LXR linux/net/ipv6/ip6

   1/*
   2 *      IPV6 GSO/GRO offload support
   3 *      Linux INET6 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
  11#include <linux/kernel.h>
  12#include <linux/socket.h>
  13#include <linux/netdevice.h>
  14#include <linux/skbuff.h>
  15#include <linux/printk.h>
  16
  17#include <net/protocol.h>
  18#include <net/ipv6.h>
  19#include <net/inet_common.h>
  20
  21#include "ip6_offload.h"
  22
  23static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
  24{
  25        const struct net_offload *ops = NULL;
  26
  27        for (;;) {
  28                struct ipv6_opt_hdr *opth;
  29                int len;
  30
  31                if (proto != NEXTHDR_HOP) {
  32                        ops = rcu_dereference(inet6_offloads[proto]);
  33
  34                        if (unlikely(!ops))
  35                                break;
  36
  37                        if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
  38                                break;
  39                }
  40
  41                if (unlikely(!pskb_may_pull(skb, 8)))
  42                        break;
  43
  44                opth = (void *)skb->data;
  45                len = ipv6_optlen(opth);
  46
  47                if (unlikely(!pskb_may_pull(skb, len)))
  48                        break;
  49
  50                opth = (void *)skb->data;
  51                proto = opth->nexthdr;
  52                __skb_pull(skb, len);
  53        }
  54
  55        return proto;
  56}
  57
  58static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
  59        netdev_features_t features)
  60{
  61        struct sk_buff *segs = ERR_PTR(-EINVAL);
  62        struct ipv6hdr *ipv6h;
  63        const struct net_offload *ops;
  64        int proto;
  65        struct frag_hdr *fptr;
  66        unsigned int unfrag_ip6hlen;
  67        unsigned int payload_len;
  68        u8 *prevhdr;
  69        int offset = 0;
  70        bool encap, udpfrag;
  71        int nhoff;
  72        bool gso_partial;
  73
  74        skb_reset_network_header(skb);
  75        nhoff = skb_network_header(skb) - skb_mac_header(skb);
  76        if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
  77                goto out;
  78
  79        encap = SKB_GSO_CB(skb)->encap_level > 0;
  80        if (encap)
  81                features &= skb->dev->hw_enc_features;
  82        SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
  83
  84        ipv6h = ipv6_hdr(skb);
  85        __skb_pull(skb, sizeof(*ipv6h));
  86        segs = ERR_PTR(-EPROTONOSUPPORT);
  87
  88        proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
  89
  90        if (skb->encapsulation &&
  91            skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))
  92                udpfrag = proto == IPPROTO_UDP && encap;
  93        else
  94                udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
  95
  96        ops = rcu_dereference(inet6_offloads[proto]);
  97        if (likely(ops && ops->callbacks.gso_segment)) {
  98                skb_reset_transport_header(skb);
  99                segs = ops->callbacks.gso_segment(skb, features);
 100        }
 101
 102        if (IS_ERR_OR_NULL(segs))
 103                goto out;
 104
 105        gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
 106
 107        for (skb = segs; skb; skb = skb->next) {
 108                ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
 109                if (gso_partial)
 110                        payload_len = skb_shinfo(skb)->gso_size +
 111                                      SKB_GSO_CB(skb)->data_offset +
 112                                      skb->head - (unsigned char *)(ipv6h + 1);
 113                else
 114                        payload_len = skb->len - nhoff - sizeof(*ipv6h);
 115                ipv6h->payload_len = htons(payload_len);
 116                skb->network_header = (u8 *)ipv6h - skb->head;
 117
 118                if (udpfrag) {
 119                        unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 120                        fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
 121                        fptr->frag_off = htons(offset);
 122                        if (skb->next)
 123                                fptr->frag_off |= htons(IP6_MF);
 124                        offset += (ntohs(ipv6h->payload_len) -
 125                                   sizeof(struct frag_hdr));
 126                }
 127                if (encap)
 128                        skb_reset_inner_headers(skb);
 129        }
 130
 131out:
 132        return segs;
 133}
 134
 135/* Return the total length of all the extension hdrs, following the same
 136 * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
 137 */
 138static int ipv6_exthdrs_len(struct ipv6hdr *iph,
 139                            const struct net_offload **opps)
 140{
 141        struct ipv6_opt_hdr *opth = (void *)iph;
 142        int len = 0, proto, optlen = sizeof(*iph);
 143
 144        proto = iph->nexthdr;
 145        for (;;) {
 146                if (proto != NEXTHDR_HOP) {
 147                        *opps = rcu_dereference(inet6_offloads[proto]);
 148                        if (unlikely(!(*opps)))
 149                                break;
 150                        if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
 151                                break;
 152                }
 153                opth = (void *)opth + optlen;
 154                optlen = ipv6_optlen(opth);
 155                len += optlen;
 156                proto = opth->nexthdr;
 157        }
 158        return len;
 159}
 160
 161static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 162                                         struct sk_buff *skb)
 163{
 164        const struct net_offload *ops;
 165        struct sk_buff **pp = NULL;
 166        struct sk_buff *p;
 167        struct ipv6hdr *iph;
 168        unsigned int nlen;
 169        unsigned int hlen;
 170        unsigned int off;
 171        u16 flush = 1;
 172        int proto;
 173
 174        off = skb_gro_offset(skb);
 175        hlen = off + sizeof(*iph);
 176        iph = skb_gro_header_fast(skb, off);
 177        if (skb_gro_header_hard(skb, hlen)) {
 178                iph = skb_gro_header_slow(skb, hlen, off);
 179                if (unlikely(!iph))
 180                        goto out;
 181        }
 182
 183        skb_set_network_header(skb, off);
 184        skb_gro_pull(skb, sizeof(*iph));
 185        skb_set_transport_header(skb, skb_gro_offset(skb));
 186
 187        flush += ntohs(iph->payload_len) != skb_gro_len(skb);
 188
 189        rcu_read_lock();
 190        proto = iph->nexthdr;
 191        ops = rcu_dereference(inet6_offloads[proto]);
 192        if (!ops || !ops->callbacks.gro_receive) {
 193                __pskb_pull(skb, skb_gro_offset(skb));
 194                proto = ipv6_gso_pull_exthdrs(skb, proto);
 195                skb_gro_pull(skb, -skb_transport_offset(skb));
 196                skb_reset_transport_header(skb);
 197                __skb_push(skb, skb_gro_offset(skb));
 198
 199                ops = rcu_dereference(inet6_offloads[proto]);
 200                if (!ops || !ops->callbacks.gro_receive)
 201                        goto out_unlock;
 202
 203                iph = ipv6_hdr(skb);
 204        }
 205
 206        NAPI_GRO_CB(skb)->proto = proto;
 207
 208        flush--;
 209        nlen = skb_network_header_len(skb);
 210
 211        for (p = *head; p; p = p->next) {
 212                const struct ipv6hdr *iph2;
 213                __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
 214
 215                if (!NAPI_GRO_CB(p)->same_flow)
 216                        continue;
 217
 218                iph2 = (struct ipv6hdr *)(p->data + off);
 219                first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
 220
 221                /* All fields must match except length and Traffic Class.
 222                 * XXX skbs on the gro_list have all been parsed and pulled
 223                 * already so we don't need to compare nlen
 224                 * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
 225                 * memcmp() alone below is suffcient, right?
 226                 */
 227                 if ((first_word & htonl(0xF00FFFFF)) ||
 228                    memcmp(&iph->nexthdr, &iph2->nexthdr,
 229                           nlen - offsetof(struct ipv6hdr, nexthdr))) {
 230                        NAPI_GRO_CB(p)->same_flow = 0;
 231                        continue;
 232                }
 233                /* flush if Traffic Class fields are different */
 234                NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
 235                NAPI_GRO_CB(p)->flush |= flush;
 236
 237                /* If the previous IP ID value was based on an atomic
 238                 * datagram we can overwrite the value and ignore it.
 239                 */
 240                if (NAPI_GRO_CB(skb)->is_atomic)
 241                        NAPI_GRO_CB(p)->flush_id = 0;
 242        }
 243
 244        NAPI_GRO_CB(skb)->is_atomic = true;
 245        NAPI_GRO_CB(skb)->flush |= flush;
 246
 247        skb_gro_postpull_rcsum(skb, iph, nlen);
 248
 249        pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
 250
 251out_unlock:
 252        rcu_read_unlock();
 253
 254out:
 255        NAPI_GRO_CB(skb)->flush |= flush;
 256
 257        return pp;
 258}
 259
 260static struct sk_buff **sit_ip6ip6_gro_receive(struct sk_buff **head,
 261                                               struct sk_buff *skb)
 262{
 263        /* Common GRO receive for SIT and IP6IP6 */
 264
 265        if (NAPI_GRO_CB(skb)->encap_mark) {
 266                NAPI_GRO_CB(skb)->flush = 1;
 267                return NULL;
 268        }
 269
 270        NAPI_GRO_CB(skb)->encap_mark = 1;
 271
 272        return ipv6_gro_receive(head, skb);
 273}
 274
 275static struct sk_buff **ip4ip6_gro_receive(struct sk_buff **head,
 276                                           struct sk_buff *skb)
 277{
 278        /* Common GRO receive for SIT and IP6IP6 */
 279
 280        if (NAPI_GRO_CB(skb)->encap_mark) {
 281                NAPI_GRO_CB(skb)->flush = 1;
 282                return NULL;
 283        }
 284
 285        NAPI_GRO_CB(skb)->encap_mark = 1;
 286
 287        return inet_gro_receive(head, skb);
 288}
 289
 290static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 291{
 292        const struct net_offload *ops;
 293        struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
 294        int err = -ENOSYS;
 295
 296        if (skb->encapsulation)
 297                skb_set_inner_network_header(skb, nhoff);
 298
 299        iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
 300
 301        rcu_read_lock();
 302
 303        nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
 304        if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 305                goto out_unlock;
 306
 307        err = ops->callbacks.gro_complete(skb, nhoff);
 308
 309out_unlock:
 310        rcu_read_unlock();
 311
 312        return err;
 313}
 314
 315static int sit_gro_complete(struct sk_buff *skb, int nhoff)
 316{
 317        skb->encapsulation = 1;
 318        skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
 319        return ipv6_gro_complete(skb, nhoff);
 320}
 321
 322static int ip6ip6_gro_complete(struct sk_buff *skb, int nhoff)
 323{
 324        skb->encapsulation = 1;
 325        skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
 326        return ipv6_gro_complete(skb, nhoff);
 327}
 328
 329static int ip4ip6_gro_complete(struct sk_buff *skb, int nhoff)
 330{
 331        skb->encapsulation = 1;
 332        skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
 333        return inet_gro_complete(skb, nhoff);
 334}
 335
 336static struct packet_offload ipv6_packet_offload __read_mostly = {
 337        .type = cpu_to_be16(ETH_P_IPV6),
 338        .callbacks = {
 339                .gso_segment = ipv6_gso_segment,
 340                .gro_receive = ipv6_gro_receive,
 341                .gro_complete = ipv6_gro_complete,
 342        },
 343};
 344
 345static const struct net_offload sit_offload = {
 346        .callbacks = {
 347                .gso_segment    = ipv6_gso_segment,
 348                .gro_receive    = sit_ip6ip6_gro_receive,
 349                .gro_complete   = sit_gro_complete,
 350        },
 351};
 352
 353static const struct net_offload ip4ip6_offload = {
 354        .callbacks = {
 355                .gso_segment    = inet_gso_segment,
 356                .gro_receive    = ip4ip6_gro_receive,
 357                .gro_complete   = ip4ip6_gro_complete,
 358        },
 359};
 360
 361static const struct net_offload ip6ip6_offload = {
 362        .callbacks = {
 363                .gso_segment    = ipv6_gso_segment,
 364                .gro_receive    = sit_ip6ip6_gro_receive,
 365                .gro_complete   = ip6ip6_gro_complete,
 366        },
 367};
 368static int __init ipv6_offload_init(void)
 369{
 370
 371        if (tcpv6_offload_init() < 0)
 372                pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 373        if (ipv6_exthdrs_offload_init() < 0)
 374                pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
 375
 376        dev_add_offload(&ipv6_packet_offload);
 377
 378        inet_add_offload(&sit_offload, IPPROTO_IPV6);
 379        inet6_add_offload(&ip6ip6_offload, IPPROTO_IPV6);
 380        inet6_add_offload(&ip4ip6_offload, IPPROTO_IPIP);
 381
 382        return 0;
 383}
 384
 385fs_initcall(ipv6_offload_init);
 386