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   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
  32 #include <linux/netfilter.h>
  33 #include <linux/netfilter_ipv6.h>
  34
  35 #include <net/sock.h>
  36 #include <net/snmp.h>
  37
  38 #include <net/ipv6.h>
  39 #include <net/protocol.h>
  40 #include <net/transp_v6.h>
  41 #include <net/rawv6.h>
  42 #include <net/ndisc.h>
  43 #include <net/ip6_route.h>
  44 #include <net/addrconf.h>
  45 #include <net/xfrm.h>
  46
  47
  48
  49 inline int ip6_rcv_finish( struct sk_buff *skb)
  50 {
  51         if (skb_dst(skb) == NULL)
  52                 ip6_route_input(skb);
  53
  54         return dst_input(skb);
  55 }
  56
  57 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  58 {
  59         struct ipv6hdr *hdr;
  60         u32             pkt_len;
  61         struct inet6_dev *idev;
  62         struct net *net = dev_net(skb->dev);
  63
  64         if (skb->pkt_type == PACKET_OTHERHOST) {
  65                 kfree_skb(skb);
  66                 return 0;
  67         }
  68
  69         rcu_read_lock();
  70
  71         idev = __in6_dev_get(skb->dev);
  72
  73         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  74
  75         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  76             !idev || unlikely(idev->cnf.disable_ipv6)) {
  77                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  78                 goto drop;
  79         }
  80
  81         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  82
  83         /*
  84          * Store incoming device index. When the packet will
  85          * be queued, we cannot refer to skb->dev anymore.
  86          *
  87          * BTW, when we send a packet for our own local address on a
  88          * non-loopback interface (e.g. ethX), it is being delivered
  89          * via the loopback interface (lo) here; skb->dev = loopback_dev.
  90          * It, however, should be considered as if it is being
  91          * arrived via the sending interface (ethX), because of the
  92          * nature of scoping architecture. --yoshfuji
  93          */
  94         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
  95
  96         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
  97                 goto err;
  98
  99         hdr = ipv6_hdr(skb);
 100
 101         if (hdr->version != 6)
 102                 goto err;
 103
 104         /*
 105          * RFC4291 2.5.3
 106          * A packet received on an interface with a destination address
 107          * of loopback must be dropped.
 108          */
 109         if (!(dev->flags & IFF_LOOPBACK) &&
 110             ipv6_addr_loopback(&hdr->daddr))
 111                 goto err;
 112
 113         skb->transport_header = skb->network_header + sizeof(*hdr);
 114         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 115
 116         pkt_len = ntohs(hdr->payload_len);
 117
 118         /* pkt_len may be zero if Jumbo payload option is present */
 119         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 120                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 121                         IP6_INC_STATS_BH(net,
 122                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 123                         goto drop;
 124                 }
 125                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 126                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 127                         goto drop;
 128                 }
 129                 hdr = ipv6_hdr(skb);
 130         }
 131
 132         if (hdr->nexthdr == NEXTHDR_HOP) {
 133                 if (ipv6_parse_hopopts(skb) < 0) {
 134                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 135                         rcu_read_unlock();
 136                         return 0;
 137                 }
 138         }
 139
 140         rcu_read_unlock();
 141
 142         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 143                        ip6_rcv_finish);
 144 err:
 145         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 146 drop:
 147         rcu_read_unlock();
 148         kfree_skb(skb);
 149         return 0;
 150 }
 151
 152 /*
 153  *      Deliver the packet to the host
 154  */
 155
 156
 157 static int ip6_input_finish(struct sk_buff *skb)
 158 {
 159         struct inet6_protocol *ipprot;
 160         unsigned int nhoff;
 161         int nexthdr, raw;
 162         u8 hash;
 163         struct inet6_dev *idev;
 164         struct net *net = dev_net(skb_dst(skb)->dev);
 165
 166         /*
 167          *      Parse extension headers
 168          */
 169
 170         rcu_read_lock();
 171 resubmit:
 172         idev = ip6_dst_idev(skb_dst(skb));
 173         if (!pskb_pull(skb, skb_transport_offset(skb)))
 174                 goto discard;
 175         nhoff = IP6CB(skb)->nhoff;
 176         nexthdr = skb_network_header(skb)[nhoff];
 177
 178         raw = raw6_local_deliver(skb, nexthdr);
 179
 180         hash = nexthdr & (MAX_INET_PROTOS - 1);
 181         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 182                 int ret;
 183
 184                 if (ipprot->flags & INET6_PROTO_FINAL) {
 185                         struct ipv6hdr *hdr;
 186
 187                         /* Free reference early: we don't need it any more,
 188                            and it may hold ip_conntrack module loaded
 189                            indefinitely. */
 190                         nf_reset(skb);
 191
 192                         skb_postpull_rcsum(skb, skb_network_header(skb),
 193                                            skb_network_header_len(skb));
 194                         hdr = ipv6_hdr(skb);
 195                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 196                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 197                             &hdr->saddr) &&
 198                             !ipv6_is_mld(skb, nexthdr))
 199                                 goto discard;
 200                 }
 201                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 202                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 203                         goto discard;
 204
 205                 ret = ipprot->handler(skb);
 206                 if (ret > 0)
 207                         goto resubmit;
 208                 else if (ret == 0)
 209                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 210         } else {
 211                 if (!raw) {
 212                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 213                                 IP6_INC_STATS_BH(net, idev,
 214                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 215                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 216                                             ICMPV6_UNK_NEXTHDR, nhoff,
 217                                             skb->dev);
 218                         }
 219                 } else
 220                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 221                 kfree_skb(skb);
 222         }
 223         rcu_read_unlock();
 224         return 0;
 225
 226 discard:
 227         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 228         rcu_read_unlock();
 229         kfree_skb(skb);
 230         return 0;
 231 }
 232
 233
 234 int ip6_input(struct sk_buff *skb)
 235 {
 236         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 237                        ip6_input_finish);
 238 }
 239
 240 int ip6_mc_input(struct sk_buff *skb)
 241 {
 242         struct ipv6hdr *hdr;
 243         int deliver;
 244
 245         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 246                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 247                          skb->len);
 248
 249         hdr = ipv6_hdr(skb);
 250         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 251
 252 #ifdef CONFIG_IPV6_MROUTE
 253         /*
 254          *      IPv6 multicast router mode is now supported ;)
 255          */
 256         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 257             !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 258             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 259                 /*
 260                  * Okay, we try to forward - split and duplicate
 261                  * packets.
 262                  */
 263                 struct sk_buff *skb2;
 264                 struct inet6_skb_parm *opt = IP6CB(skb);
 265
 266                 /* Check for MLD */
 267                 if (unlikely(opt->ra)) {
 268                         /* Check if this is a mld message */
 269                         u8 *ptr = skb_network_header(skb) + opt->ra;
 270                         struct icmp6hdr *icmp6;
 271                         u8 nexthdr = hdr->nexthdr;
 272                         int offset;
 273
 274                         /* Check if the value of Router Alert
 275                          * is for MLD (0x0000).
 276                          */
 277                         if ((ptr[2] | ptr[3]) == 0) {
 278                                 deliver = 0;
 279
 280                                 if (!ipv6_ext_hdr(nexthdr)) {
 281                                         /* BUG */
 282                                         goto out;
 283                                 }
 284                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 285                                                           &nexthdr);
 286                                 if (offset < 0)
 287                                         goto out;
 288
 289                                 if (nexthdr != IPPROTO_ICMPV6)
 290                                         goto out;
 291
 292                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 293                                                    offset + 1 - skb->data)))
 294                                         goto out;
 295
 296                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 297
 298                                 switch (icmp6->icmp6_type) {
 299                                 case ICMPV6_MGM_QUERY:
 300                                 case ICMPV6_MGM_REPORT:
 301                                 case ICMPV6_MGM_REDUCTION:
 302                                 case ICMPV6_MLD2_REPORT:
 303                                         deliver = 1;
 304                                         break;
 305                                 }
 306                                 goto out;
 307                         }
 308                         /* unknown RA - process it normally */
 309                 }
 310
 311                 if (deliver)
 312                         skb2 = skb_clone(skb, GFP_ATOMIC);
 313                 else {
 314                         skb2 = skb;
 315                         skb = NULL;
 316                 }
 317
 318                 if (skb2) {
 319                         ip6_mr_input(skb2);
 320                 }
 321         }
 322 out:
 323 #endif
 324         if (likely(deliver))
 325                 ip6_input(skb);
 326         else {
 327                 /* discard */
 328                 kfree_skb(skb);
 329         }
 330
 331         return 0;
 332 }