2 * IPV4 GSO/GRO offload support
3 * Linux INET implementation
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
13 #include <linux/skbuff.h>
14 #include <net/protocol.h>
17 static int gre_gso_send_check(struct sk_buff *skb)
19 if (!skb->encapsulation)
24 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
25 netdev_features_t features)
27 struct sk_buff *segs = ERR_PTR(-EINVAL);
28 netdev_features_t enc_features;
29 int ghl = GRE_HEADER_SECTION;
30 struct gre_base_hdr *greh;
31 u16 mac_offset = skb->mac_header;
32 int mac_len = skb->mac_len;
33 __be16 protocol = skb->protocol;
37 if (unlikely(skb_shinfo(skb)->gso_type &
47 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
50 greh = (struct gre_base_hdr *)skb_transport_header(skb);
52 if (greh->flags & GRE_KEY)
53 ghl += GRE_HEADER_SECTION;
54 if (greh->flags & GRE_SEQ)
55 ghl += GRE_HEADER_SECTION;
56 if (greh->flags & GRE_CSUM) {
57 ghl += GRE_HEADER_SECTION;
62 if (unlikely(!pskb_may_pull(skb, ghl)))
65 /* setup inner skb. */
66 skb->protocol = greh->protocol;
67 skb->encapsulation = 0;
70 skb_reset_mac_header(skb);
71 skb_set_network_header(skb, skb_inner_network_offset(skb));
72 skb->mac_len = skb_inner_network_offset(skb);
74 /* segment inner packet. */
75 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
76 segs = skb_mac_gso_segment(skb, enc_features);
77 if (!segs || IS_ERR(segs)) {
78 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
83 tnl_hlen = skb_tnl_header_len(skb);
89 if (skb_has_shared_frag(skb)) {
92 err = __skb_linearize(skb);
100 greh = (struct gre_base_hdr *)(skb->data);
101 pcsum = (__be32 *)(greh + 1);
103 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
105 __skb_push(skb, tnl_hlen - ghl);
107 skb_reset_inner_headers(skb);
108 skb->encapsulation = 1;
110 skb_reset_mac_header(skb);
111 skb_set_network_header(skb, mac_len);
112 skb->mac_len = mac_len;
113 skb->protocol = protocol;
114 } while ((skb = skb->next));
119 static const struct net_offload gre_offload = {
121 .gso_send_check = gre_gso_send_check,
122 .gso_segment = gre_gso_segment,
126 static int __init gre_offload_init(void)
128 return inet_add_offload(&gre_offload, IPPROTO_GRE);
131 static void __exit gre_offload_exit(void)
133 inet_del_offload(&gre_offload, IPPROTO_GRE);
136 module_init(gre_offload_init);
137 module_exit(gre_offload_exit);