From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH] ipv6: ip6mr: Recalc UDP checksum before forwarding
Date: Wed, 13 Dec 2017 09:52:44 -0800
Message-ID: <1513187564.25033.65.camel@gmail.com>
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To: Brendan McGrath <redmcg@redmandi.dyndns.org>,
        "David S . Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Wed, 2017-12-13 at 22:20 +1100, Brendan McGrath wrote:
> Currently, when forwarding from a Virtual Interface to a Physical
> Interface, ip_summed is set to a value of CHECKSUM_UNNECESSARY and
> the UDP checksum has not been calculated.
> 

This seems a bug then ?
CHECKSUM_UNNECESSARY means checksum has been validated.
Not that we want it being computed later in the stack.

If we force a checksum here, what guarantee do we have packet was not
corrupted before we do this ?