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252 lines (230 loc) · 7.71 KB
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// Minio Cloud Storage, (C) 2015, 2016, 2017, 2018 Minio, Inc.
//
// 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 crypto
import (
"bytes"
"encoding/base64"
"errors"
"fmt"
"strings"
"time"
vault "github.com/hashicorp/vault/api"
)
var (
//ErrKMSAuthLogin is raised when there is a failure authenticating to KMS
ErrKMSAuthLogin = errors.New("Vault service did not return auth info")
)
// VaultKey represents vault encryption key-ring.
type VaultKey struct {
Name string `json:"name"` // The name of the encryption key-ring
Version int `json:"version"` // The key version
}
// VaultAuth represents vault authentication type.
// Currently the only supported authentication type is AppRole.
type VaultAuth struct {
Type string `json:"type"` // The authentication type
AppRole VaultAppRole `json:"approle"` // The AppRole authentication credentials
}
// VaultAppRole represents vault AppRole authentication credentials
type VaultAppRole struct {
ID string `json:"id"` // The AppRole access ID
Secret string `json:"secret"` // The AppRole secret
}
// VaultConfig represents vault configuration.
type VaultConfig struct {
Endpoint string `json:"endpoint"` // The vault API endpoint as URL
CAPath string `json:"-"` // The path to PEM-encoded certificate files used for mTLS. Currently not used in config file.
Auth VaultAuth `json:"auth"` // The vault authentication configuration
Key VaultKey `json:"key-id"` // The named key used for key-generation / decryption.
Namespace string `json:"-"` // The vault namespace of enterprise vault instances
}
// vaultService represents a connection to a vault KMS.
type vaultService struct {
config *VaultConfig
client *vault.Client
secret *vault.Secret
leaseDuration time.Duration
}
var _ KMS = (*vaultService)(nil) // compiler check that *vaultService implements KMS
// empty/default vault configuration used to check whether a particular is empty.
var emptyVaultConfig = VaultConfig{}
// IsEmpty returns true if the vault config struct is an
// empty configuration.
func (v *VaultConfig) IsEmpty() bool { return *v == emptyVaultConfig }
// Verify returns a nil error if the vault configuration
// is valid. A valid configuration is either empty or
// contains valid non-default values.
func (v *VaultConfig) Verify() (err error) {
if v.IsEmpty() {
return // an empty configuration is valid
}
switch {
case v.Endpoint == "":
err = errors.New("crypto: missing hashicorp vault endpoint")
case strings.ToLower(v.Auth.Type) != "approle":
err = fmt.Errorf("crypto: invalid hashicorp vault authentication type: %s is not supported", v.Auth.Type)
case v.Auth.AppRole.ID == "":
err = errors.New("crypto: missing hashicorp vault AppRole ID")
case v.Auth.AppRole.Secret == "":
err = errors.New("crypto: missing hashicorp vault AppSecret ID")
case v.Key.Name == "":
err = errors.New("crypto: missing hashicorp vault key name")
case v.Key.Version < 0:
err = errors.New("crypto: invalid hashicorp vault key version: The key version must not be negative")
}
return
}
// NewVault initializes Hashicorp Vault KMS by authenticating
// to Vault with the credentials in config and gets a client
// token for future api calls.
func NewVault(config VaultConfig) (KMS, error) {
if config.IsEmpty() {
return nil, errors.New("crypto: the hashicorp vault configuration must not be empty")
}
if err := config.Verify(); err != nil {
return nil, err
}
vaultCfg := vault.Config{Address: config.Endpoint}
if err := vaultCfg.ConfigureTLS(&vault.TLSConfig{CAPath: config.CAPath}); err != nil {
return nil, err
}
client, err := vault.NewClient(&vaultCfg)
if err != nil {
return nil, err
}
if config.Namespace != "" {
client.SetNamespace(config.Namespace)
}
v := &vaultService{client: client, config: &config}
if err := v.authenticate(); err != nil {
return nil, err
}
v.renewToken()
return v, nil
}
// renewToken starts a new go-routine which renews
// the vault authentication token periodically and re-authenticates
// if the token renewal fails
func (v *vaultService) renewToken() {
retryDelay := v.leaseDuration / 2
go func() {
for {
if v.secret == nil {
if err := v.authenticate(); err != nil {
time.Sleep(retryDelay)
continue
}
}
s, err := v.client.Auth().Token().RenewSelf(int(v.leaseDuration))
if err != nil || s == nil {
v.secret = nil
time.Sleep(retryDelay)
continue
}
if ok, err := s.TokenIsRenewable(); !ok || err != nil {
v.secret = nil
continue
}
ttl, err := s.TokenTTL()
if err != nil {
v.secret = nil
continue
}
v.secret = s
retryDelay = ttl / 2
time.Sleep(retryDelay)
}
}()
}
// authenticate logs the app to vault, and starts the auto renewer
// before secret expires
func (v *vaultService) authenticate() (err error) {
payload := map[string]interface{}{
"role_id": v.config.Auth.AppRole.ID,
"secret_id": v.config.Auth.AppRole.Secret,
}
var tokenID string
var ttl time.Duration
var secret *vault.Secret
secret, err = v.client.Logical().Write("auth/approle/login", payload)
if err != nil {
return
}
if secret == nil {
err = ErrKMSAuthLogin
return
}
tokenID, err = secret.TokenID()
if err != nil {
err = ErrKMSAuthLogin
return
}
ttl, err = secret.TokenTTL()
if err != nil {
err = ErrKMSAuthLogin
return
}
v.client.SetToken(tokenID)
v.secret = secret
v.leaseDuration = ttl
return
}
// GenerateKey returns a new plaintext key, generated by the KMS,
// and a sealed version of this plaintext key encrypted using the
// named key referenced by keyID. It also binds the generated key
// cryptographically to the provided context.
func (v *vaultService) GenerateKey(keyID string, ctx Context) (key [32]byte, sealedKey []byte, err error) {
var contextStream bytes.Buffer
ctx.WriteTo(&contextStream)
payload := map[string]interface{}{
"context": base64.StdEncoding.EncodeToString(contextStream.Bytes()),
}
s, err := v.client.Logical().Write(fmt.Sprintf("/transit/datakey/plaintext/%s", keyID), payload)
if err != nil {
return key, sealedKey, err
}
sealKey := s.Data["ciphertext"].(string)
plainKey, err := base64.StdEncoding.DecodeString(s.Data["plaintext"].(string))
if err != nil {
return key, sealedKey, err
}
copy(key[:], []byte(plainKey))
return key, []byte(sealKey), nil
}
// UnsealKey returns the decrypted sealedKey as plaintext key.
// Therefore it sends the sealedKey to the KMS which decrypts
// it using the named key referenced by keyID and responses with
// the plaintext key.
//
// The context must be same context as the one provided while
// generating the plaintext key / sealedKey.
func (v *vaultService) UnsealKey(keyID string, sealedKey []byte, ctx Context) (key [32]byte, err error) {
var contextStream bytes.Buffer
ctx.WriteTo(&contextStream)
payload := map[string]interface{}{
"ciphertext": string(sealedKey),
"context": base64.StdEncoding.EncodeToString(contextStream.Bytes()),
}
s, err := v.client.Logical().Write(fmt.Sprintf("/transit/decrypt/%s", keyID), payload)
if err != nil {
return key, err
}
base64Key := s.Data["plaintext"].(string)
plainKey, err := base64.StdEncoding.DecodeString(base64Key)
if err != nil {
return key, err
}
copy(key[:], []byte(plainKey))
return key, nil
}