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 (dctx->bytes) { 71 int n = min(srclen, dctx->bytes); 72 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 73 74 dctx->bytes -= n; 75 srclen -= n; 76 77 while (n--) 78 *pos++ ^= *src++; 79 80 if (!dctx->bytes) 81 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 82 } 83 84 while (srclen >= GHASH_BLOCK_SIZE) { 85 crypto_xor(dst, src, GHASH_BLOCK_SIZE); 86 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 87 src += GHASH_BLOCK_SIZE; 88 srclen -= GHASH_BLOCK_SIZE; 89 } 90 91 if (srclen) { 92 dctx->bytes = GHASH_BLOCK_SIZE - srclen; 93 while (srclen--) 94 *dst++ ^= *src++; 95 } 96 97 return 0; 98 } 99 100 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx) 101 { 102 u8 *dst = dctx->buffer; 103 104 if (dctx->bytes) { 105 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 106 107 while (dctx->bytes--) 108 *tmp++ ^= 0; 109 110 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 111 } 112 113 dctx->bytes = 0; 114 } 115 116 static int ghash_final(struct shash_desc *desc, u8 *dst) 117 { 118 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 119 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 120 u8 *buf = dctx->buffer; 121 122 ghash_flush(ctx, dctx); 123 memcpy(dst, buf, GHASH_BLOCK_SIZE); 124 125 return 0; 126 } 127 128 static void ghash_exit_tfm(struct crypto_tfm *tfm) 129 { 130 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm); 131 if (ctx->gf128) 132 gf128mul_free_4k(ctx->gf128); 133 } 134 135 static struct shash_alg ghash_alg = { 136 .digestsize = GHASH_DIGEST_SIZE, 137 .init = ghash_init, 138 .update = ghash_update, 139 .final = ghash_final, 140 .setkey = ghash_setkey, 141 .descsize = sizeof(struct ghash_desc_ctx), 142 .base = { 143 .cra_name = "ghash", 144 .cra_driver_name = "ghash-generic", 145 .cra_priority = 100, 146 .cra_flags = CRYPTO_ALG_TYPE_SHASH, 147 .cra_blocksize = GHASH_BLOCK_SIZE, 148 .cra_ctxsize = sizeof(struct ghash_ctx), 149 .cra_module = THIS_MODULE, 150 .cra_list = LIST_HEAD_INIT(ghash_alg.base.cra_list), 151 .cra_exit = ghash_exit_tfm, 152 }, 153 }; 154 155 static int __init ghash_mod_init(void) 156 { 157 return crypto_register_shash(&ghash_alg); 158 } 159 160 static void __exit ghash_mod_exit(void) 161 { 162 crypto_unregister_shash(&ghash_alg); 163 } 164 165 module_init(ghash_mod_init); 166 module_exit(ghash_mod_exit); 167 168 MODULE_LICENSE("GPL"); 169 MODULE_DESCRIPTION("GHASH Message Digest Algorithm"); 170 MODULE_ALIAS("ghash"); 171