Joshua Brindle wrote:
Andi Kleen wrote:
On Monday 24 April 2006 15:11, Joshua Brindle wrote:
Sure but if, instead, it's able to open /var/chroot/etc/shadow which
is a hardlink to /etc/shadow you've bought nothing. You may filter
out worms and script kiddies this way but in the end you are using
obscurity (of filesystem layout, what the policy allows, how the
apps are configured, etc) for security, which again, leads to a
false sense of security.
AppArmor disallows both chroot and name space changes for the
constrained
application so the scenario you're describing cannot happen. What
happens
with unconstrained applications it doesn't care about by design.
This has been covered several times in this thread already - please pay
more attention.
I was paying attention, thank you. Can apparmor force an application
to only start within a certain chroot? So it may not be able to chroot
during runtime but if you can't be sure that it starts in the chroot
the argument still applies. Particularly since the app may not even
fail to run outside the chroot given that it will have access to all
the same libraries, etc it did inside (due to the paths being the same).
To make this much more real, the /usr/sbin/named policy that ships with
apparmor has the following line:
/** r,
Thats right, named can read any file on the system, I suppose this is
because the policy relies on named being chrooted. So if for any reason
named doesn't chroot its been granted read access on the entire
filesystem. If I'm misunderstanding this policy please correct me but I
believe this shows the problem very loudly and clearly.
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