Open Stack

On Tue, May 22, 2018 at 5:27 AM, Cédric Jeanneret <cjeanner at redhat.com>
wrote:

>
>
> On 05/21/2018 03:49 PM, Luke Hinds wrote:
> > A few operators have requested if its possible to limit sudo's coverage
> > on both the under / overcloud. There is concern over `ALL=(ALL)
> > NOPASSWD:ALL` , which allows someone to  `sudo su`.
> >
> > This task has come under the care of the tripleo security squad.
> >
> > The work is being tracked and discussed here [0].
> >
> > So far it looks like the approach will be to use regexp within
> > /etc/sudoers.d/*., to narrow down as close as possible to the specific
> > commands called. Some services already do this with rootwrap:
> >
> > ironic ALL = (root) NOPASSWD: /usr/bin/ironic-rootwrap
> > /etc/ironic/rootwrap.conf *
> >
> > It's fairly easy to pick up a list of all sudo calls using a simple
> > script [1]
> >
> > The other prolific user of sudo is ansible / stack, for example:
> >
> > /bin/sh -c echo BECOME-SUCCESS-kldpbeueyodisjajjqthpafzadrncdff;
> > /usr/bin/python
> > /home/stack/.ansible/tmp/ansible-tmp-1526579105.0-
> 109863952786117/systemd.py;
> > rm -rf
> > "/home/stack/.ansible/tmp/ansible-tmp-1526579105.0-109863952786117/" >
> > /dev/null 2>&1
> >
> > My feelings here are to again use regexp around the immutable non random
> > parts of the command.  cjeanner also made some suggestions in the
> > etherpad [0].
>
> Might be a temporary way to limit the surface indeed, but an upstream
> change in Ansible would still be really nice. Predictable names is the
> only "right" way, although this will create a long sudo ruleset. A
> really long one to be honnest. Maintainability is also to be discussed
> in either way (maintain a couple of regexp vs 200+ rules.. hmmm).
>
>
As I understand it, the problem with predicable names is they also become
predictable to attackers (this would be the reason ansible adds in the
random string). It helps prevent someone creating a race condition to
replace the python script with something more nefarious. Its the same
reason commands such as mktemp exists.

>
> > However aside to the approach, we need to consider the impact locking
> > down might have should someone create a develop a new bit of code that
> > leverages commands wrapped in sudo and assumes ALL with be in place.
> > This of course will be blocked.
>
> This will indeed require some doc, as this is a "major" change. However,
> the use of regexp should somewhat limit the impact, especially since
> Ansible pushes its exec script in the same location.
> Even new parts should be allowed (that might be a bit of concern if we
> want to really dig in the consequences of a bad template being injected
> in some way [looking config-download ;)]).
> But at some point, we might also decide to let the OPs ensure their
> infra isn't compromised.
> Always the same thread-of with Security vs The World - convenience vs
> cumbersome management, and so on.
>
> >
> > Now my guess is that our CI would capture this as the deploy would
> > fail(?) and the developer should work out an entry is needed when
> > testing their patch, but wanted to open this up to others who know
> > testing at gate better much better than myself.  Also encourage any
> > thoughts on the topic to be introduced to the etherpad [0]
> >
> > [0] https://etherpad.openstack.org/p/tripleo-heat-admin-security
> > [1] https://gist.github.com/lukehinds/4cdb1bf4de526a049c51f05698b8b04f
> >
> > --
> > Luke Hinds
>
> --
> Cédric Jeanneret
> Software Engineer
> DFG:DF
>
>
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>


-- 
Luke Hinds | NFV Partner Engineering | CTO Office | Red Hat
e: lhinds at redhat.com | irc: lhinds @freenode | t: +44 12 52 36 2483
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