diriv: also support old CBC symlink

4 files changed, 70 insertions, 26 deletions

diff --git a/main.go b/main.go
index b3944cc..ab2c1f1 100644
--- a/main.go
+++ b/main.go
@@ -245,6 +245,7 @@ func main() {
 	}
 	// Get master key
 	var masterkey []byte
+	var confFile *cryptfs.ConfFile
 	if args.masterkey != "" {
 		// "-masterkey"
 		cryptfs.Info.Printf("Using explicit master key.\n")
@@ -257,15 +258,12 @@ func main() {
 		masterkey = make([]byte, cryptfs.KEY_LEN)
 	} else {
 		// Load master key from config file
-		var confFile *cryptfs.ConfFile
 		masterkey, confFile = loadConfig(&args)
 		printMasterKey(masterkey)
-		// Settings from the config file override command line args
-		args.plaintextnames = confFile.IsFeatureFlagSet(cryptfs.FlagPlaintextNames)
-		args.diriv = confFile.IsFeatureFlagSet(cryptfs.FlagDirIV)
 	}
 	// Initialize FUSE server
-	srv := pathfsFrontend(masterkey, args)
+	cryptfs.Debug.Printf("args: %v\n", args)
+	srv := pathfsFrontend(masterkey, args, confFile)
 	cryptfs.Info.Println("Filesystem ready.")
 	// We are ready - send USR1 signal to our parent
 	if args.notifypid > 0 {
@@ -279,11 +277,27 @@ func main() {
 	// main exits with code 0
 }
 
-// pathfsFrontend - initialize FUSE server based on go-fuse's PathFS.
+// pathfsFrontend - initialize gocryptfs/pathfs_frontend
 // Calls os.Exit on errors
-func pathfsFrontend(key []byte, args argContainer) *fuse.Server {
+func pathfsFrontend(key []byte, args argContainer, confFile *cryptfs.ConfFile) *fuse.Server {
+
+	// Reconciliate CLI and config file arguments into a Args struct that is passed to the
+	// filesystem implementation
+	frontendArgs := pathfs_frontend.Args{
+		Cipherdir: args.cipherdir,
+		Masterkey: key,
+		OpenSSL: args.openssl,
+		PlaintextNames: args.plaintextnames,
+		DirIV: args.diriv,
+	}
+	// confFile is nil when "-zerokey" or "-masterkey" was used
+	if confFile != nil {
+		// Settings from the config file override command line args
+		frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(cryptfs.FlagPlaintextNames)
+		frontendArgs.DirIV = confFile.IsFeatureFlagSet(cryptfs.FlagDirIV)
+	}
 
-	finalFs := pathfs_frontend.NewFS(key, args.cipherdir, args.openssl, args.plaintextnames, args.diriv)
+	finalFs := pathfs_frontend.NewFS(frontendArgs)
 	pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
 	pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
 	fuseOpts := &nodefs.Options{
diff --git a/pathfs_frontend/args.go b/pathfs_frontend/args.go
new file mode 100644
index 0000000..7971b79
--- /dev/null
+++ b/pathfs_frontend/args.go
@@ -0,0 +1,10 @@
+package pathfs_frontend
+
+// Container for arguments that are passed from main() to pathfs_frontend
+type Args struct {
+	Masterkey []byte
+	Cipherdir string
+	OpenSSL bool
+	PlaintextNames bool
+	DirIV bool
+}
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index dbb6b10..e68e6bc 100644
--- a/pathfs_frontend/fs.go
+++ b/pathfs_frontend/fs.go
@@ -18,9 +18,7 @@ import (
 type FS struct {
 	*cryptfs.CryptFS
 	pathfs.FileSystem        // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
-	backingDir        string // Backing directory, cipherdir
-	// Are per-directory filename IVs enabled?
-	dirIV bool
+	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
@@ -28,23 +26,24 @@ type FS struct {
 }
 
 // Encrypted FUSE overlay filesystem
-func NewFS(key []byte, backing string, useOpenssl bool, plaintextNames bool, dirIV bool) *FS {
+func NewFS(args Args) *FS {
 	return &FS{
-		CryptFS:    cryptfs.NewCryptFS(key, useOpenssl, plaintextNames),
-		FileSystem: pathfs.NewLoopbackFileSystem(backing),
-		dirIV:      dirIV,
-		backingDir: backing,
+		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) {
-	encrypted, err := fs.encryptPath(relPath)
+	cPath, err := fs.encryptPath(relPath)
 	if err != nil {
 		return "", err
 	}
-	return filepath.Join(fs.backingDir, encrypted), nil
+	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) {
@@ -85,12 +84,12 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 				// silently ignore "gocryptfs.conf" in the top level dir
 				continue
 			}
-			if fs.dirIV && cName == cryptfs.DIRIV_FILENAME {
+			if fs.args.DirIV && cName == cryptfs.DIRIV_FILENAME {
 				// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
 				continue
 			}
 			var name string
-			if !fs.dirIV {
+			if !fs.args.DirIV {
 				name, err = fs.decryptPath(cName)
 			} else {
 				// When dirIV is enabled we need the full path to be able to decrypt it
@@ -123,15 +122,16 @@ func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
 }
 
 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 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)
@@ -214,6 +214,16 @@ func (fs *FS) Readlink(path string, context *fuse.Context) (out string, status f
 	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)
@@ -335,7 +345,17 @@ func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (co
 	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)
 
diff --git a/pathfs_frontend/names.go b/pathfs_frontend/names.go
index 122b3dd..bb73ff4 100644
--- a/pathfs_frontend/names.go
+++ b/pathfs_frontend/names.go
@@ -7,19 +7,19 @@ import (
 )
 
 func (fs *FS) encryptPath(plainPath string) (string, error) {
-	if !fs.dirIV {
+	if !fs.args.DirIV {
 		return fs.CryptFS.TranslatePathZeroIV(plainPath, cryptfs.OpEncrypt)
 	}
 	fs.dirIVLock.RLock()
 	defer fs.dirIVLock.RUnlock()
-	return fs.CryptFS.EncryptPathDirIV(plainPath, fs.backingDir)
+	return fs.CryptFS.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
 }
 
 func (fs *FS) decryptPath(cipherPath string) (string, error) {
-	if !fs.dirIV {
+	if !fs.args.DirIV {
 		return fs.CryptFS.TranslatePathZeroIV(cipherPath, cryptfs.OpDecrypt)
 	}
 	fs.dirIVLock.RLock()
 	defer fs.dirIVLock.RUnlock()
-	return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.backingDir)
+	return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.args.Cipherdir)
 }