Secure World Storage Isolation for Firmware Protection
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Solution Overview
Problem
Platform firmware stored in Universal Flash Storage (UFS) devices does not meet NIST-800-193 security guidelines, leading to security monitoring and control issues that slow access and limit storage options for critical data in legacy flash storage devices like SPI NOR flash memories.
Innovation Solution
A computer system with a RISC processor core operating in both normal and secure worlds provides hardware-level isolation, allowing critical data to be stored in a protected region of an external storage device, accessible only through authorized programs, using direct memory access (DMA) operations to transfer data between the protected region and normal memory space in external RAM, eliminating the need for a storage driver in the secure world.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If security monitoring and control are implemented to meet NIST-800-193 guidelines, then security compliance is improved, but data access speed deteriorates
Solution Approach 1:
A secure monitor is introduced as an intermediary component that validates access requests to critical data in the protected region. The secure monitor checks authorization credentials and manages access control policies, enabling security compliance while maintaining fast access paths for authorized operations. The secure monitor operates in the secure world and mediates between normal world applications and protected data resources.
2Adaptability or versatility
If legacy flash storage devices like SPI NOR flash are used for platform firmware storage, then storage compatibility is improved, but security compliance with NIST-800-193 deteriorates
Solution Approach 1:
The storage device is segmented into a regular data region and a protected data region. The protected region stores critical platform firmware and is subject to access control restrictions, while the regular region provides unrestricted access for general storage operations. This segmentation enables legacy storage devices to comply with security guidelines by isolating critical data without requiring hardware replacement.
3Reliability
If a protected data region with access control is created, then security protection is improved, but system complexity deteriorates
Solution Approach 1:
The secure monitor functionality is merged with the existing storage driver infrastructure. The storage driver in the normal world communicates with the secure monitor in the secure world, which handles access control logic. This merging approach reuses existing system components and communication mechanisms, reducing the overall system complexity compared to implementing a completely separate security subsystem.
Data Source
AI summary
A computer system includes a processor that operates in a normal world and a secure world and that provides hardware-level isolation between the normal world and the secure world. A storage device of the computer system has a protected data region that stores critical data. A random-access memory of the computer system has a normal memory space that is accessible in the normal world and a secure memory space that is accessible only in the secure world. The secure memory space stores commands that transfer the critical data between the protected data region and the normal memory space by direct memory access.