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 : bin_clear_free(data->id_server, data->id_server_len);
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 : bin_clear_free(data->password, data->password_len);
120 0 : bin_clear_free(data->id_server, data->id_server_len);
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_clear_free(data->private_value);
139 7 : BN_clear_free(data->peer_scalar);
140 7 : BN_clear_free(data->my_scalar);
141 7 : BN_clear_free(data->k);
142 7 : BN_CTX_free(data->bnctx);
143 7 : EC_POINT_clear_free(data->my_element);
144 7 : EC_POINT_clear_free(data->peer_element);
145 7 : bin_clear_free(data->id_peer, data->id_peer_len);
146 7 : bin_clear_free(data->id_server, data->id_server_len);
147 7 : bin_clear_free(data->password, data->password_len);
148 7 : if (data->grp) {
149 6 : EC_GROUP_free(data->grp->group);
150 6 : EC_POINT_clear_free(data->grp->pwe);
151 6 : BN_clear_free(data->grp->order);
152 6 : BN_clear_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 : bin_clear_free(data, sizeof(*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 12 : if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
214 12 : BN_rand_range(mask, data->grp->order) != 1 ||
215 12 : BN_add(data->my_scalar, data->private_value, mask) != 1 ||
216 6 : BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
217 : data->bnctx) != 1) {
218 0 : wpa_printf(MSG_INFO,
219 : "EAP-pwd (server): unable to get randomness");
220 0 : goto fin;
221 : }
222 :
223 12 : if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
224 6 : data->grp->pwe, mask, data->bnctx)) {
225 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
226 : "fail");
227 0 : eap_pwd_state(data, FAILURE);
228 0 : goto fin;
229 : }
230 :
231 6 : if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
232 : {
233 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
234 : "fail");
235 0 : goto fin;
236 : }
237 6 : BN_clear_free(mask);
238 :
239 6 : if (((x = BN_new()) == NULL) ||
240 : ((y = BN_new()) == NULL)) {
241 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
242 : "fail");
243 0 : goto fin;
244 : }
245 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
246 6 : data->my_element, x, y,
247 : data->bnctx)) {
248 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
249 : "fail");
250 0 : goto fin;
251 : }
252 :
253 12 : if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
254 6 : ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
255 : NULL)) {
256 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
257 0 : goto fin;
258 : }
259 :
260 : /*
261 : * bignums occupy as little memory as possible so one that is
262 : * sufficiently smaller than the prime or order might need pre-pending
263 : * with zeros.
264 : */
265 6 : os_memset(scalar, 0, BN_num_bytes(data->grp->order));
266 6 : os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
267 12 : offset = BN_num_bytes(data->grp->order) -
268 6 : BN_num_bytes(data->my_scalar);
269 6 : BN_bn2bin(data->my_scalar, scalar + offset);
270 :
271 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
272 6 : BN_bn2bin(x, element + offset);
273 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
274 6 : BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
275 :
276 12 : data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
277 6 : BN_num_bytes(data->grp->order));
278 6 : if (data->outbuf == NULL)
279 0 : goto fin;
280 :
281 : /* We send the element as (x,y) followed by the scalar */
282 6 : wpabuf_put_data(data->outbuf, element,
283 6 : 2 * BN_num_bytes(data->grp->prime));
284 6 : wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
285 :
286 : fin:
287 6 : os_free(scalar);
288 6 : os_free(element);
289 6 : BN_clear_free(x);
290 6 : BN_clear_free(y);
291 6 : if (data->outbuf == NULL)
292 0 : eap_pwd_state(data, FAILURE);
293 : }
294 :
295 :
296 6 : static void eap_pwd_build_confirm_req(struct eap_sm *sm,
297 : struct eap_pwd_data *data, u8 id)
298 : {
299 6 : BIGNUM *x = NULL, *y = NULL;
300 : struct crypto_hash *hash;
301 6 : u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
302 : u16 grp;
303 : int offset;
304 :
305 6 : wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
306 : /*
307 : * if we're fragmenting then we already have an confirm request, just
308 : * return
309 : */
310 6 : if (data->out_frag_pos)
311 6 : return;
312 :
313 : /* Each component of the cruft will be at most as big as the prime */
314 6 : if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
315 6 : ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
316 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
317 : "fail");
318 0 : goto fin;
319 : }
320 :
321 : /*
322 : * commit is H(k | server_element | server_scalar | peer_element |
323 : * peer_scalar | ciphersuite)
324 : */
325 6 : hash = eap_pwd_h_init();
326 6 : if (hash == NULL)
327 0 : goto fin;
328 :
329 : /*
330 : * Zero the memory each time because this is mod prime math and some
331 : * value may start with a few zeros and the previous one did not.
332 : *
333 : * First is k
334 : */
335 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
336 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
337 6 : BN_bn2bin(data->k, cruft + offset);
338 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
339 :
340 : /* server element: x, y */
341 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
342 6 : data->my_element, x, y,
343 : data->bnctx)) {
344 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
345 : "assignment fail");
346 0 : goto fin;
347 : }
348 :
349 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
350 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
351 6 : BN_bn2bin(x, cruft + offset);
352 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
353 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
354 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
355 6 : BN_bn2bin(y, cruft + offset);
356 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
357 :
358 : /* server scalar */
359 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
360 12 : offset = BN_num_bytes(data->grp->order) -
361 6 : BN_num_bytes(data->my_scalar);
362 6 : BN_bn2bin(data->my_scalar, cruft + offset);
363 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
364 :
365 : /* peer element: x, y */
366 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
367 6 : data->peer_element, x, y,
368 : data->bnctx)) {
369 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
370 : "assignment fail");
371 0 : goto fin;
372 : }
373 :
374 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
375 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
376 6 : BN_bn2bin(x, cruft + offset);
377 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
378 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
379 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
380 6 : BN_bn2bin(y, cruft + offset);
381 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
382 :
383 : /* peer scalar */
384 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
385 12 : offset = BN_num_bytes(data->grp->order) -
386 6 : BN_num_bytes(data->peer_scalar);
387 6 : BN_bn2bin(data->peer_scalar, cruft + offset);
388 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
389 :
390 : /* ciphersuite */
391 6 : grp = htons(data->group_num);
392 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
393 6 : ptr = cruft;
394 6 : os_memcpy(ptr, &grp, sizeof(u16));
395 6 : ptr += sizeof(u16);
396 6 : *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
397 6 : ptr += sizeof(u8);
398 6 : *ptr = EAP_PWD_DEFAULT_PRF;
399 6 : ptr += sizeof(u8);
400 6 : eap_pwd_h_update(hash, cruft, ptr - cruft);
401 :
402 : /* all done with the random function */
403 6 : eap_pwd_h_final(hash, conf);
404 6 : os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
405 :
406 6 : data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
407 6 : if (data->outbuf == NULL)
408 0 : goto fin;
409 :
410 6 : wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
411 :
412 : fin:
413 6 : bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
414 6 : BN_clear_free(x);
415 6 : BN_clear_free(y);
416 6 : if (data->outbuf == NULL)
417 0 : eap_pwd_state(data, FAILURE);
418 : }
419 :
420 :
421 : static struct wpabuf *
422 21 : eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
423 : {
424 21 : struct eap_pwd_data *data = priv;
425 : struct wpabuf *req;
426 : u8 lm_exch;
427 : const u8 *buf;
428 21 : u16 totlen = 0;
429 : size_t len;
430 :
431 : /*
432 : * if we're buffering response fragments then just ACK
433 : */
434 21 : if (data->in_frag_pos) {
435 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
436 0 : req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
437 : EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
438 0 : if (req == NULL) {
439 0 : eap_pwd_state(data, FAILURE);
440 0 : return NULL;
441 : }
442 0 : switch (data->state) {
443 : case PWD_ID_Req:
444 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
445 0 : break;
446 : case PWD_Commit_Req:
447 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
448 0 : break;
449 : case PWD_Confirm_Req:
450 0 : wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
451 0 : break;
452 : default:
453 0 : eap_pwd_state(data, FAILURE); /* just to be sure */
454 0 : wpabuf_free(req);
455 0 : return NULL;
456 : }
457 0 : return req;
458 : }
459 :
460 : /*
461 : * build the data portion of a request
462 : */
463 21 : switch (data->state) {
464 : case PWD_ID_Req:
465 7 : eap_pwd_build_id_req(sm, data, id);
466 7 : lm_exch = EAP_PWD_OPCODE_ID_EXCH;
467 7 : break;
468 : case PWD_Commit_Req:
469 8 : eap_pwd_build_commit_req(sm, data, id);
470 8 : lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
471 8 : break;
472 : case PWD_Confirm_Req:
473 6 : eap_pwd_build_confirm_req(sm, data, id);
474 6 : lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
475 6 : break;
476 : default:
477 0 : wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
478 0 : data->state);
479 0 : eap_pwd_state(data, FAILURE);
480 0 : lm_exch = 0; /* hush now, sweet compiler */
481 0 : break;
482 : }
483 :
484 21 : if (data->state == FAILURE)
485 0 : return NULL;
486 :
487 : /*
488 : * determine whether that data needs to be fragmented
489 : */
490 21 : len = wpabuf_len(data->outbuf) - data->out_frag_pos;
491 21 : if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
492 2 : len = data->mtu - EAP_PWD_HDR_SIZE;
493 2 : EAP_PWD_SET_MORE_BIT(lm_exch);
494 : /*
495 : * if this is the first fragment, need to set the M bit
496 : * and add the total length to the eap_pwd_hdr
497 : */
498 2 : if (data->out_frag_pos == 0) {
499 1 : EAP_PWD_SET_LENGTH_BIT(lm_exch);
500 1 : totlen = wpabuf_len(data->outbuf) +
501 : EAP_PWD_HDR_SIZE + sizeof(u16);
502 1 : len -= sizeof(u16);
503 1 : wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
504 : "total length = %d", totlen);
505 : }
506 2 : wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
507 : (int) len);
508 : }
509 :
510 : /*
511 : * alloc an eap request and populate it with the data
512 : */
513 42 : req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
514 21 : EAP_PWD_HDR_SIZE + len +
515 21 : (totlen ? sizeof(u16) : 0),
516 : EAP_CODE_REQUEST, id);
517 21 : if (req == NULL) {
518 0 : eap_pwd_state(data, FAILURE);
519 0 : return NULL;
520 : }
521 :
522 21 : wpabuf_put_u8(req, lm_exch);
523 21 : if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
524 1 : wpabuf_put_be16(req, totlen);
525 :
526 21 : buf = wpabuf_head_u8(data->outbuf);
527 21 : wpabuf_put_data(req, buf + data->out_frag_pos, len);
528 21 : data->out_frag_pos += len;
529 : /*
530 : * either not fragged or last fragment, either way free up the data
531 : */
532 21 : if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
533 19 : wpabuf_free(data->outbuf);
534 19 : data->outbuf = NULL;
535 19 : data->out_frag_pos = 0;
536 : }
537 :
538 21 : return req;
539 : }
540 :
541 :
542 20 : static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
543 : struct wpabuf *respData)
544 : {
545 20 : struct eap_pwd_data *data = priv;
546 : const u8 *pos;
547 : size_t len;
548 :
549 20 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
550 20 : if (pos == NULL || len < 1) {
551 0 : wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
552 0 : return TRUE;
553 : }
554 :
555 40 : wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
556 20 : EAP_PWD_GET_EXCHANGE(*pos), (int) len);
557 :
558 26 : if (data->state == PWD_ID_Req &&
559 6 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
560 6 : return FALSE;
561 :
562 22 : if (data->state == PWD_Commit_Req &&
563 8 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
564 8 : return FALSE;
565 :
566 12 : if (data->state == PWD_Confirm_Req &&
567 6 : ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
568 6 : return FALSE;
569 :
570 0 : wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
571 0 : *pos, data->state);
572 :
573 0 : return TRUE;
574 : }
575 :
576 :
577 6 : static void eap_pwd_process_id_resp(struct eap_sm *sm,
578 : struct eap_pwd_data *data,
579 : const u8 *payload, size_t payload_len)
580 : {
581 : struct eap_pwd_id *id;
582 :
583 6 : if (payload_len < sizeof(struct eap_pwd_id)) {
584 0 : wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
585 0 : return;
586 : }
587 :
588 6 : id = (struct eap_pwd_id *) payload;
589 12 : if ((data->group_num != be_to_host16(id->group_num)) ||
590 12 : (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
591 12 : (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
592 6 : (id->prf != EAP_PWD_DEFAULT_PRF)) {
593 0 : wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
594 0 : eap_pwd_state(data, FAILURE);
595 0 : return;
596 : }
597 6 : data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
598 6 : if (data->id_peer == NULL) {
599 0 : wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
600 0 : return;
601 : }
602 6 : data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
603 6 : os_memcpy(data->id_peer, id->identity, data->id_peer_len);
604 12 : wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
605 6 : data->id_peer, data->id_peer_len);
606 :
607 6 : data->grp = os_zalloc(sizeof(EAP_PWD_group));
608 6 : if (data->grp == NULL) {
609 0 : wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
610 : "group");
611 0 : return;
612 : }
613 18 : if (compute_password_element(data->grp, data->group_num,
614 6 : data->password, data->password_len,
615 6 : data->id_server, data->id_server_len,
616 6 : data->id_peer, data->id_peer_len,
617 6 : (u8 *) &data->token)) {
618 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
619 : "PWE");
620 0 : return;
621 : }
622 6 : wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
623 6 : BN_num_bits(data->grp->prime));
624 :
625 6 : eap_pwd_state(data, PWD_Commit_Req);
626 : }
627 :
628 :
629 : static void
630 6 : eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
631 : const u8 *payload, size_t payload_len)
632 : {
633 : u8 *ptr;
634 6 : BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
635 6 : EC_POINT *K = NULL, *point = NULL;
636 6 : int res = 0;
637 :
638 6 : wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
639 :
640 12 : if (((data->peer_scalar = BN_new()) == NULL) ||
641 12 : ((data->k = BN_new()) == NULL) ||
642 6 : ((cofactor = BN_new()) == NULL) ||
643 6 : ((x = BN_new()) == NULL) ||
644 6 : ((y = BN_new()) == NULL) ||
645 12 : ((point = EC_POINT_new(data->grp->group)) == NULL) ||
646 12 : ((K = EC_POINT_new(data->grp->group)) == NULL) ||
647 6 : ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
648 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
649 : "fail");
650 0 : goto fin;
651 : }
652 :
653 6 : if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
654 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
655 : "cofactor for curve");
656 0 : goto fin;
657 : }
658 :
659 : /* element, x then y, followed by scalar */
660 6 : ptr = (u8 *) payload;
661 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
662 6 : ptr += BN_num_bytes(data->grp->prime);
663 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
664 6 : ptr += BN_num_bytes(data->grp->prime);
665 6 : BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
666 6 : if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
667 : data->peer_element, x, y,
668 : data->bnctx)) {
669 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
670 : "fail");
671 0 : goto fin;
672 : }
673 :
674 : /* check to ensure peer's element is not in a small sub-group */
675 6 : if (BN_cmp(cofactor, BN_value_one())) {
676 0 : if (!EC_POINT_mul(data->grp->group, point, NULL,
677 0 : data->peer_element, cofactor, NULL)) {
678 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
679 : "multiply peer element by order");
680 0 : goto fin;
681 : }
682 0 : if (EC_POINT_is_at_infinity(data->grp->group, point)) {
683 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
684 : "is at infinity!\n");
685 0 : goto fin;
686 : }
687 : }
688 :
689 : /* compute the shared key, k */
690 12 : if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
691 12 : data->peer_scalar, data->bnctx)) ||
692 6 : (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
693 6 : data->bnctx)) ||
694 6 : (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
695 : data->bnctx))) {
696 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
697 : "fail");
698 0 : goto fin;
699 : }
700 :
701 : /* ensure that the shared key isn't in a small sub-group */
702 6 : if (BN_cmp(cofactor, BN_value_one())) {
703 0 : if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
704 : NULL)) {
705 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
706 : "multiply shared key point by order!\n");
707 0 : goto fin;
708 : }
709 : }
710 :
711 : /*
712 : * This check is strictly speaking just for the case above where
713 : * co-factor > 1 but it was suggested that even though this is probably
714 : * never going to happen it is a simple and safe check "just to be
715 : * sure" so let's be safe.
716 : */
717 6 : if (EC_POINT_is_at_infinity(data->grp->group, K)) {
718 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
719 : "at infinity");
720 0 : goto fin;
721 : }
722 6 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
723 : NULL, data->bnctx)) {
724 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
725 : "shared secret from secret point");
726 0 : goto fin;
727 : }
728 6 : res = 1;
729 :
730 : fin:
731 6 : EC_POINT_clear_free(K);
732 6 : EC_POINT_clear_free(point);
733 6 : BN_clear_free(cofactor);
734 6 : BN_clear_free(x);
735 6 : BN_clear_free(y);
736 :
737 6 : if (res)
738 6 : eap_pwd_state(data, PWD_Confirm_Req);
739 : else
740 0 : eap_pwd_state(data, FAILURE);
741 6 : }
742 :
743 :
744 : static void
745 6 : eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
746 : const u8 *payload, size_t payload_len)
747 : {
748 6 : BIGNUM *x = NULL, *y = NULL;
749 : struct crypto_hash *hash;
750 : u32 cs;
751 : u16 grp;
752 6 : u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
753 : int offset;
754 :
755 : /* build up the ciphersuite: group | random_function | prf */
756 6 : grp = htons(data->group_num);
757 6 : ptr = (u8 *) &cs;
758 6 : os_memcpy(ptr, &grp, sizeof(u16));
759 6 : ptr += sizeof(u16);
760 6 : *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
761 6 : ptr += sizeof(u8);
762 6 : *ptr = EAP_PWD_DEFAULT_PRF;
763 :
764 : /* each component of the cruft will be at most as big as the prime */
765 6 : if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
766 6 : ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
767 0 : wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
768 0 : goto fin;
769 : }
770 :
771 : /*
772 : * commit is H(k | peer_element | peer_scalar | server_element |
773 : * server_scalar | ciphersuite)
774 : */
775 6 : hash = eap_pwd_h_init();
776 6 : if (hash == NULL)
777 0 : goto fin;
778 :
779 : /* k */
780 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
781 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
782 6 : BN_bn2bin(data->k, cruft + offset);
783 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
784 :
785 : /* peer element: x, y */
786 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
787 6 : data->peer_element, x, y,
788 : data->bnctx)) {
789 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
790 : "assignment fail");
791 0 : goto fin;
792 : }
793 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
794 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
795 6 : BN_bn2bin(x, cruft + offset);
796 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
797 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
798 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
799 6 : BN_bn2bin(y, cruft + offset);
800 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
801 :
802 : /* peer scalar */
803 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
804 12 : offset = BN_num_bytes(data->grp->order) -
805 6 : BN_num_bytes(data->peer_scalar);
806 6 : BN_bn2bin(data->peer_scalar, cruft + offset);
807 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
808 :
809 : /* server element: x, y */
810 12 : if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
811 6 : data->my_element, x, y,
812 : data->bnctx)) {
813 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
814 : "assignment fail");
815 0 : goto fin;
816 : }
817 :
818 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
819 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
820 6 : BN_bn2bin(x, cruft + offset);
821 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
822 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
823 6 : offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
824 6 : BN_bn2bin(y, cruft + offset);
825 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
826 :
827 : /* server scalar */
828 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
829 12 : offset = BN_num_bytes(data->grp->order) -
830 6 : BN_num_bytes(data->my_scalar);
831 6 : BN_bn2bin(data->my_scalar, cruft + offset);
832 6 : eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
833 :
834 : /* ciphersuite */
835 6 : os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
836 6 : eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
837 :
838 : /* all done */
839 6 : eap_pwd_h_final(hash, conf);
840 :
841 6 : ptr = (u8 *) payload;
842 6 : if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
843 0 : wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
844 : "verify");
845 0 : goto fin;
846 : }
847 :
848 6 : wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
849 6 : if (compute_keys(data->grp, data->bnctx, data->k,
850 : data->peer_scalar, data->my_scalar, conf,
851 6 : data->my_confirm, &cs, data->msk, data->emsk,
852 6 : data->session_id) < 0)
853 0 : eap_pwd_state(data, FAILURE);
854 : else
855 6 : eap_pwd_state(data, SUCCESS);
856 :
857 : fin:
858 6 : bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
859 6 : BN_clear_free(x);
860 6 : BN_clear_free(y);
861 6 : }
862 :
863 :
864 20 : static void eap_pwd_process(struct eap_sm *sm, void *priv,
865 : struct wpabuf *respData)
866 : {
867 20 : struct eap_pwd_data *data = priv;
868 : const u8 *pos;
869 : size_t len;
870 : u8 lm_exch;
871 : u16 tot_len;
872 :
873 20 : pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
874 20 : if ((pos == NULL) || (len < 1)) {
875 0 : wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
876 : (pos == NULL) ? "is NULL" : "is not NULL",
877 : (int) len);
878 0 : return;
879 : }
880 :
881 20 : lm_exch = *pos;
882 20 : pos++; /* skip over the bits and the exch */
883 20 : len--;
884 :
885 : /*
886 : * if we're fragmenting then this should be an ACK with no data,
887 : * just return and continue fragmenting in the "build" section above
888 : */
889 20 : if (data->out_frag_pos) {
890 2 : if (len > 1)
891 0 : wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
892 : "Fragmenting but not an ACK");
893 : else
894 2 : wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
895 : "peer");
896 2 : return;
897 : }
898 : /*
899 : * if we're receiving fragmented packets then we need to buffer...
900 : *
901 : * the first fragment has a total length
902 : */
903 18 : if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
904 0 : tot_len = WPA_GET_BE16(pos);
905 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
906 : "length = %d", tot_len);
907 0 : if (tot_len > 15000)
908 0 : return;
909 0 : data->inbuf = wpabuf_alloc(tot_len);
910 0 : if (data->inbuf == NULL) {
911 0 : wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
912 : "buffer fragments!");
913 0 : return;
914 : }
915 0 : pos += sizeof(u16);
916 0 : len -= sizeof(u16);
917 : }
918 : /*
919 : * the first and all intermediate fragments have the M bit set
920 : */
921 18 : if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
922 0 : if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
923 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
924 : "attack detected! (%d+%d > %d)",
925 0 : (int) data->in_frag_pos, (int) len,
926 0 : (int) wpabuf_size(data->inbuf));
927 0 : eap_pwd_state(data, FAILURE);
928 0 : return;
929 : }
930 0 : wpabuf_put_data(data->inbuf, pos, len);
931 0 : data->in_frag_pos += len;
932 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
933 : (int) len);
934 0 : return;
935 : }
936 : /*
937 : * last fragment won't have the M bit set (but we're obviously
938 : * buffering fragments so that's how we know it's the last)
939 : */
940 18 : if (data->in_frag_pos) {
941 0 : wpabuf_put_data(data->inbuf, pos, len);
942 0 : data->in_frag_pos += len;
943 0 : pos = wpabuf_head_u8(data->inbuf);
944 0 : len = data->in_frag_pos;
945 0 : wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
946 : (int) len);
947 : }
948 18 : switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
949 : case EAP_PWD_OPCODE_ID_EXCH:
950 6 : eap_pwd_process_id_resp(sm, data, pos, len);
951 6 : break;
952 : case EAP_PWD_OPCODE_COMMIT_EXCH:
953 6 : eap_pwd_process_commit_resp(sm, data, pos, len);
954 6 : break;
955 : case EAP_PWD_OPCODE_CONFIRM_EXCH:
956 6 : eap_pwd_process_confirm_resp(sm, data, pos, len);
957 6 : break;
958 : }
959 : /*
960 : * if we had been buffering fragments, here's a great place
961 : * to clean up
962 : */
963 18 : if (data->in_frag_pos) {
964 0 : wpabuf_free(data->inbuf);
965 0 : data->inbuf = NULL;
966 0 : data->in_frag_pos = 0;
967 : }
968 : }
969 :
970 :
971 6 : static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
972 : {
973 6 : struct eap_pwd_data *data = priv;
974 : u8 *key;
975 :
976 6 : if (data->state != SUCCESS)
977 0 : return NULL;
978 :
979 6 : key = os_malloc(EAP_MSK_LEN);
980 6 : if (key == NULL)
981 0 : return NULL;
982 :
983 6 : os_memcpy(key, data->msk, EAP_MSK_LEN);
984 6 : *len = EAP_MSK_LEN;
985 :
986 6 : return key;
987 : }
988 :
989 :
990 0 : static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
991 : {
992 0 : struct eap_pwd_data *data = priv;
993 : u8 *key;
994 :
995 0 : if (data->state != SUCCESS)
996 0 : return NULL;
997 :
998 0 : key = os_malloc(EAP_EMSK_LEN);
999 0 : if (key == NULL)
1000 0 : return NULL;
1001 :
1002 0 : os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1003 0 : *len = EAP_EMSK_LEN;
1004 :
1005 0 : return key;
1006 : }
1007 :
1008 :
1009 6 : static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1010 : {
1011 6 : struct eap_pwd_data *data = priv;
1012 6 : return data->state == SUCCESS;
1013 : }
1014 :
1015 :
1016 20 : static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1017 : {
1018 20 : struct eap_pwd_data *data = priv;
1019 20 : return (data->state == SUCCESS) || (data->state == FAILURE);
1020 : }
1021 :
1022 :
1023 1 : int eap_server_pwd_register(void)
1024 : {
1025 : struct eap_method *eap;
1026 : int ret;
1027 : struct timeval tp;
1028 : struct timezone tz;
1029 : u32 sr;
1030 :
1031 1 : EVP_add_digest(EVP_sha256());
1032 :
1033 1 : sr = 0xdeaddada;
1034 1 : (void) gettimeofday(&tp, &tz);
1035 1 : sr ^= (tp.tv_sec ^ tp.tv_usec);
1036 1 : srandom(sr);
1037 :
1038 1 : eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1039 : EAP_VENDOR_IETF, EAP_TYPE_PWD,
1040 : "PWD");
1041 1 : if (eap == NULL)
1042 0 : return -1;
1043 :
1044 1 : eap->init = eap_pwd_init;
1045 1 : eap->reset = eap_pwd_reset;
1046 1 : eap->buildReq = eap_pwd_build_req;
1047 1 : eap->check = eap_pwd_check;
1048 1 : eap->process = eap_pwd_process;
1049 1 : eap->isDone = eap_pwd_is_done;
1050 1 : eap->getKey = eap_pwd_getkey;
1051 1 : eap->get_emsk = eap_pwd_get_emsk;
1052 1 : eap->isSuccess = eap_pwd_is_success;
1053 :
1054 1 : ret = eap_server_method_register(eap);
1055 1 : if (ret)
1056 0 : eap_server_method_free(eap);
1057 1 : return ret;
1058 : }
1059 :
|
