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 #include <linux/slab.h>
  32
  33 #include <linux/netfilter.h>
  34 #include <linux/netfilter_ipv6.h>
  35
  36 #include <net/sock.h>
  37 #include <net/snmp.h>
  38
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/transp_v6.h>
  42 #include <net/rawv6.h>
  43 #include <net/ndisc.h>
  44 #include <net/ip6_route.h>
  45 #include <net/addrconf.h>
  46 #include <net/xfrm.h>
  47
  48
  49
  50 inline int ip6_rcv_finish( struct sk_buff *skb)
  51 {
  52         if (skb_dst(skb) == NULL)
  53                 ip6_route_input(skb);
  54
  55         return dst_input(skb);
  56 }
  57
  58 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  59 {
  60         const struct ipv6hdr *hdr;
  61         u32             pkt_len;
  62         struct inet6_dev *idev;
  63         struct net *net = dev_net(skb->dev);
  64
  65         if (skb->pkt_type == PACKET_OTHERHOST) {
  66                 kfree_skb(skb);
  67                 return NET_RX_DROP;
  68         }
  69
  70         rcu_read_lock();
  71
  72         idev = __in6_dev_get(skb->dev);
  73
  74         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  75
  76         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  77             !idev || unlikely(idev->cnf.disable_ipv6)) {
  78                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  79                 goto drop;
  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(skb) ? ip6_dst_idev(skb_dst(skb))->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         /*
 115          * RFC4291 2.7
 116          * Multicast addresses must not be used as source addresses in IPv6
 117          * packets or appear in any Routing header.
 118          */
 119         if (ipv6_addr_is_multicast(&hdr->saddr))
 120                 goto err;
 121
 122         skb->transport_header = skb->network_header + sizeof(*hdr);
 123         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 124
 125         pkt_len = ntohs(hdr->payload_len);
 126
 127         /* pkt_len may be zero if Jumbo payload option is present */
 128         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 129                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 130                         IP6_INC_STATS_BH(net,
 131                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 132                         goto drop;
 133                 }
 134                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 135                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 136                         goto drop;
 137                 }
 138                 hdr = ipv6_hdr(skb);
 139         }
 140
 141         if (hdr->nexthdr == NEXTHDR_HOP) {
 142                 if (ipv6_parse_hopopts(skb) < 0) {
 143                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 144                         rcu_read_unlock();
 145                         return NET_RX_DROP;
 146                 }
 147         }
 148
 149         rcu_read_unlock();
 150
 151         /* Must drop socket now because of tproxy. */
 152         skb_orphan(skb);
 153
 154         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 155                        ip6_rcv_finish);
 156 err:
 157         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 158 drop:
 159         rcu_read_unlock();
 160         kfree_skb(skb);
 161         return NET_RX_DROP;
 162 }
 163
 164 /*
 165  *      Deliver the packet to the host
 166  */
 167
 168
 169 static int ip6_input_finish(struct sk_buff *skb)
 170 {
 171         const struct inet6_protocol *ipprot;
 172         unsigned int nhoff;
 173         int nexthdr;
 174         bool raw;
 175         u8 hash;
 176         struct inet6_dev *idev;
 177         struct net *net = dev_net(skb_dst(skb)->dev);
 178
 179         /*
 180          *      Parse extension headers
 181          */
 182
 183         rcu_read_lock();
 184 resubmit:
 185         idev = ip6_dst_idev(skb_dst(skb));
 186         if (!pskb_pull(skb, skb_transport_offset(skb)))
 187                 goto discard;
 188         nhoff = IP6CB(skb)->nhoff;
 189         nexthdr = skb_network_header(skb)[nhoff];
 190
 191         raw = raw6_local_deliver(skb, nexthdr);
 192
 193         hash = nexthdr & (MAX_INET_PROTOS - 1);
 194         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 195                 int ret;
 196
 197                 if (ipprot->flags & INET6_PROTO_FINAL) {
 198                         const struct ipv6hdr *hdr;
 199
 200                         /* Free reference early: we don't need it any more,
 201                            and it may hold ip_conntrack module loaded
 202                            indefinitely. */
 203                         nf_reset(skb);
 204
 205                         skb_postpull_rcsum(skb, skb_network_header(skb),
 206                                            skb_network_header_len(skb));
 207                         hdr = ipv6_hdr(skb);
 208                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 209                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 210                             &hdr->saddr) &&
 211                             !ipv6_is_mld(skb, nexthdr))
 212                                 goto discard;
 213                 }
 214                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 215                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 216                         goto discard;
 217
 218                 ret = ipprot->handler(skb);
 219                 if (ret > 0)
 220                         goto resubmit;
 221                 else if (ret == 0)
 222                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 223         } else {
 224                 if (!raw) {
 225                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 226                                 IP6_INC_STATS_BH(net, idev,
 227                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 228                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 229                                             ICMPV6_UNK_NEXTHDR, nhoff);
 230                         }
 231                 } else
 232                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 233                 kfree_skb(skb);
 234         }
 235         rcu_read_unlock();
 236         return 0;
 237
 238 discard:
 239         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 240         rcu_read_unlock();
 241         kfree_skb(skb);
 242         return 0;
 243 }
 244
 245
 246 int ip6_input(struct sk_buff *skb)
 247 {
 248         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 249                        ip6_input_finish);
 250 }
 251
 252 int ip6_mc_input(struct sk_buff *skb)
 253 {
 254         const struct ipv6hdr *hdr;
 255         bool deliver;
 256
 257         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 258                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 259                          skb->len);
 260
 261         hdr = ipv6_hdr(skb);
 262         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 263
 264 #ifdef CONFIG_IPV6_MROUTE
 265         /*
 266          *      IPv6 multicast router mode is now supported ;)
 267          */
 268         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 269             !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 270             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 271                 /*
 272                  * Okay, we try to forward - split and duplicate
 273                  * packets.
 274                  */
 275                 struct sk_buff *skb2;
 276                 struct inet6_skb_parm *opt = IP6CB(skb);
 277
 278                 /* Check for MLD */
 279                 if (unlikely(opt->ra)) {
 280                         /* Check if this is a mld message */
 281                         u8 *ptr = skb_network_header(skb) + opt->ra;
 282                         struct icmp6hdr *icmp6;
 283                         u8 nexthdr = hdr->nexthdr;
 284                         __be16 frag_off;
 285                         int offset;
 286
 287                         /* Check if the value of Router Alert
 288                          * is for MLD (0x0000).
 289                          */
 290                         if ((ptr[2] | ptr[3]) == 0) {
 291                                 deliver = false;
 292
 293                                 if (!ipv6_ext_hdr(nexthdr)) {
 294                                         /* BUG */
 295                                         goto out;
 296                                 }
 297                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 298                                                           &nexthdr, &frag_off);
 299                                 if (offset < 0)
 300                                         goto out;
 301
 302                                 if (nexthdr != IPPROTO_ICMPV6)
 303                                         goto out;
 304
 305                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 306                                                    offset + 1 - skb->data)))
 307                                         goto out;
 308
 309                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 310
 311                                 switch (icmp6->icmp6_type) {
 312                                 case ICMPV6_MGM_QUERY:
 313                                 case ICMPV6_MGM_REPORT:
 314                                 case ICMPV6_MGM_REDUCTION:
 315                                 case ICMPV6_MLD2_REPORT:
 316                                         deliver = true;
 317                                         break;
 318                                 }
 319                                 goto out;
 320                         }
 321                         /* unknown RA - process it normally */
 322                 }
 323
 324                 if (deliver)
 325                         skb2 = skb_clone(skb, GFP_ATOMIC);
 326                 else {
 327                         skb2 = skb;
 328                         skb = NULL;
 329                 }
 330
 331                 if (skb2) {
 332                         ip6_mr_input(skb2);
 333                 }
 334         }
 335 out:
 336 #endif
 337         if (likely(deliver))
 338                 ip6_input(skb);
 339         else {
 340                 /* discard */
 341                 kfree_skb(skb);
 342         }
 343
 344         return 0;
 345 }