1. A data processing system configured for file system access, the data processing system comprising: a processor; a file system; an operating system; a set of access rules, each of the access rules having an associated rule key; and, a file system firewall disposed between the file system and the operating system, the file system firewall comprising program code enabled to receive from a requesting application a file system access request, to determine an application identifier of the requesting application within the file system access request, to form a rule key from the determined application identifier of the requesting application, to permit or deny the file system access request according to an access rule in the set of access rules associated with the rule key.