feat(sandbox): Landlock TCP port restriction for mandatory proxy enforcement#13
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Ladas wants to merge 1 commit into
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feat(sandbox): Landlock TCP port restriction for mandatory proxy enforcement#13Ladas wants to merge 1 commit into
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When Platform mode is active, apply Landlock ABI v4 network rules to restrict TCP connect to only the proxy port (default 3128). This makes the loopback CONNECT proxy mandatory at the kernel level -- a process calling connect() to any other port gets EACCES. This closes the cooperative proxy gap identified in the enforcement analysis: without this, processes ignoring HTTP_PROXY could bypass the proxy and connect directly (caught only by Tier 3 NetworkPolicy). With this, enforcement is at Tier 1 (kernel LSM). Graceful degradation: if the kernel does not support Landlock ABI v4 (e.g. RHEL 9.5 or earlier), the network rules are silently skipped and enforcement falls back to the cooperative proxy + NetworkPolicy (same as Issue NVIDIA#899 base behavior). Ref: NVIDIA#899
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Summary
Add Landlock ABI v4 TCP port restriction to Platform mode. When active,
the kernel restricts
connect()to only the proxy port (default 3128).Any
connect()to another port returns EACCES at the kernel level.This closes the cooperative proxy gap: without this, a process ignoring
HTTP_PROXYcan connect directly (caught only by K8s NetworkPolicy atthe CNI level). With this, enforcement is at the kernel LSM layer -- no
userspace bypass possible.
Depends on: #12 (Platform mode base)
What changes
AccessNet,NetPortfrom thelandlockcrate (already v0.4, supports network rules)prepare(): handleAccessNet::ConnectTcpand addNetPortrule for the proxy port when Platform modeHow it works
Related
docs/research/openshell-network-enforcement-analysis.mdAssisted-By: Claude Code