move cloud KMS providers to an external plugin

docs/kms.md

@@ -9,8 +9,6 @@ The `secrets` section of the `kms` configuration allows to configure how to encr
 - `url` defines the URI to the KMS service
 - `master_key_path` defines the absolute path to a file containing the master encryption key. This could be, for example, a docker secrets or a file protected with filesystem level permissions.
 
-We use [Go CDK](https://gocloud.dev/howto/secrets/) to access several key management services in a portable way.
-
 ### Local provider
 
 If the `url` is empty SFTPGo uses local encryption for keeping secrets. Internally, it uses the [NaCl secret box](https://pkg.go.dev/golang.org/x/crypto/nacl/secretbox) algorithm to perform encryption and authentication.
@@ -22,41 +20,9 @@ We first generate a random key, then the per-object encryption key is derived fr
 
 For compatibility with SFTPGo versions 1.2.x and before we also support encryption based on `AES-256-GCM`. The data encrypted with this algorithm will never use the master key to keep backward compatibility.
 
-### Google Cloud Key Management Service
+### Cloud providers
 
-To use keys from Google Cloud Platform’s [Key Management Service](https://cloud.google.com/kms/) (GCP KMS) you have to use `gcpkms` as URL scheme like this:
+Several cloud providers are supported using the [sftpgo-plugin-kms](https://github.com/sftpgo/sftpgo-plugin-kms).
-
-```shell
-gcpkms://projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[KEY_RING]/cryptoKeys/[KEY]
-```
-
-SFTPGo will use Application Default Credentials. See [here](https://cloud.google.com/docs/authentication/production) for alternatives such as environment variables.
-
-The URL host+path are used as the key resource ID; see [here](https://cloud.google.com/kms/docs/object-hierarchy#key) for more details.
-
-If a master key is provided we first encrypt the plaintext data using the local provider and then we encrypt the resulting payload using the Cloud provider and store this ciphertext.
-
-### AWS Key Management Service
-
-To use customer master keys from Amazon Web Service’s [Key Management Service](https://aws.amazon.com/kms/) (AWS KMS) you have to use `awskms` as URL scheme. You can use the key’s ID, alias, or Amazon Resource Name (ARN) to identify the key. You should specify the region query parameter to ensure your application connects to the correct region.
-
-Here are some examples:
-
-- By ID: `awskms://1234abcd-12ab-34cd-56ef-1234567890ab?region=us-east-1`
-- By alias: `awskms://alias/ExampleAlias?region=us-east-1`
-- By ARN: `arn:aws:kms:us-east-1:111122223333:key/1234abcd-12ab-34bc-56ef-1234567890ab?region=us-east-1`
-
-SFTPGo will use the default AWS session. See [AWS Session](https://docs.aws.amazon.com/sdk-for-go/api/aws/session/) to learn about authentication alternatives such as environment variables.
-
-If a master key is provided we first encrypt the plaintext data using the local provider and then we encrypt the resulting payload using the Cloud provider and store this ciphertext.
-
-### HashiCorp Vault
-
-To use the [transit secrets engine](https://www.vaultproject.io/docs/secrets/transit/index.html) in [Vault](https://www.vaultproject.io/) you have to use `hashivault` as URL scheme like this: `hashivault://mykey`.
-
-The Vault server endpoint and authentication token are specified using the environment variables `VAULT_SERVER_URL` and `VAULT_SERVER_TOKEN`, respectively.
-
-If a master key is provided we first encrypt the plaintext data using the local provider and then we encrypt the resulting payload using Vault and store this ciphertext.
 
 ### Notes
 

kms/aws/aws.go

@@ -1,67 +0,0 @@
-// +build !noawskms
-
-package aws
-
-import (
-	// we import awskms here to be able to disable AWS KMS support using a build tag
-	_ "gocloud.dev/secrets/awskms"
-
-	"github.com/drakkan/sftpgo/v2/kms"
-	"github.com/drakkan/sftpgo/v2/kms/gocloud"
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-const encryptedStatus = kms.SecretStatusAWS
-
-type awsSecret struct {
-	gocloud.Secret
-}
-
-func init() {
-	version.AddFeature("+awskms")
-	kms.RegisterSecretProvider(kms.SchemeAWS, encryptedStatus, newAWSSecret)
-}
-
-func newAWSSecret(base kms.BaseSecret, url, masterKey string) kms.SecretProvider {
-	return &awsSecret{
-		gocloud.Secret{
-			BaseSecret: base,
-			URL:        url,
-			MasterKey:  masterKey,
-		},
-	}
-}
-
-func (s *awsSecret) Name() string {
-	return "AWS"
-}
-
-func (s *awsSecret) IsEncrypted() bool {
-	return s.Status == encryptedStatus
-}
-
-func (s *awsSecret) Encrypt() error {
-	if err := s.Secret.Encrypt(); err != nil {
-		return err
-	}
-	s.Status = encryptedStatus
-	return nil
-}
-
-func (s *awsSecret) Decrypt() error {
-	if !s.IsEncrypted() {
-		return kms.ErrWrongSecretStatus
-	}
-	return s.Secret.Decrypt()
-}
-
-func (s *awsSecret) Clone() kms.SecretProvider {
-	baseSecret := kms.BaseSecret{
-		Status:         s.Status,
-		Payload:        s.Payload,
-		Key:            s.Key,
-		AdditionalData: s.AdditionalData,
-		Mode:           s.Mode,
-	}
-	return newAWSSecret(baseSecret, s.URL, s.MasterKey)
-}

kms/aws/aws_disabled.go

@@ -1,11 +0,0 @@
-// +build noawskms
-
-package aws
-
-import (
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-func init() {
-	version.AddFeature("-awskms")
-}

kms/gcp/gcp.go

@@ -1,67 +0,0 @@
-// +build !nogcpkms
-
-package gcp
-
-import (
-	// we import gcpkms here to be able to disable GCP KMS support using a build tag
-	_ "gocloud.dev/secrets/gcpkms"
-
-	"github.com/drakkan/sftpgo/v2/kms"
-	"github.com/drakkan/sftpgo/v2/kms/gocloud"
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-const encryptedStatus = kms.SecretStatusGCP
-
-type gcpSecret struct {
-	gocloud.Secret
-}
-
-func init() {
-	version.AddFeature("+gcpkms")
-	kms.RegisterSecretProvider(kms.SchemeGCP, encryptedStatus, newGCPSecret)
-}
-
-func newGCPSecret(base kms.BaseSecret, url, masterKey string) kms.SecretProvider {
-	return &gcpSecret{
-		gocloud.Secret{
-			BaseSecret: base,
-			URL:        url,
-			MasterKey:  masterKey,
-		},
-	}
-}
-
-func (s *gcpSecret) Name() string {
-	return "GCP"
-}
-
-func (s *gcpSecret) IsEncrypted() bool {
-	return s.Status == encryptedStatus
-}
-
-func (s *gcpSecret) Encrypt() error {
-	if err := s.Secret.Encrypt(); err != nil {
-		return err
-	}
-	s.Status = encryptedStatus
-	return nil
-}
-
-func (s *gcpSecret) Decrypt() error {
-	if !s.IsEncrypted() {
-		return kms.ErrWrongSecretStatus
-	}
-	return s.Secret.Decrypt()
-}
-
-func (s *gcpSecret) Clone() kms.SecretProvider {
-	baseSecret := kms.BaseSecret{
-		Status:         s.Status,
-		Payload:        s.Payload,
-		Key:            s.Key,
-		AdditionalData: s.AdditionalData,
-		Mode:           s.Mode,
-	}
-	return newGCPSecret(baseSecret, s.URL, s.MasterKey)
-}

kms/gcp/gcp_disabled.go

@@ -1,11 +0,0 @@
-// +build nogcpkms
-
-package gcp
-
-import (
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-func init() {
-	version.AddFeature("-gcpkms")
-}

kms/gocloud/gocloud.go

@@ -1,105 +0,0 @@
-package gocloud
-
-import (
-	"context"
-	"encoding/base64"
-	"time"
-
-	"gocloud.dev/secrets"
-
-	"github.com/drakkan/sftpgo/v2/kms"
-)
-
-const (
-	defaultTimeout = 10 * time.Second
-)
-
-// Secret defines common methods for go-cloud based kms
-type Secret struct {
-	kms.BaseSecret
-	MasterKey string
-	URL       string
-}
-
-func (s *Secret) Encrypt() error {
-	if s.Status != kms.SecretStatusPlain {
-		return kms.ErrWrongSecretStatus
-	}
-	if s.Payload == "" {
-		return kms.ErrInvalidSecret
-	}
-
-	payload := s.Payload
-	key := ""
-	mode := 0
-	if s.MasterKey != "" {
-		localSecret := kms.NewLocalSecret(s.BaseSecret, "", s.MasterKey)
-		err := localSecret.Encrypt()
-		if err != nil {
-			return err
-		}
-		payload = localSecret.GetPayload()
-		key = localSecret.GetKey()
-		mode = localSecret.GetMode()
-	}
-
-	ctx, cancelFn := context.WithDeadline(context.Background(), time.Now().Add(defaultTimeout))
-	defer cancelFn()
-
-	keeper, err := secrets.OpenKeeper(ctx, s.URL)
-	if err != nil {
-		return err
-	}
-
-	defer keeper.Close()
-	ciphertext, err := keeper.Encrypt(context.Background(), []byte(payload))
-	if err != nil {
-		return err
-	}
-	s.Payload = base64.StdEncoding.EncodeToString(ciphertext)
-	s.Key = key
-	s.Mode = mode
-	return nil
-}
-
-func (s *Secret) Decrypt() error {
-	encrypted, err := base64.StdEncoding.DecodeString(s.Payload)
-	if err != nil {
-		return err
-	}
-	ctx, cancelFn := context.WithDeadline(context.Background(), time.Now().Add(defaultTimeout))
-	defer cancelFn()
-
-	keeper, err := secrets.OpenKeeper(ctx, s.URL)
-	if err != nil {
-		return err
-	}
-
-	defer keeper.Close()
-	plaintext, err := keeper.Decrypt(context.Background(), encrypted)
-	if err != nil {
-		return err
-	}
-	payload := string(plaintext)
-	if s.Key != "" {
-		baseSecret := kms.BaseSecret{
-			Status:         kms.SecretStatusSecretBox,
-			Payload:        payload,
-			Key:            s.Key,
-			AdditionalData: s.AdditionalData,
-			Mode:           s.Mode,
-		}
-		localSecret := kms.NewLocalSecret(baseSecret, "", s.MasterKey)
-		err = localSecret.Decrypt()
-		if err != nil {
-			return err
-		}
-		payload = localSecret.GetPayload()
-	}
-	s.Status = kms.SecretStatusPlain
-	s.Payload = payload
-	s.Key = ""
-	s.AdditionalData = ""
-	s.Mode = 0
-	return nil
-}

kms/kms.go

@@ -171,6 +171,7 @@ func (c *Configuration) getSecretProvider(base BaseSecret) SecretProvider {
 			return v.newFn(base, c.Secrets.URL, c.Secrets.masterKey)
 		}
 	}
+	logger.Warn(logSender, "", "no secret provider registered for URL %v, fallback to local provider", c.Secrets.URL)
 	return NewLocalSecret(base, c.Secrets.URL, c.Secrets.masterKey)
 }
 

kms/vault/vault.go

@@ -1,67 +0,0 @@
-// +build !novaultkms
-
-package vault
-
-import (
-	// we import hashivault here to be able to disable Vault support using a build tag
-	_ "gocloud.dev/secrets/hashivault"
-
-	"github.com/drakkan/sftpgo/v2/kms"
-	"github.com/drakkan/sftpgo/v2/kms/gocloud"
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-const encryptedStatus = kms.SecretStatusVaultTransit
-
-type vaultSecret struct {
-	gocloud.Secret
-}
-
-func init() {
-	version.AddFeature("+vaultkms")
-	kms.RegisterSecretProvider(kms.SchemeVaultTransit, encryptedStatus, newVaultSecret)
-}
-
-func newVaultSecret(base kms.BaseSecret, url, masterKey string) kms.SecretProvider {
-	return &vaultSecret{
-		gocloud.Secret{
-			BaseSecret: base,
-			URL:        url,
-			MasterKey:  masterKey,
-		},
-	}
-}
-
-func (s *vaultSecret) Name() string {
-	return "VaultTransit"
-}
-
-func (s *vaultSecret) IsEncrypted() bool {
-	return s.Status == encryptedStatus
-}
-
-func (s *vaultSecret) Encrypt() error {
-	if err := s.Secret.Encrypt(); err != nil {
-		return err
-	}
-	s.Status = encryptedStatus
-	return nil
-}
-
-func (s *vaultSecret) Decrypt() error {
-	if !s.IsEncrypted() {
-		return kms.ErrWrongSecretStatus
-	}
-	return s.Secret.Decrypt()
-}
-
-func (s *vaultSecret) Clone() kms.SecretProvider {
-	baseSecret := kms.BaseSecret{
-		Status:         s.Status,
-		Payload:        s.Payload,
-		Key:            s.Key,
-		AdditionalData: s.AdditionalData,
-		Mode:           s.Mode,
-	}
-	return newVaultSecret(baseSecret, s.URL, s.MasterKey)
-}

kms/vault/vault_disabled.go

@@ -1,11 +0,0 @@
-// +build novaultkms
-
-package vault
-
-import (
-	"github.com/drakkan/sftpgo/v2/version"
-)
-
-func init() {
-	version.AddFeature("-vaultkms")
-}

main.go

@@ -11,9 +11,6 @@ import (
 	"go.uber.org/automaxprocs/maxprocs"
 
 	"github.com/drakkan/sftpgo/v2/cmd"
-	_ "github.com/drakkan/sftpgo/v2/kms/aws"
-	_ "github.com/drakkan/sftpgo/v2/kms/gcp"
-	_ "github.com/drakkan/sftpgo/v2/kms/vault"
 )
 
 func main() {

version/version.go

@@ -22,11 +22,11 @@ type Info struct {
 func GetAsString() string {
 	var sb strings.Builder
 	sb.WriteString(info.Version)
-	if len(info.CommitHash) > 0 {
+	if info.CommitHash != "" {
 		sb.WriteString("-")
 		sb.WriteString(info.CommitHash)
 	}
-	if len(info.BuildDate) > 0 {
+	if info.BuildDate != "" {
 		sb.WriteString("-")
 		sb.WriteString(info.BuildDate)
 	}