1/*
2 * WPA Supplicant - RSN PMKSA cache
3 * Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15#include "includes.h"
16
17#include "common.h"
18#include "wpa.h"
19#include "eloop.h"
20#include "config_ssid.h"
21#include "sha1.h"
22#include "wpa_i.h"
23#include "l2_packet.h"
24#include "eapol_sm.h"
25#include "pmksa_cache.h"
26
27#if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
28
29static const int pmksa_cache_max_entries = 32;
30
31struct rsn_pmksa_cache {
32	struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
33	int pmksa_count; /* number of entries in PMKSA cache */
34	struct wpa_sm *sm; /* TODO: get rid of this reference(?) */
35
36	void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
37			int replace);
38	void *ctx;
39};
40
41
42/**
43 * rsn_pmkid - Calculate PMK identifier
44 * @pmk: Pairwise master key
45 * @pmk_len: Length of pmk in bytes
46 * @aa: Authenticator address
47 * @spa: Supplicant address
48 *
49 * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
50 * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
51 */
52static void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa,
53		      const u8 *spa, u8 *pmkid)
54{
55	char *title = "PMK Name";
56	const u8 *addr[3];
57	const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
58	unsigned char hash[SHA1_MAC_LEN];
59
60	addr[0] = (u8 *) title;
61	addr[1] = aa;
62	addr[2] = spa;
63
64	hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
65	os_memcpy(pmkid, hash, PMKID_LEN);
66}
67
68
69static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
70
71
72static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
73{
74	os_free(entry);
75}
76
77
78static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
79				   struct rsn_pmksa_cache_entry *entry,
80				   int replace)
81{
82	pmksa->pmksa_count--;
83	pmksa->free_cb(entry, pmksa->ctx, replace);
84	_pmksa_cache_free_entry(entry);
85}
86
87
88static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
89{
90	struct rsn_pmksa_cache *pmksa = eloop_ctx;
91	struct os_time now;
92
93	os_get_time(&now);
94	while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
95		struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
96		pmksa->pmksa = entry->next;
97		wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
98			   MACSTR, MAC2STR(entry->aa));
99		pmksa_cache_free_entry(pmksa, entry, 0);
100	}
101
102	pmksa_cache_set_expiration(pmksa);
103}
104
105
106static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
107{
108	struct rsn_pmksa_cache *pmksa = eloop_ctx;
109	pmksa->sm->cur_pmksa = NULL;
110	eapol_sm_request_reauth(pmksa->sm->eapol);
111}
112
113
114static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
115{
116	int sec;
117	struct rsn_pmksa_cache_entry *entry;
118	struct os_time now;
119
120	eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
121	eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
122	if (pmksa->pmksa == NULL)
123		return;
124	os_get_time(&now);
125	sec = pmksa->pmksa->expiration - now.sec;
126	if (sec < 0)
127		sec = 0;
128	eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
129
130	entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
131		pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
132	if (entry) {
133		sec = pmksa->pmksa->reauth_time - now.sec;
134		if (sec < 0)
135			sec = 0;
136		eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
137				       NULL);
138	}
139}
140
141
142/**
143 * pmksa_cache_add - Add a PMKSA cache entry
144 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
145 * @pmk: The new pairwise master key
146 * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
147 * @aa: Authenticator address
148 * @spa: Supplicant address
149 * @ssid: The network configuration for which this PMK is being added
150 * Returns: Pointer to the added PMKSA cache entry or %NULL on error
151 *
152 * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
153 * cache. If an old entry is already in the cache for the same Authenticator,
154 * this entry will be replaced with the new entry. PMKID will be calculated
155 * based on the PMK and the driver interface is notified of the new PMKID.
156 */
157struct rsn_pmksa_cache_entry *
158pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
159		const u8 *aa, const u8 *spa, struct wpa_ssid *ssid)
160{
161	struct rsn_pmksa_cache_entry *entry, *pos, *prev;
162	struct os_time now;
163
164	if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN)
165		return NULL;
166
167	entry = os_zalloc(sizeof(*entry));
168	if (entry == NULL)
169		return NULL;
170	os_memcpy(entry->pmk, pmk, pmk_len);
171	entry->pmk_len = pmk_len;
172	rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
173	os_get_time(&now);
174	entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
175	entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
176		pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
177	entry->akmp = WPA_KEY_MGMT_IEEE8021X;
178	os_memcpy(entry->aa, aa, ETH_ALEN);
179	entry->ssid = ssid;
180
181	/* Replace an old entry for the same Authenticator (if found) with the
182	 * new entry */
183	pos = pmksa->pmksa;
184	prev = NULL;
185	while (pos) {
186		if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
187			if (pos->pmk_len == pmk_len &&
188			    os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
189			    os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
190			    0) {
191				wpa_printf(MSG_DEBUG, "WPA: reusing previous "
192					   "PMKSA entry");
193				os_free(entry);
194				return pos;
195			}
196			if (prev == NULL)
197				pmksa->pmksa = pos->next;
198			else
199				prev->next = pos->next;
200			if (pos == pmksa->sm->cur_pmksa) {
201				/* We are about to replace the current PMKSA
202				 * cache entry. This happens when the PMKSA
203				 * caching attempt fails, so we don't want to
204				 * force pmksa_cache_free_entry() to disconnect
205				 * at this point. Let's just make sure the old
206				 * PMKSA cache entry will not be used in the
207				 * future.
208				 */
209				wpa_printf(MSG_DEBUG, "RSN: replacing current "
210					   "PMKSA entry");
211				pmksa->sm->cur_pmksa = NULL;
212			}
213			wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
214				   "the current AP");
215			pmksa_cache_free_entry(pmksa, pos, 1);
216			break;
217		}
218		prev = pos;
219		pos = pos->next;
220	}
221
222	if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
223		/* Remove the oldest entry to make room for the new entry */
224		pos = pmksa->pmksa;
225		pmksa->pmksa = pos->next;
226		wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
227			   "entry (for " MACSTR ") to make room for new one",
228			   MAC2STR(pos->aa));
229		wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
230		pmksa_cache_free_entry(pmksa, pos, 0);
231	}
232
233	/* Add the new entry; order by expiration time */
234	pos = pmksa->pmksa;
235	prev = NULL;
236	while (pos) {
237		if (pos->expiration > entry->expiration)
238			break;
239		prev = pos;
240		pos = pos->next;
241	}
242	if (prev == NULL) {
243		entry->next = pmksa->pmksa;
244		pmksa->pmksa = entry;
245		pmksa_cache_set_expiration(pmksa);
246	} else {
247		entry->next = prev->next;
248		prev->next = entry;
249	}
250	pmksa->pmksa_count++;
251	wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
252		   MAC2STR(entry->aa));
253	wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
254
255	return entry;
256}
257
258
259/**
260 * pmksa_cache_deinit - Free all entries in PMKSA cache
261 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
262 */
263void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
264{
265	struct rsn_pmksa_cache_entry *entry, *prev;
266
267	if (pmksa == NULL)
268		return;
269
270	entry = pmksa->pmksa;
271	pmksa->pmksa = NULL;
272	while (entry) {
273		prev = entry;
274		entry = entry->next;
275		os_free(prev);
276	}
277	pmksa_cache_set_expiration(pmksa);
278	os_free(pmksa);
279}
280
281
282/**
283 * pmksa_cache_get - Fetch a PMKSA cache entry
284 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
285 * @aa: Authenticator address or %NULL to match any
286 * @pmkid: PMKID or %NULL to match any
287 * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
288 */
289struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
290					       const u8 *aa, const u8 *pmkid)
291{
292	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
293	while (entry) {
294		if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
295		    (pmkid == NULL ||
296		     os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
297			return entry;
298		entry = entry->next;
299	}
300	return NULL;
301}
302
303
304/**
305 * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
306 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
307 *
308 * Clear references to old data structures when wpa_supplicant is reconfigured.
309 */
310void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
311{
312	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
313	while (entry) {
314		entry->ssid = NULL;
315		entry = entry->next;
316	}
317}
318
319
320static struct rsn_pmksa_cache_entry *
321pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
322			const struct rsn_pmksa_cache_entry *old_entry,
323			const u8 *aa)
324{
325	struct rsn_pmksa_cache_entry *new_entry;
326
327	new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
328				    aa, pmksa->sm->own_addr, old_entry->ssid);
329	if (new_entry == NULL)
330		return NULL;
331
332	/* TODO: reorder entries based on expiration time? */
333	new_entry->expiration = old_entry->expiration;
334	new_entry->opportunistic = 1;
335
336	return new_entry;
337}
338
339
340/**
341 * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
342 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
343 * @ssid: Pointer to the current network configuration
344 * @aa: Authenticator address for the new AP
345 * Returns: Pointer to a new PMKSA cache entry or %NULL if not available
346 *
347 * Try to create a new PMKSA cache entry opportunistically by guessing that the
348 * new AP is sharing the same PMK as another AP that has the same SSID and has
349 * already an entry in PMKSA cache.
350 */
351struct rsn_pmksa_cache_entry *
352pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa,
353			      struct wpa_ssid *ssid, const u8 *aa)
354{
355	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
356
357	if (ssid == NULL)
358		return NULL;
359	while (entry) {
360		if (entry->ssid == ssid) {
361			entry = pmksa_cache_clone_entry(pmksa, entry, aa);
362			if (entry) {
363				wpa_printf(MSG_DEBUG, "RSN: added "
364					   "opportunistic PMKSA cache entry "
365					   "for " MACSTR, MAC2STR(aa));
366			}
367			return entry;
368		}
369		entry = entry->next;
370	}
371	return NULL;
372}
373
374
375/**
376 * pmksa_cache_get_current - Get the current used PMKSA entry
377 * @sm: Pointer to WPA state machine data from wpa_sm_init()
378 * Returns: Pointer to the current PMKSA cache entry or %NULL if not available
379 */
380struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
381{
382	if (sm == NULL)
383		return NULL;
384	return sm->cur_pmksa;
385}
386
387
388/**
389 * pmksa_cache_clear_current - Clear the current PMKSA entry selection
390 * @sm: Pointer to WPA state machine data from wpa_sm_init()
391 */
392void pmksa_cache_clear_current(struct wpa_sm *sm)
393{
394	if (sm == NULL)
395		return;
396	sm->cur_pmksa = NULL;
397}
398
399
400/**
401 * pmksa_cache_set_current - Set the current PMKSA entry selection
402 * @sm: Pointer to WPA state machine data from wpa_sm_init()
403 * @pmkid: PMKID for selecting PMKSA or %NULL if not used
404 * @bssid: BSSID for PMKSA or %NULL if not used
405 * @ssid: The network configuration for the current network
406 * @try_opportunistic: Whether to allow opportunistic PMKSA caching
407 * Returns: 0 if PMKSA was found or -1 if no matching entry was found
408 */
409int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
410			    const u8 *bssid, struct wpa_ssid *ssid,
411			    int try_opportunistic)
412{
413	struct rsn_pmksa_cache *pmksa = sm->pmksa;
414	sm->cur_pmksa = NULL;
415	if (pmkid)
416		sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
417	if (sm->cur_pmksa == NULL && bssid)
418		sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
419	if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
420		sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa, ssid,
421							      bssid);
422	if (sm->cur_pmksa) {
423		wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
424			    sm->cur_pmksa->pmkid, PMKID_LEN);
425		return 0;
426	}
427	return -1;
428}
429
430
431/**
432 * pmksa_cache_list - Dump text list of entries in PMKSA cache
433 * @sm: Pointer to WPA state machine data from wpa_sm_init()
434 * @buf: Buffer for the list
435 * @len: Length of the buffer
436 * Returns: number of bytes written to buffer
437 *
438 * This function is used to generate a text format representation of the
439 * current PMKSA cache contents for the ctrl_iface PMKSA command.
440 */
441int pmksa_cache_list(struct wpa_sm *sm, char *buf, size_t len)
442{
443	int i, ret;
444	char *pos = buf;
445	struct rsn_pmksa_cache_entry *entry;
446	struct os_time now;
447
448	os_get_time(&now);
449	ret = os_snprintf(pos, buf + len - pos,
450			  "Index / AA / PMKID / expiration (in seconds) / "
451			  "opportunistic\n");
452	if (ret < 0 || ret >= buf + len - pos)
453		return pos - buf;
454	pos += ret;
455	i = 0;
456	entry = sm->pmksa->pmksa;
457	while (entry) {
458		i++;
459		ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
460				  i, MAC2STR(entry->aa));
461		if (ret < 0 || ret >= buf + len - pos)
462			return pos - buf;
463		pos += ret;
464		pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
465					PMKID_LEN);
466		ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
467				  (int) (entry->expiration - now.sec),
468				  entry->opportunistic);
469		if (ret < 0 || ret >= buf + len - pos)
470			return pos - buf;
471		pos += ret;
472		entry = entry->next;
473	}
474	return pos - buf;
475}
476
477
478/**
479 * pmksa_cache_init - Initialize PMKSA cache
480 * @free_cb: Callback function to be called when a PMKSA cache entry is freed
481 * @ctx: Context pointer for free_cb function
482 * @sm: Pointer to WPA state machine data from wpa_sm_init()
483 * Returns: Pointer to PMKSA cache data or %NULL on failure
484 */
485struct rsn_pmksa_cache *
486pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
487				 void *ctx, int replace),
488		 void *ctx, struct wpa_sm *sm)
489{
490	struct rsn_pmksa_cache *pmksa;
491
492	pmksa = os_zalloc(sizeof(*pmksa));
493	if (pmksa) {
494		pmksa->free_cb = free_cb;
495		pmksa->ctx = ctx;
496		pmksa->sm = sm;
497	}
498
499	return pmksa;
500}
501
502#endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
503