[Pkg-samba-maint] Bug#848935: Bug#848935: Bug#848935: libnss-winbind: winbind authentication and wbinfo --uid-info no longer work after uprading to 4.5.2+dfsg-1

[Stéphane Pgt]

> Unfortunately I wasn't able to reproduce the problem after downgrading to
> 4.5.2+dfsg-2.
> I then tried starting from a fresh install of 4.5.2+dfsg-1 (with current
> version of base system and dependencies) but again, the problem no longer
> appears.
> If necessary, I can retrieve at a later time a snapshot of the virtual
> machine on which I was able to reproduce the problem two weeks ago.

I first restored the snapshot from December, 21th 2016, when I reproduced
the problem.
Surprisingly, the problem was not there anymore, the mapped UID all were in
the configured range.

I then restored the same snapshot again and set the BIOS date and time to the
time at which the VM was last powered off (2016-12-21 00:19:15 CET) before
booting the OS.
This time, I was able to reproduce:

root at v-smb-fs:~# getent passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
<snip>
administrator:*:100500:100513:Administrator:/data/administrator:/bin/false
testusr:*:101103:100513:testusr:/data/testusr:/bin/false
krbtgt:*:100502:100513:krbtgt:/data/krbtgt:/bin/false
guest:*:100501:100514:Guest:/data/guest:/bin/false

root at v-smb-fs:~# wbinfo --user-info testusr
testusr:*:101103:100513:testusr:/data/testusr:/bin/false

root at v-smb-fs:~# wbinfo --uid-info 101103
failed to call wbcGetpwuid: WBC_ERR_DOMAIN_NOT_FOUND
Could not get info for uid 101103

Which may highlight, as you suggested, a caching issue.

At this point, without upgrading nor restarting anything, if I simply flush
the winbind cache, the mapped UID are now in the correct range, and the
issue goes away:

root at v-smb-fs:~# net cache flush

root at v-smb-fs:~# getent passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
<snip>
administrator:*:10000:10003:Administrator:/data/administrator:/bin/false
testusr:*:10001:10003:testusr:/data/testusr:/bin/false
krbtgt:*:10002:10003:krbtgt:/data/krbtgt:/bin/false
guest:*:10003:10004:Guest:/data/guest:/bin/false

root at v-smb-fs:~# wbinfo --user-info testusr
testusr:*:10001:10003:testusr:/data/testusr:/bin/false

root at v-smb-fs:~# wbinfo --uid-info 10001
testusr:*:10001:10003:testusr:/data/testusr:/bin/false

If you are interested, I could share some files or a complete archive of the
VM on which the problem was reproduced.
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