Realm Security Parameter Signature Verification
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Solution Overview
Problem
In privilege-based memory access control schemes, there is a lack of granular control over memory access, where a more privileged process can inadvertently access memory regions intended for less privileged processes, posing security risks, especially in multi-tenant cloud environments where data isolation is crucial.
Innovation Solution
Implementing a realm-based memory access control system where each memory region is owned by a specific realm, allowing the owner realm to exclude other realms, including those of higher privilege, from accessing its data, with a realm management unit enforcing security configuration parameters and parameter signatures to ensure correct initialization and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If privilege-based memory access control is used, then memory access control is provided, but granular control over memory access is lacking and higher privileged processes can inadvertently access memory regions intended for less privileged processes
Solution Approach 1:
The patent divides the memory address space into distinct regions, each owned by a specific process. Ownership information is stored in memory management data structures (such as page tables or region tables) that map memory regions to owning processes. This segmentation enables fine-grained control where each process can independently protect its designated memory regions from unauthorized access by other processes, even those with higher privilege levels.
2Reliability
If ownership-based control is implemented to prevent unauthorized access, then data isolation is improved, but the complexity of memory management structures increases
Solution Approach 1:
The patent combines the ownership-based access control mechanism with existing memory management structures such as page tables or region tables. By integrating ownership information into these existing structures rather than creating entirely separate control mechanisms, the system achieves enhanced security while minimizing additional complexity. The memory management unit can enforce ownership constraints during normal memory access operations without requiring separate control paths.
3Reliability
If parameter signature verification is performed on realm activation, then security configuration correctness is ensured, but activation time increases
Solution Approach 1:
The patent performs parameter signature verification as part of the realm activation process. When a realm is activated, the memory management unit retrieves the ownership information and associated signature from memory, verifies the signature against the retrieved data, and only completes activation if verification succeeds. This preliminary verification ensures that realms are properly configured before they begin operation, preventing security vulnerabilities from malformed or malicious realm configurations.
Data Source
AI summary
Memory access circuitry 26 controls access to memory based on ownership information defining, for a given memory region, an owner realm specified from among two or more realms, each realm corresponding to at least a portion of a software processes miming on processing circuitry 8. The owner realm has a right to exclude other realms from accessing data stored within the given memory region. On activation of a target realm, it is detected whether a parameter signature derived from security configuration parameters established for the target realm matches an expected signature; and in response to detecting a mismatch between the parameter signature and the expected signature, an activation restriction is applied to the target realm to prevent the activation of target realm or prevent correct functioning of the target realm following activation.