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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22E39C433FE for ; Fri, 14 Oct 2022 22:03:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6D6836B0072; Fri, 14 Oct 2022 18:03:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6851A6B0075; Fri, 14 Oct 2022 18:03:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4FEBE6B0078; Fri, 14 Oct 2022 18:03:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 3A6396B0072 for ; Fri, 14 Oct 2022 18:03:27 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 0FD36140C39 for ; Fri, 14 Oct 2022 22:03:27 +0000 (UTC) X-FDA: 80020932054.02.6A0A389 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by imf29.hostedemail.com (Postfix) with ESMTP id E21D3120030 for ; Fri, 14 Oct 2022 22:03:24 +0000 (UTC) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-317-JETZyr0OPF-X3dTWyLgaXA-1; Fri, 14 Oct 2022 23:03:20 +0100 X-MC-Unique: JETZyr0OPF-X3dTWyLgaXA-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Fri, 14 Oct 2022 23:03:18 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.040; Fri, 14 Oct 2022 23:03:18 +0100 From: David Laight To: 'Andy Lutomirski' , Jann Horn , Christian Brauner CC: Kees Cook , "Eric W. Biederman" , Jorge Merlino , Al Viro , Thomas Gleixner , "Sebastian Andrzej Siewior" , Andrew Morton , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" , "John Johansen" , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , Richard Haines , Casey Schaufler , Xin Long , "David S. Miller" , Todd Kjos , "Ondrej Mosnacek" , Prashanth Prahlad , Micah Morton , Fenghua Yu , Andrei Vagin , Linux Kernel Mailing List , "apparmor@lists.ubuntu.com" , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , "linux-hardening@vger.kernel.org" Subject: RE: [PATCH 1/2] fs/exec: Explicitly unshare fs_struct on exec Thread-Topic: [PATCH 1/2] fs/exec: Explicitly unshare fs_struct on exec Thread-Index: AQHY33u3rva59bT1H02MahRCUmFfoq4Ocehg Date: Fri, 14 Oct 2022 22:03:18 +0000 Message-ID: References: <20221006082735.1321612-1-keescook@chromium.org> <20221006082735.1321612-2-keescook@chromium.org> <20221006090506.paqjf537cox7lqrq@wittgenstein> <2032f766-1704-486b-8f24-a670c0b3cb32@app.fastmail.com> In-Reply-To: <2032f766-1704-486b-8f24-a670c0b3cb32@app.fastmail.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665785006; a=rsa-sha256; cv=none; b=Lj0DfOQbm0IakzbvbEqjmr0MWDaTDjbjY3We9HeM+sCSev4pLyghRYgB3hioahk/ty9nBl Z5mcdDXaGCkwMFxx5xOwhSXUZnhy6Oq9pLPoXU36iTL/Dac2NhB1IbGnLOR444Il80djwX HcKMrDVyAPSE8Uq3DFJ9IdM8i/Z4Hao= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none; spf=pass (imf29.hostedemail.com: domain of david.laight@aculab.com designates 185.58.86.151 as permitted sender) smtp.mailfrom=david.laight@aculab.com; dmarc=pass (policy=none) header.from=aculab.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665785006; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xCcuUEy4P9O4sUbGvVIQYkxEaxPsnNKtV9KqO2zcBDk=; b=KyagR7yTW/rpAkB/nRJXcSJHZckEfuRTTPvwbK07OX7IASOJ7XT6W2Ut/1EOso84LPUbwj QcGH0sNs8D6NzliSITqow0nhIZsvrLz0VE0ZJmq0XHYxLeFyMRaFdkRf0YqQEr/Cm65S2V ALHIe1iISfFTTIf0YdvSAvADpTyp6mI= X-Stat-Signature: tcgmm4qefxwo1d5sit7xeuigmxi1ztda X-Rspamd-Queue-Id: E21D3120030 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=none; spf=pass (imf29.hostedemail.com: domain of david.laight@aculab.com designates 185.58.86.151 as permitted sender) smtp.mailfrom=david.laight@aculab.com; dmarc=pass (policy=none) header.from=aculab.com X-Rspamd-Server: rspam06 X-HE-Tag: 1665785004-818471 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: From: Andy Lutomirski > Sent: 14 October 2022 04:18 ... > But seriously, this makes no sense at all. It should not be possible to = exec a program and then, > without ptrace, change its cwd out from under it. Do we really need to p= reserve this behavior? it maybe ok if the exec'ed program also 'bought-in' to the fact that its cwd and open files might get changed. But imagine someone doing it to a login shell! =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)