netdev - Re: [PATCH v4 1/1] net: fastopen: robustness and endianness fixes for SipHash

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Date:   Sat, 22 Jun 2019 16:30:51 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     ard.biesheuvel@...aro.org
Cc:     netdev@...r.kernel.org, ebiggers@...nel.org,
        linux-crypto@...r.kernel.org, herbert@...dor.apana.org.au,
        edumazet@...gle.com, kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        jbaron@...mai.com, cpaasch@...le.com, David.Laight@...lab.com,
        ycheng@...gle.com
Subject: Re: [PATCH v4 1/1] net: fastopen: robustness and endianness fixes
 for SipHash

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Date: Wed, 19 Jun 2019 23:46:28 +0200

> Some changes to the TCP fastopen code to make it more robust
> against future changes in the choice of key/cookie size, etc.
> 
> - Instead of keeping the SipHash key in an untyped u8[] buffer
>   and casting it to the right type upon use, use the correct
>   type directly. This ensures that the key will appear at the
>   correct alignment if we ever change the way these data
>   structures are allocated. (Currently, they are only allocated
>   via kmalloc so they always appear at the correct alignment)
> 
> - Use DIV_ROUND_UP when sizing the u64[] array to hold the
>   cookie, so it is always of sufficient size, even if
>   TCP_FASTOPEN_COOKIE_MAX is no longer a multiple of 8.
> 
> - Drop the 'len' parameter from the tcp_fastopen_reset_cipher()
>   function, which is no longer used.
> 
> - Add endian swabbing when setting the keys and calculating the hash,
>   to ensure that cookie values are the same for a given key and
>   source/destination address pair regardless of the endianness of
>   the server.
> 
> Note that none of these are functional changes wrt the current
> state of the code, with the exception of the swabbing, which only
> affects big endian systems.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>

Applied, thank you.