LXR linux/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
  21static 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
  30static 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
  55static 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
  92static 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
 108static 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
 120static 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
 127static 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
 145static int __init ghash_mod_init(void)
 146{
 147        return crypto_register_shash(&ghash_alg);
 148}
 149
 150static void __exit ghash_mod_exit(void)
 151{
 152        crypto_unregister_shash(&ghash_alg);
 153}
 154
 155subsys_initcall(ghash_mod_init);
 156module_exit(ghash_mod_exit);
 157
 158MODULE_LICENSE("GPL");
 159MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
 160MODULE_ALIAS_CRYPTO("ghash");
 161MODULE_ALIAS_CRYPTO("ghash-generic");
 162