xref: /freebsd/contrib/wpa/src/eap_peer/eap_pwd.c (revision 3b8f08459569bf0faa21473e5cec2491e95c9349)
1 /*
2  * EAP peer method: EAP-pwd (RFC 5931)
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 "eap_peer/eap_i.h"
14 #include "eap_common/eap_pwd_common.h"
15 
16 
17 struct eap_pwd_data {
18 	enum {
19 		PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
20 	} state;
21 	u8 *id_peer;
22 	size_t id_peer_len;
23 	u8 *id_server;
24 	size_t id_server_len;
25 	u8 *password;
26 	size_t password_len;
27 	u16 group_num;
28 	EAP_PWD_group *grp;
29 
30 	struct wpabuf *inbuf;
31 	size_t in_frag_pos;
32 	struct wpabuf *outbuf;
33 	size_t out_frag_pos;
34 	size_t mtu;
35 
36 	BIGNUM *k;
37 	BIGNUM *private_value;
38 	BIGNUM *server_scalar;
39 	BIGNUM *my_scalar;
40 	EC_POINT *my_element;
41 	EC_POINT *server_element;
42 
43 	u8 msk[EAP_MSK_LEN];
44 	u8 emsk[EAP_EMSK_LEN];
45 
46 	BN_CTX *bnctx;
47 };
48 
49 
50 #ifndef CONFIG_NO_STDOUT_DEBUG
51 static const char * eap_pwd_state_txt(int state)
52 {
53 	switch (state) {
54         case PWD_ID_Req:
55 		return "PWD-ID-Req";
56         case PWD_Commit_Req:
57 		return "PWD-Commit-Req";
58         case PWD_Confirm_Req:
59 		return "PWD-Confirm-Req";
60         case SUCCESS:
61 		return "SUCCESS";
62         case FAILURE:
63 		return "FAILURE";
64         default:
65 		return "PWD-UNK";
66 	}
67 }
68 #endif  /* CONFIG_NO_STDOUT_DEBUG */
69 
70 
71 static void eap_pwd_state(struct eap_pwd_data *data, int state)
72 {
73 	wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s",
74 		   eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
75 	data->state = state;
76 }
77 
78 
79 static void * eap_pwd_init(struct eap_sm *sm)
80 {
81 	struct eap_pwd_data *data;
82 	const u8 *identity, *password;
83 	size_t identity_len, password_len;
84 
85 	password = eap_get_config_password(sm, &password_len);
86 	if (password == NULL) {
87 		wpa_printf(MSG_INFO, "EAP-PWD: No password configured!");
88 		return NULL;
89 	}
90 
91 	identity = eap_get_config_identity(sm, &identity_len);
92 	if (identity == NULL) {
93 		wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!");
94 		return NULL;
95 	}
96 
97 	if ((data = os_zalloc(sizeof(*data))) == NULL) {
98 		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail");
99 		return NULL;
100 	}
101 
102 	if ((data->bnctx = BN_CTX_new()) == NULL) {
103 		wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
104 		os_free(data);
105 		return NULL;
106 	}
107 
108 	if ((data->id_peer = os_malloc(identity_len)) == NULL) {
109 		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
110 		BN_CTX_free(data->bnctx);
111 		os_free(data);
112 		return NULL;
113 	}
114 
115 	os_memcpy(data->id_peer, identity, identity_len);
116 	data->id_peer_len = identity_len;
117 
118 	if ((data->password = os_malloc(password_len)) == NULL) {
119 		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail");
120 		BN_CTX_free(data->bnctx);
121 		os_free(data->id_peer);
122 		os_free(data);
123 		return NULL;
124 	}
125 	os_memcpy(data->password, password, password_len);
126 	data->password_len = password_len;
127 
128 	data->out_frag_pos = data->in_frag_pos = 0;
129 	data->inbuf = data->outbuf = NULL;
130 	data->mtu = 1020; /* default from RFC 5931, make it configurable! */
131 
132 	data->state = PWD_ID_Req;
133 
134 	return data;
135 }
136 
137 
138 static void eap_pwd_deinit(struct eap_sm *sm, void *priv)
139 {
140 	struct eap_pwd_data *data = priv;
141 
142 	BN_free(data->private_value);
143 	BN_free(data->server_scalar);
144 	BN_free(data->my_scalar);
145 	BN_free(data->k);
146 	BN_CTX_free(data->bnctx);
147 	EC_POINT_free(data->my_element);
148 	EC_POINT_free(data->server_element);
149 	os_free(data->id_peer);
150 	os_free(data->id_server);
151 	os_free(data->password);
152 	if (data->grp) {
153 		EC_GROUP_free(data->grp->group);
154 		EC_POINT_free(data->grp->pwe);
155 		BN_free(data->grp->order);
156 		BN_free(data->grp->prime);
157 		os_free(data->grp);
158 	}
159 	os_free(data);
160 }
161 
162 
163 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
164 {
165 	struct eap_pwd_data *data = priv;
166 	u8 *key;
167 
168 	if (data->state != SUCCESS)
169 		return NULL;
170 
171 	key = os_malloc(EAP_MSK_LEN);
172 	if (key == NULL)
173 		return NULL;
174 
175 	os_memcpy(key, data->msk, EAP_MSK_LEN);
176 	*len = EAP_MSK_LEN;
177 
178 	return key;
179 }
180 
181 
182 static void
183 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
184 			    struct eap_method_ret *ret,
185 			    const struct wpabuf *reqData,
186 			    const u8 *payload, size_t payload_len)
187 {
188 	struct eap_pwd_id *id;
189 
190 	if (data->state != PWD_ID_Req) {
191 		ret->ignore = TRUE;
192 		eap_pwd_state(data, FAILURE);
193 		return;
194 	}
195 
196 	if (payload_len < sizeof(struct eap_pwd_id)) {
197 		ret->ignore = TRUE;
198 		eap_pwd_state(data, FAILURE);
199 		return;
200 	}
201 
202 	id = (struct eap_pwd_id *) payload;
203 	data->group_num = be_to_host16(id->group_num);
204 	if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
205 	    (id->prf != EAP_PWD_DEFAULT_PRF)) {
206 		ret->ignore = TRUE;
207 		eap_pwd_state(data, FAILURE);
208 		return;
209 	}
210 
211 	wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
212 		   data->group_num);
213 
214 	data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
215 	if (data->id_server == NULL) {
216 		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
217 		eap_pwd_state(data, FAILURE);
218 		return;
219 	}
220 	data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
221 	os_memcpy(data->id_server, id->identity, data->id_server_len);
222 	wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of",
223 			  data->id_server, data->id_server_len);
224 
225 	if ((data->grp = (EAP_PWD_group *) os_malloc(sizeof(EAP_PWD_group))) ==
226 	    NULL) {
227 		wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
228 			   "group");
229 		eap_pwd_state(data, FAILURE);
230 		return;
231 	}
232 
233 	/* compute PWE */
234 	if (compute_password_element(data->grp, data->group_num,
235 				     data->password, data->password_len,
236 				     data->id_server, data->id_server_len,
237 				     data->id_peer, data->id_peer_len,
238 				     id->token)) {
239 		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
240 		eap_pwd_state(data, FAILURE);
241 		return;
242 	}
243 
244 	wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
245 		   BN_num_bits(data->grp->prime));
246 
247 	data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
248 				    data->id_peer_len);
249 	if (data->outbuf == NULL) {
250 		eap_pwd_state(data, FAILURE);
251 		return;
252 	}
253 	wpabuf_put_be16(data->outbuf, data->group_num);
254 	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
255 	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
256 	wpabuf_put_data(data->outbuf, id->token, sizeof(id->token));
257 	wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
258 	wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
259 
260 	eap_pwd_state(data, PWD_Commit_Req);
261 }
262 
263 
264 static void
265 eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
266 				struct eap_method_ret *ret,
267 				const struct wpabuf *reqData,
268 				const u8 *payload, size_t payload_len)
269 {
270 	EC_POINT *K = NULL, *point = NULL;
271 	BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
272 	u16 offset;
273 	u8 *ptr, *scalar = NULL, *element = NULL;
274 
275 	if (((data->private_value = BN_new()) == NULL) ||
276 	    ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
277 	    ((cofactor = BN_new()) == NULL) ||
278 	    ((data->my_scalar = BN_new()) == NULL) ||
279 	    ((mask = BN_new()) == NULL)) {
280 		wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail");
281 		goto fin;
282 	}
283 
284 	if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
285 		wpa_printf(MSG_INFO, "EAP-pwd (peer): unable to get cofactor "
286 			   "for curve");
287 		goto fin;
288 	}
289 
290 	BN_rand_range(data->private_value, data->grp->order);
291 	BN_rand_range(mask, data->grp->order);
292 	BN_add(data->my_scalar, data->private_value, mask);
293 	BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
294 	       data->bnctx);
295 
296 	if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
297 			  data->grp->pwe, mask, data->bnctx)) {
298 		wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation "
299 			   "fail");
300 		eap_pwd_state(data, FAILURE);
301 		goto fin;
302 	}
303 
304 	if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
305 	{
306 		wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail");
307 		goto fin;
308 	}
309 	BN_free(mask);
310 
311 	if (((x = BN_new()) == NULL) ||
312 	    ((y = BN_new()) == NULL)) {
313 		wpa_printf(MSG_INFO, "EAP-PWD (peer): point allocation fail");
314 		goto fin;
315 	}
316 
317 	/* process the request */
318 	if (((data->server_scalar = BN_new()) == NULL) ||
319 	    ((data->k = BN_new()) == NULL) ||
320 	    ((K = EC_POINT_new(data->grp->group)) == NULL) ||
321 	    ((point = EC_POINT_new(data->grp->group)) == NULL) ||
322 	    ((data->server_element = EC_POINT_new(data->grp->group)) == NULL))
323 	{
324 		wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation "
325 			   "fail");
326 		goto fin;
327 	}
328 
329 	/* element, x then y, followed by scalar */
330 	ptr = (u8 *) payload;
331 	BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
332 	ptr += BN_num_bytes(data->grp->prime);
333 	BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
334 	ptr += BN_num_bytes(data->grp->prime);
335 	BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->server_scalar);
336 	if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
337 						 data->server_element, x, y,
338 						 data->bnctx)) {
339 		wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element "
340 			   "fail");
341 		goto fin;
342 	}
343 
344 	/* check to ensure server's element is not in a small sub-group */
345 	if (BN_cmp(cofactor, BN_value_one())) {
346 		if (!EC_POINT_mul(data->grp->group, point, NULL,
347 				  data->server_element, cofactor, NULL)) {
348 			wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
349 				   "server element by order!\n");
350 			goto fin;
351 		}
352 		if (EC_POINT_is_at_infinity(data->grp->group, point)) {
353 			wpa_printf(MSG_INFO, "EAP-PWD (peer): server element "
354 				   "is at infinity!\n");
355 			goto fin;
356 		}
357 	}
358 
359 	/* compute the shared key, k */
360 	if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
361 			   data->server_scalar, data->bnctx)) ||
362 	    (!EC_POINT_add(data->grp->group, K, K, data->server_element,
363 			   data->bnctx)) ||
364 	    (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
365 			   data->bnctx))) {
366 		wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key "
367 			   "fail");
368 		goto fin;
369 	}
370 
371 	/* ensure that the shared key isn't in a small sub-group */
372 	if (BN_cmp(cofactor, BN_value_one())) {
373 		if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
374 				  NULL)) {
375 			wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
376 				   "shared key point by order");
377 			goto fin;
378 		}
379 	}
380 
381 	/*
382 	 * This check is strictly speaking just for the case above where
383 	 * co-factor > 1 but it was suggested that even though this is probably
384 	 * never going to happen it is a simple and safe check "just to be
385 	 * sure" so let's be safe.
386 	 */
387 	if (EC_POINT_is_at_infinity(data->grp->group, K)) {
388 		wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at "
389 			   "infinity!\n");
390 		goto fin;
391 	}
392 
393 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
394 						 NULL, data->bnctx)) {
395 		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract "
396 			   "shared secret from point");
397 		goto fin;
398 	}
399 
400 	/* now do the response */
401 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
402 						 data->my_element, x, y,
403 						 data->bnctx)) {
404 		wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail");
405 		goto fin;
406 	}
407 
408 	if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
409 	    ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
410 	     NULL)) {
411 		wpa_printf(MSG_INFO, "EAP-PWD (peer): data allocation fail");
412 		goto fin;
413 	}
414 
415 	/*
416 	 * bignums occupy as little memory as possible so one that is
417 	 * sufficiently smaller than the prime or order might need pre-pending
418 	 * with zeros.
419 	 */
420 	os_memset(scalar, 0, BN_num_bytes(data->grp->order));
421 	os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
422 	offset = BN_num_bytes(data->grp->order) -
423 		BN_num_bytes(data->my_scalar);
424 	BN_bn2bin(data->my_scalar, scalar + offset);
425 
426 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
427 	BN_bn2bin(x, element + offset);
428 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
429 	BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
430 
431 	data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) +
432 				    2 * BN_num_bytes(data->grp->prime));
433 	if (data->outbuf == NULL)
434 		goto fin;
435 
436 	/* we send the element as (x,y) follwed by the scalar */
437 	wpabuf_put_data(data->outbuf, element,
438 			2 * BN_num_bytes(data->grp->prime));
439 	wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
440 
441 fin:
442 	os_free(scalar);
443 	os_free(element);
444 	BN_free(x);
445 	BN_free(y);
446 	BN_free(cofactor);
447 	EC_POINT_free(K);
448 	EC_POINT_free(point);
449 	if (data->outbuf == NULL)
450 		eap_pwd_state(data, FAILURE);
451 	else
452 		eap_pwd_state(data, PWD_Confirm_Req);
453 }
454 
455 
456 static void
457 eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
458 				 struct eap_method_ret *ret,
459 				 const struct wpabuf *reqData,
460 				 const u8 *payload, size_t payload_len)
461 {
462 	BIGNUM *x = NULL, *y = NULL;
463 	struct crypto_hash *hash;
464 	u32 cs;
465 	u16 grp;
466 	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
467 	int offset;
468 
469 	/*
470 	 * first build up the ciphersuite which is group | random_function |
471 	 *	prf
472 	 */
473 	grp = htons(data->group_num);
474 	ptr = (u8 *) &cs;
475 	os_memcpy(ptr, &grp, sizeof(u16));
476 	ptr += sizeof(u16);
477 	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
478 	ptr += sizeof(u8);
479 	*ptr = EAP_PWD_DEFAULT_PRF;
480 
481 	/* each component of the cruft will be at most as big as the prime */
482 	if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
483 	    ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
484 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
485 			   "fail");
486 		goto fin;
487 	}
488 
489 	/*
490 	 * server's commit is H(k | server_element | server_scalar |
491 	 *			peer_element | peer_scalar | ciphersuite)
492 	 */
493 	hash = eap_pwd_h_init();
494 	if (hash == NULL)
495 		goto fin;
496 
497 	/*
498 	 * zero the memory each time because this is mod prime math and some
499 	 * value may start with a few zeros and the previous one did not.
500 	 */
501 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
502 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
503 	BN_bn2bin(data->k, cruft + offset);
504 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
505 
506 	/* server element: x, y */
507 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
508 						 data->server_element, x, y,
509 						 data->bnctx)) {
510 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
511 			   "assignment fail");
512 		goto fin;
513 	}
514 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
515 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
516 	BN_bn2bin(x, cruft + offset);
517 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
518 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
519 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
520 	BN_bn2bin(y, cruft + offset);
521 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
522 
523 	/* server scalar */
524 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
525 	offset = BN_num_bytes(data->grp->order) -
526 		BN_num_bytes(data->server_scalar);
527 	BN_bn2bin(data->server_scalar, cruft + offset);
528 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
529 
530 	/* my element: x, y */
531 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
532 						 data->my_element, x, y,
533 						 data->bnctx)) {
534 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
535 			   "assignment fail");
536 		goto fin;
537 	}
538 
539 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
540 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
541 	BN_bn2bin(x, cruft + offset);
542 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
543 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
544 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
545 	BN_bn2bin(y, cruft + offset);
546 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
547 
548 	/* my scalar */
549 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
550 	offset = BN_num_bytes(data->grp->order) -
551 		BN_num_bytes(data->my_scalar);
552 	BN_bn2bin(data->my_scalar, cruft + offset);
553 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
554 
555 	/* the ciphersuite */
556 	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
557 
558 	/* random function fin */
559 	eap_pwd_h_final(hash, conf);
560 
561 	ptr = (u8 *) payload;
562 	if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) {
563 		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
564 		goto fin;
565 	}
566 
567 	wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified");
568 
569 	/*
570 	 * compute confirm:
571 	 *  H(k | peer_element | peer_scalar | server_element | server_scalar |
572 	 *    ciphersuite)
573 	 */
574 	hash = eap_pwd_h_init();
575 	if (hash == NULL)
576 		goto fin;
577 
578 	/* k */
579 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
580 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
581 	BN_bn2bin(data->k, cruft + offset);
582 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
583 
584 	/* my element */
585 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
586 						 data->my_element, x, y,
587 						 data->bnctx)) {
588 		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
589 			   "assignment fail");
590 		goto fin;
591 	}
592 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
593 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
594 	BN_bn2bin(x, cruft + offset);
595 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
596 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
597 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
598 	BN_bn2bin(y, cruft + offset);
599 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
600 
601 	/* my scalar */
602 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
603 	offset = BN_num_bytes(data->grp->order) -
604 		BN_num_bytes(data->my_scalar);
605 	BN_bn2bin(data->my_scalar, cruft + offset);
606 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
607 
608 	/* server element: x, y */
609 	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
610 						 data->server_element, x, y,
611 						 data->bnctx)) {
612 		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
613 			   "assignment fail");
614 		goto fin;
615 	}
616 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
617 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
618 	BN_bn2bin(x, cruft + offset);
619 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
620 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
621 	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
622 	BN_bn2bin(y, cruft + offset);
623 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
624 
625 	/* server scalar */
626 	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
627 	offset = BN_num_bytes(data->grp->order) -
628 		BN_num_bytes(data->server_scalar);
629 	BN_bn2bin(data->server_scalar, cruft + offset);
630 	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
631 
632 	/* the ciphersuite */
633 	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
634 
635 	/* all done */
636 	eap_pwd_h_final(hash, conf);
637 
638 	if (compute_keys(data->grp, data->bnctx, data->k,
639 			 data->my_scalar, data->server_scalar, conf, ptr,
640 			 &cs, data->msk, data->emsk) < 0) {
641 		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
642 			   "EMSK");
643 		goto fin;
644 	}
645 
646 	data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
647 	if (data->outbuf == NULL)
648 		goto fin;
649 
650 	wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
651 
652 fin:
653 	os_free(cruft);
654 	BN_free(x);
655 	BN_free(y);
656 	ret->methodState = METHOD_DONE;
657 	if (data->outbuf == NULL) {
658 		ret->decision = DECISION_FAIL;
659 		eap_pwd_state(data, FAILURE);
660 	} else {
661 		ret->decision = DECISION_UNCOND_SUCC;
662 		eap_pwd_state(data, SUCCESS);
663 	}
664 }
665 
666 
667 static struct wpabuf *
668 eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
669 		const struct wpabuf *reqData)
670 {
671 	struct eap_pwd_data *data = priv;
672 	struct wpabuf *resp = NULL;
673 	const u8 *pos, *buf;
674 	size_t len;
675 	u16 tot_len = 0;
676 	u8 lm_exch;
677 
678 	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
679 	if ((pos == NULL) || (len < 1)) {
680 		wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
681 			   "len is %d",
682 			   pos == NULL ? "NULL" : "not NULL", (int) len);
683 		ret->ignore = TRUE;
684 		return NULL;
685 	}
686 
687 	ret->ignore = FALSE;
688 	ret->methodState = METHOD_MAY_CONT;
689 	ret->decision = DECISION_FAIL;
690 	ret->allowNotifications = FALSE;
691 
692 	lm_exch = *pos;
693 	pos++;                  /* skip over the bits and the exch */
694 	len--;
695 
696 	/*
697 	 * we're fragmenting so send out the next fragment
698 	 */
699 	if (data->out_frag_pos) {
700 		/*
701 		 * this should be an ACK
702 		 */
703 		if (len)
704 			wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
705 				   "not an ACK");
706 
707 		wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
708 		/*
709 		 * check if there are going to be more fragments
710 		 */
711 		len = wpabuf_len(data->outbuf) - data->out_frag_pos;
712 		if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
713 			len = data->mtu - EAP_PWD_HDR_SIZE;
714 			EAP_PWD_SET_MORE_BIT(lm_exch);
715 		}
716 		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
717 				     EAP_PWD_HDR_SIZE + len,
718 				     EAP_CODE_RESPONSE, eap_get_id(reqData));
719 		if (resp == NULL) {
720 			wpa_printf(MSG_INFO, "Unable to allocate memory for "
721 				   "next fragment!");
722 			return NULL;
723 		}
724 		wpabuf_put_u8(resp, lm_exch);
725 		buf = wpabuf_head_u8(data->outbuf);
726 		wpabuf_put_data(resp, buf + data->out_frag_pos, len);
727 		data->out_frag_pos += len;
728 		/*
729 		 * this is the last fragment so get rid of the out buffer
730 		 */
731 		if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
732 			wpabuf_free(data->outbuf);
733 			data->outbuf = NULL;
734 			data->out_frag_pos = 0;
735 		}
736 		wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
737 			   data->out_frag_pos == 0 ? "last" : "next",
738 			   (int) len);
739 		return resp;
740 	}
741 
742 	/*
743 	 * see if this is a fragment that needs buffering
744 	 *
745 	 * if it's the first fragment there'll be a length field
746 	 */
747 	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
748 		tot_len = WPA_GET_BE16(pos);
749 		wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
750 			   "total length = %d", tot_len);
751 		data->inbuf = wpabuf_alloc(tot_len);
752 		if (data->inbuf == NULL) {
753 			wpa_printf(MSG_INFO, "Out of memory to buffer "
754 				   "fragments!");
755 			return NULL;
756 		}
757 		pos += sizeof(u16);
758 		len -= sizeof(u16);
759 	}
760 	/*
761 	 * buffer and ACK the fragment
762 	 */
763 	if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
764 		data->in_frag_pos += len;
765 		if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
766 			wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
767 				   "detected (%d vs. %d)!",
768 				   (int) data->in_frag_pos,
769 				   (int) wpabuf_len(data->inbuf));
770 			wpabuf_free(data->inbuf);
771 			data->in_frag_pos = 0;
772 			return NULL;
773 		}
774 		wpabuf_put_data(data->inbuf, pos, len);
775 
776 		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
777 				     EAP_PWD_HDR_SIZE,
778 				     EAP_CODE_RESPONSE, eap_get_id(reqData));
779 		if (resp != NULL)
780 			wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
781 		wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
782 			   (int) len);
783 		return resp;
784 	}
785 	/*
786 	 * we're buffering and this is the last fragment
787 	 */
788 	if (data->in_frag_pos) {
789 		wpabuf_put_data(data->inbuf, pos, len);
790 		wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
791 			   (int) len);
792 		data->in_frag_pos += len;
793 		pos = wpabuf_head_u8(data->inbuf);
794 		len = data->in_frag_pos;
795 	}
796 	wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
797 		   EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
798 
799 	switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
800 	case EAP_PWD_OPCODE_ID_EXCH:
801 		eap_pwd_perform_id_exchange(sm, data, ret, reqData,
802 					    pos, len);
803 		break;
804 	case EAP_PWD_OPCODE_COMMIT_EXCH:
805 		eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
806 						pos, len);
807 		break;
808 	case EAP_PWD_OPCODE_CONFIRM_EXCH:
809 		eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
810 						 pos, len);
811 		break;
812 	default:
813 		wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
814 			   "opcode %d", lm_exch);
815 		break;
816 	}
817 	/*
818 	 * if we buffered the just processed input now's the time to free it
819 	 */
820 	if (data->in_frag_pos) {
821 		wpabuf_free(data->inbuf);
822 		data->in_frag_pos = 0;
823 	}
824 
825 	if (data->outbuf == NULL)
826 		return NULL;        /* generic failure */
827 
828 	/*
829 	 * we have output! Do we need to fragment it?
830 	 */
831 	len = wpabuf_len(data->outbuf);
832 	if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
833 		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
834 				     EAP_CODE_RESPONSE, eap_get_id(reqData));
835 		/*
836 		 * if so it's the first so include a length field
837 		 */
838 		EAP_PWD_SET_LENGTH_BIT(lm_exch);
839 		EAP_PWD_SET_MORE_BIT(lm_exch);
840 		tot_len = len;
841 		/*
842 		 * keep the packet at the MTU
843 		 */
844 		len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
845 		wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
846 			   "length = %d", tot_len);
847 	} else {
848 		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
849 				     EAP_PWD_HDR_SIZE + len,
850 				     EAP_CODE_RESPONSE, eap_get_id(reqData));
851 	}
852 	if (resp == NULL)
853 		return NULL;
854 
855 	wpabuf_put_u8(resp, lm_exch);
856 	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
857 		wpabuf_put_be16(resp, tot_len);
858 		data->out_frag_pos += len;
859 	}
860 	buf = wpabuf_head_u8(data->outbuf);
861 	wpabuf_put_data(resp, buf, len);
862 	/*
863 	 * if we're not fragmenting then there's no need to carry this around
864 	 */
865 	if (data->out_frag_pos == 0) {
866 		wpabuf_free(data->outbuf);
867 		data->outbuf = NULL;
868 		data->out_frag_pos = 0;
869 	}
870 
871 	return resp;
872 }
873 
874 
875 static Boolean eap_pwd_key_available(struct eap_sm *sm, void *priv)
876 {
877 	struct eap_pwd_data *data = priv;
878 	return data->state == SUCCESS;
879 }
880 
881 
882 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
883 {
884 	struct eap_pwd_data *data = priv;
885 	u8 *key;
886 
887 	if (data->state != SUCCESS)
888 		return NULL;
889 
890 	if ((key = os_malloc(EAP_EMSK_LEN)) == NULL)
891 		return NULL;
892 
893 	os_memcpy(key, data->emsk, EAP_EMSK_LEN);
894 	*len = EAP_EMSK_LEN;
895 
896 	return key;
897 }
898 
899 
900 int eap_peer_pwd_register(void)
901 {
902 	struct eap_method *eap;
903 	int ret;
904 
905 	EVP_add_digest(EVP_sha256());
906 	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
907 				    EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD");
908 	if (eap == NULL)
909 		return -1;
910 
911 	eap->init = eap_pwd_init;
912 	eap->deinit = eap_pwd_deinit;
913 	eap->process = eap_pwd_process;
914 	eap->isKeyAvailable = eap_pwd_key_available;
915 	eap->getKey = eap_pwd_getkey;
916 	eap->get_emsk = eap_pwd_get_emsk;
917 
918 	ret = eap_peer_method_register(eap);
919 	if (ret)
920 		eap_peer_method_free(eap);
921 	return ret;
922 }
923