crypto/crc32.c

   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
  42 static 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 */
  48 static 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  */
  63 static 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
  76 static 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
  86 static 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 */
  96 static 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
 103 static 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
 109 static 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
 117 static 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 }
 123 static 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
 143 static int __init crc32_mod_init(void)
 144 {
 145         return crypto_register_shash(&alg);
 146 }
 147
 148 static void __exit crc32_mod_fini(void)
 149 {
 150         crypto_unregister_shash(&alg);
 151 }
 152
 153 module_init(crc32_mod_init);
 154 module_exit(crc32_mod_fini);
 155
 156 MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 157 MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 158 MODULE_LICENSE("GPL");
 159 MODULE_ALIAS_CRYPTO("crc32");