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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5819C7EE2E for ; Sat, 10 Jun 2023 22:05:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232417AbjFJVrL convert rfc822-to-8bit (ORCPT ); Sat, 10 Jun 2023 17:47:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbjFJVrG (ORCPT ); Sat, 10 Jun 2023 17:47:06 -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 57A0135A3 for ; Sat, 10 Jun 2023 14:47:03 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-71-WwJFuWklNRioR6AeYR7C1A-1; Sat, 10 Jun 2023 22:47:00 +0100 X-MC-Unique: WwJFuWklNRioR6AeYR7C1A-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Sat, 10 Jun 2023 22:46:55 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Sat, 10 Jun 2023 22:46:55 +0100 From: David Laight To: 'Nikolay Borisov' , "x86@kernel.org" CC: "linux-kernel@vger.kernel.org" , "mhocko@suse.com" , "jslaby@suse.cz" Subject: RE: [PATCH v2 0/4] Make IA32_EMULATION boot time overridable Thread-Topic: [PATCH v2 0/4] Make IA32_EMULATION boot time overridable Thread-Index: AQHZmsNlxcUUAdbQu0asg62sJKhJ1K+Ek7Zg Date: Sat, 10 Jun 2023 21:46:55 +0000 Message-ID: <930ebd9ac94843129781ec208a0dd69f@AcuMS.aculab.com> References: <20230609111311.4110901-1-nik.borisov@suse.com> In-Reply-To: <20230609111311.4110901-1-nik.borisov@suse.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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nikolay Borisov > Sent: 09 June 2023 12:13 > > Here's the 2nd version of the patch which aims to make IA32_EMULATION essentially > a boot time option. The changes in this posting are: Does it make any sense to be able to enable/disable it at run-time (through a sysctl). Perhaps only if enabled at boot - where it can be a 'soft disable' even though the cpu is initialised to allow the 32bit system calls. Remember, if you are root (and the system isn't hard locked down) it is pretty easy to change a global boolean variable. So it doesn't really affect the attack surface. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)