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  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/types.h>
   9 #include <linux/crypto.h>
  10 #include <linux/export.h>
  11 #include <linux/err.h>
  12 #include <crypto/aes.h>
  13
  14 #include <net/mac80211.h>
  15 #include "key.h"
  16 #include "aes_cmac.h"
  17
  18 #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
  19 #define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
  20 #define AAD_LEN 20
  21
  22 static const u8 zero[CMAC_TLEN_256];
  23
  24 void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
  25                         const u8 *data, size_t data_len, u8 *mic)
  26 {
  27         SHASH_DESC_ON_STACK(desc, tfm);
  28         u8 out[AES_BLOCK_SIZE];
  29
  30         desc->tfm = tfm;
  31
  32         crypto_shash_init(desc);
  33         crypto_shash_update(desc, aad, AAD_LEN);
  34         crypto_shash_update(desc, data, data_len - CMAC_TLEN);
  35         crypto_shash_finup(desc, zero, CMAC_TLEN, out);
  36
  37         memcpy(mic, out, CMAC_TLEN);
  38 }
  39
  40 void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
  41                             const u8 *data, size_t data_len, u8 *mic)
  42 {
  43         SHASH_DESC_ON_STACK(desc, tfm);
  44
  45         desc->tfm = tfm;
  46
  47         crypto_shash_init(desc);
  48         crypto_shash_update(desc, aad, AAD_LEN);
  49         crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
  50         crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
  51 }
  52
  53 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
  54                                                   size_t key_len)
  55 {
  56         struct crypto_shash *tfm;
  57
  58         tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
  59         if (!IS_ERR(tfm))
  60                 crypto_shash_setkey(tfm, key, key_len);
  61
  62         return tfm;
  63 }
  64
  65 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
  66 {
  67         crypto_free_shash(tfm);
  68 }