1 /*
2 * hostapd / EAP-MSCHAPv2 (draft-kamath-pppext-eap-mschapv2-00.txt) server
3 * Copyright (c) 2004-2007, 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/ms_funcs.h"
13 #include "crypto/random.h"
14 #include "eap_i.h"
15
16
17 struct eap_mschapv2_hdr {
18 u8 op_code; /* MSCHAPV2_OP_* */
19 u8 mschapv2_id; /* must be changed for challenges, but not for
20 * success/failure */
21 u8 ms_length[2]; /* Note: misaligned; length - 5 */
22 /* followed by data */
23 } STRUCT_PACKED;
24
25 #define MSCHAPV2_OP_CHALLENGE 1
26 #define MSCHAPV2_OP_RESPONSE 2
27 #define MSCHAPV2_OP_SUCCESS 3
28 #define MSCHAPV2_OP_FAILURE 4
29 #define MSCHAPV2_OP_CHANGE_PASSWORD 7
30
31 #define MSCHAPV2_RESP_LEN 49
32
33 #define ERROR_RESTRICTED_LOGON_HOURS 646
34 #define ERROR_ACCT_DISABLED 647
35 #define ERROR_PASSWD_EXPIRED 648
36 #define ERROR_NO_DIALIN_PERMISSION 649
37 #define ERROR_AUTHENTICATION_FAILURE 691
38 #define ERROR_CHANGING_PASSWORD 709
39
40 #define PASSWD_CHANGE_CHAL_LEN 16
41 #define MSCHAPV2_KEY_LEN 16
42
43
44 #define CHALLENGE_LEN 16
45
46 struct eap_mschapv2_data {
47 u8 auth_challenge[CHALLENGE_LEN];
48 int auth_challenge_from_tls;
49 u8 *peer_challenge;
50 u8 auth_response[20];
51 enum { CHALLENGE, SUCCESS_REQ, FAILURE_REQ, SUCCESS, FAILURE } state;
52 u8 resp_mschapv2_id;
53 u8 master_key[16];
54 int master_key_valid;
55 };
56
57
eap_mschapv2_init(struct eap_sm * sm)58 static void * eap_mschapv2_init(struct eap_sm *sm)
59 {
60 struct eap_mschapv2_data *data;
61
62 data = os_zalloc(sizeof(*data));
63 if (data == NULL)
64 return NULL;
65 data->state = CHALLENGE;
66
67 if (sm->auth_challenge) {
68 os_memcpy(data->auth_challenge, sm->auth_challenge,
69 CHALLENGE_LEN);
70 data->auth_challenge_from_tls = 1;
71 }
72
73 if (sm->peer_challenge) {
74 data->peer_challenge = os_malloc(CHALLENGE_LEN);
75 if (data->peer_challenge == NULL) {
76 os_free(data);
77 return NULL;
78 }
79 os_memcpy(data->peer_challenge, sm->peer_challenge,
80 CHALLENGE_LEN);
81 }
82
83 return data;
84 }
85
86
eap_mschapv2_reset(struct eap_sm * sm,void * priv)87 static void eap_mschapv2_reset(struct eap_sm *sm, void *priv)
88 {
89 struct eap_mschapv2_data *data = priv;
90 if (data == NULL)
91 return;
92
93 os_free(data->peer_challenge);
94 bin_clear_free(data, sizeof(*data));
95 }
96
97
eap_mschapv2_build_challenge(struct eap_sm * sm,struct eap_mschapv2_data * data,u8 id)98 static struct wpabuf * eap_mschapv2_build_challenge(
99 struct eap_sm *sm, struct eap_mschapv2_data *data, u8 id)
100 {
101 struct wpabuf *req;
102 struct eap_mschapv2_hdr *ms;
103 size_t ms_len;
104
105 if (!data->auth_challenge_from_tls &&
106 random_get_bytes(data->auth_challenge, CHALLENGE_LEN)) {
107 wpa_printf(MSG_ERROR, "EAP-MSCHAPV2: Failed to get random "
108 "data");
109 data->state = FAILURE;
110 return NULL;
111 }
112
113 ms_len = sizeof(*ms) + 1 + CHALLENGE_LEN + sm->server_id_len;
114 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
115 EAP_CODE_REQUEST, id);
116 if (req == NULL) {
117 wpa_printf(MSG_ERROR, "EAP-MSCHAPV2: Failed to allocate memory"
118 " for request");
119 data->state = FAILURE;
120 return NULL;
121 }
122
123 ms = wpabuf_put(req, sizeof(*ms));
124 ms->op_code = MSCHAPV2_OP_CHALLENGE;
125 ms->mschapv2_id = id;
126 WPA_PUT_BE16(ms->ms_length, ms_len);
127
128 wpabuf_put_u8(req, CHALLENGE_LEN);
129 if (!data->auth_challenge_from_tls)
130 wpabuf_put_data(req, data->auth_challenge, CHALLENGE_LEN);
131 else
132 wpabuf_put(req, CHALLENGE_LEN);
133 wpa_hexdump(MSG_MSGDUMP, "EAP-MSCHAPV2: Challenge",
134 data->auth_challenge, CHALLENGE_LEN);
135 wpabuf_put_data(req, sm->server_id, sm->server_id_len);
136
137 return req;
138 }
139
140
eap_mschapv2_build_success_req(struct eap_sm * sm,struct eap_mschapv2_data * data,u8 id)141 static struct wpabuf * eap_mschapv2_build_success_req(
142 struct eap_sm *sm, struct eap_mschapv2_data *data, u8 id)
143 {
144 struct wpabuf *req;
145 struct eap_mschapv2_hdr *ms;
146 u8 *msg;
147 char *message = "OK";
148 size_t ms_len;
149
150 ms_len = sizeof(*ms) + 2 + 2 * sizeof(data->auth_response) + 1 + 2 +
151 os_strlen(message);
152 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
153 EAP_CODE_REQUEST, id);
154 if (req == NULL) {
155 wpa_printf(MSG_ERROR, "EAP-MSCHAPV2: Failed to allocate memory"
156 " for request");
157 data->state = FAILURE;
158 return NULL;
159 }
160
161 ms = wpabuf_put(req, sizeof(*ms));
162 ms->op_code = MSCHAPV2_OP_SUCCESS;
163 ms->mschapv2_id = data->resp_mschapv2_id;
164 WPA_PUT_BE16(ms->ms_length, ms_len);
165 msg = (u8 *) (ms + 1);
166
167 wpabuf_put_u8(req, 'S');
168 wpabuf_put_u8(req, '=');
169 wpa_snprintf_hex_uppercase(
170 wpabuf_put(req, sizeof(data->auth_response) * 2),
171 sizeof(data->auth_response) * 2 + 1,
172 data->auth_response, sizeof(data->auth_response));
173 wpabuf_put_u8(req, ' ');
174 wpabuf_put_u8(req, 'M');
175 wpabuf_put_u8(req, '=');
176 wpabuf_put_data(req, message, os_strlen(message));
177
178 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-MSCHAPV2: Success Request Message",
179 msg, ms_len - sizeof(*ms));
180
181 return req;
182 }
183
184
eap_mschapv2_build_failure_req(struct eap_sm * sm,struct eap_mschapv2_data * data,u8 id)185 static struct wpabuf * eap_mschapv2_build_failure_req(
186 struct eap_sm *sm, struct eap_mschapv2_data *data, u8 id)
187 {
188 struct wpabuf *req;
189 struct eap_mschapv2_hdr *ms;
190 char *message = "E=691 R=0 C=00000000000000000000000000000000 V=3 "
191 "M=FAILED";
192 size_t ms_len;
193
194 ms_len = sizeof(*ms) + os_strlen(message);
195 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
196 EAP_CODE_REQUEST, id);
197 if (req == NULL) {
198 wpa_printf(MSG_ERROR, "EAP-MSCHAPV2: Failed to allocate memory"
199 " for request");
200 data->state = FAILURE;
201 return NULL;
202 }
203
204 ms = wpabuf_put(req, sizeof(*ms));
205 ms->op_code = MSCHAPV2_OP_FAILURE;
206 ms->mschapv2_id = data->resp_mschapv2_id;
207 WPA_PUT_BE16(ms->ms_length, ms_len);
208
209 wpabuf_put_data(req, message, os_strlen(message));
210
211 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-MSCHAPV2: Failure Request Message",
212 (u8 *) message, os_strlen(message));
213
214 return req;
215 }
216
217
eap_mschapv2_buildReq(struct eap_sm * sm,void * priv,u8 id)218 static struct wpabuf * eap_mschapv2_buildReq(struct eap_sm *sm, void *priv,
219 u8 id)
220 {
221 struct eap_mschapv2_data *data = priv;
222
223 switch (data->state) {
224 case CHALLENGE:
225 return eap_mschapv2_build_challenge(sm, data, id);
226 case SUCCESS_REQ:
227 return eap_mschapv2_build_success_req(sm, data, id);
228 case FAILURE_REQ:
229 return eap_mschapv2_build_failure_req(sm, data, id);
230 default:
231 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Unknown state %d in "
232 "buildReq", data->state);
233 break;
234 }
235 return NULL;
236 }
237
238
eap_mschapv2_check(struct eap_sm * sm,void * priv,struct wpabuf * respData)239 static Boolean eap_mschapv2_check(struct eap_sm *sm, void *priv,
240 struct wpabuf *respData)
241 {
242 struct eap_mschapv2_data *data = priv;
243 struct eap_mschapv2_hdr *resp;
244 const u8 *pos;
245 size_t len;
246
247 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, respData,
248 &len);
249 if (pos == NULL || len < 1) {
250 wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Invalid frame");
251 return TRUE;
252 }
253
254 resp = (struct eap_mschapv2_hdr *) pos;
255 if (data->state == CHALLENGE &&
256 resp->op_code != MSCHAPV2_OP_RESPONSE) {
257 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Expected Response - "
258 "ignore op %d", resp->op_code);
259 return TRUE;
260 }
261
262 if (data->state == SUCCESS_REQ &&
263 resp->op_code != MSCHAPV2_OP_SUCCESS &&
264 resp->op_code != MSCHAPV2_OP_FAILURE) {
265 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Expected Success or "
266 "Failure - ignore op %d", resp->op_code);
267 return TRUE;
268 }
269
270 if (data->state == FAILURE_REQ &&
271 resp->op_code != MSCHAPV2_OP_FAILURE) {
272 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Expected Failure "
273 "- ignore op %d", resp->op_code);
274 return TRUE;
275 }
276
277 return FALSE;
278 }
279
280
eap_mschapv2_process_response(struct eap_sm * sm,struct eap_mschapv2_data * data,struct wpabuf * respData)281 static void eap_mschapv2_process_response(struct eap_sm *sm,
282 struct eap_mschapv2_data *data,
283 struct wpabuf *respData)
284 {
285 struct eap_mschapv2_hdr *resp;
286 const u8 *pos, *end, *peer_challenge, *nt_response, *name;
287 u8 flags;
288 size_t len, name_len, i;
289 u8 expected[24];
290 const u8 *username, *user;
291 size_t username_len, user_len;
292 int res;
293 char *buf;
294
295 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, respData,
296 &len);
297 if (pos == NULL || len < 1)
298 return; /* Should not happen - frame already validated */
299
300 end = pos + len;
301 resp = (struct eap_mschapv2_hdr *) pos;
302 pos = (u8 *) (resp + 1);
303
304 if (len < sizeof(*resp) + 1 + 49 ||
305 resp->op_code != MSCHAPV2_OP_RESPONSE ||
306 pos[0] != 49) {
307 wpa_hexdump_buf(MSG_DEBUG, "EAP-MSCHAPV2: Invalid response",
308 respData);
309 data->state = FAILURE;
310 return;
311 }
312 data->resp_mschapv2_id = resp->mschapv2_id;
313 pos++;
314 peer_challenge = pos;
315 pos += 16 + 8;
316 nt_response = pos;
317 pos += 24;
318 flags = *pos++;
319 name = pos;
320 name_len = end - name;
321
322 if (data->peer_challenge) {
323 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Using pre-configured "
324 "Peer-Challenge");
325 peer_challenge = data->peer_challenge;
326 }
327 wpa_hexdump(MSG_MSGDUMP, "EAP-MSCHAPV2: Peer-Challenge",
328 peer_challenge, 16);
329 wpa_hexdump(MSG_MSGDUMP, "EAP-MSCHAPV2: NT-Response", nt_response, 24);
330 wpa_printf(MSG_MSGDUMP, "EAP-MSCHAPV2: Flags 0x%x", flags);
331 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-MSCHAPV2: Name", name, name_len);
332
333 buf = os_malloc(name_len * 4 + 1);
334 if (buf) {
335 printf_encode(buf, name_len * 4 + 1, name, name_len);
336 eap_log_msg(sm, "EAP-MSCHAPV2 Name '%s'", buf);
337 os_free(buf);
338 }
339
340 /* MSCHAPv2 does not include optional domain name in the
341 * challenge-response calculation, so remove domain prefix
342 * (if present). */
343 username = sm->identity;
344 username_len = sm->identity_len;
345 for (i = 0; i < username_len; i++) {
346 if (username[i] == '\\') {
347 username_len -= i + 1;
348 username += i + 1;
349 break;
350 }
351 }
352
353 user = name;
354 user_len = name_len;
355 for (i = 0; i < user_len; i++) {
356 if (user[i] == '\\') {
357 user_len -= i + 1;
358 user += i + 1;
359 break;
360 }
361 }
362
363 if (username_len != user_len ||
364 os_memcmp(username, user, username_len) != 0) {
365 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Mismatch in user names");
366 wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Expected user "
367 "name", username, username_len);
368 wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Received user "
369 "name", user, user_len);
370 data->state = FAILURE;
371 return;
372 }
373
374 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-MSCHAPV2: User name",
375 username, username_len);
376
377 if (sm->user->password_hash) {
378 res = generate_nt_response_pwhash(data->auth_challenge,
379 peer_challenge,
380 username, username_len,
381 sm->user->password,
382 expected);
383 } else {
384 res = generate_nt_response(data->auth_challenge,
385 peer_challenge,
386 username, username_len,
387 sm->user->password,
388 sm->user->password_len,
389 expected);
390 }
391 if (res) {
392 data->state = FAILURE;
393 return;
394 }
395
396 if (os_memcmp_const(nt_response, expected, 24) == 0) {
397 const u8 *pw_hash;
398 u8 pw_hash_buf[16], pw_hash_hash[16];
399
400 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Correct NT-Response");
401 data->state = SUCCESS_REQ;
402
403 /* Authenticator response is not really needed yet, but
404 * calculate it here so that peer_challenge and username need
405 * not be saved. */
406 if (sm->user->password_hash) {
407 pw_hash = sm->user->password;
408 } else {
409 if (nt_password_hash(sm->user->password,
410 sm->user->password_len,
411 pw_hash_buf) < 0) {
412 data->state = FAILURE;
413 return;
414 }
415 pw_hash = pw_hash_buf;
416 }
417 generate_authenticator_response_pwhash(
418 pw_hash, peer_challenge, data->auth_challenge,
419 username, username_len, nt_response,
420 data->auth_response);
421
422 hash_nt_password_hash(pw_hash, pw_hash_hash);
423 get_master_key(pw_hash_hash, nt_response, data->master_key);
424 data->master_key_valid = 1;
425 wpa_hexdump_key(MSG_DEBUG, "EAP-MSCHAPV2: Derived Master Key",
426 data->master_key, MSCHAPV2_KEY_LEN);
427 } else {
428 wpa_hexdump(MSG_MSGDUMP, "EAP-MSCHAPV2: Expected NT-Response",
429 expected, 24);
430 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Invalid NT-Response");
431 data->state = FAILURE_REQ;
432 }
433 }
434
435
eap_mschapv2_process_success_resp(struct eap_sm * sm,struct eap_mschapv2_data * data,struct wpabuf * respData)436 static void eap_mschapv2_process_success_resp(struct eap_sm *sm,
437 struct eap_mschapv2_data *data,
438 struct wpabuf *respData)
439 {
440 struct eap_mschapv2_hdr *resp;
441 const u8 *pos;
442 size_t len;
443
444 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, respData,
445 &len);
446 if (pos == NULL || len < 1)
447 return; /* Should not happen - frame already validated */
448
449 resp = (struct eap_mschapv2_hdr *) pos;
450
451 if (resp->op_code == MSCHAPV2_OP_SUCCESS) {
452 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received Success Response"
453 " - authentication completed successfully");
454 data->state = SUCCESS;
455 } else {
456 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Did not receive Success "
457 "Response - peer rejected authentication");
458 data->state = FAILURE;
459 }
460 }
461
462
eap_mschapv2_process_failure_resp(struct eap_sm * sm,struct eap_mschapv2_data * data,struct wpabuf * respData)463 static void eap_mschapv2_process_failure_resp(struct eap_sm *sm,
464 struct eap_mschapv2_data *data,
465 struct wpabuf *respData)
466 {
467 struct eap_mschapv2_hdr *resp;
468 const u8 *pos;
469 size_t len;
470
471 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, respData,
472 &len);
473 if (pos == NULL || len < 1)
474 return; /* Should not happen - frame already validated */
475
476 resp = (struct eap_mschapv2_hdr *) pos;
477
478 if (resp->op_code == MSCHAPV2_OP_FAILURE) {
479 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received Failure Response"
480 " - authentication failed");
481 } else {
482 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Did not receive Failure "
483 "Response - authentication failed");
484 }
485
486 data->state = FAILURE;
487 }
488
489
eap_mschapv2_process(struct eap_sm * sm,void * priv,struct wpabuf * respData)490 static void eap_mschapv2_process(struct eap_sm *sm, void *priv,
491 struct wpabuf *respData)
492 {
493 struct eap_mschapv2_data *data = priv;
494
495 if (sm->user == NULL || sm->user->password == NULL) {
496 wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Password not configured");
497 data->state = FAILURE;
498 return;
499 }
500
501 switch (data->state) {
502 case CHALLENGE:
503 eap_mschapv2_process_response(sm, data, respData);
504 break;
505 case SUCCESS_REQ:
506 eap_mschapv2_process_success_resp(sm, data, respData);
507 break;
508 case FAILURE_REQ:
509 eap_mschapv2_process_failure_resp(sm, data, respData);
510 break;
511 default:
512 wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Unknown state %d in "
513 "process", data->state);
514 break;
515 }
516 }
517
518
eap_mschapv2_isDone(struct eap_sm * sm,void * priv)519 static Boolean eap_mschapv2_isDone(struct eap_sm *sm, void *priv)
520 {
521 struct eap_mschapv2_data *data = priv;
522 return data->state == SUCCESS || data->state == FAILURE;
523 }
524
525
eap_mschapv2_getKey(struct eap_sm * sm,void * priv,size_t * len)526 static u8 * eap_mschapv2_getKey(struct eap_sm *sm, void *priv, size_t *len)
527 {
528 struct eap_mschapv2_data *data = priv;
529 u8 *key;
530
531 if (data->state != SUCCESS || !data->master_key_valid)
532 return NULL;
533
534 *len = 2 * MSCHAPV2_KEY_LEN;
535 key = os_malloc(*len);
536 if (key == NULL)
537 return NULL;
538 /* MSK = server MS-MPPE-Recv-Key | MS-MPPE-Send-Key */
539 get_asymetric_start_key(data->master_key, key, MSCHAPV2_KEY_LEN, 0, 1);
540 get_asymetric_start_key(data->master_key, key + MSCHAPV2_KEY_LEN,
541 MSCHAPV2_KEY_LEN, 1, 1);
542 wpa_hexdump_key(MSG_DEBUG, "EAP-MSCHAPV2: Derived key", key, *len);
543
544 return key;
545 }
546
547
eap_mschapv2_isSuccess(struct eap_sm * sm,void * priv)548 static Boolean eap_mschapv2_isSuccess(struct eap_sm *sm, void *priv)
549 {
550 struct eap_mschapv2_data *data = priv;
551 return data->state == SUCCESS;
552 }
553
554
eap_server_mschapv2_register(void)555 int eap_server_mschapv2_register(void)
556 {
557 struct eap_method *eap;
558 int ret;
559
560 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
561 EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2,
562 "MSCHAPV2");
563 if (eap == NULL)
564 return -1;
565
566 eap->init = eap_mschapv2_init;
567 eap->reset = eap_mschapv2_reset;
568 eap->buildReq = eap_mschapv2_buildReq;
569 eap->check = eap_mschapv2_check;
570 eap->process = eap_mschapv2_process;
571 eap->isDone = eap_mschapv2_isDone;
572 eap->getKey = eap_mschapv2_getKey;
573 eap->isSuccess = eap_mschapv2_isSuccess;
574
575 ret = eap_server_method_register(eap);
576 if (ret)
577 eap_server_method_free(eap);
578 return ret;
579 }
580