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kubeseal.go
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package kubeseal
import (
"bytes"
"context"
"crypto/rand"
"crypto/rsa"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"os"
"strings"
"time"
ssv1alpha1 "github.com/bitnami-labs/sealed-secrets/pkg/apis/sealedsecrets/v1alpha1"
"github.com/bitnami-labs/sealed-secrets/pkg/crypto"
"github.com/bitnami-labs/sealed-secrets/pkg/multidocyaml"
v1 "k8s.io/api/core/v1"
k8serrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
runtimeserializer "k8s.io/apimachinery/pkg/runtime/serializer"
"k8s.io/apimachinery/pkg/util/net"
"k8s.io/client-go/kubernetes/scheme"
corev1 "k8s.io/client-go/kubernetes/typed/core/v1"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/client-go/util/cert"
"k8s.io/client-go/util/keyutil"
)
type ClientConfig interface {
ClientConfig() (*rest.Config, error)
Namespace() (string, bool, error)
}
func ParseKey(r io.Reader) (*rsa.PublicKey, error) {
data, err := io.ReadAll(r)
if err != nil {
return nil, err
}
certs, err := cert.ParseCertsPEM(data)
if err != nil {
return nil, err
}
// ParseCertsPem returns error if len(certs) == 0, but best to be sure...
if len(certs) == 0 {
return nil, errors.New("failed to read any certificates")
}
cert, ok := certs[0].PublicKey.(*rsa.PublicKey)
if !ok {
return nil, fmt.Errorf("expected RSA public key but found %v", certs[0].PublicKey)
}
if time.Now().After(certs[0].NotAfter) {
return nil, fmt.Errorf("failed to encrypt using an expired certificate on %v", certs[0].NotAfter.Format("January 2, 2006"))
}
return cert, nil
}
func readSecret(codec runtime.Decoder, r io.Reader) (*v1.Secret, error) {
data, err := io.ReadAll(r)
if err != nil {
return nil, err
}
if err := multidocyaml.EnsureNotMultiDoc(data); err != nil {
return nil, err
}
var ret v1.Secret
if err = runtime.DecodeInto(codec, data, &ret); err != nil {
return nil, err
}
return &ret, nil
}
func prettyEncoder(codecs runtimeserializer.CodecFactory, mediaType string, gv runtime.GroupVersioner) (runtime.Encoder, error) {
info, ok := runtime.SerializerInfoForMediaType(codecs.SupportedMediaTypes(), mediaType)
if !ok {
return nil, fmt.Errorf("binary can't serialize %s", mediaType)
}
prettyEncoder := info.PrettySerializer
if prettyEncoder == nil {
prettyEncoder = info.Serializer
}
enc := codecs.EncoderForVersion(prettyEncoder, gv)
return enc, nil
}
func isFilename(name string) (bool, error) {
u, err := url.Parse(name)
if err != nil {
return false, err
}
// windows drive letters
if s := strings.ToLower(u.Scheme); len(s) == 1 && s[0] >= 'a' && s[0] <= 'z' {
return true, nil
}
return u.Scheme == "", nil
}
// getServicePortName obtains the SealedSecrets service port name
func getServicePortName(ctx context.Context, client corev1.CoreV1Interface, namespace, serviceName string) (string, error) {
service, err := client.Services(namespace).Get(ctx, serviceName, metav1.GetOptions{})
if err != nil {
return "", fmt.Errorf("cannot get sealed secret service: %v", err)
}
return service.Spec.Ports[0].Name, nil
}
// openCertLocal opens a cert URI or local filename, by fetching it locally from the client
// (as opposed as openCertCluster which fetches it via HTTP but through the k8s API proxy).
func openCertLocal(filenameOrURI string) (io.ReadCloser, error) {
// detect if a certificate is a local file or an URI.
if ok, err := isFilename(filenameOrURI); err != nil {
return nil, err
} else if ok {
// #nosec G304 -- should open user provided file
return os.Open(filenameOrURI)
}
return openCertURI(filenameOrURI)
}
func openCertURI(uri string) (io.ReadCloser, error) {
// support file:// scheme. Note: we're opening the file using os.Open rather
// than using the file:// scheme below because there is no point in complicating our lives
// and escape the filename properly.
t := &http.Transport{}
// #nosec: G111 -- we want to allow all files to be opened
t.RegisterProtocol("file", http.NewFileTransport(http.Dir("/")))
c := &http.Client{Transport: t}
resp, err := c.Get(uri)
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("cannot fetch %q: %s", uri, resp.Status)
}
return resp.Body, nil
}
// openCertCluster fetches a certificate by performing an HTTP request to the controller
// through the k8s API proxy.
func openCertCluster(ctx context.Context, c corev1.CoreV1Interface, namespace, name string) (io.ReadCloser, error) {
portName, err := getServicePortName(ctx, c, namespace, name)
if err != nil {
return nil, err
}
cert, err := c.Services(namespace).ProxyGet("http", name, portName, "/v1/cert.pem", nil).Stream(ctx)
if err != nil {
return nil, fmt.Errorf("cannot fetch certificate: %v", err)
}
return cert, nil
}
func OpenCert(ctx context.Context, clientConfig ClientConfig, controllerNs, controllerName string, certURL string) (io.ReadCloser, error) {
if certURL != "" {
return openCertLocal(certURL)
}
conf, err := clientConfig.ClientConfig()
if err != nil {
return nil, err
}
conf.AcceptContentTypes = "application/x-pem-file, */*"
restClient, err := corev1.NewForConfig(conf)
if err != nil {
return nil, err
}
return openCertCluster(ctx, restClient, controllerNs, controllerName)
}
// Seal reads a k8s Secret resource parsed from an input reader by a given codec, encrypts all its secrets
// with a given public key, using the name and namespace found in the input secret, unless explicitly overridden
// by the overrideName and overrideNamespace arguments.
func Seal(clientConfig ClientConfig, outputFormat string, in io.Reader, out io.Writer, codecs runtimeserializer.CodecFactory, pubKey *rsa.PublicKey, scope ssv1alpha1.SealingScope, allowEmptyData bool, overrideName, overrideNamespace string) error {
secret, err := readSecret(codecs.UniversalDecoder(), in)
if err != nil {
return err
}
if len(secret.Data) == 0 && len(secret.StringData) == 0 && !allowEmptyData {
return fmt.Errorf("secret.data is empty in input Secret, assuming this is an error and aborting. To work with empty data, --allow-empty-data can be used")
}
if overrideName != "" {
secret.Name = overrideName
}
if secret.GetName() == "" {
return fmt.Errorf("missing metadata.name in input Secret")
}
if overrideNamespace != "" {
secret.Namespace = overrideNamespace
}
if scope != ssv1alpha1.DefaultScope {
secret.Annotations = ssv1alpha1.UpdateScopeAnnotations(secret.Annotations, scope)
}
if ssv1alpha1.SecretScope(secret) != ssv1alpha1.ClusterWideScope && secret.GetNamespace() == "" {
ns, _, err := clientConfig.Namespace()
if clientcmd.IsEmptyConfig(err) {
return fmt.Errorf("input secret has no namespace and cannot infer the namespace automatically when no kube config is available")
} else if err != nil {
return err
}
secret.SetNamespace(ns)
}
// Strip read-only server-side ObjectMeta (if present)
secret.SetSelfLink("")
secret.SetUID("")
secret.SetResourceVersion("")
secret.Generation = 0
secret.SetCreationTimestamp(metav1.Time{})
secret.SetDeletionTimestamp(nil)
secret.DeletionGracePeriodSeconds = nil
ssecret, err := ssv1alpha1.NewSealedSecret(codecs, pubKey, secret)
if err != nil {
return err
}
if err = sealedSecretOutput(out, outputFormat, codecs, ssecret); err != nil {
return err
}
return nil
}
func ValidateSealedSecret(ctx context.Context, clientConfig ClientConfig, controllerNs, controllerName string, in io.Reader) error {
conf, err := clientConfig.ClientConfig()
if err != nil {
return err
}
restClient, err := corev1.NewForConfig(conf)
if err != nil {
return err
}
portName, err := getServicePortName(ctx, restClient, controllerNs, controllerName)
if err != nil {
return err
}
content, err := io.ReadAll(in)
if err != nil {
return err
}
req := restClient.RESTClient().Post().
Namespace(controllerNs).
Resource("services").
SubResource("proxy").
Name(net.JoinSchemeNamePort("http", controllerName, portName)).
Suffix("/v1/verify")
req.Body(content)
res := req.Do(ctx)
if err := res.Error(); err != nil {
if status, ok := err.(*k8serrors.StatusError); ok && status.Status().Code == http.StatusConflict {
return fmt.Errorf("unable to decrypt sealed secret")
}
return fmt.Errorf("cannot validate sealed secret: %v", err)
}
return nil
}
func ReEncryptSealedSecret(ctx context.Context, clientConfig ClientConfig, controllerNs, controllerName, outputFormat string, in io.Reader, out io.Writer, codecs runtimeserializer.CodecFactory) error {
conf, err := clientConfig.ClientConfig()
if err != nil {
return err
}
restClient, err := corev1.NewForConfig(conf)
if err != nil {
return err
}
portName, err := getServicePortName(ctx, restClient, controllerNs, controllerName)
if err != nil {
return err
}
content, err := io.ReadAll(in)
if err != nil {
return err
}
req := restClient.RESTClient().Post().
Namespace(controllerNs).
Resource("services").
SubResource("proxy").
Name(net.JoinSchemeNamePort("http", controllerName, portName)).
Suffix("/v1/rotate")
req.Body(content)
res := req.Do(ctx)
if err := res.Error(); err != nil {
if status, ok := err.(*k8serrors.StatusError); ok && status.Status().Code == http.StatusConflict {
return fmt.Errorf("unable to rotate secret")
}
return fmt.Errorf("cannot re-encrypt secret: %v", err)
}
body, err := res.Raw()
if err != nil {
return err
}
ssecret := &ssv1alpha1.SealedSecret{}
if err = json.Unmarshal(body, ssecret); err != nil {
return err
}
ssecret.SetCreationTimestamp(metav1.Time{})
ssecret.SetDeletionTimestamp(nil)
ssecret.Generation = 0
if err = sealedSecretOutput(out, outputFormat, codecs, ssecret); err != nil {
return err
}
return nil
}
func resourceOutput(out io.Writer, outputFormat string, codecs runtimeserializer.CodecFactory, gv runtime.GroupVersioner, obj runtime.Object) error {
var contentType string
switch strings.ToLower(outputFormat) {
case "json", "":
contentType = runtime.ContentTypeJSON
case "yaml":
contentType = runtime.ContentTypeYAML
default:
return fmt.Errorf("unsupported output format: %s", outputFormat)
}
prettyEnc, err := prettyEncoder(codecs, contentType, gv)
if err != nil {
return err
}
buf, err := runtime.Encode(prettyEnc, obj)
if err != nil {
return err
}
_, _ = out.Write(buf)
fmt.Fprint(out, "\n")
return nil
}
func sealedSecretOutput(out io.Writer, outputFormat string, codecs runtimeserializer.CodecFactory, ssecret *ssv1alpha1.SealedSecret) error {
return resourceOutput(out, outputFormat, codecs, ssv1alpha1.SchemeGroupVersion, ssecret)
}
func decodeSealedSecret(codecs runtimeserializer.CodecFactory, b []byte) (*ssv1alpha1.SealedSecret, error) {
var ss ssv1alpha1.SealedSecret
if err := runtime.DecodeInto(codecs.UniversalDecoder(), b, &ss); err != nil {
return nil, err
}
return &ss, nil
}
func SealMergingInto(clientConfig ClientConfig, outputFormat string, in io.Reader, filename string, codecs runtimeserializer.CodecFactory, pubKey *rsa.PublicKey, scope ssv1alpha1.SealingScope, allowEmptyData bool) error {
// #nosec G304 -- should open user provided file
f, err := os.OpenFile(filename, os.O_RDWR, 0)
if err != nil {
return err
}
// #nosec G307 -- we are explicitly managing a potential error from f.Close() at the end of the function
defer f.Close()
b, err := io.ReadAll(f)
if err != nil {
return err
}
orig, err := decodeSealedSecret(codecs, b)
if err != nil {
return err
}
var buf bytes.Buffer
if err := Seal(clientConfig, outputFormat, in, &buf, codecs, pubKey, scope, allowEmptyData, orig.Name, orig.Namespace); err != nil {
return err
}
update, err := decodeSealedSecret(codecs, buf.Bytes())
if err != nil {
return err
}
// merge encrypted data and metadata
for k, v := range update.Spec.EncryptedData {
orig.Spec.EncryptedData[k] = v
}
for k, v := range update.Spec.Template.Annotations {
orig.Spec.Template.Annotations[k] = v
}
for k, v := range update.Spec.Template.Labels {
orig.Spec.Template.Labels[k] = v
}
for k, v := range update.Spec.Template.Data {
orig.Spec.Template.Data[k] = v
}
// updated sealed secret file in-place avoiding clobbering the file upon rendering errors.
var out bytes.Buffer
if err := sealedSecretOutput(&out, outputFormat, codecs, orig); err != nil {
return err
}
if err := f.Truncate(0); err != nil {
return err
}
if _, err := f.Seek(0, 0); err != nil {
return err
}
if _, err := io.Copy(f, &out); err != nil {
return err
}
// we explicitly call f.Close() to return a potential error when closing the file that wouldn't be returned in the deferred f.Close()
if err := f.Close(); err != nil {
return err
}
return nil
}
func EncryptSecretItem(w io.Writer, secretName, ns string, data []byte, scope ssv1alpha1.SealingScope, pubKey *rsa.PublicKey) error {
// TODO(mkm): refactor cluster-wide/namespace-wide to an actual enum so we can have a simple flag
// to refer to the scope mode that is not a tuple of booleans.
label := ssv1alpha1.EncryptionLabel(ns, secretName, scope)
out, err := crypto.HybridEncrypt(rand.Reader, pubKey, data, label)
if err != nil {
return err
}
fmt.Fprint(w, base64.StdEncoding.EncodeToString(out))
return nil
}
// parseFromFile parses a value of the kubectl --from-file flag, which can optionally include an item name
// preceding the first equals sign.
func ParseFromFile(s string) (string, string) {
c := strings.SplitN(s, "=", 2)
if len(c) == 1 {
return "", c[0]
}
return c[0], c[1]
}
func readPrivKeysFromFile(filename string) ([]*rsa.PrivateKey, error) {
// #nosec G304 -- should open user provided file
b, err := os.ReadFile(filename)
if err != nil {
return nil, err
}
res, err := parsePrivKey(b)
if err == nil {
return []*rsa.PrivateKey{res}, nil
}
var secrets []*v1.Secret
// try to parse it as json/yaml encoded v1.List of secrets
var lst v1.List
if err = runtime.DecodeInto(scheme.Codecs.UniversalDecoder(), b, &lst); err == nil {
for _, r := range lst.Items {
s, err := readSecret(scheme.Codecs.UniversalDecoder(), bytes.NewBuffer(r.Raw))
if err != nil {
return nil, err
}
secrets = append(secrets, s)
}
} else {
// try to parse it as json/yaml encoded secret
s, err := readSecret(scheme.Codecs.UniversalDecoder(), bytes.NewBuffer(b))
if err != nil {
return nil, err
}
secrets = append(secrets, s)
}
var keys []*rsa.PrivateKey
for _, s := range secrets {
tlsKey, ok := s.Data["tls.key"]
if !ok {
return nil, fmt.Errorf("secret must contain a 'tls.data' key")
}
pk, err := parsePrivKey(tlsKey)
if err != nil {
return nil, err
}
keys = append(keys, pk)
}
return keys, nil
}
func readPrivKey(filename string) (*rsa.PrivateKey, error) {
pks, err := readPrivKeysFromFile(filename)
if err != nil {
return nil, err
}
return pks[0], nil
}
func parsePrivKey(b []byte) (*rsa.PrivateKey, error) {
key, err := keyutil.ParsePrivateKeyPEM(b)
if err != nil {
return nil, err
}
switch rsaKey := key.(type) {
case *rsa.PrivateKey:
return rsaKey, nil
default:
return nil, fmt.Errorf("unexpected private key type %T", key)
}
}
func readPrivKeys(filenames []string) (map[string]*rsa.PrivateKey, error) {
res := map[string]*rsa.PrivateKey{}
for _, filename := range filenames {
pks, err := readPrivKeysFromFile(filename)
if err != nil {
return nil, err
}
for _, pk := range pks {
fingerprint, err := crypto.PublicKeyFingerprint(&pk.PublicKey)
if err != nil {
return nil, err
}
res[fingerprint] = pk
}
}
return res, nil
}
func UnsealSealedSecret(w io.Writer, in io.Reader, privKeysFilenames []string, outputFormat string, codecs runtimeserializer.CodecFactory) error {
privKeys, err := readPrivKeys(privKeysFilenames)
if err != nil {
return err
}
b, err := io.ReadAll(in)
if err != nil {
return err
}
ss, err := decodeSealedSecret(codecs, b)
if err != nil {
return err
}
sec, err := ss.Unseal(codecs, privKeys)
if err != nil {
return err
}
return resourceOutput(w, outputFormat, codecs, v1.SchemeGroupVersion, sec)
}