the user space object manager code seems to fragile

[Dominick Grift <dac.override@gmail.com>]

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I want to bring to your attention that the user space object manager
functionality/code of selinux is fragile and is a challenge

Why now? Now fundamental components of GNU/Linux are user space
object managers (systemd) and some other components that were already
user space object managers for years became fundamental components in
GNU/Linux (dbus)

Some small fragments from a systemd.conf youtube video

https://www.youtube.com/watch?v=kUWvSXEHMhU&feature=youtu.be&t=580
https://www.youtube.com/watch?v=kUWvSXEHMhU&feature=youtu.be&t=1137

I already have been experiencing strange behavior with user space
object managers many times.

For example, on one system i have, it works inconsistently (i have to boot
the system multiple times to get the systemd and/or dbus user space
object manager to work)

Just today i hit another such issue when i tested the CIL unordered
class functionality

It seems to work fine in some cases, and in other cases it doesnt work at
all (even in permissive mode!?)

The access vectors are in the policy but for some reason the components
are confused.

To reproduce: install a fedora23 minimal server, add yourself to the
wheel group and run this script:

https://raw.githubusercontent.com/DefenSec/selinux-rpm-spec/master/scripts/dsspbase23

what it does is it installs my dssp policy with only the base. since the
dbus access vector was relocated from base to dbus.cil it is not present
in the this policy.

The policy denies unknown access vectors by default, thus i added
the dbus access vector declaration to the base.cil addon module (a
separate module to make the sole process context "unconfined")

The access vector ends up in the policy however, dbus gets confused
for some reason, and since for example firewalld wants dbus, that fails
and systemd freezes ( i suppose that may be some kind of security
feature ).

The user space object manager code should be made more robust, and/or it
should be better documented because clearly developers have a very hard
time using it properly.

The decision to support user space object managers was made long ago, but
in my view it was never really carefully thought out, or received the
attention it deserves.

The fact that we only just now support unordered access vector
declarations proves the above point I believe.

It is a fundamental requirement for this functionality.

Thank you for reading

(p.s. this is not about unordered access vectors, that was just one
example. this is about libselinux/user space object managers)

- -- 
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Dominick Grift
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