net/ipv4/udp_offload.c

   1 /*
   2  *      IPV4 GSO/GRO offload support
   3  *      Linux INET 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  *      UDPv4 GSO support
  11  */
  12
  13 #include <linux/skbuff.h>
  14 #include <net/udp.h>
  15 #include <net/protocol.h>
  16
  17 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
  18         netdev_features_t features,
  19         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
  20                                              netdev_features_t features),
  21         __be16 new_protocol, bool is_ipv6)
  22 {
  23         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
  24         bool remcsum, need_csum, offload_csum, ufo;
  25         struct sk_buff *segs = ERR_PTR(-EINVAL);
  26         struct udphdr *uh = udp_hdr(skb);
  27         u16 mac_offset = skb->mac_header;
  28         __be16 protocol = skb->protocol;
  29         u16 mac_len = skb->mac_len;
  30         int udp_offset, outer_hlen;
  31         __wsum partial;
  32
  33         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
  34                 goto out;
  35
  36         /* Adjust partial header checksum to negate old length.
  37          * We cannot rely on the value contained in uh->len as it is
  38          * possible that the actual value exceeds the boundaries of the
  39          * 16 bit length field due to the header being added outside of an
  40          * IP or IPv6 frame that was already limited to 64K - 1.
  41          */
  42         partial = csum_sub(csum_unfold(uh->check),
  43                            (__force __wsum)htonl(skb->len));
  44
  45         /* setup inner skb. */
  46         skb->encapsulation = 0;
  47         SKB_GSO_CB(skb)->encap_level = 0;
  48         __skb_pull(skb, tnl_hlen);
  49         skb_reset_mac_header(skb);
  50         skb_set_network_header(skb, skb_inner_network_offset(skb));
  51         skb->mac_len = skb_inner_network_offset(skb);
  52         skb->protocol = new_protocol;
  53
  54         need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
  55         skb->encap_hdr_csum = need_csum;
  56
  57         remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
  58         skb->remcsum_offload = remcsum;
  59
  60         ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
  61
  62         /* Try to offload checksum if possible */
  63         offload_csum = !!(need_csum &&
  64                           (skb->dev->features &
  65                            (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
  66                                       (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
  67
  68         features &= skb->dev->hw_enc_features;
  69
  70         /* The only checksum offload we care about from here on out is the
  71          * outer one so strip the existing checksum feature flags and
  72          * instead set the flag based on our outer checksum offload value.
  73          */
  74         if (remcsum || ufo) {
  75                 features &= ~NETIF_F_CSUM_MASK;
  76                 if (!need_csum || offload_csum)
  77                         features |= NETIF_F_HW_CSUM;
  78         }
  79
  80         /* segment inner packet. */
  81         segs = gso_inner_segment(skb, features);
  82         if (IS_ERR_OR_NULL(segs)) {
  83                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
  84                                      mac_len);
  85                 goto out;
  86         }
  87
  88         outer_hlen = skb_tnl_header_len(skb);
  89         udp_offset = outer_hlen - tnl_hlen;
  90         skb = segs;
  91         do {
  92                 __be16 len;
  93
  94                 if (remcsum)
  95                         skb->ip_summed = CHECKSUM_NONE;
  96
  97                 /* Set up inner headers if we are offloading inner checksum */
  98                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
  99                         skb_reset_inner_headers(skb);
 100                         skb->encapsulation = 1;
 101                 }
 102
 103                 skb->mac_len = mac_len;
 104                 skb->protocol = protocol;
 105
 106                 __skb_push(skb, outer_hlen);
 107                 skb_reset_mac_header(skb);
 108                 skb_set_network_header(skb, mac_len);
 109                 skb_set_transport_header(skb, udp_offset);
 110                 len = htons(skb->len - udp_offset);
 111                 uh = udp_hdr(skb);
 112                 uh->len = len;
 113
 114                 if (!need_csum)
 115                         continue;
 116
 117                 uh->check = ~csum_fold(csum_add(partial, (__force __wsum)len));
 118
 119                 if (skb->encapsulation || !offload_csum) {
 120                         uh->check = gso_make_checksum(skb, ~uh->check);
 121                         if (uh->check == 0)
 122                                 uh->check = CSUM_MANGLED_0;
 123                 } else {
 124                         skb->ip_summed = CHECKSUM_PARTIAL;
 125                         skb->csum_start = skb_transport_header(skb) - skb->head;
 126                         skb->csum_offset = offsetof(struct udphdr, check);
 127                 }
 128         } while ((skb = skb->next));
 129 out:
 130         return segs;
 131 }
 132
 133 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 134                                        netdev_features_t features,
 135                                        bool is_ipv6)
 136 {
 137         __be16 protocol = skb->protocol;
 138         const struct net_offload **offloads;
 139         const struct net_offload *ops;
 140         struct sk_buff *segs = ERR_PTR(-EINVAL);
 141         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 142                                              netdev_features_t features);
 143
 144         rcu_read_lock();
 145
 146         switch (skb->inner_protocol_type) {
 147         case ENCAP_TYPE_ETHER:
 148                 protocol = skb->inner_protocol;
 149                 gso_inner_segment = skb_mac_gso_segment;
 150                 break;
 151         case ENCAP_TYPE_IPPROTO:
 152                 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 153                 ops = rcu_dereference(offloads[skb->inner_ipproto]);
 154                 if (!ops || !ops->callbacks.gso_segment)
 155                         goto out_unlock;
 156                 gso_inner_segment = ops->callbacks.gso_segment;
 157                 break;
 158         default:
 159                 goto out_unlock;
 160         }
 161
 162         segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 163                                         protocol, is_ipv6);
 164
 165 out_unlock:
 166         rcu_read_unlock();
 167
 168         return segs;
 169 }
 170 EXPORT_SYMBOL(skb_udp_tunnel_segment);
 171
 172 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 173                                          netdev_features_t features)
 174 {
 175         struct sk_buff *segs = ERR_PTR(-EINVAL);
 176         unsigned int mss;
 177         __wsum csum;
 178         struct udphdr *uh;
 179         struct iphdr *iph;
 180
 181         if (skb->encapsulation &&
 182             (skb_shinfo(skb)->gso_type &
 183              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 184                 segs = skb_udp_tunnel_segment(skb, features, false);
 185                 goto out;
 186         }
 187
 188         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 189                 goto out;
 190
 191         mss = skb_shinfo(skb)->gso_size;
 192         if (unlikely(skb->len <= mss))
 193                 goto out;
 194
 195         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 196                 /* Packet is from an untrusted source, reset gso_segs. */
 197                 int type = skb_shinfo(skb)->gso_type;
 198
 199                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
 200                                       SKB_GSO_UDP_TUNNEL |
 201                                       SKB_GSO_UDP_TUNNEL_CSUM |
 202                                       SKB_GSO_TUNNEL_REMCSUM |
 203                                       SKB_GSO_IPIP |
 204                                       SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
 205                              !(type & (SKB_GSO_UDP))))
 206                         goto out;
 207
 208                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 209
 210                 segs = NULL;
 211                 goto out;
 212         }
 213
 214         /* Do software UFO. Complete and fill in the UDP checksum as
 215          * HW cannot do checksum of UDP packets sent as multiple
 216          * IP fragments.
 217          */
 218
 219         uh = udp_hdr(skb);
 220         iph = ip_hdr(skb);
 221
 222         uh->check = 0;
 223         csum = skb_checksum(skb, 0, skb->len, 0);
 224         uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 225         if (uh->check == 0)
 226                 uh->check = CSUM_MANGLED_0;
 227
 228         skb->ip_summed = CHECKSUM_NONE;
 229
 230         /* If there is no outer header we can fake a checksum offload
 231          * due to the fact that we have already done the checksum in
 232          * software prior to segmenting the frame.
 233          */
 234         if (!skb->encap_hdr_csum)
 235                 features |= NETIF_F_HW_CSUM;
 236
 237         /* Fragment the skb. IP headers of the fragments are updated in
 238          * inet_gso_segment()
 239          */
 240         segs = skb_segment(skb, features);
 241 out:
 242         return segs;
 243 }
 244
 245 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 246                                  struct udphdr *uh, udp_lookup_t lookup)
 247 {
 248         struct sk_buff *p, **pp = NULL;
 249         struct udphdr *uh2;
 250         unsigned int off = skb_gro_offset(skb);
 251         int flush = 1;
 252         struct sock *sk;
 253
 254         if (NAPI_GRO_CB(skb)->encap_mark ||
 255             (skb->ip_summed != CHECKSUM_PARTIAL &&
 256              NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 257              !NAPI_GRO_CB(skb)->csum_valid))
 258                 goto out;
 259
 260         /* mark that this skb passed once through the tunnel gro layer */
 261         NAPI_GRO_CB(skb)->encap_mark = 1;
 262
 263         rcu_read_lock();
 264         sk = (*lookup)(skb, uh->source, uh->dest);
 265
 266         if (sk && udp_sk(sk)->gro_receive)
 267                 goto unflush;
 268         goto out_unlock;
 269
 270 unflush:
 271         flush = 0;
 272
 273         for (p = *head; p; p = p->next) {
 274                 if (!NAPI_GRO_CB(p)->same_flow)
 275                         continue;
 276
 277                 uh2 = (struct udphdr   *)(p->data + off);
 278
 279                 /* Match ports and either checksums are either both zero
 280                  * or nonzero.
 281                  */
 282                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 283                     (!uh->check ^ !uh2->check)) {
 284                         NAPI_GRO_CB(p)->same_flow = 0;
 285                         continue;
 286                 }
 287         }
 288
 289         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 290         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 291         pp = udp_sk(sk)->gro_receive(sk, head, skb);
 292
 293 out_unlock:
 294         rcu_read_unlock();
 295 out:
 296         NAPI_GRO_CB(skb)->flush |= flush;
 297         return pp;
 298 }
 299 EXPORT_SYMBOL(udp_gro_receive);
 300
 301 static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 302                                          struct sk_buff *skb)
 303 {
 304         struct udphdr *uh = udp_gro_udphdr(skb);
 305
 306         if (unlikely(!uh))
 307                 goto flush;
 308
 309         /* Don't bother verifying checksum if we're going to flush anyway. */
 310         if (NAPI_GRO_CB(skb)->flush)
 311                 goto skip;
 312
 313         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 314                                                  inet_gro_compute_pseudo))
 315                 goto flush;
 316         else if (uh->check)
 317                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 318                                              inet_gro_compute_pseudo);
 319 skip:
 320         NAPI_GRO_CB(skb)->is_ipv6 = 0;
 321         return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
 322
 323 flush:
 324         NAPI_GRO_CB(skb)->flush = 1;
 325         return NULL;
 326 }
 327
 328 int udp_gro_complete(struct sk_buff *skb, int nhoff,
 329                      udp_lookup_t lookup)
 330 {
 331         __be16 newlen = htons(skb->len - nhoff);
 332         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 333         int err = -ENOSYS;
 334         struct sock *sk;
 335
 336         uh->len = newlen;
 337
 338         rcu_read_lock();
 339         sk = (*lookup)(skb, uh->source, uh->dest);
 340         if (sk && udp_sk(sk)->gro_complete)
 341                 err = udp_sk(sk)->gro_complete(sk, skb,
 342                                 nhoff + sizeof(struct udphdr));
 343         rcu_read_unlock();
 344
 345         if (skb->remcsum_offload)
 346                 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 347
 348         skb->encapsulation = 1;
 349         skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
 350
 351         return err;
 352 }
 353 EXPORT_SYMBOL(udp_gro_complete);
 354
 355 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 356 {
 357         const struct iphdr *iph = ip_hdr(skb);
 358         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 359
 360         if (uh->check) {
 361                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 362                 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 363                                           iph->daddr, 0);
 364         } else {
 365                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 366         }
 367
 368         return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 369 }
 370
 371 static const struct net_offload udpv4_offload = {
 372         .callbacks = {
 373                 .gso_segment = udp4_ufo_fragment,
 374                 .gro_receive  = udp4_gro_receive,
 375                 .gro_complete = udp4_gro_complete,
 376         },
 377 };
 378
 379 int __init udpv4_offload_init(void)
 380 {
 381         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 382 }