1 /*
2  * hostapd / EAP-pwd (RFC 5931) server
3  * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org>
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/sha256.h"
13 #include "crypto/ms_funcs.h"
14 #include "crypto/crypto.h"
15 #include "eap_server/eap_i.h"
16 #include "eap_common/eap_pwd_common.h"
17 
18 
19 struct eap_pwd_data {
20 	enum {
21 		PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
22 	} state;
23 	u8 *id_peer;
24 	size_t id_peer_len;
25 	u8 *id_server;
26 	size_t id_server_len;
27 	u8 *password;
28 	size_t password_len;
29 	int password_hash;
30 	u8 *salt;
31 	size_t salt_len;
32 	u32 token;
33 	u16 group_num;
34 	u8 password_prep;
35 	EAP_PWD_group *grp;
36 
37 	struct wpabuf *inbuf;
38 	size_t in_frag_pos;
39 	struct wpabuf *outbuf;
40 	size_t out_frag_pos;
41 	size_t mtu;
42 
43 	struct crypto_bignum *k;
44 	struct crypto_bignum *private_value;
45 	struct crypto_bignum *peer_scalar;
46 	struct crypto_bignum *my_scalar;
47 	struct crypto_ec_point *my_element;
48 	struct crypto_ec_point *peer_element;
49 
50 	u8 my_confirm[SHA256_MAC_LEN];
51 
52 	u8 msk[EAP_MSK_LEN];
53 	u8 emsk[EAP_EMSK_LEN];
54 	u8 session_id[1 + SHA256_MAC_LEN];
55 };
56 
57 
eap_pwd_state_txt(int state)58 static const char * eap_pwd_state_txt(int state)
59 {
60 	switch (state) {
61         case PWD_ID_Req:
62 		return "PWD-ID-Req";
63         case PWD_Commit_Req:
64 		return "PWD-Commit-Req";
65         case PWD_Confirm_Req:
66 		return "PWD-Confirm-Req";
67         case SUCCESS:
68 		return "SUCCESS";
69         case FAILURE:
70 		return "FAILURE";
71         default:
72 		return "PWD-Unk";
73 	}
74 }
75 
76 
eap_pwd_state(struct eap_pwd_data * data,int state)77 static void eap_pwd_state(struct eap_pwd_data *data, int state)
78 {
79 	wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
80 		   eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
81 	data->state = state;
82 }
83 
84 
eap_pwd_init(struct eap_sm * sm)85 static void * eap_pwd_init(struct eap_sm *sm)
86 {
87 	struct eap_pwd_data *data;
88 
89 	if (sm->user == NULL || sm->user->password == NULL ||
90 	    sm->user->password_len == 0) {
91 		wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
92 			   "configured");
93 		return NULL;
94 	}
95 
96 	data = os_zalloc(sizeof(*data));
97 	if (data == NULL)
98 		return NULL;
99 
100 	data->group_num = sm->pwd_group;
101 	wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
102 		   data->group_num);
103 	data->state = PWD_ID_Req;
104 
105 	data->id_server = (u8 *) os_strdup("server");
106 	if (data->id_server)
107 		data->id_server_len = os_strlen((char *) data->id_server);
108 
109 	data->password = os_malloc(sm->user->password_len);
110 	if (data->password == NULL) {
111 		wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
112 			   "fail");
113 		bin_clear_free(data->id_server, data->id_server_len);
114 		os_free(data);
115 		return NULL;
116 	}
117 	data->password_len = sm->user->password_len;
118 	os_memcpy(data->password, sm->user->password, data->password_len);
119 	data->password_hash = sm->user->password_hash;
120 
121 	data->salt_len = sm->user->salt_len;
122 	if (data->salt_len) {
123 		data->salt = os_memdup(sm->user->salt, sm->user->salt_len);
124 		if (!data->salt) {
125 			wpa_printf(MSG_INFO,
126 				   "EAP-pwd: Memory allocation of salt failed");
127 			bin_clear_free(data->id_server, data->id_server_len);
128 			bin_clear_free(data->password, data->password_len);
129 			os_free(data);
130 			return NULL;
131 		}
132 	}
133 
134 	data->in_frag_pos = data->out_frag_pos = 0;
135 	data->inbuf = data->outbuf = NULL;
136 	/* use default MTU from RFC 5931 if not configured otherwise */
137 	data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
138 
139 	return data;
140 }
141 
142 
eap_pwd_reset(struct eap_sm * sm,void * priv)143 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
144 {
145 	struct eap_pwd_data *data = priv;
146 
147 	crypto_bignum_deinit(data->private_value, 1);
148 	crypto_bignum_deinit(data->peer_scalar, 1);
149 	crypto_bignum_deinit(data->my_scalar, 1);
150 	crypto_bignum_deinit(data->k, 1);
151 	crypto_ec_point_deinit(data->my_element, 1);
152 	crypto_ec_point_deinit(data->peer_element, 1);
153 	bin_clear_free(data->id_peer, data->id_peer_len);
154 	bin_clear_free(data->id_server, data->id_server_len);
155 	bin_clear_free(data->password, data->password_len);
156 	bin_clear_free(data->salt, data->salt_len);
157 	if (data->grp) {
158 		crypto_ec_deinit(data->grp->group);
159 		crypto_ec_point_deinit(data->grp->pwe, 1);
160 		os_free(data->grp);
161 	}
162 	wpabuf_free(data->inbuf);
163 	wpabuf_free(data->outbuf);
164 	bin_clear_free(data, sizeof(*data));
165 }
166 
167 
eap_pwd_build_id_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)168 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
169 				 u8 id)
170 {
171 	wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
172 	/*
173 	 * if we're fragmenting then we already have an id request, just return
174 	 */
175 	if (data->out_frag_pos)
176 		return;
177 
178 	data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
179 				    data->id_server_len);
180 	if (data->outbuf == NULL) {
181 		eap_pwd_state(data, FAILURE);
182 		return;
183 	}
184 
185 	if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) {
186 		wpabuf_free(data->outbuf);
187 		data->outbuf = NULL;
188 		eap_pwd_state(data, FAILURE);
189 		return;
190 	}
191 
192 	wpa_hexdump_key(MSG_DEBUG, "EAP-pwd (server): password",
193 			data->password, data->password_len);
194 	if (data->salt_len)
195 		wpa_hexdump(MSG_DEBUG, "EAP-pwd (server): salt",
196 			    data->salt, data->salt_len);
197 
198 	/*
199 	 * If this is a salted password then figure out how it was hashed
200 	 * based on the length.
201 	 */
202 	if (data->salt_len) {
203 		switch (data->password_len) {
204 		case 20:
205 			data->password_prep = EAP_PWD_PREP_SSHA1;
206 			break;
207 		case 32:
208 			data->password_prep = EAP_PWD_PREP_SSHA256;
209 			break;
210 		case 64:
211 			data->password_prep = EAP_PWD_PREP_SSHA512;
212 			break;
213 		default:
214 			wpa_printf(MSG_INFO,
215 				   "EAP-pwd (server): bad size %d for salted password",
216 				   (int) data->password_len);
217 			eap_pwd_state(data, FAILURE);
218 			return;
219 		}
220 	} else {
221 		/* Otherwise, figure out whether it's MS hashed or plain */
222 		data->password_prep = data->password_hash ? EAP_PWD_PREP_MS :
223 			EAP_PWD_PREP_NONE;
224 	}
225 
226 	wpabuf_put_be16(data->outbuf, data->group_num);
227 	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
228 	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
229 	wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
230 	wpabuf_put_u8(data->outbuf, data->password_prep);
231 	wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
232 }
233 
234 
eap_pwd_build_commit_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)235 static void eap_pwd_build_commit_req(struct eap_sm *sm,
236 				     struct eap_pwd_data *data, u8 id)
237 {
238 	struct crypto_bignum *mask = NULL;
239 	u8 *scalar, *element;
240 	size_t prime_len, order_len;
241 
242 	wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
243 	/*
244 	 * if we're fragmenting then we already have an commit request, just
245 	 * return
246 	 */
247 	if (data->out_frag_pos)
248 		return;
249 
250 	prime_len = crypto_ec_prime_len(data->grp->group);
251 	order_len = crypto_ec_order_len(data->grp->group);
252 
253 	data->private_value = crypto_bignum_init();
254 	data->my_element = crypto_ec_point_init(data->grp->group);
255 	data->my_scalar = crypto_bignum_init();
256 	mask = crypto_bignum_init();
257 	if (!data->private_value || !data->my_element || !data->my_scalar ||
258 	    !mask) {
259 		wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
260 			   "fail");
261 		goto fin;
262 	}
263 
264 	if (eap_pwd_get_rand_mask(data->grp, data->private_value, mask,
265 				  data->my_scalar) < 0)
266 		goto fin;
267 
268 	if (crypto_ec_point_mul(data->grp->group, data->grp->pwe, mask,
269 				data->my_element) < 0) {
270 		wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
271 			   "fail");
272 		eap_pwd_state(data, FAILURE);
273 		goto fin;
274 	}
275 
276 	if (crypto_ec_point_invert(data->grp->group, data->my_element) < 0) {
277 		wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
278 			   "fail");
279 		goto fin;
280 	}
281 
282 	data->outbuf = wpabuf_alloc(2 * prime_len + order_len +
283 				    (data->salt ? 1 + data->salt_len : 0));
284 	if (data->outbuf == NULL)
285 		goto fin;
286 
287 	/* If we're doing salted password prep, add the salt */
288 	if (data->salt_len) {
289 		wpabuf_put_u8(data->outbuf, data->salt_len);
290 		wpabuf_put_data(data->outbuf, data->salt, data->salt_len);
291 	}
292 
293 	/* We send the element as (x,y) followed by the scalar */
294 	element = wpabuf_put(data->outbuf, 2 * prime_len);
295 	scalar = wpabuf_put(data->outbuf, order_len);
296 	crypto_bignum_to_bin(data->my_scalar, scalar, order_len, order_len);
297 	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, element,
298 				   element + prime_len) < 0) {
299 		wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
300 			   "fail");
301 		goto fin;
302 	}
303 
304 fin:
305 	crypto_bignum_deinit(mask, 1);
306 	if (data->outbuf == NULL)
307 		eap_pwd_state(data, FAILURE);
308 }
309 
310 
eap_pwd_build_confirm_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)311 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
312 				      struct eap_pwd_data *data, u8 id)
313 {
314 	struct crypto_hash *hash = NULL;
315 	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
316 	u16 grp;
317 	size_t prime_len, order_len;
318 
319 	wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
320 	/*
321 	 * if we're fragmenting then we already have an confirm request, just
322 	 * return
323 	 */
324 	if (data->out_frag_pos)
325 		return;
326 
327 	prime_len = crypto_ec_prime_len(data->grp->group);
328 	order_len = crypto_ec_order_len(data->grp->group);
329 
330 	/* Each component of the cruft will be at most as big as the prime */
331 	cruft = os_malloc(prime_len * 2);
332 	if (!cruft) {
333 		wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
334 			   "fail");
335 		goto fin;
336 	}
337 
338 	/*
339 	 * commit is H(k | server_element | server_scalar | peer_element |
340 	 *	       peer_scalar | ciphersuite)
341 	 */
342 	hash = eap_pwd_h_init();
343 	if (hash == NULL)
344 		goto fin;
345 
346 	/*
347 	 * Zero the memory each time because this is mod prime math and some
348 	 * value may start with a few zeros and the previous one did not.
349 	 *
350 	 * First is k
351 	 */
352 	crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
353 	eap_pwd_h_update(hash, cruft, prime_len);
354 
355 	/* server element: x, y */
356 	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
357 				   cruft + prime_len) < 0) {
358 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
359 			   "assignment fail");
360 		goto fin;
361 	}
362 	eap_pwd_h_update(hash, cruft, prime_len * 2);
363 
364 	/* server scalar */
365 	crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
366 	eap_pwd_h_update(hash, cruft, order_len);
367 
368 	/* peer element: x, y */
369 	if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
370 				   cruft + prime_len) < 0) {
371 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
372 			   "assignment fail");
373 		goto fin;
374 	}
375 	eap_pwd_h_update(hash, cruft, prime_len * 2);
376 
377 	/* peer scalar */
378 	crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
379 	eap_pwd_h_update(hash, cruft, order_len);
380 
381 	/* ciphersuite */
382 	grp = htons(data->group_num);
383 	os_memset(cruft, 0, prime_len);
384 	ptr = cruft;
385 	os_memcpy(ptr, &grp, sizeof(u16));
386 	ptr += sizeof(u16);
387 	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
388 	ptr += sizeof(u8);
389 	*ptr = EAP_PWD_DEFAULT_PRF;
390 	ptr += sizeof(u8);
391 	eap_pwd_h_update(hash, cruft, ptr - cruft);
392 
393 	/* all done with the random function */
394 	eap_pwd_h_final(hash, conf);
395 	hash = NULL;
396 	os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
397 
398 	data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
399 	if (data->outbuf == NULL)
400 		goto fin;
401 
402 	wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
403 
404 fin:
405 	bin_clear_free(cruft, prime_len * 2);
406 	if (data->outbuf == NULL)
407 		eap_pwd_state(data, FAILURE);
408 	eap_pwd_h_final(hash, NULL);
409 }
410 
411 
412 static struct wpabuf *
eap_pwd_build_req(struct eap_sm * sm,void * priv,u8 id)413 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
414 {
415 	struct eap_pwd_data *data = priv;
416 	struct wpabuf *req;
417 	u8 lm_exch;
418 	const u8 *buf;
419 	u16 totlen = 0;
420 	size_t len;
421 
422 	/*
423 	 * if we're buffering response fragments then just ACK
424 	 */
425 	if (data->in_frag_pos) {
426 		wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
427 		req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
428 				    EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
429 		if (req == NULL) {
430 			eap_pwd_state(data, FAILURE);
431 			return NULL;
432 		}
433 		switch (data->state) {
434 		case PWD_ID_Req:
435 			wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
436 			break;
437 		case PWD_Commit_Req:
438 			wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
439 			break;
440 		case PWD_Confirm_Req:
441 			wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
442 			break;
443 		default:
444 			eap_pwd_state(data, FAILURE);   /* just to be sure */
445 			wpabuf_free(req);
446 			return NULL;
447 		}
448 		return req;
449 	}
450 
451 	/*
452 	 * build the data portion of a request
453 	 */
454 	switch (data->state) {
455 	case PWD_ID_Req:
456 		eap_pwd_build_id_req(sm, data, id);
457 		lm_exch = EAP_PWD_OPCODE_ID_EXCH;
458 		break;
459 	case PWD_Commit_Req:
460 		eap_pwd_build_commit_req(sm, data, id);
461 		lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
462 		break;
463 	case PWD_Confirm_Req:
464 		eap_pwd_build_confirm_req(sm, data, id);
465 		lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
466 		break;
467 	default:
468 		wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
469 			   data->state);
470 		eap_pwd_state(data, FAILURE);
471 		lm_exch = 0;    /* hush now, sweet compiler */
472 		break;
473 	}
474 
475 	if (data->state == FAILURE)
476 		return NULL;
477 
478 	/*
479 	 * determine whether that data needs to be fragmented
480 	 */
481 	len = wpabuf_len(data->outbuf) - data->out_frag_pos;
482 	if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
483 		len = data->mtu - EAP_PWD_HDR_SIZE;
484 		EAP_PWD_SET_MORE_BIT(lm_exch);
485 		/*
486 		 * if this is the first fragment, need to set the M bit
487 		 * and add the total length to the eap_pwd_hdr
488 		 */
489 		if (data->out_frag_pos == 0) {
490 			EAP_PWD_SET_LENGTH_BIT(lm_exch);
491 			totlen = wpabuf_len(data->outbuf) +
492 				EAP_PWD_HDR_SIZE + sizeof(u16);
493 			len -= sizeof(u16);
494 			wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
495 				   "total length = %d", totlen);
496 		}
497 		wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
498 			   (int) len);
499 	}
500 
501 	/*
502 	 * alloc an eap request and populate it with the data
503 	 */
504 	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
505 			    EAP_PWD_HDR_SIZE + len +
506 			    (totlen ? sizeof(u16) : 0),
507 			    EAP_CODE_REQUEST, id);
508 	if (req == NULL) {
509 		eap_pwd_state(data, FAILURE);
510 		return NULL;
511 	}
512 
513 	wpabuf_put_u8(req, lm_exch);
514 	if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
515 		wpabuf_put_be16(req, totlen);
516 
517 	buf = wpabuf_head_u8(data->outbuf);
518 	wpabuf_put_data(req, buf + data->out_frag_pos, len);
519 	data->out_frag_pos += len;
520 	/*
521 	 * either not fragged or last fragment, either way free up the data
522 	 */
523 	if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
524 		wpabuf_free(data->outbuf);
525 		data->outbuf = NULL;
526 		data->out_frag_pos = 0;
527 	}
528 
529 	return req;
530 }
531 
532 
eap_pwd_check(struct eap_sm * sm,void * priv,struct wpabuf * respData)533 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
534 			     struct wpabuf *respData)
535 {
536 	struct eap_pwd_data *data = priv;
537 	const u8 *pos;
538 	size_t len;
539 
540 	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
541 	if (pos == NULL || len < 1) {
542 		wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
543 		return TRUE;
544 	}
545 
546 	wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
547 		   EAP_PWD_GET_EXCHANGE(*pos), (int) len);
548 
549 	if (data->state == PWD_ID_Req &&
550 	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
551 		return FALSE;
552 
553 	if (data->state == PWD_Commit_Req &&
554 	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
555 		return FALSE;
556 
557 	if (data->state == PWD_Confirm_Req &&
558 	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
559 		return FALSE;
560 
561 	wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
562 		   *pos, data->state);
563 
564 	return TRUE;
565 }
566 
567 
eap_pwd_process_id_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)568 static void eap_pwd_process_id_resp(struct eap_sm *sm,
569 				    struct eap_pwd_data *data,
570 				    const u8 *payload, size_t payload_len)
571 {
572 	struct eap_pwd_id *id;
573 	const u8 *password;
574 	size_t password_len;
575 	u8 pwhashhash[16];
576 	int res;
577 
578 	if (payload_len < sizeof(struct eap_pwd_id)) {
579 		wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
580 		return;
581 	}
582 
583 	id = (struct eap_pwd_id *) payload;
584 	if ((data->group_num != be_to_host16(id->group_num)) ||
585 	    (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
586 	    (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
587 	    (id->prf != EAP_PWD_DEFAULT_PRF) ||
588 	    (id->prep != data->password_prep)) {
589 		wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
590 		eap_pwd_state(data, FAILURE);
591 		return;
592 	}
593 	if (data->id_peer || data->grp) {
594 		wpa_printf(MSG_INFO, "EAP-pwd: data was already allocated");
595 		return;
596 	}
597 	data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
598 	if (data->id_peer == NULL) {
599 		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
600 		return;
601 	}
602 	data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
603 	os_memcpy(data->id_peer, id->identity, data->id_peer_len);
604 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
605 			  data->id_peer, data->id_peer_len);
606 
607 	data->grp = get_eap_pwd_group(data->group_num);
608 	if (data->grp == NULL) {
609 		wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
610 			   "group");
611 		return;
612 	}
613 
614 	/*
615 	 * If it's PREP_MS then hash the password again, otherwise regardless
616 	 * of the prep the client is doing, the password we have is the one to
617 	 * use to generate the password element.
618 	 */
619 	if (data->password_prep == EAP_PWD_PREP_MS) {
620 		res = hash_nt_password_hash(data->password, pwhashhash);
621 		if (res)
622 			return;
623 		password = pwhashhash;
624 		password_len = sizeof(pwhashhash);
625 	} else {
626 		password = data->password;
627 		password_len = data->password_len;
628 	}
629 
630 	res = compute_password_element(data->grp, data->group_num,
631 				       password, password_len,
632 				       data->id_server, data->id_server_len,
633 				       data->id_peer, data->id_peer_len,
634 				       (u8 *) &data->token);
635 	forced_memzero(pwhashhash, sizeof(pwhashhash));
636 	if (res) {
637 		wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
638 			   "PWE");
639 		return;
640 	}
641 	wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
642 		   (int) crypto_ec_prime_len_bits(data->grp->group));
643 
644 	eap_pwd_state(data, PWD_Commit_Req);
645 }
646 
647 
648 static void
eap_pwd_process_commit_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)649 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
650 			    const u8 *payload, size_t payload_len)
651 {
652 	const u8 *ptr;
653 	struct crypto_ec_point *K = NULL;
654 	int res = 0;
655 	size_t prime_len, order_len;
656 
657 	wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
658 
659 	prime_len = crypto_ec_prime_len(data->grp->group);
660 	order_len = crypto_ec_order_len(data->grp->group);
661 
662 	if (payload_len != 2 * prime_len + order_len) {
663 		wpa_printf(MSG_INFO,
664 			   "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
665 			   (unsigned int) payload_len,
666 			   (unsigned int) (2 * prime_len + order_len));
667 		goto fin;
668 	}
669 
670 	data->k = crypto_bignum_init();
671 	K = crypto_ec_point_init(data->grp->group);
672 	if (!data->k || !K) {
673 		wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
674 			   "fail");
675 		goto fin;
676 	}
677 
678 	/* element, x then y, followed by scalar */
679 	ptr = payload;
680 	data->peer_element = eap_pwd_get_element(data->grp, ptr);
681 	if (!data->peer_element) {
682 		wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
683 			   "fail");
684 		goto fin;
685 	}
686 	ptr += prime_len * 2;
687 	data->peer_scalar = eap_pwd_get_scalar(data->grp, ptr);
688 	if (!data->peer_scalar) {
689 		wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
690 			   "fail");
691 		goto fin;
692 	}
693 
694 	/* detect reflection attacks */
695 	if (crypto_bignum_cmp(data->my_scalar, data->peer_scalar) == 0 ||
696 	    crypto_ec_point_cmp(data->grp->group, data->my_element,
697 				data->peer_element) == 0) {
698 		wpa_printf(MSG_INFO,
699 			   "EAP-PWD (server): detected reflection attack!");
700 		goto fin;
701 	}
702 
703 	/* compute the shared key, k */
704 	if ((crypto_ec_point_mul(data->grp->group, data->grp->pwe,
705 				 data->peer_scalar, K) < 0) ||
706 	    (crypto_ec_point_add(data->grp->group, K, data->peer_element,
707 				 K) < 0) ||
708 	    (crypto_ec_point_mul(data->grp->group, K, data->private_value,
709 				 K) < 0)) {
710 		wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
711 			   "fail");
712 		goto fin;
713 	}
714 
715 	/*
716 	 * This check is strictly speaking just for the case where
717 	 * co-factor > 1 but it was suggested that even though this is probably
718 	 * never going to happen it is a simple and safe check "just to be
719 	 * sure" so let's be safe.
720 	 */
721 	if (crypto_ec_point_is_at_infinity(data->grp->group, K)) {
722 		wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
723 			   "at infinity");
724 		goto fin;
725 	}
726 	if (crypto_ec_point_x(data->grp->group, K, data->k)) {
727 		wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
728 			   "shared secret from secret point");
729 		goto fin;
730 	}
731 	res = 1;
732 
733 fin:
734 	crypto_ec_point_deinit(K, 1);
735 
736 	if (res)
737 		eap_pwd_state(data, PWD_Confirm_Req);
738 	else
739 		eap_pwd_state(data, FAILURE);
740 }
741 
742 
743 static void
eap_pwd_process_confirm_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)744 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
745 			     const u8 *payload, size_t payload_len)
746 {
747 	struct crypto_hash *hash = NULL;
748 	u32 cs;
749 	u16 grp;
750 	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
751 	size_t prime_len, order_len;
752 
753 	prime_len = crypto_ec_prime_len(data->grp->group);
754 	order_len = crypto_ec_order_len(data->grp->group);
755 
756 	if (payload_len != SHA256_MAC_LEN) {
757 		wpa_printf(MSG_INFO,
758 			   "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
759 			   (unsigned int) payload_len, SHA256_MAC_LEN);
760 		goto fin;
761 	}
762 
763 	/* build up the ciphersuite: group | random_function | prf */
764 	grp = htons(data->group_num);
765 	ptr = (u8 *) &cs;
766 	os_memcpy(ptr, &grp, sizeof(u16));
767 	ptr += sizeof(u16);
768 	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
769 	ptr += sizeof(u8);
770 	*ptr = EAP_PWD_DEFAULT_PRF;
771 
772 	/* each component of the cruft will be at most as big as the prime */
773 	cruft = os_malloc(prime_len * 2);
774 	if (!cruft) {
775 		wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
776 		goto fin;
777 	}
778 
779 	/*
780 	 * commit is H(k | peer_element | peer_scalar | server_element |
781 	 *	       server_scalar | ciphersuite)
782 	 */
783 	hash = eap_pwd_h_init();
784 	if (hash == NULL)
785 		goto fin;
786 
787 	/* k */
788 	crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
789 	eap_pwd_h_update(hash, cruft, prime_len);
790 
791 	/* peer element: x, y */
792 	if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
793 				   cruft + prime_len) < 0) {
794 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
795 			   "assignment fail");
796 		goto fin;
797 	}
798 	eap_pwd_h_update(hash, cruft, prime_len * 2);
799 
800 	/* peer scalar */
801 	crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
802 	eap_pwd_h_update(hash, cruft, order_len);
803 
804 	/* server element: x, y */
805 	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
806 				   cruft + prime_len) < 0) {
807 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
808 			   "assignment fail");
809 		goto fin;
810 	}
811 	eap_pwd_h_update(hash, cruft, prime_len * 2);
812 
813 	/* server scalar */
814 	crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
815 	eap_pwd_h_update(hash, cruft, order_len);
816 
817 	/* ciphersuite */
818 	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
819 
820 	/* all done */
821 	eap_pwd_h_final(hash, conf);
822 	hash = NULL;
823 
824 	ptr = (u8 *) payload;
825 	if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
826 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
827 			   "verify");
828 		goto fin;
829 	}
830 
831 	wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
832 	if (compute_keys(data->grp, data->k,
833 			 data->peer_scalar, data->my_scalar, conf,
834 			 data->my_confirm, &cs, data->msk, data->emsk,
835 			 data->session_id) < 0)
836 		eap_pwd_state(data, FAILURE);
837 	else
838 		eap_pwd_state(data, SUCCESS);
839 
840 fin:
841 	bin_clear_free(cruft, prime_len * 2);
842 	eap_pwd_h_final(hash, NULL);
843 }
844 
845 
eap_pwd_process(struct eap_sm * sm,void * priv,struct wpabuf * respData)846 static void eap_pwd_process(struct eap_sm *sm, void *priv,
847 			    struct wpabuf *respData)
848 {
849 	struct eap_pwd_data *data = priv;
850 	const u8 *pos;
851 	size_t len;
852 	u8 lm_exch;
853 	u16 tot_len;
854 
855 	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
856 	if ((pos == NULL) || (len < 1)) {
857 		wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
858 			   (pos == NULL) ? "is NULL" : "is not NULL",
859 			   (int) len);
860 		return;
861 	}
862 
863 	lm_exch = *pos;
864 	pos++;            /* skip over the bits and the exch */
865 	len--;
866 
867 	/*
868 	 * if we're fragmenting then this should be an ACK with no data,
869 	 * just return and continue fragmenting in the "build" section above
870 	 */
871 	if (data->out_frag_pos) {
872 		if (len > 1)
873 			wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
874 				   "Fragmenting but not an ACK");
875 		else
876 			wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
877 				   "peer");
878 		return;
879 	}
880 	/*
881 	 * if we're receiving fragmented packets then we need to buffer...
882 	 *
883 	 * the first fragment has a total length
884 	 */
885 	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
886 		if (len < 2) {
887 			wpa_printf(MSG_DEBUG,
888 				   "EAP-pwd: Frame too short to contain Total-Length field");
889 			return;
890 		}
891 		tot_len = WPA_GET_BE16(pos);
892 		wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
893 			   "length = %d", tot_len);
894 		if (tot_len > 15000)
895 			return;
896 		if (data->inbuf) {
897 			wpa_printf(MSG_DEBUG,
898 				   "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
899 			return;
900 		}
901 		data->inbuf = wpabuf_alloc(tot_len);
902 		if (data->inbuf == NULL) {
903 			wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
904 				   "buffer fragments!");
905 			return;
906 		}
907 		data->in_frag_pos = 0;
908 		pos += sizeof(u16);
909 		len -= sizeof(u16);
910 	}
911 	/*
912 	 * the first and all intermediate fragments have the M bit set
913 	 */
914 	if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
915 		if (!data->inbuf) {
916 			wpa_printf(MSG_DEBUG,
917 				   "EAP-pwd: No buffer for reassembly");
918 			eap_pwd_state(data, FAILURE);
919 			return;
920 		}
921 		if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
922 			wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
923 				   "attack detected! (%d+%d > %d)",
924 				   (int) data->in_frag_pos, (int) len,
925 				   (int) wpabuf_size(data->inbuf));
926 			eap_pwd_state(data, FAILURE);
927 			return;
928 		}
929 		wpabuf_put_data(data->inbuf, pos, len);
930 		data->in_frag_pos += len;
931 	}
932 	if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
933 		wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
934 			   (int) len);
935 		return;
936 	}
937 	/*
938 	 * last fragment won't have the M bit set (but we're obviously
939 	 * buffering fragments so that's how we know it's the last)
940 	 */
941 	if (data->in_frag_pos && data->inbuf) {
942 		pos = wpabuf_head_u8(data->inbuf);
943 		len = data->in_frag_pos;
944 		wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
945 			   (int) len);
946 	}
947 	switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
948 	case EAP_PWD_OPCODE_ID_EXCH:
949 		eap_pwd_process_id_resp(sm, data, pos, len);
950 		break;
951 	case EAP_PWD_OPCODE_COMMIT_EXCH:
952 		eap_pwd_process_commit_resp(sm, data, pos, len);
953 		break;
954 	case EAP_PWD_OPCODE_CONFIRM_EXCH:
955 		eap_pwd_process_confirm_resp(sm, data, pos, len);
956 		break;
957 	}
958 	/*
959 	 * if we had been buffering fragments, here's a great place
960 	 * to clean up
961 	 */
962 	if (data->in_frag_pos) {
963 		wpabuf_free(data->inbuf);
964 		data->inbuf = NULL;
965 		data->in_frag_pos = 0;
966 	}
967 }
968 
969 
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)970 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
971 {
972 	struct eap_pwd_data *data = priv;
973 	u8 *key;
974 
975 	if (data->state != SUCCESS)
976 		return NULL;
977 
978 	key = os_memdup(data->msk, EAP_MSK_LEN);
979 	if (key == NULL)
980 		return NULL;
981 
982 	*len = EAP_MSK_LEN;
983 
984 	return key;
985 }
986 
987 
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)988 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
989 {
990 	struct eap_pwd_data *data = priv;
991 	u8 *key;
992 
993 	if (data->state != SUCCESS)
994 		return NULL;
995 
996 	key = os_memdup(data->emsk, EAP_EMSK_LEN);
997 	if (key == NULL)
998 		return NULL;
999 
1000 	*len = EAP_EMSK_LEN;
1001 
1002 	return key;
1003 }
1004 
1005 
eap_pwd_is_success(struct eap_sm * sm,void * priv)1006 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1007 {
1008 	struct eap_pwd_data *data = priv;
1009 	return data->state == SUCCESS;
1010 }
1011 
1012 
eap_pwd_is_done(struct eap_sm * sm,void * priv)1013 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1014 {
1015 	struct eap_pwd_data *data = priv;
1016 	return (data->state == SUCCESS) || (data->state == FAILURE);
1017 }
1018 
1019 
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)1020 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1021 {
1022 	struct eap_pwd_data *data = priv;
1023 	u8 *id;
1024 
1025 	if (data->state != SUCCESS)
1026 		return NULL;
1027 
1028 	id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN);
1029 	if (id == NULL)
1030 		return NULL;
1031 
1032 	*len = 1 + SHA256_MAC_LEN;
1033 
1034 	return id;
1035 }
1036 
1037 
eap_server_pwd_register(void)1038 int eap_server_pwd_register(void)
1039 {
1040 	struct eap_method *eap;
1041 
1042 	eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1043 				      EAP_VENDOR_IETF, EAP_TYPE_PWD,
1044 				      "PWD");
1045 	if (eap == NULL)
1046 		return -1;
1047 
1048 	eap->init = eap_pwd_init;
1049 	eap->reset = eap_pwd_reset;
1050 	eap->buildReq = eap_pwd_build_req;
1051 	eap->check = eap_pwd_check;
1052 	eap->process = eap_pwd_process;
1053 	eap->isDone = eap_pwd_is_done;
1054 	eap->getKey = eap_pwd_getkey;
1055 	eap->get_emsk = eap_pwd_get_emsk;
1056 	eap->isSuccess = eap_pwd_is_success;
1057 	eap->getSessionId = eap_pwd_get_session_id;
1058 
1059 	return eap_server_method_register(eap);
1060 }
1061