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/sha1.h"
13 #include "crypto/sha256.h"
14 #include "crypto/sha512.h"
15 #include "crypto/ms_funcs.h"
16 #include "crypto/crypto.h"
17 #include "eap_peer/eap_i.h"
18 #include "eap_common/eap_pwd_common.h"
19
20
21 struct eap_pwd_data {
22 enum {
23 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req,
24 SUCCESS_ON_FRAG_COMPLETION, SUCCESS, FAILURE
25 } state;
26 u8 *id_peer;
27 size_t id_peer_len;
28 u8 *id_server;
29 size_t id_server_len;
30 u8 *password;
31 size_t password_len;
32 int password_hash;
33 struct wpa_freq_range_list allowed_groups;
34 u16 group_num;
35 u8 prep;
36 u8 token[4];
37 EAP_PWD_group *grp;
38
39 struct wpabuf *inbuf;
40 size_t in_frag_pos;
41 struct wpabuf *outbuf;
42 size_t out_frag_pos;
43 size_t mtu;
44
45 struct crypto_bignum *k;
46 struct crypto_bignum *private_value;
47 struct crypto_bignum *server_scalar;
48 struct crypto_bignum *my_scalar;
49 struct crypto_ec_point *my_element;
50 struct crypto_ec_point *server_element;
51
52 u8 msk[EAP_MSK_LEN];
53 u8 emsk[EAP_EMSK_LEN];
54 u8 session_id[1 + SHA256_MAC_LEN];
55 };
56
57
58 static void eap_pwd_deinit(struct eap_sm *sm, void *priv);
59
60
61 #ifndef CONFIG_NO_STDOUT_DEBUG
eap_pwd_state_txt(int state)62 static const char * eap_pwd_state_txt(int state)
63 {
64 switch (state) {
65 case PWD_ID_Req:
66 return "PWD-ID-Req";
67 case PWD_Commit_Req:
68 return "PWD-Commit-Req";
69 case PWD_Confirm_Req:
70 return "PWD-Confirm-Req";
71 case SUCCESS_ON_FRAG_COMPLETION:
72 return "SUCCESS_ON_FRAG_COMPLETION";
73 case SUCCESS:
74 return "SUCCESS";
75 case FAILURE:
76 return "FAILURE";
77 default:
78 return "PWD-UNK";
79 }
80 }
81 #endif /* CONFIG_NO_STDOUT_DEBUG */
82
83
eap_pwd_state(struct eap_pwd_data * data,int state)84 static void eap_pwd_state(struct eap_pwd_data *data, int state)
85 {
86 wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s",
87 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
88 data->state = state;
89 }
90
91
eap_pwd_init(struct eap_sm * sm)92 static void * eap_pwd_init(struct eap_sm *sm)
93 {
94 struct eap_pwd_data *data;
95 const u8 *identity, *password;
96 size_t identity_len, password_len;
97 int fragment_size;
98 int pwhash;
99 const char *phase1;
100
101 password = eap_get_config_password2(sm, &password_len, &pwhash);
102 if (password == NULL) {
103 wpa_printf(MSG_INFO, "EAP-PWD: No password configured!");
104 return NULL;
105 }
106
107 identity = eap_get_config_identity(sm, &identity_len);
108 if (identity == NULL) {
109 wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!");
110 return NULL;
111 }
112
113 if ((data = os_zalloc(sizeof(*data))) == NULL) {
114 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail");
115 return NULL;
116 }
117
118 if ((data->id_peer = os_malloc(identity_len)) == NULL) {
119 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
120 os_free(data);
121 return NULL;
122 }
123
124 os_memcpy(data->id_peer, identity, identity_len);
125 data->id_peer_len = identity_len;
126
127 if ((data->password = os_malloc(password_len)) == NULL) {
128 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail");
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 phase1 = eap_get_config_phase1(sm);
138 if (phase1) {
139 const char *pos, *end;
140 char *copy = NULL;
141 int res;
142
143 pos = os_strstr(phase1, "eap_pwd_groups=");
144 if (pos) {
145 pos += 15;
146 end = os_strchr(pos, ' ');
147 if (end) {
148 copy = os_zalloc(end - pos + 1);
149 if (!copy)
150 goto fail;
151 os_memcpy(copy, pos, end - pos);
152 pos = copy;
153 }
154 res = freq_range_list_parse(&data->allowed_groups, pos);
155 os_free(copy);
156 if (res)
157 goto fail;
158 }
159 }
160
161 data->out_frag_pos = data->in_frag_pos = 0;
162 data->inbuf = data->outbuf = NULL;
163 fragment_size = eap_get_config_fragment_size(sm);
164 if (fragment_size <= 0)
165 data->mtu = 1020; /* default from RFC 5931 */
166 else
167 data->mtu = fragment_size;
168
169 data->state = PWD_ID_Req;
170
171 return data;
172 fail:
173 eap_pwd_deinit(sm, data);
174 return NULL;
175 }
176
177
eap_pwd_deinit(struct eap_sm * sm,void * priv)178 static void eap_pwd_deinit(struct eap_sm *sm, void *priv)
179 {
180 struct eap_pwd_data *data = priv;
181
182 crypto_bignum_deinit(data->private_value, 1);
183 crypto_bignum_deinit(data->server_scalar, 1);
184 crypto_bignum_deinit(data->my_scalar, 1);
185 crypto_bignum_deinit(data->k, 1);
186 crypto_ec_point_deinit(data->my_element, 1);
187 crypto_ec_point_deinit(data->server_element, 1);
188 bin_clear_free(data->id_peer, data->id_peer_len);
189 bin_clear_free(data->id_server, data->id_server_len);
190 bin_clear_free(data->password, data->password_len);
191 if (data->grp) {
192 crypto_ec_deinit(data->grp->group);
193 crypto_ec_point_deinit(data->grp->pwe, 1);
194 os_free(data->grp);
195 }
196 wpabuf_free(data->inbuf);
197 wpabuf_free(data->outbuf);
198 os_free(data->allowed_groups.range);
199 bin_clear_free(data, sizeof(*data));
200 }
201
202
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)203 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
204 {
205 struct eap_pwd_data *data = priv;
206 u8 *key;
207
208 if (data->state != SUCCESS)
209 return NULL;
210
211 key = os_memdup(data->msk, EAP_MSK_LEN);
212 if (key == NULL)
213 return NULL;
214
215 *len = EAP_MSK_LEN;
216
217 return key;
218 }
219
220
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)221 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
222 {
223 struct eap_pwd_data *data = priv;
224 u8 *id;
225
226 if (data->state != SUCCESS)
227 return NULL;
228
229 id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN);
230 if (id == NULL)
231 return NULL;
232
233 *len = 1 + SHA256_MAC_LEN;
234
235 return id;
236 }
237
238
eap_pwd_allowed_group(struct eap_pwd_data * data,u16 group)239 static int eap_pwd_allowed_group(struct eap_pwd_data *data, u16 group)
240 {
241 if (!data->allowed_groups.range) {
242 /* By default, allow the groups using NIST curves P-256, P-384,
243 * and P-521. */
244 return group == 19 || group == 20 || group == 21;
245 }
246
247 return freq_range_list_includes(&data->allowed_groups, group);
248 }
249
250
251 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)252 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
253 struct eap_method_ret *ret,
254 const struct wpabuf *reqData,
255 const u8 *payload, size_t payload_len)
256 {
257 struct eap_pwd_id *id;
258
259 if (data->state != PWD_ID_Req) {
260 ret->ignore = true;
261 eap_pwd_state(data, FAILURE);
262 return;
263 }
264
265 if (payload_len < sizeof(struct eap_pwd_id)) {
266 ret->ignore = true;
267 eap_pwd_state(data, FAILURE);
268 return;
269 }
270
271 id = (struct eap_pwd_id *) payload;
272 data->group_num = be_to_host16(id->group_num);
273 wpa_printf(MSG_DEBUG,
274 "EAP-PWD: Server EAP-pwd-ID proposal: group=%u random=%u prf=%u prep=%u",
275 data->group_num, id->random_function, id->prf, id->prep);
276 if (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC ||
277 id->prf != EAP_PWD_DEFAULT_PRF ||
278 !eap_pwd_allowed_group(data, data->group_num)) {
279 wpa_printf(MSG_INFO,
280 "EAP-pwd: Unsupported or disabled proposal");
281 eap_pwd_state(data, FAILURE);
282 return;
283 }
284
285 if (id->prep != EAP_PWD_PREP_NONE &&
286 id->prep != EAP_PWD_PREP_MS &&
287 id->prep != EAP_PWD_PREP_SSHA1 &&
288 id->prep != EAP_PWD_PREP_SSHA256 &&
289 id->prep != EAP_PWD_PREP_SSHA512) {
290 wpa_printf(MSG_DEBUG,
291 "EAP-PWD: Unsupported password pre-processing technique (Prep=%u)",
292 id->prep);
293 eap_pwd_state(data, FAILURE);
294 return;
295 }
296
297 if (id->prep == EAP_PWD_PREP_NONE && data->password_hash) {
298 wpa_printf(MSG_DEBUG,
299 "EAP-PWD: Unhashed password not available");
300 eap_pwd_state(data, FAILURE);
301 return;
302 }
303
304 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
305 data->group_num);
306
307 data->prep = id->prep;
308 os_memcpy(data->token, id->token, sizeof(id->token));
309
310 if (data->id_server || data->grp) {
311 wpa_printf(MSG_INFO, "EAP-pwd: data was already allocated");
312 eap_pwd_state(data, FAILURE);
313 return;
314 }
315
316 data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
317 if (data->id_server == NULL) {
318 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
319 eap_pwd_state(data, FAILURE);
320 return;
321 }
322 data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
323 os_memcpy(data->id_server, id->identity, data->id_server_len);
324 wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of",
325 data->id_server, data->id_server_len);
326
327 data->grp = get_eap_pwd_group(data->group_num);
328 if (data->grp == NULL) {
329 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
330 "group");
331 eap_pwd_state(data, FAILURE);
332 return;
333 }
334
335 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
336 data->id_peer_len);
337 if (data->outbuf == NULL) {
338 eap_pwd_state(data, FAILURE);
339 return;
340 }
341 wpabuf_put_be16(data->outbuf, data->group_num);
342 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
343 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
344 wpabuf_put_data(data->outbuf, id->token, sizeof(id->token));
345 wpabuf_put_u8(data->outbuf, id->prep);
346 wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
347
348 eap_pwd_state(data, PWD_Commit_Req);
349 }
350
351
352 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)353 eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
354 struct eap_method_ret *ret,
355 const struct wpabuf *reqData,
356 const u8 *payload, size_t payload_len)
357 {
358 struct crypto_ec_point *K = NULL;
359 struct crypto_bignum *mask = NULL;
360 const u8 *ptr = payload;
361 u8 *scalar, *element;
362 size_t prime_len, order_len;
363 const u8 *password;
364 size_t password_len;
365 u8 pwhashhash[16];
366 const u8 *salt_pwd[2];
367 size_t salt_pwd_len[2], exp_len;
368 u8 salt_len, salthashpwd[64]; /* 64 = SHA512_DIGEST_LENGTH */
369 int res;
370
371 if (data->state != PWD_Commit_Req) {
372 ret->ignore = true;
373 goto fin;
374 }
375
376 if (!data->grp) {
377 wpa_printf(MSG_DEBUG,
378 "EAP-PWD (client): uninitialized EAP-pwd group");
379 ret->ignore = true;
380 goto fin;
381 }
382
383 prime_len = crypto_ec_prime_len(data->grp->group);
384 order_len = crypto_ec_order_len(data->grp->group);
385
386 switch (data->prep) {
387 case EAP_PWD_PREP_MS:
388 wpa_printf(MSG_DEBUG,
389 "EAP-pwd commit request, password prep is MS");
390 #ifdef CONFIG_FIPS
391 wpa_printf(MSG_ERROR,
392 "EAP-PWD (peer): MS password hash not supported in FIPS mode");
393 eap_pwd_state(data, FAILURE);
394 return;
395 #else /* CONFIG_FIPS */
396 if (payload_len != 2 * prime_len + order_len) {
397 wpa_printf(MSG_INFO,
398 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
399 (unsigned int) payload_len,
400 (unsigned int) (2 * prime_len + order_len));
401 goto fin;
402 }
403 if (data->password_hash) {
404 res = hash_nt_password_hash(data->password, pwhashhash);
405 } else {
406 u8 pwhash[16];
407
408 res = nt_password_hash(data->password,
409 data->password_len, pwhash);
410 if (res == 0)
411 res = hash_nt_password_hash(pwhash, pwhashhash);
412 forced_memzero(pwhash, sizeof(pwhash));
413 }
414
415 if (res) {
416 eap_pwd_state(data, FAILURE);
417 return;
418 }
419
420 password = pwhashhash;
421 password_len = sizeof(pwhashhash);
422 #endif /* CONFIG_FIPS */
423 break;
424 case EAP_PWD_PREP_SSHA1:
425 wpa_printf(MSG_DEBUG,
426 "EAP-pwd commit request, password prep is salted sha1");
427 if (payload_len < 1 || *ptr == 0) {
428 wpa_printf(MSG_DEBUG, "EAP-pwd: Invalid Salt-len");
429 goto fin;
430 }
431 salt_len = *ptr++;
432 exp_len = 1 + salt_len + 2 * prime_len + order_len;
433 if (payload_len != exp_len) {
434 wpa_printf(MSG_INFO,
435 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
436 (unsigned int) payload_len,
437 (unsigned int) exp_len);
438 goto fin;
439 }
440
441 /* salted-password = Hash(password | salt) */
442 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Unsalted password",
443 data->password, data->password_len);
444 wpa_hexdump(MSG_DEBUG, "EAP-pwd: Salt", ptr, salt_len);
445 salt_pwd[0] = data->password;
446 salt_pwd[1] = ptr;
447 salt_pwd_len[0] = data->password_len;
448 salt_pwd_len[1] = salt_len;
449 if (sha1_vector(2, salt_pwd, salt_pwd_len, salthashpwd) < 0)
450 goto fin;
451
452 wpa_printf(MSG_DEBUG,
453 "EAP-pwd: sha1 hashed %d byte salt with password",
454 (int) salt_len);
455 ptr += salt_len;
456 password = salthashpwd;
457 password_len = SHA1_MAC_LEN;
458 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Salted password",
459 password, password_len);
460 break;
461 case EAP_PWD_PREP_SSHA256:
462 wpa_printf(MSG_DEBUG,
463 "EAP-pwd commit request, password prep is salted sha256");
464 if (payload_len < 1 || *ptr == 0) {
465 wpa_printf(MSG_DEBUG, "EAP-pwd: Invalid Salt-len");
466 goto fin;
467 }
468 salt_len = *ptr++;
469 exp_len = 1 + salt_len + 2 * prime_len + order_len;
470 if (payload_len != exp_len) {
471 wpa_printf(MSG_INFO,
472 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
473 (unsigned int) payload_len,
474 (unsigned int) exp_len);
475 goto fin;
476 }
477
478 /* salted-password = Hash(password | salt) */
479 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Unsalted password",
480 data->password, data->password_len);
481 wpa_hexdump(MSG_DEBUG, "EAP-pwd: Salt", ptr, salt_len);
482 salt_pwd[0] = data->password;
483 salt_pwd[1] = ptr;
484 salt_pwd_len[0] = data->password_len;
485 salt_pwd_len[1] = salt_len;
486 if (sha256_vector(2, salt_pwd, salt_pwd_len, salthashpwd) < 0)
487 goto fin;
488
489 ptr += salt_len;
490 password = salthashpwd;
491 password_len = SHA256_MAC_LEN;
492 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Salted password",
493 password, password_len);
494 break;
495 #ifdef CONFIG_SHA512
496 case EAP_PWD_PREP_SSHA512:
497 wpa_printf(MSG_DEBUG,
498 "EAP-pwd commit request, password prep is salted sha512");
499 if (payload_len < 1 || *ptr == 0) {
500 wpa_printf(MSG_DEBUG, "EAP-pwd: Invalid Salt-len");
501 goto fin;
502 }
503 salt_len = *ptr++;
504 exp_len = 1 + salt_len + 2 * prime_len + order_len;
505 if (payload_len != exp_len) {
506 wpa_printf(MSG_INFO,
507 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
508 (unsigned int) payload_len,
509 (unsigned int) exp_len);
510 goto fin;
511 }
512
513 /* salted-password = Hash(password | salt) */
514 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Unsalted password",
515 data->password, data->password_len);
516 wpa_hexdump(MSG_DEBUG, "EAP-pwd: Salt", ptr, salt_len);
517 salt_pwd[0] = data->password;
518 salt_pwd[1] = ptr;
519 salt_pwd_len[0] = data->password_len;
520 salt_pwd_len[1] = salt_len;
521 if (sha512_vector(2, salt_pwd, salt_pwd_len, salthashpwd) < 0)
522 goto fin;
523
524 ptr += salt_len;
525 password = salthashpwd;
526 password_len = SHA512_MAC_LEN;
527 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: Salted password",
528 password, password_len);
529 break;
530 #endif /* CONFIG_SHA512 */
531 case EAP_PWD_PREP_NONE:
532 wpa_printf(MSG_DEBUG,
533 "EAP-pwd commit request, password prep is NONE");
534 if (data->password_hash) {
535 wpa_printf(MSG_DEBUG,
536 "EAP-PWD: Unhashed password not available");
537 eap_pwd_state(data, FAILURE);
538 return;
539 }
540 if (payload_len != 2 * prime_len + order_len) {
541 wpa_printf(MSG_INFO,
542 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
543 (unsigned int) payload_len,
544 (unsigned int) (2 * prime_len + order_len));
545 goto fin;
546 }
547 password = data->password;
548 password_len = data->password_len;
549 break;
550 default:
551 wpa_printf(MSG_DEBUG,
552 "EAP-pwd: Unsupported password pre-processing technique (Prep=%u)",
553 data->prep);
554 eap_pwd_state(data, FAILURE);
555 return;
556 }
557
558 /* compute PWE */
559 res = compute_password_element(data->grp, data->group_num,
560 password, password_len,
561 data->id_server, data->id_server_len,
562 data->id_peer, data->id_peer_len,
563 data->token);
564 forced_memzero(pwhashhash, sizeof(pwhashhash));
565 forced_memzero(salthashpwd, sizeof(salthashpwd));
566 if (res) {
567 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
568 eap_pwd_state(data, FAILURE);
569 return;
570 }
571
572 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
573 (int) crypto_ec_prime_len_bits(data->grp->group));
574
575 data->private_value = crypto_bignum_init();
576 data->my_element = crypto_ec_point_init(data->grp->group);
577 data->my_scalar = crypto_bignum_init();
578 mask = crypto_bignum_init();
579 if (!data->private_value || !data->my_element ||
580 !data->my_scalar || !mask) {
581 wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail");
582 goto fin;
583 }
584
585 if (eap_pwd_get_rand_mask(data->grp, data->private_value, mask,
586 data->my_scalar) < 0)
587 goto fin;
588
589 if (crypto_ec_point_mul(data->grp->group, data->grp->pwe, mask,
590 data->my_element) < 0) {
591 wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation "
592 "fail");
593 eap_pwd_state(data, FAILURE);
594 goto fin;
595 }
596
597 if (crypto_ec_point_invert(data->grp->group, data->my_element) < 0) {
598 wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail");
599 goto fin;
600 }
601
602 /* process the request */
603 data->k = crypto_bignum_init();
604 K = crypto_ec_point_init(data->grp->group);
605 if (!data->k || !K) {
606 wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation "
607 "fail");
608 goto fin;
609 }
610
611 /* element, x then y, followed by scalar */
612 data->server_element = eap_pwd_get_element(data->grp, ptr);
613 if (!data->server_element) {
614 wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element "
615 "fail");
616 goto fin;
617 }
618 ptr += prime_len * 2;
619 data->server_scalar = eap_pwd_get_scalar(data->grp, ptr);
620 if (!data->server_scalar) {
621 wpa_printf(MSG_INFO,
622 "EAP-PWD (peer): setting peer scalar fail");
623 goto fin;
624 }
625
626 /* compute the shared key, k */
627 if (crypto_ec_point_mul(data->grp->group, data->grp->pwe,
628 data->server_scalar, K) < 0 ||
629 crypto_ec_point_add(data->grp->group, K, data->server_element,
630 K) < 0 ||
631 crypto_ec_point_mul(data->grp->group, K, data->private_value,
632 K) < 0) {
633 wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key "
634 "fail");
635 goto fin;
636 }
637
638 /*
639 * This check is strictly speaking just for the case where
640 * co-factor > 1 but it was suggested that even though this is probably
641 * never going to happen it is a simple and safe check "just to be
642 * sure" so let's be safe.
643 */
644 if (crypto_ec_point_is_at_infinity(data->grp->group, K)) {
645 wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at "
646 "infinity!\n");
647 goto fin;
648 }
649
650 if (crypto_ec_point_x(data->grp->group, K, data->k) < 0) {
651 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract "
652 "shared secret from point");
653 goto fin;
654 }
655
656 /* now do the response */
657 data->outbuf = wpabuf_alloc(2 * prime_len + order_len);
658 if (data->outbuf == NULL)
659 goto fin;
660 /* We send the element as (x,y) followed by the scalar */
661 element = wpabuf_put(data->outbuf, 2 * prime_len);
662 scalar = wpabuf_put(data->outbuf, order_len);
663
664 /*
665 * bignums occupy as little memory as possible so one that is
666 * sufficiently smaller than the prime or order might need pre-pending
667 * with zeros.
668 */
669 crypto_bignum_to_bin(data->my_scalar, scalar, order_len, order_len);
670 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, element,
671 element + prime_len) != 0) {
672 wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail");
673 goto fin;
674 }
675
676 fin:
677 crypto_bignum_deinit(mask, 1);
678 crypto_ec_point_deinit(K, 1);
679 if (data->outbuf == NULL)
680 eap_pwd_state(data, FAILURE);
681 else
682 eap_pwd_state(data, PWD_Confirm_Req);
683 }
684
685
686 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)687 eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
688 struct eap_method_ret *ret,
689 const struct wpabuf *reqData,
690 const u8 *payload, size_t payload_len)
691 {
692 struct crypto_hash *hash = NULL;
693 u32 cs;
694 u16 grp;
695 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
696 size_t prime_len = 0, order_len = 0;
697
698 if (data->state != PWD_Confirm_Req) {
699 ret->ignore = true;
700 goto fin;
701 }
702
703 if (payload_len != SHA256_MAC_LEN) {
704 wpa_printf(MSG_INFO,
705 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
706 (unsigned int) payload_len, SHA256_MAC_LEN);
707 goto fin;
708 }
709
710 prime_len = crypto_ec_prime_len(data->grp->group);
711 order_len = crypto_ec_order_len(data->grp->group);
712
713 /*
714 * first build up the ciphersuite which is group | random_function |
715 * prf
716 */
717 grp = htons(data->group_num);
718 ptr = (u8 *) &cs;
719 os_memcpy(ptr, &grp, sizeof(u16));
720 ptr += sizeof(u16);
721 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
722 ptr += sizeof(u8);
723 *ptr = EAP_PWD_DEFAULT_PRF;
724
725 /* each component of the point will be at most as big as the prime */
726 cruft = os_malloc(prime_len * 2);
727 if (!cruft) {
728 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
729 "fail");
730 goto fin;
731 }
732
733 /*
734 * server's commit is H(k | server_element | server_scalar |
735 * peer_element | peer_scalar | ciphersuite)
736 */
737 hash = eap_pwd_h_init();
738 if (hash == NULL)
739 goto fin;
740
741 /*
742 * zero the memory each time because this is mod prime math and some
743 * value may start with a few zeros and the previous one did not.
744 */
745 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
746 eap_pwd_h_update(hash, cruft, prime_len);
747
748 /* server element: x, y */
749 if (crypto_ec_point_to_bin(data->grp->group, data->server_element,
750 cruft, cruft + prime_len) != 0) {
751 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
752 "assignment fail");
753 goto fin;
754 }
755 eap_pwd_h_update(hash, cruft, prime_len * 2);
756
757 /* server scalar */
758 crypto_bignum_to_bin(data->server_scalar, cruft, order_len, order_len);
759 eap_pwd_h_update(hash, cruft, order_len);
760
761 /* my element: x, y */
762 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
763 cruft + prime_len) != 0) {
764 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
765 "assignment fail");
766 goto fin;
767 }
768 eap_pwd_h_update(hash, cruft, prime_len * 2);
769
770 /* my scalar */
771 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
772 eap_pwd_h_update(hash, cruft, order_len);
773
774 /* the ciphersuite */
775 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
776
777 /* random function fin */
778 eap_pwd_h_final(hash, conf);
779 hash = NULL;
780
781 ptr = (u8 *) payload;
782 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
783 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
784 goto fin;
785 }
786
787 wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified");
788
789 /*
790 * compute confirm:
791 * H(k | peer_element | peer_scalar | server_element | server_scalar |
792 * ciphersuite)
793 */
794 hash = eap_pwd_h_init();
795 if (hash == NULL)
796 goto fin;
797
798 /* k */
799 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
800 eap_pwd_h_update(hash, cruft, prime_len);
801
802 /* my element */
803 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
804 cruft + prime_len) != 0) {
805 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
806 "assignment fail");
807 goto fin;
808 }
809 eap_pwd_h_update(hash, cruft, prime_len * 2);
810
811 /* my scalar */
812 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
813 eap_pwd_h_update(hash, cruft, order_len);
814
815 /* server element: x, y */
816 if (crypto_ec_point_to_bin(data->grp->group, data->server_element,
817 cruft, cruft + prime_len) != 0) {
818 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
819 "assignment fail");
820 goto fin;
821 }
822 eap_pwd_h_update(hash, cruft, prime_len * 2);
823
824 /* server scalar */
825 crypto_bignum_to_bin(data->server_scalar, cruft, order_len, order_len);
826 eap_pwd_h_update(hash, cruft, order_len);
827
828 /* the ciphersuite */
829 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
830
831 /* all done */
832 eap_pwd_h_final(hash, conf);
833 hash = NULL;
834
835 if (compute_keys(data->grp, data->k,
836 data->my_scalar, data->server_scalar, conf, ptr,
837 &cs, data->msk, data->emsk, data->session_id) < 0) {
838 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
839 "EMSK");
840 goto fin;
841 }
842
843 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
844 if (data->outbuf == NULL)
845 goto fin;
846
847 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
848
849 fin:
850 bin_clear_free(cruft, prime_len * 2);
851 if (data->outbuf == NULL) {
852 ret->methodState = METHOD_DONE;
853 ret->decision = DECISION_FAIL;
854 eap_pwd_state(data, FAILURE);
855 } else {
856 eap_pwd_state(data, SUCCESS_ON_FRAG_COMPLETION);
857 }
858
859 /* clean allocated memory */
860 if (hash)
861 eap_pwd_h_final(hash, conf);
862 }
863
864
865 static struct wpabuf *
eap_pwd_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)866 eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
867 const struct wpabuf *reqData)
868 {
869 struct eap_pwd_data *data = priv;
870 struct wpabuf *resp = NULL;
871 const u8 *pos, *buf;
872 size_t len;
873 u16 tot_len = 0;
874 u8 lm_exch;
875
876 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
877 if ((pos == NULL) || (len < 1)) {
878 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
879 "len is %d",
880 pos == NULL ? "NULL" : "not NULL", (int) len);
881 ret->ignore = true;
882 return NULL;
883 }
884
885 ret->ignore = false;
886 ret->methodState = METHOD_MAY_CONT;
887 ret->decision = DECISION_FAIL;
888 ret->allowNotifications = false;
889
890 lm_exch = *pos;
891 pos++; /* skip over the bits and the exch */
892 len--;
893
894 /*
895 * we're fragmenting so send out the next fragment
896 */
897 if (data->out_frag_pos) {
898 /*
899 * this should be an ACK
900 */
901 if (len)
902 wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
903 "not an ACK");
904
905 wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
906 /*
907 * check if there are going to be more fragments
908 */
909 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
910 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
911 len = data->mtu - EAP_PWD_HDR_SIZE;
912 EAP_PWD_SET_MORE_BIT(lm_exch);
913 }
914 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
915 EAP_PWD_HDR_SIZE + len,
916 EAP_CODE_RESPONSE, eap_get_id(reqData));
917 if (resp == NULL) {
918 wpa_printf(MSG_INFO, "Unable to allocate memory for "
919 "next fragment!");
920 return NULL;
921 }
922 wpabuf_put_u8(resp, lm_exch);
923 buf = wpabuf_head_u8(data->outbuf);
924 wpabuf_put_data(resp, buf + data->out_frag_pos, len);
925 data->out_frag_pos += len;
926 /*
927 * this is the last fragment so get rid of the out buffer
928 */
929 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
930 wpabuf_free(data->outbuf);
931 data->outbuf = NULL;
932 data->out_frag_pos = 0;
933 }
934 wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
935 data->out_frag_pos == 0 ? "last" : "next",
936 (int) len);
937 if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
938 ret->methodState = METHOD_DONE;
939 ret->decision = DECISION_UNCOND_SUCC;
940 eap_pwd_state(data, SUCCESS);
941 }
942 return resp;
943 }
944
945 /*
946 * see if this is a fragment that needs buffering
947 *
948 * if it's the first fragment there'll be a length field
949 */
950 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
951 if (len < 2) {
952 wpa_printf(MSG_DEBUG,
953 "EAP-pwd: Frame too short to contain Total-Length field");
954 ret->ignore = true;
955 return NULL;
956 }
957 tot_len = WPA_GET_BE16(pos);
958 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
959 "total length = %d", tot_len);
960 if (tot_len > 15000)
961 return NULL;
962 if (data->inbuf) {
963 wpa_printf(MSG_DEBUG,
964 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
965 ret->ignore = true;
966 return NULL;
967 }
968 data->inbuf = wpabuf_alloc(tot_len);
969 if (data->inbuf == NULL) {
970 wpa_printf(MSG_INFO, "Out of memory to buffer "
971 "fragments!");
972 return NULL;
973 }
974 data->in_frag_pos = 0;
975 pos += sizeof(u16);
976 len -= sizeof(u16);
977 }
978 /*
979 * buffer and ACK the fragment
980 */
981 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
982 if (!data->inbuf) {
983 wpa_printf(MSG_DEBUG,
984 "EAP-pwd: No buffer for reassembly");
985 ret->methodState = METHOD_DONE;
986 ret->decision = DECISION_FAIL;
987 return NULL;
988 }
989 data->in_frag_pos += len;
990 if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
991 wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
992 "detected (%d vs. %d)!",
993 (int) data->in_frag_pos,
994 (int) wpabuf_len(data->inbuf));
995 wpabuf_free(data->inbuf);
996 data->inbuf = NULL;
997 data->in_frag_pos = 0;
998 return NULL;
999 }
1000 wpabuf_put_data(data->inbuf, pos, len);
1001 }
1002 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
1003 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
1004 EAP_PWD_HDR_SIZE,
1005 EAP_CODE_RESPONSE, eap_get_id(reqData));
1006 if (resp != NULL)
1007 wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
1008 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
1009 (int) len);
1010 return resp;
1011 }
1012 /*
1013 * we're buffering and this is the last fragment
1014 */
1015 if (data->in_frag_pos && data->inbuf) {
1016 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
1017 (int) len);
1018 pos = wpabuf_head_u8(data->inbuf);
1019 len = data->in_frag_pos;
1020 }
1021 wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
1022 EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
1023
1024 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
1025 case EAP_PWD_OPCODE_ID_EXCH:
1026 eap_pwd_perform_id_exchange(sm, data, ret, reqData,
1027 pos, len);
1028 break;
1029 case EAP_PWD_OPCODE_COMMIT_EXCH:
1030 eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
1031 pos, len);
1032 break;
1033 case EAP_PWD_OPCODE_CONFIRM_EXCH:
1034 eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
1035 pos, len);
1036 break;
1037 default:
1038 wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
1039 "opcode %d", lm_exch);
1040 break;
1041 }
1042 /*
1043 * if we buffered the just processed input now's the time to free it
1044 */
1045 if (data->in_frag_pos) {
1046 wpabuf_free(data->inbuf);
1047 data->inbuf = NULL;
1048 data->in_frag_pos = 0;
1049 }
1050
1051 if (data->outbuf == NULL) {
1052 ret->methodState = METHOD_DONE;
1053 ret->decision = DECISION_FAIL;
1054 return NULL; /* generic failure */
1055 }
1056
1057 /*
1058 * we have output! Do we need to fragment it?
1059 */
1060 lm_exch = EAP_PWD_GET_EXCHANGE(lm_exch);
1061 len = wpabuf_len(data->outbuf);
1062 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
1063 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
1064 EAP_CODE_RESPONSE, eap_get_id(reqData));
1065 /*
1066 * if so it's the first so include a length field
1067 */
1068 EAP_PWD_SET_LENGTH_BIT(lm_exch);
1069 EAP_PWD_SET_MORE_BIT(lm_exch);
1070 tot_len = len;
1071 /*
1072 * keep the packet at the MTU
1073 */
1074 len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
1075 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
1076 "length = %d", tot_len);
1077 } else {
1078 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
1079 EAP_PWD_HDR_SIZE + len,
1080 EAP_CODE_RESPONSE, eap_get_id(reqData));
1081 }
1082 if (resp == NULL)
1083 return NULL;
1084
1085 wpabuf_put_u8(resp, lm_exch);
1086 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
1087 wpabuf_put_be16(resp, tot_len);
1088 data->out_frag_pos += len;
1089 }
1090 buf = wpabuf_head_u8(data->outbuf);
1091 wpabuf_put_data(resp, buf, len);
1092 /*
1093 * if we're not fragmenting then there's no need to carry this around
1094 */
1095 if (data->out_frag_pos == 0) {
1096 wpabuf_free(data->outbuf);
1097 data->outbuf = NULL;
1098 data->out_frag_pos = 0;
1099 if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
1100 ret->methodState = METHOD_DONE;
1101 ret->decision = DECISION_UNCOND_SUCC;
1102 eap_pwd_state(data, SUCCESS);
1103 }
1104 }
1105
1106 return resp;
1107 }
1108
1109
eap_pwd_key_available(struct eap_sm * sm,void * priv)1110 static bool eap_pwd_key_available(struct eap_sm *sm, void *priv)
1111 {
1112 struct eap_pwd_data *data = priv;
1113 return data->state == SUCCESS;
1114 }
1115
1116
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)1117 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1118 {
1119 struct eap_pwd_data *data = priv;
1120 u8 *key;
1121
1122 if (data->state != SUCCESS)
1123 return NULL;
1124
1125 if ((key = os_malloc(EAP_EMSK_LEN)) == NULL)
1126 return NULL;
1127
1128 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1129 *len = EAP_EMSK_LEN;
1130
1131 return key;
1132 }
1133
1134
eap_peer_pwd_register(void)1135 int eap_peer_pwd_register(void)
1136 {
1137 struct eap_method *eap;
1138
1139 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
1140 EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD");
1141 if (eap == NULL)
1142 return -1;
1143
1144 eap->init = eap_pwd_init;
1145 eap->deinit = eap_pwd_deinit;
1146 eap->process = eap_pwd_process;
1147 eap->isKeyAvailable = eap_pwd_key_available;
1148 eap->getKey = eap_pwd_getkey;
1149 eap->getSessionId = eap_pwd_get_session_id;
1150 eap->get_emsk = eap_pwd_get_emsk;
1151
1152 return eap_peer_method_register(eap);
1153 }
1154
