<?php

/**

 * Smarty plugin

 *

 * @package    Smarty

 * @subpackage Security

 * @author     Uwe Tews

 */

/*

 * FIXME: Smarty_Security API

 *      - getter and setter instead of public properties would allow cultivating an internal cache properly

 *      - current implementation of isTrustedResourceDir() assumes that Smarty::$template_dir and Smarty::$config_dir are immutable

 *        the cache is killed every time either of the variables change. That means that two distinct Smarty objects with differing

 *        $template_dir or $config_dir should NOT share the same Smarty_Security instance,

 *        as this would lead to (severe) performance penalty! how should this be handled?

 */

/**

 * This class does contain the security settings

 */

class Smarty_Security {

    /**

     * This determines how Smarty handles "<?php ... ?>" tags in templates.

     * possible values:

     * <ul>

     *   <li>Smarty::PHP_PASSTHRU -> echo PHP tags as they are</li>

     *   <li>Smarty::PHP_QUOTE    -> escape tags as entities</li>

     *   <li>Smarty::PHP_REMOVE   -> remove php tags</li>

     *   <li>Smarty::PHP_ALLOW    -> execute php tags</li>

     * </ul>

     *

     * @var integer

     */

    public $php_handling = Smarty::PHP_PASSTHRU;

    /**

     * This is the list of template directories that are considered secure.

     * $template_dir is in this list implicitly.

     *

     * @var array

     */

    public $secure_dir = array();

    /**

     * This is an array of directories where trusted php scripts reside.

     * {@link $security} is disabled during their inclusion/execution.

     *

     * @var array

     */

    public $trusted_dir = array();

    /**

     * List of regular expressions (PCRE) that include trusted URIs

     *

     * @var array

     */

    public $trusted_uri = array();

    /**

     * List of trusted constants names

     *

     * @var array

     */

    public $trusted_constants = array();

    /**

     * This is an array of trusted static classes.

     * If empty access to all static classes is allowed.

     * If set to 'none' none is allowed.

     *

     * @var array

     */

    public $static_classes = array();

    /**

     * This is an nested array of trusted classes and static methods.

     * If empty access to all static classes and methods is allowed.

     * Format:

     * array (

     *         'class_1' => array('method_1', 'method_2'), // allowed methods listed

     *         'class_2' => array(),                       // all methods of class allowed

     *       )

     * If set to null none is allowed.

     *

     * @var array

     */

    public $trusted_static_methods = array();

    /**

     * This is an array of trusted static properties.

     * If empty access to all static classes and properties is allowed.

     * Format:

     * array (

     *         'class_1' => array('prop_1', 'prop_2'), // allowed properties listed

     *         'class_2' => array(),                   // all properties of class allowed

     *       )

     * If set to null none is allowed.

     *

     * @var array

     */

    public $trusted_static_properties = array();

    /**

     * This is an array of trusted PHP functions.

     * If empty all functions are allowed.

     * To disable all PHP functions set $php_functions = null.

     *

     * @var array

     */

    public $php_functions = array(

        'isset', 'empty',

        'count', 'sizeof',

        'in_array', 'is_array',

        'time',

    );

    /**

     * This is an array of trusted PHP modifiers.

     * If empty all modifiers are allowed.

     * To disable all modifier set $php_modifiers = null.

     *

     * @var array

     */

    public $php_modifiers = array(

        'escape',

        'count',

        'nl2br',

    );

    /**

     * This is an array of allowed tags.

     * If empty no restriction by allowed_tags.

     *

     * @var array

     */

    public $allowed_tags = array();

    /**

     * This is an array of disabled tags.

     * If empty no restriction by disabled_tags.

     *

     * @var array

     */

    public $disabled_tags = array();

    /**

     * This is an array of allowed modifier plugins.

     * If empty no restriction by allowed_modifiers.

     *

     * @var array

     */

    public $allowed_modifiers = array();

    /**

     * This is an array of disabled modifier plugins.

     * If empty no restriction by disabled_modifiers.

     *

     * @var array

     */

    public $disabled_modifiers = array();

    /**

     * This is an array of disabled special $smarty variables.

     *

     * @var array

     */

    public $disabled_special_smarty_vars = array();

    /**

     * This is an array of trusted streams.

     * If empty all streams are allowed.

     * To disable all streams set $streams = null.

     *

     * @var array

     */

    public $streams = array('file');

    /**

     * + flag if constants can be accessed from template

     *

     * @var boolean

     */

    public $allow_constants = true;

    /**

     * + flag if super globals can be accessed from template

     *

     * @var boolean

     */

    public $allow_super_globals = true;

    /**

     * max template nesting level

     *

     * @var int

     */

    public $max_template_nesting = 0;

    /**

     * current template nesting level

     *

     * @var int

     */

    private $_current_template_nesting = 0;

    /**

     * Cache for $resource_dir lookup

     *

     * @var array

     */

    protected $_resource_dir = null;

    /**

     * Cache for $template_dir lookup

     *

     * @var array

     */

    protected $_template_dir = null;

    /**

     * Cache for $config_dir lookup

     *

     * @var array

     */

    protected $_config_dir = null;

    /**

     * Cache for $secure_dir lookup

     *

     * @var array

     */

    protected $_secure_dir = null;

    /**

     * Cache for $php_resource_dir lookup

     *

     * @var array

     */

    protected $_php_resource_dir = null;

    /**

     * Cache for $trusted_dir lookup

     *

     * @var array

     */

    protected $_trusted_dir = null;

    /**

     * @param Smarty $smarty

     */

    public function __construct($smarty) {

        $this->smarty = $smarty;

    }

    /**

     * Check if PHP function is trusted.

     *

     * @param  string $function_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if function is trusted

     * @throws SmartyCompilerException if php function is not trusted

     */

    public function isTrustedPhpFunction($function_name, $compiler) {

        if (isset($this->php_functions) && (empty($this->php_functions) || in_array($function_name, $this->php_functions))) {

            return true;

        }

        $compiler->trigger_template_error("PHP function '{$function_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if static class is trusted.

     *

     * @param  string $class_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if class is trusted

     * @throws SmartyCompilerException if static class is not trusted

     */

    public function isTrustedStaticClass($class_name, $compiler) {

        if (isset($this->static_classes) && (empty($this->static_classes) || in_array($class_name, $this->static_classes))) {

            return true;

        }

        $compiler->trigger_template_error("access to static class '{$class_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if static class method/property is trusted.

     *

     * @param  string $class_name

     * @param  string $params

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if class method is trusted

     * @throws SmartyCompilerException if static class method is not trusted

     */

    public function isTrustedStaticClassAccess($class_name, $params, $compiler) {

        if (!isset($params[2])) {

            // fall back

            return $this->isTrustedStaticClass($class_name, $compiler);

        }

        if ($params[2] == 'method') {

            $allowed = $this->trusted_static_methods;

            $name = substr($params[0], 0, strpos($params[0], '('));

        } else {

            $allowed = $this->trusted_static_properties;

            // strip '$'

            $name = substr($params[0], 1);

        }

        if (isset($allowed)) {

            if (empty($allowed)) {

                // fall back

                return $this->isTrustedStaticClass($class_name, $compiler);

            }

            if (isset($allowed[$class_name])

                && (empty($allowed[$class_name])

                    || in_array($name, $allowed[$class_name]))

            ) {

                return true;

            }

        }

        $compiler->trigger_template_error("access to static class '{$class_name}' {$params[2]} '{$name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if PHP modifier is trusted.

     *

     * @param  string $modifier_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if modifier is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedPhpModifier($modifier_name, $compiler) {

        if (isset($this->php_modifiers) && (empty($this->php_modifiers) || in_array($modifier_name, $this->php_modifiers))) {

            return true;

        }

        $compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting");

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if tag is trusted.

     *

     * @param  string $tag_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if tag is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedTag($tag_name, $compiler) {

        // check for internal always required tags

        if (in_array($tag_name, array('assign', 'call', 'private_filter', 'private_block_plugin', 'private_function_plugin', 'private_object_block_function',

            'private_object_function', 'private_registered_function', 'private_registered_block', 'private_special_variable', 'private_print_expression', 'private_modifier'))

        ) {

            return true;

        }

        // check security settings

        if (empty($this->allowed_tags)) {

            if (empty($this->disabled_tags) || !in_array($tag_name, $this->disabled_tags)) {

                return true;

            } else {

                $compiler->trigger_template_error("tag '{$tag_name}' disabled by security setting", $compiler->lex->taglineno);

            }

        } elseif (in_array($tag_name, $this->allowed_tags) && !in_array($tag_name, $this->disabled_tags)) {

            return true;

        } else {

            $compiler->trigger_template_error("tag '{$tag_name}' not allowed by security setting", $compiler->lex->taglineno);

        }

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if special $smarty variable is trusted.

     *

     * @param  string $var_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if tag is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedSpecialSmartyVar($var_name, $compiler) {

        if (!in_array($var_name, $this->disabled_special_smarty_vars)) {

            return true;

        } else {

            $compiler->trigger_template_error("special variable '\$smarty.{$var_name}' not allowed by security setting", $compiler->lex->taglineno);

        }

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if modifier plugin is trusted.

     *

     * @param  string $modifier_name

     * @param  object $compiler compiler object

     *

     * @return boolean                 true if tag is trusted

     * @throws SmartyCompilerException if modifier is not trusted

     */

    public function isTrustedModifier($modifier_name, $compiler) {

        // check for internal always allowed modifier

        if (in_array($modifier_name, array('default'))) {

            return true;

        }

        // check security settings

        if (empty($this->allowed_modifiers)) {

            if (empty($this->disabled_modifiers) || !in_array($modifier_name, $this->disabled_modifiers)) {

                return true;

            } else {

                $compiler->trigger_template_error("modifier '{$modifier_name}' disabled by security setting", $compiler->lex->taglineno);

            }

        } elseif (in_array($modifier_name, $this->allowed_modifiers) && !in_array($modifier_name, $this->disabled_modifiers)) {

            return true;

        } else {

            $compiler->trigger_template_error("modifier '{$modifier_name}' not allowed by security setting", $compiler->lex->taglineno);

        }

        return false; // should not, but who knows what happens to the compiler in the future?

    }

    /**

     * Check if constants are enabled or trusted

     *

     * @param  string $const contant name

     * @param  object $compiler compiler object

     *

     * @return bool

     */

    public function isTrustedConstant($const, $compiler) {

        if (in_array($const, array('true', 'false', 'null'))) {

            return true;

        }

        if (!empty($this->trusted_constants)) {

            if (!in_array($const, $this->trusted_constants)) {

                $compiler->trigger_template_error("Security: access to constant '{$const}' not permitted");

                return false;

            }

            return true;

        }

        if ($this->allow_constants) {

            return true;

        }

        $compiler->trigger_template_error("Security: access to constants not permitted");

        return false;

    }

    /**

     * Check if stream is trusted.

     *

     * @param  string $stream_name

     *

     * @return boolean         true if stream is trusted

     * @throws SmartyException if stream is not trusted

     */

    public function isTrustedStream($stream_name) {

        if (isset($this->streams) && (empty($this->streams) || in_array($stream_name, $this->streams))) {

            return true;

        }

        throw new SmartyException("stream '{$stream_name}' not allowed by security setting");

    }

    /**

     * Check if directory of file resource is trusted.

     *

     * @param  string $filepath

     *

     * @return boolean         true if directory is trusted

     * @throws SmartyException if directory is not trusted

     */

    public function isTrustedResourceDir($filepath) {

        $_template = false;

        $_config = false;

        $_secure = false;

        $_template_dir = $this->smarty->getTemplateDir();

        $_config_dir = $this->smarty->getConfigDir();

        // check if index is outdated

        if ((!$this->_template_dir || $this->_template_dir !== $_template_dir)

            || (!$this->_config_dir || $this->_config_dir !== $_config_dir)

            || (!empty($this->secure_dir) && (!$this->_secure_dir || $this->_secure_dir !== $this->secure_dir))

        ) {

            $this->_resource_dir = array();

            $_template = true;

            $_config = true;

            $_secure = !empty($this->secure_dir);

        }

        // rebuild template dir index

        if ($_template) {

            $this->_template_dir = $_template_dir;

            foreach ($_template_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        // rebuild config dir index

        if ($_config) {

            $this->_config_dir = $_config_dir;

            foreach ($_config_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        // rebuild secure dir index

        if ($_secure) {

            $this->_secure_dir = $this->secure_dir;

            foreach ((array)$this->secure_dir as $directory) {

                $directory = realpath($directory);

                $this->_resource_dir[$directory] = true;

            }

        }

        $_filepath = realpath($filepath);

        $directory = dirname($_filepath);

        $_directory = array();

        while (true) {

            // remember the directory to add it to _resource_dir in case we're successful

            $_directory[$directory] = true;

            // test if the directory is trusted

            if (isset($this->_resource_dir[$directory])) {

                // merge sub directories of current $directory into _resource_dir to speed up subsequent lookup

                $this->_resource_dir = array_merge($this->_resource_dir, $_directory);

                return true;

            }

            // abort if we've reached root

            if (($pos = strrpos($directory, DS)) === false || !isset($directory[1])) {

                break;

            }

            // bubble up one level

            $directory = substr($directory, 0, $pos);

        }

        // give up

        throw new SmartyException("directory '{$_filepath}' not allowed by security setting");

    }