Always yield a CSP policy instance

If the app has the CSP disabled globally allow a controller action
to enable the policy for that request.

2 files changed, 63 insertions, 13 deletions

diff --git a/actionpack/lib/action_controller/metal/content_security_policy.rb b/actionpack/lib/action_controller/metal/content_security_policy.rb
index 67682e7f4f..b8fab4ebe3 100644
--- a/actionpack/lib/action_controller/metal/content_security_policy.rb
+++ b/actionpack/lib/action_controller/metal/content_security_policy.rb
@@ -17,7 +17,7 @@ module ActionController #:nodoc:
       def content_security_policy(enabled = true, **options, &block)
         before_action(options) do
           if block_given?
-            policy = request.content_security_policy.clone
+            policy = current_content_security_policy
             yield policy
             request.content_security_policy = policy
           end
@@ -44,5 +44,9 @@ module ActionController #:nodoc:
       def content_security_policy_nonce
         request.content_security_policy_nonce
       end
+
+      def current_content_security_policy
+        request.content_security_policy.try(:clone) || ActionDispatch::ContentSecurityPolicy.new
+      end
   end
 end
diff --git a/actionpack/test/dispatch/content_security_policy_test.rb b/actionpack/test/dispatch/content_security_policy_test.rb
index 205bce16d4..f133aae865 100644
--- a/actionpack/test/dispatch/content_security_policy_test.rb
+++ b/actionpack/test/dispatch/content_security_policy_test.rb
@@ -369,18 +369,6 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
 
   private
 
-    def env_config
-      Rails.application.env_config
-    end
-
-    def content_security_policy
-      env_config["action_dispatch.content_security_policy"]
-    end
-
-    def content_security_policy=(policy)
-      env_config["action_dispatch.content_security_policy"] = policy
-    end
-
     def assert_policy(expected, report_only: false)
       assert_response :success
 
@@ -396,3 +384,61 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
       assert_equal expected, response.headers[expected_header]
     end
 end
+
+class DisabledContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
+  class PolicyController < ActionController::Base
+    content_security_policy only: :inline do |p|
+      p.default_src "https://example.com"
+    end
+
+    def index
+      head :ok
+    end
+
+    def inline
+      head :ok
+    end
+  end
+
+  ROUTES = ActionDispatch::Routing::RouteSet.new
+  ROUTES.draw do
+    scope module: "disabled_content_security_policy_integration_test" do
+      get "/", to: "policy#index"
+      get "/inline", to: "policy#inline"
+    end
+  end
+
+  class PolicyConfigMiddleware
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      env["action_dispatch.content_security_policy"] = nil
+      env["action_dispatch.content_security_policy_nonce_generator"] = nil
+      env["action_dispatch.content_security_policy_report_only"] = false
+      env["action_dispatch.show_exceptions"] = false
+
+      @app.call(env)
+    end
+  end
+
+  APP = build_app(ROUTES) do |middleware|
+    middleware.use PolicyConfigMiddleware
+    middleware.use ActionDispatch::ContentSecurityPolicy::Middleware
+  end
+
+  def app
+    APP
+  end
+
+  def test_generates_no_content_security_policy_by_default
+    get "/"
+    assert_nil response.headers["Content-Security-Policy"]
+  end
+
+  def test_generates_content_security_policy_header_when_globally_disabled
+    get "/inline"
+    assert_equal "default-src https://example.com", response.headers["Content-Security-Policy"]
+  end
+end