In today's IaaS clouds users only get a logical view of the underlying network and have limited control. Delegating more control to end users would be beneficial but would also raise security concerns for the provider. Emerging Software Defined Networking (SDN) technologies have the capabilities to facilitate delegation of network controls and provide some level of network abstractions to end users. However, any delegation solution should try to balance the level of controls delegated to end users with the security constraints of the provider. In this paper, we propose a SDN-based framework to facilitate delegation of some network controls to end users, providing the means to monitor and configure their own slices of the underlying networks. Using two instantiations of this framework, we illustrate the tradeoffs between security and the level of network abstractions provided to end users.