2 * IPV6 GSO/GRO offload support
3 * Linux INET6 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.
12 #include <linux/skbuff.h>
13 #include <net/protocol.h>
16 #include <net/ip6_checksum.h>
17 #include "ip6_offload.h"
19 static int udp6_ufo_send_check(struct sk_buff *skb)
21 const struct ipv6hdr *ipv6h;
24 if (!pskb_may_pull(skb, sizeof(*uh)))
27 if (likely(!skb->encapsulation)) {
28 ipv6h = ipv6_hdr(skb);
31 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
33 skb->csum_start = skb_transport_header(skb) - skb->head;
34 skb->csum_offset = offsetof(struct udphdr, check);
35 skb->ip_summed = CHECKSUM_PARTIAL;
41 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
42 netdev_features_t features)
44 struct sk_buff *segs = ERR_PTR(-EINVAL);
46 unsigned int unfrag_ip6hlen, unfrag_len;
47 struct frag_hdr *fptr;
48 u8 *packet_start, *prevhdr;
50 u8 frag_hdr_sz = sizeof(struct frag_hdr);
55 mss = skb_shinfo(skb)->gso_size;
56 if (unlikely(skb->len <= mss))
59 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
60 /* Packet is from an untrusted source, reset gso_segs. */
61 int type = skb_shinfo(skb)->gso_type;
63 if (unlikely(type & ~(SKB_GSO_UDP |
70 !(type & (SKB_GSO_UDP))))
73 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
79 if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL)
80 segs = skb_udp_tunnel_segment(skb, features);
82 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
83 * do checksum of UDP packets sent as multiple IP fragments.
85 offset = skb_checksum_start_offset(skb);
86 csum = skb_checksum(skb, offset, skb->len - offset, 0);
87 offset += skb->csum_offset;
88 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
89 skb->ip_summed = CHECKSUM_NONE;
91 /* Check if there is enough headroom to insert fragment header. */
92 tnl_hlen = skb_tnl_header_len(skb);
93 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
94 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
98 /* Find the unfragmentable header and shift it left by frag_hdr_sz
99 * bytes to insert fragment header.
101 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
103 *prevhdr = NEXTHDR_FRAGMENT;
104 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
105 unfrag_ip6hlen + tnl_hlen;
106 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
107 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
109 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
110 skb->mac_header -= frag_hdr_sz;
111 skb->network_header -= frag_hdr_sz;
113 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
114 fptr->nexthdr = nexthdr;
116 fptr->identification = skb_shinfo(skb)->ip6_frag_id;
118 /* Fragment the skb. ipv6 header and the remaining fields of the
119 * fragment header are updated in ipv6_gso_segment()
121 segs = skb_segment(skb, features);
127 static const struct net_offload udpv6_offload = {
129 .gso_send_check = udp6_ufo_send_check,
130 .gso_segment = udp6_ufo_fragment,
134 int __init udp_offload_init(void)
136 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);