Implements proper least-privilege model for RPC methods. Previously,
any UID in allowed_peer_uids could call privileged methods, meaning
another service's UID would inherit full host-level control.
Capability System:
- Three levels: read, write, admin
- Per-UID capability assignment via allowed_peers config
- Privileged methods require admin capability
- Backwards compatible with legacy allowed_peer_uids format
Configuration:
allowed_peers:
- uid: 0
capabilities: [read, write, admin] # Root gets all
- uid: 1000
capabilities: [read] # Docker: read-only
- uid: 1001
capabilities: [read, write] # Temps but not key distribution
Security benefit: Services can be granted only the capabilities they
need, preventing unintended privilege escalation.
Related to security audit 2025-11-07.
Co-authored-by: Codex <codex@openai.com>
Implements all remaining Codex recommendations before launch:
1. Privileged Methods Tests:
- TestPrivilegedMethodsCompleteness ensures all host-side RPCs are protected
- Will fail if new privileged RPC is added without authorization
- Verifies read-only methods are NOT in privilegedMethods
2. ID-Mapped Root Detection Tests:
- TestIDMappedRootDetection covers all boundary conditions
- Tests UID/GID range detection (both must be in range)
- Tests multiple ID ranges, edge cases, disabled mode
- 100% coverage of container identification logic
3. Authorization Tests:
- TestPrivilegedMethodsBlocked verifies containers can't call privileged RPCs
- TestIDMappedRootDisabled ensures feature can be disabled
- Tests both container and host credentials
4. Comprehensive Security Documentation (23 KB):
- Architecture overview with diagrams
- Complete authentication & authorization flow
- Rate limiting details (already implemented: 20/min per peer)
- SSH security model and forced commands
- Container isolation mechanisms
- Monitoring & alerting recommendations
- Development mode documentation (PULSE_DEV_ALLOW_CONTAINER_SSH)
- Troubleshooting guide with common issues
- Incident response procedures
Rate Limiting Status:
- Already implemented in throttle.go (20 req/min, burst 10, max 10 concurrent)
- Per-peer rate limiting at line 328 in main.go
- Per-node concurrency control at line 825 in main.go
- Exceeds Codex's requirements
All tests pass. Documentation covers all security aspects.
Addresses final Codex recommendations for production readiness.
