From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id 8B2C26B0005 for ; Mon, 19 Feb 2018 20:21:24 -0500 (EST) Received: by mail-oi0-f69.google.com with SMTP id 1so6243928oiq.8 for ; Mon, 19 Feb 2018 17:21:24 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id f187si32205oic.532.2018.02.19.17.21.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Feb 2018 17:21:23 -0800 (PST) Date: Tue, 20 Feb 2018 12:21:11 +1100 From: Dave Chinner Subject: Re: [RFC PATCH v16 0/6] mm: security: ro protection for dynamic data Message-ID: <20180220012111.GC3728@rh> References: <20180212165301.17933-1-igor.stoppa@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Kees Cook Cc: Igor Stoppa , Matthew Wilcox , Randy Dunlap , Jonathan Corbet , Michal Hocko , Laura Abbott , Jerome Glisse , Christoph Hellwig , Christoph Lameter , linux-security-module , Linux-MM , LKML , Kernel Hardening On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote: > On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa wrote: > > This patch-set introduces the possibility of protecting memory that has > > been allocated dynamically. > > > > The memory is managed in pools: when a memory pool is turned into R/O, > > all the memory that is part of it, will become R/O. > > > > A R/O pool can be destroyed, to recover its memory, but it cannot be > > turned back into R/W mode. > > > > This is intentional. This feature is meant for data that doesn't need > > further modifications after initialization. > > This series came up in discussions with Dave Chinner (and Matthew > Wilcox, already part of the discussion, and others) at LCA. I wonder > if XFS would make a good initial user of this, as it could allocate > all the function pointers and other const information about a > superblock in pmalloc(), keeping it separate from the R/W portions? > Could other filesystems do similar things? I wasn't cc'd on this patchset, (please use david@fromorbit.com for future postings) so I can't really say anything about it right now. My interest for XFS was that we have a fair amount of static data in XFS that we set up at mount time and it never gets modified after that. I'm not so worried about VFS level objects (that's a much more complex issue) but there is a lot of low hanging fruit in the XFS structures we could convert to write-once structures. Cheers, Dave. -- Dave Chinner dchinner@redhat.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org