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[thirdparty/hostap.git] / src / eap_server / eap_server_pwd.c
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 "eap_server/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, SUCCESS, FAILURE
21 } state;
22 u8 *id_peer;
23 size_t id_peer_len;
24 u8 *id_server;
25 size_t id_server_len;
26 u8 *password;
27 size_t password_len;
28 int password_hash;
29 u32 token;
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 *peer_scalar;
42 BIGNUM *my_scalar;
43 EC_POINT *my_element;
44 EC_POINT *peer_element;
45
46 u8 my_confirm[SHA256_MAC_LEN];
47
48 u8 msk[EAP_MSK_LEN];
49 u8 emsk[EAP_EMSK_LEN];
50 u8 session_id[1 + SHA256_MAC_LEN];
51
52 BN_CTX *bnctx;
53 };
54
55
56 static const char * eap_pwd_state_txt(int state)
57 {
58 switch (state) {
59 case PWD_ID_Req:
60 return "PWD-ID-Req";
61 case PWD_Commit_Req:
62 return "PWD-Commit-Req";
63 case PWD_Confirm_Req:
64 return "PWD-Confirm-Req";
65 case SUCCESS:
66 return "SUCCESS";
67 case FAILURE:
68 return "FAILURE";
69 default:
70 return "PWD-Unk";
71 }
72 }
73
74
75 static void eap_pwd_state(struct eap_pwd_data *data, int state)
76 {
77 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
78 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
79 data->state = state;
80 }
81
82
83 static void * eap_pwd_init(struct eap_sm *sm)
84 {
85 struct eap_pwd_data *data;
86
87 if (sm->user == NULL || sm->user->password == NULL ||
88 sm->user->password_len == 0) {
89 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
90 "configured");
91 return NULL;
92 }
93
94 data = os_zalloc(sizeof(*data));
95 if (data == NULL)
96 return NULL;
97
98 data->group_num = sm->pwd_group;
99 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
100 data->group_num);
101 data->state = PWD_ID_Req;
102
103 data->id_server = (u8 *) os_strdup("server");
104 if (data->id_server)
105 data->id_server_len = os_strlen((char *) data->id_server);
106
107 data->password = os_malloc(sm->user->password_len);
108 if (data->password == NULL) {
109 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
110 "fail");
111 bin_clear_free(data->id_server, data->id_server_len);
112 os_free(data);
113 return NULL;
114 }
115 data->password_len = sm->user->password_len;
116 os_memcpy(data->password, sm->user->password, data->password_len);
117 data->password_hash = sm->user->password_hash;
118
119 data->bnctx = BN_CTX_new();
120 if (data->bnctx == NULL) {
121 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
122 bin_clear_free(data->password, data->password_len);
123 bin_clear_free(data->id_server, data->id_server_len);
124 os_free(data);
125 return NULL;
126 }
127
128 data->in_frag_pos = data->out_frag_pos = 0;
129 data->inbuf = data->outbuf = NULL;
130 /* use default MTU from RFC 5931 if not configured otherwise */
131 data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
132
133 return data;
134 }
135
136
137 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
138 {
139 struct eap_pwd_data *data = priv;
140
141 BN_clear_free(data->private_value);
142 BN_clear_free(data->peer_scalar);
143 BN_clear_free(data->my_scalar);
144 BN_clear_free(data->k);
145 BN_CTX_free(data->bnctx);
146 EC_POINT_clear_free(data->my_element);
147 EC_POINT_clear_free(data->peer_element);
148 bin_clear_free(data->id_peer, data->id_peer_len);
149 bin_clear_free(data->id_server, data->id_server_len);
150 bin_clear_free(data->password, data->password_len);
151 if (data->grp) {
152 EC_GROUP_free(data->grp->group);
153 EC_POINT_clear_free(data->grp->pwe);
154 BN_clear_free(data->grp->order);
155 BN_clear_free(data->grp->prime);
156 os_free(data->grp);
157 }
158 wpabuf_free(data->inbuf);
159 wpabuf_free(data->outbuf);
160 bin_clear_free(data, sizeof(*data));
161 }
162
163
164 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
165 u8 id)
166 {
167 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
168 /*
169 * if we're fragmenting then we already have an id request, just return
170 */
171 if (data->out_frag_pos)
172 return;
173
174 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
175 data->id_server_len);
176 if (data->outbuf == NULL) {
177 eap_pwd_state(data, FAILURE);
178 return;
179 }
180
181 if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) {
182 wpabuf_free(data->outbuf);
183 data->outbuf = NULL;
184 eap_pwd_state(data, FAILURE);
185 return;
186 }
187
188 wpabuf_put_be16(data->outbuf, data->group_num);
189 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
190 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
191 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
192 wpabuf_put_u8(data->outbuf, data->password_hash ? EAP_PWD_PREP_MS :
193 EAP_PWD_PREP_NONE);
194 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
195 }
196
197
198 static void eap_pwd_build_commit_req(struct eap_sm *sm,
199 struct eap_pwd_data *data, u8 id)
200 {
201 BIGNUM *mask = NULL, *x = NULL, *y = NULL;
202 u8 *scalar = NULL, *element = NULL;
203 u16 offset;
204
205 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
206 /*
207 * if we're fragmenting then we already have an commit request, just
208 * return
209 */
210 if (data->out_frag_pos)
211 return;
212
213 if (((data->private_value = BN_new()) == NULL) ||
214 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
215 ((data->my_scalar = BN_new()) == NULL) ||
216 ((mask = BN_new()) == NULL)) {
217 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
218 "fail");
219 goto fin;
220 }
221
222 if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
223 BN_rand_range(mask, data->grp->order) != 1 ||
224 BN_add(data->my_scalar, data->private_value, mask) != 1 ||
225 BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
226 data->bnctx) != 1) {
227 wpa_printf(MSG_INFO,
228 "EAP-pwd (server): unable to get randomness");
229 goto fin;
230 }
231
232 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
233 data->grp->pwe, mask, data->bnctx)) {
234 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
235 "fail");
236 eap_pwd_state(data, FAILURE);
237 goto fin;
238 }
239
240 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
241 {
242 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
243 "fail");
244 goto fin;
245 }
246 BN_clear_free(mask);
247
248 if (((x = BN_new()) == NULL) ||
249 ((y = BN_new()) == NULL)) {
250 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
251 "fail");
252 goto fin;
253 }
254 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
255 data->my_element, x, y,
256 data->bnctx)) {
257 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
258 "fail");
259 goto fin;
260 }
261
262 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
263 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
264 NULL)) {
265 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
266 goto fin;
267 }
268
269 /*
270 * bignums occupy as little memory as possible so one that is
271 * sufficiently smaller than the prime or order might need pre-pending
272 * with zeros.
273 */
274 os_memset(scalar, 0, BN_num_bytes(data->grp->order));
275 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
276 offset = BN_num_bytes(data->grp->order) -
277 BN_num_bytes(data->my_scalar);
278 BN_bn2bin(data->my_scalar, scalar + offset);
279
280 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
281 BN_bn2bin(x, element + offset);
282 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
283 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
284
285 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
286 BN_num_bytes(data->grp->order));
287 if (data->outbuf == NULL)
288 goto fin;
289
290 /* We send the element as (x,y) followed by the scalar */
291 wpabuf_put_data(data->outbuf, element,
292 2 * BN_num_bytes(data->grp->prime));
293 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
294
295 fin:
296 os_free(scalar);
297 os_free(element);
298 BN_clear_free(x);
299 BN_clear_free(y);
300 if (data->outbuf == NULL)
301 eap_pwd_state(data, FAILURE);
302 }
303
304
305 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
306 struct eap_pwd_data *data, u8 id)
307 {
308 BIGNUM *x = NULL, *y = NULL;
309 struct crypto_hash *hash;
310 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
311 u16 grp;
312 int offset;
313
314 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
315 /*
316 * if we're fragmenting then we already have an confirm request, just
317 * return
318 */
319 if (data->out_frag_pos)
320 return;
321
322 /* Each component of the cruft will be at most as big as the prime */
323 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
324 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
325 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
326 "fail");
327 goto fin;
328 }
329
330 /*
331 * commit is H(k | server_element | server_scalar | peer_element |
332 * peer_scalar | ciphersuite)
333 */
334 hash = eap_pwd_h_init();
335 if (hash == NULL)
336 goto fin;
337
338 /*
339 * Zero the memory each time because this is mod prime math and some
340 * value may start with a few zeros and the previous one did not.
341 *
342 * First is k
343 */
344 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
345 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
346 BN_bn2bin(data->k, cruft + offset);
347 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
348
349 /* server element: x, y */
350 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
351 data->my_element, x, y,
352 data->bnctx)) {
353 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
354 "assignment fail");
355 goto fin;
356 }
357
358 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
359 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
360 BN_bn2bin(x, cruft + offset);
361 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
362 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
363 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
364 BN_bn2bin(y, cruft + offset);
365 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
366
367 /* server scalar */
368 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
369 offset = BN_num_bytes(data->grp->order) -
370 BN_num_bytes(data->my_scalar);
371 BN_bn2bin(data->my_scalar, cruft + offset);
372 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
373
374 /* peer element: x, y */
375 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
376 data->peer_element, x, y,
377 data->bnctx)) {
378 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
379 "assignment fail");
380 goto fin;
381 }
382
383 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
384 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
385 BN_bn2bin(x, cruft + offset);
386 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
387 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
388 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
389 BN_bn2bin(y, cruft + offset);
390 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
391
392 /* peer scalar */
393 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
394 offset = BN_num_bytes(data->grp->order) -
395 BN_num_bytes(data->peer_scalar);
396 BN_bn2bin(data->peer_scalar, cruft + offset);
397 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
398
399 /* ciphersuite */
400 grp = htons(data->group_num);
401 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
402 ptr = cruft;
403 os_memcpy(ptr, &grp, sizeof(u16));
404 ptr += sizeof(u16);
405 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
406 ptr += sizeof(u8);
407 *ptr = EAP_PWD_DEFAULT_PRF;
408 ptr += sizeof(u8);
409 eap_pwd_h_update(hash, cruft, ptr - cruft);
410
411 /* all done with the random function */
412 eap_pwd_h_final(hash, conf);
413 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
414
415 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
416 if (data->outbuf == NULL)
417 goto fin;
418
419 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
420
421 fin:
422 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
423 BN_clear_free(x);
424 BN_clear_free(y);
425 if (data->outbuf == NULL)
426 eap_pwd_state(data, FAILURE);
427 }
428
429
430 static struct wpabuf *
431 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
432 {
433 struct eap_pwd_data *data = priv;
434 struct wpabuf *req;
435 u8 lm_exch;
436 const u8 *buf;
437 u16 totlen = 0;
438 size_t len;
439
440 /*
441 * if we're buffering response fragments then just ACK
442 */
443 if (data->in_frag_pos) {
444 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
445 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
446 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
447 if (req == NULL) {
448 eap_pwd_state(data, FAILURE);
449 return NULL;
450 }
451 switch (data->state) {
452 case PWD_ID_Req:
453 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
454 break;
455 case PWD_Commit_Req:
456 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
457 break;
458 case PWD_Confirm_Req:
459 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
460 break;
461 default:
462 eap_pwd_state(data, FAILURE); /* just to be sure */
463 wpabuf_free(req);
464 return NULL;
465 }
466 return req;
467 }
468
469 /*
470 * build the data portion of a request
471 */
472 switch (data->state) {
473 case PWD_ID_Req:
474 eap_pwd_build_id_req(sm, data, id);
475 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
476 break;
477 case PWD_Commit_Req:
478 eap_pwd_build_commit_req(sm, data, id);
479 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
480 break;
481 case PWD_Confirm_Req:
482 eap_pwd_build_confirm_req(sm, data, id);
483 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
484 break;
485 default:
486 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
487 data->state);
488 eap_pwd_state(data, FAILURE);
489 lm_exch = 0; /* hush now, sweet compiler */
490 break;
491 }
492
493 if (data->state == FAILURE)
494 return NULL;
495
496 /*
497 * determine whether that data needs to be fragmented
498 */
499 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
500 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
501 len = data->mtu - EAP_PWD_HDR_SIZE;
502 EAP_PWD_SET_MORE_BIT(lm_exch);
503 /*
504 * if this is the first fragment, need to set the M bit
505 * and add the total length to the eap_pwd_hdr
506 */
507 if (data->out_frag_pos == 0) {
508 EAP_PWD_SET_LENGTH_BIT(lm_exch);
509 totlen = wpabuf_len(data->outbuf) +
510 EAP_PWD_HDR_SIZE + sizeof(u16);
511 len -= sizeof(u16);
512 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
513 "total length = %d", totlen);
514 }
515 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
516 (int) len);
517 }
518
519 /*
520 * alloc an eap request and populate it with the data
521 */
522 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
523 EAP_PWD_HDR_SIZE + len +
524 (totlen ? sizeof(u16) : 0),
525 EAP_CODE_REQUEST, id);
526 if (req == NULL) {
527 eap_pwd_state(data, FAILURE);
528 return NULL;
529 }
530
531 wpabuf_put_u8(req, lm_exch);
532 if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
533 wpabuf_put_be16(req, totlen);
534
535 buf = wpabuf_head_u8(data->outbuf);
536 wpabuf_put_data(req, buf + data->out_frag_pos, len);
537 data->out_frag_pos += len;
538 /*
539 * either not fragged or last fragment, either way free up the data
540 */
541 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
542 wpabuf_free(data->outbuf);
543 data->outbuf = NULL;
544 data->out_frag_pos = 0;
545 }
546
547 return req;
548 }
549
550
551 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
552 struct wpabuf *respData)
553 {
554 struct eap_pwd_data *data = priv;
555 const u8 *pos;
556 size_t len;
557
558 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
559 if (pos == NULL || len < 1) {
560 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
561 return TRUE;
562 }
563
564 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
565 EAP_PWD_GET_EXCHANGE(*pos), (int) len);
566
567 if (data->state == PWD_ID_Req &&
568 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
569 return FALSE;
570
571 if (data->state == PWD_Commit_Req &&
572 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
573 return FALSE;
574
575 if (data->state == PWD_Confirm_Req &&
576 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
577 return FALSE;
578
579 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
580 *pos, data->state);
581
582 return TRUE;
583 }
584
585
586 static void eap_pwd_process_id_resp(struct eap_sm *sm,
587 struct eap_pwd_data *data,
588 const u8 *payload, size_t payload_len)
589 {
590 struct eap_pwd_id *id;
591 const u8 *password;
592 size_t password_len;
593 u8 pwhashhash[16];
594 int res;
595
596 if (payload_len < sizeof(struct eap_pwd_id)) {
597 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
598 return;
599 }
600
601 id = (struct eap_pwd_id *) payload;
602 if ((data->group_num != be_to_host16(id->group_num)) ||
603 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
604 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
605 (id->prf != EAP_PWD_DEFAULT_PRF) ||
606 id->prep !=
607 data->password_hash ? EAP_PWD_PREP_MS : EAP_PWD_PREP_NONE) {
608 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
609 eap_pwd_state(data, FAILURE);
610 return;
611 }
612 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
613 if (data->id_peer == NULL) {
614 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
615 return;
616 }
617 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
618 os_memcpy(data->id_peer, id->identity, data->id_peer_len);
619 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
620 data->id_peer, data->id_peer_len);
621
622 data->grp = os_zalloc(sizeof(EAP_PWD_group));
623 if (data->grp == NULL) {
624 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
625 "group");
626 return;
627 }
628
629 if (data->password_hash) {
630 res = hash_nt_password_hash(data->password, pwhashhash);
631 if (res)
632 return;
633 password = pwhashhash;
634 password_len = sizeof(pwhashhash);
635 } else {
636 password = data->password;
637 password_len = data->password_len;
638 }
639
640 res = compute_password_element(data->grp, data->group_num,
641 password, password_len,
642 data->id_server, data->id_server_len,
643 data->id_peer, data->id_peer_len,
644 (u8 *) &data->token);
645 os_memset(pwhashhash, 0, sizeof(pwhashhash));
646 if (res) {
647 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
648 "PWE");
649 return;
650 }
651 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
652 BN_num_bits(data->grp->prime));
653
654 eap_pwd_state(data, PWD_Commit_Req);
655 }
656
657
658 static void
659 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
660 const u8 *payload, size_t payload_len)
661 {
662 u8 *ptr;
663 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
664 EC_POINT *K = NULL, *point = NULL;
665 int res = 0;
666 size_t prime_len, order_len;
667
668 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
669
670 prime_len = BN_num_bytes(data->grp->prime);
671 order_len = BN_num_bytes(data->grp->order);
672
673 if (payload_len != 2 * prime_len + order_len) {
674 wpa_printf(MSG_INFO,
675 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
676 (unsigned int) payload_len,
677 (unsigned int) (2 * prime_len + order_len));
678 goto fin;
679 }
680
681 if (((data->peer_scalar = BN_new()) == NULL) ||
682 ((data->k = BN_new()) == NULL) ||
683 ((cofactor = BN_new()) == NULL) ||
684 ((x = BN_new()) == NULL) ||
685 ((y = BN_new()) == NULL) ||
686 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
687 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
688 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
689 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
690 "fail");
691 goto fin;
692 }
693
694 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
695 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
696 "cofactor for curve");
697 goto fin;
698 }
699
700 /* element, x then y, followed by scalar */
701 ptr = (u8 *) payload;
702 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
703 ptr += BN_num_bytes(data->grp->prime);
704 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
705 ptr += BN_num_bytes(data->grp->prime);
706 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
707 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
708 data->peer_element, x, y,
709 data->bnctx)) {
710 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
711 "fail");
712 goto fin;
713 }
714
715 /* check to ensure peer's element is not in a small sub-group */
716 if (BN_cmp(cofactor, BN_value_one())) {
717 if (!EC_POINT_mul(data->grp->group, point, NULL,
718 data->peer_element, cofactor, NULL)) {
719 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
720 "multiply peer element by order");
721 goto fin;
722 }
723 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
724 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
725 "is at infinity!\n");
726 goto fin;
727 }
728 }
729
730 /* compute the shared key, k */
731 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
732 data->peer_scalar, data->bnctx)) ||
733 (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
734 data->bnctx)) ||
735 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
736 data->bnctx))) {
737 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
738 "fail");
739 goto fin;
740 }
741
742 /* ensure that the shared key isn't in a small sub-group */
743 if (BN_cmp(cofactor, BN_value_one())) {
744 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
745 NULL)) {
746 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
747 "multiply shared key point by order!\n");
748 goto fin;
749 }
750 }
751
752 /*
753 * This check is strictly speaking just for the case above where
754 * co-factor > 1 but it was suggested that even though this is probably
755 * never going to happen it is a simple and safe check "just to be
756 * sure" so let's be safe.
757 */
758 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
759 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
760 "at infinity");
761 goto fin;
762 }
763 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
764 NULL, data->bnctx)) {
765 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
766 "shared secret from secret point");
767 goto fin;
768 }
769 res = 1;
770
771 fin:
772 EC_POINT_clear_free(K);
773 EC_POINT_clear_free(point);
774 BN_clear_free(cofactor);
775 BN_clear_free(x);
776 BN_clear_free(y);
777
778 if (res)
779 eap_pwd_state(data, PWD_Confirm_Req);
780 else
781 eap_pwd_state(data, FAILURE);
782 }
783
784
785 static void
786 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
787 const u8 *payload, size_t payload_len)
788 {
789 BIGNUM *x = NULL, *y = NULL;
790 struct crypto_hash *hash;
791 u32 cs;
792 u16 grp;
793 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
794 int offset;
795
796 if (payload_len != SHA256_MAC_LEN) {
797 wpa_printf(MSG_INFO,
798 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
799 (unsigned int) payload_len, SHA256_MAC_LEN);
800 goto fin;
801 }
802
803 /* build up the ciphersuite: group | random_function | prf */
804 grp = htons(data->group_num);
805 ptr = (u8 *) &cs;
806 os_memcpy(ptr, &grp, sizeof(u16));
807 ptr += sizeof(u16);
808 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
809 ptr += sizeof(u8);
810 *ptr = EAP_PWD_DEFAULT_PRF;
811
812 /* each component of the cruft will be at most as big as the prime */
813 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
814 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
815 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
816 goto fin;
817 }
818
819 /*
820 * commit is H(k | peer_element | peer_scalar | server_element |
821 * server_scalar | ciphersuite)
822 */
823 hash = eap_pwd_h_init();
824 if (hash == NULL)
825 goto fin;
826
827 /* k */
828 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
829 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
830 BN_bn2bin(data->k, cruft + offset);
831 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
832
833 /* peer element: x, y */
834 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
835 data->peer_element, x, y,
836 data->bnctx)) {
837 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
838 "assignment fail");
839 goto fin;
840 }
841 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
842 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
843 BN_bn2bin(x, cruft + offset);
844 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
845 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
846 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
847 BN_bn2bin(y, cruft + offset);
848 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
849
850 /* peer scalar */
851 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
852 offset = BN_num_bytes(data->grp->order) -
853 BN_num_bytes(data->peer_scalar);
854 BN_bn2bin(data->peer_scalar, cruft + offset);
855 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
856
857 /* server element: x, y */
858 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
859 data->my_element, x, y,
860 data->bnctx)) {
861 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
862 "assignment fail");
863 goto fin;
864 }
865
866 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
867 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
868 BN_bn2bin(x, cruft + offset);
869 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
870 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
871 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
872 BN_bn2bin(y, cruft + offset);
873 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
874
875 /* server scalar */
876 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
877 offset = BN_num_bytes(data->grp->order) -
878 BN_num_bytes(data->my_scalar);
879 BN_bn2bin(data->my_scalar, cruft + offset);
880 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
881
882 /* ciphersuite */
883 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
884 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
885
886 /* all done */
887 eap_pwd_h_final(hash, conf);
888
889 ptr = (u8 *) payload;
890 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
891 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
892 "verify");
893 goto fin;
894 }
895
896 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
897 if (compute_keys(data->grp, data->bnctx, data->k,
898 data->peer_scalar, data->my_scalar, conf,
899 data->my_confirm, &cs, data->msk, data->emsk,
900 data->session_id) < 0)
901 eap_pwd_state(data, FAILURE);
902 else
903 eap_pwd_state(data, SUCCESS);
904
905 fin:
906 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
907 BN_clear_free(x);
908 BN_clear_free(y);
909 }
910
911
912 static void eap_pwd_process(struct eap_sm *sm, void *priv,
913 struct wpabuf *respData)
914 {
915 struct eap_pwd_data *data = priv;
916 const u8 *pos;
917 size_t len;
918 u8 lm_exch;
919 u16 tot_len;
920
921 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
922 if ((pos == NULL) || (len < 1)) {
923 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
924 (pos == NULL) ? "is NULL" : "is not NULL",
925 (int) len);
926 return;
927 }
928
929 lm_exch = *pos;
930 pos++; /* skip over the bits and the exch */
931 len--;
932
933 /*
934 * if we're fragmenting then this should be an ACK with no data,
935 * just return and continue fragmenting in the "build" section above
936 */
937 if (data->out_frag_pos) {
938 if (len > 1)
939 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
940 "Fragmenting but not an ACK");
941 else
942 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
943 "peer");
944 return;
945 }
946 /*
947 * if we're receiving fragmented packets then we need to buffer...
948 *
949 * the first fragment has a total length
950 */
951 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
952 if (len < 2) {
953 wpa_printf(MSG_DEBUG,
954 "EAP-pwd: Frame too short to contain Total-Length field");
955 return;
956 }
957 tot_len = WPA_GET_BE16(pos);
958 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
959 "length = %d", tot_len);
960 if (tot_len > 15000)
961 return;
962 if (data->inbuf) {
963 wpa_printf(MSG_DEBUG,
964 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
965 return;
966 }
967 data->inbuf = wpabuf_alloc(tot_len);
968 if (data->inbuf == NULL) {
969 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
970 "buffer fragments!");
971 return;
972 }
973 data->in_frag_pos = 0;
974 pos += sizeof(u16);
975 len -= sizeof(u16);
976 }
977 /*
978 * the first and all intermediate fragments have the M bit set
979 */
980 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
981 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
982 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
983 "attack detected! (%d+%d > %d)",
984 (int) data->in_frag_pos, (int) len,
985 (int) wpabuf_size(data->inbuf));
986 eap_pwd_state(data, FAILURE);
987 return;
988 }
989 wpabuf_put_data(data->inbuf, pos, len);
990 data->in_frag_pos += len;
991 }
992 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
993 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
994 (int) len);
995 return;
996 }
997 /*
998 * last fragment won't have the M bit set (but we're obviously
999 * buffering fragments so that's how we know it's the last)
1000 */
1001 if (data->in_frag_pos) {
1002 pos = wpabuf_head_u8(data->inbuf);
1003 len = data->in_frag_pos;
1004 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
1005 (int) len);
1006 }
1007 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
1008 case EAP_PWD_OPCODE_ID_EXCH:
1009 eap_pwd_process_id_resp(sm, data, pos, len);
1010 break;
1011 case EAP_PWD_OPCODE_COMMIT_EXCH:
1012 eap_pwd_process_commit_resp(sm, data, pos, len);
1013 break;
1014 case EAP_PWD_OPCODE_CONFIRM_EXCH:
1015 eap_pwd_process_confirm_resp(sm, data, pos, len);
1016 break;
1017 }
1018 /*
1019 * if we had been buffering fragments, here's a great place
1020 * to clean up
1021 */
1022 if (data->in_frag_pos) {
1023 wpabuf_free(data->inbuf);
1024 data->inbuf = NULL;
1025 data->in_frag_pos = 0;
1026 }
1027 }
1028
1029
1030 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
1031 {
1032 struct eap_pwd_data *data = priv;
1033 u8 *key;
1034
1035 if (data->state != SUCCESS)
1036 return NULL;
1037
1038 key = os_memdup(data->msk, EAP_MSK_LEN);
1039 if (key == NULL)
1040 return NULL;
1041
1042 *len = EAP_MSK_LEN;
1043
1044 return key;
1045 }
1046
1047
1048 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1049 {
1050 struct eap_pwd_data *data = priv;
1051 u8 *key;
1052
1053 if (data->state != SUCCESS)
1054 return NULL;
1055
1056 key = os_memdup(data->emsk, EAP_EMSK_LEN);
1057 if (key == NULL)
1058 return NULL;
1059
1060 *len = EAP_EMSK_LEN;
1061
1062 return key;
1063 }
1064
1065
1066 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1067 {
1068 struct eap_pwd_data *data = priv;
1069 return data->state == SUCCESS;
1070 }
1071
1072
1073 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1074 {
1075 struct eap_pwd_data *data = priv;
1076 return (data->state == SUCCESS) || (data->state == FAILURE);
1077 }
1078
1079
1080 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1081 {
1082 struct eap_pwd_data *data = priv;
1083 u8 *id;
1084
1085 if (data->state != SUCCESS)
1086 return NULL;
1087
1088 id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN);
1089 if (id == NULL)
1090 return NULL;
1091
1092 *len = 1 + SHA256_MAC_LEN;
1093
1094 return id;
1095 }
1096
1097
1098 int eap_server_pwd_register(void)
1099 {
1100 struct eap_method *eap;
1101 struct timeval tp;
1102 struct timezone tz;
1103 u32 sr;
1104
1105 sr = 0xdeaddada;
1106 (void) gettimeofday(&tp, &tz);
1107 sr ^= (tp.tv_sec ^ tp.tv_usec);
1108 srandom(sr);
1109
1110 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1111 EAP_VENDOR_IETF, EAP_TYPE_PWD,
1112 "PWD");
1113 if (eap == NULL)
1114 return -1;
1115
1116 eap->init = eap_pwd_init;
1117 eap->reset = eap_pwd_reset;
1118 eap->buildReq = eap_pwd_build_req;
1119 eap->check = eap_pwd_check;
1120 eap->process = eap_pwd_process;
1121 eap->isDone = eap_pwd_is_done;
1122 eap->getKey = eap_pwd_getkey;
1123 eap->get_emsk = eap_pwd_get_emsk;
1124 eap->isSuccess = eap_pwd_is_success;
1125 eap->getSessionId = eap_pwd_get_session_id;
1126
1127 return eap_server_method_register(eap);
1128 }
1129
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