Core File (Security class) Security. php

The CI security class provides global protection against CSRF attacks and XSS attacks. you only need to enable it in the configuration file: $ config ['csrf _ protection '] = TRUE; $ config ['global _ xss_fi

The CI security class provides global protection against CSRF attacks and XSS attacks. you only need to enable it in the configuration file:
$ Config ['csrf _ protection '] = TRUE;
$ Config ['global _ xss_filtering '] = TRUE;
And provides practical methods:
$ This-> security-> xss_clean ($ data); // The second parameter is TRUE to verify Image security.
$ This-> security-> sanitize_filename () // filter file names
CI also provides security functions:
Xss_clean () // xss filter
Sanitize_filename () // purify the file name
Do_hash () // md5 or sha encryption
Strip_image_tags () // remove unnecessary characters from the image tag
Encode_php_tags () // forcibly convert the PHP script tag to an object

 '[Removed]', 'document. write '=>' [removed] ','. parentNode '=>' [removed] ','. innerHTML '=>' [removed] ', 'window. location '=>' [removed] ','-moz-binding '=>' [removed] ','
 '=>' --> ',''=> '<![CDATA[','<comment>'=> '<comment>');//不允许出现的正则表达式数组protected $_never_allowed_regex = array('javascript\s*:','expression\s*(\(|&\#40;)', // CSS and IE'vbscript\s*:', // IE, surprise!'Redirect\s+302',"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?");//构造函数public function __construct(){// CSRF保护是否开启if (config_item('csrf_protection') === TRUE){// CSRF配置foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key){if (FALSE !== ($val = config_item($key))){$this->{'_'.$key} = $val;}}// _csrf_cookie_name加上cookie前缀if (config_item('cookie_prefix')){$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;}// 设置csrf的hash值$this->_csrf_set_hash();}log_message('debug', "Security Class Initialized");}// --------------------------------------------------------------------/** * Verify Cross Site Request Forgery Protection * * @returnobject */public function csrf_verify(){// 如果不是post请求，则设置csrf的cookie值if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST'){return $this->csrf_set_cookie();}// Do the tokens exist in both the _POST and _COOKIE arrays?if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name])){$this->csrf_show_error();}// token匹配吗if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name]){$this->csrf_show_error();}// We kill this since we're done and we don't want to// polute the _POST arrayunset($_POST[$this->_csrf_token_name]);// Nothing should last foreverunset($_COOKIE[$this->_csrf_cookie_name]);$this->_csrf_set_hash();$this->csrf_set_cookie();log_message('debug', 'CSRF token verified');return $this;}// --------------------------------------------------------------------/** * 设置csrf的cookie值 */public function csrf_set_cookie(){$expire = time() + $this->_csrf_expire;$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off')){return FALSE;}setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);log_message('debug', "CRSF cookie Set");return $this;}//csrf保存public function csrf_show_error(){show_error('The action you have requested is not allowed.');}//获取csrf的hash值public function get_csrf_hash(){return $this->_csrf_hash;}//获取csrf的token值public function get_csrf_token_name(){return $this->_csrf_token_name;}/** * XSS 过滤 */public function xss_clean($str, $is_image = FALSE){//是否是数组if (is_array($str)){while (list($key) = each($str)){$str[$key] = $this->xss_clean($str[$key]);}return $str;}//去掉可见字符串$str = remove_invisible_characters($str);// 验证实体url$str = $this->_validate_entities($str);/* * URL 解码 * * Just in case stuff like this is submitted: * * Google * * Note: Use rawurldecode() so it does not remove plus signs * */$str = rawurldecode($str);/* * Convert character entities to ASCII * * This permits our tests below to work reliably. * We only convert entities that are within tags since * these are the ones that will pose security problems. * */$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);/* * Remove Invisible Characters Again! */$str = remove_invisible_characters($str);/* * Convert all tabs to spaces * * This prevents strings like this: javascript * NOTE: we deal with spaces between characters later. * NOTE: preg_replace was found to be amazingly slow here on * large blocks of data, so we use str_replace. */if (strpos($str, "\t") !== FALSE){$str = str_replace("\t", ' ', $str);}/* * Capture converted string for later comparison */$converted_string = $str;// Remove Strings that are never allowed$str = $this->_do_never_allowed($str);/* * Makes PHP tags safe * * Note: XML tags are inadvertently replaced too: * * <?xml * * But it doesn't seem to pose a problem. */if ($is_image === TRUE){// Images have a tendency to have the PHP short opening and// closing tags every so often so we skip those and only// do the long opening tags.$str = preg_replace('/<\?(php)/i', "<?\\1", $str);}else{$str = str_replace(array('<?', '?'.'>'),  array('<?', '?>'), $str);}/* * Compact any exploded words * * This corrects words like:  j a v a s c r i p t * These words are compacted back to their correct state. */$words = array('javascript', 'expression', 'vbscript', 'script', 'base64','applet', 'alert', 'document', 'write', 'cookie', 'window');foreach ($words as $word){$temp = '';for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++){$temp .= substr($word, $i, 1)."\s*";}// We only want to do this when it is followed by a non-word character// That way valid stuff like "dealer to" does not become "dealerto"$str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);}/* * Remove disallowed Javascript in links or img tags * We used to do some version comparisons and use of stripos for PHP5, * but it is dog slow compared to these simplified non-capturing * preg_match(), especially if the pattern exists in the string */do{$original = $str;if (preg_match("/]*?)(>|$)#si", array($this, '_js_link_removal'), $str);}if (preg_match("/]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);}if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str)){$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);}}while($original != $str);unset($original);// Remove evil attributes such as style, onclick and xmlns$str = $this->_remove_evil_attributes($str, $is_image);/* * Sanitize naughty HTML elements * * If a tag containing any of the words in the list * below is found, the tag gets converted to entities. * * So this: <blink> * Becomes: <blink> */$naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';$str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is', array($this, '_sanitize_naughty_html'), $str);/* * Sanitize naughty scripting elements * * Similar to above, only instead of looking for * tags it looks for PHP and JavaScript commands * that are disallowed.  Rather than removing the * code, it simply converts the parenthesis to entities * rendering the code un-executable. * * For example:eval('some code') * Becomes:eval('some code') */$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);// Final clean up// This adds a bit of extra precaution in case// something got through the above filters$str = $this->_do_never_allowed($str);/* * Images are Handled in a Special Way * - Essentially, we want to know that after all of the character * conversion is done whether any unwanted, likely XSS, code was found. * If not, we return TRUE, as the image is clean. * However, if the string post-conversion does not matched the * string post-removal of XSS, then it fails, as there was unwanted XSS * code found and removed/changed during processing. */if ($is_image === TRUE){return ($str == $converted_string) ? TRUE: FALSE;}log_message('debug', "XSS Filtering completed");return $str;}// --------------------------------------------------------------------//保护url的随机hash值public function xss_hash(){if ($this->_xss_hash == ''){mt_srand();$this->_xss_hash = md5(time() + mt_rand(0, 1999999999));}return $this->_xss_hash;}// --------------------------------------------------------------------/** * html实体转码 */public function entity_decode($str, $charset='UTF-8'){if (stristr($str, '&') === FALSE){return $str;}$str = html_entity_decode($str, ENT_COMPAT, $charset);$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);}// --------------------------------------------------------------------//过滤文件名，保证文件名安全public function sanitize_filename($str, $relative_path = FALSE){$bad = array("../","<!--","-->","<",">","'",'"','&','$','#','{','}','[',']','=',';','?',"%20","%22","%3c",// <"%253c",// <"%3e",// >"%0e",// >"%28",// ("%29",// )"%2528",// ("%26",// &"%24",// $"%3f",// ?"%3b",// ;"%3d"// =);if ( ! $relative_path){$bad[] = './';$bad[] = '/';}$str = remove_invisible_characters($str, FALSE);return stripslashes(str_replace($bad, '', $str));}//压缩单词如j a v a s c r i p t成javascriptprotected function _compact_exploded_words($matches){return preg_replace('/\s+/s', '', $matches[1]).$matches[2];}// --------------------------------------------------------------------/* * 去掉一些危害的html属性 */protected function _remove_evil_attributes($str, $is_image){// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');if ($is_image === TRUE){/* * Adobe Photoshop puts XML metadata into JFIF images,  * including namespacing, so we have to allow this for images. */unset($evil_attributes[array_search('xmlns', $evil_attributes)]);}do {$count = 0;$attribs = array();// find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], '/');}// find occurrences of illegal attribute strings without quotespreg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], '/');}// replace illegal attribute strings that are inside an html tagif (count($attribs) > 0){$str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);}} while ($count);return $str;}// --------------------------------------------------------------------/** * 净化html,补齐未关闭的标签 */protected function _sanitize_naughty_html($matches){// encode opening brace$str = '<'.$matches[1].$matches[2].$matches[3];// encode captured opening or closing brace to prevent recursive vectors$str .= str_replace(array('>', '<'), array('>', '<'),$matches[4]);return $str;}// --------------------------------------------------------------------/** * 过滤超链接中js */protected function _js_link_removal($match){return str_replace($match[1],preg_replace('#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si','',$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))),$match[0]);}// --------------------------------------------------------------------/** * 过滤图片链接中的js */protected function _js_img_removal($match){return str_replace($match[1],preg_replace('#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si','',$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))),$match[0]);}// --------------------------------------------------------------------/** * 转换属性，将一些字符转换成实体 */protected function _convert_attribute($match){return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);}// --------------------------------------------------------------------//过滤html标签属性protected function _filter_attributes($str){$out = '';if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches)){foreach ($matches[0] as $match){$out .= preg_replace("#/\*.*?\*/#s", '', $match);}}return $out;}// --------------------------------------------------------------------//html实体转码protected function _decode_entity($match){return $this->entity_decode($match[0], strtoupper(config_item('charset')));}// --------------------------------------------------------------------/** * 验证url实体 */protected function _validate_entities($str){/* * Protect GET variables in URLs */ // 901119URL5918AMP18930PROTECT8198$str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash()."\\1=\\2", $str);/* * Validate standard character entities * * Add a semicolon if missing.  We do this to enable * the conversion of entities to ASCII later. * */$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);/* * Validate UTF16 two byte encoding (x00) * * Just as above, adds a semicolon if missing. * */$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);/* * Un-Protect GET variables in URLs */$str = str_replace($this->xss_hash(), '&', $str);return $str;}// ----------------------------------------------------------------------//过滤不允许出现的字符串protected function _do_never_allowed($str){$str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);foreach ($this->_never_allowed_regex as $regex){$str = preg_replace('#'.$regex.'#is', '[removed]', $str);}return $str;}// --------------------------------------------------------------------//设置csrf的hash值protected function _csrf_set_hash(){if ($this->_csrf_hash == ''){// 如果_csrf_cookie_name存在，直接作为csrf hash值if (isset($_COOKIE[$this->_csrf_cookie_name]) &&preg_match('#^[0-9a-f]{32}$#iS', $_COOKIE[$this->_csrf_cookie_name]) === 1){return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];}                        //否则随机一个md5字符串return $this->_csrf_hash = md5(uniqid(rand(), TRUE));}return $this->_csrf_hash;}}</pre>