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* EAP peer method: EAP-PSK (RFC 4764)
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* Copyright (c) 2004-2007, 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 "config_ssid.h"
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#include "eap_psk_common.h"
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enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
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u8 rand_p[EAP_PSK_RAND_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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size_t id_s_len, id_p_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 wpa_ssid *config = eap_get_config(sm);
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struct eap_psk_data *data;
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if (config == NULL || !config->eappsk) {
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wpa_printf(MSG_INFO, "EAP-PSK: pre-shared key not configured");
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data = os_zalloc(sizeof(*data));
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eap_psk_key_setup(config->eappsk, data->ak, data->kdk);
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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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data->state = PSK_INIT;
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data->id_p = os_malloc(config->nai_len);
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os_memcpy(data->id_p, config->nai, config->nai_len);
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data->id_p_len = config->nai_len;
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if (data->id_p == NULL) {
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wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
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static void eap_psk_deinit(struct eap_sm *sm, void *priv)
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struct eap_psk_data *data = priv;
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static u8 * eap_psk_process_1(struct eap_psk_data *data,
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struct eap_method_ret *ret,
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const u8 *reqData, size_t reqDataLen,
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const struct eap_psk_hdr_1 *hdr1;
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struct eap_psk_hdr_2 *hdr2;
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wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
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hdr1 = (const struct eap_psk_hdr_1 *) reqData;
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if (reqDataLen < sizeof(*hdr1) ||
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be_to_host16(hdr1->length) < sizeof(*hdr1) ||
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be_to_host16(hdr1->length) > reqDataLen) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
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"length (%lu %d; expected %lu or more)",
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(unsigned long) reqDataLen,
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be_to_host16(hdr1->length),
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(unsigned long) sizeof(*hdr1));
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wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
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if (EAP_PSK_FLAGS_GET_T(hdr1->flags) != 0) {
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wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
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EAP_PSK_FLAGS_GET_T(hdr1->flags));
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ret->methodState = METHOD_DONE;
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ret->decision = DECISION_FAIL;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
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data->id_s_len = be_to_host16(hdr1->length) - sizeof(*hdr1);
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data->id_s = os_malloc(data->id_s_len);
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if (data->id_s == NULL) {
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wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
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"ID_S (len=%lu)", (unsigned long) data->id_s_len);
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os_memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
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wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
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data->id_s, data->id_s_len);
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if (hostapd_get_rand(data->rand_p, EAP_PSK_RAND_LEN)) {
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wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
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*respDataLen = sizeof(*hdr2) + data->id_p_len;
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resp = os_malloc(*respDataLen);
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hdr2 = (struct eap_psk_hdr_2 *) resp;
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hdr2->code = EAP_CODE_RESPONSE;
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hdr2->identifier = hdr1->identifier;
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hdr2->length = host_to_be16(*respDataLen);
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hdr2->type = EAP_TYPE_PSK;
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hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
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os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
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os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
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os_memcpy((u8 *) (hdr2 + 1), data->id_p, data->id_p_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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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, hdr1->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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omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p);
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
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wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
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(u8 *) (hdr2 + 1), data->id_p_len);
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data->state = PSK_MAC_SENT;
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static u8 * eap_psk_process_3(struct eap_psk_data *data,
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struct eap_method_ret *ret,
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const u8 *reqData, size_t reqDataLen,
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const struct eap_psk_hdr_3 *hdr3;
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struct eap_psk_hdr_4 *hdr4;
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u8 *resp, *buf, *rpchannel, nonce[16], *decrypted;
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const u8 *pchannel, *tag, *msg;
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u8 mac[EAP_PSK_MAC_LEN];
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size_t buflen, left, data_len;
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wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
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hdr3 = (const struct eap_psk_hdr_3 *) reqData;
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left = be_to_host16(hdr3->length);
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if (left < sizeof(*hdr3) || reqDataLen < left) {
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wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
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"length (%lu %d; expected %lu)",
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(unsigned long) reqDataLen,
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be_to_host16(hdr3->length),
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(unsigned long) sizeof(*hdr3));
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left -= sizeof(*hdr3);
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pchannel = (const u8 *) (hdr3 + 1);
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wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
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if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
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wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
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EAP_PSK_FLAGS_GET_T(hdr3->flags));
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ret->methodState = METHOD_DONE;
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ret->decision = DECISION_FAIL;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, 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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"third message (len=%lu, expected 21)",
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(unsigned long) left);
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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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omac1_aes_128(data->ak, buf, buflen, mac);
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if (os_memcmp(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
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wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
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ret->methodState = METHOD_DONE;
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ret->decision = DECISION_FAIL;
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wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
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eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
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data->msk, data->emsk);
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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, 12);
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os_memcpy(nonce + 12, pchannel, 4);
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
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nonce, sizeof(nonce));
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr", reqData, 5);
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wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
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decrypted = os_malloc(left);
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if (decrypted == NULL) {
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ret->methodState = METHOD_DONE;
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ret->decision = DECISION_FAIL;
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os_memcpy(decrypted, msg, left);
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if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
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reqData, 22, decrypted, left, tag)) {
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wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
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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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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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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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wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
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*respDataLen = sizeof(*hdr4) + 4 + 16 + 1;
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resp = os_malloc(*respDataLen + 1);
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hdr4 = (struct eap_psk_hdr_4 *) resp;
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hdr4->code = EAP_CODE_RESPONSE;
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hdr4->identifier = hdr3->identifier;
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hdr4->length = host_to_be16(*respDataLen);
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hdr4->type = EAP_TYPE_PSK;
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hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
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os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
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rpchannel = (u8 *) (hdr4 + 1);
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inc_byte_array(nonce, sizeof(nonce));
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os_memcpy(rpchannel, nonce + 12, 4);
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if (decrypted[0] & EAP_PSK_E_FLAG) {
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wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
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rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
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/* Add empty EXT_Payload with same EXT_Type */
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hdr4->length = host_to_be16(*respDataLen);
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rpchannel[4 + 16 + 1] = decrypted[1];
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rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
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rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
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rpchannel + 4 + 16, data_len);
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aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), resp, 22,
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rpchannel + 4 + 16, data_len, rpchannel + 4);
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wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
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rpchannel, 4 + 16 + data_len);
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wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
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data->state = PSK_DONE;
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ret->methodState = METHOD_DONE;
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ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
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static u8 * eap_psk_process(struct eap_sm *sm, void *priv,
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struct eap_method_ret *ret,
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const u8 *reqData, size_t reqDataLen,
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struct eap_psk_data *data = priv;
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pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
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reqData, reqDataLen, &len);
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len += sizeof(struct eap_hdr) + 1;
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ret->methodState = METHOD_MAY_CONT;
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ret->decision = DECISION_FAIL;
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ret->allowNotifications = TRUE;
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switch (data->state) {
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resp = eap_psk_process_1(data, ret, reqData, len,
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resp = eap_psk_process_3(data, ret, reqData, len,
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wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
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"unexpected message");
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if (ret->methodState == METHOD_DONE) {
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ret->allowNotifications = FALSE;
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static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
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struct eap_psk_data *data = priv;
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return data->state == PSK_DONE;
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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 != PSK_DONE)
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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 != PSK_DONE)
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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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int eap_peer_psk_register(void)
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struct eap_method *eap;
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eap = eap_peer_method_alloc(EAP_PEER_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->deinit = eap_psk_deinit;
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eap->process = eap_psk_process;
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eap->isKeyAvailable = eap_psk_isKeyAvailable;
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eap->getKey = eap_psk_getKey;
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eap->get_emsk = eap_psk_get_emsk;
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ret = eap_peer_method_register(eap);
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eap_peer_method_free(eap);