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