The Security Class contains methods that help you create a secure application, processing input data for security.
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 not run globally since it requires a bit of processing overhead, and since you may not need it in all cases.
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.
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.
To filter data through the XSS filter use the xss_clean() method:
$data = $this->security->xss_clean($data);
If you want the filter to run automatically every time it encounters POST or COOKIE data you can enable it by opening your application/config/config.php file and setting this:
$config['global_xss_filtering'] = TRUE;
An optional second parameter, is_image, allows this function to be used to test images for potential XSS attacks, useful for file upload security. When this second parameter is set to TRUE, instead of returning an altered string, the function returns TRUE if the image is safe, and FALSE if it contained potentially malicious information that a browser may attempt to execute.
if ($this->security->xss_clean($file, TRUE) === FALSE)
{
// file failed the XSS test
}
You can enable CSRF protection by altering your application/config/config.php file in the following way:
$config['csrf_protection'] = TRUE;
If you use the :doc:`form helper <../helpers/form_helper>`, then
:func:`form_open()` will automatically insert a hidden csrf field in
your forms. If not, then you can use get_csrf_token_name()
and get_csrf_hash()
$csrf = array(
'name' => $this->security->get_csrf_token_name(),
'hash' => $this->security->get_csrf_hash()
);
...
<input type="hidden" name="<?=$csrf['name'];?>" value="<?=$csrf['hash'];?>" />
Tokens may be either regenerated on every submission (default) or kept the same throughout the life of the CSRF cookie. The default regeneration of tokens provides stricter security, but may result in usability concerns as other tokens become invalid (back/forward navigation, multiple tabs/windows, asynchronous actions, etc). You may alter this behavior by editing the following config parameter
$config['csrf_regeneration'] = TRUE;
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:
$config['csrf_exclude_uris'] = array('api/person/add');
Regular expressions are also supported (case-insensitive):
$config['csrf_exclude_uris'] = array(
'api/record/[0-9]+',
'api/title/[a-z]+'
);
.. php:class:: CI_Security
.. php:method:: xss_clean($str[, $is_image = FALSE])
:param mixed $str: Input string or an array of strings
:returns: XSS-clean data
:rtype: mixed
Tries to remove XSS exploits from the input data and returns the cleaned string.
If the optional second parameter is set to true, it will return boolean TRUE if the image is safe to use and FALSE if malicious data was detected in it.
.. php:method:: sanitize_filename($str[, $relative_path = FALSE])
:param string $str: File name/path
:param bool $relative_path: Whether to preserve any directories in the file path
:returns: Sanitized file name/path
:rtype: string
Tries to sanitize filenames in order to prevent directory traversal attempts
and other security threats, which is particularly useful for files that were supplied via user input.
::
$filename = $this->security->sanitize_filename($this->input->post('filename'));
If it is acceptable for the user input to include relative paths, e.g.
*file/in/some/approved/folder.txt*, you can set the second optional parameter, ``$relative_path`` to TRUE.
::
$filename = $this->security->sanitize_filename($this->input->post('filename'), TRUE);
.. php:method:: get_csrf_token_name()
:returns: CSRF token name
:rtype: string
Returns the CSRF token name (the ``$config['csrf_token_name']`` value).
.. php:method:: get_csrf_hash()
:returns: CSRF hash
:rtype: string
Returns the CSRF hash value. Useful in combination with ``get_csrf_token_name()``
for manually building forms or sending valid AJAX POST requests.
.. php:method:: entity_decode($str[, $charset = NULL])
:param string $str: Input string
:param string $charset: Character set of the input string
:returns: Entity-decoded string
:rtype: string
This method acts a lot like PHP's own native ``html_entity_decode()`` function in ENT_COMPAT mode, only
it tries to detect HTML entities that don't end in a semicolon because some browsers allow that.
If the ``$charset`` parameter is left empty, then your configured ``$config['charset']`` value will be used.
.. php:method:: get_random_bytes($length)
:param int $length: Output length
:returns: A binary stream of random bytes or FALSE on failure
:rtype: string
A convenience method for getting proper random bytes via ``mcrypt_create_iv()``,
``/dev/urandom`` or ``openssl_random_pseudo_bytes()`` (in that order), if one
of them is available.
Used for generating CSRF and XSS tokens.
.. note:: The output is NOT guaranteed to be cryptographically secure,
just the best attempt at that.