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
ieee80211_aes_cmac(struct crypto_shash * tfm,const u8 * aad,const u8 * data,size_t data_len,u8 * mic)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 const __le16 *fc;
30
31 desc->tfm = tfm;
32
33 crypto_shash_init(desc);
34 crypto_shash_update(desc, aad, AAD_LEN);
35 fc = (const __le16 *)aad;
36 if (ieee80211_is_beacon(*fc)) {
37 /* mask Timestamp field to zero */
38 crypto_shash_update(desc, zero, 8);
39 crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN);
40 } else {
41 crypto_shash_update(desc, data, data_len - CMAC_TLEN);
42 }
43 crypto_shash_finup(desc, zero, CMAC_TLEN, out);
44
45 memcpy(mic, out, CMAC_TLEN);
46 }
47
ieee80211_aes_cmac_256(struct crypto_shash * tfm,const u8 * aad,const u8 * data,size_t data_len,u8 * mic)48 void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
49 const u8 *data, size_t data_len, u8 *mic)
50 {
51 SHASH_DESC_ON_STACK(desc, tfm);
52 const __le16 *fc;
53
54 desc->tfm = tfm;
55
56 crypto_shash_init(desc);
57 crypto_shash_update(desc, aad, AAD_LEN);
58 fc = (const __le16 *)aad;
59 if (ieee80211_is_beacon(*fc)) {
60 /* mask Timestamp field to zero */
61 crypto_shash_update(desc, zero, 8);
62 crypto_shash_update(desc, data + 8,
63 data_len - 8 - CMAC_TLEN_256);
64 } else {
65 crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
66 }
67 crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
68 }
69
ieee80211_aes_cmac_key_setup(const u8 key[],size_t key_len)70 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
71 size_t key_len)
72 {
73 struct crypto_shash *tfm;
74
75 tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
76 if (!IS_ERR(tfm))
77 crypto_shash_setkey(tfm, key, key_len);
78
79 return tfm;
80 }
81
ieee80211_aes_cmac_key_free(struct crypto_shash * tfm)82 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
83 {
84 crypto_free_shash(tfm);
85 }
86