1 /*
2 * EAP peer method: EAP-PSK (RFC 4764)
3 * Copyright (c) 2004-2008, 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 * Note: EAP-PSK is an EAP authentication method and as such, completely
9 * different from WPA-PSK. This file is not needed for WPA-PSK functionality.
10 */
11
12 #include "includes.h"
13
14 #include "common.h"
15 #include "crypto/aes_wrap.h"
16 #include "crypto/random.h"
17 #include "eap_common/eap_psk_common.h"
18 #include "eap_i.h"
19
20
21 struct eap_psk_data {
22 enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
23 u8 rand_p[EAP_PSK_RAND_LEN];
24 u8 rand_s[EAP_PSK_RAND_LEN];
25 u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
26 u8 *id_s, *id_p;
27 size_t id_s_len, id_p_len;
28 u8 msk[EAP_MSK_LEN];
29 u8 emsk[EAP_EMSK_LEN];
30 };
31
32
eap_psk_init(struct eap_sm * sm)33 static void * eap_psk_init(struct eap_sm *sm)
34 {
35 struct eap_psk_data *data;
36 const u8 *identity, *password;
37 size_t identity_len, password_len;
38
39 password = eap_get_config_password(sm, &password_len);
40 if (!password || password_len != 16) {
41 wpa_printf(MSG_INFO, "EAP-PSK: 16-octet pre-shared key not "
42 "configured");
43 return NULL;
44 }
45
46 data = os_zalloc(sizeof(*data));
47 if (data == NULL)
48 return NULL;
49 if (eap_psk_key_setup(password, data->ak, data->kdk)) {
50 os_free(data);
51 return NULL;
52 }
53 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
54 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
55 data->state = PSK_INIT;
56
57 identity = eap_get_config_identity(sm, &identity_len);
58 if (identity) {
59 data->id_p = os_malloc(identity_len);
60 if (data->id_p)
61 os_memcpy(data->id_p, identity, identity_len);
62 data->id_p_len = identity_len;
63 }
64 if (data->id_p == NULL) {
65 wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
66 os_free(data);
67 return NULL;
68 }
69
70 return data;
71 }
72
73
eap_psk_deinit(struct eap_sm * sm,void * priv)74 static void eap_psk_deinit(struct eap_sm *sm, void *priv)
75 {
76 struct eap_psk_data *data = priv;
77 os_free(data->id_s);
78 os_free(data->id_p);
79 bin_clear_free(data, sizeof(*data));
80 }
81
82
eap_psk_process_1(struct eap_psk_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData)83 static struct wpabuf * eap_psk_process_1(struct eap_psk_data *data,
84 struct eap_method_ret *ret,
85 const struct wpabuf *reqData)
86 {
87 const struct eap_psk_hdr_1 *hdr1;
88 struct eap_psk_hdr_2 *hdr2;
89 struct wpabuf *resp;
90 u8 *buf, *pos;
91 size_t buflen, len;
92 const u8 *cpos;
93
94 wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
95
96 cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
97 hdr1 = (const struct eap_psk_hdr_1 *) cpos;
98 if (cpos == NULL || len < sizeof(*hdr1)) {
99 wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
100 "length (%lu; expected %lu or more)",
101 (unsigned long) len,
102 (unsigned long) sizeof(*hdr1));
103 ret->ignore = TRUE;
104 return NULL;
105 }
106 wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
107 if (EAP_PSK_FLAGS_GET_T(hdr1->flags) != 0) {
108 wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
109 EAP_PSK_FLAGS_GET_T(hdr1->flags));
110 ret->methodState = METHOD_DONE;
111 ret->decision = DECISION_FAIL;
112 return NULL;
113 }
114 wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
115 EAP_PSK_RAND_LEN);
116 os_memcpy(data->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
117 os_free(data->id_s);
118 data->id_s_len = len - sizeof(*hdr1);
119 data->id_s = os_memdup(hdr1 + 1, data->id_s_len);
120 if (data->id_s == NULL) {
121 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
122 "ID_S (len=%lu)", (unsigned long) data->id_s_len);
123 ret->ignore = TRUE;
124 return NULL;
125 }
126 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
127 data->id_s, data->id_s_len);
128
129 if (random_get_bytes(data->rand_p, EAP_PSK_RAND_LEN)) {
130 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
131 ret->ignore = TRUE;
132 return NULL;
133 }
134
135 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
136 sizeof(*hdr2) + data->id_p_len, EAP_CODE_RESPONSE,
137 eap_get_id(reqData));
138 if (resp == NULL)
139 return NULL;
140 hdr2 = wpabuf_put(resp, sizeof(*hdr2));
141 hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
142 os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
143 os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
144 wpabuf_put_data(resp, data->id_p, data->id_p_len);
145 /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
146 buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
147 buf = os_malloc(buflen);
148 if (buf == NULL) {
149 wpabuf_free(resp);
150 return NULL;
151 }
152 os_memcpy(buf, data->id_p, data->id_p_len);
153 pos = buf + data->id_p_len;
154 os_memcpy(pos, data->id_s, data->id_s_len);
155 pos += data->id_s_len;
156 os_memcpy(pos, hdr1->rand_s, EAP_PSK_RAND_LEN);
157 pos += EAP_PSK_RAND_LEN;
158 os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
159 if (omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p)) {
160 os_free(buf);
161 wpabuf_free(resp);
162 return NULL;
163 }
164 os_free(buf);
165 wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
166 EAP_PSK_RAND_LEN);
167 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
168 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
169 data->id_p, data->id_p_len);
170
171 data->state = PSK_MAC_SENT;
172
173 return resp;
174 }
175
176
eap_psk_process_3(struct eap_psk_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData)177 static struct wpabuf * eap_psk_process_3(struct eap_psk_data *data,
178 struct eap_method_ret *ret,
179 const struct wpabuf *reqData)
180 {
181 const struct eap_psk_hdr_3 *hdr3;
182 struct eap_psk_hdr_4 *hdr4;
183 struct wpabuf *resp;
184 u8 *buf, *rpchannel, nonce[16], *decrypted;
185 const u8 *pchannel, *tag, *msg;
186 u8 mac[EAP_PSK_MAC_LEN];
187 size_t buflen, left, data_len, len, plen;
188 int failed = 0;
189 const u8 *pos;
190
191 wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
192
193 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
194 reqData, &len);
195 hdr3 = (const struct eap_psk_hdr_3 *) pos;
196 if (pos == NULL || len < sizeof(*hdr3)) {
197 wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
198 "length (%lu; expected %lu or more)",
199 (unsigned long) len,
200 (unsigned long) sizeof(*hdr3));
201 ret->ignore = TRUE;
202 return NULL;
203 }
204 left = len - sizeof(*hdr3);
205 pchannel = (const u8 *) (hdr3 + 1);
206 wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
207 if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
208 wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
209 EAP_PSK_FLAGS_GET_T(hdr3->flags));
210 ret->methodState = METHOD_DONE;
211 ret->decision = DECISION_FAIL;
212 return NULL;
213 }
214 wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
215 EAP_PSK_RAND_LEN);
216 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
217 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
218
219 if (left < 4 + 16 + 1) {
220 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
221 "third message (len=%lu, expected 21)",
222 (unsigned long) left);
223 ret->ignore = TRUE;
224 return NULL;
225 }
226
227 /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
228 buflen = data->id_s_len + EAP_PSK_RAND_LEN;
229 buf = os_malloc(buflen);
230 if (buf == NULL)
231 return NULL;
232 os_memcpy(buf, data->id_s, data->id_s_len);
233 os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
234 if (omac1_aes_128(data->ak, buf, buflen, mac)) {
235 os_free(buf);
236 return NULL;
237 }
238 os_free(buf);
239 if (os_memcmp_const(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
240 wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
241 "message");
242 ret->methodState = METHOD_DONE;
243 ret->decision = DECISION_FAIL;
244 return NULL;
245 }
246 wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
247
248 if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
249 data->msk, data->emsk)) {
250 ret->methodState = METHOD_DONE;
251 ret->decision = DECISION_FAIL;
252 return NULL;
253 }
254 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
255 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
256 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
257
258 os_memset(nonce, 0, 12);
259 os_memcpy(nonce + 12, pchannel, 4);
260 pchannel += 4;
261 left -= 4;
262
263 tag = pchannel;
264 pchannel += 16;
265 left -= 16;
266
267 msg = pchannel;
268
269 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
270 nonce, sizeof(nonce));
271 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr",
272 wpabuf_head(reqData), 5);
273 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
274
275 decrypted = os_memdup(msg, left);
276 if (decrypted == NULL) {
277 ret->methodState = METHOD_DONE;
278 ret->decision = DECISION_FAIL;
279 return NULL;
280 }
281
282 if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
283 wpabuf_head(reqData),
284 sizeof(struct eap_hdr) + 1 +
285 sizeof(*hdr3) - EAP_PSK_MAC_LEN, decrypted,
286 left, tag)) {
287 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
288 os_free(decrypted);
289 return NULL;
290 }
291 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
292 decrypted, left);
293
294 /* Verify R flag */
295 switch (decrypted[0] >> 6) {
296 case EAP_PSK_R_FLAG_CONT:
297 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
298 failed = 1;
299 break;
300 case EAP_PSK_R_FLAG_DONE_SUCCESS:
301 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
302 break;
303 case EAP_PSK_R_FLAG_DONE_FAILURE:
304 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
305 wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
306 "authentication");
307 failed = 1;
308 break;
309 }
310
311 data_len = 1;
312 if ((decrypted[0] & EAP_PSK_E_FLAG) && left > 1)
313 data_len++;
314 plen = sizeof(*hdr4) + 4 + 16 + data_len;
315 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, plen,
316 EAP_CODE_RESPONSE, eap_get_id(reqData));
317 if (resp == NULL) {
318 os_free(decrypted);
319 return NULL;
320 }
321 hdr4 = wpabuf_put(resp, sizeof(*hdr4));
322 hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
323 os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
324 rpchannel = wpabuf_put(resp, 4 + 16 + data_len);
325
326 /* nonce++ */
327 inc_byte_array(nonce, sizeof(nonce));
328 os_memcpy(rpchannel, nonce + 12, 4);
329
330 if (decrypted[0] & EAP_PSK_E_FLAG) {
331 wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
332 failed = 1;
333 rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
334 EAP_PSK_E_FLAG;
335 if (left > 1) {
336 /* Add empty EXT_Payload with same EXT_Type */
337 rpchannel[4 + 16 + 1] = decrypted[1];
338 }
339 } else if (failed)
340 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
341 else
342 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
343
344 wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
345 rpchannel + 4 + 16, data_len);
346 if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
347 wpabuf_head(resp),
348 sizeof(struct eap_hdr) + 1 + sizeof(*hdr4),
349 rpchannel + 4 + 16, data_len, rpchannel + 4)) {
350 os_free(decrypted);
351 wpabuf_free(resp);
352 return NULL;
353 }
354 wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
355 rpchannel, 4 + 16 + data_len);
356
357 wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
358 failed ? "un" : "");
359 data->state = PSK_DONE;
360 ret->methodState = METHOD_DONE;
361 ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
362
363 os_free(decrypted);
364
365 return resp;
366 }
367
368
eap_psk_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)369 static struct wpabuf * eap_psk_process(struct eap_sm *sm, void *priv,
370 struct eap_method_ret *ret,
371 const struct wpabuf *reqData)
372 {
373 struct eap_psk_data *data = priv;
374 const u8 *pos;
375 struct wpabuf *resp = NULL;
376 size_t len;
377
378 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
379 if (pos == NULL) {
380 ret->ignore = TRUE;
381 return NULL;
382 }
383
384 ret->ignore = FALSE;
385 ret->methodState = METHOD_MAY_CONT;
386 ret->decision = DECISION_FAIL;
387 ret->allowNotifications = TRUE;
388
389 switch (data->state) {
390 case PSK_INIT:
391 resp = eap_psk_process_1(data, ret, reqData);
392 break;
393 case PSK_MAC_SENT:
394 resp = eap_psk_process_3(data, ret, reqData);
395 break;
396 case PSK_DONE:
397 wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
398 "unexpected message");
399 ret->ignore = TRUE;
400 return NULL;
401 }
402
403 if (ret->methodState == METHOD_DONE) {
404 ret->allowNotifications = FALSE;
405 }
406
407 return resp;
408 }
409
410
eap_psk_isKeyAvailable(struct eap_sm * sm,void * priv)411 static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
412 {
413 struct eap_psk_data *data = priv;
414 return data->state == PSK_DONE;
415 }
416
417
eap_psk_getKey(struct eap_sm * sm,void * priv,size_t * len)418 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
419 {
420 struct eap_psk_data *data = priv;
421 u8 *key;
422
423 if (data->state != PSK_DONE)
424 return NULL;
425
426 key = os_memdup(data->msk, EAP_MSK_LEN);
427 if (key == NULL)
428 return NULL;
429
430 *len = EAP_MSK_LEN;
431
432 return key;
433 }
434
435
eap_psk_get_session_id(struct eap_sm * sm,void * priv,size_t * len)436 static u8 * eap_psk_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
437 {
438 struct eap_psk_data *data = priv;
439 u8 *id;
440
441 if (data->state != PSK_DONE)
442 return NULL;
443
444 *len = 1 + 2 * EAP_PSK_RAND_LEN;
445 id = os_malloc(*len);
446 if (id == NULL)
447 return NULL;
448
449 id[0] = EAP_TYPE_PSK;
450 os_memcpy(id + 1, data->rand_p, EAP_PSK_RAND_LEN);
451 os_memcpy(id + 1 + EAP_PSK_RAND_LEN, data->rand_s, EAP_PSK_RAND_LEN);
452 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Derived Session-Id", id, *len);
453
454 return id;
455 }
456
457
eap_psk_get_emsk(struct eap_sm * sm,void * priv,size_t * len)458 static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
459 {
460 struct eap_psk_data *data = priv;
461 u8 *key;
462
463 if (data->state != PSK_DONE)
464 return NULL;
465
466 key = os_memdup(data->emsk, EAP_EMSK_LEN);
467 if (key == NULL)
468 return NULL;
469
470 *len = EAP_EMSK_LEN;
471
472 return key;
473 }
474
475
eap_peer_psk_register(void)476 int eap_peer_psk_register(void)
477 {
478 struct eap_method *eap;
479
480 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
481 EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
482 if (eap == NULL)
483 return -1;
484
485 eap->init = eap_psk_init;
486 eap->deinit = eap_psk_deinit;
487 eap->process = eap_psk_process;
488 eap->isKeyAvailable = eap_psk_isKeyAvailable;
489 eap->getKey = eap_psk_getKey;
490 eap->getSessionId = eap_psk_get_session_id;
491 eap->get_emsk = eap_psk_get_emsk;
492
493 return eap_peer_method_register(eap);
494 }
495