xref: /freebsd/sys/netinet/ip_encap.c (revision 2b743a9e9ddc6736208dc8ca1ce06ce64ad20a19) 
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 <sys/kernel.h>
91 #include <sys/malloc.h>
92 static MALLOC_DEFINE(M_NETADDR, "encap_export_host", "Export host address structure");
93 
94 static void encap_add(struct encaptab *);
95 static int mask_match(const struct encaptab *, const struct sockaddr *,
96 		const struct sockaddr *);
97 static void encap_fillarg(struct mbuf *, const struct encaptab *);
98 
99 /*
100  * All global variables in ip_encap.c are locked using encapmtx.
101  */
102 static struct mtx encapmtx;
103 MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
104 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
105 
106 /*
107  * We currently keey encap_init() for source code compatibility reasons --
108  * it's referenced by KAME pieces in netinet6.
109  */
110 void
111 encap_init()
112 {
113 }
114 
115 #ifdef INET
116 void
117 encap4_input(m, off)
118 	struct mbuf *m;
119 	int off;
120 {
121 	struct ip *ip;
122 	int proto;
123 	struct sockaddr_in s, d;
124 	const struct protosw *psw;
125 	struct encaptab *ep, *match;
126 	int prio, matchprio;
127 
128 	ip = mtod(m, struct ip *);
129 	proto = ip->ip_p;
130 
131 	bzero(&s, sizeof(s));
132 	s.sin_family = AF_INET;
133 	s.sin_len = sizeof(struct sockaddr_in);
134 	s.sin_addr = ip->ip_src;
135 	bzero(&d, sizeof(d));
136 	d.sin_family = AF_INET;
137 	d.sin_len = sizeof(struct sockaddr_in);
138 	d.sin_addr = ip->ip_dst;
139 
140 	match = NULL;
141 	matchprio = 0;
142 	mtx_lock(&encapmtx);
143 	LIST_FOREACH(ep, &encaptab, chain) {
144 		if (ep->af != AF_INET)
145 			continue;
146 		if (ep->proto >= 0 && ep->proto != proto)
147 			continue;
148 		if (ep->func)
149 			prio = (*ep->func)(m, off, proto, ep->arg);
150 		else {
151 			/*
152 			 * it's inbound traffic, we need to match in reverse
153 			 * order
154 			 */
155 			prio = mask_match(ep, (struct sockaddr *)&d,
156 			    (struct sockaddr *)&s);
157 		}
158 
159 		/*
160 		 * We prioritize the matches by using bit length of the
161 		 * matches.  mask_match() and user-supplied matching function
162 		 * should return the bit length of the matches (for example,
163 		 * if both src/dst are matched for IPv4, 64 should be returned).
164 		 * 0 or negative return value means "it did not match".
165 		 *
166 		 * The question is, since we have two "mask" portion, we
167 		 * cannot really define total order between entries.
168 		 * For example, which of these should be preferred?
169 		 * mask_match() returns 48 (32 + 16) for both of them.
170 		 *	src=3ffe::/16, dst=3ffe:501::/32
171 		 *	src=3ffe:501::/32, dst=3ffe::/16
172 		 *
173 		 * We need to loop through all the possible candidates
174 		 * to get the best match - the search takes O(n) for
175 		 * n attachments (i.e. interfaces).
176 		 */
177 		if (prio <= 0)
178 			continue;
179 		if (prio > matchprio) {
180 			matchprio = prio;
181 			match = ep;
182 		}
183 	}
184 	mtx_unlock(&encapmtx);
185 
186 	if (match) {
187 		/* found a match, "match" has the best one */
188 		psw = match->psw;
189 		if (psw && psw->pr_input) {
190 			encap_fillarg(m, match);
191 			(*psw->pr_input)(m, off);
192 		} else
193 			m_freem(m);
194 		return;
195 	}
196 
197 	/* last resort: inject to raw socket */
198 	rip_input(m, off);
199 }
200 #endif
201 
202 #ifdef INET6
203 int
204 encap6_input(mp, offp, proto)
205 	struct mbuf **mp;
206 	int *offp;
207 	int proto;
208 {
209 	struct mbuf *m = *mp;
210 	struct ip6_hdr *ip6;
211 	struct sockaddr_in6 s, d;
212 	const struct ip6protosw *psw;
213 	struct encaptab *ep, *match;
214 	int prio, matchprio;
215 
216 	ip6 = mtod(m, struct ip6_hdr *);
217 
218 	bzero(&s, sizeof(s));
219 	s.sin6_family = AF_INET6;
220 	s.sin6_len = sizeof(struct sockaddr_in6);
221 	s.sin6_addr = ip6->ip6_src;
222 	bzero(&d, sizeof(d));
223 	d.sin6_family = AF_INET6;
224 	d.sin6_len = sizeof(struct sockaddr_in6);
225 	d.sin6_addr = ip6->ip6_dst;
226 
227 	match = NULL;
228 	matchprio = 0;
229 	mtx_lock(&encapmtx);
230 	LIST_FOREACH(ep, &encaptab, chain) {
231 		if (ep->af != AF_INET6)
232 			continue;
233 		if (ep->proto >= 0 && ep->proto != proto)
234 			continue;
235 		if (ep->func)
236 			prio = (*ep->func)(m, *offp, proto, ep->arg);
237 		else {
238 			/*
239 			 * it's inbound traffic, we need to match in reverse
240 			 * order
241 			 */
242 			prio = mask_match(ep, (struct sockaddr *)&d,
243 			    (struct sockaddr *)&s);
244 		}
245 
246 		/* see encap4_input() for issues here */
247 		if (prio <= 0)
248 			continue;
249 		if (prio > matchprio) {
250 			matchprio = prio;
251 			match = ep;
252 		}
253 	}
254 	mtx_unlock(&encapmtx);
255 
256 	if (match) {
257 		/* found a match */
258 		psw = (const struct ip6protosw *)match->psw;
259 		if (psw && psw->pr_input) {
260 			encap_fillarg(m, match);
261 			return (*psw->pr_input)(mp, offp, proto);
262 		} else {
263 			m_freem(m);
264 			return IPPROTO_DONE;
265 		}
266 	}
267 
268 	/* last resort: inject to raw socket */
269 	return rip6_input(mp, offp, proto);
270 }
271 #endif
272 
273 /*lint -sem(encap_add, custodial(1)) */
274 static void
275 encap_add(ep)
276 	struct encaptab *ep;
277 {
278 
279 	mtx_assert(&encapmtx, MA_OWNED);
280 	LIST_INSERT_HEAD(&encaptab, ep, chain);
281 }
282 
283 /*
284  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
285  * length of mask (sm and dm) is assumed to be same as sp/dp.
286  * Return value will be necessary as input (cookie) for encap_detach().
287  */
288 const struct encaptab *
289 encap_attach(af, proto, sp, sm, dp, dm, psw, arg)
290 	int af;
291 	int proto;
292 	const struct sockaddr *sp, *sm;
293 	const struct sockaddr *dp, *dm;
294 	const struct protosw *psw;
295 	void *arg;
296 {
297 	struct encaptab *ep;
298 
299 	/* sanity check on args */
300 	if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst))
301 		return (NULL);
302 	if (sp->sa_len != dp->sa_len)
303 		return (NULL);
304 	if (af != sp->sa_family || af != dp->sa_family)
305 		return (NULL);
306 
307 	/* check if anyone have already attached with exactly same config */
308 	mtx_lock(&encapmtx);
309 	LIST_FOREACH(ep, &encaptab, chain) {
310 		if (ep->af != af)
311 			continue;
312 		if (ep->proto != proto)
313 			continue;
314 		if (ep->src.ss_len != sp->sa_len ||
315 		    bcmp(&ep->src, sp, sp->sa_len) != 0 ||
316 		    bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
317 			continue;
318 		if (ep->dst.ss_len != dp->sa_len ||
319 		    bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
320 		    bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
321 			continue;
322 
323 		mtx_unlock(&encapmtx);
324 		return (NULL);
325 	}
326 
327 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);	/*XXX*/
328 	if (ep == NULL) {
329 		mtx_unlock(&encapmtx);
330 		return (NULL);
331 	}
332 	bzero(ep, sizeof(*ep));
333 
334 	ep->af = af;
335 	ep->proto = proto;
336 	bcopy(sp, &ep->src, sp->sa_len);
337 	bcopy(sm, &ep->srcmask, sp->sa_len);
338 	bcopy(dp, &ep->dst, dp->sa_len);
339 	bcopy(dm, &ep->dstmask, dp->sa_len);
340 	ep->psw = psw;
341 	ep->arg = arg;
342 
343 	encap_add(ep);
344 	mtx_unlock(&encapmtx);
345 	return (ep);
346 }
347 
348 const struct encaptab *
349 encap_attach_func(af, proto, func, psw, arg)
350 	int af;
351 	int proto;
352 	int (*func)(const struct mbuf *, int, int, void *);
353 	const struct protosw *psw;
354 	void *arg;
355 {
356 	struct encaptab *ep;
357 
358 	/* sanity check on args */
359 	if (!func)
360 		return (NULL);
361 
362 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);	/*XXX*/
363 	if (ep == NULL)
364 		return (NULL);
365 	bzero(ep, sizeof(*ep));
366 
367 	ep->af = af;
368 	ep->proto = proto;
369 	ep->func = func;
370 	ep->psw = psw;
371 	ep->arg = arg;
372 
373 	mtx_lock(&encapmtx);
374 	encap_add(ep);
375 	mtx_unlock(&encapmtx);
376 	return (ep);
377 }
378 
379 int
380 encap_detach(cookie)
381 	const struct encaptab *cookie;
382 {
383 	const struct encaptab *ep = cookie;
384 	struct encaptab *p;
385 
386 	mtx_lock(&encapmtx);
387 	LIST_FOREACH(p, &encaptab, chain) {
388 		if (p == ep) {
389 			LIST_REMOVE(p, chain);
390 			mtx_unlock(&encapmtx);
391 			free(p, M_NETADDR);	/*XXX*/
392 			return 0;
393 		}
394 	}
395 	mtx_unlock(&encapmtx);
396 
397 	return EINVAL;
398 }
399 
400 static int
401 mask_match(ep, sp, dp)
402 	const struct encaptab *ep;
403 	const struct sockaddr *sp;
404 	const struct sockaddr *dp;
405 {
406 	struct sockaddr_storage s;
407 	struct sockaddr_storage d;
408 	int i;
409 	const u_int8_t *p, *q;
410 	u_int8_t *r;
411 	int matchlen;
412 
413 	if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
414 		return 0;
415 	if (sp->sa_family != ep->af || dp->sa_family != ep->af)
416 		return 0;
417 	if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
418 		return 0;
419 
420 	matchlen = 0;
421 
422 	p = (const u_int8_t *)sp;
423 	q = (const u_int8_t *)&ep->srcmask;
424 	r = (u_int8_t *)&s;
425 	for (i = 0 ; i < sp->sa_len; i++) {
426 		r[i] = p[i] & q[i];
427 		/* XXX estimate */
428 		matchlen += (q[i] ? 8 : 0);
429 	}
430 
431 	p = (const u_int8_t *)dp;
432 	q = (const u_int8_t *)&ep->dstmask;
433 	r = (u_int8_t *)&d;
434 	for (i = 0 ; i < dp->sa_len; i++) {
435 		r[i] = p[i] & q[i];
436 		/* XXX rough estimate */
437 		matchlen += (q[i] ? 8 : 0);
438 	}
439 
440 	/* need to overwrite len/family portion as we don't compare them */
441 	s.ss_len = sp->sa_len;
442 	s.ss_family = sp->sa_family;
443 	d.ss_len = dp->sa_len;
444 	d.ss_family = dp->sa_family;
445 
446 	if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
447 	    bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
448 		return matchlen;
449 	} else
450 		return 0;
451 }
452 
453 static void
454 encap_fillarg(m, ep)
455 	struct mbuf *m;
456 	const struct encaptab *ep;
457 {
458 	struct m_tag *tag;
459 
460 	tag = m_tag_get(PACKET_TAG_ENCAP, sizeof (void*), M_NOWAIT);
461 	if (tag) {
462 		*(void**)(tag+1) = ep->arg;
463 		m_tag_prepend(m, tag);
464 	}
465 }
466 
467 void *
468 encap_getarg(m)
469 	struct mbuf *m;
470 {
471 	void *p = NULL;
472 	struct m_tag *tag;
473 
474 	tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
475 	if (tag) {
476 		p = *(void**)(tag+1);
477 		m_tag_delete(m, tag);
478 	}
479 	return p;
480 }
481