Fix MRF policies to also work with Update

Objects who got updated would just pass through several of the MRF policies, undoing moderation in some situations.
In the relevant cases we now check not only for Create activities, but also Update activities.

I checked which ones checked explicitly on type Create using `grep '"type" => "Create"' lib/pleroma/web/activity_pub/mrf/*`.

The following from that list have not been changed:
* lib/pleroma/web/activity_pub/mrf/follow_bot_policy.ex
    * Not relevant for moderation
* lib/pleroma/web/activity_pub/mrf/keyword_policy.ex
    * Already had a test for Update
* lib/pleroma/web/activity_pub/mrf/object_age_policy.ex
    * In practice only relevant when fetching old objects (e.g. through Like or Announce). These are always wrapped in a Create.
* lib/pleroma/web/activity_pub/mrf/reject_non_public.ex
    * We don't allow changing scope with Update, so not relevant here

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

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.MRF.ActivityExpirationPolicy do
-  @moduledoc "Adds expiration to all local Create activities"
+  @moduledoc "Adds expiration to all local Create/Update activities"
   @behaviour Pleroma.Web.ActivityPub.MRF.Policy
 
   @impl true
@@ -25,8 +25,13 @@ defp local?(%{"actor" => actor}) do
     String.starts_with?(actor, Pleroma.Web.Endpoint.url())
   end
 
-  defp note?(activity) do
-    match?(%{"type" => "Create", "object" => %{"type" => "Note"}}, activity)
+  defp note?(%{"type" => type, "object" => %{"type" => "Note"}})
+       when type in ["Create", "Update"] do
+    true
+  end
+
+  defp note?(_) do
+    false
   end
 
   defp maybe_add_expiration(activity) do

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

@@ -29,7 +29,8 @@ defp contains_links?(%{"content" => content} = _object) do
   defp contains_links?(_), do: false
 
   @impl true
-  def filter(%{"type" => "Create", "actor" => actor, "object" => object} = message) do
+  def filter(%{"type" => type, "actor" => actor, "object" => object} = message)
+      when type in ["Create", "Update"] do
     with {:ok, %User{local: false} = u} <- User.get_or_fetch_by_ap_id(actor),
          {:contains_links, true} <- {:contains_links, contains_links?(object)},
          {:old_user, true} <- {:old_user, old_user?(u)} do

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

@@ -17,13 +17,14 @@ defp check_if_bot(user), do: check_by_actor_type(user) or check_by_nickname(user
   @impl true
   def filter(
         %{
-          "type" => "Create",
+          "type" => type,
           "to" => to,
           "cc" => cc,
           "actor" => actor,
           "object" => object
         } = message
-      ) do
+      )
+      when type in ["Create", "Update"] do
     user = User.get_cached_by_ap_id(actor)
     isbot = check_if_bot(user)
 

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

@@ -73,8 +73,8 @@ defp get_recipient_count(message) do
   end
 
   @impl true
-  def filter(%{"type" => "Create", "object" => %{"type" => object_type}} = message)
-      when object_type in ~w{Note Article} do
+  def filter(%{"type" => type, "object" => %{"type" => object_type}} = message)
+      when type in ~w{Create Update} and object_type in ~w{Note Article} do
     reject_threshold =
       Pleroma.Config.get(
         [:mrf_hellthread, :reject_threshold],

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

@@ -8,7 +8,7 @@ defmodule Pleroma.Web.ActivityPub.MRF.MentionPolicy do
   @behaviour Pleroma.Web.ActivityPub.MRF.Policy
 
   @impl true
-  def filter(%{"type" => "Create"} = message) do
+  def filter(%{"type" => type} = message) when type in ["Create", "Update"] do
     reject_actors = Pleroma.Config.get([:mrf_mention, :actors], [])
     recipients = (message["to"] || []) ++ (message["cc"] || [])
 

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

@@ -40,9 +40,9 @@ defp check_reject(%{host: actor_host} = _actor_info, object) do
 
   defp check_media_removal(
          %{host: actor_host} = _actor_info,
-         %{"type" => "Create", "object" => %{"attachment" => child_attachment}} = object
+         %{"type" => type, "object" => %{"attachment" => child_attachment}} = object
        )
-       when length(child_attachment) > 0 do
+       when type in ["Create", "Update"] and length(child_attachment) > 0 do
     media_removal =
       instance_list(:media_removal)
       |> MRF.subdomains_regex()
@@ -63,10 +63,11 @@ defp check_media_removal(_actor_info, object), do: {:ok, object}
   defp check_media_nsfw(
          %{host: actor_host} = _actor_info,
          %{
-           "type" => "Create",
+           "type" => type,
            "object" => %{} = _child_object
          } = object
-       ) do
+       )
+       when type in ["Create", "Update"] do
     media_nsfw =
       instance_list(:media_nsfw)
       |> MRF.subdomains_regex()

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

@@ -58,7 +58,8 @@ defp process_tag(
            "actor" => actor,
            "object" => object
          } = message
-       ) when type in ["Create", "Update"] do
+       )
+       when type in ["Create", "Update"] do
     user = User.get_cached_by_ap_id(actor)
 
     if Enum.member?(to, Pleroma.Constants.as_public()) do
@@ -91,7 +92,8 @@ defp process_tag(
            "actor" => actor,
            "object" => object
          } = message
-       ) when type in ["Create", "Update"] do
+       )
+       when type in ["Create", "Update"] do
     user = User.get_cached_by_ap_id(actor)
 
     if Enum.member?(to, Pleroma.Constants.as_public()) or

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

@@ -19,6 +19,16 @@ test "adds `expires_at` property" do
              })
 
     assert Timex.diff(expires_at, DateTime.utc_now(), :days) == 364
+
+    assert {:ok, %{"type" => "Update", "expires_at" => expires_at}} =
+             ActivityExpirationPolicy.filter(%{
+               "id" => @id,
+               "actor" => @local_actor,
+               "type" => "Update",
+               "object" => %{"type" => "Note"}
+             })
+
+    assert Timex.diff(expires_at, DateTime.utc_now(), :days) == 364
   end
 
   test "keeps existing `expires_at` if it less than the config setting" do
@@ -32,6 +42,15 @@ test "keeps existing `expires_at` if it less than the config setting" do
                "expires_at" => expires_at,
                "object" => %{"type" => "Note"}
              })
+
+    assert {:ok, %{"type" => "Update", "expires_at" => ^expires_at}} =
+             ActivityExpirationPolicy.filter(%{
+               "id" => @id,
+               "actor" => @local_actor,
+               "type" => "Update",
+               "expires_at" => expires_at,
+               "object" => %{"type" => "Note"}
+             })
   end
 
   test "overwrites existing `expires_at` if it greater than the config setting" do
@@ -47,6 +66,17 @@ test "overwrites existing `expires_at` if it greater than the config setting" do
              })
 
     assert Timex.diff(expires_at, DateTime.utc_now(), :days) == 364
+
+    assert {:ok, %{"type" => "Update", "expires_at" => expires_at}} =
+             ActivityExpirationPolicy.filter(%{
+               "id" => @id,
+               "actor" => @local_actor,
+               "type" => "Update",
+               "expires_at" => too_distant_future,
+               "object" => %{"type" => "Note"}
+             })
+
+    assert Timex.diff(expires_at, DateTime.utc_now(), :days) == 364
   end
 
   test "ignores remote activities" do
@@ -59,9 +89,19 @@ test "ignores remote activities" do
              })
 
     refute Map.has_key?(activity, "expires_at")
+
+    assert {:ok, activity} =
+             ActivityExpirationPolicy.filter(%{
+               "id" => "https://example.com/123",
+               "actor" => "https://example.com/users/cofe",
+               "type" => "Update",
+               "object" => %{"type" => "Note"}
+             })
+
+    refute Map.has_key?(activity, "expires_at")
   end
 
-  test "ignores non-Create/Note activities" do
+  test "ignores non-Create/Update/Note activities" do
     assert {:ok, activity} =
              ActivityExpirationPolicy.filter(%{
                "id" => "https://example.com/123",

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

@@ -32,6 +32,28 @@ defmodule Pleroma.Web.ActivityPub.MRF.AntiLinkSpamPolicyTest do
     }
   }
 
+  @linkless_update_message %{
+    "type" => "Update",
+    "object" => %{
+      "content" => "hi world!"
+    }
+  }
+
+  @linkful_update_message %{
+    "type" => "Update",
+    "object" => %{
+      "content" => "<a href='https://example.com'>hi world!</a>"
+    }
+  }
+
+  @response_update_message %{
+    "type" => "Update",
+    "object" => %{
+      "name" => "yes",
+      "type" => "Answer"
+    }
+  }
+
   describe "with new user" do
     test "it allows posts without links" do
       user = insert(:user, local: false)
@@ -42,7 +64,12 @@ test "it allows posts without links" do
         @linkless_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkless_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
 
     test "it disallows posts with links" do
@@ -66,7 +93,24 @@ test "it disallows posts with links" do
         }
       }
 
+      update_message = %{
+        "type" => "Update",
+        "actor" => user.ap_id,
+        "object" => %{
+          "formerRepresentations" => %{
+            "type" => "OrderedCollection",
+            "orderedItems" => [
+              %{
+                "content" => "<a href='https://example.com'>hi world!</a>"
+              }
+            ]
+          },
+          "content" => "mew"
+        }
+      }
+
       {:reject, _} = MRF.filter_one(AntiLinkSpamPolicy, message)
+      {:reject, _} = MRF.filter_one(AntiLinkSpamPolicy, update_message)
     end
 
     test "it allows posts with links for local users" do
@@ -78,7 +122,12 @@ test "it allows posts with links for local users" do
         @linkful_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkful_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
 
     test "it disallows posts with links in history" do
@@ -90,7 +139,12 @@ test "it disallows posts with links in history" do
         @linkful_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkful_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:reject, _} = AntiLinkSpamPolicy.filter(message)
+      {:reject, _} = AntiLinkSpamPolicy.filter(update_message)
     end
   end
 
@@ -104,7 +158,12 @@ test "it allows posts without links" do
         @linkless_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkless_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
 
     test "it allows posts with links" do
@@ -116,7 +175,12 @@ test "it allows posts with links" do
         @linkful_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkful_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
   end
 
@@ -130,7 +194,12 @@ test "it allows posts without links" do
         @linkless_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkless_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
 
     test "it allows posts with links" do
@@ -142,7 +211,12 @@ test "it allows posts with links" do
         @linkful_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @linkful_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
   end
 
@@ -161,9 +235,17 @@ test "it rejects posts without links" do
         @linkless_message
         |> Map.put("actor", "http://invalid.actor")
 
+      update_message =
+        @linkless_update_message
+        |> Map.put("actor", "http://invalid.actor")
+
       assert capture_log(fn ->
                {:reject, _} = AntiLinkSpamPolicy.filter(message)
              end) =~ "[error] Could not decode user at fetch http://invalid.actor"
+
+      assert capture_log(fn ->
+               {:reject, _} = AntiLinkSpamPolicy.filter(update_message)
+             end) =~ "[error] Could not decode user at fetch http://invalid.actor"
     end
 
     test "it rejects posts with links" do
@@ -171,9 +253,17 @@ test "it rejects posts with links" do
         @linkful_message
         |> Map.put("actor", "http://invalid.actor")
 
+      update_message =
+        @linkful_update_message
+        |> Map.put("actor", "http://invalid.actor")
+
       assert capture_log(fn ->
                {:reject, _} = AntiLinkSpamPolicy.filter(message)
              end) =~ "[error] Could not decode user at fetch http://invalid.actor"
+
+      assert capture_log(fn ->
+               {:reject, _} = AntiLinkSpamPolicy.filter(update_message)
+             end) =~ "[error] Could not decode user at fetch http://invalid.actor"
     end
   end
 
@@ -185,7 +275,12 @@ test "it does not reject them or error out" do
         @response_message
         |> Map.put("actor", user.ap_id)
 
+      update_message =
+        @response_update_message
+        |> Map.put("actor", user.ap_id)
+
       {:ok, _message} = AntiLinkSpamPolicy.filter(message)
+      {:ok, _update_message} = AntiLinkSpamPolicy.filter(update_message)
     end
   end
 end

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

@@ -26,35 +26,60 @@ defp generate_messages(actor) do
      }}
   end
 
+  defp generate_update_messages(actor) do
+    {%{
+       "actor" => actor.ap_id,
+       "type" => "Update",
+       "object" => %{},
+       "to" => [@public, "f"],
+       "cc" => [actor.follower_address, "d"]
+     },
+     %{
+       "actor" => actor.ap_id,
+       "type" => "Update",
+       "object" => %{"to" => ["f", actor.follower_address], "cc" => ["d", @public]},
+       "to" => ["f", actor.follower_address],
+       "cc" => ["d", @public]
+     }}
+  end
+
   test "removes from the federated timeline by nickname heuristics 1" do
     actor = insert(:user, %{nickname: "annoying_ebooks@example.com"})
 
     {message, except_message} = generate_messages(actor)
+    {update_message, except_update_message} = generate_update_messages(actor)
 
     assert ForceBotUnlistedPolicy.filter(message) == {:ok, except_message}
+    assert ForceBotUnlistedPolicy.filter(update_message) == {:ok, except_update_message}
   end
 
   test "removes from the federated timeline by nickname heuristics 2" do
     actor = insert(:user, %{nickname: "cirnonewsnetworkbot@meow.cat"})
 
     {message, except_message} = generate_messages(actor)
+    {update_message, except_update_message} = generate_update_messages(actor)
 
     assert ForceBotUnlistedPolicy.filter(message) == {:ok, except_message}
+    assert ForceBotUnlistedPolicy.filter(update_message) == {:ok, except_update_message}
   end
 
   test "removes from the federated timeline by actor type Application" do
     actor = insert(:user, %{actor_type: "Application"})
 
     {message, except_message} = generate_messages(actor)
+    {update_message, except_update_message} = generate_update_messages(actor)
 
     assert ForceBotUnlistedPolicy.filter(message) == {:ok, except_message}
+    assert ForceBotUnlistedPolicy.filter(update_message) == {:ok, except_update_message}
   end
 
   test "removes from the federated timeline by actor type Service" do
     actor = insert(:user, %{actor_type: "Service"})
 
     {message, except_message} = generate_messages(actor)
+    {update_message, except_update_message} = generate_update_messages(actor)
 
     assert ForceBotUnlistedPolicy.filter(message) == {:ok, except_message}
+    assert ForceBotUnlistedPolicy.filter(update_message) == {:ok, except_update_message}
   end
 end

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

@@ -26,54 +26,86 @@ defmodule Pleroma.Web.ActivityPub.MRF.HellthreadPolicyTest do
       }
     }
 
-    [user: user, message: message]
+    update_message = %{
+      "actor" => user.ap_id,
+      "cc" => [user.follower_address],
+      "type" => "Update",
+      "to" => [
+        "https://www.w3.org/ns/activitystreams#Public",
+        "https://instance.tld/users/user1",
+        "https://instance.tld/users/user2",
+        "https://instance.tld/users/user3"
+      ],
+      "object" => %{
+        "type" => "Note"
+      }
+    }
+
+    [user: user, message: message, update_message: update_message]
   end
 
   setup do: clear_config(:mrf_hellthread)
 
   describe "reject" do
     test "rejects the message if the recipient count is above reject_threshold", %{
-      message: message
+      message: message,
+      update_message: update_message
     } do
       clear_config([:mrf_hellthread], %{delist_threshold: 0, reject_threshold: 2})
 
       assert {:reject, "[HellthreadPolicy] 3 recipients is over the limit of 2"} ==
                filter(message)
+
+      assert {:reject, "[HellthreadPolicy] 3 recipients is over the limit of 2"} ==
+               filter(update_message)
     end
 
     test "does not reject the message if the recipient count is below reject_threshold", %{
-      message: message
+      message: message,
+      update_message: update_message
     } do
       clear_config([:mrf_hellthread], %{delist_threshold: 0, reject_threshold: 3})
 
       assert {:ok, ^message} = filter(message)
+      assert {:ok, ^update_message} = filter(update_message)
     end
   end
 
   describe "delist" do
     test "delists the message if the recipient count is above delist_threshold", %{
       user: user,
-      message: message
+      message: message,
+      update_message: update_message
     } do
       clear_config([:mrf_hellthread], %{delist_threshold: 2, reject_threshold: 0})
 
       {:ok, message} = filter(message)
       assert user.follower_address in message["to"]
       assert "https://www.w3.org/ns/activitystreams#Public" in message["cc"]
+
+      {:ok, update_message} = filter(update_message)
+      assert user.follower_address in update_message["to"]
+      assert "https://www.w3.org/ns/activitystreams#Public" in update_message["cc"]
     end
 
     test "does not delist the message if the recipient count is below delist_threshold", %{
-      message: message
+      message: message,
+      update_message: update_message
     } do
       clear_config([:mrf_hellthread], %{delist_threshold: 4, reject_threshold: 0})
 
       assert {:ok, ^message} = filter(message)
+      assert {:ok, ^update_message} = filter(update_message)
     end
   end
 
-  test "excludes follower collection and public URI from threshold count", %{message: message} do
+  test "excludes follower collection and public URI from threshold count", %{
+    message: message,
+    update_message: update_message
+  } do
     clear_config([:mrf_hellthread], %{delist_threshold: 0, reject_threshold: 3})
 
     assert {:ok, ^message} = filter(message)
+    assert {:ok, ^update_message} = filter(update_message)
   end
 end

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

@@ -18,7 +18,14 @@ test "pass filter if allow list is empty" do
       "cc" => ["https://example.com/blocked"]
     }
 
+    update_message = %{
+      "type" => "Update",
+      "to" => ["https://example.com/ok"],
+      "cc" => ["https://example.com/blocked"]
+    }
+
     assert MentionPolicy.filter(message) == {:ok, message}
+    assert MentionPolicy.filter(update_message) == {:ok, update_message}
   end
 
   describe "allow" do
@@ -29,7 +36,12 @@ test "empty" do
         "type" => "Create"
       }
 
+      update_message = %{
+        "type" => "Update"
+      }
+
       assert MentionPolicy.filter(message) == {:ok, message}
+      assert MentionPolicy.filter(update_message) == {:ok, update_message}
     end
 
     test "to" do
@@ -40,7 +52,13 @@ test "to" do
         "to" => ["https://example.com/ok"]
       }
 
+      update_message = %{
+        "type" => "Update",
+        "to" => ["https://example.com/ok"]
+      }
+
       assert MentionPolicy.filter(message) == {:ok, message}
+      assert MentionPolicy.filter(update_message) == {:ok, update_message}
     end
 
     test "cc" do
@@ -51,7 +69,13 @@ test "cc" do
         "cc" => ["https://example.com/ok"]
       }
 
+      update_message = %{
+        "type" => "Update",
+        "cc" => ["https://example.com/ok"]
+      }
+
       assert MentionPolicy.filter(message) == {:ok, message}
+      assert MentionPolicy.filter(update_message) == {:ok, update_message}
     end
 
     test "both" do
@@ -63,7 +87,14 @@ test "both" do
         "cc" => ["https://example.com/ok2"]
       }
 
+      update_message = %{
+        "type" => "Update",
+        "to" => ["https://example.com/ok"],
+        "cc" => ["https://example.com/ok2"]
+      }
+
       assert MentionPolicy.filter(message) == {:ok, message}
+      assert MentionPolicy.filter(update_message) == {:ok, update_message}
     end
   end
 
@@ -76,8 +107,16 @@ test "to" do
         "to" => ["https://example.com/blocked"]
       }
 
+      update_message = %{
+        "type" => "Update",
+        "to" => ["https://example.com/blocked"]
+      }
+
       assert MentionPolicy.filter(message) ==
                {:reject, "[MentionPolicy] Rejected for mention of https://example.com/blocked"}
+
+      assert MentionPolicy.filter(update_message) ==
+               {:reject, "[MentionPolicy] Rejected for mention of https://example.com/blocked"}
     end
 
     test "cc" do
@@ -89,8 +128,17 @@ test "cc" do
         "cc" => ["https://example.com/blocked"]
       }
 
+      update_message = %{
+        "type" => "Update",
+        "to" => ["https://example.com/ok"],
+        "cc" => ["https://example.com/blocked"]
+      }
+
       assert MentionPolicy.filter(message) ==
                {:reject, "[MentionPolicy] Rejected for mention of https://example.com/blocked"}
+
+      assert MentionPolicy.filter(update_message) ==
+               {:reject, "[MentionPolicy] Rejected for mention of https://example.com/blocked"}
     end
   end
 end

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

@@ -26,15 +26,18 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicyTest do
     test "is empty" do
       clear_config([:mrf_simple, :media_removal], [])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) == {:ok, media_message}
+      assert SimplePolicy.filter(media_update_message) == {:ok, media_update_message}
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
 
     test "has a matching host" do
       clear_config([:mrf_simple, :media_removal], [{"remote.instance", "Some reason"}])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) ==
@@ -42,12 +45,18 @@ test "has a matching host" do
                 media_message
                 |> Map.put("object", Map.delete(media_message["object"], "attachment"))}
 
+      assert SimplePolicy.filter(media_update_message) ==
+               {:ok,
+                media_update_message
+                |> Map.put("object", Map.delete(media_update_message["object"], "attachment"))}
+
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
 
     test "match with wildcard domain" do
       clear_config([:mrf_simple, :media_removal], [{"*.remote.instance", "Whatever reason"}])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) ==
@@ -55,6 +64,11 @@ test "match with wildcard domain" do
                 media_message
                 |> Map.put("object", Map.delete(media_message["object"], "attachment"))}
 
+      assert SimplePolicy.filter(media_update_message) ==
+               {:ok,
+                media_update_message
+                |> Map.put("object", Map.delete(media_update_message["object"], "attachment"))}
+
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
   end
@@ -63,31 +77,41 @@ test "match with wildcard domain" do
     test "is empty" do
       clear_config([:mrf_simple, :media_nsfw], [])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) == {:ok, media_message}
+      assert SimplePolicy.filter(media_update_message) == {:ok, media_update_message}
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
 
     test "has a matching host" do
       clear_config([:mrf_simple, :media_nsfw], [{"remote.instance", "Whetever"}])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) ==
                {:ok, put_in(media_message, ["object", "sensitive"], true)}
 
+      assert SimplePolicy.filter(media_update_message) ==
+               {:ok, put_in(media_update_message, ["object", "sensitive"], true)}
+
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
 
     test "match with wildcard domain" do
       clear_config([:mrf_simple, :media_nsfw], [{"*.remote.instance", "yeah yeah"}])
       media_message = build_media_message()
+      media_update_message = build_media_update_message()
       local_message = build_local_message()
 
       assert SimplePolicy.filter(media_message) ==
                {:ok, put_in(media_message, ["object", "sensitive"], true)}
 
+      assert SimplePolicy.filter(media_update_message) ==
+               {:ok, put_in(media_update_message, ["object", "sensitive"], true)}
+
       assert SimplePolicy.filter(local_message) == {:ok, local_message}
     end
   end
@@ -104,6 +128,18 @@ defp build_media_message do
     }
   end
 
+  defp build_media_update_message do
+    %{
+      "actor" => "https://remote.instance/users/bob",
+      "type" => "Update",
+      "object" => %{
+        "attachment" => [%{}],
+        "tag" => ["foo"],
+        "sensitive" => false
+      }
+    }
+  end
+
   describe "when :report_removal" do
     test "is empty" do
       clear_config([:mrf_simple, :report_removal], [])