1 /* 2 * Cryptographic API. 3 * 4 * CRC32C chksum 5 * 6 * This module file is a wrapper to invoke the lib/crc32c routines. 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the Free 10 * Software Foundation; either version 2 of the License, or (at your option) 11 * any later version. 12 * 13 */ 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/string.h> 17 #include <linux/crypto.h> 18 #include <linux/crc32c.h> 19 #include <asm/byteorder.h> 20 21 #define CHKSUM_BLOCK_SIZE 32 22 #define CHKSUM_DIGEST_SIZE 4 23 24 struct chksum_ctx { 25 u32 crc; 26 }; 27 28 /* 29 * Steps through buffer one byte at at time, calculates reflected 30 * crc using table. 31 */ 32 33 static void chksum_init(void *ctx) 34 { 35 struct chksum_ctx *mctx = ctx; 36 37 mctx->crc = ~(u32)0; /* common usage */ 38 } 39 40 /* 41 * Setting the seed allows arbitrary accumulators and flexible XOR policy 42 * If your algorithm starts with ~0, then XOR with ~0 before you set 43 * the seed. 44 */ 45 static int chksum_setkey(void *ctx, const u8 *key, unsigned int keylen, 46 u32 *flags) 47 { 48 struct chksum_ctx *mctx = ctx; 49 50 if (keylen != sizeof(mctx->crc)) { 51 if (flags) 52 *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; 53 return -EINVAL; 54 } 55 mctx->crc = __cpu_to_le32(*(u32 *)key); 56 return 0; 57 } 58 59 static void chksum_update(void *ctx, const u8 *data, unsigned int length) 60 { 61 struct chksum_ctx *mctx = ctx; 62 u32 mcrc; 63 64 mcrc = crc32c(mctx->crc, data, (size_t)length); 65 66 mctx->crc = mcrc; 67 } 68 69 static void chksum_final(void *ctx, u8 *out) 70 { 71 struct chksum_ctx *mctx = ctx; 72 u32 mcrc = (mctx->crc ^ ~(u32)0); 73 74 *(u32 *)out = __le32_to_cpu(mcrc); 75 } 76 77 static struct crypto_alg alg = { 78 .cra_name = "crc32c", 79 .cra_flags = CRYPTO_ALG_TYPE_DIGEST, 80 .cra_blocksize = CHKSUM_BLOCK_SIZE, 81 .cra_ctxsize = sizeof(struct chksum_ctx), 82 .cra_module = THIS_MODULE, 83 .cra_list = LIST_HEAD_INIT(alg.cra_list), 84 .cra_u = { 85 .digest = { 86 .dia_digestsize= CHKSUM_DIGEST_SIZE, 87 .dia_setkey = chksum_setkey, 88 .dia_init = chksum_init, 89 .dia_update = chksum_update, 90 .dia_final = chksum_final 91 } 92 } 93 }; 94 95 static int __init init(void) 96 { 97 return crypto_register_alg(&alg); 98 } 99 100 static void __exit fini(void) 101 { 102 crypto_unregister_alg(&alg); 103 } 104 105 module_init(init); 106 module_exit(fini); 107 108 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); 109 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); 110 MODULE_LICENSE("GPL"); 111