/*

 * cryptsetup plain device helper functions

 *

 * Copyright (C) 2004 Jana Saout <jana@saout.de>

 * Copyright (C) 2010-2020 Red Hat, Inc. All rights reserved.

 * Copyright (C) 2010-2020 Milan Broz

 *

 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include <string.h>

#include <stdio.h>

#include <errno.h>

#include "libcryptsetup.h"

#include "internal.h"

static int hash(const char *hash_name, size_t key_size, char *key,

		size_t passphrase_size, const char *passphrase)

{

	struct crypt_hash *md = NULL;

	size_t len;

	int round, i, r = 0;

	if (crypt_hash_init(&md, hash_name))

		return -ENOENT;

	len = crypt_hash_size(hash_name);

	for(round = 0; key_size && !r; round++) {

		/* hack from hashalot to avoid null bytes in key */

		for(i = 0; i < round; i++)

			if (crypt_hash_write(md, "A", 1))

				r = 1;

		if (crypt_hash_write(md, passphrase, passphrase_size))

			r = 1;

		if (len > key_size)

			len = key_size;

		if (crypt_hash_final(md, key, len))

			r = 1;

		key += len;

		key_size -= len;

	}

	crypt_hash_destroy(md);

	return r;

}

#define PLAIN_HASH_LEN_MAX 256

int crypt_plain_hash(struct crypt_device *cd,

		     const char *hash_name,

		     char *key, size_t key_size,

		     const char *passphrase, size_t passphrase_size)

{

	char hash_name_buf[PLAIN_HASH_LEN_MAX], *s;

	size_t hash_size, pad_size;

	int r;

	log_dbg(cd, "Plain: hashing passphrase using %s.", hash_name);

	if (strlen(hash_name) >= PLAIN_HASH_LEN_MAX)

		return -EINVAL;

	strncpy(hash_name_buf, hash_name, PLAIN_HASH_LEN_MAX);

	hash_name_buf[PLAIN_HASH_LEN_MAX - 1] = '\0';

	/* hash[:hash_length] */

	if ((s = strchr(hash_name_buf, ':'))) {

		*s = '\0';

		s++;

		if (!*s || sscanf(s, "%zd", &hash_size) != 1) {

			log_dbg(cd, "Hash length is not a number");

			return -EINVAL;

		}

		if (hash_size > key_size) {

			log_dbg(cd, "Hash length %zd > key length %zd",

				hash_size, key_size);

			return -EINVAL;

		}

		pad_size = key_size - hash_size;

	} else {

		hash_size = key_size;

		pad_size = 0;

	}

	/* No hash, copy passphrase directly */

	if (!strcmp(hash_name_buf, "plain")) {

		if (passphrase_size < hash_size) {

			log_dbg(cd, "Too short plain passphrase.");

			return -EINVAL;

		}

		memcpy(key, passphrase, hash_size);

		r = 0;

	} else

		r = hash(hash_name_buf, hash_size, key, passphrase_size, passphrase);

	if (r == 0 && pad_size)

		memset(key + hash_size, 0, pad_size);

	return r;

}