view chansession.h @ 1790:42745af83b7d

Introduce extra delay before closing unauthenticated sessions To make it harder for attackers, introduce a delay to keep an unauthenticated session open a bit longer, thus blocking a connection slot until after the delay. Without this, while there is a limit on the amount of attempts an attacker can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to handle one attempt is still short and thus for each of the allowed parallel attempts many attempts can be chained one after the other. The attempt rate is then: "MAX_UNAUTH_PER_IP / <process time of one attempt>". With the delay, this rate becomes: "MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
date Wed, 15 Feb 2017 13:53:04 +0100
parents 8a7d26e86a56
children
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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. */

#ifndef DROPBEAR_CHANSESSION_H_
#define DROPBEAR_CHANSESSION_H_

#include "loginrec.h"
#include "channel.h"
#include "listener.h"

struct exitinfo {

	int exitpid; /* -1 if not exited */
	int exitstatus;
	int exitsignal;
	int exitcore;
};

struct ChanSess {

	char * cmd; /* command to exec */
	pid_t pid; /* child process pid */
	/* command that was sent by the client, if authorized_keys command= or
	dropbear -c was used */
	char *original_command;

	/* pty details */
	int master; /* the master terminal fd*/
	int slave;
	char * tty;
	char * term;

	/* exit details */
	struct exitinfo exit;


	/* These are only set temporarily before forking */
	/* Used to set $SSH_CONNECTION in the child session.  */
	char *connection_string;
	/* Used to set $SSH_CLIENT in the child session. */
	char *client_string;
	
#if DROPBEAR_X11FWD
	struct Listener * x11listener;
	int x11port;
	char * x11authprot;
	char * x11authcookie;
	unsigned int x11screennum;
	unsigned char x11singleconn;
#endif

#if DROPBEAR_SVR_AGENTFWD
	struct Listener * agentlistener;
	char * agentfile;
	char * agentdir;
#endif
};

struct ChildPid {
	pid_t pid;
	struct ChanSess * chansess;
};


void addnewvar(const char* param, const char* var);

void cli_send_chansess_request(void);
void cli_tty_cleanup(void);
void cli_chansess_winchange(void);
#if DROPBEAR_CLI_NETCAT
void cli_send_netcat_request(void);
#endif

void svr_chansessinitialise(void);
void svr_chansess_checksignal(void);
extern const struct ChanType svrchansess;

struct SigMap {
	int signal;
	char* name;
};

extern const struct SigMap signames[];

#endif /* DROPBEAR_CHANSESSION_H_ */