Re: [PATCH (mmotm-2008-12-02-17-08)] Introducesecurity_path_set/clear() hooks.

From: Al Viro
Date: Sat Dec 06 2008 - 01:16:59 EST

On Fri, Dec 05, 2008 at 04:53:18PM -0500, Stephen Smalley wrote:
> > Right. Locations of inserting security_path_set()/security_path_clear() pairs
> > are subset of mnt_want_write()/mnt_drop_write() pairs. Thus, we can insert
> > security_path_set()/security_path_clear() pairs into
> > mnt_want_write()/mnt_drop_write() pairs, if we can tolerate performance
> > regression. According to our rough measurement, there is about 8 - 22% of
> > performance regression. But this approach needs minimum modification to the
> > existing kernel (only two hooks to be inserted).
> I assume you also need separate hooks to cover the read-only open case?
> As for your performance, your implementation of mp_* is clearly
> non-optimal, so I'd expect there is plenty of room for improvement
> there.

And just what will happen if you end up with foo_mkdir() calling something
that does e.g. pathname resolution in fs-controlled private namespace and
creates/removes some files there?
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