Commit c411ed85 authored by Jiri Benc's avatar Jiri Benc Committed by David S. Miller

nsh: add GSO support

Add a new nsh/ directory. It currently holds only GSO functions but more
will come: in particular, code shared by openvswitch and tc to manipulate
NSH headers.

For now, assume there's no hardware support for NSH segmentation. We can
always introduce netdev->nsh_features later.
Signed-off-by: default avatarJiri Benc <>
Signed-off-by: default avatarDavid S. Miller <>
parent 1f0b7744
......@@ -235,6 +235,7 @@ source "net/openvswitch/Kconfig"
source "net/vmw_vsock/Kconfig"
source "net/netlink/Kconfig"
source "net/mpls/Kconfig"
source "net/nsh/Kconfig"
source "net/hsr/Kconfig"
source "net/switchdev/Kconfig"
source "net/l3mdev/Kconfig"
......@@ -75,6 +75,7 @@ obj-$(CONFIG_NET_IFE) += ife/
obj-$(CONFIG_OPENVSWITCH) += openvswitch/
obj-$(CONFIG_VSOCKETS) += vmw_vsock/
obj-$(CONFIG_MPLS) += mpls/
obj-$(CONFIG_NET_NSH) += nsh/
obj-$(CONFIG_HSR) += hsr/
obj-y += switchdev/
menuconfig NET_NSH
tristate "Network Service Header (NSH) protocol"
default n
Network Service Header is an implementation of Service Function
Chaining (RFC 7665). The current implementation in Linux supports
only MD type 1 and only with the openvswitch module.
If unsure, say N.
obj-$(CONFIG_NET_NSH) += nsh.o
* Network Service Header
* Copyright (c) 2017 Red Hat, Inc. -- Jiri Benc <>
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/nsh.h>
#include <net/tun_proto.h>
static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
netdev_features_t features)
struct sk_buff *segs = ERR_PTR(-EINVAL);
unsigned int nsh_len, mac_len;
__be16 proto;
int nhoff;
nhoff = skb->network_header - skb->mac_header;
mac_len = skb->mac_len;
if (unlikely(!pskb_may_pull(skb, NSH_BASE_HDR_LEN)))
goto out;
nsh_len = nsh_hdr_len(nsh_hdr(skb));
if (unlikely(!pskb_may_pull(skb, nsh_len)))
goto out;
proto = tun_p_to_eth_p(nsh_hdr(skb)->np);
if (!proto)
goto out;
__skb_pull(skb, nsh_len);
skb->protocol = proto;
features &= NETIF_F_SG;
segs = skb_mac_gso_segment(skb, features);
if (IS_ERR_OR_NULL(segs)) {
skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len,
skb->network_header - nhoff,
goto out;
for (skb = segs; skb; skb = skb->next) {
skb->protocol = htons(ETH_P_NSH);
__skb_push(skb, nsh_len);
skb_set_mac_header(skb, -nhoff);
skb->network_header = skb->mac_header + mac_len;
skb->mac_len = mac_len;
return segs;
static struct packet_offload nsh_packet_offload __read_mostly = {
.type = htons(ETH_P_NSH),
.priority = 15,
.callbacks = {
.gso_segment = nsh_gso_segment,
static int __init nsh_init_module(void)
return 0;
static void __exit nsh_cleanup_module(void)
MODULE_AUTHOR("Jiri Benc <>");
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