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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 60B16C3F2D4 for ; Fri, 6 Mar 2020 06:42:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F8142084E for ; Fri, 6 Mar 2020 06:42:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726702AbgCFGmP (ORCPT ); Fri, 6 Mar 2020 01:42:15 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:11186 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726155AbgCFGmE (ORCPT ); Fri, 6 Mar 2020 01:42:04 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 4AFD3F8296F177E16BCD; Fri, 6 Mar 2020 14:42:01 +0800 (CST) Received: from huawei.com (10.175.124.28) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.439.0; Fri, 6 Mar 2020 14:41:52 +0800 From: Jason Yan To: , , , , , , , , , CC: , , , Jason Yan Subject: [PATCH v4 6/6] powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst and add 64bit part Date: Fri, 6 Mar 2020 14:40:33 +0800 Message-ID: <20200306064033.3398-7-yanaijie@huawei.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20200306064033.3398-1-yanaijie@huawei.com> References: <20200306064033.3398-1-yanaijie@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now we support both 32 and 64 bit KASLR for fsl booke. Add document for 64 bit part and rename kaslr-booke32.rst to kaslr-booke.rst. Signed-off-by: Jason Yan Cc: Scott Wood Cc: Diana Craciun Cc: Michael Ellerman Cc: Christophe Leroy Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Nicholas Piggin Cc: Kees Cook --- Documentation/powerpc/index.rst | 2 +- .../{kaslr-booke32.rst => kaslr-booke.rst} | 35 ++++++++++++++++--- 2 files changed, 32 insertions(+), 5 deletions(-) rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%) diff --git a/Documentation/powerpc/index.rst b/Documentation/powerpc/index.rst index 0d45f0fc8e57..3bad36943b22 100644 --- a/Documentation/powerpc/index.rst +++ b/Documentation/powerpc/index.rst @@ -20,7 +20,7 @@ powerpc hvcs imc isa-versions - kaslr-booke32 + kaslr-booke mpc52xx papr_hcalls pci_iov_resource_on_powernv diff --git a/Documentation/powerpc/kaslr-booke32.rst b/Documentation/powerpc/kaslr-booke.rst similarity index 59% rename from Documentation/powerpc/kaslr-booke32.rst rename to Documentation/powerpc/kaslr-booke.rst index 8b259fdfdf03..42121fed8249 100644 --- a/Documentation/powerpc/kaslr-booke32.rst +++ b/Documentation/powerpc/kaslr-booke.rst @@ -1,15 +1,18 @@ .. SPDX-License-Identifier: GPL-2.0 -=========================== -KASLR for Freescale BookE32 -=========================== +========================= +KASLR for Freescale BookE +========================= The word KASLR stands for Kernel Address Space Layout Randomization. This document tries to explain the implementation of the KASLR for -Freescale BookE32. KASLR is a security feature that deters exploit +Freescale BookE. KASLR is a security feature that deters exploit attempts relying on knowledge of the location of kernel internals. +KASLR for Freescale BookE32 +------------------------- + Since CONFIG_RELOCATABLE has already supported, what we need to do is map or copy kernel to a proper place and relocate. Freescale Book-E parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 @@ -38,5 +41,29 @@ bit of the entropy to decide the index of the 64M zone. Then we chose a kernstart_virt_addr + +KASLR for Freescale BookE64 +--------------------------- + +The implementation for Freescale BookE64 is similar as BookE32. One +difference is that Freescale BookE64 set up a TLB mapping of 1G during +booting. Another difference is that ppc64 needs the kernel to be +64K-aligned. So we can randomize the kernel in this 1G mapping and make +it 64K-aligned. This can save some code to creat another TLB map at early +boot. The disadvantage is that we only have about 1G/64K = 16384 slots to +put the kernel in:: + + KERNELBASE + + 64K |--> kernel <--| + | | | + +--+--+--+ +--+--+--+--+--+--+--+--+--+ +--+--+ + | | | |....| | | | | | | | | |....| | | + +--+--+--+ +--+--+--+--+--+--+--+--+--+ +--+--+ + | | 1G + |-----> offset <-----| + + kernstart_virt_addr + To enable KASLR, set CONFIG_RANDOMIZE_BASE = y. If KASLR is enable and you want to disable it at runtime, add "nokaslr" to the kernel cmdline. -- 2.17.2