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=-5.5 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 816EEC433E1 for ; Wed, 22 Jul 2020 07:56:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57F4F2077D for ; Wed, 22 Jul 2020 07:56:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728649AbgGVH4b (ORCPT ); Wed, 22 Jul 2020 03:56:31 -0400 Received: from verein.lst.de ([213.95.11.211]:55291 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726153AbgGVH4a (ORCPT ); Wed, 22 Jul 2020 03:56:30 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id E5D696736F; Wed, 22 Jul 2020 09:56:20 +0200 (CEST) Date: Wed, 22 Jul 2020 09:56:20 +0200 From: Christoph Hellwig To: Eric Biggers Cc: Christoph Hellwig , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Alexey Kuznetsov , Hideaki YOSHIFUJI , Eric Dumazet , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, linux-sctp@vger.kernel.org, linux-hams@vger.kernel.org, linux-bluetooth@vger.kernel.org, bridge@lists.linux-foundation.org, linux-can@vger.kernel.org, dccp@vger.kernel.org, linux-decnet-user@lists.sourceforge.net, linux-wpan@vger.kernel.org, linux-s390@vger.kernel.org, mptcp@lists.01.org, lvs-devel@vger.kernel.org, rds-devel@oss.oracle.com, linux-afs@lists.infradead.org, tipc-discussion@lists.sourceforge.net, linux-x25@vger.kernel.org Subject: Re: [PATCH 03/24] net: add a new sockptr_t type Message-ID: <20200722075620.GA26554@lst.de> References: <20200720124737.118617-1-hch@lst.de> <20200720124737.118617-4-hch@lst.de> <20200720163748.GA1292162@gmail.com> <20200720174322.GA21785@lst.de> <20200720175543.GF1292162@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200720175543.GF1292162@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jul 20, 2020 at 10:55:43AM -0700, Eric Biggers wrote: > On Mon, Jul 20, 2020 at 07:43:22PM +0200, Christoph Hellwig wrote: > > On Mon, Jul 20, 2020 at 09:37:48AM -0700, Eric Biggers wrote: > > > How does this not introduce a massive security hole when > > > CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE? > > > > > > AFAICS, userspace can pass in a pointer >= TASK_SIZE, > > > and this code makes it be treated as a kernel pointer. > > > > Yeah, we'll need to validate that before initializing the pointer. > > > > But thinking this a little further: doesn't this mean any > > set_fs(KERNEL_DS) that has other user pointers than the one it is > > intended for has the same issue? Pretty much all of these are gone > > in mainline now, but in older stable kernels there might be some > > interesting cases, especially in the compat ioctl handlers. > > Yes. I thought that eliminating that class of bug is one of the main > motivations for your "remove set_fs" work. See commit 128394eff343 > ("sg_write()/bsg_write() is not fit to be called under KERNEL_DS") for a case > where this type of bug was fixed. > > Are you aware of any specific cases that weren't already fixed? If there are > any, they need to be urgently fixed. current mainline has almost no set_fs left, and setsockopt seems pretty much safe. But if we go back a long term stable release or two I bet I'd find one or two.