[Samba] Adding user to group doesn't propagate?

[Harald Hannelius]

On Mon, 31 Aug 2020, Jonathon Reinhart via samba wrote:
> On Mon, Aug 31, 2020 at 9:21 AM Harald Hannelius via samba
> <samba at lists.samba.org> wrote:
>> On Wed, 17 Jun 2020, Harald Hannelius wrote:
>>> On Wed, 17 Jun 2020, Harald Hannelius via samba wrote:
>>>> On Wed, 17 Jun 2020, Rowland penny via samba wrote:
>>>>> On 17/06/2020 11:54, Harald Hannelius wrote:
>>>>>> On Wed, 17 Jun 2020, Rowland penny via samba wrote:
>>>>>>> On 17/06/2020 11:39, Harald Hannelius via samba wrote:
>>>>>>
>>>>>> Sorry, You lost me here. Has this been discussed recently? I'm in the
>>>>>> middle of so many projects I haven't had time to sit and follow this list
>>>>>> as much as I'd like to.
>>>>> No, it hasn't been discussed before, it happened to myself a couple of
>>>>> weeks ago, I added the user to a group and 'id' didn't show the group,
>>>>> everything else showed the user was a group member. I just put it down to
>>>>> one of those things, but the following day, 'id' showed the group, so I
>>>>> think it must be a cache problem.
>>>>
>>>> I see.
>>>>
>>>> I just checked, and all other users who show up correctly in the new group
>>>> are indeed not logged on to the domain.
>>>>
>>>> Could it be that an active session locks the group memberships until the
>>>> user logs out and in again? This might even be exactly like Windows works
>>>> if I read correctly.
>>>>
>>>>>> I read somewhere that there's some caching going on, but there was no
>>>>>> real solution on how to purge this cache other than have the client log
>>>>>> out of their computer and on again. I have asked my colleague to do this,
>>>>>> so it might be that waiting until tomorrow won't work.
>>>>>
>>>>> I tried all that, it just worked the following day. The only thing I
>>>>> didn't do, raise the log level.
>>>>
>>>> Ok, I'll wait if the logout/login doesn't work.
>>>
>>> The user restarted their computer and presto: 'groups username' showed the
>>> new membership on the member-server.
>>
>> Googling a problem, and finding one's own e-mail thread as the first hit. I
>> had already forgot about this.
>>
>> Added a group on the DC, added two members to that group and at least on of
>> those are logged on to the domain. The group doesn't show up on a
>> member-server.
>>
>> I will probably have to wait until tomorrow before I'm able to use that
>> group?
>>
>> Are there plans to fix this so one can add groups and edit group
>> memberships faster?
>>
>
> I too have observed this.
>
> Network:
> - Two Samba DCs (4.9.5+dfsg-5+deb10u1)
> - File server:  FreeNAS-11.2-U7 (running Samba 4.9.15)
>
> My internal ticket notes:
>
> - I added `jdoe` to the `cost estimates` folder ACL, and he was able
> to see the `AAA` subdirectory immediately (because he was on that ACL
> already)
> - I added him to the `XXX Finance` group, and it had no effect
> - The NAS did not believe he was a member of that group:
>    root at nas[~]# id jdoe
>    uid=100041(jdoe) gid=100000(domain users) groups=100000(domain
>    users),100010(xxx program),100016(engineering),100025(aaa
>    program),90000002(BUILTIN\users)
> - I tried clicking `REBUILD DIRECTORY SERVICE CACHE` in the FreeNAS
> GUI and it had no effect
> - I ran `watch id jdoe` and as soon as he authenticated with the NAS
> (his machine is not yet joined) and hit enter, his membership changed
> on the NAS:
>    uid=100041(jdoe) gid=100000(domain users) groups=100000(domain
>    users),100010(xxx program),100016(engineering),100025(aaa
>    program),100031(xxx finance),90000002(BUILTIN\users)
>
> So apparently re-authenticating triggers group membership update... or
> something like that.
>
> How does a Windows server handle this?
>
> Resources:
> - https://www.ixsystems.com/community/threads/slow-updating-active-directory-user-group-cache.57448/
> - https://www.ixsystems.com/community/threads/permissions-cifs-wont-pull-user-or-group-from-the-network.46044/
> - https://www.ixsystems.com/community/threads/windows-users-groups-not-refreshing.28883/
> - https://www.ixsystems.com/community/threads/ad-group-memberships-wont-update.63404/
>
> Possibly related Samba source code:
> - wcache_invalidate_samlogon() [1] "Invalidate the getpwnam and
> getgroups entries for a winbindd domain": Called only from
>  - winbindd_dual_pam_auth
>  - winbind_dual_SamLogon
>
>
> [1]: https://gitlab.com/samba-team/samba/-/blob/03f79a3bd71bc7a0a401d5f19560e831251d32b7/source3/winbindd/winbindd_cache.c#L3056

Does anyone have any tips on how to circumvent this problem? I have 
almost daily group membership-changes, and sometimes waiting 24 hours isn't 
enough for the changes in a group to propagate.

I have tried to restart smbd, nmbd and winbindd on the member server to no 
avail. On the test-server that nobody uses the changes show up much much 
earlier.

Is there a way to check if a user is authenticated to the domain at the 
present moment, and then kick out the user?


-- 

Harald Hannelius | harald.hannelius/a\arcada.fi | +358 50 594 1020