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 }
93
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