libhydra: Move kernel interface to libcharon
[strongswan.git] / src / libcharon / sa / ikev2 / tasks / ike_natd.c
1 /*
2 * Copyright (C) 2006-2007 Martin Willi
3 * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
4 * Hochschule fuer Technik Rapperswil
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2 of the License, or (at your
9 * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * for more details.
15 */
16
17 #include "ike_natd.h"
18
19 #include <string.h>
20
21 #include <daemon.h>
22 #include <config/peer_cfg.h>
23 #include <crypto/hashers/hasher.h>
24 #include <encoding/payloads/notify_payload.h>
25
26
27 typedef struct private_ike_natd_t private_ike_natd_t;
28
29 /**
30 * Private members of a ike_natd_t task.
31 */
32 struct private_ike_natd_t {
33
34 /**
35 * Public methods and task_t interface.
36 */
37 ike_natd_t public;
38
39 /**
40 * Assigned IKE_SA.
41 */
42 ike_sa_t *ike_sa;
43
44 /**
45 * Are we the initiator?
46 */
47 bool initiator;
48
49 /**
50 * Hasher used to build NAT detection hashes
51 */
52 hasher_t *hasher;
53
54 /**
55 * Did we process any NAT detection notifys for a source address?
56 */
57 bool src_seen;
58
59 /**
60 * Did we process any NAT detection notifys for a destination address?
61 */
62 bool dst_seen;
63
64 /**
65 * Have we found a matching source address NAT hash?
66 */
67 bool src_matched;
68
69 /**
70 * Have we found a matching destination address NAT hash?
71 */
72 bool dst_matched;
73
74 /**
75 * whether NAT mappings for our NATed address has changed
76 */
77 bool mapping_changed;
78 };
79
80 /**
81 * Check if UDP encapsulation has to be forced either by config or required
82 * by the kernel interface
83 */
84 static bool force_encap(ike_cfg_t *ike_cfg)
85 {
86 if (!ike_cfg->force_encap(ike_cfg))
87 {
88 return charon->kernel->get_features(charon->kernel) &
89 KERNEL_REQUIRE_UDP_ENCAPSULATION;
90 }
91 return TRUE;
92 }
93
94 /**
95 * Build NAT detection hash for a host
96 */
97 static chunk_t generate_natd_hash(private_ike_natd_t *this,
98 ike_sa_id_t *ike_sa_id, host_t *host)
99 {
100 chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk;
101 chunk_t natd_hash;
102 u_int64_t spi_i, spi_r;
103 u_int16_t port;
104
105 /* prepare all required chunks */
106 spi_i = ike_sa_id->get_initiator_spi(ike_sa_id);
107 spi_r = ike_sa_id->get_responder_spi(ike_sa_id);
108 spi_i_chunk.ptr = (void*)&spi_i;
109 spi_i_chunk.len = sizeof(spi_i);
110 spi_r_chunk.ptr = (void*)&spi_r;
111 spi_r_chunk.len = sizeof(spi_r);
112 port = htons(host->get_port(host));
113 port_chunk.ptr = (void*)&port;
114 port_chunk.len = sizeof(port);
115 addr_chunk = host->get_address(host);
116
117 /* natd_hash = SHA1( spi_i | spi_r | address | port ) */
118 natd_chunk = chunk_cat("cccc", spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk);
119 if (!this->hasher->allocate_hash(this->hasher, natd_chunk, &natd_hash))
120 {
121 natd_hash = chunk_empty;
122 }
123 DBG3(DBG_IKE, "natd_chunk %B", &natd_chunk);
124 DBG3(DBG_IKE, "natd_hash %B", &natd_hash);
125
126 chunk_free(&natd_chunk);
127 return natd_hash;
128 }
129
130 /**
131 * Build a NAT detection notify payload.
132 */
133 static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
134 notify_type_t type, host_t *host)
135 {
136 chunk_t hash;
137 notify_payload_t *notify;
138 ike_sa_id_t *ike_sa_id;
139 ike_cfg_t *config;
140
141 ike_sa_id = this->ike_sa->get_id(this->ike_sa);
142 config = this->ike_sa->get_ike_cfg(this->ike_sa);
143 if (force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
144 {
145 u_int32_t addr;
146
147 /* chunk_hash() is randomly keyed so this produces a random IPv4 address
148 * that changes with every restart but otherwise stays the same */
149 addr = chunk_hash(chunk_from_chars(0x00, 0x00, 0x00, 0x00));
150 host = host_create_from_chunk(AF_INET, chunk_from_thing(addr), 0);
151 hash = generate_natd_hash(this, ike_sa_id, host);
152 host->destroy(host);
153 }
154 else
155 {
156 hash = generate_natd_hash(this, ike_sa_id, host);
157 }
158 if (!hash.len)
159 {
160 return NULL;
161 }
162 notify = notify_payload_create(PLV2_NOTIFY);
163 notify->set_notify_type(notify, type);
164 notify->set_notification_data(notify, hash);
165 chunk_free(&hash);
166
167 return notify;
168 }
169
170 /**
171 * read notifys from message and evaluate them
172 */
173 static void process_payloads(private_ike_natd_t *this, message_t *message)
174 {
175 enumerator_t *enumerator;
176 payload_t *payload;
177 notify_payload_t *notify;
178 chunk_t hash, src_hash, dst_hash;
179 ike_sa_id_t *ike_sa_id;
180 host_t *me, *other;
181 ike_cfg_t *config;
182
183 /* Precompute NAT-D hashes for incoming NAT notify comparison */
184 ike_sa_id = message->get_ike_sa_id(message);
185 me = message->get_destination(message);
186 other = message->get_source(message);
187 dst_hash = generate_natd_hash(this, ike_sa_id, me);
188 src_hash = generate_natd_hash(this, ike_sa_id, other);
189
190 DBG3(DBG_IKE, "precalculated src_hash %B", &src_hash);
191 DBG3(DBG_IKE, "precalculated dst_hash %B", &dst_hash);
192
193 enumerator = message->create_payload_enumerator(message);
194 while (enumerator->enumerate(enumerator, &payload))
195 {
196 if (payload->get_type(payload) != PLV2_NOTIFY)
197 {
198 continue;
199 }
200 notify = (notify_payload_t*)payload;
201 switch (notify->get_notify_type(notify))
202 {
203 case NAT_DETECTION_DESTINATION_IP:
204 {
205 this->dst_seen = TRUE;
206 hash = notify->get_notification_data(notify);
207 if (!this->dst_matched)
208 {
209 DBG3(DBG_IKE, "received dst_hash %B", &hash);
210 if (chunk_equals(hash, dst_hash))
211 {
212 this->dst_matched = TRUE;
213 }
214 }
215 /* RFC4555 says we should also compare against IKE_SA_INIT
216 * NATD payloads, but this does not work: We are running
217 * there at port 500, but use 4500 afterwards... */
218 if (message->get_exchange_type(message) == INFORMATIONAL &&
219 this->initiator && !this->dst_matched)
220 {
221 this->mapping_changed = this->ike_sa->has_mapping_changed(
222 this->ike_sa, hash);
223 }
224 break;
225 }
226 case NAT_DETECTION_SOURCE_IP:
227 {
228 this->src_seen = TRUE;
229 if (!this->src_matched)
230 {
231 hash = notify->get_notification_data(notify);
232 DBG3(DBG_IKE, "received src_hash %B", &hash);
233 if (chunk_equals(hash, src_hash))
234 {
235 this->src_matched = TRUE;
236 }
237 }
238 break;
239 }
240 default:
241 break;
242 }
243 }
244 enumerator->destroy(enumerator);
245
246 chunk_free(&src_hash);
247 chunk_free(&dst_hash);
248
249 if (this->src_seen && this->dst_seen)
250 {
251 this->ike_sa->enable_extension(this->ike_sa, EXT_NATT);
252
253 this->ike_sa->set_condition(this->ike_sa, COND_NAT_HERE,
254 !this->dst_matched);
255 this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE,
256 !this->src_matched);
257 config = this->ike_sa->get_ike_cfg(this->ike_sa);
258 if (this->dst_matched && this->src_matched &&
259 force_encap(config))
260 {
261 this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE);
262 }
263 }
264 }
265
266 METHOD(task_t, process_i, status_t,
267 private_ike_natd_t *this, message_t *message)
268 {
269 process_payloads(this, message);
270
271 if (message->get_exchange_type(message) == IKE_SA_INIT)
272 {
273 peer_cfg_t *peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
274 if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY) ||
275 /* if peer supports NAT-T, we switch to port 4500 even
276 * if no NAT is detected. can't be done later (when we would know
277 * whether the peer supports MOBIKE) because there would be no
278 * exchange to actually do the switch (other than a forced DPD). */
279 (peer_cfg->use_mobike(peer_cfg) &&
280 this->ike_sa->supports_extension(this->ike_sa, EXT_NATT)))
281 {
282 this->ike_sa->float_ports(this->ike_sa);
283 }
284 }
285
286 return SUCCESS;
287 }
288
289 METHOD(task_t, build_i, status_t,
290 private_ike_natd_t *this, message_t *message)
291 {
292 notify_payload_t *notify;
293 enumerator_t *enumerator;
294 ike_cfg_t *ike_cfg;
295 host_t *host;
296
297 if (this->hasher == NULL)
298 {
299 DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
300 return NEED_MORE;
301 }
302
303 ike_cfg = this->ike_sa->get_ike_cfg(this->ike_sa);
304
305 /* destination is always set */
306 host = message->get_destination(message);
307 notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host);
308 if (notify)
309 {
310 message->add_payload(message, (payload_t*)notify);
311 }
312
313 /* source may be any, we have 3 possibilities to get our source address:
314 * 1. It is defined in the config => use the one of the IKE_SA
315 * 2. We do a routing lookup in the kernel interface
316 * 3. Include all possbile addresses
317 */
318 host = message->get_source(message);
319 if (!host->is_anyaddr(host) || force_encap(ike_cfg))
320 { /* 1. or if we force UDP encap, as it doesn't matter if it's %any */
321 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
322 if (notify)
323 {
324 message->add_payload(message, (payload_t*)notify);
325 }
326 }
327 else
328 {
329 host = charon->kernel->get_source_addr(charon->kernel,
330 this->ike_sa->get_other_host(this->ike_sa), NULL);
331 if (host)
332 { /* 2. */
333 host->set_port(host, ike_cfg->get_my_port(ike_cfg));
334 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
335 if (notify)
336 {
337 message->add_payload(message, (payload_t*)notify);
338 }
339 host->destroy(host);
340 }
341 else
342 { /* 3. */
343 enumerator = charon->kernel->create_address_enumerator(
344 charon->kernel, ADDR_TYPE_REGULAR);
345 while (enumerator->enumerate(enumerator, (void**)&host))
346 {
347 /* apply port 500 to host, but work on a copy */
348 host = host->clone(host);
349 host->set_port(host, ike_cfg->get_my_port(ike_cfg));
350 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
351 host->destroy(host);
352 if (notify)
353 {
354 message->add_payload(message, (payload_t*)notify);
355 }
356 }
357 enumerator->destroy(enumerator);
358 }
359 }
360 return NEED_MORE;
361 }
362
363 METHOD(task_t, build_r, status_t,
364 private_ike_natd_t *this, message_t *message)
365 {
366 notify_payload_t *notify;
367 host_t *me, *other;
368
369 /* only add notifies on successful responses. */
370 if (message->get_exchange_type(message) == IKE_SA_INIT &&
371 message->get_payload(message, PLV2_SECURITY_ASSOCIATION) == NULL)
372 {
373 return SUCCESS;
374 }
375
376 if (this->src_seen && this->dst_seen)
377 {
378 if (this->hasher == NULL)
379 {
380 DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
381 return SUCCESS;
382 }
383
384 /* initiator seems to support NAT detection, add response */
385 me = message->get_source(message);
386 notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, me);
387 if (notify)
388 {
389 message->add_payload(message, (payload_t*)notify);
390 }
391 other = message->get_destination(message);
392 notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, other);
393 if (notify)
394 {
395 message->add_payload(message, (payload_t*)notify);
396 }
397 }
398 return SUCCESS;
399 }
400
401 METHOD(task_t, process_r, status_t,
402 private_ike_natd_t *this, message_t *message)
403 {
404 process_payloads(this, message);
405
406 return NEED_MORE;
407 }
408
409 METHOD(task_t, get_type, task_type_t,
410 private_ike_natd_t *this)
411 {
412 return TASK_IKE_NATD;
413 }
414
415 METHOD(task_t, migrate, void,
416 private_ike_natd_t *this, ike_sa_t *ike_sa)
417 {
418 this->ike_sa = ike_sa;
419 this->src_seen = FALSE;
420 this->dst_seen = FALSE;
421 this->src_matched = FALSE;
422 this->dst_matched = FALSE;
423 this->mapping_changed = FALSE;
424 }
425
426 METHOD(task_t, destroy, void,
427 private_ike_natd_t *this)
428 {
429 DESTROY_IF(this->hasher);
430 free(this);
431 }
432
433 METHOD(ike_natd_t, has_mapping_changed, bool,
434 private_ike_natd_t *this)
435 {
436 return this->mapping_changed;
437 }
438
439 /*
440 * Described in header.
441 */
442 ike_natd_t *ike_natd_create(ike_sa_t *ike_sa, bool initiator)
443 {
444 private_ike_natd_t *this;
445
446 INIT(this,
447 .public = {
448 .task = {
449 .get_type = _get_type,
450 .migrate = _migrate,
451 .destroy = _destroy,
452 },
453 .has_mapping_changed = _has_mapping_changed,
454 },
455 .ike_sa = ike_sa,
456 .initiator = initiator,
457 .hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1),
458 );
459
460 if (initiator)
461 {
462 this->public.task.build = _build_i;
463 this->public.task.process = _process_i;
464 }
465 else
466 {
467 this->public.task.build = _build_r;
468 this->public.task.process = _process_r;
469 }
470
471 return &this->public;
472 }