From patchwork Wed Dec 6 12:35:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 120830 Delivered-To: patch@linaro.org Received: by 10.140.22.227 with SMTP id 90csp7001052qgn; Wed, 6 Dec 2017 04:37:52 -0800 (PST) X-Google-Smtp-Source: AGs4zMZQZlMRKOQM5TlBvG0WXew1nEn4Gki3IKWycWiz1qQdUA7zh+6ATfpE+eeKHQmUtg/xsY4I X-Received: by 10.101.100.199 with SMTP id t7mr21687960pgv.316.1512563871946; Wed, 06 Dec 2017 04:37:51 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1512563871; cv=none; d=google.com; s=arc-20160816; b=qBApizCNKvaamG2OgOcsfn7QwYo88N5/LZw7siW75M3ioysnSRpDPvXk83aNTi1nKv kLmRbifXH4vIOR4SFv/iQ26yDxhjcQ7ieJIAGAybTF+F7gDJmoCUdwskAsbWFnM7bXly DXajAbgHd4GeIOVsMNiJztRJygJaEbaI3QaEoDE7QU9oTjvWLzStMryUlqi4/uTkj50+ D2kWMb25aZLXi3JUABT5ana2q1hpHfqX1xATj32EkQFTTbE5H3iWwIMwXORxFTt5XN6l TbaiyIDZObfllTrrjCAl+b+ZIW1muO9VzCmKbhiUs/F1bzVhWafT7/iA/jqJGWYfU+EO En6g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=alp05x0m5Mlc2GcL6RyLGvmSzq+O1tmXi7Fc/XnMFog=; b=g3+CNMNYJC4ulfNNvQaT7QnuClhgscjkB99gXo/Kt4RvhuCusLc1Zsppu/Gqw6v/p2 Tif/iXqfKCBif0Rp5fSE4S+0p9G9lYNgFn/S6ZHPg8g+Zwk+FanKja1sHr9htPRaF+L5 LCdQ4wgAdEgGv044TYZG0roeME+NDJpriIyNUB3+T5IvKAXbQgyKv+PEkY6/kmKNAJPM 7+k9nOPV77WPRMRvNVvtlYJUZjZpKyqGH1SQdLpd+YHVM5h+Ew49nFUV2RpeqsgRMBs4 zl9njNPCkQO8h6p9nDe8+O842B4IGfr0Sk5mPlE+wTDDIh1OVG997eeoIZQZALLJco0B BLMw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id s59si1910014plb.232.2017.12.06.04.37.51; Wed, 06 Dec 2017 04:37:51 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752624AbdLFMhu (ORCPT + 28 others); Wed, 6 Dec 2017 07:37:50 -0500 Received: from foss.arm.com ([217.140.101.70]:34816 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752183AbdLFMgN (ORCPT ); Wed, 6 Dec 2017 07:36:13 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CBDBA174E; Wed, 6 Dec 2017 04:36:11 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9DE653F236; Wed, 6 Dec 2017 04:36:11 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 111891AE35FB; Wed, 6 Dec 2017 12:36:17 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, ard.biesheuvel@linaro.org, sboyd@codeaurora.org, dave.hansen@linux.intel.com, keescook@chromium.org, msalter@redhat.com, labbott@redhat.com, tglx@linutronix.de, Will Deacon Subject: [PATCH v3 17/20] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Date: Wed, 6 Dec 2017 12:35:36 +0000 Message-Id: <1512563739-25239-18-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1512563739-25239-1-git-send-email-will.deacon@arm.com> References: <1512563739-25239-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a Kconfig entry to control use of the entry trampoline, which allows us to unmap the kernel whilst running in userspace and improve the robustness of KASLR. Reviewed-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 13 +++++++++++++ 1 file changed, 13 insertions(+) -- 2.1.4 diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index fdcc7b9bb15d..3af1657fcac3 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -833,6 +833,19 @@ config FORCE_MAX_ZONEORDER However for 4K, we choose a higher default value, 11 as opposed to 10, giving us 4M allocations matching the default size used by generic code. +config UNMAP_KERNEL_AT_EL0 + bool "Unmap kernel when running in userspace (aka \"KAISER\")" + default y + help + Some attacks against KASLR make use of the timing difference between + a permission fault which could arise from a page table entry that is + present in the TLB, and a translation fault which always requires a + page table walk. This option defends against these attacks by unmapping + the kernel whilst running in userspace, therefore forcing translation + faults for all of kernel space. + + If unsure, say Y. + menuconfig ARMV8_DEPRECATED bool "Emulate deprecated/obsolete ARMv8 instructions" depends on COMPAT