forked from osmocom/wireshark
112 lines
2.8 KiB
C
112 lines
2.8 KiB
C
/* dot11decrypt_gcmp.c
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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/****************************************************************************/
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/* File includes */
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#include "config.h"
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#include "dot11decrypt_debug.h"
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#include "dot11decrypt_int.h"
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#include "dot11decrypt_system.h"
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#include "dot11decrypt_util.h"
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#include <glib.h>
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#include <wsutil/wsgcrypt.h>
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/****************************************************************************/
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/* Internal definitions */
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/****************************************************************************/
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/* Internal macros */
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#define READ_6(b0, b1, b2, b3, b4, b5) \
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((((guint64)((guint16)((b4 << 0) | (b5 << 8)))) << 32) | \
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((guint32)((b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24))))
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/****************************************************************************/
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/* Internal function prototypes declarations */
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/****************************************************************************/
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/* Function definitions */
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/* From IEEE 802.11 2016 Chapter 12.5.5.3.4 Construct GCM nonce */
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static void
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gcmp_construct_nonce(
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PDOT11DECRYPT_MAC_FRAME wh,
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guint64 pn,
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guint8 nonce[12])
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{
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/* Nonce: A2 | PN */
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DOT11DECRYPT_ADDR_COPY(nonce, wh->addr2);
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nonce[6] = (guint8)(pn >> 40);
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nonce[7] = (guint8)(pn >> 32);
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nonce[8] = (guint8)(pn >> 24);
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nonce[9] = (guint8)(pn >> 16);
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nonce[10] = (guint8)(pn >> 8);
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nonce[11] = (guint8)(pn >> 0);
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}
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int Dot11DecryptGcmpDecrypt(
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guint8 *m,
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int mac_header_len,
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int len,
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guint8 *TK1,
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int tk_len)
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{
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PDOT11DECRYPT_MAC_FRAME wh;
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guint8 aad[30];
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guint8 nonce[12];
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guint8 mic[16];
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ssize_t data_len;
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size_t aad_len;
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int z = mac_header_len;
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gcry_cipher_hd_t handle;
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guint64 pn;
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guint8 *ivp = m + z;
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wh = (PDOT11DECRYPT_MAC_FRAME )m;
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data_len = len - (z + DOT11DECRYPT_GCMP_HEADER + sizeof(mic));
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if (data_len < 1) {
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return 0;
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}
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memcpy(mic, m + len - sizeof(mic), sizeof(mic));
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pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
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gcmp_construct_nonce(wh, pn, nonce);
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dot11decrypt_construct_aad(wh, aad, &aad_len);
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if (gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_GCM, 0)) {
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return 1;
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}
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if (gcry_cipher_setkey(handle, TK1, tk_len)) {
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goto err_out;
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}
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if (gcry_cipher_setiv(handle, nonce, sizeof(nonce))) {
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goto err_out;
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}
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if (gcry_cipher_authenticate(handle, aad, aad_len)) {
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goto err_out;
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}
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if (gcry_cipher_decrypt(handle, m + z + DOT11DECRYPT_GCMP_HEADER, data_len, NULL, 0)) {
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goto err_out;
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}
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if (gcry_cipher_checktag(handle, mic, sizeof(mic))) {
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goto err_out;
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}
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/* TODO replay check (IEEE 802.11i-2004, pg. 62) */
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/* TODO PN must be incremental (IEEE 802.11i-2004, pg. 62) */
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gcry_cipher_close(handle);
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return 0;
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err_out:
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gcry_cipher_close(handle);
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return 1;
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}
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