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
  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 subsys_initcall(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");