lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 25 Apr 2014 14:17:46 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	"Serge E. Hallyn" <serge@...onical.com>,
	Linux Containers <containers@...ts.linux-foundation.org>
Subject: Re: pid ns feature request

Andy Lutomirski <luto@...capital.net> writes:

> On Fri, Apr 25, 2014 at 1:25 PM, Eric W. Biederman
> <ebiederm@...ssion.com> wrote:
>> Andy Lutomirski <luto@...capital.net> writes:
>>
>>> On Fri, Apr 25, 2014 at 12:37 PM, Eric W. Biederman
>>> <ebiederm@...ssion.com> wrote:
>>>> Andy Lutomirski <luto@...capital.net> writes:
>>>>
>>>>> Unless I'm missing some trick, it's currently rather painful to mount
>>>>> a namespace /proc.  You have to actually be in the pid namespace to
>>>>> mount the correct /proc instance, and you can't unmount the old /proc
>>>>> until you've mounted the new /proc.  This means that you have to fork
>>>>> into the new pid namespace before you can finish setting it up.
>>>>
>>>> Yes.  You have to be inside just about all namespaces before you can
>>>> finish setting them up.
>>>>
>>>> I don't know the context in which needed to be inside the pid namespace
>>>> is a burden.
>>>
>>> I'm trying to sandbox myself.  I unshare everything, setup up new
>>> mounts, pivot_root, umount the old stuff, fork, and wait around for
>>> the child to finish.
>>>
>>> This doesn't work: the parent can't mount the new /proc, and the child
>>> can't either because it's too late.
>>>
>>> The only solution I can think of without kernel changes is to fork the
>>> child (pid 1) before pivot_root, which makes everything more
>>> complicated.  I suppose I can unshare, fork immediately, have the
>>> child set up all the mounts, and then wake the parent, but this is an
>>> annoying bit of extra complexity for no obvious gain.
>>
>> Or perhaps just use clone and clone flags.
>>
>> What are you doing with the parent process?  What value does it serve?
>
> I'm not entirely sure.  I'm hacking on this thing:
>
> https://github.com/amluto/sandstorm/tree/userns
>
> which isn't really my code.  But there's an inner sandbox and an outer
> sandbox, and only the inner sandbox is in a pid namespace.
>
> I suppose what what I'm doing is a bit strange.

A bit.   But doing strange things is good.

Right now most of my energy is focused on closely the last of the design
issues.  So I don't have much energy for new namespace related features
right now.

Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ