[Freeipa-devel] [PATCH 556-557] Add option to disable setkeytab extended operations

[Simo Sorce]

On Tue, 2015-12-01 at 16:44 +0100, Petr Vobornik wrote:
> On 12/01/2015 04:20 PM, Alexander Bokovoy wrote:
> > On Tue, 01 Dec 2015, Martin Kosek wrote:
> >> On 12/01/2015 02:59 PM, Simo Sorce wrote:
> >>> On Tue, 2015-12-01 at 14:42 +0100, Martin Kosek wrote:
> >>>> On 12/01/2015 02:38 PM, Simo Sorce wrote:
> >>>>> On Tue, 2015-12-01 at 10:11 +0200, Alexander Bokovoy wrote:
> >>>>>> On Mon, 30 Nov 2015, Simo Sorce wrote:
> >>>>>>> On Wed, 2015-11-25 at 09:47 -0500, Simo Sorce wrote:
> >>>>>>>> On Wed, 2015-11-25 at 09:02 -0500, Rob Crittenden wrote:
> >>>>>>>>> Jan Cholasta wrote:
> >>>>>>>>>> On 24.11.2015 22:17, Simo Sorce wrote:
> >>>>>>>>>>> On Tue, 2015-11-24 at 14:57 -0500, Simo Sorce wrote:
> >>>>>>>>>>>> On Tue, 2015-11-24 at 14:42 -0500, Simo Sorce wrote:
> >>>>>>>>>>>>> Since some time we use the getkeytab operation to fetch
> >>>>>>>>>>>>> keytabs on
> >>>>>>>>>>>>> newer
> >>>>>>>>>>>>> clients. According to bug #232 setkeytab can be used to
> >>>>>>>>>>>>> circumvent
> >>>>>>>>>>>>> password quality controls so it needs to be slowly retired.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> The attached patches implement #5485 in 2 parts.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> The first introduces the option DisableSetKeytab which
> >>>>>>>>>>>>> globally
> >>>>>>>>>>>>> disables
> >>>>>>>>>>>>> the setkeytab extended operation. This is set to false by
> >>>>>>>>>>>>> default for
> >>>>>>>>>>>>> backwards compatibility.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> The second introduces an option called
> >>>>>>>>>>>>> DisableUserSetKeytab, which is
> >>>>>>>>>>>>> active by default in new installs (but not in upgraded
> >>>>>>>>>>>>> ones), and only
> >>>>>>>>>>>>> disables the use of setkeytab for ipa suers, but not for
> >>>>>>>>>>>>> hosts/services.
> >>>>>>>>>>>>> This is because user's are the ones that may abuse the
> >>>>>>>>>>>>> interface to
> >>>>>>>>>>>>> escape password policies and users also normally do not
> >>>>>>>>>>>>> acquire
> >>>>>>>>>>>>> keytabs,
> >>>>>>>>>>>>> so it is a safe bet to disable just them by default in new
> >>>>>>>>>>>>> installs.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> (Testing in progress)
> >>>>>>>>>>>>
> >>>>>>>>>>>> Tested and working as expected.
> >>>>>>>>>>>
> >>>>>>>>>>> I realized that adding options to ipaConfig require to add
> >>>>>>>>>>> them in the
> >>>>>>>>>>> UI as well, attached patches add options in API.txt and
> >>>>>>>>>>> config.py
> >>>>>>>>>>> Make now complain I should change API Major or Minor, but it
> >>>>>>>>>>> is not
> >>>>>>>>>>> clear to me why given this are additional values and no real
> >>>>>>>>>>> change or
> >>>>>>>>>>> new function is introduced. What's the recommendation ?
> >>>>>>>>>>
> >>>>>>>>>> When does make complain? It is supposed to complain only when
> >>>>>>>>>> API.txt
> >>>>>>>>>> does not match code.
> >>>>>>>>>>
> >>>>>>>>>> Anyway, we usually bump minor version even for backward
> >>>>>>>>>> compatible
> >>>>>>>>>> changes, see e.g. commit 9549a59.
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> The point of API.txt (and the heavy client) was to save a
> >>>>>>>>> round-trip.
> >>>>>>>>> Being able to pass in an invalid option would void that rule hence
> >>>>>>>>> having to update the API when new values are added.
> >>>>>>>>>
> >>>>>>>>> rob
> >>>>>>>>
> >>>>>>>> Ok added version change to the second patch (so we bump it only
> >>>>>>>> once
> >>>>>>>> given these are basically related changes.
> >>>>>>>
> >>>>>>> Bump, is this ok ?
> >>>>>> This patch is fine but please fix setkeytab use in ipa-sam before
> >>>>>> committing this patch.
> >>>>>
> >>>>> This patch does not disable setkeytab yet, so it can go in right away
> >>>>> (it blocks other patches already). We have a bug to change ipa-sam,
> >>>>> should we mark it blocker for 4.4 ?
> >>>>
> >>>> We also have to fix the permission to change keytab, so that it uses
> >>>> the new
> >>>> style (https://fedorahosted.org/freeipa/ticket/5487). I would
> >>>> actually make
> >>>> this ticket and the ipa-sam ticket a blocker for this patch set.
> >>>>
> >>>> Otherwise you are actually introducing a switch that breaks FreeIPA
> >>>> as some of
> >>>> it's core server functions still use the old method.
> >>>
> >>> The point of this patchset is to introduce the switch early so that
> >>> current server will support the off switch when newer servers down the
> >>> road are ready to flip it. The defaults are still to allow these
> >>> operations for services/hosts.
> >>
> >> I still do not get the logic about an early switch. Now, if switch is
> >> turned
> >> on, FreeIPA server breaks on several places. I would really rather
> >> expect the
> >> switch to be introduced when the server itself supports it. Then,
> >> admin would
> >> enable it when the clients are sufficiently updated and can use the
> >> new method.
> >>
> >> Why would admin want to enable the switch early if it breaks FreeIPA
> >> some of
> >> the FreeIPA servers? Permission can be upgraded in newer version and get
> >> replicated, that's fine. But ipa-sam would be still broken on this old
> >> FreeIPA
> >> server.
> > Old server is not a problem here: ipa-sam only talks to the
> > localhost-based server as we always use ldapi protocol. So if server is
> > running old-behavior FreeIPA, ipa-sam on the same server will work
> > against it.
> >
> > What I don't want to have is a situation where setkeytab is disabled and
> > a new server obeys it but ipa-sam on this new server is not updated and
> > will expectedly fail. We are not that forced to do the change right now
> > in 4.3, given that the default will still be to keep setkeytab, thus we
> > can wait with this patch until ipa-sam is fixed and then push both
> > patches into the closest release, be it 4.3.x (x>=0) or whatever is the
> > next one.
> >
> 
> +1, fixing ipa-sam would be then a release blocker for 4.3 which is not 
> desired.
> 
> Also what about adding support for "ipaProtectedoperation check" for 
> user principals?
> 
> I'm afraid that forbidding getting user principal might be regarded as a 
> regression which might cause that admins won't set DisableSetKeytab.

One thing at a time.
We have bugs open for all these things, but I see no reason not to add
an *optional* setting just because some things break when it is turned
on.

Simo.

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