| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * 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> |
| */ |
| |
| #include <asm/unaligned.h> |
| #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 = get_unaligned_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); |
| |
| put_unaligned_le32(~ctx->crc, out); |
| return 0; |
| } |
| |
| static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) |
| { |
| put_unaligned_le32(~__crc32c_le(*crcp, data, len), out); |
| 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_flags = CRYPTO_ALG_OPTIONAL_KEY, |
| .cra_blocksize = CHKSUM_BLOCK_SIZE, |
| .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); |
| } |
| |
| subsys_initcall(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"); |
| MODULE_ALIAS_CRYPTO("crc32c"); |
| MODULE_ALIAS_CRYPTO("crc32c-generic"); |