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
  33 #include <linux/errqueue.h>
  34 #include <asm/uaccess.h>
  35
  36 int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  37 {
  38         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
  39         struct inet_opt         *inet = inet_sk(sk);
  40         struct ipv6_pinfo       *np = inet6_sk(sk);
  41         struct in6_addr         *daddr, *final_p = NULL, final;
  42         struct dst_entry        *dst;
  43         struct flowi            fl;
  44         struct ip6_flowlabel    *flowlabel = NULL;
  45         int                     addr_type;
  46         int                     err;
  47
  48         if (usin->sin6_family == AF_INET) {
  49                 if (__ipv6_only_sock(sk))
  50                         return -EAFNOSUPPORT;
  51                 err = ip4_datagram_connect(sk, uaddr, addr_len);
  52                 goto ipv4_connected;
  53         }
  54
  55         if (addr_len < SIN6_LEN_RFC2133)
  56                 return -EINVAL;
  57
  58         if (usin->sin6_family != AF_INET6)
  59                 return -EAFNOSUPPORT;
  60
  61         memset(&fl, 0, sizeof(fl));
  62         if (np->sndflow) {
  63                 fl.fl6_flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
  64                 if (fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
  65                         flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
  66                         if (flowlabel == NULL)
  67                                 return -EINVAL;
  68                         ipv6_addr_copy(&usin->sin6_addr, &flowlabel->dst);
  69                 }
  70         }
  71
  72         addr_type = ipv6_addr_type(&usin->sin6_addr);
  73
  74         if (addr_type == IPV6_ADDR_ANY) {
  75                 /*
  76                  *      connect to self
  77                  */
  78                 usin->sin6_addr.s6_addr[15] = 0x01;
  79         }
  80
  81         daddr = &usin->sin6_addr;
  82
  83         if (addr_type == IPV6_ADDR_MAPPED) {
  84                 struct sockaddr_in sin;
  85
  86                 if (__ipv6_only_sock(sk)) {
  87                         err = -ENETUNREACH;
  88                         goto out;
  89                 }
  90                 sin.sin_family = AF_INET;
  91                 sin.sin_addr.s_addr = daddr->s6_addr32[3];
  92                 sin.sin_port = usin->sin6_port;
  93
  94                 err = ip4_datagram_connect(sk,
  95                                            (struct sockaddr*) &sin,
  96                                            sizeof(sin));
  97
  98 ipv4_connected:
  99                 if (err)
 100                         goto out;
 101
 102                 ipv6_addr_set(&np->daddr, 0, 0, htonl(0x0000ffff), inet->daddr);
 103
 104                 if (ipv6_addr_any(&np->saddr)) {
 105                         ipv6_addr_set(&np->saddr, 0, 0, htonl(0x0000ffff),
 106                                       inet->saddr);
 107                 }
 108
 109                 if (ipv6_addr_any(&np->rcv_saddr)) {
 110                         ipv6_addr_set(&np->rcv_saddr, 0, 0, htonl(0x0000ffff),
 111                                       inet->rcv_saddr);
 112                 }
 113                 goto out;
 114         }
 115
 116         if (addr_type&IPV6_ADDR_LINKLOCAL) {
 117                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 118                     usin->sin6_scope_id) {
 119                         if (sk->sk_bound_dev_if &&
 120                             sk->sk_bound_dev_if != usin->sin6_scope_id) {
 121                                 err = -EINVAL;
 122                                 goto out;
 123                         }
 124                         sk->sk_bound_dev_if = usin->sin6_scope_id;
 125                         if (!sk->sk_bound_dev_if &&
 126                             (addr_type & IPV6_ADDR_MULTICAST))
 127                                 fl.oif = np->mcast_oif;
 128                 }
 129
 130                 /* Connect to link-local address requires an interface */
 131                 if (!sk->sk_bound_dev_if) {
 132                         err = -EINVAL;
 133                         goto out;
 134                 }
 135         }
 136
 137         ipv6_addr_copy(&np->daddr, daddr);
 138         np->flow_label = fl.fl6_flowlabel;
 139
 140         inet->dport = usin->sin6_port;
 141
 142         /*
 143          *      Check for a route to destination an obtain the
 144          *      destination cache for it.
 145          */
 146
 147         fl.proto = sk->sk_protocol;
 148         ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
 149         ipv6_addr_copy(&fl.fl6_src, &np->saddr);
 150         fl.oif = sk->sk_bound_dev_if;
 151         fl.fl_ip_dport = inet->dport;
 152         fl.fl_ip_sport = inet->sport;
 153
 154         if (!fl.oif && (addr_type&IPV6_ADDR_MULTICAST))
 155                 fl.oif = np->mcast_oif;
 156
 157         if (flowlabel) {
 158                 if (flowlabel->opt && flowlabel->opt->srcrt) {
 159                         struct rt0_hdr *rt0 = (struct rt0_hdr *) flowlabel->opt->srcrt;
 160                         ipv6_addr_copy(&final, &fl.fl6_dst);
 161                         ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
 162                         final_p = &final;
 163                 }
 164         } else if (np->opt && np->opt->srcrt) {
 165                 struct rt0_hdr *rt0 = (struct rt0_hdr *)np->opt->srcrt;
 166                 ipv6_addr_copy(&final, &fl.fl6_dst);
 167                 ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
 168                 final_p = &final;
 169         }
 170
 171         err = ip6_dst_lookup(sk, &dst, &fl);
 172         if (err)
 173                 goto out;
 174         if (final_p)
 175                 ipv6_addr_copy(&fl.fl6_dst, final_p);
 176
 177         if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0) {
 178                 dst_release(dst);
 179                 goto out;
 180         }
 181
 182         /* source address lookup done in ip6_dst_lookup */
 183
 184         if (ipv6_addr_any(&np->saddr))
 185                 ipv6_addr_copy(&np->saddr, &fl.fl6_src);
 186
 187         if (ipv6_addr_any(&np->rcv_saddr)) {
 188                 ipv6_addr_copy(&np->rcv_saddr, &fl.fl6_src);
 189                 inet->rcv_saddr = LOOPBACK4_IPV6;
 190         }
 191
 192         ip6_dst_store(sk, dst,
 193                       !ipv6_addr_cmp(&fl.fl6_dst, &np->daddr) ?
 194                       &np->daddr : NULL);
 195
 196         sk->sk_state = TCP_ESTABLISHED;
 197 out:
 198         fl6_sock_release(flowlabel);
 199         return err;
 200 }
 201
 202 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
 203                      u16 port, u32 info, u8 *payload)
 204 {
 205         struct ipv6_pinfo *np  = inet6_sk(sk);
 206         struct icmp6hdr *icmph = (struct icmp6hdr *)skb->h.raw;
 207         struct sock_exterr_skb *serr;
 208
 209         if (!np->recverr)
 210                 return;
 211
 212         skb = skb_clone(skb, GFP_ATOMIC);
 213         if (!skb)
 214                 return;
 215
 216         serr = SKB_EXT_ERR(skb);
 217         serr->ee.ee_errno = err;
 218         serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6;
 219         serr->ee.ee_type = icmph->icmp6_type;
 220         serr->ee.ee_code = icmph->icmp6_code;
 221         serr->ee.ee_pad = 0;
 222         serr->ee.ee_info = info;
 223         serr->ee.ee_data = 0;
 224         serr->addr_offset = (u8*)&(((struct ipv6hdr*)(icmph+1))->daddr) - skb->nh.raw;
 225         serr->port = port;
 226
 227         skb->h.raw = payload;
 228         __skb_pull(skb, payload - skb->data);
 229
 230         if (sock_queue_err_skb(sk, skb))
 231                 kfree_skb(skb);
 232 }
 233
 234 void ipv6_local_error(struct sock *sk, int err, struct flowi *fl, u32 info)
 235 {
 236         struct ipv6_pinfo *np = inet6_sk(sk);
 237         struct sock_exterr_skb *serr;
 238         struct ipv6hdr *iph;
 239         struct sk_buff *skb;
 240
 241         if (!np->recverr)
 242                 return;
 243
 244         skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
 245         if (!skb)
 246                 return;
 247
 248         iph = (struct ipv6hdr*)skb_put(skb, sizeof(struct ipv6hdr));
 249         skb->nh.ipv6h = iph;
 250         ipv6_addr_copy(&iph->daddr, &fl->fl6_dst);
 251
 252         serr = SKB_EXT_ERR(skb);
 253         serr->ee.ee_errno = err;
 254         serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
 255         serr->ee.ee_type = 0;
 256         serr->ee.ee_code = 0;
 257         serr->ee.ee_pad = 0;
 258         serr->ee.ee_info = info;
 259         serr->ee.ee_data = 0;
 260         serr->addr_offset = (u8*)&iph->daddr - skb->nh.raw;
 261         serr->port = fl->fl_ip_dport;
 262
 263         skb->h.raw = skb->tail;
 264         __skb_pull(skb, skb->tail - skb->data);
 265
 266         if (sock_queue_err_skb(sk, skb))
 267                 kfree_skb(skb);
 268 }
 269
 270 /*
 271  *      Handle MSG_ERRQUEUE
 272  */
 273 int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
 274 {
 275         struct ipv6_pinfo *np = inet6_sk(sk);
 276         struct sock_exterr_skb *serr;
 277         struct sk_buff *skb, *skb2;
 278         struct sockaddr_in6 *sin;
 279         struct {
 280                 struct sock_extended_err ee;
 281                 struct sockaddr_in6      offender;
 282         } errhdr;
 283         int err;
 284         int copied;
 285
 286         err = -EAGAIN;
 287         skb = skb_dequeue(&sk->sk_error_queue);
 288         if (skb == NULL)
 289                 goto out;
 290
 291         copied = skb->len;
 292         if (copied > len) {
 293                 msg->msg_flags |= MSG_TRUNC;
 294                 copied = len;
 295         }
 296         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 297         if (err)
 298                 goto out_free_skb;
 299
 300         sock_recv_timestamp(msg, sk, skb);
 301
 302         serr = SKB_EXT_ERR(skb);
 303
 304         sin = (struct sockaddr_in6 *)msg->msg_name;
 305         if (sin) {
 306                 sin->sin6_family = AF_INET6;
 307                 sin->sin6_flowinfo = 0;
 308                 sin->sin6_port = serr->port;
 309                 sin->sin6_scope_id = 0;
 310                 if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) {
 311                         ipv6_addr_copy(&sin->sin6_addr,
 312                           (struct in6_addr *)(skb->nh.raw + serr->addr_offset));
 313                         if (np->sndflow)
 314                                 sin->sin6_flowinfo = *(u32*)(skb->nh.raw + serr->addr_offset - 24) & IPV6_FLOWINFO_MASK;
 315                         if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 316                                 sin->sin6_scope_id = IP6CB(skb)->iif;
 317                 } else {
 318                         ipv6_addr_set(&sin->sin6_addr, 0, 0,
 319                                       htonl(0xffff),
 320                                       *(u32*)(skb->nh.raw + serr->addr_offset));
 321                 }
 322         }
 323
 324         memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
 325         sin = &errhdr.offender;
 326         sin->sin6_family = AF_UNSPEC;
 327         if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {
 328                 sin->sin6_family = AF_INET6;
 329                 sin->sin6_flowinfo = 0;
 330                 sin->sin6_scope_id = 0;
 331                 if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6) {
 332                         ipv6_addr_copy(&sin->sin6_addr, &skb->nh.ipv6h->saddr);
 333                         if (np->rxopt.all)
 334                                 datagram_recv_ctl(sk, msg, skb);
 335                         if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 336                                 sin->sin6_scope_id = IP6CB(skb)->iif;
 337                 } else {
 338                         struct inet_opt *inet = inet_sk(sk);
 339
 340                         ipv6_addr_set(&sin->sin6_addr, 0, 0,
 341                                       htonl(0xffff),
 342                                       skb->nh.iph->saddr);
 343                         if (inet->cmsg_flags)
 344                                 ip_cmsg_recv(msg, skb);
 345                 }
 346         }
 347
 348         put_cmsg(msg, SOL_IPV6, IPV6_RECVERR, sizeof(errhdr), &errhdr);
 349
 350         /* Now we could try to dump offended packet options */
 351
 352         msg->msg_flags |= MSG_ERRQUEUE;
 353         err = copied;
 354
 355         /* Reset and regenerate socket error */
 356         spin_lock_irq(&sk->sk_error_queue.lock);
 357         sk->sk_err = 0;
 358         if ((skb2 = skb_peek(&sk->sk_error_queue)) != NULL) {
 359                 sk->sk_err = SKB_EXT_ERR(skb2)->ee.ee_errno;
 360                 spin_unlock_irq(&sk->sk_error_queue.lock);
 361                 sk->sk_error_report(sk);
 362         } else {
 363                 spin_unlock_irq(&sk->sk_error_queue.lock);
 364         }
 365
 366 out_free_skb:
 367         kfree_skb(skb);
 368 out:
 369         return err;
 370 }
 371
 372
 373
 374 int datagram_recv_ctl(struct sock *sk, struct msghdr *msg, struct sk_buff *skb)
 375 {
 376         struct ipv6_pinfo *np = inet6_sk(sk);
 377         struct inet6_skb_parm *opt = IP6CB(skb);
 378
 379         if (np->rxopt.bits.rxinfo) {
 380                 struct in6_pktinfo src_info;
 381
 382                 src_info.ipi6_ifindex = opt->iif;
 383                 ipv6_addr_copy(&src_info.ipi6_addr, &skb->nh.ipv6h->daddr);
 384                 put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO, sizeof(src_info), &src_info);
 385         }
 386
 387         if (np->rxopt.bits.rxhlim) {
 388                 int hlim = skb->nh.ipv6h->hop_limit;
 389                 put_cmsg(msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
 390         }
 391
 392         if (np->rxopt.bits.rxflow && (*(u32*)skb->nh.raw & IPV6_FLOWINFO_MASK)) {
 393                 u32 flowinfo = *(u32*)skb->nh.raw & IPV6_FLOWINFO_MASK;
 394                 put_cmsg(msg, SOL_IPV6, IPV6_FLOWINFO, sizeof(flowinfo), &flowinfo);
 395         }
 396         if (np->rxopt.bits.hopopts && opt->hop) {
 397                 u8 *ptr = skb->nh.raw + opt->hop;
 398                 put_cmsg(msg, SOL_IPV6, IPV6_HOPOPTS, (ptr[1]+1)<<3, ptr);
 399         }
 400         if (np->rxopt.bits.dstopts && opt->dst0) {
 401                 u8 *ptr = skb->nh.raw + opt->dst0;
 402                 put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, (ptr[1]+1)<<3, ptr);
 403         }
 404         if (np->rxopt.bits.srcrt && opt->srcrt) {
 405                 struct ipv6_rt_hdr *rthdr = (struct ipv6_rt_hdr *)(skb->nh.raw + opt->srcrt);
 406                 put_cmsg(msg, SOL_IPV6, IPV6_RTHDR, (rthdr->hdrlen+1) << 3, rthdr);
 407         }
 408         if (np->rxopt.bits.dstopts && opt->dst1) {
 409                 u8 *ptr = skb->nh.raw + opt->dst1;
 410                 put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, (ptr[1]+1)<<3, ptr);
 411         }
 412         return 0;
 413 }
 414
 415 int datagram_send_ctl(struct msghdr *msg, struct flowi *fl,
 416                       struct ipv6_txoptions *opt,
 417                       int *hlimit)
 418 {
 419         struct in6_pktinfo *src_info;
 420         struct cmsghdr *cmsg;
 421         struct ipv6_rt_hdr *rthdr;
 422         struct ipv6_opt_hdr *hdr;
 423         int len;
 424         int err = 0;
 425
 426         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
 427                 int addr_type;
 428                 struct net_device *dev = NULL;
 429
 430                 if (cmsg->cmsg_len < sizeof(struct cmsghdr) ||
 431                     (unsigned long)(((char*)cmsg - (char*)msg->msg_control)
 432                                     + cmsg->cmsg_len) > msg->msg_controllen) {
 433                         err = -EINVAL;
 434                         goto exit_f;
 435                 }
 436
 437                 if (cmsg->cmsg_level != SOL_IPV6)
 438                         continue;
 439
 440                 switch (cmsg->cmsg_type) {
 441                 case IPV6_PKTINFO:
 442                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct in6_pktinfo))) {
 443                                 err = -EINVAL;
 444                                 goto exit_f;
 445                         }
 446
 447                         src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
 448
 449                         if (src_info->ipi6_ifindex) {
 450                                 if (fl->oif && src_info->ipi6_ifindex != fl->oif)
 451                                         return -EINVAL;
 452                                 fl->oif = src_info->ipi6_ifindex;
 453                         }
 454
 455                         addr_type = ipv6_addr_type(&src_info->ipi6_addr);
 456
 457                         if (addr_type == IPV6_ADDR_ANY)
 458                                 break;
 459
 460                         if (addr_type & IPV6_ADDR_LINKLOCAL) {
 461                                 if (!src_info->ipi6_ifindex)
 462                                         return -EINVAL;
 463                                 else {
 464                                         dev = dev_get_by_index(src_info->ipi6_ifindex);
 465                                         if (!dev)
 466                                                 return -ENODEV;
 467                                 }
 468                         }
 469                         if (!ipv6_chk_addr(&src_info->ipi6_addr, dev, 0)) {
 470                                 if (dev)
 471                                         dev_put(dev);
 472                                 err = -EINVAL;
 473                                 goto exit_f;
 474                         }
 475                         if (dev)
 476                                 dev_put(dev);
 477
 478                         ipv6_addr_copy(&fl->fl6_src, &src_info->ipi6_addr);
 479                         break;
 480
 481                 case IPV6_FLOWINFO:
 482                         if (cmsg->cmsg_len < CMSG_LEN(4)) {
 483                                 err = -EINVAL;
 484                                 goto exit_f;
 485                         }
 486
 487                         if (fl->fl6_flowlabel&IPV6_FLOWINFO_MASK) {
 488                                 if ((fl->fl6_flowlabel^*(u32 *)CMSG_DATA(cmsg))&~IPV6_FLOWINFO_MASK) {
 489                                         err = -EINVAL;
 490                                         goto exit_f;
 491                                 }
 492                         }
 493                         fl->fl6_flowlabel = IPV6_FLOWINFO_MASK & *(u32 *)CMSG_DATA(cmsg);
 494                         break;
 495
 496                 case IPV6_HOPOPTS:
 497                         if (opt->hopopt || cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
 498                                 err = -EINVAL;
 499                                 goto exit_f;
 500                         }
 501
 502                         hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
 503                         len = ((hdr->hdrlen + 1) << 3);
 504                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 505                                 err = -EINVAL;
 506                                 goto exit_f;
 507                         }
 508                         if (!capable(CAP_NET_RAW)) {
 509                                 err = -EPERM;
 510                                 goto exit_f;
 511                         }
 512                         opt->opt_nflen += len;
 513                         opt->hopopt = hdr;
 514                         break;
 515
 516                 case IPV6_DSTOPTS:
 517                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
 518                                 err = -EINVAL;
 519                                 goto exit_f;
 520                         }
 521
 522                         hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
 523                         len = ((hdr->hdrlen + 1) << 3);
 524                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 525                                 err = -EINVAL;
 526                                 goto exit_f;
 527                         }
 528                         if (!capable(CAP_NET_RAW)) {
 529                                 err = -EPERM;
 530                                 goto exit_f;
 531                         }
 532                         if (opt->dst1opt) {
 533                                 err = -EINVAL;
 534                                 goto exit_f;
 535                         }
 536                         opt->opt_flen += len;
 537                         opt->dst1opt = hdr;
 538                         break;
 539
 540                 case IPV6_RTHDR:
 541                         if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_rt_hdr))) {
 542                                 err = -EINVAL;
 543                                 goto exit_f;
 544                         }
 545
 546                         rthdr = (struct ipv6_rt_hdr *)CMSG_DATA(cmsg);
 547
 548                         /*
 549                          *      TYPE 0
 550                          */
 551                         if (rthdr->type) {
 552                                 err = -EINVAL;
 553                                 goto exit_f;
 554                         }
 555
 556                         len = ((rthdr->hdrlen + 1) << 3);
 557
 558                         if (cmsg->cmsg_len < CMSG_LEN(len)) {
 559                                 err = -EINVAL;
 560                                 goto exit_f;
 561                         }
 562
 563                         /* segments left must also match */
 564                         if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
 565                                 err = -EINVAL;
 566                                 goto exit_f;
 567                         }
 568
 569                         opt->opt_nflen += len;
 570                         opt->srcrt = rthdr;
 571
 572                         if (opt->dst1opt) {
 573                                 int dsthdrlen = ((opt->dst1opt->hdrlen+1)<<3);
 574
 575                                 opt->opt_nflen += dsthdrlen;
 576                                 opt->dst0opt = opt->dst1opt;
 577                                 opt->dst1opt = NULL;
 578                                 opt->opt_flen -= dsthdrlen;
 579                         }
 580
 581                         break;
 582
 583                 case IPV6_HOPLIMIT:
 584                         if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
 585                                 err = -EINVAL;
 586                                 goto exit_f;
 587                         }
 588
 589                         *hlimit = *(int *)CMSG_DATA(cmsg);
 590                         break;
 591
 592                 default:
 593                         LIMIT_NETDEBUG(
 594                                 printk(KERN_DEBUG "invalid cmsg type: %d\n", cmsg->cmsg_type));
 595                         err = -EINVAL;
 596                         break;
 597                 };
 598         }
 599
 600 exit_f:
 601         return err;
 602 }