Re: [RFC][PATCH 11/11] security: AppArmor - Export namespace semaphore

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

On Thu, 2006-04-20 at 08:48 -0400, Stephen Smalley wrote:
> On Thu, 2006-04-20 at 08:21 -0500, Serge E. Hallyn wrote:
> > Tony, do you have any performance measurements?  Both for unconfined and
> > confined apps?  Presumably unconfined processes should have 0 performance
> > hit, right?
> 
> Preferably something that exercises open, mkdir, link... and friends
> intensively, not just the old WebStone data that I've seen posted
> before.  
> 
> But you don't really need the benchmarks - just look at the code, and
> think about the implications of allocating a page and calling d_path on
> every permission(9) call (on every component) plus from the separate
> hooks in the vfs_ helpers and further consider the impact of taking the
> dcache lock all the time there.  And look at the iterators being used in
> aa_perm_dentry as well as the truly fun ones in aa_link.  All because
> they are doing it from LSM hooks that were never intended to be used
> this way.

Ah, I have to correct the above - the mask filtering skips directory
traversal checking, so not every component I suppose.  Which is
interesting for another reason.  But performance situation still looks
fairly bad from a code POV, and the existing hooks still seem to be the
wrong place for this kind of processing/checking.

-- 
Stephen Smalley
National Security Agency

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