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_malloc(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 os_memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
127 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
128 data->id_s, data->id_s_len);
129
130 if (random_get_bytes(data->rand_p, EAP_PSK_RAND_LEN)) {
131 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
132 ret->ignore = TRUE;
133 return NULL;
134 }
135
136 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
137 sizeof(*hdr2) + data->id_p_len, EAP_CODE_RESPONSE,
138 eap_get_id(reqData));
139 if (resp == NULL)
140 return NULL;
141 hdr2 = wpabuf_put(resp, sizeof(*hdr2));
142 hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
143 os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
144 os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
145 wpabuf_put_data(resp, data->id_p, data->id_p_len);
146 /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
147 buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
148 buf = os_malloc(buflen);
149 if (buf == NULL) {
150 wpabuf_free(resp);
151 return NULL;
152 }
153 os_memcpy(buf, data->id_p, data->id_p_len);
154 pos = buf + data->id_p_len;
155 os_memcpy(pos, data->id_s, data->id_s_len);
156 pos += data->id_s_len;
157 os_memcpy(pos, hdr1->rand_s, EAP_PSK_RAND_LEN);
158 pos += EAP_PSK_RAND_LEN;
159 os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
160 if (omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p)) {
161 os_free(buf);
162 wpabuf_free(resp);
163 return NULL;
164 }
165 os_free(buf);
166 wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
167 EAP_PSK_RAND_LEN);
168 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
169 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
170 data->id_p, data->id_p_len);
171
172 data->state = PSK_MAC_SENT;
173
174 return resp;
175 }
176
177
eap_psk_process_3(struct eap_psk_data * data,struct eap_method_ret * ret,const struct wpabuf * reqData)178 static struct wpabuf * eap_psk_process_3(struct eap_psk_data *data,
179 struct eap_method_ret *ret,
180 const struct wpabuf *reqData)
181 {
182 const struct eap_psk_hdr_3 *hdr3;
183 struct eap_psk_hdr_4 *hdr4;
184 struct wpabuf *resp;
185 u8 *buf, *rpchannel, nonce[16], *decrypted;
186 const u8 *pchannel, *tag, *msg;
187 u8 mac[EAP_PSK_MAC_LEN];
188 size_t buflen, left, data_len, len, plen;
189 int failed = 0;
190 const u8 *pos;
191
192 wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
193
194 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
195 reqData, &len);
196 hdr3 = (const struct eap_psk_hdr_3 *) pos;
197 if (pos == NULL || len < sizeof(*hdr3)) {
198 wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
199 "length (%lu; expected %lu or more)",
200 (unsigned long) len,
201 (unsigned long) sizeof(*hdr3));
202 ret->ignore = TRUE;
203 return NULL;
204 }
205 left = len - sizeof(*hdr3);
206 pchannel = (const u8 *) (hdr3 + 1);
207 wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
208 if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
209 wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
210 EAP_PSK_FLAGS_GET_T(hdr3->flags));
211 ret->methodState = METHOD_DONE;
212 ret->decision = DECISION_FAIL;
213 return NULL;
214 }
215 wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
216 EAP_PSK_RAND_LEN);
217 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
218 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
219
220 if (left < 4 + 16 + 1) {
221 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
222 "third message (len=%lu, expected 21)",
223 (unsigned long) left);
224 ret->ignore = TRUE;
225 return NULL;
226 }
227
228 /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
229 buflen = data->id_s_len + EAP_PSK_RAND_LEN;
230 buf = os_malloc(buflen);
231 if (buf == NULL)
232 return NULL;
233 os_memcpy(buf, data->id_s, data->id_s_len);
234 os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
235 if (omac1_aes_128(data->ak, buf, buflen, mac)) {
236 os_free(buf);
237 return NULL;
238 }
239 os_free(buf);
240 if (os_memcmp_const(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
241 wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
242 "message");
243 ret->methodState = METHOD_DONE;
244 ret->decision = DECISION_FAIL;
245 return NULL;
246 }
247 wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
248
249 if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
250 data->msk, data->emsk)) {
251 ret->methodState = METHOD_DONE;
252 ret->decision = DECISION_FAIL;
253 return NULL;
254 }
255 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
256 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
257 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
258
259 os_memset(nonce, 0, 12);
260 os_memcpy(nonce + 12, pchannel, 4);
261 pchannel += 4;
262 left -= 4;
263
264 tag = pchannel;
265 pchannel += 16;
266 left -= 16;
267
268 msg = pchannel;
269
270 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
271 nonce, sizeof(nonce));
272 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr",
273 wpabuf_head(reqData), 5);
274 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
275
276 decrypted = os_malloc(left);
277 if (decrypted == NULL) {
278 ret->methodState = METHOD_DONE;
279 ret->decision = DECISION_FAIL;
280 return NULL;
281 }
282 os_memcpy(decrypted, msg, left);
283
284 if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
285 wpabuf_head(reqData),
286 sizeof(struct eap_hdr) + 1 +
287 sizeof(*hdr3) - EAP_PSK_MAC_LEN, decrypted,
288 left, tag)) {
289 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
290 os_free(decrypted);
291 return NULL;
292 }
293 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
294 decrypted, left);
295
296 /* Verify R flag */
297 switch (decrypted[0] >> 6) {
298 case EAP_PSK_R_FLAG_CONT:
299 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
300 failed = 1;
301 break;
302 case EAP_PSK_R_FLAG_DONE_SUCCESS:
303 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
304 break;
305 case EAP_PSK_R_FLAG_DONE_FAILURE:
306 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
307 wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
308 "authentication");
309 failed = 1;
310 break;
311 }
312
313 data_len = 1;
314 if ((decrypted[0] & EAP_PSK_E_FLAG) && left > 1)
315 data_len++;
316 plen = sizeof(*hdr4) + 4 + 16 + data_len;
317 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, plen,
318 EAP_CODE_RESPONSE, eap_get_id(reqData));
319 if (resp == NULL) {
320 os_free(decrypted);
321 return NULL;
322 }
323 hdr4 = wpabuf_put(resp, sizeof(*hdr4));
324 hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
325 os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
326 rpchannel = wpabuf_put(resp, 4 + 16 + data_len);
327
328 /* nonce++ */
329 inc_byte_array(nonce, sizeof(nonce));
330 os_memcpy(rpchannel, nonce + 12, 4);
331
332 if (decrypted[0] & EAP_PSK_E_FLAG) {
333 wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
334 failed = 1;
335 rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
336 EAP_PSK_E_FLAG;
337 if (left > 1) {
338 /* Add empty EXT_Payload with same EXT_Type */
339 rpchannel[4 + 16 + 1] = decrypted[1];
340 }
341 } else if (failed)
342 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
343 else
344 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
345
346 wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
347 rpchannel + 4 + 16, data_len);
348 if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
349 wpabuf_head(resp),
350 sizeof(struct eap_hdr) + 1 + sizeof(*hdr4),
351 rpchannel + 4 + 16, data_len, rpchannel + 4)) {
352 os_free(decrypted);
353 wpabuf_free(resp);
354 return NULL;
355 }
356 wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
357 rpchannel, 4 + 16 + data_len);
358
359 wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
360 failed ? "un" : "");
361 data->state = PSK_DONE;
362 ret->methodState = METHOD_DONE;
363 ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
364
365 os_free(decrypted);
366
367 return resp;
368 }
369
370
eap_psk_process(struct eap_sm * sm,void * priv,struct eap_method_ret * ret,const struct wpabuf * reqData)371 static struct wpabuf * eap_psk_process(struct eap_sm *sm, void *priv,
372 struct eap_method_ret *ret,
373 const struct wpabuf *reqData)
374 {
375 struct eap_psk_data *data = priv;
376 const u8 *pos;
377 struct wpabuf *resp = NULL;
378 size_t len;
379
380 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
381 if (pos == NULL) {
382 ret->ignore = TRUE;
383 return NULL;
384 }
385
386 ret->ignore = FALSE;
387 ret->methodState = METHOD_MAY_CONT;
388 ret->decision = DECISION_FAIL;
389 ret->allowNotifications = TRUE;
390
391 switch (data->state) {
392 case PSK_INIT:
393 resp = eap_psk_process_1(data, ret, reqData);
394 break;
395 case PSK_MAC_SENT:
396 resp = eap_psk_process_3(data, ret, reqData);
397 break;
398 case PSK_DONE:
399 wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
400 "unexpected message");
401 ret->ignore = TRUE;
402 return NULL;
403 }
404
405 if (ret->methodState == METHOD_DONE) {
406 ret->allowNotifications = FALSE;
407 }
408
409 return resp;
410 }
411
412
eap_psk_isKeyAvailable(struct eap_sm * sm,void * priv)413 static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
414 {
415 struct eap_psk_data *data = priv;
416 return data->state == PSK_DONE;
417 }
418
419
eap_psk_getKey(struct eap_sm * sm,void * priv,size_t * len)420 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
421 {
422 struct eap_psk_data *data = priv;
423 u8 *key;
424
425 if (data->state != PSK_DONE)
426 return NULL;
427
428 key = os_malloc(EAP_MSK_LEN);
429 if (key == NULL)
430 return NULL;
431
432 *len = EAP_MSK_LEN;
433 os_memcpy(key, data->msk, EAP_MSK_LEN);
434
435 return key;
436 }
437
438
eap_psk_get_session_id(struct eap_sm * sm,void * priv,size_t * len)439 static u8 * eap_psk_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
440 {
441 struct eap_psk_data *data = priv;
442 u8 *id;
443
444 if (data->state != PSK_DONE)
445 return NULL;
446
447 *len = 1 + 2 * EAP_PSK_RAND_LEN;
448 id = os_malloc(*len);
449 if (id == NULL)
450 return NULL;
451
452 id[0] = EAP_TYPE_PSK;
453 os_memcpy(id + 1, data->rand_p, EAP_PSK_RAND_LEN);
454 os_memcpy(id + 1 + EAP_PSK_RAND_LEN, data->rand_s, EAP_PSK_RAND_LEN);
455 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Derived Session-Id", id, *len);
456
457 return id;
458 }
459
460
eap_psk_get_emsk(struct eap_sm * sm,void * priv,size_t * len)461 static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
462 {
463 struct eap_psk_data *data = priv;
464 u8 *key;
465
466 if (data->state != PSK_DONE)
467 return NULL;
468
469 key = os_malloc(EAP_EMSK_LEN);
470 if (key == NULL)
471 return NULL;
472
473 *len = EAP_EMSK_LEN;
474 os_memcpy(key, data->emsk, EAP_EMSK_LEN);
475
476 return key;
477 }
478
479
eap_peer_psk_register(void)480 int eap_peer_psk_register(void)
481 {
482 struct eap_method *eap;
483
484 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
485 EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
486 if (eap == NULL)
487 return -1;
488
489 eap->init = eap_psk_init;
490 eap->deinit = eap_psk_deinit;
491 eap->process = eap_psk_process;
492 eap->isKeyAvailable = eap_psk_isKeyAvailable;
493 eap->getKey = eap_psk_getKey;
494 eap->getSessionId = eap_psk_get_session_id;
495 eap->get_emsk = eap_psk_get_emsk;
496
497 return eap_peer_method_register(eap);
498 }
499