package fusefrontend // FUSE operations on paths import ( "encoding/base64" "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/internal/toggledlog" "github.com/rfjakob/gocryptfs/internal/cryptocore" "github.com/rfjakob/gocryptfs/internal/nametransform" "github.com/rfjakob/gocryptfs/internal/contentenc" "github.com/rfjakob/gocryptfs/internal/configfile" ) const plainBS = 4096 type FS struct { 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 // Filename encryption helper nameTransform *nametransform.NameTransform // Content encryption helper contentEnc *contentenc.ContentEnc } // Encrypted FUSE overlay filesystem func NewFS(args Args) *FS { cryptoCore := cryptocore.New(args.Masterkey, args.OpenSSL, args.GCMIV128) contentEnc := contentenc.New(cryptoCore, plainBS) nameTransform := nametransform.New(cryptoCore, args.EMENames) return &FS{ FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir), args: args, nameTransform: nameTransform, contentEnc: contentEnc, } } // 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) toggledlog.Debug.Printf("getBackingPath: %s + %s -> %s", fs.args.Cipherdir, relPath, cAbsPath) return cAbsPath, nil } func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) { toggledlog.Debug.Printf("FS.GetAttr('%s')", name) if fs.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 { toggledlog.Debug.Printf("FS.GetAttr failed: %s", status.String()) return a, status } if a.IsRegular() { a.Size = fs.contentEnc.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) { toggledlog.Debug.Printf("OpenDir(%s)", 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 nil if DirIV if off) var cachedIV []byte 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.nameTransform.ReadDirIV(cDirAbsPath) if err != nil { return nil, fuse.ToStatus(err) } } // Filter and decrypt filenames var plain []fuse.DirEntry for i := range cipherEntries { cName := cipherEntries[i].Name if dirName == "" && cName == configfile.ConfDefaultName { // silently ignore "gocryptfs.conf" in the top level dir continue } if fs.args.DirIV && cName == nametransform.DirIVFilename { // silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled continue } var name string = cName if !fs.args.PlaintextNames { name, err = fs.nameTransform.DecryptName(cName, cachedIV) if err != nil { toggledlog.Warn.Printf("Invalid name \"%s\" in dir \"%s\": %s", cName, cDirName, 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.isFiltered(path) { return nil, fuse.EPERM } iflags, writeOnly := fs.mangleOpenFlags(flags) cPath, err := fs.getBackingPath(path) if err != nil { toggledlog.Debug.Printf("Open: getBackingPath: %v", err) return nil, fuse.ToStatus(err) } toggledlog.Debug.Printf("Open: %s", cPath) f, err := os.OpenFile(cPath, iflags, 0666) if err != nil { return nil, fuse.ToStatus(err) } return NewFile(f, writeOnly, fs.contentEnc), fuse.OK } func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) { if fs.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.contentEnc), fuse.OK } func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) { if fs.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.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.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) } var truncateWarned bool func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code fuse.Status) { // Only warn once if !truncateWarned { toggledlog.Warn.Printf("truncate(2) is not supported, returning ENOSYS - use ftruncate(2)") truncateWarned = true } return fuse.ENOSYS } func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) { if fs.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 { toggledlog.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 { toggledlog.Warn.Printf("Readlink: %v", err) return "", fuse.EIO } target, err := fs.contentEnc.DecryptBlock([]byte(cBinTarget), 0, nil) if err != nil { toggledlog.Warn.Printf("Readlink: %v", err) return "", fuse.EIO } return string(target), fuse.OK } func (fs *FS) Unlink(path string, context *fuse.Context) (code fuse.Status) { if fs.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) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) { toggledlog.Debug.Printf("Symlink(\"%s\", \"%s\")", target, linkName) if fs.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 { toggledlog.Warn.Printf("Symlink: BUG: we should not get an error here: %v", 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.contentEnc.EncryptBlock([]byte(target), 0, nil) cTarget := base64.URLEncoding.EncodeToString(cBinTarget) err = os.Symlink(cTarget, cPath) toggledlog.Debug.Printf("Symlink: os.Symlink(%s, %s) = %v", cTarget, cPath, err) return fuse.ToStatus(err) } func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) { if fs.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.nameTransform.DirIVCache.Clear() err = os.Rename(cOldPath, cNewPath) if lerr, ok := err.(*os.LinkError); ok && lerr.Err == syscall.ENOTEMPTY { // If an empty directory is overwritten we will always get // ENOTEMPTY as the "empty" directory will still contain gocryptfs.diriv. // Handle that case by removing the target directory and trying again. toggledlog.Debug.Printf("Rename: Handling ENOTEMPTY") if fs.Rmdir(newPath, context) == fuse.OK { err = os.Rename(cOldPath, cNewPath) } } return fuse.ToStatus(err) } func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) { if fs.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.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 }