Re: [PATCH] kunit: Taint kernel if any tests run

[David Gow <davidgow@google.com>]

On Fri, Apr 29, 2022 at 3:09 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Fri, Apr 29, 2022 at 12:39:14PM +0800, David Gow wrote:
> > KUnit tests are not supposed to run on production systems: they may do
> > deliberately illegal things to trigger errors, and have security
> > implications (assertions will often deliberately leak kernel addresses).
> >
> > Add a new taint type, TAINT_KUNIT to signal that a KUnit test has been
> > run. This will be printed as 'N' (for kuNit, as K, U and T were already
> > taken).
> >
> > This should discourage people from running KUnit tests on production
> > systems, and to make it easier to tell if tests have been run
> > accidentally (by loading the wrong configuration, etc.)
> >
> > Signed-off-by: David Gow <davidgow@google.com>

< snip >

> > +     [ TAINT_KUNIT ]                 = { 'N', ' ', false },
>
> As kunit tests can be in modules, shouldn't this be "true" here?

Ah, good catch. While I tend to use either built-in tests (or modules
which are immediately unloaded), there are definitely some cases where
the tests are part of long-lasting modules.

I'll send out v2 with that changed.

> Overall, I like it, makes sense to me.  The "N" will take some getting
> used to, and I have no idea why "T" was for "struct randomization", that
> would have allowed you to use "T" instead.  Oh well.

Yeah, 'T' would've been nice, but I doubt it'd be worth trying to
change it now. At least we haven't had to resort to emoji...

Adding an actual name as Jani suggested would be a good idea, IMHO,
though obviously best done in a separate patch.


Cheers,
-- David