Fix for issue #149: CSRF protection URI whitelisting

application/config/config.php

@@ -292,11 +292,13 @@
 | 'csrf_token_name' = The token name
 | 'csrf_cookie_name' = The cookie name
 | 'csrf_expire' = The number in seconds the token should expire.
+| 'csrf_exclude_uris' = Array of URIs which ignore CSRF checks
 */
 $config['csrf_protection'] = FALSE;
 $config['csrf_token_name'] = 'csrf_test_name';
 $config['csrf_cookie_name'] = 'csrf_cookie_name';
 $config['csrf_expire'] = 7200;
+$config['csrf_exclude_uris'] = array();
 
 /*
 |--------------------------------------------------------------------------

system/core/Security.php

@@ -93,6 +93,16 @@ public function csrf_verify()
 		{
 			return $this->csrf_set_cookie();
 		}
+
+		// Check if URI has been whitelisted from CSRF checks
+		if ($exclude_uris = config_item('csrf_exclude_uris'))
+		{
+			$uri = load_class('URI', 'core');
+			if (in_array($uri->uri_string(), $exclude_uris))
+			{
+				return $this;
+			}
+		}
 
 		// Do the tokens exist in both the _POST and _COOKIE arrays?
 		if ( ! isset($_POST[$this->_csrf_token_name]) OR 
@@ -116,7 +126,7 @@ public function csrf_verify()
 		$this->_csrf_set_hash();
 		$this->csrf_set_cookie();
 
-		log_message('debug', "CSRF token verified ");
+		log_message('debug', "CSRF token verified");
 
 		return $this;
 	}

user_guide/changelog.html

@@ -75,6 +75,7 @@ <h2>Version 2.0.3</h2>
 			<li>Visual updates to the welcome_message view file and default error templates. Thanks to <a href="https://bitbucket.org/danijelb">danijelb</a> for the pull request.</li>
 			<li class="reactor">Added <samp>insert_batch()</samp> function to the PostgreSQL database driver.  Thanks to epallerols for the patch.</li>
 			<li class="reactor">Added "application/x-csv" to mimes.php.</li>
+			<li class="reactor">Added CSRF protection URI whitelisting.</li>
 			<li>Fixed a bug where <a href="libraries/email.html">Email library</a> attachments with a "." in the name would using invalid MIME-types.</li>
 		</ul>
 	</li>

user_guide/libraries/security.html

@@ -116,6 +116,9 @@ <h2>Cross-site request forgery (CSRF)</h2>
 
 <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>
 
+<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>
+<code>$config['csrf_exclude_uris'] = array('api/person/add');</code>
+
 </div>
 <!-- END CONTENT -->