Re: [PATCH] veth: don't modify ip-summed; doing so treats packets with bad checksums as good.

[Cong Wang]

On Fri, Dec 18, 2015 at 11:42 AM, Vijay Pandurangan <vijayp@xxxxxxxxx> wrote:
> Evan and I have demonstrated this bug on Kubernetes as well, so it's
> not just a problem in Mesos. (See
> https://github.com/kubernetes/kubernetes/issues/18898)
>

Interesting... then this problem is much more serious than I thought.

Looks like in RX path the bridge sets the checksum to CHECKSUM_NONE
too:

static inline void skb_forward_csum(struct sk_buff *skb)
{
        /* Unfortunately we don't support this one.  Any brave souls? */
        if (skb->ip_summed == CHECKSUM_COMPLETE)
                skb->ip_summed = CHECKSUM_NONE;
}

I guess this is probably why Docker/Kubernetes could be affected too.
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