CNI plugin does not support network policies

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Metadata

Id: 03aabc8c-35d6-481e-9c85-20139cf72d23

Cloud Provider: Kubernetes

Platform: Kubernetes

Severity: Medium

Category: Networking and Firewall

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Description

Ensure the cluster uses a CNI plugin that supports NetworkPolicies. CNI plugins that do not support NetworkPolicies (for example, Flannel) cannot enforce pod- or namespace-level network restrictions, which may allow unrestricted cluster traffic and increase the attack surface.

Compliant Code Examples

{
  "name": "k8s-pod-network",
  "cniVersion": "0.3.0",
  "plugins": [
    {
      "type": "calico",
      "log_level": "info",
      "datastore_type": "kubernetes",
      "nodename": "127.0.0.1",
      "ipam": {
        "type": "host-local",
        "subnet": "usePodCidr"
      },
      "policy": {
        "type": "k8s"
      },
      "kubernetes": {
        "kubeconfig": "/etc/cni/net.d/calico-kubeconfig"
      }
    },
    {
      "type": "portmap",
      "capabilities": {"portMappings": true}
    }
  ]
}

kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  labels:
    tier: node
    app: calico
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "plugins": [
        {
          "type": "calico",
          "delegate": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }

Non-Compliant Code Examples

kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  labels:
    tier: node
    app: flannel
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "plugins": [
        {
          "type": "flannel",
          "delegate": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }

{
  "name": "k8s-pod-network",
  "cniVersion": "0.3.0",
  "plugins": [
    {
      "type": "flannel",
      "log_level": "info",
      "datastore_type": "kubernetes",
      "nodename": "127.0.0.1",
      "ipam": {
        "type": "host-local",
        "subnet": "usePodCidr"
      },
      "policy": {
        "type": "k8s"
      },
      "kubernetes": {
        "kubeconfig": "/etc/cni/net.d/flannel-kubeconfig"
      }
    },
    {
      "type": "portmap",
      "capabilities": {"portMappings": true}
    }
  ]
}