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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