istio.io/content/en/docs/tasks/security/authorization/authz-deny/index.md

title	description	weight	keywords	owner	test
Explicit Deny	Shows how to set up access control to deny traffic explicitly.	40	security access-control rbac authorization deny	istio/wg-security-maintainers	yes

This task shows you how to set up Istio authorization policy of DENY action to explicitly deny traffic in an Istio mesh. This is different from the ALLOW action because the DENY action has higher priority and will not be bypassed by any ALLOW actions.

Before you begin

Before you begin this task, do the following:

• Read the Istio authorization concepts.

• Follow the Istio installation guide to install Istio.

• Deploy workloads:

  This task uses two workloads, httpbin and curl, deployed on one namespace, foo. Both workloads run with an Envoy proxy in front of each. Deploy the example namespace and workloads with the following command:

  {{< text bash >}} $ kubectl create ns foo $ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@) -n foo $ kubectl apply -f <(istioctl kube-inject -f @samples/curl/curl.yaml@) -n foo {{< /text >}}

• Verify that curl talks to httpbin with the following command:

  {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl http://httpbin.foo:8000/ip -sS -o /dev/null -w "%{http_code}\n" 200 {{< /text >}}

{{< warning >}} If you don’t see the expected output as you follow the task, retry after a few seconds. Caching and propagation overhead can cause some delay. {{< /warning >}}

Explicitly deny a request

1. The following command creates the deny-method-get authorization policy for the httpbin workload in the foo namespace. The policy sets the action to DENY to deny requests that satisfy the conditions set in the rules section. This type of policy is better known as a deny policy. In this case, the policy denies requests if their method is GET.

   {{< text bash >}} $ kubectl apply -f - <<EOF apiVersion: security.istio.io/v1 kind: AuthorizationPolicy metadata: name: deny-method-get namespace: foo spec: selector: matchLabels: app: httpbin action: DENY rules:

   • to:
     • operation: methods: ["GET"] EOF {{< /text >}}

2. Verify that GET requests are denied:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/get" -X GET -sS -o /dev/null -w "%{http_code}\n" 403 {{< /text >}}

3. Verify that POST requests are allowed:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/post" -X POST -sS -o /dev/null -w "%{http_code}\n" 200 {{< /text >}}

4. Update the deny-method-get authorization policy to deny GET requests only if the x-token value of the HTTP header is not admin. The following example policy sets the value of the notValues field to ["admin"] to deny requests with a header value that is not admin:

   {{< text bash >}} $ kubectl apply -f - <<EOF apiVersion: security.istio.io/v1 kind: AuthorizationPolicy metadata: name: deny-method-get namespace: foo spec: selector: matchLabels: app: httpbin action: DENY rules:

   • to:
     • operation: methods: ["GET"] when:
     • key: request.headers[x-token] notValues: ["admin"] EOF {{< /text >}}

5. Verify that GET requests with the HTTP header x-token: admin are allowed:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/get" -X GET -H "x-token: admin" -sS -o /dev/null -w "%{http_code}\n" 200 {{< /text >}}

6. Verify that GET requests with the HTTP header x-token: guest are denied:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/get" -X GET -H "x-token: guest" -sS -o /dev/null -w "%{http_code}\n" 403 {{< /text >}}

7. The following command creates the allow-path-ip authorization policy to allow requests at the /ip path to the httpbin workload. This authorization policy sets the action field to ALLOW. This type of policy is better known as an allow policy.

   {{< text bash >}} $ kubectl apply -f - <<EOF apiVersion: security.istio.io/v1 kind: AuthorizationPolicy metadata: name: allow-path-ip namespace: foo spec: selector: matchLabels: app: httpbin action: ALLOW rules:

   • to:
     • operation: paths: ["/ip"] EOF {{< /text >}}

8. Verify that GET requests with the HTTP header x-token: guest at path /ip are denied by the deny-method-get policy. Deny policies takes precedence over the allow policies:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/ip" -X GET -H "x-token: guest" -s -o /dev/null -w "%{http_code}\n" 403 {{< /text >}}

9. Verify that GET requests with the HTTP header x-token: admin at path /ip are allowed by the allow-path-ip policy:

   {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/ip" -X GET -H "x-token: admin" -s -o /dev/null -w "%{http_code}\n" 200 {{< /text >}}

10. Verify that GET requests with the HTTP header x-token: admin at path /get are denied because they don’t match the allow-path-ip policy:

    {{< text bash >}} kubectl exec "(kubectl get pod -l app=curl -n foo -o jsonpath={.items..metadata.name})" -c curl -n foo -- curl "http://httpbin.foo:8000/get" -X GET -H "x-token: admin" -s -o /dev/null -w "%{http_code}\n" 403 {{< /text >}}

Clean up

Remove the namespace foo from your configuration:

{{< text bash >}} $ kubectl delete namespace foo {{< /text >}}