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From: David Laight <David.Laight@ACULAB.COM>
To: "'Jason A. Donenfeld'" <Jason@zx2c4.com>,
        Netdev <netdev@vger.kernel.org>, David Miller <davem@davemloft.net>,
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        Andy Lutomirski <luto@amacapital.net>,
        Greg KH <gregkh@linuxfoundation.org>,
        Eric Biggers <ebiggers3@gmail.com>
Subject: RE: [PATCH 3/3] secure_seq: use fast&secure siphash instead of
 slow&insecure md5
Thread-Topic: [PATCH 3/3] secure_seq: use fast&secure siphash instead of
 slow&insecure md5
Thread-Index: AQHSVZ+lT0WFF5fKnUWleBSnKdz9faEHM42Q
Date: Wed, 14 Dec 2016 09:51:16 +0000
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DB023F4DA@AcuExch.aculab.com>
References: <20161214001656.19388-1-Jason@zx2c4.com>
 <20161214001656.19388-3-Jason@zx2c4.com>
In-Reply-To: <20161214001656.19388-3-Jason@zx2c4.com>
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From: Jason A. Donenfeld
> Sent: 14 December 2016 00:17
> This gives a clear speed and security improvement. Rather than manually
> filling MD5 buffers, we simply create a layout by a simple anonymous
> struct, for which gcc generates rather efficient code.
...
> +	const struct {
> +		struct in6_addr saddr;
> +		struct in6_addr daddr;
> +		__be16 sport;
> +		__be16 dport;
> +	} __packed combined = {
> +		.saddr = *(struct in6_addr *)saddr,
> +		.daddr = *(struct in6_addr *)daddr,
> +		.sport = sport,
> +		.dport = dport
> +	};

You need to look at the effect of marking this (and the other)
structures 'packed' on architectures like sparc64.

	David