mirror of
https://github.com/kubernetes-sigs/kubespray.git
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082507cff2
Add variable to set kubelet staticPodPath location. It can be set to empty so that we can choose to disable it for some nodes. STIG recommendation is to disable it. Signed-off-by: Shaleen Bathla <shaleenbathla@gmail.com> Co-authored-by: ChengHao Yang <17496418+tico88612@users.noreply.github.com>
140 lines
5.9 KiB
Markdown
140 lines
5.9 KiB
Markdown
# Cluster Hardening
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If you want to improve the security on your cluster and make it compliant with the [CIS Benchmarks](https://learn.cisecurity.org/benchmarks), here you can find a configuration to harden your **kubernetes** installation.
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To apply the hardening configuration, create a file (eg. `hardening.yaml`) and paste the content of the following code snippet into that.
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## Minimum Requirements
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The **kubernetes** version should be at least `v1.23.6` to have all the most recent security features (eg. the new `PodSecurity` admission plugin, etc).
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**N.B.** Some of these configurations have just been added to **kubespray**, so ensure that you have the latest version to make it works properly. Also, ensure that other configurations doesn't override these.
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`hardening.yaml`:
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```yaml
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# Hardening
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---
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## kube-apiserver
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authorization_modes: ['Node', 'RBAC']
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kube_apiserver_request_timeout: 120s
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kube_apiserver_service_account_lookup: true
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# enable kubernetes audit
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kubernetes_audit: true
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audit_log_path: "/var/log/kube-apiserver-log.json"
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audit_log_maxage: 30
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audit_log_maxbackups: 10
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audit_log_maxsize: 100
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tls_min_version: VersionTLS12
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tls_cipher_suites:
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- TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
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- TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
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- TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305
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# enable encryption at rest
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kube_encrypt_secret_data: true
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kube_encryption_resources: [secrets]
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kube_encryption_algorithm: "secretbox"
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kube_apiserver_enable_admission_plugins:
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- EventRateLimit
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- AlwaysPullImages
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- ServiceAccount
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- NamespaceLifecycle
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- NodeRestriction
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- LimitRanger
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- ResourceQuota
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- MutatingAdmissionWebhook
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- ValidatingAdmissionWebhook
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- PodNodeSelector
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- PodSecurity
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kube_apiserver_admission_control_config_file: true
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# Creates config file for PodNodeSelector
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# kube_apiserver_admission_plugins_needs_configuration: [PodNodeSelector]
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# Define the default node selector, by default all the workloads will be scheduled on nodes
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# with label network=srv1
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# kube_apiserver_admission_plugins_podnodeselector_default_node_selector: "network=srv1"
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# EventRateLimit plugin configuration
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kube_apiserver_admission_event_rate_limits:
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limit_1:
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type: Namespace
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qps: 50
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burst: 100
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cache_size: 2000
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limit_2:
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type: User
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qps: 50
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burst: 100
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kube_profiling: false
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# Remove anonymous access to cluster
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remove_anonymous_access: true
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## kube-controller-manager
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kube_controller_manager_bind_address: 127.0.0.1
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kube_controller_terminated_pod_gc_threshold: 50
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kube_controller_feature_gates: ["RotateKubeletServerCertificate=true"]
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## kube-scheduler
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kube_scheduler_bind_address: 127.0.0.1
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## etcd
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etcd_deployment_type: kubeadm
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## kubelet
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kubelet_authorization_mode_webhook: true
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kubelet_authentication_token_webhook: true
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kube_read_only_port: 0
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kubelet_rotate_server_certificates: true
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kubelet_protect_kernel_defaults: true
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kubelet_event_record_qps: 1
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kubelet_rotate_certificates: true
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kubelet_streaming_connection_idle_timeout: "5m"
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kubelet_make_iptables_util_chains: true
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kubelet_feature_gates: ["RotateKubeletServerCertificate=true"]
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kubelet_seccomp_default: true
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kubelet_systemd_hardening: true
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# To disable kubelet's staticPodPath (for nodes that don't use static pods like worker nodes)
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kubelet_static_pod_path: ""
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# In case you have multiple interfaces in your
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# control plane nodes and you want to specify the right
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# IP addresses, kubelet_secure_addresses allows you
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# to specify the IP from which the kubelet
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# will receive the packets.
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kubelet_secure_addresses: "localhost link-local {{ kube_pods_subnet }} 192.168.10.110 192.168.10.111 192.168.10.112"
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# additional configurations
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kube_owner: root
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kube_cert_group: root
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# create a default Pod Security Configuration and deny running of insecure pods
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# kube_system namespace is exempted by default
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kube_pod_security_use_default: true
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kube_pod_security_default_enforce: restricted
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```
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Let's take a deep look to the resultant **kubernetes** configuration:
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* The `anonymous-auth` (on `kube-apiserver`) is set to `true` by default. This is fine, because it is considered safe if you enable `RBAC` for the `authorization-mode`.
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* The `enable-admission-plugins` includes `PodSecurity` (for more details, please take a look here: <https://kubernetes.io/docs/concepts/security/pod-security-admission/>). Then, we set the `EventRateLimit` plugin, providing additional configuration files (that are automatically created under the hood and mounted inside the `kube-apiserver` container) to make it work.
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* The `encryption-provider-config` provide encryption at rest. This means that the `kube-apiserver` encrypt data that is going to be stored before they reach `etcd`. So the data is completely unreadable from `etcd` (in case an attacker is able to exploit this).
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* The `rotateCertificates` in `KubeletConfiguration` is set to `true` along with `serverTLSBootstrap`. This could be used in alternative to `tlsCertFile` and `tlsPrivateKeyFile` parameters. Additionally it automatically generates certificates by itself. By default the CSRs are approved automatically via [kubelet-csr-approver](https://github.com/postfinance/kubelet-csr-approver). You can customize approval configuration by modifying Helm values via `kubelet_csr_approver_values`.
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See <https://kubernetes.io/docs/reference/access-authn-authz/kubelet-tls-bootstrapping/> for more information on the subject.
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* The `kubelet_systemd_hardening`, both with `kubelet_secure_addresses` setup a minimal firewall on the system. To better understand how these variables work, here's an explanatory image:
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Once you have the file properly filled, you can run the **Ansible** command to start the installation:
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```bash
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ansible-playbook -v cluster.yml \
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-i inventory.ini \
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-b --become-user=root \
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--private-key ~/.ssh/id_ecdsa \
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-e "@vars.yaml" \
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-e "@hardening.yaml"
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```
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**N.B.** The `vars.yaml` contains our general cluster information (SANs, load balancer, dns, etc..) and `hardening.yaml` is the file described above.
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