/* * Cryptographic API. * * CRC32C chksum * * This module file is a wrapper to invoke the lib/crc32c routines. * * 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 <linux/init.h> #include <linux/module.h> #include <linux/string.h> #include <linux/crypto.h> #include <linux/crc32c.h> #include <linux/kernel.h> #define CHKSUM_BLOCK_SIZE 32 #define CHKSUM_DIGEST_SIZE 4 struct chksum_ctx { u32 crc; u32 key; }; /* * Steps through buffer one byte at at time, calculates reflected * crc using table. */ static void chksum_init(struct crypto_tfm *tfm) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); mctx->crc = mctx->key; } /* * 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_tfm *tfm, const u8 *key, unsigned int keylen) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); if (keylen != sizeof(mctx->crc)) { tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; return -EINVAL; } mctx->key = le32_to_cpu(*(__le32 *)key); return 0; } static void chksum_update(struct crypto_tfm *tfm, const u8 *data, unsigned int length) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); mctx->crc = crc32c(mctx->crc, data, length); } static void chksum_final(struct crypto_tfm *tfm, u8 *out) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); *(__le32 *)out = ~cpu_to_le32(mctx->crc); } static int crc32c_cra_init(struct crypto_tfm *tfm) { struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); mctx->key = ~0; return 0; } static struct crypto_alg alg = { .cra_name = "crc32c", .cra_flags = CRYPTO_ALG_TYPE_DIGEST, .cra_blocksize = CHKSUM_BLOCK_SIZE, .cra_ctxsize = sizeof(struct chksum_ctx), .cra_module = THIS_MODULE, .cra_list = LIST_HEAD_INIT(alg.cra_list), .cra_init = crc32c_cra_init, .cra_u = { .digest = { .dia_digestsize= CHKSUM_DIGEST_SIZE, .dia_setkey = chksum_setkey, .dia_init = chksum_init, .dia_update = chksum_update, .dia_final = chksum_final } } }; static int __init init(void) { return crypto_register_alg(&alg); } static void __exit fini(void) { crypto_unregister_alg(&alg); } module_init(init); module_exit(fini); MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); MODULE_LICENSE("GPL");