peerkey_auth.c

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/*
 * hostapd - PeerKey for Direct Link Setup (DLS)
 * Copyright (c) 2006-2009, 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 "utils/includes.h"

#include "utils/common.h"
#include "utils/eloop.h"
#include "crypto/sha1.h"
#include "crypto/sha256.h"
#include "wpa_auth.h"
#include "wpa_auth_i.h"
#include "wpa_auth_ie.h"

#ifdef CONFIG_PEERKEY

static void wpa_stsl_step(void *eloop_ctx, void *timeout_ctx)
{
#if 0
        struct wpa_authenticator *wpa_auth = eloop_ctx;
        struct wpa_stsl_negotiation *neg = timeout_ctx;
#endif

        /* TODO: ? */
}


struct wpa_stsl_search {
        const u8 *addr;
        struct wpa_state_machine *sm;
};


static int wpa_stsl_select_sta(struct wpa_state_machine *sm, void *ctx)
{
        struct wpa_stsl_search *search = ctx;
        if (os_memcmp(search->addr, sm->addr, ETH_ALEN) == 0) {
                search->sm = sm;
                return 1;
        }
        return 0;
}


static void wpa_smk_send_error(struct wpa_authenticator *wpa_auth,
                               struct wpa_state_machine *sm, const u8 *peer,
                               u16 mui, u16 error_type)
{
        u8 kde[2 + RSN_SELECTOR_LEN + ETH_ALEN +
               2 + RSN_SELECTOR_LEN + sizeof(struct rsn_error_kde)];
        u8 *pos;
        struct rsn_error_kde error;

        wpa_auth_logger(wpa_auth, sm->addr, LOGGER_DEBUG,
                        "Sending SMK Error");

        pos = kde;

        if (peer) {
                pos = wpa_add_kde(pos, RSN_KEY_DATA_MAC_ADDR, peer, ETH_ALEN,
                                  NULL, 0);
        }

        error.mui = host_to_be16(mui);
        error.error_type = host_to_be16(error_type);
        pos = wpa_add_kde(pos, RSN_KEY_DATA_ERROR,
                          (u8 *) &error, sizeof(error), NULL, 0);

        __wpa_send_eapol(wpa_auth, sm,
                         WPA_KEY_INFO_SECURE | WPA_KEY_INFO_MIC |
                         WPA_KEY_INFO_SMK_MESSAGE | WPA_KEY_INFO_ERROR,
                         NULL, NULL, kde, pos - kde, 0, 0, 0);
}


void wpa_smk_m1(struct wpa_authenticator *wpa_auth,
                struct wpa_state_machine *sm, struct wpa_eapol_key *key)
{
        struct wpa_eapol_ie_parse kde;
        struct wpa_stsl_search search;
        u8 *buf, *pos;
        size_t buf_len;

        if (wpa_parse_kde_ies((const u8 *) (key + 1),
                              WPA_GET_BE16(key->key_data_length), &kde) < 0) {
                wpa_printf(MSG_INFO, "RSN: Failed to parse KDEs in SMK M1");
                return;
        }

        if (kde.rsn_ie == NULL || kde.mac_addr == NULL ||
            kde.mac_addr_len < ETH_ALEN) {
                wpa_printf(MSG_INFO, "RSN: No RSN IE or MAC address KDE in "
                           "SMK M1");
                return;
        }

        /* Initiator = sm->addr; Peer = kde.mac_addr */

        search.addr = kde.mac_addr;
        search.sm = NULL;
        if (wpa_auth_for_each_sta(wpa_auth, wpa_stsl_select_sta, &search) ==
            0 || search.sm == NULL) {
                wpa_printf(MSG_DEBUG, "RSN: SMK handshake with " MACSTR
                           " aborted - STA not associated anymore",
                           MAC2STR(kde.mac_addr));
                wpa_smk_send_error(wpa_auth, sm, kde.mac_addr, STK_MUI_SMK,
                                   STK_ERR_STA_NR);
                /* FIX: wpa_stsl_remove(wpa_auth, neg); */
                return;
        }

        buf_len = kde.rsn_ie_len + 2 + RSN_SELECTOR_LEN + ETH_ALEN;
        buf = os_malloc(buf_len);
        if (buf == NULL)
                return;
        /* Initiator RSN IE */
        os_memcpy(buf, kde.rsn_ie, kde.rsn_ie_len);
        pos = buf + kde.rsn_ie_len;
        /* Initiator MAC Address */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_MAC_ADDR, sm->addr, ETH_ALEN,
                          NULL, 0);

        /* SMK M2:
         * EAPOL-Key(S=1, M=1, A=1, I=0, K=0, SM=1, KeyRSC=0, Nonce=INonce,
         *           MIC=MIC, DataKDs=(RSNIE_I, MAC_I KDE)
         */

        wpa_auth_logger(wpa_auth, search.sm->addr, LOGGER_DEBUG,
                        "Sending SMK M2");

        __wpa_send_eapol(wpa_auth, search.sm,
                         WPA_KEY_INFO_SECURE | WPA_KEY_INFO_MIC |
                         WPA_KEY_INFO_ACK | WPA_KEY_INFO_SMK_MESSAGE,
                         NULL, key->key_nonce, buf, pos - buf, 0, 0, 0);

        os_free(buf);
}


static void wpa_send_smk_m4(struct wpa_authenticator *wpa_auth,
                            struct wpa_state_machine *sm,
                            struct wpa_eapol_key *key,
                            struct wpa_eapol_ie_parse *kde,
                            const u8 *smk)
{
        u8 *buf, *pos;
        size_t buf_len;
        u32 lifetime;

        /* SMK M4:
         * EAPOL-Key(S=1, M=1, A=0, I=1, K=0, SM=1, KeyRSC=0, Nonce=PNonce,
         *           MIC=MIC, DataKDs=(MAC_I KDE, INonce KDE, SMK KDE,
         *           Lifetime KDE)
         */

        buf_len = 2 + RSN_SELECTOR_LEN + ETH_ALEN +
                2 + RSN_SELECTOR_LEN + WPA_NONCE_LEN +
                2 + RSN_SELECTOR_LEN + PMK_LEN + WPA_NONCE_LEN +
                2 + RSN_SELECTOR_LEN + sizeof(lifetime);
        pos = buf = os_malloc(buf_len);
        if (buf == NULL)
                return;

        /* Initiator MAC Address */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_MAC_ADDR, kde->mac_addr, ETH_ALEN,
                          NULL, 0);

        /* Initiator Nonce */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_NONCE, kde->nonce, WPA_NONCE_LEN,
                          NULL, 0);

        /* SMK with PNonce */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_SMK, smk, PMK_LEN,
                          key->key_nonce, WPA_NONCE_LEN);

        /* Lifetime */
        lifetime = htonl(43200); /* dot11RSNAConfigSMKLifetime */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_LIFETIME,
                          (u8 *) &lifetime, sizeof(lifetime), NULL, 0);

        wpa_auth_logger(sm->wpa_auth, sm->addr, LOGGER_DEBUG,
                        "Sending SMK M4");

        __wpa_send_eapol(wpa_auth, sm,
                         WPA_KEY_INFO_SECURE | WPA_KEY_INFO_MIC |
                         WPA_KEY_INFO_INSTALL | WPA_KEY_INFO_SMK_MESSAGE,
                         NULL, key->key_nonce, buf, pos - buf, 0, 1, 0);

        os_free(buf);
}


static void wpa_send_smk_m5(struct wpa_authenticator *wpa_auth,
                            struct wpa_state_machine *sm,
                            struct wpa_eapol_key *key,
                            struct wpa_eapol_ie_parse *kde,
                            const u8 *smk, const u8 *peer)
{
        u8 *buf, *pos;
        size_t buf_len;
        u32 lifetime;

        /* SMK M5:
         * EAPOL-Key(S=1, M=1, A=0, I=0, K=0, SM=1, KeyRSC=0, Nonce=INonce,
         *           MIC=MIC, DataKDs=(RSNIE_P, MAC_P KDE, PNonce, SMK KDE,
         *                             Lifetime KDE))
         */

        buf_len = kde->rsn_ie_len +
                2 + RSN_SELECTOR_LEN + ETH_ALEN +
                2 + RSN_SELECTOR_LEN + WPA_NONCE_LEN +
                2 + RSN_SELECTOR_LEN + PMK_LEN + WPA_NONCE_LEN +
                2 + RSN_SELECTOR_LEN + sizeof(lifetime);
        pos = buf = os_malloc(buf_len);
        if (buf == NULL)
                return;

        /* Peer RSN IE */
        os_memcpy(buf, kde->rsn_ie, kde->rsn_ie_len);
        pos = buf + kde->rsn_ie_len;

        /* Peer MAC Address */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_MAC_ADDR, peer, ETH_ALEN, NULL, 0);

        /* PNonce */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_NONCE, key->key_nonce,
                          WPA_NONCE_LEN, NULL, 0);

        /* SMK and INonce */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_SMK, smk, PMK_LEN,
                          kde->nonce, WPA_NONCE_LEN);

        /* Lifetime */
        lifetime = htonl(43200); /* dot11RSNAConfigSMKLifetime */
        pos = wpa_add_kde(pos, RSN_KEY_DATA_LIFETIME,
                          (u8 *) &lifetime, sizeof(lifetime), NULL, 0);

        wpa_auth_logger(sm->wpa_auth, sm->addr, LOGGER_DEBUG,
                        "Sending SMK M5");

        __wpa_send_eapol(wpa_auth, sm,
                         WPA_KEY_INFO_SECURE | WPA_KEY_INFO_MIC |
                         WPA_KEY_INFO_SMK_MESSAGE,
                         NULL, kde->nonce, buf, pos - buf, 0, 1, 0);

        os_free(buf);
}


void wpa_smk_m3(struct wpa_authenticator *wpa_auth,
                struct wpa_state_machine *sm, struct wpa_eapol_key *key)
{
        struct wpa_eapol_ie_parse kde;
        struct wpa_stsl_search search;
        u8 smk[32], buf[ETH_ALEN + 8 + 2 * WPA_NONCE_LEN], *pos;

        if (wpa_parse_kde_ies((const u8 *) (key + 1),
                              WPA_GET_BE16(key->key_data_length), &kde) < 0) {
                wpa_printf(MSG_INFO, "RSN: Failed to parse KDEs in SMK M3");
                return;
        }

        if (kde.rsn_ie == NULL ||
            kde.mac_addr == NULL || kde.mac_addr_len < ETH_ALEN ||
            kde.nonce == NULL || kde.nonce_len < WPA_NONCE_LEN) {
                wpa_printf(MSG_INFO, "RSN: No RSN IE, MAC address KDE, or "
                           "Nonce KDE in SMK M3");
                return;
        }

        /* Peer = sm->addr; Initiator = kde.mac_addr;
         * Peer Nonce = key->key_nonce; Initiator Nonce = kde.nonce */

        search.addr = kde.mac_addr;
        search.sm = NULL;
        if (wpa_auth_for_each_sta(wpa_auth, wpa_stsl_select_sta, &search) ==
            0 || search.sm == NULL) {
                wpa_printf(MSG_DEBUG, "RSN: SMK handshake with " MACSTR
                           " aborted - STA not associated anymore",
                           MAC2STR(kde.mac_addr));
                wpa_smk_send_error(wpa_auth, sm, kde.mac_addr, STK_MUI_SMK,
                                   STK_ERR_STA_NR);
                /* FIX: wpa_stsl_remove(wpa_auth, neg); */
                return;
        }

        if (os_get_random(smk, PMK_LEN)) {
                wpa_printf(MSG_DEBUG, "RSN: Failed to generate SMK");
                return;
        }

        /* SMK = PRF-256(Random number, "SMK Derivation",
         *               AA || Time || INonce || PNonce)
         */
        os_memcpy(buf, wpa_auth->addr, ETH_ALEN);
        pos = buf + ETH_ALEN;
        wpa_get_ntp_timestamp(pos);
        pos += 8;
        os_memcpy(pos, kde.nonce, WPA_NONCE_LEN);
        pos += WPA_NONCE_LEN;
        os_memcpy(pos, key->key_nonce, WPA_NONCE_LEN);
#ifdef CONFIG_IEEE80211W
        sha256_prf(smk, PMK_LEN, "SMK Derivation", buf, sizeof(buf),
                   smk, PMK_LEN);
#else /* CONFIG_IEEE80211W */
        sha1_prf(smk, PMK_LEN, "SMK Derivation", buf, sizeof(buf),
                 smk, PMK_LEN);
#endif /* CONFIG_IEEE80211W */

        wpa_hexdump_key(MSG_DEBUG, "RSN: SMK", smk, PMK_LEN);

        wpa_send_smk_m4(wpa_auth, sm, key, &kde, smk);
        wpa_send_smk_m5(wpa_auth, search.sm, key, &kde, smk, sm->addr);

        /* Authenticator does not need SMK anymore and it is required to forget
         * it. */
        os_memset(smk, 0, sizeof(*smk));
}


void wpa_smk_error(struct wpa_authenticator *wpa_auth,
                   struct wpa_state_machine *sm, struct wpa_eapol_key *key)
{
        struct wpa_eapol_ie_parse kde;
        struct wpa_stsl_search search;
        struct rsn_error_kde error;
        u16 mui, error_type;

        if (wpa_parse_kde_ies((const u8 *) (key + 1),
                              WPA_GET_BE16(key->key_data_length), &kde) < 0) {
                wpa_printf(MSG_INFO, "RSN: Failed to parse KDEs in SMK Error");
                return;
        }

        if (kde.mac_addr == NULL || kde.mac_addr_len < ETH_ALEN ||
            kde.error == NULL || kde.error_len < sizeof(error)) {
                wpa_printf(MSG_INFO, "RSN: No MAC address or Error KDE in "
                           "SMK Error");
                return;
        }

        search.addr = kde.mac_addr;
        search.sm = NULL;
        if (wpa_auth_for_each_sta(wpa_auth, wpa_stsl_select_sta, &search) ==
            0 || search.sm == NULL) {
                wpa_printf(MSG_DEBUG, "RSN: Peer STA " MACSTR " not "
                           "associated for SMK Error message from " MACSTR,
                           MAC2STR(kde.mac_addr), MAC2STR(sm->addr));
                return;
        }

        os_memcpy(&error, kde.error, sizeof(error));
        mui = be_to_host16(error.mui);
        error_type = be_to_host16(error.error_type);
        wpa_auth_vlogger(wpa_auth, sm->addr, LOGGER_INFO,
                         "STA reported SMK Error: Peer " MACSTR
                         " MUI %d Error Type %d",
                         MAC2STR(kde.mac_addr), mui, error_type);

        wpa_smk_send_error(wpa_auth, search.sm, sm->addr, mui, error_type);
}


int wpa_stsl_remove(struct wpa_authenticator *wpa_auth,
                    struct wpa_stsl_negotiation *neg)
{
        struct wpa_stsl_negotiation *pos, *prev;

        if (wpa_auth == NULL)
                return -1;
        pos = wpa_auth->stsl_negotiations;
        prev = NULL;
        while (pos) {
                if (pos == neg) {
                        if (prev)
                                prev->next = pos->next;
                        else
                                wpa_auth->stsl_negotiations = pos->next;

                        eloop_cancel_timeout(wpa_stsl_step, wpa_auth, pos);
                        os_free(pos);
                        return 0;
                }
                prev = pos;
                pos = pos->next;
        }

        return -1;
}

#endif /* CONFIG_PEERKEY */