net/ipv4/udp_offload.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      IPV4 GSO/GRO offload support
   4  *      Linux INET implementation
   5  *
   6  *      UDPv4 GSO support
   7  */
   8
   9 #include <linux/skbuff.h>
  10 #include <net/udp.h>
  11 #include <net/protocol.h>
  12 #include <net/inet_common.h>
  13
  14 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
  15         netdev_features_t features,
  16         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
  17                                              netdev_features_t features),
  18         __be16 new_protocol, bool is_ipv6)
  19 {
  20         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
  21         bool remcsum, need_csum, offload_csum, gso_partial;
  22         struct sk_buff *segs = ERR_PTR(-EINVAL);
  23         struct udphdr *uh = udp_hdr(skb);
  24         u16 mac_offset = skb->mac_header;
  25         __be16 protocol = skb->protocol;
  26         u16 mac_len = skb->mac_len;
  27         int udp_offset, outer_hlen;
  28         __wsum partial;
  29         bool need_ipsec;
  30
  31         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
  32                 goto out;
  33
  34         /* Adjust partial header checksum to negate old length.
  35          * We cannot rely on the value contained in uh->len as it is
  36          * possible that the actual value exceeds the boundaries of the
  37          * 16 bit length field due to the header being added outside of an
  38          * IP or IPv6 frame that was already limited to 64K - 1.
  39          */
  40         if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
  41                 partial = (__force __wsum)uh->len;
  42         else
  43                 partial = (__force __wsum)htonl(skb->len);
  44         partial = csum_sub(csum_unfold(uh->check), partial);
  45
  46         /* setup inner skb. */
  47         skb->encapsulation = 0;
  48         SKB_GSO_CB(skb)->encap_level = 0;
  49         __skb_pull(skb, tnl_hlen);
  50         skb_reset_mac_header(skb);
  51         skb_set_network_header(skb, skb_inner_network_offset(skb));
  52         skb_set_transport_header(skb, skb_inner_transport_offset(skb));
  53         skb->mac_len = skb_inner_network_offset(skb);
  54         skb->protocol = new_protocol;
  55
  56         need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
  57         skb->encap_hdr_csum = need_csum;
  58
  59         remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
  60         skb->remcsum_offload = remcsum;
  61
  62         need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
  63         /* Try to offload checksum if possible */
  64         offload_csum = !!(need_csum &&
  65                           !need_ipsec &&
  66                           (skb->dev->features &
  67                            (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
  68                                       (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
  69
  70         features &= skb->dev->hw_enc_features;
  71         if (need_csum)
  72                 features &= ~NETIF_F_SCTP_CRC;
  73
  74         /* The only checksum offload we care about from here on out is the
  75          * outer one so strip the existing checksum feature flags and
  76          * instead set the flag based on our outer checksum offload value.
  77          */
  78         if (remcsum) {
  79                 features &= ~NETIF_F_CSUM_MASK;
  80                 if (!need_csum || offload_csum)
  81                         features |= NETIF_F_HW_CSUM;
  82         }
  83
  84         /* segment inner packet. */
  85         segs = gso_inner_segment(skb, features);
  86         if (IS_ERR_OR_NULL(segs)) {
  87                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
  88                                      mac_len);
  89                 goto out;
  90         }
  91
  92         gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
  93
  94         outer_hlen = skb_tnl_header_len(skb);
  95         udp_offset = outer_hlen - tnl_hlen;
  96         skb = segs;
  97         do {
  98                 unsigned int len;
  99
 100                 if (remcsum)
 101                         skb->ip_summed = CHECKSUM_NONE;
 102
 103                 /* Set up inner headers if we are offloading inner checksum */
 104                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
 105                         skb_reset_inner_headers(skb);
 106                         skb->encapsulation = 1;
 107                 }
 108
 109                 skb->mac_len = mac_len;
 110                 skb->protocol = protocol;
 111
 112                 __skb_push(skb, outer_hlen);
 113                 skb_reset_mac_header(skb);
 114                 skb_set_network_header(skb, mac_len);
 115                 skb_set_transport_header(skb, udp_offset);
 116                 len = skb->len - udp_offset;
 117                 uh = udp_hdr(skb);
 118
 119                 /* If we are only performing partial GSO the inner header
 120                  * will be using a length value equal to only one MSS sized
 121                  * segment instead of the entire frame.
 122                  */
 123                 if (gso_partial && skb_is_gso(skb)) {
 124                         uh->len = htons(skb_shinfo(skb)->gso_size +
 125                                         SKB_GSO_CB(skb)->data_offset +
 126                                         skb->head - (unsigned char *)uh);
 127                 } else {
 128                         uh->len = htons(len);
 129                 }
 130
 131                 if (!need_csum)
 132                         continue;
 133
 134                 uh->check = ~csum_fold(csum_add(partial,
 135                                        (__force __wsum)htonl(len)));
 136
 137                 if (skb->encapsulation || !offload_csum) {
 138                         uh->check = gso_make_checksum(skb, ~uh->check);
 139                         if (uh->check == 0)
 140                                 uh->check = CSUM_MANGLED_0;
 141                 } else {
 142                         skb->ip_summed = CHECKSUM_PARTIAL;
 143                         skb->csum_start = skb_transport_header(skb) - skb->head;
 144                         skb->csum_offset = offsetof(struct udphdr, check);
 145                 }
 146         } while ((skb = skb->next));
 147 out:
 148         return segs;
 149 }
 150
 151 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 152                                        netdev_features_t features,
 153                                        bool is_ipv6)
 154 {
 155         const struct net_offload __rcu **offloads;
 156         __be16 protocol = skb->protocol;
 157         const struct net_offload *ops;
 158         struct sk_buff *segs = ERR_PTR(-EINVAL);
 159         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 160                                              netdev_features_t features);
 161
 162         rcu_read_lock();
 163
 164         switch (skb->inner_protocol_type) {
 165         case ENCAP_TYPE_ETHER:
 166                 protocol = skb->inner_protocol;
 167                 gso_inner_segment = skb_mac_gso_segment;
 168                 break;
 169         case ENCAP_TYPE_IPPROTO:
 170                 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 171                 ops = rcu_dereference(offloads[skb->inner_ipproto]);
 172                 if (!ops || !ops->callbacks.gso_segment)
 173                         goto out_unlock;
 174                 gso_inner_segment = ops->callbacks.gso_segment;
 175                 break;
 176         default:
 177                 goto out_unlock;
 178         }
 179
 180         segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 181                                         protocol, is_ipv6);
 182
 183 out_unlock:
 184         rcu_read_unlock();
 185
 186         return segs;
 187 }
 188 EXPORT_SYMBOL(skb_udp_tunnel_segment);
 189
 190 static void __udpv4_gso_segment_csum(struct sk_buff *seg,
 191                                      __be32 *oldip, __be32 *newip,
 192                                      __be16 *oldport, __be16 *newport)
 193 {
 194         struct udphdr *uh;
 195         struct iphdr *iph;
 196
 197         if (*oldip == *newip && *oldport == *newport)
 198                 return;
 199
 200         uh = udp_hdr(seg);
 201         iph = ip_hdr(seg);
 202
 203         if (uh->check) {
 204                 inet_proto_csum_replace4(&uh->check, seg, *oldip, *newip,
 205                                          true);
 206                 inet_proto_csum_replace2(&uh->check, seg, *oldport, *newport,
 207                                          false);
 208                 if (!uh->check)
 209                         uh->check = CSUM_MANGLED_0;
 210         }
 211         *oldport = *newport;
 212
 213         csum_replace4(&iph->check, *oldip, *newip);
 214         *oldip = *newip;
 215 }
 216
 217 static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs)
 218 {
 219         struct sk_buff *seg;
 220         struct udphdr *uh, *uh2;
 221         struct iphdr *iph, *iph2;
 222
 223         seg = segs;
 224         uh = udp_hdr(seg);
 225         iph = ip_hdr(seg);
 226
 227         if ((udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) &&
 228             (udp_hdr(seg)->source == udp_hdr(seg->next)->source) &&
 229             (ip_hdr(seg)->daddr == ip_hdr(seg->next)->daddr) &&
 230             (ip_hdr(seg)->saddr == ip_hdr(seg->next)->saddr))
 231                 return segs;
 232
 233         while ((seg = seg->next)) {
 234                 uh2 = udp_hdr(seg);
 235                 iph2 = ip_hdr(seg);
 236
 237                 __udpv4_gso_segment_csum(seg,
 238                                          &iph2->saddr, &iph->saddr,
 239                                          &uh2->source, &uh->source);
 240                 __udpv4_gso_segment_csum(seg,
 241                                          &iph2->daddr, &iph->daddr,
 242                                          &uh2->dest, &uh->dest);
 243         }
 244
 245         return segs;
 246 }
 247
 248 static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb,
 249                                               netdev_features_t features,
 250                                               bool is_ipv6)
 251 {
 252         unsigned int mss = skb_shinfo(skb)->gso_size;
 253
 254         skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
 255         if (IS_ERR(skb))
 256                 return skb;
 257
 258         udp_hdr(skb)->len = htons(sizeof(struct udphdr) + mss);
 259
 260         return is_ipv6 ? skb : __udpv4_gso_segment_list_csum(skb);
 261 }
 262
 263 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
 264                                   netdev_features_t features, bool is_ipv6)
 265 {
 266         struct sock *sk = gso_skb->sk;
 267         unsigned int sum_truesize = 0;
 268         struct sk_buff *segs, *seg;
 269         struct udphdr *uh;
 270         unsigned int mss;
 271         bool copy_dtor;
 272         __sum16 check;
 273         __be16 newlen;
 274
 275         if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)
 276                 return __udp_gso_segment_list(gso_skb, features, is_ipv6);
 277
 278         mss = skb_shinfo(gso_skb)->gso_size;
 279         if (gso_skb->len <= sizeof(*uh) + mss)
 280                 return ERR_PTR(-EINVAL);
 281
 282         skb_pull(gso_skb, sizeof(*uh));
 283
 284         /* clear destructor to avoid skb_segment assigning it to tail */
 285         copy_dtor = gso_skb->destructor == sock_wfree;
 286         if (copy_dtor)
 287                 gso_skb->destructor = NULL;
 288
 289         segs = skb_segment(gso_skb, features);
 290         if (IS_ERR_OR_NULL(segs)) {
 291                 if (copy_dtor)
 292                         gso_skb->destructor = sock_wfree;
 293                 return segs;
 294         }
 295
 296         /* GSO partial and frag_list segmentation only requires splitting
 297          * the frame into an MSS multiple and possibly a remainder, both
 298          * cases return a GSO skb. So update the mss now.
 299          */
 300         if (skb_is_gso(segs))
 301                 mss *= skb_shinfo(segs)->gso_segs;
 302
 303         seg = segs;
 304         uh = udp_hdr(seg);
 305
 306         /* preserve TX timestamp flags and TS key for first segment */
 307         skb_shinfo(seg)->tskey = skb_shinfo(gso_skb)->tskey;
 308         skb_shinfo(seg)->tx_flags |=
 309                         (skb_shinfo(gso_skb)->tx_flags & SKBTX_ANY_TSTAMP);
 310
 311         /* compute checksum adjustment based on old length versus new */
 312         newlen = htons(sizeof(*uh) + mss);
 313         check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
 314
 315         for (;;) {
 316                 if (copy_dtor) {
 317                         seg->destructor = sock_wfree;
 318                         seg->sk = sk;
 319                         sum_truesize += seg->truesize;
 320                 }
 321
 322                 if (!seg->next)
 323                         break;
 324
 325                 uh->len = newlen;
 326                 uh->check = check;
 327
 328                 if (seg->ip_summed == CHECKSUM_PARTIAL)
 329                         gso_reset_checksum(seg, ~check);
 330                 else
 331                         uh->check = gso_make_checksum(seg, ~check) ? :
 332                                     CSUM_MANGLED_0;
 333
 334                 seg = seg->next;
 335                 uh = udp_hdr(seg);
 336         }
 337
 338         /* last packet can be partial gso_size, account for that in checksum */
 339         newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) +
 340                        seg->data_len);
 341         check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
 342
 343         uh->len = newlen;
 344         uh->check = check;
 345
 346         if (seg->ip_summed == CHECKSUM_PARTIAL)
 347                 gso_reset_checksum(seg, ~check);
 348         else
 349                 uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0;
 350
 351         /* update refcount for the packet */
 352         if (copy_dtor) {
 353                 int delta = sum_truesize - gso_skb->truesize;
 354
 355                 /* In some pathological cases, delta can be negative.
 356                  * We need to either use refcount_add() or refcount_sub_and_test()
 357                  */
 358                 if (likely(delta >= 0))
 359                         refcount_add(delta, &sk->sk_wmem_alloc);
 360                 else
 361                         WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
 362         }
 363         return segs;
 364 }
 365 EXPORT_SYMBOL_GPL(__udp_gso_segment);
 366
 367 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 368                                          netdev_features_t features)
 369 {
 370         struct sk_buff *segs = ERR_PTR(-EINVAL);
 371         unsigned int mss;
 372         __wsum csum;
 373         struct udphdr *uh;
 374         struct iphdr *iph;
 375
 376         if (skb->encapsulation &&
 377             (skb_shinfo(skb)->gso_type &
 378              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 379                 segs = skb_udp_tunnel_segment(skb, features, false);
 380                 goto out;
 381         }
 382
 383         if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
 384                 goto out;
 385
 386         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 387                 goto out;
 388
 389         if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
 390                 return __udp_gso_segment(skb, features, false);
 391
 392         mss = skb_shinfo(skb)->gso_size;
 393         if (unlikely(skb->len <= mss))
 394                 goto out;
 395
 396         /* Do software UFO. Complete and fill in the UDP checksum as
 397          * HW cannot do checksum of UDP packets sent as multiple
 398          * IP fragments.
 399          */
 400
 401         uh = udp_hdr(skb);
 402         iph = ip_hdr(skb);
 403
 404         uh->check = 0;
 405         csum = skb_checksum(skb, 0, skb->len, 0);
 406         uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 407         if (uh->check == 0)
 408                 uh->check = CSUM_MANGLED_0;
 409
 410         skb->ip_summed = CHECKSUM_UNNECESSARY;
 411
 412         /* If there is no outer header we can fake a checksum offload
 413          * due to the fact that we have already done the checksum in
 414          * software prior to segmenting the frame.
 415          */
 416         if (!skb->encap_hdr_csum)
 417                 features |= NETIF_F_HW_CSUM;
 418
 419         /* Fragment the skb. IP headers of the fragments are updated in
 420          * inet_gso_segment()
 421          */
 422         segs = skb_segment(skb, features);
 423 out:
 424         return segs;
 425 }
 426
 427 #define UDP_GRO_CNT_MAX 64
 428 static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
 429                                                struct sk_buff *skb)
 430 {
 431         struct udphdr *uh = udp_gro_udphdr(skb);
 432         struct sk_buff *pp = NULL;
 433         struct udphdr *uh2;
 434         struct sk_buff *p;
 435         unsigned int ulen;
 436         int ret = 0;
 437
 438         /* requires non zero csum, for symmetry with GSO */
 439         if (!uh->check) {
 440                 NAPI_GRO_CB(skb)->flush = 1;
 441                 return NULL;
 442         }
 443
 444         /* Do not deal with padded or malicious packets, sorry ! */
 445         ulen = ntohs(uh->len);
 446         if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) {
 447                 NAPI_GRO_CB(skb)->flush = 1;
 448                 return NULL;
 449         }
 450         /* pull encapsulating udp header */
 451         skb_gro_pull(skb, sizeof(struct udphdr));
 452
 453         list_for_each_entry(p, head, list) {
 454                 if (!NAPI_GRO_CB(p)->same_flow)
 455                         continue;
 456
 457                 uh2 = udp_hdr(p);
 458
 459                 /* Match ports only, as csum is always non zero */
 460                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
 461                         NAPI_GRO_CB(p)->same_flow = 0;
 462                         continue;
 463                 }
 464
 465                 if (NAPI_GRO_CB(skb)->is_flist != NAPI_GRO_CB(p)->is_flist) {
 466                         NAPI_GRO_CB(skb)->flush = 1;
 467                         return p;
 468                 }
 469
 470                 /* Terminate the flow on len mismatch or if it grow "too much".
 471                  * Under small packet flood GRO count could elsewhere grow a lot
 472                  * leading to excessive truesize values.
 473                  * On len mismatch merge the first packet shorter than gso_size,
 474                  * otherwise complete the GRO packet.
 475                  */
 476                 if (ulen > ntohs(uh2->len)) {
 477                         pp = p;
 478                 } else {
 479                         if (NAPI_GRO_CB(skb)->is_flist) {
 480                                 if (!pskb_may_pull(skb, skb_gro_offset(skb))) {
 481                                         NAPI_GRO_CB(skb)->flush = 1;
 482                                         return NULL;
 483                                 }
 484                                 if ((skb->ip_summed != p->ip_summed) ||
 485                                     (skb->csum_level != p->csum_level)) {
 486                                         NAPI_GRO_CB(skb)->flush = 1;
 487                                         return NULL;
 488                                 }
 489                                 ret = skb_gro_receive_list(p, skb);
 490                         } else {
 491                                 skb_gro_postpull_rcsum(skb, uh,
 492                                                        sizeof(struct udphdr));
 493
 494                                 ret = skb_gro_receive(p, skb);
 495                         }
 496                 }
 497
 498                 if (ret || ulen != ntohs(uh2->len) ||
 499                     NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
 500                         pp = p;
 501
 502                 return pp;
 503         }
 504
 505         /* mismatch, but we never need to flush */
 506         return NULL;
 507 }
 508
 509 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 510                                 struct udphdr *uh, struct sock *sk)
 511 {
 512         struct sk_buff *pp = NULL;
 513         struct sk_buff *p;
 514         struct udphdr *uh2;
 515         unsigned int off = skb_gro_offset(skb);
 516         int flush = 1;
 517
 518         /* we can do L4 aggregation only if the packet can't land in a tunnel
 519          * otherwise we could corrupt the inner stream
 520          */
 521         NAPI_GRO_CB(skb)->is_flist = 0;
 522         if (!sk || !udp_sk(sk)->gro_receive) {
 523                 if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
 524                         NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled : 1;
 525
 526                 if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) ||
 527                     (sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist)
 528                         return call_gro_receive(udp_gro_receive_segment, head, skb);
 529
 530                 /* no GRO, be sure flush the current packet */
 531                 goto out;
 532         }
 533
 534         if (NAPI_GRO_CB(skb)->encap_mark ||
 535             (uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
 536              NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 537              !NAPI_GRO_CB(skb)->csum_valid))
 538                 goto out;
 539
 540         /* mark that this skb passed once through the tunnel gro layer */
 541         NAPI_GRO_CB(skb)->encap_mark = 1;
 542
 543         flush = 0;
 544
 545         list_for_each_entry(p, head, list) {
 546                 if (!NAPI_GRO_CB(p)->same_flow)
 547                         continue;
 548
 549                 uh2 = (struct udphdr   *)(p->data + off);
 550
 551                 /* Match ports and either checksums are either both zero
 552                  * or nonzero.
 553                  */
 554                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 555                     (!uh->check ^ !uh2->check)) {
 556                         NAPI_GRO_CB(p)->same_flow = 0;
 557                         continue;
 558                 }
 559         }
 560
 561         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 562         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 563         pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
 564
 565 out:
 566         skb_gro_flush_final(skb, pp, flush);
 567         return pp;
 568 }
 569 EXPORT_SYMBOL(udp_gro_receive);
 570
 571 static struct sock *udp4_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
 572                                         __be16 dport)
 573 {
 574         const struct iphdr *iph = skb_gro_network_header(skb);
 575
 576         return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
 577                                  iph->daddr, dport, inet_iif(skb),
 578                                  inet_sdif(skb), &udp_table, NULL);
 579 }
 580
 581 INDIRECT_CALLABLE_SCOPE
 582 struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 583 {
 584         struct udphdr *uh = udp_gro_udphdr(skb);
 585         struct sock *sk = NULL;
 586         struct sk_buff *pp;
 587
 588         if (unlikely(!uh))
 589                 goto flush;
 590
 591         /* Don't bother verifying checksum if we're going to flush anyway. */
 592         if (NAPI_GRO_CB(skb)->flush)
 593                 goto skip;
 594
 595         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 596                                                  inet_gro_compute_pseudo))
 597                 goto flush;
 598         else if (uh->check)
 599                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
 600                                              inet_gro_compute_pseudo);
 601 skip:
 602         NAPI_GRO_CB(skb)->is_ipv6 = 0;
 603         rcu_read_lock();
 604
 605         if (static_branch_unlikely(&udp_encap_needed_key))
 606                 sk = udp4_gro_lookup_skb(skb, uh->source, uh->dest);
 607
 608         pp = udp_gro_receive(head, skb, uh, sk);
 609         rcu_read_unlock();
 610         return pp;
 611
 612 flush:
 613         NAPI_GRO_CB(skb)->flush = 1;
 614         return NULL;
 615 }
 616
 617 static int udp_gro_complete_segment(struct sk_buff *skb)
 618 {
 619         struct udphdr *uh = udp_hdr(skb);
 620
 621         skb->csum_start = (unsigned char *)uh - skb->head;
 622         skb->csum_offset = offsetof(struct udphdr, check);
 623         skb->ip_summed = CHECKSUM_PARTIAL;
 624
 625         skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
 626         skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
 627
 628         if (skb->encapsulation)
 629                 skb->inner_transport_header = skb->transport_header;
 630
 631         return 0;
 632 }
 633
 634 int udp_gro_complete(struct sk_buff *skb, int nhoff,
 635                      udp_lookup_t lookup)
 636 {
 637         __be16 newlen = htons(skb->len - nhoff);
 638         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 639         struct sock *sk;
 640         int err;
 641
 642         uh->len = newlen;
 643
 644         rcu_read_lock();
 645         sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
 646                                 udp4_lib_lookup_skb, skb, uh->source, uh->dest);
 647         if (sk && udp_sk(sk)->gro_complete) {
 648                 skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
 649                                         : SKB_GSO_UDP_TUNNEL;
 650
 651                 /* clear the encap mark, so that inner frag_list gro_complete
 652                  * can take place
 653                  */
 654                 NAPI_GRO_CB(skb)->encap_mark = 0;
 655
 656                 /* Set encapsulation before calling into inner gro_complete()
 657                  * functions to make them set up the inner offsets.
 658                  */
 659                 skb->encapsulation = 1;
 660                 err = udp_sk(sk)->gro_complete(sk, skb,
 661                                 nhoff + sizeof(struct udphdr));
 662         } else {
 663                 err = udp_gro_complete_segment(skb);
 664         }
 665         rcu_read_unlock();
 666
 667         if (skb->remcsum_offload)
 668                 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 669
 670         return err;
 671 }
 672 EXPORT_SYMBOL(udp_gro_complete);
 673
 674 INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 675 {
 676         const struct iphdr *iph = ip_hdr(skb);
 677         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 678
 679         /* do fraglist only if there is no outer UDP encap (or we already processed it) */
 680         if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
 681                 uh->len = htons(skb->len - nhoff);
 682
 683                 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
 684                 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
 685
 686                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 687                         if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
 688                                 skb->csum_level++;
 689                 } else {
 690                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 691                         skb->csum_level = 0;
 692                 }
 693
 694                 return 0;
 695         }
 696
 697         if (uh->check)
 698                 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 699                                           iph->daddr, 0);
 700
 701         return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 702 }
 703
 704 static const struct net_offload udpv4_offload = {
 705         .callbacks = {
 706                 .gso_segment = udp4_ufo_fragment,
 707                 .gro_receive  = udp4_gro_receive,
 708                 .gro_complete = udp4_gro_complete,
 709         },
 710 };
 711
 712 int __init udpv4_offload_init(void)
 713 {
 714         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 715 }