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