Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757982Ab0LNQER (ORCPT ); Tue, 14 Dec 2010 11:04:17 -0500 Received: from hera.kernel.org ([140.211.167.34]:48636 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755345Ab0LNQEP (ORCPT ); Tue, 14 Dec 2010 11:04:15 -0500 Message-ID: <4D079541.3090405@kernel.org> Date: Tue, 14 Dec 2010 17:03:13 +0100 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.13) Gecko/20101207 Lightning/1.0b2 Thunderbird/3.1.7 MIME-Version: 1.0 To: Linus Torvalds CC: "Suzuki K. Poulose" , linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , Christoph Hellwig , Masami Hiramatsu , Ananth N Mavinakayanahalli , Daisuke HATAYAMA , Andi Kleen , Roland McGrath , Amerigo Wang , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Oleg Nesterov , Andrew Morton Subject: Re: [RFC] [Patch 0/21] Non disruptive application core dump infrastructure References: <20101214152259.67896960@suzukikp> In-Reply-To: X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 14 Dec 2010 16:03:15 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 37 Hello, On 12/14/2010 04:49 PM, Linus Torvalds wrote: > On Tue, Dec 14, 2010 at 1:52 AM, Suzuki K. Poulose wrote: >> >> This is series of patches implementing an infrastructure for capturing the core >> of an application without disrupting its process semantics. >> >> The infrastructure makes use of the freezer subsystem in kernel to freeze the >> threads and then collect the information to generate the core. > > This seems to be a fundamentally flawed approach. > >>From a security standpoint, it looks like a total disaster. A frozen > process is really hard to get rid of, so it looks like an obvious DoS > attack to just create lots of processes, then sneakily freeze them > all, and then laugh at the poor system admin who has no idea what's > going on. While frozen, the things are basically unkillable but look > entirely normal, no? I think a better way would be adding a ptrace attach which is nestable and doesn't have the nasty side effect caused by the interactions between the implicit SIGSTOP and group stop. As a preparation step, I posted a patchset to cleanup the interactions between ptrace and group stop which is being reviewed. Once we have a nestable ptrace attach, we should be able to simply adapt gcore(1) to use it and write out core dump from userland. Thanks. -- tejun -- 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/