DeleteValidator: Don't federate local deletions of remote objects.

Closes #1497

lib/pleroma/web/activity_pub/object_validator.ex

@@ -19,11 +19,11 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   def validate(object, meta)
 
   def validate(%{"type" => "Delete"} = object, meta) do
-    with {:ok, object} <-
-           object
-           |> DeleteValidator.cast_and_validate()
-           |> Ecto.Changeset.apply_action(:insert) do
+    with cng <- DeleteValidator.cast_and_validate(object),
+         do_not_federate <- DeleteValidator.do_not_federate?(cng),
+         {:ok, object} <- Ecto.Changeset.apply_action(cng, :insert) do
       object = stringify_keys(object)
+      meta = Keyword.put(meta, :do_not_federate, do_not_federate)
       {:ok, object, meta}
     end
   end

lib/pleroma/web/activity_pub/object_validators/delete_validator.ex

@@ -6,6 +6,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator do
   use Ecto.Schema
 
   alias Pleroma.Activity
+  alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ObjectValidators.Types
 
   import Ecto.Changeset
@@ -45,12 +46,17 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator do
     cng
     |> validate_required([:id, :type, :actor, :to, :cc, :object])
     |> validate_inclusion(:type, ["Delete"])
-    |> validate_same_domain()
+    |> validate_actor_presence()
+    |> validate_deletion_rights()
     |> validate_object_or_user_presence()
     |> add_deleted_activity_id()
   end
 
-  def validate_same_domain(cng) do
+  def do_not_federate?(cng) do
+    !same_domain?(cng)
+  end
+
+  defp same_domain?(cng) do
     actor_domain =
       cng
       |> get_field(:actor)
@@ -63,11 +69,17 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator do
       |> URI.parse()
       |> (& &1.host).()
 
-    if object_domain != actor_domain do
+    object_domain == actor_domain
+  end
+
+  def validate_deletion_rights(cng) do
+    actor = User.get_cached_by_ap_id(get_field(cng, :actor))
+
+    if User.superuser?(actor) || same_domain?(cng) do
       cng
-      |> add_error(:actor, "is not allowed to delete object")
     else
       cng
+      |> add_error(:actor, "is not allowed to delete object")
     end
   end
 

lib/pleroma/web/activity_pub/pipeline.ex

@@ -29,7 +29,9 @@ defmodule Pleroma.Web.ActivityPub.Pipeline do
 
   defp maybe_federate(activity, meta) do
     with {:ok, local} <- Keyword.fetch(meta, :local) do
-      if local do
+      do_not_federate = meta[:do_not_federate]
+
+      if !do_not_federate && local do
         Federator.publish(activity)
         {:ok, :federated}
       else