linux-kernel - Re: [PATCH] crypto: gcm - restrict assoclen for rfc4543

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Message-ID: <VI1PR04MB44451D12B66EE3FADA1ECE208CC80@VI1PR04MB4445.eurprd04.prod.outlook.com>
Date:   Thu, 18 Jul 2019 14:56:35 +0000
From:   Iuliana Prodan <iuliana.prodan@....com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
CC:     "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>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH] crypto: gcm - restrict assoclen for rfc4543

On 7/18/2019 5:46 PM, Herbert Xu wrote:
> On Thu, Jul 18, 2019 at 05:43:04PM +0300, Iuliana Prodan wrote:
>> Based on seqiv, IPsec ESP and rfc4543/rfc4106 the assoclen can be 16 or
>> 20 bytes.
>>
>> >From esp4/esp6, assoclen is sizeof IP Header. This includes spi, seq_no
>> and extended seq_no, that is 8 or 12 bytes.
>> In seqiv, to asscolen is added the IV size (8 bytes).
>> Therefore, the assoclen, for rfc4543, should be restricted to 16 or 20
>> bytes, as for rfc4106.
>>
>> Signed-off-by: Iuliana Prodan <iuliana.prodan@....com>
> 
> Why does this matter? Is it for the fuzz test?
> 
> Cheers,
> 

Yes, this is for fuzz testing.
The generic implementation for rfc4543 considers any assoclen valid, 
which is not correct.

Regards,
Iulia