1 files changed, 34 insertions, 18 deletions

diff --git a/internal/fusefrontend_reverse/rfs.go b/internal/fusefrontend_reverse/rfs.go
index 914dccb..68a5ac8 100644
--- a/internal/fusefrontend_reverse/rfs.go
+++ b/internal/fusefrontend_reverse/rfs.go
@@ -2,6 +2,7 @@ package fusefrontend_reverse
 
 import (
 	"os"
+	"syscall"
 
 	"github.com/hanwen/go-fuse/fuse"
 	"github.com/hanwen/go-fuse/fuse/nodefs"
@@ -13,9 +14,11 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/nametransform"
 )
 
-type FS struct {
-	// loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
+type reverseFS struct {
+	// Embed pathfs.defaultFileSystem for a ENOSYS implementation of all methods
 	pathfs.FileSystem
+	// pathfs.loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
+	loopbackfs pathfs.FileSystem
 	// Stores configuration arguments
 	args fusefrontend.Args
 	// Filename encryption helper
@@ -25,43 +28,56 @@ type FS struct {
 }
 
 // Encrypted FUSE overlay filesystem
-func NewFS(args fusefrontend.Args) *FS {
+func NewFS(args fusefrontend.Args) *reverseFS {
 	cryptoCore := cryptocore.New(args.Masterkey, args.OpenSSL, true)
 	contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
 	nameTransform := nametransform.New(cryptoCore, args.LongNames)
 
-	return &FS{
-		FileSystem:    pathfs.NewLoopbackFileSystem(args.Cipherdir),
+	return &reverseFS{
+		// pathfs.defaultFileSystem returns ENOSYS for all operations
+		FileSystem:    pathfs.NewDefaultFileSystem(),
+		loopbackfs:    pathfs.NewLoopbackFileSystem(args.Cipherdir),
 		args:          args,
 		nameTransform: nameTransform,
 		contentEnc:    contentEnc,
 	}
 }
 
-func (fs *FS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
-	if fs.isFiltered(relPath) {
+func (rfs *reverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
+	if rfs.isFiltered(relPath) {
 		return nil, fuse.EPERM
 	}
-	relPath, err := fs.decryptPath(relPath)
+	relPath, err := rfs.decryptPath(relPath)
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
-	a, status := fs.FileSystem.GetAttr(relPath, context)
+	a, status := rfs.loopbackfs.GetAttr(relPath, context)
 	if a == nil {
 		return a, status
 	}
 	// Calculate encrypted file size
 	if a.IsRegular() {
-		a.Size = fs.contentEnc.PlainSizeToCipherSize(a.Size)
+		a.Size = rfs.contentEnc.PlainSizeToCipherSize(a.Size)
 	}
 	return a, fuse.OK
 }
 
-func (fs *FS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
-	if fs.isFiltered(relPath) {
+func (rfs *reverseFS) Access(relPath string, mode uint32, context *fuse.Context) fuse.Status {
+	if rfs.isFiltered(relPath) {
+		return fuse.EPERM
+	}
+	cPath, err := rfs.abs(rfs.encryptPath(relPath))
+	if err != nil {
+		return fuse.ToStatus(err)
+	}
+	return fuse.ToStatus(syscall.Access(cPath, mode))
+}
+
+func (rfs *reverseFS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
+	if rfs.isFiltered(relPath) {
 		return nil, fuse.EPERM
 	}
-	absPath, err := fs.abs(fs.decryptPath(relPath))
+	absPath, err := rfs.abs(rfs.decryptPath(relPath))
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
@@ -69,22 +85,22 @@ func (fs *FS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFil
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
-	return NewFile(f, fs.contentEnc)
+	return NewFile(f, rfs.contentEnc)
 }
 
-func (fs *FS) OpenDir(relPath string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
-	relPath, err := fs.decryptPath(relPath)
+func (rfs *reverseFS) OpenDir(relPath string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
+	relPath, err := rfs.decryptPath(relPath)
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
 	// Read plaintext dir
-	entries, status := fs.FileSystem.OpenDir(relPath, context)
+	entries, status := rfs.loopbackfs.OpenDir(relPath, context)
 	if entries == nil {
 		return nil, status
 	}
 	// Encrypt names
 	for i := range entries {
-		entries[i].Name, err = fs.encryptPath(entries[i].Name)
+		entries[i].Name, err = rfs.encryptPath(entries[i].Name)
 		if err != nil {
 			return nil, fuse.ToStatus(err)
 		}