Signed Unified Kernel Image Booting with Customizable Command Lines
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Solution Overview
Problem
Conventional signature validation processes for booting kernels in computing systems can leave them vulnerable to malicious attacks due to unverified command line arguments, which may limit operational flexibility and security.
Innovation Solution
Implementing a signed unified kernel image that includes multiple command lines, each with different functionalities, allows for customizable booting processes while ensuring security through cryptographic signatures. This solution also includes an allowlist to control modifications to command line arguments, preventing unauthorized changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single command line is used in the kernel image, then the kernel boot process is simple, but operational flexibility is limited
Solution Approach 1:
The kernel image is segmented into multiple command lines (first command line, second command line, etc.), each providing different functionalities. This segmentation allows the system to offer multiple operational modes while maintaining a structured and manageable kernel image format.
Solution Approach 2:
The kernel image is designed to include multiple command lines that can serve different purposes (default operation, troubleshooting, debugging). This multi-functionality approach allows a single kernel image to handle various operational scenarios without requiring separate kernel images for each function.
2Reliability
If command line arguments are left unverified, then the booting process is fast, but security is compromised
Solution Approach 1:
The cryptographic signature verification of command line arguments is performed preliminarily during the kernel boot process before the system becomes operational. This preliminary validation ensures security without adding significant overhead to the overall booting time, as the verification is integrated into the existing boot sequence.
3Reliability
If multiple command lines are included in the signed kernel image, then security is enhanced, but device complexity increases
Solution Approach 1:
Multiple command lines are merged into a single signed kernel image, with each command line cryptographically protected. This merging approach enhances security by ensuring all command lines are verified together, while the structured organization maintains manageable complexity.
4Adaptability or versatility
If a single command line with fixed functionality is used, then the kernel image is simple, but adaptability is reduced
Solution Approach 1:
The kernel boot system is made dynamic by allowing users to select different command lines based on operational needs. The first command line provides default functionality, while subsequent command lines offer alternative functionalities (troubleshooting, debugging), enabling the system to adapt to different scenarios without increasing inherent structural complexity.
Data Source
AI summary
Kernels can be securely booted while having customizable command line functionality. For example, a boot loader can initiate a kernel boot using a unified kernel image (UKI) that is cryptographically signed with a cryptographic signature and includes two or more command lines that are protected by the cryptographic signature. The two or more command lines can implement different functionalities with respect to the kernel boot. The boot loader can extract the two or more command lines from the signed UKI. A command line of the two or more command lines can be selected by a user to complete the kernel boot. Once the command line is selected, the boot loader can execute the command line to complete the kernel boot using the command line.