1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *	MPLS GSO Support
  4 *
  5 *	Authors: Simon Horman (horms@verge.net.au)
  6 *
  7 *	Based on: GSO portions of net/ipv4/gre.c
  8 */
  9
 10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 11
 12#include <linux/err.h>
 13#include <linux/module.h>
 14#include <linux/netdev_features.h>
 15#include <linux/netdevice.h>
 16#include <linux/skbuff.h>
 17
 18static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
 19				       netdev_features_t features)
 20{
 21	struct sk_buff *segs = ERR_PTR(-EINVAL);
 22	u16 mac_offset = skb->mac_header;
 23	netdev_features_t mpls_features;
 24	u16 mac_len = skb->mac_len;
 25	__be16 mpls_protocol;
 26	unsigned int mpls_hlen;
 27
 28	skb_reset_network_header(skb);
 29	mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb);
 30	if (unlikely(!pskb_may_pull(skb, mpls_hlen)))
 31		goto out;
 32
 33	/* Setup inner SKB. */
 34	mpls_protocol = skb->protocol;
 35	skb->protocol = skb->inner_protocol;
 36
 37	__skb_pull(skb, mpls_hlen);
 38
 39	skb->mac_len = 0;
 40	skb_reset_mac_header(skb);
 41
 42	/* Segment inner packet. */
 43	mpls_features = skb->dev->mpls_features & features;
 44	segs = skb_mac_gso_segment(skb, mpls_features);
 45	if (IS_ERR_OR_NULL(segs)) {
 46		skb_gso_error_unwind(skb, mpls_protocol, mpls_hlen, mac_offset,
 47				     mac_len);
 48		goto out;
 49	}
 50	skb = segs;
 51
 52	mpls_hlen += mac_len;
 53	do {
 54		skb->mac_len = mac_len;
 55		skb->protocol = mpls_protocol;
 56
 57		skb_reset_inner_network_header(skb);
 58
 59		__skb_push(skb, mpls_hlen);
 60
 61		skb_reset_mac_header(skb);
 62		skb_set_network_header(skb, mac_len);
 63	} while ((skb = skb->next));
 64
 65out:
 66	return segs;
 67}
 68
 69static struct packet_offload mpls_mc_offload __read_mostly = {
 70	.type = cpu_to_be16(ETH_P_MPLS_MC),
 71	.priority = 15,
 72	.callbacks = {
 73		.gso_segment    =	mpls_gso_segment,
 74	},
 75};
 76
 77static struct packet_offload mpls_uc_offload __read_mostly = {
 78	.type = cpu_to_be16(ETH_P_MPLS_UC),
 79	.priority = 15,
 80	.callbacks = {
 81		.gso_segment    =	mpls_gso_segment,
 82	},
 83};
 84
 85static int __init mpls_gso_init(void)
 86{
 87	pr_info("MPLS GSO support\n");
 88
 89	dev_add_offload(&mpls_uc_offload);
 90	dev_add_offload(&mpls_mc_offload);
 91
 92	return 0;
 93}
 94
 95static void __exit mpls_gso_exit(void)
 96{
 97	dev_remove_offload(&mpls_uc_offload);
 98	dev_remove_offload(&mpls_mc_offload);
 99}
100
101module_init(mpls_gso_init);
102module_exit(mpls_gso_exit);
103
104MODULE_DESCRIPTION("MPLS GSO support");
105MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
106MODULE_LICENSE("GPL");