1/*
2 * EAP-IKEv2 peer (RFC 5106)
3 * Copyright (c) 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 "eap_i.h"
13#include "eap_common/eap_ikev2_common.h"
14#include "ikev2.h"
15
16
17struct eap_ikev2_data {
18	struct ikev2_responder_data ikev2;
19	enum { WAIT_START, PROC_MSG, WAIT_FRAG_ACK, DONE, FAIL } state;
20	struct wpabuf *in_buf;
21	struct wpabuf *out_buf;
22	size_t out_used;
23	size_t fragment_size;
24	int keys_ready;
25	u8 keymat[EAP_MSK_LEN + EAP_EMSK_LEN];
26	int keymat_ok;
27};
28
29
30static const char * eap_ikev2_state_txt(int state)
31{
32	switch (state) {
33	case WAIT_START:
34		return "WAIT_START";
35	case PROC_MSG:
36		return "PROC_MSG";
37	case WAIT_FRAG_ACK:
38		return "WAIT_FRAG_ACK";
39	case DONE:
40		return "DONE";
41	case FAIL:
42		return "FAIL";
43	default:
44		return "?";
45	}
46}
47
48
49static void eap_ikev2_state(struct eap_ikev2_data *data, int state)
50{
51	wpa_printf(MSG_DEBUG, "EAP-IKEV2: %s -> %s",
52		   eap_ikev2_state_txt(data->state),
53		   eap_ikev2_state_txt(state));
54	data->state = state;
55}
56
57
58static void * eap_ikev2_init(struct eap_sm *sm)
59{
60	struct eap_ikev2_data *data;
61	const u8 *identity, *password;
62	size_t identity_len, password_len;
63
64	identity = eap_get_config_identity(sm, &identity_len);
65	if (identity == NULL) {
66		wpa_printf(MSG_INFO, "EAP-IKEV2: No identity available");
67		return NULL;
68	}
69
70	data = os_zalloc(sizeof(*data));
71	if (data == NULL)
72		return NULL;
73	data->state = WAIT_START;
74	data->fragment_size = IKEV2_FRAGMENT_SIZE;
75	data->ikev2.state = SA_INIT;
76	data->ikev2.peer_auth = PEER_AUTH_SECRET;
77	data->ikev2.key_pad = (u8 *) os_strdup("Key Pad for EAP-IKEv2");
78	if (data->ikev2.key_pad == NULL)
79		goto failed;
80	data->ikev2.key_pad_len = 21;
81	data->ikev2.IDr = os_malloc(identity_len);
82	if (data->ikev2.IDr == NULL)
83		goto failed;
84	os_memcpy(data->ikev2.IDr, identity, identity_len);
85	data->ikev2.IDr_len = identity_len;
86
87	password = eap_get_config_password(sm, &password_len);
88	if (password) {
89		data->ikev2.shared_secret = os_malloc(password_len);
90		if (data->ikev2.shared_secret == NULL)
91			goto failed;
92		os_memcpy(data->ikev2.shared_secret, password, password_len);
93		data->ikev2.shared_secret_len = password_len;
94	}
95
96	return data;
97
98failed:
99	ikev2_responder_deinit(&data->ikev2);
100	os_free(data);
101	return NULL;
102}
103
104
105static void eap_ikev2_deinit(struct eap_sm *sm, void *priv)
106{
107	struct eap_ikev2_data *data = priv;
108	wpabuf_free(data->in_buf);
109	wpabuf_free(data->out_buf);
110	ikev2_responder_deinit(&data->ikev2);
111	os_free(data);
112}
113
114
115static int eap_ikev2_peer_keymat(struct eap_ikev2_data *data)
116{
117	if (eap_ikev2_derive_keymat(
118		    data->ikev2.proposal.prf, &data->ikev2.keys,
119		    data->ikev2.i_nonce, data->ikev2.i_nonce_len,
120		    data->ikev2.r_nonce, data->ikev2.r_nonce_len,
121		    data->keymat) < 0) {
122		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to "
123			   "derive key material");
124		return -1;
125	}
126	data->keymat_ok = 1;
127	return 0;
128}
129
130
131static struct wpabuf * eap_ikev2_build_msg(struct eap_ikev2_data *data,
132					   struct eap_method_ret *ret, u8 id)
133{
134	struct wpabuf *resp;
135	u8 flags;
136	size_t send_len, plen, icv_len = 0;
137
138	ret->ignore = FALSE;
139	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Generating Response");
140	ret->allowNotifications = TRUE;
141
142	flags = 0;
143	send_len = wpabuf_len(data->out_buf) - data->out_used;
144	if (1 + send_len > data->fragment_size) {
145		send_len = data->fragment_size - 1;
146		flags |= IKEV2_FLAGS_MORE_FRAGMENTS;
147		if (data->out_used == 0) {
148			flags |= IKEV2_FLAGS_LENGTH_INCLUDED;
149			send_len -= 4;
150		}
151	}
152#ifdef CCNS_PL
153	/* Some issues figuring out the length of the message if Message Length
154	 * field not included?! */
155	if (!(flags & IKEV2_FLAGS_LENGTH_INCLUDED))
156		flags |= IKEV2_FLAGS_LENGTH_INCLUDED;
157#endif /* CCNS_PL */
158
159	plen = 1 + send_len;
160	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
161		plen += 4;
162	if (data->keys_ready) {
163		const struct ikev2_integ_alg *integ;
164		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Add Integrity Checksum "
165			   "Data");
166		flags |= IKEV2_FLAGS_ICV_INCLUDED;
167		integ = ikev2_get_integ(data->ikev2.proposal.integ);
168		if (integ == NULL) {
169			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unknown INTEG "
170				   "transform / cannot generate ICV");
171			return NULL;
172		}
173		icv_len = integ->hash_len;
174
175		plen += icv_len;
176	}
177	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, plen,
178			     EAP_CODE_RESPONSE, id);
179	if (resp == NULL)
180		return NULL;
181
182	wpabuf_put_u8(resp, flags); /* Flags */
183	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
184		wpabuf_put_be32(resp, wpabuf_len(data->out_buf));
185
186	wpabuf_put_data(resp, wpabuf_head_u8(data->out_buf) + data->out_used,
187			send_len);
188	data->out_used += send_len;
189
190	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
191		const u8 *msg = wpabuf_head(resp);
192		size_t len = wpabuf_len(resp);
193		ikev2_integ_hash(data->ikev2.proposal.integ,
194				 data->ikev2.keys.SK_ar,
195				 data->ikev2.keys.SK_integ_len,
196				 msg, len, wpabuf_put(resp, icv_len));
197	}
198
199	ret->methodState = METHOD_MAY_CONT;
200	ret->decision = DECISION_FAIL;
201
202	if (data->out_used == wpabuf_len(data->out_buf)) {
203		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
204			   "(message sent completely)",
205			   (unsigned long) send_len);
206		wpabuf_free(data->out_buf);
207		data->out_buf = NULL;
208		data->out_used = 0;
209		switch (data->ikev2.state) {
210		case SA_AUTH:
211			/* SA_INIT was sent out, so message have to be
212			 * integrity protected from now on. */
213			data->keys_ready = 1;
214			break;
215		case IKEV2_DONE:
216			ret->methodState = METHOD_DONE;
217			if (data->state == FAIL)
218				break;
219			ret->decision = DECISION_COND_SUCC;
220			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication "
221				   "completed successfully");
222			if (eap_ikev2_peer_keymat(data))
223				break;
224			eap_ikev2_state(data, DONE);
225			break;
226		case IKEV2_FAILED:
227			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication "
228				   "failed");
229			ret->methodState = METHOD_DONE;
230			ret->decision = DECISION_FAIL;
231			break;
232		default:
233			break;
234		}
235	} else {
236		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
237			   "(%lu more to send)", (unsigned long) send_len,
238			   (unsigned long) wpabuf_len(data->out_buf) -
239			   data->out_used);
240		eap_ikev2_state(data, WAIT_FRAG_ACK);
241	}
242
243	return resp;
244}
245
246
247static int eap_ikev2_process_icv(struct eap_ikev2_data *data,
248				 const struct wpabuf *reqData,
249				 u8 flags, const u8 *pos, const u8 **end)
250{
251	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
252		int icv_len = eap_ikev2_validate_icv(
253			data->ikev2.proposal.integ, &data->ikev2.keys, 1,
254			reqData, pos, *end);
255		if (icv_len < 0)
256			return -1;
257		/* Hide Integrity Checksum Data from further processing */
258		*end -= icv_len;
259	} else if (data->keys_ready) {
260		wpa_printf(MSG_INFO, "EAP-IKEV2: The message should have "
261			   "included integrity checksum");
262		return -1;
263	}
264
265	return 0;
266}
267
268
269static int eap_ikev2_process_cont(struct eap_ikev2_data *data,
270				  const u8 *buf, size_t len)
271{
272	/* Process continuation of a pending message */
273	if (len > wpabuf_tailroom(data->in_buf)) {
274		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment overflow");
275		eap_ikev2_state(data, FAIL);
276		return -1;
277	}
278
279	wpabuf_put_data(data->in_buf, buf, len);
280	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes, waiting "
281		   "for %lu bytes more", (unsigned long) len,
282		   (unsigned long) wpabuf_tailroom(data->in_buf));
283
284	return 0;
285}
286
287
288static struct wpabuf * eap_ikev2_process_fragment(struct eap_ikev2_data *data,
289						  struct eap_method_ret *ret,
290						  u8 id, u8 flags,
291						  u32 message_length,
292						  const u8 *buf, size_t len)
293{
294	/* Process a fragment that is not the last one of the message */
295	if (data->in_buf == NULL && !(flags & IKEV2_FLAGS_LENGTH_INCLUDED)) {
296		wpa_printf(MSG_DEBUG, "EAP-IKEV2: No Message Length field in "
297			   "a fragmented packet");
298		ret->ignore = TRUE;
299		return NULL;
300	}
301
302	if (data->in_buf == NULL) {
303		/* First fragment of the message */
304		data->in_buf = wpabuf_alloc(message_length);
305		if (data->in_buf == NULL) {
306			wpa_printf(MSG_DEBUG, "EAP-IKEV2: No memory for "
307				   "message");
308			ret->ignore = TRUE;
309			return NULL;
310		}
311		wpabuf_put_data(data->in_buf, buf, len);
312		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes in first "
313			   "fragment, waiting for %lu bytes more",
314			   (unsigned long) len,
315			   (unsigned long) wpabuf_tailroom(data->in_buf));
316	}
317
318	return eap_ikev2_build_frag_ack(id, EAP_CODE_RESPONSE);
319}
320
321
322static struct wpabuf * eap_ikev2_process(struct eap_sm *sm, void *priv,
323					 struct eap_method_ret *ret,
324					 const struct wpabuf *reqData)
325{
326	struct eap_ikev2_data *data = priv;
327	const u8 *start, *pos, *end;
328	size_t len;
329	u8 flags, id;
330	u32 message_length = 0;
331	struct wpabuf tmpbuf;
332
333	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, reqData, &len);
334	if (pos == NULL) {
335		ret->ignore = TRUE;
336		return NULL;
337	}
338
339	id = eap_get_id(reqData);
340
341	start = pos;
342	end = start + len;
343
344	if (len == 0)
345		flags = 0; /* fragment ack */
346	else
347		flags = *pos++;
348
349	if (eap_ikev2_process_icv(data, reqData, flags, pos, &end) < 0) {
350		ret->ignore = TRUE;
351		return NULL;
352	}
353
354	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED) {
355		if (end - pos < 4) {
356			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Message underflow");
357			ret->ignore = TRUE;
358			return NULL;
359		}
360		message_length = WPA_GET_BE32(pos);
361		pos += 4;
362
363		if (message_length < (u32) (end - pos)) {
364			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Invalid Message "
365				   "Length (%d; %ld remaining in this msg)",
366				   message_length, (long) (end - pos));
367			ret->ignore = TRUE;
368			return NULL;
369		}
370	}
371
372	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received packet: Flags 0x%x "
373		   "Message Length %u", flags, message_length);
374
375	if (data->state == WAIT_FRAG_ACK) {
376#ifdef CCNS_PL
377		if (len > 1) /* Empty Flags field included in ACK */
378#else /* CCNS_PL */
379		if (len != 0)
380#endif /* CCNS_PL */
381		{
382			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected payload "
383				   "in WAIT_FRAG_ACK state");
384			ret->ignore = TRUE;
385			return NULL;
386		}
387		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment acknowledged");
388		eap_ikev2_state(data, PROC_MSG);
389		return eap_ikev2_build_msg(data, ret, id);
390	}
391
392	if (data->in_buf && eap_ikev2_process_cont(data, pos, end - pos) < 0) {
393		ret->ignore = TRUE;
394		return NULL;
395	}
396
397	if (flags & IKEV2_FLAGS_MORE_FRAGMENTS) {
398		return eap_ikev2_process_fragment(data, ret, id, flags,
399						  message_length, pos,
400						  end - pos);
401	}
402
403	if (data->in_buf == NULL) {
404		/* Wrap unfragmented messages as wpabuf without extra copy */
405		wpabuf_set(&tmpbuf, pos, end - pos);
406		data->in_buf = &tmpbuf;
407	}
408
409	if (ikev2_responder_process(&data->ikev2, data->in_buf) < 0) {
410		if (data->in_buf == &tmpbuf)
411			data->in_buf = NULL;
412		eap_ikev2_state(data, FAIL);
413		return NULL;
414	}
415
416	if (data->in_buf != &tmpbuf)
417		wpabuf_free(data->in_buf);
418	data->in_buf = NULL;
419
420	if (data->out_buf == NULL) {
421		data->out_buf = ikev2_responder_build(&data->ikev2);
422		if (data->out_buf == NULL) {
423			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to generate "
424				   "IKEv2 message");
425			return NULL;
426		}
427		data->out_used = 0;
428	}
429
430	eap_ikev2_state(data, PROC_MSG);
431	return eap_ikev2_build_msg(data, ret, id);
432}
433
434
435static Boolean eap_ikev2_isKeyAvailable(struct eap_sm *sm, void *priv)
436{
437	struct eap_ikev2_data *data = priv;
438	return data->state == DONE && data->keymat_ok;
439}
440
441
442static u8 * eap_ikev2_getKey(struct eap_sm *sm, void *priv, size_t *len)
443{
444	struct eap_ikev2_data *data = priv;
445	u8 *key;
446
447	if (data->state != DONE || !data->keymat_ok)
448		return NULL;
449
450	key = os_malloc(EAP_MSK_LEN);
451	if (key) {
452		os_memcpy(key, data->keymat, EAP_MSK_LEN);
453		*len = EAP_MSK_LEN;
454	}
455
456	return key;
457}
458
459
460static u8 * eap_ikev2_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
461{
462	struct eap_ikev2_data *data = priv;
463	u8 *key;
464
465	if (data->state != DONE || !data->keymat_ok)
466		return NULL;
467
468	key = os_malloc(EAP_EMSK_LEN);
469	if (key) {
470		os_memcpy(key, data->keymat + EAP_MSK_LEN, EAP_EMSK_LEN);
471		*len = EAP_EMSK_LEN;
472	}
473
474	return key;
475}
476
477
478static u8 * eap_ikev2_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
479{
480	struct eap_ikev2_data *data = priv;
481	u8 *sid;
482	size_t sid_len;
483	size_t offset;
484
485	if (data->state != DONE || !data->keymat_ok)
486		return NULL;
487
488	sid_len = 1 + data->ikev2.i_nonce_len + data->ikev2.r_nonce_len;
489	sid = os_malloc(sid_len);
490	if (sid) {
491		offset = 0;
492		sid[offset] = EAP_TYPE_IKEV2;
493		offset++;
494		os_memcpy(sid + offset, data->ikev2.i_nonce,
495			  data->ikev2.i_nonce_len);
496		offset += data->ikev2.i_nonce_len;
497		os_memcpy(sid + offset, data->ikev2.r_nonce,
498			  data->ikev2.r_nonce_len);
499		*len = sid_len;
500		wpa_hexdump(MSG_DEBUG, "EAP-IKEV2: Derived Session-Id",
501			    sid, sid_len);
502	}
503
504	return sid;
505}
506
507
508int eap_peer_ikev2_register(void)
509{
510	struct eap_method *eap;
511	int ret;
512
513	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
514				    EAP_VENDOR_IETF, EAP_TYPE_IKEV2,
515				    "IKEV2");
516	if (eap == NULL)
517		return -1;
518
519	eap->init = eap_ikev2_init;
520	eap->deinit = eap_ikev2_deinit;
521	eap->process = eap_ikev2_process;
522	eap->isKeyAvailable = eap_ikev2_isKeyAvailable;
523	eap->getKey = eap_ikev2_getKey;
524	eap->get_emsk = eap_ikev2_get_emsk;
525	eap->getSessionId = eap_ikev2_get_session_id;
526
527	ret = eap_peer_method_register(eap);
528	if (ret)
529		eap_peer_method_free(eap);
530	return ret;
531}
532