Fix url guessing attacks.

lib/pleroma/web/activity_pub/activity_pub_controller.ex

@@ -20,10 +20,16 @@ def user(conn, %{"nickname" => nickname}) do
 
   def object(conn, %{"uuid" => uuid}) do
     with ap_id <- o_status_url(conn, :object, uuid),
-         %Object{} = object <- Object.get_cached_by_ap_id(ap_id) do
+         %Object{} = object <- Object.get_cached_by_ap_id(ap_id),
+         {_, true} <- {:public?, ActivityPub.is_public?(object)} do
       conn
       |> put_resp_header("content-type", "application/activity+json")
       |> json(ObjectView.render("object.json", %{object: object}))
+    else
+      {:public?, false} ->
+        conn
+        |> put_status(404)
+        |> json("Not found")
     end
   end
 

lib/pleroma/web/ostatus/ostatus_controller.ex

@@ -68,37 +68,47 @@ def salmon_incoming(conn, _) do
     |> send_resp(200, "")
   end
 
-  # TODO: Data leak
   def object(conn, %{"uuid" => uuid} = params) do
     if get_format(conn) == "activity+json" do
       ActivityPubController.object(conn, params)
     else
       with id <- o_status_url(conn, :object, uuid),
            %Activity{} = activity <- Activity.get_create_activity_by_object_ap_id(id),
+           {_, true} <- {:public?, ActivityPub.is_public?(activity)},
            %User{} = user <- User.get_cached_by_ap_id(activity.data["actor"]) do
         case get_format(conn) do
           "html" -> redirect(conn, to: "/notice/#{activity.id}")
           _ -> represent_activity(conn, activity, user)
         end
+      else
+        {:public?, false} ->
+          conn
+          |> put_status(404)
+          |> json("Not found")
       end
     end
   end
 
-  # TODO: Data leak
   def activity(conn, %{"uuid" => uuid}) do
     with id <- o_status_url(conn, :activity, uuid),
          %Activity{} = activity <- Activity.get_by_ap_id(id),
+         {_, true} <- {:public?, ActivityPub.is_public?(activity)},
          %User{} = user <- User.get_cached_by_ap_id(activity.data["actor"]) do
       case get_format(conn) do
         "html" -> redirect(conn, to: "/notice/#{activity.id}")
         _ -> represent_activity(conn, activity, user)
       end
+    else
+      {:public?, false} ->
+        conn
+        |> put_status(404)
+        |> json("Not found")
     end
   end
 
-  # TODO: Data leak
   def notice(conn, %{"id" => id}) do
     with %Activity{} = activity <- Repo.get(Activity, id),
+         {_, true} <- {:public?, ActivityPub.is_public?(activity)},
          %User{} = user <- User.get_cached_by_ap_id(activity.data["actor"]) do
       case get_format(conn) do
         "html" ->
@@ -109,6 +119,11 @@ def notice(conn, %{"id" => id}) do
         _ ->
           represent_activity(conn, activity, user)
       end
+    else
+      {:public?, false} ->
+        conn
+        |> put_status(404)
+        |> json("Not found")
     end
   end
 

test/web/activity_pub/activity_pub_controller_test.exs

@@ -4,6 +4,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubControllerTest do
   alias Pleroma.Web.ActivityPub.{UserView, ObjectView}
   alias Pleroma.{Repo, User}
   alias Pleroma.Activity
+  alias Pleroma.Web.CommonAPI
 
   describe "/users/:nickname" do
     test "it returns a json representation of the user", %{conn: conn} do
@@ -32,6 +33,18 @@ test "it returns a json representation of the object", %{conn: conn} do
 
       assert json_response(conn, 200) == ObjectView.render("object.json", %{object: note})
     end
+
+    test "it returns 404 for non-public messages", %{conn: conn} do
+      note = insert(:direct_note)
+      uuid = String.split(note.data["id"], "/") |> List.last()
+
+      conn =
+        conn
+        |> put_req_header("accept", "application/activity+json")
+        |> get("/objects/#{uuid}")
+
+      assert json_response(conn, 404)
+    end
   end
 
   describe "/users/:nickname/inbox" do

test/web/ostatus/ostatus_controller_test.exs

@@ -77,6 +77,19 @@ test "gets an object", %{conn: conn} do
     assert response(conn, 200) == expected
   end
 
+  test "404s on private objects", %{conn: conn} do
+    note_activity = insert(:direct_note_activity)
+    user = User.get_by_ap_id(note_activity.data["actor"])
+    [_, uuid] = hd(Regex.scan(~r/.+\/([\w-]+)$/, note_activity.data["object"]["id"]))
+    url = "/objects/#{uuid}"
+
+    conn =
+      conn
+      |> get(url)
+
+    assert response(conn, 404)
+  end
+
   test "gets an activity", %{conn: conn} do
     note_activity = insert(:note_activity)
     [_, uuid] = hd(Regex.scan(~r/.+\/([\w-]+)$/, note_activity.data["id"]))
@@ -89,6 +102,18 @@ test "gets an activity", %{conn: conn} do
     assert response(conn, 200)
   end
 
+  test "404s on private activities", %{conn: conn} do
+    note_activity = insert(:direct_note_activity)
+    [_, uuid] = hd(Regex.scan(~r/.+\/([\w-]+)$/, note_activity.data["id"]))
+    url = "/activities/#{uuid}"
+
+    conn =
+      conn
+      |> get(url)
+
+    assert response(conn, 404)
+  end
+
   test "gets a notice", %{conn: conn} do
     note_activity = insert(:note_activity)
     url = "/notice/#{note_activity.id}"
@@ -99,4 +124,15 @@ test "gets a notice", %{conn: conn} do
 
     assert response(conn, 200)
   end
+
+  test "404s a private notice", %{conn: conn} do
+    note_activity = insert(:direct_note_activity)
+    url = "/notice/#{note_activity.id}"
+
+    conn =
+      conn
+      |> get(url)
+
+    assert response(conn, 404)
+  end
 end