Creating the custom security context constraint for Db2

Default SCC

When you create a Db2 instance, an SCC named <NAMESPACE>-c-db2oltp-<INSTANCE_ID>-scc is created automatically.

The contents of the SCC depend on whether you change the node settings to allow Db2U to make unsafe sysctl changes.

allowHostDirVolumePlugin: true
allowHostIPC: false
allowHostNetwork: false
allowHostPID: false
allowHostPorts: false
allowPrivilegeEscalation: true
allowPrivilegedContainer: true
allowedCapabilities:
- FOWNER
- SETGID
- SETUID
- CHOWN
- DAC_OVERRIDE
- SYS_RESOURCE
- IPC_OWNER
- SYS_NICE
- FSETID
- SETFCAP
- SETPCAP
- SYS_CHROOT
- KILL
- AUDIT_WRITE
apiVersion: security.openshift.io/v1
defaultAddCapabilities: null
fsGroup:
  type: RunAsAny
groups: []
kind: SecurityContextConstraints
metadata:
  name: ${SCC_NAME}
priority: 10
readOnlyRootFilesystem: false
requiredDropCapabilities:
- ALL
runAsUser:
  type: RunAsAny
seLinuxContext:
  type: MustRunAs
supplementalGroups:
  type: RunAsAny
users:
- system:serviceaccount:${PROJECT_CPD_INSTANCE}:${SERVICE_ACCOUNT}
volumes:
- '*'

allowHostDirVolumePlugin: false
allowHostIPC: false
allowHostNetwork: false
allowHostPID: false
allowHostPorts: false
allowPrivilegeEscalation: false
allowPrivilegedContainer: false
allowedCapabilities: []
allowedUnsafeSysctls:
- kernel.shmmni
- kernel.shmmax
- kernel.shmall
- kernel.sem
- kernel.msgmni
- kernel.msgmax
- kernel.msgmnb
apiVersion: security.openshift.io/v1
defaultAddCapabilities: null
fsGroup:
  ranges:
  - max: 1000
    min: 1000
  type: MustRunAs
groups: []
kind: SecurityContextConstraints
metadata:
  name: ${SCC_NAME}
priority: null
readOnlyRootFilesystem: false
requiredDropCapabilities:
- KILL
- SETUID
- SETGID
- MKNOD
- ALL
runAsUser:
  type: MustRunAs
  uid: 500
seLinuxContext:
  type: MustRunAs
supplementalGroups:
  type: RunAsAny
users:
- system:serviceaccount:${PROJECT_CPD_INSTANCE}:${SERVICE_ACCOUNT}
volumes:
- configMap
- downwardAPI
- emptyDir
- persistentVolumeClaim
- projected
- secret

Extended description of the allowed capabilities

FOWNER

Bypasses permission checks on operations that normally require the file system UID of the process to match the UID of the file (for example, chmod(2), utime(2)), excluding those operations that are covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH.

SETGID

Necessary to run Db2 engine processes with escalated group privileges.

SETUID

Necessary to run Db2 engine processes with escalated user privileges.

CHOWN

Necessary to run chown to change ownership of files/directories in persistent volumes.

DAC_OVERRIDE

Bypasses permission checks for file read, write, and execute.

SYS_RESOURCE

Allows manipulation of reservations, memory allocations, and resource limits. Maximum memory allocation is still constrained by the memory cgroup (memcg) limit, which cannot be overridden by this sys-capability. The Db2 database engine needs this sys-capability to increase the resource limits (IE.ulimits).

IPC_OWNER

Bypasses permission checks for operations on IPC objects. Even when the IPC kernel parameters are set to maximum values on the hosts/worker nodes, the Db2 engine still tries to dynamically throttle those values. This system capability is provided in addition to sharing IPC namespace with the host.

SYS_NICE

Allows changing process priorities. Because each container has its own PID namespace, this capability applies to that container only. The Db2 database engine relies on process thread prioritization to ensure that Work Load Management (WLM) and Fast Communications Manager (FCM) processing is prioritized over generic agent work.

FSETID

Prevents the clearing of the setuid and setgid mode bits when a file is modified.

SETFCAP

Used to set capabilities on files.

SETPCAP

Used to set capabilities on processes.

SYS_CHROOT

Necessary to use the chroot command.

KILL

Bypasses permission checks for sending signals. Necessary for signal handling during process management.

AUDIT_WRITE

Required to write records to the kernel auditing log when SELinux is enabled.