[PVE-User] UIDs > 65535 not valid in container

[Frank Thommen]

Dear all,

we have a strange issue with a CentOS 7 container running on PVE 6.1-3, 
that UIDs > 65535 are invalid.  The container is used as a "SSH 
jumphost" to access a special network: Users log in to the host and SSH 
to the special network from there. sssd is running in the container. The 
directory service is an Active Directory.

However users with UID > 65535 cannot login:

/var/log/secure:
[...]
Mar 12 13:48:32 XXXXXX sshd[1021]: fatal: seteuid 86544: Invalid argument
[...]


and chown isn't possible either:

$ chown 65535 /home/test
$ chown 65536 /home/test
chown: changing ownership of ‘/home/test’: Invalid argument
$


There are no problems with such UIDs on any other systems and there is 
no problem with users with an UID <= 65535 within the container.  I fear 
this might be a container-related issue but I don't understand it and I 
don't know if there is a solution or a workaround.

Any help or hint is highly appreciated

Frank