[fnordprefect]

Not facetious.

Allow me to introduce the Commonwealth Places (Application of Laws) Act 1970 to you. [https://www.legislation.gov.au/Details/C2016C00956]

Section 4 has the effect that (leaving aside taxation laws), "[t]he provisions of the laws of a State as in force at a time (whether before or after the commencement of this Act) apply, or shall be deemed to have applied, in accordance with their tenor, at that time in and in relation to each place in that State that is or was a Commonwealth place at that time" (s 4(1)) - unless the State law already had that application, in which case the State law applied untouched (s 4(3)).

There is also express provision in s 5 concerning the operation of some Commonwealth crimes provisions.

But as a general matter, if smoking is illegal just outside the Commonwealth place, it will be illegal inside it.

eta: oops, I left this open for a while before posting, and just saw others have answered.