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Update verbs used to check SAR for users when k8s components are used #1050

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merged 1 commit into from
Feb 22, 2023
Merged

Update verbs used to check SAR for users when k8s components are used #1050

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76 changes: 47 additions & 29 deletions webhook/workspace/handler/kubernetes.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,13 @@ import (
"sigs.k8s.io/yaml"
)

var (
// Verbs used in SAR checks when users attempt to use a Kubernetes/OpenShift component. A longer list results in
// more SAR checks per request. We cannot use '*' as a verb as the SAR will check for literal '*' permissions
// rather than "all verbs"
userVerbs = []string{"get", "create", "update", "delete"}
)

func (h *WebhookHandler) validateKubernetesObjectPermissionsOnCreate(ctx context.Context, req admission.Request, wksp *dwv2.DevWorkspaceTemplateSpec) error {
kubeComponents := getKubeComponentsFromWorkspace(wksp)
for componentName, component := range kubeComponents {
Expand Down Expand Up @@ -97,37 +104,14 @@ func (h *WebhookHandler) validatePermissionsOnObject(ctx context.Context, req ad
// Convert e.g. Pod -> pods, Deployment -> deployments
resourceType := fmt.Sprintf("%ss", strings.ToLower(typeMeta.Kind))

sar := &authv1.LocalSubjectAccessReview{
ObjectMeta: metav1.ObjectMeta{
Namespace: req.Namespace,
},
Spec: authv1.SubjectAccessReviewSpec{
ResourceAttributes: &authv1.ResourceAttributes{
Namespace: req.Namespace,
Verb: "*",
Group: typeMeta.GroupVersionKind().Group,
Version: typeMeta.GroupVersionKind().Version,
Resource: resourceType,
},
User: req.UserInfo.Username,
Groups: req.UserInfo.Groups,
UID: req.UserInfo.UID,
},
}

err := h.Client.Create(ctx, sar)
if err != nil {
return fmt.Errorf("failed to create subjectaccessreview for request: %w", err)
}

username := req.UserInfo.Username
if username == "" {
username = req.UserInfo.UID
}
if !sar.Status.Allowed {
return fmt.Errorf("user %s does not have permissions to work with objects of kind %s defined in component %s", username, typeMeta.GroupVersionKind().String(), componentName)
// Check that user has permissions to use the resource
for _, verb := range userVerbs {
if err := h.checkSAR(ctx, req, typeMeta, resourceType, verb, componentName); err != nil {
return err
}
}

// Check that DWO has '*' permissions for the relevant resource
ssar := &authv1.LocalSubjectAccessReview{
ObjectMeta: metav1.ObjectMeta{
Namespace: req.Namespace,
Expand Down Expand Up @@ -250,3 +234,37 @@ func getKubeLikeComponent_v1alpha1(component *dwv1.Component) (*dwv1.K8sLikeComp
}
return nil, fmt.Errorf("component does not specify kubernetes or openshift fields")
}

func (h *WebhookHandler) checkSAR(ctx context.Context, req admission.Request, typeMeta *metav1.TypeMeta, resourceType, verb, componentName string) error {
sar := &authv1.LocalSubjectAccessReview{
ObjectMeta: metav1.ObjectMeta{
Namespace: req.Namespace,
},
Spec: authv1.SubjectAccessReviewSpec{
ResourceAttributes: &authv1.ResourceAttributes{
Namespace: req.Namespace,
Verb: verb,
Group: typeMeta.GroupVersionKind().Group,
Version: typeMeta.GroupVersionKind().Version,
Resource: resourceType,
},
User: req.UserInfo.Username,
Groups: req.UserInfo.Groups,
UID: req.UserInfo.UID,
},
}

err := h.Client.Create(ctx, sar)
if err != nil {
return fmt.Errorf("failed to create subjectaccessreview for request: %w", err)
}

username := req.UserInfo.Username
if username == "" {
username = req.UserInfo.UID
}
if !sar.Status.Allowed {
return fmt.Errorf("user %s does not have permissions to '%s' objects of kind %s defined in component %s", username, verb, typeMeta.GroupVersionKind().String(), componentName)
}
return nil
}