1 /* $FreeBSD: src/sys/netinet/ip_encap.c,v 1.1.2.5 2003/01/23 21:06:45 sam Exp $ */
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
59 #include "opt_inet.h"
60 #include "opt_inet6.h"
61
62 #include <sys/param.h>
63 #include <sys/systm.h>
64 #include <sys/socket.h>
65 #include <sys/sockio.h>
66 #include <sys/mbuf.h>
67 #include <sys/errno.h>
68 #include <sys/protosw.h>
69 #include <sys/queue.h>
70
71 #include <net/if.h>
72 #include <net/route.h>
73
74 #include <netinet/in.h>
75 #include <netinet/in_systm.h>
76 #include <netinet/ip.h>
77 #include <netinet/ip_var.h>
78 #include <netinet/ip_encap.h>
79
80 #ifdef INET6
81 #include <netinet/ip6.h>
82 #include <netinet6/ip6_var.h>
83 #include <netinet6/ip6protosw.h>
84 #endif
85
86 #include <machine/stdarg.h>
87
88 #include <net/net_osdep.h>
89
90 #include <sys/kernel.h>
91 #include <sys/malloc.h>
92 #include <sys/thread2.h>
93 MALLOC_DEFINE(M_IPENCAP, "IP Encapsulation", "IP Encapsulation");
94
95 static void encap_add (struct encaptab *);
96 static int mask_match (const struct encaptab *, const struct sockaddr *,
97 const struct sockaddr *);
98 static void encap_fillarg (struct mbuf *, const struct encaptab *);
99
100 #ifndef LIST_HEAD_INITIALIZER
101 /* rely upon BSS initialization */
102 LIST_HEAD(, encaptab) encaptab;
103 #else
104 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
105 #endif
106
107 int (*ipip_input)(struct mbuf **, int *, int); /* hook for mrouting */
108
109 void
encap_init(void)110 encap_init(void)
111 {
112 static int initialized = 0;
113
114 if (initialized)
115 return;
116 initialized++;
117 #if 0
118 /*
119 * we cannot use LIST_INIT() here, since drivers may want to call
120 * encap_attach(), on driver attach. encap_init() will be called
121 * on AF_INET{,6} initialization, which happens after driver
122 * initialization - using LIST_INIT() here can nuke encap_attach()
123 * from drivers.
124 */
125 LIST_INIT(&encaptab);
126 #endif
127 }
128
129 #ifdef INET
130 int
encap4_input(struct mbuf ** mp,int * offp,int proto)131 encap4_input(struct mbuf **mp, int *offp, int proto)
132 {
133 struct mbuf *m = *mp;
134 int off = *offp;
135 struct ip *ip;
136 struct sockaddr_in s, d;
137 const struct protosw *psw;
138 struct encaptab *ep, *match;
139 int prio, matchprio;
140
141 if (!IN_NETISR(0)) {
142 /*
143 * NOTE:
144 * Some NICs, noticeably igb(4) and ix(4), use inner IP
145 * datagram to calculate the packet hash, which leads us
146 * here.
147 */
148 m->m_flags &= ~M_HASH;
149 m = ip_rehashm(m);
150 if (m != NULL) {
151 lwkt_port_t port = netisr_hashport(m->m_pkthdr.hash);
152
153 KASSERT(port != &curthread->td_msgport,
154 ("mbuf hash recursion"));
155 ip_transport_redispatch(port, m, off);
156 }
157 return (IPPROTO_DONE);
158 }
159
160 ip = mtod(m, struct ip *);
161 *mp = NULL;
162
163 bzero(&s, sizeof s);
164 s.sin_family = AF_INET;
165 s.sin_len = sizeof(struct sockaddr_in);
166 s.sin_addr = ip->ip_src;
167 bzero(&d, sizeof d);
168 d.sin_family = AF_INET;
169 d.sin_len = sizeof(struct sockaddr_in);
170 d.sin_addr = ip->ip_dst;
171
172 match = NULL;
173 matchprio = 0;
174 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
175 if (ep->af != AF_INET)
176 continue;
177 if (ep->proto >= 0 && ep->proto != proto)
178 continue;
179 if (ep->func)
180 prio = (*ep->func)(m, off, proto, ep->arg);
181 else {
182 /*
183 * it's inbound traffic, we need to match in reverse
184 * order
185 */
186 prio = mask_match(ep,
187 (struct sockaddr *)&d,
188 (struct sockaddr *)&s);
189 }
190
191 /*
192 * We prioritize the matches by using bit length of the
193 * matches. mask_match() and user-supplied matching function
194 * should return the bit length of the matches (for example,
195 * if both src/dst are matched for IPv4, 64 should be returned).
196 * 0 or negative return value means "it did not match".
197 *
198 * The question is, since we have two "mask" portion, we
199 * cannot really define total order between entries.
200 * For example, which of these should be preferred?
201 * mask_match() returns 48 (32 + 16) for both of them.
202 * src=3ffe::/16, dst=3ffe:501::/32
203 * src=3ffe:501::/32, dst=3ffe::/16
204 *
205 * We need to loop through all the possible candidates
206 * to get the best match - the search takes O(n) for
207 * n attachments (i.e. interfaces).
208 */
209 if (prio <= 0)
210 continue;
211 if (prio > matchprio) {
212 matchprio = prio;
213 match = ep;
214 }
215 }
216
217 if (match) {
218 /* found a match, "match" has the best one */
219 psw = match->psw;
220 if (psw && psw->pr_input) {
221 encap_fillarg(m, match);
222 *mp = m;
223 (*psw->pr_input)(mp, offp, proto);
224 } else {
225 m_freem(m);
226 }
227 return(IPPROTO_DONE);
228 }
229
230 /* for backward compatibility */
231 if (proto == IPPROTO_IPV4 && ipip_input) {
232 *mp = m;
233 ipip_input(mp, offp, proto);
234 return(IPPROTO_DONE);
235 }
236
237 /* last resort: inject to raw socket */
238 *mp = m;
239 rip_input(mp, offp, proto);
240 return(IPPROTO_DONE);
241 }
242 #endif
243
244 #ifdef INET6
245 int
encap6_input(struct mbuf ** mp,int * offp,int proto)246 encap6_input(struct mbuf **mp, int *offp, int proto)
247 {
248 struct mbuf *m = *mp;
249 struct ip6_hdr *ip6;
250 struct sockaddr_in6 s, d;
251 const struct protosw *psw;
252 struct encaptab *ep, *match;
253 int prio, matchprio;
254
255 ip6 = mtod(m, struct ip6_hdr *);
256
257 bzero(&s, sizeof s);
258 s.sin6_family = AF_INET6;
259 s.sin6_len = sizeof(struct sockaddr_in6);
260 s.sin6_addr = ip6->ip6_src;
261 bzero(&d, sizeof d);
262 d.sin6_family = AF_INET6;
263 d.sin6_len = sizeof(struct sockaddr_in6);
264 d.sin6_addr = ip6->ip6_dst;
265
266 match = NULL;
267 matchprio = 0;
268 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
269 if (ep->af != AF_INET6)
270 continue;
271 if (ep->proto >= 0 && ep->proto != proto)
272 continue;
273 if (ep->func)
274 prio = (*ep->func)(m, *offp, proto, ep->arg);
275 else {
276 /*
277 * it's inbound traffic, we need to match in reverse
278 * order
279 */
280 prio = mask_match(ep, (struct sockaddr *)&d,
281 (struct sockaddr *)&s);
282 }
283
284 /* see encap4_input() for issues here */
285 if (prio <= 0)
286 continue;
287 if (prio > matchprio) {
288 matchprio = prio;
289 match = ep;
290 }
291 }
292
293 if (match) {
294 /* found a match */
295 psw = match->psw;
296 if (psw && psw->pr_input) {
297 encap_fillarg(m, match);
298 return (*psw->pr_input)(mp, offp, proto);
299 } else {
300 m_freem(m);
301 return IPPROTO_DONE;
302 }
303 }
304
305 /* last resort: inject to raw socket */
306 return rip6_input(mp, offp, proto);
307 }
308 #endif
309
310 static void
encap_add(struct encaptab * ep)311 encap_add(struct encaptab *ep)
312 {
313
314 LIST_INSERT_HEAD(&encaptab, ep, chain);
315 }
316
317 /*
318 * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
319 * length of mask (sm and dm) is assumed to be same as sp/dp.
320 * Return value will be necessary as input (cookie) for encap_detach().
321 */
322 const struct encaptab *
encap_attach(int af,int proto,const struct sockaddr * sp,const struct sockaddr * sm,const struct sockaddr * dp,const struct sockaddr * dm,const struct protosw * psw,void * arg)323 encap_attach(int af, int proto, const struct sockaddr *sp,
324 const struct sockaddr *sm, const struct sockaddr *dp,
325 const struct sockaddr *dm, const struct protosw *psw, void *arg)
326 {
327 struct encaptab *ep;
328
329 crit_enter();
330 /* sanity check on args */
331 if (sp->sa_len > sizeof ep->src || dp->sa_len > sizeof ep->dst)
332 goto fail;
333 if (sp->sa_len != dp->sa_len)
334 goto fail;
335 if (af != sp->sa_family || af != dp->sa_family)
336 goto fail;
337
338 /* check if anyone have already attached with exactly same config */
339 for (ep = LIST_FIRST(&encaptab); ep; ep = LIST_NEXT(ep, chain)) {
340 if (ep->af != af)
341 continue;
342 if (ep->proto != proto)
343 continue;
344 if (ep->src.ss_len != sp->sa_len ||
345 bcmp(&ep->src, sp, sp->sa_len) != 0 ||
346 bcmp(&ep->srcmask, sm, sp->sa_len) != 0)
347 continue;
348 if (ep->dst.ss_len != dp->sa_len ||
349 bcmp(&ep->dst, dp, dp->sa_len) != 0 ||
350 bcmp(&ep->dstmask, dm, dp->sa_len) != 0)
351 continue;
352
353 goto fail;
354 }
355
356 ep = kmalloc(sizeof *ep, M_IPENCAP, M_INTWAIT | M_ZERO | M_NULLOK);
357 if (ep == NULL)
358 goto fail;
359
360 ep->af = af;
361 ep->proto = proto;
362 bcopy(sp, &ep->src, sp->sa_len);
363 bcopy(sm, &ep->srcmask, sp->sa_len);
364 bcopy(dp, &ep->dst, dp->sa_len);
365 bcopy(dm, &ep->dstmask, dp->sa_len);
366 ep->psw = psw;
367 ep->arg = arg;
368
369 encap_add(ep);
370
371 crit_exit();
372 return ep;
373
374 fail:
375 crit_exit();
376 return NULL;
377 }
378
379 const struct encaptab *
encap_attach_func(int af,int proto,int (* func)(const struct mbuf *,int,int,void *),const struct protosw * psw,void * arg)380 encap_attach_func(int af, int proto,
381 int (*func)(const struct mbuf *, int, int, void *),
382 const struct protosw *psw, void *arg)
383 {
384 struct encaptab *ep;
385
386 crit_enter();
387 /* sanity check on args */
388 if (!func)
389 goto fail;
390
391 ep = kmalloc(sizeof *ep, M_IPENCAP, M_INTWAIT | M_ZERO | M_NULLOK);
392 if (ep == NULL)
393 goto fail;
394
395 ep->af = af;
396 ep->proto = proto;
397 ep->func = func;
398 ep->psw = psw;
399 ep->arg = arg;
400
401 encap_add(ep);
402
403 crit_exit();
404 return ep;
405
406 fail:
407 crit_exit();
408 return NULL;
409 }
410
411 int
encap_detach(const struct encaptab * cookie)412 encap_detach(const struct encaptab *cookie)
413 {
414 const struct encaptab *ep = cookie;
415 struct encaptab *p;
416
417 for (p = LIST_FIRST(&encaptab); p; p = LIST_NEXT(p, chain)) {
418 if (p == ep) {
419 LIST_REMOVE(p, chain);
420 kfree(p, M_IPENCAP); /*XXX*/
421 return 0;
422 }
423 }
424
425 return EINVAL;
426 }
427
428 static int
mask_match(const struct encaptab * ep,const struct sockaddr * sp,const struct sockaddr * dp)429 mask_match(const struct encaptab *ep, const struct sockaddr *sp,
430 const struct sockaddr *dp)
431 {
432 struct sockaddr_storage s;
433 struct sockaddr_storage d;
434 int i;
435 const u_int8_t *p, *q;
436 u_int8_t *r;
437 int matchlen;
438
439 if (sp->sa_len > sizeof s || dp->sa_len > sizeof d)
440 return 0;
441 if (sp->sa_family != ep->af || dp->sa_family != ep->af)
442 return 0;
443 if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len)
444 return 0;
445
446 matchlen = 0;
447
448 p = (const u_int8_t *)sp;
449 q = (const u_int8_t *)&ep->srcmask;
450 r = (u_int8_t *)&s;
451 for (i = 0 ; i < sp->sa_len; i++) {
452 r[i] = p[i] & q[i];
453 /* XXX estimate */
454 matchlen += (q[i] ? 8 : 0);
455 }
456
457 p = (const u_int8_t *)dp;
458 q = (const u_int8_t *)&ep->dstmask;
459 r = (u_int8_t *)&d;
460 for (i = 0 ; i < dp->sa_len; i++) {
461 r[i] = p[i] & q[i];
462 /* XXX rough estimate */
463 matchlen += (q[i] ? 8 : 0);
464 }
465
466 /* need to overwrite len/family portion as we don't compare them */
467 s.ss_len = sp->sa_len;
468 s.ss_family = sp->sa_family;
469 d.ss_len = dp->sa_len;
470 d.ss_family = dp->sa_family;
471
472 if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 &&
473 bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) {
474 return matchlen;
475 } else
476 return 0;
477 }
478
479 static void
encap_fillarg(struct mbuf * m,const struct encaptab * ep)480 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
481 {
482 struct m_tag *tag;
483
484 tag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), M_NOWAIT);
485 if (tag != NULL) {
486 *(void **)m_tag_data(tag) = ep->arg;
487 m_tag_prepend(m, tag);
488 }
489 }
490
491 void *
encap_getarg(struct mbuf * m)492 encap_getarg(struct mbuf *m)
493 {
494 void *p = NULL;
495 struct m_tag *tag;
496
497 tag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
498 if (tag != NULL) {
499 p = *(void **)m_tag_data(tag);
500 m_tag_delete(m, tag);
501 }
502 return p;
503 }
504