hostap/src/eap_server/eap_psk.c

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/*
* hostapd / EAP-PSK (RFC 4764) server
* Copyright (c) 2005-2007, 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_server/eap_i.h"
#include "aes_wrap.h"
#include "eap_common/eap_psk_common.h"
struct eap_psk_data {
enum { PSK_1, PSK_3, SUCCESS, FAILURE } state;
u8 rand_s[EAP_PSK_RAND_LEN];
u8 rand_p[EAP_PSK_RAND_LEN];
u8 *id_p, *id_s;
size_t id_p_len, id_s_len;
u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
u8 msk[EAP_MSK_LEN];
u8 emsk[EAP_EMSK_LEN];
};
static void * eap_psk_init(struct eap_sm *sm)
{
struct eap_psk_data *data;
data = os_zalloc(sizeof(*data));
if (data == NULL)
return NULL;
data->state = PSK_1;
data->id_s = (u8 *) "hostapd";
data->id_s_len = 7;
return data;
}
static void eap_psk_reset(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
os_free(data->id_p);
os_free(data);
}
static struct wpabuf * eap_psk_build_1(struct eap_sm *sm,
struct eap_psk_data *data, u8 id)
{
struct wpabuf *req;
struct eap_psk_hdr_1 *psk;
wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-1 (sending)");
if (os_get_random(data->rand_s, EAP_PSK_RAND_LEN)) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
data->state = FAILURE;
return NULL;
}
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_S (server rand)",
data->rand_s, EAP_PSK_RAND_LEN);
req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
sizeof(*psk) + data->id_s_len,
EAP_CODE_REQUEST, id);
if (req == NULL) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory "
"request");
data->state = FAILURE;
return NULL;
}
psk = wpabuf_put(req, sizeof(*psk));
psk->flags = EAP_PSK_FLAGS_SET_T(0); /* T=0 */
os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
wpabuf_put_data(req, data->id_s, data->id_s_len);
return req;
}
static struct wpabuf * eap_psk_build_3(struct eap_sm *sm,
struct eap_psk_data *data, u8 id)
{
struct wpabuf *req;
struct eap_psk_hdr_3 *psk;
u8 *buf, *pchannel, nonce[16];
size_t buflen;
wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-3 (sending)");
req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
sizeof(*psk) + 4 + 16 + 1, EAP_CODE_REQUEST, id);
if (req == NULL) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory "
"request");
data->state = FAILURE;
return NULL;
}
psk = wpabuf_put(req, sizeof(*psk));
psk->flags = EAP_PSK_FLAGS_SET_T(2); /* T=2 */
os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
/* 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)
goto fail;
os_memcpy(buf, data->id_s, data->id_s_len);
os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
if (omac1_aes_128(data->ak, buf, buflen, psk->mac_s))
goto fail;
os_free(buf);
if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek, data->msk,
data->emsk))
goto fail;
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, sizeof(nonce));
pchannel = wpabuf_put(req, 4 + 16 + 1);
os_memcpy(pchannel, nonce + 12, 4);
os_memset(pchannel + 4, 0, 16); /* Tag */
pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (plaintext)",
pchannel, 4 + 16 + 1);
if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
wpabuf_head(req), 22,
pchannel + 4 + 16, 1, pchannel + 4))
goto fail;
wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (encrypted)",
pchannel, 4 + 16 + 1);
return req;
fail:
wpabuf_free(req);
data->state = FAILURE;
return NULL;
}
static struct wpabuf * eap_psk_buildReq(struct eap_sm *sm, void *priv, u8 id)
{
struct eap_psk_data *data = priv;
switch (data->state) {
case PSK_1:
return eap_psk_build_1(sm, data, id);
case PSK_3:
return eap_psk_build_3(sm, data, id);
default:
wpa_printf(MSG_DEBUG, "EAP-PSK: Unknown state %d in buildReq",
data->state);
break;
}
return NULL;
}
static Boolean eap_psk_check(struct eap_sm *sm, void *priv,
struct wpabuf *respData)
{
struct eap_psk_data *data = priv;
size_t len;
u8 t;
const u8 *pos;
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len);
if (pos == NULL || len < 1) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
return TRUE;
}
t = EAP_PSK_FLAGS_GET_T(*pos);
wpa_printf(MSG_DEBUG, "EAP-PSK: received frame: T=%d", t);
if (data->state == PSK_1 && t != 1) {
wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-2 - "
"ignore T=%d", t);
return TRUE;
}
if (data->state == PSK_3 && t != 3) {
wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-4 - "
"ignore T=%d", t);
return TRUE;
}
if ((t == 1 && len < sizeof(struct eap_psk_hdr_2)) ||
(t == 3 && len < sizeof(struct eap_psk_hdr_4))) {
wpa_printf(MSG_DEBUG, "EAP-PSK: Too short frame");
return TRUE;
}
return FALSE;
}
static void eap_psk_process_2(struct eap_sm *sm,
struct eap_psk_data *data,
struct wpabuf *respData)
{
const struct eap_psk_hdr_2 *resp;
u8 *pos, mac[EAP_PSK_MAC_LEN], *buf;
size_t left, buflen;
int i;
const u8 *cpos;
if (data->state != PSK_1)
return;
wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-2");
cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData,
&left);
if (cpos == NULL || left < sizeof(*resp)) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
return;
}
resp = (const struct eap_psk_hdr_2 *) cpos;
cpos = (const u8 *) (resp + 1);
left -= sizeof(*resp);
os_free(data->id_p);
data->id_p = os_malloc(left);
if (data->id_p == NULL) {
wpa_printf(MSG_INFO, "EAP-PSK: Failed to allocate memory for "
"ID_P");
return;
}
os_memcpy(data->id_p, cpos, left);
data->id_p_len = left;
wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PSK: ID_P",
data->id_p, data->id_p_len);
if (eap_user_get(sm, data->id_p, data->id_p_len, 0) < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: unknown ID_P",
data->id_p, data->id_p_len);
data->state = FAILURE;
return;
}
for (i = 0;
i < EAP_MAX_METHODS &&
(sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
sm->user->methods[i].method != EAP_TYPE_NONE);
i++) {
if (sm->user->methods[i].vendor == EAP_VENDOR_IETF &&
sm->user->methods[i].method == EAP_TYPE_PSK)
break;
}
if (i >= EAP_MAX_METHODS ||
sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
sm->user->methods[i].method != EAP_TYPE_PSK) {
wpa_hexdump_ascii(MSG_DEBUG,
"EAP-PSK: EAP-PSK not enabled for ID_P",
data->id_p, data->id_p_len);
data->state = FAILURE;
return;
}
if (sm->user->password == NULL ||
sm->user->password_len != EAP_PSK_PSK_LEN) {
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: invalid password in "
"user database for ID_P",
data->id_p, data->id_p_len);
data->state = FAILURE;
return;
}
if (eap_psk_key_setup(sm->user->password, data->ak, data->kdk)) {
data->state = FAILURE;
return;
}
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);
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)",
resp->rand_p, EAP_PSK_RAND_LEN);
os_memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_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) {
data->state = FAILURE;
return;
}
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, data->rand_s, EAP_PSK_RAND_LEN);
pos += EAP_PSK_RAND_LEN;
os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
if (omac1_aes_128(data->ak, buf, buflen, mac)) {
os_free(buf);
data->state = FAILURE;
return;
}
os_free(buf);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN);
if (os_memcmp(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P");
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P",
mac, EAP_PSK_MAC_LEN);
data->state = FAILURE;
return;
}
data->state = PSK_3;
}
static void eap_psk_process_4(struct eap_sm *sm,
struct eap_psk_data *data,
struct wpabuf *respData)
{
const struct eap_psk_hdr_4 *resp;
u8 *decrypted, nonce[16];
size_t left;
const u8 *pos, *tag;
if (data->state != PSK_3)
return;
wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4");
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &left);
if (pos == NULL || left < sizeof(*resp)) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
return;
}
resp = (const struct eap_psk_hdr_4 *) pos;
pos = (const u8 *) (resp + 1);
left -= sizeof(*resp);
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left);
if (left < 4 + 16 + 1) {
wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
"PSK-4 (len=%lu, expected 21)",
(unsigned long) left);
return;
}
if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) {
wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase");
return;
}
os_memset(nonce, 0, 12);
os_memcpy(nonce + 12, pos, 4);
pos += 4;
left -= 4;
tag = pos;
pos += 16;
left -= 16;
decrypted = os_malloc(left);
if (decrypted == NULL)
return;
os_memcpy(decrypted, pos, left);
if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
wpabuf_head(respData), 22, decrypted, left,
tag)) {
wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
os_free(decrypted);
data->state = FAILURE;
return;
}
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");
data->state = FAILURE;
break;
case EAP_PSK_R_FLAG_DONE_SUCCESS:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
data->state = SUCCESS;
break;
case EAP_PSK_R_FLAG_DONE_FAILURE:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
data->state = FAILURE;
break;
}
os_free(decrypted);
}
static void eap_psk_process(struct eap_sm *sm, void *priv,
struct wpabuf *respData)
{
struct eap_psk_data *data = priv;
const u8 *pos;
size_t len;
if (sm->user == NULL || sm->user->password == NULL) {
wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not "
"configured");
data->state = FAILURE;
return;
}
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len);
if (pos == NULL || len < 1)
return;
switch (EAP_PSK_FLAGS_GET_T(*pos)) {
case 1:
eap_psk_process_2(sm, data, respData);
break;
case 3:
eap_psk_process_4(sm, data, respData);
break;
}
}
static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
return data->state == SUCCESS || data->state == FAILURE;
}
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 != SUCCESS)
return NULL;
key = os_malloc(EAP_MSK_LEN);
if (key == NULL)
return NULL;
os_memcpy(key, data->msk, EAP_MSK_LEN);
*len = 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 != SUCCESS)
return NULL;
key = os_malloc(EAP_EMSK_LEN);
if (key == NULL)
return NULL;
os_memcpy(key, data->emsk, EAP_EMSK_LEN);
*len = EAP_EMSK_LEN;
return key;
}
static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
return data->state == SUCCESS;
}
int eap_server_psk_register(void)
{
struct eap_method *eap;
int ret;
eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
if (eap == NULL)
return -1;
eap->init = eap_psk_init;
eap->reset = eap_psk_reset;
eap->buildReq = eap_psk_buildReq;
eap->check = eap_psk_check;
eap->process = eap_psk_process;
eap->isDone = eap_psk_isDone;
eap->getKey = eap_psk_getKey;
eap->isSuccess = eap_psk_isSuccess;
eap->get_emsk = eap_psk_get_emsk;
ret = eap_server_method_register(eap);
if (ret)
eap_server_method_free(eap);
return ret;
}