Secure Page Flipping for Virtual Machine Memory Isolation
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Solution Overview
Problem
Virtual machines (VMs) used as network security appliances face challenges in maintaining exclusive access to network packet data due to potential modifications by malicious code in guest VMs, leading to security breaches, and existing solutions like copying packet contents or VMM interactions are resource-intensive.
Innovation Solution
The embedded VM is allowed to directly manipulate page table mappings without running the VMM or obtaining VMXRoot privilege, enabling secure page flipping for exclusive control over memory pages, thereby restricting access from the guest VM until the embedded VM completes operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the embedded VM copies packet contents from guest VM memory to embedded VM memory, then exclusive access to packet data is achieved, but resource consumption increases
Solution Approach 1:
The patent uses a virtual memory page flipping mechanism that creates a copy of the packet data in the embedded VM's memory space. The VMM copies the guest VM's packet data into a private page in the embedded VM's virtual address space, allowing exclusive access without requiring physical memory copies or VMM intervention for each access operation.
Solution Approach 2:
The VMM acts as an intermediary that manages the page flipping operation. The VMM intercepts the embedded VM's page flip request, allocates a private page in the embedded VM's virtual address space, copies the packet data into that page, and updates the embedded VM's page table entries. This intermediary mechanism enables efficient exclusive access while minimizing resource consumption.
2Reliability
If the embedded VM requests VMM to map a page into its address space for exclusive access, then security is improved, but system overhead increases
Solution Approach 1:
The VMM performs preliminary actions by pre-configuring the page flipping mechanism and maintaining the embedded VM's page table entries in a ready state. When the embedded VM needs exclusive access, the VMM can quickly flip the page without requiring complex runtime interventions or privileged operations, thereby reducing system overhead while maintaining security.
Solution Approach 2:
The patent replaces the traditional mechanical VMM page mapping mechanism with a more efficient virtual memory page flipping approach. Instead of requiring the VMM to manually map pages into the embedded VM's address space, the system uses automated page table manipulation and virtual memory management to achieve the same security goal with reduced overhead.
3Object-affected harmful factors
If the embedded VM restricts access to packet data from the guest VM, then malicious code modifications are prevented, but access control complexity increases
Solution Approach 1:
The patent segments the packet data access into distinct memory regions with different access permissions. The VMM creates a private page in the embedded VM's virtual address space that is separate from the guest VM's memory space. The page table entries are configured to allow read access from the embedded VM while denying write access from the guest VM, thereby preventing malicious modifications through memory segmentation rather than complex access control mechanisms.
Data Source
AI summary
Embodiments of copy equivalent protection using secure page flipping for software components within an execution environment are generally described herein. An embodiment includes the ability for a Virtual Machine Monitor (VMM), Operating System Monitor, or other underlying platform capability to restrict memory regions for access only by specifically authenticated, authorized and verified software components, even when part of an otherwise compromised operating system environment. In an embodiment, an embedded VM is allowed to directly manipulate page table mappings so that, even without running the VMM or obtaining VMXRoot privilege, the embedded VM can directly flip pages of memory into its direct/exclusive control and back. Other embodiments may be described and claimed.