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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Cryptographic API.4 *5 * CRC32C chksum6 *7 *@Article{castagnoli-crc,8 * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},9 * title = {{Optimization of Cyclic Redundancy-Check Codes with 2410 * and 32 Parity Bits}},11 * journal = IEEE Transactions on Communication,12 * year = {1993},13 * volume = {41},14 * number = {6},15 * pages = {},16 * month = {June},17 *}18 * Used by the iSCSI driver, possibly others, and derived from19 * the iscsi-crc.c module of the linux-iscsi driver at20 * http://linux-iscsi.sourceforge.net.21 *22 * Following the example of lib/crc32, this function is intended to be23 * flexible and useful for all users. Modules that currently have their24 * own crc32c, but hopefully may be able to use this one are:25 * net/sctp (please add all your doco to here if you change to26 * use this one!)27 * <endoflist>28 *29 * Copyright (c) 2004 Cisco Systems, Inc.30 * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>31 */32 33#include <linux/unaligned.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#include <linux/crc32.h>40 41#define CHKSUM_BLOCK_SIZE 142#define CHKSUM_DIGEST_SIZE 443 44struct chksum_ctx {45 u32 key;46};47 48struct chksum_desc_ctx {49 u32 crc;50};51 52/*53 * Steps through buffer one byte at a time, calculates reflected54 * crc using table.55 */56 57static int chksum_init(struct shash_desc *desc)58{59 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);60 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);61 62 ctx->crc = mctx->key;63 64 return 0;65}66 67/*68 * Setting the seed allows arbitrary accumulators and flexible XOR policy69 * If your algorithm starts with ~0, then XOR with ~0 before you set70 * the seed.71 */72static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,73 unsigned int keylen)74{75 struct chksum_ctx *mctx = crypto_shash_ctx(tfm);76 77 if (keylen != sizeof(mctx->key))78 return -EINVAL;79 mctx->key = get_unaligned_le32(key);80 return 0;81}82 83static int chksum_update(struct shash_desc *desc, const u8 *data,84 unsigned int length)85{86 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);87 88 ctx->crc = __crc32c_le(ctx->crc, data, length);89 return 0;90}91 92static int chksum_final(struct shash_desc *desc, u8 *out)93{94 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);95 96 put_unaligned_le32(~ctx->crc, out);97 return 0;98}99 100static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)101{102 put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);103 return 0;104}105 106static int chksum_finup(struct shash_desc *desc, const u8 *data,107 unsigned int len, u8 *out)108{109 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);110 111 return __chksum_finup(&ctx->crc, data, len, out);112}113 114static int chksum_digest(struct shash_desc *desc, const u8 *data,115 unsigned int length, u8 *out)116{117 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);118 119 return __chksum_finup(&mctx->key, data, length, out);120}121 122static int crc32c_cra_init(struct crypto_tfm *tfm)123{124 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);125 126 mctx->key = ~0;127 return 0;128}129 130static struct shash_alg alg = {131 .digestsize = CHKSUM_DIGEST_SIZE,132 .setkey = chksum_setkey,133 .init = chksum_init,134 .update = chksum_update,135 .final = chksum_final,136 .finup = chksum_finup,137 .digest = chksum_digest,138 .descsize = sizeof(struct chksum_desc_ctx),139 .base = {140 .cra_name = "crc32c",141 .cra_driver_name = "crc32c-generic",142 .cra_priority = 100,143 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,144 .cra_blocksize = CHKSUM_BLOCK_SIZE,145 .cra_ctxsize = sizeof(struct chksum_ctx),146 .cra_module = THIS_MODULE,147 .cra_init = crc32c_cra_init,148 }149};150 151static int __init crc32c_mod_init(void)152{153 return crypto_register_shash(&alg);154}155 156static void __exit crc32c_mod_fini(void)157{158 crypto_unregister_shash(&alg);159}160 161subsys_initcall(crc32c_mod_init);162module_exit(crc32c_mod_fini);163 164MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");165MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");166MODULE_LICENSE("GPL");167MODULE_ALIAS_CRYPTO("crc32c");168MODULE_ALIAS_CRYPTO("crc32c-generic");169