Re: Privileged File Access from Desktop Applications

["Perry E. Metzger" <perry () piermont com>]

On Thu, 11 Jul 2019 21:20:15 +0100 Simon McVittie <smcv () debian org>
wrote:
> On Thu, 11 Jul 2019 at 11:47:10 -0400, Perry E. Metzger wrote:
> > having to add file i/o subsystems inside of dbus(!) probably does
> > add lots of threats  
>
> I think you might be misunderstanding the scope of D-Bus.

Not really. The whole point is that instead of having the operating
system alone as part of your file security implementation you now
have a brand new service, an IPC mechanism, and loads of other stuff,
instead of having your app just do open(2) and write(2) etc.

It seems architecturally bad from a security perspective. The number
the number of trusted entities, the number of moving parts, the number
of mechanisms, and thus the number of ways things can go wrong keeps
going up. This is a mistake. And btw, this is a major piece of
mechanism being added just to handle the problem of someone wanting to
pop open an editor inside a GUI to edit a system config file, which is
not a major attack vector. But, now I have to worry about this new
file access service providing an attack surface that didn't exist
before.

What's the right way to handle this stuff? Capabilities,
probably. It's what they're designed for.

Perry
-- 
Perry E. Metzger                perry () piermont com