X security query

[Thomi Richards]

Hi,


I'm trying to write an application that runs as a daemon and monitors
running X sessions. Right now I'm struggling to find documentation
regarding the X security model. Specifically, I'm attempting to
connect to running X displays from my daemon process. Calling
"XOpenDisplay(dispName)" doesn't work, I guess because my process
doesn't have permission to connect to this display. After a bit of
research, it looks like I need to do something with xauth.

In my test environment, the X server is started like this:

/usr/bin/X -br -nolisten tcp :0 vt7 -auth /var/run/xauth/A:0-QBEVDj

That file contains a single entry, that looks like this:

#ffff##:  MIT-MAGIC-COOKIE-1  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX


by adding an entry to ~/.Xauthority with the same hex key, I can
connect to the X server. However, this is difficult because I need to
programmatically find the auth file the X server is using (the
location of which I guess will change from distro to distro, and
probably from one boot to the next), then query it, then write a new
auth file. If the process is running as a daemon, it might not have a
home directory, so how do I know where to write the new entries to?

Ideally, what I'm looking for is a way to bypass the need to have the
xauth cookie in ~/.Xauthority, or even to know what the cookie is at
all. I realise that this is unlikely - what good is a security model
if it's easily bypassed? but I'm hoping someone on this list may have
a few good ideas. Is there a way to specify that my process is
privileged and thus should automatically be given access to any
display on the local machine?


Cheers,