Re: [PATCH v2] Add security.* XATTR support for the UBIFS

Stephen Smalley
2012-04-11T13:11:09Z

On Wed, 2012-04-11 at 06:00 -0700, Subodh Nijsure wrote:
> On Tue, Apr 10, 2012 at 5:46 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > On Mon, 2012-04-09 at 16:51 -0700, subodh.nijsure@gmail.com wrote:
> >> From: Subodh Nijsure <snijsure@grid-net.com>
> >>
> >> 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 <snijsure@grid-net.com>
> >> ---
> >> 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.