CADPAT is
not illegal to own.
Possessing some items
may be illegal though.
Much Canadian Forces property is sold as "surplus" through various channels when it exceeds it's useful life for whatever reason (like the webbing for sale above, which is no longer issued)
Some items have to be "demillitaries" for various reasons, of controlled technologies.
The Canadian government holds the copy right on cadpat.
They have lisenced several companies to produce and sell items that do not directly resemble military issue items (
www.cpgear.com is one)
Actual military items are produced with cadpat fabric that has been treated with a chemical to reduce the IR signature.
The treatment is controlled under ITAR, and it's a policy of the canadian forces that any actual military issue items are destroyed first, rather than sold directly as surplus.
Any actual military items that you find for sale are likely "stolen" (Either actually "stolen", or the owner is selling items that were issued to them, but not their property to sell). If you buy them, you're receiving stolen goods.
A small number do fall through the cracks and end up being sold surplus, I''m a lawyer , I have no idea if it's actually illegal to posses them, as they were legitimately sold, they just weren't supposed to be sold.
There are a variety of unlisenced knock-offs found for sale as well, without the IR treatment. The producers violate the copyright, but I wouldn't guess you'd suffer any repercussions for buying them.