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=-0.9 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 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 26C57C2D0E7 for ; Wed, 25 Mar 2020 20:27:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0F532076F for ; Wed, 25 Mar 2020 20:27:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="V04eeOZm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727395AbgCYU1G (ORCPT ); Wed, 25 Mar 2020 16:27:06 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:39402 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727236AbgCYU1F (ORCPT ); Wed, 25 Mar 2020 16:27:05 -0400 Received: by mail-pl1-f195.google.com with SMTP id m1so1252719pll.6 for ; Wed, 25 Mar 2020 13:27:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=V04eeOZmpXZz9+n2K8s89RAUlNtFI2i3/IBt6L+R3HaP2VRpUcKrX06reMGWIzc2c+ XwtCJxYWfVvX423KhbuO1h44rQttz9YLq0WAz9cdrMlR19jmIZbXEYme+Erycyi1IU2U 88GPKoBsjo0xyDjf5T8gvQ6OIx9M3dosv2wAo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=HbjsVlx7XPkzyKEDrHNZxOgxe7jQTgopYwkXe00td2eV7e+Q+EX+iIYPwAqmsxvsBs IEakTM7O+JveXTk4xWuY3hxRw+LhNb+liHG6Uh5yGYaPLTNlRAmVvPRjD2kSWcQgU8mX R1I8ftfPOp/qI9Y7/svHmcd3n7Kl93pvEGWWZLLeMcOSK2LUIt+oRHgspt9qbYZiq103 TYCXM5C7V7x4kqLlb2dfFjCtGUGlfbVCI2v6wwmQ/fZoJt2af+sa660aO5R+OXvt2Mdp 0B6iPXuESRdyan36cJ1f6Y+G+eE6UbaQ8JohYg3JXTgY1ZYm5mMnbExXve/pX97h1sU3 sNvA== X-Gm-Message-State: ANhLgQ2b71pCsv+PLiLmsruh8OMqELF9e2JKpGnvimpUDNG0fiXiSxwK EvV80znhRMqMWfg9R1YgJmp5Gw== X-Google-Smtp-Source: ADFU+vswtN+46ClgfmDrS2YQ0+gwH0oaxyACQpe8SmgU+n/NeZSp3mJwpEGmc/BXB2B7g4eNvcGW5w== X-Received: by 2002:a17:902:fe97:: with SMTP id x23mr4918671plm.167.1585168024550; Wed, 25 Mar 2020 13:27:04 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id n22sm100777pjq.36.2020.03.25.13.27.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 13:27:03 -0700 (PDT) Date: Wed, 25 Mar 2020 13:27:02 -0700 From: Kees Cook To: "Reshetova, Elena" Cc: Jann Horn , Thomas Gleixner , the arch/x86 maintainers , Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Ard Biesheuvel , Kernel Hardening , "linux-arm-kernel@lists.infradead.org" , Linux-MM , kernel list Subject: Re: [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Message-ID: <202003251322.180F2536E@keescook> References: <20200324203231.64324-1-keescook@chromium.org> <202003241604.7269C810B@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 25, 2020 at 12:15:12PM +0000, Reshetova, Elena wrote: > > > Also, are you sure that it isn't possible to make the syscall that > > > leaked its stack pointer never return to userspace (via ptrace or > > > SIGSTOP or something like that), and therefore never realign its > > > stack, while keeping some controlled data present on the syscall's > > > stack? > > How would you reliably detect that a stack pointer has been leaked > to userspace while it has been in a syscall? Does not seem to be a trivial > task to me. Well, my expectation is that folks using this defense are also using panic_on_warn sysctl, etc, so attackers don't get a chance to actually _use_ register values spilled to dmesg. -- Kees Cook 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=-0.9 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 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 F401DC2D0E5 for ; Wed, 25 Mar 2020 20:27:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AE92820740 for ; Wed, 25 Mar 2020 20:27:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="V04eeOZm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE92820740 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 472FA6B000E; Wed, 25 Mar 2020 16:27:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4233B6B006C; Wed, 25 Mar 2020 16:27:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 338686B0070; Wed, 25 Mar 2020 16:27:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0174.hostedemail.com [216.40.44.174]) by kanga.kvack.org (Postfix) with ESMTP id 1B3266B000E for ; Wed, 25 Mar 2020 16:27:06 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 209D51803DCFE for ; Wed, 25 Mar 2020 20:27:06 +0000 (UTC) X-FDA: 76635018852.03.kiss00_3c50ae2fa00e X-HE-Tag: kiss00_3c50ae2fa00e X-Filterd-Recvd-Size: 4220 Received: from mail-pj1-f66.google.com (mail-pj1-f66.google.com [209.85.216.66]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Mar 2020 20:27:05 +0000 (UTC) Received: by mail-pj1-f66.google.com with SMTP id m15so1483991pje.3 for ; Wed, 25 Mar 2020 13:27:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=V04eeOZmpXZz9+n2K8s89RAUlNtFI2i3/IBt6L+R3HaP2VRpUcKrX06reMGWIzc2c+ XwtCJxYWfVvX423KhbuO1h44rQttz9YLq0WAz9cdrMlR19jmIZbXEYme+Erycyi1IU2U 88GPKoBsjo0xyDjf5T8gvQ6OIx9M3dosv2wAo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=o1jCsA5pPrcaTO9apHDPu6vh93BwUglrEj3KZC6LKyZDbw1k7bgxtjwzJGRXlS+Ucn I2A6HG7uaiZkSKu8BawaTgUTzaaaoKvHoCOxSznchIyBBNZRa3+fMc+bNB2OKj5zeWMU Ck7Yu3EYV5BVvpElmDw8g6Nq/LUmFD35+A6OTi5XnH418YwHtcI7SSY/Zcvp22rWU2cB C+WZ7sRm1drHCZeILQBLni/4o4GWpKXj582m2TLfyZZv+YHreF+cgJvrwOHzehYnbrPl P/ZLMtzwv8Njcly8IdYqqCEPl5n0PEQ/Ba4CayTcy4bCJA3C7pzaeNenaXHwUXikh8Pa 78cw== X-Gm-Message-State: ANhLgQ0WA4voINvouGzBRo/7fVR+7PFN703OQUupkYetsTGwJ/z43jDW 9Ktm5sd9b7TRnWDQAvIKW3ZNNQ== X-Google-Smtp-Source: ADFU+vswtN+46ClgfmDrS2YQ0+gwH0oaxyACQpe8SmgU+n/NeZSp3mJwpEGmc/BXB2B7g4eNvcGW5w== X-Received: by 2002:a17:902:fe97:: with SMTP id x23mr4918671plm.167.1585168024550; Wed, 25 Mar 2020 13:27:04 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id n22sm100777pjq.36.2020.03.25.13.27.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 13:27:03 -0700 (PDT) Date: Wed, 25 Mar 2020 13:27:02 -0700 From: Kees Cook To: "Reshetova, Elena" Cc: Jann Horn , Thomas Gleixner , the arch/x86 maintainers , Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Ard Biesheuvel , Kernel Hardening , "linux-arm-kernel@lists.infradead.org" , Linux-MM , kernel list Subject: Re: [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Message-ID: <202003251322.180F2536E@keescook> References: <20200324203231.64324-1-keescook@chromium.org> <202003241604.7269C810B@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 25, 2020 at 12:15:12PM +0000, Reshetova, Elena wrote: > > > Also, are you sure that it isn't possible to make the syscall that > > > leaked its stack pointer never return to userspace (via ptrace or > > > SIGSTOP or something like that), and therefore never realign its > > > stack, while keeping some controlled data present on the syscall's > > > stack? > > How would you reliably detect that a stack pointer has been leaked > to userspace while it has been in a syscall? Does not seem to be a trivial > task to me. Well, my expectation is that folks using this defense are also using panic_on_warn sysctl, etc, so attackers don't get a chance to actually _use_ register values spilled to dmesg. -- Kees Cook 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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 6F5C5C2D0E5 for ; Wed, 25 Mar 2020 20:27:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3FA332074D for ; Wed, 25 Mar 2020 20:27:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MmbfnPgj"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="V04eeOZm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FA332074D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Pxf+99ohQNE7199j/P6B7lw/d8CM5llngRWkHB1NaSA=; b=MmbfnPgjFaXrsM LC1FB1ObJHfmpZlRNPccDPdzpja3E5zrbjQvBqisM34zEFmEUrUtM3SgPS9TFhF+OYvXe/AnF5/TQ xowNd7LOaO6gtDdGRomqWR4csABLznd12k8IUGleN19M/PDIJp8sKP1BWCWY9menTQ8lfORG3QfGZ oGT4EREvS0Pabn2NNWbH9GywxSB+9D8uxisIKvlHdE0AkJdS15gxhZr0p69OiX6404roB66kSZm0o xN9gEK0Epxm3F52PkNY3LLwUhFQIEMXHZDWSdH6/APgXz8QVIR9xzh3GupLwp5IqykP8nBV1h3t2h UwpZN987D4/jZ/AiYm7w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHCcG-0004Qh-2V; Wed, 25 Mar 2020 20:27:08 +0000 Received: from mail-pl1-x641.google.com ([2607:f8b0:4864:20::641]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHCcD-0004QA-MS for linux-arm-kernel@lists.infradead.org; Wed, 25 Mar 2020 20:27:06 +0000 Received: by mail-pl1-x641.google.com with SMTP id h11so1242147plr.11 for ; Wed, 25 Mar 2020 13:27:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=V04eeOZmpXZz9+n2K8s89RAUlNtFI2i3/IBt6L+R3HaP2VRpUcKrX06reMGWIzc2c+ XwtCJxYWfVvX423KhbuO1h44rQttz9YLq0WAz9cdrMlR19jmIZbXEYme+Erycyi1IU2U 88GPKoBsjo0xyDjf5T8gvQ6OIx9M3dosv2wAo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6SzOvwdTQqkZQCjlviRpZUVdzAyX4BMCYO6WRGnsRMg=; b=qsw9XDvpb4HpphAbX6GgXxxKVW5D1h8mlH6Yb04MZoffc7KJyT/1gCNGHzQZw/VAKv mi/KojXfscY+P5sXLOMrmJGB3vpQ5EHlwlLMP02VUYJU/q7ZAScOkEecRM4RknI2SpAC wYnaNFiy8sq4yH6ZeF2KzxQsOgb018+gYVmBawdrQO4wqU9wY5d+EHMqv6Fa4Y0lsMKt IZSeoOyw+NUMo3+/EUc3LrtXIShaJ0lY238+ZR1REiodjqPjQ2Y+hSK7aCD8P3VHbHOL yPcxlDJhJYPwRIQxCft/D6zccs5NaRVr9FXYuFfzchceTSY7wu6n4PnC7HgbIh5gJFyk Bp8w== X-Gm-Message-State: ANhLgQ0kwlqUeQddb8pioQJ/uvFj15NZZlFLiYzYqYiPJlTIBmMK64RO r8cHwIhEY1BOgoXOxxlsjgNkwQ== X-Google-Smtp-Source: ADFU+vswtN+46ClgfmDrS2YQ0+gwH0oaxyACQpe8SmgU+n/NeZSp3mJwpEGmc/BXB2B7g4eNvcGW5w== X-Received: by 2002:a17:902:fe97:: with SMTP id x23mr4918671plm.167.1585168024550; Wed, 25 Mar 2020 13:27:04 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id n22sm100777pjq.36.2020.03.25.13.27.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 13:27:03 -0700 (PDT) Date: Wed, 25 Mar 2020 13:27:02 -0700 From: Kees Cook To: "Reshetova, Elena" Subject: Re: [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Message-ID: <202003251322.180F2536E@keescook> References: <20200324203231.64324-1-keescook@chromium.org> <202003241604.7269C810B@keescook> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200325_132705_736050_850AF31A X-CRM114-Status: GOOD ( 12.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Ard Biesheuvel , Jann Horn , Peter Zijlstra , Catalin Marinas , the arch/x86 maintainers , kernel list , Linux-MM , Alexander Potapenko , Andy Lutomirski , Kernel Hardening , Thomas Gleixner , Will Deacon , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Mar 25, 2020 at 12:15:12PM +0000, Reshetova, Elena wrote: > > > Also, are you sure that it isn't possible to make the syscall that > > > leaked its stack pointer never return to userspace (via ptrace or > > > SIGSTOP or something like that), and therefore never realign its > > > stack, while keeping some controlled data present on the syscall's > > > stack? > > How would you reliably detect that a stack pointer has been leaked > to userspace while it has been in a syscall? Does not seem to be a trivial > task to me. Well, my expectation is that folks using this defense are also using panic_on_warn sysctl, etc, so attackers don't get a chance to actually _use_ register values spilled to dmesg. -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel