readpassword: convert from string to []byte

This will allows us to overwrite the password
with zeros once we are done with it.

https://github.com/rfjakob/gocryptfs/issues/211

3 files changed, 17 insertions, 14 deletions

diff --git a/internal/readpassword/extpass_test.go b/internal/readpassword/extpass_test.go
index 4af775a..cdfea4e 100644
--- a/internal/readpassword/extpass_test.go
+++ b/internal/readpassword/extpass_test.go
@@ -8,6 +8,8 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
+var testPw = []byte("test")
+
 func TestMain(m *testing.M) {
 	// Shut up info output
 	tlog.Info.Enabled = false
@@ -16,7 +18,7 @@ func TestMain(m *testing.M) {
 
 func TestExtpass(t *testing.T) {
 	p1 := "ads2q4tw41reg52"
-	p2 := readPasswordExtpass("echo " + p1)
+	p2 := string(readPasswordExtpass("echo " + p1))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
@@ -24,7 +26,7 @@ func TestExtpass(t *testing.T) {
 
 func TestOnceExtpass(t *testing.T) {
 	p1 := "lkadsf0923rdfi48rqwhdsf"
-	p2 := Once("echo " + p1)
+	p2 := string(Once("echo " + p1))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
@@ -32,7 +34,7 @@ func TestOnceExtpass(t *testing.T) {
 
 func TestTwiceExtpass(t *testing.T) {
 	p1 := "w5w44t3wfe45srz434"
-	p2 := Once("echo " + p1)
+	p2 := string(Once("echo " + p1))
 	if p1 != p2 {
 		t.Errorf("p1=%q != p2=%q", p1, p2)
 	}
diff --git a/internal/readpassword/read.go b/internal/readpassword/read.go
index 481911b..047eba9 100644
--- a/internal/readpassword/read.go
+++ b/internal/readpassword/read.go
@@ -2,6 +2,7 @@
 package readpassword
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"os"
@@ -23,7 +24,7 @@ const (
 
 // Once tries to get a password from the user, either from the terminal, extpass
 // or stdin.
-func Once(extpass string) string {
+func Once(extpass string) []byte {
 	if extpass != "" {
 		return readPasswordExtpass(extpass)
 	}
@@ -35,7 +36,7 @@ func Once(extpass string) string {
 
 // Twice is the same as Once but will prompt twice if we get the password from
 // the terminal.
-func Twice(extpass string) string {
+func Twice(extpass string) []byte {
 	if extpass != "" {
 		return readPasswordExtpass(extpass)
 	}
@@ -44,7 +45,7 @@ func Twice(extpass string) string {
 	}
 	p1 := readPasswordTerminal("Password: ")
 	p2 := readPasswordTerminal("Repeat: ")
-	if p1 != p2 {
+	if !bytes.Equal(p1, p2) {
 		tlog.Fatal.Println("Passwords do not match")
 		os.Exit(exitcodes.ReadPassword)
 	}
@@ -53,7 +54,7 @@ func Twice(extpass string) string {
 
 // readPasswordTerminal reads a line from the terminal.
 // Exits on read error or empty result.
-func readPasswordTerminal(prompt string) string {
+func readPasswordTerminal(prompt string) []byte {
 	fd := int(os.Stdin.Fd())
 	fmt.Fprintf(os.Stderr, prompt)
 	// terminal.ReadPassword removes the trailing newline
@@ -67,12 +68,12 @@ func readPasswordTerminal(prompt string) string {
 		tlog.Fatal.Println("Password is empty")
 		os.Exit(exitcodes.PasswordEmpty)
 	}
-	return string(p)
+	return p
 }
 
 // readPasswordStdin reads a line from stdin.
 // It exits with a fatal error on read error or empty result.
-func readPasswordStdin() string {
+func readPasswordStdin() []byte {
 	tlog.Info.Println("Reading password from stdin")
 	p := readLineUnbuffered(os.Stdin)
 	if len(p) == 0 {
@@ -85,7 +86,7 @@ func readPasswordStdin() string {
 // readPasswordExtpass executes the "extpass" program and returns the first line
 // of the output.
 // Exits on read error or empty result.
-func readPasswordExtpass(extpass string) string {
+func readPasswordExtpass(extpass string) []byte {
 	tlog.Info.Println("Reading password from extpass program")
 	var parts []string
 	// The option "-passfile=FILE" gets transformed to
@@ -125,7 +126,7 @@ func readPasswordExtpass(extpass string) string {
 
 // readLineUnbuffered reads single bytes from "r" util it gets "\n" or EOF.
 // The returned string does NOT contain the trailing "\n".
-func readLineUnbuffered(r io.Reader) (l string) {
+func readLineUnbuffered(r io.Reader) (l []byte) {
 	b := make([]byte, 1)
 	for {
 		if len(l) > maxPasswordLen {
@@ -146,7 +147,7 @@ func readLineUnbuffered(r io.Reader) (l string) {
 		if b[0] == '\n' {
 			return l
 		}
-		l = l + string(b)
+		l = append(l, b...)
 	}
 }
 
diff --git a/internal/readpassword/stdin_test.go b/internal/readpassword/stdin_test.go
index 2d9f93f..8cf9954 100644
--- a/internal/readpassword/stdin_test.go
+++ b/internal/readpassword/stdin_test.go
@@ -11,7 +11,7 @@ import (
 func TestStdin(t *testing.T) {
 	p1 := "g55434t55wef"
 	if os.Getenv("TEST_SLAVE") == "1" {
-		p2 := readPasswordStdin()
+		p2 := string(readPasswordStdin())
 		if p1 != p2 {
 			fmt.Fprintf(os.Stderr, "%q != %q", p1, p2)
 			os.Exit(1)
@@ -44,7 +44,7 @@ func TestStdin(t *testing.T) {
 func TestStdinEof(t *testing.T) {
 	p1 := "asd45as5f4a36"
 	if os.Getenv("TEST_SLAVE") == "1" {
-		p2 := readPasswordStdin()
+		p2 := string(readPasswordStdin())
 		if p1 != p2 {
 			fmt.Fprintf(os.Stderr, "%q != %q", p1, p2)
 			os.Exit(1)