linux/crypto/crc32_generic.c
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   1/* GPL HEADER START
   2 *
   3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 only,
   7 * as published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it will be useful, but
  10 * WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 * General Public License version 2 for more details (a copy is included
  13 * in the LICENSE file that accompanied this code).
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * version 2 along with this program; If not, see http://www.gnu.org/licenses
  17 *
  18 * Please  visit http://www.xyratex.com/contact if you need additional
  19 * information or have any questions.
  20 *
  21 * GPL HEADER END
  22 */
  23
  24/*
  25 * Copyright 2012 Xyratex Technology Limited
  26 */
  27
  28/*
  29 * This is crypto api shash wrappers to crc32_le.
  30 */
  31
  32#include <asm/unaligned.h>
  33#include <linux/crc32.h>
  34#include <crypto/internal/hash.h>
  35#include <linux/init.h>
  36#include <linux/module.h>
  37#include <linux/string.h>
  38#include <linux/kernel.h>
  39
  40#define CHKSUM_BLOCK_SIZE       1
  41#define CHKSUM_DIGEST_SIZE      4
  42
  43/** No default init with ~0 */
  44static int crc32_cra_init(struct crypto_tfm *tfm)
  45{
  46        u32 *key = crypto_tfm_ctx(tfm);
  47
  48        *key = 0;
  49
  50        return 0;
  51}
  52
  53/*
  54 * Setting the seed allows arbitrary accumulators and flexible XOR policy
  55 * If your algorithm starts with ~0, then XOR with ~0 before you set
  56 * the seed.
  57 */
  58static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
  59                        unsigned int keylen)
  60{
  61        u32 *mctx = crypto_shash_ctx(hash);
  62
  63        if (keylen != sizeof(u32)) {
  64                crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
  65                return -EINVAL;
  66        }
  67        *mctx = get_unaligned_le32(key);
  68        return 0;
  69}
  70
  71static int crc32_init(struct shash_desc *desc)
  72{
  73        u32 *mctx = crypto_shash_ctx(desc->tfm);
  74        u32 *crcp = shash_desc_ctx(desc);
  75
  76        *crcp = *mctx;
  77
  78        return 0;
  79}
  80
  81static int crc32_update(struct shash_desc *desc, const u8 *data,
  82                        unsigned int len)
  83{
  84        u32 *crcp = shash_desc_ctx(desc);
  85
  86        *crcp = crc32_le(*crcp, data, len);
  87        return 0;
  88}
  89
  90/* No final XOR 0xFFFFFFFF, like crc32_le */
  91static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
  92                         u8 *out)
  93{
  94        put_unaligned_le32(crc32_le(*crcp, data, len), out);
  95        return 0;
  96}
  97
  98static int crc32_finup(struct shash_desc *desc, const u8 *data,
  99                       unsigned int len, u8 *out)
 100{
 101        return __crc32_finup(shash_desc_ctx(desc), data, len, out);
 102}
 103
 104static int crc32_final(struct shash_desc *desc, u8 *out)
 105{
 106        u32 *crcp = shash_desc_ctx(desc);
 107
 108        put_unaligned_le32(*crcp, out);
 109        return 0;
 110}
 111
 112static int crc32_digest(struct shash_desc *desc, const u8 *data,
 113                        unsigned int len, u8 *out)
 114{
 115        return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
 116                             out);
 117}
 118static struct shash_alg alg = {
 119        .setkey         = crc32_setkey,
 120        .init           = crc32_init,
 121        .update         = crc32_update,
 122        .final          = crc32_final,
 123        .finup          = crc32_finup,
 124        .digest         = crc32_digest,
 125        .descsize       = sizeof(u32),
 126        .digestsize     = CHKSUM_DIGEST_SIZE,
 127        .base           = {
 128                .cra_name               = "crc32",
 129                .cra_driver_name        = "crc32-generic",
 130                .cra_priority           = 100,
 131                .cra_flags              = CRYPTO_ALG_OPTIONAL_KEY,
 132                .cra_blocksize          = CHKSUM_BLOCK_SIZE,
 133                .cra_ctxsize            = sizeof(u32),
 134                .cra_module             = THIS_MODULE,
 135                .cra_init               = crc32_cra_init,
 136        }
 137};
 138
 139static int __init crc32_mod_init(void)
 140{
 141        return crypto_register_shash(&alg);
 142}
 143
 144static void __exit crc32_mod_fini(void)
 145{
 146        crypto_unregister_shash(&alg);
 147}
 148
 149subsys_initcall(crc32_mod_init);
 150module_exit(crc32_mod_fini);
 151
 152MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 153MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 154MODULE_LICENSE("GPL");
 155MODULE_ALIAS_CRYPTO("crc32");
 156MODULE_ALIAS_CRYPTO("crc32-generic");
 157