Bug#1087496: util-linux: mesg, write and wall unclean status

[Chris Hofstaedtler]

* Jakub Wilk <jwilk at jwilk.net> [241211 19:09]:
> * Chris Hofstaedtler <zeha at debian.org>, 2024-11-14 20:57:
> > As far as I can tell, the default for /dev/tty* is mode 0620, and the
> > group owner being tty. No users should be part of that group.
> 
> There's at least nwall, which is setgid tty:
> 
>    $ ls -l /usr/bin/nwall
>    -r-xr-sr-x 1 root tty 17988 Nov 14 21:30 /usr/bin/nwall

I don't quite understand why nwall is relevant here. It is a program
that is installed by root. It still does not make a random user be
part of the tty group.

> > So no, you don't need to remove the +w part from the tty group.
> 
> Yes, you do.

systemd could probably change its compiled-in 0620 setting to 0600. 
CCing systemd@ for that.

Chris