Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754537AbZGBAjV (ORCPT ); Wed, 1 Jul 2009 20:39:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752693AbZGBAjO (ORCPT ); Wed, 1 Jul 2009 20:39:14 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:37767 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751579AbZGBAjN (ORCPT ); Wed, 1 Jul 2009 20:39:13 -0400 Date: Wed, 1 Jul 2009 17:35:20 -0700 From: Sukadev Bhattiprolu To: Roland McGrath Cc: Oleg Nesterov , "Eric W. Biederman" , Oren Laadan , serue@us.ibm.com, Alexey Dobriyan , Containers , linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] Disable CLONE_PARENT for init Message-ID: <20090702003520.GA26247@us.ibm.com> References: <20090701073140.GA14284@us.ibm.com> <20090701074654.A6C6321D57@magilla.sf.frob.com> <20090701082452.GA3297@redhat.com> <20090701214805.GA25734@us.ibm.com> <20090701215833.876DA404FD@magilla.sf.frob.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090701215833.876DA404FD@magilla.sf.frob.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2244 Lines: 57 Roland McGrath [roland@redhat.com] wrote: | Yeah, that's fine. Since Oleg's pointed out that there is indeed no way to | avoid the leak in some global-init uses, it is fine to have a comment that | says that global init problems are part of the reason to outlaw this usage. | I just objected to a change that was really for container init but said it | was only to fix something different. Ok. How about this comment: --- Disable CLONE_PARENT for init. When global or container-init processes use CLONE_PARENT, they create a multi-rooted process tree. Besides siblings of global init remain as zombies on exit since they are not reaped by their parent (swapper). So prevent global and container-inits from creating siblings. Changelog[v3]: - [Roland, Oleg] Simplify comment describing the change Changelog[v2]: - Simplify patch description based on comments from Eric Biederman and Oleg Nesterov. - [Oleg Nesterov] Use SIGNAL_UNKILLABLE instead of is_global_init() Signed-off-by: Sukadev Bhattiprolu Acked-by: "Eric W. Biederman" --- kernel/fork.c | 10 ++++++++++ 1 file changed, 10 insertions(+) Index: linux-mmotm/kernel/fork.c =================================================================== --- linux-mmotm.orig/kernel/fork.c 2009-06-30 23:01:06.000000000 -0700 +++ linux-mmotm/kernel/fork.c 2009-07-01 17:29:09.000000000 -0700 @@ -974,6 +974,16 @@ static struct task_struct *copy_process( if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) return ERR_PTR(-EINVAL); + /* + * Siblings of global init remain as zombies on exit since they are + * not reaped by their parent (swapper). To solve this and to avoid + * multi-rooted process trees, prevent global and container-inits + * from creating siblings. + */ + if ((clone_flags & CLONE_PARENT) && + current->signal->flags & SIGNAL_UNKILLABLE) + return ERR_PTR(-EINVAL); + retval = security_task_create(clone_flags); if (retval) goto fork_out; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/