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serviceaccount.go
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serviceaccount.go
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package utils
import (
"context"
"fmt"
"os"
"strconv"
"time"
"go.uber.org/zap"
authorizationv1 "k8s.io/api/authorization/v1"
v1 "k8s.io/api/core/v1"
rbac "k8s.io/api/rbac/v1"
k8serrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/client-go/kubernetes"
"github.com/fission/fission/pkg/utils/uuid"
)
const (
FetcherSAName string = "fission-fetcher"
BuilderSAName string = "fission-builder"
ENV_CREATE_SA string = "SERVICEACCOUNT_CHECK_ENABLED"
ENV_SA_INTERVAL string = "SERVICEACCOUNT_CHECK_INTERVAL"
)
type (
ServiceAccount struct {
kubernetesClient kubernetes.Interface
logger *zap.Logger
nsResolver *NamespaceResolver
permissions []*ServiceAccountPermissions
}
ServiceAccountPermissions struct {
saName string
permissions []*PermissionCheck
}
PermissionCheck struct {
gvr *schema.GroupVersionResource
verb string
exists bool
}
)
var (
fetcherCheck = &ServiceAccountPermissions{
saName: FetcherSAName,
permissions: []*PermissionCheck{
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "configmaps"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "secrets"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "fission.io", Version: "v1", Resource: "packages"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "events"},
verb: "create",
},
},
}
builderCheck = &ServiceAccountPermissions{
saName: BuilderSAName,
permissions: []*PermissionCheck{
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "configmaps"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "", Version: "v1", Resource: "secrets"},
verb: "get",
},
{
gvr: &schema.GroupVersionResource{Group: "fission.io", Version: "v1", Resource: "packages"},
verb: "get",
},
},
}
)
func CreateMissingPermissionForSA(ctx context.Context, kubernetesClient kubernetes.Interface, logger *zap.Logger) {
enableSA := createServiceAccount()
if enableSA {
interval := getSAInterval()
logger.Debug("interval value", zap.Any("interval", interval))
sa := getSAObj(ctx, kubernetesClient, logger)
logger.Info("Starting service account check", zap.Any("interval", interval))
if interval > 0 {
go wait.UntilWithContext(ctx, sa.runSACheck, interval)
} else {
sa.runSACheck(ctx)
}
}
}
func getSAObj(ctx context.Context, kubernetesClient kubernetes.Interface, logger *zap.Logger) *ServiceAccount {
saObj := &ServiceAccount{
kubernetesClient: kubernetesClient,
logger: logger,
nsResolver: DefaultNSResolver(),
}
saObj.permissions = append(saObj.permissions, fetcherCheck)
saObj.permissions = append(saObj.permissions, builderCheck)
return saObj
}
func (sa *ServiceAccount) runSACheck(ctx context.Context) {
for _, ns := range sa.nsResolver.FissionResourceNS {
for _, permission := range sa.permissions {
if permission.saName == BuilderSAName {
ns = sa.nsResolver.GetBuilderNS(ns)
} else {
ns = sa.nsResolver.GetFunctionNS(ns)
}
setupSAAndRoleBindings(ctx, sa.kubernetesClient, sa.logger, ns, permission)
}
}
}
func setupSAAndRoleBindings(ctx context.Context, client kubernetes.Interface, logger *zap.Logger, namespace string, ps *ServiceAccountPermissions) {
SAObj, err := createGetSA(ctx, client, ps.saName, namespace)
if err != nil {
logger.Error("error while creating or getting service account",
zap.String("sa_name", ps.saName),
zap.String("namespace", namespace),
zap.Error(err))
return
}
var rules []rbac.PolicyRule
for _, permission := range ps.permissions {
permission.exists, err = checkPermission(ctx, client, SAObj, permission.gvr, permission.verb)
if err != nil {
// some error occurred while checking permission, log error as warning message and continue to create new permissions
logger.Info(err.Error())
}
if !permission.exists {
logger.Info("creating new permission",
zap.String("service_account", SAObj.Name),
zap.String("namespace", SAObj.Namespace),
zap.String("group", permission.gvr.Group),
zap.String("resource", permission.gvr.Resource),
zap.String("verb", permission.verb))
rules = append(rules, rbac.PolicyRule{
APIGroups: []string{permission.gvr.Group},
Resources: []string{permission.gvr.Resource},
Verbs: []string{permission.verb},
})
}
}
if len(rules) > 0 {
suffix, err := generateSuffix()
if err != nil {
logger.Error("error while generating random suffix", zap.Error(err))
}
// permission not exists, setup roles for the same
role, err := setupRoles(ctx, client, logger, SAObj, rules, suffix)
if err != nil {
logger.Error("error while creating roles", zap.Error(err))
return
}
_, err = setupRoleBinding(ctx, client, logger, SAObj, role, suffix)
if err != nil {
logger.Error("error while creating role bindings", zap.Error(err))
return
}
}
}
func setupRoles(ctx context.Context, client kubernetes.Interface, logger *zap.Logger, sa *v1.ServiceAccount, rules []rbac.PolicyRule, suffix string) (*rbac.Role, error) {
logger.Debug("creating role",
zap.String("role_name", fmt.Sprintf("%s-role-%s", sa.Name, suffix)),
zap.String("sa_name", sa.Name),
zap.String("namespace", sa.Namespace))
roleObj := &rbac.Role{
ObjectMeta: metav1.ObjectMeta{
Name: fmt.Sprintf("%s-role-%s", sa.Name, suffix),
Namespace: sa.Namespace,
},
Rules: rules,
}
role, err := client.RbacV1().Roles(sa.Namespace).Create(ctx, roleObj, metav1.CreateOptions{})
if err != nil {
return nil, fmt.Errorf("error while creating role for sa %s in namespace %s error: %s", sa.Name, sa.Namespace, err.Error())
}
logger.Info("role created successfully",
zap.String("role_name", role.Name),
zap.String("namespace", role.Namespace),
zap.String("sa_name", sa.Name))
return role, nil
}
func setupRoleBinding(ctx context.Context, client kubernetes.Interface, logger *zap.Logger, sa *v1.ServiceAccount, role *rbac.Role, suffix string) (*rbac.RoleBinding, error) {
logger.Debug("creating role binding",
zap.String("rolebinding_name", fmt.Sprintf("%s-rolebinding-%s", sa.Name, suffix)),
zap.String("sa_name", sa.Name),
zap.String("namespace", sa.Namespace))
roleBindingObj := &rbac.RoleBinding{
ObjectMeta: metav1.ObjectMeta{
Name: fmt.Sprintf("%s-rolebinding-%s", sa.Name, suffix),
Namespace: sa.Namespace,
},
Subjects: []rbac.Subject{
{
Kind: "ServiceAccount",
Name: sa.Name,
Namespace: sa.Namespace,
},
},
RoleRef: rbac.RoleRef{
Kind: "Role",
Name: role.Name,
},
}
roleBinding, err := client.RbacV1().RoleBindings(sa.Namespace).Create(ctx, roleBindingObj, metav1.CreateOptions{})
if err != nil {
return nil, fmt.Errorf("error while creating rolebinding for sa %s in namespace %s error: %s", sa.Name, sa.Namespace, err.Error())
}
logger.Info("role binding created successfully",
zap.String("rolebinding_name", roleBinding.Name),
zap.String("namespace", roleBinding.Namespace),
zap.String("sa_name", sa.Name))
return roleBinding, nil
}
func checkPermission(ctx context.Context, client kubernetes.Interface, sa *v1.ServiceAccount, gvr *schema.GroupVersionResource, verb string) (bool, error) {
user := fmt.Sprintf("system:serviceaccount:%s:%s", sa.Namespace, sa.Name)
sar := authorizationv1.LocalSubjectAccessReview{
ObjectMeta: metav1.ObjectMeta{
Namespace: sa.Namespace,
},
Spec: authorizationv1.SubjectAccessReviewSpec{
ResourceAttributes: &authorizationv1.ResourceAttributes{
Namespace: sa.Namespace,
Group: gvr.Group,
Version: gvr.Version,
Resource: gvr.Resource,
Verb: verb,
},
User: fmt.Sprintf("system:serviceaccount:%s:%s", sa.Namespace, sa.Name),
},
}
r, err := client.AuthorizationV1().LocalSubjectAccessReviews(sa.Namespace).Create(ctx, &sar, metav1.CreateOptions{})
if err != nil {
return false, fmt.Errorf("error occurred while checking permission for sa %s error: %s", user, err.Error())
}
if !r.Status.Allowed {
return false, fmt.Errorf("permission %s/%s/%s-%s denied for sa %s", gvr.Group, gvr.Version, gvr.Resource, verb, user)
}
return true, nil
}
// CreateGetSA => create service account if not exists else get it.
func createGetSA(ctx context.Context, k8sClient kubernetes.Interface, SAName, ns string) (*v1.ServiceAccount, error) {
saObj, err := k8sClient.CoreV1().ServiceAccounts(ns).Get(ctx, SAName, metav1.GetOptions{})
if err != nil && k8serrors.IsNotFound(err) {
saObj = &v1.ServiceAccount{
ObjectMeta: metav1.ObjectMeta{
Namespace: ns,
Name: SAName,
},
}
saObj, err = k8sClient.CoreV1().ServiceAccounts(ns).Create(ctx, saObj, metav1.CreateOptions{})
if err != nil {
return nil, err
}
}
if err != nil {
return nil, err
}
return saObj, nil
}
// generateSuffix generates a random string of 6 characters
func generateSuffix() (string, error) {
id := uuid.NewString()
return id[:6], nil
}
func createServiceAccount() bool {
createSA, err := strconv.ParseBool(os.Getenv(ENV_CREATE_SA))
if err != nil {
return false
}
return createSA
}
func getSAInterval() time.Duration {
SAInterval, _ := GetUIntValueFromEnv(ENV_SA_INTERVAL)
return time.Duration(SAInterval) * time.Minute
}