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authorPascal Kriete <pascal.kriete@ellislab.com>2011-04-05 20:50:41 +0200
committerPascal Kriete <pascal.kriete@ellislab.com>2011-04-05 20:50:41 +0200
commitc9c045a7feee07563c8d14bac3381f7af0e17280 (patch)
treeb30ac4b626dcc45dbc5ede67b53dadc3394dd2fb
parent08b5169a5181706156c9a53229d164d9fa3aea32 (diff)
Improving parameter security in xss clean
-rw-r--r--system/libraries/Security.php620
1 files changed, 351 insertions, 269 deletions
diff --git a/system/libraries/Security.php b/system/libraries/Security.php
index 58db4e79c..ceef9779c 100644
--- a/system/libraries/Security.php
+++ b/system/libraries/Security.php
@@ -22,44 +22,44 @@
* @subpackage Libraries
* @category Security
* @author ExpressionEngine Dev Team
- * @link http://codeigniter.com/user_guide/libraries/sessions.html
+ * @link http://codeigniter.com/user_guide/libraries/security.html
*/
class CI_Security {
-
- public $xss_hash = '';
- public $csrf_hash = '';
- public $csrf_expire = 7200; // Two hours (in seconds)
- public $csrf_token_name = 'ci_csrf_token';
- public $csrf_cookie_name = 'ci_csrf_token';
+
+ protected $_xss_hash = '';
+ protected $_csrf_hash = '';
+ protected $_csrf_expire = 7200; // Two hours (in seconds)
+ protected $_csrf_token_name = 'ci_csrf_token';
+ protected $_csrf_cookie_name = 'ci_csrf_token';
/* never allowed, string replacement */
- public $never_allowed_str = array(
- 'document.cookie' => '[removed]',
- 'document.write' => '[removed]',
- '.parentNode' => '[removed]',
- '.innerHTML' => '[removed]',
- 'window.location' => '[removed]',
- '-moz-binding' => '[removed]',
- '<!--' => '&lt;!--',
- '-->' => '--&gt;',
- '<![CDATA[' => '&lt;![CDATA['
- );
- /* never allowed, regex replacement */
- public $never_allowed_regex = array(
- "javascript\s*:" => '[removed]',
- "expression\s*(\(|&\#40;)" => '[removed]', // CSS and IE
- "vbscript\s*:" => '[removed]', // IE, surprise!
- "Redirect\s+302" => '[removed]'
- );
+ protected $_never_allowed_str = array(
+ 'document.cookie' => '[removed]',
+ 'document.write' => '[removed]',
+ '.parentNode' => '[removed]',
+ '.innerHTML' => '[removed]',
+ 'window.location' => '[removed]',
+ '-moz-binding' => '[removed]',
+ '<!--' => '&lt;!--',
+ '-->' => '--&gt;',
+ '<![CDATA[' => '&lt;![CDATA['
+ );
+ /* never allowed, regex replacement */
+ protected $_never_allowed_regex = array(
+ "javascript\s*:" => '[removed]',
+ "expression\s*(\(|&\#40;)" => '[removed]', // CSS and IE
+ "vbscript\s*:" => '[removed]', // IE, surprise!
+ "Redirect\s+302" => '[removed]'
+ );
+
+ /**
+ * Constructor
+ */
public function __construct()
{
- $this->csrf_token_name = (config_item('csrf_token_name')) ? config_item('csrf_token_name') : 'csrf_token_name';
- $this->csrf_cookie_name = (config_item('csrf_cookie_name')) ? config_item('csrf_cookie_name') : 'csrf_cookie_name';
- $this->csrf_expire = (config_item('csrf_expire')) ? config_item('csrf_expire') : 7200;
-
// Append application specific cookie prefix to token name
- $this->csrf_cookie_name = (config_item('cookie_prefix')) ? config_item('cookie_prefix').$this->csrf_token_name : $this->csrf_token_name;
+ $this->_csrf_cookie_name = (config_item('cookie_prefix')) ? config_item('cookie_prefix').$this->_csrf_token_name : $this->_csrf_token_name;
// Set the CSRF hash
$this->_csrf_set_hash();
@@ -72,8 +72,7 @@ class CI_Security {
/**
* Verify Cross Site Request Forgery Protection
*
- * @access public
- * @return null
+ * @return object
*/
public function csrf_verify()
{
@@ -84,26 +83,30 @@ class CI_Security {
}
// Do the tokens exist in both the _POST and _COOKIE arrays?
- if ( ! isset($_POST[$this->csrf_token_name]) OR ! isset($_COOKIE[$this->csrf_cookie_name]))
+ if ( ! isset($_POST[$this->_csrf_token_name]) OR
+ ! isset($_COOKIE[$this->_csrf_cookie_name]))
{
$this->csrf_show_error();
}
// Do the tokens match?
- if ($_POST[$this->csrf_token_name] != $_COOKIE[$this->csrf_cookie_name])
+ 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[$this->csrf_token_name]);
+ // We kill this since we're done and we don't want to
+ // polute the _POST array
+ unset($_POST[$this->_csrf_token_name]);
// Nothing should last forever
- unset($_COOKIE[$this->csrf_cookie_name]);
+ unset($_COOKIE[$this->_csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();
log_message('debug', "CSRF token verified ");
+
+ return $this;
}
// --------------------------------------------------------------------
@@ -111,57 +114,68 @@ class CI_Security {
/**
* Set Cross Site Request Forgery Protection Cookie
*
- * @access public
- * @return null
+ * @return object
*/
public function csrf_set_cookie()
{
- $expire = time() + $this->csrf_expire;
+ $expire = time() + $this->_csrf_expire;
$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;
- setcookie($this->csrf_cookie_name, $this->csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);
+ if ($secure_cookie)
+ {
+ $req = isset($_SERVER['HTTPS']) ? $_SERVER['HTTPS'] : FALSE;
+
+ if ( ! $req OR $req == 'off')
+ {
+ return FALSE;
+ }
+ }
+
+ setcookie($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 $this;
}
// --------------------------------------------------------------------
/**
- * Set Cross Site Request Forgery Protection Cookie
+ * Show CSRF Error
*
- * @access private
- * @return null
+ * @return void
*/
- private function _csrf_set_hash()
+ public function csrf_show_error()
{
- if ($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]) AND $_COOKIE[$this->csrf_cookie_name] != '')
- {
- $this->csrf_hash = $_COOKIE[$this->csrf_cookie_name];
- }
- else
- {
- $this->csrf_hash = md5(uniqid(rand(), TRUE));
- }
- }
+ show_error('The action you have requested is not allowed.');
+ }
- return $this->csrf_hash;
+ // --------------------------------------------------------------------
+
+ /**
+ * Get CSRF Hash
+ *
+ * Getter Method
+ *
+ * @return string self::_csrf_hash
+ */
+ public function get_csrf_hash()
+ {
+ return $this->_csrf_hash;
}
// --------------------------------------------------------------------
/**
- * Show CSRF Error
+ * Get CSRF Token Name
*
- * @access public
- * @return null
+ * Getter Method
+ *
+ * @return string self::csrf_token_name
*/
- public function csrf_show_error()
+ public function get_csrf_token_name()
{
- show_error('The action you have requested is not allowed.');
+ return $this->_csrf_token_name;
}
// --------------------------------------------------------------------
@@ -188,7 +202,6 @@ class CI_Security {
* harvested from examining vulnerabilities in other programs:
* http://ha.ckers.org/xss.html
*
- * @access public
* @param mixed string or array
* @return string
*/
@@ -213,35 +226,8 @@ class CI_Security {
*/
$str = remove_invisible_characters($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);
+ // Validate Entities in URLs
+ $str = $this->_validate_entities($str);
/*
* URL Decode
@@ -265,7 +251,7 @@ class CI_Security {
*/
$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
-
+
$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);
/*
@@ -278,9 +264,8 @@ class CI_Security {
*
* This prevents strings like this: ja vascript
* NOTE: we deal with spaces between characters later.
- * NOTE: preg_replace was found to be amazingly slow here on large blocks of data,
- * so we use str_replace.
- *
+ * NOTE: preg_replace was found to be amazingly slow here on
+ * large blocks of data, so we use str_replace.
*/
if (strpos($str, "\t") !== FALSE)
@@ -293,34 +278,23 @@ class CI_Security {
*/
$converted_string = $str;
- /*
- * Not Allowed Under Any Conditions
- */
-
- foreach ($this->never_allowed_str as $key => $val)
- {
- $str = str_replace($key, $val, $str);
- }
-
- foreach ($this->never_allowed_regex as $key => $val)
- {
- $str = preg_replace("#".$key."#i", $val, $str);
- }
+ // Remove Strings that are never allowed
+ $str = $this->_do_never_allowed($str);
/*
* Makes PHP tags safe
*
- * Note: XML tags are inadvertently replaced too:
+ * Note: XML tags are inadvertently replaced too:
*
- * <?xml
+ * <?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.
+ // 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', "&lt;?\\1", $str);
}
else
@@ -333,9 +307,12 @@ class CI_Security {
*
* 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');
+ $words = array(
+ 'javascript', 'expression', 'vbscript', 'script',
+ 'applet', 'alert', 'document', 'write', 'cookie', 'window'
+ );
+
foreach ($words as $word)
{
$temp = '';
@@ -352,8 +329,9 @@ class CI_Security {
/*
* 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
+ * 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
{
@@ -374,30 +352,12 @@ class CI_Security {
$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
}
}
- while ($original != $str);
+ while($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.
- *
- */
- $event_handlers = array('[^a-z_\-]on\w*','xmlns');
-
- if ($is_image === TRUE)
- {
- /*
- * Adobe Photoshop puts XML metadata into JFIF images, including namespacing,
- * so we have to allow this for images. -Paul
- */
- unset($event_handlers[array_search('xmlns', $event_handlers)]);
- }
-
- $str = preg_replace("#<([^><]+?)(".implode('|', $event_handlers).")(\s*=\s*[^><]*)([><]*)#i", "<\\1\\4", $str);
+ // Remove evil attributes such as style, onclick and xmlns
+ $str = $this->_remove_evil_attributes($str, $is_image);
/*
* Sanitize naughty HTML elements
@@ -407,7 +367,6 @@ class CI_Security {
*
* So this: <blink>
* Becomes: &lt;blink&gt;
- *
*/
$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);
@@ -423,45 +382,28 @@ class CI_Security {
*
* For example: eval('some code')
* Becomes: eval&#40;'some code'&#41;
- *
*/
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2&#40;\\3&#41;", $str);
- /*
- * Final clean up
- *
- * This adds a bit of extra precaution in case
- * something got through the above filters
- *
- */
- foreach ($this->never_allowed_str as $key => $val)
- {
- $str = str_replace($key, $val, $str);
- }
- foreach ($this->never_allowed_regex as $key => $val)
- {
- $str = preg_replace("#".$key."#i", $val, $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.
+ * 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 ($is_image === TRUE)
{
- if ($str == $converted_string)
- {
- return TRUE;
- }
- else
- {
- return FALSE;
- }
+ return ($str == $converted_string) ? TRUE: FALSE;
}
log_message('debug', "XSS Filtering completed");
@@ -473,59 +415,208 @@ class CI_Security {
/**
* Random Hash for protecting URLs
*
- * @access public
* @return string
*/
public function xss_hash()
{
- if ($this->xss_hash == '')
+ if ($this->_xss_hash == '')
{
if (phpversion() >= 4.2)
+ {
mt_srand();
+ }
else
+ {
mt_srand(hexdec(substr(md5(microtime()), -8)) & 0x7fffffff);
+ }
- $this->xss_hash = md5(time() + mt_rand(0, 1999999999));
+ $this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
}
- return $this->xss_hash;
+ return $this->_xss_hash;
}
// --------------------------------------------------------------------
/**
+ * HTML Entities Decode
+ *
+ * This function is a replacement for html_entity_decode()
+ *
+ * In some versions of PHP the native function does not work
+ * when UTF-8 is the specified character set, so this gives us
+ * a work-around. More info here:
+ * http://bugs.php.net/bug.php?id=25670
+ *
+ * NOTE: html_entity_decode() has a bug in some PHP versions when UTF-8 is the
+ * character set, and the PHP developers said they were not back porting the
+ * fix to versions other than PHP 5.x.
+ *
+ * @param string
+ * @param string
+ * @return string
+ */
+ public function entity_decode($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'))
+ {
+ $str = html_entity_decode($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);
+ }
+
+ // Numeric Entities
+ $str = preg_replace('~&#x(0*[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 $str;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Filename Security
+ *
+ * @param string
+ * @return string
+ */
+ public function sanitize_filename($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, '', $str));
+ }
+
+ // ----------------------------------------------------------------
+
+ /**
* Compact Exploded Words
*
* Callback function for xss_clean() to remove whitespace from
* things like j a v a s c r i p t
*
- * @access private
* @param type
* @return type
*/
- private function _compact_exploded_words($matches)
+ 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
+ $evil_attributes = array('on\w*', 'style', 'xmlns');
+
+ if ($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 {
+ $str = preg_replace(
+ "#<(/?[^><]+?)([^A-Za-z\-])(".implode('|', $evil_attributes).")(\s*=\s*)([\"][^>]*?[\"]|[\'][^>]*?[\']|[^>]*?)([\s><])([><]*)#i",
+ "<$1$6",
+ $str, -1, $count
+ );
+ } while ($count);
+
+ return $str;
+ }
+
+ // --------------------------------------------------------------------
/**
* Sanitize Naughty HTML
*
* Callback function for xss_clean() to remove naughty HTML elements
*
- * @access private
* @param array
* @return string
*/
- private function _sanitize_naughty_html($matches)
+ protected function _sanitize_naughty_html($matches)
{
// encode opening brace
$str = '&lt;'.$matches[1].$matches[2].$matches[3];
// encode captured opening or closing brace to prevent recursive vectors
- $str .= str_replace(array('>', '<'), array('&gt;', '&lt;'), $matches[4]);
+ $str .= str_replace(array('>', '<'), array('&gt;', '&lt;'),
+ $matches[4]);
return $str;
}
@@ -540,16 +631,18 @@ class CI_Security {
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on link-heavy strings
*
- * @access private
* @param array
* @return string
*/
- private function _js_link_removal($match)
+ protected function _js_link_removal($match)
{
$attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
- return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
+
+ return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
}
+ // --------------------------------------------------------------------
+
/**
* JS Image Removal
*
@@ -558,14 +651,14 @@ class CI_Security {
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on image tag heavy strings
*
- * @access private
* @param array
* @return string
*/
- private function _js_img_removal($match)
+ protected function _js_img_removal($match)
{
$attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
- return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
+
+ return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
}
// --------------------------------------------------------------------
@@ -575,11 +668,10 @@ class CI_Security {
*
* Used as a callback for XSS Clean
*
- * @access private
* @param array
* @return string
*/
- private function _convert_attribute($match)
+ protected function _convert_attribute($match)
{
return str_replace(array('>', '<', '\\'), array('&gt;', '&lt;', '\\\\'), $match[0]);
}
@@ -591,11 +683,10 @@ class CI_Security {
*
* Filters tag attributes for consistency and safety
*
- * @access private
* @param string
* @return string
*/
- private function _filter_attributes($str)
+ protected function _filter_attributes($str)
{
$out = '';
@@ -617,118 +708,109 @@ class CI_Security {
*
* Used as a callback for XSS Clean
*
- * @access private
* @param array
* @return string
*/
- private function _decode_entity($match)
+ protected function _decode_entity($match)
{
return $this->entity_decode($match[0], strtoupper(config_item('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
+ * Validate URL entities
*
- * 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.
+ * Called by xss_clean()
*
- * @access public
- * @param string
- * @param string
- * @return string
+ * @param string
+ * @return string
*/
- public function entity_decode($str, $charset='UTF-8')
+ protected function _validate_entities($str)
{
- if (stristr($str, '&') === FALSE) return $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);
- // 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.
+ /*
+ * 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", $str);
- if (function_exists('html_entity_decode') && (strtolower($charset) != 'utf-8' OR is_php('5.0.0')))
- {
- $str = html_entity_decode($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);
- }
+ /*
+ * 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);
- // Numeric Entities
- $str = preg_replace('~&#x(0*[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);
+ /*
+ * Un-Protect GET variables in URLs
+ */
+ $str = str_replace($this->xss_hash(), '&', $str);
+
+ return $str;
+ }
- // Literal Entities - Slightly slow so we do another check
- if (stristr($str, '&') === FALSE)
+ // ----------------------------------------------------------------------
+
+ /**
+ * Do Never Allowed
+ *
+ * A utility function for xss_clean()
+ *
+ * @param string
+ * @return string
+ */
+ protected function _do_never_allowed($str)
+ {
+ foreach ($this->_never_allowed_str as $key => $val)
{
- $str = strtr($str, array_flip(get_html_translation_table(HTML_ENTITIES)));
+ $str = str_replace($key, $val, $str);
}
+ foreach ($this->_never_allowed_regex as $key => $val)
+ {
+ $str = preg_replace("#".$key."#i", $val, $str);
+ }
+
return $str;
}
// --------------------------------------------------------------------
/**
- * Filename Security
+ * Set Cross Site Request Forgery Protection Cookie
*
- * @access public
- * @param string
* @return string
*/
- public function sanitize_filename($str, $relative_path = FALSE)
+ protected function _csrf_set_hash()
{
- $bad = array(
- "../",
- "<!--",
- "-->",
- "<",
- ">",
- "'",
- '"',
- '&',
- '$',
- '#',
- '{',
- '}',
- '[',
- ']',
- '=',
- ';',
- '?',
- "%20",
- "%22",
- "%3c", // <
- "%253c", // <
- "%3e", // >
- "%0e", // >
- "%28", // (
- "%29", // )
- "%2528", // (
- "%26", // &
- "%24", // $
- "%3f", // ?
- "%3b", // ;
- "%3d" // =
- );
-
- if ( ! $relative_path)
+ if ($this->_csrf_hash == '')
{
- $bad[] = './';
- $bad[] = '/';
+ // If the cookie exists we will use it's value.
+ // We don't necessarily want to regenerate it with
+ // each page load since a page could contain embedded
+ // sub-pages causing this feature to fail
+ if (isset($_COOKIE[$this->_csrf_cookie_name]) &&
+ $_COOKIE[$this->_csrf_cookie_name] != '')
+ {
+ return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
+ }
+
+ return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
}
- return stripslashes(str_replace($bad, '', $str));
+ return $this->_csrf_hash;
}
}