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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	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>
Subject: Re: [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error)
Date: Thu, 21 Jan 2021 06:35:06 +0100	[thread overview]
Message-ID: <6b804eff-bc9f-5e05-d479-f398de4e2b30@csgroup.eu> (raw)
In-Reply-To: <CAMj1kXE7B05eAnR7KoDCym09Cw5qnzrV8KfNT2zJrko+mFic+w@mail.gmail.com>



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.

WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Ard Biesheuvel <ardb@kernel.org>
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 06:35:06 +0100	[thread overview]
Message-ID: <6b804eff-bc9f-5e05-d479-f398de4e2b30@csgroup.eu> (raw)
In-Reply-To: <CAMj1kXE7B05eAnR7KoDCym09Cw5qnzrV8KfNT2zJrko+mFic+w@mail.gmail.com>



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.

  reply	other threads:[~2021-01-21  5:41 UTC|newest]

Thread overview: 18+ 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 ` Christophe Leroy
2021-01-20 18:57 ` [PATCH 2/2] crypto: talitos - Fix ctr(aes) on SEC1 Christophe Leroy
2021-01-20 18:57   ` Christophe Leroy
2021-01-20 22:23 ` [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error) Ard Biesheuvel
2021-01-20 22:23   ` Ard Biesheuvel
2021-01-21  5:35   ` Christophe Leroy [this message]
2021-01-21  5:35     ` Christophe Leroy
2021-01-21  7:31     ` Ard Biesheuvel
2021-01-21  7:31       ` Ard Biesheuvel
2021-01-21  9:54       ` Christophe Leroy
2021-01-21  9:54         ` Christophe Leroy
2021-01-21 10:02         ` Ard Biesheuvel
2021-01-21 10:02           ` Ard Biesheuvel
2021-01-21 10:12           ` Christophe Leroy
2021-01-21 10:12             ` Christophe Leroy
2021-01-29  5:10 ` Herbert Xu
2021-01-29  5:10   ` Herbert Xu

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