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 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 <linux/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 a 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 return -EINVAL; 79 mctx->key = get_unaligned_le32(key); 80 return 0; 81 } 82 83 static int chksum_update(struct shash_desc *desc, const u8 *data, 84 unsigned int length) 85 { 86 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 87 88 ctx->crc = __crc32c_le_base(ctx->crc, data, length); 89 return 0; 90 } 91 92 static int chksum_update_arch(struct shash_desc *desc, const u8 *data, 93 unsigned int length) 94 { 95 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 96 97 ctx->crc = __crc32c_le(ctx->crc, data, length); 98 return 0; 99 } 100 101 static int chksum_final(struct shash_desc *desc, u8 *out) 102 { 103 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 104 105 put_unaligned_le32(~ctx->crc, out); 106 return 0; 107 } 108 109 static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) 110 { 111 put_unaligned_le32(~__crc32c_le_base(*crcp, data, len), out); 112 return 0; 113 } 114 115 static int __chksum_finup_arch(u32 *crcp, const u8 *data, unsigned int len, 116 u8 *out) 117 { 118 put_unaligned_le32(~__crc32c_le(*crcp, data, len), out); 119 return 0; 120 } 121 122 static int chksum_finup(struct shash_desc *desc, const u8 *data, 123 unsigned int len, u8 *out) 124 { 125 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 126 127 return __chksum_finup(&ctx->crc, data, len, out); 128 } 129 130 static int chksum_finup_arch(struct shash_desc *desc, const u8 *data, 131 unsigned int len, u8 *out) 132 { 133 struct chksum_desc_ctx *ctx = shash_desc_ctx(desc); 134 135 return __chksum_finup_arch(&ctx->crc, data, len, out); 136 } 137 138 static int chksum_digest(struct shash_desc *desc, const u8 *data, 139 unsigned int length, u8 *out) 140 { 141 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); 142 143 return __chksum_finup(&mctx->key, data, length, out); 144 } 145 146 static int chksum_digest_arch(struct shash_desc *desc, const u8 *data, 147 unsigned int length, u8 *out) 148 { 149 struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm); 150 151 return __chksum_finup_arch(&mctx->key, data, length, out); 152 } 153 154 static int crc32c_cra_init(struct crypto_tfm *tfm) 155 { 156 struct chksum_ctx *mctx = crypto_tfm_ctx(tfm); 157 158 mctx->key = ~0; 159 return 0; 160 } 161 162 static struct shash_alg algs[] = {{ 163 .digestsize = CHKSUM_DIGEST_SIZE, 164 .setkey = chksum_setkey, 165 .init = chksum_init, 166 .update = chksum_update, 167 .final = chksum_final, 168 .finup = chksum_finup, 169 .digest = chksum_digest, 170 .descsize = sizeof(struct chksum_desc_ctx), 171 172 .base.cra_name = "crc32c", 173 .base.cra_driver_name = "crc32c-generic", 174 .base.cra_priority = 100, 175 .base.cra_flags = CRYPTO_ALG_OPTIONAL_KEY, 176 .base.cra_blocksize = CHKSUM_BLOCK_SIZE, 177 .base.cra_ctxsize = sizeof(struct chksum_ctx), 178 .base.cra_module = THIS_MODULE, 179 .base.cra_init = crc32c_cra_init, 180 }, { 181 .digestsize = CHKSUM_DIGEST_SIZE, 182 .setkey = chksum_setkey, 183 .init = chksum_init, 184 .update = chksum_update_arch, 185 .final = chksum_final, 186 .finup = chksum_finup_arch, 187 .digest = chksum_digest_arch, 188 .descsize = sizeof(struct chksum_desc_ctx), 189 190 .base.cra_name = "crc32c", 191 .base.cra_driver_name = "crc32c-" __stringify(ARCH), 192 .base.cra_priority = 150, 193 .base.cra_flags = CRYPTO_ALG_OPTIONAL_KEY, 194 .base.cra_blocksize = CHKSUM_BLOCK_SIZE, 195 .base.cra_ctxsize = sizeof(struct chksum_ctx), 196 .base.cra_module = THIS_MODULE, 197 .base.cra_init = crc32c_cra_init, 198 }}; 199 200 static int __init crc32c_mod_init(void) 201 { 202 /* register the arch flavor only if it differs from the generic one */ 203 return crypto_register_shashes(algs, 1 + (&__crc32c_le != &__crc32c_le_base)); 204 } 205 206 static void __exit crc32c_mod_fini(void) 207 { 208 crypto_unregister_shashes(algs, 1 + (&__crc32c_le != &__crc32c_le_base)); 209 } 210 211 subsys_initcall(crc32c_mod_init); 212 module_exit(crc32c_mod_fini); 213 214 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); 215 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c"); 216 MODULE_LICENSE("GPL"); 217 MODULE_ALIAS_CRYPTO("crc32c"); 218 MODULE_ALIAS_CRYPTO("crc32c-generic"); 219