sse: add support for SSE-KMS bucket configurations (#12295)

This commit adds support for SSE-KMS bucket configurations.
Before, the MinIO server did not support SSE-KMS, and therefore,
it was not possible to specify an SSE-KMS bucket config.

Now, this is possible. For example:
```
mc encrypt set sse-kms some-key <alias>/my-bucket
```

Further, this commit fixes an issue caused by not supporting
SSE-KMS bucket configuration and switching to SSE-KMS as default
SSE method.

Before, the server just checked whether an SSE bucket config was
present (not which type of SSE config) and applied the default
SSE method (which was switched from SSE-S3 to SSE-KMS).

This caused objects to get encrypted with SSE-KMS even though a
SSE-S3 bucket config was present.

This issue is fixed as a side-effect of this commit.

Signed-off-by: Andreas Auernhammer <aead@mail.de>

cmd/bucket-encryption.go

@@ -53,7 +53,7 @@ func validateBucketSSEConfig(r io.Reader) (*bucketsse.BucketSSEConfig, error) {
 		return nil, err
 	}
 
-	if len(encConfig.Rules) == 1 && encConfig.Rules[0].DefaultEncryptionAction.Algorithm == bucketsse.AES256 {
+	if len(encConfig.Rules) == 1 {
 		return encConfig, nil
 	}
 

cmd/bucket-encryption_test.go

@@ -19,7 +19,6 @@ package cmd
 
 import (
 	"bytes"
-	"errors"
 	"testing"
 )
 
@@ -47,12 +46,12 @@ func TestValidateBucketSSEConfig(t *testing.T) {
 			<Rule>
 			<ApplyServerSideEncryptionByDefault>
                         <SSEAlgorithm>aws:kms</SSEAlgorithm>
-                        <KMSMasterKeyID>arn:aws:kms:us-east-1:1234/5678example</KMSMasterKeyID>
+                        <KMSMasterKeyID>my-key</KMSMasterKeyID>
 			</ApplyServerSideEncryptionByDefault>
 			</Rule>
 			</ServerSideEncryptionConfiguration>`,
-			expectedErr: errors.New("Unsupported bucket encryption configuration"),
-			shouldPass:  false,
+			expectedErr: nil,
+			shouldPass:  true,
 		},
 	}
 

cmd/bucket-handlers.go

@@ -992,12 +992,8 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 	var objectEncryptionKey crypto.ObjectKey
 
 	// Check if bucket encryption is enabled
-	if _, err = globalBucketSSEConfigSys.Get(bucket); err == nil || globalAutoEncryption {
-		// This request header needs to be set prior to setting ObjectOptions
-		if !crypto.SSEC.IsRequested(r.Header) {
-			r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
-		}
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(bucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	// get gateway encryption options
 	var opts ObjectOptions

cmd/object-handlers.go

@@ -960,11 +960,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	}
 
 	// Check if bucket encryption is enabled
-	_, err = globalBucketSSEConfigSys.Get(dstBucket)
-	// This request header needs to be set prior to setting ObjectOptions
-	if (globalAutoEncryption || err == nil) && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(dstBucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	var srcOpts, dstOpts ObjectOptions
 	srcOpts, err = copySrcOpts(ctx, r, srcBucket, srcObject)
@@ -1566,11 +1563,8 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	}
 
 	// Check if bucket encryption is enabled
-	_, err = globalBucketSSEConfigSys.Get(bucket)
-	// This request header needs to be set prior to setting ObjectOptions
-	if (globalAutoEncryption || err == nil) && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(bucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	actualSize := size
 	if objectAPI.IsCompressionSupported() && isCompressible(r.Header, object) && size > 0 {
@@ -1885,11 +1879,8 @@ func (api objectAPIHandlers) PutObjectExtractHandler(w http.ResponseWriter, r *h
 	}
 
 	// Check if bucket encryption is enabled
-	_, err = globalBucketSSEConfigSys.Get(bucket)
-	// This request header needs to be set prior to setting ObjectOptions
-	if (globalAutoEncryption || err == nil) && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(bucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	retPerms := isPutActionAllowed(ctx, getRequestAuthType(r), bucket, object, r, iampolicy.PutObjectRetentionAction)
 	holdPerms := isPutActionAllowed(ctx, getRequestAuthType(r), bucket, object, r, iampolicy.PutObjectLegalHoldAction)
@@ -2076,11 +2067,8 @@ func (api objectAPIHandlers) NewMultipartUploadHandler(w http.ResponseWriter, r
 	}
 
 	// Check if bucket encryption is enabled
-	_, err = globalBucketSSEConfigSys.Get(bucket)
-	// This request header needs to be set prior to setting ObjectOptions
-	if (globalAutoEncryption || err == nil) && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(bucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	// Validate storage class metadata if present
 	if sc := r.Header.Get(xhttp.AmzStorageClass); sc != "" {

cmd/web-handlers.go

@@ -1201,10 +1201,8 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Check if bucket encryption is enabled
-	_, err = globalBucketSSEConfigSys.Get(bucket)
-	if (globalAutoEncryption || err == nil) && !crypto.SSEC.IsRequested(r.Header) {
-		r.Header.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
-	}
+	sseConfig, _ := globalBucketSSEConfigSys.Get(bucket)
+	sseConfig.Apply(r.Header, globalAutoEncryption)
 
 	// Require Content-Length to be set in the request
 	size := r.ContentLength

pkg/bucket/encryption/bucket-sse-config.go

@@ -21,6 +21,10 @@ import (
 	"encoding/xml"
 	"errors"
 	"io"
+	"net/http"
+
+	"github.com/minio/minio/cmd/crypto"
+	xhttp "github.com/minio/minio/cmd/http"
 )
 
 const (
@@ -107,6 +111,49 @@ func ParseBucketSSEConfig(r io.Reader) (*BucketSSEConfig, error) {
 	if config.XMLNS == "" {
 		config.XMLNS = xmlNS
 	}
-
 	return &config, nil
 }
+
+// Apply applies the SSE bucket configuration on the given HTTP headers and
+// sets the specified SSE headers.
+//
+// Apply does not overwrite any existing SSE headers. Further, it will
+// set minimal SSE-KMS headers if autoEncrypt is true and the BucketSSEConfig
+// is nil.
+func (b *BucketSSEConfig) Apply(headers http.Header, autoEncrypt bool) {
+	if _, ok := crypto.IsRequested(headers); ok {
+		return
+	}
+	if b == nil {
+		if autoEncrypt {
+			headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
+		}
+		return
+	}
+
+	switch b.Algorithm() {
+	case xhttp.AmzEncryptionAES:
+		headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
+	case xhttp.AmzEncryptionKMS:
+		headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
+		headers.Set(xhttp.AmzServerSideEncryptionKmsID, b.KeyID())
+	}
+}
+
+// Algorithm returns the SSE algorithm specified by the SSE configuration.
+func (b *BucketSSEConfig) Algorithm() SSEAlgorithm {
+	for _, rule := range b.Rules {
+		return rule.DefaultEncryptionAction.Algorithm
+	}
+	return ""
+}
+
+// KeyID returns the KMS key ID specified by the SSE configuration.
+// If the SSE configuration does not specify SSE-KMS it returns an
+// empty key ID.
+func (b *BucketSSEConfig) KeyID() string {
+	for _, rule := range b.Rules {
+		return rule.DefaultEncryptionAction.MasterKeyID
+	}
+	return ""
+}