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/ghash.h> 18 #include <crypto/internal/hash.h> 19 #include <linux/crypto.h> 20 #include <linux/init.h> 21 #include <linux/kernel.h> 22 #include <linux/module.h> 23 24 static int ghash_init(struct shash_desc *desc) 25 { 26 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 27 28 memset(dctx, 0, sizeof(*dctx)); 29 30 return 0; 31 } 32 33 static int ghash_setkey(struct crypto_shash *tfm, 34 const u8 *key, unsigned int keylen) 35 { 36 struct ghash_ctx *ctx = crypto_shash_ctx(tfm); 37 38 if (keylen != GHASH_BLOCK_SIZE) { 39 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 40 return -EINVAL; 41 } 42 43 if (ctx->gf128) 44 gf128mul_free_4k(ctx->gf128); 45 ctx->gf128 = gf128mul_init_4k_lle((be128 *)key); 46 if (!ctx->gf128) 47 return -ENOMEM; 48 49 return 0; 50 } 51 52 static int ghash_update(struct shash_desc *desc, 53 const u8 *src, unsigned int srclen) 54 { 55 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 56 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 57 u8 *dst = dctx->buffer; 58 59 if (!ctx->gf128) 60 return -ENOKEY; 61 62 if (dctx->bytes) { 63 int n = min(srclen, dctx->bytes); 64 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 65 66 dctx->bytes -= n; 67 srclen -= n; 68 69 while (n--) 70 *pos++ ^= *src++; 71 72 if (!dctx->bytes) 73 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 74 } 75 76 while (srclen >= GHASH_BLOCK_SIZE) { 77 crypto_xor(dst, src, GHASH_BLOCK_SIZE); 78 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 79 src += GHASH_BLOCK_SIZE; 80 srclen -= GHASH_BLOCK_SIZE; 81 } 82 83 if (srclen) { 84 dctx->bytes = GHASH_BLOCK_SIZE - srclen; 85 while (srclen--) 86 *dst++ ^= *src++; 87 } 88 89 return 0; 90 } 91 92 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx) 93 { 94 u8 *dst = dctx->buffer; 95 96 if (dctx->bytes) { 97 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 98 99 while (dctx->bytes--) 100 *tmp++ ^= 0; 101 102 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 103 } 104 105 dctx->bytes = 0; 106 } 107 108 static int ghash_final(struct shash_desc *desc, u8 *dst) 109 { 110 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 111 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 112 u8 *buf = dctx->buffer; 113 114 if (!ctx->gf128) 115 return -ENOKEY; 116 117 ghash_flush(ctx, dctx); 118 memcpy(dst, buf, GHASH_BLOCK_SIZE); 119 120 return 0; 121 } 122 123 static void ghash_exit_tfm(struct crypto_tfm *tfm) 124 { 125 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm); 126 if (ctx->gf128) 127 gf128mul_free_4k(ctx->gf128); 128 } 129 130 static struct shash_alg ghash_alg = { 131 .digestsize = GHASH_DIGEST_SIZE, 132 .init = ghash_init, 133 .update = ghash_update, 134 .final = ghash_final, 135 .setkey = ghash_setkey, 136 .descsize = sizeof(struct ghash_desc_ctx), 137 .base = { 138 .cra_name = "ghash", 139 .cra_driver_name = "ghash-generic", 140 .cra_priority = 100, 141 .cra_flags = CRYPTO_ALG_TYPE_SHASH, 142 .cra_blocksize = GHASH_BLOCK_SIZE, 143 .cra_ctxsize = sizeof(struct ghash_ctx), 144 .cra_module = THIS_MODULE, 145 .cra_exit = ghash_exit_tfm, 146 }, 147 }; 148 149 static int __init ghash_mod_init(void) 150 { 151 return crypto_register_shash(&ghash_alg); 152 } 153 154 static void __exit ghash_mod_exit(void) 155 { 156 crypto_unregister_shash(&ghash_alg); 157 } 158 159 module_init(ghash_mod_init); 160 module_exit(ghash_mod_exit); 161 162 MODULE_LICENSE("GPL"); 163 MODULE_DESCRIPTION("GHASH Message Digest Algorithm"); 164 MODULE_ALIAS_CRYPTO("ghash"); 165 MODULE_ALIAS_CRYPTO("ghash-generic"); 166