linux/net/mac80211/aes_cmac.c
Jouni Malinen 2d5d4b0a6d mac80211: Update BIP to support Beacon frames
When BIP is used to protect Beacon frames, the Timestamp field is masked
to zero. Otherwise, the BIP processing is identical to the way it was
already used with group-addressed Robust Management frames.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Link: https://lore.kernel.org/r/20200222132548.20835-4-jouni@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2020-02-24 10:36:03 +01:00

86 lines
2.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
* Copyright 2008, Jouni Malinen <j@w1.fi>
*/
#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 CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
#define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
#define AAD_LEN 20
static const u8 zero[CMAC_TLEN_256];
void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic)
{
SHASH_DESC_ON_STACK(desc, tfm);
u8 out[AES_BLOCK_SIZE];
const __le16 *fc;
desc->tfm = tfm;
crypto_shash_init(desc);
crypto_shash_update(desc, aad, AAD_LEN);
fc = (const __le16 *)aad;
if (ieee80211_is_beacon(*fc)) {
/* mask Timestamp field to zero */
crypto_shash_update(desc, zero, 8);
crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN);
} else {
crypto_shash_update(desc, data, data_len - CMAC_TLEN);
}
crypto_shash_finup(desc, zero, CMAC_TLEN, out);
memcpy(mic, out, CMAC_TLEN);
}
void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic)
{
SHASH_DESC_ON_STACK(desc, tfm);
const __le16 *fc;
desc->tfm = tfm;
crypto_shash_init(desc);
crypto_shash_update(desc, aad, AAD_LEN);
fc = (const __le16 *)aad;
if (ieee80211_is_beacon(*fc)) {
/* mask Timestamp field to zero */
crypto_shash_update(desc, zero, 8);
crypto_shash_update(desc, data + 8,
data_len - 8 - CMAC_TLEN_256);
} else {
crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
}
crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
}
struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
size_t key_len)
{
struct crypto_shash *tfm;
tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
if (!IS_ERR(tfm))
crypto_shash_setkey(tfm, key, key_len);
return tfm;
}
void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
{
crypto_free_shash(tfm);
}