feat: add CSP clearDirective() to clear existing directive

system/HTTP/ContentSecurityPolicy.php

@@ -26,6 +26,31 @@
  */
 class ContentSecurityPolicy
 {
+    /**
+     * CSP directives
+     *
+     * @var array<string, string>
+     */
+    protected array $directives = [
+        'base-uri'        => 'baseURI',
+        'child-src'       => 'childSrc',
+        'connect-src'     => 'connectSrc',
+        'default-src'     => 'defaultSrc',
+        'font-src'        => 'fontSrc',
+        'form-action'     => 'formAction',
+        'frame-ancestors' => 'frameAncestors',
+        'frame-src'       => 'frameSrc',
+        'img-src'         => 'imageSrc',
+        'media-src'       => 'mediaSrc',
+        'object-src'      => 'objectSrc',
+        'plugin-types'    => 'pluginTypes',
+        'script-src'      => 'scriptSrc',
+        'style-src'       => 'styleSrc',
+        'manifest-src'    => 'manifestSrc',
+        'sandbox'         => 'sandbox',
+        'report-uri'      => 'reportURI',
+    ];
+
     /**
      * Used for security enforcement
      *
@@ -113,37 +138,37 @@ class ContentSecurityPolicy
     /**
      * Used for security enforcement
      *
-     * @var string
+     * @var array|string
      */
-    protected $reportURI;
+    protected $scriptSrc = [];
 
     /**
      * Used for security enforcement
      *
      * @var array|string
      */
-    protected $sandbox = [];
+    protected $styleSrc = [];
 
     /**
      * Used for security enforcement
      *
      * @var array|string
      */
-    protected $scriptSrc = [];
+    protected $manifestSrc = [];
 
     /**
      * Used for security enforcement
      *
      * @var array|string
      */
-    protected $styleSrc = [];
+    protected $sandbox = [];
 
     /**
      * Used for security enforcement
      *
-     * @var array|string
+     * @var string|null
      */
-    protected $manifestSrc = [];
+    protected $reportURI;
 
     /**
      * Used for security enforcement
@@ -704,26 +729,6 @@ protected function buildHeaders(ResponseInterface $response)
         $response->setHeader('Content-Security-Policy', []);
         $response->setHeader('Content-Security-Policy-Report-Only', []);
 
-        $directives = [
-            'base-uri'        => 'baseURI',
-            'child-src'       => 'childSrc',
-            'connect-src'     => 'connectSrc',
-            'default-src'     => 'defaultSrc',
-            'font-src'        => 'fontSrc',
-            'form-action'     => 'formAction',
-            'frame-ancestors' => 'frameAncestors',
-            'frame-src'       => 'frameSrc',
-            'img-src'         => 'imageSrc',
-            'media-src'       => 'mediaSrc',
-            'object-src'      => 'objectSrc',
-            'plugin-types'    => 'pluginTypes',
-            'script-src'      => 'scriptSrc',
-            'style-src'       => 'styleSrc',
-            'manifest-src'    => 'manifestSrc',
-            'sandbox'         => 'sandbox',
-            'report-uri'      => 'reportURI',
-        ];
-
         // inject default base & default URIs if needed
         if (empty($this->baseURI)) {
             $this->baseURI = 'self';
@@ -733,7 +738,7 @@ protected function buildHeaders(ResponseInterface $response)
             $this->defaultSrc = 'self';
         }
 
-        foreach ($directives as $name => $property) {
+        foreach ($this->directives as $name => $property) {
             if (! empty($this->{$property})) {
                 $this->addToHeader($name, $this->{$property});
             }
@@ -814,4 +819,20 @@ protected function addToHeader(string $name, $values = null)
             $this->reportOnlyHeaders[$name] = implode(' ', $reportSources);
         }
     }
+
+    /**
+     * Clear the directive.
+     *
+     * @param string $directive CSP directive
+     */
+    public function clearDirective(string $directive): void
+    {
+        if ($directive === 'report-uris') {
+            $this->{$this->directives[$directive]} = null;
+
+            return;
+        }
+
+        $this->{$this->directives[$directive]} = [];
+    }
 }

tests/system/HTTP/ContentSecurityPolicyTest.php

@@ -642,4 +642,22 @@ public function testHeaderScriptNonceEmittedOnceGetScriptNonceCalled(): void
         $result = $this->getHeaderEmitted('Content-Security-Policy');
         $this->assertStringContainsString("script-src 'self' 'nonce-", $result);
     }
+
+    public function testClearDirective(): void
+    {
+        $this->prepare();
+
+        $this->csp->addStyleSrc('css.example.com');
+        $this->csp->clearDirective('style-src');
+
+        $this->csp->setReportURI('http://example.com/csp/reports');
+        $this->csp->clearDirective('report-uri');
+        $this->csp->finalize($this->response);
+
+        $header = $this->response->getHeaderLine('Content-Security-Policy');
+
+        $this->assertStringNotContainsString('style-src ', $header);
+        $this->assertStringNotContainsString('css.example.com', $header);
+        $this->assertStringNotContainsString('report-uri', $header);
+    }
 }

user_guide_src/source/changelogs/v4.5.0.rst

@@ -240,6 +240,8 @@ Others
     - ``FileLocatorInterface`` has been added.
 - **CodeIgniter:** Added a pseudo-variable ``{memory_usage}`` to show your memory
   usage in your view files, which was supported by CodeIgniter 3.
+- **CSP:** Added ``ContentSecurityPolicy::clearDirective()`` method to clear
+  existing CSP directives. See :ref:`csp-clear-directives`.
 
 Message Changes
 ***************

user_guide_src/source/outgoing/csp.rst

@@ -66,7 +66,9 @@ call basis, by providing an optional second parameter to the adding method call.
 Runtime Configuration
 *********************
 
-If your application needs to make changes at run-time, you can access the instance at ``$this->response->getCSP()`` in your controllers. The
+If your application needs to make changes at run-time, you can access the instance at ``$this->response->getCSP()`` in your controllers.
+
+The
 class holds a number of methods that map pretty clearly to the appropriate header value that you need to set.
 Examples are shown below, with different combinations of parameters, though all accept either a directive
 name or an array of them:
@@ -76,12 +78,27 @@ name or an array of them:
 The first parameter to each of the "add" methods is an appropriate string value,
 or an array of them.
 
+Report Only
+===========
+
 The ``reportOnly()`` method allows you to specify the default reporting treatment
-for subsequent sources, unless over-ridden. For instance, you could specify
+for subsequent sources, unless over-ridden.
+
+For instance, you could specify
 that youtube.com was allowed, and then provide several allowed but reported sources:
 
 .. literalinclude:: csp/013.php
 
+.. _csp-clear-directives:
+
+Clear Directives
+================
+
+If you want to clear existing CSP directives, you can use the ``clearDirective()``
+method:
+
+.. literalinclude:: csp/014.php
+
 **************
 Inline Content
 **************

user_guide_src/source/outgoing/csp/014.php

@@ -0,0 +1,6 @@
+<?php
+
+// get the CSP instance
+$csp = $this->response->getCSP();
+
+$csp->clearDirective('style-src');