net/ipv6/udp_offload.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      IPV6 GSO/GRO offload support
   4  *      Linux INET6 implementation
   5  *
   6  *      UDPv6 GSO support
   7  */
   8 #include <linux/skbuff.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/indirect_call_wrapper.h>
  11 #include <net/protocol.h>
  12 #include <net/ipv6.h>
  13 #include <net/udp.h>
  14 #include <net/ip6_checksum.h>
  15 #include "ip6_offload.h"
  16 #include <net/gro.h>
  17 #include <net/gso.h>
  18
  19 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  20                                          netdev_features_t features)
  21 {
  22         struct sk_buff *segs = ERR_PTR(-EINVAL);
  23         unsigned int mss;
  24         unsigned int unfrag_ip6hlen, unfrag_len;
  25         struct frag_hdr *fptr;
  26         u8 *packet_start, *prevhdr;
  27         u8 nexthdr;
  28         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  29         __wsum csum;
  30         int tnl_hlen;
  31         int err;
  32
  33         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  34             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  35                 segs = skb_udp_tunnel_segment(skb, features, true);
  36         else {
  37                 const struct ipv6hdr *ipv6h;
  38                 struct udphdr *uh;
  39
  40                 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
  41                         goto out;
  42
  43                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  44                         goto out;
  45
  46                 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
  47                         return __udp_gso_segment(skb, features, true);
  48
  49                 mss = skb_shinfo(skb)->gso_size;
  50                 if (unlikely(skb->len <= mss))
  51                         goto out;
  52
  53                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  54                  * do checksum of UDP packets sent as multiple IP fragments.
  55                  */
  56
  57                 uh = udp_hdr(skb);
  58                 ipv6h = ipv6_hdr(skb);
  59
  60                 uh->check = 0;
  61                 csum = skb_checksum(skb, 0, skb->len, 0);
  62                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  63                                           &ipv6h->daddr, csum);
  64                 if (uh->check == 0)
  65                         uh->check = CSUM_MANGLED_0;
  66
  67                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  68
  69                 /* If there is no outer header we can fake a checksum offload
  70                  * due to the fact that we have already done the checksum in
  71                  * software prior to segmenting the frame.
  72                  */
  73                 if (!skb->encap_hdr_csum)
  74                         features |= NETIF_F_HW_CSUM;
  75
  76                 /* Check if there is enough headroom to insert fragment header. */
  77                 tnl_hlen = skb_tnl_header_len(skb);
  78                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  79                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  80                                 goto out;
  81                 }
  82
  83                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  84                  * bytes to insert fragment header.
  85                  */
  86                 err = ip6_find_1stfragopt(skb, &prevhdr);
  87                 if (err < 0)
  88                         return ERR_PTR(err);
  89                 unfrag_ip6hlen = err;
  90                 nexthdr = *prevhdr;
  91                 *prevhdr = NEXTHDR_FRAGMENT;
  92                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  93                              unfrag_ip6hlen + tnl_hlen;
  94                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  95                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  96
  97                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  98                 skb->mac_header -= frag_hdr_sz;
  99                 skb->network_header -= frag_hdr_sz;
 100
 101                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 102                 fptr->nexthdr = nexthdr;
 103                 fptr->reserved = 0;
 104                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 105
 106                 /* Fragment the skb. ipv6 header and the remaining fields of the
 107                  * fragment header are updated in ipv6_gso_segment()
 108                  */
 109                 segs = skb_segment(skb, features);
 110         }
 111
 112 out:
 113         return segs;
 114 }
 115
 116 static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
 117                                         __be16 dport)
 118 {
 119         const struct ipv6hdr *iph = skb_gro_network_header(skb);
 120         struct net *net = dev_net(skb->dev);
 121         int iif, sdif;
 122
 123         inet6_get_iif_sdif(skb, &iif, &sdif);
 124
 125         return __udp6_lib_lookup(net, &iph->saddr, sport,
 126                                  &iph->daddr, dport, iif,
 127                                  sdif, net->ipv4.udp_table, NULL);
 128 }
 129
 130 INDIRECT_CALLABLE_SCOPE
 131 struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 132 {
 133         struct udphdr *uh = udp_gro_udphdr(skb);
 134         struct sock *sk = NULL;
 135         struct sk_buff *pp;
 136
 137         if (unlikely(!uh))
 138                 goto flush;
 139
 140         /* Don't bother verifying checksum if we're going to flush anyway. */
 141         if (NAPI_GRO_CB(skb)->flush)
 142                 goto skip;
 143
 144         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 145                                                  ip6_gro_compute_pseudo))
 146                 goto flush;
 147         else if (uh->check)
 148                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
 149                                              ip6_gro_compute_pseudo);
 150
 151 skip:
 152         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 153
 154         if (static_branch_unlikely(&udpv6_encap_needed_key))
 155                 sk = udp6_gro_lookup_skb(skb, uh->source, uh->dest);
 156
 157         pp = udp_gro_receive(head, skb, uh, sk);
 158         return pp;
 159
 160 flush:
 161         NAPI_GRO_CB(skb)->flush = 1;
 162         return NULL;
 163 }
 164
 165 INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 166 {
 167         const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
 168         const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + offset);
 169         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 170
 171         /* do fraglist only if there is no outer UDP encap (or we already processed it) */
 172         if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
 173                 uh->len = htons(skb->len - nhoff);
 174
 175                 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
 176                 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
 177
 178                 __skb_incr_checksum_unnecessary(skb);
 179
 180                 return 0;
 181         }
 182
 183         if (uh->check)
 184                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 185                                           &ipv6h->daddr, 0);
 186
 187         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 188 }
 189
 190 int __init udpv6_offload_init(void)
 191 {
 192         net_hotdata.udpv6_offload = (struct net_offload) {
 193                 .callbacks = {
 194                         .gso_segment    =       udp6_ufo_fragment,
 195                         .gro_receive    =       udp6_gro_receive,
 196                         .gro_complete   =       udp6_gro_complete,
 197                 },
 198         };
 199         return inet6_add_offload(&net_hotdata.udpv6_offload, IPPROTO_UDP);
 200 }
 201
 202 int udpv6_offload_exit(void)
 203 {
 204         return inet6_del_offload(&net_hotdata.udpv6_offload, IPPROTO_UDP);
 205 }