Linux Foundation CKS Practice Test - Questions Answers, Page 3

ETCD secret encryption can be verified with the help of etcdctl command line utility.

ETCD secrets are stored at the path /registry/secrets/$namespace/$secret on the master node.

The below command can be used to verify if the particular ETCD secret is encrypted or not.

# ETCDCTL_API=3 etcdctl get /registry/secrets/default/secret1 [...] | hexdump -C

kubesec scan k8s-deployment.yaml

cat <<EOF > kubesec-test.yaml

apiVersion: v1

kind: Pod

metadata:

name: kubesec-demo

spec:

containers:

- name: kubesec-demo

image: gcr.io/google-samples/node-hello:1.0

securityContext:

readOnlyRootFilesystem: true

EOF

kubesec scan kubesec-test.yaml

docker run -i kubesec/kubesec:512c5e0 scan /dev/stdin < kubesec-test.yaml

kubesec http 8080 &

[1] 12345

{"severity":"info","timestamp":"2019-05-

12T11:58:34.662+0100","caller":"server/server.go:69","message":"Starting HTTP server on port

8080"}

curl -sSX POST --data-binary @test/asset/score-0-cap-sys-admin.yml http://localhost:8080/scan

[

{

"object": "Pod/security-context-demo.default",

"valid": true,

"message": "Failed with a score of -30 points",

"score": -30,

"scoring": {

"critical": [

{

"selector": "containers[] .securityContext .capabilities .add == SYS_ADMIN",

"reason": "CAP_SYS_ADMIN is the most privileged capability and should always be avoided"

},

{

"selector": "containers[] .securityContext .runAsNonRoot == true",

"reason": "Force the running image to run as a non-root user to ensure least privilege"

},

// ...

Reference: https://kubernetes.io/docs/concepts/services-networking/network-policies/

Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

https://cloud.google.com/architecture/best-practices-for-operating-containers

Create psp to disallow privileged container

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: deny-access-role

rules:

- apiGroups: ['policy']

resources: ['podsecuritypolicies']

verbs: ['use']

resourceNames:

- “deny-policy”

k create sa psp-denial-sa -n development

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRoleBinding

metadata:

name: restrict-access-bing

roleRef:

kind: ClusterRole

name: deny-access-role

apiGroup: rbac.authorization.k8s.io

subjects:

- kind: ServiceAccount

name: psp-denial-sa

namespace: development

Explanation

master1 $ vim psp.yaml

apiVersion: policy/v1beta1

kind: PodSecurityPolicy

metadata:

name: deny-policy

spec:

privileged: false # Don't allow privileged pods!

seLinux:

rule: RunAsAny

supplementalGroups:

rule: RunAsAny

runAsUser:

rule: RunAsAny

fsGroup:

rule: RunAsAny

volumes:

- '*'

master1 $ vim cr1.yaml

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: deny-access-role

rules:

- apiGroups: ['policy']

resources: ['podsecuritypolicies']

verbs: ['use']

resourceNames:

- “deny-policy”

master1 $ k create sa psp-denial-sa -n development

master1 $ vim cb1.yaml

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRoleBinding

metadata:

name: restrict-access-bing

roleRef:

kind: ClusterRole

name: deny-access-role

apiGroup: rbac.authorization.k8s.io

subjects:

# Authorize specific service accounts:

- kind: ServiceAccount

name: psp-denial-sa

namespace: development

master1 $ k apply -f psp.yaml

master1 $ k apply -f cr1.yaml

master1 $ k apply -f cb1.yaml

Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

1. For Dockerfile: Fix the image version & user name in Dockerfile

2. For mydeployment.yaml : Fix security contexts

[desk@cli] $ vim /home/cert_masters/Dockerfile

FROM ubuntu:latest # Remove this

FROM ubuntu:18.04 # Add this

USER root # Remove this

USER nobody # Add this

RUN apt get install -y lsof=4.72 wget=1.17.1 nginx=4.2

ENV ENVIRONMENT=testing

USER root # Remove this

USER nobody # Add this

CMD ["nginx -d"]

[desk@cli] $ vim /home/cert_masters/mydeployment.yaml

apiVersion: apps/v1

kind: Deployment

metadata:

creationTimestamp: null

labels:

app: kafka

name: kafka

spec:

replicas: 1

selector:

matchLabels:

app: kafka

strategy: {}

template:

metadata:

creationTimestamp: null

labels:

app: kafka

spec:

containers:

- image: bitnami/kafka

name: kafka

volumeMounts:

- name: kafka-vol

mountPath: /var/lib/kafka

securityContext:

{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged":

True,"readOnlyRootFilesystem": False, "runAsUser": 65535} # Delete This

{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged":

False,"readOnlyRootFilesystem": True, "runAsUser": 65535} # Add This

resources: {}

volumes:

- name: kafka-vol

emptyDir: {}

status: {}

Pictorial View:

[desk@cli] $ vim /home/cert_masters/mydeployment.yaml

Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

$ vim /etc/kubernetes/log-policy/audit-policy.yaml

- level: RequestResponse

userGroups: ["system:nodes"]

- level: Request

resources:

- group: "" # core API group

resources: ["persistentvolumes"]

namespaces: ["frontend"]

- level: Metadata

resources:

- group: ""

resources: ["configmaps", "secrets"]

- level: Metadata

$ vim /etc/kubernetes/manifests/kube-apiserver.yaml

Add these

- --audit-policy-file=/etc/kubernetes/log-policy/audit-policy.yaml

- --audit-log-path=/var/log/kubernetes/logs.txt

- --audit-log-maxage=5

- --audit-log-maxbackup=10

Explanation

[desk@cli] $ ssh master1

[master1@cli] $ vim /etc/kubernetes/log-policy/audit-policy.yaml

apiVersion: audit.k8s.io/v1 # This is required.

kind: Policy

# Don't generate audit events for all requests in RequestReceived stage.

omitStages:

- "RequestReceived"

rules:

# Don't log watch requests by the "system:kube-proxy" on endpoints or services

- level: None

users: ["system:kube-proxy"]

verbs: ["watch"]

resources:

- group: "" # core API group

resources: ["endpoints", "services"]

# Don't log authenticated requests to certain non-resource URL paths.

- level: None

userGroups: ["system:authenticated"]

nonResourceURLs:

- "/api*" # Wildcard matching.

- "/version"

# Add your changes below

- level: RequestResponse

userGroups: ["system:nodes"] # Block for nodes

- level: Request

resources:

- group: "" # core API group

resources: ["persistentvolumes"] # Block for persistentvolumes

namespaces: ["frontend"] # Block for persistentvolumes of frontend ns

- level: Metadata

resources:

- group: "" # core API group

resources: ["configmaps", "secrets"] # Block for configmaps & secrets

- level: Metadata # Block for everything else

[master1@cli] $ vim /etc/kubernetes/manifests/kube-apiserver.yaml

apiVersion: v1

kind: Pod

metadata:

annotations:

kubeadm.kubernetes.io/kube-apiserver.advertise-address.endpoint: 10.0.0.5:6443

labels:

component: kube-apiserver

tier: control-plane

name: kube-apiserver

namespace: kube-system

spec:

containers:

- command:

- kube-apiserver

- --advertise-address=10.0.0.5

- --allow-privileged=true

- --authorization-mode=Node,RBAC

- --audit-policy-file=/etc/kubernetes/log-policy/audit-policy.yaml #Add this

- --audit-log-path=/var/log/kubernetes/logs.txt #Add this

- --audit-log-maxage=5 #Add this

- --audit-log-maxbackup=10 #Add this

...

output truncated

Note: log volume & policy volume is already mounted in vim /etc/kubernetes/manifests/kube-apiserver.yaml so no need to mount it.

Reference: https://kubernetes.io/docs/tasks/debug-application-cluster/audit/

Reference: https://kubernetes.io/docs/tutorials/clusters/apparmor/