eap_server_tls.c

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/*
 * hostapd / EAP-TLS (RFC 2716)
 * Copyright (c) 2004-2008, 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 "eap_i.h"
#include "eap_tls_common.h"
#include "crypto/tls.h"


static void eap_tls_reset(struct eap_sm *sm, void *priv);


struct eap_tls_data {
        struct eap_ssl_data ssl;
        enum { START, CONTINUE, SUCCESS, FAILURE } state;
        int established;
};


static const char * eap_tls_state_txt(int state)
{
        switch (state) {
        case START:
                return "START";
        case CONTINUE:
                return "CONTINUE";
        case SUCCESS:
                return "SUCCESS";
        case FAILURE:
                return "FAILURE";
        default:
                return "Unknown?!";
        }
}


static void eap_tls_state(struct eap_tls_data *data, int state)
{
        wpa_printf(MSG_DEBUG, "EAP-TLS: %s -> %s",
                   eap_tls_state_txt(data->state),
                   eap_tls_state_txt(state));
        data->state = state;
}


static void * eap_tls_init(struct eap_sm *sm)
{
        struct eap_tls_data *data;

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        data->state = START;

        if (eap_server_tls_ssl_init(sm, &data->ssl, 1)) {
                wpa_printf(MSG_INFO, "EAP-TLS: Failed to initialize SSL.");
                eap_tls_reset(sm, data);
                return NULL;
        }

        return data;
}


static void eap_tls_reset(struct eap_sm *sm, void *priv)
{
        struct eap_tls_data *data = priv;
        if (data == NULL)
                return;
        eap_server_tls_ssl_deinit(sm, &data->ssl);
        os_free(data);
}


static struct wpabuf * eap_tls_build_start(struct eap_sm *sm,
                                           struct eap_tls_data *data, u8 id)
{
        struct wpabuf *req;

        req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TLS, 1, EAP_CODE_REQUEST,
                            id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-TLS: Failed to allocate memory for "
                           "request");
                eap_tls_state(data, FAILURE);
                return NULL;
        }

        wpabuf_put_u8(req, EAP_TLS_FLAGS_START);

        eap_tls_state(data, CONTINUE);

        return req;
}


static struct wpabuf * eap_tls_buildReq(struct eap_sm *sm, void *priv, u8 id)
{
        struct eap_tls_data *data = priv;
        struct wpabuf *res;

        if (data->ssl.state == FRAG_ACK) {
                return eap_server_tls_build_ack(id, EAP_TYPE_TLS, 0);
        }

        if (data->ssl.state == WAIT_FRAG_ACK) {
                res = eap_server_tls_build_msg(&data->ssl, EAP_TYPE_TLS, 0,
                                               id);
                goto check_established;
        }

        switch (data->state) {
        case START:
                return eap_tls_build_start(sm, data, id);
        case CONTINUE:
                if (tls_connection_established(sm->ssl_ctx, data->ssl.conn))
                        data->established = 1;
                break;
        default:
                wpa_printf(MSG_DEBUG, "EAP-TLS: %s - unexpected state %d",
                           __func__, data->state);
                return NULL;
        }

        res = eap_server_tls_build_msg(&data->ssl, EAP_TYPE_TLS, 0, id);

check_established:
        if (data->established && data->ssl.state != WAIT_FRAG_ACK) {
                /* TLS handshake has been completed and there are no more
                 * fragments waiting to be sent out. */
                wpa_printf(MSG_DEBUG, "EAP-TLS: Done");
                eap_tls_state(data, SUCCESS);
        }

        return res;
}


static Boolean eap_tls_check(struct eap_sm *sm, void *priv,
                             struct wpabuf *respData)
{
        const u8 *pos;
        size_t len;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_TLS, respData, &len);
        if (pos == NULL || len < 1) {
                wpa_printf(MSG_INFO, "EAP-TLS: Invalid frame");
                return TRUE;
        }

        return FALSE;
}


static void eap_tls_process_msg(struct eap_sm *sm, void *priv,
                                const struct wpabuf *respData)
{
        struct eap_tls_data *data = priv;
        if (data->state == SUCCESS && wpabuf_len(data->ssl.tls_in) == 0) {
                wpa_printf(MSG_DEBUG, "EAP-TLS: Client acknowledged final TLS "
                           "handshake message");
                return;
        }
        if (eap_server_tls_phase1(sm, &data->ssl) < 0)
                eap_tls_state(data, FAILURE);
}


static void eap_tls_process(struct eap_sm *sm, void *priv,
                            struct wpabuf *respData)
{
        struct eap_tls_data *data = priv;
        if (eap_server_tls_process(sm, &data->ssl, respData, data,
                                   EAP_TYPE_TLS, NULL, eap_tls_process_msg) <
            0)
                eap_tls_state(data, FAILURE);
}


static Boolean eap_tls_isDone(struct eap_sm *sm, void *priv)
{
        struct eap_tls_data *data = priv;
        return data->state == SUCCESS || data->state == FAILURE;
}


static u8 * eap_tls_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_tls_data *data = priv;
        u8 *eapKeyData;

        if (data->state != SUCCESS)
                return NULL;

        eapKeyData = eap_server_tls_derive_key(sm, &data->ssl,
                                               "client EAP encryption",
                                               EAP_TLS_KEY_LEN);
        if (eapKeyData) {
                *len = EAP_TLS_KEY_LEN;
                wpa_hexdump(MSG_DEBUG, "EAP-TLS: Derived key",
                            eapKeyData, EAP_TLS_KEY_LEN);
        } else {
                wpa_printf(MSG_DEBUG, "EAP-TLS: Failed to derive key");
        }

        return eapKeyData;
}


static u8 * eap_tls_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_tls_data *data = priv;
        u8 *eapKeyData, *emsk;

        if (data->state != SUCCESS)
                return NULL;

        eapKeyData = eap_server_tls_derive_key(sm, &data->ssl,
                                               "client EAP encryption",
                                               EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
        if (eapKeyData) {
                emsk = os_malloc(EAP_EMSK_LEN);
                if (emsk)
                        os_memcpy(emsk, eapKeyData + EAP_TLS_KEY_LEN,
                                  EAP_EMSK_LEN);
                os_free(eapKeyData);
        } else
                emsk = NULL;

        if (emsk) {
                *len = EAP_EMSK_LEN;
                wpa_hexdump(MSG_DEBUG, "EAP-TLS: Derived EMSK",
                            emsk, EAP_EMSK_LEN);
        } else {
                wpa_printf(MSG_DEBUG, "EAP-TLS: Failed to derive EMSK");
        }

        return emsk;
}


static Boolean eap_tls_isSuccess(struct eap_sm *sm, void *priv)
{
        struct eap_tls_data *data = priv;
        return data->state == SUCCESS;
}


int eap_server_tls_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_IETF, EAP_TYPE_TLS, "TLS");
        if (eap == NULL)
                return -1;

        eap->init = eap_tls_init;
        eap->reset = eap_tls_reset;
        eap->buildReq = eap_tls_buildReq;
        eap->check = eap_tls_check;
        eap->process = eap_tls_process;
        eap->isDone = eap_tls_isDone;
        eap->getKey = eap_tls_getKey;
        eap->isSuccess = eap_tls_isSuccess;
        eap->get_emsk = eap_tls_get_emsk;

        ret = eap_server_method_register(eap);
        if (ret)
                eap_server_method_free(eap);
        return ret;
}