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