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   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  *      $Id: ip6_input.c,v 1.19 2000/12/13 18:31:50 davem Exp $
  10  *
  11  *      Based in linux/net/ipv4/ip_input.c
  12  *
  13  *      This program is free software; you can redistribute it and/or
  14  *      modify it under the terms of the GNU General Public License
  15  *      as published by the Free Software Foundation; either version
  16  *      2 of the License, or (at your option) any later version.
  17  */
  18 /* Changes
  19  *
  20  *      Mitsuru KANDA @USAGI and
  21  *      YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
  22  */
  23
  24 #include <linux/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.h>
  28 #include <linux/net.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/in6.h>
  31 #include <linux/icmpv6.h>
  32 #include <linux/mroute6.h>
  33
  34 #include <linux/netfilter.h>
  35 #include <linux/netfilter_ipv6.h>
  36
  37 #include <net/sock.h>
  38 #include <net/snmp.h>
  39
  40 #include <net/ipv6.h>
  41 #include <net/protocol.h>
  42 #include <net/transp_v6.h>
  43 #include <net/rawv6.h>
  44 #include <net/ndisc.h>
  45 #include <net/ip6_route.h>
  46 #include <net/addrconf.h>
  47 #include <net/xfrm.h>
  48
  49
  50
  51 inline int ip6_rcv_finish( struct sk_buff *skb)
  52 {
  53         if (skb->dst == NULL)
  54                 ip6_route_input(skb);
  55
  56         return dst_input(skb);
  57 }
  58
  59 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
  60 {
  61         struct ipv6hdr *hdr;
  62         u32             pkt_len;
  63         struct inet6_dev *idev;
  64
  65         if (skb->pkt_type == PACKET_OTHERHOST) {
  66                 kfree_skb(skb);
  67                 return 0;
  68         }
  69
  70         rcu_read_lock();
  71
  72         idev = __in6_dev_get(skb->dev);
  73
  74         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INRECEIVES);
  75
  76         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
  77                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
  78                 rcu_read_unlock();
  79                 goto out;
  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 ? ip6_dst_idev(skb->dst)->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         skb->transport_header = skb->network_header + sizeof(*hdr);
 106         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 107
 108         pkt_len = ntohs(hdr->payload_len);
 109
 110         /* pkt_len may be zero if Jumbo payload option is present */
 111         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 112                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 113                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 114                         goto drop;
 115                 }
 116                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 117                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 118                         goto drop;
 119                 }
 120                 hdr = ipv6_hdr(skb);
 121         }
 122
 123         if (hdr->nexthdr == NEXTHDR_HOP) {
 124                 if (ipv6_parse_hopopts(skb) < 0) {
 125                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 126                         rcu_read_unlock();
 127                         return 0;
 128                 }
 129         }
 130
 131         rcu_read_unlock();
 132
 133         return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 134                        ip6_rcv_finish);
 135 err:
 136         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INHDRERRORS);
 137 drop:
 138         rcu_read_unlock();
 139         kfree_skb(skb);
 140 out:
 141         return 0;
 142 }
 143
 144 /*
 145  *      Deliver the packet to the host
 146  */
 147
 148
 149 static int ip6_input_finish(struct sk_buff *skb)
 150 {
 151         struct inet6_protocol *ipprot;
 152         unsigned int nhoff;
 153         int nexthdr, raw;
 154         u8 hash;
 155         struct inet6_dev *idev;
 156
 157         /*
 158          *      Parse extension headers
 159          */
 160
 161         rcu_read_lock();
 162 resubmit:
 163         idev = ip6_dst_idev(skb->dst);
 164         if (!pskb_pull(skb, skb_transport_offset(skb)))
 165                 goto discard;
 166         nhoff = IP6CB(skb)->nhoff;
 167         nexthdr = skb_network_header(skb)[nhoff];
 168
 169         raw = raw6_local_deliver(skb, nexthdr);
 170
 171         hash = nexthdr & (MAX_INET_PROTOS - 1);
 172         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 173                 int ret;
 174
 175                 if (ipprot->flags & INET6_PROTO_FINAL) {
 176                         struct ipv6hdr *hdr;
 177
 178                         /* Free reference early: we don't need it any more,
 179                            and it may hold ip_conntrack module loaded
 180                            indefinitely. */
 181                         nf_reset(skb);
 182
 183                         skb_postpull_rcsum(skb, skb_network_header(skb),
 184                                            skb_network_header_len(skb));
 185                         hdr = ipv6_hdr(skb);
 186                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 187                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 188                             &hdr->saddr) &&
 189                             !ipv6_is_mld(skb, nexthdr))
 190                                 goto discard;
 191                 }
 192                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 193                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 194                         goto discard;
 195
 196                 ret = ipprot->handler(skb);
 197                 if (ret > 0)
 198                         goto resubmit;
 199                 else if (ret == 0)
 200                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 201         } else {
 202                 if (!raw) {
 203                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 204                                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_INUNKNOWNPROTOS);
 205                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 206                                             ICMPV6_UNK_NEXTHDR, nhoff,
 207                                             skb->dev);
 208                         }
 209                 } else
 210                         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDELIVERS);
 211                 kfree_skb(skb);
 212         }
 213         rcu_read_unlock();
 214         return 0;
 215
 216 discard:
 217         IP6_INC_STATS_BH(idev, IPSTATS_MIB_INDISCARDS);
 218         rcu_read_unlock();
 219         kfree_skb(skb);
 220         return 0;
 221 }
 222
 223
 224 int ip6_input(struct sk_buff *skb)
 225 {
 226         return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 227                        ip6_input_finish);
 228 }
 229
 230 int ip6_mc_input(struct sk_buff *skb)
 231 {
 232         struct ipv6hdr *hdr;
 233         int deliver;
 234
 235         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS);
 236
 237         hdr = ipv6_hdr(skb);
 238         deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 239
 240 #ifdef CONFIG_IPV6_MROUTE
 241         /*
 242          *      IPv6 multicast router mode is now supported ;)
 243          */
 244         if (ipv6_devconf.mc_forwarding &&
 245             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 246                 /*
 247                  * Okay, we try to forward - split and duplicate
 248                  * packets.
 249                  */
 250                 struct sk_buff *skb2;
 251                 struct inet6_skb_parm *opt = IP6CB(skb);
 252
 253                 /* Check for MLD */
 254                 if (unlikely(opt->ra)) {
 255                         /* Check if this is a mld message */
 256                         u8 *ptr = skb_network_header(skb) + opt->ra;
 257                         struct icmp6hdr *icmp6;
 258                         u8 nexthdr = hdr->nexthdr;
 259                         int offset;
 260
 261                         /* Check if the value of Router Alert
 262                          * is for MLD (0x0000).
 263                          */
 264                         if ((ptr[2] | ptr[3]) == 0) {
 265                                 deliver = 0;
 266
 267                                 if (!ipv6_ext_hdr(nexthdr)) {
 268                                         /* BUG */
 269                                         goto out;
 270                                 }
 271                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 272                                                           &nexthdr);
 273                                 if (offset < 0)
 274                                         goto out;
 275
 276                                 if (nexthdr != IPPROTO_ICMPV6)
 277                                         goto out;
 278
 279                                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 280                                                    offset + 1 - skb->data)))
 281                                         goto out;
 282
 283                                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 284
 285                                 switch (icmp6->icmp6_type) {
 286                                 case ICMPV6_MGM_QUERY:
 287                                 case ICMPV6_MGM_REPORT:
 288                                 case ICMPV6_MGM_REDUCTION:
 289                                 case ICMPV6_MLD2_REPORT:
 290                                         deliver = 1;
 291                                         break;
 292                                 }
 293                                 goto out;
 294                         }
 295                         /* unknown RA - process it normally */
 296                 }
 297
 298                 if (deliver)
 299                         skb2 = skb_clone(skb, GFP_ATOMIC);
 300                 else {
 301                         skb2 = skb;
 302                         skb = NULL;
 303                 }
 304
 305                 if (skb2) {
 306                         skb2->dev = skb2->dst->dev;
 307                         ip6_mr_input(skb2);
 308                 }
 309         }
 310 out:
 311 #endif
 312         if (likely(deliver))
 313                 ip6_input(skb);
 314         else {
 315                 /* discard */
 316                 kfree_skb(skb);
 317         }
 318
 319         return 0;
 320 }