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/*
* EAP peer method: EAP-PSK (RFC 4764)
* Copyright (c) 2004-2007, 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.
*
* Note: EAP-PSK is an EAP authentication method and as such, completely
* different from WPA-PSK. This file is not needed for WPA-PSK functionality.
*/
#include "includes.h"
#include "common.h"
#include "eap_i.h"
#include "config_ssid.h"
#include "md5.h"
#include "aes_wrap.h"
#include "eap_psk_common.h"
struct eap_psk_data {
enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
u8 rand_p[EAP_PSK_RAND_LEN];
u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
u8 *id_s, *id_p;
size_t id_s_len, id_p_len;
u8 msk[EAP_MSK_LEN];
u8 emsk[EAP_EMSK_LEN];
};
static void * eap_psk_init(struct eap_sm *sm)
{
struct wpa_ssid *config = eap_get_config(sm);
struct eap_psk_data *data;
if (config == NULL || !config->eappsk) {
wpa_printf(MSG_INFO, "EAP-PSK: pre-shared key not configured");
return NULL;
}
data = os_zalloc(sizeof(*data));
if (data == NULL)
return NULL;
eap_psk_key_setup(config->eappsk, data->ak, data->kdk);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
data->state = PSK_INIT;
if (config->nai) {
data->id_p = os_malloc(config->nai_len);
if (data->id_p)
os_memcpy(data->id_p, config->nai, config->nai_len);
data->id_p_len = config->nai_len;
}
if (data->id_p == NULL) {
wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
os_free(data);
return NULL;
}
return data;
}
static void eap_psk_deinit(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
os_free(data->id_s);
os_free(data->id_p);
os_free(data);
}
static u8 * eap_psk_process_1(struct eap_psk_data *data,
struct eap_method_ret *ret,
const u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
const struct eap_psk_hdr_1 *hdr1;
struct eap_psk_hdr_2 *hdr2;
u8 *resp, *buf, *pos;
size_t buflen;
wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
hdr1 = (const struct eap_psk_hdr_1 *) reqData;
if (reqDataLen < sizeof(*hdr1) ||
be_to_host16(hdr1->length) < sizeof(*hdr1) ||
be_to_host16(hdr1->length) > reqDataLen) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
"length (%lu %d; expected %lu or more)",
(unsigned long) reqDataLen,
be_to_host16(hdr1->length),
(unsigned long) sizeof(*hdr1));
ret->ignore = TRUE;
return NULL;
}
wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
if (EAP_PSK_FLAGS_GET_T(hdr1->flags) != 0) {
wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
EAP_PSK_FLAGS_GET_T(hdr1->flags));
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
EAP_PSK_RAND_LEN);
os_free(data->id_s);
data->id_s_len = be_to_host16(hdr1->length) - sizeof(*hdr1);
data->id_s = os_malloc(data->id_s_len);
if (data->id_s == NULL) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
"ID_S (len=%lu)", (unsigned long) data->id_s_len);
ret->ignore = TRUE;
return NULL;
}
os_memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
data->id_s, data->id_s_len);
if (hostapd_get_rand(data->rand_p, EAP_PSK_RAND_LEN)) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
ret->ignore = TRUE;
return NULL;
}
*respDataLen = sizeof(*hdr2) + data->id_p_len;
resp = os_malloc(*respDataLen);
if (resp == NULL)
return NULL;
hdr2 = (struct eap_psk_hdr_2 *) resp;
hdr2->code = EAP_CODE_RESPONSE;
hdr2->identifier = hdr1->identifier;
hdr2->length = host_to_be16(*respDataLen);
hdr2->type = EAP_TYPE_PSK;
hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
os_memcpy((u8 *) (hdr2 + 1), data->id_p, data->id_p_len);
/* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
buf = os_malloc(buflen);
if (buf == NULL) {
os_free(resp);
return NULL;
}
os_memcpy(buf, data->id_p, data->id_p_len);
pos = buf + data->id_p_len;
os_memcpy(pos, data->id_s, data->id_s_len);
pos += data->id_s_len;
os_memcpy(pos, hdr1->rand_s, EAP_PSK_RAND_LEN);
pos += EAP_PSK_RAND_LEN;
os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p);
os_free(buf);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
EAP_PSK_RAND_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
(u8 *) (hdr2 + 1), data->id_p_len);
data->state = PSK_MAC_SENT;
return resp;
}
static u8 * eap_psk_process_3(struct eap_psk_data *data,
struct eap_method_ret *ret,
const u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
const struct eap_psk_hdr_3 *hdr3;
struct eap_psk_hdr_4 *hdr4;
u8 *resp, *buf, *rpchannel, nonce[16], *decrypted;
const u8 *pchannel, *tag, *msg;
u8 mac[EAP_PSK_MAC_LEN];
size_t buflen, left, data_len;
int failed = 0;
wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
hdr3 = (const struct eap_psk_hdr_3 *) reqData;
left = be_to_host16(hdr3->length);
if (left < sizeof(*hdr3) || reqDataLen < left) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
"length (%lu %d; expected %lu)",
(unsigned long) reqDataLen,
be_to_host16(hdr3->length),
(unsigned long) sizeof(*hdr3));
ret->ignore = TRUE;
return NULL;
}
left -= sizeof(*hdr3);
pchannel = (const u8 *) (hdr3 + 1);
wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
EAP_PSK_FLAGS_GET_T(hdr3->flags));
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
EAP_PSK_RAND_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
if (left < 4 + 16 + 1) {
wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
"third message (len=%lu, expected 21)",
(unsigned long) left);
ret->ignore = TRUE;
return NULL;
}
/* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
buflen = data->id_s_len + EAP_PSK_RAND_LEN;
buf = os_malloc(buflen);
if (buf == NULL)
return NULL;
os_memcpy(buf, data->id_s, data->id_s_len);
os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
omac1_aes_128(data->ak, buf, buflen, mac);
os_free(buf);
if (os_memcmp(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
"message");
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
data->msk, data->emsk);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
os_memset(nonce, 0, 12);
os_memcpy(nonce + 12, pchannel, 4);
pchannel += 4;
left -= 4;
tag = pchannel;
pchannel += 16;
left -= 16;
msg = pchannel;
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
nonce, sizeof(nonce));
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr", reqData, 5);
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
decrypted = os_malloc(left);
if (decrypted == NULL) {
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
os_memcpy(decrypted, msg, left);
if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
reqData, 22, decrypted, left, tag)) {
wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
os_free(decrypted);
return NULL;
}
wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
decrypted, left);
/* Verify R flag */
switch (decrypted[0] >> 6) {
case EAP_PSK_R_FLAG_CONT:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
failed = 1;
break;
case EAP_PSK_R_FLAG_DONE_SUCCESS:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
break;
case EAP_PSK_R_FLAG_DONE_FAILURE:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
"authentication");
failed = 1;
break;
}
*respDataLen = sizeof(*hdr4) + 4 + 16 + 1;
resp = os_malloc(*respDataLen + 1);
if (resp == NULL) {
os_free(decrypted);
return NULL;
}
hdr4 = (struct eap_psk_hdr_4 *) resp;
hdr4->code = EAP_CODE_RESPONSE;
hdr4->identifier = hdr3->identifier;
hdr4->length = host_to_be16(*respDataLen);
hdr4->type = EAP_TYPE_PSK;
hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
rpchannel = (u8 *) (hdr4 + 1);
/* nonce++ */
inc_byte_array(nonce, sizeof(nonce));
os_memcpy(rpchannel, nonce + 12, 4);
data_len = 1;
if (decrypted[0] & EAP_PSK_E_FLAG) {
wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
failed = 1;
rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
EAP_PSK_E_FLAG;
if (left > 1) {
/* Add empty EXT_Payload with same EXT_Type */
(*respDataLen)++;
hdr4->length = host_to_be16(*respDataLen);
rpchannel[4 + 16 + 1] = decrypted[1];
data_len++;
}
} else if (failed)
rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
else
rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
rpchannel + 4 + 16, data_len);
aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), resp, 22,
rpchannel + 4 + 16, data_len, rpchannel + 4);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
rpchannel, 4 + 16 + data_len);
wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
failed ? "un" : "");
data->state = PSK_DONE;
ret->methodState = METHOD_DONE;
ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
os_free(decrypted);
return resp;
}
static u8 * eap_psk_process(struct eap_sm *sm, void *priv,
struct eap_method_ret *ret,
const u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
struct eap_psk_data *data = priv;
const u8 *pos;
u8 *resp = NULL;
size_t len;
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
reqData, reqDataLen, &len);
if (pos == NULL) {
ret->ignore = TRUE;
return NULL;
}
len += sizeof(struct eap_hdr) + 1;
ret->ignore = FALSE;
ret->methodState = METHOD_MAY_CONT;
ret->decision = DECISION_FAIL;
ret->allowNotifications = TRUE;
switch (data->state) {
case PSK_INIT:
resp = eap_psk_process_1(data, ret, reqData, len,
respDataLen);
break;
case PSK_MAC_SENT:
resp = eap_psk_process_3(data, ret, reqData, len,
respDataLen);
break;
case PSK_DONE:
wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
"unexpected message");
ret->ignore = TRUE;
return NULL;
}
if (ret->methodState == METHOD_DONE) {
ret->allowNotifications = FALSE;
}
return resp;
}
static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
return data->state == PSK_DONE;
}
static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
struct eap_psk_data *data = priv;
u8 *key;
if (data->state != PSK_DONE)
return NULL;
key = os_malloc(EAP_MSK_LEN);
if (key == NULL)
return NULL;
*len = EAP_MSK_LEN;
os_memcpy(key, data->msk, EAP_MSK_LEN);
return key;
}
static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
{
struct eap_psk_data *data = priv;
u8 *key;
if (data->state != PSK_DONE)
return NULL;
key = os_malloc(EAP_EMSK_LEN);
if (key == NULL)
return NULL;
*len = EAP_EMSK_LEN;
os_memcpy(key, data->emsk, EAP_EMSK_LEN);
return key;
}
int eap_peer_psk_register(void)
{
struct eap_method *eap;
int ret;
eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
if (eap == NULL)
return -1;
eap->init = eap_psk_init;
eap->deinit = eap_psk_deinit;
eap->process = eap_psk_process;
eap->isKeyAvailable = eap_psk_isKeyAvailable;
eap->getKey = eap_psk_getKey;
eap->get_emsk = eap_psk_get_emsk;
ret = eap_peer_method_register(eap);
if (ret)
eap_peer_method_free(eap);
return ret;
}