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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=no 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 D28E3C433DF for ; Mon, 22 Jun 2020 19:32:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5B6220776 for ; Mon, 22 Jun 2020 19:32:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="DooZtDOK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728767AbgFVTcJ (ORCPT ); Mon, 22 Jun 2020 15:32:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728588AbgFVTby (ORCPT ); Mon, 22 Jun 2020 15:31:54 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6BA4C061573 for ; Mon, 22 Jun 2020 12:31:53 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id i12so317110pju.3 for ; Mon, 22 Jun 2020 12:31:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=dNG40zysheY5oB4//u6Wgw3XPF1EPVf4SWmTm1L7IBk=; b=DooZtDOKEbuL4Lmq0EjvgBqtOhkWAVzaD4OoBh35ywAVTh+8jjPlVrIL5pPZ1PCtVX +7Qt9x93Bf6jWHUSYtMRAfTERsAnE8XlcUxfZu12iJaw18sHA1rR1SQN279dsa6bQ3wr FyhdWobCP/rLa3NIoSLGX9JY/N9OLOfKVoKSc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=dNG40zysheY5oB4//u6Wgw3XPF1EPVf4SWmTm1L7IBk=; b=XqvVdfW6N7PKQZROhBy9Kycafgv8/oaQAvqRHdxPiDU5UbHgmq/+y0WunyLc+p4mWi UhnEUtNh6CYdCC3Uwe1yweCHpxqKP6iaNnNol1SF7bqrwpMiLMuGpImikOzoLGSHUyqo dR1kkGyTzELMnNksLlJQVFARdU79OVltRa+3IRpfIQ+WXeuEySNB2yH83WkSrjKijM8G BKvPDTa9D/hd0SQFJO4OKxLxkqDZ8jEaEwU1H+oZ6NwvUxe3uc291f2WtUxMQzsqb7qY nBGfcXIj9IoxYAn9ZIMqn5hJBPTfMsMHE7JKESGLLYersYDzKiqRxO/DMzZjjuXr7UIP tUlw== X-Gm-Message-State: AOAM531rH1SVNg0aIwktI0erDUDY64+2jqOBiu7ElAcZ+Rt4lvH9MqKt PzeMJ9y8X9lYyIm4CsDneavSbw== X-Google-Smtp-Source: ABdhPJwzvg0AysINBE9mrBB80x8GFaUJiCmnxanMRMBRbZ6JfPpnLr9CRvHSZ2l6hQg9n7Rg0F4HWg== X-Received: by 2002:a17:90a:9f81:: with SMTP id o1mr19808289pjp.139.1592854313385; Mon, 22 Jun 2020 12:31:53 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q129sm13899450pfc.60.2020.06.22.12.31.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2020 12:31:50 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Alexander Popov , Ard Biesheuvel , Jann Horn , kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 0/5] Optionally randomize kernel stack offset each syscall Date: Mon, 22 Jun 2020 12:31:41 -0700 Message-Id: <20200622193146.2985288-1-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v4: - rebase to v5.8-rc2 v3: https://lore.kernel.org/lkml/20200406231606.37619-1-keescook@chromium.org/ v2: https://lore.kernel.org/lkml/20200324203231.64324-1-keescook@chromium.org/ rfc: https://lore.kernel.org/kernel-hardening/20190329081358.30497-1-elena.reshetova@intel.com/ Hi, This is a continuation and refactoring of Elena's earlier effort to add kernel stack base offset randomization. In the time since the previous discussions, two attacks[1][2] were made public that depended on stack determinism, so we're no longer in the position of "this is a good idea but we have no examples of attacks". :) Earlier discussions also devolved into debates on entropy sources, which is mostly a red herring, given the already low entropy available due to stack size. Regardless, entropy can be changed/improved separately from this series as needed. Earlier discussions also got stuck debating how much syscall overhead was too much, but this is also a red herring since the feature itself needs to be selectable at boot with no cost for those that don't want it: this is solved here with static branches. So, here is an improved version, made as arch-agnostic as possible, with usage added for x86 and arm64. It also includes some small static branch clean ups, and addresses some surprise performance issues due to the stack canary[3]. Note that for v5.8, this depends on this fix (due to how x86 changed its stack protector removal for syscall entry): https://lore.kernel.org/lkml/202006221201.3641ED037E@keescook/ Thanks! -Kees [1] https://a13xp0p0v.github.io/2020/02/15/CVE-2019-18683.html [2] https://repositorio-aberto.up.pt/bitstream/10216/125357/2/374717.pdf [3] https://lore.kernel.org/lkml/202003281520.A9BFF461@keescook/ Kees Cook (5): jump_label: Provide CONFIG-driven build state defaults init_on_alloc: Unpessimize default-on builds stack: Optionally randomize kernel stack offset each syscall x86/entry: Enable random_kstack_offset support arm64: entry: Enable random_kstack_offset support Makefile | 4 ++++ arch/Kconfig | 23 ++++++++++++++++++ arch/arm64/Kconfig | 1 + arch/arm64/kernel/Makefile | 5 ++++ arch/arm64/kernel/syscall.c | 10 ++++++++ arch/x86/Kconfig | 1 + arch/x86/entry/common.c | 11 +++++++++ include/linux/jump_label.h | 19 +++++++++++++++ include/linux/mm.h | 18 +++++--------- include/linux/randomize_kstack.h | 40 ++++++++++++++++++++++++++++++++ init/main.c | 23 ++++++++++++++++++ mm/page_alloc.c | 12 ++-------- 12 files changed, 145 insertions(+), 22 deletions(-) create mode 100644 include/linux/randomize_kstack.h -- 2.25.1