Permissions on nested link

[Cassio Almeida]

I have the Client and Exam models:

class Client < ActiveRecord::Base
  has_many :exams, dependent: :destroy
end


class Exam < ActiveRecord::Base
  belongs_to :client
end

in clients controller:

class ClientsController < ApplicationController
  active_scaffold :client do |config|
    config.nested.add_link(:exams)
  end
end

How do I restrict access to exam link only for those who have permissions to exam via cancan ?