Add public API to give developers the possibility to adjust the global CSP defaults

Allows to inject something into the default content policy. This is for
example useful when you're injecting Javascript code into a view belonging
to another controller and cannot modify its Content-Security-Policy itself.
Note that the adjustment is only applied to applications that use AppFramework
controllers.

To use this from your `app.php` use `\OC::$server->getContentSecurityPolicyManager()->addDefaultPolicy($policy)`,
$policy has to be of type `\OCP\AppFramework\Http\ContentSecurityPolicy`.

To test this add something like the following into an `app.php` of any enabled app:
```
$manager = \OC::$server->getContentSecurityPolicyManager();
$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFrameDomain('asdf');
$policy->addAllowedScriptDomain('yolo.com');

$policy->allowInlineScript(false);
$manager->addDefaultPolicy($policy);
$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFontDomain('yolo.com');
$manager->addDefaultPolicy($policy);

$policy = new \OCP\AppFramework\Http\ContentSecurityPolicy(false);
$policy->addAllowedFrameDomain('banana.com');
$manager->addDefaultPolicy($policy);
```

If you now open the files app the policy should be:

```
Content-Security-Policy:default-src 'none';script-src yolo.com 'self' 'unsafe-eval';style-src 'self' 'unsafe-inline';img-src 'self' data: blob:;font-src yolo.com 'self';connect-src 'self';media-src 'self';frame-src asdf banana.com 'self'
```

10 files changed, 783 insertions, 329 deletions

diff --git a/lib/private/appframework/dependencyinjection/dicontainer.php b/lib/private/appframework/dependencyinjection/dicontainer.php
index 61a04482431..ff9da88cd81 100644
--- a/lib/private/appframework/dependencyinjection/dicontainer.php
+++ b/lib/private/appframework/dependencyinjection/dicontainer.php
@@ -32,7 +32,6 @@ namespace OC\AppFramework\DependencyInjection;
 
 use OC;
 use OC\AppFramework\Http;
-use OC\AppFramework\Http\Request;
 use OC\AppFramework\Http\Dispatcher;
 use OC\AppFramework\Http\Output;
 use OC\AppFramework\Core\API;
@@ -43,8 +42,6 @@ use OC\AppFramework\Middleware\SessionMiddleware;
 use OC\AppFramework\Utility\SimpleContainer;
 use OCP\AppFramework\IApi;
 use OCP\AppFramework\IAppContainer;
-use OCP\AppFramework\Middleware;
-use OCP\IServerContainer;
 
 
 class DIContainer extends SimpleContainer implements IAppContainer {
@@ -255,6 +252,10 @@ class DIContainer extends SimpleContainer implements IAppContainer {
 			return $this->getServer()->getSession();
 		});
 
+		$this->registerService('OCP\\Security\\IContentSecurityPolicyManager', function($c) {
+			return $this->getServer()->getContentSecurityPolicyManager();
+		});
+
 		$this->registerService('ServerContainer', function ($c) {
 			return $this->getServer();
 		});
@@ -319,7 +320,8 @@ class DIContainer extends SimpleContainer implements IAppContainer {
 				$app->getServer()->getLogger(),
 				$c['AppName'],
 				$app->isLoggedIn(),
-				$app->isAdminUser()
+				$app->isAdminUser(),
+				$app->getServer()->getContentSecurityPolicyManager()
 			);
 		});
 
diff --git a/lib/private/appframework/middleware/security/securitymiddleware.php b/lib/private/appframework/middleware/security/securitymiddleware.php
index 4ef043ad50f..f1ba98254f0 100644
--- a/lib/private/appframework/middleware/security/securitymiddleware.php
+++ b/lib/private/appframework/middleware/security/securitymiddleware.php
@@ -32,6 +32,8 @@ use OC\Appframework\Middleware\Security\Exceptions\CrossSiteRequestForgeryExcept
 use OC\Appframework\Middleware\Security\Exceptions\NotAdminException;
 use OC\Appframework\Middleware\Security\Exceptions\NotLoggedInException;
 use OC\AppFramework\Utility\ControllerMethodReflector;
+use OC\Security\CSP\ContentSecurityPolicyManager;
+use OCP\AppFramework\Http\ContentSecurityPolicy;
 use OCP\AppFramework\Http\RedirectResponse;
 use OCP\AppFramework\Http\TemplateResponse;
 use OCP\AppFramework\Middleware;
@@ -52,15 +54,24 @@ use OC\AppFramework\Middleware\Security\Exceptions\SecurityException;
  * check fails
  */
 class SecurityMiddleware extends Middleware {
-
+	/** @var INavigationManager */
 	private $navigationManager;
+	/** @var IRequest */
 	private $request;
+	/** @var ControllerMethodReflector */
 	private $reflector;
+	/** @var string */
 	private $appName;
+	/** @var IURLGenerator */
 	private $urlGenerator;
+	/** @var ILogger */
 	private $logger;
+	/** @var bool */
 	private $isLoggedIn;
+	/** @var bool */
 	private $isAdminUser;
+	/** @var ContentSecurityPolicyManager */
+	private $contentSecurityPolicyManager;
 
 	/**
 	 * @param IRequest $request
@@ -71,6 +82,7 @@ class SecurityMiddleware extends Middleware {
 	 * @param string $appName
 	 * @param bool $isLoggedIn
 	 * @param bool $isAdminUser
+	 * @param ContentSecurityPolicyManager $contentSecurityPolicyManager
 	 */
 	public function __construct(IRequest $request,
 								ControllerMethodReflector $reflector,
@@ -79,7 +91,8 @@ class SecurityMiddleware extends Middleware {
 								ILogger $logger,
 								$appName,
 								$isLoggedIn,
-								$isAdminUser) {
+								$isAdminUser,
+								ContentSecurityPolicyManager $contentSecurityPolicyManager) {
 		$this->navigationManager = $navigationManager;
 		$this->request = $request;
 		$this->reflector = $reflector;
@@ -88,6 +101,7 @@ class SecurityMiddleware extends Middleware {
 		$this->logger = $logger;
 		$this->isLoggedIn = $isLoggedIn;
 		$this->isAdminUser = $isAdminUser;
+		$this->contentSecurityPolicyManager = $contentSecurityPolicyManager;
 	}
 
 
@@ -139,6 +153,25 @@ class SecurityMiddleware extends Middleware {
 
 	}
 
+	/**
+	 * Performs the default CSP modifications that may be injected by other
+	 * applications
+	 *
+	 * @param Controller $controller
+	 * @param string $methodName
+	 * @param Response $response
+	 * @return Response
+	 */
+	public function afterController($controller, $methodName, Response $response) {
+		$policy = !is_null($response->getContentSecurityPolicy()) ? $response->getContentSecurityPolicy() : new ContentSecurityPolicy();
+
+		$defaultPolicy = $this->contentSecurityPolicyManager->getDefaultPolicy();
+		$defaultPolicy = $this->contentSecurityPolicyManager->mergePolicies($defaultPolicy, $policy);
+
+		$response->setContentSecurityPolicy($defaultPolicy);
+
+		return $response;
+	}
 
 	/**
 	 * If an SecurityException is being caught, ajax requests return a JSON error
diff --git a/lib/private/security/csp/contentsecuritypolicy.php b/lib/private/security/csp/contentsecuritypolicy.php
new file mode 100644
index 00000000000..25eacfab1d6
--- /dev/null
+++ b/lib/private/security/csp/contentsecuritypolicy.php
@@ -0,0 +1,199 @@
+<?php
+/**
+ * @author Lukas Reschke <lukas@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OC\Security\CSP;
+
+/**
+ * Class ContentSecurityPolicy extends the public class and adds getter and setters.
+ * This is necessary since we don't want to expose the setters and getters to the
+ * public API.
+ *
+ * @package OC\Security\CSP
+ */
+class ContentSecurityPolicy extends \OCP\AppFramework\Http\ContentSecurityPolicy {
+	/**
+	 * @return boolean
+	 */
+	public function isInlineScriptAllowed() {
+		return $this->inlineScriptAllowed;
+	}
+
+	/**
+	 * @param boolean $inlineScriptAllowed
+	 */
+	public function setInlineScriptAllowed($inlineScriptAllowed) {
+		$this->inlineScriptAllowed = $inlineScriptAllowed;
+	}
+
+	/**
+	 * @return boolean
+	 */
+	public function isEvalScriptAllowed() {
+		return $this->evalScriptAllowed;
+	}
+
+	/**
+	 * @param boolean $evalScriptAllowed
+	 */
+	public function setEvalScriptAllowed($evalScriptAllowed) {
+		$this->evalScriptAllowed = $evalScriptAllowed;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedScriptDomains() {
+		return $this->allowedScriptDomains;
+	}
+
+	/**
+	 * @param array $allowedScriptDomains
+	 */
+	public function setAllowedScriptDomains($allowedScriptDomains) {
+		$this->allowedScriptDomains = $allowedScriptDomains;
+	}
+
+	/**
+	 * @return boolean
+	 */
+	public function isInlineStyleAllowed() {
+		return $this->inlineStyleAllowed;
+	}
+
+	/**
+	 * @param boolean $inlineStyleAllowed
+	 */
+	public function setInlineStyleAllowed($inlineStyleAllowed) {
+		$this->inlineStyleAllowed = $inlineStyleAllowed;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedStyleDomains() {
+		return $this->allowedStyleDomains;
+	}
+
+	/**
+	 * @param array $allowedStyleDomains
+	 */
+	public function setAllowedStyleDomains($allowedStyleDomains) {
+		$this->allowedStyleDomains = $allowedStyleDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedImageDomains() {
+		return $this->allowedImageDomains;
+	}
+
+	/**
+	 * @param array $allowedImageDomains
+	 */
+	public function setAllowedImageDomains($allowedImageDomains) {
+		$this->allowedImageDomains = $allowedImageDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedConnectDomains() {
+		return $this->allowedConnectDomains;
+	}
+
+	/**
+	 * @param array $allowedConnectDomains
+	 */
+	public function setAllowedConnectDomains($allowedConnectDomains) {
+		$this->allowedConnectDomains = $allowedConnectDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedMediaDomains() {
+		return $this->allowedMediaDomains;
+	}
+
+	/**
+	 * @param array $allowedMediaDomains
+	 */
+	public function setAllowedMediaDomains($allowedMediaDomains) {
+		$this->allowedMediaDomains = $allowedMediaDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedObjectDomains() {
+		return $this->allowedObjectDomains;
+	}
+
+	/**
+	 * @param array $allowedObjectDomains
+	 */
+	public function setAllowedObjectDomains($allowedObjectDomains) {
+		$this->allowedObjectDomains = $allowedObjectDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedFrameDomains() {
+		return $this->allowedFrameDomains;
+	}
+
+	/**
+	 * @param array $allowedFrameDomains
+	 */
+	public function setAllowedFrameDomains($allowedFrameDomains) {
+		$this->allowedFrameDomains = $allowedFrameDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedFontDomains() {
+		return $this->allowedFontDomains;
+	}
+
+	/**
+	 * @param array $allowedFontDomains
+	 */
+	public function setAllowedFontDomains($allowedFontDomains) {
+		$this->allowedFontDomains = $allowedFontDomains;
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getAllowedChildSrcDomains() {
+		return $this->allowedChildSrcDomains;
+	}
+
+	/**
+	 * @param array $allowedChildSrcDomains
+	 */
+	public function setAllowedChildSrcDomains($allowedChildSrcDomains) {
+		$this->allowedChildSrcDomains = $allowedChildSrcDomains;
+	}
+
+}
diff --git a/lib/private/security/csp/contentsecuritypolicymanager.php b/lib/private/security/csp/contentsecuritypolicymanager.php
new file mode 100644
index 00000000000..760cd36e56b
--- /dev/null
+++ b/lib/private/security/csp/contentsecuritypolicymanager.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * @author Lukas Reschke <lukas@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Security\CSP;
+
+use OCP\AppFramework\Http\ContentSecurityPolicy;
+use OCP\AppFramework\Http\EmptyContentSecurityPolicy;
+use OCP\Security\IContentSecurityPolicyManager;
+
+class ContentSecurityPolicyManager implements IContentSecurityPolicyManager {
+	/** @var ContentSecurityPolicy[] */
+	private $policies = [];
+
+	/** {@inheritdoc} */
+	public function addDefaultPolicy(EmptyContentSecurityPolicy $policy) {
+		$this->policies[] = $policy;
+	}
+
+	/**
+	 * Get the configured default policy. This is not in the public namespace
+	 * as it is only supposed to be used by core itself.
+	 *
+	 * @return ContentSecurityPolicy
+	 */
+	public function getDefaultPolicy() {
+		$defaultPolicy = new \OC\Security\CSP\ContentSecurityPolicy();
+		foreach($this->policies as $policy) {
+			$defaultPolicy = $this->mergePolicies($defaultPolicy, $policy);
+		}
+		return $defaultPolicy;
+	}
+
+	/**
+	 * Merges the first given policy with the second one
+	 *
+	 * @param ContentSecurityPolicy $defaultPolicy
+	 * @param EmptyContentSecurityPolicy $originalPolicy
+	 * @return ContentSecurityPolicy
+	 */
+	public function mergePolicies(ContentSecurityPolicy $defaultPolicy,
+								  EmptyContentSecurityPolicy $originalPolicy) {
+		foreach((object)(array)$originalPolicy as $name => $value) {
+			$setter = 'set'.ucfirst($name);
+			if(is_array($value)) {
+				$getter = 'get'.ucfirst($name);
+				$currentValues = is_array($defaultPolicy->$getter()) ? $defaultPolicy->$getter() : [];
+				$defaultPolicy->$setter(array_values(array_unique(array_merge($currentValues, $value))));
+			} elseif (is_bool($value)) {
+				$defaultPolicy->$setter($value);
+			}
+		}
+
+		return $defaultPolicy;
+	}
+}
diff --git a/lib/private/server.php b/lib/private/server.php
index d453a42d3a0..d3dbcba86ba 100644
--- a/lib/private/server.php
+++ b/lib/private/server.php
@@ -63,6 +63,7 @@ use OC\Lock\NoopLockingProvider;
 use OC\Mail\Mailer;
 use OC\Notification\Manager;
 use OC\Security\CertificateManager;
+use OC\Security\CSP\ContentSecurityPolicyManager;
 use OC\Security\Crypto;
 use OC\Security\CSRF\CsrfTokenGenerator;
 use OC\Security\CSRF\CsrfTokenManager;
@@ -74,6 +75,7 @@ use OC\Security\TrustedDomainHelper;
 use OC\Session\CryptoWrapper;
 use OC\Tagging\TagMapper;
 use OCP\IServerContainer;
+use OCP\Security\IContentSecurityPolicyManager;
 use Symfony\Component\EventDispatcher\EventDispatcher;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
@@ -598,6 +600,9 @@ class Server extends ServerContainer implements IServerContainer {
 				$sessionStorage
 			);
 		});
+		$this->registerService('ContentSecurityPolicyManager', function (Server $c) {
+			return new ContentSecurityPolicyManager();
+		});
 		$this->registerService('ShareManager', function(Server $c) {
 			$config = $c->getConfig();
 			$factoryClass = $config->getSystemValue('sharing.managerFactory', '\OC\Share20\ProviderFactory');
@@ -1221,6 +1226,13 @@ class Server extends ServerContainer implements IServerContainer {
 	}
 
 	/**
+	 * @return IContentSecurityPolicyManager
+	 */
+	public function getContentSecurityPolicyManager() {
+		return $this->query('ContentSecurityPolicyManager');
+	}
+
+	/**
 	 * Not a public API as of 8.2, wait for 9.0
 	 *
 	 * @return \OCA\Files_External\Service\BackendService
diff --git a/lib/public/appframework/controller.php b/lib/public/appframework/controller.php
index 973c9044684..c3744683300 100644
--- a/lib/public/appframework/controller.php
+++ b/lib/public/appframework/controller.php
@@ -72,7 +72,7 @@ abstract class Controller {
 	 * @since 6.0.0 - parameter $appName was added in 7.0.0 - parameter $app was removed in 7.0.0
 	 */
 	public function __construct($appName,
-	                            IRequest $request){
+	                            IRequest $request) {
 		$this->appName = $appName;
 		$this->request = $request;
 
diff --git a/lib/public/appframework/http/contentsecuritypolicy.php b/lib/public/appframework/http/contentsecuritypolicy.php
index 35da4f05e80..7762ca809a2 100644
--- a/lib/public/appframework/http/contentsecuritypolicy.php
+++ b/lib/public/appframework/http/contentsecuritypolicy.php
@@ -38,17 +38,17 @@ use OCP\AppFramework\Http;
  * @package OCP\AppFramework\Http
  * @since 8.1.0
  */
-class ContentSecurityPolicy {
+class ContentSecurityPolicy extends EmptyContentSecurityPolicy {
 	/** @var bool Whether inline JS snippets are allowed */
-	private $inlineScriptAllowed = false;
+	protected $inlineScriptAllowed = false;
 	/**
 	 * @var bool Whether eval in JS scripts is allowed
 	 * TODO: Disallow per default
 	 * @link https://github.com/owncloud/core/issues/11925
 	 */
-	private $evalScriptAllowed = true;
+	protected $evalScriptAllowed = true;
 	/** @var array Domains from which scripts can get loaded */
-	private $allowedScriptDomains = [
+	protected $allowedScriptDomains = [
 		'\'self\'',
 	];
 	/**
@@ -56,342 +56,33 @@ class ContentSecurityPolicy {
 	 * TODO: Disallow per default
 	 * @link https://github.com/owncloud/core/issues/13458
 	 */
-	private $inlineStyleAllowed = true;
+	protected $inlineStyleAllowed = true;
 	/** @var array Domains from which CSS can get loaded */
-	private $allowedStyleDomains = [
+	protected $allowedStyleDomains = [
 		'\'self\'',
 	];
 	/** @var array Domains from which images can get loaded */
-	private $allowedImageDomains = [
+	protected $allowedImageDomains = [
 		'\'self\'',
 		'data:',
 		'blob:',
 	];
 	/** @var array Domains to which connections can be done */
-	private $allowedConnectDomains = [
+	protected $allowedConnectDomains = [
 		'\'self\'',
 	];
 	/** @var array Domains from which media elements can be loaded */
-	private $allowedMediaDomains = [
+	protected $allowedMediaDomains = [
 		'\'self\'',
 	];
 	/** @var array Domains from which object elements can be loaded */
-	private $allowedObjectDomains = [];
+	protected $allowedObjectDomains = [];
 	/** @var array Domains from which iframes can be loaded */
-	private $allowedFrameDomains = [];
+	protected $allowedFrameDomains = [];
 	/** @var array Domains from which fonts can be loaded */
-	private $allowedFontDomains = [
+	protected $allowedFontDomains = [
 		'\'self\'',
 	];
 	/** @var array Domains from which web-workers and nested browsing content can load elements */
-	private $allowedChildSrcDomains = [];
-
-	/**
-	 * Whether inline JavaScript snippets are allowed or forbidden
-	 * @param bool $state
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function allowInlineScript($state = false) {
-		$this->inlineScriptAllowed = $state;
-		return $this;
-	}
-
-	/**
-	 * Whether eval in JavaScript is allowed or forbidden
-	 * @param bool $state
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function allowEvalScript($state = true) {
-		$this->evalScriptAllowed = $state;
-		return $this;
-	}
-
-	/**
-	 * Allows to execute JavaScript files from a specific domain. Use * to
-	 * allow JavaScript from all domains.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedScriptDomain($domain) {
-		$this->allowedScriptDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed script domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowScriptDomain($domain) {
-		$this->allowedScriptDomains = array_diff($this->allowedScriptDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Whether inline CSS snippets are allowed or forbidden
-	 * @param bool $state
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function allowInlineStyle($state = true) {
-		$this->inlineStyleAllowed = $state;
-		return $this;
-	}
-
-	/**
-	 * Allows to execute CSS files from a specific domain. Use * to allow
-	 * CSS from all domains.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedStyleDomain($domain) {
-		$this->allowedStyleDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed style domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowStyleDomain($domain) {
-		$this->allowedStyleDomains = array_diff($this->allowedStyleDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Allows using fonts from a specific domain. Use * to allow
-	 * fonts from all domains.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedFontDomain($domain) {
-		$this->allowedFontDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed font domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowFontDomain($domain) {
-		$this->allowedFontDomains = array_diff($this->allowedFontDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Allows embedding images from a specific domain. Use * to allow
-	 * images from all domains.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedImageDomain($domain) {
-		$this->allowedImageDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed image domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowImageDomain($domain) {
-		$this->allowedImageDomains = array_diff($this->allowedImageDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * To which remote domains the JS connect to.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedConnectDomain($domain) {
-		$this->allowedConnectDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed connect domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowConnectDomain($domain) {
-		$this->allowedConnectDomains = array_diff($this->allowedConnectDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * From which domains media elements can be embedded.
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedMediaDomain($domain) {
-		$this->allowedMediaDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed media domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowMediaDomain($domain) {
-		$this->allowedMediaDomains = array_diff($this->allowedMediaDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * From which domains objects such as <object>, <embed> or <applet> are executed
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedObjectDomain($domain) {
-		$this->allowedObjectDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed object domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowObjectDomain($domain) {
-		$this->allowedObjectDomains = array_diff($this->allowedObjectDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Which domains can be embedded in an iframe
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedFrameDomain($domain) {
-		$this->allowedFrameDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed frame domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowFrameDomain($domain) {
-		$this->allowedFrameDomains = array_diff($this->allowedFrameDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Domains from which web-workers and nested browsing content can load elements
-	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function addAllowedChildSrcDomain($domain) {
-		$this->allowedChildSrcDomains[] = $domain;
-		return $this;
-	}
-
-	/**
-	 * Remove the specified allowed child src domain from the allowed domains.
-	 *
-	 * @param string $domain
-	 * @return $this
-	 * @since 8.1.0
-	 */
-	public function disallowChildSrcDomain($domain) {
-		$this->allowedChildSrcDomains = array_diff($this->allowedChildSrcDomains, [$domain]);
-		return $this;
-	}
-
-	/**
-	 * Get the generated Content-Security-Policy as a string
-	 * @return string
-	 * @since 8.1.0
-	 */
-	public function buildPolicy() {
-		$policy = "default-src 'none';";
-
-		if(!empty($this->allowedScriptDomains)) {
-			$policy .= 'script-src ' . implode(' ', $this->allowedScriptDomains);
-			if($this->inlineScriptAllowed) {
-				$policy .= ' \'unsafe-inline\'';
-			}
-			if($this->evalScriptAllowed) {
-				$policy .= ' \'unsafe-eval\'';
-			}
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedStyleDomains)) {
-			$policy .= 'style-src ' . implode(' ', $this->allowedStyleDomains);
-			if($this->inlineStyleAllowed) {
-				$policy .= ' \'unsafe-inline\'';
-			}
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedImageDomains)) {
-			$policy .= 'img-src ' . implode(' ', $this->allowedImageDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedFontDomains)) {
-			$policy .= 'font-src ' . implode(' ', $this->allowedFontDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedConnectDomains)) {
-			$policy .= 'connect-src ' . implode(' ', $this->allowedConnectDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedMediaDomains)) {
-			$policy .= 'media-src ' . implode(' ', $this->allowedMediaDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedObjectDomains)) {
-			$policy .= 'object-src ' . implode(' ', $this->allowedObjectDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedFrameDomains)) {
-			$policy .= 'frame-src ' . implode(' ', $this->allowedFrameDomains);
-			$policy .= ';';
-		}
-
-		if(!empty($this->allowedChildSrcDomains)) {
-			$policy .= 'child-src ' . implode(' ', $this->allowedChildSrcDomains);
-			$policy .= ';';
-		}
-
-		return rtrim($policy, ';');
-	}
+	protected $allowedChildSrcDomains = [];
 }
diff --git a/lib/public/appframework/http/emptycontentsecuritypolicy.php b/lib/public/appframework/http/emptycontentsecuritypolicy.php
new file mode 100644
index 00000000000..33860dcdb0f
--- /dev/null
+++ b/lib/public/appframework/http/emptycontentsecuritypolicy.php
@@ -0,0 +1,387 @@
+<?php
+/**
+ * @author Lukas Reschke <lukas@owncloud.com>
+ * @author Morris Jobke <hey@morrisjobke.de>
+ * @author sualko <klaus@jsxc.org>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\AppFramework\Http;
+
+use OCP\AppFramework\Http;
+
+/**
+ * Class EmptyContentSecurityPolicy is a simple helper which allows applications
+ * to modify the Content-Security-Policy sent by ownCloud. Per default the policy
+ * is forbidding everything.
+ *
+ * As alternative with sane exemptions look at ContentSecurityPolicy
+ *
+ * @see \OCP\AppFramework\Http\ContentSecurityPolicy
+ * @package OCP\AppFramework\Http
+ * @since 9.0.0
+ */
+class EmptyContentSecurityPolicy {
+	/** @var bool Whether inline JS snippets are allowed */
+	protected $inlineScriptAllowed = null;
+	/**
+	 * @var bool Whether eval in JS scripts is allowed
+	 * TODO: Disallow per default
+	 * @link https://github.com/owncloud/core/issues/11925
+	 */
+	protected $evalScriptAllowed = null;
+	/** @var array Domains from which scripts can get loaded */
+	protected $allowedScriptDomains = null;
+	/**
+	 * @var bool Whether inline CSS is allowed
+	 * TODO: Disallow per default
+	 * @link https://github.com/owncloud/core/issues/13458
+	 */
+	protected $inlineStyleAllowed = null;
+	/** @var array Domains from which CSS can get loaded */
+	protected $allowedStyleDomains = null;
+	/** @var array Domains from which images can get loaded */
+	protected $allowedImageDomains = null;
+	/** @var array Domains to which connections can be done */
+	protected $allowedConnectDomains = null;
+	/** @var array Domains from which media elements can be loaded */
+	protected $allowedMediaDomains = null;
+	/** @var array Domains from which object elements can be loaded */
+	protected $allowedObjectDomains = null;
+	/** @var array Domains from which iframes can be loaded */
+	protected $allowedFrameDomains = null;
+	/** @var array Domains from which fonts can be loaded */
+	protected $allowedFontDomains = null;
+	/** @var array Domains from which web-workers and nested browsing content can load elements */
+	protected $allowedChildSrcDomains = null;
+
+	/**
+	 * Whether inline JavaScript snippets are allowed or forbidden
+	 * @param bool $state
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function allowInlineScript($state = false) {
+		$this->inlineScriptAllowed = $state;
+		return $this;
+	}
+
+	/**
+	 * Whether eval in JavaScript is allowed or forbidden
+	 * @param bool $state
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function allowEvalScript($state = true) {
+		$this->evalScriptAllowed = $state;
+		return $this;
+	}
+
+	/**
+	 * Allows to execute JavaScript files from a specific domain. Use * to
+	 * allow JavaScript from all domains.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedScriptDomain($domain) {
+		$this->allowedScriptDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed script domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowScriptDomain($domain) {
+		$this->allowedScriptDomains = array_diff($this->allowedScriptDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Whether inline CSS snippets are allowed or forbidden
+	 * @param bool $state
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function allowInlineStyle($state = true) {
+		$this->inlineStyleAllowed = $state;
+		return $this;
+	}
+
+	/**
+	 * Allows to execute CSS files from a specific domain. Use * to allow
+	 * CSS from all domains.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedStyleDomain($domain) {
+		$this->allowedStyleDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed style domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowStyleDomain($domain) {
+		$this->allowedStyleDomains = array_diff($this->allowedStyleDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Allows using fonts from a specific domain. Use * to allow
+	 * fonts from all domains.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedFontDomain($domain) {
+		$this->allowedFontDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed font domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowFontDomain($domain) {
+		$this->allowedFontDomains = array_diff($this->allowedFontDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Allows embedding images from a specific domain. Use * to allow
+	 * images from all domains.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedImageDomain($domain) {
+		$this->allowedImageDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed image domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowImageDomain($domain) {
+		$this->allowedImageDomains = array_diff($this->allowedImageDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * To which remote domains the JS connect to.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedConnectDomain($domain) {
+		$this->allowedConnectDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed connect domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowConnectDomain($domain) {
+		$this->allowedConnectDomains = array_diff($this->allowedConnectDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * From which domains media elements can be embedded.
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedMediaDomain($domain) {
+		$this->allowedMediaDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed media domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowMediaDomain($domain) {
+		$this->allowedMediaDomains = array_diff($this->allowedMediaDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * From which domains objects such as <object>, <embed> or <applet> are executed
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedObjectDomain($domain) {
+		$this->allowedObjectDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed object domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowObjectDomain($domain) {
+		$this->allowedObjectDomains = array_diff($this->allowedObjectDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Which domains can be embedded in an iframe
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedFrameDomain($domain) {
+		$this->allowedFrameDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed frame domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowFrameDomain($domain) {
+		$this->allowedFrameDomains = array_diff($this->allowedFrameDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Domains from which web-workers and nested browsing content can load elements
+	 * @param string $domain Domain to whitelist. Any passed value needs to be properly sanitized.
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function addAllowedChildSrcDomain($domain) {
+		$this->allowedChildSrcDomains[] = $domain;
+		return $this;
+	}
+
+	/**
+	 * Remove the specified allowed child src domain from the allowed domains.
+	 *
+	 * @param string $domain
+	 * @return $this
+	 * @since 8.1.0
+	 */
+	public function disallowChildSrcDomain($domain) {
+		$this->allowedChildSrcDomains = array_diff($this->allowedChildSrcDomains, [$domain]);
+		return $this;
+	}
+
+	/**
+	 * Get the generated Content-Security-Policy as a string
+	 * @return string
+	 * @since 8.1.0
+	 */
+	public function buildPolicy() {
+		$policy = "default-src 'none';";
+
+		if(!empty($this->allowedScriptDomains) || $this->inlineScriptAllowed || $this->evalScriptAllowed) {
+			$policy .= 'script-src ';
+			if(is_array($this->allowedScriptDomains)) {
+				$policy .= implode(' ', $this->allowedScriptDomains);
+			}
+			if($this->inlineScriptAllowed) {
+				$policy .= ' \'unsafe-inline\'';
+			}
+			if($this->evalScriptAllowed) {
+				$policy .= ' \'unsafe-eval\'';
+			}
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedStyleDomains) || $this->inlineStyleAllowed) {
+			$policy .= 'style-src ';
+			if(is_array($this->allowedStyleDomains)) {
+				$policy .= implode(' ', $this->allowedStyleDomains);
+			}
+			if($this->inlineStyleAllowed) {
+				$policy .= ' \'unsafe-inline\'';
+			}
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedImageDomains)) {
+			$policy .= 'img-src ' . implode(' ', $this->allowedImageDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedFontDomains)) {
+			$policy .= 'font-src ' . implode(' ', $this->allowedFontDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedConnectDomains)) {
+			$policy .= 'connect-src ' . implode(' ', $this->allowedConnectDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedMediaDomains)) {
+			$policy .= 'media-src ' . implode(' ', $this->allowedMediaDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedObjectDomains)) {
+			$policy .= 'object-src ' . implode(' ', $this->allowedObjectDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedFrameDomains)) {
+			$policy .= 'frame-src ' . implode(' ', $this->allowedFrameDomains);
+			$policy .= ';';
+		}
+
+		if(!empty($this->allowedChildSrcDomains)) {
+			$policy .= 'child-src ' . implode(' ', $this->allowedChildSrcDomains);
+			$policy .= ';';
+		}
+
+		return rtrim($policy, ';');
+	}
+}
diff --git a/lib/public/iservercontainer.php b/lib/public/iservercontainer.php
index ce1364cc4ea..de48daeef88 100644
--- a/lib/public/iservercontainer.php
+++ b/lib/public/iservercontainer.php
@@ -42,6 +42,7 @@
 // use OCP namespace for all classes that are considered public.
 // This means that they should be used by apps instead of the internal ownCloud classes
 namespace OCP;
+use OCP\Security\IContentSecurityPolicyManager;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 
@@ -512,4 +513,10 @@ interface IServerContainer {
 	 * @since 9.0.0
 	 */
 	public function getShareManager();
+
+	/**
+	 * @return IContentSecurityPolicyManager
+	 * @since 9.0.0
+	 */
+	public function getContentSecurityPolicyManager();
 }
diff --git a/lib/public/security/icontentsecuritypolicymanager.php b/lib/public/security/icontentsecuritypolicymanager.php
new file mode 100644
index 00000000000..10f1efe995f
--- /dev/null
+++ b/lib/public/security/icontentsecuritypolicymanager.php
@@ -0,0 +1,50 @@
+<?php
+/**
+ * @author Lukas Reschke <lukas@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Security;
+use OCP\AppFramework\Http\EmptyContentSecurityPolicy;
+
+/**
+ * Used for Content Security Policy manipulations
+ *
+ * @package OCP\Security
+ * @since 9.0.0
+ */
+interface IContentSecurityPolicyManager {
+	/**
+	 * Allows to inject something into the default content policy. This is for
+	 * example useful when you're injecting Javascript code into a view belonging
+	 * to another controller and cannot modify its Content-Security-Policy itself.
+	 * Note that the adjustment is only applied to applications that use AppFramework
+	 * controllers.
+	 *
+	 * To use this from your `app.php` use `\OC::$server->getContentSecurityPolicyManager()->addDefaultPolicy($policy)`,
+	 * $policy has to be of type `\OCP\AppFramework\Http\ContentSecurityPolicy`.
+	 *
+	 * WARNING: Using this API incorrectly may make the instance more insecure.
+	 * Do think twice before adding whitelisting resources. Please do also note
+	 * that it is not possible to use the `disallowXYZ` functions.
+	 *
+	 * @param EmptyContentSecurityPolicy $policy
+	 * @since 9.0.0
+	 */
+	public function addDefaultPolicy(EmptyContentSecurityPolicy $policy);
+}