aes_gmac.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * AES-GMAC for IEEE 802.11 BIP-GMAC-128 and BIP-GMAC-256
 4 * Copyright 2015, Qualcomm Atheros, Inc.
 5 */
 6
 7#include <linux/kernel.h>
 8#include <linux/types.h>
 9#include <linux/err.h>
10#include <crypto/aead.h>
11#include <crypto/aes.h>
12
13#include <net/mac80211.h>
14#include "key.h"
15#include "aes_gmac.h"
16
17int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
18		       const u8 *data, size_t data_len, u8 *mic)
19{
20	struct scatterlist sg[5];
21	u8 *zero, *__aad, iv[AES_BLOCK_SIZE];
22	struct aead_request *aead_req;
23	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
24	const __le16 *fc;
25	int ret;
26
27	if (data_len < IEEE80211_GMAC_MIC_LEN)
28		return -EINVAL;
29
30	aead_req = kzalloc(reqsize + IEEE80211_GMAC_MIC_LEN + GMAC_AAD_LEN,
31			   GFP_ATOMIC);
32	if (!aead_req)
33		return -ENOMEM;
34
35	zero = (u8 *)aead_req + reqsize;
36	__aad = zero + IEEE80211_GMAC_MIC_LEN;
37	memcpy(__aad, aad, GMAC_AAD_LEN);
38
39	fc = (const __le16 *)aad;
40	if (ieee80211_is_beacon(*fc)) {
41		/* mask Timestamp field to zero */
42		sg_init_table(sg, 5);
43		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
44		sg_set_buf(&sg[1], zero, 8);
45		sg_set_buf(&sg[2], data + 8,
46			   data_len - 8 - IEEE80211_GMAC_MIC_LEN);
47		sg_set_buf(&sg[3], zero, IEEE80211_GMAC_MIC_LEN);
48		sg_set_buf(&sg[4], mic, IEEE80211_GMAC_MIC_LEN);
49	} else {
50		sg_init_table(sg, 4);
51		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
52		sg_set_buf(&sg[1], data, data_len - IEEE80211_GMAC_MIC_LEN);
53		sg_set_buf(&sg[2], zero, IEEE80211_GMAC_MIC_LEN);
54		sg_set_buf(&sg[3], mic, IEEE80211_GMAC_MIC_LEN);
55	}
56
57	memcpy(iv, nonce, GMAC_NONCE_LEN);
58	memset(iv + GMAC_NONCE_LEN, 0, sizeof(iv) - GMAC_NONCE_LEN);
59	iv[AES_BLOCK_SIZE - 1] = 0x01;
60
61	aead_request_set_tfm(aead_req, tfm);
62	aead_request_set_crypt(aead_req, sg, sg, 0, iv);
63	aead_request_set_ad(aead_req, GMAC_AAD_LEN + data_len);
64
65	ret = crypto_aead_encrypt(aead_req);
66	kfree_sensitive(aead_req);
67
68	return ret;
69}
70
71struct crypto_aead *ieee80211_aes_gmac_key_setup(const u8 key[],
72						 size_t key_len)
73{
74	struct crypto_aead *tfm;
75	int err;
76
77	tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
78	if (IS_ERR(tfm))
79		return tfm;
80
81	err = crypto_aead_setkey(tfm, key, key_len);
82	if (!err)
83		err = crypto_aead_setauthsize(tfm, IEEE80211_GMAC_MIC_LEN);
84	if (!err)
85		return tfm;
86
87	crypto_free_aead(tfm);
88	return ERR_PTR(err);
89}
90
91void ieee80211_aes_gmac_key_free(struct crypto_aead *tfm)
92{
93	crypto_free_aead(tfm);
94}