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 "crypto/ms_funcs.h"
14 #include "eap_peer/eap_i.h"
15 #include "eap_common/eap_pwd_common.h"
16
17
18 struct eap_pwd_data {
19 enum {
20 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req,
21 SUCCESS_ON_FRAG_COMPLETION, 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 u16 group_num;
31 EAP_PWD_group *grp;
32
33 struct wpabuf *inbuf;
34 size_t in_frag_pos;
35 struct wpabuf *outbuf;
36 size_t out_frag_pos;
37 size_t mtu;
38
39 BIGNUM *k;
40 BIGNUM *private_value;
41 BIGNUM *server_scalar;
42 BIGNUM *my_scalar;
43 EC_POINT *my_element;
44 EC_POINT *server_element;
45
46 u8 msk[EAP_MSK_LEN];
47 u8 emsk[EAP_EMSK_LEN];
48 u8 session_id[1 + SHA256_MAC_LEN];
49
50 BN_CTX *bnctx;
51 };
52
53
54 #ifndef CONFIG_NO_STDOUT_DEBUG
eap_pwd_state_txt(int state)55 static const char * eap_pwd_state_txt(int state)
56 {
57 switch (state) {
58 case PWD_ID_Req:
59 return "PWD-ID-Req";
60 case PWD_Commit_Req:
61 return "PWD-Commit-Req";
62 case PWD_Confirm_Req:
63 return "PWD-Confirm-Req";
64 case SUCCESS_ON_FRAG_COMPLETION:
65 return "SUCCESS_ON_FRAG_COMPLETION";
66 case SUCCESS:
67 return "SUCCESS";
68 case FAILURE:
69 return "FAILURE";
70 default:
71 return "PWD-UNK";
72 }
73 }
74 #endif /* CONFIG_NO_STDOUT_DEBUG */
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 const u8 *identity, *password;
89 size_t identity_len, password_len;
90 int fragment_size;
91 int pwhash;
92
93 password = eap_get_config_password2(sm, &password_len, &pwhash);
94 if (password == NULL) {
95 wpa_printf(MSG_INFO, "EAP-PWD: No password configured!");
96 return NULL;
97 }
98
99 identity = eap_get_config_identity(sm, &identity_len);
100 if (identity == NULL) {
101 wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!");
102 return NULL;
103 }
104
105 if ((data = os_zalloc(sizeof(*data))) == NULL) {
106 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail");
107 return NULL;
108 }
109
110 if ((data->bnctx = BN_CTX_new()) == NULL) {
111 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
112 os_free(data);
113 return NULL;
114 }
115
116 if ((data->id_peer = os_malloc(identity_len)) == NULL) {
117 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
118 BN_CTX_free(data->bnctx);
119 os_free(data);
120 return NULL;
121 }
122
123 os_memcpy(data->id_peer, identity, identity_len);
124 data->id_peer_len = identity_len;
125
126 if ((data->password = os_malloc(password_len)) == NULL) {
127 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail");
128 BN_CTX_free(data->bnctx);
129 bin_clear_free(data->id_peer, data->id_peer_len);
130 os_free(data);
131 return NULL;
132 }
133 os_memcpy(data->password, password, password_len);
134 data->password_len = password_len;
135 data->password_hash = pwhash;
136
137 data->out_frag_pos = data->in_frag_pos = 0;
138 data->inbuf = data->outbuf = NULL;
139 fragment_size = eap_get_config_fragment_size(sm);
140 if (fragment_size <= 0)
141 data->mtu = 1020; /* default from RFC 5931 */
142 else
143 data->mtu = fragment_size;
144
145 data->state = PWD_ID_Req;
146
147 return data;
148 }
149
150
eap_pwd_deinit(struct eap_sm * sm,void * priv)151 static void eap_pwd_deinit(struct eap_sm *sm, void *priv)
152 {
153 struct eap_pwd_data *data = priv;
154
155 BN_clear_free(data->private_value);
156 BN_clear_free(data->server_scalar);
157 BN_clear_free(data->my_scalar);
158 BN_clear_free(data->k);
159 BN_CTX_free(data->bnctx);
160 EC_POINT_clear_free(data->my_element);
161 EC_POINT_clear_free(data->server_element);
162 bin_clear_free(data->id_peer, data->id_peer_len);
163 bin_clear_free(data->id_server, data->id_server_len);
164 bin_clear_free(data->password, data->password_len);
165 if (data->grp) {
166 EC_GROUP_free(data->grp->group);
167 EC_POINT_clear_free(data->grp->pwe);
168 BN_clear_free(data->grp->order);
169 BN_clear_free(data->grp->prime);
170 os_free(data->grp);
171 }
172 wpabuf_free(data->inbuf);
173 wpabuf_free(data->outbuf);
174 bin_clear_free(data, sizeof(*data));
175 }
176
177
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)178 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
179 {
180 struct eap_pwd_data *data = priv;
181 u8 *key;
182
183 if (data->state != SUCCESS)
184 return NULL;
185
186 key = os_malloc(EAP_MSK_LEN);
187 if (key == NULL)
188 return NULL;
189
190 os_memcpy(key, data->msk, EAP_MSK_LEN);
191 *len = EAP_MSK_LEN;
192
193 return key;
194 }
195
196
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)197 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
198 {
199 struct eap_pwd_data *data = priv;
200 u8 *id;
201
202 if (data->state != SUCCESS)
203 return NULL;
204
205 id = os_malloc(1 + SHA256_MAC_LEN);
206 if (id == NULL)
207 return NULL;
208
209 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
210 *len = 1 + SHA256_MAC_LEN;
211
212 return id;
213 }
214
215
216 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)217 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
218 struct eap_method_ret *ret,
219 const struct wpabuf *reqData,
220 const u8 *payload, size_t payload_len)
221 {
222 struct eap_pwd_id *id;
223 const u8 *password;
224 size_t password_len;
225 u8 pwhashhash[16];
226 int res;
227
228 if (data->state != PWD_ID_Req) {
229 ret->ignore = TRUE;
230 eap_pwd_state(data, FAILURE);
231 return;
232 }
233
234 if (payload_len < sizeof(struct eap_pwd_id)) {
235 ret->ignore = TRUE;
236 eap_pwd_state(data, FAILURE);
237 return;
238 }
239
240 id = (struct eap_pwd_id *) payload;
241 data->group_num = be_to_host16(id->group_num);
242 wpa_printf(MSG_DEBUG,
243 "EAP-PWD: Server EAP-pwd-ID proposal: group=%u random=%u prf=%u prep=%u",
244 data->group_num, id->random_function, id->prf, id->prep);
245 if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
246 (id->prf != EAP_PWD_DEFAULT_PRF)) {
247 ret->ignore = TRUE;
248 eap_pwd_state(data, FAILURE);
249 return;
250 }
251
252 if (id->prep != EAP_PWD_PREP_NONE &&
253 id->prep != EAP_PWD_PREP_MS) {
254 wpa_printf(MSG_DEBUG,
255 "EAP-PWD: Unsupported password pre-processing technique (Prep=%u)",
256 id->prep);
257 eap_pwd_state(data, FAILURE);
258 return;
259 }
260
261 if (id->prep == EAP_PWD_PREP_NONE && data->password_hash) {
262 wpa_printf(MSG_DEBUG,
263 "EAP-PWD: Unhashed password not available");
264 eap_pwd_state(data, FAILURE);
265 return;
266 }
267
268 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
269 data->group_num);
270
271 data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
272 if (data->id_server == NULL) {
273 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
274 eap_pwd_state(data, FAILURE);
275 return;
276 }
277 data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
278 os_memcpy(data->id_server, id->identity, data->id_server_len);
279 wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of",
280 data->id_server, data->id_server_len);
281
282 data->grp = os_zalloc(sizeof(EAP_PWD_group));
283 if (data->grp == NULL) {
284 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
285 "group");
286 eap_pwd_state(data, FAILURE);
287 return;
288 }
289
290 if (id->prep == EAP_PWD_PREP_MS) {
291 #ifdef CONFIG_FIPS
292 wpa_printf(MSG_ERROR,
293 "EAP-PWD (peer): MS password hash not supported in FIPS mode");
294 eap_pwd_state(data, FAILURE);
295 return;
296 #else /* CONFIG_FIPS */
297 if (data->password_hash) {
298 res = hash_nt_password_hash(data->password, pwhashhash);
299 } else {
300 u8 pwhash[16];
301
302 res = nt_password_hash(data->password,
303 data->password_len, pwhash);
304 if (res == 0)
305 res = hash_nt_password_hash(pwhash, pwhashhash);
306 os_memset(pwhash, 0, sizeof(pwhash));
307 }
308
309 if (res) {
310 eap_pwd_state(data, FAILURE);
311 return;
312 }
313
314 password = pwhashhash;
315 password_len = sizeof(pwhashhash);
316 #endif /* CONFIG_FIPS */
317 } else {
318 password = data->password;
319 password_len = data->password_len;
320 }
321
322 /* compute PWE */
323 res = compute_password_element(data->grp, data->group_num,
324 password, password_len,
325 data->id_server, data->id_server_len,
326 data->id_peer, data->id_peer_len,
327 id->token);
328 os_memset(pwhashhash, 0, sizeof(pwhashhash));
329 if (res) {
330 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
331 eap_pwd_state(data, FAILURE);
332 return;
333 }
334
335 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
336 BN_num_bits(data->grp->prime));
337
338 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
339 data->id_peer_len);
340 if (data->outbuf == NULL) {
341 eap_pwd_state(data, FAILURE);
342 return;
343 }
344 wpabuf_put_be16(data->outbuf, data->group_num);
345 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
346 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
347 wpabuf_put_data(data->outbuf, id->token, sizeof(id->token));
348 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
349 wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
350
351 eap_pwd_state(data, PWD_Commit_Req);
352 }
353
354
355 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)356 eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
357 struct eap_method_ret *ret,
358 const struct wpabuf *reqData,
359 const u8 *payload, size_t payload_len)
360 {
361 EC_POINT *K = NULL, *point = NULL;
362 BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
363 u16 offset;
364 u8 *ptr, *scalar = NULL, *element = NULL;
365 size_t prime_len, order_len;
366
367 if (data->state != PWD_Commit_Req) {
368 ret->ignore = TRUE;
369 goto fin;
370 }
371
372 prime_len = BN_num_bytes(data->grp->prime);
373 order_len = BN_num_bytes(data->grp->order);
374
375 if (payload_len != 2 * prime_len + order_len) {
376 wpa_printf(MSG_INFO,
377 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
378 (unsigned int) payload_len,
379 (unsigned int) (2 * prime_len + order_len));
380 goto fin;
381 }
382
383 if (((data->private_value = BN_new()) == NULL) ||
384 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
385 ((cofactor = BN_new()) == NULL) ||
386 ((data->my_scalar = BN_new()) == NULL) ||
387 ((mask = BN_new()) == NULL)) {
388 wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail");
389 goto fin;
390 }
391
392 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
393 wpa_printf(MSG_INFO, "EAP-pwd (peer): unable to get cofactor "
394 "for curve");
395 goto fin;
396 }
397
398 if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
399 BN_rand_range(mask, data->grp->order) != 1 ||
400 BN_add(data->my_scalar, data->private_value, mask) != 1 ||
401 BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
402 data->bnctx) != 1) {
403 wpa_printf(MSG_INFO,
404 "EAP-pwd (peer): unable to get randomness");
405 goto fin;
406 }
407
408 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
409 data->grp->pwe, mask, data->bnctx)) {
410 wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation "
411 "fail");
412 eap_pwd_state(data, FAILURE);
413 goto fin;
414 }
415
416 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
417 {
418 wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail");
419 goto fin;
420 }
421
422 if (((x = BN_new()) == NULL) ||
423 ((y = BN_new()) == NULL)) {
424 wpa_printf(MSG_INFO, "EAP-PWD (peer): point allocation fail");
425 goto fin;
426 }
427
428 /* process the request */
429 if (((data->server_scalar = BN_new()) == NULL) ||
430 ((data->k = BN_new()) == NULL) ||
431 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
432 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
433 ((data->server_element = EC_POINT_new(data->grp->group)) == NULL))
434 {
435 wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation "
436 "fail");
437 goto fin;
438 }
439
440 /* element, x then y, followed by scalar */
441 ptr = (u8 *) payload;
442 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
443 ptr += BN_num_bytes(data->grp->prime);
444 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
445 ptr += BN_num_bytes(data->grp->prime);
446 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->server_scalar);
447 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
448 data->server_element, x, y,
449 data->bnctx)) {
450 wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element "
451 "fail");
452 goto fin;
453 }
454
455 /* check to ensure server's element is not in a small sub-group */
456 if (BN_cmp(cofactor, BN_value_one())) {
457 if (!EC_POINT_mul(data->grp->group, point, NULL,
458 data->server_element, cofactor, NULL)) {
459 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
460 "server element by order!\n");
461 goto fin;
462 }
463 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
464 wpa_printf(MSG_INFO, "EAP-PWD (peer): server element "
465 "is at infinity!\n");
466 goto fin;
467 }
468 }
469
470 /* compute the shared key, k */
471 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
472 data->server_scalar, data->bnctx)) ||
473 (!EC_POINT_add(data->grp->group, K, K, data->server_element,
474 data->bnctx)) ||
475 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
476 data->bnctx))) {
477 wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key "
478 "fail");
479 goto fin;
480 }
481
482 /* ensure that the shared key isn't in a small sub-group */
483 if (BN_cmp(cofactor, BN_value_one())) {
484 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
485 NULL)) {
486 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
487 "shared key point by order");
488 goto fin;
489 }
490 }
491
492 /*
493 * This check is strictly speaking just for the case above where
494 * co-factor > 1 but it was suggested that even though this is probably
495 * never going to happen it is a simple and safe check "just to be
496 * sure" so let's be safe.
497 */
498 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
499 wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at "
500 "infinity!\n");
501 goto fin;
502 }
503
504 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
505 NULL, data->bnctx)) {
506 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract "
507 "shared secret from point");
508 goto fin;
509 }
510
511 /* now do the response */
512 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
513 data->my_element, x, y,
514 data->bnctx)) {
515 wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail");
516 goto fin;
517 }
518
519 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
520 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
521 NULL)) {
522 wpa_printf(MSG_INFO, "EAP-PWD (peer): data allocation fail");
523 goto fin;
524 }
525
526 /*
527 * bignums occupy as little memory as possible so one that is
528 * sufficiently smaller than the prime or order might need pre-pending
529 * with zeros.
530 */
531 os_memset(scalar, 0, BN_num_bytes(data->grp->order));
532 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
533 offset = BN_num_bytes(data->grp->order) -
534 BN_num_bytes(data->my_scalar);
535 BN_bn2bin(data->my_scalar, scalar + offset);
536
537 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
538 BN_bn2bin(x, element + offset);
539 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
540 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
541
542 data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) +
543 2 * BN_num_bytes(data->grp->prime));
544 if (data->outbuf == NULL)
545 goto fin;
546
547 /* we send the element as (x,y) follwed by the scalar */
548 wpabuf_put_data(data->outbuf, element,
549 2 * BN_num_bytes(data->grp->prime));
550 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
551
552 fin:
553 os_free(scalar);
554 os_free(element);
555 BN_clear_free(x);
556 BN_clear_free(y);
557 BN_clear_free(mask);
558 BN_clear_free(cofactor);
559 EC_POINT_clear_free(K);
560 EC_POINT_clear_free(point);
561 if (data->outbuf == NULL)
562 eap_pwd_state(data, FAILURE);
563 else
564 eap_pwd_state(data, PWD_Confirm_Req);
565 }
566
567
568 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)569 eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
570 struct eap_method_ret *ret,
571 const struct wpabuf *reqData,
572 const u8 *payload, size_t payload_len)
573 {
574 BIGNUM *x = NULL, *y = NULL;
575 struct crypto_hash *hash;
576 u32 cs;
577 u16 grp;
578 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
579 int offset;
580
581 if (data->state != PWD_Confirm_Req) {
582 ret->ignore = TRUE;
583 goto fin;
584 }
585
586 if (payload_len != SHA256_MAC_LEN) {
587 wpa_printf(MSG_INFO,
588 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
589 (unsigned int) payload_len, SHA256_MAC_LEN);
590 goto fin;
591 }
592
593 /*
594 * first build up the ciphersuite which is group | random_function |
595 * prf
596 */
597 grp = htons(data->group_num);
598 ptr = (u8 *) &cs;
599 os_memcpy(ptr, &grp, sizeof(u16));
600 ptr += sizeof(u16);
601 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
602 ptr += sizeof(u8);
603 *ptr = EAP_PWD_DEFAULT_PRF;
604
605 /* each component of the cruft will be at most as big as the prime */
606 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
607 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
608 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
609 "fail");
610 goto fin;
611 }
612
613 /*
614 * server's commit is H(k | server_element | server_scalar |
615 * peer_element | peer_scalar | ciphersuite)
616 */
617 hash = eap_pwd_h_init();
618 if (hash == NULL)
619 goto fin;
620
621 /*
622 * zero the memory each time because this is mod prime math and some
623 * value may start with a few zeros and the previous one did not.
624 */
625 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
626 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
627 BN_bn2bin(data->k, cruft + offset);
628 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
629
630 /* server element: x, y */
631 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
632 data->server_element, x, y,
633 data->bnctx)) {
634 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
635 "assignment fail");
636 goto fin;
637 }
638 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
639 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
640 BN_bn2bin(x, cruft + offset);
641 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
642 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
643 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
644 BN_bn2bin(y, cruft + offset);
645 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
646
647 /* server scalar */
648 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
649 offset = BN_num_bytes(data->grp->order) -
650 BN_num_bytes(data->server_scalar);
651 BN_bn2bin(data->server_scalar, cruft + offset);
652 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
653
654 /* my element: x, y */
655 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
656 data->my_element, x, y,
657 data->bnctx)) {
658 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
659 "assignment fail");
660 goto fin;
661 }
662
663 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
664 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
665 BN_bn2bin(x, cruft + offset);
666 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
667 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
668 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
669 BN_bn2bin(y, cruft + offset);
670 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
671
672 /* my scalar */
673 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
674 offset = BN_num_bytes(data->grp->order) -
675 BN_num_bytes(data->my_scalar);
676 BN_bn2bin(data->my_scalar, cruft + offset);
677 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
678
679 /* the ciphersuite */
680 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
681
682 /* random function fin */
683 eap_pwd_h_final(hash, conf);
684
685 ptr = (u8 *) payload;
686 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
687 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
688 goto fin;
689 }
690
691 wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified");
692
693 /*
694 * compute confirm:
695 * H(k | peer_element | peer_scalar | server_element | server_scalar |
696 * ciphersuite)
697 */
698 hash = eap_pwd_h_init();
699 if (hash == NULL)
700 goto fin;
701
702 /* k */
703 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
704 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
705 BN_bn2bin(data->k, cruft + offset);
706 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
707
708 /* my element */
709 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
710 data->my_element, x, y,
711 data->bnctx)) {
712 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
713 "assignment fail");
714 goto fin;
715 }
716 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
717 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
718 BN_bn2bin(x, cruft + offset);
719 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
720 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
721 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
722 BN_bn2bin(y, cruft + offset);
723 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
724
725 /* my scalar */
726 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
727 offset = BN_num_bytes(data->grp->order) -
728 BN_num_bytes(data->my_scalar);
729 BN_bn2bin(data->my_scalar, cruft + offset);
730 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
731
732 /* server element: x, y */
733 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
734 data->server_element, x, y,
735 data->bnctx)) {
736 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
737 "assignment fail");
738 goto fin;
739 }
740 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
741 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
742 BN_bn2bin(x, cruft + offset);
743 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
744 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
745 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
746 BN_bn2bin(y, cruft + offset);
747 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
748
749 /* server scalar */
750 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
751 offset = BN_num_bytes(data->grp->order) -
752 BN_num_bytes(data->server_scalar);
753 BN_bn2bin(data->server_scalar, cruft + offset);
754 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
755
756 /* the ciphersuite */
757 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
758
759 /* all done */
760 eap_pwd_h_final(hash, conf);
761
762 if (compute_keys(data->grp, data->bnctx, data->k,
763 data->my_scalar, data->server_scalar, conf, ptr,
764 &cs, data->msk, data->emsk, data->session_id) < 0) {
765 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
766 "EMSK");
767 goto fin;
768 }
769
770 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
771 if (data->outbuf == NULL)
772 goto fin;
773
774 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
775
776 fin:
777 if (data->grp)
778 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
779 BN_clear_free(x);
780 BN_clear_free(y);
781 if (data->outbuf == NULL) {
782 ret->methodState = METHOD_DONE;
783 ret->decision = DECISION_FAIL;
784 eap_pwd_state(data, FAILURE);
785 } else {
786 eap_pwd_state(data, SUCCESS_ON_FRAG_COMPLETION);
787 }
788 }
789
790
791 static struct wpabuf *
eap_pwd_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)792 eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
793 const struct wpabuf *reqData)
794 {
795 struct eap_pwd_data *data = priv;
796 struct wpabuf *resp = NULL;
797 const u8 *pos, *buf;
798 size_t len;
799 u16 tot_len = 0;
800 u8 lm_exch;
801
802 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
803 if ((pos == NULL) || (len < 1)) {
804 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
805 "len is %d",
806 pos == NULL ? "NULL" : "not NULL", (int) len);
807 ret->ignore = TRUE;
808 return NULL;
809 }
810
811 ret->ignore = FALSE;
812 ret->methodState = METHOD_MAY_CONT;
813 ret->decision = DECISION_FAIL;
814 ret->allowNotifications = FALSE;
815
816 lm_exch = *pos;
817 pos++; /* skip over the bits and the exch */
818 len--;
819
820 /*
821 * we're fragmenting so send out the next fragment
822 */
823 if (data->out_frag_pos) {
824 /*
825 * this should be an ACK
826 */
827 if (len)
828 wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
829 "not an ACK");
830
831 wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
832 /*
833 * check if there are going to be more fragments
834 */
835 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
836 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
837 len = data->mtu - EAP_PWD_HDR_SIZE;
838 EAP_PWD_SET_MORE_BIT(lm_exch);
839 }
840 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
841 EAP_PWD_HDR_SIZE + len,
842 EAP_CODE_RESPONSE, eap_get_id(reqData));
843 if (resp == NULL) {
844 wpa_printf(MSG_INFO, "Unable to allocate memory for "
845 "next fragment!");
846 return NULL;
847 }
848 wpabuf_put_u8(resp, lm_exch);
849 buf = wpabuf_head_u8(data->outbuf);
850 wpabuf_put_data(resp, buf + data->out_frag_pos, len);
851 data->out_frag_pos += len;
852 /*
853 * this is the last fragment so get rid of the out buffer
854 */
855 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
856 wpabuf_free(data->outbuf);
857 data->outbuf = NULL;
858 data->out_frag_pos = 0;
859 }
860 wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
861 data->out_frag_pos == 0 ? "last" : "next",
862 (int) len);
863 if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
864 ret->methodState = METHOD_DONE;
865 ret->decision = DECISION_UNCOND_SUCC;
866 eap_pwd_state(data, SUCCESS);
867 }
868 return resp;
869 }
870
871 /*
872 * see if this is a fragment that needs buffering
873 *
874 * if it's the first fragment there'll be a length field
875 */
876 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
877 if (len < 2) {
878 wpa_printf(MSG_DEBUG,
879 "EAP-pwd: Frame too short to contain Total-Length field");
880 ret->ignore = TRUE;
881 return NULL;
882 }
883 tot_len = WPA_GET_BE16(pos);
884 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
885 "total length = %d", tot_len);
886 if (tot_len > 15000)
887 return NULL;
888 if (data->inbuf) {
889 wpa_printf(MSG_DEBUG,
890 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
891 ret->ignore = TRUE;
892 return NULL;
893 }
894 data->inbuf = wpabuf_alloc(tot_len);
895 if (data->inbuf == NULL) {
896 wpa_printf(MSG_INFO, "Out of memory to buffer "
897 "fragments!");
898 return NULL;
899 }
900 data->in_frag_pos = 0;
901 pos += sizeof(u16);
902 len -= sizeof(u16);
903 }
904 /*
905 * buffer and ACK the fragment
906 */
907 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
908 data->in_frag_pos += len;
909 if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
910 wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
911 "detected (%d vs. %d)!",
912 (int) data->in_frag_pos,
913 (int) wpabuf_len(data->inbuf));
914 wpabuf_free(data->inbuf);
915 data->inbuf = NULL;
916 data->in_frag_pos = 0;
917 return NULL;
918 }
919 wpabuf_put_data(data->inbuf, pos, len);
920 }
921 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
922 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
923 EAP_PWD_HDR_SIZE,
924 EAP_CODE_RESPONSE, eap_get_id(reqData));
925 if (resp != NULL)
926 wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
927 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
928 (int) len);
929 return resp;
930 }
931 /*
932 * we're buffering and this is the last fragment
933 */
934 if (data->in_frag_pos) {
935 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
936 (int) len);
937 pos = wpabuf_head_u8(data->inbuf);
938 len = data->in_frag_pos;
939 }
940 wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
941 EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
942
943 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
944 case EAP_PWD_OPCODE_ID_EXCH:
945 eap_pwd_perform_id_exchange(sm, data, ret, reqData,
946 pos, len);
947 break;
948 case EAP_PWD_OPCODE_COMMIT_EXCH:
949 eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
950 pos, len);
951 break;
952 case EAP_PWD_OPCODE_CONFIRM_EXCH:
953 eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
954 pos, len);
955 break;
956 default:
957 wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
958 "opcode %d", lm_exch);
959 break;
960 }
961 /*
962 * if we buffered the just processed input now's the time to free it
963 */
964 if (data->in_frag_pos) {
965 wpabuf_free(data->inbuf);
966 data->inbuf = NULL;
967 data->in_frag_pos = 0;
968 }
969
970 if (data->outbuf == NULL) {
971 ret->methodState = METHOD_DONE;
972 ret->decision = DECISION_FAIL;
973 return NULL; /* generic failure */
974 }
975
976 /*
977 * we have output! Do we need to fragment it?
978 */
979 lm_exch = EAP_PWD_GET_EXCHANGE(lm_exch);
980 len = wpabuf_len(data->outbuf);
981 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
982 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
983 EAP_CODE_RESPONSE, eap_get_id(reqData));
984 /*
985 * if so it's the first so include a length field
986 */
987 EAP_PWD_SET_LENGTH_BIT(lm_exch);
988 EAP_PWD_SET_MORE_BIT(lm_exch);
989 tot_len = len;
990 /*
991 * keep the packet at the MTU
992 */
993 len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
994 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
995 "length = %d", tot_len);
996 } else {
997 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
998 EAP_PWD_HDR_SIZE + len,
999 EAP_CODE_RESPONSE, eap_get_id(reqData));
1000 }
1001 if (resp == NULL)
1002 return NULL;
1003
1004 wpabuf_put_u8(resp, lm_exch);
1005 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
1006 wpabuf_put_be16(resp, tot_len);
1007 data->out_frag_pos += len;
1008 }
1009 buf = wpabuf_head_u8(data->outbuf);
1010 wpabuf_put_data(resp, buf, len);
1011 /*
1012 * if we're not fragmenting then there's no need to carry this around
1013 */
1014 if (data->out_frag_pos == 0) {
1015 wpabuf_free(data->outbuf);
1016 data->outbuf = NULL;
1017 data->out_frag_pos = 0;
1018 if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
1019 ret->methodState = METHOD_DONE;
1020 ret->decision = DECISION_UNCOND_SUCC;
1021 eap_pwd_state(data, SUCCESS);
1022 }
1023 }
1024
1025 return resp;
1026 }
1027
1028
eap_pwd_key_available(struct eap_sm * sm,void * priv)1029 static Boolean eap_pwd_key_available(struct eap_sm *sm, void *priv)
1030 {
1031 struct eap_pwd_data *data = priv;
1032 return data->state == SUCCESS;
1033 }
1034
1035
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)1036 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1037 {
1038 struct eap_pwd_data *data = priv;
1039 u8 *key;
1040
1041 if (data->state != SUCCESS)
1042 return NULL;
1043
1044 if ((key = os_malloc(EAP_EMSK_LEN)) == NULL)
1045 return NULL;
1046
1047 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1048 *len = EAP_EMSK_LEN;
1049
1050 return key;
1051 }
1052
1053
eap_peer_pwd_register(void)1054 int eap_peer_pwd_register(void)
1055 {
1056 struct eap_method *eap;
1057
1058 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
1059 EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD");
1060 if (eap == NULL)
1061 return -1;
1062
1063 eap->init = eap_pwd_init;
1064 eap->deinit = eap_pwd_deinit;
1065 eap->process = eap_pwd_process;
1066 eap->isKeyAvailable = eap_pwd_key_available;
1067 eap->getKey = eap_pwd_getkey;
1068 eap->getSessionId = eap_pwd_get_session_id;
1069 eap->get_emsk = eap_pwd_get_emsk;
1070
1071 return eap_peer_method_register(eap);
1072 }
1073