This more recent post has some details on the restrictions:

The source told CBC News the Canadian government was expected to agree to apply steel and aluminum tariffs on all of its trading partners at a rate comparable to what the U.S. has applied (50 per cent).

However, countries that have a free trade agreement with Canada would be treated differently. In those cases, Canada would have to establish a tariff rate quota, meaning a certain amount of product would be allowed into the country at a lowered tariff rate.