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 "ip6_offload.h"
18 static int udp6_ufo_send_check(struct sk_buff *skb)
20 const struct ipv6hdr *ipv6h;
23 if (!pskb_may_pull(skb, sizeof(*uh)))
26 ipv6h = ipv6_hdr(skb);
29 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->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;
37 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
38 netdev_features_t features)
40 struct sk_buff *segs = ERR_PTR(-EINVAL);
42 unsigned int unfrag_ip6hlen, unfrag_len;
43 struct frag_hdr *fptr;
44 u8 *mac_start, *prevhdr;
46 u8 frag_hdr_sz = sizeof(struct frag_hdr);
50 mss = skb_shinfo(skb)->gso_size;
51 if (unlikely(skb->len <= mss))
54 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
55 /* Packet is from an untrusted source, reset gso_segs. */
56 int type = skb_shinfo(skb)->gso_type;
58 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY) ||
59 !(type & (SKB_GSO_UDP))))
62 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
68 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
69 * do checksum of UDP packets sent as multiple IP fragments.
71 offset = skb_checksum_start_offset(skb);
72 csum = skb_checksum(skb, offset, skb->len - offset, 0);
73 offset += skb->csum_offset;
74 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
75 skb->ip_summed = CHECKSUM_NONE;
77 /* Check if there is enough headroom to insert fragment header. */
78 if ((skb_mac_header(skb) < skb->head + frag_hdr_sz) &&
79 pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC))
82 /* Find the unfragmentable header and shift it left by frag_hdr_sz
83 * bytes to insert fragment header.
85 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
87 *prevhdr = NEXTHDR_FRAGMENT;
88 unfrag_len = skb_network_header(skb) - skb_mac_header(skb) +
90 mac_start = skb_mac_header(skb);
91 memmove(mac_start-frag_hdr_sz, mac_start, unfrag_len);
93 skb->mac_header -= frag_hdr_sz;
94 skb->network_header -= frag_hdr_sz;
96 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
97 fptr->nexthdr = nexthdr;
99 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
101 /* Fragment the skb. ipv6 header and the remaining fields of the
102 * fragment header are updated in ipv6_gso_segment()
104 segs = skb_segment(skb, features);
109 static const struct net_offload udpv6_offload = {
111 .gso_send_check = udp6_ufo_send_check,
112 .gso_segment = udp6_ufo_fragment,
116 int __init udp_offload_init(void)
118 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);