116 lines
3.4 KiB
Go
116 lines
3.4 KiB
Go
package nametransform
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
"path/filepath"
|
|
"syscall"
|
|
|
|
"golang.org/x/sys/unix"
|
|
|
|
"github.com/rfjakob/gocryptfs/internal/cryptocore"
|
|
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
|
|
"github.com/rfjakob/gocryptfs/internal/tlog"
|
|
)
|
|
|
|
const (
|
|
// DirIVLen is identical to AES block size
|
|
DirIVLen = 16
|
|
// DirIVFilename is the filename used to store directory IV.
|
|
// Exported because we have to ignore this name in directory listing.
|
|
DirIVFilename = "gocryptfs.diriv"
|
|
)
|
|
|
|
// ReadDirIVAt reads "gocryptfs.diriv" from the directory that is opened as "dirfd".
|
|
// Using the dirfd makes it immune to concurrent renames of the directory.
|
|
func ReadDirIVAt(dirfd int) (iv []byte, err error) {
|
|
fdRaw, err := syscallcompat.Openat(dirfd, DirIVFilename,
|
|
syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("openat failed: %v", err)
|
|
}
|
|
fd := os.NewFile(uintptr(fdRaw), DirIVFilename)
|
|
defer fd.Close()
|
|
return fdReadDirIV(fd)
|
|
}
|
|
|
|
// allZeroDirIV is preallocated to quickly check if the data read from disk is all zero
|
|
var allZeroDirIV = make([]byte, DirIVLen)
|
|
|
|
// fdReadDirIV reads and verifies the DirIV from an opened gocryptfs.diriv file.
|
|
func fdReadDirIV(fd *os.File) (iv []byte, err error) {
|
|
// We want to detect if the file is bigger than DirIVLen, so
|
|
// make the buffer 1 byte bigger than necessary.
|
|
iv = make([]byte, DirIVLen+1)
|
|
n, err := fd.Read(iv)
|
|
if err != nil && err != io.EOF {
|
|
return nil, fmt.Errorf("read failed: %v", err)
|
|
}
|
|
iv = iv[0:n]
|
|
if len(iv) != DirIVLen {
|
|
return nil, fmt.Errorf("wanted %d bytes, got %d", DirIVLen, len(iv))
|
|
}
|
|
if bytes.Equal(iv, allZeroDirIV) {
|
|
return nil, fmt.Errorf("diriv is all-zero")
|
|
}
|
|
return iv, nil
|
|
}
|
|
|
|
// WriteDirIVAt - create a new gocryptfs.diriv file in the directory opened at
|
|
// "dirfd". On error we try to delete the incomplete file.
|
|
// This function is exported because it is used from fusefrontend, main,
|
|
// and also the automated tests.
|
|
func WriteDirIVAt(dirfd int) error {
|
|
iv := cryptocore.RandBytes(DirIVLen)
|
|
// 0400 permissions: gocryptfs.diriv should never be modified after creation.
|
|
// Don't use "ioutil.WriteFile", it causes trouble on NFS:
|
|
// https://github.com/rfjakob/gocryptfs/commit/7d38f80a78644c8ec4900cc990bfb894387112ed
|
|
fd, err := syscallcompat.Openat(dirfd, DirIVFilename, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0400)
|
|
if err != nil {
|
|
tlog.Warn.Printf("WriteDirIV: Openat: %v", err)
|
|
return err
|
|
}
|
|
// Wrap the fd in an os.File - we need the write retry logic.
|
|
f := os.NewFile(uintptr(fd), DirIVFilename)
|
|
_, err = f.Write(iv)
|
|
if err != nil {
|
|
f.Close()
|
|
// It is normal to get ENOSPC here
|
|
if !syscallcompat.IsENOSPC(err) {
|
|
tlog.Warn.Printf("WriteDirIV: Write: %v", err)
|
|
}
|
|
// Delete incomplete gocryptfs.diriv file
|
|
syscallcompat.Unlinkat(dirfd, DirIVFilename, 0)
|
|
return err
|
|
}
|
|
err = f.Close()
|
|
if err != nil {
|
|
tlog.Warn.Printf("WriteDirIV: Close: %v", err)
|
|
// Delete incomplete gocryptfs.diriv file
|
|
syscallcompat.Unlinkat(dirfd, DirIVFilename, 0)
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// encryptAndHashName encrypts "name" and hashes it to a longname if it is
|
|
// too long.
|
|
func (be *NameTransform) EncryptAndHashName(name string, iv []byte) string {
|
|
cName := be.EncryptName(name, iv)
|
|
if be.longNames && len(cName) > unix.NAME_MAX {
|
|
return be.HashLongName(cName)
|
|
}
|
|
return cName
|
|
}
|
|
|
|
// Dir is like filepath.Dir but returns "" instead of ".".
|
|
func Dir(path string) string {
|
|
d := filepath.Dir(path)
|
|
if d == "." {
|
|
return ""
|
|
}
|
|
return d
|
|
}
|