package pathfs_frontend import ( "encoding/base64" "fmt" "os" "path/filepath" "sync" "syscall" "time" "github.com/hanwen/go-fuse/fuse" "github.com/hanwen/go-fuse/fuse/nodefs" "github.com/hanwen/go-fuse/fuse/pathfs" "github.com/rfjakob/gocryptfs/cryptfs" ) type FS struct { *cryptfs.CryptFS pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go args Args // Stores configuration arguments // 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 func NewFS(args Args) *FS { return &FS{ CryptFS: cryptfs.NewCryptFS(args.Masterkey, args.OpenSSL, args.PlaintextNames), FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir), args: args, } } // GetBackingPath - get the absolute encrypted path of the backing file // from the relative plaintext path "relPath" func (fs *FS) getBackingPath(relPath string) (string, error) { cPath, err := fs.encryptPath(relPath) if err != nil { return "", err } cAbsPath := filepath.Join(fs.args.Cipherdir, cPath) cryptfs.Debug.Printf("getBackingPath: %s + %s -> %s\n", fs.args.Cipherdir, relPath, cAbsPath) return cAbsPath, nil } func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) { cryptfs.Debug.Printf("FS.GetAttr('%s')\n", name) if fs.CryptFS.IsFiltered(name) { return nil, fuse.EPERM } cName, err := fs.encryptPath(name) if err != nil { return nil, fuse.ToStatus(err) } a, status := fs.FileSystem.GetAttr(cName, context) if a == nil { cryptfs.Debug.Printf("FS.GetAttr failed: %s\n", status.String()) return a, status } if a.IsRegular() { a.Size = fs.CipherSizeToPlainSize(a.Size) } else if a.IsSymlink() { target, _ := fs.Readlink(name, context) a.Size = uint64(len(target)) } return a, status } func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) { cryptfs.Debug.Printf("OpenDir(%s)\n", dirName) cDirName, err := fs.encryptPath(dirName) if err != nil { return nil, fuse.ToStatus(err) } // Read ciphertext directory cipherEntries, status := fs.FileSystem.OpenDir(cDirName, context) if cipherEntries == nil { return nil, status } // Get DirIV (stays zero if DirIV if off) cachedIV := make([]byte, cryptfs.DIRIV_LEN) if fs.args.DirIV { // Read the DirIV once and use it for all later name decryptions cDirAbsPath := filepath.Join(fs.args.Cipherdir, cDirName) cachedIV, err = fs.CryptFS.ReadDirIV(cDirAbsPath) if err != nil { return nil, fuse.ToStatus(err) } } // Decrypt filenames var plain []fuse.DirEntry for i := range cipherEntries { cName := cipherEntries[i].Name if dirName == "" && cName == cryptfs.ConfDefaultName { // silently ignore "gocryptfs.conf" in the top level dir continue } if fs.args.DirIV && cName == cryptfs.DIRIV_FILENAME { // silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled continue } var name string name, err = fs.CryptFS.DecryptName(cName, cachedIV) if err != nil { cryptfs.Warn.Printf("Invalid name \"%s\" in dir \"%s\": %s\n", cName, dirName, err) continue } cipherEntries[i].Name = name plain = append(plain, cipherEntries[i]) } return plain, status } // We always need read access to do read-modify-write cycles func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) { newFlags = int(flags) if newFlags&os.O_WRONLY > 0 { writeOnly = true newFlags = newFlags ^ os.O_WRONLY | os.O_RDWR } // We also cannot open the file in append mode, we need to seek back for RMW newFlags = newFlags &^ os.O_APPEND return newFlags, writeOnly } func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) { if fs.CryptFS.IsFiltered(path) { return nil, fuse.EPERM } iflags, writeOnly := fs.mangleOpenFlags(flags) cPath, err := fs.getBackingPath(path) if err != nil { cryptfs.Debug.Printf("Open: getBackingPath: %v\n", err) return nil, fuse.ToStatus(err) } cryptfs.Debug.Printf("Open: %s\n", cPath) f, err := os.OpenFile(cPath, iflags, 0666) if err != nil { return nil, fuse.ToStatus(err) } return NewFile(f, writeOnly, fs.CryptFS), fuse.OK } func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return nil, fuse.EPERM } iflags, writeOnly := fs.mangleOpenFlags(flags) cPath, err := fs.getBackingPath(path) if err != nil { return nil, fuse.ToStatus(err) } f, err := os.OpenFile(cPath, iflags|os.O_CREATE, os.FileMode(mode)) if err != nil { return nil, fuse.ToStatus(err) } return NewFile(f, writeOnly, fs.CryptFS), fuse.OK } func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.encryptPath(path) if err != nil { return fuse.ToStatus(err) } return fs.FileSystem.Chmod(cPath, mode, context) } func (fs *FS) Chown(path string, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.encryptPath(path) if err != nil { return fuse.ToStatus(err) } return fs.FileSystem.Chown(cPath, uid, gid, context) } func (fs *FS) Mknod(path string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.encryptPath(path) if err != nil { return fuse.ToStatus(err) } return fs.FileSystem.Mknod(cPath, mode, dev, context) } func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code fuse.Status) { cryptfs.Warn.Printf("Truncate of a closed file is not supported, returning ENOSYS\n") return fuse.ENOSYS } func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.encryptPath(path) if err != nil { return fuse.ToStatus(err) } return fs.FileSystem.Utimens(cPath, Atime, Mtime, context) } func (fs *FS) Readlink(path string, context *fuse.Context) (out string, status fuse.Status) { cPath, err := fs.encryptPath(path) if err != nil { return "", fuse.ToStatus(err) } cTarget, status := fs.FileSystem.Readlink(cPath, context) if status != fuse.OK { return "", status } // Old filesystem: symlinks are encrypted like paths (CBC) if !fs.args.DirIV { target, err := fs.decryptPath(cTarget) if err != nil { cryptfs.Warn.Printf("Readlink: CBC decryption failed: %v", err) return "", fuse.EIO } return target, fuse.OK } // Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM) cBinTarget, err := base64.URLEncoding.DecodeString(cTarget) if err != nil { cryptfs.Warn.Printf("Readlink: %v\n", err) return "", fuse.EIO } target, err := fs.CryptFS.DecryptBlock([]byte(cBinTarget), 0, nil) if err != nil { cryptfs.Warn.Printf("Readlink: %v\n", err) return "", fuse.EIO } return string(target), fuse.OK } func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(relPath) { return fuse.EPERM } encPath, err := fs.getBackingPath(relPath) if err != nil { return fuse.ToStatus(err) } // The new directory may take the place of an older one that is still in the cache fs.CryptFS.DirIVCacheEnc.Clear() // 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 err = 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) err2 := syscall.Rmdir(encPath) if err2 != nil { cryptfs.Warn.Printf("Mkdir: Rollback failed: %v\n", err2) } return fuse.ToStatus(err) } return fuse.OK } func (fs *FS) Unlink(path string, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.getBackingPath(path) if err != nil { return fuse.ToStatus(err) } return fuse.ToStatus(syscall.Unlink(cPath)) } func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) { encPath, err := fs.getBackingPath(name) if err != nil { return fuse.ToStatus(err) } // If the directory is not empty besides gocryptfs.diriv, do not even // attempt the dance around gocryptfs.diriv. fd, err := os.Open(encPath) if err != nil { return fuse.ToStatus(err) } defer fd.Close() list, err := fd.Readdirnames(10) if err != nil { return fuse.ToStatus(err) } if len(list) > 1 { return fuse.ToStatus(syscall.ENOTEMPTY) } // Move "gocryptfs.diriv" to the parent dir under name "gocryptfs.diriv.rmdir.INODENUMBER" var st syscall.Stat_t err = syscall.Fstat(int(fd.Fd()), &st) if err != nil { return fuse.ToStatus(err) } dirivPath := filepath.Join(encPath, cryptfs.DIRIV_FILENAME) parentDir := filepath.Dir(encPath) 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) // The directory is in an inconsistent state between rename and rmdir. Protect against // concurrent readers. fs.dirIVLock.Lock() 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) return fuse.ToStatus(err) } // Actual Rmdir err = syscall.Rmdir(encPath) if err != nil { // This can happen if another file in the directory was created in the // meantime, undo the rename err2 := os.Rename(tmpDirivPath, dirivPath) if err2 != nil { cryptfs.Warn.Printf("Rmdir: Rollback failed: %v\n", err2) } return fuse.ToStatus(err) } // Delete "gocryptfs.diriv.rmdir.INODENUMBER" err = syscall.Unlink(tmpDirivPath) if err != nil { cryptfs.Warn.Printf("Rmdir: Could not clean up %s: %v\n", tmpName, err) } // The now-deleted directory may have been in the DirIV cache. Clear it. fs.CryptFS.DirIVCacheEnc.Clear() return fuse.OK } func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) { cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", target, linkName) if fs.CryptFS.IsFiltered(linkName) { return fuse.EPERM } cPath, err := fs.getBackingPath(linkName) if err != nil { return fuse.ToStatus(err) } // Old filesystem: symlinks are encrypted like paths (CBC) if !fs.args.DirIV { cTarget, err := fs.encryptPath(target) if err != nil { cryptfs.Warn.Printf("Symlink: BUG: we should not get an error here: %v\n", err) return fuse.ToStatus(err) } err = os.Symlink(cTarget, cPath) return fuse.ToStatus(err) } // Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM) cBinTarget := fs.CryptFS.EncryptBlock([]byte(target), 0, nil) cTarget := base64.URLEncoding.EncodeToString(cBinTarget) err = os.Symlink(cTarget, cPath) cryptfs.Debug.Printf("Symlink: os.Symlink(%s, %s) = %v\n", cTarget, cPath, err) return fuse.ToStatus(err) } func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(newPath) { return fuse.EPERM } cOldPath, err := fs.getBackingPath(oldPath) if err != nil { return fuse.ToStatus(err) } cNewPath, err := fs.getBackingPath(newPath) if err != nil { return fuse.ToStatus(err) } // The Rename may cause a directory to take the place of another directory. // That directory may still be in the DirIV cache, clear it. fs.CryptFS.DirIVCacheEnc.Clear() return fs.FileSystem.Rename(cOldPath, cNewPath, context) } func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(newPath) { return fuse.EPERM } cOldPath, err := fs.getBackingPath(oldPath) if err != nil { return fuse.ToStatus(err) } cNewPath, err := fs.getBackingPath(newPath) if err != nil { return fuse.ToStatus(err) } return fuse.ToStatus(os.Link(cOldPath, cNewPath)) } func (fs *FS) Access(path string, mode uint32, context *fuse.Context) (code fuse.Status) { if fs.CryptFS.IsFiltered(path) { return fuse.EPERM } cPath, err := fs.getBackingPath(path) if err != nil { return fuse.ToStatus(err) } return fuse.ToStatus(syscall.Access(cPath, mode)) } func (fs *FS) GetXAttr(name string, attr string, context *fuse.Context) ([]byte, fuse.Status) { return nil, fuse.ENOSYS } func (fs *FS) SetXAttr(name string, attr string, data []byte, flags int, context *fuse.Context) fuse.Status { return fuse.ENOSYS } func (fs *FS) ListXAttr(name string, context *fuse.Context) ([]string, fuse.Status) { return nil, fuse.ENOSYS } func (fs *FS) RemoveXAttr(name string, attr string, context *fuse.Context) fuse.Status { return fuse.ENOSYS }