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/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         be128 k;
  38
  39         if (keylen != GHASH_BLOCK_SIZE) {
  40                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  41                 return -EINVAL;
  42         }
  43
  44         if (ctx->gf128)
  45                 gf128mul_free_4k(ctx->gf128);
  46
  47         BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
  48         memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
  49         ctx->gf128 = gf128mul_init_4k_lle(&k);
  50         memzero_explicit(&k, GHASH_BLOCK_SIZE);
  51
  52         if (!ctx->gf128)
  53                 return -ENOMEM;
  54
  55         return 0;
  56 }
  57
  58 static int ghash_update(struct shash_desc *desc,
  59                          const u8 *src, unsigned int srclen)
  60 {
  61         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  62         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  63         u8 *dst = dctx->buffer;
  64
  65         if (!ctx->gf128)
  66                 return -ENOKEY;
  67
  68         if (dctx->bytes) {
  69                 int n = min(srclen, dctx->bytes);
  70                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  71
  72                 dctx->bytes -= n;
  73                 srclen -= n;
  74
  75                 while (n--)
  76                         *pos++ ^= *src++;
  77
  78                 if (!dctx->bytes)
  79                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  80         }
  81
  82         while (srclen >= GHASH_BLOCK_SIZE) {
  83                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
  84                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  85                 src += GHASH_BLOCK_SIZE;
  86                 srclen -= GHASH_BLOCK_SIZE;
  87         }
  88
  89         if (srclen) {
  90                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  91                 while (srclen--)
  92                         *dst++ ^= *src++;
  93         }
  94
  95         return 0;
  96 }
  97
  98 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
  99 {
 100         u8 *dst = dctx->buffer;
 101
 102         if (dctx->bytes) {
 103                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
 104
 105                 while (dctx->bytes--)
 106                         *tmp++ ^= 0;
 107
 108                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
 109         }
 110
 111         dctx->bytes = 0;
 112 }
 113
 114 static int ghash_final(struct shash_desc *desc, u8 *dst)
 115 {
 116         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 117         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 118         u8 *buf = dctx->buffer;
 119
 120         if (!ctx->gf128)
 121                 return -ENOKEY;
 122
 123         ghash_flush(ctx, dctx);
 124         memcpy(dst, buf, GHASH_BLOCK_SIZE);
 125
 126         return 0;
 127 }
 128
 129 static void ghash_exit_tfm(struct crypto_tfm *tfm)
 130 {
 131         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 132         if (ctx->gf128)
 133                 gf128mul_free_4k(ctx->gf128);
 134 }
 135
 136 static struct shash_alg ghash_alg = {
 137         .digestsize     = GHASH_DIGEST_SIZE,
 138         .init           = ghash_init,
 139         .update         = ghash_update,
 140         .final          = ghash_final,
 141         .setkey         = ghash_setkey,
 142         .descsize       = sizeof(struct ghash_desc_ctx),
 143         .base           = {
 144                 .cra_name               = "ghash",
 145                 .cra_driver_name        = "ghash-generic",
 146                 .cra_priority           = 100,
 147                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
 148                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 149                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 150                 .cra_module             = THIS_MODULE,
 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_CRYPTO("ghash");
 171 MODULE_ALIAS_CRYPTO("ghash-generic");