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/*
* Cryptographic API.
*
* CRC32C chksum
*
* This module file is a wrapper to invoke the lib/crc32c routines.
*
* 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 <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/crc32c.h>
#include <linux/kernel.h>
#define CHKSUM_BLOCK_SIZE 32
#define CHKSUM_DIGEST_SIZE 4
struct chksum_ctx {
u32 crc;
u32 key;
};
/*
* Steps through buffer one byte at at time, calculates reflected
* crc using table.
*/
static void chksum_init(struct crypto_tfm *tfm)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->crc = mctx->key;
}
/*
* 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 chksum_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
if (keylen != sizeof(mctx->crc)) {
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
mctx->key = le32_to_cpu(*(__le32 *)key);
return 0;
}
static void chksum_update(struct crypto_tfm *tfm, const u8 *data,
unsigned int length)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->crc = crc32c(mctx->crc, data, length);
}
static void chksum_final(struct crypto_tfm *tfm, u8 *out)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
*(__le32 *)out = ~cpu_to_le32(mctx->crc);
}
static int crc32c_cra_init(struct crypto_tfm *tfm)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->key = ~0;
return 0;
}
static struct crypto_alg alg = {
.cra_name = "crc32c",
.cra_flags = CRYPTO_ALG_TYPE_DIGEST,
.cra_blocksize = CHKSUM_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct chksum_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(alg.cra_list),
.cra_init = crc32c_cra_init,
.cra_u = {
.digest = {
.dia_digestsize= CHKSUM_DIGEST_SIZE,
.dia_setkey = chksum_setkey,
.dia_init = chksum_init,
.dia_update = chksum_update,
.dia_final = chksum_final
}
}
};
static int __init crc32c_mod_init(void)
{
return crypto_register_alg(&alg);
}
static void __exit crc32c_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(crc32c_mod_init);
module_exit(crc32c_mod_fini);
MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
MODULE_LICENSE("GPL");
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