linux/crypto/crc32c.c
Herbert Xu 5773a3e6e3 crypto: crc32c - Add ahash implementation
This patch reimplements crc32c using the ahash interface.  This
allows one tfm to be used by an unlimited number of users provided
that they all use the same key (which all current crc32c users do).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-07-10 20:35:18 +08:00

231 lines
5.1 KiB
C

/*
* Cryptographic API.
*
* CRC32C chksum
*
* This module file is a wrapper to invoke the lib/crc32c routines.
*
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.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 <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crc32c.h>
#include <linux/kernel.h>
#define CHKSUM_BLOCK_SIZE 1
#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_old(struct crypto_tfm *tfm)
{
struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->key = ~0;
return 0;
}
static struct crypto_alg old_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(old_alg.cra_list),
.cra_init = crc32c_cra_init_old,
.cra_u = {
.digest = {
.dia_digestsize= CHKSUM_DIGEST_SIZE,
.dia_setkey = chksum_setkey,
.dia_init = chksum_init,
.dia_update = chksum_update,
.dia_final = chksum_final
}
}
};
/*
* 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 crc32c_setkey(struct crypto_ahash *hash, const u8 *key,
unsigned int keylen)
{
u32 *mctx = crypto_ahash_ctx(hash);
if (keylen != sizeof(u32)) {
crypto_ahash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
*mctx = le32_to_cpup((__le32 *)key);
return 0;
}
static int crc32c_init(struct ahash_request *req)
{
u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
u32 *crcp = ahash_request_ctx(req);
*crcp = *mctx;
return 0;
}
static int crc32c_update(struct ahash_request *req)
{
struct crypto_hash_walk walk;
u32 *crcp = ahash_request_ctx(req);
u32 crc = *crcp;
int nbytes;
for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
nbytes = crypto_hash_walk_done(&walk, 0))
crc = crc32c(crc, walk.data, nbytes);
*crcp = crc;
return 0;
}
static int crc32c_final(struct ahash_request *req)
{
u32 *crcp = ahash_request_ctx(req);
*(__le32 *)req->result = ~cpu_to_le32p(crcp);
return 0;
}
static int crc32c_digest(struct ahash_request *req)
{
struct crypto_hash_walk walk;
u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
u32 crc = *mctx;
int nbytes;
for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
nbytes = crypto_hash_walk_done(&walk, 0))
crc = crc32c(crc, walk.data, nbytes);
*(__le32 *)req->result = ~cpu_to_le32(crc);
return 0;
}
static int crc32c_cra_init(struct crypto_tfm *tfm)
{
u32 *key = crypto_tfm_ctx(tfm);
*key = ~0;
tfm->crt_ahash.reqsize = sizeof(u32);
return 0;
}
static struct crypto_alg alg = {
.cra_name = "crc32c",
.cra_driver_name = "crc32c-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_AHASH,
.cra_blocksize = CHKSUM_BLOCK_SIZE,
.cra_alignmask = 3,
.cra_ctxsize = sizeof(u32),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(alg.cra_list),
.cra_init = crc32c_cra_init,
.cra_type = &crypto_ahash_type,
.cra_u = {
.ahash = {
.digestsize = CHKSUM_DIGEST_SIZE,
.setkey = crc32c_setkey,
.init = crc32c_init,
.update = crc32c_update,
.final = crc32c_final,
.digest = crc32c_digest,
}
}
};
static int __init crc32c_mod_init(void)
{
int err;
err = crypto_register_alg(&old_alg);
if (err)
return err;
err = crypto_register_alg(&alg);
if (err)
crypto_unregister_alg(&old_alg);
return err;
}
static void __exit crc32c_mod_fini(void)
{
crypto_unregister_alg(&alg);
crypto_unregister_alg(&old_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");