Merge pull request 'Notifications: do not notify tagged users who cannot see the post' (#8022) from lambadalambda/pleroma:fix/mention-notify-access into develop

Reviewed-on: https://git.pleroma.social/pleroma/pleroma/pulls/8022

changelog.d/mention-notify-access.security

@@ -0,0 +1 @@
+Do not notify tagged users who cannot see the post

lib/pleroma/web/common_api/utils.ex

@@ -435,13 +435,56 @@ defmodule Pleroma.Web.CommonAPI.Utils do
           %{}
       end
 
-    tagged_mentions = maybe_extract_mentions(object_data)
+    tagged_mentions =
+      maybe_extract_mentions(object_data)
+      |> filter_tags_to_qualified(activity)
 
     recipients ++ tagged_mentions
   end
 
   def maybe_notify_mentioned_recipients(recipients, _), do: recipients
 
+  # Filter tagged mentions to ensure they can actually access the status
+  defp filter_tags_to_qualified(tagged_mentions, %Activity{
+         recipients: recipients,
+         data: data,
+         actor: actor
+       }) do
+    recipients =
+      if recipients && recipients != [],
+        do: recipients,
+        else:
+          (data["to"] || []) ++ (data["cc"] || []) ++ (data["bto"] || []) ++ (data["bcc"] || [])
+
+    cond do
+      recipients == [] ->
+        []
+
+      Pleroma.Constants.as_public() in recipients ->
+        tagged_mentions
+
+      true ->
+        author = User.get_cached_by_ap_id(actor)
+        to_followers = match?(%User{}, author) and author.follower_address in recipients
+
+        Enum.filter(tagged_mentions, fn tagged ->
+          cond do
+            tagged in recipients ->
+              true
+
+            to_followers ->
+              case User.get_cached_by_ap_id(tagged) do
+                %User{} = tagged_user -> User.following?(tagged_user, author)
+                _ -> false
+              end
+
+            true ->
+              false
+          end
+        end)
+    end
+  end
+
   def maybe_notify_followers(recipients, %Activity{data: %{"type" => "Move"}} = activity) do
     with %User{} = user <- User.get_cached_by_ap_id(activity.actor) do
       user

test/pleroma/notification_test.exs

@@ -7,6 +7,8 @@ defmodule Pleroma.NotificationTest do
 
   import Pleroma.Factory
 
+  require Pleroma.Constants
+
   alias Pleroma.FollowingRelationship
   alias Pleroma.Notification
   alias Pleroma.Object
@@ -628,6 +630,102 @@ defmodule Pleroma.NotificationTest do
       assert other_user in enabled_receivers
     end
 
+    defp incoming_note_tagging(author, to, tagged_ap_ids) do
+      tags = Enum.map(tagged_ap_ids, &%{"type" => "Mention", "href" => &1, "name" => &1})
+
+      {:ok, activity} =
+        Transmogrifier.handle_incoming(%{
+          "@context" => "https://www.w3.org/ns/activitystreams",
+          "type" => "Create",
+          "to" => to,
+          "actor" => author.ap_id,
+          "object" => %{
+            "type" => "Note",
+            "id" => Pleroma.Web.ActivityPub.Utils.generate_object_id(),
+            "to" => to,
+            "content" => "tagged",
+            "tag" => tags,
+            "attributedTo" => author.ap_id
+          }
+        })
+
+      activity
+    end
+
+    defp notified_ap_ids(activity),
+      do: activity |> Notification.get_notified_from_activity() |> Enum.map(& &1.ap_id)
+
+    test "it does not notify tagged users who cannot see a followers-only post" do
+      author = insert(:user)
+      tagged = insert(:user)
+
+      activity = incoming_note_tagging(author, [author.follower_address], [tagged.ap_id])
+
+      refute tagged.ap_id in notified_ap_ids(activity)
+    end
+
+    test "it notifies tagged followers of a followers-only post" do
+      author = insert(:user)
+      tagged = insert(:user)
+      {:ok, _, _} = Pleroma.User.follow(tagged, author)
+
+      activity = incoming_note_tagging(author, [author.follower_address], [tagged.ap_id])
+
+      assert tagged.ap_id in notified_ap_ids(activity)
+    end
+
+    test "it does not notify tagged users who are not addressed by a direct message" do
+      author = insert(:user)
+      addressed = insert(:user)
+      tagged = insert(:user)
+
+      activity = incoming_note_tagging(author, [addressed.ap_id], [tagged.ap_id])
+      receivers = notified_ap_ids(activity)
+
+      assert addressed.ap_id in receivers
+      refute tagged.ap_id in receivers
+    end
+
+    test "it notifies tagged users of a public post even if they are not addressed" do
+      author = insert(:user)
+      tagged = insert(:user)
+
+      activity =
+        incoming_note_tagging(author, [Pleroma.Constants.as_public()], [tagged.ap_id])
+
+      assert tagged.ap_id in notified_ap_ids(activity)
+    end
+
+    test "it does not notify tagged users with a pending follow request" do
+      author = insert(:user, is_locked: true)
+      tagged = insert(:user)
+      {:ok, _, _, _} = CommonAPI.follow(author, tagged)
+
+      activity = incoming_note_tagging(author, [author.follower_address], [tagged.ap_id])
+
+      refute tagged.ap_id in notified_ap_ids(activity)
+    end
+
+    test "it ignores tags of unknown users in a followers-only post" do
+      author = insert(:user)
+      tagged = insert(:user)
+
+      follower = insert(:user)
+      {:ok, _, _} = Pleroma.User.follow(follower, author)
+
+      activity =
+        incoming_note_tagging(author, [author.follower_address], [
+          "https://unknown.example/users/nobody",
+          tagged.ap_id,
+          follower.ap_id
+        ])
+
+      receivers = notified_ap_ids(activity)
+
+      refute tagged.ap_id in receivers
+      assert follower.ap_id in receivers
+    end
+
     test "it does not send notifications to users who are only cc in new messages" do
       user = insert(:user)
       other_user = insert(:user)