Return 413 when an actor's banner or background exceeds the size limit

lib/pleroma/web/mastodon_api/controllers/account_controller.ex

@@ -254,6 +254,12 @@ def update_credentials(%{assigns: %{user: user}, body_params: params} = conn, _p
       {:error, %Ecto.Changeset{errors: [avatar: {"file is too large", _}]}} ->
         render_error(conn, :request_entity_too_large, "File is too large")
 
+      {:error, %Ecto.Changeset{errors: [banner: {"file is too large", _}]}} ->
+        render_error(conn, :request_entity_too_large, "File is too large")
+
+      {:error, %Ecto.Changeset{errors: [background: {"file is too large", _}]}} ->
+        render_error(conn, :request_entity_too_large, "File is too large")
+
       _e ->
         render_error(conn, :forbidden, "Invalid request")
     end

test/pleroma/web/mastodon_api/update_credentials_test.exs

@@ -319,6 +319,32 @@ test "updates the user's banner", %{user: user, conn: conn} do
       assert user.banner == nil
     end
 
+    test "updates the user's banner, upload_limit, returns a HTTP 413", %{conn: conn, user: user} do
+      upload_limit = Config.get([:instance, :upload_limit]) * 8 + 8
+
+      assert :ok ==
+               File.write(Path.absname("test/tmp/large_binary.data"), <<0::size(upload_limit)>>)
+
+      new_header_oversized = %Plug.Upload{
+        content_type: nil,
+        path: Path.absname("test/tmp/large_binary.data"),
+        filename: "large_binary.data"
+      }
+
+      res =
+        patch(conn, "/api/v1/accounts/update_credentials", %{"header" => new_header_oversized})
+
+      assert user_response = json_response_and_validate_schema(res, 413)
+      assert user_response["header"] != User.banner_url(user)
+
+      user = User.get_by_id(user.id)
+      assert user.banner == %{}
+
+      clear_config([:instance, :upload_limit], upload_limit)
+
+      assert :ok == File.rm(Path.absname("test/tmp/large_binary.data"))
+    end
+
     test "updates the user's background", %{conn: conn, user: user} do
       new_header = %Plug.Upload{
         content_type: "image/jpeg",
@@ -342,6 +368,34 @@ test "updates the user's background", %{conn: conn, user: user} do
       assert user.background == nil
     end
 
+    test "updates the user's background, upload_limit, returns a HTTP 413", %{
+      conn: conn,
+      user: user
+    } do
+      upload_limit = Config.get([:instance, :upload_limit]) * 8 + 8
+
+      assert :ok ==
+               File.write(Path.absname("test/tmp/large_binary.data"), <<0::size(upload_limit)>>)
+
+      new_background_oversized = %Plug.Upload{
+        content_type: nil,
+        path: Path.absname("test/tmp/large_binary.data"),
+        filename: "large_binary.data"
+      }
+
+      res =
+        patch(conn, "/api/v1/accounts/update_credentials", %{
+          "pleroma_background_image" => new_background_oversized
+        })
+
+      assert user_response = json_response_and_validate_schema(res, 413)
+      assert user.background == %{}
+
+      clear_config([:instance, :upload_limit], upload_limit)
+
+      assert :ok == File.rm(Path.absname("test/tmp/large_binary.data"))
+    end
+
     test "requires 'write:accounts' permission" do
       token1 = insert(:oauth_token, scopes: ["read"])
       token2 = insert(:oauth_token, scopes: ["write", "follow"])