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crypt: try not to return "unexpected EOF" error 

Before this change the code wasn't taking into account the error
io.ErrUnexpectedEOF that io.ReadFull can return properly. Sometimes
that error was being returned instead of a more specific and useful
error.

To fix this, io.ReadFull was replaced with the simpler
readers.ReadFill which is much easier to use correctly.
This commit is contained in:
Nick Craig-Wood 2023-03-06 17:49:50 +00:00
parent 07c4d95f38
commit d5afcf9e34
2 changed files with 12 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
backend/crypt/cipher.go
View File

@ -21,6 +21,7 @@ import (
"github.com/rclone/rclone/backend/crypt/pkcs7"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/accounting"
"github.com/rclone/rclone/lib/readers"
"github.com/rclone/rclone/lib/version"
"github.com/rfjakob/eme"
"golang.org/x/crypto/nacl/secretbox"
@ -609,7 +610,7 @@ func (n *nonce) pointer() *[fileNonceSize]byte {
// fromReader fills the nonce from an io.Reader - normally the OSes
// crypto random number generator
func (n *nonce) fromReader(in io.Reader) error {
read, err := io.ReadFull(in, (*n)[:])
read, err := readers.ReadFill(in, (*n)[:])
if read != fileNonceSize {
return fmt.Errorf("short read of nonce: %w", err)
}
@ -708,14 +709,12 @@ func (fh *encrypter) Read(p []byte) (n int, err error) {
// Read data
// FIXME should overlap the reads with a go-routine and 2 buffers?
readBuf := fh.readBuf[:blockDataSize]
n, err = io.ReadFull(fh.in, readBuf)
n, err = readers.ReadFill(fh.in, readBuf)
if n == 0 {
// err can't be nil since:
// n == len(buf) if and only if err == nil.
return fh.finish(err)
}
// possibly err != nil here, but we will process the
// data and the next call to ReadFull will return 0, err
// data and the next call to ReadFill will return 0, err
// Encrypt the block using the nonce
secretbox.Seal(fh.buf[:0], readBuf[:n], fh.nonce.pointer(), &fh.c.dataKey)
fh.bufIndex = 0
@ -783,8 +782,8 @@ func (c *Cipher) newDecrypter(rc io.ReadCloser) (*decrypter, error) {
}
// Read file header (magic + nonce)
readBuf := fh.readBuf[:fileHeaderSize]
_, err := io.ReadFull(fh.rc, readBuf)
if err == io.EOF || err == io.ErrUnexpectedEOF {
n, err := readers.ReadFill(fh.rc, readBuf)
if n < fileHeaderSize && err == io.EOF {
// This read from 0..fileHeaderSize-1 bytes
return nil, fh.finishAndClose(ErrorEncryptedFileTooShort)
} else if err != nil {
@ -845,10 +844,8 @@ func (c *Cipher) newDecrypterSeek(ctx context.Context, open OpenRangeSeek, offse
func (fh *decrypter) fillBuffer() (err error) {
// FIXME should overlap the reads with a go-routine and 2 buffers?
readBuf := fh.readBuf
n, err := io.ReadFull(fh.rc, readBuf)
n, err := readers.ReadFill(fh.rc, readBuf)
if n == 0 {
// err can't be nil since:
// n == len(buf) if and only if err == nil.
return err
}
// possibly err != nil here, but we will process the data and
@ -856,7 +853,7 @@ func (fh *decrypter) fillBuffer() (err error) {
// Check header + 1 byte exists
if n <= blockHeaderSize {
if err != nil {
if err != nil && err != io.EOF {
return err // return pending error as it is likely more accurate
}
return ErrorEncryptedFileBadHeader
@ -864,7 +861,7 @@ func (fh *decrypter) fillBuffer() (err error) {
// Decrypt the block using the nonce
_, ok := secretbox.Open(fh.buf[:0], readBuf[:n], fh.nonce.pointer(), &fh.c.dataKey)
if !ok {
if err != nil {
if err != nil && err != io.EOF {
return err // return pending error as it is likely more accurate
}
return ErrorEncryptedBadBlock

4
backend/crypt/cipher_test.go
View File

@ -1495,8 +1495,10 @@ func TestDecrypterRead(t *testing.T) {
case i == fileHeaderSize:
// This would normally produce an error *except* on the first block
expectedErr = nil
case i <= fileHeaderSize+blockHeaderSize:
expectedErr = ErrorEncryptedFileBadHeader
default:
expectedErr = io.ErrUnexpectedEOF
expectedErr = ErrorEncryptedBadBlock
}
if expectedErr != nil {
assert.EqualError(t, err, expectedErr.Error(), what)