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/* dot11decrypt_ccmp.c
*
* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
* Copyright (c) 2006 CACE Technologies, Davis (California)
* All rights reserved.
*
* SPDX-License-Identifier: (BSD-3-Clause OR GPL-2.0-only)
*/
/*
* Note: This file was derived from the FreeBSD source code, RELENG 6,
* sys/net80211/ieee80211_crypto_ccmp.c
*/
/****************************************************************************/
/* File includes */
#include "config.h"
#include "dot11decrypt_system.h"
#include "dot11decrypt_util.h"
#include "dot11decrypt_int.h"
#include "dot11decrypt_debug.h"
#include <wsutil/wsgcrypt.h>
/****************************************************************************/
/* Internal definitions */
/****************************************************************************/
/* Internal macros */
#define READ_6(b0, b1, b2, b3, b4, b5) \
((((uint64_t)((uint16_t)((b4 << 0) | (b5 << 8)))) << 32) | \
((uint32_t)((b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24))))
/****************************************************************************/
/* Internal function prototypes declarations */
/****************************************************************************/
/* Function definitions */
/* From IEEE 802.11 2016 Chapter 12.5.3.3.4 Construct CCM nonce */
/* Nonce: Flags | A2 | PN */
static void ccmp_construct_nonce(
PDOT11DECRYPT_MAC_FRAME wh,
uint64_t pn,
uint8_t nonce[13])
{
uint8_t mgmt = (DOT11DECRYPT_TYPE(wh->fc[0]) == DOT11DECRYPT_TYPE_MANAGEMENT);
if (DOT11DECRYPT_IS_4ADDRESS(wh) && DOT11DECRYPT_IS_QOS_DATA(wh)) {
PDOT11DECRYPT_MAC_FRAME_ADDR4_QOS qwh4 =
(PDOT11DECRYPT_MAC_FRAME_ADDR4_QOS) wh;
nonce[0] = (uint8_t)(qwh4->qos[0] & 0x0f);/* just priority bits */
} else if (DOT11DECRYPT_IS_QOS_DATA(wh)) {
PDOT11DECRYPT_MAC_FRAME_QOS qwh =
(PDOT11DECRYPT_MAC_FRAME_QOS) wh;
nonce[0] = (uint8_t)(qwh->qos[0] & 0x0f); /* just priority bits */
} else {
nonce[0] = 0;
}
if (mgmt) {
nonce[0] |= 0x10; /* set MGMT flag */
}
DOT11DECRYPT_ADDR_COPY(nonce + 1, wh->addr2);
nonce[7] = (uint8_t)(pn >> 40);
nonce[8] = (uint8_t)(pn >> 32);
nonce[9] = (uint8_t)(pn >> 24);
nonce[10] = (uint8_t)(pn >> 16);
nonce[11] = (uint8_t)(pn >> 8);
nonce[12] = (uint8_t)(pn >> 0);
}
int Dot11DecryptCcmpDecrypt(
uint8_t *m,
int mac_header_len,
int len,
uint8_t *TK1,
int tk_len,
int mic_len)
{
PDOT11DECRYPT_MAC_FRAME wh;
uint8_t aad[30]; /* Max aad_len. See Table 12-1 IEEE 802.11 2016 */
uint8_t nonce[13];
uint8_t mic[16]; /* Big enough for CCMP-256 */
ssize_t data_len;
size_t aad_len;
int z = mac_header_len;
gcry_cipher_hd_t handle;
uint64_t pn;
uint8_t *ivp = m + z;
wh = (PDOT11DECRYPT_MAC_FRAME )m;
data_len = len - (z + DOT11DECRYPT_CCMP_HEADER + mic_len);
if (data_len < 1) {
return 0;
}
memcpy(mic, m + len - mic_len, mic_len);
pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
ccmp_construct_nonce(wh, pn, nonce);
dot11decrypt_construct_aad(wh, aad, &aad_len);
if (gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CCM, 0)) {
return 1;
}
if (gcry_cipher_setkey(handle, TK1, tk_len)) {
goto err_out;
}
if (gcry_cipher_setiv(handle, nonce, sizeof(nonce))) {
goto err_out;
}
uint64_t ccm_lengths[3];
ccm_lengths[0] = data_len;
ccm_lengths[1] = aad_len;
ccm_lengths[2] = mic_len;
if (gcry_cipher_ctl(handle, GCRYCTL_SET_CCM_LENGTHS, ccm_lengths, sizeof(ccm_lengths))) {
goto err_out;
}
if (gcry_cipher_authenticate(handle, aad, aad_len)) {
goto err_out;
}
if (gcry_cipher_decrypt(handle, m + z + DOT11DECRYPT_CCMP_HEADER, data_len, NULL, 0)) {
goto err_out;
}
if (gcry_cipher_checktag(handle, mic, mic_len)) {
goto err_out;
}
/* TODO replay check (IEEE 802.11i-2004, pg. 62) */
/* TODO PN must be incremental (IEEE 802.11i-2004, pg. 62) */
gcry_cipher_close(handle);
return 0;
err_out:
gcry_cipher_close(handle);
return 1;
}
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