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Derek Jonesb8c038a2011-08-20 08:57:14 -0500[diff] [blame]31<td><h1>CodeIgniter User Guide Version 2.0.3</h1></td>
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59<h1>Security Class</h1>
60
61<p>The Security Class contains methods that help you create a secure application, processing input data for security.</p>
62
63<h2>XSS Filtering</h2>
64
65<p>CodeIgniter comes with a Cross Site Scripting Hack prevention filter which can either run automatically to filter
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]66all POST and COOKIE data that is encountered, or you can run it on a per item basis. By default it does <strong>not</strong>
Derek Jones9898b892010-03-10 14:04:17 -0600[diff] [blame]67run globally since it requires a bit of processing overhead, and since you may not need it in all cases.</p>
68
69<p>The XSS filter looks for commonly used techniques to trigger Javascript or other types of code that attempt to hijack cookies
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]70or do other malicious things. If anything disallowed is encountered it is rendered safe by converting the data to character entities.</p>
Derek Jones9898b892010-03-10 14:04:17 -0600[diff] [blame]71
72<p>
73Note: 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>
74
75
76<p>To filter data through the XSS filter use this function:</p>
77
78<h2>$this->security->xss_clean()</h2>
79
80<p>Here is an usage example:</p>
81
82<code>$data = $this->security->xss_clean($data);</code>
83
84<p>If you want the filter to run automatically every time it encounters POST or COOKIE data you can enable it by opening your
85<kbd>application/config/config.php</kbd> file and setting this:</p>
86
87<code>$config['global_xss_filtering'] = TRUE;</code>
88
89<p>Note: If you use the form validation class, it gives you the option of XSS filtering as well.</p>
90
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]91<p>An optional second parameter, <dfn>is_image</dfn>, allows this function to be used to test images for potential XSS attacks, useful for file upload security. When this second parameter is set to <dfn>TRUE</dfn>, instead of returning an altered string, the function returns TRUE if the image is safe, and FALSE if it contained potentially malicious information that a browser may attempt to execute.</p>
Derek Jones9898b892010-03-10 14:04:17 -0600[diff] [blame]92
93<code>if ($this->security->xss_clean($file, TRUE) === FALSE)<br />
94{<br />
95&nbsp;&nbsp;&nbsp;&nbsp;// file failed the XSS test<br />
96}</code>
97
98
99<h2>$this->security->sanitize_filename()</h2>
100
Derek Jones4b9c6292011-07-01 17:40:48 -0500[diff] [blame]101<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>
Derek Jones9898b892010-03-10 14:04:17 -0600[diff] [blame]102
103<code>$filename = $this->security->sanitize_filename($this->input->post('filename'));</code>
104
Derek Jones2ef37592010-10-06 17:51:59 -0500[diff] [blame]105<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,
106 <samp>$relative_path</samp> to TRUE.</p>
Eric Barnes1c97d562011-01-28 13:34:50 -0500[diff] [blame]107
Derek Jones2ef37592010-10-06 17:51:59 -0500[diff] [blame]108<code>$filename = $this->security->sanitize_filename($this->input->post('filename'), TRUE);</code>
109
Derek Jones9898b892010-03-10 14:04:17 -0600[diff] [blame]110<!-- @todo write docs for CSRF methods -->
111
Eric Barnes1c97d562011-01-28 13:34:50 -0500[diff] [blame]112<h2>Cross-site request forgery (CSRF)</h2>
113
114<p>You can enable csrf protection by opening your <kbd>application/config/config.php</kbd> file and setting this:</p>
115<code>$config['csrf_protection'] = TRUE;</code>
116
117<p>If you use the <a href="../helpers/form_helper.html">form helper</a> the <var>form_open()</var> function will automatically insert a hidden csrf field in your forms.</p>
118
Alex Bilbie87c74c82011-08-21 16:28:43 +0100[diff] [blame^]119<p>Select URIs can be whitelisted from csrf protection (for example API endpoints expecting externally POSTed content). You can add these URIs by editing the 'csrf_exclude_uris' config parameter:</p>
120<code>$config['csrf_exclude_uris'] = array('api/person/add');</code>
121
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