[Freeipa-devel] [DESIGN][UPDATE] Time-Based HBAC Policies

[Simo Sorce]

On Fri, 2016-08-26 at 18:09 +0300, Alexander Bokovoy wrote:
> On Fri, 26 Aug 2016, Simo Sorce wrote:
> >On Fri, 2016-08-26 at 12:39 +0200, Martin Basti wrote:
> >> > I miss "why" part of "To be able to handle backward compatibility
> >> with
> >> > ease, a new object called ipaHBACRulev2 is introduced. " in the
> >> design
> >> > page. If the reason is the above - old client's should ignore time
> >> rules
> >> > then it has to be mentioned there. Otherwise I don't see a reason to
> >> > introduce a new object type instead of extending the current.
> >>
> >> How do you want to enforce HBAC rule that have set time from 10 to 14
> >> everyday? With the same objectclass old clients will allow this HBAC
> >> for
> >> all day. Isn't this CVE?
> >
> >This is a discussion worth having.
> >
> >In general it is a CVE only if an authorization mechanism fails to work
> >as advertised.
> >
> >If you make it clear that old clients *DO NOT* respect time rules then
> >there is no CVE material, it is working as "described".
> >
> >The admins already have a way to not set those rules for older clients
> >by simply grouping newer clients in a different host group and applying
> >time rules only there.
> >
> >So the question really is: should we allow admins to apply an HBAC Rule
> >potentially to older clients that do not understand it and will
> >therefore allow access at any time of the day, or should we prevent it ?
> >
> >This is a hard question to answer and can go both ways.
> >
> >A time rule may be something that admins want to enforce at all cost or
> >deny access. In this case a client that fails to handle it would be a
> >problem.
> >
> >But it may be something that is just used for defense in depth and not a
> >strictly hard requirement. In this case allowing older clients would
> >make it an easy transition as you just set up the rule and the client
> >will start enforcing the time when it is upgraded but work otherwise
> >with the same rules.
> >
> >I am a bit conflicted on trying to decide what scenario we should
> >target, but the second one appeals to me because host groups do already
> >give admins a good way to apply rules to a specific set of hosts and
> >exclude old clients w/o us making it a hard rule.
> >OTOH if an admin does not understand this difference, they may be
> >surprised to find out there are clients that do not honor it.
> >
> >Perhaps we could find a way to set a flag on the rule such that when set
> >(and only when set) older clients get excluded by way of changing the
> >objectlass or something else to similar effect.
> >
> >Open to discussion.
> At this point using new object class becomes an attractive approach. We
> don't have means to exclude HBAC rules other than applying them
> per-host/hostgroup. We also have no deny rules.
> 
> I have another idea: what about enforcing time rules always to apply
> per-host or per-hostgroup by default? Add --force option to override the
> behavior but default to not allow --hostcat=all. This would raise
> awareness and make sure admins are actually applying these rules with
> intention.

This sounds like a good idea, but it is not a silver bullet I am afraid.

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York