1 /*
2  * EAP peer method: EAP-MSCHAPV2 (draft-kamath-pppext-eap-mschapv2-00.txt)
3  * Copyright (c) 2004-2008, 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  * This file implements EAP peer part of EAP-MSCHAPV2 method (EAP type 26).
9  * draft-kamath-pppext-eap-mschapv2-00.txt defines the Microsoft EAP CHAP
10  * Extensions Protocol, Version 2, for mutual authentication and key
11  * derivation. This encapsulates MS-CHAP-v2 protocol which is defined in
12  * RFC 2759. Use of EAP-MSCHAPV2 derived keys with MPPE cipher is described in
13  * RFC 3079.
14  */
15 
16 #include "includes.h"
17 
18 #include "common.h"
19 #include "crypto/ms_funcs.h"
20 #include "crypto/random.h"
21 #include "common/wpa_ctrl.h"
22 #include "mschapv2.h"
23 #include "eap_i.h"
24 #include "eap_config.h"
25 
26 
27 #ifdef _MSC_VER
28 #pragma pack(push, 1)
29 #endif /* _MSC_VER */
30 
31 struct eap_mschapv2_hdr {
32 	u8 op_code; /* MSCHAPV2_OP_* */
33 	u8 mschapv2_id; /* usually same as EAP identifier; must be changed
34 			 * for challenges, but not for success/failure */
35 	u8 ms_length[2]; /* Note: misaligned; length - 5 */
36 	/* followed by data */
37 } STRUCT_PACKED;
38 
39 /* Response Data field */
40 struct ms_response {
41 	u8 peer_challenge[MSCHAPV2_CHAL_LEN];
42 	u8 reserved[8];
43 	u8 nt_response[MSCHAPV2_NT_RESPONSE_LEN];
44 	u8 flags;
45 } STRUCT_PACKED;
46 
47 /* Change-Password Data field */
48 struct ms_change_password {
49 	u8 encr_password[516];
50 	u8 encr_hash[16];
51 	u8 peer_challenge[MSCHAPV2_CHAL_LEN];
52 	u8 reserved[8];
53 	u8 nt_response[MSCHAPV2_NT_RESPONSE_LEN];
54 	u8 flags[2];
55 } STRUCT_PACKED;
56 
57 #ifdef _MSC_VER
58 #pragma pack(pop)
59 #endif /* _MSC_VER */
60 
61 #define MSCHAPV2_OP_CHALLENGE 1
62 #define MSCHAPV2_OP_RESPONSE 2
63 #define MSCHAPV2_OP_SUCCESS 3
64 #define MSCHAPV2_OP_FAILURE 4
65 #define MSCHAPV2_OP_CHANGE_PASSWORD 7
66 
67 #define ERROR_RESTRICTED_LOGON_HOURS 646
68 #define ERROR_ACCT_DISABLED 647
69 #define ERROR_PASSWD_EXPIRED 648
70 #define ERROR_NO_DIALIN_PERMISSION 649
71 #define ERROR_AUTHENTICATION_FAILURE 691
72 #define ERROR_CHANGING_PASSWORD 709
73 
74 #define PASSWD_CHANGE_CHAL_LEN 16
75 #define MSCHAPV2_KEY_LEN 16
76 
77 
78 struct eap_mschapv2_data {
79 	u8 auth_response[MSCHAPV2_AUTH_RESPONSE_LEN];
80 	int auth_response_valid;
81 
82 	int prev_error;
83 	u8 passwd_change_challenge[PASSWD_CHANGE_CHAL_LEN];
84 	int passwd_change_challenge_valid;
85 	int passwd_change_version;
86 
87 	/* Optional challenge values generated in EAP-FAST Phase 1 negotiation
88 	 */
89 	u8 *peer_challenge;
90 	u8 *auth_challenge;
91 
92 	int phase2;
93 	u8 master_key[MSCHAPV2_MASTER_KEY_LEN];
94 	int master_key_valid;
95 	int success;
96 
97 	struct wpabuf *prev_challenge;
98 };
99 
100 
101 static void eap_mschapv2_deinit(struct eap_sm *sm, void *priv);
102 
103 
eap_mschapv2_init(struct eap_sm * sm)104 static void * eap_mschapv2_init(struct eap_sm *sm)
105 {
106 	struct eap_mschapv2_data *data;
107 	data = os_zalloc(sizeof(*data));
108 	if (data == NULL)
109 		return NULL;
110 
111 	if (sm->peer_challenge) {
112 		data->peer_challenge = os_memdup(sm->peer_challenge,
113 						 MSCHAPV2_CHAL_LEN);
114 		if (data->peer_challenge == NULL) {
115 			eap_mschapv2_deinit(sm, data);
116 			return NULL;
117 		}
118 	}
119 
120 	if (sm->auth_challenge) {
121 		data->auth_challenge = os_memdup(sm->auth_challenge,
122 						 MSCHAPV2_CHAL_LEN);
123 		if (data->auth_challenge == NULL) {
124 			eap_mschapv2_deinit(sm, data);
125 			return NULL;
126 		}
127 	}
128 
129 	data->phase2 = sm->init_phase2;
130 
131 	return data;
132 }
133 
134 
eap_mschapv2_deinit(struct eap_sm * sm,void * priv)135 static void eap_mschapv2_deinit(struct eap_sm *sm, void *priv)
136 {
137 	struct eap_mschapv2_data *data = priv;
138 	os_free(data->peer_challenge);
139 	os_free(data->auth_challenge);
140 	wpabuf_free(data->prev_challenge);
141 	bin_clear_free(data, sizeof(*data));
142 }
143 
144 
eap_mschapv2_challenge_reply(struct eap_sm * sm,struct eap_mschapv2_data * data,u8 id,u8 mschapv2_id,const u8 * auth_challenge)145 static struct wpabuf * eap_mschapv2_challenge_reply(
146 	struct eap_sm *sm, struct eap_mschapv2_data *data, u8 id,
147 	u8 mschapv2_id, const u8 *auth_challenge)
148 {
149 	struct wpabuf *resp;
150 	struct eap_mschapv2_hdr *ms;
151 	u8 *peer_challenge;
152 	int ms_len;
153 	struct ms_response *r;
154 	size_t identity_len, password_len;
155 	const u8 *identity, *password;
156 	int pwhash;
157 
158 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Generating Challenge Response");
159 
160 	identity = eap_get_config_identity(sm, &identity_len);
161 	password = eap_get_config_password2(sm, &password_len, &pwhash);
162 	if (identity == NULL || password == NULL)
163 		return NULL;
164 
165 	ms_len = sizeof(*ms) + 1 + sizeof(*r) + identity_len;
166 	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
167 			     EAP_CODE_RESPONSE, id);
168 	if (resp == NULL)
169 		return NULL;
170 
171 	ms = wpabuf_put(resp, sizeof(*ms));
172 	ms->op_code = MSCHAPV2_OP_RESPONSE;
173 	ms->mschapv2_id = mschapv2_id;
174 	if (data->prev_error) {
175 		/*
176 		 * TODO: this does not seem to be enough when processing two
177 		 * or more failure messages. IAS did not increment mschapv2_id
178 		 * in its own packets, but it seemed to expect the peer to
179 		 * increment this for all packets(?).
180 		 */
181 		ms->mschapv2_id++;
182 	}
183 	WPA_PUT_BE16(ms->ms_length, ms_len);
184 
185 	wpabuf_put_u8(resp, sizeof(*r)); /* Value-Size */
186 
187 	/* Response */
188 	r = wpabuf_put(resp, sizeof(*r));
189 	peer_challenge = r->peer_challenge;
190 	if (data->peer_challenge) {
191 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: peer_challenge generated "
192 			   "in Phase 1");
193 		peer_challenge = data->peer_challenge;
194 		os_memset(r->peer_challenge, 0, MSCHAPV2_CHAL_LEN);
195 	} else if (random_get_bytes(peer_challenge, MSCHAPV2_CHAL_LEN)) {
196 		wpabuf_free(resp);
197 		return NULL;
198 	}
199 	os_memset(r->reserved, 0, 8);
200 	if (data->auth_challenge) {
201 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: auth_challenge generated "
202 			   "in Phase 1");
203 		auth_challenge = data->auth_challenge;
204 	}
205 	if (mschapv2_derive_response(identity, identity_len, password,
206 				     password_len, pwhash, auth_challenge,
207 				     peer_challenge, r->nt_response,
208 				     data->auth_response, data->master_key)) {
209 		wpa_printf(MSG_ERROR, "EAP-MSCHAPV2: Failed to derive "
210 			   "response");
211 		wpabuf_free(resp);
212 		return NULL;
213 	}
214 	data->auth_response_valid = 1;
215 	data->master_key_valid = 1;
216 
217 	r->flags = 0; /* reserved, must be zero */
218 
219 	wpabuf_put_data(resp, identity, identity_len);
220 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: TX identifier %d mschapv2_id %d "
221 		   "(response)", id, ms->mschapv2_id);
222 	return resp;
223 }
224 
225 
226 /**
227  * eap_mschapv2_process - Process an EAP-MSCHAPv2 challenge message
228  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
229  * @data: Pointer to private EAP method data from eap_mschapv2_init()
230  * @ret: Return values from EAP request validation and processing
231  * @req: Pointer to EAP-MSCHAPv2 header from the request
232  * @req_len: Length of the EAP-MSCHAPv2 data
233  * @id: EAP identifier used in the request
234  * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
235  * no reply available
236  */
eap_mschapv2_challenge(struct eap_sm * sm,struct eap_mschapv2_data * data,struct eap_method_ret * ret,const struct eap_mschapv2_hdr * req,size_t req_len,u8 id)237 static struct wpabuf * eap_mschapv2_challenge(
238 	struct eap_sm *sm, struct eap_mschapv2_data *data,
239 	struct eap_method_ret *ret, const struct eap_mschapv2_hdr *req,
240 	size_t req_len, u8 id)
241 {
242 	size_t len, challenge_len;
243 	const u8 *pos, *challenge;
244 
245 	if (eap_get_config_identity(sm, &len) == NULL ||
246 	    eap_get_config_password(sm, &len) == NULL)
247 		return NULL;
248 
249 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received challenge");
250 	if (req_len < sizeof(*req) + 1) {
251 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Too short challenge data "
252 			   "(len %lu)", (unsigned long) req_len);
253 		ret->ignore = true;
254 		return NULL;
255 	}
256 	pos = (const u8 *) (req + 1);
257 	challenge_len = *pos++;
258 	len = req_len - sizeof(*req) - 1;
259 	if (challenge_len != MSCHAPV2_CHAL_LEN) {
260 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Invalid challenge length "
261 			   "%lu", (unsigned long) challenge_len);
262 		ret->ignore = true;
263 		return NULL;
264 	}
265 
266 	if (len < challenge_len) {
267 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Too short challenge"
268 			   " packet: len=%lu challenge_len=%lu",
269 			   (unsigned long) len, (unsigned long) challenge_len);
270 		ret->ignore = true;
271 		return NULL;
272 	}
273 
274 	if (data->passwd_change_challenge_valid) {
275 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Using challenge from the "
276 			   "failure message");
277 		challenge = data->passwd_change_challenge;
278 	} else
279 		challenge = pos;
280 	pos += challenge_len;
281 	len -= challenge_len;
282 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Authentication Servername",
283 		    pos, len);
284 
285 	ret->ignore = false;
286 	ret->methodState = METHOD_MAY_CONT;
287 	ret->decision = DECISION_FAIL;
288 	ret->allowNotifications = true;
289 
290 	return eap_mschapv2_challenge_reply(sm, data, id, req->mschapv2_id,
291 					    challenge);
292 }
293 
294 
eap_mschapv2_password_changed(struct eap_sm * sm,struct eap_mschapv2_data * data)295 static void eap_mschapv2_password_changed(struct eap_sm *sm,
296 					  struct eap_mschapv2_data *data)
297 {
298 	struct eap_peer_config *config = eap_get_config(sm);
299 	if (config && config->new_password) {
300 		wpa_msg(sm->msg_ctx, MSG_INFO,
301 			WPA_EVENT_PASSWORD_CHANGED
302 			"EAP-MSCHAPV2: Password changed successfully");
303 		data->prev_error = 0;
304 		bin_clear_free(config->password, config->password_len);
305 		if (config->flags & EAP_CONFIG_FLAGS_EXT_PASSWORD) {
306 			/* TODO: update external storage */
307 		} else if (config->flags & EAP_CONFIG_FLAGS_PASSWORD_NTHASH) {
308 			config->password = os_malloc(16);
309 			config->password_len = 16;
310 			if (config->password &&
311 			    nt_password_hash(config->new_password,
312 					     config->new_password_len,
313 					     config->password)) {
314 				bin_clear_free(config->password,
315 					       config->password_len);
316 				config->password = NULL;
317 				config->password_len = 0;
318 			}
319 			bin_clear_free(config->new_password,
320 				       config->new_password_len);
321 		} else {
322 			config->password = config->new_password;
323 			config->password_len = config->new_password_len;
324 		}
325 		config->new_password = NULL;
326 		config->new_password_len = 0;
327 	}
328 }
329 
330 
331 /**
332  * eap_mschapv2_process - Process an EAP-MSCHAPv2 success message
333  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
334  * @data: Pointer to private EAP method data from eap_mschapv2_init()
335  * @ret: Return values from EAP request validation and processing
336  * @req: Pointer to EAP-MSCHAPv2 header from the request
337  * @req_len: Length of the EAP-MSCHAPv2 data
338  * @id: EAP identifier used in th erequest
339  * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
340  * no reply available
341  */
eap_mschapv2_success(struct eap_sm * sm,struct eap_mschapv2_data * data,struct eap_method_ret * ret,const struct eap_mschapv2_hdr * req,size_t req_len,u8 id)342 static struct wpabuf * eap_mschapv2_success(struct eap_sm *sm,
343 					    struct eap_mschapv2_data *data,
344 					    struct eap_method_ret *ret,
345 					    const struct eap_mschapv2_hdr *req,
346 					    size_t req_len, u8 id)
347 {
348 	struct wpabuf *resp;
349 	const u8 *pos;
350 	size_t len;
351 
352 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received success");
353 	len = req_len - sizeof(*req);
354 	pos = (const u8 *) (req + 1);
355 	if (!data->auth_response_valid ||
356 	    mschapv2_verify_auth_response(data->auth_response, pos, len)) {
357 		wpa_printf(MSG_WARNING, "EAP-MSCHAPV2: Invalid authenticator "
358 			   "response in success request");
359 		ret->methodState = METHOD_DONE;
360 		ret->decision = DECISION_FAIL;
361 		return NULL;
362 	}
363 	pos += 2 + 2 * MSCHAPV2_AUTH_RESPONSE_LEN;
364 	len -= 2 + 2 * MSCHAPV2_AUTH_RESPONSE_LEN;
365 	while (len > 0 && *pos == ' ') {
366 		pos++;
367 		len--;
368 	}
369 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Success message",
370 			  pos, len);
371 	wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Authentication succeeded");
372 
373 	/* Note: Only op_code of the EAP-MSCHAPV2 header is included in success
374 	 * message. */
375 	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, 1,
376 			     EAP_CODE_RESPONSE, id);
377 	if (resp == NULL) {
378 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Failed to allocate "
379 			   "buffer for success response");
380 		ret->ignore = true;
381 		return NULL;
382 	}
383 
384 	wpabuf_put_u8(resp, MSCHAPV2_OP_SUCCESS); /* op_code */
385 
386 	ret->methodState = METHOD_DONE;
387 	ret->decision = DECISION_UNCOND_SUCC;
388 	ret->allowNotifications = false;
389 	data->success = 1;
390 
391 	if (data->prev_error == ERROR_PASSWD_EXPIRED)
392 		eap_mschapv2_password_changed(sm, data);
393 
394 	return resp;
395 }
396 
397 
eap_mschapv2_failure_txt(struct eap_sm * sm,struct eap_mschapv2_data * data,char * txt)398 static int eap_mschapv2_failure_txt(struct eap_sm *sm,
399 				    struct eap_mschapv2_data *data, char *txt)
400 {
401 	char *pos, *msg = "";
402 	int retry = 1;
403 	struct eap_peer_config *config = eap_get_config(sm);
404 
405 	/* For example:
406 	 * E=691 R=1 C=<32 octets hex challenge> V=3 M=Authentication Failure
407 	 */
408 
409 	pos = txt;
410 
411 	if (pos && os_strncmp(pos, "E=", 2) == 0) {
412 		pos += 2;
413 		data->prev_error = atoi(pos);
414 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: error %d",
415 			   data->prev_error);
416 		pos = os_strchr(pos, ' ');
417 		if (pos)
418 			pos++;
419 	}
420 
421 	if (pos && os_strncmp(pos, "R=", 2) == 0) {
422 		pos += 2;
423 		retry = atoi(pos);
424 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: retry is %sallowed",
425 			   retry == 1 ? "" : "not ");
426 		pos = os_strchr(pos, ' ');
427 		if (pos)
428 			pos++;
429 	}
430 
431 	if (pos && os_strncmp(pos, "C=", 2) == 0) {
432 		int hex_len;
433 		pos += 2;
434 		hex_len = os_strchr(pos, ' ') - (char *) pos;
435 		if (hex_len == PASSWD_CHANGE_CHAL_LEN * 2) {
436 			if (hexstr2bin(pos, data->passwd_change_challenge,
437 				       PASSWD_CHANGE_CHAL_LEN)) {
438 				wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: invalid "
439 					   "failure challenge");
440 			} else {
441 				wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: failure "
442 					    "challenge",
443 					    data->passwd_change_challenge,
444 					    PASSWD_CHANGE_CHAL_LEN);
445 				data->passwd_change_challenge_valid = 1;
446 			}
447 		} else {
448 			wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: invalid failure "
449 				   "challenge len %d", hex_len);
450 		}
451 		pos = os_strchr(pos, ' ');
452 		if (pos)
453 			pos++;
454 	} else {
455 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: required challenge field "
456 			   "was not present in failure message");
457 	}
458 
459 	if (pos && os_strncmp(pos, "V=", 2) == 0) {
460 		pos += 2;
461 		data->passwd_change_version = atoi(pos);
462 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: password changing "
463 			   "protocol version %d", data->passwd_change_version);
464 		pos = os_strchr(pos, ' ');
465 		if (pos)
466 			pos++;
467 	}
468 
469 	if (pos && os_strncmp(pos, "M=", 2) == 0) {
470 		pos += 2;
471 		msg = pos;
472 	}
473 	if (data->prev_error == ERROR_AUTHENTICATION_FAILURE && retry &&
474 	    config && config->phase2 &&
475 	    os_strstr(config->phase2, "mschapv2_retry=0")) {
476 		wpa_printf(MSG_DEBUG,
477 			   "EAP-MSCHAPV2: mark password retry disabled based on local configuration");
478 		retry = 0;
479 	}
480 	wpa_msg(sm->msg_ctx, MSG_WARNING,
481 		"EAP-MSCHAPV2: failure message: '%s' (retry %sallowed, error "
482 		"%d)",
483 		msg, retry == 1 ? "" : "not ", data->prev_error);
484 	if (data->prev_error == ERROR_PASSWD_EXPIRED &&
485 	    data->passwd_change_version == 3 && config) {
486 		if (config->new_password == NULL) {
487 			wpa_msg(sm->msg_ctx, MSG_INFO,
488 				"EAP-MSCHAPV2: Password expired - password "
489 				"change required");
490 			eap_sm_request_new_password(sm);
491 		}
492 	} else if (retry == 1 && config) {
493 		/* TODO: could prevent the current password from being used
494 		 * again at least for some period of time */
495 		if (!config->mschapv2_retry)
496 			eap_sm_request_identity(sm);
497 		eap_sm_request_password(sm);
498 		config->mschapv2_retry = 1;
499 	} else if (config) {
500 		/* TODO: prevent retries using same username/password */
501 		config->mschapv2_retry = 0;
502 	}
503 
504 	return retry == 1;
505 }
506 
507 
eap_mschapv2_change_password(struct eap_sm * sm,struct eap_mschapv2_data * data,struct eap_method_ret * ret,const struct eap_mschapv2_hdr * req,u8 id)508 static struct wpabuf * eap_mschapv2_change_password(
509 	struct eap_sm *sm, struct eap_mschapv2_data *data,
510 	struct eap_method_ret *ret, const struct eap_mschapv2_hdr *req, u8 id)
511 {
512 #ifdef CONFIG_NO_RC4
513 	wpa_printf(MSG_ERROR,
514 		"EAP-MSCHAPV2: RC4 not support in the build - cannot change password");
515 	return NULL;
516 #else /* CONFIG_NO_RC4 */
517 	struct wpabuf *resp;
518 	int ms_len;
519 	const u8 *username, *password, *new_password;
520 	size_t username_len, password_len, new_password_len;
521 	struct eap_mschapv2_hdr *ms;
522 	struct ms_change_password *cp;
523 	u8 password_hash[16], password_hash_hash[16];
524 	int pwhash;
525 
526 	username = eap_get_config_identity(sm, &username_len);
527 	password = eap_get_config_password2(sm, &password_len, &pwhash);
528 	new_password = eap_get_config_new_password(sm, &new_password_len);
529 	if (username == NULL || password == NULL || new_password == NULL)
530 		return NULL;
531 
532 	username = mschapv2_remove_domain(username, &username_len);
533 
534 	ret->ignore = false;
535 	ret->methodState = METHOD_MAY_CONT;
536 	ret->decision = DECISION_COND_SUCC;
537 	ret->allowNotifications = true;
538 
539 	ms_len = sizeof(*ms) + sizeof(*cp);
540 	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
541 			     EAP_CODE_RESPONSE, id);
542 	if (resp == NULL)
543 		return NULL;
544 
545 	ms = wpabuf_put(resp, sizeof(*ms));
546 	ms->op_code = MSCHAPV2_OP_CHANGE_PASSWORD;
547 	ms->mschapv2_id = req->mschapv2_id + 1;
548 	WPA_PUT_BE16(ms->ms_length, ms_len);
549 	cp = wpabuf_put(resp, sizeof(*cp));
550 
551 	/* Encrypted-Password */
552 	if (pwhash) {
553 		if (encrypt_pw_block_with_password_hash(
554 			    new_password, new_password_len,
555 			    password, cp->encr_password))
556 			goto fail;
557 	} else {
558 		if (new_password_encrypted_with_old_nt_password_hash(
559 			    new_password, new_password_len,
560 			    password, password_len, cp->encr_password))
561 			goto fail;
562 	}
563 
564 	/* Encrypted-Hash */
565 	if (pwhash) {
566 		u8 new_password_hash[16];
567 		if (nt_password_hash(new_password, new_password_len,
568 				     new_password_hash) ||
569 		    nt_password_hash_encrypted_with_block(password,
570 							  new_password_hash,
571 							  cp->encr_hash))
572 			goto fail;
573 	} else {
574 		if (old_nt_password_hash_encrypted_with_new_nt_password_hash(
575 			    new_password, new_password_len,
576 			    password, password_len, cp->encr_hash))
577 			goto fail;
578 	}
579 
580 	/* Peer-Challenge */
581 	if (random_get_bytes(cp->peer_challenge, MSCHAPV2_CHAL_LEN))
582 		goto fail;
583 
584 	/* Reserved, must be zero */
585 	os_memset(cp->reserved, 0, 8);
586 
587 	/* NT-Response */
588 	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: auth_challenge",
589 		    data->passwd_change_challenge, PASSWD_CHANGE_CHAL_LEN);
590 	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: peer_challenge",
591 		    cp->peer_challenge, MSCHAPV2_CHAL_LEN);
592 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: username",
593 			  username, username_len);
594 	wpa_hexdump_ascii_key(MSG_DEBUG, "EAP-MSCHAPV2: new password",
595 			      new_password, new_password_len);
596 	generate_nt_response(data->passwd_change_challenge, cp->peer_challenge,
597 			     username, username_len,
598 			     new_password, new_password_len,
599 			     cp->nt_response);
600 	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: NT-Response",
601 		    cp->nt_response, MSCHAPV2_NT_RESPONSE_LEN);
602 
603 	/* Authenticator response is not really needed yet, but calculate it
604 	 * here so that challenges need not be saved. */
605 	generate_authenticator_response(new_password, new_password_len,
606 					cp->peer_challenge,
607 					data->passwd_change_challenge,
608 					username, username_len,
609 					cp->nt_response, data->auth_response);
610 	data->auth_response_valid = 1;
611 
612 	/* Likewise, generate master_key here since we have the needed data
613 	 * available. */
614 	if (nt_password_hash(new_password, new_password_len, password_hash) ||
615 	    hash_nt_password_hash(password_hash, password_hash_hash) ||
616 	    get_master_key(password_hash_hash, cp->nt_response,
617 			   data->master_key)) {
618 		data->auth_response_valid = 0;
619 		goto fail;
620 	}
621 	data->master_key_valid = 1;
622 
623 	/* Flags */
624 	os_memset(cp->flags, 0, 2);
625 
626 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: TX identifier %d mschapv2_id %d "
627 		   "(change pw)", id, ms->mschapv2_id);
628 
629 	return resp;
630 
631 fail:
632 	wpabuf_free(resp);
633 	return NULL;
634 #endif /* CONFIG_NO_RC4 */
635 }
636 
637 
638 /**
639  * eap_mschapv2_process - Process an EAP-MSCHAPv2 failure message
640  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
641  * @data: Pointer to private EAP method data from eap_mschapv2_init()
642  * @ret: Return values from EAP request validation and processing
643  * @req: Pointer to EAP-MSCHAPv2 header from the request
644  * @req_len: Length of the EAP-MSCHAPv2 data
645  * @id: EAP identifier used in th erequest
646  * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
647  * no reply available
648  */
eap_mschapv2_failure(struct eap_sm * sm,struct eap_mschapv2_data * data,struct eap_method_ret * ret,const struct eap_mschapv2_hdr * req,size_t req_len,u8 id)649 static struct wpabuf * eap_mschapv2_failure(struct eap_sm *sm,
650 					    struct eap_mschapv2_data *data,
651 					    struct eap_method_ret *ret,
652 					    const struct eap_mschapv2_hdr *req,
653 					    size_t req_len, u8 id)
654 {
655 	struct wpabuf *resp;
656 	const u8 *msdata = (const u8 *) (req + 1);
657 	char *buf;
658 	size_t len = req_len - sizeof(*req);
659 	int retry = 0;
660 
661 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received failure");
662 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Failure data",
663 			  msdata, len);
664 	/*
665 	 * eap_mschapv2_failure_txt() expects a nul terminated string, so we
666 	 * must allocate a large enough temporary buffer to create that since
667 	 * the received message does not include nul termination.
668 	 */
669 	buf = dup_binstr(msdata, len);
670 	if (buf) {
671 		retry = eap_mschapv2_failure_txt(sm, data, buf);
672 		os_free(buf);
673 	}
674 
675 	ret->ignore = false;
676 	ret->methodState = METHOD_DONE;
677 	ret->decision = DECISION_FAIL;
678 	ret->allowNotifications = false;
679 
680 	if (data->prev_error == ERROR_PASSWD_EXPIRED &&
681 	    data->passwd_change_version == 3) {
682 		struct eap_peer_config *config = eap_get_config(sm);
683 		if (config && config->new_password)
684 			return eap_mschapv2_change_password(sm, data, ret, req,
685 							    id);
686 		if (config && config->pending_req_new_password)
687 			return NULL;
688 	} else if (retry && data->prev_error == ERROR_AUTHENTICATION_FAILURE) {
689 		/* TODO: could try to retry authentication, e.g, after having
690 		 * changed the username/password. In this case, EAP MS-CHAP-v2
691 		 * Failure Response would not be sent here. */
692 		return NULL;
693 	}
694 
695 	/* Note: Only op_code of the EAP-MSCHAPV2 header is included in failure
696 	 * message. */
697 	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, 1,
698 			     EAP_CODE_RESPONSE, id);
699 	if (resp == NULL)
700 		return NULL;
701 
702 	wpabuf_put_u8(resp, MSCHAPV2_OP_FAILURE); /* op_code */
703 
704 	return resp;
705 }
706 
707 
eap_mschapv2_check_config(struct eap_sm * sm)708 static int eap_mschapv2_check_config(struct eap_sm *sm)
709 {
710 	size_t len;
711 
712 	if (eap_get_config_identity(sm, &len) == NULL) {
713 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Identity not configured");
714 		eap_sm_request_identity(sm);
715 		return -1;
716 	}
717 
718 	if (eap_get_config_password(sm, &len) == NULL) {
719 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Password not configured");
720 		eap_sm_request_password(sm);
721 		return -1;
722 	}
723 
724 	return 0;
725 }
726 
727 
eap_mschapv2_check_mslen(struct eap_sm * sm,size_t len,const struct eap_mschapv2_hdr * ms)728 static int eap_mschapv2_check_mslen(struct eap_sm *sm, size_t len,
729 				    const struct eap_mschapv2_hdr *ms)
730 {
731 	size_t ms_len = WPA_GET_BE16(ms->ms_length);
732 
733 	if (ms_len == len)
734 		return 0;
735 
736 	wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Invalid header: len=%lu "
737 		   "ms_len=%lu", (unsigned long) len, (unsigned long) ms_len);
738 	if (sm->workaround) {
739 		/* Some authentication servers use invalid ms_len,
740 		 * ignore it for interoperability. */
741 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: workaround, ignore"
742 			   " invalid ms_len %lu (len %lu)",
743 			   (unsigned long) ms_len,
744 			   (unsigned long) len);
745 		return 0;
746 	}
747 
748 	return -1;
749 }
750 
751 
eap_mschapv2_copy_challenge(struct eap_mschapv2_data * data,const struct wpabuf * reqData)752 static void eap_mschapv2_copy_challenge(struct eap_mschapv2_data *data,
753 					const struct wpabuf *reqData)
754 {
755 	/*
756 	 * Store a copy of the challenge message, so that it can be processed
757 	 * again in case retry is allowed after a possible failure.
758 	 */
759 	wpabuf_free(data->prev_challenge);
760 	data->prev_challenge = wpabuf_dup(reqData);
761 }
762 
763 
764 /**
765  * eap_mschapv2_process - Process an EAP-MSCHAPv2 request
766  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
767  * @priv: Pointer to private EAP method data from eap_mschapv2_init()
768  * @ret: Return values from EAP request validation and processing
769  * @reqData: EAP request to be processed (eapReqData)
770  * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
771  * no reply available
772  */
eap_mschapv2_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)773 static struct wpabuf * eap_mschapv2_process(struct eap_sm *sm, void *priv,
774 					    struct eap_method_ret *ret,
775 					    const struct wpabuf *reqData)
776 {
777 	struct eap_mschapv2_data *data = priv;
778 	struct eap_peer_config *config = eap_get_config(sm);
779 	const struct eap_mschapv2_hdr *ms;
780 	int using_prev_challenge = 0;
781 	const u8 *pos;
782 	size_t len;
783 	u8 id;
784 
785 	if (eap_mschapv2_check_config(sm)) {
786 		ret->ignore = true;
787 		return NULL;
788 	}
789 
790 	if (config->mschapv2_retry && data->prev_challenge &&
791 	    data->prev_error == ERROR_AUTHENTICATION_FAILURE) {
792 		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Replacing pending packet "
793 			   "with the previous challenge");
794 
795 		reqData = data->prev_challenge;
796 		using_prev_challenge = 1;
797 		config->mschapv2_retry = 0;
798 	}
799 
800 	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, reqData,
801 			       &len);
802 	if (pos == NULL || len < sizeof(*ms) + 1) {
803 		ret->ignore = true;
804 		return NULL;
805 	}
806 
807 	ms = (const struct eap_mschapv2_hdr *) pos;
808 	if (eap_mschapv2_check_mslen(sm, len, ms)) {
809 		ret->ignore = true;
810 		return NULL;
811 	}
812 
813 	id = eap_get_id(reqData);
814 	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: RX identifier %d mschapv2_id %d",
815 		   id, ms->mschapv2_id);
816 
817 	switch (ms->op_code) {
818 	case MSCHAPV2_OP_CHALLENGE:
819 		if (!using_prev_challenge)
820 			eap_mschapv2_copy_challenge(data, reqData);
821 		return eap_mschapv2_challenge(sm, data, ret, ms, len, id);
822 	case MSCHAPV2_OP_SUCCESS:
823 		return eap_mschapv2_success(sm, data, ret, ms, len, id);
824 	case MSCHAPV2_OP_FAILURE:
825 		return eap_mschapv2_failure(sm, data, ret, ms, len, id);
826 	default:
827 		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Unknown op %d - ignored",
828 			   ms->op_code);
829 		ret->ignore = true;
830 		return NULL;
831 	}
832 }
833 
834 
eap_mschapv2_isKeyAvailable(struct eap_sm * sm,void * priv)835 static bool eap_mschapv2_isKeyAvailable(struct eap_sm *sm, void *priv)
836 {
837 	struct eap_mschapv2_data *data = priv;
838 	return data->success && data->master_key_valid;
839 }
840 
841 
eap_mschapv2_getKey(struct eap_sm * sm,void * priv,size_t * len)842 static u8 * eap_mschapv2_getKey(struct eap_sm *sm, void *priv, size_t *len)
843 {
844 	struct eap_mschapv2_data *data = priv;
845 	u8 *key;
846 	int key_len;
847 
848 	if (!data->master_key_valid || !data->success)
849 		return NULL;
850 
851 	key_len = 2 * MSCHAPV2_KEY_LEN;
852 
853 	key = os_malloc(key_len);
854 	if (key == NULL)
855 		return NULL;
856 
857 	/* MSK = server MS-MPPE-Recv-Key | MS-MPPE-Send-Key, i.e.,
858 	 *	peer MS-MPPE-Send-Key | MS-MPPE-Recv-Key */
859 	if (get_asymetric_start_key(data->master_key, key, MSCHAPV2_KEY_LEN, 1,
860 				    0) < 0 ||
861 	    get_asymetric_start_key(data->master_key, key + MSCHAPV2_KEY_LEN,
862 				    MSCHAPV2_KEY_LEN, 0, 0) < 0) {
863 		os_free(key);
864 		return NULL;
865 	}
866 
867 	wpa_hexdump_key(MSG_DEBUG, "EAP-MSCHAPV2: Derived key",
868 			key, key_len);
869 
870 	*len = key_len;
871 	return key;
872 }
873 
874 
875 /**
876  * eap_peer_mschapv2_register - Register EAP-MSCHAPv2 peer method
877  * Returns: 0 on success, -1 on failure
878  *
879  * This function is used to register EAP-MSCHAPv2 peer method into the EAP
880  * method list.
881  */
eap_peer_mschapv2_register(void)882 int eap_peer_mschapv2_register(void)
883 {
884 	struct eap_method *eap;
885 
886 	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
887 				    EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2,
888 				    "MSCHAPV2");
889 	if (eap == NULL)
890 		return -1;
891 
892 	eap->init = eap_mschapv2_init;
893 	eap->deinit = eap_mschapv2_deinit;
894 	eap->process = eap_mschapv2_process;
895 	eap->isKeyAvailable = eap_mschapv2_isKeyAvailable;
896 	eap->getKey = eap_mschapv2_getKey;
897 
898 	return eap_peer_method_register(eap);
899 }
900