#!/usr/local/bin/php-cgi -f
<?php
/*
	sshd - Modified to work on disk based system
	Copyright 2004 Scott K Ullrich

	Original Copyright (C) 2004 Fred Mol <fredmol@xs4all.nl>.
	All rights reserved.

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions are met:

	1. Redistributions of source code must retain the above copyright notice,
	   this list of conditions and the following disclaimer.

	2. Redistributions in binary form must reproduce the above copyright
	   notice, this list of conditions and the following disclaimer in the
	   documentation and/or other materials provided with the distribution.

	THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
	INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
	AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
	AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
	OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	POSSIBILITY OF SUCH DAMAGE.
*/

	require_once("globals.inc");
	require_once("config.inc");
	require_once("functions.inc");
	require_once("shaper.inc");

	if (!isset($config['system']['enablesshd'])) {
		return;
	}

	/* are we already running?  if not, do conf_mount_rw(), otherwise it should already be rw */
	if (!is_subsystem_dirty('sshdkeys')) {
		conf_mount_rw();
	}

	$sshConfigDir = "/etc/ssh";

	$keys = array(
		array('type' => 'rsa',     'suffix' => 'rsa_'),
		array('type' => 'ed25519', 'suffix' => 'ed25519_')
	);

	$keyfiles = array();
	foreach ($keys as $key) {
		$keyfiles[] = "ssh_host_{$key['suffix']}key";
		$keyfiles[] = "ssh_host_{$key['suffix']}key.pub";
	}

	/* restore ssh data for nanobsd platform */
	if ($g['platform'] == "nanobsd" and file_exists("/conf/sshd/ssh_host_key") and !file_exists("{$sshConfigDir}/ssh_host_key.pub")) {
		echo "Restoring SSH from /conf/sshd/";
		exec("/bin/cp -p /conf/sshd/* {$sshConfigDir}/");

		/* make sure host private key permissions aren't too open so sshd won't complain */
		foreach ($keyfiles as $f2c) {
			if (file_exists("{$sshConfigDir}/{$f2c}")) {
				chmod("{$sshConfigDir}/{$f2c}", 0600);
			}
		}
	}

	/*    if any of these files are 0 bytes then they are corrupted.
	 *    remove them
	 */
	foreach ($keyfiles as $f2c) {
		if (!file_exists("{$sshConfigDir}/{$f2c}") || filesize("{$sshConfigDir}/{$f2c}") == 0) {
			/* Make sure we remove both files */
			unlink_if_exists($sshConfigDir . '/' . basename($f2c, ".pub"));
			unlink_if_exists($sshConfigDir . '/' . $f2c);
		}
	}

	if (!is_dir("/var/empty")) {
		/* make ssh home directory */
		mkdir("/var/empty", 0555);
	}

	if (!file_exists("/var/log/lastlog")) {
		/* Login related files. */
		@touch("/var/log/lastlog");
	}

	if (is_array($config['system']['ssh']) && !empty($config['system']['ssh']['port'])) {
		$sshport = $config['system']['ssh']['port'];
	} else {
		$sshport = 22;
	}

	/* Include default configuration for pfSense */
	/* Taken from https://stribika.github.io/2015/01/04/secure-secure-shell.html */
	$sshconf = "# This file is automatically generated at startup\n";
	$sshconf .= "KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256\n";
	/* Run the server on another port if we have one defined */
	$sshconf .= "Port $sshport\n";
	/* Only allow protocol 2, because we say so */
	$sshconf .= "Protocol 2\n";
	foreach ($keys as $key) {
		$sshconf .= "HostKey {$sshConfigDir}/ssh_host_{$key['suffix']}key\n";
	}
	$sshconf .= "Compression yes\n";
	$sshconf .= "ClientAliveInterval 30\n";
	$sshconf .= "PermitRootLogin yes\n";
	if (isset($config['system']['ssh']['sshdkeyonly'])) {
		$sshconf .= "# Login via Key only\n";
		$sshconf .= "ChallengeResponseAuthentication no\n";
		$sshconf .= "PasswordAuthentication no\n";
		$sshconf .= "PubkeyAuthentication yes\n";
	} else {
		$sshconf .= "# Login via Key and Password\n";
		$sshconf .= "ChallengeResponseAuthentication yes\n";
		$sshconf .= "PasswordAuthentication yes\n";
		$sshconf .= "PubkeyAuthentication yes\n";
	}
	$sshconf .= "UseDNS no\n";
	$sshconf .= "UsePAM no\n";
	$sshconf .= "LoginGraceTime 30s\n";
	/* Hide FreeBSD version */
	$sshconf .= "VersionAddendum none\n";
	$sshconf .= "X11Forwarding no\n";
	$sshconf .= "Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr\n";
	$sshconf .= "MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-ripemd160-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160,umac-128@openssh.com\n";
	$sshconf .= "# override default of no subsystems\n";
	$sshconf .= "Subsystem\tsftp\t/usr/libexec/sftp-server\n";

	/* Apply package SSHDCond settings if config file exists */
	if (file_exists("/etc/sshd_extra")) {
		$fdExtra = fopen("/etc/sshd_extra", 'r');
		$szExtra = fread($fdExtra, 1048576); // Read up to 1MB from extra file
		$sshconf .= $szExtra;
		fclose($fdExtra);
	}

	/* Write the new sshd config file */
	@file_put_contents("{$sshConfigDir}/sshd_config", $sshconf);

	/* mop up from a badly implemented ssh keys -> cf backup */
	if ($config['ssh']['dsa_key'] <> "") {
		unset($config['ssh']['dsa_key']);
		unset($config['ssh']['ecdsa_key']);
		unset($config['ssh']['ed25519_key']);
		unset($config['ssh']['rsa_key']);
		unset($config['ssh']['rsa1_key']);
		unset($config['ssh']['dsa']);
		unset($config['ssh']['rsa']);
		unset($config['ssh']['rsa1']);
		unset($config['ssh']['ak']);
		write_config("Clearing SSH keys from config.xml");
	}

	/* are we already running?  if so exit */
	if (is_subsystem_dirty('sshdkeys')) {
		unset($keys, $keyfiles);
		return;
	}

	// Check for all needed key files. If any are missing, the keys need to be regenerated.
	$generate_keys = array();
	foreach ($keys as $key) {
		if (!file_exists("{$sshConfigDir}/ssh_host_{$key['suffix']}key") ||
		    !file_exists("{$sshConfigDir}/ssh_host_{$key['suffix']}key.pub")) {
			$generate_keys[] = $key;
		}
	}

	if (!empty($generate_keys)) {
		/* remove previous keys and regen later */
		file_notice("SSH", "{$g['product_name']} has started creating missing SSH keys.  SSH Startup will be delayed.  Please note that reloading the filter rules and changes will be delayed until this operation is completed.", "SSH KeyGen", "");
		mark_subsystem_dirty('sshdkeys');
		echo " Generating Keys:\n";
		foreach ($generate_keys as $key) {
			$_gb = exec("/usr/bin/nice -n20 /usr/bin/ssh-keygen -t {$key['type']} -b 4096 -N '' -f {$sshConfigDir}/ssh_host_{$key['suffix']}key");
		}
		clear_subsystem_dirty('sshdkeys');
		file_notice("SSH", "{$g['product_name']} has completed creating your SSH keys.  SSH is now started.", "SSH Startup", "");
	}

	/* kill existing sshd process, server only, not the childs */
	$sshd_pid = exec("ps ax | egrep '/usr/sbin/[s]shd' | awk '{print $1}'");
	if ($sshd_pid <> "") {
		echo "stopping ssh process $sshd_pid \n";
		@posix_kill($sshd_pid, SIGTERM);
	}
	/* Launch new server process */
	$status = mwexec("/usr/sbin/sshd");
	if ($status <> 0) {
		file_notice("sshd_startup", "SSHD failed to start.", "SSHD Daemon", "");
		echo "error!\n";
	} else {
		echo "done.\n";
	}

	// NanoBSD
	if ($g['platform'] == "nanobsd") {
		if (!is_dir("/conf/sshd")) {
			mkdir("/conf/sshd", 0750);
		}
		$_gb = exec("/bin/cp -p {$sshConfigDir}/ssh_host* /conf/sshd");
	}
	conf_mount_ro();
	unset($keys, $keyfiles);
?>
