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 3C593C433F5 for ; Wed, 11 May 2022 18:37:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346397AbiEKShQ (ORCPT ); Wed, 11 May 2022 14:37:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346382AbiEKSg7 (ORCPT ); Wed, 11 May 2022 14:36:59 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D76C82F021 for ; Wed, 11 May 2022 11:36:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652294217; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Cne9kzq5J+wUhheKNYyc+FraBMO4jJvb9afeixc7QTk=; b=fkgbbUq+FXs793SRRGiQ2Ysu3q84ykd5C8pQCptCiO3UwAWJD3zr44Hazaphv/ca0bS7SF /CWGOXnNvGk7xnlVZIez3qIPiqzTat4UytSnqunI8DP2reV9+I8L+wj+ObByrJuCV1qPDc hKNPcLVF8TtekqID4CHPOE5jh13e5Kw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-172-7ee-hStvPHual-hKBg3ydQ-1; Wed, 11 May 2022 14:36:51 -0400 X-MC-Unique: 7ee-hStvPHual-hKBg3ydQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E5FA0185A794; Wed, 11 May 2022 18:36:50 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.194]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CEF1D40C1421; Wed, 11 May 2022 18:36:49 +0000 (UTC) From: Florian Weimer To: Kees Cook Cc: Andy Lutomirski , x86@kernel.org, LKML Subject: Re: [PATCH] x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE References: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org> <202205111104.464A6619@keescook> Date: Wed, 11 May 2022 20:36:48 +0200 In-Reply-To: <202205111104.464A6619@keescook> (Kees Cook's message of "Wed, 11 May 2022 11:04:55 -0700") Message-ID: <87k0ardigv.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * 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-) Thanks, Florian