BMC Peripheral Access Control via Write-Once Memory
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Solution Overview
Problem
The indirect connection between a host and peripherals via baseboard management controllers (BMCs) presents an attack vector for malicious access, as a compromised host can access and manipulate peripherals, compromising security.
Innovation Solution
Incorporating an access control chip with a write-once memory that stores an access permission table, which defines access control policies for peripherals, and is securely copied from BMC flash storage during bootup, enabling the chip to manage and enforce access permissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a host is indirectly connected to peripherals via BMC, then the host can access and manipulate peripherals, but this creates an attack vector for malicious exploitation
Solution Approach 1:
An access control chip is introduced as an intermediary component between the host and peripherals. This chip enforces access control policies by validating access requests against permission tables stored in write-once memory, thereby mediating the indirect connection through BMC and preventing malicious exploitation while maintaining legitimate peripheral accessibility
2Adaptability or versatility
If access permission table is stored in BMC flash storage, then it allows flexible updates, but the integrity and security of the permission table may be compromised
Solution Approach 1:
The access permission table is copied from BMC flash storage to write-once memory during system initialization or secure boot sequences. This preliminary action ensures that the critical permission data is transferred to a tamper-resistant storage medium before normal operations begin, preserving integrity while allowing the original flash storage to remain updateable
Solution Approach 2:
A copy of the access permission table is created and stored in write-once memory, which is protected against modification. This copying mechanism allows the permission data to be updated in BMC flash storage for adaptability, while the protected copy in write-once memory maintains reliability and prevents unauthorized changes
3Reliability
If write-once memory is used to store access permission table, then security is enhanced, but the ability to update permissions is limited
Solution Approach 1:
The storage system is segmented into two distinct components: BMC flash storage for storing the updateable access permission table, and write-once memory in the access control chip for storing the protected copy. This segmentation allows each component to fulfill its specific function - one providing updatability and the other providing security - without compromising either capability
Data Source
AI summary
Described is a baseboard management controller (BMC). The BMC comprises a BMC flash storage storing firmware and an access permission table. The access permission table defines an access control policy for access requests to peripherals communicatively coupled to the BMC. The BMC further comprises an access control chip comprising one or more processors and a write-once memory. The write-once memory stores a copy of the access permission table. The access control chip is configured to manage access to the peripherals using the access permission table.