linux-kernel - Re: [PATCH] crypto: talitos - fix skcipher failure due to wrong output IV

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Message-ID: <20190516023050.GA23200@sol.localdomain>
Date:   Wed, 15 May 2019 19:30:52 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Horia Geanta <horia.geanta@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] crypto: talitos - fix skcipher failure due to wrong
 output IV

On Wed, May 15, 2019 at 08:49:48PM +0200, Christophe Leroy wrote:
> 
> 
> Le 15/05/2019 à 16:05, Horia Geanta a écrit :
> > On 5/15/2019 3:29 PM, Christophe Leroy wrote:
> > > Selftests report the following:
> > > 
> > > [    2.984845] alg: skcipher: cbc-aes-talitos encryption test failed (wrong output IV) on test vector 0, cfg="in-place"
> > > [    2.995377] 00000000: 3d af ba 42 9d 9e b4 30 b4 22 da 80 2c 9f ac 41
> > > [    3.032673] alg: skcipher: cbc-des-talitos encryption test failed (wrong output IV) on test vector 0, cfg="in-place"
> > > [    3.043185] 00000000: fe dc ba 98 76 54 32 10
> > > [    3.063238] alg: skcipher: cbc-3des-talitos encryption test failed (wrong output IV) on test vector 0, cfg="in-place"
> > > [    3.073818] 00000000: 7d 33 88 93 0f 93 b2 42
> > > 
> > > This above dumps show that the actual output IV is indeed the input IV.
> > > This is due to the IV not being copied back into the request.
> > > 
> > > This patch fixes that.
> > > 
> > > Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> > Reviewed-by: Horia Geantă <horia.geanta@....com>
> 
> It's missing a Fixes: tag and a Cc: to stable.
> 
> I'll resend tomorrow.
> 
> > 
> > While here, could you please check ecb mode (which by definition does not have
> > an IV) is behaving correctly?
> > Looking in driver_algs[] list of crypto algorithms supported by talitos,
> > ecb(aes,des,3des) are declared with ivsize != 0.
> 
> According to /proc/crypto, test are passed for ecb.
> 

Did you try enabling CONFIG_CRYPTO_MANAGER_EXTRA_TESTS?  There is now a check
that the driver's ivsize matches the generic implementation's:

        if (ivsize != crypto_skcipher_ivsize(generic_tfm)) {
                pr_err("alg: skcipher: ivsize for %s (%u) doesn't match generic impl (%u)\n",
                       driver, ivsize, crypto_skcipher_ivsize(generic_tfm));
                err = -EINVAL;
                goto out;
        }

For ECB that means the ivsize must be 0.

AFAICS the talitos driver even accesses the IV for ECB, which is wrong; and the
only reason this isn't crashing the self-tests already is that they are confused
by the declared ivsize being nonzero so they don't pass NULL as they should.

- Eric