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=-3.7 required=3.0 tests=BAYES_00, 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 61161C433E6 for ; Thu, 4 Feb 2021 18:58:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 179CB64F59 for ; Thu, 4 Feb 2021 18:58:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239243AbhBDS5s (ORCPT ); Thu, 4 Feb 2021 13:57:48 -0500 Received: from mga09.intel.com ([134.134.136.24]:2119 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239410AbhBDS4d (ORCPT ); Thu, 4 Feb 2021 13:56:33 -0500 IronPort-SDR: OOLtcW5BNSMu6RWIunb+wEeiCXaWGZREjqp0sfGc8J2FRYMgY2l0sqoqJwuW0xXhZbRj+429cN CX/3NtrKOu5g== X-IronPort-AV: E=McAfee;i="6000,8403,9885"; a="181455269" X-IronPort-AV: E=Sophos;i="5.81,153,1610438400"; d="scan'208";a="181455269" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Feb 2021 10:55:43 -0800 IronPort-SDR: 9kuExkt4nlo9ze0QjfV35lBjvzzDxy7AIn6Rd/7Gtw34q0j+7KGDkY/Ai8mQRDq1jem7DKVmTh NU1MVdRLFXUQ== X-IronPort-AV: E=Sophos;i="5.81,153,1610438400"; d="scan'208";a="393322655" Received: from jguillor-mobl1.amr.corp.intel.com (HELO intel.com) ([10.252.133.14]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Feb 2021 10:55:42 -0800 Date: Thu, 4 Feb 2021 10:55:40 -0800 From: Ben Widawsky To: Dan Williams Cc: Konrad Rzeszutek Wilk , linux-cxl@vger.kernel.org, Linux ACPI , Linux Kernel Mailing List , linux-nvdimm , Linux PCI , Bjorn Helgaas , Chris Browy , Christoph Hellwig , Ira Weiny , Jon Masters , Jonathan Cameron , Rafael Wysocki , Randy Dunlap , Vishal Verma , daniel.lll@alibaba-inc.com, "John Groves (jgroves)" , "Kelley, Sean V" Subject: Re: [PATCH 13/14] cxl/mem: Add limited Get Log command (0401h) Message-ID: <20210204185540.oxwurggwd7a37a2o@intel.com> References: <20210130002438.1872527-1-ben.widawsky@intel.com> <20210130002438.1872527-14-ben.widawsky@intel.com> <20210201182848.GL197521@fedora> <20210202235103.v36v3znh5tsi4g5x@intel.com> <20210203171610.2y2x4krijol5dvkk@intel.com> 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-pci@vger.kernel.org On 21-02-03 12:31:00, Dan Williams wrote: > On Wed, Feb 3, 2021 at 10:16 AM Konrad Rzeszutek Wilk > wrote: > > > > On Wed, Feb 03, 2021 at 09:16:10AM -0800, Ben Widawsky wrote: > > > On 21-02-02 15:57:03, Dan Williams wrote: > > > > On Tue, Feb 2, 2021 at 3:51 PM Ben Widawsky wrote: > > > > > > > > > > On 21-02-01 13:28:48, Konrad Rzeszutek Wilk wrote: > > > > > > On Fri, Jan 29, 2021 at 04:24:37PM -0800, Ben Widawsky wrote: > > > > > > > The Get Log command returns the actual log entries that are advertised > > > > > > > via the Get Supported Logs command (0400h). CXL device logs are selected > > > > > > > by UUID which is part of the CXL spec. Because the driver tries to > > > > > > > sanitize what is sent to hardware, there becomes a need to restrict the > > > > > > > types of logs which can be accessed by userspace. For example, the > > > > > > > vendor specific log might only be consumable by proprietary, or offline > > > > > > > applications, and therefore a good candidate for userspace. > > > > > > > > > > > > > > The current driver infrastructure does allow basic validation for all > > > > > > > commands, but doesn't inspect any of the payload data. Along with Get > > > > > > > Log support comes new infrastructure to add a hook for payload > > > > > > > validation. This infrastructure is used to filter out the CEL UUID, > > > > > > > which the userspace driver doesn't have business knowing, and taints on > > > > > > > invalid UUIDs being sent to hardware. > > > > > > > > > > > > Perhaps a better option is to reject invalid UUIDs? > > > > > > > > > > > > And if you really really want to use invalid UUIDs then: > > > > > > > > > > > > 1) Make that code wrapped in CONFIG_CXL_DEBUG_THIS_IS_GOING_TO..? > > > > > > > > > > > > 2) Wrap it with lockdown code so that you can't do this at all > > > > > > when in LOCKDOWN_INTEGRITY or such? > > > > > > > > > > > > > > > > The commit message needs update btw as CEL is allowed in the latest rev of the > > > > > patches. > > > > > > > > > > We could potentially combine this with the now added (in a branch) CONFIG_RAW > > > > > config option. Indeed I think that makes sense. Dan, thoughts? > > > > > > > > Yeah, unknown UUIDs blocking is the same risk as raw commands as a > > > > vendor can trigger any behavior they want. A "CONFIG_RAW depends on > > > > !CONFIG_INTEGRITY" policy sounds reasonable as well. > > > > > > What about LOCKDOWN_NONE though? I think we need something runtime for this. > > > > > > Can we summarize the CONFIG options here? > > > > > > CXL_MEM_INSECURE_DEBUG // no change > > > CXL_MEM_RAW_COMMANDS // if !security_locked_down(LOCKDOWN_NONE) > > > > > > bool cxl_unsafe() > > > > Would it be better if this inverted? Aka cxl_safe().. > > ? > > > { > > > #ifndef CXL_MEM_RAW_COMMANDS > > nit use IS_ENABLED() if this function lives in a C file, or provide > whole alternate static inline versions in a header gated by ifdefs. > I had done this independently since... but agreed. > > > return false; > > > #else > > > return !security_locked_down(LOCKDOWN_NONE); > > > > :thumbsup: > > > > (Naturally this would inverted if this was cxl_safe()). > > > > > > > #endif > > > } > > > > > > --- > > > > > > Did I get that right? > > > > :nods: > > Looks good which means it's time to bikeshed the naming. I'd call it > cxl_raw_allowed(). As "safety" isn't the only reason for blocking raw, > it's also to corral the userspace api. I.e. things like enforcing > security passphrase material through the Linux keys api. It actually got pushed into cxl_mem_raw_command_allowed() static bool cxl_mem_raw_command_allowed(u16 opcode) { int i; if (!IS_ENABLED(CONFIG_CXL_MEM_RAW_COMMANDS)) return false; if (security_locked_down(LOCKDOWN_NONE)) return false; if (raw_allow_all) return true; if (is_security_command(opcode)) return false; for (i = 0; i < ARRAY_SIZE(disabled_raw_commands); i++) if (disabled_raw_commands[i] == opcode) return false; return true; } That work for you?