crypto/crc32_generic.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 <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 */
  44 static 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  */
  58 static 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
  71 static 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
  81 static 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 */
  91 static 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
  98 static 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
 104 static 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
 112 static 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 }
 118 static 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
 139 static int __init crc32_mod_init(void)
 140 {
 141         return crypto_register_shash(&alg);
 142 }
 143
 144 static void __exit crc32_mod_fini(void)
 145 {
 146         crypto_unregister_shash(&alg);
 147 }
 148
 149 module_init(crc32_mod_init);
 150 module_exit(crc32_mod_fini);
 151
 152 MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
 153 MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
 154 MODULE_LICENSE("GPL");
 155 MODULE_ALIAS_CRYPTO("crc32");
 156 MODULE_ALIAS_CRYPTO("crc32-generic");