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/gso.h>
18#include <net/mpls.h>
19
20static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
21				       netdev_features_t features)
22{
23	struct sk_buff *segs = ERR_PTR(-EINVAL);
24	u16 mac_offset = skb->mac_header;
25	netdev_features_t mpls_features;
26	u16 mac_len = skb->mac_len;
27	__be16 mpls_protocol;
28	unsigned int mpls_hlen;
29
30	if (!skb_inner_network_header_was_set(skb))
31		goto out;
32
33	skb_reset_network_header(skb);
34	mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb);
35	if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN))
36		goto out;
37	if (unlikely(!pskb_may_pull(skb, mpls_hlen)))
38		goto out;
39
40	/* Setup inner SKB. */
41	mpls_protocol = skb->protocol;
42	skb->protocol = skb->inner_protocol;
43
44	__skb_pull(skb, mpls_hlen);
45
46	skb->mac_len = 0;
47	skb_reset_mac_header(skb);
48
49	/* Segment inner packet. */
50	mpls_features = skb->dev->mpls_features & features;
51	segs = skb_mac_gso_segment(skb, mpls_features);
52	if (IS_ERR_OR_NULL(segs)) {
53		skb_gso_error_unwind(skb, mpls_protocol, mpls_hlen, mac_offset,
54				     mac_len);
55		goto out;
56	}
57	skb = segs;
58
59	mpls_hlen += mac_len;
60	do {
61		skb->mac_len = mac_len;
62		skb->protocol = mpls_protocol;
63
64		skb_reset_inner_network_header(skb);
65
66		__skb_push(skb, mpls_hlen);
67
68		skb_reset_mac_header(skb);
69		skb_set_network_header(skb, mac_len);
70	} while ((skb = skb->next));
71
72out:
73	return segs;
74}
75
76static struct packet_offload mpls_mc_offload __read_mostly = {
77	.type = cpu_to_be16(ETH_P_MPLS_MC),
78	.priority = 15,
79	.callbacks = {
80		.gso_segment    =	mpls_gso_segment,
81	},
82};
83
84static struct packet_offload mpls_uc_offload __read_mostly = {
85	.type = cpu_to_be16(ETH_P_MPLS_UC),
86	.priority = 15,
87	.callbacks = {
88		.gso_segment    =	mpls_gso_segment,
89	},
90};
91
92static int __init mpls_gso_init(void)
93{
94	pr_info("MPLS GSO support\n");
95
96	dev_add_offload(&mpls_uc_offload);
97	dev_add_offload(&mpls_mc_offload);
98
99	return 0;
100}
101
102static void __exit mpls_gso_exit(void)
103{
104	dev_remove_offload(&mpls_uc_offload);
105	dev_remove_offload(&mpls_mc_offload);
106}
107
108module_init(mpls_gso_init);
109module_exit(mpls_gso_exit);
110
111MODULE_DESCRIPTION("MPLS GSO support");
112MODULE_AUTHOR("Simon Horman <horms@verge.net.au>");
113MODULE_LICENSE("GPL");
114