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 98925C3065A for ; Mon, 3 Jul 2023 18:47:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230106AbjGCSrg (ORCPT ); Mon, 3 Jul 2023 14:47:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229662AbjGCSre (ORCPT ); Mon, 3 Jul 2023 14:47:34 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44D93E6B for ; Mon, 3 Jul 2023 11:47:32 -0700 (PDT) Received: by mail-pf1-x436.google.com with SMTP id d2e1a72fcca58-6686ef86110so2391010b3a.2 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=GBj6cOUt7xyLBaqb7+8yd7JuAzgXB6Yl82BqFd8jNFCpCueGjkYpf3KId9282s/2FW 5baZA3uL+7xMMCBln5+82DJg1Mfx/UkQU9kbVRPc2B4gGpaS9n9NMe+GxuZci87wvEKy D3WZXmcmRH/lxQ3QUwc33fYxIpPlzlAibtLn5hEKsVg62gCab2jKye8F+KKlpyXPNEnQ hgvRVJ6bY3KZhwnX8a8ebhZzxYYPtChAdV2TRIZLip8EVa1xud5CtafFpQnUtDKX5N5M uC3ENO0bHLN0Ft30XZR3wtACx8zl52ZGOB27K69LxiItsPEklf1/2cED7WGmIWMjaS7y 2YLQ== X-Gm-Message-State: AC+VfDyfDc4pkwMd/ZZGVnyx7hg667JshlQRYnAxNmyyo41UIUy0jYED /L5j7vDKYB0XuOYBxHWJC9CDYw== 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-kernel@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