From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760451Ab2DKOXd (ORCPT ); Wed, 11 Apr 2012 10:23:33 -0400 Received: from emvm-gh1-uea08.nsa.gov ([63.239.67.9]:10766 "EHLO nsa.gov" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760341Ab2DKOX3 (ORCPT ); Wed, 11 Apr 2012 10:23:29 -0400 X-TM-IMSS-Message-ID: Subject: Re: [PATCH v2] Add security.* XATTR support for the UBIFS From: Stephen Smalley To: Subodh Nijsure Cc: linux-mtd@lists.infradead.org, Artem Bityutskiy , Adrian Hunter , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Subodh Nijsure In-Reply-To: References: <1334015486-20616-1-git-send-email-snijsure@grid-net.com> <1334061985.23411.3.camel@moss-pluto> <1334149853.14296.29.camel@moss-pluto> Content-Type: text/plain; charset="UTF-8" Organization: National Security Agency Date: Wed, 11 Apr 2012 10:23:22 -0400 Message-ID: <1334154202.14296.58.camel@moss-pluto> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-04-11 at 07:12 -0700, Subodh Nijsure wrote: > On Wed, Apr 11, 2012 at 6:10 AM, Stephen Smalley wrote: > > On Wed, 2012-04-11 at 06:00 -0700, Subodh Nijsure wrote: > >> On Tue, Apr 10, 2012 at 5:46 AM, Stephen Smalley wrote: > >> > On Mon, 2012-04-09 at 16:51 -0700, subodh.nijsure@gmail.com wrote: > >> >> From: Subodh Nijsure > >> >> > >> >> Also fix couple of bugs in UBIFS extended attribute length calculation. > >> >> > >> >> Changes Since V1: > >> >> Instead of just handling security.selinux extended attribute handle > >> >> all security.* attributes. > >> >> > >> >> TESTING: Tested on MX28 based platforms using Micron MT29F2G08ABAEAH4 NAND > >> >> With these change we are able to label UBIFS filesystem with > >> >> security.selinux and run system with selinux enabled. > >> >> This change also allows one to set other security.* extended > >> >> attributesr, such as security.smack security.evm, security.ima > >> >> Ran integck test on UBI filesystem. > >> >> > >> >> Signed-off-by: Subodh Nijsure > >> >> --- > >> >> fs/ubifs/dir.c | 4 ++ > >> >> fs/ubifs/file.c | 6 ++ > >> >> fs/ubifs/journal.c | 12 +++- > >> >> fs/ubifs/super.c | 3 + > >> >> fs/ubifs/ubifs.h | 9 +++ > >> >> fs/ubifs/xattr.c | 147 ++++++++++++++++++++++++++++++++++++++++++++++++---- > >> >> 6 files changed, 167 insertions(+), 14 deletions(-) > >> >> > >> >> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c > >> >> index ec9f187..f4e06c4 100644 > >> >> --- a/fs/ubifs/dir.c > >> >> +++ b/fs/ubifs/dir.c > >> >> @@ -293,6 +293,7 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode, > >> >> ubifs_release_budget(c, &req); > >> >> insert_inode_hash(inode); > >> >> d_instantiate(dentry, inode); > >> >> + ubifs_init_security(dir, inode, &dentry->d_name); > >> >> return 0; > >> >> > >> >> out_cancel: > >> > > >> > The ubifs_init_security() should occur before d_instantiate() so that > >> > the inode is not accessible to other threads before its security > >> > attributes have been set. And if it fails, you would ideally drop the > >> > inode altogether and return an error to the creating process. > >> > > >> > >> I will look into moving ubifs_init_security() before d_instantiate(). > >> Last time I had tried I had run into some issues and had to keep > >> creating inode and then creating xattr as two seperate items. I will > >> look through the UBIFS code that actually creates xattr ubi nodes. > >> Also I will wait for couple of days to send v3 patch with to see if > >> mtd folks have other comments this patch. > > > > I'd favor moving the call to ubifs_init_security() inside of > > ubifs_new_inode() so that it gets done as part of all inode creation. > > To do that, you'll need to pass the &dentry->d_name (const struct qstr > > *) down to ubifs_new_inode(). But you can see that it is done that way > > for ext4_new_inode(), for example. > > > > -- > > Okay, I will look at that code little bit mode. > > UBIFS create_xattr() (fs/ubifs/xattr.c) calls ubifs_new_inode() so it > can get tricky if I want to create xattr in ubifs_new_inode(). > > Also noticed that UBIFS doesn't d_instantiate() inode entry created to > hold extended attribute, not certain if that would be an issue. > > I will look how other fs manage xattrs, I certainly don't want to > modify how UBIFS manages extended attributes. Oh, I missed the fact that ubifs xattrs are implemented as their own inodes. In that case, I guess you don't want to do what I said above, and your current approach is fine (aside from moving it up before d_instantiate and handling the error case). ext4 doesn't implement the xattr as a regular inode so that is different. -- Stephen Smalley National Security Agency