Bug#611487: xterm: immediately exits upon running: exec login USER

[jeff@bsrd.net (Jeffrey Sheinberg)]

On Thu, Feb 03, 2011 at 05:47:46AM -0500, Thomas Dickey wrote:
> From: Thomas Dickey <dickey@his.com>
> To: Thomas Dickey <dickey@his.com>, 611487@bugs.debian.org
> Date: Thu, 3 Feb 2011 05:47:46 -0500 (EST)
> Subject: Re: Bug#611487: xterm: immediately exits upon running: exec login
>  USER
> X-Spam-Status: No, score=0.683 tagged_above=-99 required=5
>  tests=[AWL=-0.261,
>  BAYES_40=-0.185, DNS_FROM_OPENWHOIS=1.13, SPF_PASS=-0.001]
> 
> On Wed, 2 Feb 2011, Thomas Dickey wrote:
> 
> >On Sat, 29 Jan 2011, Jeffrey Sheinberg wrote:
> >
> >>This is a bug in xterm Version: 261-1 as I originally reported, please
> >>see my above comments.
> >
> >I can reproduce this difference without the utempter library
> >(though it's possible that the problem is related to ifdef's for
> >it).  I'll look for a solution and close out #268 "soon" (have
> >been busy setting up new development machines).
> 
> hmm - my quick check "without" was also without setgid, so there was no
> utmp entry.
> 
> Reading the source for login, I see that the error message comes
> from a check (a) not running as root and (b) no valid utmp entry
> found.
> 
> Given that, the likely explanation is that login is dropping the
> setuid itself.  I don't see that in the unpatched source, but see
> comments in the Debian patch which indicate that's intended
> behavior.
> 
> Looks like a possible workaround would be to use sudo or other
> wrapper that holds the setuid behavior.
> 

Hi Thomas,

1. As I originally wrote, I can "exec login" from xterm-235-2
successfully, but not from xterm-261-1, with no other changes to
my system.

2. Cyril noted in his reply that xfce4-terminal behaves similar to
xterm-261-1, so I checked this out, I also tried it for lxterminal - but
they have a different behavior than xterm-261-1,

    A. Xterm-261-1 seems to exit without ever invoking the login
    authentication process.

    B. Both xfce4-terminal and lxterminal invoke login and the
    authentication process is successful (it's in the syslog), and then
    they each exit.

So I still maintain that there is a bug in xterm-261-1 compared to
xterm-235-2.

Thanks,
-- 
Jeffrey Sheinberg