This should give you the roles, users and permissions granted on a directory:
SELECT *
FROM all_tab_privs
WHERE table_name = 'your_directory'; --> needs to be upper case
And yes, it IS in the all_TAB_privs view ;-) A better name for that view would be something like "ALL_OBJECT_PRIVS", since it also includes PL/SQL objects and their execute permissions as well.