Merge branch 'develop' of git://github.com/bcit-ci/CodeIgniter into develop

1 files changed, 206 insertions, 133 deletions

diff --git a/system/core/Security.php b/system/core/Security.php
index 7c5199255..4ad550fff 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -6,7 +6,7 @@
  *
  * This content is released under the MIT License (MIT)
  *
- * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -28,10 +28,10 @@
  *
  * @package	CodeIgniter
  * @author	EllisLab Dev Team
- * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
- * @copyright	Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
  * @license	http://opensource.org/licenses/MIT	MIT License
- * @link	http://codeigniter.com
+ * @link	https://codeigniter.com
  * @since	Version 1.0.0
  * @filesource
  */
@@ -44,7 +44,7 @@ defined('BASEPATH') OR exit('No direct script access allowed');
  * @subpackage	Libraries
  * @category	Security
  * @author		EllisLab Dev Team
- * @link		http://codeigniter.com/user_guide/libraries/security.html
+ * @link		https://codeigniter.com/user_guide/libraries/security.html
  */
 class CI_Security {
 
@@ -133,15 +133,16 @@ class CI_Security {
 	 * @var	array
 	 */
 	protected $_never_allowed_str =	array(
-		'document.cookie'	=> '[removed]',
-		'document.write'	=> '[removed]',
-		'.parentNode'		=> '[removed]',
-		'.innerHTML'		=> '[removed]',
-		'-moz-binding'		=> '[removed]',
-		'<!--'				=> '&lt;!--',
-		'-->'				=> '--&gt;',
-		'<![CDATA['			=> '&lt;![CDATA[',
-		'<comment>'			=> '&lt;comment&gt;'
+		'document.cookie' => '[removed]',
+		'document.write'  => '[removed]',
+		'.parentNode'     => '[removed]',
+		'.innerHTML'      => '[removed]',
+		'-moz-binding'    => '[removed]',
+		'<!--'            => '&lt;!--',
+		'-->'             => '--&gt;',
+		'<![CDATA['       => '&lt;![CDATA[',
+		'<comment>'	  => '&lt;comment&gt;',
+		'<%'              => '&lt;&#37;'
 	);
 
 	/**
@@ -166,10 +167,12 @@ class CI_Security {
 	 *
 	 * @return	void
 	 */
-	public function __construct()
+	public function __construct($charset)
 	{
+		$this->charset = $charset;
+
 		// Is CSRF protection enabled?
-		if (config_item('csrf_protection'))
+		if (config_item('csrf_protection') && ! is_cli())
 		{
 			// CSRF config
 			foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
@@ -188,10 +191,9 @@ class CI_Security {
 
 			// Set the CSRF hash
 			$this->_csrf_set_hash();
+			$this->csrf_verify();
 		}
 
-		$this->charset = strtoupper(config_item('charset'));
-
 		log_message('info', 'Security Class Initialized');
 	}
 
@@ -223,14 +225,11 @@ class CI_Security {
 			}
 		}
 
-		// Do the tokens exist in both the _POST and _COOKIE arrays?
-		if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name])
-			OR $_POST[$this->_csrf_token_name] !== $_COOKIE[$this->_csrf_cookie_name]) // Do the tokens match?
-		{
-			$this->csrf_show_error();
-		}
+		// Check CSRF token validity, but don't error on mismatch just yet - we'll want to regenerate
+		$valid = isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name])
+			&& hash_equals($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]);
 
-		// We kill this since we're done and we don't want to polute the _POST array
+		// We kill this since we're done and we don't want to pollute the _POST array
 		unset($_POST[$this->_csrf_token_name]);
 
 		// Regenerate on every submission?
@@ -244,6 +243,11 @@ class CI_Security {
 		$this->_csrf_set_hash();
 		$this->csrf_set_cookie();
 
+		if ($valid !== TRUE)
+		{
+			$this->csrf_show_error();
+		}
+
 		log_message('info', 'CSRF token verified');
 		return $this;
 	}
@@ -371,11 +375,17 @@ class CI_Security {
 		 *
 		 * Note: Use rawurldecode() so it does not remove plus signs
 		 */
-		do
+		if (stripos($str, '%') !== false)
 		{
-			$str = rawurldecode($str);
+			do
+			{
+				$oldstr = $str;
+				$str = rawurldecode($str);
+				$str = preg_replace_callback('#%(?:\s*[0-9a-f]){2,}#i', array($this, '_urldecodespaces'), $str);
+			}
+			while ($oldstr !== $str);
+			unset($oldstr);
 		}
-		while (preg_match('/%[0-9a-f]{2,}/i', $str));
 
 		/*
 		 * Convert character entities to ASCII
@@ -436,7 +446,7 @@ class CI_Security {
 		$words = array(
 			'javascript', 'expression', 'vbscript', 'jscript', 'wscript',
 			'vbs', 'script', 'base64', 'applet', 'alert', 'document',
-			'write', 'cookie', 'window', 'confirm', 'prompt'
+			'write', 'cookie', 'window', 'confirm', 'prompt', 'eval'
 		);
 
 		foreach ($words as $word)
@@ -466,7 +476,7 @@ class CI_Security {
 
 			if (preg_match('/<a/i', $str))
 			{
-				$str = preg_replace_callback('#<a[^a-z0-9>]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str);
+				$str = preg_replace_callback('#<a(?:rea)?[^a-z0-9>]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str);
 			}
 
 			if (preg_match('/<img/i', $str))
@@ -480,12 +490,8 @@ class CI_Security {
 			}
 		}
 		while ($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
 		 *
@@ -495,8 +501,29 @@ class CI_Security {
 		 * So this: <blink>
 		 * Becomes: &lt;blink&gt;
 		 */
-		$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);
+		$pattern = '#'
+			.'<((?<slash>/*\s*)((?<tagName>[a-z0-9]+)(?=[^a-z0-9]|$)|.+)' // tag start and name, followed by a non-tag character
+			.'[^\s\042\047a-z0-9>/=]*' // a valid attribute character immediately after the tag would count as a separator
+			// optional attributes
+			.'(?<attributes>(?:[\s\042\047/=]*' // non-attribute characters, excluding > (tag close) for obvious reasons
+			.'[^\s\042\047>/=]+' // attribute characters
+			// optional attribute-value
+				.'(?:\s*=' // attribute-value separator
+					.'(?:[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*))' // single, double or non-quoted value
+				.')?' // end optional attribute-value group
+			.')*)' // end optional attributes group
+			.'[^>]*)(?<closeTag>\>)?#isS';
+
+		// Note: It would be nice to optimize this for speed, BUT
+		//       only matching the naughty elements here results in
+		//       false positives and in turn - vulnerabilities!
+		do
+		{
+			$old_str = $str;
+			$str = preg_replace_callback($pattern, array($this, '_sanitize_naughty_html'), $str);
+		}
+		while ($old_str !== $str);
+		unset($old_str);
 
 		/*
 		 * Sanitize naughty scripting elements
@@ -510,9 +537,11 @@ class CI_Security {
 		 * For example:	eval('some code')
 		 * Becomes:	eval&#40;'some code'&#41;
 		 */
-		$str = preg_replace('#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si',
-					'\\1\\2&#40;\\3&#41;',
-					$str);
+		$str = preg_replace(
+			'#(alert|prompt|confirm|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
@@ -574,6 +603,22 @@ class CI_Security {
 			return FALSE;
 		}
 
+		if (function_exists('random_bytes'))
+		{
+			try
+			{
+				// The cast is required to avoid TypeError
+				return random_bytes((int) $length);
+			}
+			catch (Exception $e)
+			{
+				// If random_bytes() can't do the job, we can't either ...
+				// There's no point in using fallbacks.
+				log_message('error', $e->getMessage());
+				return FALSE;
+			}
+		}
+
 		// Unfortunately, none of the following PRNGs is guaranteed to exist ...
 		if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE)
 		{
@@ -584,7 +629,7 @@ class CI_Security {
 		if (is_readable('/dev/urandom') && ($fp = fopen('/dev/urandom', 'rb')) !== FALSE)
 		{
 			// Try not to waste entropy ...
-			is_php('5.4') && stream_set_chunk_size($fp, $length);
+			stream_set_chunk_size($fp, $length);
 			$output = fread($fp, $length);
 			fclose($fp);
 			if ($output !== FALSE)
@@ -629,10 +674,8 @@ class CI_Security {
 
 		static $_entities;
 
-		isset($charset) OR $charset = $this->charset;
-		$flag = is_php('5.4')
-			? ENT_COMPAT | ENT_HTML5
-			: ENT_COMPAT;
+		isset($charset)   OR $charset = $this->charset;
+		isset($_entities) OR $_entities = array_map('strtolower', get_html_translation_table(HTML_ENTITIES, ENT_COMPAT | ENT_HTML5, $charset));
 
 		do
 		{
@@ -641,27 +684,6 @@ class CI_Security {
 			// Decode standard entities, avoiding false positives
 			if (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[':'] = '&colon;';
-						$_entities['('] = '&lpar;';
-						$_entities[')'] = '&rpar;';
-						$_entities["\n"] = '&newline;';
-						$_entities["\t"] = '&tab;';
-					}
-				}
-
 				$replace = array();
 				$matches = array_unique(array_map('strtolower', $matches[0]));
 				foreach ($matches as &$match)
@@ -672,13 +694,13 @@ class CI_Security {
 					}
 				}
 
-				$str = str_ireplace(array_keys($replace), array_values($replace), $str);
+				$str = str_replace(array_keys($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,
+				ENT_COMPAT | ENT_HTML5,
 				$charset
 			);
 		}
@@ -727,7 +749,32 @@ class CI_Security {
 	 */
 	public function strip_image_tags($str)
 	{
-		return preg_replace(array('#<img[\s/]+.*?src\s*=\s*["\'](.+?)["\'].*?\>#', '#<img[\s/]+.*?src\s*=\s*(.+?).*?\>#'), '\\1', $str);
+		return preg_replace(
+			array(
+				'#<img[\s/]+.*?src\s*=\s*(["\'])([^\\1]+?)\\1.*?\>#i',
+				'#<img[\s/]+.*?src\s*=\s*?(([^\s"\'=<>`]+)).*?\>#i'
+			),
+			'\\2',
+			$str
+		);
+	}
+
+	// ----------------------------------------------------------------
+
+	/**
+	 * URL-decode taking spaces into account
+	 *
+	 * @see		https://github.com/bcit-ci/CodeIgniter/issues/4877
+	 * @param	array	$matches
+	 * @return	string
+	 */
+	protected function _urldecodespaces($matches)
+	{
+		$input    = $matches[0];
+		$nospaces = preg_replace('#\s+#', '', $input);
+		return ($nospaces === $input)
+			? $input
+			: rawurldecode($nospaces);
 	}
 
 	// ----------------------------------------------------------------
@@ -750,71 +797,92 @@ class CI_Security {
 	// --------------------------------------------------------------------
 
 	/**
-	 * Remove Evil HTML Attributes (like event handlers and style)
-	 *
-	 * It removes the evil attribute and either:
-	 *
-	 *  - Everything up until a space. For example, everything between the pipes:
-	 *
-	 *	<code>
-	 *		<a |style=document.write('hello');alert('world');| class=link>
-	 *	</code>
-	 *
-	 *  - Everything inside the quotes. For example, everything between the pipes:
+	 * Sanitize Naughty HTML
 	 *
-	 *	<code>
-	 *		<a |style="document.write('hello'); alert('world');"| class="link">
-	 *	</code>
+	 * Callback method for xss_clean() to remove naughty HTML elements.
 	 *
-	 * @param	string	$str		The string to check
-	 * @param	bool	$is_image	Whether the input is an image
-	 * @return	string	The string with the evil attributes removed
+	 * @used-by	CI_Security::xss_clean()
+	 * @param	array	$matches
+	 * @return	string
 	 */
-	protected function _remove_evil_attributes($str, $is_image)
+	protected function _sanitize_naughty_html($matches)
 	{
-		$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime');
+		static $naughty_tags    = array(
+			'alert', 'area', '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'
+		);
 
-		if ($is_image === TRUE)
+		static $evil_attributes = array(
+			'on\w+', 'style', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime'
+		);
+
+		// First, escape unclosed tags
+		if (empty($matches['closeTag']))
+		{
+			return '&lt;'.$matches[1];
+		}
+		// Is the element that we caught naughty? If so, escape it
+		elseif (in_array(strtolower($matches['tagName']), $naughty_tags, TRUE))
 		{
-			/*
-			 * Adobe Photoshop puts XML metadata into JFIF images,
-			 * including namespacing, so we have to allow this for images.
-			 */
-			unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
+			return '&lt;'.$matches[1].'&gt;';
 		}
+		// For other tags, see if their attributes are "evil" and strip those
+		elseif (isset($matches['attributes']))
+		{
+			// We'll store the already fitlered attributes here
+			$attributes = array();
 
-		do {
-			$count = $temp_count = 0;
+			// Attribute-catching pattern
+			$attributes_pattern = '#'
+				.'(?<name>[^\s\042\047>/=]+)' // attribute characters
+				// optional attribute-value
+				.'(?:\s*=(?<value>[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*)))' // attribute-value separator
+				.'#i';
 
-			// replace occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)
-			$str = preg_replace('/(<[^>]+)(?<!\w)('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', '$1[removed]', $str, -1, $temp_count);
-			$count += $temp_count;
+			// Blacklist pattern for evil attribute names
+			$is_evil_pattern = '#^('.implode('|', $evil_attributes).')$#i';
 
-			// find occurrences of illegal attribute strings without quotes
-			$str = preg_replace('/(<[^>]+)(?<!\w)('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', '$1[removed]', $str, -1, $temp_count);
-			$count += $temp_count;
-		}
-		while ($count);
+			// Each iteration filters a single attribute
+			do
+			{
+				// Strip any non-alpha characters that may precede an attribute.
+				// Browsers often parse these incorrectly and that has been a
+				// of numerous XSS issues we've had.
+				$matches['attributes'] = preg_replace('#^[^a-z]+#i', '', $matches['attributes']);
 
-		return $str;
-	}
+				if ( ! preg_match($attributes_pattern, $matches['attributes'], $attribute, PREG_OFFSET_CAPTURE))
+				{
+					// No (valid) attribute found? Discard everything else inside the tag
+					break;
+				}
 
-	// --------------------------------------------------------------------
+				if (
+					// Is it indeed an "evil" attribute?
+					preg_match($is_evil_pattern, $attribute['name'][0])
+					// Or does it have an equals sign, but no value and not quoted? Strip that too!
+					OR (trim($attribute['value'][0]) === '')
+				)
+				{
+					$attributes[] = 'xss=removed';
+				}
+				else
+				{
+					$attributes[] = $attribute[0][0];
+				}
 
-	/**
-	 * Sanitize Naughty HTML
-	 *
-	 * Callback method for xss_clean() to remove naughty HTML elements.
-	 *
-	 * @used-by	CI_Security::xss_clean()
-	 * @param	array	$matches
-	 * @return	string
-	 */
-	protected function _sanitize_naughty_html($matches)
-	{
-		return '&lt;'.$matches[1].$matches[2].$matches[3] // encode opening brace
-			// encode captured opening or closing brace to prevent recursive vectors:
-			.str_replace(array('>', '<'), array('&gt;', '&lt;'), $matches[4]);
+				$matches['attributes'] = substr($matches['attributes'], $attribute[0][1] + strlen($attribute[0][0]));
+			}
+			while ($matches['attributes'] !== '');
+
+			$attributes = empty($attributes)
+				? ''
+				: ' '.implode(' ', $attributes);
+			return '<'.$matches['slash'].$matches['tagName'].$attributes.'>';
+		}
+
+		return $matches[0];
 	}
 
 	// --------------------------------------------------------------------
@@ -834,12 +902,15 @@ class CI_Security {
 	 */
 	protected function _js_link_removal($match)
 	{
-		return str_replace($match[1],
-					preg_replace('#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
-							'',
-							$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
-					),
-					$match[0]);
+		return str_replace(
+			$match[1],
+			preg_replace(
+				'#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|d\s*a\s*t\s*a\s*:)#si',
+				'',
+				$this->_filter_attributes($match[1])
+			),
+			$match[0]
+		);
 	}
 
 	// --------------------------------------------------------------------
@@ -859,12 +930,15 @@ class CI_Security {
 	 */
 	protected function _js_img_removal($match)
 	{
-		return str_replace($match[1],
-					preg_replace('#src=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
-							'',
-							$this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
-					),
-					$match[0]);
+		return str_replace(
+			$match[1],
+			preg_replace(
+				'#src=.*?(?:(?:alert|prompt|confirm|eval)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
+				'',
+				$this->_filter_attributes($match[1])
+			),
+			$match[0]
+		);
 	}
 
 	// --------------------------------------------------------------------
@@ -980,5 +1054,4 @@ class CI_Security {
 
 		return $this->_csrf_hash;
 	}
-
 }