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