Файл: chatigniter v2/system/core/Security.php
Строк: 667
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* CodeIgniter
*
* An open source application development framework for PHP 5.1.6 or newer
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc.
* @copyright Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://codeigniter.com/user_guide/license.html
* @link http://codeigniter.com
* @since Version 1.0
* @filesource
*/
// ------------------------------------------------------------------------
/**
* Security Class
*
* @package CodeIgniter
* @subpackage Libraries
* @category Security
* @author EllisLab Dev Team
* @link http://codeigniter.com/user_guide/libraries/security.html
*/
class CI_Security {
/**
* Random Hash for protecting URLs
*
* @var string
* @access protected
*/
protected $_xss_hash = '';
/**
* Random Hash for Cross Site Request Forgery Protection Cookie
*
* @var string
* @access protected
*/
protected $_csrf_hash = '';
/**
* Expiration time for Cross Site Request Forgery Protection Cookie
* Defaults to two hours (in seconds)
*
* @var int
* @access protected
*/
protected $_csrf_expire = 7200;
/**
* Token name for Cross Site Request Forgery Protection Cookie
*
* @var string
* @access protected
*/
protected $_csrf_token_name = 'ci_csrf_token';
/**
* Cookie name for Cross Site Request Forgery Protection Cookie
*
* @var string
* @access protected
*/
protected $_csrf_cookie_name = 'ci_csrf_token';
/**
* List of never allowed strings
*
* @var array
* @access protected
*/
protected $_never_allowed_str = array(
'document.cookie' => '[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'-moz-binding' => '[removed]',
'<!--' => '<!--',
'-->' => '-->',
'<![CDATA[' => '<![CDATA[',
'<comment>' => '<comment>'
);
/* never allowed, regex replacement */
/**
* List of never allowed regex replacement
*
* @var array
* @access protected
*/
protected $_never_allowed_regex = array(
'javascripts*:',
'(document|(document.)?window).(location|onw*)',
'expressions*((|()', // CSS and IE
'vbscripts*:', // IE, surprise!
'wscripts*:', // IE
'jscripts*:', // IE
'vbss*:', // IE
'Redirects+30d:',
"(["'])?datas*:[^\1]*?base64[^\1]*?,[^\1]*?\1?"
);
/**
* Constructor
*
* @return void
*/
public function __construct()
{
// Is CSRF protection enabled?
if (config_item('csrf_protection') === TRUE)
{
// CSRF config
foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
{
if (FALSE !== ($val = config_item($key)))
{
$this->{'_'.$key} = $val;
}
}
// Append application specific cookie prefix
if (config_item('cookie_prefix'))
{
$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;
}
// Set the CSRF hash
$this->_csrf_set_hash();
}
log_message('debug', "Security Class Initialized");
}
// --------------------------------------------------------------------
/**
* Verify Cross Site Request Forgery Protection
*
* @return object
*/
public function csrf_verify()
{
// If it's not a POST request we will set the CSRF cookie
if (strtoupper($_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]))
{
$this->csrf_show_error();
}
// Do the tokens match?
if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name])
{
$this->csrf_show_error();
}
// We kill this since we're done and we don't want to
// polute the _POST array
unset($_POST[$this->_csrf_token_name]);
// Nothing should last forever
unset($_COOKIE[$this->_csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();
log_message('debug', 'CSRF token verified');
return $this;
}
// --------------------------------------------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
*
* @return object
*/
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;
}
// --------------------------------------------------------------------
/**
* Show CSRF Error
*
* @return void
*/
public function csrf_show_error()
{
show_error('The action you have requested is not allowed.');
}
// --------------------------------------------------------------------
/**
* Get CSRF Hash
*
* Getter Method
*
* @return string self::_csrf_hash
*/
public function get_csrf_hash()
{
return $this->_csrf_hash;
}
// --------------------------------------------------------------------
/**
* Get CSRF Token Name
*
* Getter Method
*
* @return string self::csrf_token_name
*/
public function get_csrf_token_name()
{
return $this->_csrf_token_name;
}
// --------------------------------------------------------------------
/**
* XSS Clean
*
* Sanitizes data so that Cross Site Scripting Hacks can be
* prevented. This function does a fair amount of work but
* it is extremely thorough, designed to prevent even the
* most obscure XSS attempts. Nothing is ever 100% foolproof,
* of course, but I haven't been able to get anything passed
* the filter.
*
* Note: This function should only be used to deal with data
* upon submission. It's not something that should
* be used for general runtime processing.
*
* This function was based in part on some code and ideas I
* got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention
*
* To help develop this script I used this great list of
* vulnerabilities along with a few other hacks I've
* harvested from examining vulnerabilities in other programs:
* http://ha.ckers.org/xss.html
*
* @param mixed string or array
* @param bool
* @return string
*/
public function xss_clean($str, $is_image = FALSE)
{
// Is the string an array?
if (is_array($str))
{
while (list($key) = each($str))
{
$str[$key] = $this->xss_clean($str[$key]);
}
return $str;
}
//Remove Invisible Characters
$str = remove_invisible_characters($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: Use rawurldecode() so it does not remove plus signs
*/
do
{
$str = rawurldecode($str);
}
while (preg_match('/%[0-9a-f]{2,}/i', $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.
*/
$str = preg_replace_callback("/[^a-z0-9>]+[a-z0-9]+=(['"]).*?\1/si", array($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: 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);
// 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.
*/
$words = array(
'javascript', 'expression', 'vbscript', 'jscript', 'wscript',
'vbs', 'script', 'base64', 'applet', 'alert', 'document',
'write', 'cookie', 'window', 'confirm', 'prompt'
);
foreach ($words as $word)
{
$word = implode('s*', str_split($word)).'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"
$str = preg_replace_callback('#('.substr($word, 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(),
* but it is dog slow compared to these simplified non-capturing
* preg_match(), especially if the pattern exists in the string
*
* Note: It was reported that not only space characters, but all in
* the following pattern can be parsed as separators between a tag name
* and its attributes: [ds"'`;,/=(x00x0Bx09x0C]
* ... however, remove_invisible_characters() above already strips the
* hex-encoded ones, so we'll skip them below.
*/
do
{
$original = $str;
if (preg_match('/<a/i', $str))
{
$str = preg_replace_callback('#<a[^a-z0-9>]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str);
}
if (preg_match('/<img/i', $str))
{
$str = preg_replace_callback('#<img[^a-z0-9]+([^>]*?)(?:s?/?>|$)#si', array($this, '_js_img_removal'), $str);
}
if (preg_match('/script|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|prompt|confirm|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|button|select|isindex|layer|link|meta|keygen|object|plaintext|style|script|textarea|title|math|video|svg|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|prompt|confirm|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);
}
log_message('debug', "XSS Filtering completed");
return $str;
}
// --------------------------------------------------------------------
/**
* Random Hash for protecting URLs
*
* @return string
*/
public function xss_hash()
{
if ($this->_xss_hash == '')
{
mt_srand();
$this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
}
return $this->_xss_hash;
}
// --------------------------------------------------------------------
/**
* HTML Entities Decode
*
* This function is a replacement for html_entity_decode()
*
* The reason we are not using html_entity_decode() by itself is because
* while it is not technically correct to leave out the semicolon
* at the end of an entity most browsers will still interpret the entity
* correctly. html_entity_decode() does not convert entities without
* semicolons, so we are left with our own little solution here. Bummer.
*
* @param string
* @param string
* @return string
*/
public function entity_decode($str, $charset='UTF-8')
{
if (strpos($str, '&') === FALSE)
{
return $str;
}
static $_entities;
isset($charset) OR $charset = strtoupper(config_item('charset'));
$flag = is_php('5.4')
? ENT_COMPAT | ENT_HTML5
: ENT_COMPAT;
do
{
$str_compare = $str;
// Decode standard entities, avoiding false positives
if ($c = preg_match_all('/&[a-z]{2,}(?![a-z;])/i', $str, $matches))
{
if ( ! isset($_entities))
{
$_entities = array_map(
'strtolower',
is_php('5.3.4')
? get_html_translation_table(HTML_ENTITIES, $flag, $charset)
: get_html_translation_table(HTML_ENTITIES, $flag)
);
// If we're not on PHP 5.4+, add the possibly dangerous HTML 5
// entities to the array manually
if ($flag === ENT_COMPAT)
{
$_entities[':'] = ':';
$_entities['('] = '(';
$_entities[')'] = '&rpar';
$_entities["n"] = '&newline;';
$_entities["t"] = '&tab;';
}
}
$replace = array();
$matches = array_unique(array_map('strtolower', $matches[0]));
for ($i = 0; $i < $c; $i++)
{
if (($char = array_search($matches[$i].';', $_entities, TRUE)) !== FALSE)
{
$replace[$matches[$i]] = $char;
}
}
$str = str_ireplace(array_keys($replace), array_values($replace), $str);
}
// Decode numeric & UTF16 two byte entities
$str = html_entity_decode(
preg_replace('/(&#(?:x0*[0-9a-f]{2,5}(?![0-9a-f;])|(?:0*d{2,4}(?![0-9;]))))/iS', '$1;', $str),
$flag,
$charset
);
}
while ($str_compare !== $str);
return $str;
}
// --------------------------------------------------------------------
/**
* Filename Security
*
* @param string
* @param bool
* @return string
*/
public function sanitize_filename($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);
do
{
$old = $str;
$str = str_replace($bad, '', $str);
}
while ($old !== $str);
return stripslashes($str);
}
// ----------------------------------------------------------------
/**
* Compact Exploded Words
*
* Callback function for xss_clean() to remove whitespace from
* things like j a v a s c r i p t
*
* @param type
* @return type
*/
protected function _compact_exploded_words($matches)
{
return preg_replace('/s+/s', '', $matches[1]).$matches[2];
}
// --------------------------------------------------------------------
/*
* Remove Evil HTML Attributes (like evenhandlers and style)
*
* It removes the evil attribute and either:
* - Everything up until a space
* For example, everything between the pipes:
* <a |style=document.write('hello');alert('world');| class=link>
* - Everything inside the quotes
* For example, everything between the pipes:
* <a |style="document.write('hello'); alert('world');"| class="link">
*
* @param string $str The string to check
* @param boolean $is_image TRUE if this is an image
* @return string The string with the evil attributes removed
*/
protected function _remove_evil_attributes($str, $is_image)
{
// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
$evil_attributes = array('onw*', 'style', 'xmlns', 'formaction', 'form', 'xlink:href');
if ($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('/(?<!w)('.implode('|', $evil_attributes).')s*=s*( 42| 47)([^\2]*?)(\2)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// find occurrences of illegal attribute strings without quotes
preg_match_all('/(?<!w)('.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 tag
if (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 $str;
}
// --------------------------------------------------------------------
/**
* Sanitize Naughty HTML
*
* Callback function for xss_clean() to remove naughty HTML elements
*
* @param array
* @return string
*/
protected function _sanitize_naughty_html($matches)
{
return '<'.$matches[1].$matches[2].$matches[3] // encode opening brace
// encode captured opening or closing brace to prevent recursive vectors:
.str_replace(array('>', '<'), array('>', '<'), $matches[4]);
}
// --------------------------------------------------------------------
/**
* JS Link Removal
*
* Callback function for xss_clean() to sanitize links
* This limits the PCRE backtracks, making it more performance friendly
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on link-heavy strings
*
* @param array
* @return string
*/
protected function _js_link_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#href=.*?(?:(?:alert|prompt|confirm)(?:(|()|javascript:|livescript:|mocha:|charset=|window.|document.|.cookie|<script|<xss|datas*:)#si',
'',
$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
// --------------------------------------------------------------------
/**
* JS Image Removal
*
* Callback function for xss_clean() to sanitize image tags
* This limits the PCRE backtracks, making it more performance friendly
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on image tag heavy strings
*
* @param array
* @return string
*/
protected function _js_img_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#src=.*?(?:(?:alert|prompt|confirm)(?:(|()|javascript:|livescript:|mocha:|charset=|window.|document.|.cookie|<script|<xss|base64s*,)#si',
'',
$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
// --------------------------------------------------------------------
/**
* Attribute Conversion
*
* Used as a callback for XSS Clean
*
* @param array
* @return string
*/
protected function _convert_attribute($match)
{
return str_replace(array('>', '<', '\'), array('>', '<', '\\'), $match[0]);
}
// --------------------------------------------------------------------
/**
* Filter Attributes
*
* Filters tag attributes for consistency and safety
*
* @param string
* @return string
*/
protected function _filter_attributes($str)
{
$out = '';
if (preg_match_all('#s*[a-z-]+s*=s*( 42| 47)([^\1]*?)\1#is', $str, $matches))
{
foreach ($matches[0] as $match)
{
$out .= preg_replace("#/*.*?*/#s", '', $match);
}
}
return $out;
}
// --------------------------------------------------------------------
/**
* HTML Entity Decode Callback
*
* Used as a callback for XSS Clean
*
* @param array
* @return string
*/
protected function _decode_entity($match)
{
// Protect GET variables in URLs
// 901119URL5918AMP18930PROTECT8198
$match = preg_replace('|&([a-z_0-9-]+)=([a-z_0-9-/]+)|i', $this->xss_hash().'\1=\2', $match[0]);
// Decode, then un-protect URL GET vars
return str_replace(
$this->xss_hash(),
'&',
$this->entity_decode($match, strtoupper(config_item('charset')))
);
}
// ----------------------------------------------------------------------
/**
* Do Never Allowed
*
* A utility function for xss_clean()
*
* @param string
* @return string
*/
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 $str;
}
// --------------------------------------------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
*
* @return string
*/
protected function _csrf_set_hash()
{
if ($this->_csrf_hash == '')
{
// If the cookie exists we will use it's value.
// We don't necessarily want to regenerate it with
// each page load since a page could contain embedded
// sub-pages causing this feature to fail
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];
}
return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
}
return $this->_csrf_hash;
}
}
/* End of file Security.php */
/* Location: ./system/core/Security.php */