Re: safe logging xterm

[Valdis.Kletnieks () vt edu (Valdis.Kletnieks () vt edu)]

On Thu, 16 Mar 1995 17:42:07 EST, Robert Banz said:
> On Tue, 14 Mar 1995, Adam Shostack wrote:
> > Yes, it leaves setuid on a program that is way too large.  Xterm tends
> > to be setuid so it can write to utmp.  Thats a bad reason to make a
> > large program setuid.
> Hm.  Why not make utmp group "bob" writable, and make xterm setgid "bob"?

Well.. mostly because the OTHER think xterm likes to be set-UID for is
so it can chown()/chmod() your pty so you own it so you can do things
like 'mesg n'... ;)

ObSecurityHole: AIX 3.2.5 and 4.1.2 /bin/mesg, /bin/write, and friends
still don't do the set-GID tty thing from BSD 4.2, so if you run 'mesg
y' your terminal is mode 644 and anybody can scribble on it, rather
than the nicer BSD way of setting it to mode 640 and things that were
set-GID tty could scribble on it, after filtering any inappropriate
control characters out, etc...

It aint news to IBM - I filed a bug report against AIX/370 for this back
in 1990 or so.  *sigh*.

                                Valdis Kletnieks
                                Computer Systems Engineer
                                Virginia Tech