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                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
  76                 rcu_read_unlock();
  77                 goto out;
  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         skb->transport_header = skb->network_header + sizeof(*hdr);
 104         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 105
 106         pkt_len = ntohs(hdr->payload_len);
 107
 108         /* pkt_len may be zero if Jumbo payload option is present */
 109         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 110                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 111                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 112                         goto drop;
 113                 }
 114                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 115                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 116                         goto drop;
 117                 }
 118                 hdr = ipv6_hdr(skb);
 119         }
 120
 121         if (hdr->nexthdr == NEXTHDR_HOP) {
 122                 if (ipv6_parse_hopopts(skb) < 0) {
 123                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 124                         rcu_read_unlock();
 125                         return 0;
 126                 }
 127         }
 128
 129         rcu_read_unlock();
 130
 131         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 132                        ip6_rcv_finish);
 133 err:
 134         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 135 drop:
 136         rcu_read_unlock();
 137         kfree_skb(skb);
 138 out:
 139         return 0;
 140 }
 141
 142 /*
 143  *      Deliver the packet to the host
 144  */
 145
 146
 147 static int ip6_input_finish(struct sk_buff *skb)
 148 {
 149         struct inet6_protocol *ipprot;
 150         unsigned int nhoff;
 151         int nexthdr, raw;
 152         u8 hash;
 153         struct inet6_dev *idev;
 154
 155         /*
 156          *      Parse extension headers
 157          */
 158
 159         rcu_read_lock();
 160 resubmit:
 161         idev = ip6_dst_idev(skb->dst);
 162         if (!pskb_pull(skb, skb_transport_offset(skb)))
 163                 goto discard;
 164         nhoff = IP6CB(skb)->nhoff;
 165         nexthdr = skb_network_header(skb)[nhoff];
 166
 167         raw = raw6_local_deliver(skb, nexthdr);
 168
 169         hash = nexthdr & (MAX_INET_PROTOS - 1);
 170         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 171                 int ret;
 172
 173                 if (ipprot->flags & INET6_PROTO_FINAL) {
 174                         struct ipv6hdr *hdr;
 175
 176                         /* Free reference early: we don't need it any more,
 177                            and it may hold ip_conntrack module loaded
 178                            indefinitely. */
 179                         nf_reset(skb);
 180
 181                         skb_postpull_rcsum(skb, skb_network_header(skb),
 182                                            skb_network_header_len(skb));
 183                         hdr = ipv6_hdr(skb);
 184                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 185                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 186                             &hdr->saddr) &&
 187                             !ipv6_is_mld(skb, nexthdr))
 188                                 goto discard;
 189                 }
 190                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 191                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 192                         goto discard;
 193
 194                 ret = ipprot->handler(skb);
 195                 if (ret > 0)
 196                         goto resubmit;
 197                 else if (ret == 0)
 198                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 199         } else {
 200                 if (!raw) {
 201                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 202                                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
 203                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 204                                             ICMPV6_UNK_NEXTHDR, nhoff,
 205                                             skb->dev);
 206                         }
 207                 } else
 208                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 209                 kfree_skb(skb);
 210         }
 211         rcu_read_unlock();
 212         return 0;
 213
 214 discard:
 215         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
 216         rcu_read_unlock();
 217         kfree_skb(skb);
 218         return 0;
 219 }
 220
 221
 222 int ip6_input(struct sk_buff *skb)
 223 {
 224         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 225                        ip6_input_finish);
 226 }
 227
 228 int ip6_mc_input(struct sk_buff *skb)
 229 {
 230         struct ipv6hdr *hdr;
 231         int deliver;
 232
 233         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS);
 234
 235         hdr = ipv6_hdr(skb);
 236         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 237
 238 #ifdef CONFIG_IPV6_MROUTE
 239         /*
 240          *      IPv6 multicast router mode is now supported ;)
 241          */
 242         if (ipv6_devconf.mc_forwarding &&
 243             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 244                 /*
 245                  * Okay, we try to forward - split and duplicate
 246                  * packets.
 247                  */
 248                 struct sk_buff *skb2;
 249                 struct inet6_skb_parm *opt = IP6CB(skb);
 250
 251                 /* Check for MLD */
 252                 if (unlikely(opt->ra)) {
 253                         /* Check if this is a mld message */
 254                         u8 *ptr = skb_network_header(skb) + opt->ra;
 255                         struct icmp6hdr *icmp6;
 256                         u8 nexthdr = hdr->nexthdr;
 257                         int offset;
 258
 259                         /* Check if the value of Router Alert
 260                          * is for MLD (0x0000).
 261                          */
 262                         if ((ptr[2] | ptr[3]) == 0) {
 263                                 deliver = 0;
 264
 265                                 if (!ipv6_ext_hdr(nexthdr)) {
 266                                         /* BUG */
 267                                         goto out;
 268                                 }
 269                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 270                                                           &nexthdr);
 271                                 if (offset < 0)
 272                                         goto out;
 273
 274                                 if (nexthdr != IPPROTO_ICMPV6)
 275                                         goto out;
 276
 277                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 278                                                    offset + 1 - skb->data)))
 279                                         goto out;
 280
 281                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 282
 283                                 switch (icmp6->icmp6_type) {
 284                                 case ICMPV6_MGM_QUERY:
 285                                 case ICMPV6_MGM_REPORT:
 286                                 case ICMPV6_MGM_REDUCTION:
 287                                 case ICMPV6_MLD2_REPORT:
 288                                         deliver = 1;
 289                                         break;
 290                                 }
 291                                 goto out;
 292                         }
 293                         /* unknown RA - process it normally */
 294                 }
 295
 296                 if (deliver)
 297                         skb2 = skb_clone(skb, GFP_ATOMIC);
 298                 else {
 299                         skb2 = skb;
 300                         skb = NULL;
 301                 }
 302
 303                 if (skb2) {
 304                         skb2->dev = skb2->dst->dev;
 305                         ip6_mr_input(skb2);
 306                 }
 307         }
 308 out:
 309 #endif
 310         if (likely(deliver))
 311                 ip6_input(skb);
 312         else {
 313                 /* discard */
 314                 kfree_skb(skb);
 315         }
 316
 317         return 0;
 318 }