eap_sake.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4 
1/*
2 * EAP peer method: EAP-SAKE (RFC 4763)
3 * Copyright (c) 2006-2008, 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 "crypto/random.h"
13#include "eap_peer/eap_i.h"
14#include "eap_common/eap_sake_common.h"
15
16struct eap_sake_data {
17	enum { IDENTITY, CHALLENGE, CONFIRM, SUCCESS, FAILURE } state;
18	u8 root_secret_a[EAP_SAKE_ROOT_SECRET_LEN];
19	u8 root_secret_b[EAP_SAKE_ROOT_SECRET_LEN];
20	u8 rand_s[EAP_SAKE_RAND_LEN];
21	u8 rand_p[EAP_SAKE_RAND_LEN];
22	struct {
23		u8 auth[EAP_SAKE_TEK_AUTH_LEN];
24		u8 cipher[EAP_SAKE_TEK_CIPHER_LEN];
25	} tek;
26	u8 msk[EAP_MSK_LEN];
27	u8 emsk[EAP_EMSK_LEN];
28	u8 session_id;
29	int session_id_set;
30	u8 *peerid;
31	size_t peerid_len;
32	u8 *serverid;
33	size_t serverid_len;
34};
35
36
37static const char * eap_sake_state_txt(int state)
38{
39	switch (state) {
40	case IDENTITY:
41		return "IDENTITY";
42	case CHALLENGE:
43		return "CHALLENGE";
44	case CONFIRM:
45		return "CONFIRM";
46	case SUCCESS:
47		return "SUCCESS";
48	case FAILURE:
49		return "FAILURE";
50	default:
51		return "?";
52	}
53}
54
55
56static void eap_sake_state(struct eap_sake_data *data, int state)
57{
58	wpa_printf(MSG_DEBUG, "EAP-SAKE: %s -> %s",
59		   eap_sake_state_txt(data->state),
60		   eap_sake_state_txt(state));
61	data->state = state;
62}
63
64
65static void eap_sake_deinit(struct eap_sm *sm, void *priv);
66
67
68static void * eap_sake_init(struct eap_sm *sm)
69{
70	struct eap_sake_data *data;
71	const u8 *identity, *password;
72	size_t identity_len, password_len;
73
74	password = eap_get_config_password(sm, &password_len);
75	if (!password || password_len != 2 * EAP_SAKE_ROOT_SECRET_LEN) {
76		wpa_printf(MSG_INFO, "EAP-SAKE: No key of correct length "
77			   "configured");
78		return NULL;
79	}
80
81	data = os_zalloc(sizeof(*data));
82	if (data == NULL)
83		return NULL;
84	data->state = IDENTITY;
85
86	identity = eap_get_config_identity(sm, &identity_len);
87	if (identity) {
88		data->peerid = os_malloc(identity_len);
89		if (data->peerid == NULL) {
90			eap_sake_deinit(sm, data);
91			return NULL;
92		}
93		os_memcpy(data->peerid, identity, identity_len);
94		data->peerid_len = identity_len;
95	}
96
97	os_memcpy(data->root_secret_a, password, EAP_SAKE_ROOT_SECRET_LEN);
98	os_memcpy(data->root_secret_b,
99		  password + EAP_SAKE_ROOT_SECRET_LEN,
100		  EAP_SAKE_ROOT_SECRET_LEN);
101
102	return data;
103}
104
105
106static void eap_sake_deinit(struct eap_sm *sm, void *priv)
107{
108	struct eap_sake_data *data = priv;
109	os_free(data->serverid);
110	os_free(data->peerid);
111	os_free(data);
112}
113
114
115static struct wpabuf * eap_sake_build_msg(struct eap_sake_data *data,
116					  int id, size_t length, u8 subtype)
117{
118	struct eap_sake_hdr *sake;
119	struct wpabuf *msg;
120	size_t plen;
121
122	plen = length + sizeof(struct eap_sake_hdr);
123
124	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_SAKE, plen,
125			    EAP_CODE_RESPONSE, id);
126	if (msg == NULL) {
127		wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to allocate memory "
128			   "request");
129		return NULL;
130	}
131
132	sake = wpabuf_put(msg, sizeof(*sake));
133	sake->version = EAP_SAKE_VERSION;
134	sake->session_id = data->session_id;
135	sake->subtype = subtype;
136
137	return msg;
138}
139
140
141static struct wpabuf * eap_sake_process_identity(struct eap_sm *sm,
142						 struct eap_sake_data *data,
143						 struct eap_method_ret *ret,
144						 const struct wpabuf *reqData,
145						 const u8 *payload,
146						 size_t payload_len)
147{
148	struct eap_sake_parse_attr attr;
149	struct wpabuf *resp;
150
151	if (data->state != IDENTITY) {
152		ret->ignore = TRUE;
153		return NULL;
154	}
155
156	wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Identity");
157
158	if (eap_sake_parse_attributes(payload, payload_len, &attr))
159		return NULL;
160
161	if (!attr.perm_id_req && !attr.any_id_req) {
162		wpa_printf(MSG_INFO, "EAP-SAKE: No AT_PERM_ID_REQ or "
163			   "AT_ANY_ID_REQ in Request/Identity");
164		return NULL;
165	}
166
167	wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Identity");
168
169	resp = eap_sake_build_msg(data, eap_get_id(reqData),
170				  2 + data->peerid_len,
171				  EAP_SAKE_SUBTYPE_IDENTITY);
172	if (resp == NULL)
173		return NULL;
174
175	wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_PEERID");
176	eap_sake_add_attr(resp, EAP_SAKE_AT_PEERID,
177			  data->peerid, data->peerid_len);
178
179	eap_sake_state(data, CHALLENGE);
180
181	return resp;
182}
183
184
185static struct wpabuf * eap_sake_process_challenge(struct eap_sm *sm,
186						  struct eap_sake_data *data,
187						  struct eap_method_ret *ret,
188						  const struct wpabuf *reqData,
189						  const u8 *payload,
190						  size_t payload_len)
191{
192	struct eap_sake_parse_attr attr;
193	struct wpabuf *resp;
194	u8 *rpos;
195	size_t rlen;
196
197	if (data->state != IDENTITY && data->state != CHALLENGE) {
198		wpa_printf(MSG_DEBUG, "EAP-SAKE: Request/Challenge received "
199			   "in unexpected state (%d)", data->state);
200		ret->ignore = TRUE;
201		return NULL;
202	}
203	if (data->state == IDENTITY)
204		eap_sake_state(data, CHALLENGE);
205
206	wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Challenge");
207
208	if (eap_sake_parse_attributes(payload, payload_len, &attr))
209		return NULL;
210
211	if (!attr.rand_s) {
212		wpa_printf(MSG_INFO, "EAP-SAKE: Request/Challenge did not "
213			   "include AT_RAND_S");
214		return NULL;
215	}
216
217	os_memcpy(data->rand_s, attr.rand_s, EAP_SAKE_RAND_LEN);
218	wpa_hexdump(MSG_MSGDUMP, "EAP-SAKE: RAND_S (server rand)",
219		    data->rand_s, EAP_SAKE_RAND_LEN);
220
221	if (random_get_bytes(data->rand_p, EAP_SAKE_RAND_LEN)) {
222		wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to get random data");
223		return NULL;
224	}
225	wpa_hexdump(MSG_MSGDUMP, "EAP-SAKE: RAND_P (peer rand)",
226		    data->rand_p, EAP_SAKE_RAND_LEN);
227
228	os_free(data->serverid);
229	data->serverid = NULL;
230	data->serverid_len = 0;
231	if (attr.serverid) {
232		wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-SAKE: SERVERID",
233				  attr.serverid, attr.serverid_len);
234		data->serverid = os_malloc(attr.serverid_len);
235		if (data->serverid == NULL)
236			return NULL;
237		os_memcpy(data->serverid, attr.serverid, attr.serverid_len);
238		data->serverid_len = attr.serverid_len;
239	}
240
241	eap_sake_derive_keys(data->root_secret_a, data->root_secret_b,
242			     data->rand_s, data->rand_p,
243			     (u8 *) &data->tek, data->msk, data->emsk);
244
245	wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Challenge");
246
247	rlen = 2 + EAP_SAKE_RAND_LEN + 2 + EAP_SAKE_MIC_LEN;
248	if (data->peerid)
249		rlen += 2 + data->peerid_len;
250	resp = eap_sake_build_msg(data, eap_get_id(reqData), rlen,
251				  EAP_SAKE_SUBTYPE_CHALLENGE);
252	if (resp == NULL)
253		return NULL;
254
255	wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_RAND_P");
256	eap_sake_add_attr(resp, EAP_SAKE_AT_RAND_P,
257			  data->rand_p, EAP_SAKE_RAND_LEN);
258
259	if (data->peerid) {
260		wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_PEERID");
261		eap_sake_add_attr(resp, EAP_SAKE_AT_PEERID,
262				  data->peerid, data->peerid_len);
263	}
264
265	wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_MIC_P");
266	wpabuf_put_u8(resp, EAP_SAKE_AT_MIC_P);
267	wpabuf_put_u8(resp, 2 + EAP_SAKE_MIC_LEN);
268	rpos = wpabuf_put(resp, EAP_SAKE_MIC_LEN);
269	if (eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
270				 data->serverid, data->serverid_len,
271				 data->peerid, data->peerid_len, 1,
272				 wpabuf_head(resp), wpabuf_len(resp), rpos,
273				 rpos)) {
274		wpa_printf(MSG_INFO, "EAP-SAKE: Failed to compute MIC");
275		wpabuf_free(resp);
276		return NULL;
277	}
278
279	eap_sake_state(data, CONFIRM);
280
281	return resp;
282}
283
284
285static struct wpabuf * eap_sake_process_confirm(struct eap_sm *sm,
286						struct eap_sake_data *data,
287						struct eap_method_ret *ret,
288						const struct wpabuf *reqData,
289						const u8 *payload,
290						size_t payload_len)
291{
292	struct eap_sake_parse_attr attr;
293	u8 mic_s[EAP_SAKE_MIC_LEN];
294	struct wpabuf *resp;
295	u8 *rpos;
296
297	if (data->state != CONFIRM) {
298		ret->ignore = TRUE;
299		return NULL;
300	}
301
302	wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Request/Confirm");
303
304	if (eap_sake_parse_attributes(payload, payload_len, &attr))
305		return NULL;
306
307	if (!attr.mic_s) {
308		wpa_printf(MSG_INFO, "EAP-SAKE: Request/Confirm did not "
309			   "include AT_MIC_S");
310		return NULL;
311	}
312
313	eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
314			     data->serverid, data->serverid_len,
315			     data->peerid, data->peerid_len, 0,
316			     wpabuf_head(reqData), wpabuf_len(reqData),
317			     attr.mic_s, mic_s);
318	if (os_memcmp(attr.mic_s, mic_s, EAP_SAKE_MIC_LEN) != 0) {
319		wpa_printf(MSG_INFO, "EAP-SAKE: Incorrect AT_MIC_S");
320		eap_sake_state(data, FAILURE);
321		ret->methodState = METHOD_DONE;
322		ret->decision = DECISION_FAIL;
323		ret->allowNotifications = FALSE;
324		wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending "
325			   "Response/Auth-Reject");
326		return eap_sake_build_msg(data, eap_get_id(reqData), 0,
327					  EAP_SAKE_SUBTYPE_AUTH_REJECT);
328	}
329
330	wpa_printf(MSG_DEBUG, "EAP-SAKE: Sending Response/Confirm");
331
332	resp = eap_sake_build_msg(data, eap_get_id(reqData),
333				  2 + EAP_SAKE_MIC_LEN,
334				  EAP_SAKE_SUBTYPE_CONFIRM);
335	if (resp == NULL)
336		return NULL;
337
338	wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_MIC_P");
339	wpabuf_put_u8(resp, EAP_SAKE_AT_MIC_P);
340	wpabuf_put_u8(resp, 2 + EAP_SAKE_MIC_LEN);
341	rpos = wpabuf_put(resp, EAP_SAKE_MIC_LEN);
342	if (eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
343				 data->serverid, data->serverid_len,
344				 data->peerid, data->peerid_len, 1,
345				 wpabuf_head(resp), wpabuf_len(resp), rpos,
346				 rpos)) {
347		wpa_printf(MSG_INFO, "EAP-SAKE: Failed to compute MIC");
348		wpabuf_free(resp);
349		return NULL;
350	}
351
352	eap_sake_state(data, SUCCESS);
353	ret->methodState = METHOD_DONE;
354	ret->decision = DECISION_UNCOND_SUCC;
355	ret->allowNotifications = FALSE;
356
357	return resp;
358}
359
360
361static struct wpabuf * eap_sake_process(struct eap_sm *sm, void *priv,
362					struct eap_method_ret *ret,
363					const struct wpabuf *reqData)
364{
365	struct eap_sake_data *data = priv;
366	const struct eap_sake_hdr *req;
367	struct wpabuf *resp;
368	const u8 *pos, *end;
369	size_t len;
370	u8 subtype, session_id;
371
372	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_SAKE, reqData, &len);
373	if (pos == NULL || len < sizeof(struct eap_sake_hdr)) {
374		ret->ignore = TRUE;
375		return NULL;
376	}
377
378	req = (const struct eap_sake_hdr *) pos;
379	end = pos + len;
380	subtype = req->subtype;
381	session_id = req->session_id;
382	pos = (const u8 *) (req + 1);
383
384	wpa_printf(MSG_DEBUG, "EAP-SAKE: Received frame: subtype %d "
385		   "session_id %d", subtype, session_id);
386	wpa_hexdump(MSG_DEBUG, "EAP-SAKE: Received attributes",
387		    pos, end - pos);
388
389	if (data->session_id_set && data->session_id != session_id) {
390		wpa_printf(MSG_INFO, "EAP-SAKE: Session ID mismatch (%d,%d)",
391			   session_id, data->session_id);
392		ret->ignore = TRUE;
393		return NULL;
394	}
395	data->session_id = session_id;
396	data->session_id_set = 1;
397
398	ret->ignore = FALSE;
399	ret->methodState = METHOD_MAY_CONT;
400	ret->decision = DECISION_FAIL;
401	ret->allowNotifications = TRUE;
402
403	switch (subtype) {
404	case EAP_SAKE_SUBTYPE_IDENTITY:
405		resp = eap_sake_process_identity(sm, data, ret, reqData,
406						 pos, end - pos);
407		break;
408	case EAP_SAKE_SUBTYPE_CHALLENGE:
409		resp = eap_sake_process_challenge(sm, data, ret, reqData,
410						  pos, end - pos);
411		break;
412	case EAP_SAKE_SUBTYPE_CONFIRM:
413		resp = eap_sake_process_confirm(sm, data, ret, reqData,
414						pos, end - pos);
415		break;
416	default:
417		wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring message with "
418			   "unknown subtype %d", subtype);
419		ret->ignore = TRUE;
420		return NULL;
421	}
422
423	if (ret->methodState == METHOD_DONE)
424		ret->allowNotifications = FALSE;
425
426	return resp;
427}
428
429
430static Boolean eap_sake_isKeyAvailable(struct eap_sm *sm, void *priv)
431{
432	struct eap_sake_data *data = priv;
433	return data->state == SUCCESS;
434}
435
436
437static u8 * eap_sake_getKey(struct eap_sm *sm, void *priv, size_t *len)
438{
439	struct eap_sake_data *data = priv;
440	u8 *key;
441
442	if (data->state != SUCCESS)
443		return NULL;
444
445	key = os_malloc(EAP_MSK_LEN);
446	if (key == NULL)
447		return NULL;
448	os_memcpy(key, data->msk, EAP_MSK_LEN);
449	*len = EAP_MSK_LEN;
450
451	return key;
452}
453
454
455static u8 * eap_sake_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
456{
457	struct eap_sake_data *data = priv;
458	u8 *key;
459
460	if (data->state != SUCCESS)
461		return NULL;
462
463	key = os_malloc(EAP_EMSK_LEN);
464	if (key == NULL)
465		return NULL;
466	os_memcpy(key, data->emsk, EAP_EMSK_LEN);
467	*len = EAP_EMSK_LEN;
468
469	return key;
470}
471
472
473int eap_peer_sake_register(void)
474{
475	struct eap_method *eap;
476	int ret;
477
478	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
479				    EAP_VENDOR_IETF, EAP_TYPE_SAKE, "SAKE");
480	if (eap == NULL)
481		return -1;
482
483	eap->init = eap_sake_init;
484	eap->deinit = eap_sake_deinit;
485	eap->process = eap_sake_process;
486	eap->isKeyAvailable = eap_sake_isKeyAvailable;
487	eap->getKey = eap_sake_getKey;
488	eap->get_emsk = eap_sake_get_emsk;
489
490	ret = eap_peer_method_register(eap);
491	if (ret)
492		eap_peer_method_free(eap);
493	return ret;
494}
495