aboutsummaryrefslogtreecommitdiffstats
path: root/net/mac80211/aes_cmac.c
blob: 9b9009f99551bb18b9613b4c470361d7fded4eb3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/*
 * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
 * Copyright 2008, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/export.h>
#include <linux/err.h>
#include <crypto/aes.h>

#include <net/mac80211.h>
#include "key.h"
#include "aes_cmac.h"

#define AES_CMAC_KEY_LEN 16
#define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
#define AAD_LEN 20


static void gf_mulx(u8 *pad)
{
	int i, carry;

	carry = pad[0] & 0x80;
	for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
		pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
	pad[AES_BLOCK_SIZE - 1] <<= 1;
	if (carry)
		pad[AES_BLOCK_SIZE - 1] ^= 0x87;
}


static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,
				const u8 *addr[], const size_t *len, u8 *mac)
{
	u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
	const u8 *pos, *end;
	size_t i, e, left, total_len;

	memset(cbc, 0, AES_BLOCK_SIZE);

	total_len = 0;
	for (e = 0; e < num_elem; e++)
		total_len += len[e];
	left = total_len;

	e = 0;
	pos = addr[0];
	end = pos + len[0];

	while (left >= AES_BLOCK_SIZE) {
		for (i = 0; i < AES_BLOCK_SIZE; i++) {
			cbc[i] ^= *pos++;
			if (pos >= end) {
				e++;
				pos = addr[e];
				end = pos + len[e];
			}
		}
		if (left > AES_BLOCK_SIZE)
			crypto_cipher_encrypt_one(tfm, cbc, cbc);
		left -= AES_BLOCK_SIZE;
	}

	memset(pad, 0, AES_BLOCK_SIZE);
	crypto_cipher_encrypt_one(tfm, pad, pad);
	gf_mulx(pad);

	if (left || total_len == 0) {
		for (i = 0; i < left; i++) {
			cbc[i] ^= *pos++;
			if (pos >= end) {
				e++;
				pos = addr[e];
				end = pos + len[e];
			}
		}
		cbc[left] ^= 0x80;
		gf_mulx(pad);
	}

	for (i = 0; i < AES_BLOCK_SIZE; i++)
		pad[i] ^= cbc[i];
	crypto_cipher_encrypt_one(tfm, pad, pad);
	memcpy(mac, pad, CMAC_TLEN);
}


void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
			const u8 *data, size_t data_len, u8 *mic)
{
	const u8 *addr[3];
	size_t len[3];
	u8 zero[CMAC_TLEN];

	memset(zero, 0, CMAC_TLEN);
	addr[0] = aad;
	len[0] = AAD_LEN;
	addr[1] = data;
	len[1] = data_len - CMAC_TLEN;
	addr[2] = zero;
	len[2] = CMAC_TLEN;

	aes_128_cmac_vector(tfm, 3, addr, len, mic);
}


struct crypto_cipher *ieee80211_aes_cmac_key_setup(const u8 key[])
{
	struct crypto_cipher *tfm;

	tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
	if (!IS_ERR(tfm))
		crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);

	return tfm;
}


void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
{
	crypto_free_cipher(tfm);
}

void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf,
					u8 *k1, u8 *k2)
{
	u8 l[AES_BLOCK_SIZE] = {};
	struct ieee80211_key *key =
		container_of(keyconf, struct ieee80211_key, conf);

	crypto_cipher_encrypt_one(key->u.aes_cmac.tfm, l, l);

	memcpy(k1, l, AES_BLOCK_SIZE);
	gf_mulx(k1);

	memcpy(k2, k1, AES_BLOCK_SIZE);
	gf_mulx(k2);
}
EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2);