gtp: uapi: fix GTPA_MAX

Subtract one to __GTPA_MAX, otherwise GTPA_MAX is off by 2.

Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

gtp: Implement GTP echo request

Adding GTP device through ip link creates the situation where
GTP instance is not able to send GTP echo requests.
Echo requests are used to check if GTP peer is still alive.
With this patch, gtp_genl_ops are extended by new cmd (GTP_CMD_ECHOREQ)
which allows to send echo request in the given version of GTP
protocol (v0 or v1), from the given ms address to he given
peer. TID is not inclued because in all path management
messages it should be equal to 0.

When GTP echo response is detected, multicast message is
send to everyone in the gtp_genl_family. Message contains
GTP version, ms address and peer address.

Suggested-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Revert "GTP: add support for flow based tunneling API"

This reverts commit 9ab7e76aefc97a9aa664accb59d6e8dc5e52514a.

This patch was committed without maintainer approval and despite a number
of unaddressed concerns from review. There are several issues that
impede the acceptance of this patch and that make a reversion of this
particular instance of these changes the best way forward:

i) the patch contains several logically separate changes that would be
better served as smaller patches (for review purposes)
ii) functionality like the handling of end markers has been introduced
without further explanation
iii) symmetry between the handling of GTPv0 and GTPv1 has been
unnecessarily broken
iv) the patchset produces 'broken' packets when extension headers are
included
v) there are no available userspace tools to allow for testing this
functionality
vi) there is an unaddressed Coverity report against the patch concering
memory leakage
vii) most importantly, the patch contains a large amount of superfluous
churn that impedes other ongoing work with this driver

This patch will be reworked into a series that aligns with other
ongoing work and facilitates review.

Signed-off-by: Jonas Bonn <jonas@norrbonn.se>
Acked-by: Harald Welte <laforge@gnumonks.org>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

GTP: add support for flow based tunneling API

Following patch add support for flow based tunneling API
to send and recv GTP tunnel packet over tunnel metadata API.
This would allow this device integration with OVS or eBPF using
flow based tunneling APIs.

Signed-off-by: Pravin B Shelar <pbshelar@fb.com>
Link: https://lore.kernel.org/r/20210110070021.26822-1-pbshelar@fb.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

gtp: add notification mechanism

Like all other network functions, let's notify gtp context on creation and
deletion.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Tested-by: Gabriel Ganne <gabriel.ganne@6wind.com>
Acked-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

gtp: rename SGSN netlink attribute

This is a mostly cosmetic rename of the SGSN netlink attribute to
the GTP link. The justification for this is that we will be making
the module support decapsulation of "downstream" SGSN packets, in
which case the netlink parameter actually refers to the upstream GGSN
peer. Renaming the parameter makes the relationship clearer.

The legacy name is maintained as a define in the header file in order
to not break existing code.

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

gtp: #define _UAPI_LINUX_GTP_H_ and not _UAPI_LINUX_GTP_H__

Fix clang build warning:

./include/uapi/linux/gtp.h:1:9: warning: '_UAPI_LINUX_GTP_H_' is
used as a header guard here, followed by #define of a different
macro [-Wheader-guard]

fix by defining _UAPI_LINUX_GTP_H_ and not _UAPI_LINUX_GTP_H__

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)

This is an initial implementation of a netdev driver for GTP datapath
(GTP-U) v0 and v1, according to the GSM TS 09.60 and 3GPP TS 29.060
standards. This tunneling protocol is used to prevent subscribers from
accessing mobile carrier core network infrastructure.

This implementation requires a GGSN userspace daemon that implements the
signaling protocol (GTP-C), such as OpenGGSN [1]. This userspace daemon
updates the PDP context database that represents active subscriber
sessions through a genetlink interface.

For more context on this tunneling protocol, you can check the slides
that were presented during the NetDev 1.1 [2].

Only IPv4 is supported at this time.

[1] http://git.osmocom.org/openggsn/
[2] http://www.netdevconf.org/1.1/proceedings/slides/schultz-welte-osmocom-gtp.pdf

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>