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subjectchecker.go
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subjectchecker.go
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package restrictusers
import (
"fmt"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
kerrors "k8s.io/apimachinery/pkg/util/errors"
"k8s.io/kubernetes/pkg/apis/rbac"
kclientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
authorizationapi "github.com/openshift/origin/pkg/authorization/apis/authorization"
userapi "github.com/openshift/origin/pkg/user/apis/user"
userclient "github.com/openshift/origin/pkg/user/generated/internalclientset/typed/user/internalversion"
)
// SubjectChecker determines whether rolebindings on a subject (user, group, or
// service account) are allowed in a project.
type SubjectChecker interface {
Allowed(rbac.Subject, *RoleBindingRestrictionContext) (bool, error)
}
// UnionSubjectChecker represents the union of zero or more SubjectCheckers.
type UnionSubjectChecker []SubjectChecker
// NewUnionSubjectChecker returns a new UnionSubjectChecker.
func NewUnionSubjectChecker(checkers []SubjectChecker) UnionSubjectChecker {
return UnionSubjectChecker(checkers)
}
// Allowed determines whether the given subject is allowed in rolebindings in
// the project.
func (checkers UnionSubjectChecker) Allowed(subject rbac.Subject, ctx *RoleBindingRestrictionContext) (bool, error) {
errs := []error{}
for _, checker := range []SubjectChecker(checkers) {
allowed, err := checker.Allowed(subject, ctx)
if err != nil {
errs = append(errs, err)
} else if allowed {
return true, nil
}
}
return false, kerrors.NewAggregate(errs)
}
// RoleBindingRestrictionContext holds context that is used when determining
// whether a RoleBindingRestriction allows rolebindings on a particular subject.
type RoleBindingRestrictionContext struct {
userClient userclient.UserInterface
kclient kclientset.Interface
// groupCache maps user name to groups.
groupCache GroupCache
// userToLabels maps user name to labels.Set.
userToLabelSet map[string]labels.Set
// groupToLabels maps group name to labels.Set.
groupToLabelSet map[string]labels.Set
// namespace is the namespace for which the RoleBindingRestriction makes
// determinations.
namespace string
}
// NewRoleBindingRestrictionContext returns a new RoleBindingRestrictionContext
// object.
func NewRoleBindingRestrictionContext(ns string, kc kclientset.Interface, userClient userclient.UserInterface, groupCache GroupCache) (*RoleBindingRestrictionContext, error) {
return &RoleBindingRestrictionContext{
namespace: ns,
kclient: kc,
userClient: userClient,
groupCache: groupCache,
userToLabelSet: map[string]labels.Set{},
groupToLabelSet: map[string]labels.Set{},
}, nil
}
// labelSetForUser returns the label set for the given user subject.
func (ctx *RoleBindingRestrictionContext) labelSetForUser(subject rbac.Subject) (labels.Set, error) {
if subject.Kind != rbac.UserKind {
return labels.Set{}, fmt.Errorf("not a user: %q", subject.Name)
}
labelSet, ok := ctx.userToLabelSet[subject.Name]
if ok {
return labelSet, nil
}
user, err := ctx.userClient.Users().Get(subject.Name, metav1.GetOptions{})
if err != nil {
return labels.Set{}, err
}
ctx.userToLabelSet[subject.Name] = labels.Set(user.Labels)
return ctx.userToLabelSet[subject.Name], nil
}
// groupsForUser returns the groups for the given user subject.
func (ctx *RoleBindingRestrictionContext) groupsForUser(subject rbac.Subject) ([]*userapi.Group, error) {
if subject.Kind != rbac.UserKind {
return []*userapi.Group{}, fmt.Errorf("not a user: %q", subject.Name)
}
return ctx.groupCache.GroupsFor(subject.Name)
}
// labelSetForGroup returns the label set for the given group subject.
func (ctx *RoleBindingRestrictionContext) labelSetForGroup(subject rbac.Subject) (labels.Set, error) {
if subject.Kind != rbac.GroupKind {
return labels.Set{}, fmt.Errorf("not a group: %q", subject.Name)
}
labelSet, ok := ctx.groupToLabelSet[subject.Name]
if ok {
return labelSet, nil
}
group, err := ctx.userClient.Groups().Get(subject.Name, metav1.GetOptions{})
if err != nil {
return labels.Set{}, err
}
ctx.groupToLabelSet[subject.Name] = labels.Set(group.Labels)
return ctx.groupToLabelSet[subject.Name], nil
}
// UserSubjectChecker determines whether a user subject is allowed in
// rolebindings in the project.
type UserSubjectChecker struct {
userRestriction *authorizationapi.UserRestriction
}
// NewUserSubjectChecker returns a new UserSubjectChecker.
func NewUserSubjectChecker(userRestriction *authorizationapi.UserRestriction) UserSubjectChecker {
return UserSubjectChecker{userRestriction: userRestriction}
}
// Allowed determines whether the given user subject is allowed in rolebindings
// in the project.
func (checker UserSubjectChecker) Allowed(subject rbac.Subject, ctx *RoleBindingRestrictionContext) (bool, error) {
if subject.Kind != rbac.UserKind {
return false, nil
}
for _, userName := range checker.userRestriction.Users {
if subject.Name == userName {
return true, nil
}
}
if len(checker.userRestriction.Groups) != 0 {
subjectGroups, err := ctx.groupsForUser(subject)
if err != nil {
return false, err
}
for _, groupName := range checker.userRestriction.Groups {
for _, group := range subjectGroups {
if group.Name == groupName {
return true, nil
}
}
}
}
if len(checker.userRestriction.Selectors) != 0 {
labelSet, err := ctx.labelSetForUser(subject)
if err != nil {
return false, err
}
for _, labelSelector := range checker.userRestriction.Selectors {
selector, err := metav1.LabelSelectorAsSelector(&labelSelector)
if err != nil {
return false, err
}
if selector.Matches(labelSet) {
return true, nil
}
}
}
return false, nil
}
// GroupSubjectChecker determines whether a group subject is allowed in
// rolebindings in the project.
type GroupSubjectChecker struct {
groupRestriction *authorizationapi.GroupRestriction
}
// NewGroupSubjectChecker returns a new GroupSubjectChecker.
func NewGroupSubjectChecker(groupRestriction *authorizationapi.GroupRestriction) GroupSubjectChecker {
return GroupSubjectChecker{groupRestriction: groupRestriction}
}
// Allowed determines whether the given group subject is allowed in rolebindings
// in the project.
func (checker GroupSubjectChecker) Allowed(subject rbac.Subject, ctx *RoleBindingRestrictionContext) (bool, error) {
if subject.Kind != rbac.GroupKind {
return false, nil
}
for _, groupName := range checker.groupRestriction.Groups {
if subject.Name == groupName {
return true, nil
}
}
if len(checker.groupRestriction.Selectors) != 0 {
labelSet, err := ctx.labelSetForGroup(subject)
if err != nil {
return false, err
}
for _, labelSelector := range checker.groupRestriction.Selectors {
selector, err := metav1.LabelSelectorAsSelector(&labelSelector)
if err != nil {
return false, err
}
if selector.Matches(labelSet) {
return true, nil
}
}
}
return false, nil
}
// ServiceAccountSubjectChecker determines whether a serviceaccount subject is
// allowed in rolebindings in the project.
type ServiceAccountSubjectChecker struct {
serviceAccountRestriction *authorizationapi.ServiceAccountRestriction
}
// NewServiceAccountSubjectChecker returns a new ServiceAccountSubjectChecker.
func NewServiceAccountSubjectChecker(serviceAccountRestriction *authorizationapi.ServiceAccountRestriction) ServiceAccountSubjectChecker {
return ServiceAccountSubjectChecker{
serviceAccountRestriction: serviceAccountRestriction,
}
}
// Allowed determines whether the given serviceaccount subject is allowed in
// rolebindings in the project.
func (checker ServiceAccountSubjectChecker) Allowed(subject rbac.Subject, ctx *RoleBindingRestrictionContext) (bool, error) {
if subject.Kind != rbac.ServiceAccountKind {
return false, nil
}
subjectNamespace := subject.Namespace
if len(subjectNamespace) == 0 {
// If a RoleBinding has a subject that is a ServiceAccount with
// no namespace specified, the namespace will be defaulted to
// that of the RoleBinding. However, admission control plug-ins
// execute before this happens, so in order not to reject such
// subjects erroneously, we copy the logic here of using the
// RoleBinding's namespace if the subject's is empty.
subjectNamespace = ctx.namespace
}
for _, namespace := range checker.serviceAccountRestriction.Namespaces {
if subjectNamespace == namespace {
return true, nil
}
}
for _, serviceAccountRef := range checker.serviceAccountRestriction.ServiceAccounts {
serviceAccountNamespace := serviceAccountRef.Namespace
if len(serviceAccountNamespace) == 0 {
serviceAccountNamespace = ctx.namespace
}
if subject.Name == serviceAccountRef.Name &&
subjectNamespace == serviceAccountNamespace {
return true, nil
}
}
return false, nil
}
// NewSubjectChecker returns a new SubjectChecker.
func NewSubjectChecker(spec *authorizationapi.RoleBindingRestrictionSpec) (SubjectChecker, error) {
switch {
case spec.UserRestriction != nil:
return NewUserSubjectChecker(spec.UserRestriction), nil
case spec.GroupRestriction != nil:
return NewGroupSubjectChecker(spec.GroupRestriction), nil
case spec.ServiceAccountRestriction != nil:
return NewServiceAccountSubjectChecker(spec.ServiceAccountRestriction), nil
}
return nil, fmt.Errorf("invalid RoleBindingRestrictionSpec: %v", spec)
}