Temporary Privilege Escalation via EFLAGS Control Registers
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Solution Overview
Problem
Current computer processor designs do not allow controlled access from higher privilege levels to lesser privileged data, leading to restrictions in data access between different privilege rings, such as from kernel mode to user mode, which limits system flexibility and functionality.
Innovation Solution
Implementing a temporary privilege level indication mechanism using configurable flags in processor registers, like the EFLAGS register, to allow controlled access from higher privileged levels to lesser privileged levels, enabling access to user mode pages based on set permissions, and using push/pop mechanisms or dedicated instructions to manage these access flags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If controlled access from higher privilege levels to lesser privileged levels is implemented, then system flexibility and functionality are improved, but system complexity and security management overhead increase
Solution Approach 1:
The patent implements preliminary action by pre-configuring access permissions in control registers (e.g., CR3, CR4) before execution. The system预先 sets up the privilege level access indication bits and permission masks, so that when a higher privileged level needs to access lesser privileged data, the access control is already established through prior register configuration rather than requiring complex runtime security management
Solution Approach 2:
The patent introduces intermediary control registers (such as CR3 and CR4 with specific permission bits) that act as mediators between higher and lower privilege levels. These registers store permission indicators that the processor checks during access operations, providing a structured intermediary layer that manages the complexity of privilege level transitions without requiring direct complex control logic in the access path
2Adaptability or versatility
If temporary privilege escalation is allowed, then data access capability is improved, but system security and stability deteriorate
Solution Approach 1:
The patent implements periodic action by using interrupt-driven mechanisms to temporarily enable privilege escalation only when needed. The system periodically checks and sets the privilege level access indication (through instructions like STAC/CLAC or by manipulating EFLAGS register bits) at specific interrupt handlers or system call entry points, rather than maintaining permanent elevated privileges. This ensures that higher privileged access is activated temporarily only during necessary operations and automatically reverted afterward
Solution Approach 2:
The patent changes parameters by using specific permission indicator bits in control registers (such as the permission bits in CR3 and CR4, or EFLAGS register bits) to dynamically control access. By modifying these parameter bits in response to specific conditions (interrupts, system calls), the system enables or disables privilege escalation on demand, providing fine-grained control over when data access capability is enhanced while maintaining overall system security through parameter-based conditional access
Data Source
AI summary
Embodiments of systems, apparatuses, and methods for temporarily allowing access to a lower privilege level from a higher privilege level.