Only allow access to a table via a function, not directly via queries

I have a table t and some functions which access t. For example: create function list_t() returns setof t as $$ select * from t; $$ language sql stable; Is it possible to define role permissions to only allow the execution of list_t(), while not allowing plain SELECT, UPDATE, DELETE and INSERT queries on t? I tried the following: grant execute on all functions in schema public to my_user; revoke all on t from my_user; While this indeed disallows SELECT * FROM t, it also disallows SELECT list_t().