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