signals not working in shells run under emacs on SUSE 6.3

Robert L Krawitz rlk at
Mon Feb 14 22:43:54 EST 2000

   Date: Mon, 14 Feb 2000 22:28:46 -0500
   From: Jerry Callen <jcallen at>
   CC: rpeterson at, discuss at Blu.Org

   Robert L Krawitz wrote:
   > What are the protections on your tty's and pty's starting with
   > /dev/tty*?

   Bingo! /dev/ptyp* were all 660; chmod'ing them to 666 fixed the problem.

   Thanks, Robert!

I think I've seen something like this before on a different Unix.  I'm
not certain if it was exactly the same thing or not, but...

BTW, they were 660 -- what was the group (tty on my system).  Perhaps
the intent is that emacs should be installed setgid tty, but that
seems like a truly horrid hack...

   > There might be some kind of security setting in 6.3 about whether user
   > programs are allowed to allocate ptys. 

   So what *are* the security implications of allowing user programs to
   allocate ptys?

Well, there are potential DoS problems if something allocates all the
pty's.  Beyond that, I'm not certain.  I think it used to be
considered a Bad Thing because well-behaved apps that allocated pty's
were supposed to register them in utmp or wtmp or whatnot, and only
root could do that.  I don't know if it still matters or not, or if
there are any other issues (maybe with something nasty opening one
side of the pty, something else coming along and innocently taking the
other, and it's now controlled by the bad guy?)

Robert Krawitz <rlk at>

Tall Clubs International  -- or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at
Project lead for The Gimp Print --

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton
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