// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2012 Xyratex Technology Limited
 */

/*
 * This is crypto api shash wrappers to crc32_le.
 */

#include <linux/unaligned.h>
#include <linux/crc32.h>
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/kernel.h>

#define CHKSUM_BLOCK_SIZE       1
#define CHKSUM_DIGEST_SIZE      4

/** No default init with ~0 */
static int crc32_cra_init(struct crypto_tfm *tfm)
{
        u32 *key = crypto_tfm_ctx(tfm);

        *key = 0;

        return 0;
}

/*
 * Setting the seed allows arbitrary accumulators and flexible XOR policy
 * If your algorithm starts with ~0, then XOR with ~0 before you set
 * the seed.
 */
static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
                        unsigned int keylen)
{
        u32 *mctx = crypto_shash_ctx(hash);

        if (keylen != sizeof(u32))
                return -EINVAL;
        *mctx = get_unaligned_le32(key);
        return 0;
}

static int crc32_init(struct shash_desc *desc)
{
        u32 *mctx = crypto_shash_ctx(desc->tfm);
        u32 *crcp = shash_desc_ctx(desc);

        *crcp = *mctx;

        return 0;
}

static int crc32_update(struct shash_desc *desc, const u8 *data,
                        unsigned int len)
{
        u32 *crcp = shash_desc_ctx(desc);

        *crcp = crc32_le(*crcp, data, len);
        return 0;
}

/* No final XOR 0xFFFFFFFF, like crc32_le */
static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
{
        put_unaligned_le32(crc32_le(*crcp, data, len), out);
        return 0;
}

static int crc32_finup(struct shash_desc *desc, const u8 *data,
                       unsigned int len, u8 *out)
{
        return __crc32_finup(shash_desc_ctx(desc), data, len, out);
}

static int crc32_final(struct shash_desc *desc, u8 *out)
{
        u32 *crcp = shash_desc_ctx(desc);

        put_unaligned_le32(*crcp, out);
        return 0;
}

static int crc32_digest(struct shash_desc *desc, const u8 *data,
                        unsigned int len, u8 *out)
{
        return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len, out);
}

static struct shash_alg alg = {
        .setkey                 = crc32_setkey,
        .init                   = crc32_init,
        .update                 = crc32_update,
        .final                  = crc32_final,
        .finup                  = crc32_finup,
        .digest                 = crc32_digest,
        .descsize               = sizeof(u32),
        .digestsize             = CHKSUM_DIGEST_SIZE,

        .base.cra_name          = "crc32",
        .base.cra_driver_name   = "crc32-lib",
        .base.cra_priority      = 100,
        .base.cra_flags         = CRYPTO_ALG_OPTIONAL_KEY,
        .base.cra_blocksize     = CHKSUM_BLOCK_SIZE,
        .base.cra_ctxsize       = sizeof(u32),
        .base.cra_module        = THIS_MODULE,
        .base.cra_init          = crc32_cra_init,
};

static int __init crc32_mod_init(void)
{
        return crypto_register_shash(&alg);
}

static void __exit crc32_mod_fini(void)
{
        crypto_unregister_shash(&alg);
}

module_init(crc32_mod_init);
module_exit(crc32_mod_fini);

MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("crc32");