Lab 5.4 - how to solve the challenge step?
To recap - the challenge is to use what you have learned about service accounts and RBAC roles to limit a psp to the dev-ns namespace.
My idea to solve the challenge is:
1. Create a PSP to allow everything and let everyone use it across all the namespaces.
2. A second PSP (the target) will be only allowed by all the accounts in the dev-ns
namespace.
Phase 1
student@master:~$ k get psp privileged Warning: policy/v1beta1 PodSecurityPolicy is deprecated in v1.21+, unavailable in v1.25+ NAME PRIV CAPS SELINUX RUNASUSER FSGROUP SUPGROUP READONLYROOTFS VOLUMES privileged true * RunAsAny RunAsAny RunAsAny RunAsAny false * student@master:~$ k describe clusterrole psp:privileged Name: psp:privileged Labels: <none> Annotations: <none> PolicyRule: Resources Non-Resource URLs Resource Names Verbs --------- ----------------- -------------- ----- podsecuritypolicies.policy [] [privileged] [use] student@master:~$ k describe clusterrolebinding any:psp:privileged Name: any:psp:privileged Labels: <none> Annotations: <none> Role: Kind: ClusterRole Name: psp:privileged Subjects: Kind Name Namespace ---- ---- --------- Group system:serviceaccounts Group system:authenticated student@master:~$ k auth can-i --as system:serviceaccounts:dev-ns:simple-sa use psp/privileged Warning: resource 'podsecuritypolicies' is not namespace scoped in group 'policy' yes student@master:~$ k auth can-i --as system:serviceaccounts:default:default use psp/privileged Warning: resource 'podsecuritypolicies' is not namespace scoped in group 'policy' yes student@master:~$ k auth can-i use psp/privileged Warning: resource 'podsecuritypolicies' is not namespace scoped in group 'policy' yes student@master:~$
Phase 2
student@master:~/5$ k -n dev-ns get psp Warning: policy/v1beta1 PodSecurityPolicy is deprecated in v1.21+, unavailable in v1.25+ NAME PRIV CAPS SELINUX RUNASUSER FSGROUP SUPGROUP READONLYROOTFS VOLUMES no-priv false RunAsAny MustRunAsNonRoot RunAsAny RunAsAny false * privileged true * RunAsAny RunAsAny RunAsAny RunAsAny false * student@master:~/5$ k -n dev-ns describe role psp:no-priv Name: psp:no-priv Labels: <none> Annotations: <none> PolicyRule: Resources Non-Resource URLs Resource Names Verbs --------- ----------------- -------------- ----- podsecuritypolicies.policy [] [no-priv] [use] student@master:~/5$ k -n dev-ns describe rolebinding any:psp:no-priv Name: any:psp:no-priv Labels: <none> Annotations: <none> Role: Kind: Role Name: psp:no-priv Subjects: Kind Name Namespace ---- ---- --------- Group system:authenticated Group system:serviceaccounts:dev-ns student@master:~/5$ k -n dev-ns auth can-i --as system:serviceaccount:dev-ns:default use psp/no-priv Warning: resource 'podsecuritypolicies' is not namespace scoped in group 'policy' yes student@master:~/5$ k -n dev-ns auth can-i use psp/no-priv Warning: resource 'podsecuritypolicies' is not namespace scoped in group 'policy' yes student@master:~/5$ k -n dev-ns get pod,rs,deploy No resources found in dev-ns namespace. student@master:~/5$
Now I am going to create the pod db-one
and deployment db-two
in the dev-ns
namespace. The respective pods require to run as root, which is forbidden by the no-priv
policy - we already saw it earlier in the lab. My expectation is that the policy would prevent the pods from starting:
student@master:~/5$ k run --image=mariadb db-one --port=3306 --env="MYSQL_ROOT_PASSWORD=LFtr@in" -n dev-ns pod/db-one created student@master:~/5$ k create -f db-two.yaml deployment.apps/db-two created student@master:~/5$ k -n dev-ns get pod,rs,deploy NAME READY STATUS RESTARTS AGE pod/db-one 0/1 ContainerCreating 0 14s pod/db-two-cfb5c47db-llbq8 0/1 ContainerCreating 0 3s NAME DESIRED CURRENT READY AGE replicaset.apps/db-two-cfb5c47db 1 1 0 3s NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/db-two 0/1 1 0 3s student@master:~/5$
And already we can see that my idea does not work. If the no-priv
policy actually worked in the dev-ns
namespace, then the replica controller would not have been able to create the pod, but it did. And right now the situation is that all is running, despite my expectations:
student@master:~/5$ k -n dev-ns get pod,rs,deploy NAME READY STATUS RESTARTS AGE pod/db-one 1/1 Running 0 2m30s pod/db-two-cfb5c47db-llbq8 1/1 Running 0 2m19s NAME DESIRED CURRENT READY AGE replicaset.apps/db-two-cfb5c47db 1 1 1 2m19s NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/db-two 1/1 1 1 2m19s student@master:~/5$
So my scheme does not work and I have no idea how to solve the challenge. Please, help. Thank you.
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