From: Ard Biesheuvel <ardb@kernel.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)"
<linuxppc-dev@lists.ozlabs.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error)
Date: Thu, 21 Jan 2021 08:31:51 +0100 [thread overview]
Message-ID: <CAMj1kXHz8LdDgfOcifcB-MBMM9-TbymOU_psT3JBFQfyvQ=EjQ@mail.gmail.com> (raw)
In-Reply-To: <6b804eff-bc9f-5e05-d479-f398de4e2b30@csgroup.eu>
On Thu, 21 Jan 2021 at 06:35, Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
>
>
> Le 20/01/2021 à 23:23, Ard Biesheuvel a écrit :
> > On Wed, 20 Jan 2021 at 19:59, Christophe Leroy
> > <christophe.leroy@csgroup.eu> wrote:
> >>
> >> Talitos Security Engine AESU considers any input
> >> data size that is not a multiple of 16 bytes to be an error.
> >> This is not a problem in general, except for Counter mode
> >> that is a stream cipher and can have an input of any size.
> >>
> >> Test Manager for ctr(aes) fails on 4th test vector which has
> >> a length of 499 while all previous vectors which have a 16 bytes
> >> multiple length succeed.
> >>
> >> As suggested by Freescale, round up the input data length to the
> >> nearest 16 bytes.
> >>
> >> Fixes: 5e75ae1b3cef ("crypto: talitos - add new crypto modes")
> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> >
> > Doesn't this cause the hardware to write outside the given buffer?
>
>
> Only the input length is modified. Not the output length.
>
> The ERRATA says:
>
> The input data length (in the descriptor) can be rounded up to the nearest 16B. Set the
> data-in length (in the descriptor) to include X bytes of data beyond the payload. Set the
> data-out length to only output the relevant payload (don't need to output the padding).
> SEC reads from memory are not destructive, so the extra bytes included in the AES-CTR
> operation can be whatever bytes are contiguously trailing the payload.
So what happens if the input is not 16 byte aligned, and rounding it
up causes it to extend across a page boundary into a page that is not
mapped by the IOMMU/SMMU?
next prev parent reply other threads:[~2021-01-21 7:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 18:57 [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error) Christophe Leroy
2021-01-20 18:57 ` [PATCH 2/2] crypto: talitos - Fix ctr(aes) on SEC1 Christophe Leroy
2021-01-20 22:23 ` [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error) Ard Biesheuvel
2021-01-21 5:35 ` Christophe Leroy
2021-01-21 7:31 ` Ard Biesheuvel [this message]
2021-01-21 9:54 ` Christophe Leroy
2021-01-21 10:02 ` Ard Biesheuvel
2021-01-21 10:12 ` Christophe Leroy
2021-01-29 5:10 ` Herbert Xu
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