From nobody Fri May 8 03:49:55 2026 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 DA03AC433EF for ; Wed, 11 May 2022 19:48:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345915AbiEKTsb (ORCPT ); Wed, 11 May 2022 15:48:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347374AbiEKTsH (ORCPT ); Wed, 11 May 2022 15:48:07 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65997F61C1; Wed, 11 May 2022 12:47:50 -0700 (PDT) Date: Wed, 11 May 2022 19:47:47 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1652298468; h=from:from:sender:sender:reply-to: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=1FrofJeH8+YlqGe3v/PhOdED1A/YchY+wAkMIrlJCJ4=; b=hk/2qcXifHKCqHGexFklQ1FwBKHZXXqUbyaLZp84SXfsSmf13za2IFx0yMX//ASFz9e0n+ Q4rxmiB/nFZHtBOWK4/XMOhPuFjW2IeQyhGcdsuJaJrWsS8ktxDAD3gpV5V/ShhM25C15W lM6CeqnJqsCplJD5OkgPW6s5LRdzboZc/fEJ9ZmKPuaXFqu4DtrBZ/O+irDgJ5qm+T7PA5 60ujGeNSHbXqb5G0Klp3drt3+0rvGAdAwch72WwK8ELQnEv1jGeq5CKbxNsY3F/sjiuK3M cp6CkL/70H+LxZGnb/vaTSzB1bCnh7oGkp0GFzdufQU4cbjHpMcbV+EYq3J1lA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1652298468; h=from:from:sender:sender:reply-to: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=1FrofJeH8+YlqGe3v/PhOdED1A/YchY+wAkMIrlJCJ4=; b=E65oVB2yTCkkzgnqAy/OX3yqKsde+HubQCIwaJ2lFWfiJ6FEoflsNU5YOWBPDcunOevLcv NmBoGzmYTWVdNOAA== From: "tip-bot2 for Andy Lutomirski" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/vdso] x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE Cc: Andy Lutomirski , Borislav Petkov , Kees Cook , Florian Weimer , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org> References: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org> MIME-Version: 1.0 Message-ID: <165229846773.4207.18182599891283244875.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/vdso branch of tip: Commit-ID: bf00745e7791fe2ba7941aeead8528075a158bbe Gitweb: https://git.kernel.org/tip/bf00745e7791fe2ba7941aeead8528075= a158bbe Author: Andy Lutomirski AuthorDate: Wed, 11 May 2022 10:38:53 -07:00 Committer: Borislav Petkov CommitterDate: Wed, 11 May 2022 20:39:31 +02:00 x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE 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. Eventually, dynamic switching of vsyscalls will be implemented, 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=3Demulate, and the kernel can then get away with refusing to support newer security models if that option is set. [ bp: Remove "we"s. ] Signed-off-by: Andy Lutomirski Signed-off-by: Borislav Petkov Reviewed-by: Kees Cook Acked-by: Florian Weimer Link: https://lore.kernel.org/r/898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.16= 52290558.git.luto@kernel.org --- arch/x86/Kconfig | 18 +++--------------- arch/x86/entry/vsyscall/vsyscall_64.c | 2 +- 2 files changed, 4 insertions(+), 16 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4bed3ab..68c6696 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2326,7 +2326,9 @@ choice it can be used to assist security vulnerability exploitation. =20 This setting can be changed at boot time via the kernel command - line parameter vsyscall=3D[emulate|xonly|none]. + line parameter vsyscall=3D[emulate|xonly|none]. Emulate mode + is deprecated and can only be enabled using the kernel command + line. =20 On a system with recent enough glibc (2.14 or newer) and no static binaries, you can say None without a performance penalty @@ -2334,20 +2336,6 @@ choice =20 If unsure, select "Emulate execution only". =20 - config LEGACY_VSYSCALL_EMULATE - bool "Full emulation" - help - The kernel traps and emulates calls into the fixed vsyscall - address mapping. This makes the mapping non-executable, but - it still contains readable known contents, which could be - used in certain rare security vulnerability exploits. This - configuration is recommended when using legacy userspace - that still uses vsyscalls along with legacy binary - instrumentation tools that require code to be readable. - - An example of this type of legacy userspace is running - Pin on an old binary that still uses vsyscalls. - config LEGACY_VSYSCALL_XONLY bool "Emulate execution only" help diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscal= l/vsyscall_64.c index fd2ee94..4af81df 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -48,7 +48,7 @@ static enum { EMULATE, XONLY, NONE } vsyscall_mode __ro_a= fter_init =3D #elif defined(CONFIG_LEGACY_VSYSCALL_XONLY) XONLY; #else - EMULATE; + #error VSYSCALL config is broken #endif =20 static int __init vsyscall_setup(char *str)