From: Patrick McHardy <kaber@trash•net>
To: Maxime Bizon <mbizon@freebox•fr>
Cc: Eric Dumazet <edumazet@google•com>,
davem@davemloft•net, netdev <netdev@vger•kernel.org>
Subject: Re: problem forwarding IP fragments with DF bit set (caused by ipv4: fix path MTU discovery with connection tracking)
Date: Tue, 29 Apr 2014 15:35:14 +0100 [thread overview]
Message-ID: <20140429143512.GC12781@macbook.localnet> (raw)
In-Reply-To: <1398707980.10880.6.camel@sakura.staff.proxad.net>
On Mon, Apr 28, 2014 at 07:59:40PM +0200, Maxime Bizon wrote:
>
> On Mon, 2014-04-28 at 18:37 +0200, Maxime Bizon wrote:
> >
> > conntrack causes the packets to be re-assembled, but since the
> > resulting skb now has IP_DF set, it fails the (DF + MTU) test in
> > ip_forward.c and causes ICMP frag_needed to be sent.
>
> hum isn't it just a matter of doing this ?
But why should we do this? The entire point of the patch was to fix PMTUD.
> --- a/net/ipv4/ip_fragment.c
> +++ b/net/ipv4/ip_fragment.c
> @@ -493,6 +493,8 @@ found:
> skb->len + ihl > qp->q.max_size)
> qp->q.max_size = skb->len + ihl;
>
> + skb->local_df = 1;
> +
> if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
> qp->q.meat == qp->q.len) {
> unsigned long orefdst = skb->_skb_refdst;
>
>
> --
> Maxime
>
next prev parent reply other threads:[~2014-04-29 14:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-28 16:37 problem forwarding IP fragments with DF bit set (caused by ipv4: fix path MTU discovery with connection tracking) Maxime Bizon
2014-04-28 17:59 ` Maxime Bizon
2014-04-29 14:35 ` Patrick McHardy [this message]
2014-04-29 14:33 ` Patrick McHardy
2014-04-29 14:42 ` Maxime Bizon
2014-04-29 14:45 ` Patrick McHardy
2014-04-29 15:23 ` Maxime Bizon
2014-04-29 15:37 ` Eric Dumazet
2014-04-29 20:13 ` Florian Westphal
2014-04-30 14:34 ` Maxime Bizon
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