net/ipv6/udp_offload.c

   1 /*
   2  *      IPV6 GSO/GRO offload support
   3  *      Linux INET6 implementation
   4  *
   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.
   9  *
  10  *      UDPv6 GSO support
  11  */
  12 #include <linux/skbuff.h>
  13 #include <linux/netdevice.h>
  14 #include <net/protocol.h>
  15 #include <net/ipv6.h>
  16 #include <net/udp.h>
  17 #include <net/ip6_checksum.h>
  18 #include "ip6_offload.h"
  19
  20 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  21                                          netdev_features_t features)
  22 {
  23         struct sk_buff *segs = ERR_PTR(-EINVAL);
  24         unsigned int mss;
  25         unsigned int unfrag_ip6hlen, unfrag_len;
  26         struct frag_hdr *fptr;
  27         u8 *packet_start, *prevhdr;
  28         u8 nexthdr;
  29         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  30         __wsum csum;
  31         int tnl_hlen;
  32
  33         mss = skb_shinfo(skb)->gso_size;
  34         if (unlikely(skb->len <= mss))
  35                 goto out;
  36
  37         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  38                 /* Packet is from an untrusted source, reset gso_segs. */
  39                 int type = skb_shinfo(skb)->gso_type;
  40
  41                 if (unlikely(type & ~(SKB_GSO_UDP |
  42                                       SKB_GSO_DODGY |
  43                                       SKB_GSO_UDP_TUNNEL |
  44                                       SKB_GSO_UDP_TUNNEL_CSUM |
  45                                       SKB_GSO_TUNNEL_REMCSUM |
  46                                       SKB_GSO_GRE |
  47                                       SKB_GSO_GRE_CSUM |
  48                                       SKB_GSO_IPIP |
  49                                       SKB_GSO_SIT) ||
  50                              !(type & (SKB_GSO_UDP))))
  51                         goto out;
  52
  53                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  54
  55                 /* Set the IPv6 fragment id if not set yet */
  56                 if (!skb_shinfo(skb)->ip6_frag_id)
  57                         ipv6_proxy_select_ident(skb);
  58
  59                 segs = NULL;
  60                 goto out;
  61         }
  62
  63         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  64             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  65                 segs = skb_udp_tunnel_segment(skb, features, true);
  66         else {
  67                 const struct ipv6hdr *ipv6h;
  68                 struct udphdr *uh;
  69
  70                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  71                         goto out;
  72
  73                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  74                  * do checksum of UDP packets sent as multiple IP fragments.
  75                  */
  76
  77                 uh = udp_hdr(skb);
  78                 ipv6h = ipv6_hdr(skb);
  79
  80                 uh->check = 0;
  81                 csum = skb_checksum(skb, 0, skb->len, 0);
  82                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  83                                           &ipv6h->daddr, csum);
  84
  85                 if (uh->check == 0)
  86                         uh->check = CSUM_MANGLED_0;
  87
  88                 skb->ip_summed = CHECKSUM_NONE;
  89
  90                 /* Check if there is enough headroom to insert fragment header. */
  91                 tnl_hlen = skb_tnl_header_len(skb);
  92                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  93                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  94                                 goto out;
  95                 }
  96
  97                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  98                  * bytes to insert fragment header.
  99                  */
 100                 unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 101                 nexthdr = *prevhdr;
 102                 *prevhdr = NEXTHDR_FRAGMENT;
 103                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
 104                              unfrag_ip6hlen + tnl_hlen;
 105                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
 106                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
 107
 108                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 109                 skb->mac_header -= frag_hdr_sz;
 110                 skb->network_header -= frag_hdr_sz;
 111
 112                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 113                 fptr->nexthdr = nexthdr;
 114                 fptr->reserved = 0;
 115                 if (skb_shinfo(skb)->ip6_frag_id)
 116                         fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 117                 else
 118                         ipv6_select_ident(fptr,
 119                                           (struct rt6_info *)skb_dst(skb));
 120
 121                 /* Fragment the skb. ipv6 header and the remaining fields of the
 122                  * fragment header are updated in ipv6_gso_segment()
 123                  */
 124                 segs = skb_segment(skb, features);
 125         }
 126
 127 out:
 128         return segs;
 129 }
 130
 131 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
 132                                          struct sk_buff *skb)
 133 {
 134         struct udphdr *uh = udp_gro_udphdr(skb);
 135
 136         if (unlikely(!uh))
 137                 goto flush;
 138
 139         /* Don't bother verifying checksum if we're going to flush anyway. */
 140         if (NAPI_GRO_CB(skb)->flush)
 141                 goto skip;
 142
 143         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 144                                                  ip6_gro_compute_pseudo))
 145                 goto flush;
 146         else if (uh->check)
 147                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 148                                              ip6_gro_compute_pseudo);
 149
 150 skip:
 151         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 152         return udp_gro_receive(head, skb, uh);
 153
 154 flush:
 155         NAPI_GRO_CB(skb)->flush = 1;
 156         return NULL;
 157 }
 158
 159 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 160 {
 161         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 162         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 163
 164         if (uh->check)
 165                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 166                                           &ipv6h->daddr, 0);
 167
 168         return udp_gro_complete(skb, nhoff);
 169 }
 170
 171 static const struct net_offload udpv6_offload = {
 172         .callbacks = {
 173                 .gso_segment    =       udp6_ufo_fragment,
 174                 .gro_receive    =       udp6_gro_receive,
 175                 .gro_complete   =       udp6_gro_complete,
 176         },
 177 };
 178
 179 int __init udp_offload_init(void)
 180 {
 181         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 182 }