From patchwork Mon Jun 20 17:21:25 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 9188469 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 C3A826075E for ; Mon, 20 Jun 2016 18:30:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B6B0827C14 for ; Mon, 20 Jun 2016 18:30:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AB4A427C39; Mon, 20 Jun 2016 18:30:53 +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 284F927C14 for ; Mon, 20 Jun 2016 18:30:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754898AbcFTSav (ORCPT ); Mon, 20 Jun 2016 14:30:51 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:55687 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752630AbcFTSas (ORCPT ); Mon, 20 Jun 2016 14:30:48 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1bF36e-0004eC-Iy; Mon, 20 Jun 2016 11:35:28 -0600 Received: from 67-3-204-119.omah.qwest.net ([67.3.204.119] helo=x220.int.ebiederm.org) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1bF36d-0001hg-6b; Mon, 20 Jun 2016 11:35:27 -0600 From: "Eric W. Biederman" To: Linux Containers Cc: linux-fsdevel@vger.kernel.org, Miklos Szeredi , James Bottomley , Djalal Harouni , Seth Forshee , "Serge E. Hallyn" , Andy Lutomirski Date: Mon, 20 Jun 2016 12:21:25 -0500 Message-Id: <20160620172130.15712-8-ebiederm@xmission.com> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160620172130.15712-1-ebiederm@xmission.com> References: <87fus77pns.fsf@x220.int.ebiederm.org> <20160620172130.15712-1-ebiederm@xmission.com> X-XM-SPF: eid=1bF36d-0001hg-6b; ; ; mid=<20160620172130.15712-8-ebiederm@xmission.com>; ; ; hst=in01.mta.xmission.com; ; ; ip=67.3.204.119; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX18YqxsT6sv7ch5tmAZdcv6tfL5f4b+I664= X-SA-Exim-Connect-IP: 67.3.204.119 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH review 08/13] kernfs: The cgroup filesystem also benefits from SB_I_NOEXEC X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The cgroup filesystem is in the same boat as sysfs. No one ever permits executables of any kind on the cgroup filesystem, and there is no reasonable future case to support executables in the future. Therefore move the setting of SB_I_NOEXEC which makes the code proof against future mistakes of accidentally creating executables from sysfs to kernfs itself. Making the code simpler and covering the sysfs, cgroup, and cgroup2 filesystems. Acked-by: Seth Forshee Signed-off-by: "Eric W. Biederman" --- fs/kernfs/mount.c | 2 ++ fs/sysfs/mount.c | 3 +-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index d90d574c15a2..1443df670260 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -152,6 +152,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) struct dentry *root; info->sb = sb; + /* Userspace would break if executables appear on sysfs */ + sb->s_iflags |= SB_I_NOEXEC; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; sb->s_magic = magic; diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index f31e36994dfb..20b8f82e115b 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -41,8 +41,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type, if (IS_ERR(root) || !new_sb) kobj_ns_drop(KOBJ_NS_TYPE_NET, ns); else if (new_sb) - /* Userspace would break if executables appear on sysfs */ - root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC; + root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE; return root; }