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tag: v3.2-rc6
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/*
* GHASH: digest algorithm for GCM (Galois/Counter Mode).
*
* Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
* Copyright (c) 2009 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* The algorithm implementation is copied from gcm.c.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/

#include <crypto/algapi.h>
#include <crypto/gf128mul.h>
#include <crypto/internal/hash.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>

#define GHASH_BLOCK_SIZE 16
#define GHASH_DIGEST_SIZE 16

struct ghash_ctx {
struct gf128mul_4k *gf128;
};

struct ghash_desc_ctx {
u8 buffer[GHASH_BLOCK_SIZE];
u32 bytes;
};

static int ghash_init(struct shash_desc *desc)
{
struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);

memset(dctx, 0, sizeof(*dctx));

return 0;
}

static int ghash_setkey(struct crypto_shash *tfm,
const u8 *key, unsigned int keylen)
{
struct ghash_ctx *ctx = crypto_shash_ctx(tfm);

if (keylen != GHASH_BLOCK_SIZE) {
crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}

if (ctx->gf128)
gf128mul_free_4k(ctx->gf128);
ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
if (!ctx->gf128)
return -ENOMEM;

return 0;
}

static int ghash_update(struct shash_desc *desc,
const u8 *src, unsigned int srclen)
{
struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
u8 *dst = dctx->buffer;

if (!ctx->gf128)
return -ENOKEY;

if (dctx->bytes) {
int n = min(srclen, dctx->bytes);
u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);

dctx->bytes -= n;
srclen -= n;

while (n--)
*pos++ ^= *src++;

if (!dctx->bytes)
gf128mul_4k_lle((be128 *)dst, ctx->gf128);
}

while (srclen >= GHASH_BLOCK_SIZE) {
crypto_xor(dst, src, GHASH_BLOCK_SIZE);
gf128mul_4k_lle((be128 *)dst, ctx->gf128);
src += GHASH_BLOCK_SIZE;
srclen -= GHASH_BLOCK_SIZE;
}

if (srclen) {
dctx->bytes = GHASH_BLOCK_SIZE - srclen;
while (srclen--)
*dst++ ^= *src++;
}

return 0;
}

static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
{
u8 *dst = dctx->buffer;

if (dctx->bytes) {
u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);

while (dctx->bytes--)
*tmp++ ^= 0;

gf128mul_4k_lle((be128 *)dst, ctx->gf128);
}

dctx->bytes = 0;
}

static int ghash_final(struct shash_desc *desc, u8 *dst)
{
struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
u8 *buf = dctx->buffer;

if (!ctx->gf128)
return -ENOKEY;

ghash_flush(ctx, dctx);
memcpy(dst, buf, GHASH_BLOCK_SIZE);

return 0;
}

static void ghash_exit_tfm(struct crypto_tfm *tfm)
{
struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
if (ctx->gf128)
gf128mul_free_4k(ctx->gf128);
}

static struct shash_alg ghash_alg = {
.digestsize = GHASH_DIGEST_SIZE,
.init = ghash_init,
.update = ghash_update,
.final = ghash_final,
.setkey = ghash_setkey,
.descsize = sizeof(struct ghash_desc_ctx),
.base = {
.cra_name = "ghash",
.cra_driver_name = "ghash-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = GHASH_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct ghash_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(ghash_alg.base.cra_list),
.cra_exit = ghash_exit_tfm,
},
};

static int __init ghash_mod_init(void)
{
return crypto_register_shash(&ghash_alg);
}

static void __exit ghash_mod_exit(void)
{
crypto_unregister_shash(&ghash_alg);
}

module_init(ghash_mod_init);
module_exit(ghash_mod_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
MODULE_ALIAS("ghash");
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