1/*
2 *	MPLS GSO Support
3 *
4 *	Authors: Simon Horman (horms@verge.net.au)
5 *
6 *	This program is free software; you can redistribute it and/or
7 *	modify it under the terms of the GNU General Public License
8 *	as published by the Free Software Foundation; either version
9 *	2 of the License, or (at your option) any later version.
10 *
11 *	Based on: GSO portions of net/ipv4/gre.c
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/err.h>
17#include <linux/module.h>
18#include <linux/netdev_features.h>
19#include <linux/netdevice.h>
20#include <linux/skbuff.h>
21
22static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
23				       netdev_features_t features)
24{
25	struct sk_buff *segs = ERR_PTR(-EINVAL);
26	netdev_features_t mpls_features;
27	__be16 mpls_protocol;
28
29	if (unlikely(skb_shinfo(skb)->gso_type &
30				~(SKB_GSO_TCPV4 |
31				  SKB_GSO_TCPV6 |
32				  SKB_GSO_UDP |
33				  SKB_GSO_DODGY |
34				  SKB_GSO_TCP_ECN)))
35		goto out;
36
37	/* Setup inner SKB. */
38	mpls_protocol = skb->protocol;
39	skb->protocol = skb->inner_protocol;
40
41	/* Push back the mac header that skb_mac_gso_segment() has pulled.
42	 * It will be re-pulled by the call to skb_mac_gso_segment() below
43	 */
44	__skb_push(skb, skb->mac_len);
45
46	/* Segment inner packet. */
47	mpls_features = skb->dev->mpls_features & features;
48	segs = skb_mac_gso_segment(skb, mpls_features);
49
50
51	/* Restore outer protocol. */
52	skb->protocol = mpls_protocol;
53
54	/* Re-pull the mac header that the call to skb_mac_gso_segment()
55	 * above pulled.  It will be re-pushed after returning
56	 * skb_mac_gso_segment(), an indirect caller of this function.
57	 */
58	__skb_pull(skb, skb->data - skb_mac_header(skb));
59out:
60	return segs;
61}
62
63static struct packet_offload mpls_mc_offload __read_mostly = {
64	.type = cpu_to_be16(ETH_P_MPLS_MC),
65	.callbacks = {
66		.gso_segment    =	mpls_gso_segment,
67	},
68};
69
70static struct packet_offload mpls_uc_offload __read_mostly = {
71	.type = cpu_to_be16(ETH_P_MPLS_UC),
72	.callbacks = {
73		.gso_segment    =	mpls_gso_segment,
74	},
75};
76
77static int __init mpls_gso_init(void)
78{
79	pr_info("MPLS GSO support\n");
80
81	dev_add_offload(&mpls_uc_offload);
82	dev_add_offload(&mpls_mc_offload);
83
84	return 0;
85}
86
87static void __exit mpls_gso_exit(void)
88{
89	dev_remove_offload(&mpls_uc_offload);
90	dev_remove_offload(&mpls_mc_offload);
91}
92
93module_init(mpls_gso_init);
94module_exit(mpls_gso_exit);
95
96MODULE_DESCRIPTION("MPLS GSO support");
97MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
98MODULE_LICENSE("GPL");
99