LXR linux/net/ipv6/ip6

   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
  49inline int ip6_rcv_finish( struct sk_buff *skb)
  50{
  51        if (skb_dst(skb) == NULL)
  52                ip6_route_input(skb);
  53
  54        return dst_input(skb);
  55}
  56
  57int 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        struct net *net = dev_net(skb->dev);
  63
  64        if (skb->pkt_type == PACKET_OTHERHOST) {
  65                kfree_skb(skb);
  66                return NET_RX_DROP;
  67        }
  68
  69        rcu_read_lock();
  70
  71        idev = __in6_dev_get(skb->dev);
  72
  73        IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);
  74
  75        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
  76            !idev || unlikely(idev->cnf.disable_ipv6)) {
  77                IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
  78                goto drop;
  79        }
  80
  81        memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
  82
  83        /*
  84         * Store incoming device index. When the packet will
  85         * be queued, we cannot refer to skb->dev anymore.
  86         *
  87         * BTW, when we send a packet for our own local address on a
  88         * non-loopback interface (e.g. ethX), it is being delivered
  89         * via the loopback interface (lo) here; skb->dev = loopback_dev.
  90         * It, however, should be considered as if it is being
  91         * arrived via the sending interface (ethX), because of the
  92         * nature of scoping architecture. --yoshfuji
  93         */
  94        IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
  95
  96        if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
  97                goto err;
  98
  99        hdr = ipv6_hdr(skb);
 100
 101        if (hdr->version != 6)
 102                goto err;
 103
 104        /*
 105         * RFC4291 2.5.3
 106         * A packet received on an interface with a destination address
 107         * of loopback must be dropped.
 108         */
 109        if (!(dev->flags & IFF_LOOPBACK) &&
 110            ipv6_addr_loopback(&hdr->daddr))
 111                goto err;
 112
 113        skb->transport_header = skb->network_header + sizeof(*hdr);
 114        IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 115
 116        pkt_len = ntohs(hdr->payload_len);
 117
 118        /* pkt_len may be zero if Jumbo payload option is present */
 119        if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 120                if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 121                        IP6_INC_STATS_BH(net,
 122                                         idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 123                        goto drop;
 124                }
 125                if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 126                        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 127                        goto drop;
 128                }
 129                hdr = ipv6_hdr(skb);
 130        }
 131
 132        if (hdr->nexthdr == NEXTHDR_HOP) {
 133                if (ipv6_parse_hopopts(skb) < 0) {
 134                        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 135                        rcu_read_unlock();
 136                        return NET_RX_DROP;
 137                }
 138        }
 139
 140        rcu_read_unlock();
 141
 142        /* Must drop socket now because of tproxy. */
 143        skb_orphan(skb);
 144
 145        return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 146                       ip6_rcv_finish);
 147err:
 148        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
 149drop:
 150        rcu_read_unlock();
 151        kfree_skb(skb);
 152        return NET_RX_DROP;
 153}
 154
 155/*
 156 *      Deliver the packet to the host
 157 */
 158
 159
 160static int ip6_input_finish(struct sk_buff *skb)
 161{
 162        const struct inet6_protocol *ipprot;
 163        unsigned int nhoff;
 164        int nexthdr, raw;
 165        u8 hash;
 166        struct inet6_dev *idev;
 167        struct net *net = dev_net(skb_dst(skb)->dev);
 168
 169        /*
 170         *      Parse extension headers
 171         */
 172
 173        rcu_read_lock();
 174resubmit:
 175        idev = ip6_dst_idev(skb_dst(skb));
 176        if (!pskb_pull(skb, skb_transport_offset(skb)))
 177                goto discard;
 178        nhoff = IP6CB(skb)->nhoff;
 179        nexthdr = skb_network_header(skb)[nhoff];
 180
 181        raw = raw6_local_deliver(skb, nexthdr);
 182
 183        hash = nexthdr & (MAX_INET_PROTOS - 1);
 184        if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
 185                int ret;
 186
 187                if (ipprot->flags & INET6_PROTO_FINAL) {
 188                        struct ipv6hdr *hdr;
 189
 190                        /* Free reference early: we don't need it any more,
 191                           and it may hold ip_conntrack module loaded
 192                           indefinitely. */
 193                        nf_reset(skb);
 194
 195                        skb_postpull_rcsum(skb, skb_network_header(skb),
 196                                           skb_network_header_len(skb));
 197                        hdr = ipv6_hdr(skb);
 198                        if (ipv6_addr_is_multicast(&hdr->daddr) &&
 199                            !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 200                            &hdr->saddr) &&
 201                            !ipv6_is_mld(skb, nexthdr))
 202                                goto discard;
 203                }
 204                if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 205                    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 206                        goto discard;
 207
 208                ret = ipprot->handler(skb);
 209                if (ret > 0)
 210                        goto resubmit;
 211                else if (ret == 0)
 212                        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 213        } else {
 214                if (!raw) {
 215                        if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 216                                IP6_INC_STATS_BH(net, idev,
 217                                                 IPSTATS_MIB_INUNKNOWNPROTOS);
 218                                icmpv6_send(skb, ICMPV6_PARAMPROB,
 219                                            ICMPV6_UNK_NEXTHDR, nhoff,
 220                                            skb->dev);
 221                        }
 222                } else
 223                        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
 224                kfree_skb(skb);
 225        }
 226        rcu_read_unlock();
 227        return 0;
 228
 229discard:
 230        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
 231        rcu_read_unlock();
 232        kfree_skb(skb);
 233        return 0;
 234}
 235
 236
 237int ip6_input(struct sk_buff *skb)
 238{
 239        return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 240                       ip6_input_finish);
 241}
 242
 243int ip6_mc_input(struct sk_buff *skb)
 244{
 245        struct ipv6hdr *hdr;
 246        int deliver;
 247
 248        IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
 249                         ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 250                         skb->len);
 251
 252        hdr = ipv6_hdr(skb);
 253        deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
 254
 255#ifdef CONFIG_IPV6_MROUTE
 256        /*
 257         *      IPv6 multicast router mode is now supported ;)
 258         */
 259        if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 260            !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
 261            likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 262                /*
 263                 * Okay, we try to forward - split and duplicate
 264                 * packets.
 265                 */
 266                struct sk_buff *skb2;
 267                struct inet6_skb_parm *opt = IP6CB(skb);
 268
 269                /* Check for MLD */
 270                if (unlikely(opt->ra)) {
 271                        /* Check if this is a mld message */
 272                        u8 *ptr = skb_network_header(skb) + opt->ra;
 273                        struct icmp6hdr *icmp6;
 274                        u8 nexthdr = hdr->nexthdr;
 275                        int offset;
 276
 277                        /* Check if the value of Router Alert
 278                         * is for MLD (0x0000).
 279                         */
 280                        if ((ptr[2] | ptr[3]) == 0) {
 281                                deliver = 0;
 282
 283                                if (!ipv6_ext_hdr(nexthdr)) {
 284                                        /* BUG */
 285                                        goto out;
 286                                }
 287                                offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 288                                                          &nexthdr);
 289                                if (offset < 0)
 290                                        goto out;
 291
 292                                if (nexthdr != IPPROTO_ICMPV6)
 293                                        goto out;
 294
 295                                if (!pskb_may_pull(skb, (skb_network_header(skb) +
 296                                                   offset + 1 - skb->data)))
 297                                        goto out;
 298
 299                                icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 300
 301                                switch (icmp6->icmp6_type) {
 302                                case ICMPV6_MGM_QUERY:
 303                                case ICMPV6_MGM_REPORT:
 304                                case ICMPV6_MGM_REDUCTION:
 305                                case ICMPV6_MLD2_REPORT:
 306                                        deliver = 1;
 307                                        break;
 308                                }
 309                                goto out;
 310                        }
 311                        /* unknown RA - process it normally */
 312                }
 313
 314                if (deliver)
 315                        skb2 = skb_clone(skb, GFP_ATOMIC);
 316                else {
 317                        skb2 = skb;
 318                        skb = NULL;
 319                }
 320
 321                if (skb2) {
 322                        ip6_mr_input(skb2);
 323                }
 324        }
 325out:
 326#endif
 327        if (likely(deliver))
 328                ip6_input(skb);
 329        else {
 330                /* discard */
 331                kfree_skb(skb);
 332        }
 333
 334        return 0;
 335}
 336