Do you agree that Rahim Khan knew along? Why? How would he know?

In Chapter Fourteen, we finally revisit the phrase that Amir mentions in Chapter One: "there is a way to be good again." Now we understand its magnitude; for the first time, Amir discovers that someone, Rahim Khan, knows his secret and has kept it for all these years. What he does not realize is that Rahim Khan does not want to be saved; he wants to save Amir. It is possible that somebody involved in the incident told him. It is also possible Hassan himself told him.