Data Protection and Security

VI

Operating System Security and Secure Programming

VI.II

Operating System Security

Controlled Invocation:

Suppose a user wants to execute an operation requiring supervisor mode e.g. Write to a memory location. It is desirable that the system only performs a predefined set of operations in supervisor mode and then returns to user mode before handing control back to the user. Control is taken away from the user by executing the interrupt handler. Interrupt handler should be implemented properly to avoid security flaws.