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 #include <net/inet_ecn.h>
  48
  49 int ip6_rcv_finish(struct sock *sk, struct sk_buff *skb)
  50 {
  51         if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
  52                 const struct inet6_protocol *ipprot;
  53
  54                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
  55                 if (ipprot && ipprot->early_demux)
  56                         ipprot->early_demux(skb);
  57         }
  58         if (!skb_dst(skb))
  59                 ip6_route_input(skb);
  60
  61         return dst_input(skb);
  62 }
  63
  64 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  65 {
  66         const struct ipv6hdr *hdr;
  67         u32 pkt_len;
  68         struct inet6_dev *idev;
  69         struct net *net = dev_net(skb->dev);
  70
  71         if (skb->pkt_type == PACKET_OTHERHOST) {
  72                 kfree_skb(skb);
  73                 return NET_RX_DROP;
  74         }
  75
  76         rcu_read_lock();
  77
  78         idev = __in6_dev_get(skb->dev);
  79
  80         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  81
  82         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  83             !idev || unlikely(idev->cnf.disable_ipv6)) {
  84                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  85                 goto drop;
  86         }
  87
  88         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  89
  90         /*
  91          * Store incoming device index. When the packet will
  92          * be queued, we cannot refer to skb->dev anymore.
  93          *
  94          * BTW, when we send a packet for our own local address on a
  95          * non-loopback interface (e.g. ethX), it is being delivered
  96          * via the loopback interface (lo) here; skb->dev = loopback_dev.
  97          * It, however, should be considered as if it is being
  98          * arrived via the sending interface (ethX), because of the
  99          * nature of scoping architecture. --yoshfuji
 100          */
 101         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 102
 103         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 104                 goto err;
 105
 106         hdr = ipv6_hdr(skb);
 107
 108         if (hdr->version != 6)
 109                 goto err;
 110
 111         IP6_ADD_STATS_BH(dev_net(dev), idev,
 112                          IPSTATS_MIB_NOECTPKTS +
 113                                 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
 114                          max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
 115         /*
 116          * RFC4291 2.5.3
 117          * A packet received on an interface with a destination address
 118          * of loopback must be dropped.
 119          */
 120         if (!(dev->flags & IFF_LOOPBACK) &&
 121             ipv6_addr_loopback(&hdr->daddr))
 122                 goto err;
 123
 124         /* RFC4291 Errata ID: 3480
 125          * Interface-Local scope spans only a single interface on a
 126          * node and is useful only for loopback transmission of
 127          * multicast.  Packets with interface-local scope received
 128          * from another node must be discarded.
 129          */
 130         if (!(skb->pkt_type == PACKET_LOOPBACK ||
 131               dev->flags & IFF_LOOPBACK) &&
 132             ipv6_addr_is_multicast(&hdr->daddr) &&
 133             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
 134                 goto err;
 135
 136         /* RFC4291 2.7
 137          * Nodes must not originate a packet to a multicast address whose scope
 138          * field contains the reserved value 0; if such a packet is received, it
 139          * must be silently dropped.
 140          */
 141         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 142             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
 143                 goto err;
 144
 145         /*
 146          * RFC4291 2.7
 147          * Multicast addresses must not be used as source addresses in IPv6
 148          * packets or appear in any Routing header.
 149          */
 150         if (ipv6_addr_is_multicast(&hdr->saddr))
 151                 goto err;
 152
 153         skb->transport_header = skb->network_header + sizeof(*hdr);
 154         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 155
 156         pkt_len = ntohs(hdr->payload_len);
 157
 158         /* pkt_len may be zero if Jumbo payload option is present */
 159         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 160                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 161                         IP6_INC_STATS_BH(net,
 162                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 163                         goto drop;
 164                 }
 165                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 166                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 167                         goto drop;
 168                 }
 169                 hdr = ipv6_hdr(skb);
 170         }
 171
 172         if (hdr->nexthdr == NEXTHDR_HOP) {
 173                 if (ipv6_parse_hopopts(skb) < 0) {
 174                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 175                         rcu_read_unlock();
 176                         return NET_RX_DROP;
 177                 }
 178         }
 179
 180         rcu_read_unlock();
 181
 182         /* Must drop socket now because of tproxy. */
 183         skb_orphan(skb);
 184
 185         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, NULL, skb,
 186                        dev, NULL,
 187                        ip6_rcv_finish);
 188 err:
 189         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 190 drop:
 191         rcu_read_unlock();
 192         kfree_skb(skb);
 193         return NET_RX_DROP;
 194 }
 195
 196 /*
 197  *      Deliver the packet to the host
 198  */
 199
 200
 201 static int ip6_input_finish(struct sock *sk, struct sk_buff *skb)
 202 {
 203         struct net *net = dev_net(skb_dst(skb)->dev);
 204         const struct inet6_protocol *ipprot;
 205         struct inet6_dev *idev;
 206         unsigned int nhoff;
 207         int nexthdr;
 208         bool raw;
 209
 210         /*
 211          *      Parse extension headers
 212          */
 213
 214         rcu_read_lock();
 215 resubmit:
 216         idev = ip6_dst_idev(skb_dst(skb));
 217         if (!pskb_pull(skb, skb_transport_offset(skb)))
 218                 goto discard;
 219         nhoff = IP6CB(skb)->nhoff;
 220         nexthdr = skb_network_header(skb)[nhoff];
 221
 222         raw = raw6_local_deliver(skb, nexthdr);
 223         ipprot = rcu_dereference(inet6_protos[nexthdr]);
 224         if (ipprot) {
 225                 int ret;
 226
 227                 if (ipprot->flags & INET6_PROTO_FINAL) {
 228                         const struct ipv6hdr *hdr;
 229
 230                         /* Free reference early: we don't need it any more,
 231                            and it may hold ip_conntrack module loaded
 232                            indefinitely. */
 233                         nf_reset(skb);
 234
 235                         skb_postpull_rcsum(skb, skb_network_header(skb),
 236                                            skb_network_header_len(skb));
 237                         hdr = ipv6_hdr(skb);
 238                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 239                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 240                             &hdr->saddr) &&
 241                             !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
 242                                 goto discard;
 243                 }
 244                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 245                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 246                         goto discard;
 247
 248                 ret = ipprot->handler(skb);
 249                 if (ret > 0)
 250                         goto resubmit;
 251                 else if (ret == 0)
 252                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 253         } else {
 254                 if (!raw) {
 255                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 256                                 IP6_INC_STATS_BH(net, idev,
 257                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 258                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 259                                             ICMPV6_UNK_NEXTHDR, nhoff);
 260                         }
 261                         kfree_skb(skb);
 262                 } else {
 263                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 264                         consume_skb(skb);
 265                 }
 266         }
 267         rcu_read_unlock();
 268         return 0;
 269
 270 discard:
 271         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 272         rcu_read_unlock();
 273         kfree_skb(skb);
 274         return 0;
 275 }
 276
 277
 278 int ip6_input(struct sk_buff *skb)
 279 {
 280         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, NULL, skb,
 281                        skb->dev, NULL,
 282                        ip6_input_finish);
 283 }
 284
 285 int ip6_mc_input(struct sk_buff *skb)
 286 {
 287         const struct ipv6hdr *hdr;
 288         bool deliver;
 289
 290         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 291                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 292                          skb->len);
 293
 294         hdr = ipv6_hdr(skb);
 295         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 296
 297 #ifdef CONFIG_IPV6_MROUTE
 298         /*
 299          *      IPv6 multicast router mode is now supported ;)
 300          */
 301         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 302             !(ipv6_addr_type(&hdr->daddr) &
 303               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
 304             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 305                 /*
 306                  * Okay, we try to forward - split and duplicate
 307                  * packets.
 308                  */
 309                 struct sk_buff *skb2;
 310                 struct inet6_skb_parm *opt = IP6CB(skb);
 311
 312                 /* Check for MLD */
 313                 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 314                         /* Check if this is a mld message */
 315                         u8 nexthdr = hdr->nexthdr;
 316                         __be16 frag_off;
 317                         int offset;
 318
 319                         /* Check if the value of Router Alert
 320                          * is for MLD (0x0000).
 321                          */
 322                         if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
 323                                 deliver = false;
 324
 325                                 if (!ipv6_ext_hdr(nexthdr)) {
 326                                         /* BUG */
 327                                         goto out;
 328                                 }
 329                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 330                                                           &nexthdr, &frag_off);
 331                                 if (offset < 0)
 332                                         goto out;
 333
 334                                 if (!ipv6_is_mld(skb, nexthdr, offset))
 335                                         goto out;
 336
 337                                 deliver = true;
 338                         }
 339                         /* unknown RA - process it normally */
 340                 }
 341
 342                 if (deliver)
 343                         skb2 = skb_clone(skb, GFP_ATOMIC);
 344                 else {
 345                         skb2 = skb;
 346                         skb = NULL;
 347                 }
 348
 349                 if (skb2) {
 350                         ip6_mr_input(skb2);
 351                 }
 352         }
 353 out:
 354 #endif
 355         if (likely(deliver))
 356                 ip6_input(skb);
 357         else {
 358                 /* discard */
 359                 kfree_skb(skb);
 360         }
 361
 362         return 0;
 363 }