From fbccb160438aba6f1e16b26a982122c726afee1a Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Fri, 20 Aug 2021 17:06:18 +0200
Subject: -deterministic-names: implement for reverse mode, too

---
 internal/fusefrontend_reverse/ctlsock_interface.go |  3 +--
 internal/fusefrontend_reverse/node_dir_ops.go      | 19 ++++++--------
 internal/fusefrontend_reverse/node_helpers.go      |  7 +++++-
 internal/fusefrontend_reverse/rpath.go             | 14 ++++++++++-
 internal/fusefrontend_reverse/virtualnode.go       |  8 +++---
 tests/cli/cli_test.go                              |  6 -----
 tests/reverse/correctness_test.go                  |  8 +++---
 tests/reverse/inomap_test.go                       |  6 +++--
 tests/reverse/main_test.go                         | 23 +++++++++++++++--
 tests/reverse/one_file_system_test.go              | 29 ++++++++++++----------
 10 files changed, 77 insertions(+), 46 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 {
diff --git a/tests/cli/cli_test.go b/tests/cli/cli_test.go
index f4162f8..85a8006 100644
--- a/tests/cli/cli_test.go
+++ b/tests/cli/cli_test.go
@@ -995,9 +995,3 @@ func TestMountCreat(t *testing.T) {
 		test_helpers.UnmountPanic(mnt)
 	}
 }
-
-// Test -init -deterministic-names
-func TestInitDeterministicNames(t *testing.T) {
-	dir := test_helpers.InitFS(t, "-deterministic-names")
-
-}
diff --git a/tests/reverse/correctness_test.go b/tests/reverse/correctness_test.go
index 9d7a1c8..87d2f12 100644
--- a/tests/reverse/correctness_test.go
+++ b/tests/reverse/correctness_test.go
@@ -119,10 +119,10 @@ func TestConfigMapping(t *testing.T) {
 	}
 }
 
-// Check that the access() syscall works on virtual files
-func TestAccessVirtual(t *testing.T) {
-	if plaintextnames {
-		t.Skip("test makes no sense for plaintextnames")
+// Check that the access() syscall works on virtual gocryptfs.diriv files
+func TestAccessVirtualDirIV(t *testing.T) {
+	if plaintextnames || deterministic_names {
+		t.Skip("test makes no sense for plaintextnames or deterministic_names")
 	}
 	var R_OK uint32 = 4
 	var W_OK uint32 = 2
diff --git a/tests/reverse/inomap_test.go b/tests/reverse/inomap_test.go
index e6fc525..d5544c8 100644
--- a/tests/reverse/inomap_test.go
+++ b/tests/reverse/inomap_test.go
@@ -130,8 +130,10 @@ func TestVirtualFileIno(t *testing.T) {
 	}
 	// Lower 48 bits should come from the backing file
 	const mask = 0xffffffffffff
-	if origInos.parent&mask != cipherInos.diriv&mask {
-		t.Errorf("diriv ino mismatch: %#x vs %#x", origInos.parent, cipherInos.diriv)
+	if !deterministic_names { // no diriv files with -deterministic-names
+		if origInos.parent&mask != cipherInos.diriv&mask {
+			t.Errorf("diriv ino mismatch: %#x vs %#x", origInos.parent, cipherInos.diriv)
+		}
 	}
 	if origInos.child != cipherInos.child {
 		t.Errorf("child ino mismatch: %d vs %d", origInos.child, cipherInos.child)
diff --git a/tests/reverse/main_test.go b/tests/reverse/main_test.go
index 3425289..3b9e7d0 100644
--- a/tests/reverse/main_test.go
+++ b/tests/reverse/main_test.go
@@ -2,6 +2,7 @@ package reverse_test
 
 import (
 	"bytes"
+	"fmt"
 	"os"
 	"testing"
 
@@ -9,8 +10,13 @@ import (
 )
 
 var x240 = string(bytes.Repeat([]byte("x"), 240))
+
+// plaintextnames is true when the currently running test has -plaintextnames active
 var plaintextnames bool
 
+// deterministic_names is true when the currently running test has -deterministic-names active
+var deterministic_names bool
+
 // dirA is a normal directory
 var dirA string
 
@@ -24,10 +30,22 @@ var dirC string
 // to "dirC".
 func TestMain(m *testing.M) {
 	var r int
-	for _, plaintextnames = range []bool{false, true} {
+
+	testcases := []struct {
+		plaintextnames      bool
+		deterministic_names bool
+	}{
+		{false, false},
+		{true, false},
+		{false, true},
+	}
+	for i, tc := range testcases {
 		argsA := []string{"-reverse"}
-		if plaintextnames {
+		plaintextnames, deterministic_names = tc.plaintextnames, tc.deterministic_names
+		if tc.plaintextnames {
 			argsA = append(argsA, "-plaintextnames")
+		} else if tc.deterministic_names {
+			argsA = append(argsA, "-deterministic-names")
 		}
 		dirA = test_helpers.InitFS(nil, argsA...)
 		dirB = test_helpers.TmpDir + "/b"
@@ -49,6 +67,7 @@ func TestMain(m *testing.M) {
 		os.RemoveAll(dirC)
 
 		if r != 0 {
+			fmt.Printf("testcases[%d] = %#v failed\n", i, tc)
 			os.Exit(r)
 		}
 	}
diff --git a/tests/reverse/one_file_system_test.go b/tests/reverse/one_file_system_test.go
index 61fdb61..a3e441f 100644
--- a/tests/reverse/one_file_system_test.go
+++ b/tests/reverse/one_file_system_test.go
@@ -1,8 +1,9 @@
-package reverse
+package reverse_test
 
 import (
 	"io/ioutil"
 	"net/url"
+	"os"
 	"runtime"
 	"syscall"
 	"testing"
@@ -10,7 +11,10 @@ import (
 	"github.com/rfjakob/gocryptfs/tests/test_helpers"
 )
 
-func doTestOneFileSystem(t *testing.T, plaintextnames bool) {
+func TestOneFileSystem(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("only works on linux")
+	}
 	// Let's not explode with "TempDir: pattern contains path separator"
 	myEscapedName := url.PathEscape(t.Name())
 	mnt, err := ioutil.TempDir(test_helpers.TmpDir, myEscapedName)
@@ -20,6 +24,8 @@ func doTestOneFileSystem(t *testing.T, plaintextnames bool) {
 	cliArgs := []string{"-reverse", "-zerokey", "-one-file-system"}
 	if plaintextnames {
 		cliArgs = append(cliArgs, "-plaintextnames")
+	} else if deterministic_names {
+		cliArgs = append(cliArgs, "-deterministic-names")
 	}
 	test_helpers.MountOrFatal(t, "/", mnt, cliArgs...)
 	defer test_helpers.UnmountErr(mnt)
@@ -48,25 +54,22 @@ func doTestOneFileSystem(t *testing.T, plaintextnames bool) {
 		t.Skip("no mountpoints found, nothing to test")
 	}
 	for _, m := range mountpoints {
-		e, err := ioutil.ReadDir(mnt + "/" + m)
+		dir, err := os.Open(mnt + "/" + m)
+		if err != nil {
+			t.Error(err)
+		}
+		defer dir.Close()
+		e, err := dir.Readdirnames(-1)
 		if err != nil {
 			t.Error(err)
 		}
 		expected := 1
-		if plaintextnames {
+		if plaintextnames || deterministic_names {
 			expected = 0
 		}
 		if len(e) != expected {
-			t.Errorf("mountpoint %q does not look empty: %v", m, e)
+			t.Errorf("mountpoint %q should have %d entries, actually has: %v", m, expected, e)
 		}
 	}
 	t.Logf("tested %d mountpoints: %v", len(mountpoints), mountpoints)
 }
-
-func TestOneFileSystem(t *testing.T) {
-	if runtime.GOOS != "linux" {
-		t.Skip("only works on linux")
-	}
-	t.Run("normal", func(t *testing.T) { doTestOneFileSystem(t, false) })
-	t.Run("plaintextnames", func(t *testing.T) { doTestOneFileSystem(t, true) })
-}
-- 
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