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 <linux/indirect_call_wrapper.h>
  15 #include <net/protocol.h>
  16 #include <net/ipv6.h>
  17 #include <net/udp.h>
  18 #include <net/ip6_checksum.h>
  19 #include "ip6_offload.h"
  20
  21 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  22                                          netdev_features_t features)
  23 {
  24         struct sk_buff *segs = ERR_PTR(-EINVAL);
  25         unsigned int mss;
  26         unsigned int unfrag_ip6hlen, unfrag_len;
  27         struct frag_hdr *fptr;
  28         u8 *packet_start, *prevhdr;
  29         u8 nexthdr;
  30         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  31         __wsum csum;
  32         int tnl_hlen;
  33         int err;
  34
  35         mss = skb_shinfo(skb)->gso_size;
  36         if (unlikely(skb->len <= mss))
  37                 goto out;
  38
  39         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  40             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  41                 segs = skb_udp_tunnel_segment(skb, features, true);
  42         else {
  43                 const struct ipv6hdr *ipv6h;
  44                 struct udphdr *uh;
  45
  46                 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
  47                         goto out;
  48
  49                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  50                         goto out;
  51
  52                 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
  53                         return __udp_gso_segment(skb, features);
  54
  55                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  56                  * do checksum of UDP packets sent as multiple IP fragments.
  57                  */
  58
  59                 uh = udp_hdr(skb);
  60                 ipv6h = ipv6_hdr(skb);
  61
  62                 uh->check = 0;
  63                 csum = skb_checksum(skb, 0, skb->len, 0);
  64                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  65                                           &ipv6h->daddr, csum);
  66                 if (uh->check == 0)
  67                         uh->check = CSUM_MANGLED_0;
  68
  69                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  70
  71                 /* If there is no outer header we can fake a checksum offload
  72                  * due to the fact that we have already done the checksum in
  73                  * software prior to segmenting the frame.
  74                  */
  75                 if (!skb->encap_hdr_csum)
  76                         features |= NETIF_F_HW_CSUM;
  77
  78                 /* Check if there is enough headroom to insert fragment header. */
  79                 tnl_hlen = skb_tnl_header_len(skb);
  80                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  81                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  82                                 goto out;
  83                 }
  84
  85                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  86                  * bytes to insert fragment header.
  87                  */
  88                 err = ip6_find_1stfragopt(skb, &prevhdr);
  89                 if (err < 0)
  90                         return ERR_PTR(err);
  91                 unfrag_ip6hlen = err;
  92                 nexthdr = *prevhdr;
  93                 *prevhdr = NEXTHDR_FRAGMENT;
  94                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  95                              unfrag_ip6hlen + tnl_hlen;
  96                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  97                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  98
  99                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
 100                 skb->mac_header -= frag_hdr_sz;
 101                 skb->network_header -= frag_hdr_sz;
 102
 103                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 104                 fptr->nexthdr = nexthdr;
 105                 fptr->reserved = 0;
 106                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 107
 108                 /* Fragment the skb. ipv6 header and the remaining fields of the
 109                  * fragment header are updated in ipv6_gso_segment()
 110                  */
 111                 segs = skb_segment(skb, features);
 112         }
 113
 114 out:
 115         return segs;
 116 }
 117
 118 INDIRECT_CALLABLE_SCOPE
 119 struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 120 {
 121         struct udphdr *uh = udp_gro_udphdr(skb);
 122
 123         if (unlikely(!uh) || !static_branch_unlikely(&udpv6_encap_needed_key))
 124                 goto flush;
 125
 126         /* Don't bother verifying checksum if we're going to flush anyway. */
 127         if (NAPI_GRO_CB(skb)->flush)
 128                 goto skip;
 129
 130         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 131                                                  ip6_gro_compute_pseudo))
 132                 goto flush;
 133         else if (uh->check)
 134                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 135                                              ip6_gro_compute_pseudo);
 136
 137 skip:
 138         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 139         return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
 140
 141 flush:
 142         NAPI_GRO_CB(skb)->flush = 1;
 143         return NULL;
 144 }
 145
 146 INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 147 {
 148         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 149         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 150
 151         if (uh->check)
 152                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 153                                           &ipv6h->daddr, 0);
 154
 155         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 156 }
 157
 158 static const struct net_offload udpv6_offload = {
 159         .callbacks = {
 160                 .gso_segment    =       udp6_ufo_fragment,
 161                 .gro_receive    =       udp6_gro_receive,
 162                 .gro_complete   =       udp6_gro_complete,
 163         },
 164 };
 165
 166 int udpv6_offload_init(void)
 167 {
 168         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 169 }
 170
 171 int udpv6_offload_exit(void)
 172 {
 173         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 174 }