epan/crypt/dot11decrypt_ccmp.c

   1 /* dot11decrypt_ccmp.c
   2  *
   3  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
   4  * Copyright (c) 2006 CACE Technologies, Davis (California)
   5  * All rights reserved.
   6  *
   7  * SPDX-License-Identifier: (BSD-3-Clause OR GPL-2.0-only)
   8  */
   9
  10 /*
  11  * Note: This file was derived from the FreeBSD source code, RELENG 6,
  12  *              sys/net80211/ieee80211_crypto_ccmp.c
  13  */
  14
  15 /****************************************************************************/
  16 /* File includes                                                                */
  17 #include "config.h"
  18
  19 #include "dot11decrypt_debug.h"
  20 #include "dot11decrypt_system.h"
  21 #include "dot11decrypt_util.h"
  22 #include "dot11decrypt_int.h"
  23
  24 #include <wsutil/wsgcrypt.h>
  25
  26 /****************************************************************************/
  27 /*      Internal definitions                                                    */
  28
  29 /****************************************************************************/
  30 /* Internal macros                                                              */
  31
  32 #define READ_6(b0, b1, b2, b3, b4, b5) \
  33         ((((uint64_t)((uint16_t)((b4 << 0) | (b5 << 8)))) << 32) | \
  34             ((uint32_t)((b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24))))
  35
  36 /****************************************************************************/
  37 /* Internal function prototypes declarations                                    */
  38
  39 /****************************************************************************/
  40 /* Function definitions                                                 */
  41
  42 /* From IEEE 802.11 2016 Chapter 12.5.3.3.4 Construct CCM nonce */
  43 /* Nonce: Flags | A2 | PN */
  44 static void ccmp_construct_nonce(
  45         PDOT11DECRYPT_MAC_FRAME wh,
  46         uint64_t pn,
  47         uint8_t nonce[13])
  48 {
  49         uint8_t mgmt = (DOT11DECRYPT_TYPE(wh->fc[0]) == DOT11DECRYPT_TYPE_MANAGEMENT);
  50
  51         if (DOT11DECRYPT_IS_4ADDRESS(wh) && DOT11DECRYPT_IS_QOS_DATA(wh)) {
  52                 PDOT11DECRYPT_MAC_FRAME_ADDR4_QOS qwh4 =
  53                         (PDOT11DECRYPT_MAC_FRAME_ADDR4_QOS) wh;
  54                 nonce[0] = (uint8_t)(qwh4->qos[0] & 0x0f);/* just priority bits */
  55         } else if (DOT11DECRYPT_IS_QOS_DATA(wh)) {
  56                 PDOT11DECRYPT_MAC_FRAME_QOS qwh =
  57                         (PDOT11DECRYPT_MAC_FRAME_QOS) wh;
  58                         nonce[0] = (uint8_t)(qwh->qos[0] & 0x0f); /* just priority bits */
  59         } else {
  60                 nonce[0] = 0;
  61         }
  62         if (mgmt) {
  63                 nonce[0] |= 0x10; /* set MGMT flag */
  64         }
  65
  66         DOT11DECRYPT_ADDR_COPY(nonce + 1, wh->addr2);
  67         nonce[7] = (uint8_t)(pn >> 40);
  68         nonce[8] = (uint8_t)(pn >> 32);
  69         nonce[9] = (uint8_t)(pn >> 24);
  70         nonce[10] = (uint8_t)(pn >> 16);
  71         nonce[11] = (uint8_t)(pn >> 8);
  72         nonce[12] = (uint8_t)(pn >> 0);
  73 }
  74
  75 int Dot11DecryptCcmpDecrypt(
  76         uint8_t *m,
  77         int mac_header_len,
  78         int len,
  79         uint8_t *TK1,
  80         int tk_len,
  81         int mic_len)
  82 {
  83         PDOT11DECRYPT_MAC_FRAME wh;
  84         uint8_t aad[30]; /* Max aad_len. See Table 12-1 IEEE 802.11 2016 */
  85         uint8_t nonce[13];
  86         uint8_t mic[16]; /* Big enough for CCMP-256 */
  87         ssize_t data_len;
  88         size_t aad_len;
  89         int z = mac_header_len;
  90         gcry_cipher_hd_t handle;
  91         uint64_t pn;
  92         uint8_t *ivp = m + z;
  93
  94         wh = (PDOT11DECRYPT_MAC_FRAME )m;
  95         data_len = len - (z + DOT11DECRYPT_CCMP_HEADER + mic_len);
  96         if (data_len < 1) {
  97                 return 0;
  98         }
  99
 100         memcpy(mic, m + len - mic_len, mic_len);
 101         pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
 102         ccmp_construct_nonce(wh, pn, nonce);
 103         dot11decrypt_construct_aad(wh, aad, &aad_len);
 104
 105         if (gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CCM, 0)) {
 106                 return 1;
 107         }
 108         if (gcry_cipher_setkey(handle, TK1, tk_len)) {
 109                 goto err_out;
 110         }
 111         if (gcry_cipher_setiv(handle, nonce, sizeof(nonce))) {
 112                 goto err_out;
 113         }
 114
 115         uint64_t ccm_lengths[3];
 116         ccm_lengths[0] = data_len;
 117         ccm_lengths[1] = aad_len;
 118         ccm_lengths[2] = mic_len;
 119         if (gcry_cipher_ctl(handle, GCRYCTL_SET_CCM_LENGTHS, ccm_lengths, sizeof(ccm_lengths))) {
 120                 goto err_out;
 121         }
 122         if (gcry_cipher_authenticate(handle, aad, aad_len)) {
 123                 goto err_out;
 124         }
 125         if (gcry_cipher_decrypt(handle, m + z + DOT11DECRYPT_CCMP_HEADER, data_len, NULL, 0)) {
 126                 goto err_out;
 127         }
 128         if (gcry_cipher_checktag(handle, mic, mic_len)) {
 129                 goto err_out;
 130         }
 131
 132         /* TODO replay check    (IEEE 802.11i-2004, pg. 62)                     */
 133         /* TODO PN must be incremental (IEEE 802.11i-2004, pg. 62)              */
 134
 135         gcry_cipher_close(handle);
 136         return 0;
 137 err_out:
 138         gcry_cipher_close(handle);
 139         return 1;
 140 }