fix(security): consolidated path traversal prevention for MCP and session storage

[echobt]

Summary

This PR consolidates 2 security fixes for path traversal vulnerabilities.

Included PRs:

• fix(tui): prevent path traversal in session storage via session_id sanitization #81: Prevent path traversal in session storage via session_id sanitization
• fix(tui): prevent path traversal in MCP storage via server name sanitization #83: Prevent path traversal in MCP storage via server name sanitization

Key Changes:

• Add sanitize_session_id() function that replaces dangerous characters
• Add validate_session_id() for pre-validation of untrusted input
• Add sanitize_server_name() function for MCP server names
• Add validate_server_name() for pre-validation of MCP server names
• Only alphanumeric, hyphen, and underscore characters are allowed

Files Modified:

• src/cortex-tui/src/session/storage.rs
• src/cortex-tui/src/mcp_storage.rs

Closes #81, #83

[greptile-apps]

Greptile Overview

Greptile Summary

This PR consolidates two critical security fixes that prevent path traversal vulnerabilities in both MCP server storage and session storage.

Key Security Improvements:

• Added sanitize_server_name() and sanitize_session_id() functions that replace all non-alphanumeric characters (except hyphens and underscores) with underscores
• Added validate_server_name() and validate_session_id() for pre-validation of untrusted input
• Applied sanitization at the critical path construction points: server_path() in mcp_storage.rs:195 and session_dir() in session/storage.rs:96
• Comprehensive test coverage for both sanitization and validation functions, including path traversal test cases

Security Analysis:
The implementation effectively prevents path traversal attacks by sanitizing user-controlled input (server names and session IDs) before using them in filesystem operations. The sanitization is applied consistently at the single point where paths are constructed (server_path() and session_dir()), ensuring all downstream operations are protected. This defense-in-depth approach prevents attackers from escaping the intended storage directories using sequences like ../, ../../, or null bytes.

Testing:
All security-critical functions have dedicated unit tests that verify:

• Normal alphanumeric names pass through unchanged
• Path traversal attempts (../../../etc) are properly sanitized
• The resulting paths remain within the intended base directory
• No .. sequences appear in final paths

Confidence Score: 5/5

• This PR is safe to merge with no identified issues
• The security fixes are well-implemented with proper sanitization at the correct entry points, comprehensive test coverage, and no breaking changes to the API. The sanitization functions follow security best practices by using an allowlist approach (only allowing alphanumeric, hyphen, underscore) rather than a denylist. All filesystem operations that use user-controlled input are now protected.
• No files require special attention

Important Files Changed

Filename	Overview
src/cortex-tui/src/mcp_storage.rs	Added sanitize_server_name() and validate_server_name() functions to prevent path traversal; applied sanitization in server_path(); comprehensive tests included
src/cortex-tui/src/session/storage.rs	Added sanitize_session_id() and validate_session_id() functions to prevent path traversal; applied sanitization in session_dir(); comprehensive tests included

Sequence Diagram

sequenceDiagram
    participant User
    participant API as save_server/session_dir
    participant Sanitize as sanitize_*
    participant FS as Filesystem
    
    User->>API: Provide name/ID (potentially malicious)
    Note over User,API: e.g., "../../../etc/passwd"
    
    API->>Sanitize: sanitize_server_name(name) / sanitize_session_id(id)
    Note over Sanitize: Replace non-alphanumeric chars<br/>(except - and _) with _
    Sanitize->>Sanitize: "../../../etc" → "________etc"
    Sanitize-->>API: Return sanitized string
    
    API->>API: Construct path with sanitized value
    Note over API: base_dir.join(sanitized_name)
    
    API->>FS: Access file with safe path
    Note over FS: Path is confined to base_dir<br/>No traversal possible
    FS-->>API: Success
    API-->>User: Operation complete

Loading

[greptile-apps]

_{2 files reviewed, no comments}

_{Edit Code Review Agent Settings | Greptile}

[echobt]

Closing this PR to consolidate into a single mega-PR combining all bug fixes. The changes will be included in a new consolidated PR.