net/ipv6/ip6_input.c

   1 /*
   2  *      IPv6 input
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Ian P. Morris           <I.P.Morris@soton.ac.uk>
   8  *
   9  *      Based in linux/net/ipv4/ip_input.c
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  16 /* Changes
  17  *
  18  *      Mitsuru KANDA @USAGI and
  19  *      YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
  20  */
  21
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/socket.h>
  25 #include <linux/sockios.h>
  26 #include <linux/net.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/in6.h>
  29 #include <linux/icmpv6.h>
  30 #include <linux/mroute6.h>
  31 #include <linux/slab.h>
  32
  33 #include <linux/netfilter.h>
  34 #include <linux/netfilter_ipv6.h>
  35
  36 #include <net/sock.h>
  37 #include <net/snmp.h>
  38
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/transp_v6.h>
  42 #include <net/rawv6.h>
  43 #include <net/ndisc.h>
  44 #include <net/ip6_route.h>
  45 #include <net/addrconf.h>
  46 #include <net/xfrm.h>
  47
  48
  49
  50 int ip6_rcv_finish(struct sk_buff *skb)
  51 {
  52         if (sysctl_ip_early_demux && !skb_dst(skb)) {
  53                 const struct inet6_protocol *ipprot;
  54
  55                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
  56                 if (ipprot && ipprot->early_demux)
  57                         ipprot->early_demux(skb);
  58         }
  59         if (!skb_dst(skb))
  60                 ip6_route_input(skb);
  61
  62         return dst_input(skb);
  63 }
  64
  65 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  66 {
  67         const struct ipv6hdr *hdr;
  68         u32             pkt_len;
  69         struct inet6_dev *idev;
  70         struct net *net = dev_net(skb->dev);
  71
  72         if (skb->pkt_type == PACKET_OTHERHOST) {
  73                 kfree_skb(skb);
  74                 return NET_RX_DROP;
  75         }
  76
  77         rcu_read_lock();
  78
  79         idev = __in6_dev_get(skb->dev);
  80
  81         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  82
  83         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  84             !idev || unlikely(idev->cnf.disable_ipv6)) {
  85                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  86                 goto drop;
  87         }
  88
  89         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  90
  91         /*
  92          * Store incoming device index. When the packet will
  93          * be queued, we cannot refer to skb->dev anymore.
  94          *
  95          * BTW, when we send a packet for our own local address on a
  96          * non-loopback interface (e.g. ethX), it is being delivered
  97          * via the loopback interface (lo) here; skb->dev = loopback_dev.
  98          * It, however, should be considered as if it is being
  99          * arrived via the sending interface (ethX), because of the
 100          * nature of scoping architecture. --yoshfuji
 101          */
 102         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 103
 104         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 105                 goto err;
 106
 107         hdr = ipv6_hdr(skb);
 108
 109         if (hdr->version != 6)
 110                 goto err;
 111
 112         /*
 113          * RFC4291 2.5.3
 114          * A packet received on an interface with a destination address
 115          * of loopback must be dropped.
 116          */
 117         if (!(dev->flags & IFF_LOOPBACK) &&
 118             ipv6_addr_loopback(&hdr->daddr))
 119                 goto err;
 120
 121         /* RFC4291 Errata ID: 3480
 122          * Interface-Local scope spans only a single interface on a
 123          * node and is useful only for loopback transmission of
 124          * multicast.  Packets with interface-local scope received
 125          * from another node must be discarded.
 126          */
 127         if (!(skb->pkt_type == PACKET_LOOPBACK ||
 128               dev->flags & IFF_LOOPBACK) &&
 129             ipv6_addr_is_multicast(&hdr->daddr) &&
 130             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
 131                 goto err;
 132
 133         /* RFC4291 2.7
 134          * Nodes must not originate a packet to a multicast address whose scope
 135          * field contains the reserved value 0; if such a packet is received, it
 136          * must be silently dropped.
 137          */
 138         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 139             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
 140                 goto err;
 141
 142         /*
 143          * RFC4291 2.7
 144          * Multicast addresses must not be used as source addresses in IPv6
 145          * packets or appear in any Routing header.
 146          */
 147         if (ipv6_addr_is_multicast(&hdr->saddr))
 148                 goto err;
 149
 150         skb->transport_header = skb->network_header + sizeof(*hdr);
 151         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 152
 153         pkt_len = ntohs(hdr->payload_len);
 154
 155         /* pkt_len may be zero if Jumbo payload option is present */
 156         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 157                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 158                         IP6_INC_STATS_BH(net,
 159                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 160                         goto drop;
 161                 }
 162                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 163                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 164                         goto drop;
 165                 }
 166                 hdr = ipv6_hdr(skb);
 167         }
 168
 169         if (hdr->nexthdr == NEXTHDR_HOP) {
 170                 if (ipv6_parse_hopopts(skb) < 0) {
 171                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 172                         rcu_read_unlock();
 173                         return NET_RX_DROP;
 174                 }
 175         }
 176
 177         rcu_read_unlock();
 178
 179         /* Must drop socket now because of tproxy. */
 180         skb_orphan(skb);
 181
 182         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 183                        ip6_rcv_finish);
 184 err:
 185         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 186 drop:
 187         rcu_read_unlock();
 188         kfree_skb(skb);
 189         return NET_RX_DROP;
 190 }
 191
 192 /*
 193  *      Deliver the packet to the host
 194  */
 195
 196
 197 static int ip6_input_finish(struct sk_buff *skb)
 198 {
 199         struct net *net = dev_net(skb_dst(skb)->dev);
 200         const struct inet6_protocol *ipprot;
 201         struct inet6_dev *idev;
 202         unsigned int nhoff;
 203         int nexthdr;
 204         bool raw;
 205
 206         /*
 207          *      Parse extension headers
 208          */
 209
 210         rcu_read_lock();
 211 resubmit:
 212         idev = ip6_dst_idev(skb_dst(skb));
 213         if (!pskb_pull(skb, skb_transport_offset(skb)))
 214                 goto discard;
 215         nhoff = IP6CB(skb)->nhoff;
 216         nexthdr = skb_network_header(skb)[nhoff];
 217
 218         raw = raw6_local_deliver(skb, nexthdr);
 219         if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
 220                 int ret;
 221
 222                 if (ipprot->flags & INET6_PROTO_FINAL) {
 223                         const struct ipv6hdr *hdr;
 224
 225                         /* Free reference early: we don't need it any more,
 226                            and it may hold ip_conntrack module loaded
 227                            indefinitely. */
 228                         nf_reset(skb);
 229
 230                         skb_postpull_rcsum(skb, skb_network_header(skb),
 231                                            skb_network_header_len(skb));
 232                         hdr = ipv6_hdr(skb);
 233                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 234                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 235                             &hdr->saddr) &&
 236                             !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
 237                                 goto discard;
 238                 }
 239                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 240                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 241                         goto discard;
 242
 243                 ret = ipprot->handler(skb);
 244                 if (ret > 0)
 245                         goto resubmit;
 246                 else if (ret == 0)
 247                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 248         } else {
 249                 if (!raw) {
 250                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 251                                 IP6_INC_STATS_BH(net, idev,
 252                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 253                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 254                                             ICMPV6_UNK_NEXTHDR, nhoff);
 255                         }
 256                         kfree_skb(skb);
 257                 } else {
 258                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 259                         consume_skb(skb);
 260                 }
 261         }
 262         rcu_read_unlock();
 263         return 0;
 264
 265 discard:
 266         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 267         rcu_read_unlock();
 268         kfree_skb(skb);
 269         return 0;
 270 }
 271
 272
 273 int ip6_input(struct sk_buff *skb)
 274 {
 275         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 276                        ip6_input_finish);
 277 }
 278
 279 int ip6_mc_input(struct sk_buff *skb)
 280 {
 281         const struct ipv6hdr *hdr;
 282         bool deliver;
 283
 284         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 285                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 286                          skb->len);
 287
 288         hdr = ipv6_hdr(skb);
 289         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 290
 291 #ifdef CONFIG_IPV6_MROUTE
 292         /*
 293          *      IPv6 multicast router mode is now supported ;)
 294          */
 295         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 296             !(ipv6_addr_type(&hdr->daddr) &
 297               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
 298             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 299                 /*
 300                  * Okay, we try to forward - split and duplicate
 301                  * packets.
 302                  */
 303                 struct sk_buff *skb2;
 304                 struct inet6_skb_parm *opt = IP6CB(skb);
 305
 306                 /* Check for MLD */
 307                 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 308                         /* Check if this is a mld message */
 309                         u8 nexthdr = hdr->nexthdr;
 310                         __be16 frag_off;
 311                         int offset;
 312
 313                         /* Check if the value of Router Alert
 314                          * is for MLD (0x0000).
 315                          */
 316                         if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
 317                                 deliver = false;
 318
 319                                 if (!ipv6_ext_hdr(nexthdr)) {
 320                                         /* BUG */
 321                                         goto out;
 322                                 }
 323                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 324                                                           &nexthdr, &frag_off);
 325                                 if (offset < 0)
 326                                         goto out;
 327
 328                                 if (!ipv6_is_mld(skb, nexthdr, offset))
 329                                         goto out;
 330
 331                                 deliver = true;
 332                         }
 333                         /* unknown RA - process it normally */
 334                 }
 335
 336                 if (deliver)
 337                         skb2 = skb_clone(skb, GFP_ATOMIC);
 338                 else {
 339                         skb2 = skb;
 340                         skb = NULL;
 341                 }
 342
 343                 if (skb2) {
 344                         ip6_mr_input(skb2);
 345                 }
 346         }
 347 out:
 348 #endif
 349         if (likely(deliver))
 350                 ip6_input(skb);
 351         else {
 352                 /* discard */
 353                 kfree_skb(skb);
 354         }
 355
 356         return 0;
 357 }