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* hostapd / EAP-PSK (RFC 4764) server
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* Copyright (c) 2005-2007, 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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* Note: EAP-PSK is an EAP authentication method and as such, completely
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* different from WPA-PSK. This file is not needed for WPA-PSK functionality.
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#include "eap_server/eap_i.h"
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#include "eap_common/eap_psk_common.h"
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enum { PSK_1, PSK_3, SUCCESS, FAILURE } state;
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u8 rand_s[EAP_PSK_RAND_LEN];
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u8 rand_p[EAP_PSK_RAND_LEN];
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size_t id_p_len, id_s_len;
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u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
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u8 emsk[EAP_EMSK_LEN];
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static void * eap_psk_init(struct eap_sm *sm)
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struct eap_psk_data *data;
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data = os_zalloc(sizeof(*data));
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data->id_s = (u8 *) "hostapd";
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static void eap_psk_reset(struct eap_sm *sm, void *priv)
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struct eap_psk_data *data = priv;
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static struct wpabuf * eap_psk_build_1(struct eap_sm *sm,
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struct eap_psk_data *data, u8 id)
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struct eap_psk_hdr_1 *psk;
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wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-1 (sending)");
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if (os_get_random(data->rand_s, EAP_PSK_RAND_LEN)) {
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wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
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data->state = FAILURE;
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_S (server rand)",
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data->rand_s, EAP_PSK_RAND_LEN);
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req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
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sizeof(*psk) + data->id_s_len,
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EAP_CODE_REQUEST, id);
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wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory "
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data->state = FAILURE;
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psk = wpabuf_put(req, sizeof(*psk));
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psk->flags = EAP_PSK_FLAGS_SET_T(0); /* T=0 */
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os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
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wpabuf_put_data(req, data->id_s, data->id_s_len);
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static struct wpabuf * eap_psk_build_3(struct eap_sm *sm,
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struct eap_psk_data *data, u8 id)
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struct eap_psk_hdr_3 *psk;
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u8 *buf, *pchannel, nonce[16];
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wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-3 (sending)");
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req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
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sizeof(*psk) + 4 + 16 + 1, EAP_CODE_REQUEST, id);
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wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory "
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data->state = FAILURE;
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psk = wpabuf_put(req, sizeof(*psk));
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psk->flags = EAP_PSK_FLAGS_SET_T(2); /* T=2 */
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os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
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/* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
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buflen = data->id_s_len + EAP_PSK_RAND_LEN;
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buf = os_malloc(buflen);
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os_memcpy(buf, data->id_s, data->id_s_len);
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os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
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if (omac1_aes_128(data->ak, buf, buflen, psk->mac_s))
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if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek, data->msk,
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wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
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wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
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wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
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os_memset(nonce, 0, sizeof(nonce));
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pchannel = wpabuf_put(req, 4 + 16 + 1);
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os_memcpy(pchannel, nonce + 12, 4);
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os_memset(pchannel + 4, 0, 16); /* Tag */
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pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (plaintext)",
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pchannel, 4 + 16 + 1);
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if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
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wpabuf_head(req), 22,
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pchannel + 4 + 16, 1, pchannel + 4))
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (encrypted)",
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pchannel, 4 + 16 + 1);
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data->state = FAILURE;
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static struct wpabuf * eap_psk_buildReq(struct eap_sm *sm, void *priv, u8 id)
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struct eap_psk_data *data = priv;
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switch (data->state) {
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return eap_psk_build_1(sm, data, id);
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return eap_psk_build_3(sm, data, id);
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wpa_printf(MSG_DEBUG, "EAP-PSK: Unknown state %d in buildReq",
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static Boolean eap_psk_check(struct eap_sm *sm, void *priv,
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struct wpabuf *respData)
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struct eap_psk_data *data = priv;
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pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len);
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if (pos == NULL || len < 1) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
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t = EAP_PSK_FLAGS_GET_T(*pos);
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wpa_printf(MSG_DEBUG, "EAP-PSK: received frame: T=%d", t);
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if (data->state == PSK_1 && t != 1) {
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wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-2 - "
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if (data->state == PSK_3 && t != 3) {
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wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-4 - "
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if ((t == 1 && len < sizeof(struct eap_psk_hdr_2)) ||
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(t == 3 && len < sizeof(struct eap_psk_hdr_4))) {
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wpa_printf(MSG_DEBUG, "EAP-PSK: Too short frame");
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static void eap_psk_process_2(struct eap_sm *sm,
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struct eap_psk_data *data,
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struct wpabuf *respData)
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const struct eap_psk_hdr_2 *resp;
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u8 *pos, mac[EAP_PSK_MAC_LEN], *buf;
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if (data->state != PSK_1)
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wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-2");
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cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData,
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if (cpos == NULL || left < sizeof(*resp)) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
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resp = (const struct eap_psk_hdr_2 *) cpos;
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cpos = (const u8 *) (resp + 1);
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left -= sizeof(*resp);
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data->id_p = os_malloc(left);
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if (data->id_p == NULL) {
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wpa_printf(MSG_INFO, "EAP-PSK: Failed to allocate memory for "
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os_memcpy(data->id_p, cpos, left);
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data->id_p_len = left;
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wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PSK: ID_P",
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data->id_p, data->id_p_len);
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if (eap_user_get(sm, data->id_p, data->id_p_len, 0) < 0) {
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wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: unknown ID_P",
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data->id_p, data->id_p_len);
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data->state = FAILURE;
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i < EAP_MAX_METHODS &&
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(sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
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sm->user->methods[i].method != EAP_TYPE_NONE);
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if (sm->user->methods[i].vendor == EAP_VENDOR_IETF &&
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sm->user->methods[i].method == EAP_TYPE_PSK)
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if (i >= EAP_MAX_METHODS ||
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sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
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sm->user->methods[i].method != EAP_TYPE_PSK) {
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wpa_hexdump_ascii(MSG_DEBUG,
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"EAP-PSK: EAP-PSK not enabled for ID_P",
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data->id_p, data->id_p_len);
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data->state = FAILURE;
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if (sm->user->password == NULL ||
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sm->user->password_len != EAP_PSK_PSK_LEN) {
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wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: invalid password in "
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"user database for ID_P",
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data->id_p, data->id_p_len);
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data->state = FAILURE;
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if (eap_psk_key_setup(sm->user->password, data->ak, data->kdk)) {
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data->state = FAILURE;
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wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
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wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)",
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resp->rand_p, EAP_PSK_RAND_LEN);
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os_memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_LEN);
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/* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
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buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
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buf = os_malloc(buflen);
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data->state = FAILURE;
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os_memcpy(buf, data->id_p, data->id_p_len);
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pos = buf + data->id_p_len;
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os_memcpy(pos, data->id_s, data->id_s_len);
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pos += data->id_s_len;
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os_memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN);
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pos += EAP_PSK_RAND_LEN;
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os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
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if (omac1_aes_128(data->ak, buf, buflen, mac)) {
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data->state = FAILURE;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN);
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if (os_memcmp(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P");
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P",
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mac, EAP_PSK_MAC_LEN);
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data->state = FAILURE;
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static void eap_psk_process_4(struct eap_sm *sm,
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struct eap_psk_data *data,
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struct wpabuf *respData)
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const struct eap_psk_hdr_4 *resp;
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u8 *decrypted, nonce[16];
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if (data->state != PSK_3)
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wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4");
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pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &left);
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if (pos == NULL || left < sizeof(*resp)) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
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resp = (const struct eap_psk_hdr_4 *) pos;
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pos = (const u8 *) (resp + 1);
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left -= sizeof(*resp);
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left);
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if (left < 4 + 16 + 1) {
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wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
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"PSK-4 (len=%lu, expected 21)",
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(unsigned long) left);
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if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) {
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wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase");
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os_memset(nonce, 0, 12);
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os_memcpy(nonce + 12, pos, 4);
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decrypted = os_malloc(left);
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if (decrypted == NULL)
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os_memcpy(decrypted, pos, left);
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if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
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wpabuf_head(respData), 22, decrypted, left,
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wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
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data->state = FAILURE;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
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switch (decrypted[0] >> 6) {
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case EAP_PSK_R_FLAG_CONT:
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wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
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data->state = FAILURE;
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case EAP_PSK_R_FLAG_DONE_SUCCESS:
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wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
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data->state = SUCCESS;
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case EAP_PSK_R_FLAG_DONE_FAILURE:
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wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
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data->state = FAILURE;
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static void eap_psk_process(struct eap_sm *sm, void *priv,
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struct wpabuf *respData)
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struct eap_psk_data *data = priv;
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if (sm->user == NULL || sm->user->password == NULL) {
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wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not "
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data->state = FAILURE;
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pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len);
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if (pos == NULL || len < 1)
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switch (EAP_PSK_FLAGS_GET_T(*pos)) {
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eap_psk_process_2(sm, data, respData);
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eap_psk_process_4(sm, data, respData);
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static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv)
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struct eap_psk_data *data = priv;
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return data->state == SUCCESS || data->state == FAILURE;
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static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
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struct eap_psk_data *data = priv;
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if (data->state != SUCCESS)
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key = os_malloc(EAP_MSK_LEN);
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os_memcpy(key, data->msk, EAP_MSK_LEN);
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static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
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struct eap_psk_data *data = priv;
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if (data->state != SUCCESS)
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key = os_malloc(EAP_EMSK_LEN);
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os_memcpy(key, data->emsk, EAP_EMSK_LEN);
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static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv)
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struct eap_psk_data *data = priv;
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return data->state == SUCCESS;
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int eap_server_psk_register(void)
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struct eap_method *eap;
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eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
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EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
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eap->init = eap_psk_init;
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eap->reset = eap_psk_reset;
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eap->buildReq = eap_psk_buildReq;
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eap->check = eap_psk_check;
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eap->process = eap_psk_process;
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eap->isDone = eap_psk_isDone;
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eap->getKey = eap_psk_getKey;
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eap->isSuccess = eap_psk_isSuccess;
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eap->get_emsk = eap_psk_get_emsk;
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ret = eap_server_method_register(eap);
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eap_server_method_free(eap);