hostapd/src/rsn_supp/pmksa_cache.c

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/*
* WPA Supplicant - RSN PMKSA cache
* Copyright (c) 2004-2009, 2011-2012, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "includes.h"
#include "common.h"
#include "eloop.h"
#include "eapol_supp/eapol_supp_sm.h"
#include "wpa.h"
#include "wpa_i.h"
#include "pmksa_cache.h"
#ifdef IEEE8021X_EAPOL
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,
enum pmksa_free_reason reason);
void *ctx;
};
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,
enum pmksa_free_reason reason)
{
wpa_sm_remove_pmkid(pmksa->sm, entry->aa, entry->pmkid);
pmksa->pmksa_count--;
pmksa->free_cb(entry, pmksa->ctx, reason);
_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_reltime now;
os_get_reltime(&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, PMKSA_EXPIRE);
}
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_reltime now;
eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
if (pmksa->pmksa == NULL)
return;
os_get_reltime(&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, 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
* @network_ctx: Network configuration context for this PMK
* @akmp: WPA_KEY_MGMT_* used in key derivation
* 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, void *network_ctx, int akmp)
{
struct rsn_pmksa_cache_entry *entry, *pos, *prev;
struct os_reltime now;
if (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,
wpa_key_mgmt_sha256(akmp));
os_get_reltime(&now);
entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
entry->akmp = akmp;
os_memcpy(entry->aa, aa, ETH_ALEN);
entry->network_ctx = network_ctx;
/* 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 OKC is used, there may be other PMKSA cache
* entries based on the same PMK. These needs to be
* flushed so that a new entry can be created based on
* the new PMK. Only clear other entries if they have a
* matching PMK and this PMK has been used successfully
* with the current AP, i.e., if opportunistic flag has
* been cleared in wpa_supplicant_key_neg_complete().
*/
wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
"the current AP and any PMKSA cache entry "
"that was based on the old PMK");
if (!pos->opportunistic)
pmksa_cache_flush(pmksa, network_ctx, pos->pmk,
pos->pmk_len);
pmksa_cache_free_entry(pmksa, pos, PMKSA_REPLACE);
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;
if (pos == pmksa->sm->cur_pmksa) {
/*
* Never remove the current PMKSA cache entry, since
* it's in use, and removing it triggers a needless
* deauthentication.
*/
pos = pos->next;
pmksa->pmksa->next = pos ? pos->next : NULL;
} else
pmksa->pmksa = pos->next;
if (pos) {
wpa_printf(MSG_DEBUG, "RSN: removed the oldest idle "
"PMKSA cache entry (for " MACSTR ") to "
"make room for new one",
MAC2STR(pos->aa));
pmksa_cache_free_entry(pmksa, pos, PMKSA_FREE);
}
}
/* 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
" network_ctx=%p", MAC2STR(entry->aa), network_ctx);
wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
return entry;
}
/**
* pmksa_cache_flush - Flush PMKSA cache entries for a specific network
* @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
* @network_ctx: Network configuration context or %NULL to flush all entries
* @pmk: PMK to match for or %NYLL to match all PMKs
* @pmk_len: PMK length
*/
void pmksa_cache_flush(struct rsn_pmksa_cache *pmksa, void *network_ctx,
const u8 *pmk, size_t pmk_len)
{
struct rsn_pmksa_cache_entry *entry, *prev = NULL, *tmp;
int removed = 0;
entry = pmksa->pmksa;
while (entry) {
if ((entry->network_ctx == network_ctx ||
network_ctx == NULL) &&
(pmk == NULL ||
(pmk_len == entry->pmk_len &&
os_memcmp(pmk, entry->pmk, pmk_len) == 0))) {
wpa_printf(MSG_DEBUG, "RSN: Flush PMKSA cache entry "
"for " MACSTR, MAC2STR(entry->aa));
if (prev)
prev->next = entry->next;
else
pmksa->pmksa = entry->next;
tmp = entry;
entry = entry->next;
pmksa_cache_free_entry(pmksa, tmp, PMKSA_FREE);
removed++;
} else {
prev = entry;
entry = entry->next;
}
}
if (removed)
pmksa_cache_set_expiration(pmksa);
}
/**
* 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
* @network_ctx: Network context 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,
const void *network_ctx)
{
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) &&
(network_ctx == NULL || network_ctx == entry->network_ctx))
return entry;
entry = entry->next;
}
return NULL;
}
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->network_ctx, old_entry->akmp);
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()
* @network_ctx: Network configuration context
* @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, void *network_ctx,
const u8 *aa)
{
struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
wpa_printf(MSG_DEBUG, "RSN: Consider " MACSTR " for OKC", MAC2STR(aa));
if (network_ctx == NULL)
return NULL;
while (entry) {
if (entry->network_ctx == network_ctx) {
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
* @network_ctx: Network configuration context
* @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, void *network_ctx,
int try_opportunistic)
{
struct rsn_pmksa_cache *pmksa = sm->pmksa;
wpa_printf(MSG_DEBUG, "RSN: PMKSA cache search - network_ctx=%p "
"try_opportunistic=%d", network_ctx, try_opportunistic);
if (pmkid)
wpa_hexdump(MSG_DEBUG, "RSN: Search for PMKID",
pmkid, PMKID_LEN);
if (bssid)
wpa_printf(MSG_DEBUG, "RSN: Search for BSSID " MACSTR,
MAC2STR(bssid));
sm->cur_pmksa = NULL;
if (pmkid)
sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid,
network_ctx);
if (sm->cur_pmksa == NULL && bssid)
sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL,
network_ctx);
if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa,
network_ctx,
bssid);
if (sm->cur_pmksa) {
wpa_hexdump(MSG_DEBUG, "RSN: PMKSA cache entry found - PMKID",
sm->cur_pmksa->pmkid, PMKID_LEN);
return 0;
}
wpa_printf(MSG_DEBUG, "RSN: No PMKSA cache entry found");
return -1;
}
/**
* pmksa_cache_list - Dump text list of entries in PMKSA cache
* @pmksa: Pointer to PMKSA cache data from pmksa_cache_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 rsn_pmksa_cache *pmksa, char *buf, size_t len)
{
int i, ret;
char *pos = buf;
struct rsn_pmksa_cache_entry *entry;
struct os_reltime now;
os_get_reltime(&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 = 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, enum pmksa_free_reason reason),
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 */