Re: [PATCH v3 2/2] tty: Allow TIOCSTI to be disabled

[Kees Cook]

On Sun, Jun 25, 2023 at 05:56:25PM +0200, Samuel Thibault wrote:
> > Can we perhaps just introduce a CAP_TIOCSTI that the brltty daemon would
> > be able to use? We could even make it only allow TIOCSTI on the linux
> > console (tty->ops == con_ops).

Does brltty run with CAP_SYS_ADMIN? That seems a sensible exception to
be made.

> *Please* comment on this so we can progress. ATM people are
> advising each other to set dev.tty.legacy_tiocsti=1, which is just
> counter-productive in terms of security...

So is there really no solution for brltty and TIOCSTI being disabled?
What is FreeBSD doing? I imagine it's the same situation there too,
though maybe there is just no support?

https://www.mail-archive.com/brltty@xxxxxxxxxx/msg02892.html

> Really, this a serious regression for the people affected by this.

Can you send a patch adding a CAP_SYS_ADMIN exception?

-Kees

-- 
Kees Cook