Authentication Plug: Update bcrypt password on login.

lib/pleroma/plugs/authentication_plug.ex

@@ -30,6 +30,17 @@ defmodule Pleroma.Plugs.AuthenticationPlug do
     false
   end
 
+  def maybe_update_password(%User{password_hash: "$2" <> _} = user, password) do
+    user
+    |> User.password_update_changeset(%{
+      "password" => password,
+      "password_confirmation" => password
+    })
+    |> Pleroma.Repo.update()
+  end
+
+  def maybe_update_password(user, _), do: {:ok, user}
+
   def call(%{assigns: %{user: %User{}}} = conn, _), do: conn
 
   def call(
@@ -42,6 +53,8 @@ defmodule Pleroma.Plugs.AuthenticationPlug do
         _
       ) do
     if checkpw(password, password_hash) do
+      {:ok, auth_user} = maybe_update_password(auth_user, password)
+
       conn
       |> assign(:user, auth_user)
       |> OAuthScopesPlug.skip_plug()

test/plugs/authentication_plug_test.exs

@@ -11,6 +11,7 @@ defmodule Pleroma.Plugs.AuthenticationPlugTest do
   alias Pleroma.User
 
   import ExUnit.CaptureLog
+  import Pleroma.Factory
 
   setup %{conn: conn} do
     user = %User{
@@ -50,16 +51,21 @@ defmodule Pleroma.Plugs.AuthenticationPlugTest do
     assert PlugHelper.plug_skipped?(conn, OAuthScopesPlug)
   end
 
-  test "with a wrong password in the credentials, it does nothing", %{conn: conn} do
+  test "with a bcrypt hash, it updates to a pkbdf2 hash", %{conn: conn} do
+    user = insert(:user, password_hash: Bcrypt.hash_pwd_salt("123"))
+    assert "$2" <> _ = user.password_hash
+
     conn =
       conn
-      |> assign(:auth_credentials, %{password: "wrong"})
-
-    ret_conn =
-      conn
+      |> assign(:auth_user, user)
+      |> assign(:auth_credentials, %{password: "123"})
       |> AuthenticationPlug.call(%{})
 
-    assert conn == ret_conn
+    assert conn.assigns.user.id == conn.assigns.auth_user.id
+    assert PlugHelper.plug_skipped?(conn, OAuthScopesPlug)
+
+    user = User.get_by_id(user.id)
+    assert "$pbkdf2" <> _ = user.password_hash
   end
 
   describe "checkpw/2" do