Add shared mode to Livebook sessions (#1128)

* add shared mode (working)

* add markdown write permission

* Add authorize handle_event

* Revert "add shared mode (working)"

This reverts commit c1e9ebac4d.

* Add assert_policy!

* Apply suggestions code review

* Apply suggestions from code review

* Apply suggestions from code reviews (redirect)

* Apply suggestions from code review

* Apply suggestions from code review

* Apply suggestions from code review

* Apply suggestions from code review

* Add PolicyHook

* remove assert_live_action_access!/1

* Apply suggestions from code review

* Apply suggestions from code review

* Update lib/livebook_web/live/session_live.ex

Co-authored-by: Jonatan Kłosko <jonatanklosko@gmail.com>

lib/livebook_web/live/hooks/policy_hook.ex

@@ -0,0 +1,7 @@
+defmodule LivebookWeb.PolicyHook do
+  import Phoenix.LiveView
+
+  def on_mount(:private, _params, _session, socket) do
+    {:cont, socket |> assign(:policy, %{read: true, execute: true, comment: true, edit: true})}
+  end
+end

lib/livebook_web/live/session_live.ex

@@ -549,12 +549,14 @@ defmodule LivebookWeb.SessionLive do
   end
 
   @impl true
-  def handle_params(%{"cell_id" => cell_id}, _url, socket) do
+  def handle_params(%{"cell_id" => cell_id}, _url, socket)
+      when socket.assigns.live_action in [:cell_settings, :cell_upload] do
     {:ok, cell, _} = Notebook.fetch_cell_and_section(socket.private.data.notebook, cell_id)
     {:noreply, assign(socket, cell: cell)}
   end
 
-  def handle_params(%{"section_id" => section_id}, _url, socket) do
+  def handle_params(%{"section_id" => section_id}, _url, socket)
+      when socket.assigns.live_action == :delete_section do
     {:ok, section} = Notebook.fetch_section(socket.private.data.notebook, section_id)
     first_section_id = hd(socket.private.data.notebook.sections).id
     {:noreply, assign(socket, section: section, first_section_id: first_section_id)}
@@ -565,17 +567,22 @@ defmodule LivebookWeb.SessionLive do
         _url,
         %{assigns: %{live_action: :catch_all}} = socket
       ) do
-    path_parts =
+    if socket.assigns.policy.edit do
-      Enum.map(path_parts, fn
+      path_parts =
-        "__parent__" -> ".."
+        Enum.map(path_parts, fn
-        part -> part
+          "__parent__" -> ".."
-      end)
+          part -> part
+        end)
 
-    path = Path.join(path_parts)
+      path = Path.join(path_parts)
-    {:noreply, handle_relative_path(socket, path)}
+      {:noreply, handle_relative_path(socket, path)}
+    else
+      {:noreply, socket |> put_flash(:error, "No access to navigate") |> redirect_to_self()}
+    end
   end
 
-  def handle_params(%{"tab" => tab}, _url, socket) do
+  def handle_params(%{"tab" => tab}, _url, socket)
+      when socket.assigns.live_action == :export do
     {:noreply, assign(socket, tab: tab)}
   end
 
@@ -585,6 +592,7 @@ defmodule LivebookWeb.SessionLive do
 
   @impl true
   def handle_event("append_section", %{}, socket) do
+    assert_policy!(socket, :edit)
     idx = length(socket.private.data.notebook.sections)
     Session.insert_section(socket.assigns.session.pid, idx)
 
@@ -592,6 +600,8 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("insert_section_below", params, socket) do
+    assert_policy!(socket, :edit)
+
     with {:ok, section, index} <-
            section_with_next_index(
              socket.private.data.notebook,
@@ -609,18 +619,21 @@ defmodule LivebookWeb.SessionLive do
         %{"section_id" => section_id, "parent_id" => parent_id},
         socket
       ) do
+    assert_policy!(socket, :edit)
     Session.set_section_parent(socket.assigns.session.pid, section_id, parent_id)
 
     {:noreply, socket}
   end
 
   def handle_event("unset_section_parent", %{"section_id" => section_id}, socket) do
+    assert_policy!(socket, :edit)
     Session.unset_section_parent(socket.assigns.session.pid, section_id)
 
     {:noreply, socket}
   end
 
   def handle_event("insert_cell_below", params, socket) do
+    assert_policy!(socket, :edit)
     {type, attrs} = cell_type_and_attrs_from_params(params)
 
     with {:ok, section, index} <-
@@ -636,12 +649,14 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("delete_cell", %{"cell_id" => cell_id}, socket) do
+    assert_policy!(socket, :edit)
     Session.delete_cell(socket.assigns.session.pid, cell_id)
 
     {:noreply, socket}
   end
 
   def handle_event("set_notebook_name", %{"value" => name}, socket) do
+    assert_policy!(socket, :edit)
     name = normalize_name(name)
     Session.set_notebook_name(socket.assigns.session.pid, name)
 
@@ -649,6 +664,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("set_section_name", %{"metadata" => section_id, "value" => name}, socket) do
+    assert_policy!(socket, :edit)
     name = normalize_name(name)
     Session.set_section_name(socket.assigns.session.pid, section_id, name)
 
@@ -660,6 +676,7 @@ defmodule LivebookWeb.SessionLive do
         %{"cell_id" => cell_id, "tag" => tag, "delta" => delta, "revision" => revision},
         socket
       ) do
+    assert_policy!(socket, :edit)
     tag = String.to_atom(tag)
     delta = Delta.from_compressed(delta)
     Session.apply_cell_delta(socket.assigns.session.pid, cell_id, tag, delta, revision)
@@ -672,6 +689,7 @@ defmodule LivebookWeb.SessionLive do
         %{"cell_id" => cell_id, "tag" => tag, "revision" => revision},
         socket
       ) do
+    assert_policy!(socket, :read)
     tag = String.to_atom(tag)
     Session.report_cell_revision(socket.assigns.session.pid, cell_id, tag, revision)
 
@@ -679,6 +697,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("move_cell", %{"cell_id" => cell_id, "offset" => offset}, socket) do
+    assert_policy!(socket, :edit)
     offset = ensure_integer(offset)
     Session.move_cell(socket.assigns.session.pid, cell_id, offset)
 
@@ -686,6 +705,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("move_section", %{"section_id" => section_id, "offset" => offset}, socket) do
+    assert_policy!(socket, :edit)
     offset = ensure_integer(offset)
     Session.move_section(socket.assigns.session.pid, section_id, offset)
 
@@ -693,6 +713,8 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("delete_section", %{"section_id" => section_id}, socket) do
+    assert_policy!(socket, :edit)
+
     socket =
       case Notebook.fetch_section(socket.private.data.notebook, section_id) do
         {:ok, %{cells: []} = section} ->
@@ -718,6 +740,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("convert_smart_cell", %{"cell_id" => cell_id}, socket) do
+    assert_policy!(socket, :edit)
     Session.convert_smart_cell(socket.assigns.session.pid, cell_id)
 
     {:noreply, socket}
@@ -728,6 +751,8 @@ defmodule LivebookWeb.SessionLive do
         %{"kind" => kind, "variant_idx" => variant_idx},
         socket
       ) do
+    assert_policy!(socket, :edit)
+
     with %{requirement: %{variants: variants}} <-
            Enum.find(socket.private.data.smart_cell_definitions, &(&1.kind == kind)),
          {:ok, %{dependencies: dependencies}} <- Enum.fetch(variants, variant_idx) do
@@ -744,6 +769,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("queue_cell_evaluation", %{"cell_id" => cell_id}, socket) do
+    assert_policy!(socket, :execute)
     data = socket.private.data
 
     {status, socket} =
@@ -763,24 +789,29 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("queue_section_evaluation", %{"section_id" => section_id}, socket) do
+    assert_policy!(socket, :execute)
     Session.queue_section_evaluation(socket.assigns.session.pid, section_id)
 
     {:noreply, socket}
   end
 
   def handle_event("queue_full_evaluation", %{"forced_cell_ids" => forced_cell_ids}, socket) do
+    assert_policy!(socket, :execute)
     Session.queue_full_evaluation(socket.assigns.session.pid, forced_cell_ids)
 
     {:noreply, socket}
   end
 
   def handle_event("cancel_cell_evaluation", %{"cell_id" => cell_id}, socket) do
+    assert_policy!(socket, :execute)
     Session.cancel_cell_evaluation(socket.assigns.session.pid, cell_id)
 
     {:noreply, socket}
   end
 
   def handle_event("save", %{}, socket) do
+    assert_policy!(socket, :edit)
+
     if socket.private.data.file do
       Session.save(socket.assigns.session.pid)
       {:noreply, socket}
@@ -793,16 +824,19 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("reconnect_runtime", %{}, socket) do
+    assert_policy!(socket, :execute)
     {_, socket} = maybe_reconnect_runtime(socket)
     {:noreply, socket}
   end
 
   def handle_event("connect_runtime", %{}, socket) do
+    assert_policy!(socket, :execute)
     {_, socket} = connect_runtime(socket)
     {:noreply, socket}
   end
 
   def handle_event("setup_default_runtime", %{}, socket) do
+    assert_policy!(socket, :execute)
     {status, socket} = connect_runtime(socket)
 
     if status == :ok do
@@ -813,11 +847,14 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("disconnect_runtime", %{}, socket) do
+    assert_policy!(socket, :execute)
     Session.disconnect_runtime(socket.assigns.session.pid)
     {:noreply, socket}
   end
 
   def handle_event("intellisense_request", %{"cell_id" => cell_id} = params, socket) do
+    assert_policy!(socket, :read)
+
     request =
       case params do
         %{"type" => "completion", "hint" => hint} ->
@@ -864,6 +901,7 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("fork_session", %{}, socket) do
+    assert_policy!(socket, :edit)
     %{pid: pid, images_dir: images_dir} = socket.assigns.session
     # Fetch the data, as we don't keep cells' source in the state
     data = Session.get_data(pid)
@@ -872,11 +910,14 @@ defmodule LivebookWeb.SessionLive do
   end
 
   def handle_event("erase_outputs", %{}, socket) do
+    assert_policy!(socket, :execute)
     Session.erase_outputs(socket.assigns.session.pid)
     {:noreply, socket}
   end
 
   def handle_event("location_report", report, socket) do
+    assert_policy!(socket, :read)
+
     Phoenix.PubSub.broadcast_from(
       Livebook.PubSub,
       self(),
@@ -887,19 +928,6 @@ defmodule LivebookWeb.SessionLive do
     {:noreply, socket}
   end
 
-  def handle_event("format_code", %{"code" => code}, socket) do
-    formatted =
-      try do
-        code
-        |> Code.format_string!()
-        |> IO.iodata_to_binary()
-      rescue
-        _ -> code
-      end
-
-    {:reply, %{code: formatted}, socket}
-  end
-
   @impl true
   def handle_info({:operation, operation}, socket) do
     {:noreply, handle_operation(socket, operation)}
@@ -1657,4 +1685,12 @@ defmodule LivebookWeb.SessionLive do
        }}
     end)
   end
+
+  defp assert_policy!(socket, key) do
+    unless socket.assigns.policy |> Map.fetch!(key) do
+      raise "policy not allowed"
+    end
+
+    :ok
+  end
 end

lib/livebook_web/router.ex

@@ -39,7 +39,8 @@ defmodule LivebookWeb.Router do
     get "/sessions/:id/assets/:hash/*file_parts", SessionController, :show_asset
   end
 
-  live_session :default, on_mount: [LivebookWeb.AuthHook, LivebookWeb.UserHook] do
+  live_session :default,
+    on_mount: [LivebookWeb.AuthHook, LivebookWeb.UserHook, {LivebookWeb.PolicyHook, :private}] do
     scope "/", LivebookWeb do
       pipe_through [:browser, :auth]