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* WPA Supplicant - RSN PMKSA cache
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* Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* Alternatively, this software may be distributed under the terms of BSD
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* See README and COPYING for more details.
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#include "config_ssid.h"
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#include "pmksa_cache.h"
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#if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
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static const int pmksa_cache_max_entries = 32;
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struct rsn_pmksa_cache {
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struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
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int pmksa_count; /* number of entries in PMKSA cache */
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struct wpa_sm *sm; /* TODO: get rid of this reference(?) */
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void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
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* rsn_pmkid - Calculate PMK identifier
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* @pmk: Pairwise master key
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* @pmk_len: Length of pmk in bytes
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* @aa: Authenticator address
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* @spa: Supplicant address
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* IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
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* PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
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void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa,
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char *title = "PMK Name";
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const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
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unsigned char hash[SHA1_MAC_LEN];
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addr[0] = (u8 *) title;
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hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
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os_memcpy(pmkid, hash, PMKID_LEN);
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static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
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static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
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static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
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struct rsn_pmksa_cache_entry *entry,
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pmksa->free_cb(entry, pmksa->ctx, replace);
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_pmksa_cache_free_entry(entry);
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static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
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struct rsn_pmksa_cache *pmksa = eloop_ctx;
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while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
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struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
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pmksa->pmksa = entry->next;
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wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
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MACSTR, MAC2STR(entry->aa));
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pmksa_cache_free_entry(pmksa, entry, 0);
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pmksa_cache_set_expiration(pmksa);
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static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
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struct rsn_pmksa_cache *pmksa = eloop_ctx;
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pmksa->sm->cur_pmksa = NULL;
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eapol_sm_request_reauth(pmksa->sm->eapol);
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static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
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struct rsn_pmksa_cache_entry *entry;
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eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
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eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
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if (pmksa->pmksa == NULL)
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sec = pmksa->pmksa->expiration - now.sec;
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eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
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entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
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pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
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sec = pmksa->pmksa->reauth_time - now.sec;
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eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
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* pmksa_cache_add - Add a PMKSA cache entry
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* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
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* @pmk: The new pairwise master key
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* @pmk_len: PMK length in bytes, usually PMK_LEN (32)
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* @aa: Authenticator address
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* @spa: Supplicant address
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* @network_ctx: Network configuration context for this PMK
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* Returns: Pointer to the added PMKSA cache entry or %NULL on error
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* This function create a PMKSA entry for a new PMK and adds it to the PMKSA
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* cache. If an old entry is already in the cache for the same Authenticator,
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* this entry will be replaced with the new entry. PMKID will be calculated
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* based on the PMK and the driver interface is notified of the new PMKID.
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struct rsn_pmksa_cache_entry *
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pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
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const u8 *aa, const u8 *spa, void *network_ctx)
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struct rsn_pmksa_cache_entry *entry, *pos, *prev;
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if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN)
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entry = os_zalloc(sizeof(*entry));
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os_memcpy(entry->pmk, pmk, pmk_len);
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entry->pmk_len = pmk_len;
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rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
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entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
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entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
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pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
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entry->akmp = WPA_KEY_MGMT_IEEE8021X;
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os_memcpy(entry->aa, aa, ETH_ALEN);
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entry->network_ctx = network_ctx;
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/* Replace an old entry for the same Authenticator (if found) with the
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if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
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if (pos->pmk_len == pmk_len &&
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os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
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os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
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wpa_printf(MSG_DEBUG, "WPA: reusing previous "
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pmksa->pmksa = pos->next;
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prev->next = pos->next;
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if (pos == pmksa->sm->cur_pmksa) {
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/* We are about to replace the current PMKSA
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* cache entry. This happens when the PMKSA
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* caching attempt fails, so we don't want to
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* force pmksa_cache_free_entry() to disconnect
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* at this point. Let's just make sure the old
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* PMKSA cache entry will not be used in the
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wpa_printf(MSG_DEBUG, "RSN: replacing current "
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pmksa->sm->cur_pmksa = NULL;
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wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
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pmksa_cache_free_entry(pmksa, pos, 1);
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if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
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/* Remove the oldest entry to make room for the new entry */
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pmksa->pmksa = pos->next;
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wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
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"entry (for " MACSTR ") to make room for new one",
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wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
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pmksa_cache_free_entry(pmksa, pos, 0);
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/* Add the new entry; order by expiration time */
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if (pos->expiration > entry->expiration)
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entry->next = pmksa->pmksa;
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pmksa->pmksa = entry;
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pmksa_cache_set_expiration(pmksa);
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entry->next = prev->next;
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pmksa->pmksa_count++;
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wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
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wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
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* pmksa_cache_deinit - Free all entries in PMKSA cache
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* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
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void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
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struct rsn_pmksa_cache_entry *entry, *prev;
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entry = pmksa->pmksa;
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pmksa_cache_set_expiration(pmksa);
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* pmksa_cache_get - Fetch a PMKSA cache entry
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* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
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* @aa: Authenticator address or %NULL to match any
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* @pmkid: PMKID or %NULL to match any
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* Returns: Pointer to PMKSA cache entry or %NULL if no match was found
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struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
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const u8 *aa, const u8 *pmkid)
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struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
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if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
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os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
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* pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
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* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
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* Clear references to old data structures when wpa_supplicant is reconfigured.
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void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
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struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
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entry->network_ctx = NULL;
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static struct rsn_pmksa_cache_entry *
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pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
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const struct rsn_pmksa_cache_entry *old_entry,
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struct rsn_pmksa_cache_entry *new_entry;
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new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
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aa, pmksa->sm->own_addr,
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old_entry->network_ctx);
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if (new_entry == NULL)
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/* TODO: reorder entries based on expiration time? */
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new_entry->expiration = old_entry->expiration;
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new_entry->opportunistic = 1;
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* pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
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* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
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* @network_ctx: Network configuration context
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* @aa: Authenticator address for the new AP
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* Returns: Pointer to a new PMKSA cache entry or %NULL if not available
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* Try to create a new PMKSA cache entry opportunistically by guessing that the
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* new AP is sharing the same PMK as another AP that has the same SSID and has
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* already an entry in PMKSA cache.
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struct rsn_pmksa_cache_entry *
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pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, void *network_ctx,
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struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
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if (network_ctx == NULL)
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if (entry->network_ctx == network_ctx) {
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entry = pmksa_cache_clone_entry(pmksa, entry, aa);
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wpa_printf(MSG_DEBUG, "RSN: added "
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"opportunistic PMKSA cache entry "
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"for " MACSTR, MAC2STR(aa));
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* pmksa_cache_get_current - Get the current used PMKSA entry
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* Returns: Pointer to the current PMKSA cache entry or %NULL if not available
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struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
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return sm->cur_pmksa;
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* pmksa_cache_clear_current - Clear the current PMKSA entry selection
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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void pmksa_cache_clear_current(struct wpa_sm *sm)
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sm->cur_pmksa = NULL;
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* pmksa_cache_set_current - Set the current PMKSA entry selection
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @pmkid: PMKID for selecting PMKSA or %NULL if not used
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* @bssid: BSSID for PMKSA or %NULL if not used
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* @network_ctx: Network configuration context
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* @try_opportunistic: Whether to allow opportunistic PMKSA caching
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* Returns: 0 if PMKSA was found or -1 if no matching entry was found
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int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
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const u8 *bssid, void *network_ctx,
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int try_opportunistic)
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struct rsn_pmksa_cache *pmksa = sm->pmksa;
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sm->cur_pmksa = NULL;
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sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
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if (sm->cur_pmksa == NULL && bssid)
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sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
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if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
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sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa,
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wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
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sm->cur_pmksa->pmkid, PMKID_LEN);
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* pmksa_cache_list - Dump text list of entries in PMKSA cache
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @buf: Buffer for the list
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* @len: Length of the buffer
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* Returns: number of bytes written to buffer
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* This function is used to generate a text format representation of the
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* current PMKSA cache contents for the ctrl_iface PMKSA command.
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int pmksa_cache_list(struct wpa_sm *sm, char *buf, size_t len)
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struct rsn_pmksa_cache_entry *entry;
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ret = os_snprintf(pos, buf + len - pos,
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"Index / AA / PMKID / expiration (in seconds) / "
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if (ret < 0 || ret >= buf + len - pos)
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entry = sm->pmksa->pmksa;
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ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
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i, MAC2STR(entry->aa));
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if (ret < 0 || ret >= buf + len - pos)
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pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
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ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
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(int) (entry->expiration - now.sec),
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entry->opportunistic);
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if (ret < 0 || ret >= buf + len - pos)
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* pmksa_cache_init - Initialize PMKSA cache
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* @free_cb: Callback function to be called when a PMKSA cache entry is freed
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* @ctx: Context pointer for free_cb function
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* Returns: Pointer to PMKSA cache data or %NULL on failure
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struct rsn_pmksa_cache *
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pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
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void *ctx, int replace),
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void *ctx, struct wpa_sm *sm)
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struct rsn_pmksa_cache *pmksa;
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pmksa = os_zalloc(sizeof(*pmksa));
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pmksa->free_cb = free_cb;
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#endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
added
removed
src/rsn_supp/pmksa_cache.c
