[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 03 May 2022 00:56:24 +0300
From: Alexey Izbyshev <izbyshev@...ras.ru>
To: musl@...ts.openwall.com
Cc: Florian Weimer <fweimer@...hat.com>, Rich Felker <dalias@...c.org>,
Andrei Vagin <avagin@...il.com>, Christian Brauner <brauner@...nel.org>
Subject: Re: vfork()-based posix_spawn() has more failure modes than
fork()-based one
On 2022-05-03 00:49, Alexey Izbyshev wrote:
> On 2022-05-03 00:31, Carlos O'Donell wrote:
>> On 5/2/22 17:25, Florian Weimer wrote:
>>> * Rich Felker:
>>>
>>>> I'm trying to understand how this comes to be. The child should
>>>> inherit the namespaces of the parent and thus should not be in a
>>>> different namespace that precludes spawn. I'm guessing this is some
>>>> oddity where unshare doesn't affect the process itself, only its
>>>> children? If so, it seems like a bug that it doesn't affect the
>>>> process itself after execve (after unshare(1) runs your test
>>>> program),
>>>> but that probably can't be fixed now on the Linux side for stability
>>>> reasons. :(
>>>
>>> It's about fundamentally conflicting requirements.
>>>
>>> The vDSO data mapping needs to store the time offset, so it has to be
>>> distinct from the original namespace. vfork preserves the VM
>>> sharing.
>>> It's not possible to do both things at the same time.
>>>
>>> unshare(CLONE_NEWTIME) should have been specified to only take effect
>>> after execve, when the vDSO is remapped anyway.
>>
>> Can we ask some kernel developers for an opinion?
>
> Christian Brauner had some comments [1,2] on this. Time namespaces
> were added in [3] by Andrei Vagin. Adding both to CC.
>
(Trying a different email for Andrei Vagin)
> Alexey
>
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=215769#c6
> [2] https://bugzilla.kernel.org/show_bug.cgi?id=215769#c10
> [3]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=769071ac9f20b6a447410c7eaa55d1a5233ef40c
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
