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>
15 #include <net/protocol.h>
17 static int udp4_ufo_send_check(struct sk_buff *skb)
19 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
22 if (likely(!skb->encapsulation)) {
23 const struct iphdr *iph;
29 uh->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, skb->len,
31 skb->csum_start = skb_transport_header(skb) - skb->head;
32 skb->csum_offset = offsetof(struct udphdr, check);
33 skb->ip_summed = CHECKSUM_PARTIAL;
39 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
40 netdev_features_t features)
42 struct sk_buff *segs = ERR_PTR(-EINVAL);
47 if (skb->encapsulation &&
48 skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) {
49 segs = skb_udp_tunnel_segment(skb, features);
53 mss = skb_shinfo(skb)->gso_size;
54 if (unlikely(skb->len <= mss))
57 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
58 /* Packet is from an untrusted source, reset gso_segs. */
59 int type = skb_shinfo(skb)->gso_type;
61 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
64 SKB_GSO_GRE | SKB_GSO_MPLS) ||
65 !(type & (SKB_GSO_UDP))))
68 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
74 /* Do software UFO. Complete and fill in the UDP checksum as
75 * HW cannot do checksum of UDP packets sent as multiple
78 offset = skb_checksum_start_offset(skb);
79 csum = skb_checksum(skb, offset, skb->len - offset, 0);
80 offset += skb->csum_offset;
81 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
82 skb->ip_summed = CHECKSUM_NONE;
84 /* Fragment the skb. IP headers of the fragments are updated in
87 segs = skb_segment(skb, features);
92 static const struct net_offload udpv4_offload = {
94 .gso_send_check = udp4_ufo_send_check,
95 .gso_segment = udp4_ufo_fragment,
99 int __init udpv4_offload_init(void)
101 return inet_add_offload(&udpv4_offload, IPPROTO_UDP);