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crypt: try not to return "unexpected EOF" error

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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
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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)