pmksa_cache.c - platform/external/wpa_supplicant - Git at Google

 /*
  * WPA Supplicant - RSN PMKSA cache
  * Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * Alternatively, this software may be distributed under the terms of BSD
  * license.
  *
  * See README and COPYING for more details.
  */

 #include "includes.h"

 #include "common.h"
 #include "wpa.h"
 #include "eloop.h"
 #include "config_ssid.h"
 #include "sha1.h"
 #include "wpa_i.h"
 #include "l2_packet.h"
 #include "eapol_sm.h"
 #include "pmksa_cache.h"

 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)

 static const int pmksa_cache_max_entries = 32;

 struct rsn_pmksa_cache {
 	struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
 	int pmksa_count; /* number of entries in PMKSA cache */
 	struct wpa_sm *sm; /* TODO: get rid of this reference(?) */

 	void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
 			int replace);
 	void *ctx;
 };


 /**
  * rsn_pmkid - Calculate PMK identifier
  * @pmk: Pairwise master key
  * @pmk_len: Length of pmk in bytes
  * @aa: Authenticator address
  * @spa: Supplicant address
  *
  * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
  * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
  */
 static void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa,
 		      const u8 *spa, u8 *pmkid)
 {
 	char *title = "PMK Name";
 	const u8 *addr[3];
 	const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
 	unsigned char hash[SHA1_MAC_LEN];

 	addr[0] = (u8 *) title;
 	addr[1] = aa;
 	addr[2] = spa;

 	hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
 	os_memcpy(pmkid, hash, PMKID_LEN);
 }


 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);


 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
 {
 	os_free(entry);
 }


 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
 				   struct rsn_pmksa_cache_entry *entry,
 				   int replace)
 {
 	pmksa->pmksa_count--;
 	pmksa->free_cb(entry, pmksa->ctx, replace);
 	_pmksa_cache_free_entry(entry);
 }


 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
 {
 	struct rsn_pmksa_cache *pmksa = eloop_ctx;
 	struct os_time now;

 	os_get_time(&now);
 	while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
 		struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 		pmksa->pmksa = entry->next;
 		wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
 			   MACSTR, MAC2STR(entry->aa));
 		pmksa_cache_free_entry(pmksa, entry, 0);
 	}

 	pmksa_cache_set_expiration(pmksa);
 }


 static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
 {
 	struct rsn_pmksa_cache *pmksa = eloop_ctx;
 	pmksa->sm->cur_pmksa = NULL;
 	eapol_sm_request_reauth(pmksa->sm->eapol);
 }


 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
 {
 	int sec;
 	struct rsn_pmksa_cache_entry *entry;
 	struct os_time now;

 	eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 	eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
 	if (pmksa->pmksa == NULL)
 		return;
 	os_get_time(&now);
 	sec = pmksa->pmksa->expiration - now.sec;
 	if (sec < 0)
 		sec = 0;
 	eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);

 	entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
 		pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
 	if (entry) {
 		sec = pmksa->pmksa->reauth_time - now.sec;
 		if (sec < 0)
 			sec = 0;
 		eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
 				       NULL);
 	}
 }


 /**
  * pmksa_cache_add - Add a PMKSA cache entry
  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
  * @pmk: The new pairwise master key
  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
  * @aa: Authenticator address
  * @spa: Supplicant address
  * @ssid: The network configuration for which this PMK is being added
  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
  *
  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
  * cache. If an old entry is already in the cache for the same Authenticator,
  * this entry will be replaced with the new entry. PMKID will be calculated
  * based on the PMK and the driver interface is notified of the new PMKID.
  */
 struct rsn_pmksa_cache_entry *
 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
 		const u8 *aa, const u8 *spa, struct wpa_ssid *ssid)
 {
 	struct rsn_pmksa_cache_entry *entry, *pos, *prev;
 	struct os_time now;

 	if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN)
 		return NULL;

 	entry = os_zalloc(sizeof(*entry));
 	if (entry == NULL)
 		return NULL;
 	os_memcpy(entry->pmk, pmk, pmk_len);
 	entry->pmk_len = pmk_len;
 	rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
 	os_get_time(&now);
 	entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
 	entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
 		pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
 	entry->akmp = WPA_KEY_MGMT_IEEE8021X;
 	os_memcpy(entry->aa, aa, ETH_ALEN);
 	entry->ssid = ssid;

 	/* Replace an old entry for the same Authenticator (if found) with the
 	 * new entry */
 	pos = pmksa->pmksa;
 	prev = NULL;
 	while (pos) {
 		if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
 			if (pos->pmk_len == pmk_len &&
 			    os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
 			    os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
 			    0) {
 				wpa_printf(MSG_DEBUG, "WPA: reusing previous "
 					   "PMKSA entry");
 				os_free(entry);
 				return pos;
 			}
 			if (prev == NULL)
 				pmksa->pmksa = pos->next;
 			else
 				prev->next = pos->next;
 			if (pos == pmksa->sm->cur_pmksa) {
 				/* We are about to replace the current PMKSA
 				 * cache entry. This happens when the PMKSA
 				 * caching attempt fails, so we don't want to
 				 * force pmksa_cache_free_entry() to disconnect
 				 * at this point. Let's just make sure the old
 				 * PMKSA cache entry will not be used in the
 				 * future.
 				 */
 				wpa_printf(MSG_DEBUG, "RSN: replacing current "
 					   "PMKSA entry");
 				pmksa->sm->cur_pmksa = NULL;
 			}
 			wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
 				   "the current AP");
 			pmksa_cache_free_entry(pmksa, pos, 1);
 			break;
 		}
 		prev = pos;
 		pos = pos->next;
 	}

 	if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
 		/* Remove the oldest entry to make room for the new entry */
 		pos = pmksa->pmksa;
 		pmksa->pmksa = pos->next;
 		wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
 			   "entry (for " MACSTR ") to make room for new one",
 			   MAC2STR(pos->aa));
 		wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
 		pmksa_cache_free_entry(pmksa, pos, 0);
 	}

 	/* Add the new entry; order by expiration time */
 	pos = pmksa->pmksa;
 	prev = NULL;
 	while (pos) {
 		if (pos->expiration > entry->expiration)
 			break;
 		prev = pos;
 		pos = pos->next;
 	}
 	if (prev == NULL) {
 		entry->next = pmksa->pmksa;
 		pmksa->pmksa = entry;
 		pmksa_cache_set_expiration(pmksa);
 	} else {
 		entry->next = prev->next;
 		prev->next = entry;
 	}
 	pmksa->pmksa_count++;
 	wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
 		   MAC2STR(entry->aa));
 	wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);

 	return entry;
 }


 /**
  * pmksa_cache_deinit - Free all entries in PMKSA cache
  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
  */
 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
 {
 	struct rsn_pmksa_cache_entry *entry, *prev;

 	if (pmksa == NULL)
 		return;

 	entry = pmksa->pmksa;
 	pmksa->pmksa = NULL;
 	while (entry) {
 		prev = entry;
 		entry = entry->next;
 		os_free(prev);
 	}
 	pmksa_cache_set_expiration(pmksa);
 	os_free(pmksa);
 }


 /**
  * pmksa_cache_get - Fetch a PMKSA cache entry
  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
  * @aa: Authenticator address or %NULL to match any
  * @pmkid: PMKID or %NULL to match any
  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
  */
 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
 					       const u8 *aa, const u8 *pmkid)
 {
 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 	while (entry) {
 		if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
 		    (pmkid == NULL ||
 		     os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
 			return entry;
 		entry = entry->next;
 	}
 	return NULL;
 }


 /**
  * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
  *
  * Clear references to old data structures when wpa_supplicant is reconfigured.
  */
 void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
 {
 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 	while (entry) {
 		entry->ssid = NULL;
 		entry = entry->next;
 	}
 }


 static struct rsn_pmksa_cache_entry *
 pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
 			const struct rsn_pmksa_cache_entry *old_entry,
 			const u8 *aa)
 {
 	struct rsn_pmksa_cache_entry *new_entry;

 	new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
 				    aa, pmksa->sm->own_addr, old_entry->ssid);
 	if (new_entry == NULL)
 		return NULL;

 	/* TODO: reorder entries based on expiration time? */
 	new_entry->expiration = old_entry->expiration;
 	new_entry->opportunistic = 1;

 	return new_entry;
 }


 /**
  * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
  * @ssid: Pointer to the current network configuration
  * @aa: Authenticator address for the new AP
  * Returns: Pointer to a new PMKSA cache entry or %NULL if not available
  *
  * Try to create a new PMKSA cache entry opportunistically by guessing that the
  * new AP is sharing the same PMK as another AP that has the same SSID and has
  * already an entry in PMKSA cache.
  */
 struct rsn_pmksa_cache_entry *
 pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa,
 			      struct wpa_ssid *ssid, const u8 *aa)
 {
 	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;

 	if (ssid == NULL)
 		return NULL;
 	while (entry) {
 		if (entry->ssid == ssid) {
 			entry = pmksa_cache_clone_entry(pmksa, entry, aa);
 			if (entry) {
 				wpa_printf(MSG_DEBUG, "RSN: added "
 					   "opportunistic PMKSA cache entry "
 					   "for " MACSTR, MAC2STR(aa));
 			}
 			return entry;
 		}
 		entry = entry->next;
 	}
 	return NULL;
 }


 /**
  * pmksa_cache_get_current - Get the current used PMKSA entry
  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  * Returns: Pointer to the current PMKSA cache entry or %NULL if not available
  */
 struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
 {
 	if (sm == NULL)
 		return NULL;
 	return sm->cur_pmksa;
 }


 /**
  * pmksa_cache_clear_current - Clear the current PMKSA entry selection
  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  */
 void pmksa_cache_clear_current(struct wpa_sm *sm)
 {
 	if (sm == NULL)
 		return;
 	sm->cur_pmksa = NULL;
 }


 /**
  * pmksa_cache_set_current - Set the current PMKSA entry selection
  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  * @pmkid: PMKID for selecting PMKSA or %NULL if not used
  * @bssid: BSSID for PMKSA or %NULL if not used
  * @ssid: The network configuration for the current network
  * @try_opportunistic: Whether to allow opportunistic PMKSA caching
  * Returns: 0 if PMKSA was found or -1 if no matching entry was found
  */
 int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
 			    const u8 *bssid, struct wpa_ssid *ssid,
 			    int try_opportunistic)
 {
 	struct rsn_pmksa_cache *pmksa = sm->pmksa;
 	sm->cur_pmksa = NULL;
 	if (pmkid)
 		sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
 	if (sm->cur_pmksa == NULL && bssid)
 		sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
 	if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
 		sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa, ssid,
 							      bssid);
 	if (sm->cur_pmksa) {
 		wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
 			    sm->cur_pmksa->pmkid, PMKID_LEN);
 		return 0;
 	}
 	return -1;
 }


 /**
  * pmksa_cache_list - Dump text list of entries in PMKSA cache
  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  * @buf: Buffer for the list
  * @len: Length of the buffer
  * Returns: number of bytes written to buffer
  *
  * This function is used to generate a text format representation of the
  * current PMKSA cache contents for the ctrl_iface PMKSA command.
  */
 int pmksa_cache_list(struct wpa_sm *sm, char *buf, size_t len)
 {
 	int i, ret;
 	char *pos = buf;
 	struct rsn_pmksa_cache_entry *entry;
 	struct os_time now;

 	os_get_time(&now);
 	ret = os_snprintf(pos, buf + len - pos,
 			  "Index / AA / PMKID / expiration (in seconds) / "
 			  "opportunistic\n");
 	if (ret < 0 || ret >= buf + len - pos)
 		return pos - buf;
 	pos += ret;
 	i = 0;
 	entry = sm->pmksa->pmksa;
 	while (entry) {
 		i++;
 		ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
 				  i, MAC2STR(entry->aa));
 		if (ret < 0 || ret >= buf + len - pos)
 			return pos - buf;
 		pos += ret;
 		pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
 					PMKID_LEN);
 		ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
 				  (int) (entry->expiration - now.sec),
 				  entry->opportunistic);
 		if (ret < 0 || ret >= buf + len - pos)
 			return pos - buf;
 		pos += ret;
 		entry = entry->next;
 	}
 	return pos - buf;
 }


 /**
  * pmksa_cache_init - Initialize PMKSA cache
  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
  * @ctx: Context pointer for free_cb function
  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  * Returns: Pointer to PMKSA cache data or %NULL on failure
  */
 struct rsn_pmksa_cache *
 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
 				 void *ctx, int replace),
 		 void *ctx, struct wpa_sm *sm)
 {
 	struct rsn_pmksa_cache *pmksa;

 	pmksa = os_zalloc(sizeof(*pmksa));
 	if (pmksa) {
 		pmksa->free_cb = free_cb;
 		pmksa->ctx = ctx;
 		pmksa->sm = sm;
 	}

 	return pmksa;
 }

 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
	/*
	* WPA Supplicant - RSN PMKSA cache
	* Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* Alternatively, this software may be distributed under the terms of BSD
	* license.
	*
	* See README and COPYING for more details.
	*/

	#include "includes.h"

	#include "common.h"
	#include "wpa.h"
	#include "eloop.h"
	#include "config_ssid.h"
	#include "sha1.h"
	#include "wpa_i.h"
	#include "l2_packet.h"
	#include "eapol_sm.h"
	#include "pmksa_cache.h"

	#if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)

	static const int pmksa_cache_max_entries = 32;

	struct rsn_pmksa_cache {
	struct rsn_pmksa_cache_entry pmksa; / PMKSA cache */
	int pmksa_count; /* number of entries in PMKSA cache */
	struct wpa_sm sm; / TODO: get rid of this reference(?) */

	void (free_cb)(struct rsn_pmksa_cache_entry entry, void *ctx,
	int replace);
	void *ctx;
	};


	/**
	* rsn_pmkid - Calculate PMK identifier
	* @pmk: Pairwise master key
	* @pmk_len: Length of pmk in bytes
	* @aa: Authenticator address
	* @spa: Supplicant address
	*
	* IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
	* PMKID = HMAC-SHA1-128(PMK, "PMK Name" \|\| AA \|\| SPA)
	*/
	static void rsn_pmkid(const u8 pmk, size_t pmk_len, const u8 aa,
	const u8 spa, u8 pmkid)
	{
	char *title = "PMK Name";
	const u8 *addr[3];
	const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
	unsigned char hash[SHA1_MAC_LEN];

	addr[0] = (u8 *) title;
	addr[1] = aa;
	addr[2] = spa;

	hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
	os_memcpy(pmkid, hash, PMKID_LEN);
	}


	static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);


	static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
	{
	os_free(entry);
	}


	static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
	struct rsn_pmksa_cache_entry *entry,
	int replace)
	{
	pmksa->pmksa_count--;
	pmksa->free_cb(entry, pmksa->ctx, replace);
	_pmksa_cache_free_entry(entry);
	}


	static void pmksa_cache_expire(void eloop_ctx, void timeout_ctx)
	{
	struct rsn_pmksa_cache *pmksa = eloop_ctx;
	struct os_time now;

	os_get_time(&now);
	while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
	pmksa->pmksa = entry->next;
	wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
	MACSTR, MAC2STR(entry->aa));
	pmksa_cache_free_entry(pmksa, entry, 0);
	}

	pmksa_cache_set_expiration(pmksa);
	}


	static void pmksa_cache_reauth(void eloop_ctx, void timeout_ctx)
	{
	struct rsn_pmksa_cache *pmksa = eloop_ctx;
	pmksa->sm->cur_pmksa = NULL;
	eapol_sm_request_reauth(pmksa->sm->eapol);
	}


	static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
	{
	int sec;
	struct rsn_pmksa_cache_entry *entry;
	struct os_time now;

	eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
	eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
	if (pmksa->pmksa == NULL)
	return;
	os_get_time(&now);
	sec = pmksa->pmksa->expiration - now.sec;
	if (sec < 0)
	sec = 0;
	eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);

	entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
	pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
	if (entry) {
	sec = pmksa->pmksa->reauth_time - now.sec;
	if (sec < 0)
	sec = 0;
	eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
	NULL);
	}
	}


	/**
	* pmksa_cache_add - Add a PMKSA cache entry
	* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
	* @pmk: The new pairwise master key
	* @pmk_len: PMK length in bytes, usually PMK_LEN (32)
	* @aa: Authenticator address
	* @spa: Supplicant address
	* @ssid: The network configuration for which this PMK is being added
	* Returns: Pointer to the added PMKSA cache entry or %NULL on error
	*
	* This function create a PMKSA entry for a new PMK and adds it to the PMKSA
	* cache. If an old entry is already in the cache for the same Authenticator,
	* this entry will be replaced with the new entry. PMKID will be calculated
	* based on the PMK and the driver interface is notified of the new PMKID.
	*/
	struct rsn_pmksa_cache_entry *
	pmksa_cache_add(struct rsn_pmksa_cache pmksa, const u8 pmk, size_t pmk_len,
	const u8 aa, const u8 spa, struct wpa_ssid *ssid)
	{
	struct rsn_pmksa_cache_entry entry, pos, *prev;
	struct os_time now;

	if (pmksa->sm->proto != WPA_PROTO_RSN \|\| pmk_len > PMK_LEN)
	return NULL;

	entry = os_zalloc(sizeof(*entry));
	if (entry == NULL)
	return NULL;
	os_memcpy(entry->pmk, pmk, pmk_len);
	entry->pmk_len = pmk_len;
	rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
	os_get_time(&now);
	entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
	entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
	pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
	entry->akmp = WPA_KEY_MGMT_IEEE8021X;
	os_memcpy(entry->aa, aa, ETH_ALEN);
	entry->ssid = ssid;

	/* Replace an old entry for the same Authenticator (if found) with the
	* new entry */
	pos = pmksa->pmksa;
	prev = NULL;
	while (pos) {
	if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
	if (pos->pmk_len == pmk_len &&
	os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
	os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
	0) {
	wpa_printf(MSG_DEBUG, "WPA: reusing previous "
	"PMKSA entry");
	os_free(entry);
	return pos;
	}
	if (prev == NULL)
	pmksa->pmksa = pos->next;
	else
	prev->next = pos->next;
	if (pos == pmksa->sm->cur_pmksa) {
	/* We are about to replace the current PMKSA
	* cache entry. This happens when the PMKSA
	* caching attempt fails, so we don't want to
	* force pmksa_cache_free_entry() to disconnect
	* at this point. Let's just make sure the old
	* PMKSA cache entry will not be used in the
	* future.
	*/
	wpa_printf(MSG_DEBUG, "RSN: replacing current "
	"PMKSA entry");
	pmksa->sm->cur_pmksa = NULL;
	}
	wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
	"the current AP");
	pmksa_cache_free_entry(pmksa, pos, 1);
	break;
	}
	prev = pos;
	pos = pos->next;
	}

	if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
	/* Remove the oldest entry to make room for the new entry */
	pos = pmksa->pmksa;
	pmksa->pmksa = pos->next;
	wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
	"entry (for " MACSTR ") to make room for new one",
	MAC2STR(pos->aa));
	wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
	pmksa_cache_free_entry(pmksa, pos, 0);
	}

	/* Add the new entry; order by expiration time */
	pos = pmksa->pmksa;
	prev = NULL;
	while (pos) {
	if (pos->expiration > entry->expiration)
	break;
	prev = pos;
	pos = pos->next;
	}
	if (prev == NULL) {
	entry->next = pmksa->pmksa;
	pmksa->pmksa = entry;
	pmksa_cache_set_expiration(pmksa);
	} else {
	entry->next = prev->next;
	prev->next = entry;
	}
	pmksa->pmksa_count++;
	wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
	MAC2STR(entry->aa));
	wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);

	return entry;
	}


	/**
	* pmksa_cache_deinit - Free all entries in PMKSA cache
	* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
	*/
	void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
	{
	struct rsn_pmksa_cache_entry entry, prev;

	if (pmksa == NULL)
	return;

	entry = pmksa->pmksa;
	pmksa->pmksa = NULL;
	while (entry) {
	prev = entry;
	entry = entry->next;
	os_free(prev);
	}
	pmksa_cache_set_expiration(pmksa);
	os_free(pmksa);
	}


	/**
	* pmksa_cache_get - Fetch a PMKSA cache entry
	* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
	* @aa: Authenticator address or %NULL to match any
	* @pmkid: PMKID or %NULL to match any
	* Returns: Pointer to PMKSA cache entry or %NULL if no match was found
	*/
	struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
	const u8 aa, const u8 pmkid)
	{
	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
	while (entry) {
	if ((aa == NULL \|\| os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
	(pmkid == NULL \|\|
	os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
	return entry;
	entry = entry->next;
	}
	return NULL;
	}


	/**
	* pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
	* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
	*
	* Clear references to old data structures when wpa_supplicant is reconfigured.
	*/
	void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
	{
	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
	while (entry) {
	entry->ssid = NULL;
	entry = entry->next;
	}
	}


	static struct rsn_pmksa_cache_entry *
	pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
	const struct rsn_pmksa_cache_entry *old_entry,
	const u8 *aa)
	{
	struct rsn_pmksa_cache_entry *new_entry;

	new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
	aa, pmksa->sm->own_addr, old_entry->ssid);
	if (new_entry == NULL)
	return NULL;

	/* TODO: reorder entries based on expiration time? */
	new_entry->expiration = old_entry->expiration;
	new_entry->opportunistic = 1;

	return new_entry;
	}


	/**
	* pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
	* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
	* @ssid: Pointer to the current network configuration
	* @aa: Authenticator address for the new AP
	* Returns: Pointer to a new PMKSA cache entry or %NULL if not available
	*
	* Try to create a new PMKSA cache entry opportunistically by guessing that the
	* new AP is sharing the same PMK as another AP that has the same SSID and has
	* already an entry in PMKSA cache.
	*/
	struct rsn_pmksa_cache_entry *
	pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa,
	struct wpa_ssid ssid, const u8 aa)
	{
	struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;

	if (ssid == NULL)
	return NULL;
	while (entry) {
	if (entry->ssid == ssid) {
	entry = pmksa_cache_clone_entry(pmksa, entry, aa);
	if (entry) {
	wpa_printf(MSG_DEBUG, "RSN: added "
	"opportunistic PMKSA cache entry "
	"for " MACSTR, MAC2STR(aa));
	}
	return entry;
	}
	entry = entry->next;
	}
	return NULL;
	}


	/**
	* pmksa_cache_get_current - Get the current used PMKSA entry
	* @sm: Pointer to WPA state machine data from wpa_sm_init()
	* Returns: Pointer to the current PMKSA cache entry or %NULL if not available
	*/
	struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
	{
	if (sm == NULL)
	return NULL;
	return sm->cur_pmksa;
	}


	/**
	* pmksa_cache_clear_current - Clear the current PMKSA entry selection
	* @sm: Pointer to WPA state machine data from wpa_sm_init()
	*/
	void pmksa_cache_clear_current(struct wpa_sm *sm)
	{
	if (sm == NULL)
	return;
	sm->cur_pmksa = NULL;
	}


	/**
	* pmksa_cache_set_current - Set the current PMKSA entry selection
	* @sm: Pointer to WPA state machine data from wpa_sm_init()
	* @pmkid: PMKID for selecting PMKSA or %NULL if not used
	* @bssid: BSSID for PMKSA or %NULL if not used
	* @ssid: The network configuration for the current network
	* @try_opportunistic: Whether to allow opportunistic PMKSA caching
	* Returns: 0 if PMKSA was found or -1 if no matching entry was found
	*/
	int pmksa_cache_set_current(struct wpa_sm sm, const u8 pmkid,
	const u8 bssid, struct wpa_ssid ssid,
	int try_opportunistic)
	{
	struct rsn_pmksa_cache *pmksa = sm->pmksa;
	sm->cur_pmksa = NULL;
	if (pmkid)
	sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
	if (sm->cur_pmksa == NULL && bssid)
	sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
	if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
	sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa, ssid,
	bssid);
	if (sm->cur_pmksa) {
	wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
	sm->cur_pmksa->pmkid, PMKID_LEN);
	return 0;
	}
	return -1;
	}


	/**
	* pmksa_cache_list - Dump text list of entries in PMKSA cache
	* @sm: Pointer to WPA state machine data from wpa_sm_init()
	* @buf: Buffer for the list
	* @len: Length of the buffer
	* Returns: number of bytes written to buffer
	*
	* This function is used to generate a text format representation of the
	* current PMKSA cache contents for the ctrl_iface PMKSA command.
	*/
	int pmksa_cache_list(struct wpa_sm sm, char buf, size_t len)
	{
	int i, ret;
	char *pos = buf;
	struct rsn_pmksa_cache_entry *entry;
	struct os_time now;

	os_get_time(&now);
	ret = os_snprintf(pos, buf + len - pos,
	"Index / AA / PMKID / expiration (in seconds) / "
	"opportunistic\n");
	if (ret < 0 \|\| ret >= buf + len - pos)
	return pos - buf;
	pos += ret;
	i = 0;
	entry = sm->pmksa->pmksa;
	while (entry) {
	i++;
	ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
	i, MAC2STR(entry->aa));
	if (ret < 0 \|\| ret >= buf + len - pos)
	return pos - buf;
	pos += ret;
	pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
	PMKID_LEN);
	ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
	(int) (entry->expiration - now.sec),
	entry->opportunistic);
	if (ret < 0 \|\| ret >= buf + len - pos)
	return pos - buf;
	pos += ret;
	entry = entry->next;
	}
	return pos - buf;
	}


	/**
	* pmksa_cache_init - Initialize PMKSA cache
	* @free_cb: Callback function to be called when a PMKSA cache entry is freed
	* @ctx: Context pointer for free_cb function
	* @sm: Pointer to WPA state machine data from wpa_sm_init()
	* Returns: Pointer to PMKSA cache data or %NULL on failure
	*/
	struct rsn_pmksa_cache *
	pmksa_cache_init(void (free_cb)(struct rsn_pmksa_cache_entry entry,
	void *ctx, int replace),
	void ctx, struct wpa_sm sm)
	{
	struct rsn_pmksa_cache *pmksa;

	pmksa = os_zalloc(sizeof(*pmksa));
	if (pmksa) {
	pmksa->free_cb = free_cb;
	pmksa->ctx = ctx;
	pmksa->sm = sm;
	}

	return pmksa;
	}

	#endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */