From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B528C432BE for ; Sat, 28 Aug 2021 07:10:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 932646108D for ; Sat, 28 Aug 2021 07:10:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 932646108D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 03DE46B006C; Sat, 28 Aug 2021 03:10:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F2F5A6B0071; Sat, 28 Aug 2021 03:10:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DF6B38D0001; Sat, 28 Aug 2021 03:10:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0235.hostedemail.com [216.40.44.235]) by kanga.kvack.org (Postfix) with ESMTP id C503D6B006C for ; Sat, 28 Aug 2021 03:10:18 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5A65622BF0 for ; Sat, 28 Aug 2021 07:10:18 +0000 (UTC) X-FDA: 78523615716.16.63B59D9 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf18.hostedemail.com (Postfix) with ESMTP id C61914002088 for ; Sat, 28 Aug 2021 07:10:17 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 8E5E267373; Sat, 28 Aug 2021 09:10:14 +0200 (CEST) Date: Sat, 28 Aug 2021 09:10:14 +0200 From: Christoph Hellwig To: NeilBrown Cc: Christoph Hellwig , "Darrick J. Wong" , David Howells , torvalds@linux-foundation.org, trond.myklebust@primarydata.com, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Don't block writes to swap-files with ETXTBSY. Message-ID: <20210828071014.GA31677@lst.de> References: <20210827151644.GB19199@lst.de> <163010581548.7591.7557563272768619093@noble.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <163010581548.7591.7557563272768619093@noble.neil.brown.name> User-Agent: Mutt/1.5.17 (2007-11-01) Authentication-Results: imf18.hostedemail.com; dkim=none; dmarc=none; spf=none (imf18.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C61914002088 X-Stat-Signature: hs8nampc8fedfuascjt3rbq4rdqwgdu7 X-HE-Tag: 1630134617-58550 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Aug 28, 2021 at 09:10:15AM +1000, NeilBrown wrote: > There are lots of different things root can do which will mess up the > kernel badly. The backing-store can still be changed through some other > means. > Do you have a particular threat or risk scenario other than "root might > get careless"? No, it is just that scenario. But one that is much easier to trigger than more convoluted ways for a root user to trigger damage through device files, and one that can't be prevented through LSMs or the capability system.