cloudfoundry/cf-k8s-controllers

package authorization

import (
    "context"
    "fmt"
    "strings"

    apierrors "code.cloudfoundry.org/korifi/api/errors"
    korifiv1alpha1 "code.cloudfoundry.org/korifi/controllers/api/v1alpha1"

    corev1 "k8s.io/api/core/v1"
    rbacv1 "k8s.io/api/rbac/v1"
    "sigs.k8s.io/controller-runtime/pkg/client"
)

//+kubebuilder:rbac:groups=rbac.authorization.k8s.io,resources=rolebindings,verbs=list
//+kubebuilder:rbac:groups="",resources=namespaces,verbs=list

//counterfeiter:generate -o fake -fake-name IdentityProvider . IdentityProvider

type IdentityProvider interface {
    GetIdentity(context.Context, Info) (Identity, error)
}

type NamespacePermissions struct {
    privilegedClient client.Client
    identityProvider IdentityProvider
}

func NewNamespacePermissions(privilegedClient client.Client, identityProvider IdentityProvider) *NamespacePermissions {
    return &NamespacePermissions{
        privilegedClient: privilegedClient,
        identityProvider: identityProvider,
    }
}

func (o *NamespacePermissions) GetAuthorizedOrgNamespaces(ctx context.Context, info Info) (map[string]bool, error) {
    return o.getAuthorizedNamespaces(ctx, info, korifiv1alpha1.OrgNameKey, "Org")
}

func (o *NamespacePermissions) GetAuthorizedSpaceNamespaces(ctx context.Context, info Info) (map[string]bool, error) {
    return o.getAuthorizedNamespaces(ctx, info, korifiv1alpha1.SpaceNameKey, "Space")
}

func (o *NamespacePermissions) getAuthorizedNamespaces(ctx context.Context, info Info, orgSpaceLabel, resourceType string) (map[string]bool, error) {
    identity, err := o.identityProvider.GetIdentity(ctx, info)
    if err != nil {
        return nil, fmt.Errorf("failed to get identity: %w", err)
    }

    var rolebindings rbacv1.RoleBindingList
    if err := o.privilegedClient.List(ctx, &rolebindings); err != nil {
        return nil, fmt.Errorf("failed to list rolebindings: %w", apierrors.FromK8sError(err, resourceType))
    }

    var cfOrgsOrSpaces corev1.NamespaceList
    if err := o.privilegedClient.List(ctx, &cfOrgsOrSpaces, client.HasLabels([]string{orgSpaceLabel})); err != nil {
        return nil, fmt.Errorf("failed to list namespaces: %w", apierrors.FromK8sError(err, resourceType))
    }

    cfNamespaces := map[string]bool{}
    for _, ns := range cfOrgsOrSpaces.Items {
        cfNamespaces[ns.Name] = true
    }

    authorizedNamespaces := map[string]bool{}

    for _, roleBinding := range rolebindings.Items {
        for _, subject := range roleBinding.Subjects {
            isMatch, err := SameSubject(subject, identity)
            if err != nil {
                return nil, err
            }
            if isMatch {
                if cfNamespaces[roleBinding.Namespace] {
                    authorizedNamespaces[roleBinding.Namespace] = true
                }
            }
        }
    }

    return authorizedNamespaces, nil
}

func (o *NamespacePermissions) AuthorizedIn(ctx context.Context, identity Identity, namespace string) (bool, error) {
    var rolebindings rbacv1.RoleBindingList
    err := o.privilegedClient.List(ctx, &rolebindings, client.InNamespace(namespace))
    if err != nil {
        return false, fmt.Errorf("failed to list rolebindings: %w", apierrors.FromK8sError(err, ""))
    }

    for _, roleBinding := range rolebindings.Items {
        for _, subject := range roleBinding.Subjects {
            isMatch, err := SameSubject(subject, identity)
            if err != nil {
                return false, err
            }
            if isMatch {
                return true, nil
            }
        }
    }

    return false, nil
}

func SameSubject(subject rbacv1.Subject, identity Identity) (bool, error) {
    if identity.Kind != subject.Kind {
        return false, nil
    }

    if identity.Kind == "ServiceAccount" {
        if !HasServiceAccountPrefix(identity.Name) {
            return false, fmt.Errorf("expected user identifier %q to have prefix %q", identity.Name, serviceAccountNamePrefix)
        }
        identitySANS, identitySAName := ServiceAccountNSAndName(identity.Name)
        return identitySAName == subject.Name && identitySANS == subject.Namespace, nil
    } else {
        return identity.Name == subject.Name, nil
    }
}

func ServiceAccountNSAndName(serviceAccountSubjectName string) (string, string) {
    nameSegments := strings.Split(serviceAccountSubjectName, ":")

    serviceAccountNS := nameSegments[len(nameSegments)-2]
    serviceAccountName := nameSegments[len(nameSegments)-1]
    return serviceAccountNS, serviceAccountName
}