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 int mac_len = skb->mac_len;
32 __be16 protocol = skb->protocol;
36 if (unlikely(skb_shinfo(skb)->gso_type &
45 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
48 greh = (struct gre_base_hdr *)skb_transport_header(skb);
50 if (greh->flags & GRE_KEY)
51 ghl += GRE_HEADER_SECTION;
52 if (greh->flags & GRE_SEQ)
53 ghl += GRE_HEADER_SECTION;
54 if (greh->flags & GRE_CSUM) {
55 ghl += GRE_HEADER_SECTION;
60 /* setup inner skb. */
61 skb->protocol = greh->protocol;
62 skb->encapsulation = 0;
64 if (unlikely(!pskb_may_pull(skb, ghl)))
68 skb_reset_mac_header(skb);
69 skb_set_network_header(skb, skb_inner_network_offset(skb));
70 skb->mac_len = skb_inner_network_offset(skb);
72 /* segment inner packet. */
73 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
74 segs = skb_mac_gso_segment(skb, enc_features);
75 if (!segs || IS_ERR(segs))
79 tnl_hlen = skb_tnl_header_len(skb);
85 if (skb_has_shared_frag(skb)) {
88 err = __skb_linearize(skb);
96 greh = (struct gre_base_hdr *)(skb->data);
97 pcsum = (__be32 *)(greh + 1);
99 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
101 __skb_push(skb, tnl_hlen - ghl);
103 skb_reset_mac_header(skb);
104 skb_set_network_header(skb, mac_len);
105 skb->mac_len = mac_len;
106 skb->protocol = protocol;
107 } while ((skb = skb->next));
112 static const struct net_offload gre_offload = {
114 .gso_send_check = gre_gso_send_check,
115 .gso_segment = gre_gso_segment,
119 int __init gre_offload_init(void)
121 return inet_add_offload(&gre_offload, IPPROTO_GRE);
124 void __exit gre_offload_exit(void)
126 inet_del_offload(&gre_offload, IPPROTO_GRE);