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 (dctx->bytes) { 60 int n = min(srclen, dctx->bytes); 61 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 62 63 dctx->bytes -= n; 64 srclen -= n; 65 66 while (n--) 67 *pos++ ^= *src++; 68 69 if (!dctx->bytes) 70 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 71 } 72 73 while (srclen >= GHASH_BLOCK_SIZE) { 74 crypto_xor(dst, src, GHASH_BLOCK_SIZE); 75 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 76 src += GHASH_BLOCK_SIZE; 77 srclen -= GHASH_BLOCK_SIZE; 78 } 79 80 if (srclen) { 81 dctx->bytes = GHASH_BLOCK_SIZE - srclen; 82 while (srclen--) 83 *dst++ ^= *src++; 84 } 85 86 return 0; 87 } 88 89 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx) 90 { 91 u8 *dst = dctx->buffer; 92 93 if (dctx->bytes) { 94 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes); 95 96 while (dctx->bytes--) 97 *tmp++ ^= 0; 98 99 gf128mul_4k_lle((be128 *)dst, ctx->gf128); 100 } 101 102 dctx->bytes = 0; 103 } 104 105 static int ghash_final(struct shash_desc *desc, u8 *dst) 106 { 107 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); 108 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); 109 u8 *buf = dctx->buffer; 110 111 ghash_flush(ctx, dctx); 112 memcpy(dst, buf, GHASH_BLOCK_SIZE); 113 114 return 0; 115 } 116 117 static void ghash_exit_tfm(struct crypto_tfm *tfm) 118 { 119 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm); 120 if (ctx->gf128) 121 gf128mul_free_4k(ctx->gf128); 122 } 123 124 static struct shash_alg ghash_alg = { 125 .digestsize = GHASH_DIGEST_SIZE, 126 .init = ghash_init, 127 .update = ghash_update, 128 .final = ghash_final, 129 .setkey = ghash_setkey, 130 .descsize = sizeof(struct ghash_desc_ctx), 131 .base = { 132 .cra_name = "ghash", 133 .cra_driver_name = "ghash-generic", 134 .cra_priority = 100, 135 .cra_blocksize = GHASH_BLOCK_SIZE, 136 .cra_ctxsize = sizeof(struct ghash_ctx), 137 .cra_module = THIS_MODULE, 138 .cra_exit = ghash_exit_tfm, 139 }, 140 }; 141 142 static int __init ghash_mod_init(void) 143 { 144 return crypto_register_shash(&ghash_alg); 145 } 146 147 static void __exit ghash_mod_exit(void) 148 { 149 crypto_unregister_shash(&ghash_alg); 150 } 151 152 module_init(ghash_mod_init); 153 module_exit(ghash_mod_exit); 154 155 MODULE_LICENSE("GPL"); 156 MODULE_DESCRIPTION("GHASH Message Digest Algorithm"); 157 MODULE_ALIAS_CRYPTO("ghash"); 158 MODULE_ALIAS_CRYPTO("ghash-generic"); 159