From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chao Fan Subject: [PATCH v7 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory Date: Thu, 13 Sep 2018 18:46:26 +0800 Message-ID: <20180913104629.5179-1-fanc.fnst@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-efi@vger.kernel.org, linux-acpi@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, keescook@chromium.org, bhe@redhat.com Cc: rjw@rjwysocki.net, lenb@kernel.org, ard.biesheuvel@linaro.org, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com, Chao Fan List-Id: linux-acpi@vger.kernel.org ***Background: People reported that kaslr may randomly chooses some positions which are located in movable memory regions. This will break memory hotplug feature and make the movable memory chosen by KASLR can't be removed. ***Solutions: There should be a method to limit kaslr to choosing immovable memory regions, so there are 2 solutions: 1) Add a kernel parameter to specify the memory regions. 2) Get the information of memory hot-remove, then kaslr will know the right regions. In method 2, information about memory hot-remove is in ACPI tables, which will be parsed after start_kernel(), kaslr can't get the information. In method 1, users should know the regions address and specify in kernel parameter. In the earliest time, I tried to dig ACPI tabls to solve this problem. But I didn't splite the code in 'compressed/' and ACPI code, so the patch is hard to follow so refused by community. Somebody suggest to add a kernel parameter to specify the immovable memory so that limit kaslr in these regions. Then I make a new patchset. After several versions, Ingo gave a suggestion: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1634024.html Follow Ingo's suggestion, imitate the ACPI code to parse the acpi tables, so that the kaslr can get necessary memory information in ACPI tables. I think ACPI code is an independent part, so copy the codes and functions to 'compressed/' directory, so that kaslr won't influence the initialization of ACPI. PATCH 1/3 Add acpitb.c to provide functions to parse ACPI code. PATCH 2/3 If CONFIG_MEMORY_HOTREMOVE enabled, walk all nodes and store the information of immovable memory regions. PATCH 3/3 According to the immovable memory regions, filter the immovable regions which KASLR can choose. ***Test results: - I did a very simple test, and it can get the memory information in bios and efi KVM guest machine, and put it by early printk. But no more tests, so it's with RFC tag. v1->v2: - Simplify some code. Follow Baoquan He's suggestion: - Reuse the head file of acpi code. v2->v3: - Test in more conditions, so remove the 'RFC' tag. - Change some comments. v3->v4: Follow Thomas Gleixner's suggetsion: - Put the whole efi related function into #define CONFIG_EFI and return false in the other stub. - Simplify two functions in head file. v4->v5: Follow Dou Liyang's suggestion: - Add more comments about some functions based on kernel code. - Change some typo in comments. - Clean useless variable. - Add check for the boundary of array. - Add check for 'movable_node' parameter v5->v6: Follow Baoquan He's suggestion: - Change some log. - Add the check for acpi_rsdp - Change some code logical to make code clear v6->v7: Follow Rafael's suggestion: - Add more comments and patch log. Follow test robot's suggestion: - Add "static" tag for function Any comments will be welcome. Chao Fan (3): x86/boot: Add acpitb.c to parse acpi tables x86/boot/KASLR: Walk srat tables to filter immovable memory x86/boot/KASLR: Limit kaslr to choosing the immovable memory arch/x86/boot/compressed/Makefile | 4 + arch/x86/boot/compressed/acpitb.c | 401 ++++++++++++++++++++++++++++++ arch/x86/boot/compressed/kaslr.c | 76 +++++- arch/x86/boot/compressed/misc.h | 8 + 4 files changed, 478 insertions(+), 11 deletions(-) create mode 100644 arch/x86/boot/compressed/acpitb.c -- 2.17.1 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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 52D81C04ABB for ; Thu, 13 Sep 2018 10:46:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F19FE20861 for ; Thu, 13 Sep 2018 10:46:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F19FE20861 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cn.fujitsu.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727645AbeIMPzc (ORCPT ); Thu, 13 Sep 2018 11:55:32 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:18391 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726341AbeIMPzc (ORCPT ); Thu, 13 Sep 2018 11:55:32 -0400 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="44870101" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 13 Sep 2018 18:46:36 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (unknown [10.167.33.80]) by cn.fujitsu.com (Postfix) with ESMTP id 3F39F4B6EC66; Thu, 13 Sep 2018 18:46:37 +0800 (CST) Received: from localhost (10.167.225.56) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server id 14.3.408.0; Thu, 13 Sep 2018 18:46:42 +0800 From: Chao Fan To: , , , , , , , , CC: , , , , , Chao Fan Subject: [PATCH v7 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory Date: Thu, 13 Sep 2018 18:46:26 +0800 Message-ID: <20180913104629.5179-1-fanc.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain X-yoursite-MailScanner-ID: 3F39F4B6EC66.AE66D X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: fanc.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ***Background: People reported that kaslr may randomly chooses some positions which are located in movable memory regions. This will break memory hotplug feature and make the movable memory chosen by KASLR can't be removed. ***Solutions: There should be a method to limit kaslr to choosing immovable memory regions, so there are 2 solutions: 1) Add a kernel parameter to specify the memory regions. 2) Get the information of memory hot-remove, then kaslr will know the right regions. In method 2, information about memory hot-remove is in ACPI tables, which will be parsed after start_kernel(), kaslr can't get the information. In method 1, users should know the regions address and specify in kernel parameter. In the earliest time, I tried to dig ACPI tabls to solve this problem. But I didn't splite the code in 'compressed/' and ACPI code, so the patch is hard to follow so refused by community. Somebody suggest to add a kernel parameter to specify the immovable memory so that limit kaslr in these regions. Then I make a new patchset. After several versions, Ingo gave a suggestion: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1634024.html Follow Ingo's suggestion, imitate the ACPI code to parse the acpi tables, so that the kaslr can get necessary memory information in ACPI tables. I think ACPI code is an independent part, so copy the codes and functions to 'compressed/' directory, so that kaslr won't influence the initialization of ACPI. PATCH 1/3 Add acpitb.c to provide functions to parse ACPI code. PATCH 2/3 If CONFIG_MEMORY_HOTREMOVE enabled, walk all nodes and store the information of immovable memory regions. PATCH 3/3 According to the immovable memory regions, filter the immovable regions which KASLR can choose. ***Test results: - I did a very simple test, and it can get the memory information in bios and efi KVM guest machine, and put it by early printk. But no more tests, so it's with RFC tag. v1->v2: - Simplify some code. Follow Baoquan He's suggestion: - Reuse the head file of acpi code. v2->v3: - Test in more conditions, so remove the 'RFC' tag. - Change some comments. v3->v4: Follow Thomas Gleixner's suggetsion: - Put the whole efi related function into #define CONFIG_EFI and return false in the other stub. - Simplify two functions in head file. v4->v5: Follow Dou Liyang's suggestion: - Add more comments about some functions based on kernel code. - Change some typo in comments. - Clean useless variable. - Add check for the boundary of array. - Add check for 'movable_node' parameter v5->v6: Follow Baoquan He's suggestion: - Change some log. - Add the check for acpi_rsdp - Change some code logical to make code clear v6->v7: Follow Rafael's suggestion: - Add more comments and patch log. Follow test robot's suggestion: - Add "static" tag for function Any comments will be welcome. Chao Fan (3): x86/boot: Add acpitb.c to parse acpi tables x86/boot/KASLR: Walk srat tables to filter immovable memory x86/boot/KASLR: Limit kaslr to choosing the immovable memory arch/x86/boot/compressed/Makefile | 4 + arch/x86/boot/compressed/acpitb.c | 401 ++++++++++++++++++++++++++++++ arch/x86/boot/compressed/kaslr.c | 76 +++++- arch/x86/boot/compressed/misc.h | 8 + 4 files changed, 478 insertions(+), 11 deletions(-) create mode 100644 arch/x86/boot/compressed/acpitb.c -- 2.17.1