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Signed-off-by: AnaisUrlichs <urlichsanais@gmail.com> Co-authored-by: saso <sasoakira6114@gmail.com>
99 lines
3.2 KiB
Markdown
99 lines
3.2 KiB
Markdown
# Attesting Image Scans With Kyverno
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This tutorial is based on the following blog post by Chip Zoller: [Attesting Image Scans With Kyverno](https://neonmirrors.net/post/2022-07/attesting-image-scans-kyverno/)
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This tutorial details
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- Verify the container image has an attestation with Kyverno
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### Prerequisites
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1. A running Kubernetes cluster that kubectl is connected to
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2. A Container image signed with Cosign and an attestation generated for a Trivy Vulnerability scan.
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[Follow this tutorial for more information.][vuln-attestation]
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### Kyverno Policy to check attestation
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The following policy ensures that the attestation is no older than 168h:
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vuln-attestation.yaml
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{% raw %}
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```bash
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apiVersion: kyverno.io/v1
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kind: ClusterPolicy
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metadata:
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name: check-vulnerabilities
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spec:
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validationFailureAction: Enforce
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background: false
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webhookTimeoutSeconds: 30
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failurePolicy: Fail
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rules:
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- name: checking-vulnerability-scan-not-older-than-one-hour
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match:
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any:
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- resources:
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kinds:
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- Pod
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verifyImages:
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- imageReferences:
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- "*"
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attestations:
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- type: https://cosign.sigstore.dev/attestation/vuln/v1
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conditions:
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- all:
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- key: "{{ time_since('','{{ metadata.scanFinishedOn }}', '') }}"
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operator: LessThanOrEquals
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value: "1h"
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attestors:
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- count: 1
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entries:
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- keys:
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publicKeys: |-
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-----BEGIN PUBLIC KEY-----
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abc
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xyz
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-----END PUBLIC KEY-----
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```
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{% endraw %}
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### Apply the policy to your Kubernetes cluster
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Ensure that you have Kyverno already deployed and running on your cluster -- for instance through he Kyverno Helm Chart.
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Next, apply the above policy:
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```
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kubectl apply -f vuln-attestation.yaml
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```
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To ensure that the policy worked, we can deploy an example Kubernetes Pod with our container image:
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```
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kubectl run app-signed --image= docker.io/anaisurlichs/signed-example@sha256:c5911ac313e0be82a740bd726dc290e655800a9588424ba4e0558c705d1287fd
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```
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Note that the image is based on the [signing tutorial.][vuln-attestation]
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Once we apply the deployment, it should pass since our attestation is available:
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```
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kubectl apply -f deployment.yaml -n app
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deployment.apps/cns-website created
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```
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However, if we try to deploy any other container image, our deployment will fail. We can verify this by replacing the image referenced in the deployment with `docker.io/anaisurlichs/cns-website:0.0.5` and applying the deployment:
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```
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kubectl run app-unsigned --image=docker.io/anaisurlichs/cns-website:0.1.1
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Resource: "apps/v1, Resource=deployments", GroupVersionKind: "apps/v1, Kind=Deployment"
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Name: "cns-website", Namespace: "app"
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for: "deployment-two.yaml": admission webhook "mutate.kyverno.svc-fail" denied the request:
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resource Deployment/app/cns-website was blocked due to the following policies
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check-image:
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autogen-check-image: |
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failed to verify signature for docker.io/anaisurlichs/cns-website:0.0.5: .attestors[0].entries[0].keys: no matching signatures:
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```
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[vuln-attestation]: ../signing/vuln-attestation.md |