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[217.165.113.120]) by smtp.gmail.com with ESMTPSA id e67sm1470295wmg.1.2019.02.11.15.28.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Feb 2019 15:28:13 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa Cc: Igor Stoppa , Andy Lutomirski , Nadav Amit , Matthew Wilcox , Peter Zijlstra , Kees Cook , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v4 03/12] __wr_after_init: x86_64: randomize mapping offset Date: Tue, 12 Feb 2019 01:27:40 +0200 Message-Id: <378ee1e7e4c17e3bf6e49e1fb6c7cd9abd18ccfe.1549927666.git.igor.stoppa@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: References: Reply-To: Igor Stoppa MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org x86_64 specialized way of defining the base address for the alternate mapping used by write-rare. Since the kernel address space spans across 64TB and it is mapped into a used address space of 128TB, the kernel address space can be shifted by a random offset that is up to 64TB and page aligned. This is accomplished by providing arch-specific version of the function __init_wr_base() Signed-off-by: Igor Stoppa CC: Andy Lutomirski CC: Nadav Amit CC: Matthew Wilcox CC: Peter Zijlstra CC: Kees Cook CC: Dave Hansen CC: Mimi Zohar CC: Thiago Jung Bauermann CC: Ahmed Soliman CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- arch/x86/mm/Makefile | 2 ++ arch/x86/mm/prmem.c (new) | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index 4b101dd6e52f..66652de1e2c7 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -53,3 +53,5 @@ obj-$(CONFIG_PAGE_TABLE_ISOLATION) += pti.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_identity.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_boot.o + +obj-$(CONFIG_PRMEM) += prmem.o diff --git a/arch/x86/mm/prmem.c b/arch/x86/mm/prmem.c new file mode 100644 index 000000000000..b04fc03f92fb --- /dev/null +++ b/arch/x86/mm/prmem.c @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * prmem.c: Memory Protection Library - x86_64 backend + * + * (C) Copyright 2018-2019 Huawei Technologies Co. Ltd. + * Author: Igor Stoppa + */ + +#include +#include + +unsigned long __init __init_wr_base(void) +{ + /* + * Place 64TB of kernel address space within 128TB of user address + * space, at a random page aligned offset. + */ + return (((unsigned long)kaslr_get_random_long("WR Poke")) & + PAGE_MASK) % (64 * _BITUL(40)); +} -- 2.19.1