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 6FEC4C433F5 for ; Wed, 11 May 2022 21:25:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348125AbiEKVZc (ORCPT ); Wed, 11 May 2022 17:25:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231319AbiEKVZa (ORCPT ); Wed, 11 May 2022 17:25:30 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC74A6899A for ; Wed, 11 May 2022 14:25:28 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id j6so3023694pfe.13 for ; Wed, 11 May 2022 14:25:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=HIWfXQz7kRZQ85ksmcAfNGtsJ5AkaWLd2ccGoBYRMog=; b=UcIeEmvNoPh4PVI5f7d37R7zCIYVNm23OYOPAtzxps2DCiixyPPBZiEkYXDS2QX2Db c9Urri+NPtwefoFAjOKxkaiYWXY+MjrXy9NdNLiDIp7xToFtFJ/tWRgwgtmoR4v3qFfq xnIIQ/vP5DlTTeMETD2WH6zt5IEkxumn6Hu2c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HIWfXQz7kRZQ85ksmcAfNGtsJ5AkaWLd2ccGoBYRMog=; b=R/Giq4XmPtiDOfBATE4raEVBc4irdut1qx+qsH0K+eB73davbg3lF7jlxJBABMfmjb FU4ohmkkVlQyYpNQP5mp3ismB5zxm/SqE77KV/V1hDhVW85RkKZDC1DI/mC5Fk7tE8Le gqsOHhVBON6smkqhDIZyDYGH0SamcQsbRZ2lF8r6tI31O5RFAwgbI8myW8LOrGTxHIkK 6oiD3Xpcw/ck+ybSw6FhHUaPVEsuyk8Fsb/h8QcvqCzRSjXquckFv01rye7B8nnNL+zX GzPmUp96KqRfP8SVzNoYKLyeAfouFkKS0i8CWvVf1hnvpXDwOlsDYVN0msLxfNUSvz8U c+ug== X-Gm-Message-State: AOAM532GCUrYLInSFLm9YsL4rTLOI6aPBJR2IvnTkDW3YnHQczPt0beC eHEYF7irlCVeIiPo2bM5dUyldxqPC2s9aw== X-Google-Smtp-Source: ABdhPJzOSvJ7qQ/usfWdppzoDQ4Fg4ElPTDZYeZG0FTS0KGzry4GUEaG9GtO1d5nu+p06X9BjfI91g== X-Received: by 2002:a05:6a00:1145:b0:4f6:3ebc:a79b with SMTP id b5-20020a056a00114500b004f63ebca79bmr26952276pfm.41.1652304328166; Wed, 11 May 2022 14:25:28 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id i64-20020a628743000000b0051008603b66sm2196832pfe.219.2022.05.11.14.25.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 May 2022 14:25:27 -0700 (PDT) Date: Wed, 11 May 2022 14:25:26 -0700 From: Kees Cook To: Florian Weimer Cc: Andy Lutomirski , x86@kernel.org, LKML Subject: Re: [PATCH] x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE Message-ID: <202205111424.DEB0E3418@keescook> References: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org> <202205111104.464A6619@keescook> <87k0ardigv.fsf@oldenburg.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k0ardigv.fsf@oldenburg.str.redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 11, 2022 at 08:36:48PM +0200, Florian Weimer wrote: > * Kees Cook: > > > On Wed, May 11, 2022 at 10:38:53AM -0700, Andy Lutomirski wrote: > >> CONFIG_LEGACY_VSYSCALL_EMULATE is, as far as I know, only needed for the > >> combined use of exotic and outdated debugging mechanisms with outdated > >> binaries. At this point, no one should be using it. We would like to > >> implement dynamic switching of vsyscalls, but this is much more > >> complicated to support in EMULATE mode than XONLY mode. > >> > >> So let's force all the distros off of EMULATE mode. If anyone actually > >> needs it, they can set vsyscall=emulate, and we can then get away with > >> refusing to support newer security models if that option is set. > >> > >> Cc: x86@kernel.org > >> Cc: Kees Cook > >> Cc: Florian Weimer > >> Signed-off-by: Andy Lutomirski > > > > Sounds legit! Can we switch the default to "none" while we're at it? > > I think that's a userspace ABI break? > > I do not have a *very* strong opinion about this. For one thing, it > would be handy example to have that such deliberate do actually > happen. 8-) Right, I'm just suggesting switch the Kconfig default, so systems that don't care will get that setting, and systems that do care can still pick what they need. (But yes, a separate patch, etc) -- Kees Cook