Extract authorization policy for viewing statuses (#3150)

app/controllers/statuses_controller.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class StatusesController < ApplicationController
+  include Authorization
+
   layout 'public'
 
   before_action :set_account
@@ -30,7 +32,10 @@ class StatusesController < ApplicationController
     @stream_entry = @status.stream_entry
     @type         = @stream_entry.activity_type.downcase
 
-    raise ActiveRecord::RecordNotFound unless @status.permitted?(current_account)
+    authorize @status, :show?
+  rescue Mastodon::NotPermittedError
+    # Reraise in order to get a 404
+    raise ActiveRecord::RecordNotFound
   end
 
   def check_account_suspension