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 inline int ip6_rcv_finish( struct sk_buff *skb)
  51 {
  52         if (skb_dst(skb) == NULL)
  53                 ip6_route_input(skb);
  54
  55         return dst_input(skb);
  56 }
  57
  58 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  59 {
  60         const struct ipv6hdr *hdr;
  61         u32             pkt_len;
  62         struct inet6_dev *idev;
  63         struct net *net = dev_net(skb->dev);
  64
  65         if (skb->pkt_type == PACKET_OTHERHOST) {
  66                 kfree_skb(skb);
  67                 return NET_RX_DROP;
  68         }
  69
  70         rcu_read_lock();
  71
  72         idev = __in6_dev_get(skb->dev);
  73
  74         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  75
  76         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  77             !idev || unlikely(idev->cnf.disable_ipv6)) {
  78                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  79                 goto drop;
  80         }
  81
  82         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  83
  84         /*
  85          * Store incoming device index. When the packet will
  86          * be queued, we cannot refer to skb->dev anymore.
  87          *
  88          * BTW, when we send a packet for our own local address on a
  89          * non-loopback interface (e.g. ethX), it is being delivered
  90          * via the loopback interface (lo) here; skb->dev = loopback_dev.
  91          * It, however, should be considered as if it is being
  92          * arrived via the sending interface (ethX), because of the
  93          * nature of scoping architecture. --yoshfuji
  94          */
  95         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
  96
  97         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
  98                 goto err;
  99
 100         hdr = ipv6_hdr(skb);
 101
 102         if (hdr->version != 6)
 103                 goto err;
 104
 105         /*
 106          * RFC4291 2.5.3
 107          * A packet received on an interface with a destination address
 108          * of loopback must be dropped.
 109          */
 110         if (!(dev->flags & IFF_LOOPBACK) &&
 111             ipv6_addr_loopback(&hdr->daddr))
 112                 goto err;
 113
 114         /* RFC4291 Errata ID: 3480
 115          * Interface-Local scope spans only a single interface on a
 116          * node and is useful only for loopback transmission of
 117          * multicast.  Packets with interface-local scope received
 118          * from another node must be discarded.
 119          */
 120         if (!(skb->pkt_type == PACKET_LOOPBACK ||
 121               dev->flags & IFF_LOOPBACK) &&
 122             ipv6_addr_is_multicast(&hdr->daddr) &&
 123             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
 124                 goto err;
 125
 126         /* RFC4291 2.7
 127          * Nodes must not originate a packet to a multicast address whose scope
 128          * field contains the reserved value 0; if such a packet is received, it
 129          * must be silently dropped.
 130          */
 131         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 132             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
 133                 goto err;
 134
 135         /*
 136          * RFC4291 2.7
 137          * Multicast addresses must not be used as source addresses in IPv6
 138          * packets or appear in any Routing header.
 139          */
 140         if (ipv6_addr_is_multicast(&hdr->saddr))
 141                 goto err;
 142
 143         skb->transport_header = skb->network_header + sizeof(*hdr);
 144         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 145
 146         pkt_len = ntohs(hdr->payload_len);
 147
 148         /* pkt_len may be zero if Jumbo payload option is present */
 149         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 150                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 151                         IP6_INC_STATS_BH(net,
 152                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 153                         goto drop;
 154                 }
 155                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 156                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 157                         goto drop;
 158                 }
 159                 hdr = ipv6_hdr(skb);
 160         }
 161
 162         if (hdr->nexthdr == NEXTHDR_HOP) {
 163                 if (ipv6_parse_hopopts(skb) < 0) {
 164                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 165                         rcu_read_unlock();
 166                         return NET_RX_DROP;
 167                 }
 168         }
 169
 170         rcu_read_unlock();
 171
 172         /* Must drop socket now because of tproxy. */
 173         skb_orphan(skb);
 174
 175         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 176                        ip6_rcv_finish);
 177 err:
 178         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 179 drop:
 180         rcu_read_unlock();
 181         kfree_skb(skb);
 182         return NET_RX_DROP;
 183 }
 184
 185 /*
 186  *      Deliver the packet to the host
 187  */
 188
 189
 190 static int ip6_input_finish(struct sk_buff *skb)
 191 {
 192         const struct inet6_protocol *ipprot;
 193         unsigned int nhoff;
 194         int nexthdr, raw;
 195         u8 hash;
 196         struct inet6_dev *idev;
 197         struct net *net = dev_net(skb_dst(skb)->dev);
 198
 199         /*
 200          *      Parse extension headers
 201          */
 202
 203         rcu_read_lock();
 204 resubmit:
 205         idev = ip6_dst_idev(skb_dst(skb));
 206         if (!pskb_pull(skb, skb_transport_offset(skb)))
 207                 goto discard;
 208         nhoff = IP6CB(skb)->nhoff;
 209         nexthdr = skb_network_header(skb)[nhoff];
 210
 211         raw = raw6_local_deliver(skb, nexthdr);
 212
 213         hash = nexthdr & (MAX_INET_PROTOS - 1);
 214         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 215                 int ret;
 216
 217                 if (ipprot->flags & INET6_PROTO_FINAL) {
 218                         const struct ipv6hdr *hdr;
 219
 220                         /* Free reference early: we don't need it any more,
 221                            and it may hold ip_conntrack module loaded
 222                            indefinitely. */
 223                         nf_reset(skb);
 224
 225                         skb_postpull_rcsum(skb, skb_network_header(skb),
 226                                            skb_network_header_len(skb));
 227                         hdr = ipv6_hdr(skb);
 228                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 229                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 230                             &hdr->saddr) &&
 231                             !ipv6_is_mld(skb, nexthdr))
 232                                 goto discard;
 233                 }
 234                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 235                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 236                         goto discard;
 237
 238                 ret = ipprot->handler(skb);
 239                 if (ret > 0)
 240                         goto resubmit;
 241                 else if (ret == 0)
 242                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 243         } else {
 244                 if (!raw) {
 245                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 246                                 IP6_INC_STATS_BH(net, idev,
 247                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 248                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 249                                             ICMPV6_UNK_NEXTHDR, nhoff);
 250                         }
 251                 } else
 252                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 253                 kfree_skb(skb);
 254         }
 255         rcu_read_unlock();
 256         return 0;
 257
 258 discard:
 259         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 260         rcu_read_unlock();
 261         kfree_skb(skb);
 262         return 0;
 263 }
 264
 265
 266 int ip6_input(struct sk_buff *skb)
 267 {
 268         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 269                        ip6_input_finish);
 270 }
 271
 272 int ip6_mc_input(struct sk_buff *skb)
 273 {
 274         const struct ipv6hdr *hdr;
 275         int deliver;
 276
 277         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 278                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 279                          skb->len);
 280
 281         hdr = ipv6_hdr(skb);
 282         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 283
 284 #ifdef CONFIG_IPV6_MROUTE
 285         /*
 286          *      IPv6 multicast router mode is now supported ;)
 287          */
 288         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 289             !(ipv6_addr_type(&hdr->daddr) &
 290               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
 291             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 292                 /*
 293                  * Okay, we try to forward - split and duplicate
 294                  * packets.
 295                  */
 296                 struct sk_buff *skb2;
 297                 struct inet6_skb_parm *opt = IP6CB(skb);
 298
 299                 /* Check for MLD */
 300                 if (unlikely(opt->ra)) {
 301                         /* Check if this is a mld message */
 302                         u8 *ptr = skb_network_header(skb) + opt->ra;
 303                         struct icmp6hdr *icmp6;
 304                         u8 nexthdr = hdr->nexthdr;
 305                         int offset;
 306
 307                         /* Check if the value of Router Alert
 308                          * is for MLD (0x0000).
 309                          */
 310                         if ((ptr[2] | ptr[3]) == 0) {
 311                                 deliver = 0;
 312
 313                                 if (!ipv6_ext_hdr(nexthdr)) {
 314                                         /* BUG */
 315                                         goto out;
 316                                 }
 317                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 318                                                           &nexthdr);
 319                                 if (offset < 0)
 320                                         goto out;
 321
 322                                 if (nexthdr != IPPROTO_ICMPV6)
 323                                         goto out;
 324
 325                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 326                                                    offset + 1 - skb->data)))
 327                                         goto out;
 328
 329                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 330
 331                                 switch (icmp6->icmp6_type) {
 332                                 case ICMPV6_MGM_QUERY:
 333                                 case ICMPV6_MGM_REPORT:
 334                                 case ICMPV6_MGM_REDUCTION:
 335                                 case ICMPV6_MLD2_REPORT:
 336                                         deliver = 1;
 337                                         break;
 338                                 }
 339                                 goto out;
 340                         }
 341                         /* unknown RA - process it normally */
 342                 }
 343
 344                 if (deliver)
 345                         skb2 = skb_clone(skb, GFP_ATOMIC);
 346                 else {
 347                         skb2 = skb;
 348                         skb = NULL;
 349                 }
 350
 351                 if (skb2) {
 352                         ip6_mr_input(skb2);
 353                 }
 354         }
 355 out:
 356 #endif
 357         if (likely(deliver))
 358                 ip6_input(skb);
 359         else {
 360                 /* discard */
 361                 kfree_skb(skb);
 362         }
 363
 364         return 0;
 365 }