Re: [RFC][PATCH] ima: fix lockdep circular locking dependency

[Eric Paris <eparis@redhat.com>]

On Wed, 2011-11-16 at 15:24 -0500, Mimi Zohar wrote:
> On Wed, 2011-11-16 at 12:27 -0500, Eric Paris wrote:

> > > +int ima_file_premmap(struct file *file, unsigned long prot)
> > > +{
> > > +	int rc;
> > > +
> > > +	if (!file)
> > > +		return 0;
> > > +	if (prot & PROT_EXEC)
> > > +		rc = process_measurement(file, file->f_dentry->d_name.name,
> > > +					 MAY_EXEC, FILE_PREMMAP);
> > > +	return 0;
> > > +}
> > 
> > Here lets call the helper above, but instead of FILE_PREMMAP, lets use
> > the correct FILE_MMAP or FILE_BPRM, which is going to have to come as a
> > third argument, right?
> 
> Ok, thanks for the review.

Actually it just dawned on me, that what I think we really learned here
is that we have the hooks in the wrong place.  If we are going to
sprinkle the code with ima_file_premmap() maybe we should just actually
do ALL of the work in this new hook?  Throw the security_file_mmap() IMA
hook out the window and just actually do the whole process_measurement()
work in this new hook?    You'll have to see if that's better.  But it
sucks to allocate an object just to have to look it up 100 instructions
later.  Why not just do the work when we do the allocation and not come
back a second time?

-Eric