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             !idev || unlikely(idev->cnf.disable_ipv6)) {
  76                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
  77                 rcu_read_unlock();
  78                 goto out;
  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 ? ip6_dst_idev(skb->dst)->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(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 122                         goto drop;
 123                 }
 124                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 125                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 126                         goto drop;
 127                 }
 128                 hdr = ipv6_hdr(skb);
 129         }
 130
 131         if (hdr->nexthdr == NEXTHDR_HOP) {
 132                 if (ipv6_parse_hopopts(skb) < 0) {
 133                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 134                         rcu_read_unlock();
 135                         return 0;
 136                 }
 137         }
 138
 139         rcu_read_unlock();
 140
 141         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 142                        ip6_rcv_finish);
 143 err:
 144         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 145 drop:
 146         rcu_read_unlock();
 147         kfree_skb(skb);
 148 out:
 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
 165         /*
 166          *      Parse extension headers
 167          */
 168
 169         rcu_read_lock();
 170 resubmit:
 171         idev = ip6_dst_idev(skb->dst);
 172         if (!pskb_pull(skb, skb_transport_offset(skb)))
 173                 goto discard;
 174         nhoff = IP6CB(skb)->nhoff;
 175         nexthdr = skb_network_header(skb)[nhoff];
 176
 177         raw = raw6_local_deliver(skb, nexthdr);
 178
 179         hash = nexthdr & (MAX_INET_PROTOS - 1);
 180         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 181                 int ret;
 182
 183                 if (ipprot->flags & INET6_PROTO_FINAL) {
 184                         struct ipv6hdr *hdr;
 185
 186                         /* Free reference early: we don't need it any more,
 187                            and it may hold ip_conntrack module loaded
 188                            indefinitely. */
 189                         nf_reset(skb);
 190
 191                         skb_postpull_rcsum(skb, skb_network_header(skb),
 192                                            skb_network_header_len(skb));
 193                         hdr = ipv6_hdr(skb);
 194                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 195                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 196                             &hdr->saddr) &&
 197                             !ipv6_is_mld(skb, nexthdr))
 198                                 goto discard;
 199                 }
 200                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 201                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 202                         goto discard;
 203
 204                 ret = ipprot->handler(skb);
 205                 if (ret > 0)
 206                         goto resubmit;
 207                 else if (ret == 0)
 208                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 209         } else {
 210                 if (!raw) {
 211                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 212                                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
 213                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 214                                             ICMPV6_UNK_NEXTHDR, nhoff,
 215                                             skb->dev);
 216                         }
 217                 } else
 218                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 219                 kfree_skb(skb);
 220         }
 221         rcu_read_unlock();
 222         return 0;
 223
 224 discard:
 225         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
 226         rcu_read_unlock();
 227         kfree_skb(skb);
 228         return 0;
 229 }
 230
 231
 232 int ip6_input(struct sk_buff *skb)
 233 {
 234         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 235                        ip6_input_finish);
 236 }
 237
 238 int ip6_mc_input(struct sk_buff *skb)
 239 {
 240         struct ipv6hdr *hdr;
 241         int deliver;
 242
 243         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS);
 244
 245         hdr = ipv6_hdr(skb);
 246         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 247
 248 #ifdef CONFIG_IPV6_MROUTE
 249         /*
 250          *      IPv6 multicast router mode is now supported ;)
 251          */
 252         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 253             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 254                 /*
 255                  * Okay, we try to forward - split and duplicate
 256                  * packets.
 257                  */
 258                 struct sk_buff *skb2;
 259                 struct inet6_skb_parm *opt = IP6CB(skb);
 260
 261                 /* Check for MLD */
 262                 if (unlikely(opt->ra)) {
 263                         /* Check if this is a mld message */
 264                         u8 *ptr = skb_network_header(skb) + opt->ra;
 265                         struct icmp6hdr *icmp6;
 266                         u8 nexthdr = hdr->nexthdr;
 267                         int offset;
 268
 269                         /* Check if the value of Router Alert
 270                          * is for MLD (0x0000).
 271                          */
 272                         if ((ptr[2] | ptr[3]) == 0) {
 273                                 deliver = 0;
 274
 275                                 if (!ipv6_ext_hdr(nexthdr)) {
 276                                         /* BUG */
 277                                         goto out;
 278                                 }
 279                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 280                                                           &nexthdr);
 281                                 if (offset < 0)
 282                                         goto out;
 283
 284                                 if (nexthdr != IPPROTO_ICMPV6)
 285                                         goto out;
 286
 287                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 288                                                    offset + 1 - skb->data)))
 289                                         goto out;
 290
 291                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 292
 293                                 switch (icmp6->icmp6_type) {
 294                                 case ICMPV6_MGM_QUERY:
 295                                 case ICMPV6_MGM_REPORT:
 296                                 case ICMPV6_MGM_REDUCTION:
 297                                 case ICMPV6_MLD2_REPORT:
 298                                         deliver = 1;
 299                                         break;
 300                                 }
 301                                 goto out;
 302                         }
 303                         /* unknown RA - process it normally */
 304                 }
 305
 306                 if (deliver)
 307                         skb2 = skb_clone(skb, GFP_ATOMIC);
 308                 else {
 309                         skb2 = skb;
 310                         skb = NULL;
 311                 }
 312
 313                 if (skb2) {
 314                         skb2->dev = skb2->dst->dev;
 315                         ip6_mr_input(skb2);
 316                 }
 317         }
 318 out:
 319 #endif
 320         if (likely(deliver))
 321                 ip6_input(skb);
 322         else {
 323                 /* discard */
 324                 kfree_skb(skb);
 325         }
 326
 327         return 0;
 328 }