Dynamic Detection and Prevention of Race Conditions in File Accesses

Race conditions in filesystem accesses occur when sequences of filesystem operations are not carried out in an isolated manner. Incorrect assumptions of filesystem namespace access isolation allow attackers to elevate their privileges without authorization by changing the namespace bindings. To address this security issue, we propose a mechanism for keeping track of all filesystem operations and possible interferences that might arise. If a filesystem operation is found to be interfering with another operation, it is temporarily suspended allowing the first process to access a file object to proceed, thereby reducing the size of the time window when a race condition exists. The above mechanism is shown to be effective at stopping all realistic filesystem race condition attacks known to us with minimal performance overhead.