From: ebiederm@xmission•com (Eric W. Biederman)
To: "Rémi Denis-Courmont" <remi@remlab•net>
Cc: linux-arch@vger•kernel.org, linux-kernel@vger•kernel.org,
netdev@vger•kernel.org, linux-fsdevel@vger•kernel.org,
jamal <hadi@cyberus•ca>, Daniel Lezcano <daniel.lezcano@free•fr>,
Linux Containers <containers@lists•osdl.org>,
Renato Westphal <renatowestphal@gmail•com>
Subject: Re: [PATCH 2/7] ns: Introduce the setns syscall
Date: Sat, 07 May 2011 06:57:06 -0700 [thread overview]
Message-ID: <m1bozepqa5.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <201105071101.10950.remi@remlab.net> ("Rémi Denis-Courmont"'s message of "Sat, 7 May 2011 11:01:08 +0300")
"Rémi Denis-Courmont" <remi@remlab•net> writes:
> Le samedi 7 mai 2011 05:24:56 Eric W. Biederman, vous avez écrit :
>> Pieces of this puzzle can also be solved by instead of
>> coming up with a general purpose system call coming up
>> with targed system calls perhaps socketat that solve
>> a subset of the larger problem. Overall that appears
>> to be more work for less reward.
>
> socketat() is still required for multithreaded namespace-aware userspace, I
> believe.
The network namespace is a per task property so there are no problems
with multithreaded network namespace aware userspace applications. The
implementation of a userspace socketat will still need to disable signal
handling around the network namespace switch to be signal safe. Which
means that ultimately a kernel version of socketat may be desirable,
for performance reasons but I know of know correctness reasons to need
it.
For the time being I have simply removed socketat from what I plan to
merge because it is not strictly needed, I don't yet have a test case
for socketat, and I don't have as much time to work on this as I
would like.
There is one bug a multi-threaded network namespace aware user space
application might run into, and that is /proc/net is a symlink to
/proc/self. Which means that if you open /proc/net/foo from a task with
a different network namespace than your the task whose tid equals your
tgid, the /proc/net will return the wrong file. Still you can
avoid even that silliness by opening /proc/<tid>/net.
Eric
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next prev parent reply other threads:[~2011-05-07 13:57 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-07 2:23 [PATCH 0/7] Network namespace manipulation with file descriptors Eric W. Biederman
2011-05-07 2:24 ` [PATCH 1/7] ns: proc files for namespace naming policy Eric W. Biederman
2011-05-07 2:24 ` [PATCH 3/7] ns proc: Add support for the network namespace Eric W. Biederman
2011-05-07 22:41 ` Daniel Lezcano
2011-05-11 19:21 ` Nathan Lynch
2011-05-11 21:34 ` Eric W. Biederman
2011-05-11 21:42 ` Nathan Lynch
2011-05-07 2:24 ` [PATCH 4/7] ns proc: Add support for the uts namespace Eric W. Biederman
2011-05-07 22:42 ` Daniel Lezcano
2011-05-07 2:24 ` [PATCH 5/7] ns proc: Add support for the ipc namespace Eric W. Biederman
2011-05-07 22:44 ` Daniel Lezcano
[not found] ` <1304735101-1824-1-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2011-05-07 2:24 ` [PATCH 2/7] ns: Introduce the setns syscall Eric W. Biederman
[not found] ` <1304735101-1824-2-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2011-05-07 8:01 ` Rémi Denis-Courmont
2011-05-07 13:57 ` Eric W. Biederman [this message]
2011-05-07 22:39 ` Daniel Lezcano
2011-05-08 3:51 ` Matt Helsley
2011-05-11 19:21 ` Nathan Lynch
2011-05-11 20:33 ` Eric W. Biederman
2011-05-07 2:25 ` [PATCH 6/7] net: Allow setting the network namespace by fd Eric W. Biederman
2011-05-07 22:46 ` Daniel Lezcano
2011-05-07 2:25 ` [PATCH 7/7] ns: Wire up the setns system call Eric W. Biederman
2011-05-07 8:27 ` Geert Uytterhoeven
2011-05-07 14:09 ` Eric W. Biederman
2011-05-07 18:22 ` Geert Uytterhoeven
2011-05-07 13:59 ` Mike Frysinger
2011-05-07 20:06 ` James Bottomley
2011-05-08 2:19 ` Eric W. Biederman
2011-05-08 4:02 ` James Bottomley
2011-05-07 22:37 ` [PATCH 1/7] ns: proc files for namespace naming policy Daniel Lezcano
2011-05-11 19:20 ` Nathan Lynch
2011-05-11 22:52 ` Eric W. Biederman
[not found] ` <m1tyd7p7tq.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-05-07 6:58 ` [PATCH 0/7] Network namespace manipulation with file descriptors Alex Bligh
2011-05-07 14:18 ` Eric W. Biederman
2011-05-08 12:31 ` Alex Bligh
[not found] ` <m1fwoqoapn.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-05-17 11:11 ` David Lamparter
2011-05-17 14:33 ` Eric W. Biederman
2011-05-17 15:35 ` David Lamparter
2011-05-22 4:19 ` Renato Westphal
2011-05-09 19:04 ` David Miller
2011-05-09 19:59 ` Eric W. Biederman
2011-05-09 20:40 ` David Miller
2011-05-09 20:54 ` Eric W. Biederman
2011-05-09 20:55 ` David Miller
2011-05-10 21:56 ` Luck, Tony
2011-05-10 23:02 ` Eric W. Biederman
2011-05-18 12:43 ` Identifying network namespaces (was: Network namespace manipulation with file descriptors) David Lamparter
2011-05-18 13:03 ` Alexey Dobriyan
[not found] ` <BANLkTikmrC86hk=W84UBwhJLe_uGAN4w9w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-18 13:33 ` David Lamparter
2011-05-18 14:13 ` Alexey Dobriyan
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