crypto/ghash-generic.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * GHASH: digest algorithm for GCM (Galois/Counter Mode).
   4  *
   5  * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
   6  * Copyright (c) 2009 Intel Corp.
   7  *   Author: Huang Ying <ying.huang@intel.com>
   8  *
   9  * The algorithm implementation is copied from gcm.c.
  10  */
  11
  12 #include <crypto/algapi.h>
  13 #include <crypto/gf128mul.h>
  14 #include <crypto/ghash.h>
  15 #include <crypto/internal/hash.h>
  16 #include <linux/crypto.h>
  17 #include <linux/init.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20
  21 static int ghash_init(struct shash_desc *desc)
  22 {
  23         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  24
  25         memset(dctx, 0, sizeof(*dctx));
  26
  27         return 0;
  28 }
  29
  30 static int ghash_setkey(struct crypto_shash *tfm,
  31                         const u8 *key, unsigned int keylen)
  32 {
  33         struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
  34         be128 k;
  35
  36         if (keylen != GHASH_BLOCK_SIZE) {
  37                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  38                 return -EINVAL;
  39         }
  40
  41         if (ctx->gf128)
  42                 gf128mul_free_4k(ctx->gf128);
  43
  44         BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
  45         memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
  46         ctx->gf128 = gf128mul_init_4k_lle(&k);
  47         memzero_explicit(&k, GHASH_BLOCK_SIZE);
  48
  49         if (!ctx->gf128)
  50                 return -ENOMEM;
  51
  52         return 0;
  53 }
  54
  55 static int ghash_update(struct shash_desc *desc,
  56                          const u8 *src, unsigned int srclen)
  57 {
  58         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  59         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  60         u8 *dst = dctx->buffer;
  61
  62         if (dctx->bytes) {
  63                 int n = min(srclen, dctx->bytes);
  64                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  65
  66                 dctx->bytes -= n;
  67                 srclen -= n;
  68
  69                 while (n--)
  70                         *pos++ ^= *src++;
  71
  72                 if (!dctx->bytes)
  73                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  74         }
  75
  76         while (srclen >= GHASH_BLOCK_SIZE) {
  77                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
  78                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  79                 src += GHASH_BLOCK_SIZE;
  80                 srclen -= GHASH_BLOCK_SIZE;
  81         }
  82
  83         if (srclen) {
  84                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  85                 while (srclen--)
  86                         *dst++ ^= *src++;
  87         }
  88
  89         return 0;
  90 }
  91
  92 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
  93 {
  94         u8 *dst = dctx->buffer;
  95
  96         if (dctx->bytes) {
  97                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  98
  99                 while (dctx->bytes--)
 100                         *tmp++ ^= 0;
 101
 102                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
 103         }
 104
 105         dctx->bytes = 0;
 106 }
 107
 108 static int ghash_final(struct shash_desc *desc, u8 *dst)
 109 {
 110         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 111         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 112         u8 *buf = dctx->buffer;
 113
 114         ghash_flush(ctx, dctx);
 115         memcpy(dst, buf, GHASH_BLOCK_SIZE);
 116
 117         return 0;
 118 }
 119
 120 static void ghash_exit_tfm(struct crypto_tfm *tfm)
 121 {
 122         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 123         if (ctx->gf128)
 124                 gf128mul_free_4k(ctx->gf128);
 125 }
 126
 127 static struct shash_alg ghash_alg = {
 128         .digestsize     = GHASH_DIGEST_SIZE,
 129         .init           = ghash_init,
 130         .update         = ghash_update,
 131         .final          = ghash_final,
 132         .setkey         = ghash_setkey,
 133         .descsize       = sizeof(struct ghash_desc_ctx),
 134         .base           = {
 135                 .cra_name               = "ghash",
 136                 .cra_driver_name        = "ghash-generic",
 137                 .cra_priority           = 100,
 138                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 139                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 140                 .cra_module             = THIS_MODULE,
 141                 .cra_exit               = ghash_exit_tfm,
 142         },
 143 };
 144
 145 static int __init ghash_mod_init(void)
 146 {
 147         return crypto_register_shash(&ghash_alg);
 148 }
 149
 150 static void __exit ghash_mod_exit(void)
 151 {
 152         crypto_unregister_shash(&ghash_alg);
 153 }
 154
 155 subsys_initcall(ghash_mod_init);
 156 module_exit(ghash_mod_exit);
 157
 158 MODULE_LICENSE("GPL");
 159 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
 160 MODULE_ALIAS_CRYPTO("ghash");
 161 MODULE_ALIAS_CRYPTO("ghash-generic");