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
 42static 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 */
 48static 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 */
 63static 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
 76static 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
 86static 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 */
 96static 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
103static 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
109static 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
117static 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}
123static 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
143static int __init crc32_mod_init(void)
144{
145	return crypto_register_shash(&alg);
146}
147
148static void __exit crc32_mod_fini(void)
149{
150	crypto_unregister_shash(&alg);
151}
152
153module_init(crc32_mod_init);
154module_exit(crc32_mod_fini);
155
156MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
157MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
158MODULE_LICENSE("GPL");
159MODULE_ALIAS_CRYPTO("crc32");
160MODULE_ALIAS_CRYPTO("crc32-generic");