LXR linux/net/mac80211/aes

   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
  23static const u8 zero[CMAC_TLEN_256];
  24
  25void 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
  49void 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
  71struct 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
  89void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
  90{
  91        crypto_free_shash(tfm);
  92}
  93