113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/*
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* Cryptographic API.
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*
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* CRC32C chksum
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*
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* This module file is a wrapper to invoke the lib/crc32c routines.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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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/crypto.h>
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#include <linux/crc32c.h>
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#include <linux/types.h>
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#include <asm/byteorder.h>
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#define CHKSUM_BLOCK_SIZE 32
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#define CHKSUM_DIGEST_SIZE 4
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struct chksum_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 at time, calculates reflected
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* crc using table.
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*/
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static void chksum_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->crc = ~(u32)0; /* common usage */
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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_tfm *tfm, const u8 *key,
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unsigned int keylen, u32 *flags)
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{
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struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
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if (keylen != sizeof(mctx->crc)) {
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if (flags)
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*flags = CRYPTO_TFM_RES_BAD_KEY_LEN;
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return -EINVAL;
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}
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mctx->crc = __cpu_to_le32(*(u32 *)key);
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return 0;
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}
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static void chksum_update(struct crypto_tfm *tfm, const u8 *data,
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unsigned int length)
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{
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struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
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u32 mcrc;
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mcrc = crc32c(mctx->crc, data, (size_t)length);
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mctx->crc = mcrc;
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}
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static void chksum_final(struct crypto_tfm *tfm, u8 *out)
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{
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struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
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u32 mcrc = (mctx->crc ^ ~(u32)0);
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*(u32 *)out = __le32_to_cpu(mcrc);
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}
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static struct crypto_alg alg = {
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.cra_name = "crc32c",
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.cra_flags = CRYPTO_ALG_TYPE_DIGEST,
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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_list = LIST_HEAD_INIT(alg.cra_list),
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.cra_u = {
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.digest = {
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.dia_digestsize= CHKSUM_DIGEST_SIZE,
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.dia_setkey = chksum_setkey,
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.dia_init = chksum_init,
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.dia_update = chksum_update,
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.dia_final = chksum_final
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}
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}
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};
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static int __init init(void)
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{
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return crypto_register_alg(&alg);
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}
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static void __exit fini(void)
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{
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crypto_unregister_alg(&alg);
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}
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module_init(init);
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module_exit(fini);
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MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
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MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
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MODULE_LICENSE("GPL");
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