey encap_init() for source code compatibility reasons --
110 * it's referenced by KAME pieces in netinet6.
111 */
112 void
113 encap_init()
114 {
115 }
116
117 #ifdef INET
118 void
119 encap4_input(m, off)
120 struct mbuf *m;
121 int off;
122 {
123 struct ip *ip;
124 int proto;
125 struct sockaddr_in s, d;
126 const struct protosw *psw;
127 struct encaptab *ep, *match;
128 int prio, matchprio;
129
130 ip = mtod(m, struct ip *);
131 proto = ip->ip_p;
132
133 bzero(&s, sizeof(s));
134 s.sin_family = AF_INET;
135 s.sin_len = sizeof(struct sockaddr_in);
136 s.sin_addr = ip->ip_src;
137 bzero(&d, sizeof(d));
138 d.sin_family = AF_INET;
139 d.sin_len = sizeof(struct sockaddr_in);
140 d.sin_addr = ip->ip_dst;
141
142 match = NULL;
143 matchprio = 0;
144 mtx_lock(&encapmtx);
145 LIST_FOREACH(ep, &encaptab, chain) {
146 if (ep->af != AF_INET)
147 continue;
148 if (ep->proto >= 0 && ep->proto != proto)
149 continue;
150 if (ep->func)
151 prio = (*ep->func)(m, off, proto, ep->arg);
152 else {
153 /*
154 * it's inbound traffic, we need to match in reverse
155 * order
156 */
157 prio = mask_match(ep, (struct sockaddr *)&d,
158 (struct sockaddr *)&s);
159 }
160
161 /*
162 * We prioritize the matches by using bit length of the
163 * matches. mask_match() and user-supplied matching function
164 * should return the bit length of the matches (for example,
165 * if both src/dst are matched for IPv4, 64 should be returned).
166 * 0 or negative return value means "it did not match".
167 *
168 * The question is, since we have two "mask" portion, we
169 * cannot really define total order between entries.
170 * For example, which of these should be preferred?
171 * mask_match() returns 48 (32 + 16) for both of them.
172 * src=3ffe::/16, dst=3ffe:501::/32
173 * src=3ffe:501::/32, dst=3ffe::/16
174 *
175 * We need to loop through all the possible candidates
176 * to get the best match - the search takes O(n) for
177 * n attachments (i.e. interfaces).
178 */
179 if (prio <= 0)
180 continue;
181 if (prio > matchprio) {
182 matchprio = prio;
183 match = ep;
184 }
185 }
186 mtx_unlock(&encapmtx);
187
188 if (match) {
189 /* found a match, "match" has the best one */
190 psw = match->psw;
191 if (psw && psw->pr_input) {
192 encap_fillarg(m, match);
193 (*psw->pr_input)(m, off);
194 } else
195 m_freem(m);
196 return;
197 }
198
199 /* last resort: inject to raw socket */
200 rip_input(m, off);
201 }
202 #endif
203
204 #ifdef INET6
205 int
206 encap6_input(mp, offp, proto)
207 struct mbuf **mp;
208 int *offp;
209 int proto;
210 {
211 struct mbuf *m = *mp;
212 struct ip6_hdr *ip6;
213 struct sockaddr_in6 s, d;
214 const struct ip6protosw *psw;
215 struct encaptab *ep, *match;
216 int prio, matchprio;
217
218 ip6 = mtod(m, struct ip6_hdr *);
219
220 bzero(&s, sizeof(s));
221 s.sin6_family = AF_INET6;
222 s.sin6_len = sizeof(struct sockaddr_in6);
223 s.sin6_addr = ip6->ip6_src;
224 bzero(&d, sizeof(d));
225 d.sin6_family = AF_INET6;
226 d.sin6_len = sizeof(struct sockaddr_in6);
227 d.sin6_addr = ip6->ip6_dst;
228
229 match = NULL;
230 matchprio = 0;
231 mtx_lock(&encapmtx);
232 LIST_FOREACH(ep, &encaptab, chain) {
233 if (ep->af != AF_INET6)
234 continue;
235 if (ep->proto >= 0 && ep->proto != proto)
236 continue;
237 if (ep->func)
238 prio = (*ep->func)(m, *offp, proto, ep->arg);
239 else {
240 /*
241 * it's inbound traffic, we need to match in reverse
242 * order
243 */
244 prio = mask_match(ep, (struct sockaddr *)&d,
245 (struct sockaddr *)&s);
246 }
247
248 /* see encap4_input() for issues here */
249 if (prio <= 0)
250 continue;
251 if (prio > matchprio) {
252 matchprio = prio;
253 match = ep;
254 }
255 }
256 mtx_unlock(&encapmtx);
257
258 if (match) {
259 /* found a match */
260 psw = (const struct ip6protosw *)match->psw;
261 if (psw && psw->pr_input) {
262 encap_fillarg(m, match);
263 return (*psw->pr_input)(mp, offp, proto);
264 } else {
265 m_freem(m);
266 return IPPROTO_DONE;
267 }
268 }
269
270 /* last resort: inject to raw socket */
271 return rip6_input(mp, offp, proto);
272 }
273 #endif
274
275 /*lint -sem(encap_add, custodial(1)) */
276 static void
277 encap_add(ep)
278 struct encaptab *ep;
279 {
280
281 mtx_assert(&encapmtx, MA_OWNED);
282 LIST_INSERT_HEAD(&encaptab, ep, chain);
283 }
284
285 /*
286 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
287 * length of mask (sm and dm) is assumed to be same as sp/dp.
288 * Return value will be necessary as input (cookie) for encap_detach().
289 */
290 const struct encaptab *
291 encap_attach(af, proto, sp, sm, dp, dm, psw, arg)
292 int af;
293 int proto;
294 const struct sockaddr *sp, *sm;
295 const struct sockaddr *dp, *dm;
296 const struct protosw *psw;
297 void *arg;
298 {
299 struct encaptab *ep;
300
301 /* sanity check on args */
302 if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst))
303 return (NULL);
304 if (sp->sa_len != dp->sa_len)
305 return (NULL);
306 if (af != sp->sa_family || af != dp->sa_family)
307 return (NULL);
308
309 /* check if anyone have already attached with exactly same config */
310 mtx_lock(&encapmtx);
311 LIST_FOREACH(ep, &encaptab, chain) {
312 if (ep->af != af)
313 continue;
314 if (ep->proto != proto)
315 continue;
316 if (ep->src.ss_len != sp->sa_len ||
317 bcmp(&ep->src, sp, sp->sa_len) != 0 ||
318 bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
319 continue;
320 if (ep->dst.ss_len != dp->sa_len ||
321 bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
322 bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
323 continue;
324
325 mtx_unlock(&encapmtx);
326 return (NULL);
327 }
328
329 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/
330 if (ep == NULL) {
331 mtx_unlock(&encapmtx);
332 return (NULL);
333 }
334 bzero(ep, sizeof(*ep));
335
336 ep->af = af;
337 ep->proto = proto;
338 bcopy(sp, &ep->src, sp->sa_len);
339 bcopy(sm, &ep->srcmask, sp->sa_len);
340 bcopy(dp, &ep->dst, dp->sa_len);
341 bcopy(dm, &ep->dstmask, dp->sa_len);
342 ep->psw = psw;
343 ep->arg = arg;
344
345 encap_add(ep);
346 mtx_unlock(&encapmtx);
347 return (ep);
348 }
349
350 const struct encaptab *
351 encap_attach_func(af, proto, func, psw, arg)
352 int af;
353 int proto;
354 int (*func)(const struct mbuf *, int, int, void *);
355 const struct protosw *psw;
356 void *arg;
357 {
358 struct encaptab *ep;
359
360 /* sanity check on args */
361 if (!func)
362 return (NULL);
363
364 ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/
365 if (ep == NULL)
366 return (NULL);
367 bzero(ep, sizeof(*ep));
368
369 ep->af = af;
370 ep->proto = proto;
371 ep->func = func;
372 ep->psw = psw;
373 ep->arg = arg;
374
375 mtx_lock(&encapmtx);
376 encap_add(ep);
377 mtx_unlock(&encapmtx);
378 return (ep);
379 }
380
381 int
382 encap_detach(cookie)
383 const struct encaptab *cookie;
384 {
385 const struct encaptab *ep = cookie;
386 struct encaptab *p;
387
388 mtx_lock(&encapmtx);
389 LIST_FOREACH(p, &encaptab, chain) {
390 if (p == ep) {
391 LIST_REMOVE(p, chain);
392 mtx_unlock(&encapmtx);
393 free(p, M_NETADDR); /*XXX*/
394 return 0;
395 }
396 }
397 mtx_unlock(&encapmtx);
398
399 return EINVAL;
400 }
401
402 static int
403 mask_match(ep, sp, dp)
404 const struct encaptab *ep;
405 const struct sockaddr *sp;
406 const struct sockaddr *dp;
407 {
408 struct sockaddr_storage s;
409 struct sockaddr_storage d;
410 int i;
411 const u_int8_t *p, *q;
412 u_int8_t *r;
413 int matchlen;
414
415 if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
416 return 0;
417 if (sp->sa_family != ep->af || dp->sa_family != ep->af)
418 return 0;
419 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
420 return 0;
421
422 matchlen = 0;
423
424 p = (const u_int8_t *)sp;
425 q = (const u_int8_t *)&ep->srcmask;
426 r = (u_int8_t *)&s;
427 for (i = 0 ; i < sp->sa_len; i++) {
428 r[i] = p[i] & q[i];
429 /* XXX estimate */
430 matchlen += (q[i] ? 8 : 0);
431 }
432
433 p = (const u_int8_t *)dp;
434 q = (const u_int8_t *)&ep->dstmask;
435 r = (u_int8_t *)&d;
436 for (i = 0 ; i < dp->sa_len; i++) {
437 r[i] = p[i] & q[i];
438 /* XXX rough estimate */
439 matchlen += (q[i] ? 8 : 0);
440 }
441
442 /* need to overwrite len/family portion as we don't compare them */
443 s.ss_len = sp->sa_len;
444 s.ss_family = sp->sa_family;
445 d.ss_len = dp->sa_len;
446 d.ss_family = dp->sa_family;
447
448 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
449 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
450 return matchlen;
451 } else
452 return 0;
453 }
454
455 static void
456 encap_fillarg(m, ep)
457 struct mbuf *m;
458 const struct encaptab *ep;
459 {
460 struct m_tag *tag;
461
462 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), M_NOWAIT);
463 if (tag) {
464 *(void**)(tag+1) = ep->arg;
465 m_tag_prepend(m, tag);
466 }
467 }
468
469 void *
470 encap_getarg(m)
471 struct mbuf *m;
472 {
473 void *p = NULL;
474 struct m_tag *tag;
475
476 tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
477 if (tag) {
478 p = *(void**)(tag+1);
479 m_tag_delete(m, tag);
480 }
481 return p;
482 }
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