netdev - Re: [PATCH net 2/2] macsec: fix checksumming after decryption

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Date:   Tue, 2 Jul 2019 21:47:08 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Andreas Steinmetz <ast@...dv.de>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        Sabrina Dubroca <sd@...asysnail.net>
Subject: Re: [PATCH net 2/2] macsec: fix checksumming after decryption

On Tue, Jul 2, 2019 at 3:48 PM Andreas Steinmetz <ast@...dv.de> wrote:
>
> On Tue, 2019-07-02 at 10:35 -0400, Willem de Bruijn wrote:
> > On Tue, Jul 2, 2019 at 12:25 AM Andreas Steinmetz <ast@...dv.de> wrote:
> > > On Sun, 2019-06-30 at 21:47 -0400, Willem de Bruijn wrote:
> > > > On Sun, Jun 30, 2019 at 4:48 PM Andreas Steinmetz <ast@...dv.de>
> > > > wrote:
> > > > > Fix checksumming after decryption.
> > > > >
> > > > > Signed-off-by: Andreas Steinmetz <ast@...dv.de>
> > > > >
> > > > > --- a/drivers/net/macsec.c      2019-06-30 22:14:10.250285314 +0200
> > > > > +++ b/drivers/net/macsec.c      2019-06-30 22:15:11.931230417 +0200
> > > > > @@ -869,6 +869,7 @@
> > > > >
> > > > >  static void macsec_finalize_skb(struct sk_buff *skb, u8 icv_len,
> > > > > u8 hdr_len)
> > > > >  {
> > > > > +       skb->ip_summed = CHECKSUM_NONE;
> > > > >         memmove(skb->data + hdr_len, skb->data, 2 * ETH_ALEN);
> > > > >         skb_pull(skb, hdr_len);
> > > > >         pskb_trim_unique(skb, skb->len - icv_len);
> > > >
> > > > Does this belong in macset_reset_skb?
> > >
> > > Putting this in macsec_reset_skb would then miss out the "nosci:" part
> > > of the RX path in macsec_handle_frame().
> >
> > It is called on each nskb before calling netif_rx.
> >
> > It indeed is not called when returning RX_HANDLER_PASS, but that is correct?
>
> This is correct. Packets passed on with RX_HANDLER_PASS are either not for this
> driver or the special case of being destined for a KaY and in this case being
> the MACsec ethernet protocol and thus not IP, so no checksumming.

So this could have been set in macsec_reset_skb, then? As all relevant cases
call it. Anyway, it's not very important and already merged.