XACE performance data, fixed XACE patch

[Roland Mainz]

Bryan Ericson wrote:
> I've run some performance tests using x11perf on the XACE security
> framework.  The tests indicate that, in general, XACE does not
> severely impact server performance.
[snip]
> Additionally, the test turned up a bug in the XACE patch involving a
> few places where "#ifdef XCSECURITY" should have been replaced with
> "#ifdef XACE".  The following patch corrects the problem, and
> supersedes the previous XACE patch.  The XSELINUX patch is not
> affected by the new XACE patch.
> 
> http://dgoeddel.home.insightbb.com/xorg-x11-6.8.2.xace.patch2

Just some thoughts (I just quickly looked over the patch without
picking-up all details):
- Does "xauth"'s "generate" command still work (please read
https://bugs.freedesktop.org/show_bug.cgi?id=2606#c4) ?
- You can "censor" XGetImage() requests - but what happens if someone
tries to do a XCopyArea()/XCopyPlane() from a trusted window/pixmap to
an untrusted window/pixmap and then calls XGetImage() on the untrusted
version ?
- Some extensions may need extra handling - GLX (where some OpenGL
extensions may allow copying of window data), Xprint's XpExtension (you
may want to restrict access to single printers (like those which sits in
a unsecure/public area (this wouldn't be the first case that confidetial
data leave the building just because someone selected the wrong printer
=:-))) and others come ad-hoc in my mind. A general accept/reject filter
for extensions may be usefull here, maybe even used together with the
XC-APPGROUP extensions (e.g. untrusted applications then could live in
their own XC-APPGROUP group (think about something like a *BSD "jail")
where they can't disturb applications in other groups)
- (This is likely Solaris-only): XReadScreen() needs to be wrapped, too
- Just curious: How does XACE compare to extensions such as Xserver
additions in "Trusted Solaris" (see
http://docs.sun.com/app/docs/doc/835-8004/6ruu29hk4?q=trusted+solaris+xsun&a=view
... maybe Alan Coopersmith has a better link which describes the details
better... :) ?

----

Bye,
Roland

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