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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  *      $Id: ip6_input.c,v 1.19 2000/12/13 18:31:50 davem Exp $
  10  *
  11  *      Based in linux/net/ipv4/ip_input.c
  12  *
  13  *      This program is free software; you can redistribute it and/or
  14  *      modify it under the terms of the GNU General Public License
  15  *      as published by the Free Software Foundation; either version
  16  *      2 of the License, or (at your option) any later version.
  17  */
  18 /* Changes
  19  *
  20  *      Mitsuru KANDA @USAGI and
  21  *      YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
  22  */
  23
  24 #include <linux/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.h>
  28 #include <linux/net.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/in6.h>
  31 #include <linux/icmpv6.h>
  32 #include <linux/mroute6.h>
  33
  34 #include <linux/netfilter.h>
  35 #include <linux/netfilter_ipv6.h>
  36
  37 #include <net/sock.h>
  38 #include <net/snmp.h>
  39
  40 #include <net/ipv6.h>
  41 #include <net/protocol.h>
  42 #include <net/transp_v6.h>
  43 #include <net/rawv6.h>
  44 #include <net/ndisc.h>
  45 #include <net/ip6_route.h>
  46 #include <net/addrconf.h>
  47 #include <net/xfrm.h>
  48
  49
  50
  51 inline int ip6_rcv_finish( struct sk_buff *skb)
  52 {
  53         if (skb->dst == NULL)
  54                 ip6_route_input(skb);
  55
  56         return dst_input(skb);
  57 }
  58
  59 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  60 {
  61         struct ipv6hdr *hdr;
  62         u32             pkt_len;
  63         struct inet6_dev *idev;
  64
  65         if (skb->pkt_type == PACKET_OTHERHOST) {
  66                 kfree_skb(skb);
  67                 return 0;
  68         }
  69
  70         rcu_read_lock();
  71
  72         idev = __in6_dev_get(skb->dev);
  73
  74         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INRECEIVES);
  75
  76         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
  77                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
  78                 rcu_read_unlock();
  79                 goto out;
  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 ? ip6_dst_idev(skb->dst)->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         skb->transport_header = skb->network_header + sizeof(*hdr);
 115         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 116
 117         pkt_len = ntohs(hdr->payload_len);
 118
 119         /* pkt_len may be zero if Jumbo payload option is present */
 120         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 121                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 122                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 123                         goto drop;
 124                 }
 125                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 126                         IP6_INC_STATS_BH(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(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(idev, IPSTATS_MIB_INHDRERRORS);
 146 drop:
 147         rcu_read_unlock();
 148         kfree_skb(skb);
 149 out:
 150         return 0;
 151 }
 152
 153 /*
 154  *      Deliver the packet to the host
 155  */
 156
 157
 158 static int ip6_input_finish(struct sk_buff *skb)
 159 {
 160         struct inet6_protocol *ipprot;
 161         unsigned int nhoff;
 162         int nexthdr, raw;
 163         u8 hash;
 164         struct inet6_dev *idev;
 165
 166         /*
 167          *      Parse extension headers
 168          */
 169
 170         rcu_read_lock();
 171 resubmit:
 172         idev = ip6_dst_idev(skb->dst);
 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(idev, IPSTATS_MIB_INDELIVERS);
 210         } else {
 211                 if (!raw) {
 212                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 213                                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
 214                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 215                                             ICMPV6_UNK_NEXTHDR, nhoff,
 216                                             skb->dev);
 217                         }
 218                 } else
 219                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 220                 kfree_skb(skb);
 221         }
 222         rcu_read_unlock();
 223         return 0;
 224
 225 discard:
 226         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
 227         rcu_read_unlock();
 228         kfree_skb(skb);
 229         return 0;
 230 }
 231
 232
 233 int ip6_input(struct sk_buff *skb)
 234 {
 235         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 236                        ip6_input_finish);
 237 }
 238
 239 int ip6_mc_input(struct sk_buff *skb)
 240 {
 241         struct ipv6hdr *hdr;
 242         int deliver;
 243
 244         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS);
 245
 246         hdr = ipv6_hdr(skb);
 247         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 248
 249 #ifdef CONFIG_IPV6_MROUTE
 250         /*
 251          *      IPv6 multicast router mode is now supported ;)
 252          */
 253         if (ipv6_devconf.mc_forwarding &&
 254             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 255                 /*
 256                  * Okay, we try to forward - split and duplicate
 257                  * packets.
 258                  */
 259                 struct sk_buff *skb2;
 260                 struct inet6_skb_parm *opt = IP6CB(skb);
 261
 262                 /* Check for MLD */
 263                 if (unlikely(opt->ra)) {
 264                         /* Check if this is a mld message */
 265                         u8 *ptr = skb_network_header(skb) + opt->ra;
 266                         struct icmp6hdr *icmp6;
 267                         u8 nexthdr = hdr->nexthdr;
 268                         int offset;
 269
 270                         /* Check if the value of Router Alert
 271                          * is for MLD (0x0000).
 272                          */
 273                         if ((ptr[2] | ptr[3]) == 0) {
 274                                 deliver = 0;
 275
 276                                 if (!ipv6_ext_hdr(nexthdr)) {
 277                                         /* BUG */
 278                                         goto out;
 279                                 }
 280                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 281                                                           &nexthdr);
 282                                 if (offset < 0)
 283                                         goto out;
 284
 285                                 if (nexthdr != IPPROTO_ICMPV6)
 286                                         goto out;
 287
 288                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 289                                                    offset + 1 - skb->data)))
 290                                         goto out;
 291
 292                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 293
 294                                 switch (icmp6->icmp6_type) {
 295                                 case ICMPV6_MGM_QUERY:
 296                                 case ICMPV6_MGM_REPORT:
 297                                 case ICMPV6_MGM_REDUCTION:
 298                                 case ICMPV6_MLD2_REPORT:
 299                                         deliver = 1;
 300                                         break;
 301                                 }
 302                                 goto out;
 303                         }
 304                         /* unknown RA - process it normally */
 305                 }
 306
 307                 if (deliver)
 308                         skb2 = skb_clone(skb, GFP_ATOMIC);
 309                 else {
 310                         skb2 = skb;
 311                         skb = NULL;
 312                 }
 313
 314                 if (skb2) {
 315                         skb2->dev = skb2->dst->dev;
 316                         ip6_mr_input(skb2);
 317                 }
 318         }
 319 out:
 320 #endif
 321         if (likely(deliver))
 322                 ip6_input(skb);
 323         else {
 324                 /* discard */
 325                 kfree_skb(skb);
 326         }
 327
 328         return 0;
 329 }