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
eap_pwd_state_txt(int state)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
eap_pwd_state(struct eap_pwd_data * data,int state)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
eap_pwd_init(struct eap_sm * sm)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
eap_pwd_deinit(struct eap_sm * sm,void * priv)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
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)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
eap_pwd_perform_id_exchange(struct eap_sm * sm,struct eap_pwd_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData,const u8 * payload,size_t payload_len)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
eap_pwd_perform_commit_exchange(struct eap_sm * sm,struct eap_pwd_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData,const u8 * payload,size_t payload_len)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
eap_pwd_perform_confirm_exchange(struct eap_sm * sm,struct eap_pwd_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData,const u8 * payload,size_t payload_len)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 *
eap_pwd_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)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
eap_pwd_key_available(struct eap_sm * sm,void * priv)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
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)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
eap_peer_pwd_register(void)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