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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9727ACA9EAF for ; Sun, 27 Oct 2019 21:10:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 670E8214AF for ; Sun, 27 Oct 2019 21:10:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572210607; bh=1oMNMrK0NmsSeFiB3o1cyKQqEZTPEu/Oc6jImObE9eI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dhwBbJE41E60MIp74Df7Zw2y1GNW3CeWZwSnr3VsggCc1k+Tfx5hqQ0EhuU5Zh8Hv trrCncQRnBr9PR9Q0lC3mOlwcSPDRcWqOvWygEUuNkmL2B18wCa+HKaYmHARGSyvLu 6jFVFKcuXVmTMyVY5WBDA4o/VS4f//tYv4TgHlDw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729627AbfJ0VKG (ORCPT ); Sun, 27 Oct 2019 17:10:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:56492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729606AbfJ0VKF (ORCPT ); Sun, 27 Oct 2019 17:10:05 -0400 Received: from localhost (100.50.158.77.rev.sfr.net [77.158.50.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8E2732064A; Sun, 27 Oct 2019 21:10:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572210605; bh=1oMNMrK0NmsSeFiB3o1cyKQqEZTPEu/Oc6jImObE9eI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ieDndb3KckUAVpViXEHWp9PwkPUutUmzoAf6wfSC/Gdr0p8Qg3+LIDL0wo8jzEKvp lwhc7ZU5qcc3Cwjpk8gRdKYywL+JpvXopYJKglCJW08Mgtv3vMy9sNCLfnto5fYIKU Ds0JS89nMiRhOQUhdsBZjspVYiTICtX8pe7OZh2Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Jeremy Linton , Suzuki K Poulose , Andre Przywara , Catalin Marinas , Stefan Wahren , Will Deacon , Ard Biesheuvel Subject: [PATCH 4.14 073/119] arm64: add sysfs vulnerability show for meltdown Date: Sun, 27 Oct 2019 22:00:50 +0100 Message-Id: <20191027203339.394733907@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203259.948006506@linuxfoundation.org> References: <20191027203259.948006506@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jeremy Linton [ Upstream commit 1b3ccf4be0e7be8c4bd8522066b6cbc92591e912 ] We implement page table isolation as a mitigation for meltdown. Report this to userspace via sysfs. Signed-off-by: Jeremy Linton Reviewed-by: Suzuki K Poulose Reviewed-by: Andre Przywara Reviewed-by: Catalin Marinas Tested-by: Stefan Wahren Signed-off-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/cpufeature.c | 58 +++++++++++++++++++++++++++++++---------- 1 file changed, 44 insertions(+), 14 deletions(-) --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -824,7 +824,7 @@ static bool has_no_fpsimd(const struct a ID_AA64PFR0_FP_SHIFT) < 0; } -#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +static bool __meltdown_safe = true; static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, @@ -842,6 +842,16 @@ static bool unmap_kernel_at_el0(const st MIDR_ALL_VERSIONS(MIDR_CORTEX_A73), }; char const *str = "command line option"; + bool meltdown_safe; + + meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list); + + /* Defer to CPU feature registers */ + if (has_cpuid_feature(entry, scope)) + meltdown_safe = true; + + if (!meltdown_safe) + __meltdown_safe = false; /* * For reasons that aren't entirely clear, enabling KPTI on Cavium @@ -853,6 +863,19 @@ static bool unmap_kernel_at_el0(const st __kpti_forced = -1; } + /* Useful for KASLR robustness */ + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0) { + if (!__kpti_forced) { + str = "KASLR"; + __kpti_forced = 1; + } + } + + if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) { + pr_info_once("kernel page table isolation disabled by kernel configuration\n"); + return false; + } + /* Forced? */ if (__kpti_forced) { pr_info_once("kernel page table isolation forced %s by %s\n", @@ -860,18 +883,10 @@ static bool unmap_kernel_at_el0(const st return __kpti_forced > 0; } - /* Useful for KASLR robustness */ - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) - return true; - - /* Don't force KPTI for CPUs that are not vulnerable */ - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) - return false; - - /* Defer to CPU feature registers */ - return !has_cpuid_feature(entry, scope); + return !meltdown_safe; } +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static void kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) { @@ -896,6 +911,12 @@ kpti_install_ng_mappings(const struct ar return; } +#else +static void +kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) +{ +} +#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ static int __init parse_kpti(char *str) { @@ -909,7 +930,6 @@ static int __init parse_kpti(char *str) return 0; } early_param("kpti", parse_kpti); -#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused) { @@ -1056,7 +1076,6 @@ static const struct arm64_cpu_capabiliti .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = hyp_offset_low, }, -#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 { .desc = "Kernel page table isolation (KPTI)", .capability = ARM64_UNMAP_KERNEL_AT_EL0, @@ -1072,7 +1091,6 @@ static const struct arm64_cpu_capabiliti .matches = unmap_kernel_at_el0, .cpu_enable = kpti_install_ng_mappings, }, -#endif { /* FP/SIMD is not implemented */ .capability = ARM64_HAS_NO_FPSIMD, @@ -1629,3 +1647,15 @@ static int __init enable_mrs_emulation(v } core_initcall(enable_mrs_emulation); + +ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, + char *buf) +{ + if (__meltdown_safe) + return sprintf(buf, "Not affected\n"); + + if (arm64_kernel_unmapped_at_el0()) + return sprintf(buf, "Mitigation: PTI\n"); + + return sprintf(buf, "Vulnerable\n"); +}