1/*
2 * RSN pre-authentication (supplicant)
3 * Copyright (c) 2003-2012, 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 "wpa.h"
13#include "eloop.h"
14#include "l2_packet/l2_packet.h"
15#include "eapol_supp/eapol_supp_sm.h"
16#include "preauth.h"
17#include "pmksa_cache.h"
18#include "wpa_i.h"
19
20
21#ifdef IEEE8021X_EAPOL
22
23#define PMKID_CANDIDATE_PRIO_SCAN 1000
24
25
26struct rsn_pmksa_candidate {
27	struct dl_list list;
28	u8 bssid[ETH_ALEN];
29	int priority;
30};
31
32
33/**
34 * pmksa_candidate_free - Free all entries in PMKSA candidate list
35 * @sm: Pointer to WPA state machine data from wpa_sm_init()
36 */
37void pmksa_candidate_free(struct wpa_sm *sm)
38{
39	struct rsn_pmksa_candidate *entry, *n;
40
41	if (sm == NULL)
42		return;
43
44	dl_list_for_each_safe(entry, n, &sm->pmksa_candidates,
45			      struct rsn_pmksa_candidate, list) {
46		dl_list_del(&entry->list);
47		os_free(entry);
48	}
49}
50
51
52static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
53				const u8 *buf, size_t len)
54{
55	struct wpa_sm *sm = ctx;
56
57	wpa_printf(MSG_DEBUG, "RX pre-auth from " MACSTR, MAC2STR(src_addr));
58	wpa_hexdump(MSG_MSGDUMP, "RX pre-auth", buf, len);
59
60	if (sm->preauth_eapol == NULL ||
61	    is_zero_ether_addr(sm->preauth_bssid) ||
62	    os_memcmp(sm->preauth_bssid, src_addr, ETH_ALEN) != 0) {
63		wpa_printf(MSG_WARNING, "RSN pre-auth frame received from "
64			   "unexpected source " MACSTR " - dropped",
65			   MAC2STR(src_addr));
66		return;
67	}
68
69	eapol_sm_rx_eapol(sm->preauth_eapol, src_addr, buf, len);
70}
71
72
73static void rsn_preauth_eapol_cb(struct eapol_sm *eapol,
74				 enum eapol_supp_result result,
75				 void *ctx)
76{
77	struct wpa_sm *sm = ctx;
78	u8 pmk[PMK_LEN];
79
80	if (result == EAPOL_SUPP_RESULT_SUCCESS) {
81		int res, pmk_len;
82		pmk_len = PMK_LEN;
83		res = eapol_sm_get_key(eapol, pmk, PMK_LEN);
84		if (res) {
85			/*
86			 * EAP-LEAP is an exception from other EAP methods: it
87			 * uses only 16-byte PMK.
88			 */
89			res = eapol_sm_get_key(eapol, pmk, 16);
90			pmk_len = 16;
91		}
92		if (res == 0) {
93			wpa_hexdump_key(MSG_DEBUG, "RSN: PMK from pre-auth",
94					pmk, pmk_len);
95			sm->pmk_len = pmk_len;
96			pmksa_cache_add(sm->pmksa, pmk, pmk_len,
97					sm->preauth_bssid, sm->own_addr,
98					sm->network_ctx,
99					WPA_KEY_MGMT_IEEE8021X);
100		} else {
101			wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
102				"RSN: failed to get master session key from "
103				"pre-auth EAPOL state machines");
104			result = EAPOL_SUPP_RESULT_FAILURE;
105		}
106	}
107
108	wpa_msg(sm->ctx->msg_ctx, MSG_INFO, "RSN: pre-authentication with "
109		MACSTR " %s", MAC2STR(sm->preauth_bssid),
110		result == EAPOL_SUPP_RESULT_SUCCESS ? "completed successfully" :
111		"failed");
112
113	rsn_preauth_deinit(sm);
114	rsn_preauth_candidate_process(sm);
115}
116
117
118static void rsn_preauth_timeout(void *eloop_ctx, void *timeout_ctx)
119{
120	struct wpa_sm *sm = eloop_ctx;
121
122	wpa_msg(sm->ctx->msg_ctx, MSG_INFO, "RSN: pre-authentication with "
123		MACSTR " timed out", MAC2STR(sm->preauth_bssid));
124	rsn_preauth_deinit(sm);
125	rsn_preauth_candidate_process(sm);
126}
127
128
129static int rsn_preauth_eapol_send(void *ctx, int type, const u8 *buf,
130				  size_t len)
131{
132	struct wpa_sm *sm = ctx;
133	u8 *msg;
134	size_t msglen;
135	int res;
136
137	/* TODO: could add l2_packet_sendmsg that allows fragments to avoid
138	 * extra copy here */
139
140	if (sm->l2_preauth == NULL)
141		return -1;
142
143	msg = wpa_sm_alloc_eapol(sm, type, buf, len, &msglen, NULL);
144	if (msg == NULL)
145		return -1;
146
147	wpa_hexdump(MSG_MSGDUMP, "TX EAPOL (preauth)", msg, msglen);
148	res = l2_packet_send(sm->l2_preauth, sm->preauth_bssid,
149			     ETH_P_RSN_PREAUTH, msg, msglen);
150	os_free(msg);
151	return res;
152}
153
154
155/**
156 * rsn_preauth_init - Start new RSN pre-authentication
157 * @sm: Pointer to WPA state machine data from wpa_sm_init()
158 * @dst: Authenticator address (BSSID) with which to preauthenticate
159 * @eap_conf: Current EAP configuration
160 * Returns: 0 on success, -1 on another pre-authentication is in progress,
161 * -2 on layer 2 packet initialization failure, -3 on EAPOL state machine
162 * initialization failure, -4 on memory allocation failure
163 *
164 * This function request an RSN pre-authentication with a given destination
165 * address. This is usually called for PMKSA candidates found from scan results
166 * or from driver reports. In addition, ctrl_iface PREAUTH command can trigger
167 * pre-authentication.
168 */
169int rsn_preauth_init(struct wpa_sm *sm, const u8 *dst,
170		     struct eap_peer_config *eap_conf)
171{
172	struct eapol_config eapol_conf;
173	struct eapol_ctx *ctx;
174
175	if (sm->preauth_eapol)
176		return -1;
177
178	wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG,
179		"RSN: starting pre-authentication with " MACSTR, MAC2STR(dst));
180
181	sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
182					ETH_P_RSN_PREAUTH,
183					rsn_preauth_receive, sm, 0);
184	if (sm->l2_preauth == NULL) {
185		wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
186			   "processing for pre-authentication");
187		return -2;
188	}
189
190	if (sm->bridge_ifname) {
191		sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
192						   sm->own_addr,
193						   ETH_P_RSN_PREAUTH,
194						   rsn_preauth_receive, sm, 0);
195		if (sm->l2_preauth_br == NULL) {
196			wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
197				   "packet processing (bridge) for "
198				   "pre-authentication");
199			return -2;
200		}
201	}
202
203	ctx = os_zalloc(sizeof(*ctx));
204	if (ctx == NULL) {
205		wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
206		return -4;
207	}
208	ctx->ctx = sm->ctx->ctx;
209	ctx->msg_ctx = sm->ctx->ctx;
210	ctx->preauth = 1;
211	ctx->cb = rsn_preauth_eapol_cb;
212	ctx->cb_ctx = sm;
213	ctx->scard_ctx = sm->scard_ctx;
214	ctx->eapol_send = rsn_preauth_eapol_send;
215	ctx->eapol_send_ctx = sm;
216	ctx->set_config_blob = sm->ctx->set_config_blob;
217	ctx->get_config_blob = sm->ctx->get_config_blob;
218
219	sm->preauth_eapol = eapol_sm_init(ctx);
220	if (sm->preauth_eapol == NULL) {
221		os_free(ctx);
222		wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
223			   "state machines for pre-authentication");
224		return -3;
225	}
226	os_memset(&eapol_conf, 0, sizeof(eapol_conf));
227	eapol_conf.accept_802_1x_keys = 0;
228	eapol_conf.required_keys = 0;
229	eapol_conf.fast_reauth = sm->fast_reauth;
230	eapol_conf.workaround = sm->eap_workaround;
231	eapol_sm_notify_config(sm->preauth_eapol, eap_conf, &eapol_conf);
232	/*
233	 * Use a shorter startPeriod with preauthentication since the first
234	 * preauth EAPOL-Start frame may end up being dropped due to race
235	 * condition in the AP between the data receive and key configuration
236	 * after the 4-Way Handshake.
237	 */
238	eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
239	os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
240
241	eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
242	/* 802.1X::portControl = Auto */
243	eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
244
245	eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
246			       rsn_preauth_timeout, sm, NULL);
247
248	return 0;
249}
250
251
252/**
253 * rsn_preauth_deinit - Abort RSN pre-authentication
254 * @sm: Pointer to WPA state machine data from wpa_sm_init()
255 *
256 * This function aborts the current RSN pre-authentication (if one is started)
257 * and frees resources allocated for it.
258 */
259void rsn_preauth_deinit(struct wpa_sm *sm)
260{
261	if (sm == NULL || !sm->preauth_eapol)
262		return;
263
264	eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
265	eapol_sm_deinit(sm->preauth_eapol);
266	sm->preauth_eapol = NULL;
267	os_memset(sm->preauth_bssid, 0, ETH_ALEN);
268
269	l2_packet_deinit(sm->l2_preauth);
270	sm->l2_preauth = NULL;
271	if (sm->l2_preauth_br) {
272		l2_packet_deinit(sm->l2_preauth_br);
273		sm->l2_preauth_br = NULL;
274	}
275}
276
277
278/**
279 * rsn_preauth_candidate_process - Process PMKSA candidates
280 * @sm: Pointer to WPA state machine data from wpa_sm_init()
281 *
282 * Go through the PMKSA candidates and start pre-authentication if a candidate
283 * without an existing PMKSA cache entry is found. Processed candidates will be
284 * removed from the list.
285 */
286void rsn_preauth_candidate_process(struct wpa_sm *sm)
287{
288	struct rsn_pmksa_candidate *candidate, *n;
289
290	if (dl_list_empty(&sm->pmksa_candidates))
291		return;
292
293	/* TODO: drop priority for old candidate entries */
294
295	wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
296		"list");
297	if (sm->preauth_eapol ||
298	    sm->proto != WPA_PROTO_RSN ||
299	    wpa_sm_get_state(sm) != WPA_COMPLETED ||
300	    (sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X &&
301	     sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SHA256)) {
302		wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: not in suitable "
303			"state for new pre-authentication");
304		return; /* invalid state for new pre-auth */
305	}
306
307	dl_list_for_each_safe(candidate, n, &sm->pmksa_candidates,
308			      struct rsn_pmksa_candidate, list) {
309		struct rsn_pmksa_cache_entry *p = NULL;
310		p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL, NULL);
311		if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
312		    (p == NULL || p->opportunistic)) {
313			wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA "
314				"candidate " MACSTR
315				" selected for pre-authentication",
316				MAC2STR(candidate->bssid));
317			dl_list_del(&candidate->list);
318			rsn_preauth_init(sm, candidate->bssid,
319					 sm->eap_conf_ctx);
320			os_free(candidate);
321			return;
322		}
323		wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA candidate "
324			MACSTR " does not need pre-authentication anymore",
325			MAC2STR(candidate->bssid));
326		/* Some drivers (e.g., NDIS) expect to get notified about the
327		 * PMKIDs again, so report the existing data now. */
328		if (p) {
329			wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
330		}
331
332		dl_list_del(&candidate->list);
333		os_free(candidate);
334	}
335	wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
336		"candidates");
337}
338
339
340/**
341 * pmksa_candidate_add - Add a new PMKSA candidate
342 * @sm: Pointer to WPA state machine data from wpa_sm_init()
343 * @bssid: BSSID (authenticator address) of the candidate
344 * @prio: Priority (the smaller number, the higher priority)
345 * @preauth: Whether the candidate AP advertises support for pre-authentication
346 *
347 * This function is used to add PMKSA candidates for RSN pre-authentication. It
348 * is called from scan result processing and from driver events for PMKSA
349 * candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
350 */
351void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
352			 int prio, int preauth)
353{
354	struct rsn_pmksa_candidate *cand, *pos;
355
356	if (sm->network_ctx && sm->proactive_key_caching)
357		pmksa_cache_get_opportunistic(sm->pmksa, sm->network_ctx,
358					      bssid);
359
360	if (!preauth) {
361		wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
362			   "preauth flag");
363		return;
364	}
365
366	/* If BSSID already on candidate list, update the priority of the old
367	 * entry. Do not override priority based on normal scan results. */
368	cand = NULL;
369	dl_list_for_each(pos, &sm->pmksa_candidates,
370			 struct rsn_pmksa_candidate, list) {
371		if (os_memcmp(pos->bssid, bssid, ETH_ALEN) == 0) {
372			cand = pos;
373			break;
374		}
375	}
376
377	if (cand) {
378		dl_list_del(&cand->list);
379		if (prio < PMKID_CANDIDATE_PRIO_SCAN)
380			cand->priority = prio;
381	} else {
382		cand = os_zalloc(sizeof(*cand));
383		if (cand == NULL)
384			return;
385		os_memcpy(cand->bssid, bssid, ETH_ALEN);
386		cand->priority = prio;
387	}
388
389	/* Add candidate to the list; order by increasing priority value. i.e.,
390	 * highest priority (smallest value) first. */
391	dl_list_for_each(pos, &sm->pmksa_candidates,
392			 struct rsn_pmksa_candidate, list) {
393		if (cand->priority <= pos->priority) {
394			dl_list_add(pos->list.prev, &cand->list);
395			cand = NULL;
396			break;
397		}
398	}
399	if (cand)
400		dl_list_add_tail(&sm->pmksa_candidates, &cand->list);
401
402	wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: added PMKSA cache "
403		"candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
404	rsn_preauth_candidate_process(sm);
405}
406
407
408/* TODO: schedule periodic scans if current AP supports preauth */
409
410/**
411 * rsn_preauth_scan_results - Start processing scan results for canditates
412 * @sm: Pointer to WPA state machine data from wpa_sm_init()
413 * Returns: 0 if ready to process results or -1 to skip processing
414 *
415 * This functions is used to notify RSN code about start of new scan results
416 * processing. The actual scan results will be provided by calling
417 * rsn_preauth_scan_result() for each BSS if this function returned 0.
418 */
419int rsn_preauth_scan_results(struct wpa_sm *sm)
420{
421	if (sm->ssid_len == 0)
422		return -1;
423
424	/*
425	 * TODO: is it ok to free all candidates? What about the entries
426	 * received from EVENT_PMKID_CANDIDATE?
427	 */
428	pmksa_candidate_free(sm);
429
430	return 0;
431}
432
433
434/**
435 * rsn_preauth_scan_result - Processing scan result for PMKSA canditates
436 * @sm: Pointer to WPA state machine data from wpa_sm_init()
437 *
438 * Add all suitable APs (Authenticators) from scan results into PMKSA
439 * candidate list.
440 */
441void rsn_preauth_scan_result(struct wpa_sm *sm, const u8 *bssid,
442			     const u8 *ssid, const u8 *rsn)
443{
444	struct wpa_ie_data ie;
445	struct rsn_pmksa_cache_entry *pmksa;
446
447	if (ssid[1] != sm->ssid_len ||
448	    os_memcmp(ssid + 2, sm->ssid, sm->ssid_len) != 0)
449		return; /* Not for the current SSID */
450
451	if (os_memcmp(bssid, sm->bssid, ETH_ALEN) == 0)
452		return; /* Ignore current AP */
453
454	if (wpa_parse_wpa_ie(rsn, 2 + rsn[1], &ie))
455		return;
456
457	pmksa = pmksa_cache_get(sm->pmksa, bssid, NULL, NULL);
458	if (pmksa && (!pmksa->opportunistic ||
459		      !(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
460		return;
461
462	/* Give less priority to candidates found from normal scan results. */
463	pmksa_candidate_add(sm, bssid, PMKID_CANDIDATE_PRIO_SCAN,
464			    ie.capabilities & WPA_CAPABILITY_PREAUTH);
465}
466
467
468#ifdef CONFIG_CTRL_IFACE
469/**
470 * rsn_preauth_get_status - Get pre-authentication status
471 * @sm: Pointer to WPA state machine data from wpa_sm_init()
472 * @buf: Buffer for status information
473 * @buflen: Maximum buffer length
474 * @verbose: Whether to include verbose status information
475 * Returns: Number of bytes written to buf.
476 *
477 * Query WPA2 pre-authentication for status information. This function fills in
478 * a text area with current status information. If the buffer (buf) is not
479 * large enough, status information will be truncated to fit the buffer.
480 */
481int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
482			   int verbose)
483{
484	char *pos = buf, *end = buf + buflen;
485	int res, ret;
486
487	if (sm->preauth_eapol) {
488		ret = os_snprintf(pos, end - pos, "Pre-authentication "
489				  "EAPOL state machines:\n");
490		if (ret < 0 || ret >= end - pos)
491			return pos - buf;
492		pos += ret;
493		res = eapol_sm_get_status(sm->preauth_eapol,
494					  pos, end - pos, verbose);
495		if (res >= 0)
496			pos += res;
497	}
498
499	return pos - buf;
500}
501#endif /* CONFIG_CTRL_IFACE */
502
503
504/**
505 * rsn_preauth_in_progress - Verify whether pre-authentication is in progress
506 * @sm: Pointer to WPA state machine data from wpa_sm_init()
507 */
508int rsn_preauth_in_progress(struct wpa_sm *sm)
509{
510	return sm->preauth_eapol != NULL;
511}
512
513#endif /* IEEE8021X_EAPOL */
514