reverse: add gcmsiv flag and associated tests

11 files changed, 153 insertions, 64 deletions

diff --git a/Documentation/MANPAGE.md b/Documentation/MANPAGE.md
index bf696f1..5c31a92 100644
--- a/Documentation/MANPAGE.md
+++ b/Documentation/MANPAGE.md
@@ -58,6 +58,9 @@ to mount the gocryptfs filesytem without user interaction.
 **-fusedebug**
 :	Enable fuse library debug output
 
+**-gcmsiv**
+:	Use the GCM-SIV encryption mode (implied by -reverse)
+
 **-init**
 :	Initialize encrypted directory
 
@@ -94,7 +97,7 @@ runs as root, you can enable device files by passing the opposite mount option,
 interesting. For a complete liste see the section
 `FILESYSTEM-INDEPENDENT MOUNT OPTIONS` in mount(8).
 
-**-openssl bool**
+**-openssl bool/"auto"**
 :	Use OpenSSL instead of built-in Go crypto (default "auto"). Using
 built-in crypto is 4x slower unless your CPU has AES instructions and
 you are using Go 1.6+. In mode "auto", gocrypts chooses the faster
@@ -109,6 +112,10 @@ option.
 **-q, -quiet**
 :	Quiet - silence informational messages
 
+**-reverse**
+:	Reverse mode shows a read-only encrypted view of a plaintext
+directory
+
 **-ro**
 :	Mount the filesystem read-only
 
diff --git a/cli_args.go b/cli_args.go
index 4c91f44..b50c350 100644
--- a/cli_args.go
+++ b/cli_args.go
@@ -14,7 +14,7 @@ import (
 type argContainer struct {
 	debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
 	plaintextnames, quiet, nosyslog, wpanic,
-	longnames, allow_other, ro, reverse bool
+	longnames, allow_other, ro, reverse, gcmsiv bool
 	masterkey, mountpoint, cipherdir, cpuprofile, extpass,
 	memprofile, o string
 	// Configuration file name override
@@ -51,6 +51,7 @@ func parseCliOpts() (args argContainer) {
 		"Only works if user_allow_other is set in /etc/fuse.conf.")
 	flagSet.BoolVar(&args.ro, "ro", false, "Mount the filesystem read-only")
 	flagSet.BoolVar(&args.reverse, "reverse", false, "Reverse mode")
+	flagSet.BoolVar(&args.gcmsiv, "gcmsiv", false, "GCM-SIV encryption")
 	flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
 	flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
 	flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory profile to specified file")
diff --git a/init_dir.go b/init_dir.go
index fac4053..c9c7be6 100644
--- a/init_dir.go
+++ b/init_dir.go
@@ -39,7 +39,7 @@ func initDir(args *argContainer) {
 	}
 	password := readpassword.Twice(args.extpass)
 	creator := tlog.ProgramName + " " + GitVersion
-	err = configfile.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn, creator, args.reverse)
+	err = configfile.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn, creator, args.gcmsiv)
 	if err != nil {
 		tlog.Fatal.Println(err)
 		os.Exit(ERREXIT_INIT)
@@ -53,8 +53,14 @@ func initDir(args *argContainer) {
 			os.Exit(ERREXIT_INIT)
 		}
 	}
-
-	tlog.Info.Printf(tlog.ColorGreen + "The filesystem has been created successfully." + tlog.ColorReset)
+	mountArgs := ""
+	fsName := "gocryptfs"
+	if args.reverse {
+		mountArgs = " -reverse"
+		fsName = "gocryptfs-reverse"
+	}
+	tlog.Info.Printf(tlog.ColorGreen+"The %s filesystem has been created successfully."+tlog.ColorReset,
+		fsName)
 	wd, _ := os.Getwd()
 	friendlyPath, _ := filepath.Rel(wd, args.cipherdir)
 	if strings.HasPrefix(friendlyPath, "../") {
@@ -62,7 +68,7 @@ func initDir(args *argContainer) {
 		// keep the absolute path.
 		friendlyPath = args.cipherdir
 	}
-	tlog.Info.Printf(tlog.ColorGrey+"You can now mount it using: %s %s MOUNTPOINT"+tlog.ColorReset,
-		tlog.ProgramName, friendlyPath)
+	tlog.Info.Printf(tlog.ColorGrey+"You can now mount it using: %s%s %s MOUNTPOINT"+tlog.ColorReset,
+		tlog.ProgramName, mountArgs, friendlyPath)
 	os.Exit(0)
 }
diff --git a/internal/configfile/config_file.go b/internal/configfile/config_file.go
index b1504b4..32e7e66 100644
--- a/internal/configfile/config_file.go
+++ b/internal/configfile/config_file.go
@@ -45,7 +45,7 @@ type ConfFile struct {
 // CreateConfFile - create a new config with a random key encrypted with
 // "password" and write it to "filename".
 // Uses scrypt with cost parameter logN.
-func CreateConfFile(filename string, password string, plaintextNames bool, logN int, creator string, reverse bool) error {
+func CreateConfFile(filename string, password string, plaintextNames bool, logN int, creator string, gcmsiv bool) error {
 	var cf ConfFile
 	cf.filename = filename
 	cf.Creator = creator
@@ -59,7 +59,7 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN
 	cf.EncryptKey(key, password, logN)
 
 	// Set feature flags
-	cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagGCMIV128])
+	cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagGCMIV128]) // 128-bit IVs
 	if plaintextNames {
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagPlaintextNames])
 	} else {
@@ -67,8 +67,8 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagEMENames])
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagLongNames])
 	}
-	if reverse {
-		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagGCMSIV])
+	if gcmsiv {
+		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagGCMSIV]) // GCM-SIV encryption mode
 	}
 
 	// Write file to disk
diff --git a/internal/configfile/config_test.go b/internal/configfile/config_test.go
index 72c25f6..ac85c8d 100644
--- a/internal/configfile/config_test.go
+++ b/internal/configfile/config_test.go
@@ -71,7 +71,7 @@ func TestCreateConfFile(t *testing.T) {
 
 }
 
-func TestCreateConfFileReverse(t *testing.T) {
+func TestCreateConfFileGCMSIV(t *testing.T) {
 	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", true)
 	if err != nil {
 		t.Fatal(err)
@@ -87,7 +87,7 @@ func TestCreateConfFileReverse(t *testing.T) {
 
 func TestIsFeatureFlagKnown(t *testing.T) {
 	// Test a few hardcoded values
-	testKnownFlags := []string{"DirIV", "PlaintextNames", "EMENames", "GCMIV128", "LongNames"}
+	testKnownFlags := []string{"DirIV", "PlaintextNames", "EMENames", "GCMIV128", "LongNames", "GCMSIV"}
 	// And also everything in knownFlags (yes, it is likely that we end up with
 	// some duplicates. Does not matter.)
 	for _, f := range knownFlags {
diff --git a/main.go b/main.go
index ea9efad..e2777b0 100644
--- a/main.go
+++ b/main.go
@@ -111,11 +111,9 @@ func printVersion() {
 func main() {
 	runtime.GOMAXPROCS(4)
 	var err error
-
 	// Parse all command-line options (i.e. arguments starting with "-")
 	// into "args". Path arguments are parsed below.
 	args := parseCliOpts()
-
 	// Fork a child into the background if "-f" is not set AND we are mounting
 	// a filesystem. The child will do all the work.
 	if !args.foreground && flagSet.NArg() == 2 {
@@ -152,6 +150,10 @@ func main() {
 	if args.quiet {
 		tlog.Info.Enabled = false
 	}
+	// "-reverse" implies "-gcmsiv"
+	if args.reverse {
+		args.gcmsiv = true
+	}
 	// "-config"
 	if args.config != "" {
 		args.config, err = filepath.Abs(args.config)
@@ -201,7 +203,7 @@ func main() {
 	} else {
 		tlog.Debug.Printf("OpenSSL enabled")
 	}
-	// Operation flags: init, passwd or mount
+	// Operation flags: -init or -passwd; otherwise: mount
 	// "-init"
 	if args.init {
 		if flagSet.NArg() > 1 {
@@ -288,8 +290,7 @@ func initFuseFrontend(key []byte, args argContainer, confFile *configfile.ConfFi
 	if args.openssl {
 		cryptoBackend = cryptocore.BackendOpenSSL
 	}
-	if args.reverse {
-		// reverse implies GCMSIV
+	if args.gcmsiv {
 		cryptoBackend = cryptocore.BackendGCMSIV
 	}
 	frontendArgs := fusefrontend.Args{
@@ -306,7 +307,7 @@ func initFuseFrontend(key []byte, args argContainer, confFile *configfile.ConfFi
 		if confFile.IsFeatureFlagSet(configfile.FlagGCMSIV) {
 			frontendArgs.CryptoBackend = cryptocore.BackendGCMSIV
 		} else if args.reverse {
-			tlog.Fatal.Printf("GCMSIV is required by reverse mode, but not enabled in the config file")
+			tlog.Fatal.Printf("GCM-SIV is required by reverse mode, but not enabled in the config file")
 			os.Exit(ERREXIT_USAGE)
 		}
 	}
@@ -317,11 +318,14 @@ func initFuseFrontend(key []byte, args argContainer, confFile *configfile.ConfFi
 	}
 	jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
 	tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
-
+	if frontendArgs.CryptoBackend == cryptocore.BackendGCMSIV {
+		tlog.Info.Printf(tlog.ColorYellow +
+			"Warning: The GCM-SIV format used by reverse mode is not yet finalized.\n" +
+			"The on-disk format will change in the future." + tlog.ColorReset)
+	}
 	var finalFs pathfs.FileSystem
 	if args.reverse {
 		finalFs = fusefrontend_reverse.NewFS(frontendArgs)
-		tlog.Info.Printf(tlog.ColorYellow + "REVERSE MODE IS EXPERIMENTAL!" + tlog.ColorReset)
 	} else {
 		finalFs = fusefrontend.NewFS(frontendArgs)
 	}
diff --git a/test.bash b/test.bash
index 2a565b7..8711d8f 100755
--- a/test.bash
+++ b/test.bash
@@ -8,8 +8,8 @@ source build.bash
 
 go test ./... $*
 
-# Clean up after ourself, but don't descend into maybe still mounted
-# example filesystems
+# Clean up after ourself, but don't descend into possibly still mounted
+# example filesystems.
 # The tests cannot to this themselves as they are run in parallel
 rm -Rf --one-file-system /tmp/gocryptfs-test-parent
 
diff --git a/tests/normal/cli_test.go b/tests/normal/cli_test.go
index ed3111b..62ad217 100644
--- a/tests/normal/cli_test.go
+++ b/tests/normal/cli_test.go
@@ -5,7 +5,6 @@ package normal
 import (
 	"os"
 	"os/exec"
-	"path/filepath"
 	"testing"
 
 	"github.com/rfjakob/gocryptfs/internal/configfile"
@@ -24,18 +23,45 @@ func TestMain(m *testing.M) {
 // Test -init flag
 func TestInit(t *testing.T) {
 	dir := test_helpers.InitFS(t)
-	_, err := os.Stat(filepath.Join(dir, configfile.ConfDefaultName))
+	_, c, err := configfile.LoadConfFile(dir+"/"+configfile.ConfDefaultName, "test")
 	if err != nil {
 		t.Fatal(err)
 	}
+	if c.IsFeatureFlagSet(configfile.FlagGCMSIV) {
+		t.Error("GCMSIV flag should not be set")
+	}
 }
 
-// Test -passwd flag
-func TestPasswd(t *testing.T) {
-	// Create FS
-	dir := test_helpers.InitFS(t)
+// Test -init with -gcmsiv
+func TestInitGcmsiv(t *testing.T) {
+	dir := test_helpers.InitFS(t, "-gcmsiv")
+	_, c, err := configfile.LoadConfFile(dir+"/"+configfile.ConfDefaultName, "test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !c.IsFeatureFlagSet(configfile.FlagGCMSIV) {
+		t.Error("GCMSIV flag should be set but is not")
+	}
+}
+
+// Test -init with -reverse
+func TestInitReverse(t *testing.T) {
+	dir := test_helpers.InitFS(t, "-reverse")
+	_, c, err := configfile.LoadConfFile(dir+"/"+configfile.ConfReverseName, "test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !c.IsFeatureFlagSet(configfile.FlagGCMSIV) {
+		t.Error("GCMSIV flag should be set but is not")
+	}
+}
+
+func testPasswd(t *testing.T, dir string, extraArgs ...string) {
 	// Change password using "-extpass"
-	cmd := exec.Command(test_helpers.GocryptfsBinary, "-q", "-passwd", "-extpass", "echo test", dir)
+	args := []string{"-q", "-passwd", "-extpass", "echo test"}
+	args = append(args, extraArgs...)
+	args = append(args, dir)
+	cmd := exec.Command(test_helpers.GocryptfsBinary, args...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	err := cmd.Run()
@@ -43,7 +69,10 @@ func TestPasswd(t *testing.T) {
 		t.Error(err)
 	}
 	// Change password using stdin
-	cmd = exec.Command(test_helpers.GocryptfsBinary, "-q", "-passwd", dir)
+	args = []string{"-q", "-passwd", "-extpass", "echo test"}
+	args = append(args, extraArgs...)
+	args = append(args, dir)
+	cmd = exec.Command(test_helpers.GocryptfsBinary, args...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	p, err := cmd.StdinPipe()
@@ -65,6 +94,20 @@ func TestPasswd(t *testing.T) {
 	}
 }
 
+// Test -passwd flag
+func TestPasswd(t *testing.T) {
+	// Create FS
+	dir := test_helpers.InitFS(t)
+	testPasswd(t, dir)
+}
+
+// Test -passwd with -reverse
+func TestPasswdReverse(t *testing.T) {
+	// Create FS
+	dir := test_helpers.InitFS(t, "-reverse")
+	testPasswd(t, dir, "-reverse")
+}
+
 // Test -init & -config flag
 func TestInitConfig(t *testing.T) {
 	config := test_helpers.TmpDir + "/TestInitConfig.conf"
diff --git a/tests/reverse/correctness_test.go b/tests/reverse/correctness_test.go
new file mode 100644
index 0000000..e268815
--- /dev/null
+++ b/tests/reverse/correctness_test.go
@@ -0,0 +1,17 @@
+package reverse_test
+
+import (
+	"os"
+	"testing"
+)
+
+func TestLongnameStat(t *testing.T) {
+	_, err := os.Stat(dirA + "/" + "")
+	if err != nil {
+		t.Error(err)
+	}
+	_, err = os.Stat(dirA + "/" + "")
+	if err != nil {
+		t.Error(err)
+	}
+}
diff --git a/tests/reverse/longname_perf_test.go b/tests/reverse/longname_perf_test.go
index 43acd25..f170ad7 100644
--- a/tests/reverse/longname_perf_test.go
+++ b/tests/reverse/longname_perf_test.go
@@ -5,34 +5,17 @@ import (
 	"fmt"
 	"os"
 	"testing"
-
-	"github.com/rfjakob/gocryptfs/tests/test_helpers"
 )
 
-var dirA, dirB, x240 string
-
-func TestMain(m *testing.M) {
-	x240 = string(bytes.Repeat([]byte("x"), 240))
-	dirA = test_helpers.TmpDir + "/a"
-	dirB = test_helpers.TmpDir + "/b"
-	os.Mkdir(dirA, 0700)
-	os.Mkdir(dirB, 0700)
-	generateFiles(dirA)
-	test_helpers.MountOrExit(dirA, dirB, "-zerokey", "-reverse")
-	r := m.Run()
-	test_helpers.UnmountPanic(dirB)
-	os.RemoveAll(test_helpers.TmpDir)
-	os.Exit(r)
-}
-
-func genName(i int) string {
-	return fmt.Sprintf("%04d.%s", i, x240)
+func genName(i int, postfix string) string {
+	return fmt.Sprintf("%04d.%s", i, postfix)
 }
 
 // Create 10000 files with long names
-func generateFiles(dir string) {
+func generateLongnameFiles(dir string) {
+	x240 := string(bytes.Repeat([]byte("x"), 240))
 	for i := 0; i < 100000; i++ {
-		n := genName(i)
+		n := genName(i, x240)
 		f, err := os.Create(dir + "/" + n)
 		if err != nil {
 			panic(err)
@@ -41,18 +24,9 @@ func generateFiles(dir string) {
 	}
 }
 
-func TestLongnameStat(t *testing.T) {
-	_, err := os.Stat(dirA + "/" + genName(0))
-	if err != nil {
-		t.Error(err)
-	}
-	_, err = os.Stat(dirA + "/" + genName(9999))
-	if err != nil {
-		t.Error(err)
-	}
-}
-
 func BenchmarkLongnameStat(b *testing.B) {
+	// Setup
+	generateLongnameFiles(dirA)
 	dirFd, err := os.Open(dirB)
 	if err != nil {
 		b.Fatal(err)
@@ -63,6 +37,7 @@ func BenchmarkLongnameStat(b *testing.B) {
 	}
 	l := len(encryptedNames)
 	dirFd.Close()
+	// Benchmark
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		_, err := os.Stat(dirB + "/" + encryptedNames[i%l])
@@ -70,4 +45,8 @@ func BenchmarkLongnameStat(b *testing.B) {
 			b.Fatal(err)
 		}
 	}
+	// Cleanup
+	b.StopTimer()
+	os.RemoveAll(dirA)
+	os.Mkdir(dirA, 0700)
 }
diff --git a/tests/reverse/main_test.go b/tests/reverse/main_test.go
new file mode 100644
index 0000000..3d10750
--- /dev/null
+++ b/tests/reverse/main_test.go
@@ -0,0 +1,32 @@
+package reverse_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/rfjakob/gocryptfs/tests/test_helpers"
+)
+
+var dirA, dirB, dirC string
+
+func TestMain(m *testing.M) {
+	dirA = test_helpers.TmpDir + "/a"
+	dirB = test_helpers.TmpDir + "/b"
+	dirC = test_helpers.TmpDir + "/c"
+	if err := os.Mkdir(dirA, 0700); err != nil {
+		panic(err)
+	}
+	if err := os.Mkdir(dirB, 0700); err != nil {
+		panic(err)
+	}
+	if err := os.Mkdir(dirC, 0700); err != nil {
+		panic(err)
+	}
+	test_helpers.MountOrExit(dirA, dirB, "-zerokey", "-reverse")
+	test_helpers.MountOrExit(dirB, dirC, "-zerokey", "-gcmsiv")
+	r := m.Run()
+	test_helpers.UnmountPanic(dirC)
+	test_helpers.UnmountPanic(dirB)
+	os.RemoveAll(test_helpers.TmpDir)
+	os.Exit(r)
+}