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- <?php
- /* For licensing terms, see /license.txt */
- /**
- * This is the security library for Dokeos.
- *
- * This library is based on recommendations found in the PHP5 Certification
- * Guide published at PHP|Architect, and other recommendations found on
- * http://www.phpsec.org/
- * The principles here are that all data is tainted (most scripts of Dokeos are
- * open to the public or at least to a certain public that could be malicious
- * under specific circumstances). We use the white list approach, where as we
- * consider that data can only be used in the database or in a file if it has
- * been filtered.
- *
- * For session fixation, use ...
- * For session hijacking, use get_ua() and check_ua()
- * For Cross-Site Request Forgeries, use get_token() and check_tocken()
- * For basic filtering, use filter()
- * For files inclusions (using dynamic paths) use check_rel_path() and check_abs_path()
- *
- * @package dokeos.library
- * @author Yannick Warnier <ywarnier@beeznest.org>
- */
- /**
- * Security class
- *
- * Include/require it in your code and call Security::function()
- * to use its functionalities.
- *
- * This class can also be used as a container for filtered data, by creating
- * a new Security object and using $secure->filter($new_var,[more options])
- * and then using $secure->clean['var'] as a filtered equivalent, although
- * this is *not* mandatory at all.
- *
- * @author Yannick Warnier <yannick.warnier@dokeos.com>
- */
- class Security {
- public static $clean = array();
- /**
- * Checks if the absolute path (directory) given is really under the
- * checker path (directory)
- * @param string Absolute path to be checked (with trailing slash)
- * @param string Checker path under which the path should be (absolute path, with trailing slash, get it from api_get_path(SYS_COURSE_PATH))
- * @return bool True if the path is under the checker, false otherwise
- */
- public static function check_abs_path ($abs_path,$checker_path) {
- if (empty($checker_path)) {return false;} //checker path must be set
- $true_path=str_replace("\\", "/", realpath($abs_path));
- $found = strpos($true_path.'/',$checker_path);
- if ($found===0) {
- return true;
- }
- return false;
- }
- /**
- * Checks if the relative path (directory) given is really under the
- * checker path (directory)
- * @param string Relative path to be checked (relative to the current directory) (with trailing slash)
- * @param string Checker path under which the path should be (absolute path, with trailing slash, get it from api_get_path(SYS_COURSE_PATH))
- * @return bool True if the path is under the checker, false otherwise
- */
- public static function check_rel_path ($rel_path,$checker_path) {
- if (empty($checker_path)){return false;} //checker path must be set
- $current_path = getcwd(); //no trailing slash
- if (substr($rel_path,-1,1)!='/') {
- $rel_path = '/'.$rel_path;
- }
- $abs_path = $current_path.$rel_path;
- $true_path=str_replace("\\", "/", realpath($abs_path));
- $found = strpos($true_path.'/',$checker_path);
- if ($found===0) {
- return true;
- }
- return false;
- }
- /**
- * Filters dangerous filenames (*.php[.]?* and .htaccess) and returns it in
- * a non-executable form (for PHP and htaccess, this is still vulnerable to
- * other languages' files extensions)
- * @param string Unfiltered filename
- * @param string Filtered filename
- */
- public static function filter_filename ($filename) {
- require_once(api_get_path(LIBRARY_PATH).'fileUpload.lib.php');
- return disable_dangerous_file($filename);
- }
- /**
- * This function checks that the token generated in get_token() has been kept (prevents
- * Cross-Site Request Forgeries attacks)
- * @param string The array in which to get the token ('get' or 'post')
- * @return bool True if it's the right token, false otherwise
- */
- public static function check_token ($array='post') {
- switch ($array) {
- case 'get':
- if (isset($_SESSION['sec_token']) && isset($_GET['sec_token']) && $_SESSION['sec_token'] === $_GET['sec_token']) {
- return true;
- }
- return false;
- case 'post':
- if (isset($_SESSION['sec_token']) && isset($_POST['sec_token']) && $_SESSION['sec_token'] === $_POST['sec_token']) {
- return true;
- }
- return false;
- default:
- if (isset($_SESSION['sec_token']) && isset($array) && $_SESSION['sec_token'] === $array) {
- return true;
- }
- return false;
- }
- return false; //just in case, don't let anything slip
- }
- /**
- * Checks the user agent of the client as recorder by get_ua() to prevent
- * most session hijacking attacks.
- * @return bool True if the user agent is the same, false otherwise
- */
- public static function check_ua () {
- if (isset($_SESSION['sec_ua']) and $_SESSION['sec_ua'] === $_SERVER['HTTP_USER_AGENT'].$_SESSION['sec_ua_seed']) {
- return true;
- }
- return false;
- }
- /**
- * Clear the security token from the session
- * @return void
- */
- public static function clear_token () {
- $_SESSION['sec_token'] = null;
- unset($_SESSION['sec_token']);
- }
- /**
- * This function sets a random token to be included in a form as a hidden field
- * and saves it into the user's session. Returns an HTML form element
- * This later prevents Cross-Site Request Forgeries by checking that the user is really
- * the one that sent this form in knowingly (this form hasn't been generated from
- * another website visited by the user at the same time).
- * Check the token with check_token()
- * @return string Hidden-type input ready to insert into a form
- */
- public static function get_HTML_token () {
- $token = md5(uniqid(rand(),TRUE));
- $string = '<input type="hidden" name="sec_token" value="'.$token.'"/>';
- $_SESSION['sec_token'] = $token;
- return $string;
- }
- /**
- * This function sets a random token to be included in a form as a hidden field
- * and saves it into the user's session.
- * This later prevents Cross-Site Request Forgeries by checking that the user is really
- * the one that sent this form in knowingly (this form hasn't been generated from
- * another website visited by the user at the same time).
- * Check the token with check_token()
- * @return string Token
- */
- public static function get_token () {
- $token = md5(uniqid(rand(),TRUE));
- $_SESSION['sec_token'] = $token;
- return $token;
- }
- /**
- * Gets the user agent in the session to later check it with check_ua() to prevent
- * most cases of session hijacking.
- * @return void
- */
- public static function get_ua () {
- $_SESSION['sec_ua_seed'] = uniqid(rand(),TRUE);
- $_SESSION['sec_ua'] = $_SERVER['HTTP_USER_AGENT'].$_SESSION['sec_ua_seed'];
- }
- /**
- * This function filters a variable to the type given, with the options given
- * @param mixed The variable to be filtered
- * @param string The type of variable we expect (bool,int,float,string)
- * @param array Additional options
- * @return bool True if variable was filtered and added to the current object, false otherwise
- */
- public static function filter ($var,$type='string',$options=array()) {
- //This function is not finished! Do not use!
- $result = false;
- //get variable name and value
- $args = func_get_args();
- $names =array_keys($args);
- $name = $names[0];
- $value = $args[$name];
- switch ($type) {
- case 'bool':
- $result = (bool) $var;
- break;
- case 'int':
- $result = (int) $var;
- break;
- case 'float':
- $result = (float) $var;
- break;
- case 'string/html':
- $result = self::remove_XSS($var);
- break;
- case 'string/db':
- $result = Database::escape_string($var);
- break;
- case 'array':
- //an array variable shouldn't be given to the filter
- return false;
- default:
- return false;
- }
- if (!empty($option['save'])) {
- $this->clean[$name]=$result;
- }
- return $result;
- }
- /**
- * This function returns a variable from the clean array. If the variable doesn't exist,
- * it returns null
- * @param string Variable name
- * @return mixed Variable or NULL on error
- */
- public static function get ($varname) {
- if (isset(self::$clean[$varname])) {
- return self::$clean[$varname];
- }
- return NULL;
- }
- /**
- * This function tackles the XSS injections.
- * Filtering for XSS is very easily done by using the htmlentities() function.
- * This kind of filtering prevents JavaScript snippets to be understood as such.
- * @param mixed The variable to filter for XSS, this params can be a string or an array (example : array(x,y))
- * @param integer The user status,constant allowed(STUDENT,COURSEMANAGER,ANONYMOUS,COURSEMANAGERLOWSECURITY)
- * @return mixed Filtered string or array
- */
- public static function remove_XSS ($var,$user_status=ANONYMOUS) {
- $purifier = new HTMLPurifier(null,$user_status);
- if (is_array($var)) {
- return $purifier->purifyArray($var);
- } else {
- return $purifier->purify($var);
- }
- }
- }
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