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[thirdparty/hostap.git] / src / eap_peer / eap_pwd.c
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 "eap_peer/eap_i.h"
13 #include "eap_common/eap_pwd_common.h"
14
15
16 struct eap_pwd_data {
17 enum {
18 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
19 } state;
20 u8 *id_peer;
21 size_t id_peer_len;
22 u8 *id_server;
23 size_t id_server_len;
24 u8 *password;
25 size_t password_len;
26 u16 group_num;
27 EAP_PWD_group *grp;
28
29 struct wpabuf *inbuf;
30 size_t in_frag_pos;
31 struct wpabuf *outbuf;
32 size_t out_frag_pos;
33 size_t mtu;
34
35 BIGNUM *k;
36 BIGNUM *private_value;
37 BIGNUM *server_scalar;
38 BIGNUM *my_scalar;
39 EC_POINT *my_element;
40 EC_POINT *server_element;
41
42 u8 msk[EAP_MSK_LEN];
43 u8 emsk[EAP_EMSK_LEN];
44
45 BN_CTX *bnctx;
46 };
47
48
49 #ifndef CONFIG_NO_STDOUT_DEBUG
50 static const char * eap_pwd_state_txt(int state)
51 {
52 switch (state) {
53 case PWD_ID_Req:
54 return "PWD-ID-Req";
55 case PWD_Commit_Req:
56 return "PWD-Commit-Req";
57 case PWD_Confirm_Req:
58 return "PWD-Confirm-Req";
59 case SUCCESS:
60 return "SUCCESS";
61 case FAILURE:
62 return "FAILURE";
63 default:
64 return "PWD-UNK";
65 }
66 }
67 #endif /* CONFIG_NO_STDOUT_DEBUG */
68
69
70 static void eap_pwd_state(struct eap_pwd_data *data, int state)
71 {
72 wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s",
73 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
74 data->state = state;
75 }
76
77
78 static void * eap_pwd_init(struct eap_sm *sm)
79 {
80 struct eap_pwd_data *data;
81 const u8 *identity, *password;
82 size_t identity_len, password_len;
83
84 password = eap_get_config_password(sm, &password_len);
85 if (password == NULL) {
86 wpa_printf(MSG_INFO, "EAP-PWD: No password configured!");
87 return NULL;
88 }
89
90 identity = eap_get_config_identity(sm, &identity_len);
91 if (identity == NULL) {
92 wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!");
93 return NULL;
94 }
95
96 if ((data = os_zalloc(sizeof(*data))) == NULL) {
97 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail");
98 return NULL;
99 }
100
101 if ((data->bnctx = BN_CTX_new()) == NULL) {
102 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
103 os_free(data);
104 return NULL;
105 }
106
107 if ((data->id_peer = os_malloc(identity_len)) == NULL) {
108 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
109 BN_CTX_free(data->bnctx);
110 os_free(data);
111 return NULL;
112 }
113
114 os_memcpy(data->id_peer, identity, identity_len);
115 data->id_peer_len = identity_len;
116
117 if ((data->password = os_malloc(password_len)) == NULL) {
118 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail");
119 BN_CTX_free(data->bnctx);
120 os_free(data->id_peer);
121 os_free(data);
122 return NULL;
123 }
124 os_memcpy(data->password, password, password_len);
125 data->password_len = password_len;
126
127 data->out_frag_pos = data->in_frag_pos = 0;
128 data->inbuf = data->outbuf = NULL;
129 data->mtu = 1020; /* default from RFC 5931, make it configurable! */
130
131 data->state = PWD_ID_Req;
132
133 return data;
134 }
135
136
137 static void eap_pwd_deinit(struct eap_sm *sm, void *priv)
138 {
139 struct eap_pwd_data *data = priv;
140
141 BN_free(data->private_value);
142 BN_free(data->server_scalar);
143 BN_free(data->my_scalar);
144 BN_free(data->k);
145 BN_CTX_free(data->bnctx);
146 EC_POINT_free(data->my_element);
147 EC_POINT_free(data->server_element);
148 os_free(data->id_peer);
149 os_free(data->id_server);
150 os_free(data->password);
151 if (data->grp) {
152 EC_GROUP_free(data->grp->group);
153 EC_POINT_free(data->grp->pwe);
154 BN_free(data->grp->order);
155 BN_free(data->grp->prime);
156 os_free(data->grp);
157 }
158 os_free(data);
159 }
160
161
162 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
163 {
164 struct eap_pwd_data *data = priv;
165 u8 *key;
166
167 if (data->state != SUCCESS)
168 return NULL;
169
170 key = os_malloc(EAP_MSK_LEN);
171 if (key == NULL)
172 return NULL;
173
174 os_memcpy(key, data->msk, EAP_MSK_LEN);
175 *len = EAP_MSK_LEN;
176
177 return key;
178 }
179
180
181 static void
182 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
183 struct eap_method_ret *ret,
184 const struct wpabuf *reqData,
185 const u8 *payload, size_t payload_len)
186 {
187 struct eap_pwd_id *id;
188
189 if (data->state != PWD_ID_Req) {
190 ret->ignore = TRUE;
191 eap_pwd_state(data, FAILURE);
192 return;
193 }
194
195 if (payload_len < sizeof(struct eap_pwd_id)) {
196 ret->ignore = TRUE;
197 eap_pwd_state(data, FAILURE);
198 return;
199 }
200
201 id = (struct eap_pwd_id *) payload;
202 data->group_num = be_to_host16(id->group_num);
203 if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
204 (id->prf != EAP_PWD_DEFAULT_PRF)) {
205 ret->ignore = TRUE;
206 eap_pwd_state(data, FAILURE);
207 return;
208 }
209
210 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
211 data->group_num);
212
213 data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
214 if (data->id_server == NULL) {
215 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
216 eap_pwd_state(data, FAILURE);
217 return;
218 }
219 data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
220 os_memcpy(data->id_server, id->identity, data->id_server_len);
221 wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of",
222 data->id_server, data->id_server_len);
223
224 if ((data->grp = (EAP_PWD_group *) os_malloc(sizeof(EAP_PWD_group))) ==
225 NULL) {
226 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
227 "group");
228 eap_pwd_state(data, FAILURE);
229 return;
230 }
231
232 /* compute PWE */
233 if (compute_password_element(data->grp, data->group_num,
234 data->password, data->password_len,
235 data->id_server, data->id_server_len,
236 data->id_peer, data->id_peer_len,
237 id->token)) {
238 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
239 eap_pwd_state(data, FAILURE);
240 return;
241 }
242
243 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
244 BN_num_bits(data->grp->prime));
245
246 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
247 data->id_peer_len);
248 if (data->outbuf == NULL) {
249 eap_pwd_state(data, FAILURE);
250 return;
251 }
252 wpabuf_put_be16(data->outbuf, data->group_num);
253 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
254 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
255 wpabuf_put_data(data->outbuf, id->token, sizeof(id->token));
256 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
257 wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
258
259 eap_pwd_state(data, PWD_Commit_Req);
260 }
261
262
263 static void
264 eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
265 struct eap_method_ret *ret,
266 const struct wpabuf *reqData,
267 const u8 *payload, size_t payload_len)
268 {
269 EC_POINT *K = NULL, *point = NULL;
270 BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
271 u16 offset;
272 u8 *ptr, *scalar = NULL, *element = NULL;
273
274 if (((data->private_value = BN_new()) == NULL) ||
275 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
276 ((cofactor = BN_new()) == NULL) ||
277 ((data->my_scalar = BN_new()) == NULL) ||
278 ((mask = BN_new()) == NULL)) {
279 wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail");
280 goto fin;
281 }
282
283 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
284 wpa_printf(MSG_INFO, "EAP-pwd (peer): unable to get cofactor "
285 "for curve");
286 goto fin;
287 }
288
289 BN_rand_range(data->private_value, data->grp->order);
290 BN_rand_range(mask, data->grp->order);
291 BN_add(data->my_scalar, data->private_value, mask);
292 BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
293 data->bnctx);
294
295 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
296 data->grp->pwe, mask, data->bnctx)) {
297 wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation "
298 "fail");
299 eap_pwd_state(data, FAILURE);
300 goto fin;
301 }
302
303 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
304 {
305 wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail");
306 goto fin;
307 }
308 BN_free(mask);
309
310 if (((x = BN_new()) == NULL) ||
311 ((y = BN_new()) == NULL)) {
312 wpa_printf(MSG_INFO, "EAP-PWD (peer): point allocation fail");
313 goto fin;
314 }
315
316 /* process the request */
317 if (((data->server_scalar = BN_new()) == NULL) ||
318 ((data->k = BN_new()) == NULL) ||
319 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
320 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
321 ((data->server_element = EC_POINT_new(data->grp->group)) == NULL))
322 {
323 wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation "
324 "fail");
325 goto fin;
326 }
327
328 /* element, x then y, followed by scalar */
329 ptr = (u8 *) payload;
330 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
331 ptr += BN_num_bytes(data->grp->prime);
332 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
333 ptr += BN_num_bytes(data->grp->prime);
334 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->server_scalar);
335 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
336 data->server_element, x, y,
337 data->bnctx)) {
338 wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element "
339 "fail");
340 goto fin;
341 }
342
343 /* check to ensure server's element is not in a small sub-group */
344 if (BN_cmp(cofactor, BN_value_one())) {
345 if (!EC_POINT_mul(data->grp->group, point, NULL,
346 data->server_element, cofactor, NULL)) {
347 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
348 "server element by order!\n");
349 goto fin;
350 }
351 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
352 wpa_printf(MSG_INFO, "EAP-PWD (peer): server element "
353 "is at infinity!\n");
354 goto fin;
355 }
356 }
357
358 /* compute the shared key, k */
359 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
360 data->server_scalar, data->bnctx)) ||
361 (!EC_POINT_add(data->grp->group, K, K, data->server_element,
362 data->bnctx)) ||
363 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
364 data->bnctx))) {
365 wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key "
366 "fail");
367 goto fin;
368 }
369
370 /* ensure that the shared key isn't in a small sub-group */
371 if (BN_cmp(cofactor, BN_value_one())) {
372 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
373 NULL)) {
374 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
375 "shared key point by order");
376 goto fin;
377 }
378 }
379
380 /*
381 * This check is strictly speaking just for the case above where
382 * co-factor > 1 but it was suggested that even though this is probably
383 * never going to happen it is a simple and safe check "just to be
384 * sure" so let's be safe.
385 */
386 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
387 wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at "
388 "infinity!\n");
389 goto fin;
390 }
391
392 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
393 NULL, data->bnctx)) {
394 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract "
395 "shared secret from point");
396 goto fin;
397 }
398
399 /* now do the response */
400 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
401 data->my_element, x, y,
402 data->bnctx)) {
403 wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail");
404 goto fin;
405 }
406
407 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
408 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
409 NULL)) {
410 wpa_printf(MSG_INFO, "EAP-PWD (peer): data allocation fail");
411 goto fin;
412 }
413
414 /*
415 * bignums occupy as little memory as possible so one that is
416 * sufficiently smaller than the prime or order might need pre-pending
417 * with zeros.
418 */
419 os_memset(scalar, 0, BN_num_bytes(data->grp->order));
420 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
421 offset = BN_num_bytes(data->grp->order) -
422 BN_num_bytes(data->my_scalar);
423 BN_bn2bin(data->my_scalar, scalar + offset);
424
425 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
426 BN_bn2bin(x, element + offset);
427 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
428 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
429
430 data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) +
431 2 * BN_num_bytes(data->grp->prime));
432 if (data->outbuf == NULL)
433 goto fin;
434
435 /* we send the element as (x,y) follwed by the scalar */
436 wpabuf_put_data(data->outbuf, element,
437 2 * BN_num_bytes(data->grp->prime));
438 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
439
440 fin:
441 os_free(scalar);
442 os_free(element);
443 BN_free(x);
444 BN_free(y);
445 BN_free(cofactor);
446 EC_POINT_free(K);
447 EC_POINT_free(point);
448 if (data->outbuf == NULL)
449 eap_pwd_state(data, FAILURE);
450 else
451 eap_pwd_state(data, PWD_Confirm_Req);
452 }
453
454
455 static void
456 eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
457 struct eap_method_ret *ret,
458 const struct wpabuf *reqData,
459 const u8 *payload, size_t payload_len)
460 {
461 BIGNUM *x = NULL, *y = NULL;
462 HMAC_CTX ctx;
463 u32 cs;
464 u16 grp;
465 u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;
466 int offset;
467
468 /*
469 * first build up the ciphersuite which is group | random_function |
470 * prf
471 */
472 grp = htons(data->group_num);
473 ptr = (u8 *) &cs;
474 os_memcpy(ptr, &grp, sizeof(u16));
475 ptr += sizeof(u16);
476 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
477 ptr += sizeof(u8);
478 *ptr = EAP_PWD_DEFAULT_PRF;
479
480 /* each component of the cruft will be at most as big as the prime */
481 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
482 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
483 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
484 "fail");
485 goto fin;
486 }
487
488 /*
489 * server's commit is H(k | server_element | server_scalar |
490 * peer_element | peer_scalar | ciphersuite)
491 */
492 H_Init(&ctx);
493
494 /*
495 * zero the memory each time because this is mod prime math and some
496 * value may start with a few zeros and the previous one did not.
497 */
498 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
499 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
500 BN_bn2bin(data->k, cruft + offset);
501 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
502
503 /* server element: x, y */
504 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
505 data->server_element, x, y,
506 data->bnctx)) {
507 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
508 "assignment fail");
509 goto fin;
510 }
511 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
512 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
513 BN_bn2bin(x, cruft + offset);
514 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
515 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
516 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
517 BN_bn2bin(y, cruft + offset);
518 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
519
520 /* server scalar */
521 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
522 offset = BN_num_bytes(data->grp->order) -
523 BN_num_bytes(data->server_scalar);
524 BN_bn2bin(data->server_scalar, cruft + offset);
525 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
526
527 /* my element: x, y */
528 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
529 data->my_element, x, y,
530 data->bnctx)) {
531 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
532 "assignment fail");
533 goto fin;
534 }
535
536 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
537 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
538 BN_bn2bin(x, cruft + offset);
539 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
540 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
541 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
542 BN_bn2bin(y, cruft + offset);
543 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
544
545 /* my scalar */
546 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
547 offset = BN_num_bytes(data->grp->order) -
548 BN_num_bytes(data->my_scalar);
549 BN_bn2bin(data->my_scalar, cruft + offset);
550 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
551
552 /* the ciphersuite */
553 H_Update(&ctx, (u8 *) &cs, sizeof(u32));
554
555 /* random function fin */
556 H_Final(&ctx, conf);
557
558 ptr = (u8 *) payload;
559 if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) {
560 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
561 goto fin;
562 }
563
564 wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified");
565
566 /*
567 * compute confirm:
568 * H(k | peer_element | peer_scalar | server_element | server_scalar |
569 * ciphersuite)
570 */
571 H_Init(&ctx);
572
573 /* k */
574 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
575 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
576 BN_bn2bin(data->k, cruft + offset);
577 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
578
579 /* my element */
580 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
581 data->my_element, x, y,
582 data->bnctx)) {
583 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
584 "assignment fail");
585 goto fin;
586 }
587 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
588 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
589 BN_bn2bin(x, cruft + offset);
590 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
591 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
592 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
593 BN_bn2bin(y, cruft + offset);
594 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
595
596 /* my scalar */
597 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
598 offset = BN_num_bytes(data->grp->order) -
599 BN_num_bytes(data->my_scalar);
600 BN_bn2bin(data->my_scalar, cruft + offset);
601 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
602
603 /* server element: x, y */
604 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
605 data->server_element, x, y,
606 data->bnctx)) {
607 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
608 "assignment fail");
609 goto fin;
610 }
611 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
612 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
613 BN_bn2bin(x, cruft + offset);
614 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
615 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
616 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
617 BN_bn2bin(y, cruft + offset);
618 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
619
620 /* server scalar */
621 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
622 offset = BN_num_bytes(data->grp->order) -
623 BN_num_bytes(data->server_scalar);
624 BN_bn2bin(data->server_scalar, cruft + offset);
625 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
626
627 /* the ciphersuite */
628 H_Update(&ctx, (u8 *) &cs, sizeof(u32));
629
630 /* all done */
631 H_Final(&ctx, conf);
632
633 if (compute_keys(data->grp, data->bnctx, data->k,
634 data->my_scalar, data->server_scalar, conf, ptr,
635 &cs, data->msk, data->emsk) < 0) {
636 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
637 "EMSK");
638 goto fin;
639 }
640
641 data->outbuf = wpabuf_alloc(SHA256_DIGEST_LENGTH);
642 if (data->outbuf == NULL)
643 goto fin;
644
645 wpabuf_put_data(data->outbuf, conf, SHA256_DIGEST_LENGTH);
646
647 fin:
648 os_free(cruft);
649 BN_free(x);
650 BN_free(y);
651 ret->methodState = METHOD_DONE;
652 if (data->outbuf == NULL) {
653 ret->decision = DECISION_FAIL;
654 eap_pwd_state(data, FAILURE);
655 } else {
656 ret->decision = DECISION_UNCOND_SUCC;
657 eap_pwd_state(data, SUCCESS);
658 }
659 }
660
661
662 static struct wpabuf *
663 eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
664 const struct wpabuf *reqData)
665 {
666 struct eap_pwd_data *data = priv;
667 struct wpabuf *resp = NULL;
668 const u8 *pos, *buf;
669 size_t len;
670 u16 tot_len = 0;
671 u8 lm_exch;
672
673 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
674 if ((pos == NULL) || (len < 1)) {
675 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
676 "len is %d",
677 pos == NULL ? "NULL" : "not NULL", (int) len);
678 ret->ignore = TRUE;
679 return NULL;
680 }
681
682 ret->ignore = FALSE;
683 ret->methodState = METHOD_MAY_CONT;
684 ret->decision = DECISION_FAIL;
685 ret->allowNotifications = FALSE;
686
687 lm_exch = *pos;
688 pos++; /* skip over the bits and the exch */
689 len--;
690
691 /*
692 * we're fragmenting so send out the next fragment
693 */
694 if (data->out_frag_pos) {
695 /*
696 * this should be an ACK
697 */
698 if (len)
699 wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
700 "not an ACK");
701
702 wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
703 /*
704 * check if there are going to be more fragments
705 */
706 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
707 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
708 len = data->mtu - EAP_PWD_HDR_SIZE;
709 EAP_PWD_SET_MORE_BIT(lm_exch);
710 }
711 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
712 EAP_PWD_HDR_SIZE + len,
713 EAP_CODE_RESPONSE, eap_get_id(reqData));
714 if (resp == NULL) {
715 wpa_printf(MSG_INFO, "Unable to allocate memory for "
716 "next fragment!");
717 return NULL;
718 }
719 wpabuf_put_u8(resp, lm_exch);
720 buf = wpabuf_head_u8(data->outbuf);
721 wpabuf_put_data(resp, buf + data->out_frag_pos, len);
722 data->out_frag_pos += len;
723 /*
724 * this is the last fragment so get rid of the out buffer
725 */
726 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
727 wpabuf_free(data->outbuf);
728 data->outbuf = NULL;
729 data->out_frag_pos = 0;
730 }
731 wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
732 data->out_frag_pos == 0 ? "last" : "next",
733 (int) len);
734 return resp;
735 }
736
737 /*
738 * see if this is a fragment that needs buffering
739 *
740 * if it's the first fragment there'll be a length field
741 */
742 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
743 tot_len = WPA_GET_BE16(pos);
744 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
745 "total length = %d", tot_len);
746 data->inbuf = wpabuf_alloc(tot_len);
747 if (data->inbuf == NULL) {
748 wpa_printf(MSG_INFO, "Out of memory to buffer "
749 "fragments!");
750 return NULL;
751 }
752 pos += sizeof(u16);
753 len -= sizeof(u16);
754 }
755 /*
756 * buffer and ACK the fragment
757 */
758 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
759 data->in_frag_pos += len;
760 if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
761 wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
762 "detected (%d vs. %d)!",
763 (int) data->in_frag_pos,
764 (int) wpabuf_len(data->inbuf));
765 wpabuf_free(data->inbuf);
766 data->in_frag_pos = 0;
767 return NULL;
768 }
769 wpabuf_put_data(data->inbuf, pos, len);
770
771 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
772 EAP_PWD_HDR_SIZE,
773 EAP_CODE_RESPONSE, eap_get_id(reqData));
774 if (resp != NULL)
775 wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
776 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
777 (int) len);
778 return resp;
779 }
780 /*
781 * we're buffering and this is the last fragment
782 */
783 if (data->in_frag_pos) {
784 wpabuf_put_data(data->inbuf, pos, len);
785 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
786 (int) len);
787 data->in_frag_pos += len;
788 pos = wpabuf_head_u8(data->inbuf);
789 len = data->in_frag_pos;
790 }
791 wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
792 EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
793
794 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
795 case EAP_PWD_OPCODE_ID_EXCH:
796 eap_pwd_perform_id_exchange(sm, data, ret, reqData,
797 pos, len);
798 break;
799 case EAP_PWD_OPCODE_COMMIT_EXCH:
800 eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
801 pos, len);
802 break;
803 case EAP_PWD_OPCODE_CONFIRM_EXCH:
804 eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
805 pos, len);
806 break;
807 default:
808 wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
809 "opcode %d", lm_exch);
810 break;
811 }
812 /*
813 * if we buffered the just processed input now's the time to free it
814 */
815 if (data->in_frag_pos) {
816 wpabuf_free(data->inbuf);
817 data->in_frag_pos = 0;
818 }
819
820 if (data->outbuf == NULL)
821 return NULL; /* generic failure */
822
823 /*
824 * we have output! Do we need to fragment it?
825 */
826 len = wpabuf_len(data->outbuf);
827 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
828 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
829 EAP_CODE_RESPONSE, eap_get_id(reqData));
830 /*
831 * if so it's the first so include a length field
832 */
833 EAP_PWD_SET_LENGTH_BIT(lm_exch);
834 EAP_PWD_SET_MORE_BIT(lm_exch);
835 tot_len = len;
836 /*
837 * keep the packet at the MTU
838 */
839 len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
840 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
841 "length = %d", tot_len);
842 } else {
843 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
844 EAP_PWD_HDR_SIZE + len,
845 EAP_CODE_RESPONSE, eap_get_id(reqData));
846 }
847 if (resp == NULL)
848 return NULL;
849
850 wpabuf_put_u8(resp, lm_exch);
851 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
852 wpabuf_put_be16(resp, tot_len);
853 data->out_frag_pos += len;
854 }
855 buf = wpabuf_head_u8(data->outbuf);
856 wpabuf_put_data(resp, buf, len);
857 /*
858 * if we're not fragmenting then there's no need to carry this around
859 */
860 if (data->out_frag_pos == 0) {
861 wpabuf_free(data->outbuf);
862 data->outbuf = NULL;
863 data->out_frag_pos = 0;
864 }
865
866 return resp;
867 }
868
869
870 static Boolean eap_pwd_key_available(struct eap_sm *sm, void *priv)
871 {
872 struct eap_pwd_data *data = priv;
873 return data->state == SUCCESS;
874 }
875
876
877 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
878 {
879 struct eap_pwd_data *data = priv;
880 u8 *key;
881
882 if (data->state != SUCCESS)
883 return NULL;
884
885 if ((key = os_malloc(EAP_EMSK_LEN)) == NULL)
886 return NULL;
887
888 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
889 *len = EAP_EMSK_LEN;
890
891 return key;
892 }
893
894
895 int eap_peer_pwd_register(void)
896 {
897 struct eap_method *eap;
898 int ret;
899
900 EVP_add_digest(EVP_sha256());
901 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
902 EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD");
903 if (eap == NULL)
904 return -1;
905
906 eap->init = eap_pwd_init;
907 eap->deinit = eap_pwd_deinit;
908 eap->process = eap_pwd_process;
909 eap->isKeyAvailable = eap_pwd_key_available;
910 eap->getKey = eap_pwd_getkey;
911 eap->get_emsk = eap_pwd_get_emsk;
912
913 ret = eap_peer_method_register(eap);
914 if (ret)
915 eap_peer_method_free(eap);
916 return ret;
917 }
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