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libgocryptfs
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diriv: Move WriteDirIV() to cryptfs; add locking to Mkdir, Rmdir

This commit is contained in:
Jakob Unterwurzacher 2015-11-27 21:48:58 +01:00
parent decfc1ab79
commit bdd9249a52
3 changed files with 23 additions and 8 deletions
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9
cryptfs/names_diriv.go
View File

@ -21,6 +21,15 @@ func (be *CryptFS) readDirIV(dir string) (iv []byte, err error) {
return iv, nil
}
// WriteDirIV - create diriv file inside "dir" (absolute path)
// This function is exported because it is used from pathfs_frontend
func (be *CryptFS) WriteDirIV(dir string) error {
iv := RandBytes(DIRIV_LEN)
file := filepath.Join(dir, DIRIV_FILENAME)
// 0444 permissions: the file is not secret but should not be written to
return ioutil.WriteFile(file, iv, 0444)
}
// EncryptPathDirIV - encrypt path using CBC with DirIV
func (be *CryptFS) EncryptPathDirIV(plainPath string, rootDir string) (string, error) {
if be.plaintextNames {

18
pathfs_frontend/fs.go
View File

@ -5,7 +5,6 @@ import (
"fmt"
"sync"
"syscall"
"io/ioutil"
"os"
"path/filepath"
"time"
@ -20,7 +19,11 @@ type FS struct {
*cryptfs.CryptFS
pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
backingDir string // Backing directory, cipherdir
dirivLock sync.RWMutex // Global lock that is taken if any "gocryptfs.diriv" file is modified
// dirIVLock: Lock()ed if any "gocryptfs.diriv" file is modified
// Readers must RLock() it to prevent them from seeing intermediate
// states
dirIVLock sync.RWMutex
}
// Encrypted FUSE overlay filesystem
@ -217,16 +220,15 @@ func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fu
if err != nil {
return fuse.ToStatus(err)
}
diriv := cryptfs.RandBytes(cryptfs.DIRIV_LEN)
dirivPath := filepath.Join(encPath, cryptfs.DIRIV_FILENAME)
// Create directory
fs.dirIVLock.Lock()
defer fs.dirIVLock.Unlock()
err = os.Mkdir(encPath, os.FileMode(mode))
if err != nil {
return fuse.ToStatus(err)
}
// Create gocryptfs.diriv inside
// 0444 permissions: the file is not secret but should not be written to
err = ioutil.WriteFile(dirivPath, diriv, 0444)
err = fs.CryptFS.WriteDirIV(encPath)
if err != nil {
// This should not happen
cryptfs.Warn.Printf("Creating %s in dir %s failed: %v\n", cryptfs.DIRIV_FILENAME, encPath, err)
@ -282,8 +284,8 @@ func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
tmpName := fmt.Sprintf("gocryptfs.diriv.rmdir.%d", st.Ino)
tmpDirivPath := filepath.Join(parentDir, tmpName)
cryptfs.Debug.Printf("Rmdir: Renaming %s to %s\n", cryptfs.DIRIV_FILENAME, tmpDirivPath)
fs.dirivLock.Lock() // directory will be in an inconsistent state after the rename
defer fs.dirivLock.Unlock()
fs.dirIVLock.Lock() // directory will be in an inconsistent state after the rename
defer fs.dirIVLock.Unlock()
err = os.Rename(dirivPath, tmpDirivPath)
if err != nil {
cryptfs.Warn.Printf("Rmdir: Renaming %s to %s failed: %v\n", cryptfs.DIRIV_FILENAME, tmpDirivPath, err)

4
pathfs_frontend/names.go
View File

@ -3,9 +3,13 @@ package pathfs_frontend
// This file handles filename encryption
func (fs *FS) encryptPath(plainPath string) (string, error) {
fs.dirIVLock.RLock()
defer fs.dirIVLock.RUnlock()
return fs.CryptFS.EncryptPathDirIV(plainPath, fs.backingDir)
}
func (fs *FS) decryptPath(cipherPath string) (string, error) {
fs.dirIVLock.RLock()
defer fs.dirIVLock.RUnlock()
return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.backingDir)
}