Implement PlainTextNames mode

Also, forbid access to "gocryptfs.conf" in the root dir.

5 files changed, 84 insertions, 20 deletions

diff --git a/cryptfs/config_file.go b/cryptfs/config_file.go
index de3054a..a790c51 100644
--- a/cryptfs/config_file.go
+++ b/cryptfs/config_file.go
@@ -76,7 +76,7 @@ func LoadConfFile(filename string, password string) ([]byte, *ConfFile, error) {
 	// Unlock master key using password-based key
 	// We use stock go GCM instead of OpenSSL here as speed is not important
 	// and we get better error messages
-	cfs := NewCryptFS(scryptHash, false)
+	cfs := NewCryptFS(scryptHash, false, false)
 	key, err := cfs.DecryptBlock(cf.EncryptedKey, 0, nil)
 	if err != nil {
 		Warn.Printf("failed to unlock master key: %s\n", err.Error())
@@ -95,7 +95,7 @@ func (cf *ConfFile) EncryptKey(key []byte, password string) {
 	scryptHash := cf.ScryptObject.DeriveKey(password)
 
 	// Lock master key using password-based key
-	cfs := NewCryptFS(scryptHash, false)
+	cfs := NewCryptFS(scryptHash, false, false)
 	cf.EncryptedKey = cfs.EncryptBlock(key, 0, nil)
 }
 
diff --git a/cryptfs/cryptfs.go b/cryptfs/cryptfs.go
index 9fe492d..ed19b26 100644
--- a/cryptfs/cryptfs.go
+++ b/cryptfs/cryptfs.go
@@ -23,9 +23,10 @@ type CryptFS struct {
 	cipherBS    uint64
 	// Stores an all-zero block of size cipherBS
 	allZeroBlock []byte
+	plaintextNames bool
 }
 
-func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
+func NewCryptFS(key []byte, useOpenssl bool, plaintextNames bool) *CryptFS {
 
 	if len(key) != KEY_LEN {
 		panic(fmt.Sprintf("Unsupported key length %d", len(key)))
@@ -54,6 +55,7 @@ func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
 		plainBS:      DEFAULT_PLAINBS,
 		cipherBS:     uint64(cipherBS),
 		allZeroBlock: make([]byte, cipherBS),
+		plaintextNames: plaintextNames,
 	}
 }
 
diff --git a/cryptfs/cryptfs_names.go b/cryptfs/cryptfs_names.go
index 5476b17..a7a9a8c 100644
--- a/cryptfs/cryptfs_names.go
+++ b/cryptfs/cryptfs_names.go
@@ -102,14 +102,20 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) {
 	return strings.Join(translatedParts, "/"), err
 }
 
-// EncryptPath - encrypt filename or path. Just hands it to TranslatePath().
+// EncryptPath - encrypt filename or path. Just hands it to translatePath().
 func (be *CryptFS) EncryptPath(path string) string {
+	if be.plaintextNames {
+		return path
+	}
 	newPath, _ := be.translatePath(path, ENCRYPT)
 	return newPath
 }
 
-// DecryptPath - decrypt filename or path. Just hands it to TranslatePath().
+// DecryptPath - decrypt filename or path. Just hands it to translatePath().
 func (be *CryptFS) DecryptPath(path string) (string, error) {
+	if be.plaintextNames {
+		return path, nil
+	}
 	return be.translatePath(path, DECRYPT)
 }
 
diff --git a/main.go b/main.go
index cf82ad2..3d9bed7 100644
--- a/main.go
+++ b/main.go
@@ -41,7 +41,7 @@ func initDir(dirArg string, plaintextNames bool) {
 
 	err := checkDirEmpty(dir)
 	if err != nil {
-		fmt.Printf("Error: \"%s\": %v\n", dirArg, err)
+		fmt.Printf("Invalid CIPHERDIR: %v\n", err)
 		os.Exit(ERREXIT_INIT)
 	}
 
@@ -114,8 +114,8 @@ func main() {
 		fmt.Printf("Openssl disabled\n")
 	}
 	if args.init {
-		if flag.NArg() != 1 {
-			fmt.Printf("Usage: %s --init CIPHERDIR\n", PROGRAM_NAME)
+		if flag.NArg() != 1 && args.plaintextnames == false {
+			fmt.Printf("Usage: %s --init [--plaintextnames] CIPHERDIR\n", PROGRAM_NAME)
 			os.Exit(ERREXIT_USAGE)
 		}
 		initDir(flag.Arg(0), args.plaintextnames) // does not return
@@ -154,6 +154,7 @@ func main() {
 		key = parseMasterKey(args.masterkey)
 		fmt.Printf("Using explicit master key.\n")
 	} else {
+		// Load config file
 		cfname := filepath.Join(args.cipherdir, cryptfs.ConfDefaultName)
 		_, err = os.Stat(cfname)
 		if err != nil {
@@ -194,7 +195,11 @@ func main() {
 		os.Exit(0)
 	}
 
-	srv := pathfsFrontend(key, args.cipherdir, args.mountpoint, args.fusedebug, args.openssl)
+	var plaintextNames bool
+	if cf != nil {
+		plaintextNames = cf.PlaintextNames
+	}
+	srv := pathfsFrontend(key, args.cipherdir, args.mountpoint, args.fusedebug, args.openssl, plaintextNames)
 
 	if args.zerokey == false && len(args.masterkey) == 0 {
 		printMasterKey(key)
@@ -215,9 +220,10 @@ func main() {
 	// main returns with code 0
 }
 
-func pathfsFrontend(key []byte, cipherdir string, mountpoint string, debug bool, openssl bool) *fuse.Server {
+func pathfsFrontend(key []byte, cipherdir string, mountpoint string,
+	debug bool, openssl bool, plaintextNames bool) *fuse.Server {
 
-	finalFs := pathfs_frontend.NewFS(key, cipherdir, openssl)
+	finalFs := pathfs_frontend.NewFS(key, cipherdir, openssl, plaintextNames)
 	pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
 	pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
 	fuseOpts := &nodefs.Options{
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index 3ec503f..1ef19d2 100644
--- a/pathfs_frontend/fs.go
+++ b/pathfs_frontend/fs.go
@@ -19,9 +19,9 @@ type FS struct {
 }
 
 // Encrypted FUSE overlay filesystem
-func NewFS(key []byte, backing string, useOpenssl bool) *FS {
+func NewFS(key []byte, backing string, useOpenssl bool, plaintextNames bool) *FS {
 	return &FS{
-		CryptFS:    cryptfs.NewCryptFS(key, useOpenssl),
+		CryptFS:    cryptfs.NewCryptFS(key, useOpenssl, plaintextNames),
 		FileSystem: pathfs.NewLoopbackFileSystem(backing),
 		backing:    backing,
 	}
@@ -34,6 +34,9 @@ func (fs *FS) GetPath(relPath string) string {
 
 func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
 	cryptfs.Debug.Printf("FS.GetAttr('%s')\n", name)
+	if name == cryptfs.ConfDefaultName {
+		return nil, fuse.EPERM // See comment in Open()
+	}
 	cName := fs.EncryptPath(name)
 	a, status := fs.FileSystem.GetAttr(cName, context)
 	if a == nil {
@@ -56,12 +59,12 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 	if cipherEntries != nil {
 		for i := range cipherEntries {
 			cName := cipherEntries[i].Name
+			if dirName == "" && cName == cryptfs.ConfDefaultName {
+				// ignore "gocryptfs.conf" in the top level dir
+				continue
+			}
 			name, err := fs.DecryptPath(cName)
 			if err != nil {
-				if dirName == "" && cName == cryptfs.ConfDefaultName {
-					// Silently ignore "gocryptfs.conf" in the top level dir
-					continue
-				}
 				fmt.Printf("Invalid name \"%s\" in dir \"%s\": %s\n", cName, name, err)
 				continue
 			}
@@ -85,11 +88,18 @@ func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
 	return newFlags, writeOnly
 }
 
-func (fs *FS) Open(name string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
-	cryptfs.Debug.Printf("Open(%s)\n", name)
+func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
+	cryptfs.Debug.Printf("Open(%s)\n", path)
+
+	if path == cryptfs.ConfDefaultName {
+		// "gocryptfs.conf" in the top level dir is forbidden
+		// to protect the config file of this filesystem if
+		// "--plaintextnames" is enabled
+		return nil, fuse.EPERM
+	}
 
 	iflags, writeOnly := fs.mangleOpenFlags(flags)
-	f, err := os.OpenFile(fs.GetPath(name), iflags, 0666)
+	f, err := os.OpenFile(fs.GetPath(path), iflags, 0666)
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
@@ -98,6 +108,10 @@ func (fs *FS) Open(name string, flags uint32, context *fuse.Context) (fuseFile n
 }
 
 func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) {
+	if path == cryptfs.ConfDefaultName {
+		return nil, fuse.EPERM // See comment in Open()
+	}
+
 	iflags, writeOnly := fs.mangleOpenFlags(flags)
 	f, err := os.OpenFile(fs.GetPath(path), iflags|os.O_CREATE, os.FileMode(mode))
 	if err != nil {
@@ -107,14 +121,26 @@ func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Conte
 }
 
 func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
+	if path == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Chmod(fs.EncryptPath(path), mode, context)
 }
 
 func (fs *FS) Chown(path string, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status) {
+	if path == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Chown(fs.EncryptPath(path), uid, gid, context)
 }
 
 func (fs *FS) Mknod(name string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
+	if name == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Mknod(fs.EncryptPath(name), mode, dev, context)
 }
 
@@ -124,6 +150,10 @@ func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code
 }
 
 func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) {
+	if path == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Utimens(fs.EncryptPath(path), Atime, Mtime, context)
 }
 
@@ -141,10 +171,18 @@ func (fs *FS) Readlink(name string, context *fuse.Context) (out string, status f
 }
 
 func (fs *FS) Mkdir(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
+	if path == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Mkdir(fs.EncryptPath(path), mode, context)
 }
 
 func (fs *FS) Unlink(name string, context *fuse.Context) (code fuse.Status) {
+	if name == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	cName := fs.EncryptPath(name)
 	code = fs.FileSystem.Unlink(cName, context)
 	if code != fuse.OK {
@@ -158,16 +196,28 @@ func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
 }
 
 func (fs *FS) Symlink(pointedTo string, linkName string, context *fuse.Context) (code fuse.Status) {
+	if linkName == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	// TODO symlink encryption
 	cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", pointedTo, linkName)
 	return fs.FileSystem.Symlink(fs.EncryptPath(pointedTo), fs.EncryptPath(linkName), context)
 }
 
 func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (codee fuse.Status) {
+	if newPath == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Rename(fs.EncryptPath(oldPath), fs.EncryptPath(newPath), context)
 }
 
 func (fs *FS) Link(orig string, newName string, context *fuse.Context) (code fuse.Status) {
+	if newName == cryptfs.ConfDefaultName {
+		return fuse.EPERM // See comment in Open()
+	}
+
 	return fs.FileSystem.Link(fs.EncryptPath(orig), fs.EncryptPath(newName), context)
 }