As long as you are working under the Canadian work permit, you are bound to Canadian law, also Canadian tax law about working foreigners may be different from the native Canadians(fi. You may not need to pay taxes even if you earn more then 30k CAD, or you may need to pay even if you earn less and that kind of stuff).

I do not know if you can work without a permit as freelancer. also don't know which law you are bound to in that case.