/* * Cryptographic API. * * CRC32C chksum * *@Article{castagnoli-crc, * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman}, * title = {{Optimization of Cyclic Redundancy-Check Codes with 24 * and 32 Parity Bits}}, * journal = IEEE Transactions on Communication, * year = {1993}, * volume = {41}, * number = {6}, * pages = {}, * month = {June}, *} * Used by the iSCSI driver, possibly others, and derived from the * the iscsi-crc.c module of the linux-iscsi driver at * http://linux-iscsi.sourceforge.net. * * Following the example of lib/crc32, this function is intended to be * flexible and useful for all users. Modules that currently have their * own crc32c, but hopefully may be able to use this one are: * net/sctp (please add all your doco to here if you change to * use this one!) * <endoflist> * * Copyright (c) 2004 Cisco Systems, Inc. * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. * */ #include <crypto/internal/hash.h> #include <linux/init.h> #include <linux/module.h> #include <linux/string.h> #include <linux/kernel.h> #include <linux/crc32.h> #define CHKSUM_BLOCK_SIZE 1 #define CHKSUM_DIGEST_SIZE 4 struct chksum_ctx { u32 key; }; struct chksum_desc_ctx { u32 crc; }; /* * Steps through buffer one byte at at time, calculates reflected * crc using table. */ static int chksum_init(struct shash_desc *desc) { struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); ctx->crc = mctx->key; return 0; } /* * Setting the seed allows arbitrary accumulators and flexible XOR policy * If your algorithm starts with ~0, then XOR with ~0 before you set * the seed. */ static int chksum_setkey(struct crypto_shash *tfm, const u8 *key, unsigned int keylen) { struct chksum_ctx *mctx = crypto_shash_ctx(tfm); if (keylen != sizeof(mctx->key)) { crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); return -EINVAL; } mctx->key = le32_to_cpu(*(__le32 *)key); return 0; } static int chksum_update(struct shash_desc *desc, const u8 *data, unsigned int length) { struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); ctx->crc = __crc32c_le(ctx->crc, data, length); return 0; } static int chksum_final(struct shash_desc *desc, u8 *out) { struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); *(__le32 *)out = ~cpu_to_le32p(&ctx->crc); return 0; } static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) { *(__le32 *)out = ~cpu_to_le32(__crc32c_le(*crcp, data, len)); return 0; } static int chksum_finup(struct shash_desc *desc, const u8 *data, unsigned int len, u8 *out) { struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); return __chksum_finup(&ctx->crc, data, len, out); } static int chksum_digest(struct shash_desc *desc, const u8 *data, unsigned int length, u8 *out) { struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); return __chksum_finup(&mctx->key, data, length, out); } static int crc32c_cra_init(struct crypto_tfm *tfm) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); mctx->key = ~0; return 0; } static struct shash_alg alg = { .digestsize = CHKSUM_DIGEST_SIZE, .setkey = chksum_setkey, .init = chksum_init, .update = chksum_update, .final = chksum_final, .finup = chksum_finup, .digest = chksum_digest, .descsize = sizeof(struct chksum_desc_ctx), .base = { .cra_name = "crc32c", .cra_driver_name = "crc32c-generic", .cra_priority = 100, .cra_blocksize = CHKSUM_BLOCK_SIZE, .cra_alignmask = 3, .cra_ctxsize = sizeof(struct chksum_ctx), .cra_module = THIS_MODULE, .cra_init = crc32c_cra_init, } }; static int __init crc32c_mod_init(void) { return crypto_register_shash(&alg); } static void __exit crc32c_mod_fini(void) { crypto_unregister_shash(&alg); } module_init(crc32c_mod_init); module_exit(crc32c_mod_fini); MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); MODULE_LICENSE("GPL");