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 AAD_LEN 20
20
21static const u8 zero[IEEE80211_CMAC_256_MIC_LEN];
22
23int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
24 const u8 *data, size_t data_len, u8 *mic,
25 unsigned int mic_len)
26{
27 int err;
28 SHASH_DESC_ON_STACK(desc, tfm);
29 u8 out[AES_BLOCK_SIZE];
30 const __le16 *fc;
31
32 desc->tfm = tfm;
33
34 err = crypto_shash_init(desc);
35 if (err)
36 return err;
37 err = crypto_shash_update(desc, data: aad, AAD_LEN);
38 if (err)
39 return err;
40 fc = (const __le16 *)aad;
41 if (ieee80211_is_beacon(fc: *fc)) {
42 /* mask Timestamp field to zero */
43 err = crypto_shash_update(desc, data: zero, len: 8);
44 if (err)
45 return err;
46 err = crypto_shash_update(desc, data: data + 8,
47 len: data_len - 8 - mic_len);
48 if (err)
49 return err;
50 } else {
51 err = crypto_shash_update(desc, data, len: data_len - mic_len);
52 if (err)
53 return err;
54 }
55 err = crypto_shash_finup(desc, data: zero, len: mic_len, out);
56 if (err)
57 return err;
58 memcpy(mic, out, mic_len);
59
60 return 0;
61}
62
63struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
64 size_t key_len)
65{
66 struct crypto_shash *tfm;
67
68 tfm = crypto_alloc_shash(alg_name: "cmac(aes)", type: 0, mask: 0);
69 if (!IS_ERR(ptr: tfm)) {
70 int err = crypto_shash_setkey(tfm, key, keylen: key_len);
71
72 if (err) {
73 crypto_free_shash(tfm);
74 return ERR_PTR(error: err);
75 }
76 }
77
78 return tfm;
79}
80
81void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
82{
83 crypto_free_shash(tfm);
84}
85

source code of linux/net/mac80211/aes_cmac.c