From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751265AbeBTVfd (ORCPT ); Tue, 20 Feb 2018 16:35:33 -0500 Received: from mail-io0-f181.google.com ([209.85.223.181]:37885 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710AbeBTVfc (ORCPT ); Tue, 20 Feb 2018 16:35:32 -0500 X-Google-Smtp-Source: AG47ELuJtsNCJGeYzP+HQ1Oz9Nv9gWIiXTXBJn13NL4r/Jjjnd9tBlCZg4i77PZC7MyZGRMYfKHA88NEFuUPQt0l9MM= MIME-Version: 1.0 References: <20180215182208.35003-1-joe.konno@linux.intel.com> <20180215182208.35003-2-joe.konno@linux.intel.com> <6680a760-eb30-4daf-2dad-a9628f1c15a8@kernel.org> <20180220211849.fqjb6rdmypl6opir@agluck-desk> <20180220213246.43y2vbiiikqyx2ys@agluck-desk> In-Reply-To: <20180220213246.43y2vbiiikqyx2ys@agluck-desk> From: Matthew Garrett Date: Tue, 20 Feb 2018 21:35:20 +0000 Message-ID: Subject: Re: [PATCH 1/2] fs/efivarfs: restrict inode permissions To: tony.luck@intel.com Cc: Linus Torvalds , joe.konno@linux.intel.com, linux-efi , Linux Kernel Mailing List , Ard Biesheuvel , matthew.garrett@nebula.com, jk@ozlabs.org, ak@linux.intel.com, pjones@redhat.com, luto@kernel.org, James Bottomley Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 20, 2018 at 1:32 PM Luck, Tony wrote: > The immediate problem is the denial of service attack. I have > a nagging worry that allowing a user to cause an SMI at a precise > time might also be a problem. But I don't know how that could be > leveraged in some other attack. The thing that worries me here is that if it's possible for root to potentially attack the kernel then just changing the permissions is still allowing an escalation of privilege. The other approaches would also block this.