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
  18 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
  19                                          netdev_features_t features)
  20 {
  21         struct sk_buff *segs = ERR_PTR(-EINVAL);
  22         unsigned int mss;
  23         unsigned int unfrag_ip6hlen, unfrag_len;
  24         struct frag_hdr *fptr;
  25         u8 *packet_start, *prevhdr;
  26         u8 nexthdr;
  27         u8 frag_hdr_sz = sizeof(struct frag_hdr);
  28         __wsum csum;
  29         int tnl_hlen;
  30         int err;
  31
  32         if (skb->encapsulation && skb_shinfo(skb)->gso_type &
  33             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
  34                 segs = skb_udp_tunnel_segment(skb, features, true);
  35         else {
  36                 const struct ipv6hdr *ipv6h;
  37                 struct udphdr *uh;
  38
  39                 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
  40                         goto out;
  41
  42                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  43                         goto out;
  44
  45                 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
  46                         return __udp_gso_segment(skb, features, true);
  47
  48                 mss = skb_shinfo(skb)->gso_size;
  49                 if (unlikely(skb->len <= mss))
  50                         goto out;
  51
  52                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  53                  * do checksum of UDP packets sent as multiple IP fragments.
  54                  */
  55
  56                 uh = udp_hdr(skb);
  57                 ipv6h = ipv6_hdr(skb);
  58
  59                 uh->check = 0;
  60                 csum = skb_checksum(skb, 0, skb->len, 0);
  61                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  62                                           &ipv6h->daddr, csum);
  63                 if (uh->check == 0)
  64                         uh->check = CSUM_MANGLED_0;
  65
  66                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  67
  68                 /* If there is no outer header we can fake a checksum offload
  69                  * due to the fact that we have already done the checksum in
  70                  * software prior to segmenting the frame.
  71                  */
  72                 if (!skb->encap_hdr_csum)
  73                         features |= NETIF_F_HW_CSUM;
  74
  75                 /* Check if there is enough headroom to insert fragment header. */
  76                 tnl_hlen = skb_tnl_header_len(skb);
  77                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  78                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  79                                 goto out;
  80                 }
  81
  82                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  83                  * bytes to insert fragment header.
  84                  */
  85                 err = ip6_find_1stfragopt(skb, &prevhdr);
  86                 if (err < 0)
  87                         return ERR_PTR(err);
  88                 unfrag_ip6hlen = err;
  89                 nexthdr = *prevhdr;
  90                 *prevhdr = NEXTHDR_FRAGMENT;
  91                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  92                              unfrag_ip6hlen + tnl_hlen;
  93                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  94                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  95
  96                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  97                 skb->mac_header -= frag_hdr_sz;
  98                 skb->network_header -= frag_hdr_sz;
  99
 100                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 101                 fptr->nexthdr = nexthdr;
 102                 fptr->reserved = 0;
 103                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 104
 105                 /* Fragment the skb. ipv6 header and the remaining fields of the
 106                  * fragment header are updated in ipv6_gso_segment()
 107                  */
 108                 segs = skb_segment(skb, features);
 109         }
 110
 111 out:
 112         return segs;
 113 }
 114
 115 static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
 116                                         __be16 dport)
 117 {
 118         const struct ipv6hdr *iph = skb_gro_network_header(skb);
 119         struct net *net = dev_net(skb->dev);
 120
 121         return __udp6_lib_lookup(net, &iph->saddr, sport,
 122                                  &iph->daddr, dport, inet6_iif(skb),
 123                                  inet6_sdif(skb), net->ipv4.udp_table, NULL);
 124 }
 125
 126 INDIRECT_CALLABLE_SCOPE
 127 struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 128 {
 129         struct udphdr *uh = udp_gro_udphdr(skb);
 130         struct sock *sk = NULL;
 131         struct sk_buff *pp;
 132
 133         if (unlikely(!uh))
 134                 goto flush;
 135
 136         /* Don't bother verifying checksum if we're going to flush anyway. */
 137         if (NAPI_GRO_CB(skb)->flush)
 138                 goto skip;
 139
 140         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 141                                                  ip6_gro_compute_pseudo))
 142                 goto flush;
 143         else if (uh->check)
 144                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
 145                                              ip6_gro_compute_pseudo);
 146
 147 skip:
 148         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 149
 150         if (static_branch_unlikely(&udpv6_encap_needed_key))
 151                 sk = udp6_gro_lookup_skb(skb, uh->source, uh->dest);
 152
 153         pp = udp_gro_receive(head, skb, uh, sk);
 154         return pp;
 155
 156 flush:
 157         NAPI_GRO_CB(skb)->flush = 1;
 158         return NULL;
 159 }
 160
 161 INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 162 {
 163         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 164         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 165
 166         /* do fraglist only if there is no outer UDP encap (or we already processed it) */
 167         if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
 168                 uh->len = htons(skb->len - nhoff);
 169
 170                 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
 171                 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
 172
 173                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 174                         if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
 175                                 skb->csum_level++;
 176                 } else {
 177                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 178                         skb->csum_level = 0;
 179                 }
 180
 181                 return 0;
 182         }
 183
 184         if (uh->check)
 185                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 186                                           &ipv6h->daddr, 0);
 187
 188         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 189 }
 190
 191 static const struct net_offload udpv6_offload = {
 192         .callbacks = {
 193                 .gso_segment    =       udp6_ufo_fragment,
 194                 .gro_receive    =       udp6_gro_receive,
 195                 .gro_complete   =       udp6_gro_complete,
 196         },
 197 };
 198
 199 int udpv6_offload_init(void)
 200 {
 201         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 202 }
 203
 204 int udpv6_offload_exit(void)
 205 {
 206         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 207 }