1 /*
2 * EAP peer method: EAP-PAX (RFC 4746)
3 * Copyright (c) 2005-2008, Jouni Malinen <j@w1.fi>
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/random.h"
13 #include "eap_common/eap_pax_common.h"
14 #include "eap_i.h"
15
16 /*
17 * Note: only PAX_STD subprotocol is currently supported
18 *
19 * TODO: Add support with PAX_SEC with the mandatory to implement ciphersuite
20 * (HMAC_SHA1_128, IANA DH Group 14 (2048 bits), RSA-PKCS1-V1_5) and
21 * recommended ciphersuite (HMAC_SHA256_128, IANA DH Group 15 (3072 bits),
22 * RSAES-OAEP).
23 */
24
25 struct eap_pax_data {
26 enum { PAX_INIT, PAX_STD_2_SENT, PAX_DONE } state;
27 u8 mac_id, dh_group_id, public_key_id;
28 union {
29 u8 e[2 * EAP_PAX_RAND_LEN];
30 struct {
31 u8 x[EAP_PAX_RAND_LEN]; /* server rand */
32 u8 y[EAP_PAX_RAND_LEN]; /* client rand */
33 } r;
34 } rand;
35 char *cid;
36 size_t cid_len;
37 u8 ak[EAP_PAX_AK_LEN];
38 u8 mk[EAP_PAX_MK_LEN];
39 u8 ck[EAP_PAX_CK_LEN];
40 u8 ick[EAP_PAX_ICK_LEN];
41 u8 mid[EAP_PAX_MID_LEN];
42 };
43
44
45 static void eap_pax_deinit(struct eap_sm *sm, void *priv);
46
47
eap_pax_init(struct eap_sm * sm)48 static void * eap_pax_init(struct eap_sm *sm)
49 {
50 struct eap_pax_data *data;
51 const u8 *identity, *password;
52 size_t identity_len, password_len;
53
54 identity = eap_get_config_identity(sm, &identity_len);
55 password = eap_get_config_password(sm, &password_len);
56 if (!identity || !password) {
57 wpa_printf(MSG_INFO, "EAP-PAX: CID (nai) or key (password) "
58 "not configured");
59 return NULL;
60 }
61
62 if (password_len != EAP_PAX_AK_LEN) {
63 wpa_printf(MSG_INFO, "EAP-PAX: Invalid PSK length");
64 return NULL;
65 }
66
67 data = os_zalloc(sizeof(*data));
68 if (data == NULL)
69 return NULL;
70 data->state = PAX_INIT;
71
72 data->cid = os_malloc(identity_len);
73 if (data->cid == NULL) {
74 eap_pax_deinit(sm, data);
75 return NULL;
76 }
77 os_memcpy(data->cid, identity, identity_len);
78 data->cid_len = identity_len;
79
80 os_memcpy(data->ak, password, EAP_PAX_AK_LEN);
81
82 return data;
83 }
84
85
eap_pax_deinit(struct eap_sm * sm,void * priv)86 static void eap_pax_deinit(struct eap_sm *sm, void *priv)
87 {
88 struct eap_pax_data *data = priv;
89 os_free(data->cid);
90 bin_clear_free(data, sizeof(*data));
91 }
92
93
eap_pax_alloc_resp(const struct eap_pax_hdr * req,u8 id,u8 op_code,size_t plen)94 static struct wpabuf * eap_pax_alloc_resp(const struct eap_pax_hdr *req,
95 u8 id, u8 op_code, size_t plen)
96 {
97 struct wpabuf *resp;
98 struct eap_pax_hdr *pax;
99
100 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
101 sizeof(*pax) + plen, EAP_CODE_RESPONSE, id);
102 if (resp == NULL)
103 return NULL;
104
105 pax = wpabuf_put(resp, sizeof(*pax));
106 pax->op_code = op_code;
107 pax->flags = 0;
108 pax->mac_id = req->mac_id;
109 pax->dh_group_id = req->dh_group_id;
110 pax->public_key_id = req->public_key_id;
111
112 return resp;
113 }
114
115
eap_pax_process_std_1(struct eap_pax_data * data,struct eap_method_ret * ret,u8 id,const struct eap_pax_hdr * req,size_t req_plen)116 static struct wpabuf * eap_pax_process_std_1(struct eap_pax_data *data,
117 struct eap_method_ret *ret, u8 id,
118 const struct eap_pax_hdr *req,
119 size_t req_plen)
120 {
121 struct wpabuf *resp;
122 const u8 *pos;
123 u8 *rpos;
124 size_t left, plen;
125
126 wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-1 (received)");
127
128 if (data->state != PAX_INIT) {
129 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 received in "
130 "unexpected state (%d) - ignored", data->state);
131 ret->ignore = TRUE;
132 return NULL;
133 }
134
135 if (req->flags & EAP_PAX_FLAGS_CE) {
136 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with CE flag set - "
137 "ignored");
138 ret->ignore = TRUE;
139 return NULL;
140 }
141
142 left = req_plen - sizeof(*req);
143
144 if (left < 2 + EAP_PAX_RAND_LEN) {
145 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with too short "
146 "payload");
147 ret->ignore = TRUE;
148 return NULL;
149 }
150
151 pos = (const u8 *) (req + 1);
152 if (WPA_GET_BE16(pos) != EAP_PAX_RAND_LEN) {
153 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with incorrect A "
154 "length %d (expected %d)",
155 WPA_GET_BE16(pos), EAP_PAX_RAND_LEN);
156 ret->ignore = TRUE;
157 return NULL;
158 }
159
160 pos += 2;
161 left -= 2;
162 os_memcpy(data->rand.r.x, pos, EAP_PAX_RAND_LEN);
163 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: X (server rand)",
164 data->rand.r.x, EAP_PAX_RAND_LEN);
165 pos += EAP_PAX_RAND_LEN;
166 left -= EAP_PAX_RAND_LEN;
167
168 if (left > 0) {
169 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
170 pos, left);
171 }
172
173 if (random_get_bytes(data->rand.r.y, EAP_PAX_RAND_LEN)) {
174 wpa_printf(MSG_ERROR, "EAP-PAX: Failed to get random data");
175 ret->ignore = TRUE;
176 return NULL;
177 }
178 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Y (client rand)",
179 data->rand.r.y, EAP_PAX_RAND_LEN);
180
181 if (eap_pax_initial_key_derivation(req->mac_id, data->ak, data->rand.e,
182 data->mk, data->ck, data->ick,
183 data->mid) < 0) {
184 ret->ignore = TRUE;
185 return NULL;
186 }
187
188 wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-2 (sending)");
189
190 plen = 2 + EAP_PAX_RAND_LEN + 2 + data->cid_len + 2 + EAP_PAX_MAC_LEN +
191 EAP_PAX_ICV_LEN;
192 resp = eap_pax_alloc_resp(req, id, EAP_PAX_OP_STD_2, plen);
193 if (resp == NULL)
194 return NULL;
195
196 wpabuf_put_be16(resp, EAP_PAX_RAND_LEN);
197 wpabuf_put_data(resp, data->rand.r.y, EAP_PAX_RAND_LEN);
198 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: B = Y (client rand)",
199 data->rand.r.y, EAP_PAX_RAND_LEN);
200
201 wpabuf_put_be16(resp, data->cid_len);
202 wpabuf_put_data(resp, data->cid, data->cid_len);
203 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PAX: CID",
204 (u8 *) data->cid, data->cid_len);
205
206 wpabuf_put_be16(resp, EAP_PAX_MAC_LEN);
207 rpos = wpabuf_put(resp, EAP_PAX_MAC_LEN);
208 eap_pax_mac(req->mac_id, data->ck, EAP_PAX_CK_LEN,
209 data->rand.r.x, EAP_PAX_RAND_LEN,
210 data->rand.r.y, EAP_PAX_RAND_LEN,
211 (u8 *) data->cid, data->cid_len, rpos);
212 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(A, B, CID)",
213 rpos, EAP_PAX_MAC_LEN);
214
215 /* Optional ADE could be added here, if needed */
216
217 rpos = wpabuf_put(resp, EAP_PAX_ICV_LEN);
218 eap_pax_mac(req->mac_id, data->ick, EAP_PAX_ICK_LEN,
219 wpabuf_head(resp), wpabuf_len(resp) - EAP_PAX_ICV_LEN,
220 NULL, 0, NULL, 0, rpos);
221 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", rpos, EAP_PAX_ICV_LEN);
222
223 data->state = PAX_STD_2_SENT;
224 data->mac_id = req->mac_id;
225 data->dh_group_id = req->dh_group_id;
226 data->public_key_id = req->public_key_id;
227
228 return resp;
229 }
230
231
eap_pax_process_std_3(struct eap_pax_data * data,struct eap_method_ret * ret,u8 id,const struct eap_pax_hdr * req,size_t req_plen)232 static struct wpabuf * eap_pax_process_std_3(struct eap_pax_data *data,
233 struct eap_method_ret *ret, u8 id,
234 const struct eap_pax_hdr *req,
235 size_t req_plen)
236 {
237 struct wpabuf *resp;
238 u8 *rpos, mac[EAP_PAX_MAC_LEN];
239 const u8 *pos;
240 size_t left;
241
242 wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-3 (received)");
243
244 if (data->state != PAX_STD_2_SENT) {
245 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 received in "
246 "unexpected state (%d) - ignored", data->state);
247 ret->ignore = TRUE;
248 return NULL;
249 }
250
251 if (req->flags & EAP_PAX_FLAGS_CE) {
252 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with CE flag set - "
253 "ignored");
254 ret->ignore = TRUE;
255 return NULL;
256 }
257
258 left = req_plen - sizeof(*req);
259
260 if (left < 2 + EAP_PAX_MAC_LEN) {
261 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with too short "
262 "payload");
263 ret->ignore = TRUE;
264 return NULL;
265 }
266
267 pos = (const u8 *) (req + 1);
268 if (WPA_GET_BE16(pos) != EAP_PAX_MAC_LEN) {
269 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with incorrect "
270 "MAC_CK length %d (expected %d)",
271 WPA_GET_BE16(pos), EAP_PAX_MAC_LEN);
272 ret->ignore = TRUE;
273 return NULL;
274 }
275 pos += 2;
276 left -= 2;
277 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(B, CID)",
278 pos, EAP_PAX_MAC_LEN);
279 if (eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
280 data->rand.r.y, EAP_PAX_RAND_LEN,
281 (u8 *) data->cid, data->cid_len, NULL, 0, mac) < 0 ||
282 os_memcmp_const(pos, mac, EAP_PAX_MAC_LEN) != 0) {
283 wpa_printf(MSG_INFO, "EAP-PAX: Invalid MAC_CK(B, CID) "
284 "received");
285 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected MAC_CK(B, CID)",
286 mac, EAP_PAX_MAC_LEN);
287 ret->methodState = METHOD_DONE;
288 ret->decision = DECISION_FAIL;
289 return NULL;
290 }
291
292 pos += EAP_PAX_MAC_LEN;
293 left -= EAP_PAX_MAC_LEN;
294
295 if (left > 0) {
296 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
297 pos, left);
298 }
299
300 wpa_printf(MSG_DEBUG, "EAP-PAX: PAX-ACK (sending)");
301
302 resp = eap_pax_alloc_resp(req, id, EAP_PAX_OP_ACK, EAP_PAX_ICV_LEN);
303 if (resp == NULL)
304 return NULL;
305
306 /* Optional ADE could be added here, if needed */
307
308 rpos = wpabuf_put(resp, EAP_PAX_ICV_LEN);
309 if (eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
310 wpabuf_head(resp), wpabuf_len(resp) - EAP_PAX_ICV_LEN,
311 NULL, 0, NULL, 0, rpos) < 0) {
312 wpabuf_free(resp);
313 return NULL;
314 }
315 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", rpos, EAP_PAX_ICV_LEN);
316
317 data->state = PAX_DONE;
318 ret->methodState = METHOD_DONE;
319 ret->decision = DECISION_UNCOND_SUCC;
320 ret->allowNotifications = FALSE;
321
322 return resp;
323 }
324
325
eap_pax_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)326 static struct wpabuf * eap_pax_process(struct eap_sm *sm, void *priv,
327 struct eap_method_ret *ret,
328 const struct wpabuf *reqData)
329 {
330 struct eap_pax_data *data = priv;
331 const struct eap_pax_hdr *req;
332 struct wpabuf *resp;
333 u8 icvbuf[EAP_PAX_ICV_LEN], id;
334 const u8 *icv, *pos;
335 size_t len;
336 u16 flen, mlen;
337
338 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, reqData, &len);
339 if (pos == NULL || len < sizeof(*req) + EAP_PAX_ICV_LEN) {
340 ret->ignore = TRUE;
341 return NULL;
342 }
343 id = eap_get_id(reqData);
344 req = (const struct eap_pax_hdr *) pos;
345 flen = len - EAP_PAX_ICV_LEN;
346 mlen = wpabuf_len(reqData) - EAP_PAX_ICV_LEN;
347
348 wpa_printf(MSG_DEBUG, "EAP-PAX: received frame: op_code 0x%x "
349 "flags 0x%x mac_id 0x%x dh_group_id 0x%x "
350 "public_key_id 0x%x",
351 req->op_code, req->flags, req->mac_id, req->dh_group_id,
352 req->public_key_id);
353 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: received payload",
354 pos, len - EAP_PAX_ICV_LEN);
355
356 if (data->state != PAX_INIT && data->mac_id != req->mac_id) {
357 wpa_printf(MSG_INFO, "EAP-PAX: MAC ID changed during "
358 "authentication (was 0x%d, is 0x%d)",
359 data->mac_id, req->mac_id);
360 ret->ignore = TRUE;
361 return NULL;
362 }
363
364 if (data->state != PAX_INIT && data->dh_group_id != req->dh_group_id) {
365 wpa_printf(MSG_INFO, "EAP-PAX: DH Group ID changed during "
366 "authentication (was 0x%d, is 0x%d)",
367 data->dh_group_id, req->dh_group_id);
368 ret->ignore = TRUE;
369 return NULL;
370 }
371
372 if (data->state != PAX_INIT &&
373 data->public_key_id != req->public_key_id) {
374 wpa_printf(MSG_INFO, "EAP-PAX: Public Key ID changed during "
375 "authentication (was 0x%d, is 0x%d)",
376 data->public_key_id, req->public_key_id);
377 ret->ignore = TRUE;
378 return NULL;
379 }
380
381 /* TODO: add support EAP_PAX_HMAC_SHA256_128 */
382 if (req->mac_id != EAP_PAX_MAC_HMAC_SHA1_128) {
383 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported MAC ID 0x%x",
384 req->mac_id);
385 ret->ignore = TRUE;
386 return NULL;
387 }
388
389 if (req->dh_group_id != EAP_PAX_DH_GROUP_NONE) {
390 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported DH Group ID 0x%x",
391 req->dh_group_id);
392 ret->ignore = TRUE;
393 return NULL;
394 }
395
396 if (req->public_key_id != EAP_PAX_PUBLIC_KEY_NONE) {
397 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported Public Key ID 0x%x",
398 req->public_key_id);
399 ret->ignore = TRUE;
400 return NULL;
401 }
402
403 if (req->flags & EAP_PAX_FLAGS_MF) {
404 /* TODO: add support for reassembling fragments */
405 wpa_printf(MSG_INFO, "EAP-PAX: fragmentation not supported - "
406 "ignored packet");
407 ret->ignore = TRUE;
408 return NULL;
409 }
410
411 icv = pos + len - EAP_PAX_ICV_LEN;
412 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", icv, EAP_PAX_ICV_LEN);
413 if (req->op_code == EAP_PAX_OP_STD_1) {
414 eap_pax_mac(req->mac_id, (u8 *) "", 0,
415 wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
416 icvbuf);
417 } else {
418 eap_pax_mac(req->mac_id, data->ick, EAP_PAX_ICK_LEN,
419 wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
420 icvbuf);
421 }
422 if (os_memcmp_const(icv, icvbuf, EAP_PAX_ICV_LEN) != 0) {
423 wpa_printf(MSG_DEBUG, "EAP-PAX: invalid ICV - ignoring the "
424 "message");
425 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected ICV",
426 icvbuf, EAP_PAX_ICV_LEN);
427 ret->ignore = TRUE;
428 return NULL;
429 }
430
431 ret->ignore = FALSE;
432 ret->methodState = METHOD_MAY_CONT;
433 ret->decision = DECISION_FAIL;
434 ret->allowNotifications = TRUE;
435
436 switch (req->op_code) {
437 case EAP_PAX_OP_STD_1:
438 resp = eap_pax_process_std_1(data, ret, id, req, flen);
439 break;
440 case EAP_PAX_OP_STD_3:
441 resp = eap_pax_process_std_3(data, ret, id, req, flen);
442 break;
443 default:
444 wpa_printf(MSG_DEBUG, "EAP-PAX: ignoring message with unknown "
445 "op_code %d", req->op_code);
446 ret->ignore = TRUE;
447 return NULL;
448 }
449
450 if (ret->methodState == METHOD_DONE) {
451 ret->allowNotifications = FALSE;
452 }
453
454 return resp;
455 }
456
457
eap_pax_isKeyAvailable(struct eap_sm * sm,void * priv)458 static Boolean eap_pax_isKeyAvailable(struct eap_sm *sm, void *priv)
459 {
460 struct eap_pax_data *data = priv;
461 return data->state == PAX_DONE;
462 }
463
464
eap_pax_getKey(struct eap_sm * sm,void * priv,size_t * len)465 static u8 * eap_pax_getKey(struct eap_sm *sm, void *priv, size_t *len)
466 {
467 struct eap_pax_data *data = priv;
468 u8 *key;
469
470 if (data->state != PAX_DONE)
471 return NULL;
472
473 key = os_malloc(EAP_MSK_LEN);
474 if (key == NULL)
475 return NULL;
476
477 *len = EAP_MSK_LEN;
478 if (eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
479 "Master Session Key",
480 data->rand.e, 2 * EAP_PAX_RAND_LEN,
481 EAP_MSK_LEN, key) < 0) {
482 os_free(key);
483 return NULL;
484 }
485
486 return key;
487 }
488
489
eap_pax_get_emsk(struct eap_sm * sm,void * priv,size_t * len)490 static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
491 {
492 struct eap_pax_data *data = priv;
493 u8 *key;
494
495 if (data->state != PAX_DONE)
496 return NULL;
497
498 key = os_malloc(EAP_EMSK_LEN);
499 if (key == NULL)
500 return NULL;
501
502 *len = EAP_EMSK_LEN;
503 if (eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
504 "Extended Master Session Key",
505 data->rand.e, 2 * EAP_PAX_RAND_LEN,
506 EAP_EMSK_LEN, key) < 0) {
507 os_free(key);
508 return NULL;
509 }
510
511 return key;
512 }
513
514
eap_pax_get_session_id(struct eap_sm * sm,void * priv,size_t * len)515 static u8 * eap_pax_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
516 {
517 struct eap_pax_data *data = priv;
518 u8 *sid;
519
520 if (data->state != PAX_DONE)
521 return NULL;
522
523 sid = os_malloc(1 + EAP_PAX_MID_LEN);
524 if (sid == NULL)
525 return NULL;
526
527 *len = 1 + EAP_PAX_MID_LEN;
528 sid[0] = EAP_TYPE_PAX;
529 os_memcpy(sid + 1, data->mid, EAP_PAX_MID_LEN);
530
531 return sid;
532 }
533
534
eap_peer_pax_register(void)535 int eap_peer_pax_register(void)
536 {
537 struct eap_method *eap;
538
539 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
540 EAP_VENDOR_IETF, EAP_TYPE_PAX, "PAX");
541 if (eap == NULL)
542 return -1;
543
544 eap->init = eap_pax_init;
545 eap->deinit = eap_pax_deinit;
546 eap->process = eap_pax_process;
547 eap->isKeyAvailable = eap_pax_isKeyAvailable;
548 eap->getKey = eap_pax_getKey;
549 eap->get_emsk = eap_pax_get_emsk;
550 eap->getSessionId = eap_pax_get_session_id;
551
552 return eap_peer_method_register(eap);
553 }
554