This is the multi-page printable view of this section. Click here to print.

Return to the regular view of this page.

Security

1: Apply Pod Security Standards at the Cluster Level
2: Apply Pod Security Standards at the Namespace Level
3: Restrict a Container's Access to Resources with AppArmor
4: Restrict a Container's Syscalls with seccomp

1 - Apply Pod Security Standards at the Cluster Level

Note

This tutorial applies only for new clusters.

Pod Security admission (PSA) is enabled by default in v1.23 and later, as it has graduated to beta. Pod Security is an admission controller that carries out checks against the Kubernetes Pod Security Standards when new pods are created. This tutorial shows you how to enforce the baseline Pod Security Standard at the cluster level which applies a standard configuration to all namespaces in a cluster.

To apply Pod Security Standards to specific namespaces, refer to Apply Pod Security Standards at the namespace level.

If you are running a version of Kubernetes other than v1.25, check the documentation for that version.

Before you begin

Install the following on your workstation:

KinD
kubectl

Choose the right Pod Security Standard to apply

Pod Security Admission lets you apply built-in Pod Security Standards with the following modes: enforce, audit, and warn.

To gather information that helps you to choose the Pod Security Standards that are most appropriate for your configuration, do the following:

Create a cluster with no Pod Security Standards applied:

kind create cluster --name psa-wo-cluster-pss --image kindest/node:v1.24.0

The output is similar to this:

Creating cluster "psa-wo-cluster-pss" ...
✓ Ensuring node image (kindest/node:v1.24.0) 🖼
✓ Preparing nodes 📦  
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
Set kubectl context to "kind-psa-wo-cluster-pss"
You can now use your cluster with:

kubectl cluster-info --context kind-psa-wo-cluster-pss

Thanks for using kind! 😊

Set the kubectl context to the new cluster:

kubectl cluster-info --context kind-psa-wo-cluster-pss

The output is similar to this:

 Kubernetes control plane is running at https://127.0.0.1:61350

CoreDNS is running at https://127.0.0.1:61350/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Get a list of namespaces in the cluster:

kubectl get ns

The output is similar to this:

NAME                 STATUS   AGE
default              Active   9m30s
kube-node-lease      Active   9m32s
kube-public          Active   9m32s
kube-system          Active   9m32s
local-path-storage   Active   9m26s

Use --dry-run=server to understand what happens when different Pod Security Standards are applied:

Privileged

kubectl label --dry-run=server --overwrite ns --all \
pod-security.kubernetes.io/enforce=privileged

The output is similar to this:

namespace/default labeled
namespace/kube-node-lease labeled
namespace/kube-public labeled
namespace/kube-system labeled
namespace/local-path-storage labeled

Baseline

kubectl label --dry-run=server --overwrite ns --all \
pod-security.kubernetes.io/enforce=baseline

The output is similar to this:

namespace/default labeled
namespace/kube-node-lease labeled
namespace/kube-public labeled
Warning: existing pods in namespace "kube-system" violate the new PodSecurity enforce level "baseline:latest"
Warning: etcd-psa-wo-cluster-pss-control-plane (and 3 other pods): host namespaces, hostPath volumes
Warning: kindnet-vzj42: non-default capabilities, host namespaces, hostPath volumes
Warning: kube-proxy-m6hwf: host namespaces, hostPath volumes, privileged
namespace/kube-system labeled
namespace/local-path-storage labeled

Restricted

 kubectl label --dry-run=server --overwrite ns --all \
 pod-security.kubernetes.io/enforce=restricted

The output is similar to this:

namespace/default labeled
namespace/kube-node-lease labeled
namespace/kube-public labeled
Warning: existing pods in namespace "kube-system" violate the new PodSecurity enforce level "restricted:latest"
Warning: coredns-7bb9c7b568-hsptc (and 1 other pod): unrestricted capabilities, runAsNonRoot != true, seccompProfile
Warning: etcd-psa-wo-cluster-pss-control-plane (and 3 other pods): host namespaces, hostPath volumes, allowPrivilegeEscalation != false, unrestricted capabilities, restricted volume types, runAsNonRoot != true
Warning: kindnet-vzj42: non-default capabilities, host namespaces, hostPath volumes, allowPrivilegeEscalation != false, unrestricted capabilities, restricted volume types, runAsNonRoot != true, seccompProfile
Warning: kube-proxy-m6hwf: host namespaces, hostPath volumes, privileged, allowPrivilegeEscalation != false, unrestricted capabilities, restricted volume types, runAsNonRoot != true, seccompProfile
namespace/kube-system labeled
Warning: existing pods in namespace "local-path-storage" violate the new PodSecurity enforce level "restricted:latest"
Warning: local-path-provisioner-d6d9f7ffc-lw9lh: allowPrivilegeEscalation != false, unrestricted capabilities, runAsNonRoot != true, seccompProfile
namespace/local-path-storage labeled

From the previous output, you'll notice that applying the privileged Pod Security Standard shows no warnings for any namespaces. However, baseline and restricted standards both have warnings, specifically in the kube-system namespace.

Set modes, versions and standards

In this section, you apply the following Pod Security Standards to the latest version:

baseline standard in enforce mode.
restricted standard in warn and audit mode.

The baseline Pod Security Standard provides a convenient middle ground that allows keeping the exemption list short and prevents known privilege escalations.

Additionally, to prevent pods from failing in kube-system, you'll exempt the namespace from having Pod Security Standards applied.

When you implement Pod Security Admission in your own environment, consider the following:

Based on the risk posture applied to a cluster, a stricter Pod Security Standard like restricted might be a better choice.
Exempting the kube-system namespace allows pods to run as privileged in this namespace. For real world use, the Kubernetes project strongly recommends that you apply strict RBAC policies that limit access to kube-system, following the principle of least privilege. To implement the preceding standards, do the following:

Create a configuration file that can be consumed by the Pod Security Admission Controller to implement these Pod Security Standards:

mkdir -p /tmp/pss
cat <<EOF > /tmp/pss/cluster-level-pss.yaml 
apiVersion: apiserver.config.k8s.io/v1
kind: AdmissionConfiguration
plugins:
- name: PodSecurity
  configuration:
    apiVersion: pod-security.admission.config.k8s.io/v1
    kind: PodSecurityConfiguration
    defaults:
      enforce: "baseline"
      enforce-version: "latest"
      audit: "restricted"
      audit-version: "latest"
      warn: "restricted"
      warn-version: "latest"
    exemptions:
      usernames: []
      runtimeClasses: []
      namespaces: [kube-system]
EOF

Note: pod-security.admission.config.k8s.io/v1 configuration requires v1.25+. For v1.23 and v1.24, use v1beta1. For v1.22, use v1alpha1.

Configure the API server to consume this file during cluster creation:

cat <<EOF > /tmp/pss/cluster-config.yaml 
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
  kubeadmConfigPatches:
  - |
    kind: ClusterConfiguration
    apiServer:
        extraArgs:
          admission-control-config-file: /etc/config/cluster-level-pss.yaml
        extraVolumes:
          - name: accf
            hostPath: /etc/config
            mountPath: /etc/config
            readOnly: false
            pathType: "DirectoryOrCreate"
  extraMounts:
  - hostPath: /tmp/pss
    containerPath: /etc/config
    # optional: if set, the mount is read-only.
    # default false
    readOnly: false
    # optional: if set, the mount needs SELinux relabeling.
    # default false
    selinuxRelabel: false
    # optional: set propagation mode (None, HostToContainer or Bidirectional)
    # see https://kubernetes.io/docs/concepts/storage/volumes/#mount-propagation
    # default None
    propagation: None
EOF

Note: If you use Docker Desktop with KinD on macOS, you can add /tmp as a Shared Directory under the menu item Preferences > Resources > File Sharing.

Create a cluster that uses Pod Security Admission to apply these Pod Security Standards:

 kind create cluster --name psa-with-cluster-pss --image kindest/node:v1.24.0 --config /tmp/pss/cluster-config.yaml

The output is similar to this:

 Creating cluster "psa-with-cluster-pss" ...
  ✓ Ensuring node image (kindest/node:v1.24.0) 🖼 
  ✓ Preparing nodes 📦  
  ✓ Writing configuration 📜 
  ✓ Starting control-plane 🕹️ 
  ✓ Installing CNI 🔌 
  ✓ Installing StorageClass 💾 
 Set kubectl context to "kind-psa-with-cluster-pss"
 You can now use your cluster with:

 kubectl cluster-info --context kind-psa-with-cluster-pss

 Have a question, bug, or feature request? Let us know! https://kind.sigs.k8s.io/#community 🙂

Point kubectl to the cluster

 kubectl cluster-info --context kind-psa-with-cluster-pss

The output is similar to this:

 Kubernetes control plane is running at https://127.0.0.1:63855
 CoreDNS is running at https://127.0.0.1:63855/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

 To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Create the following Pod specification for a minimal configuration in the default namespace:

cat <<EOF > /tmp/pss/nginx-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - image: nginx
      name: nginx
      ports:
        - containerPort: 80
EOF

Create the Pod in the cluster:

 kubectl apply -f /tmp/pss/nginx-pod.yaml

The output is similar to this:

 Warning: would violate PodSecurity "restricted:latest": allowPrivilegeEscalation != false (container "nginx" must set securityContext.allowPrivilegeEscalation=false), unrestricted capabilities (container "nginx" must set securityContext.capabilities.drop=["ALL"]), runAsNonRoot != true (pod or container "nginx" must set securityContext.runAsNonRoot=true), seccompProfile (pod or container "nginx" must set securityContext.seccompProfile.type to "RuntimeDefault" or "Localhost")
 pod/nginx created

Clean up

Run kind delete cluster --name psa-with-cluster-pss and kind delete cluster --name psa-wo-cluster-pss to delete the clusters you created.

What's next

Run a shell script to perform all the preceding steps at once:
1. Create a Pod Security Standards based cluster level Configuration
2. Create a file to let API server consume this configuration
3. Create a cluster that creates an API server with this configuration
4. Set kubectl context to this new cluster
5. Create a minimal pod yaml file
6. Apply this file to create a Pod in the new cluster
Pod Security Admission
Pod Security Standards
Apply Pod Security Standards at the namespace level

2 - Apply Pod Security Standards at the Namespace Level

Note

This tutorial applies only for new clusters.

Pod Security admission (PSA) is enabled by default in v1.23 and later, as it graduated to beta. Pod Security Admission is an admission controller that applies Pod Security Standards when pods are created. In this tutorial, you will enforce the baseline Pod Security Standard, one namespace at a time.

You can also apply Pod Security Standards to multiple namespaces at once at the cluster level. For instructions, refer to Apply Pod Security Standards at the cluster level.

Before you begin

Install the following on your workstation:

KinD
kubectl

Create cluster

Create a KinD cluster as follows:

kind create cluster --name psa-ns-level --image kindest/node:v1.23.0

The output is similar to this:

Creating cluster "psa-ns-level" ...
 ✓ Ensuring node image (kindest/node:v1.23.0) 🖼 
 ✓ Preparing nodes 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Set kubectl context to "kind-psa-ns-level"
You can now use your cluster with:

kubectl cluster-info --context kind-psa-ns-level

Not sure what to do next? 😅  Check out https://kind.sigs.k8s.io/docs/user/quick-start/

Set the kubectl context to the new cluster:

kubectl cluster-info --context kind-psa-ns-level

The output is similar to this:

Kubernetes control plane is running at https://127.0.0.1:50996
CoreDNS is running at https://127.0.0.1:50996/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Create a namespace

Create a new namespace called example:

kubectl create ns example

The output is similar to this:

namespace/example created

Apply Pod Security Standards

Enable Pod Security Standards on this namespace using labels supported by built-in Pod Security Admission. In this step we will warn on baseline pod security standard as per the latest version (default value)
```
kubectl label --overwrite ns example \
   pod-security.kubernetes.io/warn=baseline \
   pod-security.kubernetes.io/warn-version=latest
```

Multiple pod security standards can be enabled on any namespace, using labels. Following command will enforce the baseline Pod Security Standard, but warn and audit for restricted Pod Security Standards as per the latest version (default value)

kubectl label --overwrite ns example \
  pod-security.kubernetes.io/enforce=baseline \
  pod-security.kubernetes.io/enforce-version=latest \
  pod-security.kubernetes.io/warn=restricted \
  pod-security.kubernetes.io/warn-version=latest \
  pod-security.kubernetes.io/audit=restricted \
  pod-security.kubernetes.io/audit-version=latest

Verify the Pod Security Standards

Create a minimal pod in example namespace:

cat <<EOF > /tmp/pss/nginx-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - image: nginx
      name: nginx
      ports:
        - containerPort: 80
EOF

Apply the pod spec to the cluster in example namespace:

kubectl apply -n example -f /tmp/pss/nginx-pod.yaml

The output is similar to this:

Warning: would violate PodSecurity "restricted:latest": allowPrivilegeEscalation != false (container "nginx" must set securityContext.allowPrivilegeEscalation=false), unrestricted capabilities (container "nginx" must set securityContext.capabilities.drop=["ALL"]), runAsNonRoot != true (pod or container "nginx" must set securityContext.runAsNonRoot=true), seccompProfile (pod or container "nginx" must set securityContext.seccompProfile.type to "RuntimeDefault" or "Localhost")
pod/nginx created

Apply the pod spec to the cluster in default namespace:
```
kubectl apply -n default -f /tmp/pss/nginx-pod.yaml
```
Output is similar to this:
```
pod/nginx created
```

The Pod Security Standards were applied only to the example namespace. You could create the same Pod in the default namespace with no warnings.

Clean up

Run kind delete cluster --name psa-ns-level to delete the cluster created.

What's next

Run a shell script to perform all the preceding steps all at once.
1. Create KinD cluster
2. Create new namespace
3. Apply baseline Pod Security Standard in enforce mode while applying restricted Pod Security Standard also in warn and audit mode.
4. Create a new pod with the following pod security standards applied
Pod Security Admission
Pod Security Standards
Apply Pod Security Standards at the cluster level

3 - Restrict a Container's Access to Resources with AppArmor

FEATURE STATE: Kubernetes v1.4 [beta]

AppArmor is a Linux kernel security module that supplements the standard Linux user and group based permissions to confine programs to a limited set of resources. AppArmor can be configured for any application to reduce its potential attack surface and provide greater in-depth defense. It is configured through profiles tuned to allow the access needed by a specific program or container, such as Linux capabilities, network access, file permissions, etc. Each profile can be run in either enforcing mode, which blocks access to disallowed resources, or complain mode, which only reports violations.

AppArmor can help you to run a more secure deployment by restricting what containers are allowed to do, and/or provide better auditing through system logs. However, it is important to keep in mind that AppArmor is not a silver bullet and can only do so much to protect against exploits in your application code. It is important to provide good, restrictive profiles, and harden your applications and cluster from other angles as well.

Objectives

See an example of how to load a profile on a node
Learn how to enforce the profile on a Pod
Learn how to check that the profile is loaded
See what happens when a profile is violated
See what happens when a profile cannot be loaded

Before you begin

Make sure:

Kubernetes version is at least v1.4 -- Kubernetes support for AppArmor was added in v1.4. Kubernetes components older than v1.4 are not aware of the new AppArmor annotations, and will silently ignore any AppArmor settings that are provided. To ensure that your Pods are receiving the expected protections, it is important to verify the Kubelet version of your nodes:
```
kubectl get nodes -o=jsonpath=$'{range .items[*]}{@.metadata.name}: {@.status.nodeInfo.kubeletVersion}\n{end}'
```
```
gke-test-default-pool-239f5d02-gyn2: v1.4.0
gke-test-default-pool-239f5d02-x1kf: v1.4.0
gke-test-default-pool-239f5d02-xwux: v1.4.0
```
AppArmor kernel module is enabled -- For the Linux kernel to enforce an AppArmor profile, the AppArmor kernel module must be installed and enabled. Several distributions enable the module by default, such as Ubuntu and SUSE, and many others provide optional support. To check whether the module is enabled, check the /sys/module/apparmor/parameters/enabled file:
```
cat /sys/module/apparmor/parameters/enabled
Y
```
If the Kubelet contains AppArmor support (>= v1.4), it will refuse to run a Pod with AppArmor options if the kernel module is not enabled.

Note: Ubuntu carries many AppArmor patches that have not been merged into the upstream Linux kernel, including patches that add additional hooks and features. Kubernetes has only been tested with the upstream version, and does not promise support for other features.

Container runtime supports AppArmor -- Currently all common Kubernetes-supported container runtimes should support AppArmor, like Docker, CRI-O or containerd. Please refer to the corresponding runtime documentation and verify that the cluster fulfills the requirements to use AppArmor.
Profile is loaded -- AppArmor is applied to a Pod by specifying an AppArmor profile that each container should be run with. If any of the specified profiles is not already loaded in the kernel, the Kubelet (>= v1.4) will reject the Pod. You can view which profiles are loaded on a node by checking the /sys/kernel/security/apparmor/profiles file. For example:
```
ssh gke-test-default-pool-239f5d02-gyn2 "sudo cat /sys/kernel/security/apparmor/profiles | sort"
```
```
apparmor-test-deny-write (enforce)
apparmor-test-audit-write (enforce)
docker-default (enforce)
k8s-nginx (enforce)
```
For more details on loading profiles on nodes, see Setting up nodes with profiles.

As long as the Kubelet version includes AppArmor support (>= v1.4), the Kubelet will reject a Pod with AppArmor options if any of the prerequisites are not met. You can also verify AppArmor support on nodes by checking the node ready condition message (though this is likely to be removed in a later release):

kubectl get nodes -o=jsonpath='{range .items[*]}{@.metadata.name}: {.status.conditions[?(@.reason=="KubeletReady")].message}{"\n"}{end}'

gke-test-default-pool-239f5d02-gyn2: kubelet is posting ready status. AppArmor enabled
gke-test-default-pool-239f5d02-x1kf: kubelet is posting ready status. AppArmor enabled
gke-test-default-pool-239f5d02-xwux: kubelet is posting ready status. AppArmor enabled

Securing a Pod

Note: AppArmor is currently in beta, so options are specified as annotations. Once support graduates to general availability, the annotations will be replaced with first-class fields (more details in Upgrade path to GA).

AppArmor profiles are specified per-container. To specify the AppArmor profile to run a Pod container with, add an annotation to the Pod's metadata:

container.apparmor.security.beta.kubernetes.io/<container_name>: <profile_ref>

Where <container_name> is the name of the container to apply the profile to, and <profile_ref> specifies the profile to apply. The profile_ref can be one of:

runtime/default to apply the runtime's default profile
localhost/<profile_name> to apply the profile loaded on the host with the name <profile_name>
unconfined to indicate that no profiles will be loaded

See the API Reference for the full details on the annotation and profile name formats.

Kubernetes AppArmor enforcement works by first checking that all the prerequisites have been met, and then forwarding the profile selection to the container runtime for enforcement. If the prerequisites have not been met, the Pod will be rejected, and will not run.

To verify that the profile was applied, you can look for the AppArmor security option listed in the container created event:

kubectl get events | grep Created

22s        22s         1         hello-apparmor     Pod       spec.containers{hello}   Normal    Created     {kubelet e2e-test-stclair-node-pool-31nt}   Created container with docker id 269a53b202d3; Security:[seccomp=unconfined apparmor=k8s-apparmor-example-deny-write]

You can also verify directly that the container's root process is running with the correct profile by checking its proc attr:

kubectl exec <pod_name> -- cat /proc/1/attr/current

k8s-apparmor-example-deny-write (enforce)

Example

This example assumes you have already set up a cluster with AppArmor support.

First, we need to load the profile we want to use onto our nodes. This profile denies all file writes:

#include <tunables/global>

profile k8s-apparmor-example-deny-write flags=(attach_disconnected) {
  #include <abstractions/base>

  file,

  # Deny all file writes.
  deny /** w,
}

Since we don't know where the Pod will be scheduled, we'll need to load the profile on all our nodes. For this example we'll use SSH to install the profiles, but other approaches are discussed in Setting up nodes with profiles.

NODES=(
    # The SSH-accessible domain names of your nodes
    gke-test-default-pool-239f5d02-gyn2.us-central1-a.my-k8s
    gke-test-default-pool-239f5d02-x1kf.us-central1-a.my-k8s
    gke-test-default-pool-239f5d02-xwux.us-central1-a.my-k8s)
for NODE in ${NODES[*]}; do ssh $NODE 'sudo apparmor_parser -q <<EOF
#include <tunables/global>

profile k8s-apparmor-example-deny-write flags=(attach_disconnected) {
  #include <abstractions/base>

  file,

  # Deny all file writes.
  deny /** w,
}
EOF'
done

Next, we'll run a simple "Hello AppArmor" pod with the deny-write profile:

pods/security/hello-apparmor.yaml

apiVersion: v1
kind: Pod
metadata:
  name: hello-apparmor
  annotations:
    # Tell Kubernetes to apply the AppArmor profile "k8s-apparmor-example-deny-write".
    # Note that this is ignored if the Kubernetes node is not running version 1.4 or greater.
    container.apparmor.security.beta.kubernetes.io/hello: localhost/k8s-apparmor-example-deny-write
spec:
  containers:
  - name: hello
    image: busybox:1.28
    command: [ "sh", "-c", "echo 'Hello AppArmor!' && sleep 1h" ]

kubectl create -f ./hello-apparmor.yaml

If we look at the pod events, we can see that the Pod container was created with the AppArmor profile "k8s-apparmor-example-deny-write":

kubectl get events | grep hello-apparmor

14s        14s         1         hello-apparmor   Pod                                Normal    Scheduled   {default-scheduler }                           Successfully assigned hello-apparmor to gke-test-default-pool-239f5d02-gyn2
14s        14s         1         hello-apparmor   Pod       spec.containers{hello}   Normal    Pulling     {kubelet gke-test-default-pool-239f5d02-gyn2}   pulling image "busybox"
13s        13s         1         hello-apparmor   Pod       spec.containers{hello}   Normal    Pulled      {kubelet gke-test-default-pool-239f5d02-gyn2}   Successfully pulled image "busybox"
13s        13s         1         hello-apparmor   Pod       spec.containers{hello}   Normal    Created     {kubelet gke-test-default-pool-239f5d02-gyn2}   Created container with docker id 06b6cd1c0989; Security:[seccomp=unconfined apparmor=k8s-apparmor-example-deny-write]
13s        13s         1         hello-apparmor   Pod       spec.containers{hello}   Normal    Started     {kubelet gke-test-default-pool-239f5d02-gyn2}   Started container with docker id 06b6cd1c0989

We can verify that the container is actually running with that profile by checking its proc attr:

kubectl exec hello-apparmor -- cat /proc/1/attr/current

k8s-apparmor-example-deny-write (enforce)

Finally, we can see what happens if we try to violate the profile by writing to a file:

kubectl exec hello-apparmor -- touch /tmp/test

touch: /tmp/test: Permission denied
error: error executing remote command: command terminated with non-zero exit code: Error executing in Docker Container: 1

To wrap up, let's look at what happens if we try to specify a profile that hasn't been loaded:

kubectl create -f /dev/stdin <<EOF

apiVersion: v1
kind: Pod
metadata:
  name: hello-apparmor-2
  annotations:
    container.apparmor.security.beta.kubernetes.io/hello: localhost/k8s-apparmor-example-allow-write
spec:
  containers:
  - name: hello
    image: busybox:1.28
    command: [ "sh", "-c", "echo 'Hello AppArmor!' && sleep 1h" ]
EOF
pod/hello-apparmor-2 created

kubectl describe pod hello-apparmor-2

Name:          hello-apparmor-2
Namespace:     default
Node:          gke-test-default-pool-239f5d02-x1kf/
Start Time:    Tue, 30 Aug 2016 17:58:56 -0700
Labels:        <none>
Annotations:   container.apparmor.security.beta.kubernetes.io/hello=localhost/k8s-apparmor-example-allow-write
Status:        Pending
Reason:        AppArmor
Message:       Pod Cannot enforce AppArmor: profile "k8s-apparmor-example-allow-write" is not loaded
IP:
Controllers:   <none>
Containers:
  hello:
    Container ID:
    Image:     busybox
    Image ID:
    Port:
    Command:
      sh
      -c
      echo 'Hello AppArmor!' && sleep 1h
    State:              Waiting
      Reason:           Blocked
    Ready:              False
    Restart Count:      0
    Environment:        <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-dnz7v (ro)
Conditions:
  Type          Status
  Initialized   True
  Ready         False
  PodScheduled  True
Volumes:
  default-token-dnz7v:
    Type:    Secret (a volume populated by a Secret)
    SecretName:    default-token-dnz7v
    Optional:   false
QoS Class:      BestEffort
Node-Selectors: <none>
Tolerations:    <none>
Events:
  FirstSeen    LastSeen    Count    From                        SubobjectPath    Type        Reason        Message
  ---------    --------    -----    ----                        -------------    --------    ------        -------
  23s          23s         1        {default-scheduler }                         Normal      Scheduled     Successfully assigned hello-apparmor-2 to e2e-test-stclair-node-pool-t1f5
  23s          23s         1        {kubelet e2e-test-stclair-node-pool-t1f5}             Warning        AppArmor    Cannot enforce AppArmor: profile "k8s-apparmor-example-allow-write" is not loaded

Note the pod status is Pending, with a helpful error message: Pod Cannot enforce AppArmor: profile "k8s-apparmor-example-allow-write" is not loaded. An event was also recorded with the same message.

Administration

Setting up nodes with profiles

Kubernetes does not currently provide any native mechanisms for loading AppArmor profiles onto nodes. There are lots of ways to set up the profiles though, such as:

Through a DaemonSet that runs a Pod on each node to ensure the correct profiles are loaded. An example implementation can be found here.
At node initialization time, using your node initialization scripts (e.g. Salt, Ansible, etc.) or image.
By copying the profiles to each node and loading them through SSH, as demonstrated in the Example.

The scheduler is not aware of which profiles are loaded onto which node, so the full set of profiles must be loaded onto every node. An alternative approach is to add a node label for each profile (or class of profiles) on the node, and use a node selector to ensure the Pod is run on a node with the required profile.

Disabling AppArmor

If you do not want AppArmor to be available on your cluster, it can be disabled by a command-line flag:

--feature-gates=AppArmor=false

When disabled, any Pod that includes an AppArmor profile will fail validation with a "Forbidden" error.

Note: Even if the Kubernetes feature is disabled, runtimes may still enforce the default profile. The option to disable the AppArmor feature will be removed when AppArmor graduates to general availability (GA).

Authoring Profiles

Getting AppArmor profiles specified correctly can be a tricky business. Fortunately there are some tools to help with that:

aa-genprof and aa-logprof generate profile rules by monitoring an application's activity and logs, and admitting the actions it takes. Further instructions are provided by the AppArmor documentation.
bane is an AppArmor profile generator for Docker that uses a simplified profile language.

To debug problems with AppArmor, you can check the system logs to see what, specifically, was denied. AppArmor logs verbose messages to dmesg, and errors can usually be found in the system logs or through journalctl. More information is provided in AppArmor failures.

API Reference

Pod Annotation

Specifying the profile a container will run with:

key: container.apparmor.security.beta.kubernetes.io/<container_name> Where <container_name> matches the name of a container in the Pod. A separate profile can be specified for each container in the Pod.
value: a profile reference, described below

Profile Reference

runtime/default: Refers to the default runtime profile.
- Equivalent to not specifying a profile, except it still requires AppArmor to be enabled.
- In practice, many container runtimes use the same OCI default profile, defined here: https://github.com/containers/common/blob/main/pkg/apparmor/apparmor_linux_template.go
localhost/<profile_name>: Refers to a profile loaded on the node (localhost) by name.
- The possible profile names are detailed in the core policy reference.
unconfined: This effectively disables AppArmor on the container.

Any other profile reference format is invalid.

What's next

Additional resources:

4 - Restrict a Container's Syscalls with seccomp

FEATURE STATE: Kubernetes v1.19 [stable]

Seccomp stands for secure computing mode and has been a feature of the Linux kernel since version 2.6.12. It can be used to sandbox the privileges of a process, restricting the calls it is able to make from userspace into the kernel. Kubernetes lets you automatically apply seccomp profiles loaded onto a node to your Pods and containers.

Identifying the privileges required for your workloads can be difficult. In this tutorial, you will go through how to load seccomp profiles into a local Kubernetes cluster, how to apply them to a Pod, and how you can begin to craft profiles that give only the necessary privileges to your container processes.

Objectives

Learn how to load seccomp profiles on a node
Learn how to apply a seccomp profile to a container
Observe auditing of syscalls made by a container process
Observe behavior when a missing profile is specified
Observe a violation of a seccomp profile
Learn how to create fine-grained seccomp profiles
Learn how to apply a container runtime default seccomp profile

Before you begin

In order to complete all steps in this tutorial, you must install kind and kubectl.

This tutorial shows some examples that are still beta (since v1.25) and others that use only generally available seccomp functionality. You should make sure that your cluster is configured correctly for the version you are using.

The tutorial also uses the curl tool for downloading examples to your computer. You can adapt the steps to use a different tool if you prefer.

Note: It is not possible to apply a seccomp profile to a container running with privileged: true set in the container's securityContext. Privileged containers always run as Unconfined.

Download example seccomp profiles

The contents of these profiles will be explored later on, but for now go ahead and download them into a directory named profiles/ so that they can be loaded into the cluster.

Run these commands: n:right"> ubernetes/website/main/content/en/examples/pods/security/seccomp/profiles/audit.json" download="pods/security/seccomp/profiles/audit.json">pods/security/seccomp/profiles/audit.json net/0901162ab78eb4ff2e9e5dc8b17c3824befc91a6/44ccd/images/copycode.svg" style="max-height:24px; cursor: pointer" onclick="copyCode('pods-security-seccomp-profiles-audit-json')" title="Copy pods/security/seccomp/profiles/audit.json to clipboard"> eccomp-profiles-audit-json"> style="background-color:#f8f8f8;-moz-tab-size:4;-o-tab-size:4;tab-size:4;">{ "defaultAction": "SCMP_ACT_LOG" }

role="tabpanel" aria-labelledby="tab-with-code-1"> n:right"> ubernetes/website/main/content/en/examples/pods/security/seccomp/profiles/violation.json" download="pods/security/seccomp/profiles/violation.json">pods/security/seccomp/profiles/violation.json net/0901162ab78eb4ff2e9e5dc8b17c3824befc91a6/44ccd/images/copycode.svg" style="max-height:24px; cursor: pointer" onclick="copyCode('pods-security-seccomp-profiles-violation-json')" title="Copy pods/security/seccomp/profiles/violation.json to clipboard"> eccomp-profiles-violation-json"> style="background-color:#f8f8f8;-moz-tab-size:4;-o-tab-size:4;tab-size:4;">{ "defaultAction": "SCMP_ACT_ERRNO" }

Security

1 - Apply Pod Security Standards at the Cluster Level

Note

Before you begin

Choose the right Pod Security Standard to apply

Set modes, versions and standards

Clean up

What's next

2 - Apply Pod Security Standards at the Namespace Level

Note

Before you begin

Create cluster

Create a namespace

Apply Pod Security Standards

Verify the Pod Security Standards

Clean up

What's next

3 - Restrict a Container's Access to Resources with AppArmor

Objectives

Before you begin

Securing a Pod

Example

Administration

Setting up nodes with profiles

Disabling AppArmor

Authoring Profiles

API Reference

Pod Annotation

Profile Reference

What's next

4 - Restrict a Container's Syscalls with seccomp

Objectives

Before you begin

Download example seccomp profiles

Create a local Kubernetes cluster with kind

Enable the use of RuntimeDefault as the default seccomp profile for all workloads

Create a Pod with a seccomp profile for syscall auditing

Create Pod with a seccomp profile that causes violation

Create Pod with a seccomp profile that only allows necessary syscalls

Create Pod that uses the container runtime default seccomp profile

What's next

Enable the use of `RuntimeDefault` as the default seccomp profile for all workloads