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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 0246CC76195 for ; Tue, 16 Jul 2019 23:14:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE26F20880 for ; Tue, 16 Jul 2019 23:14:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388939AbfGPXOn (ORCPT ); Tue, 16 Jul 2019 19:14:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:43770 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728601AbfGPXOn (ORCPT ); Tue, 16 Jul 2019 19:14:43 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7A64B20880; Tue, 16 Jul 2019 23:14:41 +0000 (UTC) Date: Tue, 16 Jul 2019 19:14:39 -0400 From: Steven Rostedt To: Matthew Garrett Cc: jmorris@namei.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Matthew Garrett Subject: Re: [PATCH V35 27/29] tracefs: Restrict tracefs when the kernel is locked down Message-ID: <20190716191439.59a1ac32@gandalf.local.home> In-Reply-To: <20190715195946.223443-28-matthewgarrett@google.com> References: <20190715195946.223443-1-matthewgarrett@google.com> <20190715195946.223443-28-matthewgarrett@google.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Jul 2019 12:59:44 -0700 Matthew Garrett wrote: > Tracefs may release more information about the kernel than desirable, so > restrict it when the kernel is locked down in confidentiality mode by > preventing open(). > > Signed-off-by: Matthew Garrett > Cc: Steven Rostedt > --- > > @@ -389,6 +414,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode, > { > struct dentry *dentry; > struct inode *inode; > + struct file_operations *proxy_fops; Small nit, but please add this as the first declaration, to keep the "upside-down x-mas tree" look. I know some of the other functions in this file don't follow that (which should be cleaned up some day), but I'd like to avoid adding more that breaks the aesthetic of the code. > > if (!(mode & S_IFMT)) > mode |= S_IFREG; > @@ -402,8 +428,18 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode, > if (unlikely(!inode)) > return failed_creating(dentry); > > + proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL); > + if (!proxy_fops) > + return failed_creating(dentry); > + > + if (fops) I think you meant "if (!fops)". -- Steve > + fops = &tracefs_file_operations; > + > + dentry->d_fsdata = (void *)fops; > + memcpy(proxy_fops, fops, sizeof(*proxy_fops)); > + proxy_fops->open = default_open_file; > inode->i_mode = mode; > - inode->i_fop = fops ? fops : &tracefs_file_operations; > + inode->i_fop = proxy_fops; > inode->i_private = data; > d_instantiate(dentry, inode); > fsnotify_create(dentry->d_parent->d_inode, dentry);