1.4. Container image signatures

PDF

Red Hat delivers signatures for the images in the Red Hat Container Registries. Those signatures can be automatically verified when being pulled to OpenShift Container Platform 4 clusters by using the Machine Config Operator (MCO).

Quay.io serves most of the images that make up OpenShift Container Platform, and only the release image is signed. Release images refer to the approved OpenShift Container Platform images, offering a degree of protection against supply chain attacks. However, some extensions to OpenShift Container Platform, such as logging, monitoring, and service mesh, are shipped as Operators from the Operator Lifecycle Manager (OLM). Those images ship from the Red Hat Ecosystem Catalog Container images registry.

To verify the integrity of those images between Red Hat registries and your infrastructure, enable signature verification.

1.4.1. Enabling signature verification for Red Hat Container Registries

Enabling container signature validation requires files that link the registry URLs to the sigstore and then specifies the keys which verify the images.

Procedure

Create the files that link the registry URLs to the sigstore and that specifies the key to verify the image.

Create the policy.json file:

$ cat > policy.json <<EOF
{
  "default": [
    {
      "type": "insecureAcceptAnything"
    }
  ],
  "transports": {
    "docker": {
      "registry.access.redhat.com": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ],
      "registry.redhat.io": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ]
    },
    "docker-daemon": {
      "": [
        {
          "type": "insecureAcceptAnything"
        }
      ]
    }
  }
}
EOF

Create the registry.access.redhat.com.yaml file:

$ cat <<EOF > registry.access.redhat.com.yaml
docker:
     registry.access.redhat.com:
         sigstore: https://access.redhat.com/webassets/docker/content/sigstore
EOF

Create the registry.redhat.io.yaml file:

$ cat <<EOF > registry.redhat.io.yaml
docker:
     registry.redhat.io:
         sigstore: https://registry.redhat.io/containers/sigstore
EOF

Set the files with a base64 encode format that will be used for the machine config template:

$ export ARC_REG=$( cat registry.access.redhat.com.yaml | base64 -w0 )
$ export RIO_REG=$( cat registry.redhat.io.yaml | base64 -w0 )
$ export POLICY_CONFIG=$( cat policy.json | base64 -w0 )

Create a machine config that writes the exported files to disk on the worker nodes:

$ cat > 51-worker-rh-registry-trust.yaml <<EOF
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 51-worker-rh-registry-trust
spec:
  config:
    ignition:
      config: {}
      security:
        tls: {}
      timeouts: {}
      version: 2.2.0
    networkd: {}
    passwd: {}
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,${ARC_REG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/registries.d/registry.access.redhat.com.yaml
      - contents:
          source: data:text/plain;charset=utf-8;base64,${RIO_REG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/registries.d/registry.redhat.io.yaml
      - contents:
          source: data:text/plain;charset=utf-8;base64,${POLICY_CONFIG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/policy.json
  osImageURL: ""
EOF

Apply the created machine config:

$ oc apply -f 51-worker-rh-registry-trust.yaml

Create a machine config, which writes the exported files to disk on the master nodes:

$ cat > 51-master-rh-registry-trust.yaml <<EOF
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 51-master-rh-registry-trust
spec:
  config:
    ignition:
      config: {}
      security:
        tls: {}
      timeouts: {}
      version: 2.2.0
    networkd: {}
    passwd: {}
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,${ARC_REG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/registries.d/registry.access.redhat.com.yaml
      - contents:
          source: data:text/plain;charset=utf-8;base64,${RIO_REG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/registries.d/registry.redhat.io.yaml
      - contents:
          source: data:text/plain;charset=utf-8;base64,${POLICY_CONFIG}
          verification: {}
        filesystem: root
        mode: 420
        path: /etc/containers/policy.json
  osImageURL: ""
EOF

Apply the master machine config changes to the cluster:
```
$ oc apply -f 51-master-rh-registry-trust.yaml
```

1.4.2. Verifying the signature verification configuration

After you apply the machine configs to the cluster, the Machine Config Controller detects the new MachineConfig object and generates a new rendered-worker-<hash> version.

Prerequisites

You enabled signature verification by using a machine config file.

Procedure

On the command line, run the following command to display information about a desired worker:

$ oc describe machineconfigpool/worker

Name:         worker
Namespace:
Labels:       machineconfiguration.openshift.io/mco-built-in=
Annotations:  <none>
API Version:  machineconfiguration.openshift.io/v1
Kind:         MachineConfigPool
Metadata:
  Creation Timestamp:  2019-12-19T02:02:12Z
  Generation:          3
  Resource Version:    16229
  Self Link:           /apis/machineconfiguration.openshift.io/v1/machineconfigpools/worker
  UID:                 92697796-2203-11ea-b48c-fa163e3940e5
Spec:
  Configuration:
    Name:  rendered-worker-f6819366eb455a401c42f8d96ab25c02
    Source:
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         00-worker
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         01-worker-container-runtime
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         01-worker-kubelet
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         51-worker-rh-registry-trust
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         99-worker-92697796-2203-11ea-b48c-fa163e3940e5-registries
      API Version:  machineconfiguration.openshift.io/v1
      Kind:         MachineConfig
      Name:         99-worker-ssh
  Machine Config Selector:
    Match Labels:
      machineconfiguration.openshift.io/role:  worker
  Node Selector:
    Match Labels:
      node-role.kubernetes.io/worker:
  Paused:                              false
Status:
  Conditions:
    Last Transition Time:  2019-12-19T02:03:27Z
    Message:
    Reason:
    Status:                False
    Type:                  RenderDegraded
    Last Transition Time:  2019-12-19T02:03:43Z
    Message:
    Reason:
    Status:                False
    Type:                  NodeDegraded
    Last Transition Time:  2019-12-19T02:03:43Z
    Message:
    Reason:
    Status:                False
    Type:                  Degraded
    Last Transition Time:  2019-12-19T02:28:23Z
    Message:
    Reason:
    Status:                False
    Type:                  Updated
    Last Transition Time:  2019-12-19T02:28:23Z
    Message:               All nodes are updating to rendered-worker-f6819366eb455a401c42f8d96ab25c02
    Reason:
    Status:                True
    Type:                  Updating
  Configuration:
    Name:  rendered-worker-d9b3f4ffcfd65c30dcf591a0e8cf9b2e
    Source:
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   00-worker
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   01-worker-container-runtime
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   01-worker-kubelet
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   99-worker-92697796-2203-11ea-b48c-fa163e3940e5-registries
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   99-worker-ssh
  Degraded Machine Count:     0
  Machine Count:              1
  Observed Generation:        3
  Ready Machine Count:        0
  Unavailable Machine Count:  1
  Updated Machine Count:      0
Events:                       <none>

Run the oc describe command again:

$ oc describe machineconfigpool/worker

...
    Last Transition Time:  2019-12-19T04:53:09Z
    Message:               All nodes are updated with rendered-worker-f6819366eb455a401c42f8d96ab25c02
    Reason:
    Status:                True
    Type:                  Updated
    Last Transition Time:  2019-12-19T04:53:09Z
    Message:
    Reason:
    Status:                False
    Type:                  Updating
  Configuration:
    Name:  rendered-worker-f6819366eb455a401c42f8d96ab25c02
    Source:
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   00-worker
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   01-worker-container-runtime
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   01-worker-kubelet
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   51-worker-rh-registry-trust
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   99-worker-92697796-2203-11ea-b48c-fa163e3940e5-registries
      API Version:            machineconfiguration.openshift.io/v1
      Kind:                   MachineConfig
      Name:                   99-worker-ssh
  Degraded Machine Count:     0
  Machine Count:              3
  Observed Generation:        4
  Ready Machine Count:        3
  Unavailable Machine Count:  0
  Updated Machine Count:      3
...

注意

The Observed Generation parameter shows an increased count based on the generation of the controller-produced configuration. This controller updates this value even if it fails to process the specification and generate a revision. The Configuration Source value points to the 51-worker-rh-registry-trust configuration.

Confirm that the policy.json file exists with the following command:

$ oc debug node/<node> -- chroot /host cat /etc/containers/policy.json

Starting pod/<node>-debug ...
To use host binaries, run `chroot /host`
{
  "default": [
    {
      "type": "insecureAcceptAnything"
    }
  ],
  "transports": {
    "docker": {
      "registry.access.redhat.com": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ],
      "registry.redhat.io": [
        {
          "type": "signedBy",
          "keyType": "GPGKeys",
          "keyPath": "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"
        }
      ]
    },
    "docker-daemon": {
      "": [
        {
          "type": "insecureAcceptAnything"
        }
      ]
    }
  }
}

Confirm that the registry.redhat.io.yaml file exists with the following command:

$ oc debug node/<node> -- chroot /host cat /etc/containers/registries.d/registry.redhat.io.yaml

Starting pod/<node>-debug ...
To use host binaries, run `chroot /host`
docker:
     registry.redhat.io:
         sigstore: https://registry.redhat.io/containers/sigstore

Confirm that the registry.access.redhat.com.yaml file exists with the following command:

$ oc debug node/<node> -- chroot /host cat /etc/containers/registries.d/registry.access.redhat.com.yaml

Starting pod/<node>-debug ...
To use host binaries, run `chroot /host`
docker:
     registry.access.redhat.com:
         sigstore: https://access.redhat.com/webassets/docker/content/sigstore

1.4. Container image signatures

1.4.1. Enabling signature verification for Red Hat Container Registries

1.4.2. Verifying the signature verification configuration

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