Line data Source code
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 :
17 : struct 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 : u8 session_id[1 + SHA256_MAC_LEN];
49 :
50 : BN_CTX *bnctx;
51 : };
52 :
53 :
54 36 : static const char * eap_pwd_state_txt(int state)
55 : {
56 36 : switch (state) {
57 : case PWD_ID_Req:
58 6 : return "PWD-ID-Req";
59 : case PWD_Commit_Req:
60 12 : return "PWD-Commit-Req";
61 : case PWD_Confirm_Req:
62 12 : return "PWD-Confirm-Req";
63 : case SUCCESS:
64 6 : return "SUCCESS";
65 : case FAILURE:
66 0 : return "FAILURE";
67 : default:
68 0 : return "PWD-Unk";
69 : }
70 : }
71 :
72 :
73 18 : static void eap_pwd_state(struct eap_pwd_data *data, int state)
74 : {
75 36 : wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
76 18 : eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
77 18 : data->state = state;
78 18 : }
79 :
80 :
81 7 : static void * eap_pwd_init(struct eap_sm *sm)
82 : {
83 : struct eap_pwd_data *data;
84 :
85 14 : if (sm->user == NULL || sm->user->password == NULL ||
86 7 : sm->user->password_len == 0) {
87 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
88 : "configured");
89 0 : return NULL;
90 : }
91 :
92 7 : data = os_zalloc(sizeof(*data));
93 7 : if (data == NULL)
94 0 : return NULL;
95 :
96 7 : data->group_num = sm->pwd_group;
97 7 : wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
98 7 : data->group_num);
99 7 : data->state = PWD_ID_Req;
100 :
101 7 : data->id_server = (u8 *) os_strdup("server");
102 7 : if (data->id_server)
103 7 : data->id_server_len = os_strlen((char *) data->id_server);
104 :
105 7 : data->password = os_malloc(sm->user->password_len);
106 7 : if (data->password == NULL) {
107 0 : wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
108 : "fail");
109 0 : os_free(data->id_server);
110 0 : os_free(data);
111 0 : return NULL;
112 : }
113 7 : data->password_len = sm->user->password_len;
114 7 : os_memcpy(data->password, sm->user->password, data->password_len);
115 :
116 7 : data->bnctx = BN_CTX_new();
117 7 : if (data->bnctx == NULL) {
118 0 : wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
119 0 : os_free(data->password);
120 0 : os_free(data->id_server);
121 0 : os_free(data);
122 0 : return NULL;
123 : }
124 :
125 7 : data->in_frag_pos = data->out_frag_pos = 0;
126 7 : data->inbuf = data->outbuf = NULL;
127 : /* use default MTU from RFC 5931 if not configured otherwise */
128 7 : data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
129 :
130 7 : return data;
131 : }
132 :
133 :
134 7 : static void eap_pwd_reset(struct eap_sm *sm, void *priv)
135 : {
136 7 : struct eap_pwd_data *data = priv;
137 :
138 7 : BN_free(data->private_value);
139 7 : BN_free(data->peer_scalar);
140 7 : BN_free(data->my_scalar);
141 7 : BN_free(data->k);
142 7 : BN_CTX_free(data->bnctx);
143 7 : EC_POINT_free(data->my_element);
144 7 : EC_POINT_free(data->peer_element);
145 7 : os_free(data->id_peer);
146 7 : os_free(data->id_server);
147 7 : os_free(data->password);
148 7 : if (data->grp) {
149 6 : EC_GROUP_free(data->grp->group);
150 6 : EC_POINT_free(data->grp->pwe);
151 6 : BN_free(data->grp->order);
152 6 : BN_free(data->grp->prime);
153 6 : os_free(data->grp);
154 : }
155 7 : wpabuf_free(data->inbuf);
156 7 : wpabuf_free(data->outbuf);
157 7 : os_free(data);
158 7 : }
159 :
160 :
161 7 : static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
162 : u8 id)
163 : {
164 7 : wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
165 : /*
166 : * if we're fragmenting then we already have an id request, just return
167 : */
168 7 : if (data->out_frag_pos)
169 0 : return;
170 :
171 7 : data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
172 7 : data->id_server_len);
173 7 : if (data->outbuf == NULL) {
174 0 : eap_pwd_state(data, FAILURE);
175 0 : return;
176 : }
177 :
178 : /* an lfsr is good enough to generate unpredictable tokens */
179 7 : data->token = os_random();
180 7 : wpabuf_put_be16(data->outbuf, data->group_num);
181 7 : wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
182 7 : wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
183 7 : wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
184 7 : wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
185 7 : wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
186 : }
187 :
188 :
189 8 : static void eap_pwd_build_commit_req(struct eap_sm *sm,
190 : struct eap_pwd_data *data, u8 id)
191 : {
192 8 : BIGNUM *mask = NULL, *x = NULL, *y = NULL;
193 8 : u8 *scalar = NULL, *element = NULL;
194 : u16 offset;
195 :
196 8 : wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
197 : /*
198 : * if we're fragmenting then we already have an commit request, just
199 : * return
200 : */
201 8 : if (data->out_frag_pos)
202 10 : return;
203 :
204 12 : if (((data->private_value = BN_new()) == NULL) ||
205 12 : ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
206 12 : ((data->my_scalar = BN_new()) == NULL) ||
207 : ((mask = BN_new()) == NULL)) {
208 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
209 : "fail");
210 0 : goto fin;
211 : }
212 :
213 6 : BN_rand_range(data->private_value, data->grp->order);
214 6 : BN_rand_range(mask, data->grp->order);
215 6 : BN_add(data->my_scalar, data->private_value, mask);
216 6 : BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
217 : data->bnctx);
218 :
219 12 : if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
220 6 : data->grp->pwe, mask, data->bnctx)) {
221 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
222 : "fail");
223 0 : eap_pwd_state(data, FAILURE);
224 0 : goto fin;
225 : }
226 :
227 6 : if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
228 : {
229 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
230 : "fail");
231 0 : goto fin;
232 : }
233 6 : BN_free(mask);
234 :
235 6 : if (((x = BN_new()) == NULL) ||
236 : ((y = BN_new()) == NULL)) {
237 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
238 : "fail");
239 0 : goto fin;
240 : }
241 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
242 6 : data->my_element, x, y,
243 : data->bnctx)) {
244 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
245 : "fail");
246 0 : goto fin;
247 : }
248 :
249 12 : if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
250 6 : ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
251 : NULL)) {
252 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
253 0 : goto fin;
254 : }
255 :
256 : /*
257 : * bignums occupy as little memory as possible so one that is
258 : * sufficiently smaller than the prime or order might need pre-pending
259 : * with zeros.
260 : */
261 6 : os_memset(scalar, 0, BN_num_bytes(data->grp->order));
262 6 : os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
263 12 : offset = BN_num_bytes(data->grp->order) -
264 6 : BN_num_bytes(data->my_scalar);
265 6 : BN_bn2bin(data->my_scalar, scalar + offset);
266 :
267 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
268 6 : BN_bn2bin(x, element + offset);
269 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
270 6 : BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
271 :
272 12 : data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
273 6 : BN_num_bytes(data->grp->order));
274 6 : if (data->outbuf == NULL)
275 0 : goto fin;
276 :
277 : /* We send the element as (x,y) followed by the scalar */
278 6 : wpabuf_put_data(data->outbuf, element,
279 6 : 2 * BN_num_bytes(data->grp->prime));
280 6 : wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
281 :
282 : fin:
283 6 : os_free(scalar);
284 6 : os_free(element);
285 6 : BN_free(x);
286 6 : BN_free(y);
287 6 : if (data->outbuf == NULL)
288 0 : eap_pwd_state(data, FAILURE);
289 : }
290 :
291 :
292 6 : static void eap_pwd_build_confirm_req(struct eap_sm *sm,
293 : struct eap_pwd_data *data, u8 id)
294 : {
295 6 : BIGNUM *x = NULL, *y = NULL;
296 : struct crypto_hash *hash;
297 6 : u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
298 : u16 grp;
299 : int offset;
300 :
301 6 : wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
302 : /*
303 : * if we're fragmenting then we already have an confirm request, just
304 : * return
305 : */
306 6 : if (data->out_frag_pos)
307 6 : return;
308 :
309 : /* Each component of the cruft will be at most as big as the prime */
310 6 : if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
311 6 : ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
312 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
313 : "fail");
314 0 : goto fin;
315 : }
316 :
317 : /*
318 : * commit is H(k | server_element | server_scalar | peer_element |
319 : * peer_scalar | ciphersuite)
320 : */
321 6 : hash = eap_pwd_h_init();
322 6 : if (hash == NULL)
323 0 : goto fin;
324 :
325 : /*
326 : * Zero the memory each time because this is mod prime math and some
327 : * value may start with a few zeros and the previous one did not.
328 : *
329 : * First is k
330 : */
331 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
332 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
333 6 : BN_bn2bin(data->k, cruft + offset);
334 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
335 :
336 : /* server element: x, y */
337 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
338 6 : data->my_element, x, y,
339 : data->bnctx)) {
340 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
341 : "assignment fail");
342 0 : goto fin;
343 : }
344 :
345 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
346 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
347 6 : BN_bn2bin(x, cruft + offset);
348 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
349 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
350 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
351 6 : BN_bn2bin(y, cruft + offset);
352 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
353 :
354 : /* server scalar */
355 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
356 12 : offset = BN_num_bytes(data->grp->order) -
357 6 : BN_num_bytes(data->my_scalar);
358 6 : BN_bn2bin(data->my_scalar, cruft + offset);
359 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
360 :
361 : /* peer element: x, y */
362 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
363 6 : data->peer_element, x, y,
364 : data->bnctx)) {
365 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
366 : "assignment fail");
367 0 : goto fin;
368 : }
369 :
370 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
371 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
372 6 : BN_bn2bin(x, cruft + offset);
373 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
374 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
375 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
376 6 : BN_bn2bin(y, cruft + offset);
377 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
378 :
379 : /* peer scalar */
380 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
381 12 : offset = BN_num_bytes(data->grp->order) -
382 6 : BN_num_bytes(data->peer_scalar);
383 6 : BN_bn2bin(data->peer_scalar, cruft + offset);
384 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
385 :
386 : /* ciphersuite */
387 6 : grp = htons(data->group_num);
388 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
389 6 : ptr = cruft;
390 6 : os_memcpy(ptr, &grp, sizeof(u16));
391 6 : ptr += sizeof(u16);
392 6 : *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
393 6 : ptr += sizeof(u8);
394 6 : *ptr = EAP_PWD_DEFAULT_PRF;
395 6 : ptr += sizeof(u8);
396 6 : eap_pwd_h_update(hash, cruft, ptr - cruft);
397 :
398 : /* all done with the random function */
399 6 : eap_pwd_h_final(hash, conf);
400 6 : os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
401 :
402 6 : data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
403 6 : if (data->outbuf == NULL)
404 0 : goto fin;
405 :
406 6 : wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
407 :
408 : fin:
409 6 : os_free(cruft);
410 6 : BN_free(x);
411 6 : BN_free(y);
412 6 : if (data->outbuf == NULL)
413 0 : eap_pwd_state(data, FAILURE);
414 : }
415 :
416 :
417 : static struct wpabuf *
418 21 : eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
419 : {
420 21 : struct eap_pwd_data *data = priv;
421 : struct wpabuf *req;
422 : u8 lm_exch;
423 : const u8 *buf;
424 21 : u16 totlen = 0;
425 : size_t len;
426 :
427 : /*
428 : * if we're buffering response fragments then just ACK
429 : */
430 21 : if (data->in_frag_pos) {
431 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
432 0 : req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
433 : EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
434 0 : if (req == NULL) {
435 0 : eap_pwd_state(data, FAILURE);
436 0 : return NULL;
437 : }
438 0 : switch (data->state) {
439 : case PWD_ID_Req:
440 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
441 0 : break;
442 : case PWD_Commit_Req:
443 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
444 0 : break;
445 : case PWD_Confirm_Req:
446 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
447 0 : break;
448 : default:
449 0 : eap_pwd_state(data, FAILURE); /* just to be sure */
450 0 : wpabuf_free(req);
451 0 : return NULL;
452 : }
453 0 : return req;
454 : }
455 :
456 : /*
457 : * build the data portion of a request
458 : */
459 21 : switch (data->state) {
460 : case PWD_ID_Req:
461 7 : eap_pwd_build_id_req(sm, data, id);
462 7 : lm_exch = EAP_PWD_OPCODE_ID_EXCH;
463 7 : break;
464 : case PWD_Commit_Req:
465 8 : eap_pwd_build_commit_req(sm, data, id);
466 8 : lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
467 8 : break;
468 : case PWD_Confirm_Req:
469 6 : eap_pwd_build_confirm_req(sm, data, id);
470 6 : lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
471 6 : break;
472 : default:
473 0 : wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
474 0 : data->state);
475 0 : eap_pwd_state(data, FAILURE);
476 0 : lm_exch = 0; /* hush now, sweet compiler */
477 0 : break;
478 : }
479 :
480 21 : if (data->state == FAILURE)
481 0 : return NULL;
482 :
483 : /*
484 : * determine whether that data needs to be fragmented
485 : */
486 21 : len = wpabuf_len(data->outbuf) - data->out_frag_pos;
487 21 : if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
488 2 : len = data->mtu - EAP_PWD_HDR_SIZE;
489 2 : EAP_PWD_SET_MORE_BIT(lm_exch);
490 : /*
491 : * if this is the first fragment, need to set the M bit
492 : * and add the total length to the eap_pwd_hdr
493 : */
494 2 : if (data->out_frag_pos == 0) {
495 1 : EAP_PWD_SET_LENGTH_BIT(lm_exch);
496 1 : totlen = wpabuf_len(data->outbuf) +
497 : EAP_PWD_HDR_SIZE + sizeof(u16);
498 1 : len -= sizeof(u16);
499 1 : wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
500 : "total length = %d", totlen);
501 : }
502 2 : wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
503 : (int) len);
504 : }
505 :
506 : /*
507 : * alloc an eap request and populate it with the data
508 : */
509 42 : req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
510 21 : EAP_PWD_HDR_SIZE + len +
511 21 : (totlen ? sizeof(u16) : 0),
512 : EAP_CODE_REQUEST, id);
513 21 : if (req == NULL) {
514 0 : eap_pwd_state(data, FAILURE);
515 0 : return NULL;
516 : }
517 :
518 21 : wpabuf_put_u8(req, lm_exch);
519 21 : if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
520 1 : wpabuf_put_be16(req, totlen);
521 :
522 21 : buf = wpabuf_head_u8(data->outbuf);
523 21 : wpabuf_put_data(req, buf + data->out_frag_pos, len);
524 21 : data->out_frag_pos += len;
525 : /*
526 : * either not fragged or last fragment, either way free up the data
527 : */
528 21 : if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
529 19 : wpabuf_free(data->outbuf);
530 19 : data->outbuf = NULL;
531 19 : data->out_frag_pos = 0;
532 : }
533 :
534 21 : return req;
535 : }
536 :
537 :
538 20 : static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
539 : struct wpabuf *respData)
540 : {
541 20 : struct eap_pwd_data *data = priv;
542 : const u8 *pos;
543 : size_t len;
544 :
545 20 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
546 20 : if (pos == NULL || len < 1) {
547 0 : wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
548 0 : return TRUE;
549 : }
550 :
551 40 : wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
552 20 : EAP_PWD_GET_EXCHANGE(*pos), (int) len);
553 :
554 26 : if (data->state == PWD_ID_Req &&
555 6 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
556 6 : return FALSE;
557 :
558 22 : if (data->state == PWD_Commit_Req &&
559 8 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
560 8 : return FALSE;
561 :
562 12 : if (data->state == PWD_Confirm_Req &&
563 6 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
564 6 : return FALSE;
565 :
566 0 : wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
567 0 : *pos, data->state);
568 :
569 0 : return TRUE;
570 : }
571 :
572 :
573 6 : static void eap_pwd_process_id_resp(struct eap_sm *sm,
574 : struct eap_pwd_data *data,
575 : const u8 *payload, size_t payload_len)
576 : {
577 : struct eap_pwd_id *id;
578 :
579 6 : if (payload_len < sizeof(struct eap_pwd_id)) {
580 0 : wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
581 0 : return;
582 : }
583 :
584 6 : id = (struct eap_pwd_id *) payload;
585 12 : if ((data->group_num != be_to_host16(id->group_num)) ||
586 12 : (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
587 12 : (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
588 6 : (id->prf != EAP_PWD_DEFAULT_PRF)) {
589 0 : wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
590 0 : eap_pwd_state(data, FAILURE);
591 0 : return;
592 : }
593 6 : data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
594 6 : if (data->id_peer == NULL) {
595 0 : wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
596 0 : return;
597 : }
598 6 : data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
599 6 : os_memcpy(data->id_peer, id->identity, data->id_peer_len);
600 12 : wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
601 6 : data->id_peer, data->id_peer_len);
602 :
603 6 : data->grp = os_zalloc(sizeof(EAP_PWD_group));
604 6 : if (data->grp == NULL) {
605 0 : wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
606 : "group");
607 0 : return;
608 : }
609 18 : if (compute_password_element(data->grp, data->group_num,
610 6 : data->password, data->password_len,
611 6 : data->id_server, data->id_server_len,
612 6 : data->id_peer, data->id_peer_len,
613 6 : (u8 *) &data->token)) {
614 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
615 : "PWE");
616 0 : return;
617 : }
618 6 : wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
619 6 : BN_num_bits(data->grp->prime));
620 :
621 6 : eap_pwd_state(data, PWD_Commit_Req);
622 : }
623 :
624 :
625 : static void
626 6 : eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
627 : const u8 *payload, size_t payload_len)
628 : {
629 : u8 *ptr;
630 6 : BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
631 6 : EC_POINT *K = NULL, *point = NULL;
632 6 : int res = 0;
633 :
634 6 : wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
635 :
636 12 : if (((data->peer_scalar = BN_new()) == NULL) ||
637 12 : ((data->k = BN_new()) == NULL) ||
638 6 : ((cofactor = BN_new()) == NULL) ||
639 6 : ((x = BN_new()) == NULL) ||
640 6 : ((y = BN_new()) == NULL) ||
641 12 : ((point = EC_POINT_new(data->grp->group)) == NULL) ||
642 12 : ((K = EC_POINT_new(data->grp->group)) == NULL) ||
643 6 : ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
644 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
645 : "fail");
646 0 : goto fin;
647 : }
648 :
649 6 : if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
650 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
651 : "cofactor for curve");
652 0 : goto fin;
653 : }
654 :
655 : /* element, x then y, followed by scalar */
656 6 : ptr = (u8 *) payload;
657 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
658 6 : ptr += BN_num_bytes(data->grp->prime);
659 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
660 6 : ptr += BN_num_bytes(data->grp->prime);
661 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
662 6 : if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
663 : data->peer_element, x, y,
664 : data->bnctx)) {
665 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
666 : "fail");
667 0 : goto fin;
668 : }
669 :
670 : /* check to ensure peer's element is not in a small sub-group */
671 6 : if (BN_cmp(cofactor, BN_value_one())) {
672 0 : if (!EC_POINT_mul(data->grp->group, point, NULL,
673 0 : data->peer_element, cofactor, NULL)) {
674 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
675 : "multiply peer element by order");
676 0 : goto fin;
677 : }
678 0 : if (EC_POINT_is_at_infinity(data->grp->group, point)) {
679 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
680 : "is at infinity!\n");
681 0 : goto fin;
682 : }
683 : }
684 :
685 : /* compute the shared key, k */
686 12 : if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
687 12 : data->peer_scalar, data->bnctx)) ||
688 6 : (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
689 6 : data->bnctx)) ||
690 6 : (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
691 : data->bnctx))) {
692 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
693 : "fail");
694 0 : goto fin;
695 : }
696 :
697 : /* ensure that the shared key isn't in a small sub-group */
698 6 : if (BN_cmp(cofactor, BN_value_one())) {
699 0 : if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
700 : NULL)) {
701 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
702 : "multiply shared key point by order!\n");
703 0 : goto fin;
704 : }
705 : }
706 :
707 : /*
708 : * This check is strictly speaking just for the case above where
709 : * co-factor > 1 but it was suggested that even though this is probably
710 : * never going to happen it is a simple and safe check "just to be
711 : * sure" so let's be safe.
712 : */
713 6 : if (EC_POINT_is_at_infinity(data->grp->group, K)) {
714 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
715 : "at infinity");
716 0 : goto fin;
717 : }
718 6 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
719 : NULL, data->bnctx)) {
720 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
721 : "shared secret from secret point");
722 0 : goto fin;
723 : }
724 6 : res = 1;
725 :
726 : fin:
727 6 : EC_POINT_free(K);
728 6 : EC_POINT_free(point);
729 6 : BN_free(cofactor);
730 6 : BN_free(x);
731 6 : BN_free(y);
732 :
733 6 : if (res)
734 6 : eap_pwd_state(data, PWD_Confirm_Req);
735 : else
736 0 : eap_pwd_state(data, FAILURE);
737 6 : }
738 :
739 :
740 : static void
741 6 : eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
742 : const u8 *payload, size_t payload_len)
743 : {
744 6 : BIGNUM *x = NULL, *y = NULL;
745 : struct crypto_hash *hash;
746 : u32 cs;
747 : u16 grp;
748 6 : u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
749 : int offset;
750 :
751 : /* build up the ciphersuite: group | random_function | prf */
752 6 : grp = htons(data->group_num);
753 6 : ptr = (u8 *) &cs;
754 6 : os_memcpy(ptr, &grp, sizeof(u16));
755 6 : ptr += sizeof(u16);
756 6 : *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
757 6 : ptr += sizeof(u8);
758 6 : *ptr = EAP_PWD_DEFAULT_PRF;
759 :
760 : /* each component of the cruft will be at most as big as the prime */
761 6 : if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
762 6 : ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
763 0 : wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
764 0 : goto fin;
765 : }
766 :
767 : /*
768 : * commit is H(k | peer_element | peer_scalar | server_element |
769 : * server_scalar | ciphersuite)
770 : */
771 6 : hash = eap_pwd_h_init();
772 6 : if (hash == NULL)
773 0 : goto fin;
774 :
775 : /* k */
776 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
777 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
778 6 : BN_bn2bin(data->k, cruft + offset);
779 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
780 :
781 : /* peer element: x, y */
782 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
783 6 : data->peer_element, x, y,
784 : data->bnctx)) {
785 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
786 : "assignment fail");
787 0 : goto fin;
788 : }
789 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
790 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
791 6 : BN_bn2bin(x, cruft + offset);
792 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
793 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
794 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
795 6 : BN_bn2bin(y, cruft + offset);
796 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
797 :
798 : /* peer scalar */
799 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
800 12 : offset = BN_num_bytes(data->grp->order) -
801 6 : BN_num_bytes(data->peer_scalar);
802 6 : BN_bn2bin(data->peer_scalar, cruft + offset);
803 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
804 :
805 : /* server element: x, y */
806 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
807 6 : data->my_element, x, y,
808 : data->bnctx)) {
809 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
810 : "assignment fail");
811 0 : goto fin;
812 : }
813 :
814 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
815 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
816 6 : BN_bn2bin(x, cruft + offset);
817 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
818 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
819 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
820 6 : BN_bn2bin(y, cruft + offset);
821 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
822 :
823 : /* server scalar */
824 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
825 12 : offset = BN_num_bytes(data->grp->order) -
826 6 : BN_num_bytes(data->my_scalar);
827 6 : BN_bn2bin(data->my_scalar, cruft + offset);
828 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
829 :
830 : /* ciphersuite */
831 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
832 6 : eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
833 :
834 : /* all done */
835 6 : eap_pwd_h_final(hash, conf);
836 :
837 6 : ptr = (u8 *) payload;
838 6 : if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) {
839 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
840 : "verify");
841 0 : goto fin;
842 : }
843 :
844 6 : wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
845 6 : if (compute_keys(data->grp, data->bnctx, data->k,
846 : data->peer_scalar, data->my_scalar, conf,
847 6 : data->my_confirm, &cs, data->msk, data->emsk,
848 6 : data->session_id) < 0)
849 0 : eap_pwd_state(data, FAILURE);
850 : else
851 6 : eap_pwd_state(data, SUCCESS);
852 :
853 : fin:
854 6 : os_free(cruft);
855 6 : BN_free(x);
856 6 : BN_free(y);
857 6 : }
858 :
859 :
860 20 : static void eap_pwd_process(struct eap_sm *sm, void *priv,
861 : struct wpabuf *respData)
862 : {
863 20 : struct eap_pwd_data *data = priv;
864 : const u8 *pos;
865 : size_t len;
866 : u8 lm_exch;
867 : u16 tot_len;
868 :
869 20 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
870 20 : if ((pos == NULL) || (len < 1)) {
871 0 : wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
872 : (pos == NULL) ? "is NULL" : "is not NULL",
873 : (int) len);
874 0 : return;
875 : }
876 :
877 20 : lm_exch = *pos;
878 20 : pos++; /* skip over the bits and the exch */
879 20 : len--;
880 :
881 : /*
882 : * if we're fragmenting then this should be an ACK with no data,
883 : * just return and continue fragmenting in the "build" section above
884 : */
885 20 : if (data->out_frag_pos) {
886 2 : if (len > 1)
887 0 : wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
888 : "Fragmenting but not an ACK");
889 : else
890 2 : wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
891 : "peer");
892 2 : return;
893 : }
894 : /*
895 : * if we're receiving fragmented packets then we need to buffer...
896 : *
897 : * the first fragment has a total length
898 : */
899 18 : if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
900 0 : tot_len = WPA_GET_BE16(pos);
901 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
902 : "length = %d", tot_len);
903 0 : data->inbuf = wpabuf_alloc(tot_len);
904 0 : if (data->inbuf == NULL) {
905 0 : wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
906 : "buffer fragments!");
907 0 : return;
908 : }
909 0 : pos += sizeof(u16);
910 0 : len -= sizeof(u16);
911 : }
912 : /*
913 : * the first and all intermediate fragments have the M bit set
914 : */
915 18 : if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
916 0 : if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
917 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
918 : "attack detected! (%d+%d > %d)",
919 0 : (int) data->in_frag_pos, (int) len,
920 0 : (int) wpabuf_size(data->inbuf));
921 0 : eap_pwd_state(data, FAILURE);
922 0 : return;
923 : }
924 0 : wpabuf_put_data(data->inbuf, pos, len);
925 0 : data->in_frag_pos += len;
926 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
927 : (int) len);
928 0 : return;
929 : }
930 : /*
931 : * last fragment won't have the M bit set (but we're obviously
932 : * buffering fragments so that's how we know it's the last)
933 : */
934 18 : if (data->in_frag_pos) {
935 0 : wpabuf_put_data(data->inbuf, pos, len);
936 0 : data->in_frag_pos += len;
937 0 : pos = wpabuf_head_u8(data->inbuf);
938 0 : len = data->in_frag_pos;
939 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
940 : (int) len);
941 : }
942 18 : switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
943 : case EAP_PWD_OPCODE_ID_EXCH:
944 6 : eap_pwd_process_id_resp(sm, data, pos, len);
945 6 : break;
946 : case EAP_PWD_OPCODE_COMMIT_EXCH:
947 6 : eap_pwd_process_commit_resp(sm, data, pos, len);
948 6 : break;
949 : case EAP_PWD_OPCODE_CONFIRM_EXCH:
950 6 : eap_pwd_process_confirm_resp(sm, data, pos, len);
951 6 : break;
952 : }
953 : /*
954 : * if we had been buffering fragments, here's a great place
955 : * to clean up
956 : */
957 18 : if (data->in_frag_pos) {
958 0 : wpabuf_free(data->inbuf);
959 0 : data->inbuf = NULL;
960 0 : data->in_frag_pos = 0;
961 : }
962 : }
963 :
964 :
965 6 : static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
966 : {
967 6 : struct eap_pwd_data *data = priv;
968 : u8 *key;
969 :
970 6 : if (data->state != SUCCESS)
971 0 : return NULL;
972 :
973 6 : key = os_malloc(EAP_MSK_LEN);
974 6 : if (key == NULL)
975 0 : return NULL;
976 :
977 6 : os_memcpy(key, data->msk, EAP_MSK_LEN);
978 6 : *len = EAP_MSK_LEN;
979 :
980 6 : return key;
981 : }
982 :
983 :
984 0 : static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
985 : {
986 0 : struct eap_pwd_data *data = priv;
987 : u8 *key;
988 :
989 0 : if (data->state != SUCCESS)
990 0 : return NULL;
991 :
992 0 : key = os_malloc(EAP_EMSK_LEN);
993 0 : if (key == NULL)
994 0 : return NULL;
995 :
996 0 : os_memcpy(key, data->emsk, EAP_EMSK_LEN);
997 0 : *len = EAP_EMSK_LEN;
998 :
999 0 : return key;
1000 : }
1001 :
1002 :
1003 6 : static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1004 : {
1005 6 : struct eap_pwd_data *data = priv;
1006 6 : return data->state == SUCCESS;
1007 : }
1008 :
1009 :
1010 20 : static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1011 : {
1012 20 : struct eap_pwd_data *data = priv;
1013 20 : return (data->state == SUCCESS) || (data->state == FAILURE);
1014 : }
1015 :
1016 :
1017 1 : int eap_server_pwd_register(void)
1018 : {
1019 : struct eap_method *eap;
1020 : int ret;
1021 : struct timeval tp;
1022 : struct timezone tz;
1023 : u32 sr;
1024 :
1025 1 : EVP_add_digest(EVP_sha256());
1026 :
1027 1 : sr = 0xdeaddada;
1028 1 : (void) gettimeofday(&tp, &tz);
1029 1 : sr ^= (tp.tv_sec ^ tp.tv_usec);
1030 1 : srandom(sr);
1031 :
1032 1 : eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1033 : EAP_VENDOR_IETF, EAP_TYPE_PWD,
1034 : "PWD");
1035 1 : if (eap == NULL)
1036 0 : return -1;
1037 :
1038 1 : eap->init = eap_pwd_init;
1039 1 : eap->reset = eap_pwd_reset;
1040 1 : eap->buildReq = eap_pwd_build_req;
1041 1 : eap->check = eap_pwd_check;
1042 1 : eap->process = eap_pwd_process;
1043 1 : eap->isDone = eap_pwd_is_done;
1044 1 : eap->getKey = eap_pwd_getkey;
1045 1 : eap->get_emsk = eap_pwd_get_emsk;
1046 1 : eap->isSuccess = eap_pwd_is_success;
1047 :
1048 1 : ret = eap_server_method_register(eap);
1049 1 : if (ret)
1050 0 : eap_server_method_free(eap);
1051 1 : return ret;
1052 : }
1053 :
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