Remove 'unsafe-inline' from Content-Security-Policy style-src (#13679)

* Make sure wicg-inert doesn't rely on inline CSS

* Remove unsafe-inline from style-src

app/views/layouts/application.html.haml

@@ -26,6 +26,8 @@
     = javascript_pack_tag "locale_#{I18n.locale}", integrity: true, crossorigin: 'anonymous'
     = csrf_meta_tags
 
+    = stylesheet_link_tag '/inert.css', skip_pipeline: true, media: 'all', id: 'inert-style'
+
     - if Setting.custom_css.present?
       = stylesheet_link_tag custom_css_path, media: 'all'
 

config/initializers/content_security_policy.rb

@@ -22,7 +22,7 @@ Rails.application.config.content_security_policy do |p|
   p.frame_ancestors :none
   p.font_src        :self, assets_host
   p.img_src         :self, :https, :data, :blob, assets_host
-  p.style_src       :self, :unsafe_inline, assets_host
+  p.style_src       :self, assets_host
   p.media_src       :self, :https, :data, assets_host
   p.frame_src       :self, :https
   p.manifest_src    :self, assets_host

public/inert.css

+[inert] {
+  pointer-events: none;
+  cursor: default;
+}
+
+[inert], [inert] * {
+  user-select: none;
+  -webkit-user-select: none;
+  -moz-user-select: none;
+  -ms-user-select: none;
+}