view bignum.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 1051e4eea25a
children 8b4274d34fe8
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/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

/* Contains helper functions for mp_int handling */

#include "includes.h"
#include "dbutil.h"

/* wrapper for mp_init, failing fatally on errors (memory allocation) */
void m_mp_init(mp_int *mp) {

	if (mp_init(mp) != MP_OKAY) {
		dropbear_exit("Mem alloc error");
	}
}

/* simplified duplication of bn_mp_multi's mp_init_multi, but die fatally
 * on error */
void m_mp_init_multi(mp_int *mp, ...) 
{
	mp_int* cur_arg = mp;
	va_list args;

	va_start(args, mp);        /* init args to next argument from caller */
	while (cur_arg != NULL) {
		if (mp_init(cur_arg) != MP_OKAY) {
			dropbear_exit("Mem alloc error");
		}
		cur_arg = va_arg(args, mp_int*);
	}
	va_end(args);
}

void m_mp_alloc_init_multi(mp_int **mp, ...) 
{
	mp_int** cur_arg = mp;
	va_list args;

	va_start(args, mp);        /* init args to next argument from caller */
	while (cur_arg != NULL) {
		*cur_arg = m_malloc(sizeof(mp_int));
		if (mp_init(*cur_arg) != MP_OKAY) {
			dropbear_exit("Mem alloc error");
		}
		cur_arg = va_arg(args, mp_int**);
	}
	va_end(args);
}

void m_mp_free_multi(mp_int **mp, ...) 
{
	mp_int** cur_arg = mp;
	va_list args;

	va_start(args, mp);        /* init args to next argument from caller */
	while (cur_arg != NULL) {
		if (*cur_arg) {
			mp_clear(*cur_arg);
		}
		m_free(*cur_arg);
		cur_arg = va_arg(args, mp_int**);
	}
	va_end(args);
}

void bytes_to_mp(mp_int *mp, const unsigned char* bytes, unsigned int len) {

	if (mp_from_ubin(mp, (unsigned char*)bytes, len) != MP_OKAY) {
		dropbear_exit("Mem alloc error");
	}
}

/* hash the ssh representation of the mp_int mp */
void hash_process_mp(const struct ltc_hash_descriptor *hash_desc, 
				hash_state *hs, mp_int *mp) {
	buffer * buf;

	buf = buf_new(512 + 20); /* max buffer is a 4096 bit key, 
								plus header + some leeway*/
	buf_putmpint(buf, mp);
	hash_desc->process(hs, buf->data, buf->len);
	buf_free(buf);
}