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      1 /*
      2  * WPA Supplicant - RSN PMKSA cache
      3  * Copyright (c) 2004-2008, Jouni Malinen <j (at) 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 "eloop.h"
     19 #include "eapol_supp/eapol_supp_sm.h"
     20 #include "wpa.h"
     21 #include "wpa_i.h"
     22 #include "pmksa_cache.h"
     23 
     24 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
     25 
     26 static const int pmksa_cache_max_entries = 32;
     27 
     28 struct rsn_pmksa_cache {
     29 	struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
     30 	int pmksa_count; /* number of entries in PMKSA cache */
     31 	struct wpa_sm *sm; /* TODO: get rid of this reference(?) */
     32 
     33 	void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
     34 			int replace);
     35 	void *ctx;
     36 };
     37 
     38 
     39 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
     40 
     41 
     42 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
     43 {
     44 	os_free(entry);
     45 }
     46 
     47 
     48 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
     49 				   struct rsn_pmksa_cache_entry *entry,
     50 				   int replace)
     51 {
     52 	pmksa->pmksa_count--;
     53 	pmksa->free_cb(entry, pmksa->ctx, replace);
     54 	_pmksa_cache_free_entry(entry);
     55 }
     56 
     57 
     58 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
     59 {
     60 	struct rsn_pmksa_cache *pmksa = eloop_ctx;
     61 	struct os_time now;
     62 
     63 	os_get_time(&now);
     64 	while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
     65 		struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
     66 		pmksa->pmksa = entry->next;
     67 		wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
     68 			   MACSTR, MAC2STR(entry->aa));
     69 		pmksa_cache_free_entry(pmksa, entry, 0);
     70 	}
     71 
     72 	pmksa_cache_set_expiration(pmksa);
     73 }
     74 
     75 
     76 static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
     77 {
     78 	struct rsn_pmksa_cache *pmksa = eloop_ctx;
     79 	pmksa->sm->cur_pmksa = NULL;
     80 	eapol_sm_request_reauth(pmksa->sm->eapol);
     81 }
     82 
     83 
     84 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
     85 {
     86 	int sec;
     87 	struct rsn_pmksa_cache_entry *entry;
     88 	struct os_time now;
     89 
     90 	eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
     91 	eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
     92 	if (pmksa->pmksa == NULL)
     93 		return;
     94 	os_get_time(&now);
     95 	sec = pmksa->pmksa->expiration - now.sec;
     96 	if (sec < 0)
     97 		sec = 0;
     98 	eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
     99 
    100 	entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
    101 		pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
    102 	if (entry) {
    103 		sec = pmksa->pmksa->reauth_time - now.sec;
    104 		if (sec < 0)
    105 			sec = 0;
    106 		eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
    107 				       NULL);
    108 	}
    109 }
    110 
    111 
    112 /**
    113  * pmksa_cache_add - Add a PMKSA cache entry
    114  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    115  * @pmk: The new pairwise master key
    116  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
    117  * @aa: Authenticator address
    118  * @spa: Supplicant address
    119  * @network_ctx: Network configuration context for this PMK
    120  * @akmp: WPA_KEY_MGMT_* used in key derivation
    121  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
    122  *
    123  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
    124  * cache. If an old entry is already in the cache for the same Authenticator,
    125  * this entry will be replaced with the new entry. PMKID will be calculated
    126  * based on the PMK and the driver interface is notified of the new PMKID.
    127  */
    128 struct rsn_pmksa_cache_entry *
    129 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
    130 		const u8 *aa, const u8 *spa, void *network_ctx, int akmp)
    131 {
    132 	struct rsn_pmksa_cache_entry *entry, *pos, *prev;
    133 	struct os_time now;
    134 
    135 	if (pmk_len > PMK_LEN)
    136 		return NULL;
    137 
    138 	entry = os_zalloc(sizeof(*entry));
    139 	if (entry == NULL)
    140 		return NULL;
    141 	os_memcpy(entry->pmk, pmk, pmk_len);
    142 	entry->pmk_len = pmk_len;
    143 	rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid,
    144 		  wpa_key_mgmt_sha256(akmp));
    145 	os_get_time(&now);
    146 	entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
    147 	entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
    148 		pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
    149 	entry->akmp = akmp;
    150 	os_memcpy(entry->aa, aa, ETH_ALEN);
    151 	entry->network_ctx = network_ctx;
    152 
    153 	/* Replace an old entry for the same Authenticator (if found) with the
    154 	 * new entry */
    155 	pos = pmksa->pmksa;
    156 	prev = NULL;
    157 	while (pos) {
    158 		if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
    159 			if (pos->pmk_len == pmk_len &&
    160 			    os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
    161 			    os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
    162 			    0) {
    163 				wpa_printf(MSG_DEBUG, "WPA: reusing previous "
    164 					   "PMKSA entry");
    165 				os_free(entry);
    166 				return pos;
    167 			}
    168 			if (prev == NULL)
    169 				pmksa->pmksa = pos->next;
    170 			else
    171 				prev->next = pos->next;
    172 			if (pos == pmksa->sm->cur_pmksa) {
    173 				/* We are about to replace the current PMKSA
    174 				 * cache entry. This happens when the PMKSA
    175 				 * caching attempt fails, so we don't want to
    176 				 * force pmksa_cache_free_entry() to disconnect
    177 				 * at this point. Let's just make sure the old
    178 				 * PMKSA cache entry will not be used in the
    179 				 * future.
    180 				 */
    181 				wpa_printf(MSG_DEBUG, "RSN: replacing current "
    182 					   "PMKSA entry");
    183 				pmksa->sm->cur_pmksa = NULL;
    184 			}
    185 			wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
    186 				   "the current AP");
    187 			pmksa_cache_free_entry(pmksa, pos, 1);
    188 			break;
    189 		}
    190 		prev = pos;
    191 		pos = pos->next;
    192 	}
    193 
    194 	if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
    195 		/* Remove the oldest entry to make room for the new entry */
    196 		pos = pmksa->pmksa;
    197 		pmksa->pmksa = pos->next;
    198 		wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
    199 			   "entry (for " MACSTR ") to make room for new one",
    200 			   MAC2STR(pos->aa));
    201 		wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
    202 		pmksa_cache_free_entry(pmksa, pos, 0);
    203 	}
    204 
    205 	/* Add the new entry; order by expiration time */
    206 	pos = pmksa->pmksa;
    207 	prev = NULL;
    208 	while (pos) {
    209 		if (pos->expiration > entry->expiration)
    210 			break;
    211 		prev = pos;
    212 		pos = pos->next;
    213 	}
    214 	if (prev == NULL) {
    215 		entry->next = pmksa->pmksa;
    216 		pmksa->pmksa = entry;
    217 		pmksa_cache_set_expiration(pmksa);
    218 	} else {
    219 		entry->next = prev->next;
    220 		prev->next = entry;
    221 	}
    222 	pmksa->pmksa_count++;
    223 	wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
    224 		   MAC2STR(entry->aa));
    225 	wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
    226 
    227 	return entry;
    228 }
    229 
    230 
    231 /**
    232  * pmksa_cache_deinit - Free all entries in PMKSA cache
    233  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    234  */
    235 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
    236 {
    237 	struct rsn_pmksa_cache_entry *entry, *prev;
    238 
    239 	if (pmksa == NULL)
    240 		return;
    241 
    242 	entry = pmksa->pmksa;
    243 	pmksa->pmksa = NULL;
    244 	while (entry) {
    245 		prev = entry;
    246 		entry = entry->next;
    247 		os_free(prev);
    248 	}
    249 	pmksa_cache_set_expiration(pmksa);
    250 	os_free(pmksa);
    251 }
    252 
    253 
    254 /**
    255  * pmksa_cache_get - Fetch a PMKSA cache entry
    256  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    257  * @aa: Authenticator address or %NULL to match any
    258  * @pmkid: PMKID or %NULL to match any
    259  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
    260  */
    261 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
    262 					       const u8 *aa, const u8 *pmkid)
    263 {
    264 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
    265 	while (entry) {
    266 		if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
    267 		    (pmkid == NULL ||
    268 		     os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
    269 			return entry;
    270 		entry = entry->next;
    271 	}
    272 	return NULL;
    273 }
    274 
    275 
    276 /**
    277  * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
    278  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    279  *
    280  * Clear references to old data structures when wpa_supplicant is reconfigured.
    281  */
    282 void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
    283 {
    284 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
    285 	while (entry) {
    286 		entry->network_ctx = NULL;
    287 		entry = entry->next;
    288 	}
    289 }
    290 
    291 
    292 static struct rsn_pmksa_cache_entry *
    293 pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
    294 			const struct rsn_pmksa_cache_entry *old_entry,
    295 			const u8 *aa)
    296 {
    297 	struct rsn_pmksa_cache_entry *new_entry;
    298 
    299 	new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
    300 				    aa, pmksa->sm->own_addr,
    301 				    old_entry->network_ctx, old_entry->akmp);
    302 	if (new_entry == NULL)
    303 		return NULL;
    304 
    305 	/* TODO: reorder entries based on expiration time? */
    306 	new_entry->expiration = old_entry->expiration;
    307 	new_entry->opportunistic = 1;
    308 
    309 	return new_entry;
    310 }
    311 
    312 
    313 /**
    314  * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
    315  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    316  * @network_ctx: Network configuration context
    317  * @aa: Authenticator address for the new AP
    318  * Returns: Pointer to a new PMKSA cache entry or %NULL if not available
    319  *
    320  * Try to create a new PMKSA cache entry opportunistically by guessing that the
    321  * new AP is sharing the same PMK as another AP that has the same SSID and has
    322  * already an entry in PMKSA cache.
    323  */
    324 struct rsn_pmksa_cache_entry *
    325 pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, void *network_ctx,
    326 			      const u8 *aa)
    327 {
    328 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
    329 
    330 	if (network_ctx == NULL)
    331 		return NULL;
    332 	while (entry) {
    333 		if (entry->network_ctx == network_ctx) {
    334 			entry = pmksa_cache_clone_entry(pmksa, entry, aa);
    335 			if (entry) {
    336 				wpa_printf(MSG_DEBUG, "RSN: added "
    337 					   "opportunistic PMKSA cache entry "
    338 					   "for " MACSTR, MAC2STR(aa));
    339 			}
    340 			return entry;
    341 		}
    342 		entry = entry->next;
    343 	}
    344 	return NULL;
    345 }
    346 
    347 
    348 /**
    349  * pmksa_cache_get_current - Get the current used PMKSA entry
    350  * @sm: Pointer to WPA state machine data from wpa_sm_init()
    351  * Returns: Pointer to the current PMKSA cache entry or %NULL if not available
    352  */
    353 struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
    354 {
    355 	if (sm == NULL)
    356 		return NULL;
    357 	return sm->cur_pmksa;
    358 }
    359 
    360 
    361 /**
    362  * pmksa_cache_clear_current - Clear the current PMKSA entry selection
    363  * @sm: Pointer to WPA state machine data from wpa_sm_init()
    364  */
    365 void pmksa_cache_clear_current(struct wpa_sm *sm)
    366 {
    367 	if (sm == NULL)
    368 		return;
    369 	sm->cur_pmksa = NULL;
    370 }
    371 
    372 
    373 /**
    374  * pmksa_cache_set_current - Set the current PMKSA entry selection
    375  * @sm: Pointer to WPA state machine data from wpa_sm_init()
    376  * @pmkid: PMKID for selecting PMKSA or %NULL if not used
    377  * @bssid: BSSID for PMKSA or %NULL if not used
    378  * @network_ctx: Network configuration context
    379  * @try_opportunistic: Whether to allow opportunistic PMKSA caching
    380  * Returns: 0 if PMKSA was found or -1 if no matching entry was found
    381  */
    382 int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
    383 			    const u8 *bssid, void *network_ctx,
    384 			    int try_opportunistic)
    385 {
    386 	struct rsn_pmksa_cache *pmksa = sm->pmksa;
    387 	sm->cur_pmksa = NULL;
    388 	if (pmkid)
    389 		sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
    390 	if (sm->cur_pmksa == NULL && bssid)
    391 		sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
    392 	if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
    393 		sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa,
    394 							      network_ctx,
    395 							      bssid);
    396 	if (sm->cur_pmksa) {
    397 		wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
    398 			    sm->cur_pmksa->pmkid, PMKID_LEN);
    399 		return 0;
    400 	}
    401 	return -1;
    402 }
    403 
    404 
    405 /**
    406  * pmksa_cache_list - Dump text list of entries in PMKSA cache
    407  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
    408  * @buf: Buffer for the list
    409  * @len: Length of the buffer
    410  * Returns: number of bytes written to buffer
    411  *
    412  * This function is used to generate a text format representation of the
    413  * current PMKSA cache contents for the ctrl_iface PMKSA command.
    414  */
    415 int pmksa_cache_list(struct rsn_pmksa_cache *pmksa, char *buf, size_t len)
    416 {
    417 	int i, ret;
    418 	char *pos = buf;
    419 	struct rsn_pmksa_cache_entry *entry;
    420 	struct os_time now;
    421 
    422 	os_get_time(&now);
    423 	ret = os_snprintf(pos, buf + len - pos,
    424 			  "Index / AA / PMKID / expiration (in seconds) / "
    425 			  "opportunistic\n");
    426 	if (ret < 0 || ret >= buf + len - pos)
    427 		return pos - buf;
    428 	pos += ret;
    429 	i = 0;
    430 	entry = pmksa->pmksa;
    431 	while (entry) {
    432 		i++;
    433 		ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
    434 				  i, MAC2STR(entry->aa));
    435 		if (ret < 0 || ret >= buf + len - pos)
    436 			return pos - buf;
    437 		pos += ret;
    438 		pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
    439 					PMKID_LEN);
    440 		ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
    441 				  (int) (entry->expiration - now.sec),
    442 				  entry->opportunistic);
    443 		if (ret < 0 || ret >= buf + len - pos)
    444 			return pos - buf;
    445 		pos += ret;
    446 		entry = entry->next;
    447 	}
    448 	return pos - buf;
    449 }
    450 
    451 
    452 /**
    453  * pmksa_cache_init - Initialize PMKSA cache
    454  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
    455  * @ctx: Context pointer for free_cb function
    456  * @sm: Pointer to WPA state machine data from wpa_sm_init()
    457  * Returns: Pointer to PMKSA cache data or %NULL on failure
    458  */
    459 struct rsn_pmksa_cache *
    460 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
    461 				 void *ctx, int replace),
    462 		 void *ctx, struct wpa_sm *sm)
    463 {
    464 	struct rsn_pmksa_cache *pmksa;
    465 
    466 	pmksa = os_zalloc(sizeof(*pmksa));
    467 	if (pmksa) {
    468 		pmksa->free_cb = free_cb;
    469 		pmksa->ctx = ctx;
    470 		pmksa->sm = sm;
    471 	}
    472 
    473 	return pmksa;
    474 }
    475 
    476 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
    477