feat(rules): support recursive wrapper command evaluation

[fohte]

Why

• Wrapper commands like sudo rm -rf / or bash -c "curl -X POST ..." need their inner commands evaluated against rules
  • Duplicating every rule for each wrapper combination causes combinatorial explosion

What

• Extract the <cmd> placeholder argument from wrapper patterns defined in definitions.wrappers (e.g., sudo <cmd>, bash -c <cmd>) and recursively evaluate the inner command against rules
• Enforce a recursion depth limit (default 10), returning RuleError::RecursionDepthExceeded on overflow
• Aggregate direct rule results with wrapper evaluation results using Explicit Deny Wins

---

[gemini-code-assist]

Summary of Changes

Hello @fohte, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the rule engine's capability by introducing recursive evaluation for commands wrapped by common utilities like sudo or bash -c. This change eliminates the need for users to define redundant rules for every possible wrapper combination, streamlining rule management and improving the accuracy of security policy enforcement by ensuring that the actual command being executed is always evaluated against the defined rules, even when nested.

Highlights

• Recursive Wrapper Command Evaluation: The rule engine now supports recursively evaluating inner commands within wrapper patterns defined in definitions.wrappers, such as sudo <cmd> or bash -c <cmd>.
• Recursion Depth Limit: A maximum recursion depth of 10 has been enforced for wrapper command evaluation to prevent infinite loops, returning a RuleError::RecursionDepthExceeded on overflow.
• Explicit Deny Wins Aggregation: Evaluation results from direct rule matches and recursive wrapper evaluations are aggregated using an 'Explicit Deny Wins' strategy, ensuring the most restrictive action is applied.

Changelog

• src/rules/pattern_matcher.rs
  • Introduced extract_placeholder function to match wrapper patterns and extract the inner command string.
  • Implemented extract_placeholder_inner for recursive token matching and placeholder capture, including a step limit.
• src/rules/rule_engine.rs
  • Updated imports to include extract_placeholder for new wrapper logic.
  • Defined MAX_WRAPPER_DEPTH to prevent infinite recursion in wrapper evaluation.
  • Refactored evaluate_command into evaluate_command_inner to manage recursion depth.
  • Integrated wrapper command evaluation into the main rule engine flow.
  • Added try_unwrap_wrapper function to detect and recursively evaluate commands within defined wrapper patterns.
  • Implemented merge_results and action_priority to apply 'Explicit Deny Wins' when combining direct and wrapper evaluation results.
  • Ensured RuleError::RecursionDepthExceeded is returned if the wrapper recursion limit is hit.
  • Expanded unit tests to cover recursive wrapper command evaluation, including sudo, bash -c, nested wrappers, and recursion depth overflow scenarios.

Activity

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