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 /* UDP Tunnel offload on ipv6 is not yet supported. */
25 if (skb->encapsulation)
28 if (!pskb_may_pull(skb, sizeof(*uh)))
31 ipv6h = ipv6_hdr(skb);
34 uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
36 skb->csum_start = skb_transport_header(skb) - skb->head;
37 skb->csum_offset = offsetof(struct udphdr, check);
38 skb->ip_summed = CHECKSUM_PARTIAL;
42 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
43 netdev_features_t features)
45 struct sk_buff *segs = ERR_PTR(-EINVAL);
47 unsigned int unfrag_ip6hlen, unfrag_len;
48 struct frag_hdr *fptr;
49 u8 *mac_start, *prevhdr;
51 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 |
67 !(type & (SKB_GSO_UDP))))
70 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
76 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
77 * do checksum of UDP packets sent as multiple IP fragments.
79 offset = skb_checksum_start_offset(skb);
80 csum = skb_checksum(skb, offset, skb->len - offset, 0);
81 offset += skb->csum_offset;
82 *(__sum16 *)(skb->data + offset) = csum_fold(csum);
83 skb->ip_summed = CHECKSUM_NONE;
85 /* Check if there is enough headroom to insert fragment header. */
86 if ((skb_mac_header(skb) < skb->head + frag_hdr_sz) &&
87 pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC))
90 /* Find the unfragmentable header and shift it left by frag_hdr_sz
91 * bytes to insert fragment header.
93 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
95 *prevhdr = NEXTHDR_FRAGMENT;
96 unfrag_len = skb_network_header(skb) - skb_mac_header(skb) +
98 mac_start = skb_mac_header(skb);
99 memmove(mac_start-frag_hdr_sz, mac_start, unfrag_len);
101 skb->mac_header -= frag_hdr_sz;
102 skb->network_header -= frag_hdr_sz;
104 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
105 fptr->nexthdr = nexthdr;
107 ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
109 /* Fragment the skb. ipv6 header and the remaining fields of the
110 * fragment header are updated in ipv6_gso_segment()
112 segs = skb_segment(skb, features);
117 static const struct net_offload udpv6_offload = {
119 .gso_send_check = udp6_ufo_send_check,
120 .gso_segment = udp6_ufo_fragment,
124 int __init udp_offload_init(void)
126 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);