File Page Table Linking for Secure User Mode Access
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Solution Overview
Problem
Conventional file systems require frequent switching between user mode and kernel mode for file access, leading to resource and time consumption, and pose security risks due to unauthorized access to file data in non-volatile memory (NVM).
Innovation Solution
A method and system that allocate user space and kernel space during process initialization, where the user space includes file system space and PGD space, allowing secure file data access by linking a file page table to a PGD entry only when needed, and disconnecting the link when access ends, to prevent unauthorized access and reduce resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a process in user mode accesses file data by executing file system interface functions, then file access can be performed, but the user mode switches to kernel mode twice (entry and exit), consuming resources and time
Solution Approach 1:
The patent segments the file access process into distinct phases: linking the file page table to PGD entry only when file data needs to be accessed, and disconnecting it when access ends. This segmentation allows the system to maintain security (file access only when linked) while reducing unnecessary mode switches (no switch needed during active access).
Solution Approach 2:
The patent implements dynamic linking and disconnecting of the file page table to the PGD entry based on actual file access needs. The link is established when a process needs to access file data and disconnected when access ends, creating a dynamic access control mechanism that reduces overhead during active operations while maintaining security when idle.
2Productivity
If the file page table is continuously linked to the PGD entry, then file data access is fast and convenient, but unauthorized access to file data in NVM may occur
Solution Approach 1:
The patent applies preliminary anti-action by disconnecting the file page table from the PGD entry when file access is not needed, proactively preventing unauthorized access before it can occur. The system anticipates security risks and eliminates the access path by disconnecting the link, rather than relying on detection or correction mechanisms.
Solution Approach 2:
The patent implements dynamic control of the file page table linkage, establishing the connection only when file access is required and disconnecting it when access ends. This dynamic approach allows efficient access during active operations while eliminating unauthorized access risks during idle periods.
3Loss of energy
If mode switching is reduced for file access, then resource and time consumption decreases, but security control over file data access may be weakened
Solution Approach 1:
The patent segments access control into linkage state management (linking/disconnecting file page table to PGD entry) and actual data access. This segmentation allows the system to maintain strong security control through explicit linkage states while reducing resource consumption by avoiding unnecessary mode switches during active file operations.
Solution Approach 2:
The patent implements dynamic linkage management where the file page table is connected to the PGD entry only during active file access and disconnected otherwise. This dynamic control maintains security through explicit linkage states while minimizing mode switching overhead, as the linkage state itself provides the security control mechanism.
Data Source
AI summary
A file data access method and a computer system, where the method includes accessing a page global directory (PGD) of the process using PGD space when accessing first file data by a process, determining, based on access to the PGD and according to a first virtual address of the first file data in file system space, a first PGD entry in the PGD, linking a file page table of the process to the first PGD entry, where the file page table points to a physical address of the file data such that a processor retrieves a first physical address of the first file data in a memory according to the first virtual address using the PGD and the file page table, and accessing the first file data according to the first physical address.