linux-kernel - Re: integrity: nfsd imbalance bug fix

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Date:	Mon, 11 May 2009 16:09:12 -0400
From:	Eric Paris <eparis@...isplace.org>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, hooanon05@...oo.co.jp,
	jmorris@...ei.org, safford@...son.ibm.com,
	"J. Bruce Fields" <bfields@...ldses.org>,
	linux-nfs@...r.kernel.org, Eric Paris <eparis@...hat.com>
Subject: Re: integrity: nfsd imbalance bug fix

On Fri, May 8, 2009 at 1:35 PM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> On Wed, 2009-04-29 at 14:18 -0700, Andrew Morton wrote:
>> On Tue, 28 Apr 2009 14:32:14 -0400
>> Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:

>> > Index: security-testing-2.6/mm/shmem.c
>> > ===================================================================
>> > --- security-testing-2.6.orig/mm/shmem.c
>> > +++ security-testing-2.6/mm/shmem.c
>> > @@ -2680,7 +2680,7 @@ int shmem_zero_setup(struct vm_area_stru
>> >     if (IS_ERR(file))
>> >             return PTR_ERR(file);
>> >
>> > -   ima_shm_check(file);
>> > +   ima_opencount_get(file);
>> >     if (vma->vm_file)
>> >             fput(vma->vm_file);
>> >     vma->vm_file = file;
>>
>> Maybe do the IMA operations in (or under) shmem_file_setup() and
>> hugetlb_file_setup()?
>
> Again, that would hide the real issue of not having done integrity
> (permission) checking.

Where are we doing integrity or permission checks on hugetlb or shm
files?   Andrew's right, another example of this problem would be
drivers/gpu/drm/drm_gem.c::drm_get_object_alloc() (at least in
linux-next) which uses shmem_file_setup().  If we aren't doing
integrity checks on shmem already, why do we care about kernel vs.
non-kernel users?

moving the ima_opencount_get() from newseg down a layer into
*_file_setup() would, I think, have taken care of the drm case as
well.....

-Eric
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