Secure Enclave Page Relocation Without Data Zeroing
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Solution Overview
Problem
Current secure enclave technologies, such as Intel Software Guard Extensions (SGX), do not allow for dynamic page relocation without zeroing or destroying the contents of the page, limiting their ability to support dynamic library loaders and other applications that require changing the linear address of memory pages during their lifetime.
Innovation Solution
The introduction of user-level and privileged-level instructions and logic within processors to modify enclave page metadata, enabling the change of linear addresses without zeroing the page contents, and updating secure protection mechanisms to manage access and integrity during such relocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current secure enclave technologies (Intel SGX) are used to protect memory pages, then security and data integrity are maintained, but dynamic page relocation is not allowed without zeroing or destroying page contents
Solution Approach 1:
The patent implements dynamic page relocation within secure enclaves by introducing runtime address translation mechanisms. The system allows enclave pages to be moved between different physical memory locations while maintaining security, using a combination of hardware-supported address translation and software-managed page tables that update mappings without requiring page zeroing or destruction.
Solution Approach 2:
The patent introduces an intermediary address translation layer between the enclave code and physical memory. This includes enclave page cache maps (EPCM) and translation lookaside buffers (TLB) that mediate access to relocated pages, allowing the system to maintain security protections while enabling flexible page movement through intermediate address mapping structures.
2Reliability
If page contents are preserved during relocation, then data integrity is maintained, but support for dynamic library loaders and address-changing applications is limited
Solution Approach 1:
The system enables dynamic library loaders and address-changing applications to operate within secure enclaves by implementing runtime address translation. Page tables and EPCM structures are dynamically updated to reflect new addresses of relocated library code and data, allowing applications to modify their address spaces without compromising security or data integrity.
Solution Approach 2:
The patent changes the address space parameters of enclave pages through controlled relocation. By modifying page table entries and EPCM mappings to point to new physical locations while preserving page contents, the system enables applications to change their address parameters dynamically, supporting library loaders and other address-modifying operations.
3Adaptability or versatility
If secure protection mechanisms are updated to allow address changes, then adaptability improves, but security complexity increases
Solution Approach 1:
The patent segments the address translation and protection mechanisms into distinct hierarchical layers: EPCM for enclave-specific page management, nested page tables for virtual-to-physical translation, and TLB for caching. This segmentation allows each layer to handle specific aspects of address translation independently, managing complexity through modular organization while enabling address changes.
Solution Approach 2:
The system introduces intermediary data structures (EPCM, nested page tables) that mediate between enclave code and physical memory. These intermediaries absorb the complexity of secure protection mechanism updates by providing a structured layer that automatically manages address translation and security attributes during page relocation, reducing the burden on the core security enforcement logic.
Data Source
AI summary
A processor of an aspect includes a decode unit to decode a user-level instruction. The user-level instruction is to indicate a page of a secure enclave and is to indicate a linear address. An execution logic is coupled with the decode unit. The execution logic is operable, in response to the user-level instruction, to change an initial linear address of the page of the secure enclave. The initial linear address is to be stored in an enclave page storage metadata unit. The initial linear address is to be changed by the execution logic to the linear address that is to be indicated by the user-level instruction. The change to the linear address is performed without contents of the page of the secure enclave being lost.