[cherry-pick: release-v0.3.x] fix(rbac): harden ClusterRole to least-privilege - #416
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Remove unused Knative boilerplate RBAC that granted permissions the
controller and webhook never exercise, reducing post-compromise blast
radius.
- Namespace: reduce from full CRUD to get/list/watch; remove
namespaces/finalizers (never referenced in code)
- Webhook configs: remove mutatingwebhookconfigurations entirely
(no mutating webhook exists); scope validatingwebhookconfigurations
to resourceNames + get/update only
- Secrets: remove cluster-wide get/list/watch (namespaced Role in
tekton-pipelines already covers it); switch webhook secret informer
from cluster-scoped to namespace-scoped import
Signed-off-by: Shubham Bhardwaj <shubbhar@redhat.com>
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This is a cherry-pick of #391
Changes
The ClusterRole
tekton-pruner-controller-cluster-accesscontainedKnative boilerplate RBAC rules that grant permissions the code never
uses. This tightens every rule to match actual runtime behavior:
get/list/watchonly. Thenamespaces/finalizersrule is removed — no code path referencesnamespace finalizers.
mutatingwebhookconfigurationsremovedentirely (no mutating webhook exists).
validatingwebhookconfigurationsscoped to
resourceNames: [validation.webhook.pruner.tekton.dev]with only
getandupdate(the two verbs used inpkg/webhook/configmapvalidation.go).get/list/watchremoved. The namespacedRole in
tekton-pipelinesalready grants secret access. The webhook'ssecret informer import is switched from the cluster-scoped factory
(
knative.dev/pkg/client/injection/kube/informers/core/v1/secret)to the namespace-scoped factory
(
knative.dev/pkg/injection/clients/namespacedkube/informers/core/v1/secret),which is the same one the certificate controller already uses.
Why
A compromised pruner pod could use these unused permissions to delete
arbitrary namespaces, read secrets from any namespace, or register
malicious mutating webhooks. These are hardening issues — not directly
exploitable without prior pod compromise — but reducing the blast
radius is standard least-privilege hygiene.
Submitter Checklist
As the author of this PR, please check off the items in this checklist:
/kind <type>. Valid types are bug, cleanup, design, documentation, feature, flake, misc, question, tepRelease Notes
/kind misc