Re: [PATCH v6 0/1] ns: introduce binfmt_misc namespace

From: Laurent Vivier <laurent@vivier.eu>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jann Horn <jannh@google.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	kernel list <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	containers@lists.linux-foundation.org, dima@arista.com,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v6 0/1] ns: introduce binfmt_misc namespace
Date: Thu, 29 Nov 2018 14:05:31 +0100	[thread overview]
Message-ID: <36933e07-d7b3-49be-4ad9-2028fa1977f7@vivier.eu> (raw)
In-Reply-To: <87zhusq3x7.fsf@xmission.com>

Le 01/11/2018 à 15:16, Eric W. Biederman a écrit :
> Laurent Vivier <laurent@vivier.eu> writes:
> 
>> On 01/11/2018 04:51, Jann Horn wrote:
>>> On Thu, Nov 1, 2018 at 3:59 AM James Bottomley
>>> <James.Bottomley@hansenpartnership.com> wrote:
>>>>
>>>> On Tue, 2018-10-16 at 11:52 +0200, Laurent Vivier wrote:
>>>>> Hi,
>>>>>
>>>>> Any comment on this last version?
>>>>>
>>>>> Any chance to be merged?
>>>>
>>>> I've got a use case for this:  I went to one of the Graphene talks in
>>>> Edinburgh and it struck me that we seem to keep reinventing the type of
>>>> sandboxing that qemu-user already does.  However if you want to do an
>>>> x86 on x86 sandbox, you can't currently use the binfmt_misc mechanism
>>>> because that has you running *every* binary on the system emulated.
>>>> Doing it per user namespace fixes this problem and allows us to at
>>>> least cut down on all the pointless duplication.
>>>
>>> Waaaaaait. What? qemu-user does not do "sandboxing". qemu-user makes
>>> your code slower and *LESS* secure. As far as I know, qemu-user is
>>> only intended for purposes like development and testing.
>>>
>>
>> I think the idea here is not to run qemu, but to use an interpreter
>> (something like gVisor) into a container to control the binaries
>> execution inside the container without using this interpreter on the
>> host itself (container and host shares the same binfmt_misc
>> magic/mask).
> 
> Please remind me of this patchset after the merge window is over, and if
> there are no issues I will take it via my user namespace branch.
> 
> Last I looked I had a concern that some of the permission check issues
> were being papered over by using override cred instead of fixing the
> deaper code.  Sometimes they are necessary but seeing work-arounds
> instead of fixes for problems tends to be a maintenance issue, possibly
> with security consequences.  Best is if the everyone agrees on how all
> of the interfaces work so their are no surprises.

I don't know where we are in the merge window, but is there something I
can do to have this merged?

Thanks,
Laurent