net/mac80211/aes_cmac.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
   4  * Copyright 2008, Jouni Malinen <j@w1.fi>
   5  * Copyright (C) 2020 Intel Corporation
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/types.h>
  10 #include <linux/crypto.h>
  11 #include <linux/export.h>
  12 #include <linux/err.h>
  13 #include <crypto/aes.h>
  14
  15 #include <net/mac80211.h>
  16 #include "key.h"
  17 #include "aes_cmac.h"
  18
  19 #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
  20 #define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
  21 #define AAD_LEN 20
  22
  23 static const u8 zero[CMAC_TLEN_256];
  24
  25 void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
  26                         const u8 *data, size_t data_len, u8 *mic)
  27 {
  28         SHASH_DESC_ON_STACK(desc, tfm);
  29         u8 out[AES_BLOCK_SIZE];
  30         const __le16 *fc;
  31
  32         desc->tfm = tfm;
  33
  34         crypto_shash_init(desc);
  35         crypto_shash_update(desc, aad, AAD_LEN);
  36         fc = (const __le16 *)aad;
  37         if (ieee80211_is_beacon(*fc)) {
  38                 /* mask Timestamp field to zero */
  39                 crypto_shash_update(desc, zero, 8);
  40                 crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN);
  41         } else {
  42                 crypto_shash_update(desc, data, data_len - CMAC_TLEN);
  43         }
  44         crypto_shash_finup(desc, zero, CMAC_TLEN, out);
  45
  46         memcpy(mic, out, CMAC_TLEN);
  47 }
  48
  49 void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
  50                             const u8 *data, size_t data_len, u8 *mic)
  51 {
  52         SHASH_DESC_ON_STACK(desc, tfm);
  53         const __le16 *fc;
  54
  55         desc->tfm = tfm;
  56
  57         crypto_shash_init(desc);
  58         crypto_shash_update(desc, aad, AAD_LEN);
  59         fc = (const __le16 *)aad;
  60         if (ieee80211_is_beacon(*fc)) {
  61                 /* mask Timestamp field to zero */
  62                 crypto_shash_update(desc, zero, 8);
  63                 crypto_shash_update(desc, data + 8,
  64                                     data_len - 8 - CMAC_TLEN_256);
  65         } else {
  66                 crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
  67         }
  68         crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
  69 }
  70
  71 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
  72                                                   size_t key_len)
  73 {
  74         struct crypto_shash *tfm;
  75
  76         tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
  77         if (!IS_ERR(tfm)) {
  78                 int err = crypto_shash_setkey(tfm, key, key_len);
  79
  80                 if (err) {
  81                         crypto_free_shash(tfm);
  82                         return ERR_PTR(err);
  83                 }
  84         }
  85
  86         return tfm;
  87 }
  88
  89 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
  90 {
  91         crypto_free_shash(tfm);
  92 }