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 /* an lfsr is good enough to generate unpredictable tokens */
182 data->token = os_random();
183 wpabuf_put_be16(data->outbuf, data->group_num);
184 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
185 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
186 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
187 wpabuf_put_u8(data->outbuf, data->password_hash ? EAP_PWD_PREP_MS :
188 EAP_PWD_PREP_NONE);
189 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
190 }
191
192
eap_pwd_build_commit_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)193 static void eap_pwd_build_commit_req(struct eap_sm *sm,
194 struct eap_pwd_data *data, u8 id)
195 {
196 BIGNUM *mask = NULL, *x = NULL, *y = NULL;
197 u8 *scalar = NULL, *element = NULL;
198 u16 offset;
199
200 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
201 /*
202 * if we're fragmenting then we already have an commit request, just
203 * return
204 */
205 if (data->out_frag_pos)
206 return;
207
208 if (((data->private_value = BN_new()) == NULL) ||
209 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
210 ((data->my_scalar = BN_new()) == NULL) ||
211 ((mask = BN_new()) == NULL)) {
212 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
213 "fail");
214 goto fin;
215 }
216
217 if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
218 BN_rand_range(mask, data->grp->order) != 1 ||
219 BN_add(data->my_scalar, data->private_value, mask) != 1 ||
220 BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
221 data->bnctx) != 1) {
222 wpa_printf(MSG_INFO,
223 "EAP-pwd (server): unable to get randomness");
224 goto fin;
225 }
226
227 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
228 data->grp->pwe, mask, data->bnctx)) {
229 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
230 "fail");
231 eap_pwd_state(data, FAILURE);
232 goto fin;
233 }
234
235 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
236 {
237 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
238 "fail");
239 goto fin;
240 }
241 BN_clear_free(mask);
242
243 if (((x = BN_new()) == NULL) ||
244 ((y = BN_new()) == NULL)) {
245 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
246 "fail");
247 goto fin;
248 }
249 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
250 data->my_element, x, y,
251 data->bnctx)) {
252 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
253 "fail");
254 goto fin;
255 }
256
257 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
258 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
259 NULL)) {
260 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
261 goto fin;
262 }
263
264 /*
265 * bignums occupy as little memory as possible so one that is
266 * sufficiently smaller than the prime or order might need pre-pending
267 * with zeros.
268 */
269 os_memset(scalar, 0, BN_num_bytes(data->grp->order));
270 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
271 offset = BN_num_bytes(data->grp->order) -
272 BN_num_bytes(data->my_scalar);
273 BN_bn2bin(data->my_scalar, scalar + offset);
274
275 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
276 BN_bn2bin(x, element + offset);
277 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
278 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
279
280 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
281 BN_num_bytes(data->grp->order));
282 if (data->outbuf == NULL)
283 goto fin;
284
285 /* We send the element as (x,y) followed by the scalar */
286 wpabuf_put_data(data->outbuf, element,
287 2 * BN_num_bytes(data->grp->prime));
288 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
289
290 fin:
291 os_free(scalar);
292 os_free(element);
293 BN_clear_free(x);
294 BN_clear_free(y);
295 if (data->outbuf == NULL)
296 eap_pwd_state(data, FAILURE);
297 }
298
299
eap_pwd_build_confirm_req(struct eap_sm * sm,struct eap_pwd_data * data,u8 id)300 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
301 struct eap_pwd_data *data, u8 id)
302 {
303 BIGNUM *x = NULL, *y = NULL;
304 struct crypto_hash *hash;
305 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
306 u16 grp;
307 int offset;
308
309 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
310 /*
311 * if we're fragmenting then we already have an confirm request, just
312 * return
313 */
314 if (data->out_frag_pos)
315 return;
316
317 /* Each component of the cruft will be at most as big as the prime */
318 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
319 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
320 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
321 "fail");
322 goto fin;
323 }
324
325 /*
326 * commit is H(k | server_element | server_scalar | peer_element |
327 * peer_scalar | ciphersuite)
328 */
329 hash = eap_pwd_h_init();
330 if (hash == NULL)
331 goto fin;
332
333 /*
334 * Zero the memory each time because this is mod prime math and some
335 * value may start with a few zeros and the previous one did not.
336 *
337 * First is k
338 */
339 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
340 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
341 BN_bn2bin(data->k, cruft + offset);
342 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
343
344 /* server element: x, y */
345 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
346 data->my_element, x, y,
347 data->bnctx)) {
348 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
349 "assignment fail");
350 goto fin;
351 }
352
353 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
354 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
355 BN_bn2bin(x, cruft + offset);
356 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
357 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
358 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
359 BN_bn2bin(y, cruft + offset);
360 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
361
362 /* server scalar */
363 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
364 offset = BN_num_bytes(data->grp->order) -
365 BN_num_bytes(data->my_scalar);
366 BN_bn2bin(data->my_scalar, cruft + offset);
367 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
368
369 /* peer element: x, y */
370 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
371 data->peer_element, x, y,
372 data->bnctx)) {
373 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
374 "assignment fail");
375 goto fin;
376 }
377
378 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
379 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
380 BN_bn2bin(x, cruft + offset);
381 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
382 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
383 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
384 BN_bn2bin(y, cruft + offset);
385 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
386
387 /* peer scalar */
388 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
389 offset = BN_num_bytes(data->grp->order) -
390 BN_num_bytes(data->peer_scalar);
391 BN_bn2bin(data->peer_scalar, cruft + offset);
392 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
393
394 /* ciphersuite */
395 grp = htons(data->group_num);
396 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
397 ptr = cruft;
398 os_memcpy(ptr, &grp, sizeof(u16));
399 ptr += sizeof(u16);
400 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
401 ptr += sizeof(u8);
402 *ptr = EAP_PWD_DEFAULT_PRF;
403 ptr += sizeof(u8);
404 eap_pwd_h_update(hash, cruft, ptr - cruft);
405
406 /* all done with the random function */
407 eap_pwd_h_final(hash, conf);
408 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
409
410 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
411 if (data->outbuf == NULL)
412 goto fin;
413
414 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
415
416 fin:
417 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
418 BN_clear_free(x);
419 BN_clear_free(y);
420 if (data->outbuf == NULL)
421 eap_pwd_state(data, FAILURE);
422 }
423
424
425 static struct wpabuf *
eap_pwd_build_req(struct eap_sm * sm,void * priv,u8 id)426 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
427 {
428 struct eap_pwd_data *data = priv;
429 struct wpabuf *req;
430 u8 lm_exch;
431 const u8 *buf;
432 u16 totlen = 0;
433 size_t len;
434
435 /*
436 * if we're buffering response fragments then just ACK
437 */
438 if (data->in_frag_pos) {
439 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
440 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
441 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
442 if (req == NULL) {
443 eap_pwd_state(data, FAILURE);
444 return NULL;
445 }
446 switch (data->state) {
447 case PWD_ID_Req:
448 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
449 break;
450 case PWD_Commit_Req:
451 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
452 break;
453 case PWD_Confirm_Req:
454 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
455 break;
456 default:
457 eap_pwd_state(data, FAILURE); /* just to be sure */
458 wpabuf_free(req);
459 return NULL;
460 }
461 return req;
462 }
463
464 /*
465 * build the data portion of a request
466 */
467 switch (data->state) {
468 case PWD_ID_Req:
469 eap_pwd_build_id_req(sm, data, id);
470 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
471 break;
472 case PWD_Commit_Req:
473 eap_pwd_build_commit_req(sm, data, id);
474 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
475 break;
476 case PWD_Confirm_Req:
477 eap_pwd_build_confirm_req(sm, data, id);
478 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
479 break;
480 default:
481 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
482 data->state);
483 eap_pwd_state(data, FAILURE);
484 lm_exch = 0; /* hush now, sweet compiler */
485 break;
486 }
487
488 if (data->state == FAILURE)
489 return NULL;
490
491 /*
492 * determine whether that data needs to be fragmented
493 */
494 len = wpabuf_len(data->outbuf) - data->out_frag_pos;
495 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
496 len = data->mtu - EAP_PWD_HDR_SIZE;
497 EAP_PWD_SET_MORE_BIT(lm_exch);
498 /*
499 * if this is the first fragment, need to set the M bit
500 * and add the total length to the eap_pwd_hdr
501 */
502 if (data->out_frag_pos == 0) {
503 EAP_PWD_SET_LENGTH_BIT(lm_exch);
504 totlen = wpabuf_len(data->outbuf) +
505 EAP_PWD_HDR_SIZE + sizeof(u16);
506 len -= sizeof(u16);
507 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
508 "total length = %d", totlen);
509 }
510 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
511 (int) len);
512 }
513
514 /*
515 * alloc an eap request and populate it with the data
516 */
517 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
518 EAP_PWD_HDR_SIZE + len +
519 (totlen ? sizeof(u16) : 0),
520 EAP_CODE_REQUEST, id);
521 if (req == NULL) {
522 eap_pwd_state(data, FAILURE);
523 return NULL;
524 }
525
526 wpabuf_put_u8(req, lm_exch);
527 if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
528 wpabuf_put_be16(req, totlen);
529
530 buf = wpabuf_head_u8(data->outbuf);
531 wpabuf_put_data(req, buf + data->out_frag_pos, len);
532 data->out_frag_pos += len;
533 /*
534 * either not fragged or last fragment, either way free up the data
535 */
536 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
537 wpabuf_free(data->outbuf);
538 data->outbuf = NULL;
539 data->out_frag_pos = 0;
540 }
541
542 return req;
543 }
544
545
eap_pwd_check(struct eap_sm * sm,void * priv,struct wpabuf * respData)546 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
547 struct wpabuf *respData)
548 {
549 struct eap_pwd_data *data = priv;
550 const u8 *pos;
551 size_t len;
552
553 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
554 if (pos == NULL || len < 1) {
555 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
556 return TRUE;
557 }
558
559 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
560 EAP_PWD_GET_EXCHANGE(*pos), (int) len);
561
562 if (data->state == PWD_ID_Req &&
563 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
564 return FALSE;
565
566 if (data->state == PWD_Commit_Req &&
567 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
568 return FALSE;
569
570 if (data->state == PWD_Confirm_Req &&
571 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
572 return FALSE;
573
574 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
575 *pos, data->state);
576
577 return TRUE;
578 }
579
580
eap_pwd_process_id_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)581 static void eap_pwd_process_id_resp(struct eap_sm *sm,
582 struct eap_pwd_data *data,
583 const u8 *payload, size_t payload_len)
584 {
585 struct eap_pwd_id *id;
586 const u8 *password;
587 size_t password_len;
588 u8 pwhashhash[16];
589 int res;
590
591 if (payload_len < sizeof(struct eap_pwd_id)) {
592 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
593 return;
594 }
595
596 id = (struct eap_pwd_id *) payload;
597 if ((data->group_num != be_to_host16(id->group_num)) ||
598 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
599 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
600 (id->prf != EAP_PWD_DEFAULT_PRF)) {
601 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
602 eap_pwd_state(data, FAILURE);
603 return;
604 }
605 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
606 if (data->id_peer == NULL) {
607 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
608 return;
609 }
610 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
611 os_memcpy(data->id_peer, id->identity, data->id_peer_len);
612 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
613 data->id_peer, data->id_peer_len);
614
615 data->grp = os_zalloc(sizeof(EAP_PWD_group));
616 if (data->grp == NULL) {
617 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
618 "group");
619 return;
620 }
621
622 if (data->password_hash) {
623 res = hash_nt_password_hash(data->password, pwhashhash);
624 if (res)
625 return;
626 password = pwhashhash;
627 password_len = sizeof(pwhashhash);
628 } else {
629 password = data->password;
630 password_len = data->password_len;
631 }
632
633 res = compute_password_element(data->grp, data->group_num,
634 password, password_len,
635 data->id_server, data->id_server_len,
636 data->id_peer, data->id_peer_len,
637 (u8 *) &data->token);
638 os_memset(pwhashhash, 0, sizeof(pwhashhash));
639 if (res) {
640 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
641 "PWE");
642 return;
643 }
644 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
645 BN_num_bits(data->grp->prime));
646
647 eap_pwd_state(data, PWD_Commit_Req);
648 }
649
650
651 static void
eap_pwd_process_commit_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)652 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
653 const u8 *payload, size_t payload_len)
654 {
655 u8 *ptr;
656 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
657 EC_POINT *K = NULL, *point = NULL;
658 int res = 0;
659 size_t prime_len, order_len;
660
661 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
662
663 prime_len = BN_num_bytes(data->grp->prime);
664 order_len = BN_num_bytes(data->grp->order);
665
666 if (payload_len != 2 * prime_len + order_len) {
667 wpa_printf(MSG_INFO,
668 "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
669 (unsigned int) payload_len,
670 (unsigned int) (2 * prime_len + order_len));
671 goto fin;
672 }
673
674 if (((data->peer_scalar = BN_new()) == NULL) ||
675 ((data->k = BN_new()) == NULL) ||
676 ((cofactor = BN_new()) == NULL) ||
677 ((x = BN_new()) == NULL) ||
678 ((y = BN_new()) == NULL) ||
679 ((point = EC_POINT_new(data->grp->group)) == NULL) ||
680 ((K = EC_POINT_new(data->grp->group)) == NULL) ||
681 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
682 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
683 "fail");
684 goto fin;
685 }
686
687 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
688 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
689 "cofactor for curve");
690 goto fin;
691 }
692
693 /* element, x then y, followed by scalar */
694 ptr = (u8 *) payload;
695 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
696 ptr += BN_num_bytes(data->grp->prime);
697 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
698 ptr += BN_num_bytes(data->grp->prime);
699 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
700 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
701 data->peer_element, x, y,
702 data->bnctx)) {
703 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
704 "fail");
705 goto fin;
706 }
707
708 /* check to ensure peer's element is not in a small sub-group */
709 if (BN_cmp(cofactor, BN_value_one())) {
710 if (!EC_POINT_mul(data->grp->group, point, NULL,
711 data->peer_element, cofactor, NULL)) {
712 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
713 "multiply peer element by order");
714 goto fin;
715 }
716 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
717 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
718 "is at infinity!\n");
719 goto fin;
720 }
721 }
722
723 /* compute the shared key, k */
724 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
725 data->peer_scalar, data->bnctx)) ||
726 (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
727 data->bnctx)) ||
728 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
729 data->bnctx))) {
730 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
731 "fail");
732 goto fin;
733 }
734
735 /* ensure that the shared key isn't in a small sub-group */
736 if (BN_cmp(cofactor, BN_value_one())) {
737 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
738 NULL)) {
739 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
740 "multiply shared key point by order!\n");
741 goto fin;
742 }
743 }
744
745 /*
746 * This check is strictly speaking just for the case above where
747 * co-factor > 1 but it was suggested that even though this is probably
748 * never going to happen it is a simple and safe check "just to be
749 * sure" so let's be safe.
750 */
751 if (EC_POINT_is_at_infinity(data->grp->group, K)) {
752 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
753 "at infinity");
754 goto fin;
755 }
756 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
757 NULL, data->bnctx)) {
758 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
759 "shared secret from secret point");
760 goto fin;
761 }
762 res = 1;
763
764 fin:
765 EC_POINT_clear_free(K);
766 EC_POINT_clear_free(point);
767 BN_clear_free(cofactor);
768 BN_clear_free(x);
769 BN_clear_free(y);
770
771 if (res)
772 eap_pwd_state(data, PWD_Confirm_Req);
773 else
774 eap_pwd_state(data, FAILURE);
775 }
776
777
778 static void
eap_pwd_process_confirm_resp(struct eap_sm * sm,struct eap_pwd_data * data,const u8 * payload,size_t payload_len)779 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
780 const u8 *payload, size_t payload_len)
781 {
782 BIGNUM *x = NULL, *y = NULL;
783 struct crypto_hash *hash;
784 u32 cs;
785 u16 grp;
786 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
787 int offset;
788
789 if (payload_len != SHA256_MAC_LEN) {
790 wpa_printf(MSG_INFO,
791 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
792 (unsigned int) payload_len, SHA256_MAC_LEN);
793 goto fin;
794 }
795
796 /* build up the ciphersuite: group | random_function | prf */
797 grp = htons(data->group_num);
798 ptr = (u8 *) &cs;
799 os_memcpy(ptr, &grp, sizeof(u16));
800 ptr += sizeof(u16);
801 *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
802 ptr += sizeof(u8);
803 *ptr = EAP_PWD_DEFAULT_PRF;
804
805 /* each component of the cruft will be at most as big as the prime */
806 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
807 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
808 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
809 goto fin;
810 }
811
812 /*
813 * commit is H(k | peer_element | peer_scalar | server_element |
814 * server_scalar | ciphersuite)
815 */
816 hash = eap_pwd_h_init();
817 if (hash == NULL)
818 goto fin;
819
820 /* k */
821 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
822 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
823 BN_bn2bin(data->k, cruft + offset);
824 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
825
826 /* peer element: x, y */
827 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
828 data->peer_element, x, y,
829 data->bnctx)) {
830 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
831 "assignment fail");
832 goto fin;
833 }
834 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
835 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
836 BN_bn2bin(x, cruft + offset);
837 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
838 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
839 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
840 BN_bn2bin(y, cruft + offset);
841 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
842
843 /* peer scalar */
844 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
845 offset = BN_num_bytes(data->grp->order) -
846 BN_num_bytes(data->peer_scalar);
847 BN_bn2bin(data->peer_scalar, cruft + offset);
848 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
849
850 /* server element: x, y */
851 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
852 data->my_element, x, y,
853 data->bnctx)) {
854 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
855 "assignment fail");
856 goto fin;
857 }
858
859 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
860 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
861 BN_bn2bin(x, cruft + offset);
862 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
863 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
864 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
865 BN_bn2bin(y, cruft + offset);
866 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
867
868 /* server scalar */
869 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
870 offset = BN_num_bytes(data->grp->order) -
871 BN_num_bytes(data->my_scalar);
872 BN_bn2bin(data->my_scalar, cruft + offset);
873 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
874
875 /* ciphersuite */
876 os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
877 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
878
879 /* all done */
880 eap_pwd_h_final(hash, conf);
881
882 ptr = (u8 *) payload;
883 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
884 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
885 "verify");
886 goto fin;
887 }
888
889 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
890 if (compute_keys(data->grp, data->bnctx, data->k,
891 data->peer_scalar, data->my_scalar, conf,
892 data->my_confirm, &cs, data->msk, data->emsk,
893 data->session_id) < 0)
894 eap_pwd_state(data, FAILURE);
895 else
896 eap_pwd_state(data, SUCCESS);
897
898 fin:
899 bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
900 BN_clear_free(x);
901 BN_clear_free(y);
902 }
903
904
eap_pwd_process(struct eap_sm * sm,void * priv,struct wpabuf * respData)905 static void eap_pwd_process(struct eap_sm *sm, void *priv,
906 struct wpabuf *respData)
907 {
908 struct eap_pwd_data *data = priv;
909 const u8 *pos;
910 size_t len;
911 u8 lm_exch;
912 u16 tot_len;
913
914 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
915 if ((pos == NULL) || (len < 1)) {
916 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
917 (pos == NULL) ? "is NULL" : "is not NULL",
918 (int) len);
919 return;
920 }
921
922 lm_exch = *pos;
923 pos++; /* skip over the bits and the exch */
924 len--;
925
926 /*
927 * if we're fragmenting then this should be an ACK with no data,
928 * just return and continue fragmenting in the "build" section above
929 */
930 if (data->out_frag_pos) {
931 if (len > 1)
932 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
933 "Fragmenting but not an ACK");
934 else
935 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
936 "peer");
937 return;
938 }
939 /*
940 * if we're receiving fragmented packets then we need to buffer...
941 *
942 * the first fragment has a total length
943 */
944 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
945 if (len < 2) {
946 wpa_printf(MSG_DEBUG,
947 "EAP-pwd: Frame too short to contain Total-Length field");
948 return;
949 }
950 tot_len = WPA_GET_BE16(pos);
951 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
952 "length = %d", tot_len);
953 if (tot_len > 15000)
954 return;
955 if (data->inbuf) {
956 wpa_printf(MSG_DEBUG,
957 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
958 return;
959 }
960 data->inbuf = wpabuf_alloc(tot_len);
961 if (data->inbuf == NULL) {
962 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
963 "buffer fragments!");
964 return;
965 }
966 data->in_frag_pos = 0;
967 pos += sizeof(u16);
968 len -= sizeof(u16);
969 }
970 /*
971 * the first and all intermediate fragments have the M bit set
972 */
973 if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
974 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
975 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
976 "attack detected! (%d+%d > %d)",
977 (int) data->in_frag_pos, (int) len,
978 (int) wpabuf_size(data->inbuf));
979 eap_pwd_state(data, FAILURE);
980 return;
981 }
982 wpabuf_put_data(data->inbuf, pos, len);
983 data->in_frag_pos += len;
984 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
985 (int) len);
986 return;
987 }
988 /*
989 * last fragment won't have the M bit set (but we're obviously
990 * buffering fragments so that's how we know it's the last)
991 */
992 if (data->in_frag_pos) {
993 wpabuf_put_data(data->inbuf, pos, len);
994 data->in_frag_pos += len;
995 pos = wpabuf_head_u8(data->inbuf);
996 len = data->in_frag_pos;
997 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
998 (int) len);
999 }
1000 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
1001 case EAP_PWD_OPCODE_ID_EXCH:
1002 eap_pwd_process_id_resp(sm, data, pos, len);
1003 break;
1004 case EAP_PWD_OPCODE_COMMIT_EXCH:
1005 eap_pwd_process_commit_resp(sm, data, pos, len);
1006 break;
1007 case EAP_PWD_OPCODE_CONFIRM_EXCH:
1008 eap_pwd_process_confirm_resp(sm, data, pos, len);
1009 break;
1010 }
1011 /*
1012 * if we had been buffering fragments, here's a great place
1013 * to clean up
1014 */
1015 if (data->in_frag_pos) {
1016 wpabuf_free(data->inbuf);
1017 data->inbuf = NULL;
1018 data->in_frag_pos = 0;
1019 }
1020 }
1021
1022
eap_pwd_getkey(struct eap_sm * sm,void * priv,size_t * len)1023 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
1024 {
1025 struct eap_pwd_data *data = priv;
1026 u8 *key;
1027
1028 if (data->state != SUCCESS)
1029 return NULL;
1030
1031 key = os_malloc(EAP_MSK_LEN);
1032 if (key == NULL)
1033 return NULL;
1034
1035 os_memcpy(key, data->msk, EAP_MSK_LEN);
1036 *len = EAP_MSK_LEN;
1037
1038 return key;
1039 }
1040
1041
eap_pwd_get_emsk(struct eap_sm * sm,void * priv,size_t * len)1042 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1043 {
1044 struct eap_pwd_data *data = priv;
1045 u8 *key;
1046
1047 if (data->state != SUCCESS)
1048 return NULL;
1049
1050 key = os_malloc(EAP_EMSK_LEN);
1051 if (key == NULL)
1052 return NULL;
1053
1054 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1055 *len = EAP_EMSK_LEN;
1056
1057 return key;
1058 }
1059
1060
eap_pwd_is_success(struct eap_sm * sm,void * priv)1061 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1062 {
1063 struct eap_pwd_data *data = priv;
1064 return data->state == SUCCESS;
1065 }
1066
1067
eap_pwd_is_done(struct eap_sm * sm,void * priv)1068 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1069 {
1070 struct eap_pwd_data *data = priv;
1071 return (data->state == SUCCESS) || (data->state == FAILURE);
1072 }
1073
1074
eap_pwd_get_session_id(struct eap_sm * sm,void * priv,size_t * len)1075 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1076 {
1077 struct eap_pwd_data *data = priv;
1078 u8 *id;
1079
1080 if (data->state != SUCCESS)
1081 return NULL;
1082
1083 id = os_malloc(1 + SHA256_MAC_LEN);
1084 if (id == NULL)
1085 return NULL;
1086
1087 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
1088 *len = 1 + SHA256_MAC_LEN;
1089
1090 return id;
1091 }
1092
1093
eap_server_pwd_register(void)1094 int eap_server_pwd_register(void)
1095 {
1096 struct eap_method *eap;
1097 int ret;
1098 struct timeval tp;
1099 struct timezone tz;
1100 u32 sr;
1101
1102 sr = 0xdeaddada;
1103 (void) gettimeofday(&tp, &tz);
1104 sr ^= (tp.tv_sec ^ tp.tv_usec);
1105 srandom(sr);
1106
1107 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1108 EAP_VENDOR_IETF, EAP_TYPE_PWD,
1109 "PWD");
1110 if (eap == NULL)
1111 return -1;
1112
1113 eap->init = eap_pwd_init;
1114 eap->reset = eap_pwd_reset;
1115 eap->buildReq = eap_pwd_build_req;
1116 eap->check = eap_pwd_check;
1117 eap->process = eap_pwd_process;
1118 eap->isDone = eap_pwd_is_done;
1119 eap->getKey = eap_pwd_getkey;
1120 eap->get_emsk = eap_pwd_get_emsk;
1121 eap->isSuccess = eap_pwd_is_success;
1122 eap->getSessionId = eap_pwd_get_session_id;
1123
1124 ret = eap_server_method_register(eap);
1125 if (ret)
1126 eap_server_method_free(eap);
1127 return ret;
1128 }
1129
1130