Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754400Ab2FFBZK (ORCPT ); Tue, 5 Jun 2012 21:25:10 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:36655 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752203Ab2FFBZI (ORCPT ); Tue, 5 Jun 2012 21:25:08 -0400 Date: Wed, 6 Jun 2012 10:54:59 +0930 From: Christopher Yeoh To: Borislav Petkov Cc: Andrew Morton , Linus Torvalds , LKML , Randy Dunlap Subject: Re: [PATCH] CMA: Do no enable it by default Message-ID: <20120606105459.49430920@Gantu> In-Reply-To: <20120605110541.GC13495@aftab.osrc.amd.com> References: <20120531153512.GK14515@aftab.osrc.amd.com> <20120531154224.GL14515@aftab.osrc.amd.com> <20120601110647.2c446aa7@rockpopper> <20120605110541.GC13495@aftab.osrc.amd.com> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit x-cbid: 12060515-9264-0000-0000-000001A694A1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1253 Lines: 34 On Tue, 5 Jun 2012 13:05:41 +0200 Borislav Petkov wrote: > > CROSS_MEMORY_ATTACH is a MPI feature which shouldn't be enabled by > default on every linux system simply because the majority of users do > not need it. btw although CMA was primarily written for MPI it is used by more than just MPI implementations. For example, recent versions of strace now use it instead of PTRACE_PEEKDATA if its available: http://article.gmane.org/gmane.comp.sysutils.strace.devel/2467/match=process_vm_readv > Besides, in the config option it says "... which allow a process with > the correct privileges to directly read from or write to to another > process's address space.", which, if the reading process has somehow > gained privileges (as that never happens) is your security issue right > there. The privileges required are exactly the same as required to ptrace the target. You're rather stuffed anyway if you have a hostile process with those privileges. Regards, Chris -- cyeoh@au.ibm.com -- 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/