Re: [PATCH] crypto: testmgr - Improve randomization of params for AEAD fuzz testing

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Jul 29, 2019 at 04:10:06PM +0000, Pascal Van Leeuwen wrote:
> Hi Eric,
> 
> > -----Original Message-----
> > From: linux-crypto-owner@vger.kernel.org <linux-crypto-owner@vger.kernel.org> On Behalf Of
> > Pascal Van Leeuwen
> > Sent: Monday, July 29, 2019 11:11 AM
> > To: Eric Biggers <ebiggers@kernel.org>; Pascal van Leeuwen <pascalvanl@gmail.com>
> > Cc: linux-crypto@vger.kernel.org; herbert@gondor.apana.org.au; davem@davemloft.net
> > Subject: RE: [PATCH] crypto: testmgr - Improve randomization of params for AEAD fuzz
> > testing
> > 
> > Hi Eric,
> > 
> > Thanks for your feedback!
> > 
> > > -----Original Message-----
> > > From: Eric Biggers <ebiggers@kernel.org>
> > > Sent: Sunday, July 28, 2019 7:31 PM
> > > To: Pascal van Leeuwen <pascalvanl@gmail.com>
> > > Cc: linux-crypto@vger.kernel.org; herbert@gondor.apana.org.au; davem@davemloft.net;
> > Pascal Van Leeuwen
> > > <pvanleeuwen@verimatrix.com>
> > > Subject: Re: [PATCH] crypto: testmgr - Improve randomization of params for AEAD fuzz
> > testing
> > > >
> > > > +struct len_range_set {
> > > > +	const struct len_range_sel *lensel;
> > > > +	unsigned int count;
> > > > +};
> > > > +
> > > >  struct aead_test_suite {
> > > >  	const struct aead_testvec *vecs;
> > > >  	unsigned int count;
> > > >  };
> > > >
> > > > +struct aead_test_params {
> > > > +	struct len_range_set ckeylensel;
> > > > +	struct len_range_set akeylensel;
> > > > +	struct len_range_set authsizesel;
> > > > +	struct len_range_set aadlensel;
> > > > +	struct len_range_set ptxtlensel;
> > > > +};
> > > > +
> > > >  struct cipher_test_suite {
> > > >  	const struct cipher_testvec *vecs;
> > > >  	unsigned int count;
> > > > @@ -143,6 +156,10 @@ struct alg_test_desc {
> > > >  		struct akcipher_test_suite akcipher;
> > > >  		struct kpp_test_suite kpp;
> > > >  	} suite;
> > > > +
> > > > +	union {
> > > > +		struct aead_test_params aead;
> > > > +	} params;
> > > >  };
> > >
> > > Why not put these new fields in the existing 'struct aead_test_suite'?
> > >
> > > I don't see the point of the separate 'params' struct.  It just confuses things.
> > >
> > Mostly because I'm not that familiar with C datastructures (I'm not a programmer
> > and this is pretty much my first serious experience with C), so I didn't know how
> > to do that / didn't want to break anything else :-)
> > 
> > So if you can provide some example on how to do that ...
> > 
> Actually, while looking into some way to combine these fields into 
> 'struct aead_test_suite':  I really can't think of a way to do that that
> would be as convenient as the current approach which allows me to:
> 
> - NOT have these params for the other types (cipher, comp, hash etc.), at
>   least for now

> - NOT have to touch any declarations in the alg_test_desc assignment that
>   do not need this
> - conveniently use a macro line __LENS (idea shamelessly borrowed from
>   __VECS) to assign the struct ptr / list length fields pairs
> 
> If you know of a better way to achieve all that, then feel free to teach
> me. But, frankly I do not see why having 1 entry defining the testsuite 
> and  a seperate entry defining the fuzz test parameters would necessarily
> be confusing? Apart from 'params' perhaps not being a really good name, 
> being too generic and all, 'fuzz_params' would probably be better?
> 

Doesn't simply putting the fields in 'struct aead_test_suite' work?

The reason the current approach confuses me is that it's unclear what should go
in the aead_test_suite and what should go in the aead_test_params, both now and
in the future as people add new stuff.  They seem like the same thing to me.

- Eric