1 /* 2 * GHASH: digest algorithm for GCM (Galois/Counter Mode). 3 * 4 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi> 5 * Copyright (c) 2009 Intel Corp. 6 * Author: Huang Ying <ying.huang@intel.com> 7 * 8 * The algorithm implementation is copied from gcm.c. 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License version 2 as published 12 * by the Free Software Foundation. 13 */ 14 15 #include <crypto/algapi.h> 16 #include <crypto/gf128mul.h> 17 #include <crypto/internal/hash.h> 18 #include <linux/crypto.h> 19 #include <linux/init.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 23 #define GHASH_BLOCK_SIZE 16 24 #define GHASH_DIGEST_SIZE 16 25 26 struct ghash_ctx { 27 struct gf128mul_4k *gf128; 28 }; 29 30 struct ghash_desc_ctx { 31 u8 buffer[GHASH_BLOCK_SIZE]; 32 u32 bytes; 33 }; 34 35 static int ghash_init(struct shash_desc *desc) 36 { 37 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 38 39 memset(dctx, 0, sizeof(*dctx)); 40 41 return 0; 42 } 43 44 static int ghash_setkey(struct crypto_shash *tfm, 45 const u8 *key, unsigned int keylen) 46 { 47 struct ghash_ctx *ctx = crypto_shash_ctx(tfm); 48 49 if (keylen != GHASH_BLOCK_SIZE) { 50 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 51 return -EINVAL; 52 } 53 54 if (ctx->gf128) 55 gf128mul_free_4k(ctx->gf128); 56 ctx->gf128 = gf128mul_init_4k_lle((be128 *)key); 57 if (!ctx->gf128) 58 return -ENOMEM; 59 60 return 0; 61 } 62 63 static int ghash_update(struct shash_desc *desc, 64 const u8 *src, unsigned int srclen) 65 { 66 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 67 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 68 u8 *dst = dctx->buffer; 69 70 if (!ctx->gf128) 71 return -ENOKEY; 72 73 if (dctx->bytes) { 74 int n = min(srclen, dctx->bytes); 75 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 76 77 dctx->bytes -= n; 78 srclen -= n; 79 80 while (n--) 81 *pos++ ^= *src++; 82 83 if (!dctx->bytes) 84 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 85 } 86 87 while (srclen >= GHASH_BLOCK_SIZE) { 88 crypto_xor(dst, src, GHASH_BLOCK_SIZE); 89 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 90 src += GHASH_BLOCK_SIZE; 91 srclen -= GHASH_BLOCK_SIZE; 92 } 93 94 if (srclen) { 95 dctx->bytes = GHASH_BLOCK_SIZE - srclen; 96 while (srclen--) 97 *dst++ ^= *src++; 98 } 99 100 return 0; 101 } 102 103 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx) 104 { 105 u8 *dst = dctx->buffer; 106 107 if (dctx->bytes) { 108 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 109 110 while (dctx->bytes--) 111 *tmp++ ^= 0; 112 113 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 114 } 115 116 dctx->bytes = 0; 117 } 118 119 static int ghash_final(struct shash_desc *desc, u8 *dst) 120 { 121 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 122 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 123 u8 *buf = dctx->buffer; 124 125 if (!ctx->gf128) 126 return -ENOKEY; 127 128 ghash_flush(ctx, dctx); 129 memcpy(dst, buf, GHASH_BLOCK_SIZE); 130 131 return 0; 132 } 133 134 static void ghash_exit_tfm(struct crypto_tfm *tfm) 135 { 136 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm); 137 if (ctx->gf128) 138 gf128mul_free_4k(ctx->gf128); 139 } 140 141 static struct shash_alg ghash_alg = { 142 .digestsize = GHASH_DIGEST_SIZE, 143 .init = ghash_init, 144 .update = ghash_update, 145 .final = ghash_final, 146 .setkey = ghash_setkey, 147 .descsize = sizeof(struct ghash_desc_ctx), 148 .base = { 149 .cra_name = "ghash", 150 .cra_driver_name = "ghash-generic", 151 .cra_priority = 100, 152 .cra_flags = CRYPTO_ALG_TYPE_SHASH, 153 .cra_blocksize = GHASH_BLOCK_SIZE, 154 .cra_ctxsize = sizeof(struct ghash_ctx), 155 .cra_module = THIS_MODULE, 156 .cra_exit = ghash_exit_tfm, 157 }, 158 }; 159 160 static int __init ghash_mod_init(void) 161 { 162 return crypto_register_shash(&ghash_alg); 163 } 164 165 static void __exit ghash_mod_exit(void) 166 { 167 crypto_unregister_shash(&ghash_alg); 168 } 169 170 module_init(ghash_mod_init); 171 module_exit(ghash_mod_exit); 172 173 MODULE_LICENSE("GPL"); 174 MODULE_DESCRIPTION("GHASH Message Digest Algorithm"); 175 MODULE_ALIAS_CRYPTO("ghash"); 176 MODULE_ALIAS_CRYPTO("ghash-generic"); 177