add support for SSE-S3 bulk ETag decryption (minio#14627)

This commit adds support for bulk ETag
decryption for SSE-S3 encrypted objects.

If KES supports a bulk decryption API, then
MinIO will check whether its policy grants
access to this API. If so, MinIO will use
a bulk API call instead of sending encrypted
ETags serially to KES.

Note that MinIO will not use the KES bulk API
if its client certificate is an admin identity.

MinIO will process object listings in batches.
A batch has a configurable size that can be set
via `MINIO_KMS_KES_BULK_API_BATCH_SIZE=N`.
It defaults to `500`.

This env. variable is experimental and may be
renamed / removed in the future.

Signed-off-by: Andreas Auernhammer <[email protected]>

cmd/bucket-listobjects-handlers.go

@@ -24,28 +24,12 @@ import (
 	"strings"
 
 	"github.com/gorilla/mux"
+	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
 
-	"github.com/minio/minio/internal/sync/errgroup"
 	"github.com/minio/pkg/bucket/policy"
 )
 
-func concurrentDecryptETag(ctx context.Context, objects []ObjectInfo) {
-	g := errgroup.WithNErrs(len(objects)).WithConcurrency(500)
-	for index := range objects {
-		index := index
-		g.Go(func() error {
-			size, err := objects[index].GetActualSize()
-			if err == nil {
-				objects[index].Size = size
-			}
-			objects[index].ETag = objects[index].GetActualETag(nil)
-			return nil
-		}, index)
-	}
-	g.Wait()
-}
-
 // Validate all the ListObjects query arguments, returns an APIErrorCode
 // if one of the args do not meet the required conditions.
 // Special conditions required by MinIO server are as below
@@ -116,7 +100,10 @@ func (api objectAPIHandlers) ListObjectVersionsHandler(w http.ResponseWriter, r
 		return
 	}
 
-	concurrentDecryptETag(ctx, listObjectVersionsInfo.Objects)
+	if err = DecryptETags(ctx, GlobalKMS, listObjectVersionsInfo.Objects, kms.BatchSize()); err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
 
 	response := generateListVersionsResponse(bucket, prefix, marker, versionIDMarker, delimiter, encodingType, maxkeys, listObjectVersionsInfo)
 
@@ -178,7 +165,10 @@ func (api objectAPIHandlers) ListObjectsV2MHandler(w http.ResponseWriter, r *htt
 		return
 	}
 
-	concurrentDecryptETag(ctx, listObjectsV2Info.Objects)
+	if err = DecryptETags(ctx, GlobalKMS, listObjectsV2Info.Objects, kms.BatchSize()); err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
 
 	// The next continuation token has id@node_index format to optimize paginated listing
 	nextContinuationToken := listObjectsV2Info.NextContinuationToken
@@ -253,7 +243,10 @@ func (api objectAPIHandlers) ListObjectsV2Handler(w http.ResponseWriter, r *http
 		return
 	}
 
-	concurrentDecryptETag(ctx, listObjectsV2Info.Objects)
+	if err = DecryptETags(ctx, GlobalKMS, listObjectsV2Info.Objects, kms.BatchSize()); err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
 
 	response := generateListObjectsV2Response(bucket, prefix, token, listObjectsV2Info.NextContinuationToken, startAfter,
 		delimiter, encodingType, fetchOwner, listObjectsV2Info.IsTruncated,
@@ -350,7 +343,10 @@ func (api objectAPIHandlers) ListObjectsV1Handler(w http.ResponseWriter, r *http
 		return
 	}
 
-	concurrentDecryptETag(ctx, listObjectsInfo.Objects)
+	if err = DecryptETags(ctx, GlobalKMS, listObjectsInfo.Objects, kms.BatchSize()); err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
 
 	response := generateListObjectsV1Response(bucket, prefix, marker, delimiter, encodingType, maxKeys, listObjectsInfo)
 

cmd/encryption-v1.go

@@ -19,6 +19,7 @@ package cmd
 
 import (
 	"bufio"
+	"context"
 	"crypto/hmac"
 	"crypto/rand"
 	"crypto/sha256"
@@ -35,6 +36,7 @@ import (
 
 	"github.com/minio/kes"
 	"github.com/minio/minio/internal/crypto"
+	"github.com/minio/minio/internal/etag"
 	"github.com/minio/minio/internal/fips"
 	xhttp "github.com/minio/minio/internal/http"
 	"github.com/minio/minio/internal/kms"
@@ -80,17 +82,104 @@ func (o *MultipartInfo) KMSKeyID() string { return kmsKeyIDFromMetadata(o.UserDe
 // metadata, if any. It returns an empty ID if no key ID is
 // present.
 func kmsKeyIDFromMetadata(metadata map[string]string) string {
+	const ARNPrefix = "arn:aws:kms:"
 	if len(metadata) == 0 {
 		return ""
 	}
 	kmsID, ok := metadata[crypto.MetaKeyID]
 	if !ok {
 		return ""
 	}
-	if strings.HasPrefix(kmsID, "arn:aws:kms:") {
+	if strings.HasPrefix(kmsID, ARNPrefix) {
 		return kmsID
 	}
-	return "arn:aws:kms:" + kmsID
+	return ARNPrefix + kmsID
+}
+
+// DecryptETags dectypts all ObjectInfo ETags, if encrypted, using the KMS.
+func DecryptETags(ctx context.Context, KMS kms.KMS, objects []ObjectInfo, batchSize int) error {
+	var (
+		metadata []map[string]string
+		buckets  []string
+		names    []string
+	)
+	for len(objects) > 0 {
+		var N int
+		if len(objects) < batchSize {
+			N = len(objects)
+		} else {
+			N = batchSize
+		}
+
+		SSES3Batch := true
+		for _, object := range objects[:N] {
+			if kind, ok := crypto.IsEncrypted(object.UserDefined); !ok || kind != crypto.S3 {
+				SSES3Batch = false
+				break
+			}
+		}
+		if !SSES3Batch {
+			for i := range objects[:N] {
+				size, err := objects[i].GetActualSize()
+				if err != nil {
+					return err
+				}
+				objects[i].Size = size
+				objects[i].ETag = objects[i].GetActualETag(nil)
+			}
+			objects = objects[N:]
+			continue
+		}
+
+		// Now, decrypt all ETags using the a specialized bulk decryption API, if available.
+		// We check the cap of all slices first, to avoid allocating them over and over again.
+		if cap(metadata) >= N {
+			metadata = metadata[:0:N]
+		} else {
+			metadata = make([]map[string]string, 0, N)
+		}
+		if cap(buckets) >= N {
+			buckets = buckets[:0:N]
+		} else {
+			buckets = make([]string, 0, N)
+		}
+		if cap(names) >= N {
+			names = names[:0:N]
+		} else {
+			names = make([]string, 0, N)
+		}
+		for _, object := range objects[:N] {
+			metadata = append(metadata, object.UserDefined)
+			buckets = append(buckets, object.Bucket)
+			names = append(names, object.Name)
+		}
+		keys, err := crypto.S3.UnsealObjectKeys(KMS, metadata, buckets, names)
+		if err != nil {
+			return err
+		}
+
+		for i := range objects[:N] {
+			size, err := objects[i].GetActualSize()
+			if err != nil {
+				return err
+			}
+			ETag, err := etag.Parse(objects[i].ETag)
+			if err != nil {
+				return err
+			}
+			if ETag.IsEncrypted() {
+				tag, err := keys[i].UnsealETag(ETag)
+				if err != nil {
+					return err
+				}
+				ETag = etag.ETag(tag)
+				objects[i].Size = size
+				objects[i].ETag = ETag.String()
+			}
+		}
+		objects = objects[N:]
+	}
+	return nil
 }
 
 // isMultipart returns true if the current object is

go.mod

@@ -49,7 +49,7 @@ require (
 	github.com/minio/csvparser v1.0.0
 	github.com/minio/dperf v0.3.4
 	github.com/minio/highwayhash v1.0.2
-	github.com/minio/kes v0.18.0
+	github.com/minio/kes v0.19.0
 	github.com/minio/madmin-go v1.3.5
 	github.com/minio/minio-go/v7 v7.0.23
 	github.com/minio/parquet-go v1.1.0

go.sum

@@ -1090,8 +1090,9 @@ github.com/minio/filepath v1.0.0/go.mod h1:/nRZA2ldl5z6jT9/KQuvZcQlxZIMQoFFQPvEX
 github.com/minio/highwayhash v1.0.1/go.mod h1:BQskDq+xkJ12lmlUUi7U0M5Swg3EWR+dLTk+kldvVxY=
 github.com/minio/highwayhash v1.0.2 h1:Aak5U0nElisjDCfPSG79Tgzkn2gl66NxOMspRrKnA/g=
 github.com/minio/highwayhash v1.0.2/go.mod h1:BQskDq+xkJ12lmlUUi7U0M5Swg3EWR+dLTk+kldvVxY=
-github.com/minio/kes v0.18.0 h1:HryN2oAXc/xCwr+LzsU+P/xnrsLuIRJBun3EU8PuJaw=
 github.com/minio/kes v0.18.0/go.mod h1:zrimNafasyumYOBjHonPLLIUgCuRzCef0uQ6IojITZA=
+github.com/minio/kes v0.19.0 h1:rKzkDXT4ay7FBW34KgXK+y85bie4x4Oiq29ONRuMzh0=
+github.com/minio/kes v0.19.0/go.mod h1:e9YGKbwFCV7LbqNPMfZBazfNUsFGJ5LG4plSeWL8mmg=
 github.com/minio/madmin-go v1.1.23/go.mod h1:wv8zCroSCnpjjQdmgsdJEkFH2oD4w9J40OZqbhxjiJ4=
 github.com/minio/madmin-go v1.3.0/go.mod h1:b+BL64YlLY/NnE/LCPGbSgIcNX6WSWHx8BOb9wrYShk=
 github.com/minio/madmin-go v1.3.5 h1:YbDc4Q1oAjeGCss1u4j29kVgwJDLzoohgIGebAaLBXc=

internal/crypto/sse-s3.go

@@ -84,6 +84,63 @@ func (s3 sses3) UnsealObjectKey(KMS kms.KMS, metadata map[string]string, bucket,
 	return key, err
 }
 
+// UnsealObjectsKeys extracts and decrypts all sealed object keys
+// from the metadata using the KMS and returns the decrypted object
+// keys.
+//
+// The metadata, buckets and objects slices must have the same length.
+func (s3 sses3) UnsealObjectKeys(KMS kms.KMS, metadata []map[string]string, buckets, objects []string) ([]ObjectKey, error) {
+	if len(metadata) != len(buckets) || len(metadata) != len(objects) {
+		return nil, Errorf("invalid metadata/object count: %d != %d != %d", len(metadata), len(buckets), len(objects))
+	}
+
+	keyIDs := make([]string, 0, len(metadata))
+	kmsKeys := make([][]byte, 0, len(metadata))
+	sealedKeys := make([]SealedKey, 0, len(metadata))
+
+	sameKeyID := true
+	for i := range metadata {
+		keyID, kmsKey, sealedKey, err := s3.ParseMetadata(metadata[i])
+		if err != nil {
+			return nil, err
+		}
+		keyIDs = append(keyIDs, keyID)
+		kmsKeys = append(kmsKeys, kmsKey)
+		sealedKeys = append(sealedKeys, sealedKey)
+
+		if i > 0 && keyID != keyIDs[i-1] {
+			sameKeyID = false
+		}
+	}
+	if sameKeyID {
+		contexts := make([]kms.Context, 0, len(keyIDs))
+		for i := range buckets {
+			contexts = append(contexts, kms.Context{buckets[i]: path.Join(buckets[i], objects[i])})
+		}
+		unsealKeys, err := KMS.DecryptAll(keyIDs[0], kmsKeys, contexts)
+		if err != nil {
+			return nil, err
+		}
+		keys := make([]ObjectKey, len(unsealKeys))
+		for i := range keys {
+			if err := keys[i].Unseal(unsealKeys[i], sealedKeys[i], s3.String(), buckets[i], objects[i]); err != nil {
+				return nil, err
+			}
+		}
+		return keys, nil
+	}
+
+	keys := make([]ObjectKey, 0, len(keyIDs))
+	for i := range keyIDs {
+		key, err := s3.UnsealObjectKey(KMS, metadata[i], buckets[i], objects[i])
+		if err != nil {
+			return nil, err
+		}
+		keys = append(keys, key)
+	}
+	return keys, nil
+}
+
 // CreateMetadata encodes the sealed object key into the metadata and returns
 // the modified metadata. If the keyID and the kmsKey is not empty it encodes
 // both into the metadata as well. It allocates a new metadata map if metadata

internal/kms/kes.go

@@ -22,6 +22,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"errors"
+	"strings"
 	"time"
 
 	"github.com/minio/kes"
@@ -69,15 +70,30 @@ func NewWithConfig(config Config) (KMS, error) {
 		ClientSessionCache: tls.NewLRUClientSessionCache(tlsClientSessionCacheSize),
 	})
 	client.Endpoints = endpoints
+
+	var bulkAvailable bool
+	_, policy, err := client.DescribeSelf(context.Background())
+	if err == nil {
+		const BulkAPI = "/v1/key/bulk/decrypt/"
+		for _, allow := range policy.Allow {
+			if strings.HasPrefix(allow, BulkAPI) {
+				bulkAvailable = true
+				break
+			}
+		}
+	}
 	return &kesClient{
-		client:       client,
-		defaultKeyID: config.DefaultKeyID,
+		client:        client,
+		defaultKeyID:  config.DefaultKeyID,
+		bulkAvailable: bulkAvailable,
 	}, nil
 }
 
 type kesClient struct {
 	defaultKeyID string
 	client       *kes.Client
+
+	bulkAvailable bool
 }
 
 var _ KMS = (*kesClient)(nil) // compiler check
@@ -145,3 +161,38 @@ func (c *kesClient) DecryptKey(keyID string, ciphertext []byte, ctx Context) ([]
 	}
 	return c.client.Decrypt(context.Background(), keyID, ciphertext, ctxBytes)
 }
+
+func (c *kesClient) DecryptAll(keyID string, ciphertexts [][]byte, contexts []Context) ([][]byte, error) {
+	if c.bulkAvailable {
+		CCPs := make([]kes.CCP, 0, len(ciphertexts))
+		for i := range ciphertexts {
+			bCtx, err := contexts[i].MarshalText()
+			if err != nil {
+				return nil, err
+			}
+			CCPs = append(CCPs, kes.CCP{
+				Ciphertext: ciphertexts[i],
+				Context:    bCtx,
+			})
+		}
+		PCPs, err := c.client.DecryptAll(context.Background(), keyID, CCPs...)
+		if err != nil {
+			return nil, err
+		}
+		plaintexts := make([][]byte, 0, len(PCPs))
+		for _, p := range PCPs {
+			plaintexts = append(plaintexts, p.Plaintext)
+		}
+		return plaintexts, nil
+	}
+
+	plaintexts := make([][]byte, 0, len(ciphertexts))
+	for i := range ciphertexts {
+		plaintext, err := c.DecryptKey(keyID, ciphertexts[i], contexts[i])
+		if err != nil {
+			return nil, err
+		}
+		plaintexts = append(plaintexts, plaintext)
+	}
+	return plaintexts, nil
+}