Disconnect hostapd from building in base
[dragonfly.git] / contrib / hostapd / src / eap_server / eap_server_pwd.c
CommitLineData
4781064b
JM
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 "eap_server/eap_i.h"
14#include "eap_common/eap_pwd_common.h"
15
16
17struct eap_pwd_data {
18 enum {
19 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
20 } state;
21 u8 *id_peer;
22 size_t id_peer_len;
23 u8 *id_server;
24 size_t id_server_len;
25 u8 *password;
26 size_t password_len;
27 u32 token;
28 u16 group_num;
29 EAP_PWD_group *grp;
30
31 struct wpabuf *inbuf;
32 size_t in_frag_pos;
33 struct wpabuf *outbuf;
34 size_t out_frag_pos;
35 size_t mtu;
36
37 BIGNUM *k;
38 BIGNUM *private_value;
39 BIGNUM *peer_scalar;
40 BIGNUM *my_scalar;
41 EC_POINT *my_element;
42 EC_POINT *peer_element;
43
44 u8 my_confirm[SHA256_MAC_LEN];
45
46 u8 msk[EAP_MSK_LEN];
47 u8 emsk[EAP_EMSK_LEN];
48
49 BN_CTX *bnctx;
50};
51
52
53static const char * eap_pwd_state_txt(int state)
54{
55 switch (state) {
56 case PWD_ID_Req:
57 return "PWD-ID-Req";
58 case PWD_Commit_Req:
59 return "PWD-Commit-Req";
60 case PWD_Confirm_Req:
61 return "PWD-Confirm-Req";
62 case SUCCESS:
63 return "SUCCESS";
64 case FAILURE:
65 return "FAILURE";
66 default:
67 return "PWD-Unk";
68 }
69}
70
71
72static void eap_pwd_state(struct eap_pwd_data *data, int state)
73{
74 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
75 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
76 data->state = state;
77}
78
79
80static void * eap_pwd_init(struct eap_sm *sm)
81{
82 struct eap_pwd_data *data;
83
84 if (sm->user == NULL || sm->user->password == NULL ||
85 sm->user->password_len == 0) {
86 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
87 "configured");
88 return NULL;
89 }
90
91 data = os_zalloc(sizeof(*data));
92 if (data == NULL)
93 return NULL;
94
95 data->group_num = sm->pwd_group;
96 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
97 data->group_num);
98 data->state = PWD_ID_Req;
99
100 data->id_server = (u8 *) os_strdup("server");
101 if (data->id_server)
102 data->id_server_len = os_strlen((char *) data->id_server);
103
104 data->password = os_malloc(sm->user->password_len);
105 if (data->password == NULL) {
106 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
107 "fail");
108 os_free(data->id_server);
109 os_free(data);
110 return NULL;
111 }
112 data->password_len = sm->user->password_len;
113 os_memcpy(data->password, sm->user->password, data->password_len);
114
115 data->bnctx = BN_CTX_new();
116 if (data->bnctx == NULL) {
117 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
118 os_free(data->password);
119 os_free(data->id_server);
120 os_free(data);
121 return NULL;
122 }
123
124 data->in_frag_pos = data->out_frag_pos = 0;
125 data->inbuf = data->outbuf = NULL;
126 data->mtu = 1020; /* default from RFC 5931, make it configurable! */
127
128 return data;
129}
130
131
132static void eap_pwd_reset(struct eap_sm *sm, void *priv)
133{
134 struct eap_pwd_data *data = priv;
135
136 BN_free(data->private_value);
137 BN_free(data->peer_scalar);
138 BN_free(data->my_scalar);
139 BN_free(data->k);
140 BN_CTX_free(data->bnctx);
141 EC_POINT_free(data->my_element);
142 EC_POINT_free(data->peer_element);
143 os_free(data->id_peer);
144 os_free(data->id_server);
145 os_free(data->password);
146 if (data->grp) {
147 EC_GROUP_free(data->grp->group);
148 EC_POINT_free(data->grp->pwe);
149 BN_free(data->grp->order);
150 BN_free(data->grp->prime);
151 os_free(data->grp);
152 }
153 os_free(data);
154}
155
156
157static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
158 u8 id)
159{
160 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
161 /*
162 * if we're fragmenting then we already have an id request, just return
163 */
164 if (data->out_frag_pos)
165 return;
166
167 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
168 data->id_server_len);
169 if (data->outbuf == NULL) {
170 eap_pwd_state(data, FAILURE);
171 return;
172 }
173
174 /* an lfsr is good enough to generate unpredictable tokens */
175 data->token = os_random();
176 wpabuf_put_be16(data->outbuf, data->group_num);
177 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
178 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
179 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
180 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
181 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
182}
183
184
185static void eap_pwd_build_commit_req(struct eap_sm *sm,
186 struct eap_pwd_data *data, u8 id)
187{
188 BIGNUM *mask = NULL, *x = NULL, *y = NULL;
189 u8 *scalar = NULL, *element = NULL;
190 u16 offset;
191
192 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
193 /*
194 * if we're fragmenting then we already have an commit request, just
195 * return
196 */
197 if (data->out_frag_pos)
198 return;
199
200 if (((data->private_value = BN_new()) == NULL) ||
201 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
202 ((data->my_scalar = BN_new()) == NULL) ||
203 ((mask = BN_new()) == NULL)) {
204 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
205 "fail");
206 goto fin;
207 }
208
209 BN_rand_range(data->private_value, data->grp->order);
210 BN_rand_range(mask, data->grp->order);
211 BN_add(data->my_scalar, data->private_value, mask);
212 BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
213 data->bnctx);
214
215 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
216 data->grp->pwe, mask, data->bnctx)) {
217 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
218 "fail");
219 eap_pwd_state(data, FAILURE);
220 goto fin;
221 }
222
223 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
224 {
225 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
226 "fail");
227 goto fin;
228 }
229 BN_free(mask);
230
231 if (((x = BN_new()) == NULL) ||
232 ((y = BN_new()) == NULL)) {
233 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
234 "fail");
235 goto fin;
236 }
237 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
238 data->my_element, x, y,
239 data->bnctx)) {
240 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
241 "fail");
242 goto fin;
243 }
244
245 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
246 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
247 NULL)) {
248 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
249 goto fin;
250 }
251
252 /*
253 * bignums occupy as little memory as possible so one that is
254 * sufficiently smaller than the prime or order might need pre-pending
255 * with zeros.
256 */
257 os_memset(scalar, 0, BN_num_bytes(data->grp->order));
258 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
259 offset = BN_num_bytes(data->grp->order) -
260 BN_num_bytes(data->my_scalar);
261 BN_bn2bin(data->my_scalar, scalar + offset);
262
263 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
264 BN_bn2bin(x, element + offset);
265 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
266 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
267
268 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
269 BN_num_bytes(data->grp->order));
270 if (data->outbuf == NULL)
271 goto fin;
272
273 /* We send the element as (x,y) followed by the scalar */
274 wpabuf_put_data(data->outbuf, element,
275 2 * BN_num_bytes(data->grp->prime));
276 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
277
278fin:
279 os_free(scalar);
280 os_free(element);
281 BN_free(x);
282 BN_free(y);
283 if (data->outbuf == NULL)
284 eap_pwd_state(data, FAILURE);
285}
286
287
288static void eap_pwd_build_confirm_req(struct eap_sm *sm,
289 struct eap_pwd_data *data, u8 id)
290{
291 BIGNUM *x = NULL, *y = NULL;
292 struct crypto_hash *hash;
293 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
294 u16 grp;
295 int offset;
296
297 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
298 /*
299 * if we're fragmenting then we already have an confirm request, just
300 * return
301 */
302 if (data->out_frag_pos)
303 return;
304
305 /* Each component of the cruft will be at most as big as the prime */
306 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
307 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
308 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
309 "fail");
310 goto fin;
311 }
312
313 /*
314 * commit is H(k | server_element | server_scalar | peer_element |
315 * peer_scalar | ciphersuite)
316 */
317 hash = eap_pwd_h_init();
318 if (hash == NULL)
319 goto fin;
320
321 /*
322 * Zero the memory each time because this is mod prime math and some
323 * value may start with a few zeros and the previous one did not.
324 *
325 * First is k
326 */
327 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
328 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
329 BN_bn2bin(data->k, cruft + offset);
330 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
331
332 /* server element: x, y */
333 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
334 data->my_element, x, y,
335 data->bnctx)) {
336 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
337 "assignment fail");
338 goto fin;
339 }
340
341 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
342 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
343 BN_bn2bin(x, cruft + offset);
344 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
345 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
346 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
347 BN_bn2bin(y, cruft + offset);
348 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
349
350 /* server scalar */
351 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
352 offset = BN_num_bytes(data->grp->order) -
353 BN_num_bytes(data->my_scalar);
354 BN_bn2bin(data->my_scalar, cruft + offset);
355 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
356
357 /* peer element: x, y */
358 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
359 data->peer_element, x, y,
360 data->bnctx)) {
361 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
362 "assignment fail");
363 goto fin;
364 }
365
366 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
367 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
368 BN_bn2bin(x, cruft + offset);
369 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
370 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
371 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
372 BN_bn2bin(y, cruft + offset);
373 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
374
375 /* peer scalar */
376 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
377 offset = BN_num_bytes(data->grp->order) -
378 BN_num_bytes(data->peer_scalar);
379 BN_bn2bin(data->peer_scalar, cruft + offset);
380 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
381
382 /* ciphersuite */
383 grp = htons(data->group_num);
384 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
385 ptr = cruft;
386 os_memcpy(ptr, &grp, sizeof(u16));
387 ptr += sizeof(u16);
388 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
389 ptr += sizeof(u8);
390 *ptr = EAP_PWD_DEFAULT_PRF;
391 ptr += sizeof(u8);
392 eap_pwd_h_update(hash, cruft, ptr - cruft);
393
394 /* all done with the random function */
395 eap_pwd_h_final(hash, conf);
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
404fin:
405 os_free(cruft);
406 BN_free(x);
407 BN_free(y);
408 if (data->outbuf == NULL)
409 eap_pwd_state(data, FAILURE);
410}
411
412
413static struct wpabuf *
414eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
415{
416 struct eap_pwd_data *data = priv;
417 struct wpabuf *req;
418 u8 lm_exch;
419 const u8 *buf;
420 u16 totlen = 0;
421 size_t len;
422
423 /*
424 * if we're buffering response fragments then just ACK
425 */
426 if (data->in_frag_pos) {
427 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
428 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
429 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
430 if (req == NULL) {
431 eap_pwd_state(data, FAILURE);
432 return NULL;
433 }
434 switch (data->state) {
435 case PWD_ID_Req:
436 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
437 break;
438 case PWD_Commit_Req:
439 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
440 break;
441 case PWD_Confirm_Req:
442 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
443 break;
444 default:
445 eap_pwd_state(data, FAILURE); /* just to be sure */
446 wpabuf_free(req);
447 return NULL;
448 }
449 return req;
450 }
451
452 /*
453 * build the data portion of a request
454 */
455 switch (data->state) {
456 case PWD_ID_Req:
457 eap_pwd_build_id_req(sm, data, id);
458 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
459 break;
460 case PWD_Commit_Req:
461 eap_pwd_build_commit_req(sm, data, id);
462 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
463 break;
464 case PWD_Confirm_Req:
465 eap_pwd_build_confirm_req(sm, data, id);
466 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
467 break;
468 default:
469 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
470 data->state);
471 eap_pwd_state(data, FAILURE);
472 lm_exch = 0; /* hush now, sweet compiler */
473 break;
474 }
475
476 if (data->state == FAILURE)
477 return NULL;
478
479 /*
480 * determine whether that data needs to be fragmented
481 */
482 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
483 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
484 len = data->mtu - EAP_PWD_HDR_SIZE;
485 EAP_PWD_SET_MORE_BIT(lm_exch);
486 /*
487 * if this is the first fragment, need to set the M bit
488 * and add the total length to the eap_pwd_hdr
489 */
490 if (data->out_frag_pos == 0) {
491 EAP_PWD_SET_LENGTH_BIT(lm_exch);
492 totlen = wpabuf_len(data->outbuf) +
493 EAP_PWD_HDR_SIZE + sizeof(u16);
494 len -= sizeof(u16);
495 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
496 "total length = %d", totlen);
497 }
498 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
499 (int) len);
500 }
501
502 /*
503 * alloc an eap request and populate it with the data
504 */
505 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
506 EAP_PWD_HDR_SIZE + len +
507 (totlen ? sizeof(u16) : 0),
508 EAP_CODE_REQUEST, id);
509 if (req == NULL) {
510 eap_pwd_state(data, FAILURE);
511 return NULL;
512 }
513
514 wpabuf_put_u8(req, lm_exch);
515 if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
516 wpabuf_put_be16(req, totlen);
517
518 buf = wpabuf_head_u8(data->outbuf);
519 wpabuf_put_data(req, buf + data->out_frag_pos, len);
520 data->out_frag_pos += len;
521 /*
522 * either not fragged or last fragment, either way free up the data
523 */
524 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
525 wpabuf_free(data->outbuf);
526 data->out_frag_pos = 0;
527 }
528
529 return req;
530}
531
532
533static Boolean 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
568static 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
574 if (payload_len < sizeof(struct eap_pwd_id)) {
575 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
576 return;
577 }
578
579 id = (struct eap_pwd_id *) payload;
580 if ((data->group_num != be_to_host16(id->group_num)) ||
581 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
582 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
583 (id->prf != EAP_PWD_DEFAULT_PRF)) {
584 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
585 eap_pwd_state(data, FAILURE);
586 return;
587 }
588 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
589 if (data->id_peer == NULL) {
590 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
591 return;
592 }
593 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
594 os_memcpy(data->id_peer, id->identity, data->id_peer_len);
595 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
596 data->id_peer, data->id_peer_len);
597
598 if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == NULL) {
599 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
600 "group");
601 return;
602 }
603 if (compute_password_element(data->grp, data->group_num,
604 data->password, data->password_len,
605 data->id_server, data->id_server_len,
606 data->id_peer, data->id_peer_len,
607 (u8 *) &data->token)) {
608 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
609 "PWE");
610 return;
611 }
612 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
613 BN_num_bits(data->grp->prime));
614
615 eap_pwd_state(data, PWD_Commit_Req);
616}
617
618
619static void
620eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
621 const u8 *payload, size_t payload_len)
622{
623 u8 *ptr;
624 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
625 EC_POINT *K = NULL, *point = NULL;
626 int res = 0;
627
628 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
629
630 if (((data->peer_scalar = BN_new()) == NULL) ||
631 ((data->k = BN_new()) == NULL) ||
632 ((cofactor = BN_new()) == NULL) ||
633 ((x = BN_new()) == NULL) ||
634 ((y = BN_new()) == NULL) ||
635 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
636 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
637 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
638 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
639 "fail");
640 goto fin;
641 }
642
643 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
644 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
645 "cofactor for curve");
646 goto fin;
647 }
648
649 /* element, x then y, followed by scalar */
650 ptr = (u8 *) payload;
651 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
652 ptr += BN_num_bytes(data->grp->prime);
653 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
654 ptr += BN_num_bytes(data->grp->prime);
655 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
656 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
657 data->peer_element, x, y,
658 data->bnctx)) {
659 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
660 "fail");
661 goto fin;
662 }
663
664 /* check to ensure peer's element is not in a small sub-group */
665 if (BN_cmp(cofactor, BN_value_one())) {
666 if (!EC_POINT_mul(data->grp->group, point, NULL,
667 data->peer_element, cofactor, NULL)) {
668 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
669 "multiply peer element by order");
670 goto fin;
671 }
672 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
673 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
674 "is at infinity!\n");
675 goto fin;
676 }
677 }
678
679 /* compute the shared key, k */
680 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
681 data->peer_scalar, data->bnctx)) ||
682 (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
683 data->bnctx)) ||
684 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
685 data->bnctx))) {
686 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
687 "fail");
688 goto fin;
689 }
690
691 /* ensure that the shared key isn't in a small sub-group */
692 if (BN_cmp(cofactor, BN_value_one())) {
693 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
694 NULL)) {
695 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
696 "multiply shared key point by order!\n");
697 goto fin;
698 }
699 }
700
701 /*
702 * This check is strictly speaking just for the case above where
703 * co-factor > 1 but it was suggested that even though this is probably
704 * never going to happen it is a simple and safe check "just to be
705 * sure" so let's be safe.
706 */
707 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
708 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
709 "at infinity");
710 goto fin;
711 }
712 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
713 NULL, data->bnctx)) {
714 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
715 "shared secret from secret point");
716 goto fin;
717 }
718 res = 1;
719
720fin:
721 EC_POINT_free(K);
722 EC_POINT_free(point);
723 BN_free(cofactor);
724 BN_free(x);
725 BN_free(y);
726
727 if (res)
728 eap_pwd_state(data, PWD_Confirm_Req);
729 else
730 eap_pwd_state(data, FAILURE);
731}
732
733
734static void
735eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
736 const u8 *payload, size_t payload_len)
737{
738 BIGNUM *x = NULL, *y = NULL;
739 struct crypto_hash *hash;
740 u32 cs;
741 u16 grp;
742 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
743 int offset;
744
745 /* build up the ciphersuite: group | random_function | prf */
746 grp = htons(data->group_num);
747 ptr = (u8 *) &cs;
748 os_memcpy(ptr, &grp, sizeof(u16));
749 ptr += sizeof(u16);
750 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
751 ptr += sizeof(u8);
752 *ptr = EAP_PWD_DEFAULT_PRF;
753
754 /* each component of the cruft will be at most as big as the prime */
755 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
756 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
757 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
758 goto fin;
759 }
760
761 /*
762 * commit is H(k | peer_element | peer_scalar | server_element |
763 * server_scalar | ciphersuite)
764 */
765 hash = eap_pwd_h_init();
766 if (hash == NULL)
767 goto fin;
768
769 /* k */
770 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
771 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
772 BN_bn2bin(data->k, cruft + offset);
773 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
774
775 /* peer element: x, y */
776 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
777 data->peer_element, x, y,
778 data->bnctx)) {
779 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
780 "assignment fail");
781 goto fin;
782 }
783 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
784 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
785 BN_bn2bin(x, cruft + offset);
786 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
787 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
788 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
789 BN_bn2bin(y, cruft + offset);
790 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
791
792 /* peer scalar */
793 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
794 offset = BN_num_bytes(data->grp->order) -
795 BN_num_bytes(data->peer_scalar);
796 BN_bn2bin(data->peer_scalar, cruft + offset);
797 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
798
799 /* server element: x, y */
800 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
801 data->my_element, x, y,
802 data->bnctx)) {
803 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
804 "assignment fail");
805 goto fin;
806 }
807
808 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
809 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
810 BN_bn2bin(x, cruft + offset);
811 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
812 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
813 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
814 BN_bn2bin(y, cruft + offset);
815 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
816
817 /* server scalar */
818 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
819 offset = BN_num_bytes(data->grp->order) -
820 BN_num_bytes(data->my_scalar);
821 BN_bn2bin(data->my_scalar, cruft + offset);
822 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
823
824 /* ciphersuite */
825 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
826 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
827
828 /* all done */
829 eap_pwd_h_final(hash, conf);
830
831 ptr = (u8 *) payload;
832 if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) {
833 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
834 "verify");
835 goto fin;
836 }
837
838 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
839 if (compute_keys(data->grp, data->bnctx, data->k,
840 data->peer_scalar, data->my_scalar, conf,
841 data->my_confirm, &cs, data->msk, data->emsk) < 0)
842 eap_pwd_state(data, FAILURE);
843 else
844 eap_pwd_state(data, SUCCESS);
845
846fin:
847 os_free(cruft);
848 BN_free(x);
849 BN_free(y);
850}
851
852
853static void eap_pwd_process(struct eap_sm *sm, void *priv,
854 struct wpabuf *respData)
855{
856 struct eap_pwd_data *data = priv;
857 const u8 *pos;
858 size_t len;
859 u8 lm_exch;
860 u16 tot_len;
861
862 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
863 if ((pos == NULL) || (len < 1)) {
864 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
865 (pos == NULL) ? "is NULL" : "is not NULL",
866 (int) len);
867 return;
868 }
869
870 lm_exch = *pos;
871 pos++; /* skip over the bits and the exch */
872 len--;
873
874 /*
875 * if we're fragmenting then this should be an ACK with no data,
876 * just return and continue fragmenting in the "build" section above
877 */
878 if (data->out_frag_pos) {
879 if (len > 1)
880 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
881 "Fragmenting but not an ACK");
882 else
883 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
884 "peer");
885 return;
886 }
887 /*
888 * if we're receiving fragmented packets then we need to buffer...
889 *
890 * the first fragment has a total length
891 */
892 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
893 tot_len = WPA_GET_BE16(pos);
894 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
895 "length = %d", tot_len);
896 data->inbuf = wpabuf_alloc(tot_len);
897 if (data->inbuf == NULL) {
898 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
899 "buffer fragments!");
900 return;
901 }
902 pos += sizeof(u16);
903 len -= sizeof(u16);
904 }
905 /*
906 * the first and all intermediate fragments have the M bit set
907 */
908 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
909 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
910 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
911 "attack detected! (%d+%d > %d)",
912 (int) data->in_frag_pos, (int) len,
913 (int) wpabuf_size(data->inbuf));
914 eap_pwd_state(data, FAILURE);
915 return;
916 }
917 wpabuf_put_data(data->inbuf, pos, len);
918 data->in_frag_pos += len;
919 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
920 (int) len);
921 return;
922 }
923 /*
924 * last fragment won't have the M bit set (but we're obviously
925 * buffering fragments so that's how we know it's the last)
926 */
927 if (data->in_frag_pos) {
928 wpabuf_put_data(data->inbuf, pos, len);
929 data->in_frag_pos += len;
930 pos = wpabuf_head_u8(data->inbuf);
931 len = data->in_frag_pos;
932 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
933 (int) len);
934 }
935 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
936 case EAP_PWD_OPCODE_ID_EXCH:
937 eap_pwd_process_id_resp(sm, data, pos, len);
938 break;
939 case EAP_PWD_OPCODE_COMMIT_EXCH:
940 eap_pwd_process_commit_resp(sm, data, pos, len);
941 break;
942 case EAP_PWD_OPCODE_CONFIRM_EXCH:
943 eap_pwd_process_confirm_resp(sm, data, pos, len);
944 break;
945 }
946 /*
947 * if we had been buffering fragments, here's a great place
948 * to clean up
949 */
950 if (data->in_frag_pos) {
951 wpabuf_free(data->inbuf);
952 data->in_frag_pos = 0;
953 }
954}
955
956
957static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
958{
959 struct eap_pwd_data *data = priv;
960 u8 *key;
961
962 if (data->state != SUCCESS)
963 return NULL;
964
965 key = os_malloc(EAP_MSK_LEN);
966 if (key == NULL)
967 return NULL;
968
969 os_memcpy(key, data->msk, EAP_MSK_LEN);
970 *len = EAP_MSK_LEN;
971
972 return key;
973}
974
975
976static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
977{
978 struct eap_pwd_data *data = priv;
979 u8 *key;
980
981 if (data->state != SUCCESS)
982 return NULL;
983
984 key = os_malloc(EAP_EMSK_LEN);
985 if (key == NULL)
986 return NULL;
987
988 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
989 *len = EAP_EMSK_LEN;
990
991 return key;
992}
993
994
995static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
996{
997 struct eap_pwd_data *data = priv;
998 return data->state == SUCCESS;
999}
1000
1001
1002static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1003{
1004 struct eap_pwd_data *data = priv;
1005 return (data->state == SUCCESS) || (data->state == FAILURE);
1006}
1007
1008
1009int eap_server_pwd_register(void)
1010{
1011 struct eap_method *eap;
1012 int ret;
1013 struct timeval tp;
1014 struct timezone tz;
1015 u32 sr;
1016
1017 EVP_add_digest(EVP_sha256());
1018
1019 sr = 0xdeaddada;
1020 (void) gettimeofday(&tp, &tz);
1021 sr ^= (tp.tv_sec ^ tp.tv_usec);
1022 srandom(sr);
1023
1024 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1025 EAP_VENDOR_IETF, EAP_TYPE_PWD,
1026 "PWD");
1027 if (eap == NULL)
1028 return -1;
1029
1030 eap->init = eap_pwd_init;
1031 eap->reset = eap_pwd_reset;
1032 eap->buildReq = eap_pwd_build_req;
1033 eap->check = eap_pwd_check;
1034 eap->process = eap_pwd_process;
1035 eap->isDone = eap_pwd_is_done;
1036 eap->getKey = eap_pwd_getkey;
1037 eap->get_emsk = eap_pwd_get_emsk;
1038 eap->isSuccess = eap_pwd_is_success;
1039
1040 ret = eap_server_method_register(eap);
1041 if (ret)
1042 eap_server_method_free(eap);
1043 return ret;
1044}
1045