Re: [PATCH v4 0/3] Linux: Fix posix_spawn when user with time namespaces

[Alexey Izbyshev <izbyshev@ispras.ru>]

On 2022-05-11 12:21, Christian Brauner wrote:
> On Tue, May 10, 2022 at 09:18:46PM +0200, Florian Weimer wrote:
>> * Adhemerval Zanella:
>> 
>> > The patchset adds some support to tests the fallback code to
>> > use only use CLONE_VFORK.  It uses unshare directly because
>> > it simpler than add container support.
>> >
>> > Adhemerval Zanella (3):
>> >   linux: Add CLONE_NEWTIME from Linux 5.6 to bits/sched.h
>> >   support: Add support_enter_time_namespace
>> >   linux: Add fallback for clone failure on posix_spawn (BZ #29115)
>> 
>> Christan, how likely is it that we'd get another time namespace 
>> variant
>> that would only become effective after execve (when the DSO is 
>> remapped
>> anyway)?
> 
> Not unlikely if it helps you avoid a lot of complexity. I will need 
> some
> time to track down Andrei and others to discuss though.
> 
A more general question is whether the kernel aims to maintain the 
property that vfork() can always be used in place of fork() in the 
future. If it doesn't, code that currently relies on vfork() (even 
unwittingly via high-level APIs like posix_spawn()) will still have to 
grow workarounds.

Thanks,
Alexey