Re: [PATCH] Restrict access to TIOCLINUX

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Apr 02, 2023 at 07:16:52PM +0200, Hanno Böck wrote:
> On Sun, 2 Apr 2023 16:55:01 +0200
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > You just now broke any normal user programs that required this (or the
> > other ioctls), and so you are going to have to force them to be run
> > with CAP_SYS_ADMIN permissions? 
> 
> Are you aware of such normal user programs?
> It was my impression that this is a relatively obscure feature and gpm
> is pretty much the only tool using it.

"Pretty much" does not mean "none" :(

> > And you didn't change anything for programs like gpm that already had
> > root permission (and shouldn't that permission be dropped anyway?)
> 
> Well, you could restrict all that to a specific capability. However, it
> is my understanding that the existing capability system is limited in
> the number of capabilities and new ones should only be introduced in
> rare cases. It does not seem a feature probably few people use anyway
> deserves a new capability.

I did not suggest that a new capability be created for this, that would
be an abust of the capability levels for sure.

> Do you have other proposals how to fix this issue? One could introduce
> an option like for TIOCSTI that allows disabling selection features by
> default.

What exact issue are you trying to fix here?

thanks,

greg k-h