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 ipv6h = ipv6_hdr(skb);
30 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
32 skb->csum_start = skb_transport_header(skb) - skb->head;
33 skb->csum_offset = offsetof(struct udphdr, check);
34 skb->ip_summed = CHECKSUM_PARTIAL;
38 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
39 netdev_features_t features)
41 struct sk_buff *segs = ERR_PTR(-EINVAL);
43 unsigned int unfrag_ip6hlen, unfrag_len;
44 struct frag_hdr *fptr;
45 u8 *mac_start, *prevhdr;
47 u8 frag_hdr_sz = sizeof(struct frag_hdr);
51 mss = skb_shinfo(skb)->gso_size;
52 if (unlikely(skb->len <= mss))
55 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
56 /* Packet is from an untrusted source, reset gso_segs. */
57 int type = skb_shinfo(skb)->gso_type;
59 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
61 !(type & (SKB_GSO_UDP))))
64 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
70 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
71 * do checksum of UDP packets sent as multiple IP fragments.
73 offset = skb_checksum_start_offset(skb);
74 csum = skb_checksum(skb, offset, skb->len - offset, 0);
75 offset += skb->csum_offset;
76 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
77 skb->ip_summed = CHECKSUM_NONE;
79 /* Check if there is enough headroom to insert fragment header. */
80 if ((skb_mac_header(skb) < skb->head + frag_hdr_sz) &&
81 pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC))
84 /* Find the unfragmentable header and shift it left by frag_hdr_sz
85 * bytes to insert fragment header.
87 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
89 *prevhdr = NEXTHDR_FRAGMENT;
90 unfrag_len = skb_network_header(skb) - skb_mac_header(skb) +
92 mac_start = skb_mac_header(skb);
93 memmove(mac_start-frag_hdr_sz, mac_start, unfrag_len);
95 skb->mac_header -= frag_hdr_sz;
96 skb->network_header -= frag_hdr_sz;
98 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
99 fptr->nexthdr = nexthdr;
101 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
103 /* Fragment the skb. ipv6 header and the remaining fields of the
104 * fragment header are updated in ipv6_gso_segment()
106 segs = skb_segment(skb, features);
111 static const struct net_offload udpv6_offload = {
113 .gso_send_check = udp6_ufo_send_check,
114 .gso_segment = udp6_ufo_fragment,
118 int __init udp_offload_init(void)
120 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);