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 (dctx->bytes) {
  66                 int n = min(srclen, dctx->bytes);
  67                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  68
  69                 dctx->bytes -= n;
  70                 srclen -= n;
  71
  72                 while (n--)
  73                         *pos++ ^= *src++;
  74
  75                 if (!dctx->bytes)
  76                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  77         }
  78
  79         while (srclen >= GHASH_BLOCK_SIZE) {
  80                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
  81                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  82                 src += GHASH_BLOCK_SIZE;
  83                 srclen -= GHASH_BLOCK_SIZE;
  84         }
  85
  86         if (srclen) {
  87                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  88                 while (srclen--)
  89                         *dst++ ^= *src++;
  90         }
  91
  92         return 0;
  93 }
  94
  95 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
  96 {
  97         u8 *dst = dctx->buffer;
  98
  99         if (dctx->bytes) {
 100                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
 101
 102                 while (dctx->bytes--)
 103                         *tmp++ ^= 0;
 104
 105                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
 106         }
 107
 108         dctx->bytes = 0;
 109 }
 110
 111 static int ghash_final(struct shash_desc *desc, u8 *dst)
 112 {
 113         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 114         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 115         u8 *buf = dctx->buffer;
 116
 117         ghash_flush(ctx, dctx);
 118         memcpy(dst, buf, GHASH_BLOCK_SIZE);
 119
 120         return 0;
 121 }
 122
 123 static void ghash_exit_tfm(struct crypto_tfm *tfm)
 124 {
 125         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 126         if (ctx->gf128)
 127                 gf128mul_free_4k(ctx->gf128);
 128 }
 129
 130 static struct shash_alg ghash_alg = {
 131         .digestsize     = GHASH_DIGEST_SIZE,
 132         .init           = ghash_init,
 133         .update         = ghash_update,
 134         .final          = ghash_final,
 135         .setkey         = ghash_setkey,
 136         .descsize       = sizeof(struct ghash_desc_ctx),
 137         .base           = {
 138                 .cra_name               = "ghash",
 139                 .cra_driver_name        = "ghash-generic",
 140                 .cra_priority           = 100,
 141                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 142                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 143                 .cra_module             = THIS_MODULE,
 144                 .cra_exit               = ghash_exit_tfm,
 145         },
 146 };
 147
 148 static int __init ghash_mod_init(void)
 149 {
 150         return crypto_register_shash(&ghash_alg);
 151 }
 152
 153 static void __exit ghash_mod_exit(void)
 154 {
 155         crypto_unregister_shash(&ghash_alg);
 156 }
 157
 158 module_init(ghash_mod_init);
 159 module_exit(ghash_mod_exit);
 160
 161 MODULE_LICENSE("GPL");
 162 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
 163 MODULE_ALIAS_CRYPTO("ghash");
 164 MODULE_ALIAS_CRYPTO("ghash-generic");