1/*
2 * AES-GMAC for IEEE 802.11 BIP-GMAC-128 and BIP-GMAC-256
3 * Copyright 2015, Qualcomm Atheros, Inc.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/kernel.h>
11#include <linux/types.h>
12#include <linux/crypto.h>
13#include <linux/err.h>
14#include <crypto/aes.h>
15
16#include <net/mac80211.h>
17#include "key.h"
18#include "aes_gmac.h"
19
20#define GMAC_MIC_LEN 16
21#define GMAC_NONCE_LEN 12
22#define AAD_LEN 20
23
24int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
25		       const u8 *data, size_t data_len, u8 *mic)
26{
27	struct scatterlist sg[3], ct[1];
28	char aead_req_data[sizeof(struct aead_request) +
29			   crypto_aead_reqsize(tfm)]
30		__aligned(__alignof__(struct aead_request));
31	struct aead_request *aead_req = (void *)aead_req_data;
32	u8 zero[GMAC_MIC_LEN], iv[AES_BLOCK_SIZE];
33
34	if (data_len < GMAC_MIC_LEN)
35		return -EINVAL;
36
37	memset(aead_req, 0, sizeof(aead_req_data));
38
39	memset(zero, 0, GMAC_MIC_LEN);
40	sg_init_table(sg, 3);
41	sg_set_buf(&sg[0], aad, AAD_LEN);
42	sg_set_buf(&sg[1], data, data_len - GMAC_MIC_LEN);
43	sg_set_buf(&sg[2], zero, GMAC_MIC_LEN);
44
45	memcpy(iv, nonce, GMAC_NONCE_LEN);
46	memset(iv + GMAC_NONCE_LEN, 0, sizeof(iv) - GMAC_NONCE_LEN);
47	iv[AES_BLOCK_SIZE - 1] = 0x01;
48
49	sg_init_table(ct, 1);
50	sg_set_buf(&ct[0], mic, GMAC_MIC_LEN);
51
52	aead_request_set_tfm(aead_req, tfm);
53	aead_request_set_assoc(aead_req, sg, AAD_LEN + data_len);
54	aead_request_set_crypt(aead_req, NULL, ct, 0, iv);
55
56	crypto_aead_encrypt(aead_req);
57
58	return 0;
59}
60
61struct crypto_aead *ieee80211_aes_gmac_key_setup(const u8 key[],
62						 size_t key_len)
63{
64	struct crypto_aead *tfm;
65	int err;
66
67	tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
68	if (IS_ERR(tfm))
69		return tfm;
70
71	err = crypto_aead_setkey(tfm, key, key_len);
72	if (!err)
73		err = crypto_aead_setauthsize(tfm, GMAC_MIC_LEN);
74	if (!err)
75		return tfm;
76
77	crypto_free_aead(tfm);
78	return ERR_PTR(err);
79}
80
81void ieee80211_aes_gmac_key_free(struct crypto_aead *tfm)
82{
83	crypto_free_aead(tfm);
84}
85