From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Schultz Subject: Re: [PATCH 5/5] gtp: let userspace handle packets for invalid tunnels Date: Tue, 24 Jan 2017 21:02:31 +0100 (CET) Message-ID: <1060167008.597625.1485288151511.JavaMail.zimbra@tpip.net> References: <20170124172402.12096-1-aschultz@tpip.net> <20170124172402.12096-6-aschultz@tpip.net> <20170124190349.GA9757@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Lionel Gauthier , openbsc@lists.osmocom.org, laforge To: pablo Return-path: Received: from mail.tpip.net ([92.43.49.48]:53435 "EHLO mail.tpip.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750715AbdAXUCe (ORCPT ); Tue, 24 Jan 2017 15:02:34 -0500 In-Reply-To: <20170124190349.GA9757@salvia> Sender: netdev-owner@vger.kernel.org List-ID: Hi Pablo, ----- On Jan 24, 2017, at 8:03 PM, pablo pablo@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 >> --- >> 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. 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 ;-) Andreas > >> } >> >> /* Get rid of the GTP + UDP headers. */ >> @@ -247,12 +247,12 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, >> struct sk_buff *skb, >> pctx = gtp1_pdp_find(gtp, ntohl(gtp1->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; >> } >> >> /* Get rid of the GTP + UDP headers. */ >> -- >> 2.10.2