LXR linux/net/ipv4/udp

   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
  17static 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        if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
  43                partial = (__force __wsum)uh->len;
  44        else
  45                partial = (__force __wsum)htonl(skb->len);
  46        partial = csum_sub(csum_unfold(uh->check), partial);
  47
  48        /* setup inner skb. */
  49        skb->encapsulation = 0;
  50        SKB_GSO_CB(skb)->encap_level = 0;
  51        __skb_pull(skb, tnl_hlen);
  52        skb_reset_mac_header(skb);
  53        skb_set_network_header(skb, skb_inner_network_offset(skb));
  54        skb->mac_len = skb_inner_network_offset(skb);
  55        skb->protocol = new_protocol;
  56
  57        need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
  58        skb->encap_hdr_csum = need_csum;
  59
  60        remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
  61        skb->remcsum_offload = remcsum;
  62
  63        ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
  64
  65        /* Try to offload checksum if possible */
  66        offload_csum = !!(need_csum &&
  67                          (skb->dev->features &
  68                           (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
  69                                      (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
  70
  71        features &= skb->dev->hw_enc_features;
  72
  73        /* The only checksum offload we care about from here on out is the
  74         * outer one so strip the existing checksum feature flags and
  75         * instead set the flag based on our outer checksum offload value.
  76         */
  77        if (remcsum || ufo) {
  78                features &= ~NETIF_F_CSUM_MASK;
  79                if (!need_csum || offload_csum)
  80                        features |= NETIF_F_HW_CSUM;
  81        }
  82
  83        /* segment inner packet. */
  84        segs = gso_inner_segment(skb, features);
  85        if (IS_ERR_OR_NULL(segs)) {
  86                skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
  87                                     mac_len);
  88                goto out;
  89        }
  90
  91        outer_hlen = skb_tnl_header_len(skb);
  92        udp_offset = outer_hlen - tnl_hlen;
  93        skb = segs;
  94        do {
  95                unsigned int len;
  96
  97                if (remcsum)
  98                        skb->ip_summed = CHECKSUM_NONE;
  99
 100                /* Set up inner headers if we are offloading inner checksum */
 101                if (skb->ip_summed == CHECKSUM_PARTIAL) {
 102                        skb_reset_inner_headers(skb);
 103                        skb->encapsulation = 1;
 104                }
 105
 106                skb->mac_len = mac_len;
 107                skb->protocol = protocol;
 108
 109                __skb_push(skb, outer_hlen);
 110                skb_reset_mac_header(skb);
 111                skb_set_network_header(skb, mac_len);
 112                skb_set_transport_header(skb, udp_offset);
 113                len = skb->len - udp_offset;
 114                uh = udp_hdr(skb);
 115
 116                /* If we are only performing partial GSO the inner header
 117                 * will be using a length value equal to only one MSS sized
 118                 * segment instead of the entire frame.
 119                 */
 120                if (skb_is_gso(skb)) {
 121                        uh->len = htons(skb_shinfo(skb)->gso_size +
 122                                        SKB_GSO_CB(skb)->data_offset +
 123                                        skb->head - (unsigned char *)uh);
 124                } else {
 125                        uh->len = htons(len);
 126                }
 127
 128                if (!need_csum)
 129                        continue;
 130
 131                uh->check = ~csum_fold(csum_add(partial,
 132                                       (__force __wsum)htonl(len)));
 133
 134                if (skb->encapsulation || !offload_csum) {
 135                        uh->check = gso_make_checksum(skb, ~uh->check);
 136                        if (uh->check == 0)
 137                                uh->check = CSUM_MANGLED_0;
 138                } else {
 139                        skb->ip_summed = CHECKSUM_PARTIAL;
 140                        skb->csum_start = skb_transport_header(skb) - skb->head;
 141                        skb->csum_offset = offsetof(struct udphdr, check);
 142                }
 143        } while ((skb = skb->next));
 144out:
 145        return segs;
 146}
 147
 148struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 149                                       netdev_features_t features,
 150                                       bool is_ipv6)
 151{
 152        __be16 protocol = skb->protocol;
 153        const struct net_offload **offloads;
 154        const struct net_offload *ops;
 155        struct sk_buff *segs = ERR_PTR(-EINVAL);
 156        struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 157                                             netdev_features_t features);
 158
 159        rcu_read_lock();
 160
 161        switch (skb->inner_protocol_type) {
 162        case ENCAP_TYPE_ETHER:
 163                protocol = skb->inner_protocol;
 164                gso_inner_segment = skb_mac_gso_segment;
 165                break;
 166        case ENCAP_TYPE_IPPROTO:
 167                offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 168                ops = rcu_dereference(offloads[skb->inner_ipproto]);
 169                if (!ops || !ops->callbacks.gso_segment)
 170                        goto out_unlock;
 171                gso_inner_segment = ops->callbacks.gso_segment;
 172                break;
 173        default:
 174                goto out_unlock;
 175        }
 176
 177        segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 178                                        protocol, is_ipv6);
 179
 180out_unlock:
 181        rcu_read_unlock();
 182
 183        return segs;
 184}
 185EXPORT_SYMBOL(skb_udp_tunnel_segment);
 186
 187static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 188                                         netdev_features_t features)
 189{
 190        struct sk_buff *segs = ERR_PTR(-EINVAL);
 191        unsigned int mss;
 192        __wsum csum;
 193        struct udphdr *uh;
 194        struct iphdr *iph;
 195
 196        if (skb->encapsulation &&
 197            (skb_shinfo(skb)->gso_type &
 198             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 199                segs = skb_udp_tunnel_segment(skb, features, false);
 200                goto out;
 201        }
 202
 203        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 204                goto out;
 205
 206        mss = skb_shinfo(skb)->gso_size;
 207        if (unlikely(skb->len <= mss))
 208                goto out;
 209
 210        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 211                /* Packet is from an untrusted source, reset gso_segs. */
 212
 213                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 214
 215                segs = NULL;
 216                goto out;
 217        }
 218
 219        /* Do software UFO. Complete and fill in the UDP checksum as
 220         * HW cannot do checksum of UDP packets sent as multiple
 221         * IP fragments.
 222         */
 223
 224        uh = udp_hdr(skb);
 225        iph = ip_hdr(skb);
 226
 227        uh->check = 0;
 228        csum = skb_checksum(skb, 0, skb->len, 0);
 229        uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 230        if (uh->check == 0)
 231                uh->check = CSUM_MANGLED_0;
 232
 233        skb->ip_summed = CHECKSUM_NONE;
 234
 235        /* If there is no outer header we can fake a checksum offload
 236         * due to the fact that we have already done the checksum in
 237         * software prior to segmenting the frame.
 238         */
 239        if (!skb->encap_hdr_csum)
 240                features |= NETIF_F_HW_CSUM;
 241
 242        /* Fragment the skb. IP headers of the fragments are updated in
 243         * inet_gso_segment()
 244         */
 245        segs = skb_segment(skb, features);
 246out:
 247        return segs;
 248}
 249
 250struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 251                                 struct udphdr *uh, udp_lookup_t lookup)
 252{
 253        struct sk_buff *p, **pp = NULL;
 254        struct udphdr *uh2;
 255        unsigned int off = skb_gro_offset(skb);
 256        int flush = 1;
 257        struct sock *sk;
 258
 259        if (NAPI_GRO_CB(skb)->encap_mark ||
 260            (skb->ip_summed != CHECKSUM_PARTIAL &&
 261             NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 262             !NAPI_GRO_CB(skb)->csum_valid))
 263                goto out;
 264
 265        /* mark that this skb passed once through the tunnel gro layer */
 266        NAPI_GRO_CB(skb)->encap_mark = 1;
 267
 268        rcu_read_lock();
 269        sk = (*lookup)(skb, uh->source, uh->dest);
 270
 271        if (sk && udp_sk(sk)->gro_receive)
 272                goto unflush;
 273        goto out_unlock;
 274
 275unflush:
 276        flush = 0;
 277
 278        for (p = *head; p; p = p->next) {
 279                if (!NAPI_GRO_CB(p)->same_flow)
 280                        continue;
 281
 282                uh2 = (struct udphdr   *)(p->data + off);
 283
 284                /* Match ports and either checksums are either both zero
 285                 * or nonzero.
 286                 */
 287                if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 288                    (!uh->check ^ !uh2->check)) {
 289                        NAPI_GRO_CB(p)->same_flow = 0;
 290                        continue;
 291                }
 292        }
 293
 294        skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 295        skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 296        pp = udp_sk(sk)->gro_receive(sk, head, skb);
 297
 298out_unlock:
 299        rcu_read_unlock();
 300out:
 301        NAPI_GRO_CB(skb)->flush |= flush;
 302        return pp;
 303}
 304EXPORT_SYMBOL(udp_gro_receive);
 305
 306static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 307                                         struct sk_buff *skb)
 308{
 309        struct udphdr *uh = udp_gro_udphdr(skb);
 310
 311        if (unlikely(!uh))
 312                goto flush;
 313
 314        /* Don't bother verifying checksum if we're going to flush anyway. */
 315        if (NAPI_GRO_CB(skb)->flush)
 316                goto skip;
 317
 318        if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 319                                                 inet_gro_compute_pseudo))
 320                goto flush;
 321        else if (uh->check)
 322                skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 323                                             inet_gro_compute_pseudo);
 324skip:
 325        NAPI_GRO_CB(skb)->is_ipv6 = 0;
 326        return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
 327
 328flush:
 329        NAPI_GRO_CB(skb)->flush = 1;
 330        return NULL;
 331}
 332
 333int udp_gro_complete(struct sk_buff *skb, int nhoff,
 334                     udp_lookup_t lookup)
 335{
 336        __be16 newlen = htons(skb->len - nhoff);
 337        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 338        int err = -ENOSYS;
 339        struct sock *sk;
 340
 341        uh->len = newlen;
 342
 343        /* Set encapsulation before calling into inner gro_complete() functions
 344         * to make them set up the inner offsets.
 345         */
 346        skb->encapsulation = 1;
 347
 348        rcu_read_lock();
 349        sk = (*lookup)(skb, uh->source, uh->dest);
 350        if (sk && udp_sk(sk)->gro_complete)
 351                err = udp_sk(sk)->gro_complete(sk, skb,
 352                                nhoff + sizeof(struct udphdr));
 353        rcu_read_unlock();
 354
 355        if (skb->remcsum_offload)
 356                skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 357
 358        return err;
 359}
 360EXPORT_SYMBOL(udp_gro_complete);
 361
 362static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 363{
 364        const struct iphdr *iph = ip_hdr(skb);
 365        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 366
 367        if (uh->check) {
 368                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 369                uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 370                                          iph->daddr, 0);
 371        } else {
 372                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 373        }
 374
 375        return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 376}
 377
 378static const struct net_offload udpv4_offload = {
 379        .callbacks = {
 380                .gso_segment = udp4_ufo_fragment,
 381                .gro_receive  = udp4_gro_receive,
 382                .gro_complete = udp4_gro_complete,
 383        },
 384};
 385
 386int __init udpv4_offload_init(void)
 387{
 388        return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 389}
 390