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
  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 NET_RX_DROP;
  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 NET_RX_DROP;
 137                 }
 138         }
 139
 140         rcu_read_unlock();
 141
 142         /* Must drop socket now because of tproxy. */
 143         skb_orphan(skb);
 144
 145         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 146                        ip6_rcv_finish);
 147 err:
 148         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 149 drop:
 150         rcu_read_unlock();
 151         kfree_skb(skb);
 152         return NET_RX_DROP;
 153 }
 154
 155 /*
 156  *      Deliver the packet to the host
 157  */
 158
 159
 160 static int ip6_input_finish(struct sk_buff *skb)
 161 {
 162         const struct inet6_protocol *ipprot;
 163         unsigned int nhoff;
 164         int nexthdr, raw;
 165         u8 hash;
 166         struct inet6_dev *idev;
 167         struct net *net = dev_net(skb_dst(skb)->dev);
 168
 169         /*
 170          *      Parse extension headers
 171          */
 172
 173         rcu_read_lock();
 174 resubmit:
 175         idev = ip6_dst_idev(skb_dst(skb));
 176         if (!pskb_pull(skb, skb_transport_offset(skb)))
 177                 goto discard;
 178         nhoff = IP6CB(skb)->nhoff;
 179         nexthdr = skb_network_header(skb)[nhoff];
 180
 181         raw = raw6_local_deliver(skb, nexthdr);
 182
 183         hash = nexthdr & (MAX_INET_PROTOS - 1);
 184         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 185                 int ret;
 186
 187                 if (ipprot->flags & INET6_PROTO_FINAL) {
 188                         struct ipv6hdr *hdr;
 189
 190                         /* Free reference early: we don't need it any more,
 191                            and it may hold ip_conntrack module loaded
 192                            indefinitely. */
 193                         nf_reset(skb);
 194
 195                         skb_postpull_rcsum(skb, skb_network_header(skb),
 196                                            skb_network_header_len(skb));
 197                         hdr = ipv6_hdr(skb);
 198                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 199                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 200                             &hdr->saddr) &&
 201                             !ipv6_is_mld(skb, nexthdr))
 202                                 goto discard;
 203                 }
 204                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 205                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 206                         goto discard;
 207
 208                 ret = ipprot->handler(skb);
 209                 if (ret > 0)
 210                         goto resubmit;
 211                 else if (ret == 0)
 212                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 213         } else {
 214                 if (!raw) {
 215                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 216                                 IP6_INC_STATS_BH(net, idev,
 217                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 218                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 219                                             ICMPV6_UNK_NEXTHDR, nhoff);
 220                         }
 221                 } else
 222                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 223                 kfree_skb(skb);
 224         }
 225         rcu_read_unlock();
 226         return 0;
 227
 228 discard:
 229         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 230         rcu_read_unlock();
 231         kfree_skb(skb);
 232         return 0;
 233 }
 234
 235
 236 int ip6_input(struct sk_buff *skb)
 237 {
 238         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 239                        ip6_input_finish);
 240 }
 241
 242 int ip6_mc_input(struct sk_buff *skb)
 243 {
 244         struct ipv6hdr *hdr;
 245         int deliver;
 246
 247         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 248                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 249                          skb->len);
 250
 251         hdr = ipv6_hdr(skb);
 252         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 253
 254 #ifdef CONFIG_IPV6_MROUTE
 255         /*
 256          *      IPv6 multicast router mode is now supported ;)
 257          */
 258         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 259             !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 260             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 261                 /*
 262                  * Okay, we try to forward - split and duplicate
 263                  * packets.
 264                  */
 265                 struct sk_buff *skb2;
 266                 struct inet6_skb_parm *opt = IP6CB(skb);
 267
 268                 /* Check for MLD */
 269                 if (unlikely(opt->ra)) {
 270                         /* Check if this is a mld message */
 271                         u8 *ptr = skb_network_header(skb) + opt->ra;
 272                         struct icmp6hdr *icmp6;
 273                         u8 nexthdr = hdr->nexthdr;
 274                         int offset;
 275
 276                         /* Check if the value of Router Alert
 277                          * is for MLD (0x0000).
 278                          */
 279                         if ((ptr[2] | ptr[3]) == 0) {
 280                                 deliver = 0;
 281
 282                                 if (!ipv6_ext_hdr(nexthdr)) {
 283                                         /* BUG */
 284                                         goto out;
 285                                 }
 286                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 287                                                           &nexthdr);
 288                                 if (offset < 0)
 289                                         goto out;
 290
 291                                 if (nexthdr != IPPROTO_ICMPV6)
 292                                         goto out;
 293
 294                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 295                                                    offset + 1 - skb->data)))
 296                                         goto out;
 297
 298                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 299
 300                                 switch (icmp6->icmp6_type) {
 301                                 case ICMPV6_MGM_QUERY:
 302                                 case ICMPV6_MGM_REPORT:
 303                                 case ICMPV6_MGM_REDUCTION:
 304                                 case ICMPV6_MLD2_REPORT:
 305                                         deliver = 1;
 306                                         break;
 307                                 }
 308                                 goto out;
 309                         }
 310                         /* unknown RA - process it normally */
 311                 }
 312
 313                 if (deliver)
 314                         skb2 = skb_clone(skb, GFP_ATOMIC);
 315                 else {
 316                         skb2 = skb;
 317                         skb = NULL;
 318                 }
 319
 320                 if (skb2) {
 321                         ip6_mr_input(skb2);
 322                 }
 323         }
 324 out:
 325 #endif
 326         if (likely(deliver))
 327                 ip6_input(skb);
 328         else {
 329                 /* discard */
 330                 kfree_skb(skb);
 331         }
 332
 333         return 0;
 334 }