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/*
* Copyright (C)2006 USAGI/WIDE Project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author:
* Kazunori Miyazawa <miyazawa@linux-ipv6.org>
*/

#include <crypto/internal/hash.h>
#include <linux/err.h>
#include <linux/kernel.h>

static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
0x02020202, 0x02020202, 0x02020202, 0x02020202,
0x03030303, 0x03030303, 0x03030303, 0x03030303};

/*
* +------------------------
* | <parent tfm>
* +------------------------
* | xcbc_tfm_ctx
* +------------------------
* | consts (block size * 2)
* +------------------------
*/
struct xcbc_tfm_ctx {
struct crypto_cipher *child;
u8 ctx[];
};

/*
* +------------------------
* | <shash desc>
* +------------------------
* | xcbc_desc_ctx
* +------------------------
* | odds (block size)
* +------------------------
* | prev (block size)
* +------------------------
*/
struct xcbc_desc_ctx {
unsigned int len;
u8 ctx[];
};

static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
const u8 *inkey, unsigned int keylen)
{
unsigned long alignmask = crypto_shash_alignmask(parent);
struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
int bs = crypto_shash_blocksize(parent);
u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
int err = 0;
u8 key1[bs];

if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
return err;

crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);

return crypto_cipher_setkey(ctx->child, key1, bs);

}

static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
{
unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
int bs = crypto_shash_blocksize(pdesc->tfm);
u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;

ctx->len = 0;
memset(prev, 0, bs);

return 0;
}

static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
unsigned int len)
{
struct crypto_shash *parent = pdesc->tfm;
unsigned long alignmask = crypto_shash_alignmask(parent);
struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
u8 *prev = odds + bs;

/* checking the data can fill the block */
if ((ctx->len + len) <= bs) {
memcpy(odds + ctx->len, p, len);
ctx->len += len;
return 0;
}

/* filling odds with new data and encrypting it */
memcpy(odds + ctx->len, p, bs - ctx->len);
len -= bs - ctx->len;
p += bs - ctx->len;

crypto_xor(prev, odds, bs);
crypto_cipher_encrypt_one(tfm, prev, prev);

/* clearing the length */
ctx->len = 0;

/* encrypting the rest of data */
while (len > bs) {
crypto_xor(prev, p, bs);
crypto_cipher_encrypt_one(tfm, prev, prev);
p += bs;
len -= bs;
}

/* keeping the surplus of blocksize */
if (len) {
memcpy(odds, p, len);
ctx->len = len;
}

return 0;
}

static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
{
struct crypto_shash *parent = pdesc->tfm;
unsigned long alignmask = crypto_shash_alignmask(parent);
struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
u8 *prev = odds + bs;
unsigned int offset = 0;

if (ctx->len != bs) {
unsigned int rlen;
u8 *p = odds + ctx->len;

*p = 0x80;
p++;

rlen = bs - ctx->len -1;
if (rlen)
memset(p, 0, rlen);

offset += bs;
}

crypto_xor(prev, odds, bs);
crypto_xor(prev, consts + offset, bs);

crypto_cipher_encrypt_one(tfm, out, prev);

return 0;
}

static int xcbc_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_cipher *cipher;
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_spawn *spawn = crypto_instance_ctx(inst);
struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);

cipher = crypto_spawn_cipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);

ctx->child = cipher;

return 0;
};

static void xcbc_exit_tfm(struct crypto_tfm *tfm)
{
struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
crypto_free_cipher(ctx->child);
}

static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct shash_instance *inst;
struct crypto_alg *alg;
unsigned long alignmask;
int err;

err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
if (err)
return err;

alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
if (IS_ERR(alg))
return PTR_ERR(alg);

switch(alg->cra_blocksize) {
case 16:
break;
default:
goto out_put_alg;
}

inst = shash_alloc_instance("xcbc", alg);
err = PTR_ERR(inst);
if (IS_ERR(inst))
goto out_put_alg;

err = crypto_init_spawn(shash_instance_ctx(inst), alg,
shash_crypto_instance(inst),
CRYPTO_ALG_TYPE_MASK);
if (err)
goto out_free_inst;

alignmask = alg->cra_alignmask | 3;
inst->alg.base.cra_alignmask = alignmask;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;

inst->alg.digestsize = alg->cra_blocksize;
inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
crypto_tfm_ctx_alignment()) +
(alignmask &
~(crypto_tfm_ctx_alignment() - 1)) +
alg->cra_blocksize * 2;

inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
alignmask + 1) +
alg->cra_blocksize * 2;
inst->alg.base.cra_init = xcbc_init_tfm;
inst->alg.base.cra_exit = xcbc_exit_tfm;

inst->alg.init = crypto_xcbc_digest_init;
inst->alg.update = crypto_xcbc_digest_update;
inst->alg.final = crypto_xcbc_digest_final;
inst->alg.setkey = crypto_xcbc_digest_setkey;

err = shash_register_instance(tmpl, inst);
if (err) {
out_free_inst:
shash_free_instance(shash_crypto_instance(inst));
}

out_put_alg:
crypto_mod_put(alg);
return err;
}

static struct crypto_template crypto_xcbc_tmpl = {
.name = "xcbc",
.create = xcbc_create,
.free = shash_free_instance,
.module = THIS_MODULE,
};

static int __init crypto_xcbc_module_init(void)
{
return crypto_register_template(&crypto_xcbc_tmpl);
}

static void __exit crypto_xcbc_module_exit(void)
{
crypto_unregister_template(&crypto_xcbc_tmpl);
}

module_init(crypto_xcbc_module_init);
module_exit(crypto_xcbc_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XCBC keyed hash algorithm");
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