1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Cryptographic API. 4 * 5 * CRC32C chksum 6 * 7 *@Article{castagnoli-crc, 8 * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman}, 9 * title = {{Optimization of Cyclic Redundancy-Check Codes with 24 10 * and 32 Parity Bits}}, 11 * journal = IEEE Transactions on Communication, 12 * year = {1993}, 13 * volume = {41}, 14 * number = {6}, 15 * pages = {}, 16 * month = {June}, 17 *} 18 * Used by the iSCSI driver, possibly others, and derived from the 19 * the iscsi-crc.c module of the linux-iscsi driver at 20 * http://linux-iscsi.sourceforge.net. 21 * 22 * Following the example of lib/crc32, this function is intended to be 23 * flexible and useful for all users. Modules that currently have their 24 * own crc32c, but hopefully may be able to use this one are: 25 * net/sctp (please add all your doco to here if you change to 26 * use this one!) 27 * <endoflist> 28 * 29 * Copyright (c) 2004 Cisco Systems, Inc. 30 * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au> 31 */ 32 33 #include <asm/unaligned.h> 34 #include <crypto/internal/hash.h> 35 #include <linux/init.h> 36 #include <linux/module.h> 37 #include <linux/string.h> 38 #include <linux/kernel.h> 39 #include <linux/crc32.h> 40 41 #define CHKSUM_BLOCK_SIZE 1 42 #define CHKSUM_DIGEST_SIZE 4 43 44 struct chksum_ctx { 45 u32 key; 46 }; 47 48 struct chksum_desc_ctx { 49 u32 crc; 50 }; 51 52 /* 53 * Steps through buffer one byte at at time, calculates reflected 54 * crc using table. 55 */ 56 57 static int chksum_init(struct shash_desc *desc) 58 { 59 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); 60 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 61 62 ctx->crc = mctx->key; 63 64 return 0; 65 } 66 67 /* 68 * Setting the seed allows arbitrary accumulators and flexible XOR policy 69 * If your algorithm starts with ~0, then XOR with ~0 before you set 70 * the seed. 71 */ 72 static int chksum_setkey(struct crypto_shash *tfm, const u8 *key, 73 unsigned int keylen) 74 { 75 struct chksum_ctx *mctx = crypto_shash_ctx(tfm); 76 77 if (keylen != sizeof(mctx->key)) { 78 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 79 return -EINVAL; 80 } 81 mctx->key = get_unaligned_le32(key); 82 return 0; 83 } 84 85 static int chksum_update(struct shash_desc *desc, const u8 *data, 86 unsigned int length) 87 { 88 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 89 90 ctx->crc = __crc32c_le(ctx->crc, data, length); 91 return 0; 92 } 93 94 static int chksum_final(struct shash_desc *desc, u8 *out) 95 { 96 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 97 98 put_unaligned_le32(~ctx->crc, out); 99 return 0; 100 } 101 102 static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) 103 { 104 put_unaligned_le32(~__crc32c_le(*crcp, data, len), out); 105 return 0; 106 } 107 108 static int chksum_finup(struct shash_desc *desc, const u8 *data, 109 unsigned int len, u8 *out) 110 { 111 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 112 113 return __chksum_finup(&ctx->crc, data, len, out); 114 } 115 116 static int chksum_digest(struct shash_desc *desc, const u8 *data, 117 unsigned int length, u8 *out) 118 { 119 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); 120 121 return __chksum_finup(&mctx->key, data, length, out); 122 } 123 124 static int crc32c_cra_init(struct crypto_tfm *tfm) 125 { 126 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 127 128 mctx->key = ~0; 129 return 0; 130 } 131 132 static struct shash_alg alg = { 133 .digestsize = CHKSUM_DIGEST_SIZE, 134 .setkey = chksum_setkey, 135 .init = chksum_init, 136 .update = chksum_update, 137 .final = chksum_final, 138 .finup = chksum_finup, 139 .digest = chksum_digest, 140 .descsize = sizeof(struct chksum_desc_ctx), 141 .base = { 142 .cra_name = "crc32c", 143 .cra_driver_name = "crc32c-generic", 144 .cra_priority = 100, 145 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY, 146 .cra_blocksize = CHKSUM_BLOCK_SIZE, 147 .cra_ctxsize = sizeof(struct chksum_ctx), 148 .cra_module = THIS_MODULE, 149 .cra_init = crc32c_cra_init, 150 } 151 }; 152 153 static int __init crc32c_mod_init(void) 154 { 155 return crypto_register_shash(&alg); 156 } 157 158 static void __exit crc32c_mod_fini(void) 159 { 160 crypto_unregister_shash(&alg); 161 } 162 163 subsys_initcall(crc32c_mod_init); 164 module_exit(crc32c_mod_fini); 165 166 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); 167 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); 168 MODULE_LICENSE("GPL"); 169 MODULE_ALIAS_CRYPTO("crc32c"); 170 MODULE_ALIAS_CRYPTO("crc32c-generic"); 171