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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76C45C001DD for ; Mon, 3 Jul 2023 18:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230189AbjGCSre (ORCPT ); Mon, 3 Jul 2023 14:47:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229914AbjGCSre (ORCPT ); Mon, 3 Jul 2023 14:47:34 -0400 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4689FE70 for ; Mon, 3 Jul 2023 11:47:32 -0700 (PDT) Received: by mail-pg1-x529.google.com with SMTP id 41be03b00d2f7-55b12286476so2367106a12.1 for ; Mon, 03 Jul 2023 11:47:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1688410052; x=1691002052; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=kN9o72g+S+fr453o45UGKHe2553NpYDOTlk2hs27c8U=; b=b9iCvxxHye8HsmgiBQdPV5wB3f1FHMfAOiUqp/E9CmOP7x6AhyW5/oynel97W2sEmn FvScJKeTY17iuoxKWd3fJHBDoV3jQ5VhDZhAiDH7gJxV6cBYtNcXXCFvQiJuShNtQGJA 4z03TR4FvqYVUbHwqT8AyLfVintdaAK9d5apw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688410052; x=1691002052; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=kN9o72g+S+fr453o45UGKHe2553NpYDOTlk2hs27c8U=; b=SLnqd4lorelrTp/UEnfmqvJ6KEQ4jVbWPjT2oDmv+YOQybxKn6L4yLwLHn1CBUt3K9 o6Wc5mdc7a+2LMnsIEdajpGMDy6rj9abN+gAKtjkSZKi5NRtV5reF79DT8wnC0HPif3m lbt451k6bHoDpDj3G6FDsv/9iIygCl1NHKxMkbuJplRWVLLwBYwsuzWkZyhGkfGcSbXv +9v7ImrvkHqN92XD7hhiUOd0n2bq5jsD1/W2LUBo+1Axk3ABncxnufFDyUrsM5aD9yXB 4+g2TXWYcyDEPPQ+W/y/psPoBZrox2/mzWub3gSiAsCk6dqxzYOE4DdmwawzKOj/921O 38bA== X-Gm-Message-State: AC+VfDwOqqr1rKkOSUvp09palnrpOPIWlCe12y7gXB34H4w0hlezuQA2 Xg4JpB5flSHz+OmjtumRadc/yw== X-Google-Smtp-Source: ACHHUZ7Uw6JIzie0IqBbLm1Jpta+I6oauYqzRMNr4YquzVcV9CbMBRcoIqPoHfkBX5hGG4i8DnEZeA== X-Received: by 2002:a05:6a20:6a0f:b0:126:f64b:668e with SMTP id p15-20020a056a206a0f00b00126f64b668emr11925154pzk.5.1688410051738; Mon, 03 Jul 2023 11:47:31 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id jf5-20020a170903268500b001b7eeffbdbfsm14742165plb.261.2023.07.03.11.47.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jul 2023 11:47:31 -0700 (PDT) Date: Mon, 3 Jul 2023 11:47:30 -0700 From: Kees Cook To: Jann Horn Cc: Roberto Sassu , Oleg Nesterov , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , Andrew Morton , Mimi Zohar , Casey Schaufler , David Howells , LuisChamberlain , Eric Biederman , Petr Tesarik , Christoph Hellwig , Petr Mladek , Peter Zijlstra , Thomas Gleixner , Tejun Heo , linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org, linux-integrity@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [QUESTION] Full user space process isolation? Message-ID: <202307031140.D52C63D46@keescook> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Mon, Jul 03, 2023 at 05:06:42PM +0200, Jann Horn wrote: > But I'm not convinced that it makes sense to try to draw a security > boundary between fully-privileged root (with the ability to mount > things and configure swap and so on) and the kernel - my understanding > is that some kernel subsystems don't treat root-to-kernel privilege > escalation issues as security bugs that have to be fixed. There are certainly arguments to be made about this, but efforts continue to provide a separation between full-cap uid 0 and kernel memory. LSMs like Lockdown, IMA, and LoadPin, for example, seek to close these gaps, and systems are designed with this bright line existing between kernel and root (e.g. Chrome OS). I'm sure there are gaps in attack surface coverage, but since work continues on this kind of hardening, I'd hate to knowingly create new attack surface. Providing uid 0 with kernel memory access should continue to be mediated by at least Lockdown, and if there are gaps in coverage, let's get them recorded[1] to be fixed. -Kees [1] https://github.com/KSPP/linux/issues -- Kees Cook