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 wpa_printf(MSG_INFO,
283 "EAP-PAX: Could not derive MAC_CK(B, CID)");
284 ret->methodState = METHOD_DONE;
285 ret->decision = DECISION_FAIL;
286 return NULL;
287 }
288
289 if (os_memcmp_const(pos, mac, EAP_PAX_MAC_LEN) != 0) {
290 wpa_printf(MSG_INFO, "EAP-PAX: Invalid MAC_CK(B, CID) "
291 "received");
292 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected MAC_CK(B, CID)",
293 mac, EAP_PAX_MAC_LEN);
294 ret->methodState = METHOD_DONE;
295 ret->decision = DECISION_FAIL;
296 return NULL;
297 }
298
299 pos += EAP_PAX_MAC_LEN;
300 left -= EAP_PAX_MAC_LEN;
301
302 if (left > 0) {
303 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
304 pos, left);
305 }
306
307 wpa_printf(MSG_DEBUG, "EAP-PAX: PAX-ACK (sending)");
308
309 resp = eap_pax_alloc_resp(req, id, EAP_PAX_OP_ACK, EAP_PAX_ICV_LEN);
310 if (resp == NULL)
311 return NULL;
312
313 /* Optional ADE could be added here, if needed */
314
315 rpos = wpabuf_put(resp, EAP_PAX_ICV_LEN);
316 if (eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
317 wpabuf_head(resp), wpabuf_len(resp) - EAP_PAX_ICV_LEN,
318 NULL, 0, NULL, 0, rpos) < 0) {
319 wpabuf_free(resp);
320 return NULL;
321 }
322 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", rpos, EAP_PAX_ICV_LEN);
323
324 data->state = PAX_DONE;
325 ret->methodState = METHOD_DONE;
326 ret->decision = DECISION_UNCOND_SUCC;
327 ret->allowNotifications = FALSE;
328
329 return resp;
330 }
331
332
eap_pax_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)333 static struct wpabuf * eap_pax_process(struct eap_sm *sm, void *priv,
334 struct eap_method_ret *ret,
335 const struct wpabuf *reqData)
336 {
337 struct eap_pax_data *data = priv;
338 const struct eap_pax_hdr *req;
339 struct wpabuf *resp;
340 u8 icvbuf[EAP_PAX_ICV_LEN], id;
341 const u8 *icv, *pos;
342 size_t len;
343 u16 flen, mlen;
344
345 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, reqData, &len);
346 if (pos == NULL || len < sizeof(*req) + EAP_PAX_ICV_LEN) {
347 ret->ignore = TRUE;
348 return NULL;
349 }
350 id = eap_get_id(reqData);
351 req = (const struct eap_pax_hdr *) pos;
352 flen = len - EAP_PAX_ICV_LEN;
353 mlen = wpabuf_len(reqData) - EAP_PAX_ICV_LEN;
354
355 wpa_printf(MSG_DEBUG, "EAP-PAX: received frame: op_code 0x%x "
356 "flags 0x%x mac_id 0x%x dh_group_id 0x%x "
357 "public_key_id 0x%x",
358 req->op_code, req->flags, req->mac_id, req->dh_group_id,
359 req->public_key_id);
360 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: received payload",
361 pos, len - EAP_PAX_ICV_LEN);
362
363 if (data->state != PAX_INIT && data->mac_id != req->mac_id) {
364 wpa_printf(MSG_INFO, "EAP-PAX: MAC ID changed during "
365 "authentication (was 0x%d, is 0x%d)",
366 data->mac_id, req->mac_id);
367 ret->ignore = TRUE;
368 return NULL;
369 }
370
371 if (data->state != PAX_INIT && data->dh_group_id != req->dh_group_id) {
372 wpa_printf(MSG_INFO, "EAP-PAX: DH Group ID changed during "
373 "authentication (was 0x%d, is 0x%d)",
374 data->dh_group_id, req->dh_group_id);
375 ret->ignore = TRUE;
376 return NULL;
377 }
378
379 if (data->state != PAX_INIT &&
380 data->public_key_id != req->public_key_id) {
381 wpa_printf(MSG_INFO, "EAP-PAX: Public Key ID changed during "
382 "authentication (was 0x%d, is 0x%d)",
383 data->public_key_id, req->public_key_id);
384 ret->ignore = TRUE;
385 return NULL;
386 }
387
388 /* TODO: add support EAP_PAX_HMAC_SHA256_128 */
389 if (req->mac_id != EAP_PAX_MAC_HMAC_SHA1_128) {
390 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported MAC ID 0x%x",
391 req->mac_id);
392 ret->ignore = TRUE;
393 return NULL;
394 }
395
396 if (req->dh_group_id != EAP_PAX_DH_GROUP_NONE) {
397 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported DH Group ID 0x%x",
398 req->dh_group_id);
399 ret->ignore = TRUE;
400 return NULL;
401 }
402
403 if (req->public_key_id != EAP_PAX_PUBLIC_KEY_NONE) {
404 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported Public Key ID 0x%x",
405 req->public_key_id);
406 ret->ignore = TRUE;
407 return NULL;
408 }
409
410 if (req->flags & EAP_PAX_FLAGS_MF) {
411 /* TODO: add support for reassembling fragments */
412 wpa_printf(MSG_INFO, "EAP-PAX: fragmentation not supported - "
413 "ignored packet");
414 ret->ignore = TRUE;
415 return NULL;
416 }
417
418 icv = pos + len - EAP_PAX_ICV_LEN;
419 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", icv, EAP_PAX_ICV_LEN);
420 if (req->op_code == EAP_PAX_OP_STD_1) {
421 eap_pax_mac(req->mac_id, (u8 *) "", 0,
422 wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
423 icvbuf);
424 } else {
425 eap_pax_mac(req->mac_id, data->ick, EAP_PAX_ICK_LEN,
426 wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
427 icvbuf);
428 }
429 if (os_memcmp_const(icv, icvbuf, EAP_PAX_ICV_LEN) != 0) {
430 wpa_printf(MSG_DEBUG, "EAP-PAX: invalid ICV - ignoring the "
431 "message");
432 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected ICV",
433 icvbuf, EAP_PAX_ICV_LEN);
434 ret->ignore = TRUE;
435 return NULL;
436 }
437
438 ret->ignore = FALSE;
439 ret->methodState = METHOD_MAY_CONT;
440 ret->decision = DECISION_FAIL;
441 ret->allowNotifications = TRUE;
442
443 switch (req->op_code) {
444 case EAP_PAX_OP_STD_1:
445 resp = eap_pax_process_std_1(data, ret, id, req, flen);
446 break;
447 case EAP_PAX_OP_STD_3:
448 resp = eap_pax_process_std_3(data, ret, id, req, flen);
449 break;
450 default:
451 wpa_printf(MSG_DEBUG, "EAP-PAX: ignoring message with unknown "
452 "op_code %d", req->op_code);
453 ret->ignore = TRUE;
454 return NULL;
455 }
456
457 if (ret->methodState == METHOD_DONE) {
458 ret->allowNotifications = FALSE;
459 }
460
461 return resp;
462 }
463
464
eap_pax_isKeyAvailable(struct eap_sm * sm,void * priv)465 static Boolean eap_pax_isKeyAvailable(struct eap_sm *sm, void *priv)
466 {
467 struct eap_pax_data *data = priv;
468 return data->state == PAX_DONE;
469 }
470
471
eap_pax_getKey(struct eap_sm * sm,void * priv,size_t * len)472 static u8 * eap_pax_getKey(struct eap_sm *sm, void *priv, size_t *len)
473 {
474 struct eap_pax_data *data = priv;
475 u8 *key;
476
477 if (data->state != PAX_DONE)
478 return NULL;
479
480 key = os_malloc(EAP_MSK_LEN);
481 if (key == NULL)
482 return NULL;
483
484 *len = EAP_MSK_LEN;
485 if (eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
486 "Master Session Key",
487 data->rand.e, 2 * EAP_PAX_RAND_LEN,
488 EAP_MSK_LEN, key) < 0) {
489 os_free(key);
490 return NULL;
491 }
492
493 return key;
494 }
495
496
eap_pax_get_emsk(struct eap_sm * sm,void * priv,size_t * len)497 static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
498 {
499 struct eap_pax_data *data = priv;
500 u8 *key;
501
502 if (data->state != PAX_DONE)
503 return NULL;
504
505 key = os_malloc(EAP_EMSK_LEN);
506 if (key == NULL)
507 return NULL;
508
509 *len = EAP_EMSK_LEN;
510 if (eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
511 "Extended Master Session Key",
512 data->rand.e, 2 * EAP_PAX_RAND_LEN,
513 EAP_EMSK_LEN, key) < 0) {
514 os_free(key);
515 return NULL;
516 }
517
518 return key;
519 }
520
521
eap_pax_get_session_id(struct eap_sm * sm,void * priv,size_t * len)522 static u8 * eap_pax_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
523 {
524 struct eap_pax_data *data = priv;
525 u8 *sid;
526
527 if (data->state != PAX_DONE)
528 return NULL;
529
530 sid = os_malloc(1 + EAP_PAX_MID_LEN);
531 if (sid == NULL)
532 return NULL;
533
534 *len = 1 + EAP_PAX_MID_LEN;
535 sid[0] = EAP_TYPE_PAX;
536 os_memcpy(sid + 1, data->mid, EAP_PAX_MID_LEN);
537
538 return sid;
539 }
540
541
eap_peer_pax_register(void)542 int eap_peer_pax_register(void)
543 {
544 struct eap_method *eap;
545
546 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
547 EAP_VENDOR_IETF, EAP_TYPE_PAX, "PAX");
548 if (eap == NULL)
549 return -1;
550
551 eap->init = eap_pax_init;
552 eap->deinit = eap_pax_deinit;
553 eap->process = eap_pax_process;
554 eap->isKeyAvailable = eap_pax_isKeyAvailable;
555 eap->getKey = eap_pax_getKey;
556 eap->get_emsk = eap_pax_get_emsk;
557 eap->getSessionId = eap_pax_get_session_id;
558
559 return eap_peer_method_register(eap);
560 }
561