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 DEFINE_SPINLOCK(udp_offload_lock);
  18static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
  19
  20#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
  21
  22struct udp_offload_priv {
  23        struct udp_offload      *offload;
  24        possible_net_t  net;
  25        struct rcu_head         rcu;
  26        struct udp_offload_priv __rcu *next;
  27};
  28
  29static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
  30        netdev_features_t features,
  31        struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
  32                                             netdev_features_t features),
  33        __be16 new_protocol, bool is_ipv6)
  34{
  35        int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
  36        bool remcsum, need_csum, offload_csum, ufo;
  37        struct sk_buff *segs = ERR_PTR(-EINVAL);
  38        struct udphdr *uh = udp_hdr(skb);
  39        u16 mac_offset = skb->mac_header;
  40        __be16 protocol = skb->protocol;
  41        u16 mac_len = skb->mac_len;
  42        int udp_offset, outer_hlen;
  43        __wsum partial;
  44
  45        if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
  46                goto out;
  47
  48        /* Adjust partial header checksum to negate old length.
  49         * We cannot rely on the value contained in uh->len as it is
  50         * possible that the actual value exceeds the boundaries of the
  51         * 16 bit length field due to the header being added outside of an
  52         * IP or IPv6 frame that was already limited to 64K - 1.
  53         */
  54        partial = csum_sub(csum_unfold(uh->check),
  55                           (__force __wsum)htonl(skb->len));
  56
  57        /* setup inner skb. */
  58        skb->encapsulation = 0;
  59        SKB_GSO_CB(skb)->encap_level = 0;
  60        __skb_pull(skb, tnl_hlen);
  61        skb_reset_mac_header(skb);
  62        skb_set_network_header(skb, skb_inner_network_offset(skb));
  63        skb->mac_len = skb_inner_network_offset(skb);
  64        skb->protocol = new_protocol;
  65
  66        need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
  67        skb->encap_hdr_csum = need_csum;
  68
  69        remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
  70        skb->remcsum_offload = remcsum;
  71
  72        ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
  73
  74        /* Try to offload checksum if possible */
  75        offload_csum = !!(need_csum &&
  76                          (skb->dev->features &
  77                           (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
  78                                      (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
  79
  80        features &= skb->dev->hw_enc_features;
  81
  82        /* The only checksum offload we care about from here on out is the
  83         * outer one so strip the existing checksum feature flags and
  84         * instead set the flag based on our outer checksum offload value.
  85         */
  86        if (remcsum || ufo) {
  87                features &= ~NETIF_F_CSUM_MASK;
  88                if (!need_csum || offload_csum)
  89                        features |= NETIF_F_HW_CSUM;
  90        }
  91
  92        /* segment inner packet. */
  93        segs = gso_inner_segment(skb, features);
  94        if (IS_ERR_OR_NULL(segs)) {
  95                skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
  96                                     mac_len);
  97                goto out;
  98        }
  99
 100        outer_hlen = skb_tnl_header_len(skb);
 101        udp_offset = outer_hlen - tnl_hlen;
 102        skb = segs;
 103        do {
 104                __be16 len;
 105
 106                if (remcsum)
 107                        skb->ip_summed = CHECKSUM_NONE;
 108
 109                /* Set up inner headers if we are offloading inner checksum */
 110                if (skb->ip_summed == CHECKSUM_PARTIAL) {
 111                        skb_reset_inner_headers(skb);
 112                        skb->encapsulation = 1;
 113                }
 114
 115                skb->mac_len = mac_len;
 116                skb->protocol = protocol;
 117
 118                __skb_push(skb, outer_hlen);
 119                skb_reset_mac_header(skb);
 120                skb_set_network_header(skb, mac_len);
 121                skb_set_transport_header(skb, udp_offset);
 122                len = htons(skb->len - udp_offset);
 123                uh = udp_hdr(skb);
 124                uh->len = len;
 125
 126                if (!need_csum)
 127                        continue;
 128
 129                uh->check = ~csum_fold(csum_add(partial, (__force __wsum)len));
 130
 131                if (skb->encapsulation || !offload_csum) {
 132                        uh->check = gso_make_checksum(skb, ~uh->check);
 133                        if (uh->check == 0)
 134                                uh->check = CSUM_MANGLED_0;
 135                } else {
 136                        skb->ip_summed = CHECKSUM_PARTIAL;
 137                        skb->csum_start = skb_transport_header(skb) - skb->head;
 138                        skb->csum_offset = offsetof(struct udphdr, check);
 139                }
 140        } while ((skb = skb->next));
 141out:
 142        return segs;
 143}
 144
 145struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 146                                       netdev_features_t features,
 147                                       bool is_ipv6)
 148{
 149        __be16 protocol = skb->protocol;
 150        const struct net_offload **offloads;
 151        const struct net_offload *ops;
 152        struct sk_buff *segs = ERR_PTR(-EINVAL);
 153        struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 154                                             netdev_features_t features);
 155
 156        rcu_read_lock();
 157
 158        switch (skb->inner_protocol_type) {
 159        case ENCAP_TYPE_ETHER:
 160                protocol = skb->inner_protocol;
 161                gso_inner_segment = skb_mac_gso_segment;
 162                break;
 163        case ENCAP_TYPE_IPPROTO:
 164                offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 165                ops = rcu_dereference(offloads[skb->inner_ipproto]);
 166                if (!ops || !ops->callbacks.gso_segment)
 167                        goto out_unlock;
 168                gso_inner_segment = ops->callbacks.gso_segment;
 169                break;
 170        default:
 171                goto out_unlock;
 172        }
 173
 174        segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 175                                        protocol, is_ipv6);
 176
 177out_unlock:
 178        rcu_read_unlock();
 179
 180        return segs;
 181}
 182
 183static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 184                                         netdev_features_t features)
 185{
 186        struct sk_buff *segs = ERR_PTR(-EINVAL);
 187        unsigned int mss;
 188        __wsum csum;
 189        struct udphdr *uh;
 190        struct iphdr *iph;
 191
 192        if (skb->encapsulation &&
 193            (skb_shinfo(skb)->gso_type &
 194             (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 195                segs = skb_udp_tunnel_segment(skb, features, false);
 196                goto out;
 197        }
 198
 199        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 200                goto out;
 201
 202        mss = skb_shinfo(skb)->gso_size;
 203        if (unlikely(skb->len <= mss))
 204                goto out;
 205
 206        if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 207                /* Packet is from an untrusted source, reset gso_segs. */
 208                int type = skb_shinfo(skb)->gso_type;
 209
 210                if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
 211                                      SKB_GSO_UDP_TUNNEL |
 212                                      SKB_GSO_UDP_TUNNEL_CSUM |
 213                                      SKB_GSO_TUNNEL_REMCSUM |
 214                                      SKB_GSO_IPIP |
 215                                      SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
 216                             !(type & (SKB_GSO_UDP))))
 217                        goto out;
 218
 219                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 220
 221                segs = NULL;
 222                goto out;
 223        }
 224
 225        /* Do software UFO. Complete and fill in the UDP checksum as
 226         * HW cannot do checksum of UDP packets sent as multiple
 227         * IP fragments.
 228         */
 229
 230        uh = udp_hdr(skb);
 231        iph = ip_hdr(skb);
 232
 233        uh->check = 0;
 234        csum = skb_checksum(skb, 0, skb->len, 0);
 235        uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 236        if (uh->check == 0)
 237                uh->check = CSUM_MANGLED_0;
 238
 239        skb->ip_summed = CHECKSUM_NONE;
 240
 241        /* If there is no outer header we can fake a checksum offload
 242         * due to the fact that we have already done the checksum in
 243         * software prior to segmenting the frame.
 244         */
 245        if (!skb->encap_hdr_csum)
 246                features |= NETIF_F_HW_CSUM;
 247
 248        /* Fragment the skb. IP headers of the fragments are updated in
 249         * inet_gso_segment()
 250         */
 251        segs = skb_segment(skb, features);
 252out:
 253        return segs;
 254}
 255
 256int udp_add_offload(struct net *net, struct udp_offload *uo)
 257{
 258        struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
 259
 260        if (!new_offload)
 261                return -ENOMEM;
 262
 263        write_pnet(&new_offload->net, net);
 264        new_offload->offload = uo;
 265
 266        spin_lock(&udp_offload_lock);
 267        new_offload->next = udp_offload_base;
 268        rcu_assign_pointer(udp_offload_base, new_offload);
 269        spin_unlock(&udp_offload_lock);
 270
 271        return 0;
 272}
 273EXPORT_SYMBOL(udp_add_offload);
 274
 275static void udp_offload_free_routine(struct rcu_head *head)
 276{
 277        struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
 278        kfree(ou_priv);
 279}
 280
 281void udp_del_offload(struct udp_offload *uo)
 282{
 283        struct udp_offload_priv __rcu **head = &udp_offload_base;
 284        struct udp_offload_priv *uo_priv;
 285
 286        spin_lock(&udp_offload_lock);
 287
 288        uo_priv = udp_deref_protected(*head);
 289        for (; uo_priv != NULL;
 290             uo_priv = udp_deref_protected(*head)) {
 291                if (uo_priv->offload == uo) {
 292                        rcu_assign_pointer(*head,
 293                                           udp_deref_protected(uo_priv->next));
 294                        goto unlock;
 295                }
 296                head = &uo_priv->next;
 297        }
 298        pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
 299unlock:
 300        spin_unlock(&udp_offload_lock);
 301        if (uo_priv)
 302                call_rcu(&uo_priv->rcu, udp_offload_free_routine);
 303}
 304EXPORT_SYMBOL(udp_del_offload);
 305
 306struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 307                                 struct udphdr *uh)
 308{
 309        struct udp_offload_priv *uo_priv;
 310        struct sk_buff *p, **pp = NULL;
 311        struct udphdr *uh2;
 312        unsigned int off = skb_gro_offset(skb);
 313        int flush = 1;
 314
 315        if (NAPI_GRO_CB(skb)->encap_mark ||
 316            (skb->ip_summed != CHECKSUM_PARTIAL &&
 317             NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 318             !NAPI_GRO_CB(skb)->csum_valid))
 319                goto out;
 320
 321        /* mark that this skb passed once through the tunnel gro layer */
 322        NAPI_GRO_CB(skb)->encap_mark = 1;
 323
 324        rcu_read_lock();
 325        uo_priv = rcu_dereference(udp_offload_base);
 326        for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 327                if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
 328                    uo_priv->offload->port == uh->dest &&
 329                    uo_priv->offload->callbacks.gro_receive)
 330                        goto unflush;
 331        }
 332        goto out_unlock;
 333
 334unflush:
 335        flush = 0;
 336
 337        for (p = *head; p; p = p->next) {
 338                if (!NAPI_GRO_CB(p)->same_flow)
 339                        continue;
 340
 341                uh2 = (struct udphdr   *)(p->data + off);
 342
 343                /* Match ports and either checksums are either both zero
 344                 * or nonzero.
 345                 */
 346                if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 347                    (!uh->check ^ !uh2->check)) {
 348                        NAPI_GRO_CB(p)->same_flow = 0;
 349                        continue;
 350                }
 351        }
 352
 353        skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 354        skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 355        NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 356        pp = uo_priv->offload->callbacks.gro_receive(head, skb,
 357                                                     uo_priv->offload);
 358
 359out_unlock:
 360        rcu_read_unlock();
 361out:
 362        NAPI_GRO_CB(skb)->flush |= flush;
 363        return pp;
 364}
 365
 366static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 367                                         struct sk_buff *skb)
 368{
 369        struct udphdr *uh = udp_gro_udphdr(skb);
 370
 371        if (unlikely(!uh))
 372                goto flush;
 373
 374        /* Don't bother verifying checksum if we're going to flush anyway. */
 375        if (NAPI_GRO_CB(skb)->flush)
 376                goto skip;
 377
 378        if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 379                                                 inet_gro_compute_pseudo))
 380                goto flush;
 381        else if (uh->check)
 382                skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 383                                             inet_gro_compute_pseudo);
 384skip:
 385        NAPI_GRO_CB(skb)->is_ipv6 = 0;
 386        return udp_gro_receive(head, skb, uh);
 387
 388flush:
 389        NAPI_GRO_CB(skb)->flush = 1;
 390        return NULL;
 391}
 392
 393int udp_gro_complete(struct sk_buff *skb, int nhoff)
 394{
 395        struct udp_offload_priv *uo_priv;
 396        __be16 newlen = htons(skb->len - nhoff);
 397        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 398        int err = -ENOSYS;
 399
 400        uh->len = newlen;
 401
 402        /* Set encapsulation before calling into inner gro_complete() functions
 403         * to make them set up the inner offsets.
 404         */
 405        skb->encapsulation = 1;
 406
 407        rcu_read_lock();
 408
 409        uo_priv = rcu_dereference(udp_offload_base);
 410        for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 411                if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
 412                    uo_priv->offload->port == uh->dest &&
 413                    uo_priv->offload->callbacks.gro_complete)
 414                        break;
 415        }
 416
 417        if (uo_priv) {
 418                NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 419                err = uo_priv->offload->callbacks.gro_complete(skb,
 420                                nhoff + sizeof(struct udphdr),
 421                                uo_priv->offload);
 422        }
 423
 424        rcu_read_unlock();
 425
 426        if (skb->remcsum_offload)
 427                skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 428
 429        return err;
 430}
 431
 432static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 433{
 434        const struct iphdr *iph = ip_hdr(skb);
 435        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 436
 437        if (uh->check) {
 438                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 439                uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 440                                          iph->daddr, 0);
 441        } else {
 442                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 443        }
 444
 445        return udp_gro_complete(skb, nhoff);
 446}
 447
 448static const struct net_offload udpv4_offload = {
 449        .callbacks = {
 450                .gso_segment = udp4_ufo_fragment,
 451                .gro_receive  = udp4_gro_receive,
 452                .gro_complete = udp4_gro_complete,
 453        },
 454};
 455
 456int __init udpv4_offload_init(void)
 457{
 458        return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 459}
 460