crypto/crc32_generic.c

   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 */
  22 static 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  */
  36 static 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
  47 static 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
  57 static 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 */
  67 static 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
  74 static 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
  80 static 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
  88 static 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 }
  94 static 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
 115 static int __init crc32_mod_init(void)
 116 {
 117         return crypto_register_shash(&alg);
 118 }
 119
 120 static void __exit crc32_mod_fini(void)
 121 {
 122         crypto_unregister_shash(&alg);
 123 }
 124
 125 subsys_initcall(crc32_mod_init);
 126 module_exit(crc32_mod_fini);
 127
 128 MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 129 MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 130 MODULE_LICENSE("GPL");
 131 MODULE_ALIAS_CRYPTO("crc32");
 132 MODULE_ALIAS_CRYPTO("crc32-generic");