Re: Removing EXPORT_SYMBOL(security_ops) (was Re: Time to remove LSM)

[Stephen Smalley <sds@tycho.nsa.gov>]

On Thu, 2006-04-20 at 09:46 -0700, Greg KH wrote:
> On Thu, Apr 20, 2006 at 12:34:57PM -0400, Stephen Smalley wrote:
> > On Thu, 2006-04-20 at 17:23 +0100, Christoph Hellwig wrote:
> > > On Thu, Apr 20, 2006 at 09:15:52AM -0700, Greg KH wrote:
> > > > On Thu, Apr 20, 2006 at 10:20:11AM -0400, Stephen Smalley wrote:
> > > > > On Thu, 2006-04-20 at 08:00 -0700, Greg KH wrote:
> > > > > > I agree.  In looking over the code some more, I'm trying to figure out
> > > > > > why we are exporting that variable at all.  Is it because of people
> > > > > > wanting to stack security modules?
> > > > > > 
> > > > > > I see selinux code using it, but you are always built into the kernel,
> > > > > > right?  So unexporting it would not be an issue to you.
> > > > > 
> > > > > Various in-tree modules (e.g. ext3) call security hooks via the static
> > > > > inlines and end up referencing security_ops directly.  We'd have to wrap
> > > > > all such hooks in the same manner as capable and permission.
> > > > 
> > > > Ah, and people like making their file systems as modules :(
> > > 
> > > But actually yes, calling into rndom lsm hooks in modules is not a good
> > > thing.a  The only think filesystems calls is security_inode_init_security
> > > and it would make a lot of sense to make that an out of line wrapper
> > > instead of exporting security_ops.
> > 
> > There are other cases as well, I think, e.g. af_unix calls certain hooks
> > to ensure mediation of even the abstract namespace.  But the problem is
> > avoided altogether if the security static inlines compile down to direct
> > selinux function calls (which can be exported as needed).
> 
> Of course it's "avoided alltogether" but we are not talking about
> dropping the whole LSM interface here right now.  I am wanting something
> that can go into 2.6.17 to fix this issue this week.

Ah, I see - didn't realize you were targeting 2.6.17 for this change.
In that case, your original proposal of just making it _GPL makes the
most sense for 2.6.17, and then look to introduce out of line wrappers
for all affected hooks (or remove LSM, if that is decided) later.

-- 
Stephen Smalley
National Security Agency

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