If someone has been convicted of an indictable offence (and served more then 2 years in prison) or of certain offences under the elections canada act then they can't serve as MP's as I understand it.

But the only information I found is still about 4 years old so they may have changed the law as it stands.

See: http://www.lop.parl.gc.ca/Content/LOP/ResearchPublications/2012-38-e.htm#a3