From: Pavel Emelyanov <xemul@parallels•com>
To: "Eric W. Biederman" <ebiederm@xmission•com>,
Sukadev Bhattiprolu <sukadev@linux•vnet.ibm.com>
Cc: Daniel Lezcano <daniel.lezcano@free•fr>,
Serge Hallyn <serue@us•ibm.com>,
Linux Netdev List <netdev@vger•kernel.org>,
containers@lists•linux-foundation.org,
Netfilter Development Mailinglist
<netfilter-devel@vger•kernel.org>,
Ben Greear <greearb@candelatech•com>
Subject: Re: [RFC][PATCH] ns: Syscalls for better namespace sharing control.
Date: Fri, 05 Mar 2010 22:18:13 +0300 [thread overview]
Message-ID: <4B9158F5.5040205@parallels.com> (raw)
In-Reply-To: <m17hptjh3m.fsf@fess.ebiederm.org>
> 2 parallel enters? I meant you have pid 0 in the entered pid namespace.
> You have pid 0 because your pid simply does not map.
Oh, I see.
> There is nothing that makes to parallel enters impossible in that.
> Even today we have one thread per cpu that has task->pid == &init_struct_pid
> which is pid 0.
How about the forked processes then? Who will be their parent?
> For the case of unshare where we are designed to be used with PAM I don't
> think my proposed semantics work. For a join needed an extra fork before
> you are really in the pid namespace should be minor.
Hm... One more proposal - can we adopt the planned new fork_with_pids system
call to fork the process right into a new pid namespace?
> That doesn't handle the case of cached struct pids. A good example is
> waitpid, where it waits for a specific struct pid. Which means that
> allocating a new struct pid and changing task->pid will cause
> waitpid(pid) to wait forever...
OK. Good example. Thanks.
> To change struct pid would require the refcount on struct pid to show
> no references from anywhere except the task_struct.
I think this is OK to return -EBUSY for this. And fix the waitpid
respectively not to block this common case. All the others I think
can be stayed as is.
> At the cost of a little memory we can solve that problem for unshare
> if we have a an extra upid in struct pid, how we verify there is space
> in struct pid I'm not certain.
>
> I do think that at least until someone calls exec the namespace pids are
> reported to the process itself should not change. That is kill and
Wait a second - in that case the wait will be blocked too! No?
> waitpid etc. Which suggests an implementation the opposite of what
> I proposed. With ns_of_pid(task_pid(current)) being used as the
> pid namespace of children, and current->nsproxy->pid_ns not changing
> in the case of unshare.
>
> Shrug.
>
> Or perhaps this is a case where we use we can implement join with
> an extra process but we can't implement unshare, because the effect
> cannot be immediate.
Well, I'm talking only about the join now.
> Eric
>
next prev parent reply other threads:[~2010-03-05 19:19 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-14 14:05 RFC: netfilter: nf_conntrack: add support for "conntrack zones" Patrick McHardy
2010-01-14 15:05 ` jamal
2010-01-14 15:37 ` Patrick McHardy
2010-01-14 17:33 ` jamal
2010-01-15 10:15 ` Patrick McHardy
2010-01-15 15:19 ` jamal
2010-02-22 20:46 ` Eric W. Biederman
2010-02-22 21:55 ` jamal
2010-02-22 23:17 ` Eric W. Biederman
[not found] ` <m1wry46es9.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-02-23 13:27 ` jamal
2010-02-23 14:07 ` Eric W. Biederman
2010-02-23 14:20 ` jamal
2010-02-23 20:00 ` Eric W. Biederman
2010-02-23 23:09 ` jamal
2010-02-24 1:43 ` Eric W. Biederman
2010-02-25 20:57 ` [RFC][PATCH] ns: Syscalls for better namespace sharing control Eric W. Biederman
2010-02-25 21:31 ` Daniel Lezcano
2010-02-25 21:49 ` Eric W. Biederman
2010-02-25 22:13 ` Daniel Lezcano
2010-02-25 22:31 ` Eric W. Biederman
2010-02-26 20:35 ` Eric W. Biederman
2010-02-25 21:46 ` Matt Helsley
2010-02-25 21:54 ` Eric W. Biederman
2010-02-26 0:53 ` Eric W. Biederman
2010-02-26 1:09 ` Matt Helsley
2010-02-26 1:26 ` Eric W. Biederman
2010-02-26 3:15 ` [RFC][PATCH] ns: Syscalls for better namespace sharing control. v2 Eric W. Biederman
[not found] ` <m18wagy9f3.fsf_-_-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-03-03 20:29 ` Jonathan Corbet
2010-03-03 20:50 ` Eric W. Biederman
[not found] ` <m1pr3t2fvl.fsf_-_-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-02-26 21:13 ` [RFC][PATCH] ns: Syscalls for better namespace sharing control Pavel Emelyanov
2010-02-26 21:24 ` Eric W. Biederman
2010-02-26 21:34 ` Pavel Emelyanov
2010-02-26 21:42 ` Eric W. Biederman
2010-02-26 21:58 ` Oren Laadan
2010-02-26 22:16 ` Eric W. Biederman
2010-02-26 22:52 ` Oren Laadan
2010-02-26 23:13 ` Eric W. Biederman
2010-02-27 8:30 ` Pavel Emelyanov
2010-02-27 9:04 ` Eric W. Biederman
[not found] ` <m1mxyvrqvk.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-02-27 9:21 ` Pavel Emelyanov
2010-02-27 9:42 ` Eric W. Biederman
2010-02-27 16:16 ` Pavel Emelyanov
2010-02-27 19:08 ` Eric W. Biederman
2010-02-27 19:29 ` Pavel Emelyanov
2010-02-27 19:44 ` Eric W. Biederman
2010-02-28 22:05 ` Daniel Lezcano
2010-03-01 19:24 ` Eric W. Biederman
2010-03-01 21:42 ` Eric W. Biederman
2010-03-02 13:10 ` Cedric Le Goater
2010-03-02 15:03 ` Pavel Emelyanov
2010-03-02 15:14 ` Jan Engelhardt
2010-03-02 21:45 ` Eric W. Biederman
2010-03-02 21:19 ` Sukadev Bhattiprolu
2010-03-02 22:13 ` Eric W. Biederman
2010-03-03 0:07 ` Sukadev Bhattiprolu
2010-03-03 0:46 ` Eric W. Biederman
2010-03-03 15:38 ` Serge E. Hallyn
2010-03-03 19:47 ` Eric W. Biederman
2010-03-04 21:45 ` Eric W. Biederman
2010-03-04 22:55 ` Jan Engelhardt
2010-03-03 16:50 ` Pavel Emelyanov
2010-03-03 20:16 ` Eric W. Biederman
2010-03-05 19:18 ` Pavel Emelyanov [this message]
2010-03-05 20:26 ` Eric W. Biederman
2010-03-06 14:47 ` Daniel Lezcano
[not found] ` <4B926B1B.5070207-GANU6spQydw@public.gmane.org>
2010-03-06 20:48 ` Eric W. Biederman
[not found] ` <m1aaulyy5c.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-03-06 21:26 ` Daniel Lezcano
2010-03-08 8:32 ` Eric W. Biederman
2010-03-08 16:54 ` Daniel Lezcano
2010-03-08 17:29 ` Eric W. Biederman
2010-03-08 19:57 ` Daniel Lezcano
2010-03-08 20:24 ` Eric W. Biederman
2010-03-08 20:42 ` Daniel Lezcano
2010-03-08 20:47 ` Eric W. Biederman
2010-03-08 21:12 ` Daniel Lezcano
2010-03-08 21:25 ` Eric W. Biederman
2010-03-08 21:49 ` Serge E. Hallyn
2010-03-08 22:24 ` Eric W. Biederman
2010-03-09 10:03 ` Daniel Lezcano
2010-03-09 10:13 ` Eric W. Biederman
2010-03-09 10:26 ` Daniel Lezcano
2010-03-10 21:16 ` Daniel Lezcano
2010-03-08 17:07 ` Serge E. Hallyn
2010-03-08 17:35 ` Eric W. Biederman
2010-03-08 17:47 ` Serge E. Hallyn
2010-03-03 20:59 ` Oren Laadan
2010-03-03 21:05 ` Eric W. Biederman
[not found] ` <m1bpfbwuze.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2010-02-26 21:35 ` Pavel Emelyanov
2010-02-26 21:49 ` Eric W. Biederman
2010-02-23 23:49 ` RFC: netfilter: nf_conntrack: add support for "conntrack zones" Matt Helsley
2010-02-24 1:32 ` Eric W. Biederman
2010-02-24 1:39 ` Serge E. Hallyn
2010-01-14 18:32 ` Ben Greear
2010-01-15 15:03 ` jamal
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