jakman85andClaude Opus 5
f178d85c71
Prod's UniFi VM has no disk. `DataVolume unifi/unifi-rootdisk` stuck in
ImportScheduled for hours, because Kyverno denied CDI's own generated pod:
validate.kyverno.svc-fail denied Pod/unifi/importer-prime-<uid>
require-auth-mode-label (R-IDP-02)
require-egress-class-label (R-NET-05)
Both policies match any Pod in an `app-namespace: "true"` namespace with no
exclusion, and CDI generates `importer-*` itself — it cannot carry repo labels.
A COLD-START defect, not a prod quirk: dev's identical import Succeeded 9 days
ago, before the policies enforced, so dev has never exercised it and would hit it
on any rebuild. Fourth bug of this shape in two days.
MECHANISM: a MUTATE ClusterPolicy that ADDS
`egress-class: internet` + `auth-mode: none` (add-if-absent anchor) to Pods on
CREATE in app namespaces WHEN the requesting subject is ServiceAccount
`cdi/cdi-sa`. Both validate policies are untouched — no exclude, no exception,
`background: true` preserved on them.
Why mutate beats exempting: the requirement stays literally true ("every pod in an
app namespace declares both labels") and the values are HONEST — the importer does
pull over the default WAN path, and `internet` is the least-reach class (it does
not grant the VPN path); a transient worker pod with no UI genuinely is
`auth-mode: none`.
THE MATCH IS IDENTITY, NOT A NAME. `subjects: ServiceAccount cdi/cdi-sa` is the
AdmissionReview userInfo, taken from the real prod denial
(`system:serviceaccount:cdi:cdi-sa`, name importer-prime-…, op CREATE). A name
prefix is attacker-choosable; a requesting ServiceAccount is not — and the test
proves it, with a fixture `importer-prime-forged-by-an-app` that copies both the
name prefix AND CDI's labels and is still DENIED. Covers every CDI worker kind
(importer/uploader/cloner) without enumerating names that change per release.
Confirmed on prod that cdi-sa is the only cdi-namespace SA that can create pods.
REJECTED, and the first one is a trap worth recording:
* PolicyException — the CRD EXISTS (v2/v2beta1, from the pre-applied bundle) but
all controllers run `--enablePolicyException=false` (verified live on prod:
admission, background and reports controllers all carry the flag). An exception
would apply cleanly through Flux and be SILENTLY IGNORED. Enabling the gate is a
cluster-wide capability change for no gain over the mutate.
* `exclude` scoped to cdi-sa — sound identity, worse consequences: any userInfo
match forces `background: false`, which would drop background scanning and
policy-report coverage of R-NET-05/R-IDP-02 for ALL EXISTING PODS to fix one pod
class. It also leaves the importer with no labels at all — the unlabelled
fall-through that require-egress-class-label's own header calls a fail-open leak.
* name-prefix / CDI-label matching — attacker-choosable, and proven walkable.
TWO-WAY PROOF, non-vacuous by construction — same resource, different requester,
opposite outcomes (verified by me, not just reported):
userinfo cdi-sa -> mutate pass, require-egress-class pass, require-auth-mode pass
userinfo ordinary -> mutate SKIP, require-egress-class FAIL, require-auth-mode FAIL
Kyverno L0 went 17 -> 29 tests passed, 0 failed. The mutate policy is deliberately
kept OUT of the existing tests/kyverno-test.yaml: that suite declares no userinfo,
and without userinfo the offline engine does not discriminate on subjects — it
mutates everything, which would have silently turned its negative rows into passes.
platform-config/kustomization.yaml is the live apply path for these ClusterPolicies;
without it the policy never reaches a cluster.
RESIDUAL TRADE-OFF, reversible by deleting one file: anything created by cdi-sa in
an app namespace now has these labels supplied rather than being rejected for not
declaring them — including a pod that is not a CDI worker. That identity already
holds `pods create/delete` cluster-wide via ClusterRole `cdi`, so it is not a new
capability; what changes is that for that one identity the declaration is assumed
rather than demanded. restrict-host-namespaces, the namespace default-deny baseline
and the CiliumNetworkPolicies all still apply.
FIRST resource-mutating policy on this cluster: kyverno-resource-mutating-webhook-cfg
holds 0 webhooks today; with autoUpdateWebhooks=true Kyverno registers
mutate.kyverno.svc-fail for Pods within seconds of this applying. Prod's
forceFailurePolicyIgnore=false makes it failurePolicy: Fail — same posture as the
validating webhook already in that path.
CDI retries importer creation on a loop, so the stuck import should proceed once
this lands. The detached prime-be3f9d1c-… 40 GiB scratch PVC is separate operator
cleanup; untouched, as is the DataVolume.
VERIFIED: full CI gate PASS. Nothing applied to any cluster.
Refs R-IDP-02, R-NET-05, R-PLAT-01.
Co-Authored-By: Claude Opus 5 <[email protected]>
22 lines
803 B
YAML
22 lines
803 B
YAML
# The requester identity Kyverno actually saw on prod when CDI created the importer pod
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# (from the kyverno-admission-controller log of the blocked request, 2026-09-06):
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# user={"username":"system:serviceaccount:cdi:cdi-sa","groups":["system:serviceaccounts",
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# "system:serviceaccounts:cdi","system:authenticated"], ...}
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# roles=["cdi:cdi-deployment"] clusterroles=["cdi", …]
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# `kyverno test` feeds this to the engine as the AdmissionReview userInfo so
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# `match.subjects` can be evaluated offline.
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apiVersion: cli.kyverno.io/v1alpha1
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kind: UserInfo
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metadata:
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name: cdi-controller
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clusterRoles:
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- cdi
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roles:
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- cdi:cdi-deployment
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userInfo:
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username: system:serviceaccount:cdi:cdi-sa
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groups:
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- system:serviceaccounts
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- system:serviceaccounts:cdi
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- system:authenticated
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