git.oblomov.eu Git - linux-2.6/blob - net/ipv6/datagram.c

   1 /*
   2  *      common UDP/RAW code
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      $Id: datagram.c,v 1.24 2002/02/01 22:01:04 davem Exp $
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/errno.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/sched.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/socket.h>
  22 #include <linux/sockios.h>
  23 #include <linux/in6.h>
  24 #include <linux/ipv6.h>
  25 #include <linux/route.h>
  26
  27 #include <net/ipv6.h>
  28 #include <net/ndisc.h>
  29 #include <net/addrconf.h>
  30 #include <net/transp_v6.h>
  31 #include <net/ip6_route.h>
  32 #include <net/tcp_states.h>
  33
  34 #include <linux/errqueue.h>
  35 #include <asm/uaccess.h>
  36
  37 int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  38 {
  39         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
  40         struct inet_sock        *inet = inet_sk(sk);
  41         struct ipv6_pinfo       *np = inet6_sk(sk);
  42         struct in6_addr         *daddr, *final_p = NULL, final;
  43         struct dst_entry        *dst;
  44         struct flowi            fl;
  45         struct ip6_flowlabel    *flowlabel = NULL;
  46         int                     addr_type;
  47         int                     err;
  48
  49         if (usin->sin6_family == AF_INET) {
  50                 if (__ipv6_only_sock(sk))
  51                         return -EAFNOSUPPORT;
  52                 err = ip4_datagram_connect(sk, uaddr, addr_len);
  53                 goto ipv4_connected;
  54         }
  55
  56         if (addr_len < SIN6_LEN_RFC2133)
  57                 return -EINVAL;
  58
  59         if (usin->sin6_family != AF_INET6)
  60                 return -EAFNOSUPPORT;
  61
  62         memset(&fl, 0, sizeof(fl));
  63         if (np->sndflow) {
  64                 fl.fl6_flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
  65                 if (fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
  66                         flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
  67                         if (flowlabel == NULL)
  68                                 return -EINVAL;
  69                         ipv6_addr_copy(&usin->sin6_addr, &flowlabel->dst);
  70                 }
  71         }
  72
  73         addr_type = ipv6_addr_type(&usin->sin6_addr);
  74
  75         if (addr_type == IPV6_ADDR_ANY) {
  76                 /*
  77                  *      connect to self
  78                  */
  79                 usin->sin6_addr.s6_addr[15] = 0x01;
  80         }
  81
  82         daddr = &usin->sin6_addr;
  83
  84         if (addr_type == IPV6_ADDR_MAPPED) {
  85                 struct sockaddr_in sin;
  86
  87                 if (__ipv6_only_sock(sk)) {
  88                         err = -ENETUNREACH;
  89                         goto out;
  90                 }
  91                 sin.sin_family = AF_INET;
  92                 sin.sin_addr.s_addr = daddr->s6_addr32[3];
  93                 sin.sin_port = usin->sin6_port;
  94
  95                 err = ip4_datagram_connect(sk,
  96                                            (struct sockaddr*) &sin,
  97                                            sizeof(sin));
  98
  99 ipv4_connected:
 100                 if (err)
 101                         goto out;
 102
 103                 ipv6_addr_set(&np->daddr, 0, 0, htonl(0x0000ffff), inet->daddr);
 104
 105                 if (ipv6_addr_any(&np->saddr)) {
 106                         ipv6_addr_set(&np->saddr, 0, 0, htonl(0x0000ffff),
 107                                       inet->saddr);
 108                 }
 109
 110                 if (ipv6_addr_any(&np->rcv_saddr)) {
 111                         ipv6_addr_set(&np->rcv_saddr, 0, 0, htonl(0x0000ffff),
 112                                       inet->rcv_saddr);
 113                 }
 114                 goto out;
 115         }
 116
 117         if (addr_type&IPV6_ADDR_LINKLOCAL) {
 118                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 119                     usin->sin6_scope_id) {
 120                         if (sk->sk_bound_dev_if &&
 121                             sk->sk_bound_dev_if != usin->sin6_scope_id) {
 122                                 err = -EINVAL;
 123                                 goto out;
 124                         }
 125                         sk->sk_bound_dev_if = usin->sin6_scope_id;
 126                         if (!sk->sk_bound_dev_if &&
 127                             (addr_type & IPV6_ADDR_MULTICAST))
 128                                 fl.oif = np->mcast_oif;
 129                 }
 130
 131                 /* Connect to link-local address requires an interface */
 132                 if (!sk->sk_bound_dev_if) {
 133                         err = -EINVAL;
 134                         goto out;
 135                 }
 136         }
 137
 138         ipv6_addr_copy(&np->daddr, daddr);
 139         np->flow_label = fl.fl6_flowlabel;
 140
 141         inet->dport = usin->sin6_port;
 142
 143         /*
 144          *      Check for a route to destination an obtain the
 145          *      destination cache for it.
 146          */
 147
 148         fl.proto = sk->sk_protocol;
 149         ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
 150         ipv6_addr_copy(&fl.fl6_src, &np->saddr);
 151         fl.oif = sk->sk_bound_dev_if;
 152         fl.fl_ip_dport = inet->dport;
 153         fl.fl_ip_sport = inet->sport;
 154
 155         if (!fl.oif && (addr_type&IPV6_ADDR_MULTICAST))
 156                 fl.oif = np->mcast_oif;
 157
 158         if (flowlabel) {
 159                 if (flowlabel->opt && flowlabel->opt->srcrt) {
 160                         struct rt0_hdr *rt0 = (struct rt0_hdr *) flowlabel->opt->srcrt;
 161                         ipv6_addr_copy(&final, &fl.fl6_dst);
 162                         ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
 163                         final_p = &final;
 164                 }
 165         } else if (np->opt && np->opt->srcrt) {
 166                 struct rt0_hdr *rt0 = (struct rt0_hdr *)np->opt->srcrt;
 167                 ipv6_addr_copy(&final, &fl.fl6_dst);
 168                 ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
 169                 final_p = &final;
 170         }
 171
 172         err = ip6_dst_lookup(sk, &dst, &fl);
 173         if (err)
 174                 goto out;
 175         if (final_p)
 176                 ipv6_addr_copy(&fl.fl6_dst, final_p);
 177
 178         if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0) {
 179                 dst_release(dst);
 180                 goto out;
 181         }
 182
 183         /* source address lookup done in ip6_dst_lookup */
 184
 185         if (ipv6_addr_any(&np->saddr))
 186                 ipv6_addr_copy(&np->saddr, &fl.fl6_src);
 187
 188         if (ipv6_addr_any(&np->rcv_saddr)) {
 189                 ipv6_addr_copy(&np->rcv_saddr, &fl.fl6_src);
 190                 inet->rcv_saddr = LOOPBACK4_IPV6;
 191         }
 192
 193         ip6_dst_store(sk, dst,
 194                       ipv6_addr_equal(&fl.fl6_dst, &np->daddr) ?
 195                       &np->daddr : NULL);
 196
 197         sk->sk_state = TCP_ESTABLISHED;
 198 out:
 199         fl6_sock_release(flowlabel);
 200         return err;
 201 }
 202
 203 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
 204                      u16 port, u32 info, u8 *payload)
 205 {
 206         struct ipv6_pinfo *np  = inet6_sk(sk);
 207         struct icmp6hdr *icmph = (struct icmp6hdr *)skb->h.raw;
 208         struct sock_exterr_skb *serr;
 209
 210         if (!np->recverr)
 211                 return;
 212
 213         skb = skb_clone(skb, GFP_ATOMIC);
 214         if (!skb)
 215                 return;
 216
 217         serr = SKB_EXT_ERR(skb);
 218         serr->ee.ee_errno = err;
 219         serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6;
 220         serr->ee.ee_type = icmph->icmp6_type;
 221         serr->ee.ee_code = icmph->icmp6_code;
 222         serr->ee.ee_pad = 0;
 223         serr->ee.ee_info = info;
 224         serr->ee.ee_data = 0;
 225         serr->addr_offset = (u8*)&(((struct ipv6hdr*)(icmph+1))->daddr) - skb->nh.raw;
 226         serr->port = port;
 227
 228         skb->h.raw = payload;
 229         __skb_pull(skb, payload - skb->data);
 230
 231         if (sock_queue_err_skb(sk, skb))
 232                 kfree_skb(skb);
 233 }
 234
 235 void ipv6_local_error(struct sock *sk, int err, struct flowi *fl, u32 info)
 236 {
 237         struct ipv6_pinfo *np = inet6_sk(sk);
 238         struct sock_exterr_skb *serr;
 239         struct ipv6hdr *iph;
 240         struct sk_buff *skb;
 241
 242         if (!np->recverr)
 243                 return;
 244
 245         skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
 246         if (!skb)
 247                 return;
 248
 249         iph = (struct ipv6hdr*)skb_put(skb, sizeof(struct ipv6hdr));
 250         skb->nh.ipv6h = iph;
 251         ipv6_addr_copy(&iph->daddr, &fl->fl6_dst);
 252
 253         serr = SKB_EXT_ERR(skb);
 254         serr->ee.ee_errno = err;
 255         serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
 256         serr->ee.ee_type = 0;
 257         serr->ee.ee_code = 0;
 258         serr->ee.ee_pad = 0;
 259         serr->ee.ee_info = info;
 260         serr->ee.ee_data = 0;
 261         serr->addr_offset = (u8*)&iph->daddr - skb->nh.raw;
 262         serr->port = fl->fl_ip_dport;
 263
 264         skb->h.raw = skb->tail;
 265         __skb_pull(skb, skb->tail - skb->data);
 266
 267         if (sock_queue_err_skb(sk, skb))
 268                 kfree_skb(skb);
 269 }
 270
 271 /*
 272  *      Handle MSG_ERRQUEUE
 273  */
 274 int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
 275 {
 276         struct ipv6_pinfo *np = inet6_sk(sk);
 277         struct sock_exterr_skb *serr;
 278         struct sk_buff *skb, *skb2;
 279         struct sockaddr_in6 *sin;
 280         struct {
 281                 struct sock_extended_err ee;
 282                 struct sockaddr_in6      offender;
 283         } errhdr;
 284         int err;
 285         int copied;
 286
 287         err = -EAGAIN;
 288         skb = skb_dequeue(&sk->sk_error_queue);
 289         if (skb == NULL)
 290                 goto out;
 291
 292         copied = skb->len;
 293         if (copied > len) {
 294                 msg->msg_flags |= MSG_TRUNC;
 295                 copied = len;
 296         }
 297         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 298         if (err)
 299                 goto out_free_skb;
 300
 301         sock_recv_timestamp(msg, sk, skb);
 302
 303         serr = SKB_EXT_ERR(skb);
 304
 305         sin = (struct sockaddr_in6 *)msg->msg_name;
 306         if (sin) {
 307                 sin->sin6_family = AF_INET6;
 308                 sin->sin6_flowinfo = 0;
 309                 sin->sin6_port = serr->port;
 310                 sin->sin6_scope_id = 0;
 311                 if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) {
 312                         ipv6_addr_copy(&sin->sin6_addr,
 313                           (struct in6_addr *)(skb->nh.raw + serr->addr_offset));
 314                         if (np->sndflow)
 315                                 sin->sin6_flowinfo = *(u32*)(skb->nh.raw + serr->addr_offset - 24) & IPV6_FLOWINFO_MASK;
 316                         if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 317                                 sin->sin6_scope_id = IP6CB(skb)->iif;
 318                 } else {
 319                         ipv6_addr_set(&sin->sin6_addr, 0, 0,
 320                                       htonl(0xffff),
 321                                       *(u32*)(skb->nh.raw + serr->addr_offset));
 322                 }
 323         }
 324
 325         memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
 326         sin = &errhdr.offender;
 327         sin->sin6_family = AF_UNSPEC;
 328         if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {
 329                 sin->sin6_family = AF_INET6;
 330                 sin->sin6_flowinfo = 0;
 331                 sin->sin6_scope_id = 0;
 332                 if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) {
 333                         ipv6_addr_copy(&sin->sin6_addr, &skb->nh.ipv6h->saddr);
 334                         if (np->rxopt.all)
 335                                 datagram_recv_ctl(sk, msg, skb);
 336                         if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 337                                 sin->sin6_scope_id = IP6CB(skb)->iif;
 338                 } else {
 339                         struct inet_sock *inet = inet_sk(sk);
 340
 341                         ipv6_addr_set(&sin->sin6_addr, 0, 0,
 342                                       htonl(0xffff),
 343                                       skb->nh.iph->saddr);
 344                         if (inet->cmsg_flags)
 345                                 ip_cmsg_recv(msg, skb);
 346                 }
 347         }
 348
 349         put_cmsg(msg, SOL_IPV6, IPV6_RECVERR, sizeof(errhdr), &errhdr);
 350
 351         /* Now we could try to dump offended packet options */
 352
 353         msg->msg_flags |= MSG_ERRQUEUE;
 354         err = copied;
 355
 356         /* Reset and regenerate socket error */
 357         spin_lock_bh(&sk->sk_error_queue.lock);
 358         sk->sk_err = 0;
 359         if ((skb2 = skb_peek(&sk->sk_error_queue)) != NULL) {
 360                 sk->sk_err = SKB_EXT_ERR(skb2)->ee.ee_errno;
 361                 spin_unlock_bh(&sk->sk_error_queue.lock);
 362                 sk->sk_error_report(sk);
 363         } else {
 364                 spin_unlock_bh(&sk->sk_error_queue.lock);
 365         }
 366
 367 out_free_skb:
 368         kfree_skb(skb);
 369 out:
 370         return err;
 371 }
 372
 373
 374
 375 int datagram_recv_ctl(struct sock *sk, struct msghdr *msg, struct sk_buff *skb)
 376 {
 377         struct ipv6_pinfo *np = inet6_sk(sk);
 378         struct inet6_skb_parm *opt = IP6CB(skb);
 379
 380         if (np->rxopt.bits.rxinfo) {
 381                 struct in6_pktinfo src_info;
 382
 383                 src_info.ipi6_ifindex = opt->iif;
 384                 ipv6_addr_copy(&src_info.ipi6_addr, &skb->nh.ipv6h->daddr);
 385                 put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO, sizeof(src_info), &src_info);
 386         }
 387
 388         if (np->rxopt.bits.rxhlim) {
 389                 int hlim = skb->nh.ipv6h->hop_limit;
 390                 put_cmsg(msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
 391         }
 392
 393         if (np->rxopt.bits.rxflow && (*(u32*)skb->nh.raw & IPV6_FLOWINFO_MASK)) {
 394                 u32 flowinfo = *(u32*)skb->nh.raw & IPV6_FLOWINFO_MASK;
 395                 put_cmsg(msg, SOL_IPV6, IPV6_FLOWINFO, sizeof(flowinfo), &flowinfo);
 396         }
 397         if (np->rxopt.bits.hopopts && opt->hop) {
 398                 u8 *ptr = skb->nh.raw + opt->hop;
 399                 put_cmsg(msg, SOL_IPV6, IPV6_HOPOPTS, (ptr[1]+1)<<3, ptr);
 400         }
 401         if (np->rxopt.bits.dstopts && opt->dst0) {
 402                 u8 *ptr = skb->nh.raw + opt->dst0;
 403                 put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, (ptr[1]+1)<<3, ptr);
 404         }
 405         if (np->rxopt.bits.srcrt && opt->srcrt) {
 406                 struct ipv6_rt_hdr *rthdr = (struct ipv6_rt_hdr *)(skb->nh.raw + opt->srcrt);
 407                 put_cmsg(msg, SOL_IPV6, IPV6_RTHDR, (rthdr->hdrlen+1) << 3, rthdr);
 408         }
 409         if (np->rxopt.bits.dstopts && opt->dst1) {
 410                 u8 *ptr = skb->nh.raw + opt->dst1;
 411                 put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, (ptr[1]+1)<<3, ptr);
 412         }
 413         return 0;
 414 }
 415
 416 int datagram_send_ctl(struct msghdr *msg, struct flowi *fl,
 417                       struct ipv6_txoptions *opt,
 418                       int *hlimit)
 419 {
 420         struct in6_pktinfo *src_info;
 421         struct cmsghdr *cmsg;
 422         struct ipv6_rt_hdr *rthdr;
 423         struct ipv6_opt_hdr *hdr;
 424         int len;
 425         int err = 0;
 426
 427         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
 428                 int addr_type;
 429                 struct net_device *dev = NULL;
 430
 431                 if (!CMSG_OK(msg, cmsg)) {
 432                         err = -EINVAL;
 433                         goto exit_f;
 434                 }
 435
 436                 if (cmsg->cmsg_level != SOL_IPV6)
 437                         continue;
 438
 439                 switch (cmsg->cmsg_type) {
 440                 case IPV6_PKTINFO:
 441                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct in6_pktinfo))) {
 442                                 err = -EINVAL;
 443                                 goto exit_f;
 444                         }
 445
 446                         src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
 447
 448                         if (src_info->ipi6_ifindex) {
 449                                 if (fl->oif && src_info->ipi6_ifindex != fl->oif)
 450                                         return -EINVAL;
 451                                 fl->oif = src_info->ipi6_ifindex;
 452                         }
 453
 454                         addr_type = ipv6_addr_type(&src_info->ipi6_addr);
 455
 456                         if (addr_type == IPV6_ADDR_ANY)
 457                                 break;
 458
 459                         if (addr_type & IPV6_ADDR_LINKLOCAL) {
 460                                 if (!src_info->ipi6_ifindex)
 461                                         return -EINVAL;
 462                                 else {
 463                                         dev = dev_get_by_index(src_info->ipi6_ifindex);
 464                                         if (!dev)
 465                                                 return -ENODEV;
 466                                 }
 467                         }
 468                         if (!ipv6_chk_addr(&src_info->ipi6_addr, dev, 0)) {
 469                                 if (dev)
 470                                         dev_put(dev);
 471                                 err = -EINVAL;
 472                                 goto exit_f;
 473                         }
 474                         if (dev)
 475                                 dev_put(dev);
 476
 477                         ipv6_addr_copy(&fl->fl6_src, &src_info->ipi6_addr);
 478                         break;
 479
 480                 case IPV6_FLOWINFO:
 481                         if (cmsg->cmsg_len < CMSG_LEN(4)) {
 482                                 err = -EINVAL;
 483                                 goto exit_f;
 484                         }
 485
 486                         if (fl->fl6_flowlabel&IPV6_FLOWINFO_MASK) {
 487                                 if ((fl->fl6_flowlabel^*(u32 *)CMSG_DATA(cmsg))&~IPV6_FLOWINFO_MASK) {
 488                                         err = -EINVAL;
 489                                         goto exit_f;
 490                                 }
 491                         }
 492                         fl->fl6_flowlabel = IPV6_FLOWINFO_MASK & *(u32 *)CMSG_DATA(cmsg);
 493                         break;
 494
 495                 case IPV6_HOPOPTS:
 496                         if (opt->hopopt || cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
 497                                 err = -EINVAL;
 498                                 goto exit_f;
 499                         }
 500
 501                         hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
 502                         len = ((hdr->hdrlen + 1) << 3);
 503                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 504                                 err = -EINVAL;
 505                                 goto exit_f;
 506                         }
 507                         if (!capable(CAP_NET_RAW)) {
 508                                 err = -EPERM;
 509                                 goto exit_f;
 510                         }
 511                         opt->opt_nflen += len;
 512                         opt->hopopt = hdr;
 513                         break;
 514
 515                 case IPV6_DSTOPTS:
 516                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
 517                                 err = -EINVAL;
 518                                 goto exit_f;
 519                         }
 520
 521                         hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
 522                         len = ((hdr->hdrlen + 1) << 3);
 523                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 524                                 err = -EINVAL;
 525                                 goto exit_f;
 526                         }
 527                         if (!capable(CAP_NET_RAW)) {
 528                                 err = -EPERM;
 529                                 goto exit_f;
 530                         }
 531                         if (opt->dst1opt) {
 532                                 err = -EINVAL;
 533                                 goto exit_f;
 534                         }
 535                         opt->opt_flen += len;
 536                         opt->dst1opt = hdr;
 537                         break;
 538
 539                 case IPV6_RTHDR:
 540                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_rt_hdr))) {
 541                                 err = -EINVAL;
 542                                 goto exit_f;
 543                         }
 544
 545                         rthdr = (struct ipv6_rt_hdr *)CMSG_DATA(cmsg);
 546
 547                         /*
 548                          *      TYPE 0
 549                          */
 550                         if (rthdr->type) {
 551                                 err = -EINVAL;
 552                                 goto exit_f;
 553                         }
 554
 555                         len = ((rthdr->hdrlen + 1) << 3);
 556
 557                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 558                                 err = -EINVAL;
 559                                 goto exit_f;
 560                         }
 561
 562                         /* segments left must also match */
 563                         if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
 564                                 err = -EINVAL;
 565                                 goto exit_f;
 566                         }
 567
 568                         opt->opt_nflen += len;
 569                         opt->srcrt = rthdr;
 570
 571                         if (opt->dst1opt) {
 572                                 int dsthdrlen = ((opt->dst1opt->hdrlen+1)<<3);
 573
 574                                 opt->opt_nflen += dsthdrlen;
 575                                 opt->dst0opt = opt->dst1opt;
 576                                 opt->dst1opt = NULL;
 577                                 opt->opt_flen -= dsthdrlen;
 578                         }
 579
 580                         break;
 581
 582                 case IPV6_HOPLIMIT:
 583                         if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
 584                                 err = -EINVAL;
 585                                 goto exit_f;
 586                         }
 587
 588                         *hlimit = *(int *)CMSG_DATA(cmsg);
 589                         break;
 590
 591                 default:
 592                         LIMIT_NETDEBUG(KERN_DEBUG "invalid cmsg type: %d\n",
 593                                        cmsg->cmsg_type);
 594                         err = -EINVAL;
 595                         break;
 596                 };
 597         }
 598
 599 exit_f:
 600         return err;
 601 }