Messages in this thread | | | Date | Wed, 15 Jun 2022 09:37:59 +0200 | From | Christian Brauner <> | Subject | Re: [PATCH 1/2] fs/exec: allow to unshare a time namespace on vfork+exec |
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On Sun, Jun 12, 2022 at 11:07:22PM -0700, Andrei Vagin wrote: > Right now, a new process can't be forked in another time namespace > if it shares mm with its parent. It is prohibited, because each time > namespace has its own vvar page that is mapped into a process address > space. > > When a process calls exec, it gets a new mm and so it could be "legal" > to switch time namespace in that case. This was not implemented and > now if we want to do this, we need to add another clone flag to not > break backward compatibility. > > We don't have any user requests to switch times on exec except the > vfork+exec combination, so there is no reason to add a new clone flag. > As for vfork+exec, this should be safe to allow switching timens with > the current clone flag. Right now, vfork (CLONE_VFORK | CLONE_VM) fails > if a child is forked into another time namespace. With this change, > vfork creates a new process in parent's timens, and the following exec > does the actual switch to the target time namespace. > > Suggested-by: Florian Weimer <fweimer@redhat.com> > Signed-off-by: Andrei Vagin <avagin@gmail.com> > ---
Looks good, Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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