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                     !skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST))
  48                         return __udp_gso_segment(skb, features, true);
  49
  50                 mss = skb_shinfo(skb)->gso_size;
  51                 if (unlikely(skb->len <= mss))
  52                         goto out;
  53
  54                 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  55                  * do checksum of UDP packets sent as multiple IP fragments.
  56                  */
  57
  58                 uh = udp_hdr(skb);
  59                 ipv6h = ipv6_hdr(skb);
  60
  61                 uh->check = 0;
  62                 csum = skb_checksum(skb, 0, skb->len, 0);
  63                 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
  64                                           &ipv6h->daddr, csum);
  65                 if (uh->check == 0)
  66                         uh->check = CSUM_MANGLED_0;
  67
  68                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  69
  70                 /* If there is no outer header we can fake a checksum offload
  71                  * due to the fact that we have already done the checksum in
  72                  * software prior to segmenting the frame.
  73                  */
  74                 if (!skb->encap_hdr_csum)
  75                         features |= NETIF_F_HW_CSUM;
  76
  77                 /* Check if there is enough headroom to insert fragment header. */
  78                 tnl_hlen = skb_tnl_header_len(skb);
  79                 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
  80                         if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
  81                                 goto out;
  82                 }
  83
  84                 /* Find the unfragmentable header and shift it left by frag_hdr_sz
  85                  * bytes to insert fragment header.
  86                  */
  87                 err = ip6_find_1stfragopt(skb, &prevhdr);
  88                 if (err < 0)
  89                         return ERR_PTR(err);
  90                 unfrag_ip6hlen = err;
  91                 nexthdr = *prevhdr;
  92                 *prevhdr = NEXTHDR_FRAGMENT;
  93                 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
  94                              unfrag_ip6hlen + tnl_hlen;
  95                 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
  96                 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
  97
  98                 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
  99                 skb->mac_header -= frag_hdr_sz;
 100                 skb->network_header -= frag_hdr_sz;
 101
 102                 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
 103                 fptr->nexthdr = nexthdr;
 104                 fptr->reserved = 0;
 105                 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
 106
 107                 /* Fragment the skb. ipv6 header and the remaining fields of the
 108                  * fragment header are updated in ipv6_gso_segment()
 109                  */
 110                 segs = skb_segment(skb, features);
 111         }
 112
 113 out:
 114         return segs;
 115 }
 116
 117 static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
 118                                         __be16 dport)
 119 {
 120         const struct ipv6hdr *iph = skb_gro_network_header(skb);
 121         struct net *net = dev_net(skb->dev);
 122
 123         return __udp6_lib_lookup(net, &iph->saddr, sport,
 124                                  &iph->daddr, dport, inet6_iif(skb),
 125                                  inet6_sdif(skb), net->ipv4.udp_table, NULL);
 126 }
 127
 128 INDIRECT_CALLABLE_SCOPE
 129 struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 130 {
 131         struct udphdr *uh = udp_gro_udphdr(skb);
 132         struct sock *sk = NULL;
 133         struct sk_buff *pp;
 134
 135         if (unlikely(!uh))
 136                 goto flush;
 137
 138         /* Don't bother verifying checksum if we're going to flush anyway. */
 139         if (NAPI_GRO_CB(skb)->flush)
 140                 goto skip;
 141
 142         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 143                                                  ip6_gro_compute_pseudo))
 144                 goto flush;
 145         else if (uh->check)
 146                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
 147                                              ip6_gro_compute_pseudo);
 148
 149 skip:
 150         NAPI_GRO_CB(skb)->is_ipv6 = 1;
 151
 152         if (static_branch_unlikely(&udpv6_encap_needed_key))
 153                 sk = udp6_gro_lookup_skb(skb, uh->source, uh->dest);
 154
 155         pp = udp_gro_receive(head, skb, uh, sk);
 156         return pp;
 157
 158 flush:
 159         NAPI_GRO_CB(skb)->flush = 1;
 160         return NULL;
 161 }
 162
 163 INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 164 {
 165         const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 166         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 167
 168         /* do fraglist only if there is no outer UDP encap (or we already processed it) */
 169         if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
 170                 uh->len = htons(skb->len - nhoff);
 171
 172                 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
 173                 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
 174
 175                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 176                         if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
 177                                 skb->csum_level++;
 178                 } else {
 179                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 180                         skb->csum_level = 0;
 181                 }
 182
 183                 return 0;
 184         }
 185
 186         if (uh->check)
 187                 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
 188                                           &ipv6h->daddr, 0);
 189
 190         return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 191 }
 192
 193 static const struct net_offload udpv6_offload = {
 194         .callbacks = {
 195                 .gso_segment    =       udp6_ufo_fragment,
 196                 .gro_receive    =       udp6_gro_receive,
 197                 .gro_complete   =       udp6_gro_complete,
 198         },
 199 };
 200
 201 int udpv6_offload_init(void)
 202 {
 203         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
 204 }
 205
 206 int udpv6_offload_exit(void)
 207 {
 208         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 209 }