ip6_input.c

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/*
 *  IPv6 input
 *  Linux INET6 implementation
 *
 *  Authors:
 *  Pedro Roque     <[email protected]>
 *  Ian P. Morris       <[email protected]>
 *
 *  Based in linux/net/ipv4/ip_input.c
 *
 *  This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
/* Changes
 *
 *  Mitsuru KANDA @USAGI and
 *  YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/icmpv6.h>
#include <linux/mroute6.h>
#include <linux/slab.h>

#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>

#include <net/sock.h>
#include <net/snmp.h>

#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/rawv6.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/xfrm.h>



int ip6_rcv_finish(struct sk_buff *skb)
{
    if (sysctl_ip_early_demux && !skb_dst(skb)) {
        const struct inet6_protocol *ipprot;

        ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
        if (ipprot && ipprot->early_demux)
            ipprot->early_demux(skb);
    }
    if (!skb_dst(skb))
        ip6_route_input(skb);

    return dst_input(skb);
}

int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
    const struct ipv6hdr *hdr;
    u32         pkt_len;
    struct inet6_dev *idev;
    struct net *net = dev_net(skb->dev);

    if (skb->pkt_type == PACKET_OTHERHOST) {
        kfree_skb(skb);
        return NET_RX_DROP;
    }

    rcu_read_lock();

    idev = __in6_dev_get(skb->dev);

    IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);

    if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
        !idev || unlikely(idev->cnf.disable_ipv6)) {
        IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
        goto drop;
    }

    memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

    /*
     * Store incoming device index. When the packet will
     * be queued, we cannot refer to skb->dev anymore.
     *
     * BTW, when we send a packet for our own local address on a
     * non-loopback interface (e.g. ethX), it is being delivered
     * via the loopback interface (lo) here; skb->dev = loopback_dev.
     * It, however, should be considered as if it is being
     * arrived via the sending interface (ethX), because of the
     * nature of scoping architecture. --yoshfuji
     */
    IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

    if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
        goto err;

    hdr = ipv6_hdr(skb);

    if (hdr->version != 6)
        goto err;

    /*
     * RFC4291 2.5.3
     * A packet received on an interface with a destination address
     * of loopback must be dropped.
     */
    if (!(dev->flags & IFF_LOOPBACK) &&
        ipv6_addr_loopback(&hdr->daddr))
        goto err;

    /*
     * RFC4291 2.7
     * Multicast addresses must not be used as source addresses in IPv6
     * packets or appear in any Routing header.
     */
    if (ipv6_addr_is_multicast(&hdr->saddr))
        goto err;

    skb->transport_header = skb->network_header + sizeof(*hdr);
    IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

    pkt_len = ntohs(hdr->payload_len);

    /* pkt_len may be zero if Jumbo payload option is present */
    if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
        if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
            IP6_INC_STATS_BH(net,
                     idev, IPSTATS_MIB_INTRUNCATEDPKTS);
            goto drop;
        }
        if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
            IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
            goto drop;
        }
        hdr = ipv6_hdr(skb);
    }

    if (hdr->nexthdr == NEXTHDR_HOP) {
        if (ipv6_parse_hopopts(skb) < 0) {
            IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
            rcu_read_unlock();
            return NET_RX_DROP;
        }
    }

    rcu_read_unlock();

    /* Must drop socket now because of tproxy. */
    skb_orphan(skb);

    return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
               ip6_rcv_finish);
err:
    IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
drop:
    rcu_read_unlock();
    kfree_skb(skb);
    return NET_RX_DROP;
}

/*
 *  Deliver the packet to the host
 */


static int ip6_input_finish(struct sk_buff *skb)
{
    struct net *net = dev_net(skb_dst(skb)->dev);
    const struct inet6_protocol *ipprot;
    struct inet6_dev *idev;
    unsigned int nhoff;
    int nexthdr;
    bool raw;

    /*
     *  Parse extension headers
     */

    rcu_read_lock();
resubmit:
    idev = ip6_dst_idev(skb_dst(skb));
    if (!pskb_pull(skb, skb_transport_offset(skb)))
        goto discard;
    nhoff = IP6CB(skb)->nhoff;
    nexthdr = skb_network_header(skb)[nhoff];

    raw = raw6_local_deliver(skb, nexthdr);
    if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
        int ret;

        if (ipprot->flags & INET6_PROTO_FINAL) {
            const struct ipv6hdr *hdr;

            /* Free reference early: we don't need it any more,
               and it may hold ip_conntrack module loaded
               indefinitely. */
            nf_reset(skb);

            skb_postpull_rcsum(skb, skb_network_header(skb),
                       skb_network_header_len(skb));
            hdr = ipv6_hdr(skb);
            if (ipv6_addr_is_multicast(&hdr->daddr) &&
                !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
                &hdr->saddr) &&
                !ipv6_is_mld(skb, nexthdr))
                goto discard;
        }
        if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
            !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
            goto discard;

        ret = ipprot->handler(skb);
        if (ret > 0)
            goto resubmit;
        else if (ret == 0)
            IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
    } else {
        if (!raw) {
            if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
                IP6_INC_STATS_BH(net, idev,
                         IPSTATS_MIB_INUNKNOWNPROTOS);
                icmpv6_send(skb, ICMPV6_PARAMPROB,
                        ICMPV6_UNK_NEXTHDR, nhoff);
            }
        } else
            IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
        kfree_skb(skb);
    }
    rcu_read_unlock();
    return 0;

discard:
    IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
    rcu_read_unlock();
    kfree_skb(skb);
    return 0;
}


int ip6_input(struct sk_buff *skb)
{
    return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
               ip6_input_finish);
}

int ip6_mc_input(struct sk_buff *skb)
{
    const struct ipv6hdr *hdr;
    bool deliver;

    IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
             ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
             skb->len);

    hdr = ipv6_hdr(skb);
    deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);

#ifdef CONFIG_IPV6_MROUTE
    /*
     *      IPv6 multicast router mode is now supported ;)
     */
    if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
        !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
        likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
        /*
         * Okay, we try to forward - split and duplicate
         * packets.
         */
        struct sk_buff *skb2;
        struct inet6_skb_parm *opt = IP6CB(skb);

        /* Check for MLD */
        if (unlikely(opt->ra)) {
            /* Check if this is a mld message */
            u8 *ptr = skb_network_header(skb) + opt->ra;
            struct icmp6hdr *icmp6;
            u8 nexthdr = hdr->nexthdr;
            __be16 frag_off;
            int offset;

            /* Check if the value of Router Alert
             * is for MLD (0x0000).
             */
            if ((ptr[2] | ptr[3]) == 0) {
                deliver = false;

                if (!ipv6_ext_hdr(nexthdr)) {
                    /* BUG */
                    goto out;
                }
                offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
                              &nexthdr, &frag_off);
                if (offset < 0)
                    goto out;

                if (nexthdr != IPPROTO_ICMPV6)
                    goto out;

                if (!pskb_may_pull(skb, (skb_network_header(skb) +
                           offset + 1 - skb->data)))
                    goto out;

                icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);

                switch (icmp6->icmp6_type) {
                case ICMPV6_MGM_QUERY:
                case ICMPV6_MGM_REPORT:
                case ICMPV6_MGM_REDUCTION:
                case ICMPV6_MLD2_REPORT:
                    deliver = true;
                    break;
                }
                goto out;
            }
            /* unknown RA - process it normally */
        }

        if (deliver)
            skb2 = skb_clone(skb, GFP_ATOMIC);
        else {
            skb2 = skb;
            skb = NULL;
        }

        if (skb2) {
            ip6_mr_input(skb2);
        }
    }
out:
#endif
    if (likely(deliver))
        ip6_input(skb);
    else {
        /* discard */
        kfree_skb(skb);
    }

    return 0;
}