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
eap_pwd_state_txt(int state)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
eap_pwd_state(struct eap_pwd_data * data,int state)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
eap_pwd_init(struct eap_sm * sm)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
eap_pwd_reset(struct eap_sm * sm,void * priv)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
eap_pwd_build_id_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)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
eap_pwd_build_commit_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)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
eap_pwd_build_confirm_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)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 *
eap_pwd_build_req(struct eap_sm * sm,void * priv,u8 id)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
eap_pwd_check(struct eap_sm * sm,void * priv,struct wpabuf * respData)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
eap_pwd_process_id_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)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 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
607 eap_pwd_state(data, FAILURE);
608 return;
609 }
610 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
611 if (data->id_peer == NULL) {
612 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
613 return;
614 }
615 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
616 os_memcpy(data->id_peer, id->identity, data->id_peer_len);
617 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
618 data->id_peer, data->id_peer_len);
619
620 data->grp = os_zalloc(sizeof(EAP_PWD_group));
621 if (data->grp == NULL) {
622 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
623 "group");
624 return;
625 }
626
627 if (data->password_hash) {
628 res = hash_nt_password_hash(data->password, pwhashhash);
629 if (res)
630 return;
631 password = pwhashhash;
632 password_len = sizeof(pwhashhash);
633 } else {
634 password = data->password;
635 password_len = data->password_len;
636 }
637
638 res = compute_password_element(data->grp, data->group_num,
639 password, password_len,
640 data->id_server, data->id_server_len,
641 data->id_peer, data->id_peer_len,
642 (u8 *) &data->token);
643 os_memset(pwhashhash, 0, sizeof(pwhashhash));
644 if (res) {
645 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
646 "PWE");
647 return;
648 }
649 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
650 BN_num_bits(data->grp->prime));
651
652 eap_pwd_state(data, PWD_Commit_Req);
653 }
654
655
656 static void
eap_pwd_process_commit_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)657 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
658 const u8 *payload, size_t payload_len)
659 {
660 u8 *ptr;
661 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
662 EC_POINT *K = NULL, *point = NULL;
663 int res = 0;
664 size_t prime_len, order_len;
665
666 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
667
668 prime_len = BN_num_bytes(data->grp->prime);
669 order_len = BN_num_bytes(data->grp->order);
670
671 if (payload_len != 2 * prime_len + order_len) {
672 wpa_printf(MSG_INFO,
673 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
674 (unsigned int) payload_len,
675 (unsigned int) (2 * prime_len + order_len));
676 goto fin;
677 }
678
679 if (((data->peer_scalar = BN_new()) == NULL) ||
680 ((data->k = BN_new()) == NULL) ||
681 ((cofactor = BN_new()) == NULL) ||
682 ((x = BN_new()) == NULL) ||
683 ((y = BN_new()) == NULL) ||
684 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
685 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
686 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
687 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
688 "fail");
689 goto fin;
690 }
691
692 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
693 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
694 "cofactor for curve");
695 goto fin;
696 }
697
698 /* element, x then y, followed by scalar */
699 ptr = (u8 *) payload;
700 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
701 ptr += BN_num_bytes(data->grp->prime);
702 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
703 ptr += BN_num_bytes(data->grp->prime);
704 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
705 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
706 data->peer_element, x, y,
707 data->bnctx)) {
708 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
709 "fail");
710 goto fin;
711 }
712
713 /* check to ensure peer's element is not in a small sub-group */
714 if (BN_cmp(cofactor, BN_value_one())) {
715 if (!EC_POINT_mul(data->grp->group, point, NULL,
716 data->peer_element, cofactor, NULL)) {
717 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
718 "multiply peer element by order");
719 goto fin;
720 }
721 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
722 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
723 "is at infinity!\n");
724 goto fin;
725 }
726 }
727
728 /* compute the shared key, k */
729 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
730 data->peer_scalar, data->bnctx)) ||
731 (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
732 data->bnctx)) ||
733 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
734 data->bnctx))) {
735 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
736 "fail");
737 goto fin;
738 }
739
740 /* ensure that the shared key isn't in a small sub-group */
741 if (BN_cmp(cofactor, BN_value_one())) {
742 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
743 NULL)) {
744 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
745 "multiply shared key point by order!\n");
746 goto fin;
747 }
748 }
749
750 /*
751 * This check is strictly speaking just for the case above where
752 * co-factor > 1 but it was suggested that even though this is probably
753 * never going to happen it is a simple and safe check "just to be
754 * sure" so let's be safe.
755 */
756 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
757 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
758 "at infinity");
759 goto fin;
760 }
761 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
762 NULL, data->bnctx)) {
763 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
764 "shared secret from secret point");
765 goto fin;
766 }
767 res = 1;
768
769 fin:
770 EC_POINT_clear_free(K);
771 EC_POINT_clear_free(point);
772 BN_clear_free(cofactor);
773 BN_clear_free(x);
774 BN_clear_free(y);
775
776 if (res)
777 eap_pwd_state(data, PWD_Confirm_Req);
778 else
779 eap_pwd_state(data, FAILURE);
780 }
781
782
783 static void
eap_pwd_process_confirm_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)784 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
785 const u8 *payload, size_t payload_len)
786 {
787 BIGNUM *x = NULL, *y = NULL;
788 struct crypto_hash *hash;
789 u32 cs;
790 u16 grp;
791 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
792 int offset;
793
794 if (payload_len != SHA256_MAC_LEN) {
795 wpa_printf(MSG_INFO,
796 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
797 (unsigned int) payload_len, SHA256_MAC_LEN);
798 goto fin;
799 }
800
801 /* build up the ciphersuite: group | random_function | prf */
802 grp = htons(data->group_num);
803 ptr = (u8 *) &cs;
804 os_memcpy(ptr, &grp, sizeof(u16));
805 ptr += sizeof(u16);
806 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
807 ptr += sizeof(u8);
808 *ptr = EAP_PWD_DEFAULT_PRF;
809
810 /* each component of the cruft will be at most as big as the prime */
811 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
812 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
813 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
814 goto fin;
815 }
816
817 /*
818 * commit is H(k | peer_element | peer_scalar | server_element |
819 * server_scalar | ciphersuite)
820 */
821 hash = eap_pwd_h_init();
822 if (hash == NULL)
823 goto fin;
824
825 /* k */
826 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
827 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
828 BN_bn2bin(data->k, cruft + offset);
829 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
830
831 /* peer element: x, y */
832 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
833 data->peer_element, x, y,
834 data->bnctx)) {
835 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
836 "assignment fail");
837 goto fin;
838 }
839 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
840 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
841 BN_bn2bin(x, cruft + offset);
842 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
843 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
844 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
845 BN_bn2bin(y, cruft + offset);
846 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
847
848 /* peer scalar */
849 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
850 offset = BN_num_bytes(data->grp->order) -
851 BN_num_bytes(data->peer_scalar);
852 BN_bn2bin(data->peer_scalar, cruft + offset);
853 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
854
855 /* server element: x, y */
856 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
857 data->my_element, x, y,
858 data->bnctx)) {
859 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
860 "assignment fail");
861 goto fin;
862 }
863
864 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
865 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
866 BN_bn2bin(x, cruft + offset);
867 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
868 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
869 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
870 BN_bn2bin(y, cruft + offset);
871 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
872
873 /* server scalar */
874 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
875 offset = BN_num_bytes(data->grp->order) -
876 BN_num_bytes(data->my_scalar);
877 BN_bn2bin(data->my_scalar, cruft + offset);
878 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
879
880 /* ciphersuite */
881 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
882 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
883
884 /* all done */
885 eap_pwd_h_final(hash, conf);
886
887 ptr = (u8 *) payload;
888 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
889 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
890 "verify");
891 goto fin;
892 }
893
894 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
895 if (compute_keys(data->grp, data->bnctx, data->k,
896 data->peer_scalar, data->my_scalar, conf,
897 data->my_confirm, &cs, data->msk, data->emsk,
898 data->session_id) < 0)
899 eap_pwd_state(data, FAILURE);
900 else
901 eap_pwd_state(data, SUCCESS);
902
903 fin:
904 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
905 BN_clear_free(x);
906 BN_clear_free(y);
907 }
908
909
eap_pwd_process(struct eap_sm * sm,void * priv,struct wpabuf * respData)910 static void eap_pwd_process(struct eap_sm *sm, void *priv,
911 struct wpabuf *respData)
912 {
913 struct eap_pwd_data *data = priv;
914 const u8 *pos;
915 size_t len;
916 u8 lm_exch;
917 u16 tot_len;
918
919 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
920 if ((pos == NULL) || (len < 1)) {
921 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
922 (pos == NULL) ? "is NULL" : "is not NULL",
923 (int) len);
924 return;
925 }
926
927 lm_exch = *pos;
928 pos++; /* skip over the bits and the exch */
929 len--;
930
931 /*
932 * if we're fragmenting then this should be an ACK with no data,
933 * just return and continue fragmenting in the "build" section above
934 */
935 if (data->out_frag_pos) {
936 if (len > 1)
937 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
938 "Fragmenting but not an ACK");
939 else
940 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
941 "peer");
942 return;
943 }
944 /*
945 * if we're receiving fragmented packets then we need to buffer...
946 *
947 * the first fragment has a total length
948 */
949 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
950 if (len < 2) {
951 wpa_printf(MSG_DEBUG,
952 "EAP-pwd: Frame too short to contain Total-Length field");
953 return;
954 }
955 tot_len = WPA_GET_BE16(pos);
956 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
957 "length = %d", tot_len);
958 if (tot_len > 15000)
959 return;
960 if (data->inbuf) {
961 wpa_printf(MSG_DEBUG,
962 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
963 return;
964 }
965 data->inbuf = wpabuf_alloc(tot_len);
966 if (data->inbuf == NULL) {
967 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
968 "buffer fragments!");
969 return;
970 }
971 data->in_frag_pos = 0;
972 pos += sizeof(u16);
973 len -= sizeof(u16);
974 }
975 /*
976 * the first and all intermediate fragments have the M bit set
977 */
978 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
979 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
980 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
981 "attack detected! (%d+%d > %d)",
982 (int) data->in_frag_pos, (int) len,
983 (int) wpabuf_size(data->inbuf));
984 eap_pwd_state(data, FAILURE);
985 return;
986 }
987 wpabuf_put_data(data->inbuf, pos, len);
988 data->in_frag_pos += len;
989 }
990 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
991 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
992 (int) len);
993 return;
994 }
995 /*
996 * last fragment won't have the M bit set (but we're obviously
997 * buffering fragments so that's how we know it's the last)
998 */
999 if (data->in_frag_pos) {
1000 pos = wpabuf_head_u8(data->inbuf);
1001 len = data->in_frag_pos;
1002 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
1003 (int) len);
1004 }
1005 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
1006 case EAP_PWD_OPCODE_ID_EXCH:
1007 eap_pwd_process_id_resp(sm, data, pos, len);
1008 break;
1009 case EAP_PWD_OPCODE_COMMIT_EXCH:
1010 eap_pwd_process_commit_resp(sm, data, pos, len);
1011 break;
1012 case EAP_PWD_OPCODE_CONFIRM_EXCH:
1013 eap_pwd_process_confirm_resp(sm, data, pos, len);
1014 break;
1015 }
1016 /*
1017 * if we had been buffering fragments, here's a great place
1018 * to clean up
1019 */
1020 if (data->in_frag_pos) {
1021 wpabuf_free(data->inbuf);
1022 data->inbuf = NULL;
1023 data->in_frag_pos = 0;
1024 }
1025 }
1026
1027
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)1028 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
1029 {
1030 struct eap_pwd_data *data = priv;
1031 u8 *key;
1032
1033 if (data->state != SUCCESS)
1034 return NULL;
1035
1036 key = os_malloc(EAP_MSK_LEN);
1037 if (key == NULL)
1038 return NULL;
1039
1040 os_memcpy(key, data->msk, EAP_MSK_LEN);
1041 *len = EAP_MSK_LEN;
1042
1043 return key;
1044 }
1045
1046
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)1047 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1048 {
1049 struct eap_pwd_data *data = priv;
1050 u8 *key;
1051
1052 if (data->state != SUCCESS)
1053 return NULL;
1054
1055 key = os_malloc(EAP_EMSK_LEN);
1056 if (key == NULL)
1057 return NULL;
1058
1059 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1060 *len = EAP_EMSK_LEN;
1061
1062 return key;
1063 }
1064
1065
eap_pwd_is_success(struct eap_sm * sm,void * priv)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
eap_pwd_is_done(struct eap_sm * sm,void * priv)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
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)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_malloc(1 + SHA256_MAC_LEN);
1089 if (id == NULL)
1090 return NULL;
1091
1092 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
1093 *len = 1 + SHA256_MAC_LEN;
1094
1095 return id;
1096 }
1097
1098
eap_server_pwd_register(void)1099 int eap_server_pwd_register(void)
1100 {
1101 struct eap_method *eap;
1102 struct timeval tp;
1103 struct timezone tz;
1104 u32 sr;
1105
1106 sr = 0xdeaddada;
1107 (void) gettimeofday(&tp, &tz);
1108 sr ^= (tp.tv_sec ^ tp.tv_usec);
1109 srandom(sr);
1110
1111 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1112 EAP_VENDOR_IETF, EAP_TYPE_PWD,
1113 "PWD");
1114 if (eap == NULL)
1115 return -1;
1116
1117 eap->init = eap_pwd_init;
1118 eap->reset = eap_pwd_reset;
1119 eap->buildReq = eap_pwd_build_req;
1120 eap->check = eap_pwd_check;
1121 eap->process = eap_pwd_process;
1122 eap->isDone = eap_pwd_is_done;
1123 eap->getKey = eap_pwd_getkey;
1124 eap->get_emsk = eap_pwd_get_emsk;
1125 eap->isSuccess = eap_pwd_is_success;
1126 eap->getSessionId = eap_pwd_get_session_id;
1127
1128 return eap_server_method_register(eap);
1129 }
1130
1131