// SPDX-License-Identifier: GPL-2.0-only
/*
 * AES-GMAC for IEEE 802.11 BIP-GMAC-128 and BIP-GMAC-256
 * Copyright 2015, Qualcomm Atheros, Inc.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/err.h>
#include <crypto/aead.h>
#include <crypto/aes.h>

#include <net/mac80211.h>
#include "key.h"
#include "aes_gmac.h"

int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
                       const u8 *data, size_t data_len, u8 *mic)
{
        struct scatterlist sg[5];
        u8 *zero, *__aad, iv[AES_BLOCK_SIZE];
        struct aead_request *aead_req;
        int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
        const __le16 *fc;
        int ret;

        if (data_len < IEEE80211_GMAC_MIC_LEN)
                return -EINVAL;

        aead_req = kzalloc(reqsize + IEEE80211_GMAC_MIC_LEN + GMAC_AAD_LEN,
                           GFP_ATOMIC);
        if (!aead_req)
                return -ENOMEM;

        zero = (u8 *)aead_req + reqsize;
        __aad = zero + IEEE80211_GMAC_MIC_LEN;
        memcpy(__aad, aad, GMAC_AAD_LEN);

        fc = (const __le16 *)aad;
        if (ieee80211_is_beacon(*fc)) {
                /* mask Timestamp field to zero */
                sg_init_table(sg, 5);
                sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
                sg_set_buf(&sg[1], zero, 8);
                sg_set_buf(&sg[2], data + 8,
                           data_len - 8 - IEEE80211_GMAC_MIC_LEN);
                sg_set_buf(&sg[3], zero, IEEE80211_GMAC_MIC_LEN);
                sg_set_buf(&sg[4], mic, IEEE80211_GMAC_MIC_LEN);
        } else {
                sg_init_table(sg, 4);
                sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
                sg_set_buf(&sg[1], data, data_len - IEEE80211_GMAC_MIC_LEN);
                sg_set_buf(&sg[2], zero, IEEE80211_GMAC_MIC_LEN);
                sg_set_buf(&sg[3], mic, IEEE80211_GMAC_MIC_LEN);
        }

        memcpy(iv, nonce, GMAC_NONCE_LEN);
        memset(iv + GMAC_NONCE_LEN, 0, sizeof(iv) - GMAC_NONCE_LEN);
        iv[AES_BLOCK_SIZE - 1] = 0x01;

        aead_request_set_tfm(aead_req, tfm);
        aead_request_set_crypt(aead_req, sg, sg, 0, iv);
        aead_request_set_ad(aead_req, GMAC_AAD_LEN + data_len);

        ret = crypto_aead_encrypt(aead_req);
        kfree_sensitive(aead_req);

        return ret;
}

struct crypto_aead *ieee80211_aes_gmac_key_setup(const u8 key[],
                                                 size_t key_len)
{
        struct crypto_aead *tfm;
        int err;

        tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm))
                return tfm;

        err = crypto_aead_setkey(tfm, key, key_len);
        if (!err)
                err = crypto_aead_setauthsize(tfm, IEEE80211_GMAC_MIC_LEN);
        if (!err)
                return tfm;

        crypto_free_aead(tfm);
        return ERR_PTR(err);
}

void ieee80211_aes_gmac_key_free(struct crypto_aead *tfm)
{
        crypto_free_aead(tfm);
}