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sec(sandbox): graceful degradation to no network namespace isolation #586
Description
Summary
At crates/openshell-sandbox/src/sandbox/linux/netns.rs (lines 246–257), if iptables is not found, bypass rules are silently skipped with a warning. If network namespace creation fails (missing CAP_NET_ADMIN), the proxy falls back to binding on 127.0.0.1:3128 (crates/openshell-sandbox/src/proxy.rs, lines 137–149).
In this fallback mode, the sandbox process could make direct outbound connections that bypass the proxy entirely, since there is no network namespace isolation.
Impact
- Severity: Medium
- Policy enforcement (OPA evaluation, SSRF blocking, credential injection) relies on traffic flowing through the proxy. Without network namespace isolation, this is advisory only.
Proposed Fix
Consider making network namespace creation mandatory (fail-closed) rather than degrading to a less-secure mode. At minimum, emit an error-level log and surface the degradation in openshell status or openshell doctor.
Activity
johntmyers commentedon Mar 24, 2026
Security triage determination: No-go (outdated against current code path).
Current proxy-mode startup fails closed when network-namespace creation fails; it does not silently continue in an unrestricted mode. The report appears to reflect older behavior and no longer matches present enforcement flow.
If there is a suspected regression, please provide a reproduction against current main with logs. Without that, this is not actionable.