Allow multiple -extpass arguments

To support arguments containing spaces, -extpass can now
be passed multiple times.

#289

Documentation/MANPAGE.md

@@ -89,8 +89,19 @@ Enable (`-exec`) or disable (`-noexec`) executables in a gocryptfs mount
 #### -extpass string
 Use an external program (like ssh-askpass) for the password prompt.
 The program should return the password on stdout, a trailing newline is
-stripped by gocryptfs. Using something like "cat /mypassword.txt" allows
-one to mount the gocryptfs filesystem without user interaction.
+stripped by gocryptfs. If you just want to read from a password file, see `-passfile`.
+
+When `-extpass` is specified once, the string argument will be split on spaces.
+For example, `-extpass "md5sum my password.txt"` will be executed as
+`"md5sum" "my" "password.txt"`, which is NOT what you want.
+
+Specify `-extpass` twice or more to use the string arguments as-is.
+For example, you DO want to call `md5sum` like this:
+`-extpass "md5sum" -extpass "my password.txt"`.
+
+If you want to prevent splitting on spaces but don't want to pass arguments
+to your program, use `"--"`, which is accepted by most programs:
+`-extpass "my program" -extpass "--"`
 
 #### -fg, -f
 Stay in the foreground instead of forking away. Implies "-nosyslog".

README.md

@@ -182,6 +182,8 @@ v1.7, in progress (v1.7-beta1: 2019-01-03, v1.7-rc1: 2019-01-04)
   ([#320](https://github.com/rfjakob/gocryptfs/issues/320)).
   Prevents trouble in the unlikely case that gocryptfs is called with
   stdin,stdout and/or stderr closed.
+* `-extpass` now can be specified multiple times to support arguments containing spaces
+  ([#289](https://github.com/rfjakob/gocryptfs/issues/289))
 
 v1.6.1, 2018-12-12
 * Fix "Operation not supported" chmod errors on Go 1.11

cli_args.go

@@ -32,9 +32,11 @@ type argContainer struct {
 	sharedstorage, devrandom, fsck, trezor bool
 	// Mount options with opposites
 	dev, nodev, suid, nosuid, exec, noexec, rw, ro bool
-	masterkey, mountpoint, cipherdir, cpuprofile, extpass,
+	masterkey, mountpoint, cipherdir, cpuprofile,
 	memprofile, ko, passfile, ctlsock, fsname, force_owner, trace string
-	// For reverse mode, --exclude is available. It can be specified multiple times.
+	// -extpass can be passed multiple times
+	extpass multipleStrings
+	// For reverse mode, -exclude is available. It can be specified multiple times.
 	exclude multipleStrings
 	// Configuration file name override
 	config             string
@@ -62,6 +64,11 @@ func (s *multipleStrings) Set(val string) error {
 	return nil
 }
 
+func (s *multipleStrings) Empty() bool {
+	s2 := []string(*s)
+	return len(s2) == 0
+}
+
 var flagSet *flag.FlagSet
 
 // prefixOArgs transform options passed via "-o foo,bar" into regular options
@@ -179,7 +186,6 @@ func parseCliOpts() (args argContainer) {
 	flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
 	flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory profile to specified file")
 	flagSet.StringVar(&args.config, "config", "", "Use specified config file instead of CIPHERDIR/gocryptfs.conf")
-	flagSet.StringVar(&args.extpass, "extpass", "", "Use external program for the password prompt")
 	flagSet.StringVar(&args.passfile, "passfile", "", "Read password from file")
 	flagSet.StringVar(&args.ko, "ko", "", "Pass additional options directly to the kernel, comma-separated list")
 	flagSet.StringVar(&args.ctlsock, "ctlsock", "", "Create control socket at specified path")
@@ -190,6 +196,8 @@ func parseCliOpts() (args argContainer) {
 	// -e, --exclude
 	flagSet.Var(&args.exclude, "e", "Alias for -exclude")
 	flagSet.Var(&args.exclude, "exclude", "Exclude relative path from reverse view")
+	// -extpass
+	flagSet.Var(&args.extpass, "extpass", "Use external program for the password prompt")
 
 	flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
 		"successful mount - used internally for daemonization")
@@ -248,19 +256,19 @@ func parseCliOpts() (args argContainer) {
 		args.allow_other = false
 		args.ko = "noexec"
 	}
-	if args.extpass != "" && args.passfile != "" {
+	if !args.extpass.Empty() && args.passfile != "" {
 		tlog.Fatal.Printf("The options -extpass and -passfile cannot be used at the same time")
 		os.Exit(exitcodes.Usage)
 	}
 	if args.passfile != "" && args.masterkey != "" {
 		tlog.Fatal.Printf("The options -passfile and -masterkey cannot be used at the same time")
 		os.Exit(exitcodes.Usage)
 	}
-	if args.extpass != "" && args.masterkey != "" {
+	if !args.extpass.Empty() && args.masterkey != "" {
 		tlog.Fatal.Printf("The options -extpass and -masterkey cannot be used at the same time")
 		os.Exit(exitcodes.Usage)
 	}
-	if args.extpass != "" && args.trezor {
+	if !args.extpass.Empty() && args.trezor {
 		tlog.Fatal.Printf("The options -extpass and -trezor cannot be used at the same time")
 		os.Exit(exitcodes.Usage)
 	}

gocryptfs-xray/xray_main.go

@@ -68,7 +68,7 @@ func main() {
 
 func dumpMasterKey(fn string) {
 	tlog.Info.Enabled = false
-	pw := readpassword.Once("", "", "")
+	pw := readpassword.Once(nil, "", "")
 	masterkey, _, err := configfile.LoadAndDecrypt(fn, pw)
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)

init_dir.go

@@ -68,7 +68,7 @@ func initDir(args *argContainer) {
 		}
 	}
 	// Choose password for config file
-	if args.extpass == "" {
+	if args.extpass.Empty() {
 		tlog.Info.Printf("Choose a password for protecting your files.")
 	}
 	{
@@ -80,7 +80,7 @@ func initDir(args *argContainer) {
 			password = readpassword.Trezor(trezorPayload)
 		} else {
 			// Normal password entry
-			password = readpassword.Twice(args.extpass, args.passfile)
+			password = readpassword.Twice([]string(args.extpass), args.passfile)
 			readpassword.CheckTrailingGarbage()
 		}
 		creator := tlog.ProgramName + " " + GitVersion

internal/readpassword/extpass_test.go

@@ -18,23 +18,49 @@ func TestMain(m *testing.M) {
 
 func TestExtpass(t *testing.T) {
 	p1 := "ads2q4tw41reg52"
-	p2 := string(readPasswordExtpass("echo " + p1))
+	p2 := string(readPasswordExtpass([]string{"echo " + p1}))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
 }
 
 func TestOnceExtpass(t *testing.T) {
 	p1 := "lkadsf0923rdfi48rqwhdsf"
-	p2 := string(Once("echo "+p1, "", ""))
+	p2 := string(Once([]string{"echo " + p1}, "", ""))
+	if p1 != p2 {
+		t.Errorf("p1=%q != p2=%q", p1, p2)
+	}
+}
+
+// extpass with two arguments
+func TestOnceExtpass2(t *testing.T) {
+	p1 := "foo"
+	p2 := string(Once([]string{"echo", p1}, "", ""))
+	if p1 != p2 {
+		t.Errorf("p1=%q != p2=%q", p1, p2)
+	}
+}
+
+// extpass with three arguments
+func TestOnceExtpass3(t *testing.T) {
+	p1 := "foo bar baz"
+	p2 := string(Once([]string{"echo", "foo", "bar", "baz"}, "", ""))
+	if p1 != p2 {
+		t.Errorf("p1=%q != p2=%q", p1, p2)
+	}
+}
+
+func TestOnceExtpassSpaces(t *testing.T) {
+	p1 := "mypassword"
+	p2 := string(Once([]string{"cat", "passfile_test_files/file with spaces.txt"}, "", ""))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
 }
 
 func TestTwiceExtpass(t *testing.T) {
 	p1 := "w5w44t3wfe45srz434"
-	p2 := string(Once("echo "+p1, "", ""))
+	p2 := string(Once([]string{"echo " + p1}, "", ""))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
@@ -46,7 +72,7 @@ func TestTwiceExtpass(t *testing.T) {
 // https://talks.golang.org/2014/testing.slide#23 .
 func TestExtpassEmpty(t *testing.T) {
 	if os.Getenv("TEST_SLAVE") == "1" {
-		readPasswordExtpass("echo")
+		readPasswordExtpass([]string{"echo"})
 		return
 	}
 	cmd := exec.Command(os.Args[0], "-test.run=TestExtpassEmpty$")

internal/readpassword/passfile_test.go

@@ -14,6 +14,7 @@ func TestPassfile(t *testing.T) {
 		{"mypassword.txt", "mypassword"},
 		{"mypassword_garbage.txt", "mypassword"},
 		{"mypassword_missing_newline.txt", "mypassword"},
+		{"file with spaces.txt", "mypassword"},
 	}
 	for _, tc := range testcases {
 		pw := readPassFile("passfile_test_files/" + tc.file)

internal/readpassword/passfile_test_files/file with spaces.txt

@@ -0,0 +1 @@
+mypassword

internal/readpassword/read.go

@@ -24,11 +24,11 @@ const (
 
 // Once tries to get a password from the user, either from the terminal, extpass
 // or stdin. Leave "prompt" empty to use the default "Password: " prompt.
-func Once(extpass string, passfile string, prompt string) []byte {
+func Once(extpass []string, passfile string, prompt string) []byte {
 	if passfile != "" {
 		return readPassFile(passfile)
 	}
-	if extpass != "" {
+	if len(extpass) != 0 {
 		return readPasswordExtpass(extpass)
 	}
 	if prompt == "" {
@@ -42,11 +42,11 @@ func Once(extpass string, passfile string, prompt string) []byte {
 
 // Twice is the same as Once but will prompt twice if we get the password from
 // the terminal.
-func Twice(extpass string, passfile string) []byte {
+func Twice(extpass []string, passfile string) []byte {
 	if passfile != "" {
 		return readPassFile(passfile)
 	}
-	if extpass != "" {
+	if len(extpass) != 0 {
 		return readPasswordExtpass(extpass)
 	}
 	if !terminal.IsTerminal(int(os.Stdin.Fd())) {
@@ -99,9 +99,14 @@ func readPasswordStdin(prompt string) []byte {
 // readPasswordExtpass executes the "extpass" program and returns the first line
 // of the output.
 // Exits on read error or empty result.
-func readPasswordExtpass(extpass string) []byte {
-	tlog.Info.Println("Reading password from extpass program")
-	parts := strings.Split(extpass, " ")
+func readPasswordExtpass(extpass []string) []byte {
+	var parts []string
+	if len(extpass) == 1 {
+		parts = strings.Split(extpass[0], " ")
+	} else {
+		parts = extpass
+	}
+	tlog.Info.Printf("Reading password from extpass program %q, arguments: %q\n", parts[0], parts[1:])
 	cmd := exec.Command(parts[0], parts[1:]...)
 	cmd.Stderr = os.Stderr
 	pipe, err := cmd.StdoutPipe()

main.go

@@ -53,7 +53,7 @@ func loadConfig(args *argContainer) (masterkey []byte, cf *configfile.ConfFile,
 		pw = readpassword.Trezor(cf.TrezorPayload)
 	} else {
 		// Normal password entry
-		pw = readpassword.Once(args.extpass, args.passfile, "")
+		pw = readpassword.Once([]string(args.extpass), args.passfile, "")
 	}
 	tlog.Info.Println("Decrypting master key")
 	masterkey, err = cf.DecryptMasterKey(pw)
@@ -93,7 +93,7 @@ func changePassword(args *argContainer) {
 			log.Panic("empty masterkey")
 		}
 		tlog.Info.Println("Please enter your new password.")
-		newPw := readpassword.Twice(args.extpass, args.passfile)
+		newPw := readpassword.Twice([]string(args.extpass), args.passfile)
 		readpassword.CheckTrailingGarbage()
 		confFile.EncryptKey(masterkey, newPw, confFile.ScryptObject.LogN())
 		for i := range newPw {

masterkey.go

@@ -43,7 +43,7 @@ func getMasterKey(args *argContainer) (masterkey []byte, confFile *configfile.Co
 	masterkeyFromStdin := false
 	// "-masterkey=stdin"
 	if args.masterkey == "stdin" {
-		args.masterkey = string(readpassword.Once("", "", "Masterkey"))
+		args.masterkey = string(readpassword.Once(nil, "", "Masterkey"))
 		masterkeyFromStdin = true
 	}
 	// "-masterkey=941a6029-3adc6a1c-..."