netdev - Re: Misalignment, MIPS, and ip

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Message-ID: <20161211153027.GD29761@lunn.ch>
Date:   Sun, 11 Dec 2016 16:30:27 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-mips@...ux-mips.org, Netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Dan Lüdtke <mail@...rl.com>,
        Willy Tarreau <w@....eu>,
        Måns Rullgård <mans@...sr.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        WireGuard mailing list <wireguard@...ts.zx2c4.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Felix Fietkau <nbd@....name>, Jiri Benc <jbenc@...hat.com>,
        David Miller <davem@...emloft.net>
Subject: Re: Misalignment, MIPS, and ip_hdr(skb)->version

> 3. Add 3 bytes of padding, set to zero, to the encrypted section just
> before the IP header, marked for future use.
> Pros: satisfies IETF mantras, can use those extra bits in the future
> for interesting protocol extensions for authenticated peers.
> Cons: lowers MTU, marginally more difficult to implement but still
> probably just one or two lines of code.

I'm not a crypto expert, but does this not give you a helping hand in
breaking the crypto? You know the plain text value of these bytes, and
where they are in the encrypted text.

      Andrew