Merge branch 'simplepolicy-announce-leak' into 'develop'

SimplePolicy: filter nested objects, fixes #2582

Closes #2582

See merge request pleroma/pleroma!3376

CHANGELOG.md

@@ -33,6 +33,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Applying ConcurrentLimiter settings via AdminAPI
 - User login failures if their `notification_settings` were in a NULL state.
 - Mix task `pleroma.user delete_activities` query transaction timeout is now :infinity
+- MRF (`SimplePolicy`): Embedded objects are now checked. If any embedded object would be rejected, its parent is rejected. This fixes Announces leaking posts from blocked domains.
 - Fixed some Markdown issues, including trailing slash in links.
 
 ## [2.3.0] - 2020-03-01

lib/pleroma/web/activity_pub/mrf/simple_policy.ex

@@ -177,6 +177,14 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicy do
 
   defp check_banner_removal(_actor_info, object), do: {:ok, object}
 
+  defp check_object(%{"object" => object} = activity) do
+    with {:ok, _object} <- filter(object) do
+      {:ok, activity}
+    end
+  end
+
+  defp check_object(object), do: {:ok, object}
+
   @impl true
   def filter(%{"type" => "Delete", "actor" => actor} = object) do
     %{host: actor_host} = URI.parse(actor)
@@ -202,7 +210,8 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicy do
          {:ok, object} <- check_media_nsfw(actor_info, object),
          {:ok, object} <- check_ftl_removal(actor_info, object),
          {:ok, object} <- check_followers_only(actor_info, object),
-         {:ok, object} <- check_report_removal(actor_info, object) do
+         {:ok, object} <- check_report_removal(actor_info, object),
+         {:ok, object} <- check_object(object) do
       {:ok, object}
     else
       {:reject, nil} -> {:reject, "[SimplePolicy]"}
@@ -227,6 +236,19 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicy do
     end
   end
 
+  def filter(object) when is_binary(object) do
+    uri = URI.parse(object)
+
+    with {:ok, object} <- check_accept(uri, object),
+         {:ok, object} <- check_reject(uri, object) do
+      {:ok, object}
+    else
+      {:reject, nil} -> {:reject, "[SimplePolicy]"}
+      {:reject, _} = e -> e
+      _ -> {:reject, "[SimplePolicy]"}
+    end
+  end
+
   def filter(object), do: {:ok, object}
 
   @impl true

test/pleroma/web/activity_pub/mrf/simple_policy_test.exs

@@ -254,6 +254,30 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicyTest do
 
       assert {:reject, _} = SimplePolicy.filter(remote_user)
     end
+
+    test "reject Announce when object would be rejected" do
+      clear_config([:mrf_simple, :reject], ["blocked.tld"])
+
+      announce = %{
+        "type" => "Announce",
+        "actor" => "https://okay.tld/users/alice",
+        "object" => %{"type" => "Note", "actor" => "https://blocked.tld/users/bob"}
+      }
+
+      assert {:reject, _} = SimplePolicy.filter(announce)
+    end
+
+    test "reject by URI object" do
+      clear_config([:mrf_simple, :reject], ["blocked.tld"])
+
+      announce = %{
+        "type" => "Announce",
+        "actor" => "https://okay.tld/users/alice",
+        "object" => "https://blocked.tld/activities/1"
+      }
+
+      assert {:reject, _} = SimplePolicy.filter(announce)
+    end
   end
 
   describe "when :followers_only" do