// 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>
 * Copyright (C) 2020 Intel Corporation
 */

#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 AAD_LEN 20

static const u8 zero[IEEE80211_CMAC_256_MIC_LEN];

int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
                       const u8 *data, size_t data_len, u8 *mic,
                       unsigned int mic_len)
{
        int err;
        SHASH_DESC_ON_STACK(desc, tfm);
        u8 out[AES_BLOCK_SIZE];
        const __le16 *fc;

        desc->tfm = tfm;

        err = crypto_shash_init(desc);
        if (err)
                return err;
        err = crypto_shash_update(desc, aad, AAD_LEN);
        if (err)
                return err;
        fc = (const __le16 *)aad;
        if (ieee80211_is_beacon(*fc)) {
                /* mask Timestamp field to zero */
                err = crypto_shash_update(desc, zero, 8);
                if (err)
                        return err;
                err = crypto_shash_update(desc, data + 8,
                                          data_len - 8 - mic_len);
                if (err)
                        return err;
        } else {
                err = crypto_shash_update(desc, data, data_len - mic_len);
                if (err)
                        return err;
        }
        err = crypto_shash_finup(desc, zero, mic_len, out);
        if (err)
                return err;
        memcpy(mic, out, mic_len);

        return 0;
}

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)) {
                int err = crypto_shash_setkey(tfm, key, key_len);

                if (err) {
                        crypto_free_shash(tfm);
                        return ERR_PTR(err);
                }
        }

        return tfm;
}

void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
{
        crypto_free_shash(tfm);
}