Extract authorization policy for viewing statuses (#3150)

app/controllers/api/activitypub/activities_controller.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class Api::Activitypub::ActivitiesController < ApiController
+  include Authorization
+
   # before_action :set_follow, only: [:show_follow]
   before_action :set_status, only: [:show_status]
 
@@ -8,7 +10,7 @@ class Api::Activitypub::ActivitiesController < ApiController
 
   # Show a status in AS2 format, as either an Announce (reblog) or a Create (post) activity.
   def show_status
-    return forbidden unless @status.permitted?
+    authorize @status, :show?
 
     if @status.reblog?
       render :show_status_announce

app/controllers/api/activitypub/notes_controller.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
 class Api::Activitypub::NotesController < ApiController
+  include Authorization
+
   before_action :set_status
 
   respond_to :activitystreams2
 
   def show
-    forbidden unless @status.permitted?
+    authorize @status, :show?
   end
 
   private

app/controllers/api/v1/statuses_controller.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class Api::V1::StatusesController < ApiController
+  include Authorization
+
   before_action :authorize_if_got_token, except:            [:create, :destroy, :reblog, :unreblog, :favourite, :unfavourite, :mute, :unmute]
   before_action -> { doorkeeper_authorize! :write }, only:  [:create, :destroy, :reblog, :unreblog, :favourite, :unfavourite, :mute, :unmute]
   before_action :require_user!, except:  [:show, :context, :card, :reblogged_by, :favourited_by]
@@ -130,7 +132,10 @@ class Api::V1::StatusesController < ApiController
 
   def set_status
     @status = Status.find(params[:id])
-    raise ActiveRecord::RecordNotFound unless @status.permitted?(current_account)
+    authorize @status, :show?
+  rescue Mastodon::NotPermittedError
+    # Reraise in order to get a 404 instead of a 403 error code
+    raise ActiveRecord::RecordNotFound
   end
 
   def set_conversation