xref: /dragonfly/sys/netinet/ip_encap.c (revision 0bb9290e) 
1 /*	$FreeBSD: src/sys/netinet/ip_encap.c,v 1.1.2.5 2003/01/23 21:06:45 sam Exp $	*/
2 /*	$DragonFly: src/sys/netinet/ip_encap.c,v 1.14 2006/01/14 11:33:50 swildner Exp $	*/
3 /*	$KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $	*/
4 
5 /*
6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the project nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 /*
34  * My grandfather said that there's a devil inside tunnelling technology...
35  *
36  * We have surprisingly many protocols that want packets with IP protocol
37  * #4 or #41.  Here's a list of protocols that want protocol #41:
38  *	RFC1933 configured tunnel
39  *	RFC1933 automatic tunnel
40  *	RFC2401 IPsec tunnel
41  *	RFC2473 IPv6 generic packet tunnelling
42  *	RFC2529 6over4 tunnel
43  *	mobile-ip6 (uses RFC2473)
44  *	RFC3056 6to4 tunnel
45  *	isatap tunnel
46  * Here's a list of protocol that want protocol #4:
47  *	RFC1853 IPv4-in-IPv4 tunnelling
48  *	RFC2003 IPv4 encapsulation within IPv4
49  *	RFC2344 reverse tunnelling for mobile-ip4
50  *	RFC2401 IPsec tunnel
51  * Well, what can I say.  They impose different en/decapsulation mechanism
52  * from each other, so they need separate protocol handler.  The only one
53  * we can easily determine by protocol # is IPsec, which always has
54  * AH/ESP/IPComp header right after outer IP header.
55  *
56  * So, clearly good old protosw does not work for protocol #4 and #41.
57  * The code will let you match protocol via src/dst address pair.
58  */
59 /* XXX is M_NETADDR correct? */
60 
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 #include <sys/thread2.h>
95 MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
96 
97 static void encap_add (struct encaptab *);
98 static int mask_match (const struct encaptab *, const struct sockaddr *,
99 		const struct sockaddr *);
100 static void encap_fillarg (struct mbuf *, const struct encaptab *);
101 
102 #ifndef LIST_HEAD_INITIALIZER
103 /* rely upon BSS initialization */
104 LIST_HEAD(, encaptab) encaptab;
105 #else
106 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
107 #endif
108 
109 void     (*ipip_input)(struct mbuf *, int, int); /* hook for mrouting */
110 
111 void
112 encap_init(void)
113 {
114 	static int initialized = 0;
115 
116 	if (initialized)
117 		return;
118 	initialized++;
119 #if 0
120 	/*
121 	 * we cannot use LIST_INIT() here, since drivers may want to call
122 	 * encap_attach(), on driver attach.  encap_init() will be called
123 	 * on AF_INET{,6} initialization, which happens after driver
124 	 * initialization - using LIST_INIT() here can nuke encap_attach()
125 	 * from drivers.
126 	 */
127 	LIST_INIT(&encaptab);
128 #endif
129 }
130 
131 #ifdef INET
132 void
133 encap4_input(struct mbuf *m, ...)
134 {
135 	int off, proto;
136 	struct ip *ip;
137 	struct sockaddr_in s, d;
138 	const struct protosw *psw;
139 	struct encaptab *ep, *match;
140 	int prio, matchprio;
141 	__va_list ap;
142 
143 	__va_start(ap, m);
144 	off = __va_arg(ap, int);
145 	proto = __va_arg(ap, int);
146 	__va_end(ap);
147 
148 	ip = mtod(m, struct ip *);
149 
150 	bzero(&s, sizeof s);
151 	s.sin_family = AF_INET;
152 	s.sin_len = sizeof(struct sockaddr_in);
153 	s.sin_addr = ip->ip_src;
154 	bzero(&d, sizeof d);
155 	d.sin_family = AF_INET;
156 	d.sin_len = sizeof(struct sockaddr_in);
157 	d.sin_addr = ip->ip_dst;
158 
159 	match = NULL;
160 	matchprio = 0;
161 	for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
162 		if (ep->af != AF_INET)
163 			continue;
164 		if (ep->proto >= 0 && ep->proto != proto)
165 			continue;
166 		if (ep->func)
167 			prio = (*ep->func)(m, off, proto, ep->arg);
168 		else {
169 			/*
170 			 * it's inbound traffic, we need to match in reverse
171 			 * order
172 			 */
173 			prio = mask_match(ep, (struct sockaddr *)&d,
174 			    (struct sockaddr *)&s);
175 		}
176 
177 		/*
178 		 * We prioritize the matches by using bit length of the
179 		 * matches.  mask_match() and user-supplied matching function
180 		 * should return the bit length of the matches (for example,
181 		 * if both src/dst are matched for IPv4, 64 should be returned).
182 		 * 0 or negative return value means "it did not match".
183 		 *
184 		 * The question is, since we have two "mask" portion, we
185 		 * cannot really define total order between entries.
186 		 * For example, which of these should be preferred?
187 		 * mask_match() returns 48 (32 + 16) for both of them.
188 		 *	src=3ffe::/16, dst=3ffe:501::/32
189 		 *	src=3ffe:501::/32, dst=3ffe::/16
190 		 *
191 		 * We need to loop through all the possible candidates
192 		 * to get the best match - the search takes O(n) for
193 		 * n attachments (i.e. interfaces).
194 		 */
195 		if (prio <= 0)
196 			continue;
197 		if (prio > matchprio) {
198 			matchprio = prio;
199 			match = ep;
200 		}
201 	}
202 
203 	if (match) {
204 		/* found a match, "match" has the best one */
205 		psw = match->psw;
206 		if (psw && psw->pr_input) {
207 			encap_fillarg(m, match);
208 			(*psw->pr_input)(m, off, proto);
209 		} else
210 			m_freem(m);
211 		return;
212 	}
213 
214 	/* for backward compatibility */
215 	if (proto == IPPROTO_IPV4 && ipip_input) {
216 		ipip_input(m, off, proto);
217 		return;
218 	}
219 
220 	/* last resort: inject to raw socket */
221 	rip_input(m, off, proto);
222 }
223 #endif
224 
225 #ifdef INET6
226 int
227 encap6_input(struct mbuf **mp, int *offp, int proto)
228 {
229 	struct mbuf *m = *mp;
230 	struct ip6_hdr *ip6;
231 	struct sockaddr_in6 s, d;
232 	const struct ip6protosw *psw;
233 	struct encaptab *ep, *match;
234 	int prio, matchprio;
235 
236 	ip6 = mtod(m, struct ip6_hdr *);
237 
238 	bzero(&s, sizeof s);
239 	s.sin6_family = AF_INET6;
240 	s.sin6_len = sizeof(struct sockaddr_in6);
241 	s.sin6_addr = ip6->ip6_src;
242 	bzero(&d, sizeof d);
243 	d.sin6_family = AF_INET6;
244 	d.sin6_len = sizeof(struct sockaddr_in6);
245 	d.sin6_addr = ip6->ip6_dst;
246 
247 	match = NULL;
248 	matchprio = 0;
249 	for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
250 		if (ep->af != AF_INET6)
251 			continue;
252 		if (ep->proto >= 0 && ep->proto != proto)
253 			continue;
254 		if (ep->func)
255 			prio = (*ep->func)(m, *offp, proto, ep->arg);
256 		else {
257 			/*
258 			 * it's inbound traffic, we need to match in reverse
259 			 * order
260 			 */
261 			prio = mask_match(ep, (struct sockaddr *)&d,
262 			    (struct sockaddr *)&s);
263 		}
264 
265 		/* see encap4_input() for issues here */
266 		if (prio <= 0)
267 			continue;
268 		if (prio > matchprio) {
269 			matchprio = prio;
270 			match = ep;
271 		}
272 	}
273 
274 	if (match) {
275 		/* found a match */
276 		psw = (const struct ip6protosw *)match->psw;
277 		if (psw && psw->pr_input) {
278 			encap_fillarg(m, match);
279 			return (*psw->pr_input)(mp, offp, proto);
280 		} else {
281 			m_freem(m);
282 			return IPPROTO_DONE;
283 		}
284 	}
285 
286 	/* last resort: inject to raw socket */
287 	return rip6_input(mp, offp, proto);
288 }
289 #endif
290 
291 static void
292 encap_add(struct encaptab *ep)
293 {
294 
295 	LIST_INSERT_HEAD(&encaptab, ep, chain);
296 }
297 
298 /*
299  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
300  * length of mask (sm and dm) is assumed to be same as sp/dp.
301  * Return value will be necessary as input (cookie) for encap_detach().
302  */
303 const struct encaptab *
304 encap_attach(int af, int proto, const struct sockaddr *sp,
305 	     const struct sockaddr *sm, const struct sockaddr *dp,
306 	     const struct sockaddr *dm, const struct protosw *psw, void *arg)
307 {
308 	struct encaptab *ep;
309 	int error;
310 
311 	crit_enter();
312 	/* sanity check on args */
313 	if (sp->sa_len > sizeof ep->src || dp->sa_len > sizeof ep->dst) {
314 		error = EINVAL;
315 		goto fail;
316 	}
317 	if (sp->sa_len != dp->sa_len) {
318 		error = EINVAL;
319 		goto fail;
320 	}
321 	if (af != sp->sa_family || af != dp->sa_family) {
322 		error = EINVAL;
323 		goto fail;
324 	}
325 
326 	/* check if anyone have already attached with exactly same config */
327 	for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
328 		if (ep->af != af)
329 			continue;
330 		if (ep->proto != proto)
331 			continue;
332 		if (ep->src.ss_len != sp->sa_len ||
333 		    bcmp(&ep->src, sp, sp->sa_len) != 0 ||
334 		    bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
335 			continue;
336 		if (ep->dst.ss_len != dp->sa_len ||
337 		    bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
338 		    bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
339 			continue;
340 
341 		error = EEXIST;
342 		goto fail;
343 	}
344 
345 	ep = malloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK);
346 	if (ep == NULL) {
347 		error = ENOBUFS;
348 		goto fail;
349 	}
350 
351 	ep->af = af;
352 	ep->proto = proto;
353 	bcopy(sp, &ep->src, sp->sa_len);
354 	bcopy(sm, &ep->srcmask, sp->sa_len);
355 	bcopy(dp, &ep->dst, dp->sa_len);
356 	bcopy(dm, &ep->dstmask, dp->sa_len);
357 	ep->psw = psw;
358 	ep->arg = arg;
359 
360 	encap_add(ep);
361 
362 	error = 0;
363 	crit_exit();
364 	return ep;
365 
366 fail:
367 	crit_exit();
368 	return NULL;
369 }
370 
371 const struct encaptab *
372 encap_attach_func(int af, int proto,
373 		  int (*func)(const struct mbuf *, int, int, void *),
374 		  const struct protosw *psw, void *arg)
375 {
376 	struct encaptab *ep;
377 	int error;
378 
379 	crit_enter();
380 	/* sanity check on args */
381 	if (!func) {
382 		error = EINVAL;
383 		goto fail;
384 	}
385 
386 	ep = malloc(sizeof *ep, M_NETADDR, M_INTWAIT | M_ZERO | M_NULLOK);
387 	if (ep == NULL) {
388 		error = ENOBUFS;
389 		goto fail;
390 	}
391 
392 	ep->af = af;
393 	ep->proto = proto;
394 	ep->func = func;
395 	ep->psw = psw;
396 	ep->arg = arg;
397 
398 	encap_add(ep);
399 
400 	error = 0;
401 	crit_exit();
402 	return ep;
403 
404 fail:
405 	crit_exit();
406 	return NULL;
407 }
408 
409 int
410 encap_detach(const struct encaptab *cookie)
411 {
412 	const struct encaptab *ep = cookie;
413 	struct encaptab *p;
414 
415 	for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
416 		if (p == ep) {
417 			LIST_REMOVE(p, chain);
418 			free(p, M_NETADDR);	/*XXX*/
419 			return 0;
420 		}
421 	}
422 
423 	return EINVAL;
424 }
425 
426 static int
427 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
428 	   const struct sockaddr *dp)
429 {
430 	struct sockaddr_storage s;
431 	struct sockaddr_storage d;
432 	int i;
433 	const u_int8_t *p, *q;
434 	u_int8_t *r;
435 	int matchlen;
436 
437 	if (sp->sa_len > sizeof s || dp->sa_len > sizeof d)
438 		return 0;
439 	if (sp->sa_family != ep->af || dp->sa_family != ep->af)
440 		return 0;
441 	if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
442 		return 0;
443 
444 	matchlen = 0;
445 
446 	p = (const u_int8_t *)sp;
447 	q = (const u_int8_t *)&ep->srcmask;
448 	r = (u_int8_t *)&s;
449 	for (i = 0 ; i < sp->sa_len; i++) {
450 		r[i] = p[i] & q[i];
451 		/* XXX estimate */
452 		matchlen += (q[i] ? 8 : 0);
453 	}
454 
455 	p = (const u_int8_t *)dp;
456 	q = (const u_int8_t *)&ep->dstmask;
457 	r = (u_int8_t *)&d;
458 	for (i = 0 ; i < dp->sa_len; i++) {
459 		r[i] = p[i] & q[i];
460 		/* XXX rough estimate */
461 		matchlen += (q[i] ? 8 : 0);
462 	}
463 
464 	/* need to overwrite len/family portion as we don't compare them */
465 	s.ss_len = sp->sa_len;
466 	s.ss_family = sp->sa_family;
467 	d.ss_len = dp->sa_len;
468 	d.ss_family = dp->sa_family;
469 
470 	if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
471 	    bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
472 		return matchlen;
473 	} else
474 		return 0;
475 }
476 
477 static void
478 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
479 {
480 	struct m_tag *tag;
481 
482 	tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), MB_DONTWAIT);
483 	if (tag != NULL) {
484 		*(void **)m_tag_data(tag) = ep->arg;
485 		m_tag_prepend(m, tag);
486 	}
487 }
488 
489 void *
490 encap_getarg(struct mbuf *m)
491 {
492 	void *p = NULL;
493 	struct m_tag *tag;
494 
495 	tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
496 	if (tag != NULL) {
497 		p = *(void **)m_tag_data(tag);
498 		m_tag_delete(m, tag);
499 	}
500 	return p;
501 }
502