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 <linux/types.h> 20 #include <asm/byteorder.h> 21 22 #define CHKSUM_BLOCK_SIZE 32 23 #define CHKSUM_DIGEST_SIZE 4 24 25 struct chksum_ctx { 26 u32 crc; 27 }; 28 29 /* 30 * Steps through buffer one byte at at time, calculates reflected 31 * crc using table. 32 */ 33 34 static void chksum_init(struct crypto_tfm *tfm) 35 { 36 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 37 38 mctx->crc = ~(u32)0; /* common usage */ 39 } 40 41 /* 42 * Setting the seed allows arbitrary accumulators and flexible XOR policy 43 * If your algorithm starts with ~0, then XOR with ~0 before you set 44 * the seed. 45 */ 46 static int chksum_setkey(struct crypto_tfm *tfm, const u8 *key, 47 unsigned int keylen, u32 *flags) 48 { 49 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 50 51 if (keylen != sizeof(mctx->crc)) { 52 if (flags) 53 *flags = CRYPTO_TFM_RES_BAD_KEY_LEN; 54 return -EINVAL; 55 } 56 mctx->crc = __cpu_to_le32(*(u32 *)key); 57 return 0; 58 } 59 60 static void chksum_update(struct crypto_tfm *tfm, const u8 *data, 61 unsigned int length) 62 { 63 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 64 u32 mcrc; 65 66 mcrc = crc32c(mctx->crc, data, (size_t)length); 67 68 mctx->crc = mcrc; 69 } 70 71 static void chksum_final(struct crypto_tfm *tfm, u8 *out) 72 { 73 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 74 u32 mcrc = (mctx->crc ^ ~(u32)0); 75 76 *(u32 *)out = __le32_to_cpu(mcrc); 77 } 78 79 static struct crypto_alg alg = { 80 .cra_name = "crc32c", 81 .cra_flags = CRYPTO_ALG_TYPE_DIGEST, 82 .cra_blocksize = CHKSUM_BLOCK_SIZE, 83 .cra_ctxsize = sizeof(struct chksum_ctx), 84 .cra_module = THIS_MODULE, 85 .cra_list = LIST_HEAD_INIT(alg.cra_list), 86 .cra_u = { 87 .digest = { 88 .dia_digestsize= CHKSUM_DIGEST_SIZE, 89 .dia_setkey = chksum_setkey, 90 .dia_init = chksum_init, 91 .dia_update = chksum_update, 92 .dia_final = chksum_final 93 } 94 } 95 }; 96 97 static int __init init(void) 98 { 99 return crypto_register_alg(&alg); 100 } 101 102 static void __exit fini(void) 103 { 104 crypto_unregister_alg(&alg); 105 } 106 107 module_init(init); 108 module_exit(fini); 109 110 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); 111 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); 112 MODULE_LICENSE("GPL"); 113