From: David Lamparter <equinox@diac24.net>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: David Lamparter <equinox@diac24.net>,
linux-kernel@vger.kernel.org,
Linux Containers <containers@lists.osdl.org>,
netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, jamal <hadi@cyberus.ca>,
Daniel Lezcano <daniel.lezcano@free.fr>,
Linus Torvalds <torvalds@linux-foundation.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Ulrich Drepper <drepper@gmail.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
David Miller <davem@davemloft.net>,
"Serge E. Hallyn" <serge@hallyn.com>,
Pavel Emelyanov <xemul@openvz.org>,
Pavel Emelyanov <xemul@parallels.com>,
Ben Greear <greearb@candelatech.com>,
Matt Helsley <matthltc@us.ibm.com>,
Jonathan Corbet <corbet@lwn.net>,
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
Jan Engelhardt <jengelh@medozas.de>,
Patrick McHardy <kaber@trash.net>
Subject: Re: [ABI REVIEW][PATCH 0/8] Namespace file descriptors
Date: Thu, 23 Sep 2010 18:49:44 +0200 [thread overview]
Message-ID: <20100923164944.GA1202237@jupiter.n2.diac24.net> (raw)
In-Reply-To: <m11v8kh142.fsf@fess.ebiederm.org>
On Thu, Sep 23, 2010 at 09:32:29AM -0700, Eric W. Biederman wrote:
> > At several occasions, I was left with either some runaway daemon which
> > kept the namespace alive. To describe this a little more graphically:
> > I found no other way than doing a
> > md5sum /proc/*/net/if_inet6 | sort | uniq -c -w 32
> > to find out which runaway to kill to terminate the namespace.
> >
> > This makes network namespaces particularly cumbersome to use without PID
> > namespaces. While I agree that a large part of the users - namely lxc -
> > will use them together, network namespaces without pidns are very
> > interesting for routing applications implementing VRFs.
> >
> > Is it possible to add some kind of "all namespaces" list, optimally
> > giving an opportunity to open() exactly this file descriptor that you
> > get from /proc/<pid>/ns/net?
> >
> > Also, is it possible to extend that file descriptor to have an
> > "get all pids" ioctl,
> > ...or, wait, maybe have /proc/...ns/proc/<pid> symlink?
> >
> > (This obviously isn't fully thought to the end, please pick up...)
>
> Maybe. I can understand the pain.
>
> Is the problem you are facing you are shutting down a vrf and you want
> to make certain nothing is using it any longer?
Hrm. There are 2 and a half problems i can describe:
1) identifying namespaces. You can walk over /proc just fine and look at
all processes namespaces, but you don't know which are actually the
same aside from looking at some entry like if_inet6. There is no
identifier and no easy equality match. (As far as i can tell.)
Bonus difficulty: your patch will allow namespaces that have no
process attached to them anymore since they only exist as files.
Those will be invisible to someone running through /proc. Which leads
to:
2) enumerating namespaces. Sure you can walk through /proc, but that's
racy and won't even work with fd-only namespaces. It might even be a
security risk if some trojan creates, say, a VLAN on your eth0, or a
macvlan, hides it in a network namespace and communicates through it.
2 1/2) is terminating a namespace. It's not really a problem to add a
PID namespace when you have "uncontrollable" daemons; however you
can't be sure whether someone else took a reference on the network
namespace from the outside.
These all are mainly administration/management issues, not that much
regular operation. Writing routing software with VRF support works just
fine, but the sysadmin can be at somewhat of an odd end here.
-David
next prev parent reply other threads:[~2010-09-23 16:50 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-23 8:45 [ABI REVIEW][PATCH 0/8] Namespace file descriptors Eric W. Biederman
2010-09-23 8:46 ` [PATCH 1/8] ns: proc files for namespace naming policy Eric W. Biederman
2010-09-23 8:46 ` [PATCH 2/8] ns: Introduce the setns syscall Eric W. Biederman
2010-09-23 8:47 ` [PATCH 3/8] ns proc: Add support for the network namespace Eric W. Biederman
2010-09-23 11:27 ` Louis Rilling
2010-09-23 16:00 ` Eric W. Biederman
2010-09-23 8:48 ` [PATCH 4/8] ns proc: Add support for the uts namespace Eric W. Biederman
2010-09-23 8:49 ` [PATCH 5/8] ns proc: Add support for the ipc namespace Eric W. Biederman
2010-09-23 8:50 ` [PATCH 6/8] ns proc: Add support for the mount namespace Eric W. Biederman
2010-09-23 8:51 ` [PATCH 7/8] net: Allow setting the network namespace by fd Eric W. Biederman
2010-09-23 9:41 ` Eric Dumazet
2010-09-23 16:03 ` Eric W. Biederman
2010-09-23 11:22 ` jamal
2010-09-23 14:58 ` David Lamparter
2010-09-24 11:51 ` jamal
2010-09-24 12:57 ` David Lamparter
2010-09-24 13:32 ` jamal
2010-09-24 14:09 ` David Lamparter
2010-09-24 14:16 ` jamal
2010-09-23 15:14 ` Eric W. Biederman
2010-09-23 14:22 ` Brian Haley
2010-09-23 16:16 ` Eric W. Biederman
2010-09-24 13:46 ` Daniel Lezcano
2010-09-23 8:51 ` [PATCH 8/8] net: Implement socketat Eric W. Biederman
2010-09-23 8:56 ` Pavel Emelyanov
2010-09-23 11:19 ` jamal
2010-09-23 11:33 ` Pavel Emelyanov
2010-09-23 11:40 ` jamal
2010-09-23 11:53 ` Pavel Emelyanov
2010-09-23 12:11 ` jamal
2010-09-23 12:34 ` Pavel Emelyanov
2010-09-23 14:54 ` David Lamparter
2010-09-23 15:00 ` Eric W. Biederman
2010-10-02 21:13 ` Daniel Lezcano
2010-10-03 13:44 ` jamal
2010-10-04 10:13 ` Daniel Lezcano
2010-10-04 19:07 ` Eric W. Biederman
2010-10-15 12:30 ` netns patches WAS( " jamal
2010-10-26 20:52 ` jamal
2010-10-27 0:27 ` Eric W. Biederman
2010-09-23 15:18 ` [ABI REVIEW][PATCH 0/8] Namespace file descriptors David Lamparter
2010-09-23 16:32 ` Eric W. Biederman
2010-09-23 16:49 ` David Lamparter [this message]
2010-09-24 13:02 ` Andrew Lutomirski
2010-09-24 13:49 ` Daniel Lezcano
2010-09-24 17:06 ` Eric W. Biederman
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