xref: /freebsd/sys/netinet/ip_encap.c (revision 7660b554bc59a07be0431c17e0e33815818baa69) 
1 /*	$FreeBSD$	*/
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 #ifndef LIST_HEAD_INITIALIZER
102 /* rely upon BSS initialization */
103 LIST_HEAD(, encaptab) encaptab;
104 #else
105 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
106 #endif
107 
108 void
109 encap_init()
110 {
111 	static int initialized = 0;
112 
113 	if (initialized)
114 		return;
115 	initialized++;
116 #if 0
117 	/*
118 	 * we cannot use LIST_INIT() here, since drivers may want to call
119 	 * encap_attach(), on driver attach.  encap_init() will be called
120 	 * on AF_INET{,6} initialization, which happens after driver
121 	 * initialization - using LIST_INIT() here can nuke encap_attach()
122 	 * from drivers.
123 	 */
124 	LIST_INIT(&encaptab);
125 #endif
126 }
127 
128 #ifdef INET
129 void
130 encap4_input(m, off)
131 	struct mbuf *m;
132 	int off;
133 {
134 	struct ip *ip;
135 	int proto;
136 	struct sockaddr_in s, d;
137 	const struct protosw *psw;
138 	struct encaptab *ep, *match;
139 	int prio, matchprio;
140 
141 	ip = mtod(m, struct ip *);
142 	proto = ip->ip_p;
143 
144 	bzero(&s, sizeof(s));
145 	s.sin_family = AF_INET;
146 	s.sin_len = sizeof(struct sockaddr_in);
147 	s.sin_addr = ip->ip_src;
148 	bzero(&d, sizeof(d));
149 	d.sin_family = AF_INET;
150 	d.sin_len = sizeof(struct sockaddr_in);
151 	d.sin_addr = ip->ip_dst;
152 
153 	match = NULL;
154 	matchprio = 0;
155 	LIST_FOREACH(ep, &encaptab, chain) {
156 		if (ep->af != AF_INET)
157 			continue;
158 		if (ep->proto >= 0 && ep->proto != proto)
159 			continue;
160 		if (ep->func)
161 			prio = (*ep->func)(m, off, proto, ep->arg);
162 		else {
163 			/*
164 			 * it's inbound traffic, we need to match in reverse
165 			 * order
166 			 */
167 			prio = mask_match(ep, (struct sockaddr *)&d,
168 			    (struct sockaddr *)&s);
169 		}
170 
171 		/*
172 		 * We prioritize the matches by using bit length of the
173 		 * matches.  mask_match() and user-supplied matching function
174 		 * should return the bit length of the matches (for example,
175 		 * if both src/dst are matched for IPv4, 64 should be returned).
176 		 * 0 or negative return value means "it did not match".
177 		 *
178 		 * The question is, since we have two "mask" portion, we
179 		 * cannot really define total order between entries.
180 		 * For example, which of these should be preferred?
181 		 * mask_match() returns 48 (32 + 16) for both of them.
182 		 *	src=3ffe::/16, dst=3ffe:501::/32
183 		 *	src=3ffe:501::/32, dst=3ffe::/16
184 		 *
185 		 * We need to loop through all the possible candidates
186 		 * to get the best match - the search takes O(n) for
187 		 * n attachments (i.e. interfaces).
188 		 */
189 		if (prio <= 0)
190 			continue;
191 		if (prio > matchprio) {
192 			matchprio = prio;
193 			match = ep;
194 		}
195 	}
196 
197 	if (match) {
198 		/* found a match, "match" has the best one */
199 		psw = match->psw;
200 		if (psw && psw->pr_input) {
201 			encap_fillarg(m, match);
202 			(*psw->pr_input)(m, off);
203 		} else
204 			m_freem(m);
205 		return;
206 	}
207 
208 	/* last resort: inject to raw socket */
209 	rip_input(m, off);
210 }
211 #endif
212 
213 #ifdef INET6
214 int
215 encap6_input(mp, offp, proto)
216 	struct mbuf **mp;
217 	int *offp;
218 	int proto;
219 {
220 	struct mbuf *m = *mp;
221 	struct ip6_hdr *ip6;
222 	struct sockaddr_in6 s, d;
223 	const struct ip6protosw *psw;
224 	struct encaptab *ep, *match;
225 	int prio, matchprio;
226 
227 	ip6 = mtod(m, struct ip6_hdr *);
228 
229 	bzero(&s, sizeof(s));
230 	s.sin6_family = AF_INET6;
231 	s.sin6_len = sizeof(struct sockaddr_in6);
232 	s.sin6_addr = ip6->ip6_src;
233 	bzero(&d, sizeof(d));
234 	d.sin6_family = AF_INET6;
235 	d.sin6_len = sizeof(struct sockaddr_in6);
236 	d.sin6_addr = ip6->ip6_dst;
237 
238 	match = NULL;
239 	matchprio = 0;
240 	LIST_FOREACH(ep, &encaptab, chain) {
241 		if (ep->af != AF_INET6)
242 			continue;
243 		if (ep->proto >= 0 && ep->proto != proto)
244 			continue;
245 		if (ep->func)
246 			prio = (*ep->func)(m, *offp, proto, ep->arg);
247 		else {
248 			/*
249 			 * it's inbound traffic, we need to match in reverse
250 			 * order
251 			 */
252 			prio = mask_match(ep, (struct sockaddr *)&d,
253 			    (struct sockaddr *)&s);
254 		}
255 
256 		/* see encap4_input() for issues here */
257 		if (prio <= 0)
258 			continue;
259 		if (prio > matchprio) {
260 			matchprio = prio;
261 			match = ep;
262 		}
263 	}
264 
265 	if (match) {
266 		/* found a match */
267 		psw = (const struct ip6protosw *)match->psw;
268 		if (psw && psw->pr_input) {
269 			encap_fillarg(m, match);
270 			return (*psw->pr_input)(mp, offp, proto);
271 		} else {
272 			m_freem(m);
273 			return IPPROTO_DONE;
274 		}
275 	}
276 
277 	/* last resort: inject to raw socket */
278 	return rip6_input(mp, offp, proto);
279 }
280 #endif
281 
282 /*lint -sem(encap_add, custodial(1)) */
283 static void
284 encap_add(ep)
285 	struct encaptab *ep;
286 {
287 
288 	LIST_INSERT_HEAD(&encaptab, ep, chain);
289 }
290 
291 /*
292  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
293  * length of mask (sm and dm) is assumed to be same as sp/dp.
294  * Return value will be necessary as input (cookie) for encap_detach().
295  */
296 const struct encaptab *
297 encap_attach(af, proto, sp, sm, dp, dm, psw, arg)
298 	int af;
299 	int proto;
300 	const struct sockaddr *sp, *sm;
301 	const struct sockaddr *dp, *dm;
302 	const struct protosw *psw;
303 	void *arg;
304 {
305 	struct encaptab *ep;
306 	int s;
307 
308 	s = splnet();
309 	/* sanity check on args */
310 	if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) {
311 		goto fail;
312 	}
313 	if (sp->sa_len != dp->sa_len) {
314 		goto fail;
315 	}
316 	if (af != sp->sa_family || af != dp->sa_family) {
317 		goto fail;
318 	}
319 
320 	/* check if anyone have already attached with exactly same config */
321 	LIST_FOREACH(ep, &encaptab, chain) {
322 		if (ep->af != af)
323 			continue;
324 		if (ep->proto != proto)
325 			continue;
326 		if (ep->src.ss_len != sp->sa_len ||
327 		    bcmp(&ep->src, sp, sp->sa_len) != 0 ||
328 		    bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
329 			continue;
330 		if (ep->dst.ss_len != dp->sa_len ||
331 		    bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
332 		    bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
333 			continue;
334 
335 		goto fail;
336 	}
337 
338 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);	/*XXX*/
339 	if (ep == NULL) {
340 		goto fail;
341 	}
342 	bzero(ep, sizeof(*ep));
343 
344 	ep->af = af;
345 	ep->proto = proto;
346 	bcopy(sp, &ep->src, sp->sa_len);
347 	bcopy(sm, &ep->srcmask, sp->sa_len);
348 	bcopy(dp, &ep->dst, dp->sa_len);
349 	bcopy(dm, &ep->dstmask, dp->sa_len);
350 	ep->psw = psw;
351 	ep->arg = arg;
352 
353 	encap_add(ep);
354 
355 	splx(s);
356 	return ep;
357 
358 fail:
359 	splx(s);
360 	return NULL;
361 }
362 
363 const struct encaptab *
364 encap_attach_func(af, proto, func, psw, arg)
365 	int af;
366 	int proto;
367 	int (*func)(const struct mbuf *, int, int, void *);
368 	const struct protosw *psw;
369 	void *arg;
370 {
371 	struct encaptab *ep;
372 	int s;
373 
374 	s = splnet();
375 	/* sanity check on args */
376 	if (!func)
377 		goto fail;
378 
379 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);	/*XXX*/
380 	if (ep == NULL)
381 		goto fail;
382 	bzero(ep, sizeof(*ep));
383 
384 	ep->af = af;
385 	ep->proto = proto;
386 	ep->func = func;
387 	ep->psw = psw;
388 	ep->arg = arg;
389 
390 	encap_add(ep);
391 
392 	splx(s);
393 	return ep;
394 
395 fail:
396 	splx(s);
397 	return NULL;
398 }
399 
400 int
401 encap_detach(cookie)
402 	const struct encaptab *cookie;
403 {
404 	const struct encaptab *ep = cookie;
405 	struct encaptab *p;
406 
407 	LIST_FOREACH(p, &encaptab, chain) {
408 		if (p == ep) {
409 			LIST_REMOVE(p, chain);
410 			free(p, M_NETADDR);	/*XXX*/
411 			return 0;
412 		}
413 	}
414 
415 	return EINVAL;
416 }
417 
418 static int
419 mask_match(ep, sp, dp)
420 	const struct encaptab *ep;
421 	const struct sockaddr *sp;
422 	const struct sockaddr *dp;
423 {
424 	struct sockaddr_storage s;
425 	struct sockaddr_storage d;
426 	int i;
427 	const u_int8_t *p, *q;
428 	u_int8_t *r;
429 	int matchlen;
430 
431 	if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
432 		return 0;
433 	if (sp->sa_family != ep->af || dp->sa_family != ep->af)
434 		return 0;
435 	if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
436 		return 0;
437 
438 	matchlen = 0;
439 
440 	p = (const u_int8_t *)sp;
441 	q = (const u_int8_t *)&ep->srcmask;
442 	r = (u_int8_t *)&s;
443 	for (i = 0 ; i < sp->sa_len; i++) {
444 		r[i] = p[i] & q[i];
445 		/* XXX estimate */
446 		matchlen += (q[i] ? 8 : 0);
447 	}
448 
449 	p = (const u_int8_t *)dp;
450 	q = (const u_int8_t *)&ep->dstmask;
451 	r = (u_int8_t *)&d;
452 	for (i = 0 ; i < dp->sa_len; i++) {
453 		r[i] = p[i] & q[i];
454 		/* XXX rough estimate */
455 		matchlen += (q[i] ? 8 : 0);
456 	}
457 
458 	/* need to overwrite len/family portion as we don't compare them */
459 	s.ss_len = sp->sa_len;
460 	s.ss_family = sp->sa_family;
461 	d.ss_len = dp->sa_len;
462 	d.ss_family = dp->sa_family;
463 
464 	if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
465 	    bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
466 		return matchlen;
467 	} else
468 		return 0;
469 }
470 
471 static void
472 encap_fillarg(m, ep)
473 	struct mbuf *m;
474 	const struct encaptab *ep;
475 {
476 	struct m_tag *tag;
477 
478 	tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), M_NOWAIT);
479 	if (tag) {
480 		*(void**)(tag+1) = ep->arg;
481 		m_tag_prepend(m, tag);
482 	}
483 }
484 
485 void *
486 encap_getarg(m)
487 	struct mbuf *m;
488 {
489 	void *p = NULL;
490 	struct m_tag *tag;
491 
492 	tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
493 	if (tag) {
494 		p = *(void**)(tag+1);
495 		m_tag_delete(m, tag);
496 	}
497 	return p;
498 }
499