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
  35         if (keylen != GHASH_BLOCK_SIZE) {
  36                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  37                 return -EINVAL;
  38         }
  39
  40         if (ctx->gf128)
  41                 gf128mul_free_4k(ctx->gf128);
  42         ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
  43         if (!ctx->gf128)
  44                 return -ENOMEM;
  45
  46         return 0;
  47 }
  48
  49 static int ghash_update(struct shash_desc *desc,
  50                          const u8 *src, unsigned int srclen)
  51 {
  52         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
  53         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
  54         u8 *dst = dctx->buffer;
  55
  56         if (dctx->bytes) {
  57                 int n = min(srclen, dctx->bytes);
  58                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  59
  60                 dctx->bytes -= n;
  61                 srclen -= n;
  62
  63                 while (n--)
  64                         *pos++ ^= *src++;
  65
  66                 if (!dctx->bytes)
  67                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  68         }
  69
  70         while (srclen >= GHASH_BLOCK_SIZE) {
  71                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
  72                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  73                 src += GHASH_BLOCK_SIZE;
  74                 srclen -= GHASH_BLOCK_SIZE;
  75         }
  76
  77         if (srclen) {
  78                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
  79                 while (srclen--)
  80                         *dst++ ^= *src++;
  81         }
  82
  83         return 0;
  84 }
  85
  86 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
  87 {
  88         u8 *dst = dctx->buffer;
  89
  90         if (dctx->bytes) {
  91                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
  92
  93                 while (dctx->bytes--)
  94                         *tmp++ ^= 0;
  95
  96                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  97         }
  98
  99         dctx->bytes = 0;
 100 }
 101
 102 static int ghash_final(struct shash_desc *desc, u8 *dst)
 103 {
 104         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 105         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
 106         u8 *buf = dctx->buffer;
 107
 108         ghash_flush(ctx, dctx);
 109         memcpy(dst, buf, GHASH_BLOCK_SIZE);
 110
 111         return 0;
 112 }
 113
 114 static void ghash_exit_tfm(struct crypto_tfm *tfm)
 115 {
 116         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 117         if (ctx->gf128)
 118                 gf128mul_free_4k(ctx->gf128);
 119 }
 120
 121 static struct shash_alg ghash_alg = {
 122         .digestsize     = GHASH_DIGEST_SIZE,
 123         .init           = ghash_init,
 124         .update         = ghash_update,
 125         .final          = ghash_final,
 126         .setkey         = ghash_setkey,
 127         .descsize       = sizeof(struct ghash_desc_ctx),
 128         .base           = {
 129                 .cra_name               = "ghash",
 130                 .cra_driver_name        = "ghash-generic",
 131                 .cra_priority           = 100,
 132                 .cra_blocksize          = GHASH_BLOCK_SIZE,
 133                 .cra_ctxsize            = sizeof(struct ghash_ctx),
 134                 .cra_module             = THIS_MODULE,
 135                 .cra_exit               = ghash_exit_tfm,
 136         },
 137 };
 138
 139 static int __init ghash_mod_init(void)
 140 {
 141         return crypto_register_shash(&ghash_alg);
 142 }
 143
 144 static void __exit ghash_mod_exit(void)
 145 {
 146         crypto_unregister_shash(&ghash_alg);
 147 }
 148
 149 subsys_initcall(ghash_mod_init);
 150 module_exit(ghash_mod_exit);
 151
 152 MODULE_LICENSE("GPL");
 153 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
 154 MODULE_ALIAS_CRYPTO("ghash");
 155 MODULE_ALIAS_CRYPTO("ghash-generic");