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securitycontextconstraints.go
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securitycontextconstraints.go
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package bootstrappolicy
import (
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apiserver/pkg/authentication/serviceaccount"
kapi "k8s.io/kubernetes/pkg/api"
)
const (
// SecurityContextConstraintPrivileged is used as the name for the system default privileged scc.
SecurityContextConstraintPrivileged = "privileged"
SecurityContextConstraintPrivilegedDesc = "privileged allows access to all privileged and host features and the ability to run as any user, any group, any fsGroup, and with any SELinux context. WARNING: this is the most relaxed SCC and should be used only for cluster administration. Grant with caution."
// SecurityContextConstraintRestricted is used as the name for the system default restricted scc.
SecurityContextConstraintRestricted = "restricted"
SecurityContextConstraintRestrictedDesc = "restricted denies access to all host features and requires pods to be run with a UID, and SELinux context that are allocated to the namespace. This is the most restrictive SCC and it is used by default for authenticated users."
// SecurityContextConstraintNonRoot is used as the name for the system default non-root scc.
SecurityContextConstraintNonRoot = "nonroot"
SecurityContextConstraintNonRootDesc = "nonroot provides all features of the restricted SCC but allows users to run with any non-root UID. The user must specify the UID or it must be specified on the by the manifest of the container runtime."
// SecurityContextConstraintHostMountAndAnyUID is used as the name for the system default host mount + any UID scc.
SecurityContextConstraintHostMountAndAnyUID = "hostmount-anyuid"
SecurityContextConstraintHostMountAndAnyUIDDesc = "hostmount-anyuid provides all the features of the restricted SCC but allows host mounts and any UID by a pod. This is primarily used by the persistent volume recycler. WARNING: this SCC allows host file system access as any UID, including UID 0. Grant with caution."
// SecurityContextConstraintHostNS is used as the name for the system default scc
// that grants access to all host ns features.
SecurityContextConstraintHostNS = "hostaccess"
SecurityContextConstraintHostNSDesc = "hostaccess allows access to all host namespaces but still requires pods to be run with a UID and SELinux context that are allocated to the namespace. WARNING: this SCC allows host access to namespaces, file systems, and PIDS. It should only be used by trusted pods. Grant with caution."
// SecurityContextConstraintsAnyUID is used as the name for the system default scc that
// grants access to run as any uid but is still restricted to specific SELinux contexts.
SecurityContextConstraintsAnyUID = "anyuid"
SecurityContextConstraintsAnyUIDDesc = "anyuid provides all features of the restricted SCC but allows users to run with any UID and any GID."
// SecurityContextConstraintsHostNetwork is used as the name for the system default scc that
// grants access to run with host networking and host ports but still allocates uid/gids/selinux from the
// namespace.
SecurityContextConstraintsHostNetwork = "hostnetwork"
SecurityContextConstraintsHostNetworkDesc = "hostnetwork allows using host networking and host ports but still requires pods to be run with a UID and SELinux context that are allocated to the namespace."
// DescriptionAnnotation is the annotation used for attaching descriptions.
DescriptionAnnotation = "kubernetes.io/description"
)
// GetBootstrapSecurityContextConstraints returns the slice of default SecurityContextConstraints
// for system bootstrapping. This method takes additional users and groups that should be added
// to the strategies. Use GetBoostrapSCCAccess to produce the default set of mappings.
func GetBootstrapSecurityContextConstraints(sccNameToAdditionalGroups map[string][]string, sccNameToAdditionalUsers map[string][]string) []kapi.SecurityContextConstraints {
// define priorities here and reference them below so it is easy to see, at a glance
// what we're setting
var (
// this is set to 10 to allow wiggle room for admins to set other priorities without
// having to adjust anyUID.
securityContextConstraintsAnyUIDPriority = int32(10)
)
constraints := []kapi.SecurityContextConstraints{
// SecurityContextConstraintPrivileged allows all access for every field
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintPrivileged,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintPrivilegedDesc,
},
},
AllowPrivilegedContainer: true,
AllowedCapabilities: []kapi.Capability{kapi.CapabilityAll},
Volumes: []kapi.FSType{kapi.FSTypeAll},
AllowHostNetwork: true,
AllowHostPorts: true,
AllowHostPID: true,
AllowHostIPC: true,
SELinuxContext: kapi.SELinuxContextStrategyOptions{
Type: kapi.SELinuxStrategyRunAsAny,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
Type: kapi.RunAsUserStrategyRunAsAny,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyRunAsAny,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
SeccompProfiles: []string{"*"},
},
// SecurityContextConstraintNonRoot does not allow host access, allocates SELinux labels
// and allows the user to request a specific UID or provide the default in the dockerfile.
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintNonRoot,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintNonRootDesc,
},
},
Volumes: []kapi.FSType{kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSProjected},
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
// This strategy requires that the user request to run as a specific UID or that
// the docker file contain a USER directive.
Type: kapi.RunAsUserStrategyMustRunAsNonRoot,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyRunAsAny,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
},
// SecurityContextConstraintHostMountAndAnyUID is the same as the restricted scc but allows the use of the hostPath and NFS plugins, and running as any UID.
// Used by the PV recycler.
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintHostMountAndAnyUID,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintHostMountAndAnyUIDDesc,
},
},
Volumes: []kapi.FSType{kapi.FSTypeHostPath, kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSTypeNFS, kapi.FSProjected},
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.RunAsUserStrategyRunAsAny,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyRunAsAny,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
},
// SecurityContextConstraintHostNS allows access to everything except privileged on the host
// but still allocates UIDs and SELinux.
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintHostNS,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintHostNSDesc,
},
},
Volumes: []kapi.FSType{kapi.FSTypeHostPath, kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSProjected},
AllowHostNetwork: true,
AllowHostPorts: true,
AllowHostPID: true,
AllowHostIPC: true,
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.RunAsUserStrategyMustRunAsRange,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyMustRunAs,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
},
// SecurityContextConstraintRestricted allows no host access and allocates UIDs and SELinux.
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintRestricted,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintRestrictedDesc,
},
},
Volumes: []kapi.FSType{kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSProjected},
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.RunAsUserStrategyMustRunAsRange,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyMustRunAs,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
// drops unsafe caps
RequiredDropCapabilities: []kapi.Capability{"KILL", "MKNOD", "SYS_CHROOT", "SETUID", "SETGID"},
},
// SecurityContextConstraintsAnyUID allows no host access and allocates SELinux.
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintsAnyUID,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintsAnyUIDDesc,
},
},
Volumes: []kapi.FSType{kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSProjected},
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
Type: kapi.RunAsUserStrategyRunAsAny,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyRunAsAny,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyRunAsAny,
},
// prefer the anyuid SCC over ones that force a uid
Priority: &securityContextConstraintsAnyUIDPriority,
// drops unsafe caps
RequiredDropCapabilities: []kapi.Capability{"MKNOD", "SYS_CHROOT"},
},
// SecurityContextConstraintsHostNetwork allows host network and host ports
{
ObjectMeta: metav1.ObjectMeta{
Name: SecurityContextConstraintsHostNetwork,
Annotations: map[string]string{
DescriptionAnnotation: SecurityContextConstraintsHostNetworkDesc,
},
},
AllowHostNetwork: true,
AllowHostPorts: true,
Volumes: []kapi.FSType{kapi.FSTypeEmptyDir, kapi.FSTypeSecret, kapi.FSTypeDownwardAPI, kapi.FSTypeConfigMap, kapi.FSTypePersistentVolumeClaim, kapi.FSProjected},
SELinuxContext: kapi.SELinuxContextStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.SELinuxStrategyMustRunAs,
},
RunAsUser: kapi.RunAsUserStrategyOptions{
// This strategy requires that annotations on the namespace which will be populated
// by the admission controller. If namespaces are not annotated creating the strategy
// will fail.
Type: kapi.RunAsUserStrategyMustRunAsRange,
},
FSGroup: kapi.FSGroupStrategyOptions{
Type: kapi.FSGroupStrategyMustRunAs,
},
SupplementalGroups: kapi.SupplementalGroupsStrategyOptions{
Type: kapi.SupplementalGroupsStrategyMustRunAs,
},
// drops unsafe caps
RequiredDropCapabilities: []kapi.Capability{"KILL", "MKNOD", "SYS_CHROOT", "SETUID", "SETGID"},
},
}
// add default access
for i, constraint := range constraints {
if usersToAdd, ok := sccNameToAdditionalUsers[constraint.Name]; ok {
constraints[i].Users = append(constraints[i].Users, usersToAdd...)
}
if groupsToAdd, ok := sccNameToAdditionalGroups[constraint.Name]; ok {
constraints[i].Groups = append(constraints[i].Groups, groupsToAdd...)
}
}
return constraints
}
// GetBoostrapSCCAccess provides the default set of access that should be passed to GetBootstrapSecurityContextConstraints.
func GetBoostrapSCCAccess(infraNamespace string) (map[string][]string, map[string][]string) {
groups := map[string][]string{
SecurityContextConstraintPrivileged: {ClusterAdminGroup, NodesGroup},
SecurityContextConstraintsAnyUID: {ClusterAdminGroup},
SecurityContextConstraintRestricted: {AuthenticatedGroup},
}
buildControllerUsername := serviceaccount.MakeUsername(infraNamespace, InfraBuildControllerServiceAccountName)
pvRecyclerControllerUsername := serviceaccount.MakeUsername(infraNamespace, InfraPersistentVolumeRecyclerControllerServiceAccountName)
users := map[string][]string{
SecurityContextConstraintPrivileged: {buildControllerUsername},
SecurityContextConstraintHostMountAndAnyUID: {pvRecyclerControllerUsername},
}
return groups, users
}