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minio/cmd/encryption-v1.go

841 lines
27 KiB

/*
* MinIO Cloud Storage, (C) 2017-2020 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 (
"bufio"
"crypto/hmac"
"crypto/rand"
"crypto/subtle"
"encoding/binary"
"encoding/hex"
"errors"
"io"
"net/http"
"path"
"strconv"
"strings"
"github.com/minio/minio/cmd/crypto"
xhttp "github.com/minio/minio/cmd/http"
"github.com/minio/minio/cmd/logger"
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
)
// 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 Erasure 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(GlobalKMS.DefaultKeyID(), 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, GlobalKMS.DefaultKeyID(), encKey, sealedKey)
return nil
}
}
func newEncryptMetadata(key []byte, bucket, object string, metadata map[string]string, sseS3 bool) (crypto.ObjectKey, error) {
var sealedKey crypto.SealedKey
if sseS3 {
if GlobalKMS == nil {
return crypto.ObjectKey{}, errKMSNotConfigured
}
key, encKey, err := GlobalKMS.GenerateKey(GlobalKMS.DefaultKeyID(), crypto.Context{bucket: path.Join(bucket, object)})
if err != nil {
return crypto.ObjectKey{}, err
}
objectKey := crypto.GenerateKey(key, rand.Reader)
sealedKey = objectKey.Seal(key, crypto.GenerateIV(rand.Reader), crypto.S3.String(), bucket, object)
crypto.S3.CreateMetadata(metadata, GlobalKMS.DefaultKeyID(), 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) (io.Reader, crypto.ObjectKey, error) {
objectEncryptionKey, err := newEncryptMetadata(key, bucket, object, metadata, sseS3)
if err != nil {
return nil, crypto.ObjectKey{}, err
}
reader, err := sio.EncryptReader(content, sio.Config{Key: objectEncryptionKey[:], MinVersion: sio.Version20})
if err != nil {
return nil, crypto.ObjectKey{}, 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) (io.Reader, crypto.ObjectKey, error) {
if crypto.S3.IsRequested(r.Header) && crypto.SSEC.IsRequested(r.Header) {
return nil, crypto.ObjectKey{}, crypto.ErrIncompatibleEncryptionMethod
}
if r.ContentLength > encryptBufferThreshold {
// The encryption reads in blocks of 64KB.
// We add a buffer on bigger files to reduce the number of syscalls upstream.
content = bufio.NewReaderSize(content, encryptBufferSize)
}
var key []byte
if crypto.SSEC.IsRequested(r.Header) {
var err error
key, err = ParseSSECustomerRequest(r)
if err != nil {
return nil, crypto.ObjectKey{}, err
}
}
return newEncryptReader(content, key, bucket, object, metadata, crypto.S3.IsRequested(r.Header))
}
func decryptObjectInfo(key []byte, bucket, object string, metadata map[string]string) ([]byte, error) {
switch {
default:
return nil, errObjectTampered
case crypto.S3.IsEncrypted(metadata) && isCacheEncrypted(metadata):
if globalCacheKMS == nil {
return nil, errKMSNotConfigured
}
keyID, kmsKey, sealedKey, err := crypto.S3.ParseMetadata(metadata)
if err != nil {
return nil, err
}
extKey, err := globalCacheKMS.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.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
}
}
// 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)
}
func newDecryptReaderWithObjectKey(client io.Reader, objectEncryptionKey []byte, seqNumber uint32) (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(xhttp.AmzServerSideEncryptionCustomerKey),
copySource: copySource,
metadata: cloneMSS(oi.UserDefined),
}
if w.copySource {
w.customerKeyHeader = h.Get(xhttp.AmzServerSideEncryptionCopyCustomerKey)
}
if err := w.buildDecrypter(w.parts[w.partIndex].Number); err != nil {
return nil, err
}
return w, nil
}
// 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 := cloneMSS(d.metadata)
// 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(xhttp.AmzServerSideEncryptionCopyCustomerKey, d.customerKeyHeader)
key, err = ParseSSECopyCustomerRequest(d.header, d.metadata)
}
} else {
if crypto.SSEC.IsEncrypted(d.metadata) {
d.header.Set(xhttp.AmzServerSideEncryptionCustomerKey, 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)
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
}
// 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
}
// DecryptETag decrypts the ETag that is part of given object
// with the given object encryption key.
//
// However, DecryptETag does not try to decrypt the ETag if
// it consists of a 128 bit hex value (32 hex chars) and exactly
// one '-' followed by a 32-bit number.
// This special case adresses randomly-generated ETags generated
// by the MinIO server when running in non-compat mode. These
// random ETags are not encrypt.
//
// Calling DecryptETag with a non-randomly generated ETag will
// fail.
func DecryptETag(key crypto.ObjectKey, object ObjectInfo) (string, error) {
if n := strings.Count(object.ETag, "-"); n > 0 {
if n != 1 {
return "", errObjectTampered
}
i := strings.IndexByte(object.ETag, '-')
if len(object.ETag[:i]) != 32 {
return "", errObjectTampered
}
if _, err := hex.DecodeString(object.ETag[:32]); err != nil {
return "", errObjectTampered
}
if _, err := strconv.ParseInt(object.ETag[i+1:], 10, 32); err != nil {
return "", errObjectTampered
}
return object.ETag, nil
}
etag, err := hex.DecodeString(object.ETag)
if err != nil {
return "", err
}
etag, err = key.UnsealETag(etag)
if err != nil {
return "", err
}
return hex.EncodeToString(etag), 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, 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(GlobalContext, reqInfo)
logger.CriticalIf(ctx, err)
}
return int64(size)
}
// 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, r *http.Request) (encrypted bool, err error) {
// Directories are never encrypted.
if info.IsDir {
return false, nil
}
if r == nil {
return false, errInvalidArgument
}
headers := r.Header
// disallow X-Amz-Server-Side-Encryption header on HEAD and GET
switch r.Method {
case http.MethodGet, http.MethodHead:
if crypto.S3.IsRequested(headers) {
return false, errInvalidEncryptionParameters
}
}
encrypted = crypto.IsEncrypted(info.UserDefined)
if !encrypted && crypto.SSEC.IsRequested(headers) && r.Header.Get(xhttp.AmzCopySource) == "" {
return false, errInvalidEncryptionParameters
}
if encrypted {
if crypto.SSEC.IsEncrypted(info.UserDefined) {
if !(crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers)) {
return encrypted, errEncryptedObject
}
}
if crypto.S3.IsEncrypted(info.UserDefined) && r.Header.Get(xhttp.AmzCopySource) == "" {
if crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers) {
return encrypted, errEncryptedObject
}
}
if _, err = info.DecryptedSize(); err != nil {
return encrypted, err
}
if crypto.IsEncrypted(info.UserDefined) && !crypto.IsMultiPart(info.UserDefined) {
info.ETag = getDecryptedETag(headers, *info, false)
}
}
return encrypted, nil
}
// 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
}