CI framework source code reading---------Security.php_PHP tutorial

[php]  

/** 

 * CodeIgniter 

 * 

 * An open source application development framework for PHP 5.1.6 or newer 

 * 

 * @package     CodeIgniter 

 * @author      ExpressionEngine Dev Team 

 * @copyright   Copyright (c) 2008 - 2011, EllisLab, Inc. 

 * @license     http://codeigniter.com/user_guide/license.html 

 * @link        http://codeigniter.com 

 * @since       Version 1.0 

 * @filesource 

 */  

  

// ------------------------------------------------------------------------  

  

/**

* Security Class

* This class contains some methods that can help you create secure applications and process input data securely.

* The address of CI official manual for this category: http://codeigniter.org.cn/user_guide/libraries/security.html

* @package CodeIgniter

* @subpackage Libraries

* @category Security

* @author ExpressionEngine Dev Team

* @link http://codeigniter.com/user_guide/libraries/security.html

*/  

class CI_Security {  

  

    /**

* Random Hash for protecting URLs

* Random hash value to protect URL (cross-site scripting attack)

* @var string

* @access protected

*/  

    protected $_xss_hash            = '';  

    /**

* Random Hash for Cross Site Request Forgery Protection Cookie

* Random hash to prevent cross-site requests from forging cookies

* @var string

* @access protected

*/  

    protected $_csrf_hash           = '';  

    /**

* Expiration time for Cross Site Request Forgery Protection Cookie

* Defaults to two hours (in seconds)

* Cross-site request protection cookie expiration time, the default is 2 hours (unit seconds)

* @var int

* @access protected

*/  

    protected $_csrf_expire         = 7200;  

    /**

* Token name for Cross Site Request Forgery Protection Cookie

* Cookie token name for cross-site request forgery protection

* @var string

* @access protected

*/  

    protected $_csrf_token_name     = 'ci_csrf_token';  

    /**

* Cookie name for Cross Site Request Forgery Protection Cookie

* Cookie name of the cookie for cross-site request forgery protection

* @var string

* @access protected

*/  

    protected $_csrf_cookie_name    = 'ci_csrf_token';  

    /**

* List of never allowed strings

* List of strings that are never allowed

* @var array

* @access protected

*/  

    protected $_never_allowed_str = array(  

        'document.cookie'   => '[removed]',  

        'document.write'    => '[removed]',  

        '.parentNode'       => '[removed]',  

        '.innerHTML'        => '[removed]',  

        'window.location'   => '[removed]',  

        '-moz-binding'      => '[removed]',  

        ''                => '-->',  

        ' '

        ''           => ''  

    );  

  

    /* never allowed, regex replacement */  

    /**

* List of never allowed regex replacement

* List of disallowed regular replacement strings

* @var array

* @access protected

*/  

    protected $_never_allowed_regex = array(  

        'javascripts*:',  

        'expressions*((|()', // CSS and IE  

        'vbscripts*:', // IE, surprise!  

        'Redirects+302',  

        "(["'])?datas*:[^\1]*?base64[^\1]*?,[^\1]*?\1?"  

    );  

  

    /** 

     * Constructor 

     * 

     * @return  void 

     */  

    public function __construct()  

    {  

        // Is CSRF protection enabled?  

        // csrf 是否开启   

        if (config_item('csrf_protection') === TRUE)  

        {  

            // CSRF config 读取CSRF 配置并赋值给本类下的对应的属性  

            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  

            // 添加应用指定的cookie前缀  

            if (config_item('cookie_prefix'))  

            {  

                $this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;  

            }  

  

            // Set the CSRF hash  

            // 设置CSRF hash  

            $this->_csrf_set_hash();  

        }  

  

        log_message('debug', "Security Class Initialized");  

    }  

  

    // --------------------------------------------------------------------  

  

    /** 

     * Verify Cross Site Request Forgery Protection 

     * 验证跨站请求伪造保护 

     * @return  object 

*/

public function csrf_verify()

{

// If it's not a POST request we will set the CSRF cookie

// If it is not a post request, we need to 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 the request token does not exist, call csrf_show_error to report an error

if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]))

{

$this->csrf_show_error();

} }

// Do the tokens match?

// If the token is incorrect, an error will be reported.

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

// pollute the _POST array

// Destroy the sign because we don’t want to pollute the _POST array

unset($_POST[$this->_csrf_token_name]);

// Nothing should last forever

// Destroy cookie name and reset hash and cookie

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

* Set fake cookies to protect cross-site requests

* @return object

*/

public function csrf_set_cookie()

{

$expire = time() + $this->_csrf_expire;

$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;

// Set cookie when https exists

if ($secure_cookie && (emptyempty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))

{

return FALSE;

} }

// Set cookie

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

* Show CSRF error

* @return void

*/

    public function csrf_show_error()  

    {  

        show_error('The action you have requested is not allowed.');  

    }  

  

    // --------------------------------------------------------------------  

  

    /** 

     * Get CSRF Hash 

     * 获取CSRF hash 

     * Getter Method 

     * 

     * @return  string  self::_csrf_hash 

     */  

    public function get_csrf_hash()  

    {  

        return $this->_csrf_hash;  

    }  

  

    // --------------------------------------------------------------------  

  

    /**

* Get CSRF Token Name

* Get CSRF order ranking

* 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.Prevent 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.

* Filter data to prevent cross-site scripting attacks. This function does some work, but it's very thorough,

* Even prevents most obscure XSS attempts. Of course, nothing is 100% safe,

* But we have done all we can think of in this 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.

* Note: This function can only be used to process submitted data.

* This function should not be used during normal operation.

*

* 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? 

         * 需要过滤的字符串是数组吗？ 

         * 

         */  

        if (is_array($str))  

        {  

        while (list($key) = each($str))                                                                                    

                                                                 

$str[$key] = $this->xss_clean($str[$key]);

      }  

return $str;

} }

/*

* Remove Invisible Characters

* Remove invisible characters

*/

$str = remove_invisible_characters($str);

// Validate Entities in URLs

// Verify the character entity in the URL

$str = $this->_validate_entities($str);

/*

* URL Decode

* URL decoding

* Just in case stuff like this is submitted:

* Prevent things like the following from being submitted

* Google

* *

* Note: Use rawurldecode() so it does not remove plus signs

* rawurldecode() does not decode the plus sign ('+') into a space, while urldecode() does.

* *

*/

$str = rawurldecode($str);

/*

* Convert character entities to ASCII

* Convert physical characters into ASCII code

* This makes our test below reliable, we only convert tags within entities because these are the entities that will cause security issues

* 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("/|

/*

* Remove Invisible Characters Again!

* Remove invisible characters again

*/

$str = remove_invisible_characters($str);

/*

* Convert all tabs to spaces

* Convert all tab characters to spaces

* This prevents strings like this: ja vascript

* This is used to prevent strings similar to javascript

* NOTE: we deal with spaces between characters later.

* Note: We will deal with the spaces between characters later

* NOTE: preg_replace was found to be amazingly slow here on

* large blocks of data, so we use str_replace.

* Note: preg_replace is extremely slow here for large chunks of data, so use str_replace

* *

*/

if (strpos($str, "t") !== FALSE)

{

$str = str_replace("t", ' ', $str);

} }

/*

* Capture capture converted string for later comparison

* Capture the converted string for later comparison

*/

$converted_string = $str;

// Remove Strings that are never allowed

// Delete strings that are not allowed

$str = $this->_do_never_allowed($str);

/*

* Makes PHP tags safe

* Make PHP tags safe

* Note: XML tags are inadvertently replaced too:

* Note: XML tags can also be unintentionally replaced

*

* *

* But it doesn't seem to pose a problem.

* But it doesn’t seem to be 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

* Compress all decomposed 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

                                                                 

$temp .= substr($word, $i, 1)."s*";

      }  

                                                                                                                                                                               

                                                                                                                                                                                                        // 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

* Remove javascript code that is not allowed in link and image tags

* We used to do some version comparisons and use of stripos for PHP5,

* We usually use stripos in PHP5 to do some version comparisons,

* but it is dog slow compared to these simplified non-capturing

* But especially when the pattern exists in the string, it is much slower than the non-capturing preg_match()

* preg_match(), especially if the pattern exists in the string

*/

do

{

$original = $str;

if (preg_match("/

                                                                 

                    $str = preg_replace_callback("#]*?)(>|$)#si", array($this, '_js_link_removal'), $str);

      }  

if (preg_match("/

                                                                 

                      $str = preg_replace_callback("#]*?)(s?/?>|$)#si", array($this, '_js_img_removal'), $str);

      }  

                          if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))  

                                                                 

                    $str = preg_replace("##si", '[removed]', $str);

      }  

} }

while($original != $str);

unset($original);

// Remove evil attributes such as style, onclick and xmlns

// Remove harmful attributes, such as style, onclick, xmlns

$str = $this->_remove_evil_attributes($str, $is_image);

/*

* Sanitize naughty HTML elements

* Clean inappropriate HTML elements

* If a tag containing any of the words in the list

* below is found, the tag gets converted to entities.

* If a tag contains any of the words in the list below, the tag is converted to a character entity

* So this:

* Becomes:

*/

$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('#

/*

* Sanitize naughty scripting elements

* Clean up illegal script 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.

* Similar to the above, only replacing the queried disallowed tags similar to PHP and Javascript commands

* Rather than removing the code, it is better to convert the code into a non-executable entity

* *

* 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

// Final cleanup

// This adds a bit of extra precaution in case

// something got through the above filters

// Extra precautions to prevent the above processing from generating illegal characters

$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;

}

//------------------------------------------------ -----------------------

/**

* Random Hash for protecting URLs

* Then generate an _xss_hssh

* @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

* HTML entity decoding

* This function is a replacement for html_entity_decode()

* This function is used to replace the html_entity_decode() function

* The reason we are not using html_entity_decode() by itself is because

* while it is not technically 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.

* When there is no ; written after the encoded character, most browsers will be able to interpret the code correctly, however, html_entity_decode will not interpret it

* html_entity_decode() will not convert entities without semicolons, so use your own solution

* @param string

* @param string

* @return string

*/

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('~(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\1"))', $str);

return preg_replace('~([0-9]{2,4})~e', 'chr(\1)', $str);

}

//------------------------------------------------ -----------------------

/**

* Filename Security

* File name 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);  

        return stripslashes(str_replace($bad, '', $str));  

    }  

  

    // ----------------------------------------------------------------  

  

    /**

* Compact Exploded Words

* Compress the searched words

* Callback function for xss_clean() to remove whitespace from

* things like j a v a s c r i p t

* Callback function for xss_clean(), remove spaces from 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) 

     * 移除有害的html属性，（像事件处理和样式） 

     * It removes the evil attribute and either: 

     *  - Everything up until a space 

     *      For example, everything between the pipes: 

     *       

     *  - Everything inside the quotes 

     *      For example, everything between the pipes: 

     *       

     * 

     * @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  

        // 所有的havascript事件处理器  

        $evil_attributes = array('onw*', '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. 

             * Adobe Photoshop在JFIF图片中放入了XML元数据 

             * 包含命名空间，所以我们必须对图片允许这些 

             */  

            unset($evil_attributes[array_search('xmlns', $evil_attributes)]);  

        }  

  

        do {  

            $count = 0;  

            $attribs = array();  

  

// find occurrences of illegal attribute strings without quotes

// Find out illegal attributes that have not been added

preg_match_all('/('.implode('|', $evil_attributes).')s*=s*([^s>]*)/is', $str, $matches, PREG_SET_ORDER);

foreach ($matches as $attr)

                                                                 

$attribs[] = preg_quote($attr[0], '/');

      }  

// find occurrences of illegal illegal attribute strings with quotes (042 and 047 are octal quotes)

// Find out illegal attributes without quotations (042, 4,0 is an octagonal quotation)

preg_match_all("/(".implode('|', $evil_attributes).")s*=s*(

foreach ($matches as $attr)

                                                                 

$attribs[] = preg_quote($attr[0], '/');

      }  

// replace illegal attribute strings that are inside an html tag

// Replace the illegal attributes in the html label

if (count($attribs) > 0)

                                                                 

                      $str = preg_replace("/-])(.*?)(".implode(' |', $attribs).")(.*?)([s>

      }  

} while ($count);

return $str;

}

//------------------------------------------------ -----------------------

/** 

     * Sanitize Naughty HTML 

     * 消除有害的html 

     * Callback function for xss_clean() to remove naughty HTML elements 

     * 

     * @param   array 

     * @return  string 

     */

protected function _sanitize_naughty_html($matches)

{

// encode opening brace

$str = '

// encode captured opening or closing brace to prevent recursive vectors

$str .= str_replace(array('>', '', '

                              $matches[4]);                                      

return $str;

}

//------------------------------------------------ -----------------------

/**

* JS Link Removal

* js link cleaning

* 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

* Call xss_clean to clean up the connection

* @param array

     * @return  string 

     */  

    protected function _js_link_removal($match)  

    {  

        return str_replace(  

            $match[1],  

            preg_replace(  

                '#href=.*?(alert(|alert(|javascript:|livescript:|mocha:|charset=|window.|document.|.cookie|<script> <div>                '',  </script>

                $this->_filter_attributes(str_replace(array(''), '', $match[1]))  

            ),  

            $match[0]  

        );  

    }  

  

    // --------------------------------------------------------------------  

  

    /** 

     * JS Image Removal 

     * js图片清理 

     * 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(|alert(|javascript:|livescript:|mocha:|charset=|window.|document.|.cookie|<script> <div>                '',  </script>

                $this->_filter_attributes(str_replace(array(''), '', $match[1]))  

            ),  

            $match[0]  

        );  

    }  

  

    // --------------------------------------------------------------------  

  

    /** 

     * Attribute Conversion 

     * 属性转换 

     * Used as a callback for XSS Clean 

     * 

     * @param   array 

     * @return  string 

     */  

    protected function _convert_attribute($match)  

    {  

        return str_replace(array('>', '', '

    }  

  

    // --------------------------------------------------------------------  

  

    /**

* Filter Attributes

* Filter attributes

* Filters tag attributes for consistency and safety

* Filter tag attributes for consistency and security

* @param string

* @return string

*/  

    protected function _filter_attributes($str)  

    {  

        $out = '';  

  

        if (preg_match_all('#s*[a-z-]+s*=s*(