Pileus Git - ~andy/linux/blob - 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 int ip6_rcv_finish(struct sk_buff *skb)
  51 {
  52         if (sysctl_ip_early_demux && !skb_dst(skb)) {
  53                 const struct inet6_protocol *ipprot;
  54
  55                 rcu_read_lock();
  56                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
  57                 if (ipprot && ipprot->early_demux)
  58                         ipprot->early_demux(skb);
  59                 rcu_read_unlock();
  60         }
  61         if (!skb_dst(skb))
  62                 ip6_route_input(skb);
  63
  64         return dst_input(skb);
  65 }
  66
  67 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  68 {
  69         const struct ipv6hdr *hdr;
  70         u32             pkt_len;
  71         struct inet6_dev *idev;
  72         struct net *net = dev_net(skb->dev);
  73
  74         if (skb->pkt_type == PACKET_OTHERHOST) {
  75                 kfree_skb(skb);
  76                 return NET_RX_DROP;
  77         }
  78
  79         rcu_read_lock();
  80
  81         idev = __in6_dev_get(skb->dev);
  82
  83         IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  84
  85         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  86             !idev || unlikely(idev->cnf.disable_ipv6)) {
  87                 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  88                 goto drop;
  89         }
  90
  91         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  92
  93         /*
  94          * Store incoming device index. When the packet will
  95          * be queued, we cannot refer to skb->dev anymore.
  96          *
  97          * BTW, when we send a packet for our own local address on a
  98          * non-loopback interface (e.g. ethX), it is being delivered
  99          * via the loopback interface (lo) here; skb->dev = loopback_dev.
 100          * It, however, should be considered as if it is being
 101          * arrived via the sending interface (ethX), because of the
 102          * nature of scoping architecture. --yoshfuji
 103          */
 104         IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 105
 106         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 107                 goto err;
 108
 109         hdr = ipv6_hdr(skb);
 110
 111         if (hdr->version != 6)
 112                 goto err;
 113
 114         /*
 115          * RFC4291 2.5.3
 116          * A packet received on an interface with a destination address
 117          * of loopback must be dropped.
 118          */
 119         if (!(dev->flags & IFF_LOOPBACK) &&
 120             ipv6_addr_loopback(&hdr->daddr))
 121                 goto err;
 122
 123         /*
 124          * RFC4291 2.7
 125          * Multicast addresses must not be used as source addresses in IPv6
 126          * packets or appear in any Routing header.
 127          */
 128         if (ipv6_addr_is_multicast(&hdr->saddr))
 129                 goto err;
 130
 131         skb->transport_header = skb->network_header + sizeof(*hdr);
 132         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 133
 134         pkt_len = ntohs(hdr->payload_len);
 135
 136         /* pkt_len may be zero if Jumbo payload option is present */
 137         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 138                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 139                         IP6_INC_STATS_BH(net,
 140                                          idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 141                         goto drop;
 142                 }
 143                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 144                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 145                         goto drop;
 146                 }
 147                 hdr = ipv6_hdr(skb);
 148         }
 149
 150         if (hdr->nexthdr == NEXTHDR_HOP) {
 151                 if (ipv6_parse_hopopts(skb) < 0) {
 152                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 153                         rcu_read_unlock();
 154                         return NET_RX_DROP;
 155                 }
 156         }
 157
 158         rcu_read_unlock();
 159
 160         /* Must drop socket now because of tproxy. */
 161         skb_orphan(skb);
 162
 163         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 164                        ip6_rcv_finish);
 165 err:
 166         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 167 drop:
 168         rcu_read_unlock();
 169         kfree_skb(skb);
 170         return NET_RX_DROP;
 171 }
 172
 173 /*
 174  *      Deliver the packet to the host
 175  */
 176
 177
 178 static int ip6_input_finish(struct sk_buff *skb)
 179 {
 180         struct net *net = dev_net(skb_dst(skb)->dev);
 181         const struct inet6_protocol *ipprot;
 182         struct inet6_dev *idev;
 183         unsigned int nhoff;
 184         int nexthdr;
 185         bool raw;
 186
 187         /*
 188          *      Parse extension headers
 189          */
 190
 191         rcu_read_lock();
 192 resubmit:
 193         idev = ip6_dst_idev(skb_dst(skb));
 194         if (!pskb_pull(skb, skb_transport_offset(skb)))
 195                 goto discard;
 196         nhoff = IP6CB(skb)->nhoff;
 197         nexthdr = skb_network_header(skb)[nhoff];
 198
 199         raw = raw6_local_deliver(skb, nexthdr);
 200         if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
 201                 int ret;
 202
 203                 if (ipprot->flags & INET6_PROTO_FINAL) {
 204                         const struct ipv6hdr *hdr;
 205
 206                         /* Free reference early: we don't need it any more,
 207                            and it may hold ip_conntrack module loaded
 208                            indefinitely. */
 209                         nf_reset(skb);
 210
 211                         skb_postpull_rcsum(skb, skb_network_header(skb),
 212                                            skb_network_header_len(skb));
 213                         hdr = ipv6_hdr(skb);
 214                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 215                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 216                             &hdr->saddr) &&
 217                             !ipv6_is_mld(skb, nexthdr))
 218                                 goto discard;
 219                 }
 220                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 221                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 222                         goto discard;
 223
 224                 ret = ipprot->handler(skb);
 225                 if (ret > 0)
 226                         goto resubmit;
 227                 else if (ret == 0)
 228                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 229         } else {
 230                 if (!raw) {
 231                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 232                                 IP6_INC_STATS_BH(net, idev,
 233                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
 234                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 235                                             ICMPV6_UNK_NEXTHDR, nhoff);
 236                         }
 237                 } else
 238                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 239                 kfree_skb(skb);
 240         }
 241         rcu_read_unlock();
 242         return 0;
 243
 244 discard:
 245         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 246         rcu_read_unlock();
 247         kfree_skb(skb);
 248         return 0;
 249 }
 250
 251
 252 int ip6_input(struct sk_buff *skb)
 253 {
 254         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 255                        ip6_input_finish);
 256 }
 257
 258 int ip6_mc_input(struct sk_buff *skb)
 259 {
 260         const struct ipv6hdr *hdr;
 261         bool deliver;
 262
 263         IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 264                          ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 265                          skb->len);
 266
 267         hdr = ipv6_hdr(skb);
 268         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 269
 270 #ifdef CONFIG_IPV6_MROUTE
 271         /*
 272          *      IPv6 multicast router mode is now supported ;)
 273          */
 274         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 275             !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 276             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 277                 /*
 278                  * Okay, we try to forward - split and duplicate
 279                  * packets.
 280                  */
 281                 struct sk_buff *skb2;
 282                 struct inet6_skb_parm *opt = IP6CB(skb);
 283
 284                 /* Check for MLD */
 285                 if (unlikely(opt->ra)) {
 286                         /* Check if this is a mld message */
 287                         u8 *ptr = skb_network_header(skb) + opt->ra;
 288                         struct icmp6hdr *icmp6;
 289                         u8 nexthdr = hdr->nexthdr;
 290                         __be16 frag_off;
 291                         int offset;
 292
 293                         /* Check if the value of Router Alert
 294                          * is for MLD (0x0000).
 295                          */
 296                         if ((ptr[2] | ptr[3]) == 0) {
 297                                 deliver = false;
 298
 299                                 if (!ipv6_ext_hdr(nexthdr)) {
 300                                         /* BUG */
 301                                         goto out;
 302                                 }
 303                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 304                                                           &nexthdr, &frag_off);
 305                                 if (offset < 0)
 306                                         goto out;
 307
 308                                 if (nexthdr != IPPROTO_ICMPV6)
 309                                         goto out;
 310
 311                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 312                                                    offset + 1 - skb->data)))
 313                                         goto out;
 314
 315                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 316
 317                                 switch (icmp6->icmp6_type) {
 318                                 case ICMPV6_MGM_QUERY:
 319                                 case ICMPV6_MGM_REPORT:
 320                                 case ICMPV6_MGM_REDUCTION:
 321                                 case ICMPV6_MLD2_REPORT:
 322                                         deliver = true;
 323                                         break;
 324                                 }
 325                                 goto out;
 326                         }
 327                         /* unknown RA - process it normally */
 328                 }
 329
 330                 if (deliver)
 331                         skb2 = skb_clone(skb, GFP_ATOMIC);
 332                 else {
 333                         skb2 = skb;
 334                         skb = NULL;
 335                 }
 336
 337                 if (skb2) {
 338                         ip6_mr_input(skb2);
 339                 }
 340         }
 341 out:
 342 #endif
 343         if (likely(deliver))
 344                 ip6_input(skb);
 345         else {
 346                 /* discard */
 347                 kfree_skb(skb);
 348         }
 349
 350         return 0;
 351 }