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   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");