linux-kernel - Re: IMA: How to manage user space signing policy with others

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Date:	Thu, 7 Mar 2013 10:53:43 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	Eric Paris <eparis@...isplace.org>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>
Subject: Re: IMA: How to manage user space signing policy with others

On Thu, Mar 07, 2013 at 10:40:33AM -0500, Mimi Zohar wrote:
> On Thu, 2013-03-07 at 09:36 -0500, Vivek Goyal wrote:
> > On Wed, Mar 06, 2013 at 08:39:08PM -0500, Mimi Zohar wrote:
> > > On Wed, 2013-03-06 at 18:55 -0500, Vivek Goyal wrote:
> > > > On Wed, Mar 06, 2013 at 10:42:31AM -0500, Mimi Zohar wrote:
> >  
> > > Adding an IMA call to directly appraise the integrity of a file, rather
> > > than adding a hook, prevents other integrity users from being able to
> > > define a rule at that point.
> > 
> > We already have security hooks in exec() code and mmap(). And current
> > integrity callers are happy with it.
> 
> Exposing integrity calls, resolves the problem of code duplication, but
> does not address Rusty's third issue of improving the integrity
> subsystem.

I thought rusty wanted me to reuse existing integrity code so that there
is no code duplication. And improve things as needed int the process
so meet new requirements.

And exposing functions calls will just do that. Improve IMA so that
more people can reuse the same code without breaking existing users.

Other improvements will be to improve "cpio" to support xattr and
figure a way out to chain into secureboot root of trust and load
only trusted keys.

So yes, I am improving IMA subsystem. Only thing I am arguing against
that I don't think trying to enahnce policy based interface is right
thing to do here in the light of new requirements. It just makes IMA too
complicated and it is not worth it.

>  You have no idea if the existing integrity users are happy
> with the status quo.

If nobody is speaking then I have to assume something. If they are happy,
great, exposing new functions are not going to break any of their
functionality. If they are not happy then there is more reason to believe
that trying to enahance policy based interface is a bad thing. It is not
working.

>  It's there and they're using it.  They could want
> additional hooks or better located hooks.  Each of your complaints about
> the integrity subsystem could be addressed and would improve the
> subsystem.

If they want better located hooks, they are more than welcome to put
it. Exposing some of the functions does not prevent it. They want
to improve IMA subsystem, sure, why not. Exposing some fucntions
does not prevent it.

Thanks
Vivek
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