From: ebiederm@xmission•com (Eric W. Biederman)
To: linux-kernel@vger•kernel.org
Cc: 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: [PATCH 3/8] ns proc: Add support for the network namespace.
Date: Thu, 23 Sep 2010 09:00:31 -0700 [thread overview]
Message-ID: <m1pqw4h2lc.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20100923112739.GD2211@hawkmoon.kerlabs.com> (Louis Rilling's message of "Thu, 23 Sep 2010 13:27:39 +0200")
Louis Rilling <Louis.Rilling@kerlabs•com> writes:
> On 23/09/10 1:47 -0700, Eric W. Biederman wrote:
>>
>> Implementing file descriptors for the network namespace is simple and
>> straight forward.
>>
>> Signed-off-by: Eric W. Biederman <ebiederm@xmission•com>
>
> [...]
>
>> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
>> index c988e68..581a088 100644
>> --- a/net/core/net_namespace.c
>> +++ b/net/core/net_namespace.c
>> @@ -571,3 +571,33 @@ void unregister_pernet_device(struct pernet_operations *ops)
>> mutex_unlock(&net_mutex);
>> }
>> EXPORT_SYMBOL_GPL(unregister_pernet_device);
>> +
>> +#ifdef CONFIG_NET_NS
>> +static void *netns_get(struct task_struct *task)
>> +{
>> + struct net *net;
>> + rcu_read_lock();
>> + net = get_net(task->nsproxy->net_ns);
>
> task could be exiting, so task->nsproxy could be NULL, right?
> Maybe make proc_ns_instantiate() rcu_dereference task->nsproxy, check for it
> being not NULL, and pass task->nsproxy to ns_ops->get()?
Ugh. Thanks. fixed.
Somehow I forgot /proc shows zombies which means nsproxy
will definitely be NULL in those cases. It is easy enough to handle
once my brain gets out of park.
I don't hold any locks at that point so I don't think I want to do
anything in proc_ns_instantiate() except handle a NULL return when
the ns_ops->get() fails.
> That could be an issue for the user namespace since it is not in nsproxy, but
> maybe no reasonable usage of ns_ops with user namespaces is
> envisioned.
It is also a issue for the pid namespace.
> Otherwise, checking that task is alive with RCU locked in proc_ns_instantiate() should be enough to be
> rely on task->cred when calling ns_ops->get().
That sounds about right. I keep conveniently forgetting the user
namespace. It doesn't support unshare right now so there isn't anything
I can reasonably do with it at the moment. It wouldn't surprise me if I
don't wind up handling the user namespace like the pid namespace, where
unsharing it changes the properties for the children and not the parent.
Bleh.
Eric
next prev parent reply other threads:[~2010-09-23 16:00 UTC|newest]
Thread overview: 47+ 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 [this message]
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
[not found] ` <m1ocborgq7.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
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
[not found] ` <m1hbhgq1v1.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
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
[not found] ` <4C9B3B06.900-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
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
2010-09-24 13:02 ` Andrew Lutomirski
2010-09-24 13:49 ` Daniel Lezcano
2010-09-24 17:06 ` Eric W. Biederman
2010-09-29 3:09 ` Rémi Denis-Courmont
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