[PATCH xinit 2/2] startx: Make startx auto display select work with per user /tmp dirs

[Ray Strode]

Hi,

> Now, I've tried to avoid anything xauth-related, but from the little I know:
> to support displayfd in startx you'd have to communicate back to startx
> about the $DISPLAY and do the xauth dance before continuing with the xinit
> initial client connection. AFAICT, that's the tricky bit about -displayfd
> support in startx. Does that make sense or am I way off here?
Sending $DISPLAY back to startx isn't actually an option since, $DISPLAY comes
from the X server, and the auth file has to be prepared before
starting the X server.
If you start the X server without the auth file then the X server will
get started wide
open to anyone on the host. Sure you could lock it down at that point,
but then there's
a race where anyone could open the display and snoop from then on.

The two ideas I proposed in my other mail are the only secure ways I
can think to
go forward. Either:

1) Have xinit write out the auth file itself (with the $DISPLAY wildcard)
or
2) Fix /usr/bin/xauth to allow adding a $DISPLAY wildcard and change startx to
use the wildcard.

--Ray