MD_STD/MD_JAIL.php

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<?PHP
/**
* Provides class MD_JAIL.
*/
declare(strict_types = 1);
/**
* A class that, once initialized, forces the programmer to make security instructions implicit.
* If an object of the class has been created, not specifying security instructions
* leads to an error.
* A restriction on basic file operations is not practical in an md context because of
* the way transations are loaded through MDTlLoader.
*/
final class MD_JAIL {
const STATUS_NONE = 0;
const STATUS_STARTED = 1;
const STATUS_SPECIFIED = 2; // Determines that everything is fine.
/** @var integer */
private int $_status = self::STATUS_NONE;
/**
* @var integer
* Maximum execution time in seconds.
*/
public int $max_execution_time;
/**
* @var string[]
* Specifies which paths may be used by this script.
*/
private array $_open_basedir = [];
/**
* @var string
* Specifies the maximum RAM the script may use.
*/
public string $memory_limit;
/**
* Registers an additional accessible directory for open_basedir.
*
* @param string $dir Directory to register.
*
* @return void
*/
public function register_accessible_dir(string $dir):void {
$this->_open_basedir[] = $dir;
}
/**
* Applies the memory limit setting.
*
* @return void
*/
private function _apply_memory_limit():void {
if (!isset($this->memory_limit)) {
throw new MDJailSecurityOptionNotSetException("It has not been specified, which memory limit the script should hold. Set MD_JAIL->memory_limit = string.");
}
if (ini_set("memory_limit", $this->memory_limit) === false) {
throw new Exception('Failed to change memory_limit to ' . $this->memory_limit);
}
}
/**
* Applies the maximum execution time setting.
*
* @return void
*/
private function _apply_time_limit():void {
if (!isset($this->max_execution_time)) {
throw new MDJailSecurityOptionNotSetException("It has not been specified, which maximum execution time the script should hold. Set MD_JAIL->max_execution_time = integer.");
}
if (set_time_limit($this->max_execution_time) === false) {
throw new Exception('Failed to change max_execution_time to ' . $this->max_execution_time);
}
}
/**
* Applies basedir restrictions.
*
* @return void
*/
private function _apply_basedir_restriction():void {
if (empty($this->_open_basedir)) {
throw new MDJailSecurityOptionNotSetException("It has not been specified, which memory limit the script should hold. Set MD_JAIL->open_basedir = string.");
}
if (ini_set("open_basedir", implode(':', $this->_open_basedir)) === false) {
throw new Exception('Failed to set open_basedir restrictions');
}
}
/**
* Enforces security options previously set.
*
* @return void
*/
public function enforce():void {
2020-11-11 17:25:41 +01:00
// Special instructions on CLI, so as to not disturb PHPUnit
if (PHP_SAPI === 'cli') {
if (!isset($this->memory_limit)) {
throw new MDJailSecurityOptionNotSetException("It has not been specified, which memory limit the script should hold. Set MD_JAIL->memory_limit = string.");
}
if (!isset($this->max_execution_time)) {
throw new MDJailSecurityOptionNotSetException("It has not been specified, which maximum execution time the script should hold. Set MD_JAIL->max_execution_time = integer.");
}
$this->_status = self::STATUS_SPECIFIED;
$this->__destruct();
}
$this->_apply_memory_limit();
$this->_apply_time_limit();
// Set accessible file paths
// $this->_apply_basedir_restriction();
$this->_status = self::STATUS_SPECIFIED;
$this->__destruct();
}
/**
* Setup function. Registers a shutdown function that throws an error
* if the security specifications have not been made.
*
* @return void
*/
public function __construct() {
$this->_status = self::STATUS_STARTED;
}
public function __destruct() {
if ($this->_status !== self::STATUS_SPECIFIED) {
echo "Security specifications need to be set.";
if (!isset($this->memory_limit)) {
echo "Set memory limit";
}
if (!isset($this->max_execution_time)) {
echo "Set max_execution_time";
}
if (empty($this->_open_basedir)) {
echo "Set open_basedir";
}
throw new MDJailSecurityOptionNotSetException("Security specifications need to be set.");
}
}
}