linux/crypto/crc32.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 <linux/crc32.h>
  33#include <crypto/internal/hash.h>
  34#include <linux/init.h>
  35#include <linux/module.h>
  36#include <linux/string.h>
  37#include <linux/kernel.h>
  38
  39#define CHKSUM_BLOCK_SIZE       1
  40#define CHKSUM_DIGEST_SIZE      4
  41
  42static u32 __crc32_le(u32 crc, unsigned char const *p, size_t len)
  43{
  44        return crc32_le(crc, p, len);
  45}
  46
  47/** No default init with ~0 */
  48static int crc32_cra_init(struct crypto_tfm *tfm)
  49{
  50        u32 *key = crypto_tfm_ctx(tfm);
  51
  52        *key = 0;
  53
  54        return 0;
  55}
  56
  57
  58/*
  59 * Setting the seed allows arbitrary accumulators and flexible XOR policy
  60 * If your algorithm starts with ~0, then XOR with ~0 before you set
  61 * the seed.
  62 */
  63static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
  64                        unsigned int keylen)
  65{
  66        u32 *mctx = crypto_shash_ctx(hash);
  67
  68        if (keylen != sizeof(u32)) {
  69                crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
  70                return -EINVAL;
  71        }
  72        *mctx = le32_to_cpup((__le32 *)key);
  73        return 0;
  74}
  75
  76static int crc32_init(struct shash_desc *desc)
  77{
  78        u32 *mctx = crypto_shash_ctx(desc->tfm);
  79        u32 *crcp = shash_desc_ctx(desc);
  80
  81        *crcp = *mctx;
  82
  83        return 0;
  84}
  85
  86static int crc32_update(struct shash_desc *desc, const u8 *data,
  87                        unsigned int len)
  88{
  89        u32 *crcp = shash_desc_ctx(desc);
  90
  91        *crcp = __crc32_le(*crcp, data, len);
  92        return 0;
  93}
  94
  95/* No final XOR 0xFFFFFFFF, like crc32_le */
  96static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
  97                         u8 *out)
  98{
  99        *(__le32 *)out = cpu_to_le32(__crc32_le(*crcp, data, len));
 100        return 0;
 101}
 102
 103static int crc32_finup(struct shash_desc *desc, const u8 *data,
 104                       unsigned int len, u8 *out)
 105{
 106        return __crc32_finup(shash_desc_ctx(desc), data, len, out);
 107}
 108
 109static int crc32_final(struct shash_desc *desc, u8 *out)
 110{
 111        u32 *crcp = shash_desc_ctx(desc);
 112
 113        *(__le32 *)out = cpu_to_le32p(crcp);
 114        return 0;
 115}
 116
 117static int crc32_digest(struct shash_desc *desc, const u8 *data,
 118                        unsigned int len, u8 *out)
 119{
 120        return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
 121                             out);
 122}
 123static struct shash_alg alg = {
 124        .setkey         = crc32_setkey,
 125        .init           = crc32_init,
 126        .update         = crc32_update,
 127        .final          = crc32_final,
 128        .finup          = crc32_finup,
 129        .digest         = crc32_digest,
 130        .descsize       = sizeof(u32),
 131        .digestsize     = CHKSUM_DIGEST_SIZE,
 132        .base           = {
 133                .cra_name               = "crc32",
 134                .cra_driver_name        = "crc32-table",
 135                .cra_priority           = 100,
 136                .cra_blocksize          = CHKSUM_BLOCK_SIZE,
 137                .cra_ctxsize            = sizeof(u32),
 138                .cra_module             = THIS_MODULE,
 139                .cra_init               = crc32_cra_init,
 140        }
 141};
 142
 143static int __init crc32_mod_init(void)
 144{
 145        return crypto_register_shash(&alg);
 146}
 147
 148static void __exit crc32_mod_fini(void)
 149{
 150        crypto_unregister_shash(&alg);
 151}
 152
 153module_init(crc32_mod_init);
 154module_exit(crc32_mod_fini);
 155
 156MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 157MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 158MODULE_LICENSE("GPL");
 159
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