Fix the below warning generated by static checker:
    net/mpls/af_mpls.c:2111 mpls_getroute()
    error: uninitialized symbol 'in_label'."

Fixes: 397fc9e5 ("mpls: route get support")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

fix rtm policy name typo in mpls_getroute and also remove
export of rtm_ipv4_policy

Fixes: 397fc9e5 ("mpls: route get support")
Reported-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds RTM_GETROUTE doit handler for mpls routes.

Input:
RTA_DST - input label
RTA_NEWDST - labels in packet for multipath selection

By default the getroute handler returns matched
nexthop label, via and oif

With RTM_F_FIB_MATCH flag, full matched route is
returned.

example (with patched iproute2):
$ip -f mpls route show
101
        nexthop as to 102/103 via inet 172.16.2.2 dev virt1-2
        nexthop as to 302/303 via inet 172.16.12.2 dev virt1-12
201
        nexthop as to 202/203 via inet6 2001:db8:2::2 dev virt1-2
        nexthop as to 402/403 via inet6 2001:db8:12::2 dev virt1-12

$ip -f mpls route get 103
RTNETLINK answers: Network is unreachable

$ip -f mpls route get 101
101 as to 102/103 via inet 172.16.2.2 dev virt1-2

$ip -f mpls route get as to 302/303 101
101 as to 302/303 via inet 172.16.12.2 dev virt1-12

$ip -f mpls route get fibmatch 103
RTNETLINK answers: Network is unreachable

$ip -f mpls route get fibmatch 101
101
        nexthop as to 102/103 via inet 172.16.2.2 dev virt1-2
        nexthop as to 302/303 via inet 172.16.12.2 dev virt1-12
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

recent fixes to use WRITE_ONCE for nh_flags on link up,
accidently ended up leaving the deadflags on a nh. This patch
fixes the WRITE_ONCE to use freshly evaluated nh_flags.

Fixes: 39eb8cd1 ("net: mpls: rt_nhn_alive and nh_flags should be accessed using READ_ONCE")
Reported-by: NSatish Ashok <sashok@cumulusnetworks.com>
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

err is initialized to EINVAL and not used before it is set again.
Remove the unnecessary initialization.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

nla_get_via is only used in af_mpls.c. Remove declaration from internal.h
and move up in af_mpls.c before first use. Code move only; no
functional change intended.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add error messages for failures in adding and deleting mpls routes.
This covers most of the annoying EINVAL errors.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

mpls_route_add and mpls_route_del have the same checks on the label.
Move to a helper. Avoid duplicate extack messages in the next patch.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fill in extack for errors in build_state for mpls lwt encap including
passing extack to nla_get_labels and adding error messages for failures
in it.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pass extack arg down to lwtunnel_build_state and the build_state callbacks.
Add messages for failures in lwtunnel_build_state, and add the extarg to
nla_parse where possible in the build_state callbacks.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are many code paths opencoding kvmalloc.  Let's use the helper
instead.  The main difference to kvmalloc is that those users are
usually not considering all the aspects of the memory allocator.  E.g.
allocation requests <= 32kB (with 4kB pages) are basically never failing
and invoke OOM killer to satisfy the allocation.  This sounds too
disruptive for something that has a reasonable fallback - the vmalloc.
On the other hand those requests might fallback to vmalloc even when the
memory allocator would succeed after several more reclaim/compaction
attempts previously.  There is no guarantee something like that happens
though.

This patch converts many of those places to kv[mz]alloc* helpers because
they are more conservative.

Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Xen bits
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: Andreas Dilger <andreas.dilger@intel.com> # Lustre
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> # KVM/s390
Acked-by: Dan Williams <dan.j.williams@intel.com> # nvdim
Acked-by: David Sterba <dsterba@suse.com> # btrfs
Acked-by: Ilya Dryomov <idryomov@gmail.com> # Ceph
Acked-by: Tariq Toukan <tariqt@mellanox.com> # mlx4
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx5
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Santosh Raspatur <santosh@chelsio.com>
Cc: Hariprasad S <hariprasad@chelsio.com>
Cc: Yishai Hadas <yishaih@mellanox.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: "Yan, Zheng" <zyan@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add netlink_ext_ack arg to rtnl_doit_func. Pass extack arg to nlmsg_parse
for doit functions that call it directly.

This is the first step to using extended error reporting in rtnetlink.
>From here individual subsystems can be updated to set netlink_ext_ack as
needed.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Alow users to push down more labels per MPLS encap. Similar to LSR case,
move label array to the end of mpls_iptunnel_encap and allocate based on
the number of labels for the route.

For consistency with the LSR case, re-use the same maximum number of
labels.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow users to push down more labels per MPLS route. With the previous
patches, no memory allocations are based on MAX_NEW_LABELS; the limit
is only used to keep userspace in check.

At this point MAX_NEW_LABELS is only used for mpls_route_config (copying
route data from userspace) and processing nexthops looking for the max
number of labels across the route spec.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Limit memory allocation size for mpls_route to 4096.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Move labels to the end of mpls_nh as a 0-sized array and within mpls_route
move the via for a nexthop after the mpls_nh. The new layout becomes:

   +----------------------+
   | mpls_route           |
   +----------------------+
   | mpls_nh 0            |
   +----------------------+
   | alignment padding    |   4 bytes for odd number of labels; 0 for even
   +----------------------+
   | via[rt_max_alen] 0   |
   +----------------------+
   | alignment padding    |   via's aligned on sizeof(unsigned long)
   +----------------------+
   | ...                  |
   +----------------------+
   | mpls_nh n-1          |
   +----------------------+
   | via[rt_max_alen] n-1 |
   +----------------------+

Memory allocated for nexthop + via is constant across all nexthops and
their via. It is based on the maximum number of labels across all nexthops
and the maximum via length. The size is saved in the mpls_route as
rt_nh_size. Accessing a nexthop becomes rt->rt_nh + index * rt->rt_nh_size.

The offset of the via address from a nexthop is saved as rt_via_offset
so that given an mpls_nh pointer the via for that hop is simply
nh + rt->rt_via_offset.

With prior code, memory allocated per mpls_route with 1 nexthop:
     via is an ethernet address - 64 bytes
     via is an ipv4 address     - 64
     via is an ipv6 address     - 72

With this patch set, memory allocated per mpls_route with 1 nexthop and
1 or 2 labels:
     via is an ethernet address - 56 bytes
     via is an ipv4 address     - 56
     via is an ipv6 address     - 64

The 8-byte reduction is due to the previous patch; the change introduced
by this patch has no impact on the size of allocations for 1 or 2 labels.

Performance impact of this change was examined using network namespaces
with veth pairs connecting namespaces. ns0 inserts the packet to the
label-switched path using an lwt route with encap mpls. ns1 adds 1 or 2
labels depending on test, ns2 (and ns3 for 2-label test) pops the label
and forwards. ns3 (or ns4) for a 2-label is the destination. Similar
series of namespaces used for 2-nexthop test.

Intent is to measure changes to latency (overhead in manipulating the
packet) in the forwarding path. Tests used netperf with UDP_RR.

IPv4:                     current   patches
   1 label, 1 nexthop      29908     30115
   2 label, 1 nexthop      29071     29612
   1 label, 2 nexthop      29582     29776
   2 label, 2 nexthop      29086     29149

IPv6:                     current   patches
   1 label, 1 nexthop      24502     24960
   2 label, 1 nexthop      24041     24407
   1 label, 2 nexthop      23795     23899
   2 label, 2 nexthop      23074     22959

In short, the change has no effect to a modest increase in performance.
This is expected since this patch does not really have an impact on routes
with 1 or 2 labels (the current limit) and 1 or 2 nexthops.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Number of nexthops and number of alive nexthops are tracked using an
unsigned int. A route should never have more than 255 nexthops so
convert both to u8. Update all references and intermediate variables
to consistently use u8 as well.

Shrinks the size of mpls_route from 32 bytes to 24 bytes with a 2-byte
hole before the nexthops.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The number of alive nexthops for a route (rt->rt_nhn_alive) and the
flags for a next hop (nh->nh_flags) are modified by netdev event
handlers. The event handlers run with rtnl_lock held so updates are
always done with the lock held. The packet path accesses the fields
under the rcu lock. Since those fields can change at any moment in
the packet path, both fields should be accessed using READ_ONCE. Updates
to both fields should use WRITE_ONCE.

Update mpls_select_multipath (packet path) and mpls_ifdown and mpls_ifup
(event handlers) accordingly.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A recent commit skips nexthops in a route if the device has been
deleted. Update lfib_nlmsg_size accordingly.
Reported-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Acked-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Send netconf notifications for MPLS when the device registers and
unregisters.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Refactor mpls_netconf_notify_devconf to take the event as an input arg.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When all devices for all nexthops in a route have been deleted, the
route is effectively dead, so remove it.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If the device for a nexthop in a multipath route is deleted, the nexthop
is effectively removed from the route. Currently, a route dump still
returns the nexhop though without the device set:

$ ip -f mpls ro ls
100
	nexthopvia inet 10.11.1.2  dev br0
	nexthopvia inet 10.100.3.1  dev eth3
$ ip li del br0
$ ip -f mpls ro ls
100
	nexthopvia inet 10.11.1.2  dev * dead linkdown
	nexthopvia inet 10.100.3.1  dev eth3

Since the nexthop is effectively deleted, drop the hop from the route
dump.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix copy and paste error setting rt_ttl_propagate.

Fixes: 5b441ac8 ("mpls: allow TTL propagation to IP packets to be configured")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Alive tracking of nexthops can account for a link twice if the carrier
goes down followed by an admin down of the same link rendering multipath
routes useless. This is similar to 79099aab for UNREGISTER events and
DOWN events.

Fix by tracking number of alive nexthops in mpls_ifdown similar to the
logic in mpls_ifup. Checking the flags per nexthop once after all events
have been processed is simpler than trying to maintian a running count
through all event combinations.

Also, WRITE_ONCE is used instead of ACCESS_ONCE to set rt_nhn_alive
per a comment from checkpatch:
    WARNING: Prefer WRITE_ONCE(<FOO>, <BAR>) over ACCESS_ONCE(<FOO>) = <BAR>

Fixes: c89359a4 ("mpls: support for dead routes")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow TTL propagation from IP packets to MPLS packets to be
configured. Add a new optional LWT attribute, MPLS_IPTUNNEL_TTL, which
allows the TTL to be set in the resulting MPLS packet, with the value
of 0 having the semantics of enabling propagation of the TTL from the
IP header (i.e. non-zero values disable propagation).

Also allow the configuration to be overridden globally by reusing the
same sysctl to control whether the TTL is propagated from IP packets
into the MPLS header. If the per-LWT attribute is set then it
overrides the global configuration. If the TTL isn't propagated then a
default TTL value is used which can be configured via a new sysctl,
"net.mpls.default_ttl". This is kept separate from the configuration
of whether IP TTL propagation is enabled as it can be used in the
future when non-IP payloads are supported (i.e. where there is no
payload TTL that can be propagated).
Signed-off-by: NRobert Shearman <rshearma@brocade.com>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Tested-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Provide the ability to control on a per-route basis whether the TTL
value from an MPLS packet is propagated to an IPv4/IPv6 packet when
the last label is popped as per the theoretical model in RFC 3443
through a new route attribute, RTA_TTL_PROPAGATE which can be 0 to
mean disable propagation and 1 to mean enable propagation.

In order to provide the ability to change the behaviour for packets
arriving with IPv4/IPv6 Explicit Null labels and to provide an easy
way for a user to change the behaviour for all existing routes without
having to reprogram them, a global knob is provided. This is done
through the addition of a new per-namespace sysctl,
"net.mpls.ip_ttl_propagate", which defaults to enabled. If the
per-route attribute is set (either enabled or disabled) then it
overrides the global configuration.
Signed-off-by: NRobert Shearman <rshearma@brocade.com>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Tested-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Multipath routes can be rendered usesless when a device in one of the
paths is deleted. For example:

$ ip -f mpls ro ls
100
	nexthop as to 200 via inet 172.16.2.2  dev virt12
	nexthop as to 300 via inet 172.16.3.2  dev br0
101
	nexthop as to 201 via inet6 2000:2::2  dev virt12
	nexthop as to 301 via inet6 2000:3::2  dev br0

$ ip li del br0

When br0 is deleted the other hop is not considered in
mpls_select_multipath because of the alive check -- rt_nhn_alive
is 0.

rt_nhn_alive is decremented once in mpls_ifdown when the device is taken
down (NETDEV_DOWN) and again when it is deleted (NETDEV_UNREGISTER). For
a 2 hop route, deleting one device drops the alive count to 0. Since
devices are taken down before unregistering, the decrement on
NETDEV_UNREGISTER is redundant.

Fixes: c89359a4 ("mpls: support for dead routes")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the mpls_router module is unloaded, mpls routes are deleted but
notifications are not sent to userspace leaving userspace caches
out of sync. Add the call to mpls_notify_route in mpls_net_exit as
routes are freed.

Fixes: 0189197f ("mpls: Basic routing support")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add netconf support to MPLS. Allows userpsace to learn and be notified
of changes to 'input' enable setting per interface.
Acked-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Nothing about lwt state requires a device reference, so remove the
input argument.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Modules implementing lwtunnel ops should not be allowed to unload
while there is state alive using those ops, so specify the owning
module for all lwtunnel ops.
Signed-off-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

MPLS multipath for LSR is broken -- always selecting the first nexthop
in the one label case. For example:

    $ ip -f mpls ro ls
    100
            nexthop as to 200 via inet 172.16.2.2  dev virt12
            nexthop as to 300 via inet 172.16.3.2  dev virt13
    101
            nexthop as to 201 via inet6 2000:2::2  dev virt12
            nexthop as to 301 via inet6 2000:3::2  dev virt13

In this example incoming packets have a single MPLS labels which means
BOS bit is set. The BOS bit is passed from mpls_forward down to
mpls_multipath_hash which never processes the hash loop because BOS is 1.

Update mpls_multipath_hash to process the entire label stack. mpls_hdr_len
tracks the total mpls header length on each pass (on pass N mpls_hdr_len
is N * sizeof(mpls_shim_hdr)). When the label is found with the BOS set
it verifies the skb has sufficient header for ipv4 or ipv6, and find the
IPv4 and IPv6 header by using the last mpls_hdr pointer and adding 1 to
advance past it.

With these changes I have verified the code correctly sees the label,
BOS, IPv4 and IPv6 addresses in the network header and icmp/tcp/udp
traffic for ipv4 and ipv6 are distributed across the nexthops.

Fixes: 1c78efa8 ("mpls: flow-based multipath selection")
Acked-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Having MPLS packet stats is useful for observing network operation and
for diagnosing network problems. In the absence of anything better,
RFC2863 and RFC3813 are used for guidance for which stats to expose
and the semantics of them. In particular rx_noroutes maps to in
unknown protos in RFC2863. The stats are exposed to userspace via
AF_MPLS attributes embedded in the IFLA_STATS_AF_SPEC attribute of
RTM_GETSTATS messages.

All the introduced fields are 64-bit, even error ones, to ensure no
overflow with long uptimes. Per-CPU counters are used to avoid
cache-line contention on the commonly used fields. The other fields
have also been made per-CPU for code to avoid performance problems in
error conditions on the assumption that on some platforms the cost of
atomic operations could be more expensive than sending the packet
(which is what would be done in the success case). If that's not the
case, we could instead not use per-CPU counters for these fields.

Only unicast and non-fragment are exposed at the moment, but other
counters can be exposed in the future either by adding to the end of
struct mpls_link_stats or by additional netlink attributes in the
AF_MPLS IFLA_STATS_AF_SPEC nested attribute.
Signed-off-by: NRobert Shearman <rshearma@brocade.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adding space after switch keyword before open
parenthesis for readability purpose.

This patch fixes the checkpatch.pl warning:
space required before the open parenthesis '('
Signed-off-by: NSuraj Deshmukh <surajssd009005@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The field is initialized by ILA and MPLS but never used. Remove it.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This will be also used by openvswitch.
Signed-off-by: NJiri Benc <jbenc@redhat.com>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Acked-by: NPravin B Shelar <pshelar@ovn.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

return at end of function is useless.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As reported by Lennert the MPLS GSO code is failing to properly segment
large packets. There are a couple of problems:

1. the inner protocol is not set so the gso segment functions for inner
   protocol layers are not getting run, and

2  MPLS labels for packets that use the "native" (non-OVS) MPLS code
   are not properly accounted for in mpls_gso_segment.

The MPLS GSO code was added for OVS. It is re-using skb_mac_gso_segment
to call the gso segment functions for the higher layer protocols. That
means skb_mac_gso_segment is called twice -- once with the network
protocol set to MPLS and again with the network protocol set to the
inner protocol.

This patch sets the inner skb protocol addressing item 1 above and sets
the network_header and inner_network_header to mark where the MPLS labels
start and end. The MPLS code in OVS is also updated to set the two
network markers.

>From there the MPLS GSO code uses the difference between the network
header and the inner network header to know the size of the MPLS header
that was pushed. It then pulls the MPLS header, resets the mac_len and
protocol for the inner protocol and then calls skb_mac_gso_segment
to segment the skb.

Afterward the inner protocol segmentation is done the skb protocol
is set to mpls for each segment and the network and mac headers
restored.
Reported-by: NLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>