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Analysis of Monolithic and Microkernel Architectures - Towards Secure Hypervisor Design
- 1. Analysis of Monolithicand Microkernel Architectures Towards Secure Hypervisor Design Islam, Pahlwan Rabiul 20-61980-1 By Dr. Jordan Shropshire
- 2. Contents Hypervisor Architecture Hypervisor Security Hypervisor Platforms ESX Xen Hyper-V Architectural Features Management API Monitoring Interface Hypercalls Interrupts Networking I/O
- 3. Introduction Monolithic Hypervisor ThinLayer of Software Hardware Drivers Application Programming Interface Virtualization Stack Microkernel Hypervisor Small hypervisor Kernel Management Partition Drivers Virtualization Managers Administrative Interfaces Vulnerabilities & Trade-offs Comparison
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- 5. Hypervisors Intermediary betweenvirtual machines & underlying hardware Hypercalls Paravirtualization Deliberate System Calls Interrupts Signal to Processor Scheduler One or more vCPU for each virtual machine Multiprocessing Abstraction
- 6. Security Rings Hierarchicallevel of privilege Ring 0 → OS Kernel | CPU | Memory Ring 1 & Ring 2 → Device Drivers Ring 3 → User Mode Shared memory privilege System flags Gate feature Context switch
- 7. Trusted Code Base(TCB) Trusted Code Base components Hardware Drivers Operating System Abstraction Software Resource Brokering Software “all of the elements of the system responsible for supporting the security policy and supporting the isolation of objects (code and data) on which the protection is based”
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- 9. Hypervisor Task Startingand Maintaining virtual machines Abstracting System Resources Sharing Hardware and Assets
- 10. Microkernel Architecture Management Partition ManagementOS Kernel Management Interface Virtualization Stack Virtual Machine Guest OS Kernel Applications Hypervisor
- 11. Monolithic Architecture Application Guest OSKernel Management Interface Virtualization Stack Hypervisor Kernel
- 12. Threat Model Logical Accessbut No Physical Access
- 13. Analysis Analysis of SixFeatures of Hypervisors
- 14. Management Interface RemoteAgents Connect with a Hypervisor Perform Managerial Duties Management Platforms Hyper-V Support for classes and objects Xen Controls for limiting access & permissions ESXi Allows for basic file system interaction while restricting other usage
- 15. Monitoring Monitoring SystemFootprint Xen → 14 Steps Hyper-V → 13 Steps ESXi → 10 steps
- 16. Hypercalls Hypercall Support Xen → 100 Hypercalls Hyper-V → 113 Hypercalls ESXi → 82 Hypercalls
- 17. Interrupts User SpaceEmulators Susceptible to tampering Privileged Zone Emulator Harder to reach
- 18. Networking Network Path Xen → 25 Steps Hyper-V → 31 Steps ESXi → 20 Steps
- 19. Storage Storage Path Xen → 23 Steps Hyper-V → 25 Steps ESXi → 16 Steps
- 20. Conclusion “Regardless of thesize of the footprint or the type of architecture, well written and tested kernel code will provide better security”