fix(security): supply C-0211's two non-privilege fields to flux-operator - #3577
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flux-system is excluded from add-pod-security-context and add-container-security-context because its workloads need elevated privilege by design. fsGroupChangePolicy and seLinuxOptions are not privilege fields, so that exclusion suppressed two CIS-5.7.3 (C-0211) rules it never needed to. The namespace-scoped add-baseline-context-optin-* rules cannot close this: all three match `kinds: Pod`, so they mutate at admission and leave the stored workload spec Kubescape reads untouched. Only a template-level change moves the measurement, which is why #3541 (velero) and #3544 (the four FluxInstance controllers) were done this way. Measured against live PROD stored specs 2026-09-04: of flux-system's six workloads, four already carry both fields from #3544, leaving flux-operator and tofu-controller; the latter is retired and pending removal in #3480. flux-operator is therefore the namespace's last workload needing this. Both fields are inert for this workload — it sets no fsGroup, so the kubelet's volume ownership pass never runs, and its only volumes are an emptyDir and the projected service-account token (no PVC, no hostPath). seLinuxOptions {level: s0} is the documented AppArmor-cluster no-op kept as CIS-5.7.3 defense-in-depth. Declared posture moves; runtime behaviour does not. Neither field carries the runAsGroup-without-runAsUser coupling that can stop a sandbox building. The pod-level op adds a leaf into the chart's pod securityContext, which renders as `{}`. A leaf add is deliberate: adding the whole object would replace it and silently discard any field the chart starts setting later. Proven with a before/after control through the same kyaml engine helm-controller uses, over a fixture built from the live Deployment with the post-rendered fields stripped back to chart shape: at base both fields read ABSENT; with this change they read OnRootMismatch and {level: s0}, with runAsUser 65532 preserved in both arms. Part of #3239 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Evidence and user evaluationWhy a template-level change, and not the namespace opt-in
Measured against live PROD, this run (2026-09-04)flux-system's six workloads:
This independently reproduces the residual the sizing record already names — "flux-system's remaining two are flux-operator and tofu-controller, the latter retired and pending removal in #3480" — so Both fields are inert here — established, not assumed
RED/GREEN, against the real object shapeThe assumption carrying actual risk was that a JSON-Patch leaf add works against the chart's pod
The control confirms the gap is real at base and that the existing Validation
What is deliberately NOT in this PRThe C-0211 sizing record in |
…flux-operator fix The rendered authorization surface fingerprint is a change-detection tripwire over every selected authorization-capable document. The flux-operator HelmRelease is one of them, so editing its postRenderer patch moves the aggregate digest even though the edit grants nothing. Conservation proven by rendering all five overlays from both trees with the same renderer and taking the set difference in BOTH directions over the complete apiVersion|kind|namespace|name identity: 548 documents on main e37660b and 548 on this branch — zero added, zero removed, zero renamed, and no duplicate identity on either side, so the pairing is one-to-one. The entire content delta across all five roots is seven added lines inside that one HelmRelease, with nothing removed anywhere: the two securityContext ops this branch adds. No rule, verb, resource, group, subject, ServiceAccount, role reference or policy moved. The value is CI's own computed digest at head 5dc2d80, taken from the failing run rather than recomputed locally: this validator pins the renderer to kubectl v1.36.2 and refuses any other, and the preparing host has v1.36.1. The conservation proof is renderer-robust because both sides used the same local renderer; the digest is not, so it comes from the pinned one. Part of #3239 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Documents on main e37660b2 |
548 |
| Documents on this branch | 548 |
| Added | 0 |
| Removed | 0 |
| Renamed | 0 |
| Duplicate identity, either side | 0 (so the pairing is one-to-one) |
Compared over the complete apiVersion\|kind\|namespace\|name identity across providers/hetzner/{apps,infrastructure,infrastructure/controllers} and clusters/prod/{bootstrap,}.
The entire content delta across all five roots is seven added lines in one document, with nothing removed anywhere — the two ops this PR adds. No rule, verb, resource, group, subject, ServiceAccount, role reference or policy moved on either side.
Why the digest comes from CI rather than a local recompute
The validator pins the renderer (kubectl v1.36.2) and refuses any other — the preparing host has v1.36.1, and it does refuse there (unapproved renderer: kubectl=v1.36.1). So the digest is CI's own computed value at head 5dc2d805. The conservation proof is renderer-robust in a way the digest is not, because both sides were rendered with the same local renderer; only the digest needs the pinned one.
A correction worth recording
My first attempt at this proof was void, and it failed in the flattering direction. I ran the mandated end-of-tick branch-cleanup.sh after pushing — which, by design, returns the checkout to the default branch. Every render I took after that came from main, so I was comparing main against main and got a perfect byte-identical result: diff rc=0, zero added, zero removed. That reads as the strongest possible evidence and was worth nothing.
The tell was a count that failed to move: seLinuxOptions was 49 on both sides when the change adds one, so it should have been 50. Re-checked out the branch (5dc2d805, ops present) and re-rendered; the numbers above are from that run and the delta is the expected 50 vs 49.
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📝 WalkthroughWalkthroughThe Flux Operator HelmRelease documents its template-level security-context requirements. Its Deployment post-renderer adds container SELinux level Merge Risk: 🟡 Moderate · up to This change adds the required security-context fields, but forcing a shared SELinux level may weaken isolation between Flux Operator Pods on SELinux-enabled nodes. Resolve or explicitly accept this deployment-specific security risk before merge. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Inline comments:
In `@k8s/bases/infrastructure/controllers/flux-operator/helm-release.yaml`:
- Line 101: Remove the fixed seLinuxOptions.level value of s0 from the security
context, preserving the required SELinux security context while allowing
runtime-assigned unique MCS categories on SELinux-enabled nodes.
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k8s/bases/infrastructure/controllers/flux-operator/helm-release.yamlscripts/validate-eks-ci-role-policy/main.go
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k8s/bases/infrastructure/controllers/flux-operator/helm-release.yaml
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scripts/validate-eks-ci-role-policy/main.go (1)
1658-1690: LGTM!
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Why
The twelve namespaces excluded from the cluster-wide security-context mutation are excluded because their workloads need elevated privilege. Two of the fields that exclusion suppresses aren't privilege fields at all, so the cluster has been carrying an open CIS-5.7.3 gap it never needed to.
In flux-system, four of six workloads were already fixed and one more is retiring — this closes the last one that actually needs it.
What
Supplies the two non-privilege fields to the Flux Operator through the same mechanism its existing hardening already uses. Both are inert for this workload: one governs a volume-ownership step that only runs when a pod requests it (this one doesn't), and the other is a documented no-op on this cluster's security module, kept because the benchmark requires it and it is correct on any cluster that does use SELinux. So the operator's declared posture improves and nothing about how it runs changes.
Verified against the live cluster and proven with a before/after control, including the one assumption that carried real risk.
Operational note: takes effect when the Flux Operator's deployment next reconciles. The posture measurement record is deliberately not edited here — it records measured state, and re-measuring after reconcile is how that file is maintained.
Part of #3239