netdev - Re: [RFC PATCH 15/16] gtp: add ability to send GTP controls headers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 28 Jan 2021 13:29:24 -0800
From:   Pravin Shelar <pravin.ovn@...il.com>
To:     Harald Welte <laforge@...monks.org>
Cc:     Jonas Bonn <jonas@...rbonn.se>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Pravin B Shelar <pbshelar@...com>,
        Jakub Kicinski <kuba@...nel.org>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: Re: [RFC PATCH 15/16] gtp: add ability to send GTP controls headers

On Mon, Jan 25, 2021 at 9:52 AM Harald Welte <laforge@...monks.org> wrote:
>
> Hi Jonas,
>

> On Sun, Jan 24, 2021 at 03:21:21PM +0100, Jonas Bonn wrote:
> > struct gtpu_metadata {
> >         __u8    ver;
> >         __u8    flags;
> >         __u8    type;
> > };
> >
> > Here ver is the version of the metadata structure itself, which is fine.
> > 'flags' corresponds to the 3 flag bits of GTP header's first byte:  E, S,
> > and PN.
> > 'type' corresponds to the 'message type' field of the GTP header.
>
> One more comment on the 'type': Of how much use is it?  After all, the
> GTP-U kernel driver only handles a single message type at all (G-PDU /
> 255 - the only message type that encapsulates user IP data), while all
> other message types are always processed in userland via the UDP socket.
>
There is NO userland UDP socket for the LWT tunnel. All UDP traffic is
terminated in kernel space. userland only sets rules over LTW tunnel
device to handle traffic. This is how OVS/eBPF handles other UDP based
LWT tunnel devices.


> Side-note: 3GPP TS 29.060 lists 5 other message types that can happen in
> GTP-U:
> * Echo Request
> * Echo Response
> * Error Indication
> * Supported Extension Headers Notification
> * End Marker
>
> It would be interesting to understand how the new flow-based tunnel would
> treat those, if those
>
Current code does handle Echo Request, Response and End marker.