1 /*
2 * hostapd / EAP-pwd (RFC 5931) server
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 "crypto/crypto.h"
15 #include "eap_server/eap_i.h"
16 #include "eap_common/eap_pwd_common.h"
17
18
19 struct eap_pwd_data {
20 enum {
21 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, 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 u8 *salt;
31 size_t salt_len;
32 u32 token;
33 u16 group_num;
34 u8 password_prep;
35 EAP_PWD_group *grp;
36
37 struct wpabuf *inbuf;
38 size_t in_frag_pos;
39 struct wpabuf *outbuf;
40 size_t out_frag_pos;
41 size_t mtu;
42
43 struct crypto_bignum *k;
44 struct crypto_bignum *private_value;
45 struct crypto_bignum *peer_scalar;
46 struct crypto_bignum *my_scalar;
47 struct crypto_ec_point *my_element;
48 struct crypto_ec_point *peer_element;
49
50 u8 my_confirm[SHA256_MAC_LEN];
51
52 u8 msk[EAP_MSK_LEN];
53 u8 emsk[EAP_EMSK_LEN];
54 u8 session_id[1 + SHA256_MAC_LEN];
55 };
56
57
eap_pwd_state_txt(int state)58 static const char * eap_pwd_state_txt(int state)
59 {
60 switch (state) {
61 case PWD_ID_Req:
62 return "PWD-ID-Req";
63 case PWD_Commit_Req:
64 return "PWD-Commit-Req";
65 case PWD_Confirm_Req:
66 return "PWD-Confirm-Req";
67 case SUCCESS:
68 return "SUCCESS";
69 case FAILURE:
70 return "FAILURE";
71 default:
72 return "PWD-Unk";
73 }
74 }
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
89 if (sm->user == NULL || sm->user->password == NULL ||
90 sm->user->password_len == 0) {
91 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
92 "configured");
93 return NULL;
94 }
95
96 data = os_zalloc(sizeof(*data));
97 if (data == NULL)
98 return NULL;
99
100 data->group_num = sm->cfg->pwd_group;
101 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
102 data->group_num);
103 data->state = PWD_ID_Req;
104
105 data->id_server = (u8 *) os_strdup("server");
106 if (data->id_server)
107 data->id_server_len = os_strlen((char *) data->id_server);
108
109 data->password = os_malloc(sm->user->password_len);
110 if (data->password == NULL) {
111 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
112 "fail");
113 bin_clear_free(data->id_server, data->id_server_len);
114 os_free(data);
115 return NULL;
116 }
117 data->password_len = sm->user->password_len;
118 os_memcpy(data->password, sm->user->password, data->password_len);
119 data->password_hash = sm->user->password_hash;
120
121 data->salt_len = sm->user->salt_len;
122 if (data->salt_len) {
123 data->salt = os_memdup(sm->user->salt, sm->user->salt_len);
124 if (!data->salt) {
125 wpa_printf(MSG_INFO,
126 "EAP-pwd: Memory allocation of salt failed");
127 bin_clear_free(data->id_server, data->id_server_len);
128 bin_clear_free(data->password, data->password_len);
129 os_free(data);
130 return NULL;
131 }
132 }
133
134 data->in_frag_pos = data->out_frag_pos = 0;
135 data->inbuf = data->outbuf = NULL;
136 /* use default MTU from RFC 5931 if not configured otherwise */
137 data->mtu = sm->cfg->fragment_size > 0 ? sm->cfg->fragment_size : 1020;
138
139 return data;
140 }
141
142
eap_pwd_reset(struct eap_sm * sm,void * priv)143 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
144 {
145 struct eap_pwd_data *data = priv;
146
147 crypto_bignum_deinit(data->private_value, 1);
148 crypto_bignum_deinit(data->peer_scalar, 1);
149 crypto_bignum_deinit(data->my_scalar, 1);
150 crypto_bignum_deinit(data->k, 1);
151 crypto_ec_point_deinit(data->my_element, 1);
152 crypto_ec_point_deinit(data->peer_element, 1);
153 bin_clear_free(data->id_peer, data->id_peer_len);
154 bin_clear_free(data->id_server, data->id_server_len);
155 bin_clear_free(data->password, data->password_len);
156 bin_clear_free(data->salt, data->salt_len);
157 if (data->grp) {
158 crypto_ec_deinit(data->grp->group);
159 crypto_ec_point_deinit(data->grp->pwe, 1);
160 os_free(data->grp);
161 }
162 wpabuf_free(data->inbuf);
163 wpabuf_free(data->outbuf);
164 bin_clear_free(data, sizeof(*data));
165 }
166
167
eap_pwd_build_id_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)168 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
169 u8 id)
170 {
171 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
172 /*
173 * if we're fragmenting then we already have an id request, just return
174 */
175 if (data->out_frag_pos)
176 return;
177
178 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
179 data->id_server_len);
180 if (data->outbuf == NULL) {
181 eap_pwd_state(data, FAILURE);
182 return;
183 }
184
185 if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) {
186 wpabuf_free(data->outbuf);
187 data->outbuf = NULL;
188 eap_pwd_state(data, FAILURE);
189 return;
190 }
191
192 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd (server): password",
193 data->password, data->password_len);
194 if (data->salt_len)
195 wpa_hexdump(MSG_DEBUG, "EAP-pwd (server): salt",
196 data->salt, data->salt_len);
197
198 /*
199 * If this is a salted password then figure out how it was hashed
200 * based on the length.
201 */
202 if (data->salt_len) {
203 switch (data->password_len) {
204 case 20:
205 data->password_prep = EAP_PWD_PREP_SSHA1;
206 break;
207 case 32:
208 data->password_prep = EAP_PWD_PREP_SSHA256;
209 break;
210 case 64:
211 data->password_prep = EAP_PWD_PREP_SSHA512;
212 break;
213 default:
214 wpa_printf(MSG_INFO,
215 "EAP-pwd (server): bad size %d for salted password",
216 (int) data->password_len);
217 eap_pwd_state(data, FAILURE);
218 return;
219 }
220 } else {
221 /* Otherwise, figure out whether it's MS hashed or plain */
222 data->password_prep = data->password_hash ? EAP_PWD_PREP_MS :
223 EAP_PWD_PREP_NONE;
224 }
225
226 wpabuf_put_be16(data->outbuf, data->group_num);
227 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
228 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
229 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
230 wpabuf_put_u8(data->outbuf, data->password_prep);
231 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
232 }
233
234
eap_pwd_build_commit_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)235 static void eap_pwd_build_commit_req(struct eap_sm *sm,
236 struct eap_pwd_data *data, u8 id)
237 {
238 struct crypto_bignum *mask = NULL;
239 u8 *scalar, *element;
240 size_t prime_len, order_len;
241
242 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
243 /*
244 * if we're fragmenting then we already have an commit request, just
245 * return
246 */
247 if (data->out_frag_pos)
248 return;
249
250 prime_len = crypto_ec_prime_len(data->grp->group);
251 order_len = crypto_ec_order_len(data->grp->group);
252
253 data->private_value = crypto_bignum_init();
254 data->my_element = crypto_ec_point_init(data->grp->group);
255 data->my_scalar = crypto_bignum_init();
256 mask = crypto_bignum_init();
257 if (!data->private_value || !data->my_element || !data->my_scalar ||
258 !mask) {
259 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
260 "fail");
261 goto fin;
262 }
263
264 if (eap_pwd_get_rand_mask(data->grp, data->private_value, mask,
265 data->my_scalar) < 0)
266 goto fin;
267
268 if (crypto_ec_point_mul(data->grp->group, data->grp->pwe, mask,
269 data->my_element) < 0) {
270 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
271 "fail");
272 eap_pwd_state(data, FAILURE);
273 goto fin;
274 }
275
276 if (crypto_ec_point_invert(data->grp->group, data->my_element) < 0) {
277 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
278 "fail");
279 goto fin;
280 }
281
282 data->outbuf = wpabuf_alloc(2 * prime_len + order_len +
283 (data->salt ? 1 + data->salt_len : 0));
284 if (data->outbuf == NULL)
285 goto fin;
286
287 /* If we're doing salted password prep, add the salt */
288 if (data->salt_len) {
289 wpabuf_put_u8(data->outbuf, data->salt_len);
290 wpabuf_put_data(data->outbuf, data->salt, data->salt_len);
291 }
292
293 /* We send the element as (x,y) followed by the scalar */
294 element = wpabuf_put(data->outbuf, 2 * prime_len);
295 scalar = wpabuf_put(data->outbuf, order_len);
296 crypto_bignum_to_bin(data->my_scalar, scalar, order_len, order_len);
297 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, element,
298 element + prime_len) < 0) {
299 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
300 "fail");
301 goto fin;
302 }
303
304 fin:
305 crypto_bignum_deinit(mask, 1);
306 if (data->outbuf == NULL)
307 eap_pwd_state(data, FAILURE);
308 }
309
310
eap_pwd_build_confirm_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)311 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
312 struct eap_pwd_data *data, u8 id)
313 {
314 struct crypto_hash *hash = NULL;
315 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
316 u16 grp;
317 size_t prime_len, order_len;
318
319 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
320 /*
321 * if we're fragmenting then we already have an confirm request, just
322 * return
323 */
324 if (data->out_frag_pos)
325 return;
326
327 prime_len = crypto_ec_prime_len(data->grp->group);
328 order_len = crypto_ec_order_len(data->grp->group);
329
330 /* Each component of the cruft will be at most as big as the prime */
331 cruft = os_malloc(prime_len * 2);
332 if (!cruft) {
333 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
334 "fail");
335 goto fin;
336 }
337
338 /*
339 * commit is H(k | server_element | server_scalar | peer_element |
340 * peer_scalar | ciphersuite)
341 */
342 hash = eap_pwd_h_init();
343 if (hash == NULL)
344 goto fin;
345
346 /*
347 * Zero the memory each time because this is mod prime math and some
348 * value may start with a few zeros and the previous one did not.
349 *
350 * First is k
351 */
352 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
353 eap_pwd_h_update(hash, cruft, prime_len);
354
355 /* server element: x, y */
356 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
357 cruft + prime_len) < 0) {
358 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
359 "assignment fail");
360 goto fin;
361 }
362 eap_pwd_h_update(hash, cruft, prime_len * 2);
363
364 /* server scalar */
365 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
366 eap_pwd_h_update(hash, cruft, order_len);
367
368 /* peer element: x, y */
369 if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
370 cruft + prime_len) < 0) {
371 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
372 "assignment fail");
373 goto fin;
374 }
375 eap_pwd_h_update(hash, cruft, prime_len * 2);
376
377 /* peer scalar */
378 crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
379 eap_pwd_h_update(hash, cruft, order_len);
380
381 /* ciphersuite */
382 grp = htons(data->group_num);
383 os_memset(cruft, 0, prime_len);
384 ptr = cruft;
385 os_memcpy(ptr, &grp, sizeof(u16));
386 ptr += sizeof(u16);
387 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
388 ptr += sizeof(u8);
389 *ptr = EAP_PWD_DEFAULT_PRF;
390 ptr += sizeof(u8);
391 eap_pwd_h_update(hash, cruft, ptr - cruft);
392
393 /* all done with the random function */
394 eap_pwd_h_final(hash, conf);
395 hash = NULL;
396 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
397
398 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
399 if (data->outbuf == NULL)
400 goto fin;
401
402 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
403
404 fin:
405 bin_clear_free(cruft, prime_len * 2);
406 if (data->outbuf == NULL)
407 eap_pwd_state(data, FAILURE);
408 eap_pwd_h_final(hash, NULL);
409 }
410
411
412 static struct wpabuf *
eap_pwd_build_req(struct eap_sm * sm,void * priv,u8 id)413 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
414 {
415 struct eap_pwd_data *data = priv;
416 struct wpabuf *req;
417 u8 lm_exch;
418 const u8 *buf;
419 u16 totlen = 0;
420 size_t len;
421
422 /*
423 * if we're buffering response fragments then just ACK
424 */
425 if (data->in_frag_pos) {
426 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
427 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
428 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
429 if (req == NULL) {
430 eap_pwd_state(data, FAILURE);
431 return NULL;
432 }
433 switch (data->state) {
434 case PWD_ID_Req:
435 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
436 break;
437 case PWD_Commit_Req:
438 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
439 break;
440 case PWD_Confirm_Req:
441 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
442 break;
443 default:
444 eap_pwd_state(data, FAILURE); /* just to be sure */
445 wpabuf_free(req);
446 return NULL;
447 }
448 return req;
449 }
450
451 /*
452 * build the data portion of a request
453 */
454 switch (data->state) {
455 case PWD_ID_Req:
456 eap_pwd_build_id_req(sm, data, id);
457 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
458 break;
459 case PWD_Commit_Req:
460 eap_pwd_build_commit_req(sm, data, id);
461 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
462 break;
463 case PWD_Confirm_Req:
464 eap_pwd_build_confirm_req(sm, data, id);
465 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
466 break;
467 default:
468 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
469 data->state);
470 eap_pwd_state(data, FAILURE);
471 lm_exch = 0; /* hush now, sweet compiler */
472 break;
473 }
474
475 if (data->state == FAILURE)
476 return NULL;
477
478 /*
479 * determine whether that data needs to be fragmented
480 */
481 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
482 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
483 len = data->mtu - EAP_PWD_HDR_SIZE;
484 EAP_PWD_SET_MORE_BIT(lm_exch);
485 /*
486 * if this is the first fragment, need to set the M bit
487 * and add the total length to the eap_pwd_hdr
488 */
489 if (data->out_frag_pos == 0) {
490 EAP_PWD_SET_LENGTH_BIT(lm_exch);
491 totlen = wpabuf_len(data->outbuf) +
492 EAP_PWD_HDR_SIZE + sizeof(u16);
493 len -= sizeof(u16);
494 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
495 "total length = %d", totlen);
496 }
497 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
498 (int) len);
499 }
500
501 /*
502 * alloc an eap request and populate it with the data
503 */
504 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
505 EAP_PWD_HDR_SIZE + len +
506 (totlen ? sizeof(u16) : 0),
507 EAP_CODE_REQUEST, id);
508 if (req == NULL) {
509 eap_pwd_state(data, FAILURE);
510 return NULL;
511 }
512
513 wpabuf_put_u8(req, lm_exch);
514 if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
515 wpabuf_put_be16(req, totlen);
516
517 buf = wpabuf_head_u8(data->outbuf);
518 wpabuf_put_data(req, buf + data->out_frag_pos, len);
519 data->out_frag_pos += len;
520 /*
521 * either not fragged or last fragment, either way free up the data
522 */
523 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
524 wpabuf_free(data->outbuf);
525 data->outbuf = NULL;
526 data->out_frag_pos = 0;
527 }
528
529 return req;
530 }
531
532
eap_pwd_check(struct eap_sm * sm,void * priv,struct wpabuf * respData)533 static bool eap_pwd_check(struct eap_sm *sm, void *priv,
534 struct wpabuf *respData)
535 {
536 struct eap_pwd_data *data = priv;
537 const u8 *pos;
538 size_t len;
539
540 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
541 if (pos == NULL || len < 1) {
542 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
543 return true;
544 }
545
546 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
547 EAP_PWD_GET_EXCHANGE(*pos), (int) len);
548
549 if (data->state == PWD_ID_Req &&
550 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
551 return false;
552
553 if (data->state == PWD_Commit_Req &&
554 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
555 return false;
556
557 if (data->state == PWD_Confirm_Req &&
558 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
559 return false;
560
561 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
562 *pos, data->state);
563
564 return true;
565 }
566
567
eap_pwd_process_id_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)568 static void eap_pwd_process_id_resp(struct eap_sm *sm,
569 struct eap_pwd_data *data,
570 const u8 *payload, size_t payload_len)
571 {
572 struct eap_pwd_id *id;
573 const u8 *password;
574 size_t password_len;
575 u8 pwhashhash[16];
576 int res;
577
578 if (payload_len < sizeof(struct eap_pwd_id)) {
579 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
580 return;
581 }
582
583 id = (struct eap_pwd_id *) payload;
584 if ((data->group_num != be_to_host16(id->group_num)) ||
585 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
586 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
587 (id->prf != EAP_PWD_DEFAULT_PRF) ||
588 (id->prep != data->password_prep)) {
589 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
590 eap_pwd_state(data, FAILURE);
591 return;
592 }
593 if (data->id_peer || data->grp) {
594 wpa_printf(MSG_INFO, "EAP-pwd: data was already allocated");
595 return;
596 }
597 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
598 if (data->id_peer == NULL) {
599 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
600 return;
601 }
602 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
603 os_memcpy(data->id_peer, id->identity, data->id_peer_len);
604 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
605 data->id_peer, data->id_peer_len);
606
607 data->grp = get_eap_pwd_group(data->group_num);
608 if (data->grp == NULL) {
609 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
610 "group");
611 return;
612 }
613
614 /*
615 * If it's PREP_MS then hash the password again, otherwise regardless
616 * of the prep the client is doing, the password we have is the one to
617 * use to generate the password element.
618 */
619 if (data->password_prep == EAP_PWD_PREP_MS) {
620 res = hash_nt_password_hash(data->password, pwhashhash);
621 if (res)
622 return;
623 password = pwhashhash;
624 password_len = sizeof(pwhashhash);
625 } else {
626 password = data->password;
627 password_len = data->password_len;
628 }
629
630 res = compute_password_element(data->grp, data->group_num,
631 password, password_len,
632 data->id_server, data->id_server_len,
633 data->id_peer, data->id_peer_len,
634 (u8 *) &data->token);
635 forced_memzero(pwhashhash, sizeof(pwhashhash));
636 if (res) {
637 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
638 "PWE");
639 return;
640 }
641 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
642 (int) crypto_ec_prime_len_bits(data->grp->group));
643
644 eap_pwd_state(data, PWD_Commit_Req);
645 }
646
647
648 static void
eap_pwd_process_commit_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)649 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
650 const u8 *payload, size_t payload_len)
651 {
652 const u8 *ptr;
653 struct crypto_ec_point *K = NULL;
654 int res = 0;
655 size_t prime_len, order_len;
656
657 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
658
659 prime_len = crypto_ec_prime_len(data->grp->group);
660 order_len = crypto_ec_order_len(data->grp->group);
661
662 if (payload_len != 2 * prime_len + order_len) {
663 wpa_printf(MSG_INFO,
664 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
665 (unsigned int) payload_len,
666 (unsigned int) (2 * prime_len + order_len));
667 goto fin;
668 }
669
670 data->k = crypto_bignum_init();
671 K = crypto_ec_point_init(data->grp->group);
672 if (!data->k || !K) {
673 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
674 "fail");
675 goto fin;
676 }
677
678 /* element, x then y, followed by scalar */
679 ptr = payload;
680 data->peer_element = eap_pwd_get_element(data->grp, ptr);
681 if (!data->peer_element) {
682 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
683 "fail");
684 goto fin;
685 }
686 ptr += prime_len * 2;
687 data->peer_scalar = eap_pwd_get_scalar(data->grp, ptr);
688 if (!data->peer_scalar) {
689 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
690 "fail");
691 goto fin;
692 }
693
694 /* detect reflection attacks */
695 if (crypto_bignum_cmp(data->my_scalar, data->peer_scalar) == 0 ||
696 crypto_ec_point_cmp(data->grp->group, data->my_element,
697 data->peer_element) == 0) {
698 wpa_printf(MSG_INFO,
699 "EAP-PWD (server): detected reflection attack!");
700 goto fin;
701 }
702
703 /* compute the shared key, k */
704 if ((crypto_ec_point_mul(data->grp->group, data->grp->pwe,
705 data->peer_scalar, K) < 0) ||
706 (crypto_ec_point_add(data->grp->group, K, data->peer_element,
707 K) < 0) ||
708 (crypto_ec_point_mul(data->grp->group, K, data->private_value,
709 K) < 0)) {
710 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
711 "fail");
712 goto fin;
713 }
714
715 /*
716 * This check is strictly speaking just for the case where
717 * co-factor > 1 but it was suggested that even though this is probably
718 * never going to happen it is a simple and safe check "just to be
719 * sure" so let's be safe.
720 */
721 if (crypto_ec_point_is_at_infinity(data->grp->group, K)) {
722 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
723 "at infinity");
724 goto fin;
725 }
726 if (crypto_ec_point_x(data->grp->group, K, data->k)) {
727 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
728 "shared secret from secret point");
729 goto fin;
730 }
731 res = 1;
732
733 fin:
734 crypto_ec_point_deinit(K, 1);
735
736 if (res)
737 eap_pwd_state(data, PWD_Confirm_Req);
738 else
739 eap_pwd_state(data, FAILURE);
740 }
741
742
743 static void
eap_pwd_process_confirm_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)744 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
745 const u8 *payload, size_t payload_len)
746 {
747 struct crypto_hash *hash = NULL;
748 u32 cs;
749 u16 grp;
750 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
751 size_t prime_len, order_len;
752
753 prime_len = crypto_ec_prime_len(data->grp->group);
754 order_len = crypto_ec_order_len(data->grp->group);
755
756 if (payload_len != SHA256_MAC_LEN) {
757 wpa_printf(MSG_INFO,
758 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
759 (unsigned int) payload_len, SHA256_MAC_LEN);
760 goto fin;
761 }
762
763 /* build up the ciphersuite: group | random_function | prf */
764 grp = htons(data->group_num);
765 ptr = (u8 *) &cs;
766 os_memcpy(ptr, &grp, sizeof(u16));
767 ptr += sizeof(u16);
768 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
769 ptr += sizeof(u8);
770 *ptr = EAP_PWD_DEFAULT_PRF;
771
772 /* each component of the cruft will be at most as big as the prime */
773 cruft = os_malloc(prime_len * 2);
774 if (!cruft) {
775 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
776 goto fin;
777 }
778
779 /*
780 * commit is H(k | peer_element | peer_scalar | server_element |
781 * server_scalar | ciphersuite)
782 */
783 hash = eap_pwd_h_init();
784 if (hash == NULL)
785 goto fin;
786
787 /* k */
788 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
789 eap_pwd_h_update(hash, cruft, prime_len);
790
791 /* peer element: x, y */
792 if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
793 cruft + prime_len) < 0) {
794 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
795 "assignment fail");
796 goto fin;
797 }
798 eap_pwd_h_update(hash, cruft, prime_len * 2);
799
800 /* peer scalar */
801 crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
802 eap_pwd_h_update(hash, cruft, order_len);
803
804 /* server element: x, y */
805 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
806 cruft + prime_len) < 0) {
807 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
808 "assignment fail");
809 goto fin;
810 }
811 eap_pwd_h_update(hash, cruft, prime_len * 2);
812
813 /* server scalar */
814 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
815 eap_pwd_h_update(hash, cruft, order_len);
816
817 /* ciphersuite */
818 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
819
820 /* all done */
821 eap_pwd_h_final(hash, conf);
822 hash = NULL;
823
824 ptr = (u8 *) payload;
825 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
826 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
827 "verify");
828 goto fin;
829 }
830
831 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
832 if (compute_keys(data->grp, data->k,
833 data->peer_scalar, data->my_scalar, conf,
834 data->my_confirm, &cs, data->msk, data->emsk,
835 data->session_id) < 0)
836 eap_pwd_state(data, FAILURE);
837 else
838 eap_pwd_state(data, SUCCESS);
839
840 fin:
841 bin_clear_free(cruft, prime_len * 2);
842 eap_pwd_h_final(hash, NULL);
843 }
844
845
eap_pwd_process(struct eap_sm * sm,void * priv,struct wpabuf * respData)846 static void eap_pwd_process(struct eap_sm *sm, void *priv,
847 struct wpabuf *respData)
848 {
849 struct eap_pwd_data *data = priv;
850 const u8 *pos;
851 size_t len;
852 u8 lm_exch;
853 u16 tot_len;
854
855 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
856 if ((pos == NULL) || (len < 1)) {
857 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
858 (pos == NULL) ? "is NULL" : "is not NULL",
859 (int) len);
860 return;
861 }
862
863 lm_exch = *pos;
864 pos++; /* skip over the bits and the exch */
865 len--;
866
867 /*
868 * if we're fragmenting then this should be an ACK with no data,
869 * just return and continue fragmenting in the "build" section above
870 */
871 if (data->out_frag_pos) {
872 if (len > 1)
873 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
874 "Fragmenting but not an ACK");
875 else
876 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
877 "peer");
878 return;
879 }
880 /*
881 * if we're receiving fragmented packets then we need to buffer...
882 *
883 * the first fragment has a total length
884 */
885 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
886 if (len < 2) {
887 wpa_printf(MSG_DEBUG,
888 "EAP-pwd: Frame too short to contain Total-Length field");
889 return;
890 }
891 tot_len = WPA_GET_BE16(pos);
892 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
893 "length = %d", tot_len);
894 if (tot_len > 15000)
895 return;
896 if (data->inbuf) {
897 wpa_printf(MSG_DEBUG,
898 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
899 return;
900 }
901 data->inbuf = wpabuf_alloc(tot_len);
902 if (data->inbuf == NULL) {
903 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
904 "buffer fragments!");
905 return;
906 }
907 data->in_frag_pos = 0;
908 pos += sizeof(u16);
909 len -= sizeof(u16);
910 }
911 /*
912 * the first and all intermediate fragments have the M bit set
913 */
914 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
915 if (!data->inbuf) {
916 wpa_printf(MSG_DEBUG,
917 "EAP-pwd: No buffer for reassembly");
918 eap_pwd_state(data, FAILURE);
919 return;
920 }
921 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
922 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
923 "attack detected! (%d+%d > %d)",
924 (int) data->in_frag_pos, (int) len,
925 (int) wpabuf_size(data->inbuf));
926 eap_pwd_state(data, FAILURE);
927 return;
928 }
929 wpabuf_put_data(data->inbuf, pos, len);
930 data->in_frag_pos += len;
931 }
932 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
933 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
934 (int) len);
935 return;
936 }
937 /*
938 * last fragment won't have the M bit set (but we're obviously
939 * buffering fragments so that's how we know it's the last)
940 */
941 if (data->in_frag_pos && data->inbuf) {
942 pos = wpabuf_head_u8(data->inbuf);
943 len = data->in_frag_pos;
944 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
945 (int) len);
946 }
947 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
948 case EAP_PWD_OPCODE_ID_EXCH:
949 eap_pwd_process_id_resp(sm, data, pos, len);
950 break;
951 case EAP_PWD_OPCODE_COMMIT_EXCH:
952 eap_pwd_process_commit_resp(sm, data, pos, len);
953 break;
954 case EAP_PWD_OPCODE_CONFIRM_EXCH:
955 eap_pwd_process_confirm_resp(sm, data, pos, len);
956 break;
957 }
958 /*
959 * if we had been buffering fragments, here's a great place
960 * to clean up
961 */
962 if (data->in_frag_pos) {
963 wpabuf_free(data->inbuf);
964 data->inbuf = NULL;
965 data->in_frag_pos = 0;
966 }
967 }
968
969
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)970 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
971 {
972 struct eap_pwd_data *data = priv;
973 u8 *key;
974
975 if (data->state != SUCCESS)
976 return NULL;
977
978 key = os_memdup(data->msk, EAP_MSK_LEN);
979 if (key == NULL)
980 return NULL;
981
982 *len = EAP_MSK_LEN;
983
984 return key;
985 }
986
987
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)988 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
989 {
990 struct eap_pwd_data *data = priv;
991 u8 *key;
992
993 if (data->state != SUCCESS)
994 return NULL;
995
996 key = os_memdup(data->emsk, EAP_EMSK_LEN);
997 if (key == NULL)
998 return NULL;
999
1000 *len = EAP_EMSK_LEN;
1001
1002 return key;
1003 }
1004
1005
eap_pwd_is_success(struct eap_sm * sm,void * priv)1006 static bool eap_pwd_is_success(struct eap_sm *sm, void *priv)
1007 {
1008 struct eap_pwd_data *data = priv;
1009 return data->state == SUCCESS;
1010 }
1011
1012
eap_pwd_is_done(struct eap_sm * sm,void * priv)1013 static bool eap_pwd_is_done(struct eap_sm *sm, void *priv)
1014 {
1015 struct eap_pwd_data *data = priv;
1016 return (data->state == SUCCESS) || (data->state == FAILURE);
1017 }
1018
1019
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)1020 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1021 {
1022 struct eap_pwd_data *data = priv;
1023 u8 *id;
1024
1025 if (data->state != SUCCESS)
1026 return NULL;
1027
1028 id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN);
1029 if (id == NULL)
1030 return NULL;
1031
1032 *len = 1 + SHA256_MAC_LEN;
1033
1034 return id;
1035 }
1036
1037
eap_server_pwd_register(void)1038 int eap_server_pwd_register(void)
1039 {
1040 struct eap_method *eap;
1041
1042 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1043 EAP_VENDOR_IETF, EAP_TYPE_PWD,
1044 "PWD");
1045 if (eap == NULL)
1046 return -1;
1047
1048 eap->init = eap_pwd_init;
1049 eap->reset = eap_pwd_reset;
1050 eap->buildReq = eap_pwd_build_req;
1051 eap->check = eap_pwd_check;
1052 eap->process = eap_pwd_process;
1053 eap->isDone = eap_pwd_is_done;
1054 eap->getKey = eap_pwd_getkey;
1055 eap->get_emsk = eap_pwd_get_emsk;
1056 eap->isSuccess = eap_pwd_is_success;
1057 eap->getSessionId = eap_pwd_get_session_id;
1058
1059 return eap_server_method_register(eap);
1060 }
1061
