linux-kernel - Re: Potentially undesirable interactions between vfork() and time namespaces

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Message-ID: <YxI9PbdWsCmJe1Pz@gmail.com>
Date:   Fri, 2 Sep 2022 10:28:29 -0700
From:   Andrei Vagin <avagin@...il.com>
To:     Alexey Izbyshev <izbyshev@...ras.ru>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Florian Weimer <fweimer@...hat.com>,
        Christian Brauner <brauner@...nel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: Potentially undesirable interactions between vfork() and time
 namespaces

On Fri, Sep 02, 2022 at 08:01:57PM +0300, Alexey Izbyshev wrote:
> On 2022-09-01 21:11, Eric W. Biederman wrote:

<snip>

> >  static int check_setns_flags(unsigned long flags)
> >  {
> >  	if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> > 
> > 
> > 
> > To keep things from being too confusing it probably makes sense to
> > rename the nsproxy variable from time_ns_for_children to
> > time_ns_for_new_mm.  Likewise timens_on_fork can be renamed
> > timens_on_new_mm.
> > 
> Do you imply renaming "/proc/[pid]/ns/time_for_children" as well, or will it
> be preserved for compatibility?

I don't think this is possible. It is used by a few tools already.