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#include <net/mpls.h>
 18
 19static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
 20				       netdev_features_t features)
 21{
 22	struct sk_buff *segs = ERR_PTR(-EINVAL);
 23	u16 mac_offset = skb->mac_header;
 24	netdev_features_t mpls_features;
 25	u16 mac_len = skb->mac_len;
 26	__be16 mpls_protocol;
 27	unsigned int mpls_hlen;
 28
 29	skb_reset_network_header(skb);
 30	mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb);
 31	if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN))
 32		goto out;
 33	if (unlikely(!pskb_may_pull(skb, mpls_hlen)))
 34		goto out;
 35
 36	/* Setup inner SKB. */
 37	mpls_protocol = skb->protocol;
 38	skb->protocol = skb->inner_protocol;
 39
 40	__skb_pull(skb, mpls_hlen);
 41
 42	skb->mac_len = 0;
 43	skb_reset_mac_header(skb);
 44
 45	/* Segment inner packet. */
 46	mpls_features = skb->dev->mpls_features & features;
 47	segs = skb_mac_gso_segment(skb, mpls_features);
 48	if (IS_ERR_OR_NULL(segs)) {
 49		skb_gso_error_unwind(skb, mpls_protocol, mpls_hlen, mac_offset,
 50				     mac_len);
 51		goto out;
 52	}
 53	skb = segs;
 54
 55	mpls_hlen += mac_len;
 56	do {
 57		skb->mac_len = mac_len;
 58		skb->protocol = mpls_protocol;
 59
 60		skb_reset_inner_network_header(skb);
 61
 62		__skb_push(skb, mpls_hlen);
 63
 64		skb_reset_mac_header(skb);
 65		skb_set_network_header(skb, mac_len);
 66	} while ((skb = skb->next));
 67
 68out:
 69	return segs;
 70}
 71
 72static struct packet_offload mpls_mc_offload __read_mostly = {
 73	.type = cpu_to_be16(ETH_P_MPLS_MC),
 74	.priority = 15,
 75	.callbacks = {
 76		.gso_segment    =	mpls_gso_segment,
 77	},
 78};
 79
 80static struct packet_offload mpls_uc_offload __read_mostly = {
 81	.type = cpu_to_be16(ETH_P_MPLS_UC),
 82	.priority = 15,
 83	.callbacks = {
 84		.gso_segment    =	mpls_gso_segment,
 85	},
 86};
 87
 88static int __init mpls_gso_init(void)
 89{
 90	pr_info("MPLS GSO support\n");
 91
 92	dev_add_offload(&mpls_uc_offload);
 93	dev_add_offload(&mpls_mc_offload);
 94
 95	return 0;
 96}
 97
 98static void __exit mpls_gso_exit(void)
 99{
100	dev_remove_offload(&mpls_uc_offload);
101	dev_remove_offload(&mpls_mc_offload);
102}
103
104module_init(mpls_gso_init);
105module_exit(mpls_gso_exit);
106
107MODULE_DESCRIPTION("MPLS GSO support");
108MODULE_AUTHOR("Simon Horman (horms@verge.net.au)");
109MODULE_LICENSE("GPL");