175 lines
4.3 KiB
C
175 lines
4.3 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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*@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 the
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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 <herbert@gondor.apana.org.au>
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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 <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 at 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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crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
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return -EINVAL;
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}
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mctx->key = le32_to_cpu(*(__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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*(__le32 *)out = ~cpu_to_le32p(&ctx->crc);
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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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*(__le32 *)out = ~cpu_to_le32(__crc32c_le(*crcp, data, len));
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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_blocksize = CHKSUM_BLOCK_SIZE,
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.cra_alignmask = 3,
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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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module_init(crc32c_mod_init);
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module_exit(crc32c_mod_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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MODULE_ALIAS_CRYPTO("crc32c");
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MODULE_SOFTDEP("pre: crc32c");
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