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1 /*
2  * EAP-IKEv2 peer (RFC 5106)
3  * Copyright (c) 2007-2014, Jouni Malinen <j@w1.fi>
4  *
5  * This software may be distributed under the terms of the BSD license.
6  * See README for more details.
7  */
8 
9 #include "includes.h"
10 
11 #include "common.h"
12 #include "eap_i.h"
13 #include "eap_common/eap_ikev2_common.h"
14 #include "ikev2.h"
15 
16 
17 struct eap_ikev2_data {
18 	struct ikev2_responder_data ikev2;
19 	enum { WAIT_START, PROC_MSG, WAIT_FRAG_ACK, DONE, FAIL } state;
20 	struct wpabuf *in_buf;
21 	struct wpabuf *out_buf;
22 	size_t out_used;
23 	size_t fragment_size;
24 	int keys_ready;
25 	u8 keymat[EAP_MSK_LEN + EAP_EMSK_LEN];
26 	int keymat_ok;
27 };
28 
29 
eap_ikev2_state_txt(int state)30 static const char * eap_ikev2_state_txt(int state)
31 {
32 	switch (state) {
33 	case WAIT_START:
34 		return "WAIT_START";
35 	case PROC_MSG:
36 		return "PROC_MSG";
37 	case WAIT_FRAG_ACK:
38 		return "WAIT_FRAG_ACK";
39 	case DONE:
40 		return "DONE";
41 	case FAIL:
42 		return "FAIL";
43 	default:
44 		return "?";
45 	}
46 }
47 
48 
eap_ikev2_state(struct eap_ikev2_data * data,int state)49 static void eap_ikev2_state(struct eap_ikev2_data *data, int state)
50 {
51 	wpa_printf(MSG_DEBUG, "EAP-IKEV2: %s -> %s",
52 		   eap_ikev2_state_txt(data->state),
53 		   eap_ikev2_state_txt(state));
54 	data->state = state;
55 }
56 
57 
eap_ikev2_init(struct eap_sm * sm)58 static void * eap_ikev2_init(struct eap_sm *sm)
59 {
60 	struct eap_ikev2_data *data;
61 	const u8 *identity, *password;
62 	size_t identity_len, password_len;
63 	int fragment_size;
64 
65 	identity = eap_get_config_identity(sm, &identity_len);
66 	if (identity == NULL) {
67 		wpa_printf(MSG_INFO, "EAP-IKEV2: No identity available");
68 		return NULL;
69 	}
70 
71 	data = os_zalloc(sizeof(*data));
72 	if (data == NULL)
73 		return NULL;
74 	data->state = WAIT_START;
75 	fragment_size = eap_get_config_fragment_size(sm);
76 	if (fragment_size <= 0)
77 		data->fragment_size = IKEV2_FRAGMENT_SIZE;
78 	else
79 		data->fragment_size = fragment_size;
80 	data->ikev2.state = SA_INIT;
81 	data->ikev2.peer_auth = PEER_AUTH_SECRET;
82 	data->ikev2.key_pad = (u8 *) os_strdup("Key Pad for EAP-IKEv2");
83 	if (data->ikev2.key_pad == NULL)
84 		goto failed;
85 	data->ikev2.key_pad_len = 21;
86 	data->ikev2.IDr = os_malloc(identity_len);
87 	if (data->ikev2.IDr == NULL)
88 		goto failed;
89 	os_memcpy(data->ikev2.IDr, identity, identity_len);
90 	data->ikev2.IDr_len = identity_len;
91 
92 	password = eap_get_config_password(sm, &password_len);
93 	if (password) {
94 		data->ikev2.shared_secret = os_malloc(password_len);
95 		if (data->ikev2.shared_secret == NULL)
96 			goto failed;
97 		os_memcpy(data->ikev2.shared_secret, password, password_len);
98 		data->ikev2.shared_secret_len = password_len;
99 	}
100 
101 	return data;
102 
103 failed:
104 	ikev2_responder_deinit(&data->ikev2);
105 	os_free(data);
106 	return NULL;
107 }
108 
109 
eap_ikev2_deinit(struct eap_sm * sm,void * priv)110 static void eap_ikev2_deinit(struct eap_sm *sm, void *priv)
111 {
112 	struct eap_ikev2_data *data = priv;
113 	wpabuf_free(data->in_buf);
114 	wpabuf_free(data->out_buf);
115 	ikev2_responder_deinit(&data->ikev2);
116 	bin_clear_free(data, sizeof(*data));
117 }
118 
119 
eap_ikev2_peer_keymat(struct eap_ikev2_data * data)120 static int eap_ikev2_peer_keymat(struct eap_ikev2_data *data)
121 {
122 	if (eap_ikev2_derive_keymat(
123 		    data->ikev2.proposal.prf, &data->ikev2.keys,
124 		    data->ikev2.i_nonce, data->ikev2.i_nonce_len,
125 		    data->ikev2.r_nonce, data->ikev2.r_nonce_len,
126 		    data->keymat) < 0) {
127 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to "
128 			   "derive key material");
129 		return -1;
130 	}
131 	data->keymat_ok = 1;
132 	return 0;
133 }
134 
135 
eap_ikev2_build_msg(struct eap_ikev2_data * data,struct eap_method_ret * ret,u8 id)136 static struct wpabuf * eap_ikev2_build_msg(struct eap_ikev2_data *data,
137 					   struct eap_method_ret *ret, u8 id)
138 {
139 	struct wpabuf *resp;
140 	u8 flags;
141 	size_t send_len, plen, icv_len = 0;
142 
143 	ret->ignore = FALSE;
144 	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Generating Response");
145 	ret->allowNotifications = TRUE;
146 
147 	flags = 0;
148 	send_len = wpabuf_len(data->out_buf) - data->out_used;
149 	if (1 + send_len > data->fragment_size) {
150 		send_len = data->fragment_size - 1;
151 		flags |= IKEV2_FLAGS_MORE_FRAGMENTS;
152 		if (data->out_used == 0) {
153 			flags |= IKEV2_FLAGS_LENGTH_INCLUDED;
154 			send_len -= 4;
155 		}
156 	}
157 
158 	plen = 1 + send_len;
159 	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
160 		plen += 4;
161 	if (data->keys_ready) {
162 		const struct ikev2_integ_alg *integ;
163 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Add Integrity Checksum "
164 			   "Data");
165 		flags |= IKEV2_FLAGS_ICV_INCLUDED;
166 		integ = ikev2_get_integ(data->ikev2.proposal.integ);
167 		if (integ == NULL) {
168 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unknown INTEG "
169 				   "transform / cannot generate ICV");
170 			return NULL;
171 		}
172 		icv_len = integ->hash_len;
173 
174 		plen += icv_len;
175 	}
176 	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, plen,
177 			     EAP_CODE_RESPONSE, id);
178 	if (resp == NULL)
179 		return NULL;
180 
181 	wpabuf_put_u8(resp, flags); /* Flags */
182 	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
183 		wpabuf_put_be32(resp, wpabuf_len(data->out_buf));
184 
185 	wpabuf_put_data(resp, wpabuf_head_u8(data->out_buf) + data->out_used,
186 			send_len);
187 	data->out_used += send_len;
188 
189 	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
190 		const u8 *msg = wpabuf_head(resp);
191 		size_t len = wpabuf_len(resp);
192 		ikev2_integ_hash(data->ikev2.proposal.integ,
193 				 data->ikev2.keys.SK_ar,
194 				 data->ikev2.keys.SK_integ_len,
195 				 msg, len, wpabuf_put(resp, icv_len));
196 	}
197 
198 	ret->methodState = METHOD_MAY_CONT;
199 	ret->decision = DECISION_FAIL;
200 
201 	if (data->out_used == wpabuf_len(data->out_buf)) {
202 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
203 			   "(message sent completely)",
204 			   (unsigned long) send_len);
205 		wpabuf_free(data->out_buf);
206 		data->out_buf = NULL;
207 		data->out_used = 0;
208 		switch (data->ikev2.state) {
209 		case SA_AUTH:
210 			/* SA_INIT was sent out, so message have to be
211 			 * integrity protected from now on. */
212 			data->keys_ready = 1;
213 			break;
214 		case IKEV2_DONE:
215 			ret->methodState = METHOD_DONE;
216 			if (data->state == FAIL)
217 				break;
218 			ret->decision = DECISION_COND_SUCC;
219 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication "
220 				   "completed successfully");
221 			if (eap_ikev2_peer_keymat(data))
222 				break;
223 			eap_ikev2_state(data, DONE);
224 			break;
225 		case IKEV2_FAILED:
226 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication "
227 				   "failed");
228 			ret->methodState = METHOD_DONE;
229 			ret->decision = DECISION_FAIL;
230 			break;
231 		default:
232 			break;
233 		}
234 	} else {
235 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
236 			   "(%lu more to send)", (unsigned long) send_len,
237 			   (unsigned long) wpabuf_len(data->out_buf) -
238 			   data->out_used);
239 		eap_ikev2_state(data, WAIT_FRAG_ACK);
240 	}
241 
242 	return resp;
243 }
244 
245 
eap_ikev2_process_icv(struct eap_ikev2_data * data,const struct wpabuf * reqData,u8 flags,const u8 * pos,const u8 ** end,int frag_ack)246 static int eap_ikev2_process_icv(struct eap_ikev2_data *data,
247 				 const struct wpabuf *reqData,
248 				 u8 flags, const u8 *pos, const u8 **end,
249 				 int frag_ack)
250 {
251 	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
252 		int icv_len = eap_ikev2_validate_icv(
253 			data->ikev2.proposal.integ, &data->ikev2.keys, 1,
254 			reqData, pos, *end);
255 		if (icv_len < 0)
256 			return -1;
257 		/* Hide Integrity Checksum Data from further processing */
258 		*end -= icv_len;
259 	} else if (data->keys_ready && !frag_ack) {
260 		wpa_printf(MSG_INFO, "EAP-IKEV2: The message should have "
261 			   "included integrity checksum");
262 		return -1;
263 	}
264 
265 	return 0;
266 }
267 
268 
eap_ikev2_process_cont(struct eap_ikev2_data * data,const u8 * buf,size_t len)269 static int eap_ikev2_process_cont(struct eap_ikev2_data *data,
270 				  const u8 *buf, size_t len)
271 {
272 	/* Process continuation of a pending message */
273 	if (len > wpabuf_tailroom(data->in_buf)) {
274 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment overflow");
275 		eap_ikev2_state(data, FAIL);
276 		return -1;
277 	}
278 
279 	wpabuf_put_data(data->in_buf, buf, len);
280 	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes, waiting "
281 		   "for %lu bytes more", (unsigned long) len,
282 		   (unsigned long) wpabuf_tailroom(data->in_buf));
283 
284 	return 0;
285 }
286 
287 
eap_ikev2_process_fragment(struct eap_ikev2_data * data,struct eap_method_ret * ret,u8 id,u8 flags,u32 message_length,const u8 * buf,size_t len)288 static struct wpabuf * eap_ikev2_process_fragment(struct eap_ikev2_data *data,
289 						  struct eap_method_ret *ret,
290 						  u8 id, u8 flags,
291 						  u32 message_length,
292 						  const u8 *buf, size_t len)
293 {
294 	/* Process a fragment that is not the last one of the message */
295 	if (data->in_buf == NULL && !(flags & IKEV2_FLAGS_LENGTH_INCLUDED)) {
296 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: No Message Length field in "
297 			   "a fragmented packet");
298 		ret->ignore = TRUE;
299 		return NULL;
300 	}
301 
302 	if (data->in_buf == NULL) {
303 		/* First fragment of the message */
304 		if (message_length > 50000) {
305 			/* Limit maximum memory allocation */
306 			wpa_printf(MSG_DEBUG,
307 				   "EAP-IKEV2: Ignore too long message");
308 			ret->ignore = TRUE;
309 			return NULL;
310 		}
311 		data->in_buf = wpabuf_alloc(message_length);
312 		if (data->in_buf == NULL) {
313 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: No memory for "
314 				   "message");
315 			ret->ignore = TRUE;
316 			return NULL;
317 		}
318 		wpabuf_put_data(data->in_buf, buf, len);
319 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes in first "
320 			   "fragment, waiting for %lu bytes more",
321 			   (unsigned long) len,
322 			   (unsigned long) wpabuf_tailroom(data->in_buf));
323 	}
324 
325 	ret->ignore = FALSE;
326 	return eap_ikev2_build_frag_ack(id, EAP_CODE_RESPONSE);
327 }
328 
329 
eap_ikev2_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)330 static struct wpabuf * eap_ikev2_process(struct eap_sm *sm, void *priv,
331 					 struct eap_method_ret *ret,
332 					 const struct wpabuf *reqData)
333 {
334 	struct eap_ikev2_data *data = priv;
335 	const u8 *start, *pos, *end;
336 	size_t len;
337 	u8 flags, id;
338 	u32 message_length = 0;
339 	struct wpabuf tmpbuf;
340 
341 	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, reqData, &len);
342 	if (pos == NULL) {
343 		ret->ignore = TRUE;
344 		return NULL;
345 	}
346 
347 	id = eap_get_id(reqData);
348 
349 	start = pos;
350 	end = start + len;
351 
352 	if (len == 0)
353 		flags = 0; /* fragment ack */
354 	else
355 		flags = *pos++;
356 
357 	if (eap_ikev2_process_icv(data, reqData, flags, pos, &end,
358 				  data->state == WAIT_FRAG_ACK && len == 0) < 0)
359 	{
360 		ret->ignore = TRUE;
361 		return NULL;
362 	}
363 
364 	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED) {
365 		if (end - pos < 4) {
366 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Message underflow");
367 			ret->ignore = TRUE;
368 			return NULL;
369 		}
370 		message_length = WPA_GET_BE32(pos);
371 		pos += 4;
372 
373 		if (message_length < (u32) (end - pos)) {
374 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Invalid Message "
375 				   "Length (%d; %ld remaining in this msg)",
376 				   message_length, (long) (end - pos));
377 			ret->ignore = TRUE;
378 			return NULL;
379 		}
380 	}
381 
382 	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received packet: Flags 0x%x "
383 		   "Message Length %u", flags, message_length);
384 
385 	if (data->state == WAIT_FRAG_ACK) {
386 		if (len != 0) {
387 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected payload "
388 				   "in WAIT_FRAG_ACK state");
389 			ret->ignore = TRUE;
390 			return NULL;
391 		}
392 		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment acknowledged");
393 		eap_ikev2_state(data, PROC_MSG);
394 		return eap_ikev2_build_msg(data, ret, id);
395 	}
396 
397 	if (data->in_buf && eap_ikev2_process_cont(data, pos, end - pos) < 0) {
398 		ret->ignore = TRUE;
399 		return NULL;
400 	}
401 
402 	if (flags & IKEV2_FLAGS_MORE_FRAGMENTS) {
403 		return eap_ikev2_process_fragment(data, ret, id, flags,
404 						  message_length, pos,
405 						  end - pos);
406 	}
407 
408 	if (data->in_buf == NULL) {
409 		/* Wrap unfragmented messages as wpabuf without extra copy */
410 		wpabuf_set(&tmpbuf, pos, end - pos);
411 		data->in_buf = &tmpbuf;
412 	}
413 
414 	if (ikev2_responder_process(&data->ikev2, data->in_buf) < 0) {
415 		if (data->in_buf == &tmpbuf)
416 			data->in_buf = NULL;
417 		eap_ikev2_state(data, FAIL);
418 		return NULL;
419 	}
420 
421 	if (data->in_buf != &tmpbuf)
422 		wpabuf_free(data->in_buf);
423 	data->in_buf = NULL;
424 
425 	if (data->out_buf == NULL) {
426 		data->out_buf = ikev2_responder_build(&data->ikev2);
427 		if (data->out_buf == NULL) {
428 			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to generate "
429 				   "IKEv2 message");
430 			return NULL;
431 		}
432 		data->out_used = 0;
433 	}
434 
435 	eap_ikev2_state(data, PROC_MSG);
436 	return eap_ikev2_build_msg(data, ret, id);
437 }
438 
439 
eap_ikev2_isKeyAvailable(struct eap_sm * sm,void * priv)440 static Boolean eap_ikev2_isKeyAvailable(struct eap_sm *sm, void *priv)
441 {
442 	struct eap_ikev2_data *data = priv;
443 	return data->state == DONE && data->keymat_ok;
444 }
445 
446 
eap_ikev2_getKey(struct eap_sm * sm,void * priv,size_t * len)447 static u8 * eap_ikev2_getKey(struct eap_sm *sm, void *priv, size_t *len)
448 {
449 	struct eap_ikev2_data *data = priv;
450 	u8 *key;
451 
452 	if (data->state != DONE || !data->keymat_ok)
453 		return NULL;
454 
455 	key = os_malloc(EAP_MSK_LEN);
456 	if (key) {
457 		os_memcpy(key, data->keymat, EAP_MSK_LEN);
458 		*len = EAP_MSK_LEN;
459 	}
460 
461 	return key;
462 }
463 
464 
eap_ikev2_get_emsk(struct eap_sm * sm,void * priv,size_t * len)465 static u8 * eap_ikev2_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
466 {
467 	struct eap_ikev2_data *data = priv;
468 	u8 *key;
469 
470 	if (data->state != DONE || !data->keymat_ok)
471 		return NULL;
472 
473 	key = os_malloc(EAP_EMSK_LEN);
474 	if (key) {
475 		os_memcpy(key, data->keymat + EAP_MSK_LEN, EAP_EMSK_LEN);
476 		*len = EAP_EMSK_LEN;
477 	}
478 
479 	return key;
480 }
481 
482 
eap_ikev2_get_session_id(struct eap_sm * sm,void * priv,size_t * len)483 static u8 * eap_ikev2_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
484 {
485 	struct eap_ikev2_data *data = priv;
486 	u8 *sid;
487 	size_t sid_len;
488 	size_t offset;
489 
490 	if (data->state != DONE || !data->keymat_ok)
491 		return NULL;
492 
493 	sid_len = 1 + data->ikev2.i_nonce_len + data->ikev2.r_nonce_len;
494 	sid = os_malloc(sid_len);
495 	if (sid) {
496 		offset = 0;
497 		sid[offset] = EAP_TYPE_IKEV2;
498 		offset++;
499 		os_memcpy(sid + offset, data->ikev2.i_nonce,
500 			  data->ikev2.i_nonce_len);
501 		offset += data->ikev2.i_nonce_len;
502 		os_memcpy(sid + offset, data->ikev2.r_nonce,
503 			  data->ikev2.r_nonce_len);
504 		*len = sid_len;
505 		wpa_hexdump(MSG_DEBUG, "EAP-IKEV2: Derived Session-Id",
506 			    sid, sid_len);
507 	}
508 
509 	return sid;
510 }
511 
512 
eap_peer_ikev2_register(void)513 int eap_peer_ikev2_register(void)
514 {
515 	struct eap_method *eap;
516 
517 	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
518 				    EAP_VENDOR_IETF, EAP_TYPE_IKEV2,
519 				    "IKEV2");
520 	if (eap == NULL)
521 		return -1;
522 
523 	eap->init = eap_ikev2_init;
524 	eap->deinit = eap_ikev2_deinit;
525 	eap->process = eap_ikev2_process;
526 	eap->isKeyAvailable = eap_ikev2_isKeyAvailable;
527 	eap->getKey = eap_ikev2_getKey;
528 	eap->get_emsk = eap_ikev2_get_emsk;
529 	eap->getSessionId = eap_ikev2_get_session_id;
530 
531 	return eap_peer_method_register(eap);
532 }
533