From patchwork Thu Nov 9 17:33:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 10051525 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 70517603FA for ; Thu, 9 Nov 2017 17:36:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 59E312B037 for ; Thu, 9 Nov 2017 17:36:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4EDB22B049; Thu, 9 Nov 2017 17:36:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CE05A2B037 for ; Thu, 9 Nov 2017 17:36:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753774AbdKIRdp (ORCPT ); Thu, 9 Nov 2017 12:33:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46266 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbdKIRdn (ORCPT ); Thu, 9 Nov 2017 12:33:43 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 99D1AC0587FF; Thu, 9 Nov 2017 17:33:43 +0000 (UTC) Received: from warthog.procyon.org.uk.com (ovpn-121-14.rdu2.redhat.com [10.10.121.14]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5CCC660C80; Thu, 9 Nov 2017 17:33:42 +0000 (UTC) From: David Howells To: linux-security-module@vger.kernel.org Cc: gnomes@lxorguk.ukuu.org.uk, linux-efi@vger.kernel.org, dhowells@redhat.com, linux-kernel@vger.kernel.org, jforbes@redhat.com Subject: [PATCH 24/30] debugfs: Disallow use of debugfs files when the kernel is locked down Date: Thu, 9 Nov 2017 17:33:41 +0000 Message-Id: <151024882152.28329.13943595155704545862.stgit@warthog.procyon.org.uk> Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 In-Reply-To: <151024863544.28329.2436580122759221600.stgit@warthog.procyon.org.uk> References: <151024863544.28329.2436580122759221600.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 09 Nov 2017 17:33:43 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Disallow opening of debugfs files when the kernel is locked down as various drivers give raw access to hardware through debugfs. Accesses to tracefs should use /sys/kernel/tracing/ rather than /sys/kernel/debug/tracing/. Possibly a symlink should be emplaced. Normal device interaction should be done through configfs or a miscdev, not debugfs. Note that this makes it unnecessary to specifically lock down show_dsts(), show_devs() and show_call() in the asus-wmi driver. Signed-off-by: David Howells cc: Andy Shevchenko cc: acpi4asus-user@lists.sourceforge.net cc: platform-driver-x86@vger.kernel.org cc: Matthew Garrett cc: Thomas Gleixner --- fs/debugfs/file.c | 6 ++++++ 1 file changed, 6 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 6dabc4a10396..32b5168a7e91 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -103,6 +103,9 @@ static int open_proxy_open(struct inode *inode, struct file *filp) const struct file_operations *real_fops = NULL; int srcu_idx, r; + if (kernel_is_locked_down("debugfs")) + return -EPERM; + r = debugfs_use_file_start(dentry, &srcu_idx); if (r) { r = -ENOENT; @@ -232,6 +235,9 @@ static int full_proxy_open(struct inode *inode, struct file *filp) struct file_operations *proxy_fops = NULL; int srcu_idx, r; + if (kernel_is_locked_down("debugfs")) + return -EPERM; + r = debugfs_use_file_start(dentry, &srcu_idx); if (r) { r = -ENOENT;