xref: /openbmc/linux/net/mac80211/aes_gmac.c (revision d7a3d85e)
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 
24 int 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 
61 struct 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 
81 void ieee80211_aes_gmac_key_free(struct crypto_aead *tfm)
82 {
83 	crypto_free_aead(tfm);
84 }
85