linux/crypto/crc32_generic.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright 2012 Xyratex Technology Limited
   4 */
   5
   6/*
   7 * This is crypto api shash wrappers to crc32_le.
   8 */
   9
  10#include <asm/unaligned.h>
  11#include <linux/crc32.h>
  12#include <crypto/internal/hash.h>
  13#include <linux/init.h>
  14#include <linux/module.h>
  15#include <linux/string.h>
  16#include <linux/kernel.h>
  17
  18#define CHKSUM_BLOCK_SIZE       1
  19#define CHKSUM_DIGEST_SIZE      4
  20
  21/** No default init with ~0 */
  22static int crc32_cra_init(struct crypto_tfm *tfm)
  23{
  24        u32 *key = crypto_tfm_ctx(tfm);
  25
  26        *key = 0;
  27
  28        return 0;
  29}
  30
  31/*
  32 * Setting the seed allows arbitrary accumulators and flexible XOR policy
  33 * If your algorithm starts with ~0, then XOR with ~0 before you set
  34 * the seed.
  35 */
  36static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
  37                        unsigned int keylen)
  38{
  39        u32 *mctx = crypto_shash_ctx(hash);
  40
  41        if (keylen != sizeof(u32))
  42                return -EINVAL;
  43        *mctx = get_unaligned_le32(key);
  44        return 0;
  45}
  46
  47static int crc32_init(struct shash_desc *desc)
  48{
  49        u32 *mctx = crypto_shash_ctx(desc->tfm);
  50        u32 *crcp = shash_desc_ctx(desc);
  51
  52        *crcp = *mctx;
  53
  54        return 0;
  55}
  56
  57static int crc32_update(struct shash_desc *desc, const u8 *data,
  58                        unsigned int len)
  59{
  60        u32 *crcp = shash_desc_ctx(desc);
  61
  62        *crcp = crc32_le(*crcp, data, len);
  63        return 0;
  64}
  65
  66/* No final XOR 0xFFFFFFFF, like crc32_le */
  67static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
  68                         u8 *out)
  69{
  70        put_unaligned_le32(crc32_le(*crcp, data, len), out);
  71        return 0;
  72}
  73
  74static int crc32_finup(struct shash_desc *desc, const u8 *data,
  75                       unsigned int len, u8 *out)
  76{
  77        return __crc32_finup(shash_desc_ctx(desc), data, len, out);
  78}
  79
  80static int crc32_final(struct shash_desc *desc, u8 *out)
  81{
  82        u32 *crcp = shash_desc_ctx(desc);
  83
  84        put_unaligned_le32(*crcp, out);
  85        return 0;
  86}
  87
  88static int crc32_digest(struct shash_desc *desc, const u8 *data,
  89                        unsigned int len, u8 *out)
  90{
  91        return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
  92                             out);
  93}
  94static struct shash_alg alg = {
  95        .setkey         = crc32_setkey,
  96        .init           = crc32_init,
  97        .update         = crc32_update,
  98        .final          = crc32_final,
  99        .finup          = crc32_finup,
 100        .digest         = crc32_digest,
 101        .descsize       = sizeof(u32),
 102        .digestsize     = CHKSUM_DIGEST_SIZE,
 103        .base           = {
 104                .cra_name               = "crc32",
 105                .cra_driver_name        = "crc32-generic",
 106                .cra_priority           = 100,
 107                .cra_flags              = CRYPTO_ALG_OPTIONAL_KEY,
 108                .cra_blocksize          = CHKSUM_BLOCK_SIZE,
 109                .cra_ctxsize            = sizeof(u32),
 110                .cra_module             = THIS_MODULE,
 111                .cra_init               = crc32_cra_init,
 112        }
 113};
 114
 115static int __init crc32_mod_init(void)
 116{
 117        return crypto_register_shash(&alg);
 118}
 119
 120static void __exit crc32_mod_fini(void)
 121{
 122        crypto_unregister_shash(&alg);
 123}
 124
 125subsys_initcall(crc32_mod_init);
 126module_exit(crc32_mod_fini);
 127
 128MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 129MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 130MODULE_LICENSE("GPL");
 131MODULE_ALIAS_CRYPTO("crc32");
 132MODULE_ALIAS_CRYPTO("crc32-generic");
 133
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