From patchwork Thu Mar 10 14:19:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 550389 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 5D7BBC41535 for ; Thu, 10 Mar 2022 14:33:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244732AbiCJOdu (ORCPT ); Thu, 10 Mar 2022 09:33:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343870AbiCJOb0 (ORCPT ); Thu, 10 Mar 2022 09:31:26 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADAB2C7EAE; Thu, 10 Mar 2022 06:27:44 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1F0B861C0A; Thu, 10 Mar 2022 14:27:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED9FEC340E8; Thu, 10 Mar 2022 14:27:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646922463; bh=YYTxn4Nwrg6CuOgCloYwoSlfT43YKOmCi0fRD30gcL8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PJ5Jv2w+Fp1bsklgCcfrd1qZEwgYUMXqr9UUEVAwuHBtEg7gRJtdUnnwclVvt9aYs yScyBXtlJhJEniKkrZeJ5LpeO6hOdh+EBd8wgeZxTSJg1PhA2fZUgTQUbmv+acVUSW Vc4pgUrL22ogZ2MRxCFj8Z5SrmwN88R0bIyf6c6Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Russell King (Oracle)" Subject: [PATCH 5.4 17/33] ARM: include unprivileged BPF status in Spectre V2 reporting Date: Thu, 10 Mar 2022 15:19:18 +0100 Message-Id: <20220310140809.250185790@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310140808.741682643@linuxfoundation.org> References: <20220310140808.741682643@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Russell King (Oracle) commit 25875aa71dfefd1959f07e626c4d285b88b27ac2 upstream. The mitigations for Spectre-BHB are only applied when an exception is taken, but when unprivileged BPF is enabled, userspace can load BPF programs that can be used to exploit the problem. When unprivileged BPF is enabled, report the vulnerable status via the spectre_v2 sysfs file. Signed-off-by: Russell King (Oracle) Signed-off-by: Greg Kroah-Hartman --- arch/arm/kernel/spectre.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/arch/arm/kernel/spectre.c +++ b/arch/arm/kernel/spectre.c @@ -1,9 +1,19 @@ // SPDX-License-Identifier: GPL-2.0-only +#include #include #include #include +static bool _unprivileged_ebpf_enabled(void) +{ +#ifdef CONFIG_BPF_SYSCALL + return !sysctl_unprivileged_bpf_disabled; +#else + return false +#endif +} + ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf) { @@ -31,6 +41,9 @@ ssize_t cpu_show_spectre_v2(struct devic if (spectre_v2_state != SPECTRE_MITIGATED) return sprintf(buf, "%s\n", "Vulnerable"); + if (_unprivileged_ebpf_enabled()) + return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); + switch (spectre_v2_methods) { case SPECTRE_V2_METHOD_BPIALL: method = "Branch predictor hardening";