pmksa_cache.c

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#include "includes.h"

#include "hostapd.h"
#include "common.h"
#include "wpa.h"
#include "eloop.h"
#include "sha1.h"
#include "ieee802_1x.h"
#include "eapol_sm.h"
#include "pmksa_cache.h"


static const int pmksa_cache_max_entries = 1024;
static const int dot11RSNAConfigPMKLifetime = 43200;

struct rsn_pmksa_cache {
#define PMKID_HASH_SIZE 128
#define PMKID_HASH(pmkid) (unsigned int) ((pmkid)[0] & 0x7f)
        struct rsn_pmksa_cache_entry *pmkid[PMKID_HASH_SIZE];
        struct rsn_pmksa_cache_entry *pmksa;
        int pmksa_count;

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


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);
        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)
{
        if (entry == NULL)
                return;
        free(entry->identity);
        ieee802_1x_free_radius_class(&entry->radius_class);
        free(entry);
}


static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
                                   struct rsn_pmksa_cache_entry *entry)
{
        struct rsn_pmksa_cache_entry *pos, *prev;

        pmksa->pmksa_count--;
        pmksa->free_cb(entry, pmksa->ctx);
        pos = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
        prev = NULL;
        while (pos) {
                if (pos == entry) {
                        if (prev != NULL) {
                                prev->hnext = pos->hnext;
                        } else {
                                pmksa->pmkid[PMKID_HASH(entry->pmkid)] =
                                        pos->hnext;
                        }
                        break;
                }
                prev = pos;
                pos = pos->hnext;
        }

        pos = pmksa->pmksa;
        prev = NULL;
        while (pos) {
                if (pos == entry) {
                        if (prev != NULL)
                                prev->next = pos->next;
                        else
                                pmksa->pmksa = pos->next;
                        break;
                }
                prev = pos;
                pos = pos->next;
        }
        _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->spa));
                pmksa_cache_free_entry(pmksa, entry);
        }

        pmksa_cache_set_expiration(pmksa);
}


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

        eloop_cancel_timeout(pmksa_cache_expire, 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);
}


static void pmksa_cache_from_eapol_data(struct rsn_pmksa_cache_entry *entry,
                                        struct eapol_state_machine *eapol)
{
        if (eapol == NULL)
                return;

        if (eapol->identity) {
                entry->identity = malloc(eapol->identity_len);
                if (entry->identity) {
                        entry->identity_len = eapol->identity_len;
                        memcpy(entry->identity, eapol->identity,
                               eapol->identity_len);
                }
        }

        ieee802_1x_copy_radius_class(&entry->radius_class,
                                     &eapol->radius_class);

        entry->eap_type_authsrv = eapol->eap_type_authsrv;
        entry->vlan_id = eapol->sta->vlan_id;
}


void pmksa_cache_to_eapol_data(struct rsn_pmksa_cache_entry *entry,
                               struct eapol_state_machine *eapol)
{
        if (entry == NULL || eapol == NULL)
                return;

        if (entry->identity) {
                free(eapol->identity);
                eapol->identity = malloc(entry->identity_len);
                if (eapol->identity) {
                        eapol->identity_len = entry->identity_len;
                        memcpy(eapol->identity, entry->identity,
                               entry->identity_len);
                }
                wpa_hexdump_ascii(MSG_DEBUG, "STA identity from PMKSA",
                                  eapol->identity, eapol->identity_len);
        }

        ieee802_1x_free_radius_class(&eapol->radius_class);
        ieee802_1x_copy_radius_class(&eapol->radius_class,
                                     &entry->radius_class);
        if (eapol->radius_class.attr) {
                wpa_printf(MSG_DEBUG, "Copied %lu Class attribute(s) from "
                           "PMKSA", (unsigned long) eapol->radius_class.count);
        }

        eapol->eap_type_authsrv = entry->eap_type_authsrv;
        eapol->sta->vlan_id = entry->vlan_id;
}


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, int session_timeout,
                struct eapol_state_machine *eapol)
{
        struct rsn_pmksa_cache_entry *entry, *pos, *prev;
        struct os_time now;

        if (pmk_len > PMK_LEN)
                return NULL;

        entry = wpa_zalloc(sizeof(*entry));
        if (entry == NULL)
                return NULL;
        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;
        if (session_timeout > 0)
                entry->expiration += session_timeout;
        else
                entry->expiration += dot11RSNAConfigPMKLifetime;
        entry->akmp = WPA_KEY_MGMT_IEEE8021X;
        memcpy(entry->spa, spa, ETH_ALEN);
        pmksa_cache_from_eapol_data(entry, eapol);

        /* Replace an old entry for the same STA (if found) with the new entry
         */
        pos = pmksa_cache_get(pmksa, spa, NULL);
        if (pos)
                pmksa_cache_free_entry(pmksa, pos);

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

        /* 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;
        } else {
                entry->next = prev->next;
                prev->next = entry;
        }
        entry->hnext = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
        pmksa->pmkid[PMKID_HASH(entry->pmkid)] = entry;

        pmksa->pmksa_count++;
        wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
                   MAC2STR(entry->spa));
        wpa_hexdump(MSG_DEBUG, "RSN: added PMKID", entry->pmkid, PMKID_LEN);

        return entry;
}


void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
{
        struct rsn_pmksa_cache_entry *entry, *prev;
        int i;

        if (pmksa == NULL)
                return;

        entry = pmksa->pmksa;
        while (entry) {
                prev = entry;
                entry = entry->next;
                _pmksa_cache_free_entry(prev);
        }
        eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
        for (i = 0; i < PMKID_HASH_SIZE; i++)
                pmksa->pmkid[i] = NULL;
        free(pmksa);
}


struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
                                               const u8 *spa, const u8 *pmkid)
{
        struct rsn_pmksa_cache_entry *entry;

        if (pmkid)
                entry = pmksa->pmkid[PMKID_HASH(pmkid)];
        else
                entry = pmksa->pmksa;
        while (entry) {
                if ((spa == NULL || memcmp(entry->spa, spa, ETH_ALEN) == 0) &&
                    (pmkid == NULL ||
                     memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
                        return entry;
                entry = pmkid ? entry->hnext : entry->next;
        }
        return NULL;
}


struct rsn_pmksa_cache *
pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
                                 void *ctx), void *ctx)
{
        struct rsn_pmksa_cache *pmksa;

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

        return pmksa;
}

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