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Linux/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 <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-generic",
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");
160 MODULE_ALIAS_CRYPTO("crc32-generic");
161 

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