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minio/cmd/encryption-v1.go

1272 lines
42 KiB

/*
* Minio Cloud Storage, (C) 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 cmd
import (
"context"
"crypto/hmac"
"crypto/rand"
"crypto/subtle"
"encoding/binary"
"encoding/hex"
"errors"
"io"
"net/http"
"path"
"strconv"
"github.com/minio/minio-go/pkg/encrypt"
"github.com/minio/minio/cmd/crypto"
"github.com/minio/minio/cmd/logger"
"github.com/minio/minio/pkg/ioutil"
sha256 "github.com/minio/sha256-simd"
"github.com/minio/sio"
)
var (
// AWS errors for invalid SSE-C requests.
errEncryptedObject = errors.New("The object was stored using a form of SSE")
errInvalidSSEParameters = errors.New("The SSE-C key for key-rotation is not correct") // special access denied
errKMSNotConfigured = errors.New("KMS not configured for a server side encrypted object")
// Additional Minio errors for SSE-C requests.
errObjectTampered = errors.New("The requested object was modified and may be compromised")
// error returned when invalid encryption parameters are specified
errInvalidEncryptionParameters = errors.New("The encryption parameters are not applicable to this object")
)
const (
// SSECustomerKeySize is the size of valid client provided encryption keys in bytes.
// Currently AWS supports only AES256. So the SSE-C key size is fixed to 32 bytes.
SSECustomerKeySize = 32
// SSEIVSize is the size of the IV data
SSEIVSize = 32 // 32 bytes
// SSEDAREPackageBlockSize - SSE dare package block size.
SSEDAREPackageBlockSize = 64 * 1024 // 64KiB bytes
// SSEDAREPackageMetaSize - SSE dare package meta padding bytes.
SSEDAREPackageMetaSize = 32 // 32 bytes
)
const (
// SSESealAlgorithmDareSha256 specifies DARE as authenticated en/decryption scheme and SHA256 as cryptographic
// hash function. The key derivation of DARE-SHA256 is not optimal and does not include the object path.
// It is considered legacy and should not be used anymore.
SSESealAlgorithmDareSha256 = "DARE-SHA256"
// SSESealAlgorithmDareV2HmacSha256 specifies DAREv2 as authenticated en/decryption scheme and SHA256 as cryptographic
// hash function for the HMAC PRF.
SSESealAlgorithmDareV2HmacSha256 = "DAREv2-HMAC-SHA256"
)
// hasServerSideEncryptionHeader returns true if the given HTTP header
// contains server-side-encryption.
func hasServerSideEncryptionHeader(header http.Header) bool {
return crypto.S3.IsRequested(header) || crypto.SSEC.IsRequested(header)
}
// isEncryptedMultipart returns true if the current object is
// uploaded by the user using multipart mechanism:
// initiate new multipart, upload part, complete upload
func isEncryptedMultipart(objInfo ObjectInfo) bool {
if len(objInfo.Parts) == 0 {
return false
}
if !crypto.IsMultiPart(objInfo.UserDefined) {
return false
}
for _, part := range objInfo.Parts {
_, err := sio.DecryptedSize(uint64(part.Size))
if err != nil {
return false
}
}
// Further check if this object is uploaded using multipart mechanism
// by the user and it is not about XL internally splitting the
// object into parts in PutObject()
return !(objInfo.backendType == BackendErasure && len(objInfo.ETag) == 32)
}
// ParseSSECopyCustomerRequest parses the SSE-C header fields of the provided request.
// It returns the client provided key on success.
func ParseSSECopyCustomerRequest(h http.Header, metadata map[string]string) (key []byte, err error) {
if crypto.S3.IsEncrypted(metadata) && crypto.SSECopy.IsRequested(h) {
return nil, crypto.ErrIncompatibleEncryptionMethod
}
k, err := crypto.SSECopy.ParseHTTP(h)
return k[:], err
}
// ParseSSECustomerRequest parses the SSE-C header fields of the provided request.
// It returns the client provided key on success.
func ParseSSECustomerRequest(r *http.Request) (key []byte, err error) {
return ParseSSECustomerHeader(r.Header)
}
// ParseSSECustomerHeader parses the SSE-C header fields and returns
// the client provided key on success.
func ParseSSECustomerHeader(header http.Header) (key []byte, err error) {
if crypto.S3.IsRequested(header) && crypto.SSEC.IsRequested(header) {
return key, crypto.ErrIncompatibleEncryptionMethod
}
k, err := crypto.SSEC.ParseHTTP(header)
return k[:], err
}
// This function rotates old to new key.
func rotateKey(oldKey []byte, newKey []byte, bucket, object string, metadata map[string]string) error {
switch {
default:
return errObjectTampered
case crypto.SSEC.IsEncrypted(metadata):
sealedKey, err := crypto.SSEC.ParseMetadata(metadata)
if err != nil {
return err
}
var objectKey crypto.ObjectKey
var extKey [32]byte
copy(extKey[:], oldKey)
if err = objectKey.Unseal(extKey, sealedKey, crypto.SSEC.String(), bucket, object); err != nil {
if subtle.ConstantTimeCompare(oldKey, newKey) == 1 {
return errInvalidSSEParameters // AWS returns special error for equal but invalid keys.
}
return crypto.ErrInvalidCustomerKey // To provide strict AWS S3 compatibility we return: access denied.
}
if subtle.ConstantTimeCompare(oldKey, newKey) == 1 && sealedKey.Algorithm == crypto.SealAlgorithm {
return nil // don't rotate on equal keys if seal algorithm is latest
}
copy(extKey[:], newKey)
sealedKey = objectKey.Seal(extKey, sealedKey.IV, crypto.SSEC.String(), bucket, object)
crypto.SSEC.CreateMetadata(metadata, sealedKey)
return nil
case crypto.S3.IsEncrypted(metadata):
if GlobalKMS == nil {
return errKMSNotConfigured
}
keyID, kmsKey, sealedKey, err := crypto.S3.ParseMetadata(metadata)
if err != nil {
return err
}
oldKey, err := GlobalKMS.UnsealKey(keyID, kmsKey, crypto.Context{bucket: path.Join(bucket, object)})
if err != nil {
return err
}
var objectKey crypto.ObjectKey
if err = objectKey.Unseal(oldKey, sealedKey, crypto.S3.String(), bucket, object); err != nil {
return err
}
newKey, encKey, err := GlobalKMS.GenerateKey(globalKMSKeyID, crypto.Context{bucket: path.Join(bucket, object)})
if err != nil {
return err
}
sealedKey = objectKey.Seal(newKey, crypto.GenerateIV(rand.Reader), crypto.S3.String(), bucket, object)
crypto.S3.CreateMetadata(metadata, globalKMSKeyID, encKey, sealedKey)
return nil
}
}
func newEncryptMetadata(key []byte, bucket, object string, metadata map[string]string, sseS3 bool) ([]byte, error) {
var sealedKey crypto.SealedKey
if sseS3 {
if GlobalKMS == nil {
return nil, errKMSNotConfigured
}
key, encKey, err := GlobalKMS.GenerateKey(globalKMSKeyID, crypto.Context{bucket: path.Join(bucket, object)})
if err != nil {
return nil, err
}
objectKey := crypto.GenerateKey(key, rand.Reader)
sealedKey = objectKey.Seal(key, crypto.GenerateIV(rand.Reader), crypto.S3.String(), bucket, object)
crypto.S3.CreateMetadata(metadata, globalKMSKeyID, encKey, sealedKey)
return objectKey[:], nil
}
var extKey [32]byte
copy(extKey[:], key)
objectKey := crypto.GenerateKey(extKey, rand.Reader)
sealedKey = objectKey.Seal(extKey, crypto.GenerateIV(rand.Reader), crypto.SSEC.String(), bucket, object)
crypto.SSEC.CreateMetadata(metadata, sealedKey)
return objectKey[:], nil
}
func newEncryptReader(content io.Reader, key []byte, bucket, object string, metadata map[string]string, sseS3 bool) (r io.Reader, encKey []byte, err error) {
objectEncryptionKey, err := newEncryptMetadata(key, bucket, object, metadata, sseS3)
if err != nil {
return nil, encKey, err
}
reader, err := sio.EncryptReader(content, sio.Config{Key: objectEncryptionKey[:], MinVersion: sio.Version20})
if err != nil {
return nil, encKey, crypto.ErrInvalidCustomerKey
}
return reader, objectEncryptionKey, nil
}
// set new encryption metadata from http request headers for SSE-C and generated key from KMS in the case of
// SSE-S3
func setEncryptionMetadata(r *http.Request, bucket, object string, metadata map[string]string) (err error) {
var (
key []byte
)
if crypto.SSEC.IsRequested(r.Header) {
key, err = ParseSSECustomerRequest(r)
if err != nil {
return
}
}
_, err = newEncryptMetadata(key, bucket, object, metadata, crypto.S3.IsRequested(r.Header))
return
}
// EncryptRequest takes the client provided content and encrypts the data
// with the client provided key. It also marks the object as client-side-encrypted
// and sets the correct headers.
func EncryptRequest(content io.Reader, r *http.Request, bucket, object string, metadata map[string]string) (reader io.Reader, objEncKey []byte, err error) {
var (
key []byte
)
if crypto.S3.IsRequested(r.Header) && crypto.SSEC.IsRequested(r.Header) {
return nil, objEncKey, crypto.ErrIncompatibleEncryptionMethod
}
if crypto.SSEC.IsRequested(r.Header) {
key, err = ParseSSECustomerRequest(r)
if err != nil {
return nil, objEncKey, err
}
}
return newEncryptReader(content, key, bucket, object, metadata, crypto.S3.IsRequested(r.Header))
}
// DecryptCopyRequest decrypts the object with the client provided key. It also removes
// the client-side-encryption metadata from the object and sets the correct headers.
func DecryptCopyRequest(client io.Writer, r *http.Request, bucket, object string, metadata map[string]string) (io.WriteCloser, error) {
var (
key []byte
err error
)
if crypto.SSECopy.IsRequested(r.Header) {
key, err = ParseSSECopyCustomerRequest(r.Header, metadata)
if err != nil {
return nil, err
}
}
return newDecryptWriter(client, key, bucket, object, 0, metadata)
}
func decryptObjectInfo(key []byte, bucket, object string, metadata map[string]string) ([]byte, error) {
switch {
default:
return nil, errObjectTampered
case crypto.S3.IsEncrypted(metadata):
if GlobalKMS == nil {
return nil, errKMSNotConfigured
}
keyID, kmsKey, sealedKey, err := crypto.S3.ParseMetadata(metadata)
if err != nil {
return nil, err
}
extKey, err := GlobalKMS.UnsealKey(keyID, kmsKey, crypto.Context{bucket: path.Join(bucket, object)})
if err != nil {
return nil, err
}
var objectKey crypto.ObjectKey
if err = objectKey.Unseal(extKey, sealedKey, crypto.S3.String(), bucket, object); err != nil {
return nil, err
}
return objectKey[:], nil
case crypto.SSEC.IsEncrypted(metadata):
var extKey [32]byte
copy(extKey[:], key)
sealedKey, err := crypto.SSEC.ParseMetadata(metadata)
if err != nil {
return nil, err
}
var objectKey crypto.ObjectKey
if err = objectKey.Unseal(extKey, sealedKey, crypto.SSEC.String(), bucket, object); err != nil {
return nil, err
}
return objectKey[:], nil
}
}
func newDecryptWriter(client io.Writer, key []byte, bucket, object string, seqNumber uint32, metadata map[string]string) (io.WriteCloser, error) {
objectEncryptionKey, err := decryptObjectInfo(key, bucket, object, metadata)
if err != nil {
return nil, err
}
return newDecryptWriterWithObjectKey(client, objectEncryptionKey, seqNumber, metadata)
}
func newDecryptWriterWithObjectKey(client io.Writer, objectEncryptionKey []byte, seqNumber uint32, metadata map[string]string) (io.WriteCloser, error) {
writer, err := sio.DecryptWriter(client, sio.Config{
Key: objectEncryptionKey,
SequenceNumber: seqNumber,
})
if err != nil {
return nil, crypto.ErrInvalidCustomerKey
}
delete(metadata, crypto.SSEIV)
delete(metadata, crypto.SSESealAlgorithm)
delete(metadata, crypto.SSECSealedKey)
delete(metadata, crypto.SSEMultipart)
delete(metadata, crypto.S3SealedKey)
delete(metadata, crypto.S3KMSSealedKey)
delete(metadata, crypto.S3KMSKeyID)
return writer, nil
}
// Adding support for reader based interface
// DecryptRequestWithSequenceNumberR - same as
// DecryptRequestWithSequenceNumber but with a reader
func DecryptRequestWithSequenceNumberR(client io.Reader, h http.Header, bucket, object string, seqNumber uint32, metadata map[string]string) (io.Reader, error) {
if crypto.S3.IsEncrypted(metadata) {
return newDecryptReader(client, nil, bucket, object, seqNumber, metadata)
}
key, err := ParseSSECustomerHeader(h)
if err != nil {
return nil, err
}
return newDecryptReader(client, key, bucket, object, seqNumber, metadata)
}
// DecryptCopyRequestR - same as DecryptCopyRequest, but with a
// Reader
func DecryptCopyRequestR(client io.Reader, h http.Header, bucket, object string, seqNumber uint32, metadata map[string]string) (io.Reader, error) {
var (
key []byte
err error
)
if crypto.SSECopy.IsRequested(h) {
key, err = ParseSSECopyCustomerRequest(h, metadata)
if err != nil {
return nil, err
}
}
return newDecryptReader(client, key, bucket, object, seqNumber, metadata)
}
func newDecryptReader(client io.Reader, key []byte, bucket, object string, seqNumber uint32, metadata map[string]string) (io.Reader, error) {
objectEncryptionKey, err := decryptObjectInfo(key, bucket, object, metadata)
if err != nil {
return nil, err
}
return newDecryptReaderWithObjectKey(client, objectEncryptionKey, seqNumber, metadata)
}
func newDecryptReaderWithObjectKey(client io.Reader, objectEncryptionKey []byte, seqNumber uint32, metadata map[string]string) (io.Reader, error) {
reader, err := sio.DecryptReader(client, sio.Config{
Key: objectEncryptionKey,
SequenceNumber: seqNumber,
})
if err != nil {
return nil, crypto.ErrInvalidCustomerKey
}
return reader, nil
}
// DecryptBlocksRequestR - same as DecryptBlocksRequest but with a
// reader
func DecryptBlocksRequestR(inputReader io.Reader, h http.Header, offset,
length int64, seqNumber uint32, partStart int, oi ObjectInfo, copySource bool) (
io.Reader, error) {
bucket, object := oi.Bucket, oi.Name
// Single part case
if !isEncryptedMultipart(oi) {
var reader io.Reader
var err error
if copySource {
reader, err = DecryptCopyRequestR(inputReader, h, bucket, object, seqNumber, oi.UserDefined)
} else {
reader, err = DecryptRequestWithSequenceNumberR(inputReader, h, bucket, object, seqNumber, oi.UserDefined)
}
if err != nil {
return nil, err
}
return reader, nil
}
partDecRelOffset := int64(seqNumber) * SSEDAREPackageBlockSize
partEncRelOffset := int64(seqNumber) * (SSEDAREPackageBlockSize + SSEDAREPackageMetaSize)
w := &DecryptBlocksReader{
reader: inputReader,
startSeqNum: seqNumber,
partDecRelOffset: partDecRelOffset,
partEncRelOffset: partEncRelOffset,
parts: oi.Parts,
partIndex: partStart,
header: h,
bucket: bucket,
object: object,
customerKeyHeader: h.Get(crypto.SSECKey),
copySource: copySource,
}
w.metadata = map[string]string{}
// Copy encryption metadata for internal use.
for k, v := range oi.UserDefined {
w.metadata[k] = v
}
if w.copySource {
w.customerKeyHeader = h.Get(crypto.SSECopyKey)
}
if err := w.buildDecrypter(w.parts[w.partIndex].Number); err != nil {
return nil, err
}
return w, nil
}
// DecryptRequestWithSequenceNumber decrypts the object with the client provided key. It also removes
// the client-side-encryption metadata from the object and sets the correct headers.
func DecryptRequestWithSequenceNumber(client io.Writer, r *http.Request, bucket, object string, seqNumber uint32, metadata map[string]string) (io.WriteCloser, error) {
if crypto.S3.IsEncrypted(metadata) {
return newDecryptWriter(client, nil, bucket, object, seqNumber, metadata)
}
key, err := ParseSSECustomerRequest(r)
if err != nil {
return nil, err
}
return newDecryptWriter(client, key, bucket, object, seqNumber, metadata)
}
// DecryptRequest decrypts the object with client provided key for SSE-C and SSE-S3. It also removes
// the encryption metadata from the object and sets the correct headers.
func DecryptRequest(client io.Writer, r *http.Request, bucket, object string, metadata map[string]string) (io.WriteCloser, error) {
return DecryptRequestWithSequenceNumber(client, r, bucket, object, 0, metadata)
}
// DecryptBlocksReader - decrypts multipart parts, while implementing
// a io.Reader compatible interface.
type DecryptBlocksReader struct {
// Source of the encrypted content that will be decrypted
reader io.Reader
// Current decrypter for the current encrypted data block
decrypter io.Reader
// Start sequence number
startSeqNum uint32
// Current part index
partIndex int
// Parts information
parts []ObjectPartInfo
header http.Header
bucket, object string
metadata map[string]string
partDecRelOffset, partEncRelOffset int64
copySource bool
// Customer Key
customerKeyHeader string
}
func (d *DecryptBlocksReader) buildDecrypter(partID int) error {
m := make(map[string]string)
for k, v := range d.metadata {
m[k] = v
}
// Initialize the first decrypter; new decrypters will be
// initialized in Read() operation as needed.
var key []byte
var err error
if d.copySource {
if crypto.SSEC.IsEncrypted(d.metadata) {
d.header.Set(crypto.SSECopyKey, d.customerKeyHeader)
key, err = ParseSSECopyCustomerRequest(d.header, d.metadata)
}
} else {
if crypto.SSEC.IsEncrypted(d.metadata) {
d.header.Set(crypto.SSECKey, d.customerKeyHeader)
key, err = ParseSSECustomerHeader(d.header)
}
}
if err != nil {
return err
}
objectEncryptionKey, err := decryptObjectInfo(key, d.bucket, d.object, m)
if err != nil {
return err
}
var partIDbin [4]byte
binary.LittleEndian.PutUint32(partIDbin[:], uint32(partID)) // marshal part ID
mac := hmac.New(sha256.New, objectEncryptionKey) // derive part encryption key from part ID and object key
mac.Write(partIDbin[:])
partEncryptionKey := mac.Sum(nil)
// Limit the reader, so the decryptor doesnt receive bytes
// from the next part (different DARE stream)
encLenToRead := d.parts[d.partIndex].Size - d.partEncRelOffset
decrypter, err := newDecryptReaderWithObjectKey(io.LimitReader(d.reader, encLenToRead), partEncryptionKey, d.startSeqNum, m)
if err != nil {
return err
}
d.decrypter = decrypter
return nil
}
func (d *DecryptBlocksReader) Read(p []byte) (int, error) {
var err error
var n1 int
decPartSize, _ := sio.DecryptedSize(uint64(d.parts[d.partIndex].Size))
unreadPartLen := int64(decPartSize) - d.partDecRelOffset
if int64(len(p)) < unreadPartLen {
n1, err = d.decrypter.Read(p)
if err != nil {
return 0, err
}
d.partDecRelOffset += int64(n1)
} else {
n1, err = io.ReadFull(d.decrypter, p[:unreadPartLen])
if err != nil {
return 0, err
}
// We should now proceed to next part, reset all
// values appropriately.
d.partEncRelOffset = 0
d.partDecRelOffset = 0
d.startSeqNum = 0
d.partIndex++
if d.partIndex == len(d.parts) {
return n1, io.EOF
}
err = d.buildDecrypter(d.parts[d.partIndex].Number)
if err != nil {
return 0, err
}
n1, err = d.decrypter.Read(p[n1:])
if err != nil {
return 0, err
}
d.partDecRelOffset += int64(n1)
}
return len(p), nil
}
// DecryptBlocksWriter - decrypts multipart parts, while implementing
// a io.Writer compatible interface.
type DecryptBlocksWriter struct {
// Original writer where the plain data will be written
writer io.Writer
// Current decrypter for the current encrypted data block
decrypter io.WriteCloser
// Start sequence number
startSeqNum uint32
// Current part index
partIndex int
// Parts information
parts []ObjectPartInfo
req *http.Request
bucket, object string
metadata map[string]string
partEncRelOffset int64
copySource bool
// Customer Key
customerKeyHeader string
}
func (w *DecryptBlocksWriter) buildDecrypter(partID int) error {
m := make(map[string]string)
for k, v := range w.metadata {
m[k] = v
}
// Initialize the first decrypter, new decrypters will be initialized in Write() operation as needed.
var key []byte
var err error
if w.copySource {
if crypto.SSEC.IsEncrypted(w.metadata) {
w.req.Header.Set(crypto.SSECopyKey, w.customerKeyHeader)
key, err = ParseSSECopyCustomerRequest(w.req.Header, w.metadata)
}
} else {
if crypto.SSEC.IsEncrypted(w.metadata) {
w.req.Header.Set(crypto.SSECKey, w.customerKeyHeader)
key, err = ParseSSECustomerRequest(w.req)
}
}
if err != nil {
return err
}
objectEncryptionKey, err := decryptObjectInfo(key, w.bucket, w.object, m)
if err != nil {
return err
}
var partIDbin [4]byte
binary.LittleEndian.PutUint32(partIDbin[:], uint32(partID)) // marshal part ID
mac := hmac.New(sha256.New, objectEncryptionKey) // derive part encryption key from part ID and object key
mac.Write(partIDbin[:])
partEncryptionKey := mac.Sum(nil)
// make sure to provide a NopCloser such that a Close
// on sio.decryptWriter doesn't close the underlying writer's
// close which perhaps can close the stream prematurely.
decrypter, err := newDecryptWriterWithObjectKey(ioutil.NopCloser(w.writer), partEncryptionKey, w.startSeqNum, m)
if err != nil {
return err
}
if w.decrypter != nil {
// Pro-actively close the writer such that any pending buffers
// are flushed already before we allocate a new decrypter.
err = w.decrypter.Close()
if err != nil {
return err
}
}
w.decrypter = decrypter
return nil
}
func (w *DecryptBlocksWriter) Write(p []byte) (int, error) {
var err error
var n1 int
if int64(len(p)) < w.parts[w.partIndex].Size-w.partEncRelOffset {
n1, err = w.decrypter.Write(p)
if err != nil {
return 0, err
}
w.partEncRelOffset += int64(n1)
} else {
n1, err = w.decrypter.Write(p[:w.parts[w.partIndex].Size-w.partEncRelOffset])
if err != nil {
return 0, err
}
// We should now proceed to next part, reset all values appropriately.
w.partEncRelOffset = 0
w.startSeqNum = 0
w.partIndex++
err = w.buildDecrypter(w.partIndex + 1)
if err != nil {
return 0, err
}
n1, err = w.decrypter.Write(p[n1:])
if err != nil {
return 0, err
}
w.partEncRelOffset += int64(n1)
}
return len(p), nil
}
// Close closes the LimitWriter. It behaves like io.Closer.
func (w *DecryptBlocksWriter) Close() error {
if w.decrypter != nil {
err := w.decrypter.Close()
if err != nil {
return err
}
}
if closer, ok := w.writer.(io.Closer); ok {
return closer.Close()
}
return nil
}
// DecryptAllBlocksCopyRequest - setup a struct which can decrypt many concatenated encrypted data
// parts information helps to know the boundaries of each encrypted data block, this function decrypts
// all parts starting from part-1.
func DecryptAllBlocksCopyRequest(client io.Writer, r *http.Request, bucket, object string, objInfo ObjectInfo) (io.WriteCloser, int64, error) {
w, _, size, err := DecryptBlocksRequest(client, r, bucket, object, 0, objInfo.Size, objInfo, true)
return w, size, err
}
// DecryptBlocksRequest - setup a struct which can decrypt many concatenated encrypted data
// parts information helps to know the boundaries of each encrypted data block.
func DecryptBlocksRequest(client io.Writer, r *http.Request, bucket, object string, startOffset, length int64, objInfo ObjectInfo, copySource bool) (io.WriteCloser, int64, int64, error) {
var seqNumber uint32
var encStartOffset, encLength int64
if !isEncryptedMultipart(objInfo) {
seqNumber, encStartOffset, encLength = getEncryptedSinglePartOffsetLength(startOffset, length, objInfo)
var writer io.WriteCloser
var err error
if copySource {
writer, err = DecryptCopyRequest(client, r, bucket, object, objInfo.UserDefined)
} else {
writer, err = DecryptRequestWithSequenceNumber(client, r, bucket, object, seqNumber, objInfo.UserDefined)
}
if err != nil {
return nil, 0, 0, err
}
return writer, encStartOffset, encLength, nil
}
_, encStartOffset, encLength = getEncryptedMultipartsOffsetLength(startOffset, length, objInfo)
var partStartIndex int
var partStartOffset = startOffset
// Skip parts until final offset maps to a particular part offset.
for i, part := range objInfo.Parts {
decryptedSize, err := sio.DecryptedSize(uint64(part.Size))
if err != nil {
return nil, -1, -1, errObjectTampered
}
partStartIndex = i
// Offset is smaller than size we have reached the
// proper part offset, break out we start from
// this part index.
if partStartOffset < int64(decryptedSize) {
break
}
// Continue to look for next part.
partStartOffset -= int64(decryptedSize)
}
startSeqNum := partStartOffset / SSEDAREPackageBlockSize
partEncRelOffset := int64(startSeqNum) * (SSEDAREPackageBlockSize + SSEDAREPackageMetaSize)
w := &DecryptBlocksWriter{
writer: client,
startSeqNum: uint32(startSeqNum),
partEncRelOffset: partEncRelOffset,
parts: objInfo.Parts,
partIndex: partStartIndex,
req: r,
bucket: bucket,
object: object,
customerKeyHeader: r.Header.Get(crypto.SSECKey),
copySource: copySource,
}
w.metadata = map[string]string{}
// Copy encryption metadata for internal use.
for k, v := range objInfo.UserDefined {
w.metadata[k] = v
}
// Purge all the encryption headers.
delete(objInfo.UserDefined, crypto.SSEIV)
delete(objInfo.UserDefined, crypto.SSESealAlgorithm)
delete(objInfo.UserDefined, crypto.SSECSealedKey)
delete(objInfo.UserDefined, crypto.SSEMultipart)
if crypto.S3.IsEncrypted(objInfo.UserDefined) {
delete(objInfo.UserDefined, crypto.S3SealedKey)
delete(objInfo.UserDefined, crypto.S3KMSKeyID)
delete(objInfo.UserDefined, crypto.S3KMSSealedKey)
}
if w.copySource {
w.customerKeyHeader = r.Header.Get(crypto.SSECopyKey)
}
if err := w.buildDecrypter(w.parts[w.partIndex].Number); err != nil {
return nil, 0, 0, err
}
return w, encStartOffset, encLength, nil
}
// getEncryptedMultipartsOffsetLength - fetch sequence number, encrypted start offset and encrypted length.
func getEncryptedMultipartsOffsetLength(offset, length int64, obj ObjectInfo) (uint32, int64, int64) {
// Calculate encrypted offset of a multipart object
computeEncOffset := func(off int64, obj ObjectInfo) (seqNumber uint32, encryptedOffset int64, err error) {
var curPartEndOffset uint64
var prevPartsEncSize int64
for _, p := range obj.Parts {
size, decErr := sio.DecryptedSize(uint64(p.Size))
if decErr != nil {
err = errObjectTampered // assign correct error type
return
}
if off < int64(curPartEndOffset+size) {
seqNumber, encryptedOffset, _ = getEncryptedSinglePartOffsetLength(off-int64(curPartEndOffset), 1, obj)
encryptedOffset += int64(prevPartsEncSize)
break
}
curPartEndOffset += size
prevPartsEncSize += p.Size
}
return
}
// Calculate the encrypted start offset corresponding to the plain offset
seqNumber, encStartOffset, _ := computeEncOffset(offset, obj)
// Calculate also the encrypted end offset corresponding to plain offset + plain length
_, encEndOffset, _ := computeEncOffset(offset+length-1, obj)
// encLength is the diff between encrypted end offset and encrypted start offset + one package size
// to ensure all encrypted data are covered
encLength := encEndOffset - encStartOffset + (64*1024 + 32)
// Calculate total size of all parts
var totalPartsLength int64
for _, p := range obj.Parts {
totalPartsLength += p.Size
}
// Set encLength to maximum possible value if it exceeded total parts size
if encLength+encStartOffset > totalPartsLength {
encLength = totalPartsLength - encStartOffset
}
return seqNumber, encStartOffset, encLength
}
// getEncryptedSinglePartOffsetLength - fetch sequence number, encrypted start offset and encrypted length.
func getEncryptedSinglePartOffsetLength(offset, length int64, objInfo ObjectInfo) (seqNumber uint32, encOffset int64, encLength int64) {
onePkgSize := int64(SSEDAREPackageBlockSize + SSEDAREPackageMetaSize)
seqNumber = uint32(offset / SSEDAREPackageBlockSize)
encOffset = int64(seqNumber) * onePkgSize
// The math to compute the encrypted length is always
// originalLength i.e (offset+length-1) to be divided under
// 64KiB blocks which is the payload size for each encrypted
// block. This is then multiplied by final package size which
// is basically 64KiB + 32. Finally negate the encrypted offset
// to get the final encrypted length on disk.
encLength = ((offset+length)/SSEDAREPackageBlockSize)*onePkgSize - encOffset
// Check for the remainder, to figure if we need one extract package to read from.
if (offset+length)%SSEDAREPackageBlockSize > 0 {
encLength += onePkgSize
}
if encLength+encOffset > objInfo.EncryptedSize() {
encLength = objInfo.EncryptedSize() - encOffset
}
return seqNumber, encOffset, encLength
}
// DecryptedSize returns the size of the object after decryption in bytes.
// It returns an error if the object is not encrypted or marked as encrypted
// but has an invalid size.
func (o *ObjectInfo) DecryptedSize() (int64, error) {
if !crypto.IsEncrypted(o.UserDefined) {
return 0, errors.New("Cannot compute decrypted size of an unencrypted object")
}
if !isEncryptedMultipart(*o) {
size, err := sio.DecryptedSize(uint64(o.Size))
if err != nil {
err = errObjectTampered // assign correct error type
}
return int64(size), err
}
var size int64
for _, part := range o.Parts {
partSize, err := sio.DecryptedSize(uint64(part.Size))
if err != nil {
return 0, errObjectTampered
}
size += int64(partSize)
}
return size, nil
}
// For encrypted objects, the ETag sent by client if available
// is stored in encrypted form in the backend. Decrypt the ETag
// if ETag was previously encrypted.
func getDecryptedETag(headers http.Header, objInfo ObjectInfo, copySource bool) (decryptedETag string) {
var (
key [32]byte
err error
)
// If ETag is contentMD5Sum return it as is.
if len(objInfo.ETag) == 32 {
return objInfo.ETag
}
if crypto.IsMultiPart(objInfo.UserDefined) {
return objInfo.ETag
}
if crypto.SSECopy.IsRequested(headers) {
key, err = crypto.SSECopy.ParseHTTP(headers)
if err != nil {
return objInfo.ETag
}
}
// As per AWS S3 Spec, ETag for SSE-C encrypted objects need not be MD5Sum of the data.
// Since server side copy with same source and dest just replaces the ETag, we save
// encrypted content MD5Sum as ETag for both SSE-C and SSE-S3, we standardize the ETag
//encryption across SSE-C and SSE-S3, and only return last 32 bytes for SSE-C
if crypto.SSEC.IsEncrypted(objInfo.UserDefined) && !copySource {
return objInfo.ETag[len(objInfo.ETag)-32:]
}
objectEncryptionKey, err := decryptObjectInfo(key[:], objInfo.Bucket, objInfo.Name, objInfo.UserDefined)
if err != nil {
return objInfo.ETag
}
return tryDecryptETag(objectEncryptionKey, objInfo.ETag, false)
}
// helper to decrypt Etag given object encryption key and encrypted ETag
func tryDecryptETag(key []byte, encryptedETag string, ssec bool) string {
// ETag for SSE-C encrypted objects need not be content MD5Sum.While encrypted
// md5sum is stored internally, return just the last 32 bytes of hex-encoded and
// encrypted md5sum string for SSE-C
if ssec {
return encryptedETag[len(encryptedETag)-32:]
}
var objectKey crypto.ObjectKey
copy(objectKey[:], key)
encBytes, err := hex.DecodeString(encryptedETag)
if err != nil {
return encryptedETag
}
etagBytes, err := objectKey.UnsealETag(encBytes)
if err != nil {
return encryptedETag
}
return hex.EncodeToString(etagBytes)
}
// GetDecryptedRange - To decrypt the range (off, length) of the
// decrypted object stream, we need to read the range (encOff,
// encLength) of the encrypted object stream to decrypt it, and
// compute skipLen, the number of bytes to skip in the beginning of
// the encrypted range.
//
// In addition we also compute the object part number for where the
// requested range starts, along with the DARE sequence number within
// that part. For single part objects, the partStart will be 0.
func (o *ObjectInfo) GetDecryptedRange(rs *HTTPRangeSpec) (encOff, encLength, skipLen int64, seqNumber uint32, partStart int, err error) {
if !crypto.IsEncrypted(o.UserDefined) {
err = errors.New("Object is not encrypted")
return
}
if rs == nil {
// No range, so offsets refer to the whole object.
return 0, int64(o.Size), 0, 0, 0, nil
}
// Assemble slice of (decrypted) part sizes in `sizes`
var sizes []int64
var decObjSize int64 // decrypted total object size
if isEncryptedMultipart(*o) {
sizes = make([]int64, len(o.Parts))
for i, part := range o.Parts {
var partSize uint64
partSize, err = sio.DecryptedSize(uint64(part.Size))
if err != nil {
err = errObjectTampered
return
}
sizes[i] = int64(partSize)
decObjSize += int64(partSize)
}
} else {
var partSize uint64
partSize, err = sio.DecryptedSize(uint64(o.Size))
if err != nil {
err = errObjectTampered
return
}
sizes = []int64{int64(partSize)}
decObjSize = sizes[0]
}
var off, length int64
off, length, err = rs.GetOffsetLength(decObjSize)
if err != nil {
return
}
// At this point, we have:
//
// 1. the decrypted part sizes in `sizes` (single element for
// single part object) and total decrypted object size `decObjSize`
//
// 2. the (decrypted) start offset `off` and (decrypted)
// length to read `length`
//
// These are the inputs to the rest of the algorithm below.
// Locate the part containing the start of the required range
var partEnd int
var cumulativeSum, encCumulativeSum int64
for i, size := range sizes {
if off < cumulativeSum+size {
partStart = i
break
}
cumulativeSum += size
encPartSize, _ := sio.EncryptedSize(uint64(size))
encCumulativeSum += int64(encPartSize)
}
// partStart is always found in the loop above,
// because off is validated.
sseDAREEncPackageBlockSize := int64(SSEDAREPackageBlockSize + SSEDAREPackageMetaSize)
startPkgNum := (off - cumulativeSum) / SSEDAREPackageBlockSize
// Now we can calculate the number of bytes to skip
skipLen = (off - cumulativeSum) % SSEDAREPackageBlockSize
encOff = encCumulativeSum + startPkgNum*sseDAREEncPackageBlockSize
// Locate the part containing the end of the required range
endOffset := off + length - 1
for i1, size := range sizes[partStart:] {
i := partStart + i1
if endOffset < cumulativeSum+size {
partEnd = i
break
}
cumulativeSum += size
encPartSize, _ := sio.EncryptedSize(uint64(size))
encCumulativeSum += int64(encPartSize)
}
// partEnd is always found in the loop above, because off and
// length are validated.
endPkgNum := (endOffset - cumulativeSum) / SSEDAREPackageBlockSize
// Compute endEncOffset with one additional DARE package (so
// we read the package containing the last desired byte).
endEncOffset := encCumulativeSum + (endPkgNum+1)*sseDAREEncPackageBlockSize
// Check if the DARE package containing the end offset is a
// full sized package (as the last package in the part may be
// smaller)
lastPartSize, _ := sio.EncryptedSize(uint64(sizes[partEnd]))
if endEncOffset > encCumulativeSum+int64(lastPartSize) {
endEncOffset = encCumulativeSum + int64(lastPartSize)
}
encLength = endEncOffset - encOff
// Set the sequence number as the starting package number of
// the requested block
seqNumber = uint32(startPkgNum)
return encOff, encLength, skipLen, seqNumber, partStart, nil
}
// EncryptedSize returns the size of the object after encryption.
// An encrypted object is always larger than a plain object
// except for zero size objects.
func (o *ObjectInfo) EncryptedSize() int64 {
size, err := sio.EncryptedSize(uint64(o.Size))
if err != nil {
// This cannot happen since AWS S3 allows parts to be 5GB at most
// sio max. size is 256 TB
reqInfo := (&logger.ReqInfo{}).AppendTags("size", strconv.FormatUint(size, 10))
ctx := logger.SetReqInfo(context.Background(), reqInfo)
logger.CriticalIf(ctx, err)
}
return int64(size)
}
// DecryptCopyObjectInfo tries to decrypt the provided object if it is encrypted.
// It fails if the object is encrypted and the HTTP headers don't contain
// SSE-C headers or the object is not encrypted but SSE-C headers are provided. (AWS behavior)
// DecryptObjectInfo returns 'ErrNone' if the object is not encrypted or the
// decryption succeeded.
//
// DecryptCopyObjectInfo also returns whether the object is encrypted or not.
func DecryptCopyObjectInfo(info *ObjectInfo, headers http.Header) (errCode APIErrorCode, encrypted bool) {
// Directories are never encrypted.
if info.IsDir {
return ErrNone, false
}
if errCode, encrypted = ErrNone, crypto.IsEncrypted(info.UserDefined); !encrypted && crypto.SSECopy.IsRequested(headers) {
errCode = ErrInvalidEncryptionParameters
} else if encrypted {
if (!crypto.SSECopy.IsRequested(headers) && crypto.SSEC.IsEncrypted(info.UserDefined)) ||
(crypto.SSECopy.IsRequested(headers) && crypto.S3.IsEncrypted(info.UserDefined)) {
errCode = ErrSSEEncryptedObject
return
}
var err error
if info.Size, err = info.DecryptedSize(); err != nil {
errCode = toAPIErrorCode(context.Background(), err)
}
}
return
}
// DecryptObjectInfo tries to decrypt the provided object if it is encrypted.
// It fails if the object is encrypted and the HTTP headers don't contain
// SSE-C headers or the object is not encrypted but SSE-C headers are provided. (AWS behavior)
// DecryptObjectInfo returns 'ErrNone' if the object is not encrypted or the
// decryption succeeded.
//
// DecryptObjectInfo also returns whether the object is encrypted or not.
func DecryptObjectInfo(info *ObjectInfo, headers http.Header) (encrypted bool, err error) {
// Directories are never encrypted.
if info.IsDir {
return false, nil
}
// disallow X-Amz-Server-Side-Encryption header on HEAD and GET
if crypto.S3.IsRequested(headers) {
err = errInvalidEncryptionParameters
return
}
if err, encrypted = nil, crypto.IsEncrypted(info.UserDefined); !encrypted && crypto.SSEC.IsRequested(headers) {
err = errInvalidEncryptionParameters
} else if encrypted {
if (crypto.SSEC.IsEncrypted(info.UserDefined) && !crypto.SSEC.IsRequested(headers)) ||
(crypto.S3.IsEncrypted(info.UserDefined) && crypto.SSEC.IsRequested(headers)) {
err = errEncryptedObject
return
}
_, err = info.DecryptedSize()
if crypto.IsEncrypted(info.UserDefined) && !crypto.IsMultiPart(info.UserDefined) {
info.ETag = getDecryptedETag(headers, *info, false)
}
}
return
}
// The customer key in the header is used by the gateway for encryption in the case of
// s3 gateway double encryption. A new client key is derived from the customer provided
// key to be sent to the s3 backend for encryption at the backend.
func deriveClientKey(clientKey [32]byte, bucket, object string) [32]byte {
var key [32]byte
mac := hmac.New(sha256.New, clientKey[:])
mac.Write([]byte(crypto.SSEC.String()))
mac.Write([]byte(path.Join(bucket, object)))
mac.Sum(key[:0])
return key
}
// set encryption options for pass through to backend in the case of gateway and UserDefined metadata
func getDefaultOpts(header http.Header, copySource bool, metadata map[string]string) (opts ObjectOptions, err error) {
var clientKey [32]byte
var sse encrypt.ServerSide
if copySource {
if crypto.SSECopy.IsRequested(header) {
clientKey, err = crypto.SSECopy.ParseHTTP(header)
if err != nil {
return
}
if sse, err = encrypt.NewSSEC(clientKey[:]); err != nil {
return
}
return ObjectOptions{ServerSideEncryption: encrypt.SSECopy(sse), UserDefined: metadata}, nil
}
return
}
if crypto.SSEC.IsRequested(header) {
clientKey, err = crypto.SSEC.ParseHTTP(header)
if err != nil {
return
}
if sse, err = encrypt.NewSSEC(clientKey[:]); err != nil {
return
}
return ObjectOptions{ServerSideEncryption: sse, UserDefined: metadata}, nil
}
if crypto.S3.IsRequested(header) || (metadata != nil && crypto.S3.IsEncrypted(metadata)) {
return ObjectOptions{ServerSideEncryption: encrypt.NewSSE(), UserDefined: metadata}, nil
}
return ObjectOptions{UserDefined: metadata}, nil
}
// get ObjectOptions for GET calls from encryption headers
func getOpts(ctx context.Context, r *http.Request, bucket, object string) (ObjectOptions, error) {
var (
encryption encrypt.ServerSide
opts ObjectOptions
)
if GlobalGatewaySSE.SSEC() && crypto.SSEC.IsRequested(r.Header) {
key, err := crypto.SSEC.ParseHTTP(r.Header)
if err != nil {
return opts, err
}
derivedKey := deriveClientKey(key, bucket, object)
encryption, err = encrypt.NewSSEC(derivedKey[:])
logger.CriticalIf(ctx, err)
return ObjectOptions{ServerSideEncryption: encryption}, nil
}
// default case of passing encryption headers to backend
return getDefaultOpts(r.Header, false, nil)
}
// get ObjectOptions for PUT calls from encryption headers and metadata
func putOpts(ctx context.Context, r *http.Request, bucket, object string, metadata map[string]string) (opts ObjectOptions, err error) {
// In the case of multipart custom format, the metadata needs to be checked in addition to header to see if it
// is SSE-S3 encrypted, primarily because S3 protocol does not require SSE-S3 headers in PutObjectPart calls
if GlobalGatewaySSE.SSES3() && (crypto.S3.IsRequested(r.Header) || crypto.S3.IsEncrypted(metadata)) {
return ObjectOptions{ServerSideEncryption: encrypt.NewSSE(), UserDefined: metadata}, nil
}
if GlobalGatewaySSE.SSEC() && crypto.SSEC.IsRequested(r.Header) {
opts, err = getOpts(ctx, r, bucket, object)
opts.UserDefined = metadata
return
}
// default case of passing encryption headers and UserDefined metadata to backend
return getDefaultOpts(r.Header, false, metadata)
}
// get ObjectOptions for Copy calls with encryption headers provided on the target side and source side metadata
func copyDstOpts(ctx context.Context, r *http.Request, bucket, object string, metadata map[string]string) (opts ObjectOptions, err error) {
return putOpts(ctx, r, bucket, object, metadata)
}
// get ObjectOptions for Copy calls with encryption headers provided on the source side
func copySrcOpts(ctx context.Context, r *http.Request, bucket, object string) (ObjectOptions, error) {
var (
ssec encrypt.ServerSide
opts ObjectOptions
)
if GlobalGatewaySSE.SSEC() && crypto.SSECopy.IsRequested(r.Header) {
key, err := crypto.SSECopy.ParseHTTP(r.Header)
if err != nil {
return opts, err
}
derivedKey := deriveClientKey(key, bucket, object)
ssec, err = encrypt.NewSSEC(derivedKey[:])
if err != nil {
return opts, err
}
return ObjectOptions{ServerSideEncryption: encrypt.SSECopy(ssec)}, nil
}
// default case of passing encryption headers to backend
return getDefaultOpts(r.Header, true, nil)
}