crypto/ghash-generic.c

   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         be128 k;
  49
  50         if (keylen != GHASH_BLOCK_SIZE) {
  51                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  52                 return -EINVAL;
  53         }
  54
  55         if (ctx->gf128)
  56                 gf128mul_free_4k(ctx->gf128);
  57
  58         BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
  59         memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
  60         ctx->gf128 = gf128mul_init_4k_lle(&k);
  61         memzero_explicit(&k, GHASH_BLOCK_SIZE);
  62
  63         if (!ctx->gf128)
  64                 return -ENOMEM;
  65
  66         return 0;
  67 }
  68
  69 static int ghash_update(struct shash_desc *desc,
  70                          const u8 *src, unsigned int srclen)
  71 {
  72         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  73         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  74         u8 *dst = dctx->buffer;
  75
  76         if (!ctx->gf128)
  77                 return -ENOKEY;
  78
  79         if (dctx->bytes) {
  80                 int n = min(srclen, dctx->bytes);
  81                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  82
  83                 dctx->bytes -= n;
  84                 srclen -= n;
  85
  86                 while (n--)
  87                         *pos++ ^= *src++;
  88
  89                 if (!dctx->bytes)
  90                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  91         }
  92
  93         while (srclen >= GHASH_BLOCK_SIZE) {
  94                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
  95                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  96                 src += GHASH_BLOCK_SIZE;
  97                 srclen -= GHASH_BLOCK_SIZE;
  98         }
  99
 100         if (srclen) {
 101                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
 102                 while (srclen--)
 103                         *dst++ ^= *src++;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
 110 {
 111         u8 *dst = dctx->buffer;
 112
 113         if (dctx->bytes) {
 114                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
 115
 116                 while (dctx->bytes--)
 117                         *tmp++ ^= 0;
 118
 119                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
 120         }
 121
 122         dctx->bytes = 0;
 123 }
 124
 125 static int ghash_final(struct shash_desc *desc, u8 *dst)
 126 {
 127         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 128         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 129         u8 *buf = dctx->buffer;
 130
 131         if (!ctx->gf128)
 132                 return -ENOKEY;
 133
 134         ghash_flush(ctx, dctx);
 135         memcpy(dst, buf, GHASH_BLOCK_SIZE);
 136
 137         return 0;
 138 }
 139
 140 static void ghash_exit_tfm(struct crypto_tfm *tfm)
 141 {
 142         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 143         if (ctx->gf128)
 144                 gf128mul_free_4k(ctx->gf128);
 145 }
 146
 147 static struct shash_alg ghash_alg = {
 148         .digestsize     = GHASH_DIGEST_SIZE,
 149         .init           = ghash_init,
 150         .update         = ghash_update,
 151         .final          = ghash_final,
 152         .setkey         = ghash_setkey,
 153         .descsize       = sizeof(struct ghash_desc_ctx),
 154         .base           = {
 155                 .cra_name               = "ghash",
 156                 .cra_driver_name        = "ghash-generic",
 157                 .cra_priority           = 100,
 158                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 159                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 160                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 161                 .cra_module             = THIS_MODULE,
 162                 .cra_exit               = ghash_exit_tfm,
 163         },
 164 };
 165
 166 static int __init ghash_mod_init(void)
 167 {
 168         return crypto_register_shash(&ghash_alg);
 169 }
 170
 171 static void __exit ghash_mod_exit(void)
 172 {
 173         crypto_unregister_shash(&ghash_alg);
 174 }
 175
 176 module_init(ghash_mod_init);
 177 module_exit(ghash_mod_exit);
 178
 179 MODULE_LICENSE("GPL");
 180 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
 181 MODULE_ALIAS_CRYPTO("ghash");
 182 MODULE_ALIAS_CRYPTO("ghash-generic");