Layering System Protects Shared Files via Write Layer Redirection
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Solution Overview
Problem
Information handling systems face challenges in protecting shared layers from modifications by multiple users while allowing individual users to make private modifications, requiring a solution to preserve the original contents and manage user-specific changes efficiently.
Innovation Solution
The implementation of a layering system that mounts a protected read-only layer shared among users and a user-specific write layer, where file operations are redirected to a dummy file or a write-layer copy, ensuring the original file remains unmodified, and user-specific changes are stored on the write layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shared layer is made read-only to protect original files, then the original files are protected from modifications, but users cannot make any changes to the shared resources
Solution Approach 1:
The system divides the file system into multiple independent layers: a protected read-only shared layer containing original files, and user-specific write layers allowing modifications. This segmentation enables simultaneous protection of original files and user ability to modify, as each layer operates independently with defined access permissions.
Solution Approach 2:
The patent introduces a layering driver as an intermediary component that manages file access requests. When a user requests to modify a file, the driver intercepts the request, creates an appropriate handle pointing to a write layer copy rather than the original, and allows modification without affecting the protected shared layer. This intermediary mechanism resolves the contradiction by mediating between protection requirements and modification needs.
2Adaptability or versatility
If user-specific write layers are created for each user, then users can make private modifications, but the system complexity increases
Solution Approach 1:
The layering driver implements universal functionality that handles multiple user requests and file operations through a single unified mechanism. Rather than requiring separate complex systems for each user, the driver provides multi-functional support for creating handles, managing write layers, and coordinating access across all users, thereby reducing overall system complexity while maintaining user-specific capabilities.
Solution Approach 2:
The system employs a nested layer structure where user-specific write layers are contained within or alongside the protected shared layer. Each user's modifications are nested in their own write layer, which references the underlying shared layer. This nesting approach organizes complexity hierarchically, making the system more manageable while enabling user-specific modifications without affecting other users or the original files.
3Reliability
If file operations are redirected through dummy files or write-layer copies, then the original file remains protected, but the file operation handling becomes more complex
Solution Approach 1:
Instead of directly modifying original files, the system creates copies in user-specific write layers. When a user needs to modify a file, a copy is created in their write layer, and all subsequent operations are performed on this copy. The original file remains untouched and protected. This copying mechanism simplifies protection logic while enabling safe modifications.
Solution Approach 2:
The layering driver acts as an intermediary that manages the redirection of file operations. It intercepts file access requests, determines whether to serve from the shared layer or a user's write layer, and returns appropriate handles. This intermediary approach centralizes the complexity of redirection logic within the driver, keeping the overall system manageable while ensuring original files remain protected through controlled access.
Data Source
AI summary
A method and system for handling a file operation directed to an original file of a protected layer. A protected layer and a user- or device-specific write layer associated with the protected layer are both mounted. File open operations directed to an original file on the protected layer are instead redirected to one of a dummy file associated with the original file or a write-layer copy of the original file located on the write layer. If neither a dummy file nor a write-layer copy of the original file are on the write layer, a dummy file having the same file name and file attributes as the original file is created in the write layer. Subsequent file operations, such as reading, writing, and closing, are directed to the one of the dummy file or the write-layer copy.