<?php if (!defined('BASEPATH')) exit('No direct script access allowed'); /** * CodeIgniter * * An open source application development framework for PHP 4.3.2 or newer * * @package CodeIgniter * @author Rick Ellis * @copyright Copyright (c) 2006, EllisLab, Inc. * @license http://www.codeignitor.com/user_guide/license.html * @link http://www.codeigniter.com * @since Version 1.0 * @filesource */ // ------------------------------------------------------------------------ /** * Input Class * * Pre-processes global input data for security * * @package CodeIgniter * @subpackage Libraries * @category Input * @author Rick Ellis * @link http://www.codeigniter.com/user_guide/libraries/input.html */ class CI_Input { var $use_xss_clean = FALSE; var $ip_address = FALSE; var $user_agent = FALSE; var $allow_get_array = FALSE; /** * Constructor * * Sets whether to globally enable the XSS processing * and whether to allow the $_GET array * * @access public */ function CI_Input() { log_message('debug', "Input Class Initialized"); $CFG =& load_class('Config'); $this->use_xss_clean = ($CFG->item('global_xss_filtering') === TRUE) ? TRUE : FALSE; $this->allow_get_array = ($CFG->item('enable_query_strings') === TRUE) ? TRUE : FALSE; $this->_sanitize_globals(); } // -------------------------------------------------------------------- /** * Sanitize Globals * * This function does the following: * * Unsets $_GET data (if query strings are not enabled) * * Unsets all globals if register_globals is enabled * * Standardizes newline characters to \n * * @access private * @return void */ function _sanitize_globals() { // Would kind of be "wrong" to unset any of these GLOBALS. $protected = array('_SERVER', '_GET', '_POST', '_FILES', '_REQUEST', '_SESSION', '_ENV', 'GLOBALS', 'HTTP_RAW_POST_DATA'); // Unset globals for securiy. // This is effectively the same as register_globals = off foreach (array($_GET, $_POST, $_COOKIE) as $global) { if ( ! is_array($global)) { if ( ! in_array($global, $protected)) { global $global; $$global = NULL; } } else { foreach ($global as $key => $val) { if ( ! in_array($key, $protected)) { global $$key; $$key = NULL; } } } } // Is $_GET data allowed? If not we'll set the $_GET to an empty array if ($this->allow_get_array == FALSE) { $_GET = array(); } else { if (is_array($_GET) AND count($_GET) > 0) { foreach($_GET as $key => $val) { $_GET[$this->_clean_input_keys($key)] = $this->_clean_input_data($val); } } } // Clean $_POST Data if (is_array($_POST) AND count($_POST) > 0) { foreach($_POST as $key => $val) { $_POST[$this->_clean_input_keys($key)] = $this->_clean_input_data($val); } } // Clean $_COOKIE Data if (is_array($_COOKIE) AND count($_COOKIE) > 0) { foreach($_COOKIE as $key => $val) { $_COOKIE[$this->_clean_input_keys($key)] = $this->_clean_input_data($val); } } log_message('debug', "Global POST and COOKIE data sanitized"); } // -------------------------------------------------------------------- /** * Clean Input Data * * This is a helper function. It escapes data and * standardizes newline characters to \n * * @access private * @param string * @return string */ function _clean_input_data($str) { if (is_array($str)) { $new_array = array(); foreach ($str as $key => $val) { $new_array[$this->_clean_input_keys($key)] = $this->_clean_input_data($val); } return $new_array; } // We strip slashes if magic quotes is on to keep things consistent if (get_magic_quotes_gpc()) { $str = stripslashes($str); } // Should we filter the input data? if ($this->use_xss_clean === TRUE) { $str = $this->xss_clean($str); } // Standardize newlines return preg_replace("/\015\012|\015|\012/", "\n", $str); } // -------------------------------------------------------------------- /** * Clean Keys * * This is a helper function. To prevent malicious users * from trying to exploit keys we make sure that keys are * only named with alpha-numeric text and a few other items. * * @access private * @param string * @return string */ function _clean_input_keys($str) { if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str)) { exit('Disallowed Key Characters.'); } return $str; } // -------------------------------------------------------------------- /** * Fetch an item from the GET array * * @access public * @param string * @param bool * @return string */ function get($index = '', $xss_clean = FALSE) { if ( ! isset($_GET[$index])) { return FALSE; } if ($xss_clean === TRUE) { if (is_array($_GET[$index])) { foreach($_GET[$index] as $key => $val) { $_GET[$index][$key] = $this->xss_clean($val); } } else { return $this->xss_clean($_GET[$index]); } } return $_GET[$index]; } // -------------------------------------------------------------------- /** * Fetch an item from the POST array * * @access public * @param string * @param bool * @return string */ function post($index = '', $xss_clean = FALSE) { if ( ! isset($_POST[$index])) { return FALSE; } if ($xss_clean === TRUE) { if (is_array($_POST[$index])) { foreach($_POST[$index] as $key => $val) { $_POST[$index][$key] = $this->xss_clean($val); } } else { return $this->xss_clean($_POST[$index]); } } return $_POST[$index]; } // -------------------------------------------------------------------- /** * Fetch an item from the COOKIE array * * @access public * @param string * @param bool * @return string */ function cookie($index = '', $xss_clean = FALSE) { if ( ! isset($_COOKIE[$index])) { return FALSE; } if ($xss_clean === TRUE) { if (is_array($_COOKIE[$index])) { $cookie = array(); foreach($_COOKIE[$index] as $key => $val) { $cookie[$key] = $this->xss_clean($val); } return $cookie; } else { return $this->xss_clean($_COOKIE[$index]); } } else { return $_COOKIE[$index]; } } // -------------------------------------------------------------------- /** * Fetch an item from the SERVER array * * @access public * @param string * @param bool * @return string */ function server($index = '', $xss_clean = FALSE) { if ( ! isset($_SERVER[$index])) { return FALSE; } if ($xss_clean === TRUE) { return $this->xss_clean($_SERVER[$index]); } return $_SERVER[$index]; } // -------------------------------------------------------------------- /** * Fetch the IP Address * * @access public * @return string */ function ip_address() { if ($this->ip_address !== FALSE) { return $this->ip_address; } if ($this->server('REMOTE_ADDR') AND $this->server('HTTP_CLIENT_IP')) { $this->ip_address = $_SERVER['HTTP_CLIENT_IP']; } elseif ($this->server('REMOTE_ADDR')) { $this->ip_address = $_SERVER['REMOTE_ADDR']; } elseif ($this->server('HTTP_CLIENT_IP')) { $this->ip_address = $_SERVER['HTTP_CLIENT_IP']; } elseif ($this->server('HTTP_X_FORWARDED_FOR')) { $this->ip_address = $_SERVER['HTTP_X_FORWARDED_FOR']; } if ($this->ip_address === FALSE) { $this->ip_address = '0.0.0.0'; return $this->ip_address; } if (strstr($this->ip_address, ',')) { $x = explode(',', $this->ip_address); $this->ip_address = end($x); } if ( ! $this->valid_ip($this->ip_address)) { $this->ip_address = '0.0.0.0'; } return $this->ip_address; } // -------------------------------------------------------------------- /** * Validate IP Address * * Updated version suggested by Geert De Deckere * * @access public * @param string * @return string */ function valid_ip($ip) { $ip_segments = explode('.', $ip); // Always 4 segments needed if (count($ip_segments) != 4) { return FALSE; } // IP can not start with 0 if (substr($ip_segments[0], 0, 1) == '0') { return FALSE; } // Check each segment foreach ($ip_segments as $segment) { // IP segments must be digits and can not be // longer than 3 digits or greater then 255 if (preg_match("/[^0-9]/", $segment) OR $segment > 255 OR strlen($segment) > 3) { return FALSE; } } return TRUE; } // -------------------------------------------------------------------- /** * User Agent * * @access public * @return string */ function user_agent() { if ($this->user_agent !== FALSE) { return $this->user_agent; } $this->user_agent = ( ! isset($_SERVER['HTTP_USER_AGENT'])) ? FALSE : $_SERVER['HTTP_USER_AGENT']; return $this->user_agent; } // -------------------------------------------------------------------- /** * Filename Security * * @access public * @param string * @return string */ function filename_security($str) { $bad = array( "../", "./", "<!--", "-->", "<", ">", "'", '"', '&', '$', '#', '{', '}', '[', ']', '=', ';', '?', "%20", "%22", "%3c", // < "%253c", // < "%3e", // > "%0e", // > "%28", // ( "%29", // ) "%2528", // ( "%26", // & "%24", // $ "%3f", // ? "%3b", // ; "%3d" // = ); return stripslashes(str_replace($bad, '', $str)); } // -------------------------------------------------------------------- /** * XSS Clean * * Sanitizes data so that Cross Site Scripting Hacks can be * prevented. This function does a fair amount of work but * it is extremely thorough, designed to prevent even the * most obscure XSS attempts. Nothing is ever 100% foolproof, * of course, but I haven't been able to get anything passed * the filter. * * Note: This function should only be used to deal with data * upon submission. It's not something that should * be used for general runtime processing. * * This function was based in part on some code and ideas I * got from Bitflux: http://blog.bitflux.ch/wiki/XSS_Prevention * * To help develop this script I used this great list of * vulnerabilities along with a few other hacks I've * harvested from examining vulnerabilities in other programs: * http://ha.ckers.org/xss.html * * @access public * @param string * @return string */ function xss_clean($str) { /* * Remove Null Characters * * This prevents sandwiching null characters * between ascii characters, like Java\0script. * */ $str = preg_replace('/\0+/', '', $str); $str = preg_replace('/(\\\\0)+/', '', $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]+)[\x00-\x20]*;?#i', "\\1;", $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); /* * URL Decode * * Just in case stuff like this is submitted: * * <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a> * * Note: Normally urldecode() would be easier but it removes plus signs * */ $str = preg_replace("/(%20)+/", '9u3iovBnRThju941s89rKozm', $str); $str = preg_replace("/%u0([a-z0-9]{3})/i", "&#x\\1;", $str); $str = preg_replace("/%([a-z0-9]{2})/i", "&#x\\1;", $str); $str = str_replace('9u3iovBnRThju941s89rKozm', "%20", $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, '_attribute_conversion'), $str); $str = preg_replace_callback("/<([\w]+)[^>]*>/si", array($this, '_html_entity_decode_callback'), $str); /* Old Code that when modified to use preg_replace()'s above became more efficient memory-wise if (preg_match_all("/[a-z]+=([\'\"]).*?\\1/si", $str, $matches)) { for ($i = 0; $i < count($matches[0]); $i++) { if (stristr($matches[0][$i], '>')) { $str = str_replace( $matches['0'][$i], str_replace('>', '<', $matches[0][$i]), $str); } } } if (preg_match_all("/<([\w]+)[^>]*>/si", $str, $matches)) { for ($i = 0; $i < count($matches[0]); $i++) { $str = str_replace($matches[0][$i], $this->_html_entity_decode($matches[0][$i], $charset), $str); } } */ /* * Convert all tabs to spaces * * This prevents strings like this: ja vascript * 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. * */ $str = str_replace("\t", " ", $str); /* * Not Allowed Under Any Conditions */ $bad = array( 'document.cookie' => '[removed]', 'document.write' => '[removed]', '.parentNode' => '[removed]', '.innerHTML' => '[removed]', 'window.location' => '[removed]', '-moz-binding' => '[removed]', '<!--' => '<!--', '-->' => '-->', '<!CDATA[' => '<![CDATA[' ); foreach ($bad as $key => $val) { $str = str_replace($key, $val, $str); } $bad = array( "javascript\s*:" => '[removed]', "expression\s*\(" => '[removed]', // CSS and IE "Redirect\s+302" => '[removed]' ); foreach ($bad as $key => $val) { $str = preg_replace("#".$key."#i", $val, $str); } /* * Makes PHP tags safe * * Note: XML tags are inadvertently replaced too: * * <?xml * * But it doesn't seem to pose a problem. * */ $str = str_replace(array('<?php', '<?PHP', '<?', '?'.'>'), array('<?php', '<?PHP', '<?', '?>'), $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. * */ $words = array('javascript', 'expression', 'vbscript', 'script', 'applet', 'alert', 'document', 'write', 'cookie', 'window'); foreach ($words as $word) { $temp = ''; for ($i = 0; $i < strlen($word); $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" $str = preg_replace('#('.substr($temp, 0, -3).')(\W)#ise', "preg_replace('/\s+/s', '', '\\1').'\\2'", $str); } /* * Remove disallowed Javascript in links or img tags */ do { $original = $str; if ((version_compare(PHP_VERSION, '5.0', '>=') === TRUE && stripos($str, '</a>') !== FALSE) OR preg_match("/<\/a>/i", $str)) { $str = preg_replace_callback("#<a.*?</a>#si", array($this, '_js_link_removal'), $str); } if ((version_compare(PHP_VERSION, '5.0', '>=') === TRUE && stripos($str, '<img') !== FALSE) OR preg_match("/img/i", $str)) { $str = preg_replace_callback("#<img.*?".">#si", array($this, '_js_img_removal'), $str); } if ((version_compare(PHP_VERSION, '5.0', '>=') === TRUE && (stripos($str, 'script') !== FALSE OR stripos($str, 'xss') !== FALSE)) OR preg_match("/(script|xss)/i", $str)) { $str = preg_replace("#</*(script|xss).*?\>#si", "", $str); } } while($original != $str); unset($original); /* * Remove JavaScript Event Handlers * * Note: This code is a little blunt. It removes * the event handler and anything up to the closing >, * but it's unlikely to be a problem. * */ $event_handlers = array('onblur','onchange','onclick','onfocus','onload','onmouseover','onmouseup','onmousedown','onselect','onsubmit','onunload','onkeypress','onkeydown','onkeyup','onresize', 'xmlns'); $str = preg_replace("#<([^>]+)(".implode('|', $event_handlers).")([^>]*)>#iU", "<\\1\\2\\3>", $str); /* * 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> * */ $str = preg_replace('#<(/*\s*)(alert|applet|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|layer|link|meta|object|plaintext|style|script|textarea|title|xml|xss)([^>]*)>#is', "<\\1\\2\\3>", $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 * */ $bad = array( 'document.cookie' => '[removed]', 'document.write' => '[removed]', '.parentNode' => '[removed]', '.innerHTML' => '[removed]', 'window.location' => '[removed]', '-moz-binding' => '[removed]', '<!--' => '<!--', '-->' => '-->', '<!CDATA[' => '<![CDATA[' ); foreach ($bad as $key => $val) { $str = str_replace($key, $val, $str); } $bad = array( "javascript\s*:" => '[removed]', "expression\s*\(" => '[removed]', // CSS and IE "Redirect\s+302" => '[removed]' ); foreach ($bad as $key => $val) { $str = preg_replace("#".$key."#i", $val, $str); } log_message('debug', "XSS Filtering completed"); return $str; } // -------------------------------------------------------------------- /** * JS Link Removal * * Callback function for xss_clean() to sanitize links * This limits the PCRE backtracks, making it more performance friendly * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in * PHP 5.2+ on link-heavy strings * * @access private * @param array * @return string */ function _js_link_removal($match) { return preg_replace("#<a.+?href=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\>.*?</a>#si", "", $match[0]); } /** * JS Image Removal * * Callback function for xss_clean() to sanitize image tags * This limits the PCRE backtracks, making it more performance friendly * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in * PHP 5.2+ on image tag heavy strings * * @access private * @param array * @return string */ function _js_img_removal($match) { return preg_replace("#<img.+?src=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\>#si", "", $match[0]); } // -------------------------------------------------------------------- /** * Attribute Conversion * * Used as a callback for XSS Clean * * @access public * @param array * @return string */ function _attribute_conversion($match) { return str_replace('>', '<', $match[0]); } // -------------------------------------------------------------------- /** * HTML Entity Decode Callback * * Used as a callback for XSS Clean * * @access public * @param array * @return string */ function _html_entity_decode_callback($match) { global $CFG; $charset = $CFG->item('charset'); return $this->_html_entity_decode($match[0], strtoupper($charset)); } // -------------------------------------------------------------------- /** * HTML Entities Decode * * This function is a replacement for html_entity_decode() * * In some versions of PHP the native function does not work * when UTF-8 is the specified character set, so this gives us * a work-around. More info here: * http://bugs.php.net/bug.php?id=25670 * * @access private * @param string * @param string * @return string */ /* ------------------------------------------------- /* Replacement for html_entity_decode() /* -------------------------------------------------*/ /* NOTE: html_entity_decode() has a bug in some PHP versions when UTF-8 is the character set, and the PHP developers said they were not back porting the fix to versions other than PHP 5.x. */ function _html_entity_decode($str, $charset='UTF-8') { if (stristr($str, '&') === FALSE) return $str; // The reason we are not using html_entity_decode() by itself is because // while it is not technically correct to leave out the semicolon // at the end of an entity most browsers will still interpret the entity // correctly. html_entity_decode() does not convert entities without // semicolons, so we are left with our own little solution here. Bummer. if (function_exists('html_entity_decode') && (strtolower($charset) != 'utf-8' OR version_compare(phpversion(), '5.0.0', '>='))) { $str = html_entity_decode($str, ENT_COMPAT, $charset); $str = preg_replace('~&#x([0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str); return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str); } // Numeric Entities $str = preg_replace('~&#x([0-9a-f]{2,5});{0,1}~ei', 'chr(hexdec("\\1"))', $str); $str = preg_replace('~&#([0-9]{2,4});{0,1}~e', 'chr(\\1)', $str); // Literal Entities - Slightly slow so we do another check if (stristr($str, '&') === FALSE) { $str = strtr($str, array_flip(get_html_translation_table(HTML_ENTITIES))); } return $str; } } // END Input class ?>