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	.priority = 15,
 66	.callbacks = {
 67		.gso_segment    =	mpls_gso_segment,
 68	},
 69};
 70
 71static struct packet_offload mpls_uc_offload __read_mostly = {
 72	.type = cpu_to_be16(ETH_P_MPLS_UC),
 73	.priority = 15,
 74	.callbacks = {
 75		.gso_segment    =	mpls_gso_segment,
 76	},
 77};
 78
 79static int __init mpls_gso_init(void)
 80{
 81	pr_info("MPLS GSO support\n");
 82
 83	dev_add_offload(&mpls_uc_offload);
 84	dev_add_offload(&mpls_mc_offload);
 85
 86	return 0;
 87}
 88
 89static void __exit mpls_gso_exit(void)
 90{
 91	dev_remove_offload(&mpls_uc_offload);
 92	dev_remove_offload(&mpls_mc_offload);
 93}
 94
 95module_init(mpls_gso_init);
 96module_exit(mpls_gso_exit);
 97
 98MODULE_DESCRIPTION("MPLS GSO support");
 99MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
100MODULE_LICENSE("GPL");