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
22static const u8 zero[CMAC_TLEN_256];
23
24void 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
48void 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
70struct 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
82void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
83{
84	crypto_free_shash(tfm);
85}
86