diff options
Diffstat (limited to 'crypto/crc32c.c')
-rw-r--r-- | crypto/crc32c.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/crypto/crc32c.c b/crypto/crc32c.c new file mode 100644 index 0000000..256956c --- /dev/null +++ b/crypto/crc32c.c @@ -0,0 +1,110 @@ +/* + * 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 <asm/byteorder.h> + +#define CHKSUM_BLOCK_SIZE 32 +#define CHKSUM_DIGEST_SIZE 4 + +struct chksum_ctx { + u32 crc; +}; + +/* + * Steps through buffer one byte at at time, calculates reflected + * crc using table. + */ + +static void chksum_init(void *ctx) +{ + struct chksum_ctx *mctx = ctx; + + mctx->crc = ~(u32)0; /* common usage */ +} + +/* + * 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(void *ctx, const u8 *key, unsigned int keylen, + u32 *flags) +{ + struct chksum_ctx *mctx = ctx; + + if (keylen != sizeof(mctx->crc)) { + if (flags) + *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; + return -EINVAL; + } + mctx->crc = __cpu_to_le32(*(u32 *)key); + return 0; +} + +static void chksum_update(void *ctx, const u8 *data, unsigned int length) +{ + struct chksum_ctx *mctx = ctx; + u32 mcrc; + + mcrc = crc32c(mctx->crc, data, (size_t)length); + + mctx->crc = mcrc; +} + +static void chksum_final(void *ctx, u8 *out) +{ + struct chksum_ctx *mctx = ctx; + u32 mcrc = (mctx->crc ^ ~(u32)0); + + *(u32 *)out = __le32_to_cpu(mcrc); +} + +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_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"); |