On Tue, Jan 24, 2017 at 09:02:31PM +0100, Andreas Schultz wrote:
> Hi Pablo,
>
> ----- On Jan 24, 2017, at 8:03 PM, pablo pa...@netfilter.org wrote:
>
> > Hi Andreas,
> >
> > On Tue, Jan 24, 2017 at 06:24:02PM +0100, Andreas Schultz wrote:
> >> enable userspace to send error replies for invalid tunnels
> >>
> >> Signed-off-by: Andreas Schultz <aschu...@tpip.net>
> >> ---
> >> drivers/net/gtp.c | 8 ++++----
> >> 1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
> >> index 912721e..c607333 100644
> >> --- a/drivers/net/gtp.c
> >> +++ b/drivers/net/gtp.c
> >> @@ -198,12 +198,12 @@ static int gtp0_udp_encap_recv(struct gtp_dev *gtp,
> >> struct
> >> sk_buff *skb,
> >> pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid));
> >> if (!pctx) {
> >> netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
> >> - return -1;
> >> + return 1;
> >> }
> >>
> >> if (!gtp_check_src_ms(skb, pctx, hdrlen)) {
> >> netdev_dbg(gtp->dev, "No PDP ctx for this MS\n");
> >> - return -1;
> >> + return 1;
> >
> > So userspace gets the packet that we cannot forward. I guess your
> > userspace codebase performs this sanity checks again so you can send
> > the appropriate error reply?
>
> For TEID /= 0, the only reply is a T-PDU of type error indication. There
> is no cause specified. So I don't actually have to repeat the check.
> TEID == 0 is more interesting, this tells userspace that it tried to
> send on an invalid tunnel and should tear it down.
Ah, I see, thanks for explaining, I guess this is good to debug
misconfigurations.
> If you like, you can have a look at the userspace code. The relevant piece
> is at
> https://github.com/travelping/gtp_u_kmod/blob/master/src/gtp_u_kmod_port.erl#L231
>
> But be warned, it's written in Erlang ;-)
Will have a look, but you taking me away from my usual domains :).
