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168 lines
4.1 KiB
168 lines
4.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Cryptographic API. |
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* |
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* CRC32C chksum |
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* |
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*@Article{castagnoli-crc, |
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* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman}, |
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* title = {{Optimization of Cyclic Redundancy-Check Codes with 24 |
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* and 32 Parity Bits}}, |
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* journal = IEEE Transactions on Communication, |
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* year = {1993}, |
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* volume = {41}, |
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* number = {6}, |
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* pages = {}, |
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* month = {June}, |
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*} |
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* Used by the iSCSI driver, possibly others, and derived from |
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* the iscsi-crc.c module of the linux-iscsi driver at |
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* http://linux-iscsi.sourceforge.net. |
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* |
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* Following the example of lib/crc32, this function is intended to be |
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* flexible and useful for all users. Modules that currently have their |
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* own crc32c, but hopefully may be able to use this one are: |
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* net/sctp (please add all your doco to here if you change to |
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* use this one!) |
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* <endoflist> |
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* |
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* Copyright (c) 2004 Cisco Systems, Inc. |
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* Copyright (c) 2008 Herbert Xu <[email protected]> |
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*/ |
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#include <asm/unaligned.h> |
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#include <crypto/internal/hash.h> |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/string.h> |
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#include <linux/kernel.h> |
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#include <linux/crc32.h> |
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#define CHKSUM_BLOCK_SIZE 1 |
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#define CHKSUM_DIGEST_SIZE 4 |
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struct chksum_ctx { |
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u32 key; |
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}; |
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struct chksum_desc_ctx { |
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u32 crc; |
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}; |
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/* |
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* Steps through buffer one byte at a time, calculates reflected |
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* crc using table. |
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*/ |
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static int chksum_init(struct shash_desc *desc) |
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{ |
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struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); |
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); |
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ctx->crc = mctx->key; |
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return 0; |
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} |
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/* |
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* Setting the seed allows arbitrary accumulators and flexible XOR policy |
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* If your algorithm starts with ~0, then XOR with ~0 before you set |
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* the seed. |
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*/ |
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static int chksum_setkey(struct crypto_shash *tfm, const u8 *key, |
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unsigned int keylen) |
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{ |
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struct chksum_ctx *mctx = crypto_shash_ctx(tfm); |
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if (keylen != sizeof(mctx->key)) |
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return -EINVAL; |
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mctx->key = get_unaligned_le32(key); |
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return 0; |
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} |
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static int chksum_update(struct shash_desc *desc, const u8 *data, |
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unsigned int length) |
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{ |
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); |
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ctx->crc = __crc32c_le(ctx->crc, data, length); |
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return 0; |
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} |
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static int chksum_final(struct shash_desc *desc, u8 *out) |
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{ |
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); |
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put_unaligned_le32(~ctx->crc, out); |
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return 0; |
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} |
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static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) |
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{ |
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put_unaligned_le32(~__crc32c_le(*crcp, data, len), out); |
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return 0; |
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} |
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static int chksum_finup(struct shash_desc *desc, const u8 *data, |
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unsigned int len, u8 *out) |
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{ |
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); |
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return __chksum_finup(&ctx->crc, data, len, out); |
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} |
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static int chksum_digest(struct shash_desc *desc, const u8 *data, |
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unsigned int length, u8 *out) |
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{ |
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struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); |
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return __chksum_finup(&mctx->key, data, length, out); |
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} |
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static int crc32c_cra_init(struct crypto_tfm *tfm) |
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{ |
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struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); |
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mctx->key = ~0; |
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return 0; |
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} |
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static struct shash_alg alg = { |
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.digestsize = CHKSUM_DIGEST_SIZE, |
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.setkey = chksum_setkey, |
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.init = chksum_init, |
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.update = chksum_update, |
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.final = chksum_final, |
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.finup = chksum_finup, |
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.digest = chksum_digest, |
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.descsize = sizeof(struct chksum_desc_ctx), |
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.base = { |
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.cra_name = "crc32c", |
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.cra_driver_name = "crc32c-generic", |
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.cra_priority = 100, |
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.cra_flags = CRYPTO_ALG_OPTIONAL_KEY, |
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.cra_blocksize = CHKSUM_BLOCK_SIZE, |
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.cra_ctxsize = sizeof(struct chksum_ctx), |
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.cra_module = THIS_MODULE, |
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.cra_init = crc32c_cra_init, |
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} |
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}; |
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static int __init crc32c_mod_init(void) |
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{ |
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return crypto_register_shash(&alg); |
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} |
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static void __exit crc32c_mod_fini(void) |
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{ |
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crypto_unregister_shash(&alg); |
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} |
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subsys_initcall(crc32c_mod_init); |
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module_exit(crc32c_mod_fini); |
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MODULE_AUTHOR("Clay Haapala <[email protected]>"); |
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MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS_CRYPTO("crc32c"); |
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MODULE_ALIAS_CRYPTO("crc32c-generic");
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