Re: [PATCH v3 0/2] netfilter: nfqueue: incorrect sctp checksum

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Mon, May 20, 2024 at 05:44:35PM +0200, Pablo Neira Ayuso wrote:
> On Mon, May 20, 2024 at 01:27:22PM +0200, Pablo Neira Ayuso wrote:
> > On Mon, May 13, 2024 at 10:00:31PM +0000, Antonio Ojea wrote:
> > > Fixes the bug described in
> > > https://bugzilla.netfilter.org/show_bug.cgi?id=1742
> > > causing netfilter to drop SCTP packets when using
> > > nfqueue and GSO due to incorrect checksum.
> > > 
> > > Patch 1 adds a new helper to process the sctp checksum
> > > correctly.
> > > 
> > > Patch 2 adds a selftest regression test.
> > 
> > I am inclined to integrated this into nf.git, I will pick a Fixes: tag
> > sufficiently old so -stable picks up.
> 
> I have to collapse this chunk, otherwise I hit one issue with missing
> exported symbol. No need to resend, I will amend here. Just for the
> record.

Hm. SCTP GSO support is different too, because it keeps a list of segments.

static int
nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
{
[...]
        if ((queue->flags & NFQA_CFG_F_GSO) || !skb_is_gso(skb))
                return __nfqnl_enqueue_packet(net, queue, entry);

I think this needs to be:

        if ((queue->flags & NFQA_CFG_F_GSO) || !skb_is_gso(skb) || !skb_is_gso_sctp(skb))
                return __nfqnl_enqueue_packet(net, queue, entry);

so SCTP GSO packets enters this path below:

        nf_bridge_adjust_skb_data(skb);
        segs = skb_gso_segment(skb, 0);

to deliver separated segments to userspace.

Otherwise, I don't see yet how userspace can deal with several SCTP
segments, from nf_reinject() there is a list of segments no more.