// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Cryptographic API
 *
 * ARC4 Cipher Algorithm
 *
 * Jon Oberheide <jon@oberheide.org>
 */

#include <crypto/arc4.h>
#include <crypto/internal/skcipher.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>

#define ARC4_ALIGN __alignof__(struct arc4_ctx)

static int crypto_arc4_setkey(struct crypto_lskcipher *tfm, const u8 *in_key,
                              unsigned int key_len)
{
        struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);

        return arc4_setkey(ctx, in_key, key_len);
}

static int crypto_arc4_crypt(struct crypto_lskcipher *tfm, const u8 *src,
                             u8 *dst, unsigned nbytes, u8 *siv, u32 flags)
{
        struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);

        if (!(flags & CRYPTO_LSKCIPHER_FLAG_CONT))
                memcpy(siv, ctx, sizeof(*ctx));

        ctx = (struct arc4_ctx *)siv;

        arc4_crypt(ctx, dst, src, nbytes);
        return 0;
}

static int crypto_arc4_init(struct crypto_lskcipher *tfm)
{
        pr_warn_ratelimited("\"%s\" (%ld) uses obsolete ecb(arc4) skcipher\n",
                            current->comm, (unsigned long)current->pid);

        return 0;
}

static struct lskcipher_alg arc4_alg = {
        .co.base.cra_name               =       "arc4",
        .co.base.cra_driver_name        =       "arc4-generic",
        .co.base.cra_priority           =       100,
        .co.base.cra_blocksize          =       ARC4_BLOCK_SIZE,
        .co.base.cra_ctxsize            =       sizeof(struct arc4_ctx),
        .co.base.cra_alignmask          =       ARC4_ALIGN - 1,
        .co.base.cra_module             =       THIS_MODULE,
        .co.min_keysize                 =       ARC4_MIN_KEY_SIZE,
        .co.max_keysize                 =       ARC4_MAX_KEY_SIZE,
        .co.statesize                   =       sizeof(struct arc4_ctx),
        .setkey                         =       crypto_arc4_setkey,
        .encrypt                        =       crypto_arc4_crypt,
        .decrypt                        =       crypto_arc4_crypt,
        .init                           =       crypto_arc4_init,
};

static int __init arc4_init(void)
{
        return crypto_register_lskcipher(&arc4_alg);
}

static void __exit arc4_exit(void)
{
        crypto_unregister_lskcipher(&arc4_alg);
}

module_init(arc4_init);
module_exit(arc4_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
MODULE_ALIAS_CRYPTO("ecb(arc4)");