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auth: don't allow kubelet to from modify ResourceClaimStatuses

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The status determines which claims kubelet is allowed to access when claims get
created from a template. Therefore kubelet must not be allowed to modify that
part of the status, because otherwise it could add an entry and then gain
access to a claim it should have access to.
This commit is contained in:
Patrick Ohly 2023-07-13 20:39:48 +02:00
parent 1db11c07ff
commit 4121c1fc79
1 changed files with 26 additions and 0 deletions
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26
plugin/pkg/admission/noderestriction/admission.go
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@ -288,6 +288,9 @@ func (p *Plugin) admitPodStatus(nodeName string, a admission.Attributes) error {
if !labels.Equals(oldPod.Labels, newPod.Labels) { if !labels.Equals(oldPod.Labels, newPod.Labels) {
return admission.NewForbidden(a, fmt.Errorf("node %q cannot update labels through pod status", nodeName)) return admission.NewForbidden(a, fmt.Errorf("node %q cannot update labels through pod status", nodeName))
} }
if !resourceClaimStatusesEqual(oldPod.Status.ResourceClaimStatuses, newPod.Status.ResourceClaimStatuses) {
return admission.NewForbidden(a, fmt.Errorf("node %q cannot update resource claim statues", nodeName))
}
return nil return nil
default: default:
@ -295,6 +298,29 @@ func (p *Plugin) admitPodStatus(nodeName string, a admission.Attributes) error {
} }
} }
func resourceClaimStatusesEqual(statusA, statusB []api.PodResourceClaimStatus) bool {
if len(statusA) != len(statusB) {
return false
}
// In most cases, status entries only get added once and not modified.
// But this cannot be guaranteed, so for the sake of correctness in all
// cases this code here has to check.
for i := range statusA {
if statusA[i].Name != statusB[i].Name {
return false
}
claimNameA := statusA[i].ResourceClaimName
claimNameB := statusB[i].ResourceClaimName
if (claimNameA == nil) != (claimNameB == nil) {
return false
}
if claimNameA != nil && *claimNameA != *claimNameB {
return false
}
}
return true
}
// admitPodEviction allows to evict a pod if it is assigned to the current node. // admitPodEviction allows to evict a pod if it is assigned to the current node.
func (p *Plugin) admitPodEviction(nodeName string, a admission.Attributes) error { func (p *Plugin) admitPodEviction(nodeName string, a admission.Attributes) error {
switch a.GetOperation() { switch a.GetOperation() {