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, data: aad, AAD_LEN); |
36 | fc = (const __le16 *)aad; |
37 | if (ieee80211_is_beacon(fc: *fc)) { |
38 | /* mask Timestamp field to zero */ |
39 | crypto_shash_update(desc, data: zero, len: 8); |
40 | crypto_shash_update(desc, data: data + 8, len: data_len - 8 - CMAC_TLEN); |
41 | } else { |
42 | crypto_shash_update(desc, data, len: data_len - CMAC_TLEN); |
43 | } |
44 | crypto_shash_finup(desc, data: 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, data: aad, AAD_LEN); |
59 | fc = (const __le16 *)aad; |
60 | if (ieee80211_is_beacon(fc: *fc)) { |
61 | /* mask Timestamp field to zero */ |
62 | crypto_shash_update(desc, data: zero, len: 8); |
63 | crypto_shash_update(desc, data: data + 8, |
64 | len: data_len - 8 - CMAC_TLEN_256); |
65 | } else { |
66 | crypto_shash_update(desc, data, len: data_len - CMAC_TLEN_256); |
67 | } |
68 | crypto_shash_finup(desc, data: zero, CMAC_TLEN_256, out: 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(alg_name: "cmac(aes)" , type: 0, mask: 0); |
77 | if (!IS_ERR(ptr: tfm)) { |
78 | int err = crypto_shash_setkey(tfm, key, keylen: key_len); |
79 | |
80 | if (err) { |
81 | crypto_free_shash(tfm); |
82 | return ERR_PTR(error: 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 | |