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/*
* Cryptographic API.
*
* Null algorithms, aka Much Ado About Nothing.
*
* These are needed for IPsec, and may be useful in general for
* testing & debugging.
*
* The null cipher is compliant with RFC2410.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/

#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/string.h>

#define NULL_KEY_SIZE 0
#define NULL_BLOCK_SIZE 1
#define NULL_DIGEST_SIZE 0
#define NULL_IV_SIZE 0

static int null_compress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
if (slen > *dlen)
return -EINVAL;
memcpy(dst, src, slen);
*dlen = slen;
return 0;
}

static int null_init(struct shash_desc *desc)
{
return 0;
}

static int null_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
return 0;
}

static int null_final(struct shash_desc *desc, u8 *out)
{
return 0;
}

static int null_digest(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return 0;
}

static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{ return 0; }

static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{ return 0; }

static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
memcpy(dst, src, NULL_BLOCK_SIZE);
}

static int skcipher_null_crypt(struct blkcipher_desc *desc,
struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct blkcipher_walk walk;
int err;

blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt(desc, &walk);

while (walk.nbytes) {
if (walk.src.virt.addr != walk.dst.virt.addr)
memcpy(walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes);
err = blkcipher_walk_done(desc, &walk, 0);
}

return err;
}

static struct shash_alg digest_null = {
.digestsize = NULL_DIGEST_SIZE,
.setkey = null_hash_setkey,
.init = null_init,
.update = null_update,
.finup = null_digest,
.digest = null_digest,
.final = null_final,
.base = {
.cra_name = "digest_null",
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = NULL_BLOCK_SIZE,
.cra_module = THIS_MODULE,
}
};

static struct crypto_alg null_algs[3] = { {
.cra_name = "cipher_null",
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = NULL_BLOCK_SIZE,
.cra_ctxsize = 0,
.cra_module = THIS_MODULE,
.cra_u = { .cipher = {
.cia_min_keysize = NULL_KEY_SIZE,
.cia_max_keysize = NULL_KEY_SIZE,
.cia_setkey = null_setkey,
.cia_encrypt = null_crypt,
.cia_decrypt = null_crypt } }
}, {
.cra_name = "ecb(cipher_null)",
.cra_driver_name = "ecb-cipher_null",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = NULL_BLOCK_SIZE,
.cra_type = &crypto_blkcipher_type,
.cra_ctxsize = 0,
.cra_module = THIS_MODULE,
.cra_u = { .blkcipher = {
.min_keysize = NULL_KEY_SIZE,
.max_keysize = NULL_KEY_SIZE,
.ivsize = NULL_IV_SIZE,
.setkey = null_setkey,
.encrypt = skcipher_null_crypt,
.decrypt = skcipher_null_crypt } }
}, {
.cra_name = "compress_null",
.cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
.cra_blocksize = NULL_BLOCK_SIZE,
.cra_ctxsize = 0,
.cra_module = THIS_MODULE,
.cra_u = { .compress = {
.coa_compress = null_compress,
.coa_decompress = null_compress } }
} };

MODULE_ALIAS("compress_null");
MODULE_ALIAS("digest_null");
MODULE_ALIAS("cipher_null");

static int __init crypto_null_mod_init(void)
{
int ret = 0;

ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
if (ret < 0)
goto out;

ret = crypto_register_shash(&digest_null);
if (ret < 0)
goto out_unregister_algs;

return 0;

out_unregister_algs:
crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
out:
return ret;
}

static void __exit crypto_null_mod_fini(void)
{
crypto_unregister_shash(&digest_null);
crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
}

module_init(crypto_null_mod_init);
module_exit(crypto_null_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Null Cryptographic Algorithms");
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