From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [PATCH v7 10/15] platform/x86: dell-smbios: add filtering capability for requests Date: Fri, 13 Oct 2017 15:18:32 +0100 Message-ID: <20171013151832.3ab0891d@alans-desktop> References: <83dc225624f1cde5ee1797aebc945732444ded91.1507733291.git.mario.limonciello@dell.com> <20171012110903.3ab4ed5e@alans-desktop> <1200feb837864baa8a3be9740413f2e9@ausx13mpc120.AMER.DELL.COM> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from www.llwyncelyn.cymru ([82.70.14.225]:52192 "EHLO fuzix.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753415AbdJMOTR (ORCPT ); Fri, 13 Oct 2017 10:19:17 -0400 In-Reply-To: <1200feb837864baa8a3be9740413f2e9@ausx13mpc120.AMER.DELL.COM> Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Mario.Limonciello@dell.com Cc: dvhart@infradead.org, andy.shevchenko@gmail.com, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, luto@kernel.org, quasisec@google.com, pali.rohar@gmail.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, greg@kroah.com > Within Linux the security model is that items accessible through this interface > are only accessible by root. "root" has not been a security concept in the Linux kernel since about 2.0. If you are relying on file permissions then at best you are using CAP_SYS_DAC which is too weak for this. If you are allowing near unchecked communication with a third party entity that the user doesn't trust too much you should be requiring CAP_SYS_RAWIO. In fact it's a fair argument hat if you require CAP_SYS_RAWIO and have a module option you have to set to allow it that with the module loaded with say insmod dell_smbios factory=1 does even blacklisted stuff then you are ok, because a process with CAP_SYS_RAWIO has enough power to totally own the machine anyway including taking over and doing the WMI call itself by hand in user space or loading its own module. Alan