Security Rule Conflict Resolution in Trusted Computing
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Solution Overview
Problem
Existing trusted computing systems face issues with filename aliasing and rule conflicts, which can lead to inadequate security policies and potential system vulnerabilities, such as file defacement, due to the complexity of managing access permissions across multiple compartments and links.
Innovation Solution
A system and method that determine the complete set of files affected by conflicting security rules, assess if one rule's scope is a complete subset of another, and apply the most restrictive or recently added rule to resolve conflicts, while providing warnings or removing offending links to maintain secure access controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If filename-based security rules are used to control access, then ease of operation is improved, but reliability deteriorates due to filename aliasing and rule conflicts
Solution Approach 1:
The patent segments the security rule evaluation process into distinct phases: first evaluating inode-based rules (which are reliable and unambiguous), then evaluating filename-based rules (which provide ease of operation but suffer from aliasing conflicts). This segmentation allows the system to maintain reliability through inode rules while preserving operational convenience through filename rules, resolving the contradiction by applying each type of rule where it is most effective.
2Ease of operation
If simple filename-based access control is implemented, then ease of operation is improved, but security deteriorates due to inadequate policy enforcement
Solution Approach 1:
The patent applies preliminary action by first evaluating inode-based security rules before evaluating filename-based rules. This preliminary evaluation ensures that reliable, unambiguous security constraints are established first, preventing security vulnerabilities before filename-based rules are applied. The system proactively identifies and applies the most restrictive rules in advance, eliminating security gaps that would otherwise exist in simple filename-based systems.
Solution Approach 2:
The patent provides beforehand cushioning by implementing a two-layer security rule evaluation system where inode-based rules serve as a protective foundation. This cushioning mechanism ensures that even if filename-based rules are ambiguous or conflicting, the underlying inode-based rules provide a safety net that maintains security. The system prepares multiple layers of protection in advance, preventing security breaches before they can occur.
3Reliability
If multiple security rules are applied to files, then security is improved, but device complexity increases due to rule conflict resolution
Solution Approach 1:
The patent applies local quality by treating inode-based rules and filename-based rules with different evaluation criteria appropriate to their respective characteristics. Inode-based rules are evaluated first with strict matching criteria to ensure reliability, while filename-based rules are evaluated second with flexibility to handle aliasing. This localized approach to rule evaluation optimizes the complexity-security trade-off by applying appropriate complexity only where needed for each rule type.
Solution Approach 2:
The patent changes the evaluation parameters based on the rule type being processed. For inode-based rules, the system uses precise inode identifier matching with high selectivity. For filename-based rules, the system uses pattern matching with lower selectivity to accommodate aliasing. This parameter change strategy allows the system to manage multiple security rules effectively while controlling complexity by adapting evaluation strictness to the specific rule characteristics.
4Ease of operation
If filename-specific rules are used, then ease of operation is improved, but manufacturing precision deteriorates due to ambiguity in rule application
Solution Approach 1:
The patent segments rule application precision by applying inode-based rules first with high precision (exact inode matching) and then applying filename-based rules with lower precision (pattern matching that accepts aliases). This segmentation ensures that the most precise rules are applied first to establish definitive security constraints, while less precise filename-based rules provide operational convenience without compromising overall precision.
Solution Approach 2:
The patent applies preliminary action by first establishing precise inode-based security constraints before applying less precise filename-based rules. This preliminary high-precision evaluation ensures that unambiguous security requirements are met first, creating a foundation of manufacturing precision that the subsequent filename-based rules build upon rather than undermine.
Data Source
AI summary
A system and method for resolving a rule conflict within a security policy applied to a trusted computing platform, wherein the fileset to which each of the conflicting rules v and s refers (or “scope”) is determined (step 10). It is then determined (at step 12) if the scope of one of the rules s is a complete subset of the scope of rule r. If so, rule s is applied to the accessed file f (at step 14). If not, the conflict is resolved in another way, for example, by determining the most restrictive of rules r and s (at step 16) and applying the result accordingly (step 18).