Air carrier pilot reported smoke during cruise in the forward cabin. Flight crew requested special handling to a diversionary airport and a safe landing; followed by an expedited passenger deplaning at the gate.

Narrative

Two issues here....first; [at] XA:03 I finally got the aircraft security slip; which was very close from the Number 4 from going illegal by FAR 121.467. At that point we would need a fifth FA (Flight Attendant)....[Scheduling] refused to update to a more realistic [departure] time which would guarantee the No.4 going illegal; or at best causing a [issue] in ZZZZ; as she was guaranteed to go illegal in ZZZZ by going over 14 hours scheduled duty day. Finally got another No.4.......Then left for ZZZZ...after 35 minutes in flight had reported smoke in cabin and dense smoke in FC lav.......did emergency descent into ZZZ with overweight landing... CFR (Crash Fire Rescue) met on runway and cleared us as the smoke was mostly dissipated...during taxi to gate; smoke started getting thicker. I then expedited my taxi to deplaning at the gate...no aircraft damage....No passenger injuries... 2 Flight Attendants required medical attention due to smoke inhalation.Educate [crew scheduling] on FAR 121.467 and hold them accountable; as I did...not just play with unrealistic [departure] times to make crews legal.........thank the ZZZ personnel for me as they were outstanding....ZZZ Center as well.