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 == 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
  63         if (skb->pkt_type == PACKET_OTHERHOST) {
  64                 kfree_skb(skb);
  65                 return 0;
  66         }
  67
  68         rcu_read_lock();
  69
  70         idev = __in6_dev_get(skb->dev);
  71
  72         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INRECEIVES);
  73
  74         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
  75                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
  76                 rcu_read_unlock();
  77                 goto out;
  78         }
  79
  80         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  81
  82         /*
  83          * Store incoming device index. When the packet will
  84          * be queued, we cannot refer to skb->dev anymore.
  85          *
  86          * BTW, when we send a packet for our own local address on a
  87          * non-loopback interface (e.g. ethX), it is being delivered
  88          * via the loopback interface (lo) here; skb->dev = loopback_dev.
  89          * It, however, should be considered as if it is being
  90          * arrived via the sending interface (ethX), because of the
  91          * nature of scoping architecture. --yoshfuji
  92          */
  93         IP6CB(skb)->iif = skb->dst ? ip6_dst_idev(skb->dst)->dev->ifindex : dev->ifindex;
  94
  95         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
  96                 goto err;
  97
  98         hdr = ipv6_hdr(skb);
  99
 100         if (hdr->version != 6)
 101                 goto err;
 102
 103         /*
 104          * RFC4291 2.5.3
 105          * A packet received on an interface with a destination address
 106          * of loopback must be dropped.
 107          */
 108         if (!(dev->flags & IFF_LOOPBACK) &&
 109             ipv6_addr_loopback(&hdr->daddr))
 110                 goto err;
 111
 112         skb->transport_header = skb->network_header + sizeof(*hdr);
 113         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 114
 115         pkt_len = ntohs(hdr->payload_len);
 116
 117         /* pkt_len may be zero if Jumbo payload option is present */
 118         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 119                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 120                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 121                         goto drop;
 122                 }
 123                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 124                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 125                         goto drop;
 126                 }
 127                 hdr = ipv6_hdr(skb);
 128         }
 129
 130         if (hdr->nexthdr == NEXTHDR_HOP) {
 131                 if (ipv6_parse_hopopts(skb) < 0) {
 132                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 133                         rcu_read_unlock();
 134                         return 0;
 135                 }
 136         }
 137
 138         rcu_read_unlock();
 139
 140         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 141                        ip6_rcv_finish);
 142 err:
 143         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 144 drop:
 145         rcu_read_unlock();
 146         kfree_skb(skb);
 147 out:
 148         return 0;
 149 }
 150
 151 /*
 152  *      Deliver the packet to the host
 153  */
 154
 155
 156 static int ip6_input_finish(struct sk_buff *skb)
 157 {
 158         struct inet6_protocol *ipprot;
 159         unsigned int nhoff;
 160         int nexthdr, raw;
 161         u8 hash;
 162         struct inet6_dev *idev;
 163
 164         /*
 165          *      Parse extension headers
 166          */
 167
 168         rcu_read_lock();
 169 resubmit:
 170         idev = ip6_dst_idev(skb->dst);
 171         if (!pskb_pull(skb, skb_transport_offset(skb)))
 172                 goto discard;
 173         nhoff = IP6CB(skb)->nhoff;
 174         nexthdr = skb_network_header(skb)[nhoff];
 175
 176         raw = raw6_local_deliver(skb, nexthdr);
 177
 178         hash = nexthdr & (MAX_INET_PROTOS - 1);
 179         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 180                 int ret;
 181
 182                 if (ipprot->flags & INET6_PROTO_FINAL) {
 183                         struct ipv6hdr *hdr;
 184
 185                         /* Free reference early: we don't need it any more,
 186                            and it may hold ip_conntrack module loaded
 187                            indefinitely. */
 188                         nf_reset(skb);
 189
 190                         skb_postpull_rcsum(skb, skb_network_header(skb),
 191                                            skb_network_header_len(skb));
 192                         hdr = ipv6_hdr(skb);
 193                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 194                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 195                             &hdr->saddr) &&
 196                             !ipv6_is_mld(skb, nexthdr))
 197                                 goto discard;
 198                 }
 199                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 200                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 201                         goto discard;
 202
 203                 ret = ipprot->handler(skb);
 204                 if (ret > 0)
 205                         goto resubmit;
 206                 else if (ret == 0)
 207                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 208         } else {
 209                 if (!raw) {
 210                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 211                                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
 212                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 213                                             ICMPV6_UNK_NEXTHDR, nhoff,
 214                                             skb->dev);
 215                         }
 216                 } else
 217                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 218                 kfree_skb(skb);
 219         }
 220         rcu_read_unlock();
 221         return 0;
 222
 223 discard:
 224         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
 225         rcu_read_unlock();
 226         kfree_skb(skb);
 227         return 0;
 228 }
 229
 230
 231 int ip6_input(struct sk_buff *skb)
 232 {
 233         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 234                        ip6_input_finish);
 235 }
 236
 237 int ip6_mc_input(struct sk_buff *skb)
 238 {
 239         struct ipv6hdr *hdr;
 240         int deliver;
 241
 242         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS);
 243
 244         hdr = ipv6_hdr(skb);
 245         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 246
 247 #ifdef CONFIG_IPV6_MROUTE
 248         /*
 249          *      IPv6 multicast router mode is now supported ;)
 250          */
 251         if (ipv6_devconf.mc_forwarding &&
 252             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 253                 /*
 254                  * Okay, we try to forward - split and duplicate
 255                  * packets.
 256                  */
 257                 struct sk_buff *skb2;
 258                 struct inet6_skb_parm *opt = IP6CB(skb);
 259
 260                 /* Check for MLD */
 261                 if (unlikely(opt->ra)) {
 262                         /* Check if this is a mld message */
 263                         u8 *ptr = skb_network_header(skb) + opt->ra;
 264                         struct icmp6hdr *icmp6;
 265                         u8 nexthdr = hdr->nexthdr;
 266                         int offset;
 267
 268                         /* Check if the value of Router Alert
 269                          * is for MLD (0x0000).
 270                          */
 271                         if ((ptr[2] | ptr[3]) == 0) {
 272                                 deliver = 0;
 273
 274                                 if (!ipv6_ext_hdr(nexthdr)) {
 275                                         /* BUG */
 276                                         goto out;
 277                                 }
 278                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 279                                                           &nexthdr);
 280                                 if (offset < 0)
 281                                         goto out;
 282
 283                                 if (nexthdr != IPPROTO_ICMPV6)
 284                                         goto out;
 285
 286                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 287                                                    offset + 1 - skb->data)))
 288                                         goto out;
 289
 290                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 291
 292                                 switch (icmp6->icmp6_type) {
 293                                 case ICMPV6_MGM_QUERY:
 294                                 case ICMPV6_MGM_REPORT:
 295                                 case ICMPV6_MGM_REDUCTION:
 296                                 case ICMPV6_MLD2_REPORT:
 297                                         deliver = 1;
 298                                         break;
 299                                 }
 300                                 goto out;
 301                         }
 302                         /* unknown RA - process it normally */
 303                 }
 304
 305                 if (deliver)
 306                         skb2 = skb_clone(skb, GFP_ATOMIC);
 307                 else {
 308                         skb2 = skb;
 309                         skb = NULL;
 310                 }
 311
 312                 if (skb2) {
 313                         skb2->dev = skb2->dst->dev;
 314                         ip6_mr_input(skb2);
 315                 }
 316         }
 317 out:
 318 #endif
 319         if (likely(deliver))
 320                 ip6_input(skb);
 321         else {
 322                 /* discard */
 323                 kfree_skb(skb);
 324         }
 325
 326         return 0;
 327 }