Received: by 2002:a05:6358:1087:b0:cb:c9d3:cd90 with SMTP id j7csp1227035rwi; Fri, 14 Oct 2022 15:08:10 -0700 (PDT) X-Google-Smtp-Source: AMsMyM5n4v/PzSaV9+inHctAg/Nv71cIgla4CpTIXS1zKXBN0wTOS8EgOXDC8t+0lKCMUV1Vf7kn X-Received: by 2002:a17:907:2da6:b0:78d:3cf1:9132 with SMTP id gt38-20020a1709072da600b0078d3cf19132mr47346ejc.299.1665785290131; Fri, 14 Oct 2022 15:08:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1665785290; cv=none; d=google.com; s=arc-20160816; b=oS05Xs/K5HNqg3C2N1pincZopQYvAw/FsaW1LktNvIAWi2MVkvWPYsPzJUxdYTH9w/ 20P4R+Wa9oq6HbliqKvVmbYxTImCCOxewPTt3YDPrS5HE1//ZTo7H2LFTELk4T4Xbvih AdSYn9l3shVxxHT+Kh0da7wHgFexCpEYuCUc9Z7evJOu3vvkBc8KqAOTZmGhMSZftcIp EVh5x0d4EfB7+6g4kHWMww7oQbsqCE9uIWwJwFGYQIPY3Y8TxBSILR/+4+gSy8Z5VolW rvvcyE0ohN5F3Gx8u+xoEX/OIFsp4JYLAuXRSs0z0QnWeQECAEAZ/fVAxsaH0mXG4VHc IKmQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :mime-version:accept-language:in-reply-to:references:message-id:date :thread-index:thread-topic:subject:cc:to:from; bh=zqUhJLryFbjlHRhSgVRe/vu0xHAkGbbiX9yHfhmhsW8=; b=ahXl/GBiQsr8ACh6pephkQ5yiNXXIJBkMXf6WDbFm/ONvf9ZDJgWmE8+rOCS6IJRf2 jgo//wvyZr78peJ6/7Gs0HKF/DWcoAmaqRPb5k++j07UAME7zI9CHCXDBX8NHbaembYx z2KtrMljuAhe5UCzQX8PoS0cnqjtIZ5r8tiSQcQ6JSt6PwTsmNNhkOwgryzl9E+DWEmf eG+7F+qLOkK1PzzbhQ+Jr94+M6U9NZRizD7HnK+9A+Khr904sAXQzazaPM4ni82uwbpD C5WRyjmiKz6ViBsxTyv9XOPWzGLaybU2JC9sX4jj/PydQMEcVvJ0eP+LL2oQbmJ4HonN XbTA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=aculab.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id s18-20020a1709067b9200b0078df19995e4si3015199ejo.241.2022.10.14.15.07.43; Fri, 14 Oct 2022 15:08:10 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=aculab.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229595AbiJNWD1 convert rfc822-to-8bit (ORCPT + 99 others); Fri, 14 Oct 2022 18:03:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbiJNWDZ (ORCPT ); Fri, 14 Oct 2022 18:03:25 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 432D3176520 for ; Fri, 14 Oct 2022 15:03:23 -0700 (PDT) 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: 8BIT X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 preserve 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! David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)