From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755362Ab2LRUTc (ORCPT ); Tue, 18 Dec 2012 15:19:32 -0500 Received: from charlotte.tuxdriver.com ([70.61.120.58]:55304 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755254Ab2LRUTb (ORCPT ); Tue, 18 Dec 2012 15:19:31 -0500 Date: Tue, 18 Dec 2012 15:19:01 -0500 From: Neil Horman To: Oleg Nesterov Cc: "Eric W. Biederman" , Pavel Emelyanov , Daniel Berrange , Alexander Viro , Serge Hallyn , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: + core_pattern-set-core-helpers-root-and-namespace-to-crashing-process .patch added to -mm tree Message-ID: <20121218201900.GA10059@hmsreliant.think-freely.org> References: <20121217123428.GA1957@redhat.com> <20121217150559.GD25322@hmsreliant.think-freely.org> <20121217160408.GA20166@redhat.com> <20121217183925.GE25322@hmsreliant.think-freely.org> <20121218200604.GA28834@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121218200604.GA28834@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Score: -2.9 (--) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2012 at 09:06:04PM +0100, Oleg Nesterov wrote: > On 12/17, Neil Horman wrote: > > > > On Mon, Dec 17, 2012 at 05:04:08PM +0100, Oleg Nesterov wrote: > > > > > > > Is there a way to switch all namespaces, except for the pid > > > > namespace? > > > > > > Which exactly namespaces you want to change? > > > > > Ideally, I want the pipe reader process to execute in the same namespaces that > > the crashing process executed in (i.e. the pipe reader should execute as though > > the crashing process forked it). > > Yes, and we probably want to change pid_ns as well. But afaics currently > this is not possible, even setns can't do this. > > I am starting to think that in this case, perhaps, do_coredump() should > not use call_usermode_helper() at all. Perhaps we can do clone(CLONE_VM) + > commit_creds/restore_root/etc + kernel_execve. > Yeah, I was comming to this same conclusion last night as well. I'd rather keep using the call_usermode_helper solution if at all possible, but perhaps we can integrate a clone path into it. > > > To be honest, I do not understand this patch at all. It seems that > > > you need to do something like sys_setns(). But if we do this, then > > > why we can't make core_pattern per-namespace? > > > > > That actually would make sense, although we can't really use setns directly, as > > I don't think we want to open file descriptors to do this manipulation in the > > kernel. > > Yes, yes, sure. But this is solveable. We do not really need to open > the files in /proc, we could use proc_ns_operations->install() directly. > Although this is not pretty. > Its not pretty, no. If we use the above clone solution however, we can avoid this entirely. > > Perhaps its best just to restrict this patch to adjusting the root fs location > > for the chroot case. > > Probably... at least for the start. > > BTW. Of course this is subjective, but personally I think that "||" > looks strange. Perhaps it would be better to add something like > --croot argument? > The || is ambiguous with its simmilarity to a shell 'or' command, but I don't think the --croot argument is much better on that front, as that then becomes ambiguous with arguments supplied to the pipe reader directly. The token should be leading the pipe_reader string in core_pattern to indicate a change in environment independent of the executable path. Perhaps |^ or something simmilar? Either way, Andrew, could you please drop this patch? Olegs comments I think make it pretty clear I've got some more work to do on this. Thanks! Neil