LXR linux/net/ipv4/udp

   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
  14static 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));
 147out:
 148        return segs;
 149}
 150
 151struct 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
 183out_unlock:
 184        rcu_read_unlock();
 185
 186        return segs;
 187}
 188EXPORT_SYMBOL(skb_udp_tunnel_segment);
 189
 190static 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
 217static 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
 248static 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
 263struct 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}
 365EXPORT_SYMBOL_GPL(__udp_gso_segment);
 366
 367static 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);
 423out:
 424        return segs;
 425}
 426
 427#define UDP_GRO_CNT_MAX 64
 428static 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
 509struct 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
 565out:
 566        skb_gro_flush_final(skb, pp, flush);
 567        return pp;
 568}
 569EXPORT_SYMBOL(udp_gro_receive);
 570
 571static 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
 581INDIRECT_CALLABLE_SCOPE
 582struct 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);
 601skip:
 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
 612flush:
 613        NAPI_GRO_CB(skb)->flush = 1;
 614        return NULL;
 615}
 616
 617static 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
 634int 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}
 672EXPORT_SYMBOL(udp_gro_complete);
 673
 674INDIRECT_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
 704static 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
 712int __init udpv4_offload_init(void)
 713{
 714        return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 715}
 716