datapath/flow.c

   1 /*
   2  * Copyright (c) 2007-2013 Nicira, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301, USA
  17  */
  18
  19 #include "flow.h"
  20 #include "datapath.h"
  21 #include <linux/uaccess.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/etherdevice.h>
  24 #include <linux/if_ether.h>
  25 #include <linux/if_vlan.h>
  26 #include <net/llc_pdu.h>
  27 #include <linux/kernel.h>
  28 #include <linux/jhash.h>
  29 #include <linux/jiffies.h>
  30 #include <linux/llc.h>
  31 #include <linux/module.h>
  32 #include <linux/in.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/if_arp.h>
  35 #include <linux/ip.h>
  36 #include <linux/ipv6.h>
  37 #include <linux/sctp.h>
  38 #include <linux/smp.h>
  39 #include <linux/tcp.h>
  40 #include <linux/udp.h>
  41 #include <linux/icmp.h>
  42 #include <linux/icmpv6.h>
  43 #include <linux/rculist.h>
  44 #include <net/ip.h>
  45 #include <net/ipv6.h>
  46 #include <net/ndisc.h>
  47
  48 #include "vlan.h"
  49
  50 u64 ovs_flow_used_time(unsigned long flow_jiffies)
  51 {
  52         struct timespec cur_ts;
  53         u64 cur_ms, idle_ms;
  54
  55         ktime_get_ts(&cur_ts);
  56         idle_ms = jiffies_to_msecs(jiffies - flow_jiffies);
  57         cur_ms = (u64)cur_ts.tv_sec * MSEC_PER_SEC +
  58                  cur_ts.tv_nsec / NSEC_PER_MSEC;
  59
  60         return cur_ms - idle_ms;
  61 }
  62
  63 #define TCP_FLAGS_BE16(tp) (*(__be16 *)&tcp_flag_word(tp) & htons(0x0FFF))
  64
  65 void ovs_flow_stats_update(struct sw_flow *flow, struct sk_buff *skb)
  66 {
  67         struct flow_stats *stats;
  68         __be16 tcp_flags = 0;
  69
  70         if (!flow->stats.is_percpu)
  71                 stats = flow->stats.stat;
  72         else
  73                 stats = this_cpu_ptr(flow->stats.cpu_stats);
  74
  75         if ((flow->key.eth.type == htons(ETH_P_IP) ||
  76              flow->key.eth.type == htons(ETH_P_IPV6)) &&
  77             flow->key.ip.proto == IPPROTO_TCP &&
  78             likely(skb->len >= skb_transport_offset(skb) + sizeof(struct tcphdr))) {
  79                 tcp_flags = TCP_FLAGS_BE16(tcp_hdr(skb));
  80         }
  81
  82         spin_lock(&stats->lock);
  83         stats->used = jiffies;
  84         stats->packet_count++;
  85         stats->byte_count += skb->len;
  86         stats->tcp_flags |= tcp_flags;
  87         spin_unlock(&stats->lock);
  88 }
  89
  90 static void stats_read(struct flow_stats *stats,
  91                        struct ovs_flow_stats *ovs_stats,
  92                        unsigned long *used, __be16 *tcp_flags)
  93 {
  94         spin_lock(&stats->lock);
  95         if (time_after(stats->used, *used))
  96                 *used = stats->used;
  97         *tcp_flags |= stats->tcp_flags;
  98         ovs_stats->n_packets += stats->packet_count;
  99         ovs_stats->n_bytes += stats->byte_count;
 100         spin_unlock(&stats->lock);
 101 }
 102
 103 void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
 104                         unsigned long *used, __be16 *tcp_flags)
 105 {
 106         int cpu, cur_cpu;
 107
 108         *used = 0;
 109         *tcp_flags = 0;
 110         memset(ovs_stats, 0, sizeof(*ovs_stats));
 111
 112         if (!flow->stats.is_percpu) {
 113                 stats_read(flow->stats.stat, ovs_stats, used, tcp_flags);
 114         } else {
 115                 cur_cpu = get_cpu();
 116                 for_each_possible_cpu(cpu) {
 117                         struct flow_stats *stats;
 118
 119                         if (cpu == cur_cpu)
 120                                 local_bh_disable();
 121
 122                         stats = per_cpu_ptr(flow->stats.cpu_stats, cpu);
 123                         stats_read(stats, ovs_stats, used, tcp_flags);
 124
 125                         if (cpu == cur_cpu)
 126                                 local_bh_enable();
 127                 }
 128                 put_cpu();
 129         }
 130 }
 131
 132 static void stats_reset(struct flow_stats *stats)
 133 {
 134         spin_lock(&stats->lock);
 135         stats->used = 0;
 136         stats->packet_count = 0;
 137         stats->byte_count = 0;
 138         stats->tcp_flags = 0;
 139         spin_unlock(&stats->lock);
 140 }
 141
 142 void ovs_flow_stats_clear(struct sw_flow *flow)
 143 {
 144         int cpu, cur_cpu;
 145
 146         if (!flow->stats.is_percpu) {
 147                 stats_reset(flow->stats.stat);
 148         } else {
 149                 cur_cpu = get_cpu();
 150
 151                 for_each_possible_cpu(cpu) {
 152
 153                         if (cpu == cur_cpu)
 154                                 local_bh_disable();
 155
 156                         stats_reset(per_cpu_ptr(flow->stats.cpu_stats, cpu));
 157
 158                         if (cpu == cur_cpu)
 159                                 local_bh_enable();
 160                 }
 161                 put_cpu();
 162         }
 163 }
 164
 165 static int check_header(struct sk_buff *skb, int len)
 166 {
 167         if (unlikely(skb->len < len))
 168                 return -EINVAL;
 169         if (unlikely(!pskb_may_pull(skb, len)))
 170                 return -ENOMEM;
 171         return 0;
 172 }
 173
 174 static bool arphdr_ok(struct sk_buff *skb)
 175 {
 176         return pskb_may_pull(skb, skb_network_offset(skb) +
 177                                   sizeof(struct arp_eth_header));
 178 }
 179
 180 static int check_iphdr(struct sk_buff *skb)
 181 {
 182         unsigned int nh_ofs = skb_network_offset(skb);
 183         unsigned int ip_len;
 184         int err;
 185
 186         err = check_header(skb, nh_ofs + sizeof(struct iphdr));
 187         if (unlikely(err))
 188                 return err;
 189
 190         ip_len = ip_hdrlen(skb);
 191         if (unlikely(ip_len < sizeof(struct iphdr) ||
 192                      skb->len < nh_ofs + ip_len))
 193                 return -EINVAL;
 194
 195         skb_set_transport_header(skb, nh_ofs + ip_len);
 196         return 0;
 197 }
 198
 199 static bool tcphdr_ok(struct sk_buff *skb)
 200 {
 201         int th_ofs = skb_transport_offset(skb);
 202         int tcp_len;
 203
 204         if (unlikely(!pskb_may_pull(skb, th_ofs + sizeof(struct tcphdr))))
 205                 return false;
 206
 207         tcp_len = tcp_hdrlen(skb);
 208         if (unlikely(tcp_len < sizeof(struct tcphdr) ||
 209                      skb->len < th_ofs + tcp_len))
 210                 return false;
 211
 212         return true;
 213 }
 214
 215 static bool udphdr_ok(struct sk_buff *skb)
 216 {
 217         return pskb_may_pull(skb, skb_transport_offset(skb) +
 218                                   sizeof(struct udphdr));
 219 }
 220
 221 static bool sctphdr_ok(struct sk_buff *skb)
 222 {
 223         return pskb_may_pull(skb, skb_transport_offset(skb) +
 224                                   sizeof(struct sctphdr));
 225 }
 226
 227 static bool icmphdr_ok(struct sk_buff *skb)
 228 {
 229         return pskb_may_pull(skb, skb_transport_offset(skb) +
 230                                   sizeof(struct icmphdr));
 231 }
 232
 233 static int parse_ipv6hdr(struct sk_buff *skb, struct sw_flow_key *key)
 234 {
 235         unsigned int nh_ofs = skb_network_offset(skb);
 236         unsigned int nh_len;
 237         int payload_ofs;
 238         struct ipv6hdr *nh;
 239         uint8_t nexthdr;
 240         __be16 frag_off;
 241         int err;
 242
 243         err = check_header(skb, nh_ofs + sizeof(*nh));
 244         if (unlikely(err))
 245                 return err;
 246
 247         nh = ipv6_hdr(skb);
 248         nexthdr = nh->nexthdr;
 249         payload_ofs = (u8 *)(nh + 1) - skb->data;
 250
 251         key->ip.proto = NEXTHDR_NONE;
 252         key->ip.tos = ipv6_get_dsfield(nh);
 253         key->ip.ttl = nh->hop_limit;
 254         key->ipv6.label = *(__be32 *)nh & htonl(IPV6_FLOWINFO_FLOWLABEL);
 255         key->ipv6.addr.src = nh->saddr;
 256         key->ipv6.addr.dst = nh->daddr;
 257
 258         payload_ofs = ipv6_skip_exthdr(skb, payload_ofs, &nexthdr, &frag_off);
 259         if (unlikely(payload_ofs < 0))
 260                 return -EINVAL;
 261
 262         if (frag_off) {
 263                 if (frag_off & htons(~0x7))
 264                         key->ip.frag = OVS_FRAG_TYPE_LATER;
 265                 else
 266                         key->ip.frag = OVS_FRAG_TYPE_FIRST;
 267         }
 268
 269         nh_len = payload_ofs - nh_ofs;
 270         skb_set_transport_header(skb, nh_ofs + nh_len);
 271         key->ip.proto = nexthdr;
 272         return nh_len;
 273 }
 274
 275 static bool icmp6hdr_ok(struct sk_buff *skb)
 276 {
 277         return pskb_may_pull(skb, skb_transport_offset(skb) +
 278                                   sizeof(struct icmp6hdr));
 279 }
 280
 281 static int parse_vlan(struct sk_buff *skb, struct sw_flow_key *key)
 282 {
 283         struct qtag_prefix {
 284                 __be16 eth_type; /* ETH_P_8021Q */
 285                 __be16 tci;
 286         };
 287         struct qtag_prefix *qp;
 288
 289         if (unlikely(skb->len < sizeof(struct qtag_prefix) + sizeof(__be16)))
 290                 return 0;
 291
 292         if (unlikely(!pskb_may_pull(skb, sizeof(struct qtag_prefix) +
 293                                          sizeof(__be16))))
 294                 return -ENOMEM;
 295
 296         qp = (struct qtag_prefix *) skb->data;
 297         key->eth.tci = qp->tci | htons(VLAN_TAG_PRESENT);
 298         __skb_pull(skb, sizeof(struct qtag_prefix));
 299
 300         return 0;
 301 }
 302
 303 static __be16 parse_ethertype(struct sk_buff *skb)
 304 {
 305         struct llc_snap_hdr {
 306                 u8  dsap;  /* Always 0xAA */
 307                 u8  ssap;  /* Always 0xAA */
 308                 u8  ctrl;
 309                 u8  oui[3];
 310                 __be16 ethertype;
 311         };
 312         struct llc_snap_hdr *llc;
 313         __be16 proto;
 314
 315         proto = *(__be16 *) skb->data;
 316         __skb_pull(skb, sizeof(__be16));
 317
 318         if (ntohs(proto) >= ETH_P_802_3_MIN)
 319                 return proto;
 320
 321         if (skb->len < sizeof(struct llc_snap_hdr))
 322                 return htons(ETH_P_802_2);
 323
 324         if (unlikely(!pskb_may_pull(skb, sizeof(struct llc_snap_hdr))))
 325                 return htons(0);
 326
 327         llc = (struct llc_snap_hdr *) skb->data;
 328         if (llc->dsap != LLC_SAP_SNAP ||
 329             llc->ssap != LLC_SAP_SNAP ||
 330             (llc->oui[0] | llc->oui[1] | llc->oui[2]) != 0)
 331                 return htons(ETH_P_802_2);
 332
 333         __skb_pull(skb, sizeof(struct llc_snap_hdr));
 334
 335         if (ntohs(llc->ethertype) >= ETH_P_802_3_MIN)
 336                 return llc->ethertype;
 337
 338         return htons(ETH_P_802_2);
 339 }
 340
 341 static int parse_icmpv6(struct sk_buff *skb, struct sw_flow_key *key,
 342                         int nh_len)
 343 {
 344         struct icmp6hdr *icmp = icmp6_hdr(skb);
 345
 346         /* The ICMPv6 type and code fields use the 16-bit transport port
 347          * fields, so we need to store them in 16-bit network byte order.
 348          */
 349         key->ipv6.tp.src = htons(icmp->icmp6_type);
 350         key->ipv6.tp.dst = htons(icmp->icmp6_code);
 351
 352         if (icmp->icmp6_code == 0 &&
 353             (icmp->icmp6_type == NDISC_NEIGHBOUR_SOLICITATION ||
 354              icmp->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT)) {
 355                 int icmp_len = skb->len - skb_transport_offset(skb);
 356                 struct nd_msg *nd;
 357                 int offset;
 358
 359                 /* In order to process neighbor discovery options, we need the
 360                  * entire packet.
 361                  */
 362                 if (unlikely(icmp_len < sizeof(*nd)))
 363                         return 0;
 364
 365                 if (unlikely(skb_linearize(skb)))
 366                         return -ENOMEM;
 367
 368                 nd = (struct nd_msg *)skb_transport_header(skb);
 369                 key->ipv6.nd.target = nd->target;
 370
 371                 icmp_len -= sizeof(*nd);
 372                 offset = 0;
 373                 while (icmp_len >= 8) {
 374                         struct nd_opt_hdr *nd_opt =
 375                                  (struct nd_opt_hdr *)(nd->opt + offset);
 376                         int opt_len = nd_opt->nd_opt_len * 8;
 377
 378                         if (unlikely(!opt_len || opt_len > icmp_len))
 379                                 return 0;
 380
 381                         /* Store the link layer address if the appropriate
 382                          * option is provided.  It is considered an error if
 383                          * the same link layer option is specified twice.
 384                          */
 385                         if (nd_opt->nd_opt_type == ND_OPT_SOURCE_LL_ADDR
 386                             && opt_len == 8) {
 387                                 if (unlikely(!is_zero_ether_addr(key->ipv6.nd.sll)))
 388                                         goto invalid;
 389                                 memcpy(key->ipv6.nd.sll,
 390                                     &nd->opt[offset+sizeof(*nd_opt)], ETH_ALEN);
 391                         } else if (nd_opt->nd_opt_type == ND_OPT_TARGET_LL_ADDR
 392                                    && opt_len == 8) {
 393                                 if (unlikely(!is_zero_ether_addr(key->ipv6.nd.tll)))
 394                                         goto invalid;
 395                                 memcpy(key->ipv6.nd.tll,
 396                                     &nd->opt[offset+sizeof(*nd_opt)], ETH_ALEN);
 397                         }
 398
 399                         icmp_len -= opt_len;
 400                         offset += opt_len;
 401                 }
 402         }
 403
 404         return 0;
 405
 406 invalid:
 407         memset(&key->ipv6.nd.target, 0, sizeof(key->ipv6.nd.target));
 408         memset(key->ipv6.nd.sll, 0, sizeof(key->ipv6.nd.sll));
 409         memset(key->ipv6.nd.tll, 0, sizeof(key->ipv6.nd.tll));
 410
 411         return 0;
 412 }
 413
 414 /**
 415  * ovs_flow_extract - extracts a flow key from an Ethernet frame.
 416  * @skb: sk_buff that contains the frame, with skb->data pointing to the
 417  * Ethernet header
 418  * @in_port: port number on which @skb was received.
 419  * @key: output flow key
 420  *
 421  * The caller must ensure that skb->len >= ETH_HLEN.
 422  *
 423  * Returns 0 if successful, otherwise a negative errno value.
 424  *
 425  * Initializes @skb header pointers as follows:
 426  *
 427  *    - skb->mac_header: the Ethernet header.
 428  *
 429  *    - skb->network_header: just past the Ethernet header, or just past the
 430  *      VLAN header, to the first byte of the Ethernet payload.
 431  *
 432  *    - skb->transport_header: If key->eth.type is ETH_P_IP or ETH_P_IPV6
 433  *      on output, then just past the IP header, if one is present and
 434  *      of a correct length, otherwise the same as skb->network_header.
 435  *      For other key->eth.type values it is left untouched.
 436  */
 437 int ovs_flow_extract(struct sk_buff *skb, u16 in_port, struct sw_flow_key *key)
 438 {
 439         int error;
 440         struct ethhdr *eth;
 441
 442         memset(key, 0, sizeof(*key));
 443
 444         key->phy.priority = skb->priority;
 445         if (OVS_CB(skb)->tun_key)
 446                 memcpy(&key->tun_key, OVS_CB(skb)->tun_key, sizeof(key->tun_key));
 447         key->phy.in_port = in_port;
 448         key->phy.skb_mark = skb->mark;
 449
 450         skb_reset_mac_header(skb);
 451
 452         /* Link layer.  We are guaranteed to have at least the 14 byte Ethernet
 453          * header in the linear data area.
 454          */
 455         eth = eth_hdr(skb);
 456         memcpy(key->eth.src, eth->h_source, ETH_ALEN);
 457         memcpy(key->eth.dst, eth->h_dest, ETH_ALEN);
 458
 459         __skb_pull(skb, 2 * ETH_ALEN);
 460         /* We are going to push all headers that we pull, so no need to
 461          * update skb->csum here. */
 462
 463         if (vlan_tx_tag_present(skb))
 464                 key->eth.tci = htons(vlan_get_tci(skb));
 465         else if (eth->h_proto == htons(ETH_P_8021Q))
 466                 if (unlikely(parse_vlan(skb, key)))
 467                         return -ENOMEM;
 468
 469         key->eth.type = parse_ethertype(skb);
 470         if (unlikely(key->eth.type == htons(0)))
 471                 return -ENOMEM;
 472
 473         skb_reset_network_header(skb);
 474         __skb_push(skb, skb->data - skb_mac_header(skb));
 475
 476         /* Network layer. */
 477         if (key->eth.type == htons(ETH_P_IP)) {
 478                 struct iphdr *nh;
 479                 __be16 offset;
 480
 481                 error = check_iphdr(skb);
 482                 if (unlikely(error)) {
 483                         if (error == -EINVAL) {
 484                                 skb->transport_header = skb->network_header;
 485                                 error = 0;
 486                         }
 487                         return error;
 488                 }
 489
 490                 nh = ip_hdr(skb);
 491                 key->ipv4.addr.src = nh->saddr;
 492                 key->ipv4.addr.dst = nh->daddr;
 493
 494                 key->ip.proto = nh->protocol;
 495                 key->ip.tos = nh->tos;
 496                 key->ip.ttl = nh->ttl;
 497
 498                 offset = nh->frag_off & htons(IP_OFFSET);
 499                 if (offset) {
 500                         key->ip.frag = OVS_FRAG_TYPE_LATER;
 501                         return 0;
 502                 }
 503                 if (nh->frag_off & htons(IP_MF) ||
 504                          skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 505                         key->ip.frag = OVS_FRAG_TYPE_FIRST;
 506
 507                 /* Transport layer. */
 508                 if (key->ip.proto == IPPROTO_TCP) {
 509                         if (tcphdr_ok(skb)) {
 510                                 struct tcphdr *tcp = tcp_hdr(skb);
 511                                 key->ipv4.tp.src = tcp->source;
 512                                 key->ipv4.tp.dst = tcp->dest;
 513                                 key->ipv4.tp.flags = TCP_FLAGS_BE16(tcp);
 514                         }
 515                 } else if (key->ip.proto == IPPROTO_UDP) {
 516                         if (udphdr_ok(skb)) {
 517                                 struct udphdr *udp = udp_hdr(skb);
 518                                 key->ipv4.tp.src = udp->source;
 519                                 key->ipv4.tp.dst = udp->dest;
 520                         }
 521                 } else if (key->ip.proto == IPPROTO_SCTP) {
 522                         if (sctphdr_ok(skb)) {
 523                                 struct sctphdr *sctp = sctp_hdr(skb);
 524                                 key->ipv4.tp.src = sctp->source;
 525                                 key->ipv4.tp.dst = sctp->dest;
 526                         }
 527                 } else if (key->ip.proto == IPPROTO_ICMP) {
 528                         if (icmphdr_ok(skb)) {
 529                                 struct icmphdr *icmp = icmp_hdr(skb);
 530                                 /* The ICMP type and code fields use the 16-bit
 531                                  * transport port fields, so we need to store
 532                                  * them in 16-bit network byte order. */
 533                                 key->ipv4.tp.src = htons(icmp->type);
 534                                 key->ipv4.tp.dst = htons(icmp->code);
 535                         }
 536                 }
 537
 538         } else if ((key->eth.type == htons(ETH_P_ARP) ||
 539                    key->eth.type == htons(ETH_P_RARP)) && arphdr_ok(skb)) {
 540                 struct arp_eth_header *arp;
 541
 542                 arp = (struct arp_eth_header *)skb_network_header(skb);
 543
 544                 if (arp->ar_hrd == htons(ARPHRD_ETHER)
 545                                 && arp->ar_pro == htons(ETH_P_IP)
 546                                 && arp->ar_hln == ETH_ALEN
 547                                 && arp->ar_pln == 4) {
 548
 549                         /* We only match on the lower 8 bits of the opcode. */
 550                         if (ntohs(arp->ar_op) <= 0xff)
 551                                 key->ip.proto = ntohs(arp->ar_op);
 552                         memcpy(&key->ipv4.addr.src, arp->ar_sip, sizeof(key->ipv4.addr.src));
 553                         memcpy(&key->ipv4.addr.dst, arp->ar_tip, sizeof(key->ipv4.addr.dst));
 554                         memcpy(key->ipv4.arp.sha, arp->ar_sha, ETH_ALEN);
 555                         memcpy(key->ipv4.arp.tha, arp->ar_tha, ETH_ALEN);
 556                 }
 557         } else if (key->eth.type == htons(ETH_P_IPV6)) {
 558                 int nh_len;             /* IPv6 Header + Extensions */
 559
 560                 nh_len = parse_ipv6hdr(skb, key);
 561                 if (unlikely(nh_len < 0)) {
 562                         if (nh_len == -EINVAL) {
 563                                 skb->transport_header = skb->network_header;
 564                                 error = 0;
 565                         } else {
 566                                 error = nh_len;
 567                         }
 568                         return error;
 569                 }
 570
 571                 if (key->ip.frag == OVS_FRAG_TYPE_LATER)
 572                         return 0;
 573                 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
 574                         key->ip.frag = OVS_FRAG_TYPE_FIRST;
 575
 576                 /* Transport layer. */
 577                 if (key->ip.proto == NEXTHDR_TCP) {
 578                         if (tcphdr_ok(skb)) {
 579                                 struct tcphdr *tcp = tcp_hdr(skb);
 580                                 key->ipv6.tp.src = tcp->source;
 581                                 key->ipv6.tp.dst = tcp->dest;
 582                                 key->ipv6.tp.flags = TCP_FLAGS_BE16(tcp);
 583                         }
 584                 } else if (key->ip.proto == NEXTHDR_UDP) {
 585                         if (udphdr_ok(skb)) {
 586                                 struct udphdr *udp = udp_hdr(skb);
 587                                 key->ipv6.tp.src = udp->source;
 588                                 key->ipv6.tp.dst = udp->dest;
 589                         }
 590                 } else if (key->ip.proto == NEXTHDR_SCTP) {
 591                         if (sctphdr_ok(skb)) {
 592                                 struct sctphdr *sctp = sctp_hdr(skb);
 593                                 key->ipv6.tp.src = sctp->source;
 594                                 key->ipv6.tp.dst = sctp->dest;
 595                         }
 596                 } else if (key->ip.proto == NEXTHDR_ICMP) {
 597                         if (icmp6hdr_ok(skb)) {
 598                                 error = parse_icmpv6(skb, key, nh_len);
 599                                 if (error)
 600                                         return error;
 601                         }
 602                 }
 603         }
 604
 605         return 0;
 606 }