From: Gao feng <gaofeng@cn•fujitsu.com>
To: "Eric W. Biederman" <ebiederm@xmission•com>
Cc: netdev@vger•kernel.org, systemd-devel@lists•freedesktop.org,
lxc-devel@lists•sourceforge.net, davem@davemloft•net,
Linux Containers <containers@lists•linux-foundation.org>,
"libvir-list@redhat•com" <libvir-list@redhat•com>
Subject: Re: [PATCH] netns: unix: only allow to find out unix socket in same net namespace
Date: Wed, 21 Aug 2013 15:22:42 +0800 [thread overview]
Message-ID: <52146AC2.5070409@cn.fujitsu.com> (raw)
In-Reply-To: <87wqnfttdf.fsf@xmission.com>
On 08/21/2013 03:06 PM, Eric W. Biederman wrote:
> Gao feng <gaofeng@cn•fujitsu.com> writes:
>
>> cc libvirt-list
>>
>> On 08/21/2013 01:30 PM, Eric W. Biederman wrote:
>>> Gao feng <gaofeng@cn•fujitsu.com> writes:
>>>
>>>> Unix sockets are private resources of net namespace,
>>>> allowing one net namespace to access to other netns's unix
>>>> sockets is meaningless.
>>>
>>> Allowing one net namespace to access another netns's unix socket is
>>> deliberate behavior. This is a desired and useful feature, and
>>> only a misconfiguration of visible files would allow this to be a
>>> problem.
>>>
>>>> I'm researching a problem about shutdown from container,
>>>> if the cotainer shares the same file /run/systemd/private
>>>> with host, when we run shutdown -h xxx in container, the
>>>> shutdown message will be send to the systemd-shutdownd
>>>> through unix socket /run/systemd/private, and because
>>>> systemd-shutdownd is running in host, so finally, the host
>>>> will become shutdown.
>>>
>>> The simple answer is don't do that then. I can see no reason
>>> to share /run outside of the container unless you want this kind of
>>> behavior.
>>>
>>> Quite frankly I want this behavior if I am using network namespaces
>>> to support multiple routing contexts. That is if I am using scripts
>>> like:
>>>
>>> ip netns add other
>>> ip netns exec other script
>>>
>>> I don't want to have to remember to say
>>> ip netns orig exec shutdown -h now
>>>
>>> There are more compelling uses and there is no cost in supporting this
>>> in the kernel.
>>>
>>> What kind of misconfiguration caused someone to complain about this?
>>>
>>
>> libvirt lxc allows user to set up a container which shares the same root
>> directory with host.
>>
>> seems like the unix sockets whose sun_path is an abstract socket address
>> are net namespace aware.
>>
>> Should we use "abstract" type of address instead of a file system pathname
>> for systemd in this case?
>
> I suspect libvirt should simply not share /run or any other normally
> writable directory with the host. Sharing /run /var/run or even /tmp
> seems extremely dubious if you want some kind of containment, and
> without strange things spilling through.
>
right now I only take note of the unix socket /run/systemd/private,
but there may have many similar unix sockets, they can exist in any
path. the strange problems will still happen.
anyway, I will send a patch to setup a fresh tmpfs for the /run directory of
container first.
Eric, Thanks for your help!
next prev parent reply other threads:[~2013-08-21 7:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-21 4:31 [PATCH] netns: unix: only allow to find out unix socket in same net namespace Gao feng
[not found] ` <1377059473-25526-1-git-send-email-gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-08-21 4:58 ` Gao feng
2013-08-21 5:30 ` Eric W. Biederman
[not found] ` <87d2p7vcdx.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-08-21 6:54 ` Gao feng
[not found] ` <5214641C.9030902-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-08-21 7:06 ` Eric W. Biederman
2013-08-21 7:22 ` Gao feng [this message]
[not found] ` <52146AC2.5070409-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-08-21 9:51 ` [systemd-devel] " Kay Sievers
[not found] ` <CAPXgP120YUEVnFiD0uPnqeO4x=5oRvHL79-cX5CnmEWc3d5mvQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-08-21 9:56 ` Daniel P. Berrange
2013-08-25 17:16 ` James Bottomley
2013-08-25 17:37 ` Kay Sievers
[not found] ` <CAPXgP115pEE8jxyCqauoMRWui3Qb0fBzPr9L2_SA411=gfnX3w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-08-25 18:16 ` James Bottomley
2013-08-26 1:06 ` Gao feng
[not found] ` <521AAA23.9050604-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-08-26 3:19 ` James Bottomley
2013-08-26 3:35 ` Gao feng
[not found] ` <521ACCEF.4050101-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-08-26 3:53 ` James Bottomley
2013-08-26 13:53 ` Serge Hallyn
2013-08-21 10:42 ` Eric W. Biederman
2013-08-22 1:36 ` Gao feng
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