Mask on login devise

How I put a mask on login with devise?

This is my views/devise/sessions/new.html.erb
<%= simple_form_for(resource, as: resource_name, url:
session_path(resource_name)) do |f| %>

<%= f.input :cpf, required: false, autofocus: true,
input_html: {
class: ‘form-control mask-cpf’ }, placeholder: ‘LOGIN’, label: false
<%= f.input :password, required: false, input_html: { class:
‘form-control’ }, placeholder: ‘SENHA’, label: false %>

<%= f.button :submit, “Log in”, :class => “btn btn-default
btn-block” %>

<% end %>

I need generate the sessions_controller of the devise? Or I just use in
User.rb? The mask appear, but when save, save with . and - , because
this I
cant sign_in :frowning:
My class User, this:

class User < ActiveRecord::Base
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable

before_validation do
self.cpf.gsub!(/(.|-)/, “”)

validates :cpf, uniqueness: true