On 08/02/2018 04:43 PM, Florian Westphal wrote:
> don't bother with pathological cases, they only waste cycles.
> IPv6 requires a minimum MTU of 1280 so we should never see fragments
> smaller than this (except last frag).
>
> For IPv4, in practice, we could probably also adopt a higher limit,
> but for now use ipv4 min mtu (68).
...
> + if (-skb_network_offset(skb) + skb->len < IPV4_MIN_MTU &&
> + ip_hdr(skb)->frag_off & htons(IP_MF))
> + goto drop;
> +
>
I am not totally sure this is legit for IPv4.
Some intermediate nodes can try to be smart and could decide to further split
fragments.
I am pretty sure I have seen this behavior on some radio environments :/
Eventually we could add a sysctl to allow an admin to set the threshold ?
