nsswitch: do not reload if "/" changes

[Carlos O'Donell]

On 1/18/21 11:53 AM, Florian Weimer wrote:
> * Carlos O'Donell via Libc-alpha:
> 
>> Can we create a non-test-container test for this?
>>
>> I think you can use support_become_root to unshare and then try
>> to use support_chroot_create/support_chroot_free and xhcroot to 
>> change root, and then try to do an NSS call that will fail?
> 
> You need to chroot twice, first to get a defined /etc/nsswitch.conf, and
> another one to make sure things don't ger reloaded after chroot.

That would be a perfect solution.

However, I think you could get away with recording some known uid/gid
from the system that was doing the build and then ensure that value
is not present in the container.

> You probably also have to copy different service modules into the two
> chroots.

Correct.

-- 
Cheers,
Carlos.