view dbmulti.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 11f645c3715b
children 0dcc5b0d93fa
line wrap: on
line source

/*
 * Dropbear SSH
 * 
 * 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. */

#include "includes.h"

/* definitions are cleanest if we just put them here */
int dropbear_main(int argc, char ** argv);
int cli_main(int argc, char ** argv);
int dropbearkey_main(int argc, char ** argv);
int dropbearconvert_main(int argc, char ** argv);
int scp_main(int argc, char ** argv);

static int runprog(const char *progname, int argc, char ** argv, int *match) {
	*match = DROPBEAR_SUCCESS;

#ifdef DBMULTI_dropbear
		if (strcmp(progname, "dropbear") == 0) {
			return dropbear_main(argc, argv);
		}
#endif
#ifdef DBMULTI_dbclient
		if (strcmp(progname, "dbclient") == 0
				|| strcmp(progname, "ssh") == 0) {
			return cli_main(argc, argv);
		}
#endif
#ifdef DBMULTI_dropbearkey
		if (strcmp(progname, "dropbearkey") == 0) {
			return dropbearkey_main(argc, argv);
		}
#endif
#ifdef DBMULTI_dropbearconvert
		if (strcmp(progname, "dropbearconvert") == 0) {
			return dropbearconvert_main(argc, argv);
		}
#endif
#ifdef DBMULTI_scp
		if (strcmp(progname, "scp") == 0) {
			return scp_main(argc, argv);
		}
#endif
	*match = DROPBEAR_FAILURE;
	return 1;
}

int main(int argc, char ** argv) {
	int i;
	for (i = 0; i < 2; i++) {
		/* Try symlink first, then try as an argument eg "dropbearmulti dbclient host ..." */
		if (argc > i) {
			int match, res;
			/* figure which form we're being called as */
			const char* progname = basename(argv[i]);
			res = runprog(progname, argc-i, &argv[i], &match);
			if (match == DROPBEAR_SUCCESS) {
				return res;
			}
		}
	}

	fprintf(stderr, "Dropbear SSH multi-purpose v%s\n"
			"Make a symlink pointing at this binary with one of the\n"
			"following names or run 'dropbearmulti <command>'.\n"
#ifdef DBMULTI_dropbear
			"'dropbear' - the Dropbear server\n"
#endif
#ifdef DBMULTI_dbclient
			"'dbclient' or 'ssh' - the Dropbear client\n"
#endif
#ifdef DBMULTI_dropbearkey
			"'dropbearkey' - the key generator\n"
#endif
#ifdef DBMULTI_dropbearconvert
			"'dropbearconvert' - the key converter\n"
#endif
#ifdef DBMULTI_scp
			"'scp' - secure copy\n"
#endif
			,
			DROPBEAR_VERSION);
	exit(1);

}