🛡️ Sentinel: [CRITICAL] Fix Path Truncation Vulnerability

[EffortlessSteven]

🚨 Severity: CRITICAL
💡 Vulnerability: The validate_model_request function validated file extensions (like .gguf) using string operations but failed to check for null bytes (\0). This could allow attackers to bypass extension validation by appending a null byte followed by the required extension, causing underlying C APIs to load arbitrary files.
🎯 Impact: Attackers could potentially bypass file extension checks and load arbitrary files on the filesystem, leading to potential data exposure or code execution.
🔧 Fix: Added an explicit check for null bytes (\0) in the model_path during validation.
✅ Verification: Ran cargo test -p bitnet-server --lib security::tests:: and cargo clippy -p bitnet-server -- -D warnings. Both passed.

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PR created automatically by Jules for task 830514392079978534 started by @EffortlessSteven

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[gemini-code-assist]

Code Review

This pull request addresses a path truncation vulnerability by implementing a null byte check in the model path validation and documenting the vulnerability in the sentinel log. A review comment suggests broadening this check to include all control characters using char::is_control for improved security and to prevent issues like log injection.

[gemini-code-assist]

While blocking null bytes (\0) is critical to prevent path truncation and extension bypass when interacting with C APIs, it is a security best practice to reject all control characters in user-provided file paths. This broader check helps prevent other potential issues, such as log injection or unexpected behavior in downstream processing. Consider using char::is_control to catch all such characters.

Suggested change

	if model_path.contains("..") || model_path.contains("~") || model_path.contains('\0') {
	if model_path.contains("..") || model_path.contains("~") || model_path.contains(char::is_control) {