user_guide/libraries/security.html - code-igniter-v3-giggi - Gitiles

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <title>Security Class : CodeIgniter User Guide</title>

 <style type='text/css' media='all'>@import url('../userguide.css');</style>
 <link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />

 <script type="text/javascript" src="../nav/nav.js"></script>
 <script type="text/javascript" src="../nav/prototype.lite.js"></script>
 <script type="text/javascript" src="../nav/moo.fx.js"></script>
 <script type="text/javascript" src="../nav/user_guide_menu.js"></script>

 <meta http-equiv='expires' content='-1' />
 <meta http-equiv= 'pragma' content='no-cache' />
 <meta name='robots' content='all' />
 <meta name='author' content='ExpressionEngine Dev Team' />
 <meta name='description' content='CodeIgniter User Guide' />

 </head>
 <body>

 <!-- START NAVIGATION -->
 <div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
 <div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
 <div id="masthead">
 <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
 <tr>
 <td><h1>CodeIgniter User Guide Version 2.0.2</h1></td>
 <td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
 </tr>
 </table>
 </div>
 <!-- END NAVIGATION -->


 <!-- START BREADCRUMB -->
 <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
 <tr>
 <td id="breadcrumb">
 <a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
 <a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
 Security Class
 </td>
 <td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide&nbsp; <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" />&nbsp;<input type="submit" class="submit" name="sa" value="Go" /></form></td>
 </tr>
 </table>
 <!-- END BREADCRUMB -->

 <br clear="all" />


 <!-- START CONTENT -->
 <div id="content">


 <h1>Security Class</h1>

 <p>The Security Class contains methods that help you create a secure application, processing input data for security.</p>

 <h2>XSS Filtering</h2>

 <p>CodeIgniter comes with a Cross Site Scripting Hack prevention filter which can either run automatically to filter
 all POST and COOKIE data that is encountered, or you can run it on a per item basis.  By default it does <strong>not</strong>
 run globally since it requires a bit of processing overhead, and since you may not need it in all cases.</p>

 <p>The XSS filter looks for commonly used techniques to trigger Javascript or other types of code that attempt to hijack cookies
 or do other malicious things.  If anything disallowed is encountered it is rendered safe by converting the data to character entities.</p>

 <p>
 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 since it requires a fair amount of processing overhead.</p>


 <p>To filter data through the XSS filter use this function:</p>

 <h2>$this->security->xss_clean()</h2>

 <p>Here is an usage example:</p>

 <code>$data = $this->security->xss_clean($data);</code>

 <p>If you want the filter to run automatically every time it encounters POST or COOKIE data you can enable it by opening your
 <kbd>application/config/config.php</kbd> file and setting this:</p>

 <code>$config['global_xss_filtering'] = TRUE;</code>

 <p>Note: If you use the form validation class, it gives you the option of XSS filtering as well.</p>

 <p>An optional second parameter, <dfn>is_image</dfn>, allows this function to be used to test images for potential XSS attacks, useful for file upload security.  When this second parameter is set to <dfn>TRUE</dfn>, instead of returning an altered string, the function returns TRUE if the image is safe, and FALSE if it contained potentially malicious information that a browser may attempt to execute.</p>

 <code>if ($this->security->xss_clean($file, TRUE) === FALSE)<br />
 {<br />
 &nbsp;&nbsp;&nbsp;&nbsp;// file failed the XSS test<br />
 }</code>


 <h2>$this->security->sanitize_filename()</h2>

 <p>When accepting filenames from user input, it is best to sanitize them to prevent directory traversal and other security related issues.  To do so, use the <dfn>sanitize_filename()</dfn> method of the Security class.  Here is an example:</p>

 <code>$filename = $this->security->sanitize_filename($this->input->post('filename'));</code>

 <p>If it is acceptable for the user input to include relative paths, e.g. <kbd>file/in/some/approved/folder.txt</kbd>, you can set the second optional parameter,
 	<samp>$relative_path</samp> to TRUE.</p>

 <code>$filename = $this->security->sanitize_filename($this->input->post('filename'), TRUE);</code>

 <!-- @todo write docs for CSRF methods -->

 <h2>Cross-site request forgery (CSRF)</h2>

 <p>You can enable csrf protection by opening your <kbd>application/config/config.php</kbd> file and setting this:</p>
 <code>$config['csrf_protection'] = TRUE;</code>

 <p>If you use the <a href="../helpers/form_helper.html">form helper</a> the <var>form_open()</var> function will automatically insert a hidden csrf field in your forms.</p>

 </div>
 <!-- END CONTENT -->


 <div id="footer">
 <p>
 Previous Topic:&nbsp;&nbsp;<a href="pagination.html">Pagination Class</a>
 &nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
 <a href="#top">Top of Page</a>&nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
 <a href="../index.html">User Guide Home</a>&nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
 Next Topic:&nbsp;&nbsp;<a href="sessions.html">Session Class</a>
 </p>
 <p><a href="http://codeigniter.com">CodeIgniter</a> &nbsp;&middot;&nbsp; Copyright &#169; 2006 - 2011 &nbsp;&middot;&nbsp; <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
 </div>

 </body>
 </html>
	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
	<head>

	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<title>Security Class : CodeIgniter User Guide</title>

	<style type='text/css' media='all'>@import url('../userguide.css');</style>
	<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />

	<script type="text/javascript" src="../nav/nav.js"></script>
	<script type="text/javascript" src="../nav/prototype.lite.js"></script>
	<script type="text/javascript" src="../nav/moo.fx.js"></script>
	<script type="text/javascript" src="../nav/user_guide_menu.js"></script>

	<meta http-equiv='expires' content='-1' />
	<meta http-equiv= 'pragma' content='no-cache' />
	<meta name='robots' content='all' />
	<meta name='author' content='ExpressionEngine Dev Team' />
	<meta name='description' content='CodeIgniter User Guide' />

	</head>
	<body>

	<!-- START NAVIGATION -->
	<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
	<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
	<div id="masthead">
	<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
	<tr>
	<td><h1>CodeIgniter User Guide Version 2.0.2</h1></td>
	<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
	</tr>
	</table>
	</div>
	<!-- END NAVIGATION -->


	<!-- START BREADCRUMB -->
	<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
	<tr>
	<td id="breadcrumb">
	<a href="http://codeigniter.com/">CodeIgniter Home</a>  ›
	<a href="../index.html">User Guide Home</a>  ›
	Security Class
	</td>
	<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide  <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
	</tr>
	</table>
	<!-- END BREADCRUMB -->

	<br clear="all" />


	<!-- START CONTENT -->
	<div id="content">


	<h1>Security Class</h1>

	<p>The Security Class contains methods that help you create a secure application, processing input data for security.</p>

	<h2>XSS Filtering</h2>

	<p>CodeIgniter comes with a Cross Site Scripting Hack prevention filter which can either run automatically to filter
	all POST and COOKIE data that is encountered, or you can run it on a per item basis. By default it does <strong>not</strong>
	run globally since it requires a bit of processing overhead, and since you may not need it in all cases.</p>

	<p>The XSS filter looks for commonly used techniques to trigger Javascript or other types of code that attempt to hijack cookies
	or do other malicious things. If anything disallowed is encountered it is rendered safe by converting the data to character entities.</p>

	<p>
	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 since it requires a fair amount of processing overhead.</p>


	<p>To filter data through the XSS filter use this function:</p>

	<h2>$this->security->xss_clean()</h2>

	<p>Here is an usage example:</p>

	<code>$data = $this->security->xss_clean($data);</code>

	<p>If you want the filter to run automatically every time it encounters POST or COOKIE data you can enable it by opening your
	<kbd>application/config/config.php</kbd> file and setting this:</p>

	<code>$config['global_xss_filtering'] = TRUE;</code>

	<p>Note: If you use the form validation class, it gives you the option of XSS filtering as well.</p>

	<p>An optional second parameter, <dfn>is_image</dfn>, allows this function to be used to test images for potential XSS attacks, useful for file upload security. When this second parameter is set to <dfn>TRUE</dfn>, instead of returning an altered string, the function returns TRUE if the image is safe, and FALSE if it contained potentially malicious information that a browser may attempt to execute.</p>

	<code>if ($this->security->xss_clean($file, TRUE) === FALSE)<br />
	{<br />
	// file failed the XSS test<br />
	}</code>


	<h2>$this->security->sanitize_filename()</h2>

	<p>When accepting filenames from user input, it is best to sanitize them to prevent directory traversal and other security related issues. To do so, use the <dfn>sanitize_filename()</dfn> method of the Security class. Here is an example:</p>

	<code>$filename = $this->security->sanitize_filename($this->input->post('filename'));</code>

	<p>If it is acceptable for the user input to include relative paths, e.g. <kbd>file/in/some/approved/folder.txt</kbd>, you can set the second optional parameter,
	<samp>$relative_path</samp> to TRUE.</p>

	<code>$filename = $this->security->sanitize_filename($this->input->post('filename'), TRUE);</code>

	<!-- @todo write docs for CSRF methods -->

	<h2>Cross-site request forgery (CSRF)</h2>

	<p>You can enable csrf protection by opening your <kbd>application/config/config.php</kbd> file and setting this:</p>
	<code>$config['csrf_protection'] = TRUE;</code>

	<p>If you use the <a href="../helpers/form_helper.html">form helper</a> the <var>form_open()</var> function will automatically insert a hidden csrf field in your forms.</p>

	</div>
	<!-- END CONTENT -->


	<div id="footer">
	<p>
	Previous Topic:  <a href="pagination.html">Pagination Class</a>
	·
	<a href="#top">Top of Page</a>   ·
	<a href="../index.html">User Guide Home</a>   ·
	Next Topic:  <a href="sessions.html">Session Class</a>
	</p>
	<p><a href="http://codeigniter.com">CodeIgniter</a>  ·  Copyright © 2006 - 2011  ·  <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
	</div>

	</body>
	</html>