1/*
2 * hostapd / EAP-PAX (RFC 4746) server
3 * Copyright (c) 2005-2007, 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_server/eap_i.h"
14#include "eap_common/eap_pax_common.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
25struct eap_pax_data {
26	enum { PAX_STD_1, PAX_STD_3, SUCCESS, FAILURE } state;
27	u8 mac_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	u8 ak[EAP_PAX_AK_LEN];
36	u8 mk[EAP_PAX_MK_LEN];
37	u8 ck[EAP_PAX_CK_LEN];
38	u8 ick[EAP_PAX_ICK_LEN];
39	int keys_set;
40	char *cid;
41	size_t cid_len;
42};
43
44
45static void * eap_pax_init(struct eap_sm *sm)
46{
47	struct eap_pax_data *data;
48
49	data = os_zalloc(sizeof(*data));
50	if (data == NULL)
51		return NULL;
52	data->state = PAX_STD_1;
53	/*
54	 * TODO: make this configurable once EAP_PAX_HMAC_SHA256_128 is
55	 * supported
56	 */
57	data->mac_id = EAP_PAX_MAC_HMAC_SHA1_128;
58
59	return data;
60}
61
62
63static void eap_pax_reset(struct eap_sm *sm, void *priv)
64{
65	struct eap_pax_data *data = priv;
66	os_free(data->cid);
67	os_free(data);
68}
69
70
71static struct wpabuf * eap_pax_build_std_1(struct eap_sm *sm,
72					   struct eap_pax_data *data, u8 id)
73{
74	struct wpabuf *req;
75	struct eap_pax_hdr *pax;
76	u8 *pos;
77
78	wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-1 (sending)");
79
80	if (random_get_bytes(data->rand.r.x, EAP_PAX_RAND_LEN)) {
81		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to get random data");
82		data->state = FAILURE;
83		return NULL;
84	}
85
86	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
87			    sizeof(*pax) + 2 + EAP_PAX_RAND_LEN +
88			    EAP_PAX_ICV_LEN, EAP_CODE_REQUEST, id);
89	if (req == NULL) {
90		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to allocate memory "
91			   "request");
92		data->state = FAILURE;
93		return NULL;
94	}
95
96	pax = wpabuf_put(req, sizeof(*pax));
97	pax->op_code = EAP_PAX_OP_STD_1;
98	pax->flags = 0;
99	pax->mac_id = data->mac_id;
100	pax->dh_group_id = EAP_PAX_DH_GROUP_NONE;
101	pax->public_key_id = EAP_PAX_PUBLIC_KEY_NONE;
102
103	wpabuf_put_be16(req, EAP_PAX_RAND_LEN);
104	wpabuf_put_data(req, data->rand.r.x, EAP_PAX_RAND_LEN);
105	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: A = X (server rand)",
106		    data->rand.r.x, EAP_PAX_RAND_LEN);
107
108	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
109	eap_pax_mac(data->mac_id, (u8 *) "", 0,
110		    wpabuf_mhead(req), wpabuf_len(req) - EAP_PAX_ICV_LEN,
111		    NULL, 0, NULL, 0, pos);
112	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
113
114	return req;
115}
116
117
118static struct wpabuf * eap_pax_build_std_3(struct eap_sm *sm,
119					   struct eap_pax_data *data, u8 id)
120{
121	struct wpabuf *req;
122	struct eap_pax_hdr *pax;
123	u8 *pos;
124
125	wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-3 (sending)");
126
127	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
128			    sizeof(*pax) + 2 + EAP_PAX_MAC_LEN +
129			    EAP_PAX_ICV_LEN, EAP_CODE_REQUEST, id);
130	if (req == NULL) {
131		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to allocate memory "
132			   "request");
133		data->state = FAILURE;
134		return NULL;
135	}
136
137	pax = wpabuf_put(req, sizeof(*pax));
138	pax->op_code = EAP_PAX_OP_STD_3;
139	pax->flags = 0;
140	pax->mac_id = data->mac_id;
141	pax->dh_group_id = EAP_PAX_DH_GROUP_NONE;
142	pax->public_key_id = EAP_PAX_PUBLIC_KEY_NONE;
143
144	wpabuf_put_be16(req, EAP_PAX_MAC_LEN);
145	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
146	eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
147		    data->rand.r.y, EAP_PAX_RAND_LEN,
148		    (u8 *) data->cid, data->cid_len, NULL, 0, pos);
149	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(B, CID)",
150		    pos, EAP_PAX_MAC_LEN);
151	pos += EAP_PAX_MAC_LEN;
152
153	/* Optional ADE could be added here, if needed */
154
155	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
156	eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
157		    wpabuf_mhead(req), wpabuf_len(req) - EAP_PAX_ICV_LEN,
158		    NULL, 0, NULL, 0, pos);
159	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
160
161	return req;
162}
163
164
165static struct wpabuf * eap_pax_buildReq(struct eap_sm *sm, void *priv, u8 id)
166{
167	struct eap_pax_data *data = priv;
168
169	switch (data->state) {
170	case PAX_STD_1:
171		return eap_pax_build_std_1(sm, data, id);
172	case PAX_STD_3:
173		return eap_pax_build_std_3(sm, data, id);
174	default:
175		wpa_printf(MSG_DEBUG, "EAP-PAX: Unknown state %d in buildReq",
176			   data->state);
177		break;
178	}
179	return NULL;
180}
181
182
183static Boolean eap_pax_check(struct eap_sm *sm, void *priv,
184			     struct wpabuf *respData)
185{
186	struct eap_pax_data *data = priv;
187	struct eap_pax_hdr *resp;
188	const u8 *pos;
189	size_t len, mlen;
190	u8 icvbuf[EAP_PAX_ICV_LEN], *icv;
191
192	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
193	if (pos == NULL || len < sizeof(*resp)) {
194		wpa_printf(MSG_INFO, "EAP-PAX: Invalid frame");
195		return TRUE;
196	}
197
198	mlen = sizeof(struct eap_hdr) + 1 + len;
199	resp = (struct eap_pax_hdr *) pos;
200
201	wpa_printf(MSG_DEBUG, "EAP-PAX: received frame: op_code 0x%x "
202		   "flags 0x%x mac_id 0x%x dh_group_id 0x%x "
203		   "public_key_id 0x%x",
204		   resp->op_code, resp->flags, resp->mac_id, resp->dh_group_id,
205		   resp->public_key_id);
206	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: received payload",
207		    (u8 *) (resp + 1), len - sizeof(*resp) - EAP_PAX_ICV_LEN);
208
209	if (data->state == PAX_STD_1 &&
210	    resp->op_code != EAP_PAX_OP_STD_2) {
211		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected PAX_STD-2 - "
212			   "ignore op %d", resp->op_code);
213		return TRUE;
214	}
215
216	if (data->state == PAX_STD_3 &&
217	    resp->op_code != EAP_PAX_OP_ACK) {
218		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected PAX-ACK - "
219			   "ignore op %d", resp->op_code);
220		return TRUE;
221	}
222
223	if (resp->op_code != EAP_PAX_OP_STD_2 &&
224	    resp->op_code != EAP_PAX_OP_ACK) {
225		wpa_printf(MSG_DEBUG, "EAP-PAX: Unknown op_code 0x%x",
226			   resp->op_code);
227	}
228
229	if (data->mac_id != resp->mac_id) {
230		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected MAC ID 0x%x, "
231			   "received 0x%x", data->mac_id, resp->mac_id);
232		return TRUE;
233	}
234
235	if (resp->dh_group_id != EAP_PAX_DH_GROUP_NONE) {
236		wpa_printf(MSG_INFO, "EAP-PAX: Expected DH Group ID 0x%x, "
237			   "received 0x%x", EAP_PAX_DH_GROUP_NONE,
238			   resp->dh_group_id);
239		return TRUE;
240	}
241
242	if (resp->public_key_id != EAP_PAX_PUBLIC_KEY_NONE) {
243		wpa_printf(MSG_INFO, "EAP-PAX: Expected Public Key ID 0x%x, "
244			   "received 0x%x", EAP_PAX_PUBLIC_KEY_NONE,
245			   resp->public_key_id);
246		return TRUE;
247	}
248
249	if (resp->flags & EAP_PAX_FLAGS_MF) {
250		/* TODO: add support for reassembling fragments */
251		wpa_printf(MSG_INFO, "EAP-PAX: fragmentation not supported");
252		return TRUE;
253	}
254
255	if (resp->flags & EAP_PAX_FLAGS_CE) {
256		wpa_printf(MSG_INFO, "EAP-PAX: Unexpected CE flag");
257		return TRUE;
258	}
259
260	if (data->keys_set) {
261		if (len - sizeof(*resp) < EAP_PAX_ICV_LEN) {
262			wpa_printf(MSG_INFO, "EAP-PAX: No ICV in the packet");
263			return TRUE;
264		}
265		icv = wpabuf_mhead_u8(respData) + mlen - EAP_PAX_ICV_LEN;
266		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", icv, EAP_PAX_ICV_LEN);
267		eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
268			    wpabuf_mhead(respData),
269			    wpabuf_len(respData) - EAP_PAX_ICV_LEN,
270			    NULL, 0, NULL, 0, icvbuf);
271		if (os_memcmp(icvbuf, icv, EAP_PAX_ICV_LEN) != 0) {
272			wpa_printf(MSG_INFO, "EAP-PAX: Invalid ICV");
273			wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected ICV",
274				    icvbuf, EAP_PAX_ICV_LEN);
275			return TRUE;
276		}
277	}
278
279	return FALSE;
280}
281
282
283static void eap_pax_process_std_2(struct eap_sm *sm,
284				  struct eap_pax_data *data,
285				  struct wpabuf *respData)
286{
287	struct eap_pax_hdr *resp;
288	u8 mac[EAP_PAX_MAC_LEN], icvbuf[EAP_PAX_ICV_LEN];
289	const u8 *pos;
290	size_t len, left;
291	int i;
292
293	if (data->state != PAX_STD_1)
294		return;
295
296	wpa_printf(MSG_DEBUG, "EAP-PAX: Received PAX_STD-2");
297
298	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
299	if (pos == NULL || len < sizeof(*resp) + EAP_PAX_ICV_LEN)
300		return;
301
302	resp = (struct eap_pax_hdr *) pos;
303	pos = (u8 *) (resp + 1);
304	left = len - sizeof(*resp);
305
306	if (left < 2 + EAP_PAX_RAND_LEN ||
307	    WPA_GET_BE16(pos) != EAP_PAX_RAND_LEN) {
308		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (B)");
309		return;
310	}
311	pos += 2;
312	left -= 2;
313	os_memcpy(data->rand.r.y, pos, EAP_PAX_RAND_LEN);
314	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Y (client rand)",
315		    data->rand.r.y, EAP_PAX_RAND_LEN);
316	pos += EAP_PAX_RAND_LEN;
317	left -= EAP_PAX_RAND_LEN;
318
319	if (left < 2 || (size_t) 2 + WPA_GET_BE16(pos) > left) {
320		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (CID)");
321		return;
322	}
323	data->cid_len = WPA_GET_BE16(pos);
324	os_free(data->cid);
325	data->cid = os_malloc(data->cid_len);
326	if (data->cid == NULL) {
327		wpa_printf(MSG_INFO, "EAP-PAX: Failed to allocate memory for "
328			   "CID");
329		return;
330	}
331	os_memcpy(data->cid, pos + 2, data->cid_len);
332	pos += 2 + data->cid_len;
333	left -= 2 + data->cid_len;
334	wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PAX: CID",
335			  (u8 *) data->cid, data->cid_len);
336
337	if (left < 2 + EAP_PAX_MAC_LEN ||
338	    WPA_GET_BE16(pos) != EAP_PAX_MAC_LEN) {
339		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (MAC_CK)");
340		return;
341	}
342	pos += 2;
343	left -= 2;
344	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(A, B, CID)",
345		    pos, EAP_PAX_MAC_LEN);
346
347	if (eap_user_get(sm, (u8 *) data->cid, data->cid_len, 0) < 0) {
348		wpa_hexdump_ascii(MSG_DEBUG, "EAP-PAX: unknown CID",
349				  (u8 *) data->cid, data->cid_len);
350		data->state = FAILURE;
351		return;
352	}
353
354	for (i = 0;
355	     i < EAP_MAX_METHODS &&
356		     (sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
357		      sm->user->methods[i].method != EAP_TYPE_NONE);
358	     i++) {
359		if (sm->user->methods[i].vendor == EAP_VENDOR_IETF &&
360		    sm->user->methods[i].method == EAP_TYPE_PAX)
361			break;
362	}
363
364	if (i >= EAP_MAX_METHODS ||
365	    sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
366	    sm->user->methods[i].method != EAP_TYPE_PAX) {
367		wpa_hexdump_ascii(MSG_DEBUG,
368				  "EAP-PAX: EAP-PAX not enabled for CID",
369				  (u8 *) data->cid, data->cid_len);
370		data->state = FAILURE;
371		return;
372	}
373
374	if (sm->user->password == NULL ||
375	    sm->user->password_len != EAP_PAX_AK_LEN) {
376		wpa_hexdump_ascii(MSG_DEBUG, "EAP-PAX: invalid password in "
377				  "user database for CID",
378				  (u8 *) data->cid, data->cid_len);
379		data->state = FAILURE;
380		return;
381	}
382	os_memcpy(data->ak, sm->user->password, EAP_PAX_AK_LEN);
383
384	if (eap_pax_initial_key_derivation(data->mac_id, data->ak,
385					   data->rand.e, data->mk, data->ck,
386					   data->ick) < 0) {
387		wpa_printf(MSG_INFO, "EAP-PAX: Failed to complete initial "
388			   "key derivation");
389		data->state = FAILURE;
390		return;
391	}
392	data->keys_set = 1;
393
394	eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
395		    data->rand.r.x, EAP_PAX_RAND_LEN,
396		    data->rand.r.y, EAP_PAX_RAND_LEN,
397		    (u8 *) data->cid, data->cid_len, mac);
398	if (os_memcmp(mac, pos, EAP_PAX_MAC_LEN) != 0) {
399		wpa_printf(MSG_INFO, "EAP-PAX: Invalid MAC_CK(A, B, CID) in "
400			   "PAX_STD-2");
401		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected MAC_CK(A, B, CID)",
402			    mac, EAP_PAX_MAC_LEN);
403		data->state = FAILURE;
404		return;
405	}
406
407	pos += EAP_PAX_MAC_LEN;
408	left -= EAP_PAX_MAC_LEN;
409
410	if (left < EAP_PAX_ICV_LEN) {
411		wpa_printf(MSG_INFO, "EAP-PAX: Too short ICV (%lu) in "
412			   "PAX_STD-2", (unsigned long) left);
413		return;
414	}
415	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
416	eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
417		    wpabuf_head(respData),
418		    wpabuf_len(respData) - EAP_PAX_ICV_LEN, NULL, 0, NULL, 0,
419		    icvbuf);
420	if (os_memcmp(icvbuf, pos, EAP_PAX_ICV_LEN) != 0) {
421		wpa_printf(MSG_INFO, "EAP-PAX: Invalid ICV in PAX_STD-2");
422		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected ICV",
423			    icvbuf, EAP_PAX_ICV_LEN);
424		return;
425	}
426	pos += EAP_PAX_ICV_LEN;
427	left -= EAP_PAX_ICV_LEN;
428
429	if (left > 0) {
430		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
431			    pos, left);
432	}
433
434	data->state = PAX_STD_3;
435}
436
437
438static void eap_pax_process_ack(struct eap_sm *sm,
439				struct eap_pax_data *data,
440				struct wpabuf *respData)
441{
442	if (data->state != PAX_STD_3)
443		return;
444
445	wpa_printf(MSG_DEBUG, "EAP-PAX: Received PAX-ACK - authentication "
446		   "completed successfully");
447	data->state = SUCCESS;
448}
449
450
451static void eap_pax_process(struct eap_sm *sm, void *priv,
452			    struct wpabuf *respData)
453{
454	struct eap_pax_data *data = priv;
455	struct eap_pax_hdr *resp;
456	const u8 *pos;
457	size_t len;
458
459	if (sm->user == NULL || sm->user->password == NULL) {
460		wpa_printf(MSG_INFO, "EAP-PAX: Plaintext password not "
461			   "configured");
462		data->state = FAILURE;
463		return;
464	}
465
466	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
467	if (pos == NULL || len < sizeof(*resp))
468		return;
469
470	resp = (struct eap_pax_hdr *) pos;
471
472	switch (resp->op_code) {
473	case EAP_PAX_OP_STD_2:
474		eap_pax_process_std_2(sm, data, respData);
475		break;
476	case EAP_PAX_OP_ACK:
477		eap_pax_process_ack(sm, data, respData);
478		break;
479	}
480}
481
482
483static Boolean eap_pax_isDone(struct eap_sm *sm, void *priv)
484{
485	struct eap_pax_data *data = priv;
486	return data->state == SUCCESS || data->state == FAILURE;
487}
488
489
490static u8 * eap_pax_getKey(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 != SUCCESS)
496		return NULL;
497
498	key = os_malloc(EAP_MSK_LEN);
499	if (key == NULL)
500		return NULL;
501
502	*len = EAP_MSK_LEN;
503	eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
504		    "Master Session Key", data->rand.e, 2 * EAP_PAX_RAND_LEN,
505		    EAP_MSK_LEN, key);
506
507	return key;
508}
509
510
511static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
512{
513	struct eap_pax_data *data = priv;
514	u8 *key;
515
516	if (data->state != SUCCESS)
517		return NULL;
518
519	key = os_malloc(EAP_EMSK_LEN);
520	if (key == NULL)
521		return NULL;
522
523	*len = EAP_EMSK_LEN;
524	eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
525		    "Extended Master Session Key",
526		    data->rand.e, 2 * EAP_PAX_RAND_LEN,
527		    EAP_EMSK_LEN, key);
528
529	return key;
530}
531
532
533static Boolean eap_pax_isSuccess(struct eap_sm *sm, void *priv)
534{
535	struct eap_pax_data *data = priv;
536	return data->state == SUCCESS;
537}
538
539
540int eap_server_pax_register(void)
541{
542	struct eap_method *eap;
543	int ret;
544
545	eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
546				      EAP_VENDOR_IETF, EAP_TYPE_PAX, "PAX");
547	if (eap == NULL)
548		return -1;
549
550	eap->init = eap_pax_init;
551	eap->reset = eap_pax_reset;
552	eap->buildReq = eap_pax_buildReq;
553	eap->check = eap_pax_check;
554	eap->process = eap_pax_process;
555	eap->isDone = eap_pax_isDone;
556	eap->getKey = eap_pax_getKey;
557	eap->isSuccess = eap_pax_isSuccess;
558	eap->get_emsk = eap_pax_get_emsk;
559
560	ret = eap_server_method_register(eap);
561	if (ret)
562		eap_server_method_free(eap);
563	return ret;
564}
565