-deterministic-names: implement for reverse mode, too

5 files changed, 32 insertions, 19 deletions

diff --git a/internal/fusefrontend_reverse/ctlsock_interface.go b/internal/fusefrontend_reverse/ctlsock_interface.go
index 2157044..1cfdf3e 100644
--- a/internal/fusefrontend_reverse/ctlsock_interface.go
+++ b/internal/fusefrontend_reverse/ctlsock_interface.go
@@ -7,7 +7,6 @@ import (
 	"golang.org/x/sys/unix"
 
 	"github.com/rfjakob/gocryptfs/internal/ctlsocksrv"
-	"github.com/rfjakob/gocryptfs/internal/pathiv"
 )
 
 // Verify that the interface is implemented.
@@ -22,7 +21,7 @@ func (rn *RootNode) EncryptPath(plainPath string) (string, error) {
 	cipherPath := ""
 	parts := strings.Split(plainPath, "/")
 	for _, part := range parts {
-		dirIV := pathiv.Derive(cipherPath, pathiv.PurposeDirIV)
+		dirIV := rn.deriveDirIV(cipherPath)
 		encryptedPart, err := rn.nameTransform.EncryptName(part, dirIV)
 		if err != nil {
 			return "", err
diff --git a/internal/fusefrontend_reverse/node_dir_ops.go b/internal/fusefrontend_reverse/node_dir_ops.go
index 21b9775..2592ebc 100644
--- a/internal/fusefrontend_reverse/node_dir_ops.go
+++ b/internal/fusefrontend_reverse/node_dir_ops.go
@@ -13,7 +13,6 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/configfile"
 	"github.com/rfjakob/gocryptfs/internal/cryptocore"
 	"github.com/rfjakob/gocryptfs/internal/nametransform"
-	"github.com/rfjakob/gocryptfs/internal/pathiv"
 	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
@@ -23,20 +22,16 @@ import (
 // This function is symlink-safe through use of openBackingDir() and
 // ReadDirIVAt().
 func (n *Node) Readdir(ctx context.Context) (stream fs.DirStream, errno syscall.Errno) {
-	// Virtual files: at least one gocryptfs.diriv file
-	virtualFiles := []fuse.DirEntry{
-		{Mode: virtualFileMode, Name: nametransform.DirIVFilename},
-	}
 	rn := n.rootNode()
+	// Should we present a virtual gocryptfs.diriv?
+	var virtualFiles []fuse.DirEntry
+	if !rn.args.PlaintextNames && !rn.args.DeterministicNames {
+		virtualFiles = append(virtualFiles, fuse.DirEntry{Mode: virtualFileMode, Name: nametransform.DirIVFilename})
+	}
 
 	// This directory is a mountpoint. Present it as empty.
 	if rn.args.OneFileSystem && n.isOtherFilesystem {
-		if rn.args.PlaintextNames {
-			return fs.NewListDirStream(nil), 0
-		} else {
-			// An "empty" directory still has a gocryptfs.diriv file!
-			return fs.NewListDirStream(virtualFiles), 0
-		}
+		return fs.NewListDirStream(virtualFiles), 0
 	}
 
 	d, errno := n.prepareAtSyscall("")
@@ -64,7 +59,7 @@ func (n *Node) Readdir(ctx context.Context) (stream fs.DirStream, errno syscall.
 		return n.readdirPlaintextnames(entries)
 	}
 
-	dirIV := pathiv.Derive(d.cPath, pathiv.PurposeDirIV)
+	dirIV := rn.deriveDirIV(d.cPath)
 	// Encrypt names
 	for i := range entries {
 		var cName string
diff --git a/internal/fusefrontend_reverse/node_helpers.go b/internal/fusefrontend_reverse/node_helpers.go
index 7b286a0..b7dc086 100644
--- a/internal/fusefrontend_reverse/node_helpers.go
+++ b/internal/fusefrontend_reverse/node_helpers.go
@@ -2,6 +2,7 @@ package fusefrontend_reverse
 
 import (
 	"context"
+	"log"
 	"path/filepath"
 	"syscall"
 
@@ -129,8 +130,8 @@ func (n *Node) lookupLongnameName(ctx context.Context, nameFile string, out *fus
 		return
 	}
 	defer syscall.Close(fd)
-	diriv := pathiv.Derive(d.cPath, pathiv.PurposeDirIV)
 	rn := n.rootNode()
+	diriv := rn.deriveDirIV(d.cPath)
 	pName, cFullname, errno := rn.findLongnameParent(fd, diriv, nameFile)
 	if errno != 0 {
 		return
@@ -160,6 +161,10 @@ func (n *Node) lookupLongnameName(ctx context.Context, nameFile string, out *fus
 
 // lookupDiriv returns a new Inode for a gocryptfs.diriv file inside `n`.
 func (n *Node) lookupDiriv(ctx context.Context, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
+	if rn := n.rootNode(); rn.args.DeterministicNames {
+		log.Panic("BUG: lookupDiriv called but DeterministicNames is set")
+	}
+
 	d, errno := n.prepareAtSyscall("")
 	if errno != 0 {
 		return
diff --git a/internal/fusefrontend_reverse/rpath.go b/internal/fusefrontend_reverse/rpath.go
index 199473b..7ebedd7 100644
--- a/internal/fusefrontend_reverse/rpath.go
+++ b/internal/fusefrontend_reverse/rpath.go
@@ -2,6 +2,7 @@ package fusefrontend_reverse
 
 import (
 	"encoding/base64"
+	"log"
 	"path/filepath"
 	"strings"
 	"syscall"
@@ -72,7 +73,7 @@ func (rn *RootNode) decryptPath(cPath string) (string, error) {
 		// Start at the top and recurse
 		currentCipherDir := filepath.Join(parts[:i]...)
 		currentPlainDir := filepath.Join(transformedParts[:i]...)
-		dirIV := pathiv.Derive(currentCipherDir, pathiv.PurposeDirIV)
+		dirIV := rn.deriveDirIV(currentCipherDir)
 		transformedPart, err := rn.rDecryptName(parts[i], dirIV, currentPlainDir)
 		if err != nil {
 			return "", err
@@ -83,6 +84,17 @@ func (rn *RootNode) decryptPath(cPath string) (string, error) {
 	return pRelPath, nil
 }
 
+// deriveDirIV wraps pathiv.Derive but takes DeterministicNames into account.
+func (rn *RootNode) deriveDirIV(cPath string) []byte {
+	if rn.args.PlaintextNames {
+		log.Panic("BUG: deriveDirIV called but PlaintextNames is set")
+	}
+	if rn.args.DeterministicNames {
+		return make([]byte, nametransform.DirIVLen)
+	}
+	return pathiv.Derive(cPath, pathiv.PurposeDirIV)
+}
+
 // openBackingDir receives an already decrypted relative path
 // "pRelPath", opens the directory that contains the target file/dir
 // and returns the fd to the directory and the decrypted name of the
diff --git a/internal/fusefrontend_reverse/virtualnode.go b/internal/fusefrontend_reverse/virtualnode.go
index 2ee9548..328f021 100644
--- a/internal/fusefrontend_reverse/virtualnode.go
+++ b/internal/fusefrontend_reverse/virtualnode.go
@@ -43,9 +43,11 @@ func (n *Node) lookupFileType(cName string) fileType {
 	rn := n.rootNode()
 	// In -plaintextname mode, neither diriv nor longname files exist.
 	if !rn.args.PlaintextNames {
-		// Is it a gocryptfs.diriv file?
-		if cName == nametransform.DirIVFilename {
-			return typeDiriv
+		if !rn.args.DeterministicNames {
+			// Is it a gocryptfs.diriv file?
+			if cName == nametransform.DirIVFilename {
+				return typeDiriv
+			}
 		}
 		// Is it a gocryptfs.longname.*.name file?
 		if t := nametransform.NameType(cName); t == nametransform.LongNameFilename {