History log of /linux-master/net/ipv4/gre_demux.c
Revision Date Author Comments
# 6a57a219 13-Feb-2024 Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>

Normalise "name (ad@dr)" MODULE_AUTHORs to "name <ad@dr>"

Found with git grep 'MODULE_AUTHOR(".*([^)]*@'
Fixed with
sed -i '/MODULE_AUTHOR(".*([^)]*@/{s/ (/ </g;s/)"/>"/;s/)and/> and/}' \
$(git grep -l 'MODULE_AUTHOR(".*([^)]*@')

Also:
in drivers/media/usb/siano/smsusb.c normalise ", INC" to ", Inc";
this is what every other MODULE_AUTHOR for this company says,
and it's what the header says
in drivers/sbus/char/openprom.c normalise a double-spaced separator;
this is clearly copied from the copyright header,
where the names are aligned on consecutive lines thusly:
* Linux/SPARC PROM Configuration Driver
* Copyright (C) 1996 Thomas K. Dyas (tdyas@noc.rutgers.edu)
* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
but the authorship branding is single-line

Link: https://lkml.kernel.org/r/mk3geln4azm5binjjlfsgjepow4o73domjv6ajybws3tz22vb3@tarta.nabijaczleweli.xyz
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>


# 5796254e 17-May-2021 Yejune Deng <yejune.deng@gmail.com>

net: Remove the member netns_ok

Every protocol has the 'netns_ok' member and it is euqal to 1. The
'if (!prot->netns_ok)' always false in inet_add_protocol().

Signed-off-by: Yejune Deng <yejunedeng@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 085c7c4e 26-Dec-2020 Cong Wang <cong.wang@bytedance.com>

erspan: fix version 1 check in gre_parse_header()

Both version 0 and version 1 use ETH_P_ERSPAN, but version 0 does not
have an erspan header. So the check in gre_parse_header() is wrong,
we have to distinguish version 1 from version 0.

We can just check the gre header length like is_erspan_type1().

Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Reported-by: syzbot+f583ce3d4ddf9836b27a@syzkaller.appspotmail.com
Cc: William Tu <u9012063@gmail.com>
Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 17c25caf 07-Mar-2020 Eric Dumazet <edumazet@google.com>

gre: fix uninit-value in __iptunnel_pull_header

syzbot found an interesting case of the kernel reading
an uninit-value [1]

Problem is in the handling of ETH_P_WCCP in gre_parse_header()

We look at the byte following GRE options to eventually decide
if the options are four bytes longer.

Use skb_header_pointer() to not pull bytes if we found
that no more bytes were needed.

All callers of gre_parse_header() are properly using pskb_may_pull()
anyway before proceeding to next header.

[1]
BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2303 [inline]
BUG: KMSAN: uninit-value in __iptunnel_pull_header+0x30c/0xbd0 net/ipv4/ip_tunnel_core.c:94
CPU: 1 PID: 11784 Comm: syz-executor940 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x220 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
pskb_may_pull include/linux/skbuff.h:2303 [inline]
__iptunnel_pull_header+0x30c/0xbd0 net/ipv4/ip_tunnel_core.c:94
iptunnel_pull_header include/net/ip_tunnels.h:411 [inline]
gre_rcv+0x15e/0x19c0 net/ipv6/ip6_gre.c:606
ip6_protocol_deliver_rcu+0x181b/0x22c0 net/ipv6/ip6_input.c:432
ip6_input_finish net/ipv6/ip6_input.c:473 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ip6_input net/ipv6/ip6_input.c:482 [inline]
ip6_mc_input+0xdf2/0x1460 net/ipv6/ip6_input.c:576
dst_input include/net/dst.h:442 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ipv6_rcv+0x683/0x710 net/ipv6/ip6_input.c:306
__netif_receive_skb_one_core net/core/dev.c:5198 [inline]
__netif_receive_skb net/core/dev.c:5312 [inline]
netif_receive_skb_internal net/core/dev.c:5402 [inline]
netif_receive_skb+0x66b/0xf20 net/core/dev.c:5461
tun_rx_batched include/linux/skbuff.h:4321 [inline]
tun_get_user+0x6aef/0x6f60 drivers/net/tun.c:1997
tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write fs/read_write.c:483 [inline]
__vfs_write+0xa5a/0xca0 fs/read_write.c:496
vfs_write+0x44a/0x8f0 fs/read_write.c:558
ksys_write+0x267/0x450 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__ia32_sys_write+0xdb/0x120 fs/read_write.c:620
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f62d99
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000fffedb2c EFLAGS: 00000217 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020002580
RDX: 0000000000000fca RSI: 0000000000000036 RDI: 0000000000000004
RBP: 0000000000008914 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
slab_alloc_node mm/slub.c:2793 [inline]
__kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4401
__kmalloc_reserve net/core/skbuff.c:142 [inline]
__alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
alloc_skb include/linux/skbuff.h:1051 [inline]
alloc_skb_with_frags+0x18c/0xa70 net/core/skbuff.c:5766
sock_alloc_send_pskb+0xada/0xc60 net/core/sock.c:2242
tun_alloc_skb drivers/net/tun.c:1529 [inline]
tun_get_user+0x10ae/0x6f60 drivers/net/tun.c:1843
tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write fs/read_write.c:483 [inline]
__vfs_write+0xa5a/0xca0 fs/read_write.c:496
vfs_write+0x44a/0x8f0 fs/read_write.c:558
ksys_write+0x267/0x450 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__ia32_sys_write+0xdb/0x120 fs/read_write.c:620
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139

Fixes: 95f5c64c3c13 ("gre: Move utility functions to common headers")
Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 0e494092 05-Dec-2019 Cong Wang <xiyou.wangcong@gmail.com>

gre: refetch erspan header from skb->data after pskb_may_pull()

After pskb_may_pull() we should always refetch the header
pointers from the skb->data in case it got reallocated.

In gre_parse_header(), the erspan header is still fetched
from the 'options' pointer which is fetched before
pskb_may_pull().

Found this during code review of a KMSAN bug report.

Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Acked-by: William Tu <u9012063@gmail.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# e4aa33ad 04-Jul-2019 Li RongQing <lirongqing@baidu.com>

net: remove unused parameter from skb_checksum_try_convert

the check parameter is never used

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 2874c5fd 27-May-2019 Thomas Gleixner <tglx@linutronix.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# cb73ee40 17-Jan-2019 Lorenzo Bianconi <lorenzo.bianconi@redhat.com>

net: ip_gre: use erspan key field for tunnel lookup

Use ERSPAN key header field as tunnel key in gre_parse_header routine
since ERSPAN protocol sets the key field of the external GRE header to
0 resulting in a tunnel lookup fail in ip6gre_err.
In addition remove key field parsing and pskb_may_pull check in
erspan_rcv and ip6erspan_rcv

Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 32bbd879 07-Nov-2018 Stefano Brivio <sbrivio@redhat.com>

net: Convert protocol error handlers from void to int

We'll need this to handle ICMP errors for tunnels without a sending socket
(i.e. FoU and GUE). There, we might have to look up different types of IP
tunnels, registered as network protocols, before we get a match, so we
want this for the error handlers of IPPROTO_IPIP and IPPROTO_IPV6 in both
inet_protos and inet6_protos. These error codes will be used in the next
patch.

For consistency, return sensible error codes in protocol error handlers
whenever handlers can't handle errors because, even if valid, they don't
match a protocol or any of its states.

This has no effect on existing error handling paths.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>


# b0350d51 13-Sep-2018 Haishuang Yan <yanhaishuang@cmss.chinamobile.com>

ip_gre: fix parsing gre header in ipgre_err

gre_parse_header stops parsing when csum_err is encountered, which means
tpi->key is undefined and ip_tunnel_lookup will return NULL improperly.

This patch introduce a NULL pointer as csum_err parameter. Even when
csum_err is encountered, it won't return error and continue parsing gre
header as expected.

Fixes: 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook.")
Reported-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 9b8c6d7b 18-Jun-2016 Eric Dumazet <edumazet@google.com>

gre: better support for ICMP messages for gre+ipv6

ipgre_err() can call ip6_err_gen_icmpv6_unreach() for proper
support of ipv4+gre+icmp+ipv6+... frames, used for example
by traceroute/mtr.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# e582615ad 15-Jun-2016 Eric Dumazet <edumazet@google.com>

gre: fix error handler

1) gre_parse_header() can be called from gre_err()

At this point transport header points to ICMP header, not the inner
header.

2) We can not really change transport header as ipgre_err() will later
assume transport header still points to ICMP header (using icmp_hdr())

3) pskb_may_pull() logic in gre_parse_header() really works
if we are interested at zone pointed by skb->data

4) As Jiri explained in commit b7f8fe251e46 ("gre: do not pull header in
ICMP error processing") we should not pull headers in error handler.

So this fix :

A) changes gre_parse_header() to use skb->data instead of
skb_transport_header()

B) Adds a nhs parameter to gre_parse_header() so that we can skip the
not pulled IP header from error path.
This offset is 0 for normal receive path.

C) remove obsolete IPV6 includes

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# da73b4e9 11-May-2016 Haishuang Yan <yanhaishuang@cmss.chinamobile.com>

gre: Fix wrong tpi->proto in WCCP

When dealing with WCCP in gre6 tunnel, it sets the wrong tpi->protocol,
that is, ETH_P_IP instead of ETH_P_IPV6 for the encapuslated traffic.

Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 00b20340 03-May-2016 Jiri Benc <jbenc@redhat.com>

gre: remove superfluous pskb_may_pull

The call to gre_parse_header is either followed by iptunnel_pull_header, or
in the case of ICMP error path, the actual header is not accessed at all.

In the first case, iptunnel_pull_header will call pskb_may_pull anyway and
it's pointless to do it twice. The only difference is what call will fail
with what error code but the net effect is still the same in all call sites.

In the second case, pskb_may_pull is pointless, as skb->data is at the outer
IP header and not at the GRE header.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# f132ae7c 03-May-2016 Jiri Benc <jbenc@redhat.com>

gre: change gre_parse_header to return the header length

It's easier for gre_parse_header to return the header length instead of
filing it into a parameter. That way, the callers that don't care about the
header length can just check whether the returned value is lower than zero.

In gre_err, the tunnel header must not be pulled. See commit b7f8fe251e46
("gre: do not pull header in ICMP error processing") for details.

This patch reduces the conflict between the mentioned commit and commit
95f5c64c3c13 ("gre: Move utility functions to common headers").

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 95f5c64c 29-Apr-2016 Tom Herbert <tom@herbertland.com>

gre: Move utility functions to common headers

Several of the GRE functions defined in net/ipv4/ip_gre.c are usable
for IPv6 GRE implementation (that is they are protocol agnostic).

These include:
- GRE flag handling functions are move to gre.h
- GRE build_header is moved to gre.h and renamed gre_build_header
- parse_gre_header is moved to gre_demux.c and renamed gre_parse_header
- iptunnel_pull_header is taken out of gre_parse_header. This is now
done by caller. The header length is returned from gre_parse_header
in an int* argument.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 9f57c67c 08-Aug-2015 Pravin B Shelar <pshelar@nicira.com>

gre: Remove support for sharing GRE protocol hook.

Support for sharing GREPROTO_CISCO port was added so that
OVS gre port and kernel GRE devices can co-exist. After
flow-based tunneling patches OVS GRE protocol processing
is completely moved to ip_gre module. so there is no need
for GRE protocol hook. Following patch consolidates
GRE protocol related functions into ip_gre module.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>


# b2acd1dc 08-Aug-2015 Pravin B Shelar <pshelar@nicira.com>

openvswitch: Use regular GRE net_device instead of vport

Using GRE tunnel meta data collection feature, we can implement
OVS GRE vport. This patch removes all of the OVS
specific GRE code and make OVS use a ip_gre net_device.
Minimal GRE vport is kept to handle compatibility with
current userspace application.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 1e701f16 08-Sep-2014 Tom Herbert <therbert@google.com>

net: Fix GRE RX to use skb_transport_header for GRE header offset

GRE assumes that the GRE header is at skb_network_header +
ip_hrdlen(skb). It is more general to use skb_transport_header
and this allows the possbility of inserting additional header
between IP and GRE (which is what we will done in Generic UDP
Encapsulation for GRE).

Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 884d338c 31-Aug-2014 Tom Herbert <therbert@google.com>

gre: Add support for checksum unnecessary conversions

Call skb_checksum_try_convert and skb_gro_checksum_try_convert
after checksum is found present and validated in the GRE header
for normal and GRO paths respectively.

In GRO path, call skb_gro_checksum_try_convert

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 77cffe23 27-Aug-2014 Tom Herbert <therbert@google.com>

net: Clarification of CHECKSUM_UNNECESSARY

This patch:
- Clarifies the specific requirements of devices returning
CHECKSUM_UNNECESSARY (comments in skbuff.h).
- Adds csum_level field to skbuff. This is used to express how
many checksums are covered by CHECKSUM_UNNECESSARY (stores n - 1).
This replaces the overloading of skb->encapsulation, that field is
is now only used to indicate inner headers are valid.
- Change __skb_checksum_validate_needed to "consume" each checksum
as indicated by csum_level as layers of the the packet are parsed.
- Remove skb_pop_rcv_encapsulation, no longer needed in the new
csum_level model.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 48a5fc77 22-Aug-2014 Tom Herbert <therbert@google.com>

gre: When GRE csum is present count as encap layer wrt csum

In GRE demux if the GRE checksum pop rcv encapsulation so that any
encapsulated checksums are treated as tunnel checksums.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# d0a7ebbc 10-Jul-2014 Amritha Nambiar <amritha.nambiar@intel.com>

GRE: enable offloads for GRE

To get offloads to work with Generic Routing Encapsulation (GRE), the
outer transport header has to be reset after skb_push is done. This
patch has the support for this fix and hence GRE offloading.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: Joseph Gasparakis <joseph.gasparakis@intel.com>
Tested-By: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 4749c09c 04-Jun-2014 Tom Herbert <therbert@google.com>

gre: Call gso_make_checksum

Call gso_make_checksum. This should have the benefit of using a
checksum that may have been previously computed for the packet.

This also adds NETIF_F_GSO_GRE_CSUM to differentiate devices that
offload GRE GSO with and without the GRE checksum offloaed.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# b1036c6a 07-May-2014 Tom Herbert <therbert@google.com>

gre: Call skb_checksum_simple_validate

Use skb_checksum_simple_validate to verify checksum.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# fbd02dd4 23-Mar-2014 Pravin B Shelar <pshelar@nicira.com>

ip_tunnel: Fix dst ref-count.

Commit 10ddceb22ba (ip_tunnel:multicast process cause panic due
to skb->_skb_refdst NULL pointer) removed dst-drop call from
ip-tunnel-recv.

Following commit reintroduce dst-drop and fix the original bug by
checking loopback packet before releasing dst.
Original bug: https://bugzilla.kernel.org/show_bug.cgi?id=70681

CC: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 438e38fa 06-Jan-2014 Eric Dumazet <edumazet@google.com>

gre_offload: statically build GRE offloading support

GRO/GSO layers can be enabled on a node, even if said
node is only forwarding packets.

This patch permits GSO (and upcoming GRO) support for GRE
encapsulated packets, even if the host has no GRE tunnel setup.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: H.K. Jerry Chu <hkchu@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# 2d26f0a3 19-Oct-2013 Eric Dumazet <edumazet@google.com>

ipv4: generalize gre_handle_offloads

This patch makes gre_handle_offloads() more generic
and rename it to iptunnel_handle_offloads()

This will be used to add GSO/TSO support to IPIP tunnels.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>


# c50cd357 01-Jul-2013 Daniel Borkmann <daniel@iogearbox.net>

net: gre: move GSO functions to gre_offload

Similarly to TCP/UDP offloading, move all related GRE functions to
gre_offload.c to make things more explicit and similar to the rest
of the code.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>