That is definitely an issue with 9.2 as I had 9.1 before with no problem at all

пн, 15 мая 2023 г. в 20:08, Sam Morris via FreeIPA-users
<[email protected]>:
>
> On Mon, May 15, 2023 at 09:28:22AM +0300, Alexander Bokovoy via FreeIPA-users 
> wrote:
> > On su, 14 touko 2023, Sam Morris wrote:
> > > On Fri, May 12, 2023 at 06:19:44PM +0100, Sam Morris via FreeIPA-users 
> > > wrote:
> > > > I wonder about the root cause; is this because MIT Kerberos 1.20 always
> > > > wants to include a PAC in its issued TGTs, and it gives up if it can't
> > > > retrieve a user's SID from the directory? (If so I wonder if setting
> > > > disable_pac = true in the realm section of krb5.conf would have worked
> > > > around the problem?)
> > >
> > > This seems to be the case. Specifically I:
> > >
> > > 1. Removed the ipantsecurityidentifier attribute from a user, and
> > >    removed ipantuserattrs from the user's objectclass
> > > 2. Tried to log in as the user & got the same failures + 'No such file
> > >    or directory' message in /var/log/krb5kdc.log
> > > 3. Edited /var/kerberos/krb5kdc/kdc.conf, adding 'disable_pac = true'
> > >    within the realm-specific configuration in the realms section
> > > 4. Restarted krb5kdc
> > > 5. Tried to log in as the user and it worked!
> > >
> > > The docs for disable_pac say:
> > >
> > >    If true, the KDC will not issue PACs for this realm, and S4U2Self
> > >    and S4U2Proxy operations will be disabled.  The default is false,
> > >    which will permit the KDC to issue PACs.  New in release 1.20.
> > >
> > > ... which doesn't explain that if the KDC can't issue a PAC for some
> > > reason then the KDC will fail to issue the TGT. But at least I've gotten
> > > to the bottom of things now. :)
> >
> > RHEL IdM documentation has a separate chapter related to it.
> >
> > RHEL 9:
> > https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/managing_idm_users_groups_hosts_and_access_control_rules/assembly_strengthening-kerberos-security-with-pac-information_managing-users-groups-hosts
> >
> > RHEL 8:
> > https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_idm_users_groups_hosts_and_access_control_rules/assembly_strengthening-kerberos-security-with-pac-information_managing-users-groups-hosts
> >
> > This documentation is in place since summer 2022.
>
> Brilliant. It's interesting that the docs say "As of RHEL 8.6, Kerberos
> in IdM requires that your IdM objects have SIDs, which are necessary for
> security based on Privilege Access Certificate (PAC) information.", but
> I had no problems with authentication on my RHEL 8.6/8.7 servers...
>
> > > > "After upgrading, krb5kdc may fail to issue TGTs to users who have not
> > > > had a SID assigned to their accounts ('ipa user-show user --all' will
> > > > not include an ipantsecurityidentifier attribute). In this case
> > > > krb5kdc.log will log a message "HANDLE_AUTHDATA: [email protected] for
> > > > krbtgt/[email protected], No such file or directory". This can be
> > > > fixed by running 'ipa config-mod --enable-sid --add-sids' as an IPA
> > > > admin on another IPA server."
> > >
> > > ... "or on the same server after temporarily setting "disable_pac =
> > > true" in kdc.conf, and restarting krb5kdc."
> >
> > You should not be disabling PAC because you are really setting yourself
> > up to an attack with a known exploit out in a wild.
>
> Absolutely--I just wanted to document what I'd found out, because there
> isn't a clear connection documented between the behaviour in RHEL 9.2
> with MIT Kerberos 1.20 and the behaviour seen when your IPA users don't
> have SIDs assigned.
>
> --
> Sam Morris <https://robots.org.uk/>
> PGP: rsa4096/CAAA AA1A CA69 A83A 892B  1855 D20B 4202 5CDA 27B9
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