EAP-TLS & deny access?

Hi, how can i deny access to a user (a certificate)? Is a CRL (with the CA_path and c_rehash stuff) the only possibility to deny access or is it possible to have a *whitelist* (like the CA_path and c_rehash stuff but as a whitelist) with certs that are allowed? I'm using Freeradius 1.1.7 with EAP-TLS which works fine so far. I'm not using any SQL or LDAP backend only the *users* file. -- regards uHel