Unfortunately "our constitution" is not a single document. In the same way that British law is decided by cases (not statute), "our constitution" is a series of legal documents and interpretations and is not so plainly defined as the USA.

The reality is that legal authority and rights in Canada are derived from the divine right to rule of the sovereign, which is only another way of saying anything goes unless power is leveraged by the people and the courts onto the government.

All that said, no where in our various constitutional documents does Canada have sovereignty or responsibility over non-Canadian citizens. That is unless you (or courts) consider foreign treaties to be constitutionally binding, in which case, our constitution would also be made up of ratifications of agreements with foreign bodies.