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Merge pull request #48574 from sakshamsharma/kms-transformer
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Add Google cloud KMS service for envelope encryption transformer

This adds the required pieces which will allow addition of KMS based encryption providers (envelope transformer).

For now, we will be implementing it using Google Cloud KMS, but the code should make it easy to add support for any other such provider which can expose Decrypt and Encrypt calls.

Writing tests for Google Cloud KMS Service may cause a significant overhead to the testing framework. It has been tested locally and on GKE though.

Upcoming after this PR:
* Complete implementation of the envelope transformer, which uses LRU cache to maintain decrypted DEKs in memory.
* Track key version to assist in data re-encryption after a KEK rotation.

Development branch containing the changes described above: sakshamsharma#4

Envelope transformer used by this PR was merged in #49350 

Concerns #48522 

Planned configuration:
```
kind: EncryptionConfig
apiVersion: v1
resources:
  - resources:
    - secrets
    providers:
    - kms:
        cachesize: 100
        configfile: gcp-cloudkms.conf
        name: gcp-cloudkms
    - identity: {}
```

gcp-cloudkms.conf:
```
[GoogleCloudKMS]
    kms-location: global
    kms-keyring: google-container-engine
    kms-cryptokey: example-key
```
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Kubernetes Submit Queue committed Aug 29, 2017
2 parents ce55939 + 3e11baf commit 0d17e9d
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Showing 9 changed files with 214 additions and 123 deletions.
4 changes: 4 additions & 0 deletions cluster/gce/gci/configure-helper.sh
Original file line number Diff line number Diff line change
Expand Up @@ -1457,6 +1457,10 @@ function start-kube-apiserver {

if [[ -n "${ENCRYPTION_PROVIDER_CONFIG:-}" ]]; then
local encryption_provider_config_path="/etc/srv/kubernetes/encryption-provider-config.yml"
if [[ -n "${GOOGLE_CLOUD_KMS_CONFIG_FILE_NAME:-}" && -n "${GOOGLE_CLOUD_KMS_CONFIG:-}" ]]; then
echo "${GOOGLE_CLOUD_KMS_CONFIG}" | base64 --decode > "${GOOGLE_CLOUD_KMS_CONFIG_FILE_NAME}"
fi

echo "${ENCRYPTION_PROVIDER_CONFIG}" | base64 --decode > "${encryption_provider_config_path}"
params+=" --experimental-encryption-provider-config=${encryption_provider_config_path}"
fi
Expand Down
13 changes: 11 additions & 2 deletions cmd/kube-apiserver/app/server.go
Original file line number Diff line number Diff line change
Expand Up @@ -259,6 +259,14 @@ func CreateKubeAPIServerConfig(s *options.ServerRunOptions, nodeTunneler tunnele
return nil, nil, nil, nil, nil, utilerrors.NewAggregate(errs)
}

if s.CloudProvider != nil {
// Initialize the cloudprovider once, to give it a chance to register KMS plugins, if any.
_, err := cloudprovider.InitCloudProvider(s.CloudProvider.CloudProvider, s.CloudProvider.CloudConfigFile)
if err != nil {
return nil, nil, nil, nil, nil, err
}
}

genericConfig, sharedInformers, versionedInformers, insecureServingOptions, serviceResolver, err := BuildGenericConfig(s)
if err != nil {
return nil, nil, nil, nil, nil, err
Expand Down Expand Up @@ -539,7 +547,8 @@ func BuildAuthorizer(s *options.ServerRunOptions, sharedInformers informers.Shar
return authorizationConfig.New()
}

// BuildStorageFactory constructs the storage factory
// BuildStorageFactory constructs the storage factory. If encryption at rest is used, it expects
// all supported KMS plugins to be registered in the KMS plugin registry before being called.
func BuildStorageFactory(s *options.ServerRunOptions) (*serverstorage.DefaultStorageFactory, error) {
storageGroupsToEncodingVersion, err := s.StorageSerialization.StorageGroupsToEncodingVersion()
if err != nil {
Expand Down Expand Up @@ -581,7 +590,7 @@ func BuildStorageFactory(s *options.ServerRunOptions) (*serverstorage.DefaultSto
storageFactory.SetEtcdLocation(groupResource, servers)
}

if s.Etcd.EncryptionProviderConfigFilepath != "" {
if len(s.Etcd.EncryptionProviderConfigFilepath) != 0 {
transformerOverrides, err := encryptionconfig.GetTransformerOverrides(s.Etcd.EncryptionProviderConfigFilepath)
if err != nil {
return nil, err
Expand Down
3 changes: 3 additions & 0 deletions pkg/cloudprovider/providers/gce/BUILD
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ go_library(
"gce_urlmap.go",
"gce_util.go",
"gce_zones.go",
"kms.go",
"metrics.go",
"token_source.go",
],
Expand Down Expand Up @@ -71,6 +72,8 @@ go_library(
"//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/watch:go_default_library",
"//vendor/k8s.io/apiserver/pkg/server/options/encryptionconfig:go_default_library",
"//vendor/k8s.io/apiserver/pkg/storage/value/encrypt/envelope:go_default_library",
"//vendor/k8s.io/client-go/kubernetes:go_default_library",
"//vendor/k8s.io/client-go/tools/cache:go_default_library",
"//vendor/k8s.io/client-go/util/flowcontrol:go_default_library",
Expand Down
15 changes: 15 additions & 0 deletions pkg/cloudprovider/providers/gce/gce.go
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@ import (

"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/apiserver/pkg/server/options/encryptionconfig"
"k8s.io/apiserver/pkg/storage/value/encrypt/envelope"
"k8s.io/client-go/util/flowcontrol"
"k8s.io/kubernetes/pkg/cloudprovider"
"k8s.io/kubernetes/pkg/controller"
Expand Down Expand Up @@ -199,6 +201,10 @@ type CloudConfig struct {
AlphaFeatureGate *AlphaFeatureGate
}

// kmsPluginRegisterOnce prevents the cloudprovider from registering its KMS plugin
// more than once in the KMS plugin registry.
var kmsPluginRegisterOnce sync.Once

func init() {
cloudprovider.RegisterCloudProvider(
ProviderName,
Expand Down Expand Up @@ -462,6 +468,15 @@ func CreateGCECloud(config *CloudConfig) (*GCECloud, error) {
}

gce.manager = &GCEServiceManager{gce}

// Registering the KMS plugin only the first time.
kmsPluginRegisterOnce.Do(func() {
// Register the Google Cloud KMS based service in the KMS plugin registry.
encryptionconfig.KMSPluginRegistry.Register(KMSServiceName, func(config io.Reader) (envelope.Service, error) {
return gce.getGCPCloudKMSService(config)
})
})

return gce, nil
}

Expand Down
167 changes: 167 additions & 0 deletions pkg/cloudprovider/providers/gce/kms.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,167 @@
/*
Copyright 2017 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package gce

import (
"encoding/base64"
"fmt"
"io"

"github.com/golang/glog"
cloudkms "google.golang.org/api/cloudkms/v1"
"google.golang.org/api/googleapi"
gcfg "gopkg.in/gcfg.v1"
"k8s.io/apiserver/pkg/storage/value/encrypt/envelope"
)

const (
// KMSServiceName is the name of the cloudkms provider registered by this cloud.
KMSServiceName = "gcp-cloudkms"

defaultGKMSKeyRing = "google-container-engine"
defaultGKMSKeyRingLocation = "global"
)

// gkmsConfig contains the GCE specific KMS configuration for setting up a KMS connection.
type gkmsConfig struct {
Global struct {
// location is the KMS location of the KeyRing to be used for encryption.
// It can be found by checking the available KeyRings in the IAM UI.
// This is not the same as the GCP location of the project.
// +optional
Location string `gcfg:"kms-location"`
// keyRing is the keyRing of the hosted key to be used. The default value is "google-kubernetes".
// +optional
KeyRing string `gcfg:"kms-keyring"`
// cryptoKey is the name of the key to be used for encryption of Data-Encryption-Keys.
CryptoKey string `gcfg:"kms-cryptokey"`
}
}

// readGCPCloudKMSConfig parses and returns the configuration parameters for Google Cloud KMS.
func readGCPCloudKMSConfig(reader io.Reader) (*gkmsConfig, error) {
cfg := &gkmsConfig{}
if err := gcfg.FatalOnly(gcfg.ReadInto(cfg, reader)); err != nil {
glog.Errorf("Couldn't read Google Cloud KMS config: %v", err)
return nil, err
}
return cfg, nil
}

// gkmsService provides Encrypt and Decrypt methods which allow cryptographic operations
// using Google Cloud KMS service.
type gkmsService struct {
parentName string
cloudkmsService *cloudkms.Service
}

// getGCPCloudKMSService provides a Google Cloud KMS based implementation of envelope.Service.
func (gce *GCECloud) getGCPCloudKMSService(config io.Reader) (envelope.Service, error) {
kmsConfig, err := readGCPCloudKMSConfig(config)
if err != nil {
return nil, err
}

// Hosting on GCE/GKE with Google KMS encryption provider
cloudkmsService := gce.GetKMSService()

// Set defaults for location and keyRing.
location := kmsConfig.Global.Location
if len(location) == 0 {
location = defaultGKMSKeyRingLocation
}
keyRing := kmsConfig.Global.KeyRing
if len(keyRing) == 0 {
keyRing = defaultGKMSKeyRing
}

cryptoKey := kmsConfig.Global.CryptoKey
if len(cryptoKey) == 0 {
return nil, fmt.Errorf("missing cryptoKey for cloudprovided KMS: " + KMSServiceName)
}

parentName := fmt.Sprintf("projects/%s/locations/%s", gce.projectID, location)

// Create the keyRing if it does not exist yet
_, err = cloudkmsService.Projects.Locations.KeyRings.Create(parentName,
&cloudkms.KeyRing{}).KeyRingId(keyRing).Do()
if err != nil && unrecoverableCreationError(err) {
return nil, err
}
parentName = parentName + "/keyRings/" + keyRing

// Create the cryptoKey if it does not exist yet
_, err = cloudkmsService.Projects.Locations.KeyRings.CryptoKeys.Create(parentName,
&cloudkms.CryptoKey{
Purpose: "ENCRYPT_DECRYPT",
}).CryptoKeyId(cryptoKey).Do()
if err != nil && unrecoverableCreationError(err) {
return nil, err
}
parentName = parentName + "/cryptoKeys/" + cryptoKey

service := &gkmsService{
parentName: parentName,
cloudkmsService: cloudkmsService,
}

// Sanity check before startup. For non-GCP clusters, the user's account may not have permissions to create
// the key. We need to verify the existence of the key before apiserver startup.
_, err = service.Encrypt([]byte("test"))
if err != nil {
return nil, fmt.Errorf("failed to encrypt data using Google cloudkms, using key %s. Ensure that the keyRing and cryptoKey exist. Got error: %v", parentName, err)
}

return service, nil
}

// Decrypt decrypts a base64 representation of encrypted bytes.
func (t *gkmsService) Decrypt(data string) ([]byte, error) {
resp, err := t.cloudkmsService.Projects.Locations.KeyRings.CryptoKeys.
Decrypt(t.parentName, &cloudkms.DecryptRequest{
Ciphertext: data,
}).Do()
if err != nil {
return nil, err
}
return base64.StdEncoding.DecodeString(resp.Plaintext)
}

// Encrypt encrypts bytes, and returns base64 representation of the ciphertext.
func (t *gkmsService) Encrypt(data []byte) (string, error) {
resp, err := t.cloudkmsService.Projects.Locations.KeyRings.CryptoKeys.
Encrypt(t.parentName, &cloudkms.EncryptRequest{
Plaintext: base64.StdEncoding.EncodeToString(data),
}).Do()
if err != nil {
return "", err
}
return resp.Ciphertext, nil
}

// unrecoverableCreationError decides if Kubernetes should ignore the encountered Google KMS
// error. Only to be used for errors seen while creating a KeyRing or CryptoKey.
func unrecoverableCreationError(err error) bool {
apiError, isAPIError := err.(*googleapi.Error)
// 409 means the object exists.
// 403 means we do not have permission to create the object, the user must do it.
// Else, it is an unrecoverable error.
if !isAPIError || (apiError.Code != 409 && apiError.Code != 403) {
return true
}
return false
}
Original file line number Diff line number Diff line change
Expand Up @@ -36,11 +36,10 @@ import (
)

const (
aesCBCTransformerPrefixV1 = "k8s:enc:aescbc:v1:"
aesGCMTransformerPrefixV1 = "k8s:enc:aesgcm:v1:"
secretboxTransformerPrefixV1 = "k8s:enc:secretbox:v1:"
kmsTransformerPrefixV1 = "k8s:enc:kms:v1:"
cloudProvidedKMSTransformerPrefixV1 = "k8s:enc:cloudprovidedkms:v1:"
aesCBCTransformerPrefixV1 = "k8s:enc:aescbc:v1:"
aesGCMTransformerPrefixV1 = "k8s:enc:aesgcm:v1:"
secretboxTransformerPrefixV1 = "k8s:enc:secretbox:v1:"
kmsTransformerPrefixV1 = "k8s:enc:kms:v1:"
)

// GetTransformerOverrides returns the transformer overrides by reading and parsing the encryption provider configuration file
Expand Down Expand Up @@ -163,19 +162,7 @@ func GetPrefixTransformers(config *ResourceConfig) ([]value.PrefixTransformer, e
if pluginFound == false {
return nil, fmt.Errorf("KMS plugin %q not found", provider.KMS.Name)
}
transformer, err = getEnvelopePrefixTransformer(provider.KMS.CoreKMSConfig, envelopeService, kmsTransformerPrefixV1)
found = true
}

if provider.CloudProvidedKMS != nil {
if found == true {
return nil, fmt.Errorf("more than one provider specified in a single element, should split into different list elements")
}
envelopeService, err := KMSPluginRegistry.getCloudProvidedPlugin(provider.CloudProvidedKMS.Name)
if err != nil {
return nil, fmt.Errorf("could not configure Cloud-Provided KMS plugin %q, %v", provider.CloudProvidedKMS.Name, err)
}
transformer, err = getEnvelopePrefixTransformer(provider.CloudProvidedKMS.CoreKMSConfig, envelopeService, cloudProvidedKMSTransformerPrefixV1)
transformer, err = getEnvelopePrefixTransformer(provider.KMS, envelopeService, kmsTransformerPrefixV1)
found = true
}

Expand Down Expand Up @@ -296,7 +283,7 @@ func GetSecretboxPrefixTransformer(config *SecretboxConfig) (value.PrefixTransfo

// getEnvelopePrefixTransformer returns a prefix transformer from the provided config.
// envelopeService is used as the root of trust.
func getEnvelopePrefixTransformer(config *CoreKMSConfig, envelopeService envelope.Service, prefix string) (value.PrefixTransformer, error) {
func getEnvelopePrefixTransformer(config *KMSConfig, envelopeService envelope.Service, prefix string) (value.PrefixTransformer, error) {
envelopeTransformer, err := envelope.NewEnvelopeTransformer(envelopeService, config.CacheSize, aestransformer.NewCBCTransformer)
if err != nil {
return value.PrefixTransformer{}, err
Expand Down

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