Chapter 10. Configuring TLS security profiles TLS security profiles provide a way for servers to regulate which ciphers a client can use when connecting to the server. This ensures that OpenShift Container Platform components use cryptographic libraries that do not allow known insecure protocols, ciphers, or algorithms. Cluster administrators can choose which TLS security profile to use for each of the following components: the Ingress Controller the control plane This includes the Kubernetes API server, Kubernetes controller manager, Kubernetes scheduler, OpenShift API server, OpenShift OAuth API server, OpenShift OAuth server, and etcd. the kubelet, when it acts as an HTTP server for the Kubernetes API server 10.1. Understanding TLS security profiles You can use a TLS (Transport Layer Security) security profile to define which TLS ciphers are required by various OpenShift Container Platform components. The OpenShift Container Platform TLS security profiles are based on Mozilla recommended configurations . You can specify one of the following TLS security profiles for each component: Table 10.1. TLS security profiles Profile Description Old This profile is intended for use with legacy clients or libraries. The profile is based on the Old backward compatibility recommended configuration. The Old profile requires a minimum TLS version of 1.0. Note For the Ingress Controller, the minimum TLS version is converted from 1.0 to 1.1. Intermediate This profile is the recommended configuration for the majority of clients. It is the default TLS security profile for the Ingress Controller, kubelet, and control plane. The profile is based on the Intermediate compatibility recommended configuration. The Intermediate profile requires a minimum TLS version of 1.2. Modern This profile is intended for use with modern clients that have no need for backwards compatibility. This profile is based on the Modern compatibility recommended configuration. The Modern profile requires a minimum TLS version of 1.3. Custom This profile allows you to define the TLS version and ciphers to use. Warning Use caution when using a Custom profile, because invalid configurations can cause problems. Note When using one of the predefined profile types, the effective profile configuration is subject to change between releases. For example, given a specification to use the Intermediate profile deployed on release X.Y.Z, an upgrade to release X.Y.Z+1 might cause a new profile configuration to be applied, resulting in a rollout. 10.2. Viewing TLS security profile details You can view the minimum TLS version and ciphers for the predefined TLS security profiles for each of the following components: Ingress Controller, control plane, and kubelet. Important The effective configuration of minimum TLS version and list of ciphers for a profile might differ between components. Procedure View details for a specific TLS security profile: USD oc explain <component>.spec.tlsSecurityProfile.<profile> 1 1 For <component> , specify ingresscontroller , apiserver , or kubeletconfig . For <profile> , specify old , intermediate , or custom . For example, to check the ciphers included for the intermediate profile for the control plane: USD oc explain apiserver.spec.tlsSecurityProfile.intermediate Example output KIND: APIServer VERSION: config.openshift.io/v1 DESCRIPTION: intermediate is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Intermediate_compatibility_.28recommended.29 and looks like this (yaml): ciphers: - TLS_AES_128_GCM_SHA256 - TLS_AES_256_GCM_SHA384 - TLS_CHACHA20_POLY1305_SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES256-GCM-SHA384 - ECDHE-RSA-AES256-GCM-SHA384 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - DHE-RSA-AES128-GCM-SHA256 - DHE-RSA-AES256-GCM-SHA384 minTLSVersion: TLSv1.2 View all details for the tlsSecurityProfile field of a component: USD oc explain <component>.spec.tlsSecurityProfile 1 1 For <component> , specify ingresscontroller , apiserver , or kubeletconfig . For example, to check all details for the tlsSecurityProfile field for the Ingress Controller: USD oc explain ingresscontroller.spec.tlsSecurityProfile Example output KIND: IngressController VERSION: operator.openshift.io/v1 RESOURCE: tlsSecurityProfile <Object> DESCRIPTION: ... FIELDS: custom <> custom is a user-defined TLS security profile. Be extremely careful using a custom profile as invalid configurations can be catastrophic. An example custom profile looks like this: ciphers: - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: TLSv1.1 intermediate <> intermediate is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Intermediate_compatibility_.28recommended.29 and looks like this (yaml): ... 1 modern <> modern is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Modern_compatibility and looks like this (yaml): ... 2 NOTE: Currently unsupported. old <> old is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Old_backward_compatibility and looks like this (yaml): ... 3 type <string> ... 1 Lists ciphers and minimum version for the intermediate profile here. 2 Lists ciphers and minimum version for the modern profile here. 3 Lists ciphers and minimum version for the old profile here. 10.3. Configuring the TLS security profile for the Ingress Controller To configure a TLS security profile for an Ingress Controller, edit the IngressController custom resource (CR) to specify a predefined or custom TLS security profile. If a TLS security profile is not configured, the default value is based on the TLS security profile set for the API server. Sample IngressController CR that configures the Old TLS security profile apiVersion: operator.openshift.io/v1 kind: IngressController ... spec: tlsSecurityProfile: old: {} type: Old ... The TLS security profile defines the minimum TLS version and the TLS ciphers for TLS connections for Ingress Controllers. You can see the ciphers and the minimum TLS version of the configured TLS security profile in the IngressController custom resource (CR) under Status.Tls Profile and the configured TLS security profile under Spec.Tls Security Profile . For the Custom TLS security profile, the specific ciphers and minimum TLS version are listed under both parameters. Note The HAProxy Ingress Controller image supports TLS 1.3 and the Modern profile. The Ingress Operator also converts the TLS 1.0 of an Old or Custom profile to 1.1 . Prerequisites You have access to the cluster as a user with the cluster-admin role. Procedure Edit the IngressController CR in the openshift-ingress-operator project to configure the TLS security profile: USD oc edit IngressController default -n openshift-ingress-operator Add the spec.tlsSecurityProfile field: Sample IngressController CR for a Custom profile apiVersion: operator.openshift.io/v1 kind: IngressController ... spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11 ... 1 Specify the TLS security profile type ( Old , Intermediate , or Custom ). The default is Intermediate . 2 Specify the appropriate field for the selected type: old: {} intermediate: {} custom: 3 For the custom type, specify a list of TLS ciphers and minimum accepted TLS version. Save the file to apply the changes. Verification Verify that the profile is set in the IngressController CR: USD oc describe IngressController default -n openshift-ingress-operator Example output Name: default Namespace: openshift-ingress-operator Labels: <none> Annotations: <none> API Version: operator.openshift.io/v1 Kind: IngressController ... Spec: ... Tls Security Profile: Custom: Ciphers: ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES128-GCM-SHA256 Min TLS Version: VersionTLS11 Type: Custom ... 10.4. Configuring the TLS security profile for the control plane To configure a TLS security profile for the control plane, edit the APIServer custom resource (CR) to specify a predefined or custom TLS security profile. Setting the TLS security profile in the APIServer CR propagates the setting to the following control plane components: Kubernetes API server Kubernetes controller manager Kubernetes scheduler OpenShift API server OpenShift OAuth API server OpenShift OAuth server etcd If a TLS security profile is not configured, the default TLS security profile is Intermediate . Note The default TLS security profile for the Ingress Controller is based on the TLS security profile set for the API server. Sample APIServer CR that configures the Old TLS security profile apiVersion: config.openshift.io/v1 kind: APIServer ... spec: tlsSecurityProfile: old: {} type: Old ... The TLS security profile defines the minimum TLS version and the TLS ciphers required to communicate with the control plane components. You can see the configured TLS security profile in the APIServer custom resource (CR) under Spec.Tls Security Profile . For the Custom TLS security profile, the specific ciphers and minimum TLS version are listed. Note The control plane does not support TLS 1.3 as the minimum TLS version; the Modern profile is not supported because it requires TLS 1.3 . Prerequisites You have access to the cluster as a user with the cluster-admin role. Procedure Edit the default APIServer CR to configure the TLS security profile: USD oc edit APIServer cluster Add the spec.tlsSecurityProfile field: Sample APIServer CR for a Custom profile apiVersion: config.openshift.io/v1 kind: APIServer metadata: name: cluster spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11 1 Specify the TLS security profile type ( Old , Intermediate , or Custom ). The default is Intermediate . 2 Specify the appropriate field for the selected type: old: {} intermediate: {} custom: 3 For the custom type, specify a list of TLS ciphers and minimum accepted TLS version. Save the file to apply the changes. Verification Verify that the TLS security profile is set in the APIServer CR: USD oc describe apiserver cluster Example output Name: cluster Namespace: ... API Version: config.openshift.io/v1 Kind: APIServer ... Spec: Audit: Profile: Default Tls Security Profile: Custom: Ciphers: ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES128-GCM-SHA256 Min TLS Version: VersionTLS11 Type: Custom ... Verify that the TLS security profile is set in the etcd CR: USD oc describe etcd cluster Example output Name: cluster Namespace: ... API Version: operator.openshift.io/v1 Kind: Etcd ... Spec: Log Level: Normal Management State: Managed Observed Config: Serving Info: Cipher Suites: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 Min TLS Version: VersionTLS12 ... 10.5. Configuring the TLS security profile for the kubelet To configure a TLS security profile for the kubelet when it is acting as an HTTP server, create a KubeletConfig custom resource (CR) to specify a predefined or custom TLS security profile for specific nodes. If a TLS security profile is not configured, the default TLS security profile is Intermediate . The kubelet uses its HTTP/GRPC server to communicate with the Kubernetes API server, which sends commands to pods, gathers logs, and run exec commands on pods through the kubelet. Sample KubeletConfig CR that configures the Old TLS security profile on worker nodes apiVersion: config.openshift.io/v1 kind: KubeletConfig ... spec: tlsSecurityProfile: old: {} type: Old machineConfigPoolSelector: matchLabels: pools.operator.machineconfiguration.openshift.io/worker: "" #... You can see the ciphers and the minimum TLS version of the configured TLS security profile in the kubelet.conf file on a configured node. Prerequisites You have access to the cluster as a user with the cluster-admin role. Procedure Create a KubeletConfig CR to configure the TLS security profile: Sample KubeletConfig CR for a Custom profile apiVersion: machineconfiguration.openshift.io/v1 kind: KubeletConfig metadata: name: set-kubelet-tls-security-profile spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11 machineConfigPoolSelector: matchLabels: pools.operator.machineconfiguration.openshift.io/worker: "" 4 #... 1 Specify the TLS security profile type ( Old , Intermediate , or Custom ). The default is Intermediate . 2 Specify the appropriate field for the selected type: old: {} intermediate: {} custom: 3 For the custom type, specify a list of TLS ciphers and minimum accepted TLS version. 4 Optional: Specify the machine config pool label for the nodes you want to apply the TLS security profile. Create the KubeletConfig object: USD oc create -f <filename> Depending on the number of worker nodes in the cluster, wait for the configured nodes to be rebooted one by one. Verification To verify that the profile is set, perform the following steps after the nodes are in the Ready state: Start a debug session for a configured node: USD oc debug node/<node_name> Set /host as the root directory within the debug shell: sh-4.4# chroot /host View the kubelet.conf file: sh-4.4# cat /etc/kubernetes/kubelet.conf Example output "kind": "KubeletConfiguration", "apiVersion": "kubelet.config.k8s.io/v1beta1", #... "tlsCipherSuites": [ "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256", "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256" ], "tlsMinVersion": "VersionTLS12", #...

Commands:
oc explain <component>.spec.tlsSecurityProfile.<profile> 1
oc explain apiserver.spec.tlsSecurityProfile.intermediate
KIND: APIServer VERSION: config.openshift.io/v1 DESCRIPTION: intermediate is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Intermediate_compatibility_.28recommended.29 and looks like this (yaml): ciphers: - TLS_AES_128_GCM_SHA256 - TLS_AES_256_GCM_SHA384 - TLS_CHACHA20_POLY1305_SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES256-GCM-SHA384 - ECDHE-RSA-AES256-GCM-SHA384 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - DHE-RSA-AES128-GCM-SHA256 - DHE-RSA-AES256-GCM-SHA384 minTLSVersion: TLSv1.2
oc explain <component>.spec.tlsSecurityProfile 1
oc explain ingresscontroller.spec.tlsSecurityProfile
KIND: IngressController VERSION: operator.openshift.io/v1 RESOURCE: tlsSecurityProfile <Object> DESCRIPTION: FIELDS: custom <> custom is a user-defined TLS security profile. Be extremely careful using a custom profile as invalid configurations can be catastrophic. An example custom profile looks like this: ciphers: - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: TLSv1.1 intermediate <> intermediate is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Intermediate_compatibility_.28recommended.29 and looks like this (yaml): ... 1 modern <> modern is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Modern_compatibility and looks like this (yaml): ... 2 NOTE: Currently unsupported. old <> old is a TLS security profile based on: https://wiki.mozilla.org/Security/Server_Side_TLS#Old_backward_compatibility and looks like this (yaml): ... 3 type <string>
apiVersion: operator.openshift.io/v1 kind: IngressController spec: tlsSecurityProfile: old: {} type: Old
oc edit IngressController default -n openshift-ingress-operator
apiVersion: operator.openshift.io/v1 kind: IngressController spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11
oc describe IngressController default -n openshift-ingress-operator
Name: default Namespace: openshift-ingress-operator Labels: <none> Annotations: <none> API Version: operator.openshift.io/v1 Kind: IngressController Spec: Tls Security Profile: Custom: Ciphers: ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES128-GCM-SHA256 Min TLS Version: VersionTLS11 Type: Custom
apiVersion: config.openshift.io/v1 kind: APIServer spec: tlsSecurityProfile: old: {} type: Old
oc edit APIServer cluster
apiVersion: config.openshift.io/v1 kind: APIServer metadata: name: cluster spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11
oc describe apiserver cluster
Name: cluster Namespace: API Version: config.openshift.io/v1 Kind: APIServer Spec: Audit: Profile: Default Tls Security Profile: Custom: Ciphers: ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES128-GCM-SHA256 Min TLS Version: VersionTLS11 Type: Custom
oc describe etcd cluster
Name: cluster Namespace: API Version: operator.openshift.io/v1 Kind: Etcd Spec: Log Level: Normal Management State: Managed Observed Config: Serving Info: Cipher Suites: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 Min TLS Version: VersionTLS12
apiVersion: config.openshift.io/v1 kind: KubeletConfig spec: tlsSecurityProfile: old: {} type: Old machineConfigPoolSelector: matchLabels: pools.operator.machineconfiguration.openshift.io/worker: "" #
apiVersion: machineconfiguration.openshift.io/v1 kind: KubeletConfig metadata: name: set-kubelet-tls-security-profile spec: tlsSecurityProfile: type: Custom 1 custom: 2 ciphers: 3 - ECDHE-ECDSA-CHACHA20-POLY1305 - ECDHE-RSA-CHACHA20-POLY1305 - ECDHE-RSA-AES128-GCM-SHA256 - ECDHE-ECDSA-AES128-GCM-SHA256 minTLSVersion: VersionTLS11 machineConfigPoolSelector: matchLabels: pools.operator.machineconfiguration.openshift.io/worker: "" 4 #
oc create -f <filename>
oc debug node/<node_name>
sh-4.4# chroot /host
sh-4.4# cat /etc/kubernetes/kubelet.conf
"kind": "KubeletConfiguration", "apiVersion": "kubelet.config.k8s.io/v1beta1", # "tlsCipherSuites": [ "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256", "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256" ], "tlsMinVersion": "VersionTLS12", #