x/crypto/ssh/terminal: ReadPassword keeps echo disabled when stopped with Ctrl+C

[giner]

What version of Go are you using (go version)?

$ go version
go version go1.12.1 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

Linux and macOS

What did you do?

Tried to use the following code to read passwords (from https://qiita.com/moutend/items/12d53750363edbbc3d6b):

package main
  
import (
    "fmt"
    "log"
    "syscall"

    "golang.org/x/crypto/ssh/terminal"
)

func main() {
    fmt.Print("Password: ")
    password, err := terminal.ReadPassword(int(syscall.Stdin))
    if err != nil {
        log.Fatal(err)
    } else {
        fmt.Printf("\nYour password is %v\n", string(password))
    }
}

What did you expect to see?

If I press Ctrl+C at the point when I'm supposed to enter password I'm expecting my terminal back working as before running the code.

What did you see instead?

I'm unable to see what I'm typing anymore as echo is kept disabled

[andybons]

@FiloSottile @hanwen

[hanwen]

I thought this is normal behavior with other similar programs too.

[agnivade]

Your expected and observed reports are different. You expect your terminal back when you press ctrl-C (which does happen), but you observe that you cannot see your password (which is the right behavior).

Please clarify.

EDIT: Sorry, I get it now.

[agnivade]

Doesn't seem to be the behavior for sudo su -

[giner]

Removed Linux from the description as I cannot reproduce it on Linux with go1.12.1.

[agnivade]

Actually, I can reproduce on Linux.

[giner]

It seems to depend on the shell. Cannot reproduce with bash (Ubuntu 18.04) but reproduced with dash.

[zladovan]

I was able to reproduce with bash 5.0.11 on linux 4.19.99-1-MANJARO.

go version go1.13.7 linux/amd64

[norbjd]

I got the exact same issue and found a way to fix it, based on this thread: https://groups.google.com/g/golang-nuts/c/DCl8xUJMJJ0.

import (
	"os"
	"os/signal"
	"syscall"

	"golang.org/x/term"
)

func ReadPassword() (string, error) {
	stdin := int(syscall.Stdin)
	oldState, err := term.GetState(stdin)
	if err != nil {
		return "", err
	}
	defer term.Restore(stdin, oldState)

	sigch := make(chan os.Signal, 1)
	signal.Notify(sigch, os.Interrupt)
	go func() {
		for _ = range sigch {
			term.Restore(stdin, oldState)
			os.Exit(1)
		}
	}()

	password, err := term.ReadPassword(stdin)
	if err != nil {
		return "", err
	}
	return string(password), nil
}

Calling that ReadPassword method and doing a CTRL+C when the prompt appears does restore the old terminal state, meaning echo is not disabled anymore.

Also, based on that PR: https://go-review.googlesource.com/c/crypto/+/258003/, I believe we should use golang.org/x/term instead of golang.org/x/crypto/ssh/terminal.

Hope that helps.

[SadPencil]

I reproduced this bug with ash on OpenWRT.
BusyBox v1.35.0 (2022-06-23 16:55:05 UTC) built-in shell (ash)

[SadPencil]

The issue should be renamed to x/term from x/crypto/ssh/terminal.

@norbjd Personally I think your code is exactly the solution to this issue. How about making a pull request? So that the implementation of readPassword() gets fixed directly.