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, gso_partial;
  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        gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
  92
  93        outer_hlen = skb_tnl_header_len(skb);
  94        udp_offset = outer_hlen - tnl_hlen;
  95        skb = segs;
  96        do {
  97                unsigned int len;
  98
  99                if (remcsum)
 100                        skb->ip_summed = CHECKSUM_NONE;
 101
 102                /* Set up inner headers if we are offloading inner checksum */
 103                if (skb->ip_summed == CHECKSUM_PARTIAL) {
 104                        skb_reset_inner_headers(skb);
 105                        skb->encapsulation = 1;
 106                }
 107
 108                skb->mac_len = mac_len;
 109                skb->protocol = protocol;
 110
 111                __skb_push(skb, outer_hlen);
 112                skb_reset_mac_header(skb);
 113                skb_set_network_header(skb, mac_len);
 114                skb_set_transport_header(skb, udp_offset);
 115                len = skb->len - udp_offset;
 116                uh = udp_hdr(skb);
 117
 118                /* If we are only performing partial GSO the inner header
 119                 * will be using a length value equal to only one MSS sized
 120                 * segment instead of the entire frame.
 121                 */
 122                if (gso_partial) {
 123                        uh->len = htons(skb_shinfo(skb)->gso_size +
 124                                        SKB_GSO_CB(skb)->data_offset +
 125                                        skb->head - (unsigned char *)uh);
 126                } else {
 127                        uh->len = htons(len);
 128                }
 129
 130                if (!need_csum)
 131                        continue;
 132
 133                uh->check = ~csum_fold(csum_add(partial,
 134                                       (__force __wsum)htonl(len)));
 135
 136                if (skb->encapsulation || !offload_csum) {
 137                        uh->check = gso_make_checksum(skb, ~uh->check);
 138                        if (uh->check == 0)
 139                                uh->check = CSUM_MANGLED_0;
 140                } else {
 141                        skb->ip_summed = CHECKSUM_PARTIAL;
 142                        skb->csum_start = skb_transport_header(skb) - skb->head;
 143                        skb->csum_offset = offsetof(struct udphdr, check);
 144                }
 145        } while ((skb = skb->next));
 146out:
 147        return segs;
 148}
 149
 150struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 151                                       netdev_features_t features,
 152                                       bool is_ipv6)
 153{
 154        __be16 protocol = skb->protocol;
 155        const struct net_offload **offloads;
 156        const struct net_offload *ops;
 157        struct sk_buff *segs = ERR_PTR(-EINVAL);
 158        struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 159                                             netdev_features_t features);
 160
 161        rcu_read_lock();
 162
 163        switch (skb->inner_protocol_type) {
 164        case ENCAP_TYPE_ETHER:
 165                protocol = skb->inner_protocol;
 166                gso_inner_segment = skb_mac_gso_segment;
 167                break;
 168        case ENCAP_TYPE_IPPROTO:
 169                offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 170                ops = rcu_dereference(offloads[skb->inner_ipproto]);
 171                if (!ops || !ops->callbacks.gso_segment)
 172                        goto out_unlock;
 173                gso_inner_segment = ops->callbacks.gso_segment;
 174                break;
 175        default:
 176                goto out_unlock;
 177        }
 178
 179        segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 180                                        protocol, is_ipv6);
 181
 182out_unlock:
 183        rcu_read_unlock();
 184
 185        return segs;
 186}
 187EXPORT_SYMBOL(skb_udp_tunnel_segment);
 188
 189static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 190                                         netdev_features_t features)
 191{
 192        struct sk_buff *segs = ERR_PTR(-EINVAL);
 193        unsigned int mss;
 194        __wsum csum;
 195        struct udphdr *uh;
 196        struct iphdr *iph;
 197
 198        if (skb->encapsulation &&
 199            (skb_shinfo(skb)->gso_type &
 200             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 201                segs = skb_udp_tunnel_segment(skb, features, false);
 202                goto out;
 203        }
 204
 205        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 206                goto out;
 207
 208        mss = skb_shinfo(skb)->gso_size;
 209        if (unlikely(skb->len <= mss))
 210                goto out;
 211
 212        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 213                /* Packet is from an untrusted source, reset gso_segs. */
 214
 215                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 216
 217                segs = NULL;
 218                goto out;
 219        }
 220
 221        /* Do software UFO. Complete and fill in the UDP checksum as
 222         * HW cannot do checksum of UDP packets sent as multiple
 223         * IP fragments.
 224         */
 225
 226        uh = udp_hdr(skb);
 227        iph = ip_hdr(skb);
 228
 229        uh->check = 0;
 230        csum = skb_checksum(skb, 0, skb->len, 0);
 231        uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 232        if (uh->check == 0)
 233                uh->check = CSUM_MANGLED_0;
 234
 235        skb->ip_summed = CHECKSUM_NONE;
 236
 237        /* If there is no outer header we can fake a checksum offload
 238         * due to the fact that we have already done the checksum in
 239         * software prior to segmenting the frame.
 240         */
 241        if (!skb->encap_hdr_csum)
 242                features |= NETIF_F_HW_CSUM;
 243
 244        /* Fragment the skb. IP headers of the fragments are updated in
 245         * inet_gso_segment()
 246         */
 247        segs = skb_segment(skb, features);
 248out:
 249        return segs;
 250}
 251
 252struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 253                                 struct udphdr *uh, udp_lookup_t lookup)
 254{
 255        struct sk_buff *p, **pp = NULL;
 256        struct udphdr *uh2;
 257        unsigned int off = skb_gro_offset(skb);
 258        int flush = 1;
 259        struct sock *sk;
 260
 261        if (NAPI_GRO_CB(skb)->encap_mark ||
 262            (skb->ip_summed != CHECKSUM_PARTIAL &&
 263             NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 264             !NAPI_GRO_CB(skb)->csum_valid))
 265                goto out;
 266
 267        /* mark that this skb passed once through the tunnel gro layer */
 268        NAPI_GRO_CB(skb)->encap_mark = 1;
 269
 270        rcu_read_lock();
 271        sk = (*lookup)(skb, uh->source, uh->dest);
 272
 273        if (sk && udp_sk(sk)->gro_receive)
 274                goto unflush;
 275        goto out_unlock;
 276
 277unflush:
 278        flush = 0;
 279
 280        for (p = *head; p; p = p->next) {
 281                if (!NAPI_GRO_CB(p)->same_flow)
 282                        continue;
 283
 284                uh2 = (struct udphdr   *)(p->data + off);
 285
 286                /* Match ports and either checksums are either both zero
 287                 * or nonzero.
 288                 */
 289                if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 290                    (!uh->check ^ !uh2->check)) {
 291                        NAPI_GRO_CB(p)->same_flow = 0;
 292                        continue;
 293                }
 294        }
 295
 296        skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 297        skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 298        pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
 299
 300out_unlock:
 301        rcu_read_unlock();
 302out:
 303        NAPI_GRO_CB(skb)->flush |= flush;
 304        return pp;
 305}
 306EXPORT_SYMBOL(udp_gro_receive);
 307
 308static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 309                                         struct sk_buff *skb)
 310{
 311        struct udphdr *uh = udp_gro_udphdr(skb);
 312
 313        if (unlikely(!uh))
 314                goto flush;
 315
 316        /* Don't bother verifying checksum if we're going to flush anyway. */
 317        if (NAPI_GRO_CB(skb)->flush)
 318                goto skip;
 319
 320        if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 321                                                 inet_gro_compute_pseudo))
 322                goto flush;
 323        else if (uh->check)
 324                skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 325                                             inet_gro_compute_pseudo);
 326skip:
 327        NAPI_GRO_CB(skb)->is_ipv6 = 0;
 328        return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
 329
 330flush:
 331        NAPI_GRO_CB(skb)->flush = 1;
 332        return NULL;
 333}
 334
 335int udp_gro_complete(struct sk_buff *skb, int nhoff,
 336                     udp_lookup_t lookup)
 337{
 338        __be16 newlen = htons(skb->len - nhoff);
 339        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 340        int err = -ENOSYS;
 341        struct sock *sk;
 342
 343        uh->len = newlen;
 344
 345        /* Set encapsulation before calling into inner gro_complete() functions
 346         * to make them set up the inner offsets.
 347         */
 348        skb->encapsulation = 1;
 349
 350        rcu_read_lock();
 351        sk = (*lookup)(skb, uh->source, uh->dest);
 352        if (sk && udp_sk(sk)->gro_complete)
 353                err = udp_sk(sk)->gro_complete(sk, skb,
 354                                nhoff + sizeof(struct udphdr));
 355        rcu_read_unlock();
 356
 357        if (skb->remcsum_offload)
 358                skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 359
 360        return err;
 361}
 362EXPORT_SYMBOL(udp_gro_complete);
 363
 364static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 365{
 366        const struct iphdr *iph = ip_hdr(skb);
 367        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 368
 369        if (uh->check) {
 370                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 371                uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 372                                          iph->daddr, 0);
 373        } else {
 374                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 375        }
 376
 377        return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 378}
 379
 380static const struct net_offload udpv4_offload = {
 381        .callbacks = {
 382                .gso_segment = udp4_ufo_fragment,
 383                .gro_receive  = udp4_gro_receive,
 384                .gro_complete = udp4_gro_complete,
 385        },
 386};
 387
 388int __init udpv4_offload_init(void)
 389{
 390        return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 391}
 392