ipmr.c

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/*
 *  IP multicast routing support for mrouted 3.6/3.8
 *
 *      (c) 1995 Alan Cox, <[email protected]>
 *    Linux Consultancy and Custom Driver Development
 *
 *  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.
 *
 *  Fixes:
 *  Michael Chastain    :   Incorrect size of copying.
 *  Alan Cox        :   Added the cache manager code
 *  Alan Cox        :   Fixed the clone/copy bug and device race.
 *  Mike McLagan        :   Routing by source
 *  Malcolm Beattie     :   Buffer handling fixes.
 *  Alexey Kuznetsov    :   Double buffer free and other fixes.
 *  SVR Anand       :   Fixed several multicast bugs and problems.
 *  Alexey Kuznetsov    :   Status, optimisations and more.
 *  Brad Parker     :   Better behaviour on mrouted upcall
 *                  overflow.
 *      Carlos Picoto           :       PIMv1 Support
 *  Pavlin Ivanov Radoslavov:   PIMv2 Registers must checksum only PIM header
 *                  Relax this requirement to work with older peers.
 *
 */

#include <asm/uaccess.h>
#include <linux/types.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/mroute.h>
#include <linux/init.h>
#include <linux/if_ether.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <linux/notifier.h>
#include <linux/if_arp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/compat.h>
#include <linux/export.h>
#include <net/ipip.h>
#include <net/checksum.h>
#include <net/netlink.h>
#include <net/fib_rules.h>

#if defined(CONFIG_IP_PIMSM_V1) || defined(CONFIG_IP_PIMSM_V2)
#define CONFIG_IP_PIMSM 1
#endif

struct mr_table {
    struct list_head    list;
#ifdef CONFIG_NET_NS
    struct net      *net;
#endif
    u32         id;
    struct sock __rcu   *mroute_sk;
    struct timer_list   ipmr_expire_timer;
    struct list_head    mfc_unres_queue;
    struct list_head    mfc_cache_array[MFC_LINES];
    struct vif_device   vif_table[MAXVIFS];
    int         maxvif;
    atomic_t        cache_resolve_queue_len;
    int         mroute_do_assert;
    int         mroute_do_pim;
#if defined(CONFIG_IP_PIMSM_V1) || defined(CONFIG_IP_PIMSM_V2)
    int         mroute_reg_vif_num;
#endif
};

struct ipmr_rule {
    struct fib_rule     common;
};

struct ipmr_result {
    struct mr_table     *mrt;
};

/* Big lock, protecting vif table, mrt cache and mroute socket state.
 * Note that the changes are semaphored via rtnl_lock.
 */

static DEFINE_RWLOCK(mrt_lock);

/*
 *  Multicast router control variables
 */

#define VIF_EXISTS(_mrt, _idx) ((_mrt)->vif_table[_idx].dev != NULL)

/* Special spinlock for queue of unresolved entries */
static DEFINE_SPINLOCK(mfc_unres_lock);

/* We return to original Alan's scheme. Hash table of resolved
 * entries is changed only in process context and protected
 * with weak lock mrt_lock. Queue of unresolved entries is protected
 * with strong spinlock mfc_unres_lock.
 *
 * In this case data path is free of exclusive locks at all.
 */

static struct kmem_cache *mrt_cachep __read_mostly;

static struct mr_table *ipmr_new_table(struct net *net, u32 id);
static void ipmr_free_table(struct mr_table *mrt);

static int ip_mr_forward(struct net *net, struct mr_table *mrt,
             struct sk_buff *skb, struct mfc_cache *cache,
             int local);
static int ipmr_cache_report(struct mr_table *mrt,
                 struct sk_buff *pkt, vifi_t vifi, int assert);
static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
                  struct mfc_cache *c, struct rtmsg *rtm);
static void mroute_clean_tables(struct mr_table *mrt);
static void ipmr_expire_process(unsigned long arg);

#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
#define ipmr_for_each_table(mrt, net) \
    list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list)

static struct mr_table *ipmr_get_table(struct net *net, u32 id)
{
    struct mr_table *mrt;

    ipmr_for_each_table(mrt, net) {
        if (mrt->id == id)
            return mrt;
    }
    return NULL;
}

static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
               struct mr_table **mrt)
{
    struct ipmr_result res;
    struct fib_lookup_arg arg = { .result = &res, };
    int err;

    err = fib_rules_lookup(net->ipv4.mr_rules_ops,
                   flowi4_to_flowi(flp4), 0, &arg);
    if (err < 0)
        return err;
    *mrt = res.mrt;
    return 0;
}

static int ipmr_rule_action(struct fib_rule *rule, struct flowi *flp,
                int flags, struct fib_lookup_arg *arg)
{
    struct ipmr_result *res = arg->result;
    struct mr_table *mrt;

    switch (rule->action) {
    case FR_ACT_TO_TBL:
        break;
    case FR_ACT_UNREACHABLE:
        return -ENETUNREACH;
    case FR_ACT_PROHIBIT:
        return -EACCES;
    case FR_ACT_BLACKHOLE:
    default:
        return -EINVAL;
    }

    mrt = ipmr_get_table(rule->fr_net, rule->table);
    if (mrt == NULL)
        return -EAGAIN;
    res->mrt = mrt;
    return 0;
}

static int ipmr_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
{
    return 1;
}

static const struct nla_policy ipmr_rule_policy[FRA_MAX + 1] = {
    FRA_GENERIC_POLICY,
};

static int ipmr_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
                   struct fib_rule_hdr *frh, struct nlattr **tb)
{
    return 0;
}

static int ipmr_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
                 struct nlattr **tb)
{
    return 1;
}

static int ipmr_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
              struct fib_rule_hdr *frh)
{
    frh->dst_len = 0;
    frh->src_len = 0;
    frh->tos     = 0;
    return 0;
}

static const struct fib_rules_ops __net_initconst ipmr_rules_ops_template = {
    .family     = RTNL_FAMILY_IPMR,
    .rule_size  = sizeof(struct ipmr_rule),
    .addr_size  = sizeof(u32),
    .action     = ipmr_rule_action,
    .match      = ipmr_rule_match,
    .configure  = ipmr_rule_configure,
    .compare    = ipmr_rule_compare,
    .default_pref   = fib_default_rule_pref,
    .fill       = ipmr_rule_fill,
    .nlgroup    = RTNLGRP_IPV4_RULE,
    .policy     = ipmr_rule_policy,
    .owner      = THIS_MODULE,
};

static int __net_init ipmr_rules_init(struct net *net)
{
    struct fib_rules_ops *ops;
    struct mr_table *mrt;
    int err;

    ops = fib_rules_register(&ipmr_rules_ops_template, net);
    if (IS_ERR(ops))
        return PTR_ERR(ops);

    INIT_LIST_HEAD(&net->ipv4.mr_tables);

    mrt = ipmr_new_table(net, RT_TABLE_DEFAULT);
    if (mrt == NULL) {
        err = -ENOMEM;
        goto err1;
    }

    err = fib_default_rule_add(ops, 0x7fff, RT_TABLE_DEFAULT, 0);
    if (err < 0)
        goto err2;

    net->ipv4.mr_rules_ops = ops;
    return 0;

err2:
    kfree(mrt);
err1:
    fib_rules_unregister(ops);
    return err;
}

static void __net_exit ipmr_rules_exit(struct net *net)
{
    struct mr_table *mrt, *next;

    list_for_each_entry_safe(mrt, next, &net->ipv4.mr_tables, list) {
        list_del(&mrt->list);
        ipmr_free_table(mrt);
    }
    fib_rules_unregister(net->ipv4.mr_rules_ops);
}
#else
#define ipmr_for_each_table(mrt, net) \
    for (mrt = net->ipv4.mrt; mrt; mrt = NULL)

static struct mr_table *ipmr_get_table(struct net *net, u32 id)
{
    return net->ipv4.mrt;
}

static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
               struct mr_table **mrt)
{
    *mrt = net->ipv4.mrt;
    return 0;
}

static int __net_init ipmr_rules_init(struct net *net)
{
    net->ipv4.mrt = ipmr_new_table(net, RT_TABLE_DEFAULT);
    return net->ipv4.mrt ? 0 : -ENOMEM;
}

static void __net_exit ipmr_rules_exit(struct net *net)
{
    ipmr_free_table(net->ipv4.mrt);
}
#endif

static struct mr_table *ipmr_new_table(struct net *net, u32 id)
{
    struct mr_table *mrt;
    unsigned int i;

    mrt = ipmr_get_table(net, id);
    if (mrt != NULL)
        return mrt;

    mrt = kzalloc(sizeof(*mrt), GFP_KERNEL);
    if (mrt == NULL)
        return NULL;
    write_pnet(&mrt->net, net);
    mrt->id = id;

    /* Forwarding cache */
    for (i = 0; i < MFC_LINES; i++)
        INIT_LIST_HEAD(&mrt->mfc_cache_array[i]);

    INIT_LIST_HEAD(&mrt->mfc_unres_queue);

    setup_timer(&mrt->ipmr_expire_timer, ipmr_expire_process,
            (unsigned long)mrt);

#ifdef CONFIG_IP_PIMSM
    mrt->mroute_reg_vif_num = -1;
#endif
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
    list_add_tail_rcu(&mrt->list, &net->ipv4.mr_tables);
#endif
    return mrt;
}

static void ipmr_free_table(struct mr_table *mrt)
{
    del_timer_sync(&mrt->ipmr_expire_timer);
    mroute_clean_tables(mrt);
    kfree(mrt);
}

/* Service routines creating virtual interfaces: DVMRP tunnels and PIMREG */

static void ipmr_del_tunnel(struct net_device *dev, struct vifctl *v)
{
    struct net *net = dev_net(dev);

    dev_close(dev);

    dev = __dev_get_by_name(net, "tunl0");
    if (dev) {
        const struct net_device_ops *ops = dev->netdev_ops;
        struct ifreq ifr;
        struct ip_tunnel_parm p;

        memset(&p, 0, sizeof(p));
        p.iph.daddr = v->vifc_rmt_addr.s_addr;
        p.iph.saddr = v->vifc_lcl_addr.s_addr;
        p.iph.version = 4;
        p.iph.ihl = 5;
        p.iph.protocol = IPPROTO_IPIP;
        sprintf(p.name, "dvmrp%d", v->vifc_vifi);
        ifr.ifr_ifru.ifru_data = (__force void __user *)&p;

        if (ops->ndo_do_ioctl) {
            mm_segment_t oldfs = get_fs();

            set_fs(KERNEL_DS);
            ops->ndo_do_ioctl(dev, &ifr, SIOCDELTUNNEL);
            set_fs(oldfs);
        }
    }
}

static
struct net_device *ipmr_new_tunnel(struct net *net, struct vifctl *v)
{
    struct net_device  *dev;

    dev = __dev_get_by_name(net, "tunl0");

    if (dev) {
        const struct net_device_ops *ops = dev->netdev_ops;
        int err;
        struct ifreq ifr;
        struct ip_tunnel_parm p;
        struct in_device  *in_dev;

        memset(&p, 0, sizeof(p));
        p.iph.daddr = v->vifc_rmt_addr.s_addr;
        p.iph.saddr = v->vifc_lcl_addr.s_addr;
        p.iph.version = 4;
        p.iph.ihl = 5;
        p.iph.protocol = IPPROTO_IPIP;
        sprintf(p.name, "dvmrp%d", v->vifc_vifi);
        ifr.ifr_ifru.ifru_data = (__force void __user *)&p;

        if (ops->ndo_do_ioctl) {
            mm_segment_t oldfs = get_fs();

            set_fs(KERNEL_DS);
            err = ops->ndo_do_ioctl(dev, &ifr, SIOCADDTUNNEL);
            set_fs(oldfs);
        } else {
            err = -EOPNOTSUPP;
        }
        dev = NULL;

        if (err == 0 &&
            (dev = __dev_get_by_name(net, p.name)) != NULL) {
            dev->flags |= IFF_MULTICAST;

            in_dev = __in_dev_get_rtnl(dev);
            if (in_dev == NULL)
                goto failure;

            ipv4_devconf_setall(in_dev);
            IPV4_DEVCONF(in_dev->cnf, RP_FILTER) = 0;

            if (dev_open(dev))
                goto failure;
            dev_hold(dev);
        }
    }
    return dev;

failure:
    /* allow the register to be completed before unregistering. */
    rtnl_unlock();
    rtnl_lock();

    unregister_netdevice(dev);
    return NULL;
}

#ifdef CONFIG_IP_PIMSM

static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct net *net = dev_net(dev);
    struct mr_table *mrt;
    struct flowi4 fl4 = {
        .flowi4_oif = dev->ifindex,
        .flowi4_iif = skb->skb_iif,
        .flowi4_mark    = skb->mark,
    };
    int err;

    err = ipmr_fib_lookup(net, &fl4, &mrt);
    if (err < 0) {
        kfree_skb(skb);
        return err;
    }

    read_lock(&mrt_lock);
    dev->stats.tx_bytes += skb->len;
    dev->stats.tx_packets++;
    ipmr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, IGMPMSG_WHOLEPKT);
    read_unlock(&mrt_lock);
    kfree_skb(skb);
    return NETDEV_TX_OK;
}

static const struct net_device_ops reg_vif_netdev_ops = {
    .ndo_start_xmit = reg_vif_xmit,
};

static void reg_vif_setup(struct net_device *dev)
{
    dev->type       = ARPHRD_PIMREG;
    dev->mtu        = ETH_DATA_LEN - sizeof(struct iphdr) - 8;
    dev->flags      = IFF_NOARP;
    dev->netdev_ops     = &reg_vif_netdev_ops,
    dev->destructor     = free_netdev;
    dev->features       |= NETIF_F_NETNS_LOCAL;
}

static struct net_device *ipmr_reg_vif(struct net *net, struct mr_table *mrt)
{
    struct net_device *dev;
    struct in_device *in_dev;
    char name[IFNAMSIZ];

    if (mrt->id == RT_TABLE_DEFAULT)
        sprintf(name, "pimreg");
    else
        sprintf(name, "pimreg%u", mrt->id);

    dev = alloc_netdev(0, name, reg_vif_setup);

    if (dev == NULL)
        return NULL;

    dev_net_set(dev, net);

    if (register_netdevice(dev)) {
        free_netdev(dev);
        return NULL;
    }
    dev->iflink = 0;

    rcu_read_lock();
    in_dev = __in_dev_get_rcu(dev);
    if (!in_dev) {
        rcu_read_unlock();
        goto failure;
    }

    ipv4_devconf_setall(in_dev);
    IPV4_DEVCONF(in_dev->cnf, RP_FILTER) = 0;
    rcu_read_unlock();

    if (dev_open(dev))
        goto failure;

    dev_hold(dev);

    return dev;

failure:
    /* allow the register to be completed before unregistering. */
    rtnl_unlock();
    rtnl_lock();

    unregister_netdevice(dev);
    return NULL;
}
#endif

static int vif_delete(struct mr_table *mrt, int vifi, int notify,
              struct list_head *head)
{
    struct vif_device *v;
    struct net_device *dev;
    struct in_device *in_dev;

    if (vifi < 0 || vifi >= mrt->maxvif)
        return -EADDRNOTAVAIL;

    v = &mrt->vif_table[vifi];

    write_lock_bh(&mrt_lock);
    dev = v->dev;
    v->dev = NULL;

    if (!dev) {
        write_unlock_bh(&mrt_lock);
        return -EADDRNOTAVAIL;
    }

#ifdef CONFIG_IP_PIMSM
    if (vifi == mrt->mroute_reg_vif_num)
        mrt->mroute_reg_vif_num = -1;
#endif

    if (vifi + 1 == mrt->maxvif) {
        int tmp;

        for (tmp = vifi - 1; tmp >= 0; tmp--) {
            if (VIF_EXISTS(mrt, tmp))
                break;
        }
        mrt->maxvif = tmp+1;
    }

    write_unlock_bh(&mrt_lock);

    dev_set_allmulti(dev, -1);

    in_dev = __in_dev_get_rtnl(dev);
    if (in_dev) {
        IPV4_DEVCONF(in_dev->cnf, MC_FORWARDING)--;
        ip_rt_multicast_event(in_dev);
    }

    if (v->flags & (VIFF_TUNNEL | VIFF_REGISTER) && !notify)
        unregister_netdevice_queue(dev, head);

    dev_put(dev);
    return 0;
}

static void ipmr_cache_free_rcu(struct rcu_head *head)
{
    struct mfc_cache *c = container_of(head, struct mfc_cache, rcu);

    kmem_cache_free(mrt_cachep, c);
}

static inline void ipmr_cache_free(struct mfc_cache *c)
{
    call_rcu(&c->rcu, ipmr_cache_free_rcu);
}

/* Destroy an unresolved cache entry, killing queued skbs
 * and reporting error to netlink readers.
 */

static void ipmr_destroy_unres(struct mr_table *mrt, struct mfc_cache *c)
{
    struct net *net = read_pnet(&mrt->net);
    struct sk_buff *skb;
    struct nlmsgerr *e;

    atomic_dec(&mrt->cache_resolve_queue_len);

    while ((skb = skb_dequeue(&c->mfc_un.unres.unresolved))) {
        if (ip_hdr(skb)->version == 0) {
            struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct iphdr));
            nlh->nlmsg_type = NLMSG_ERROR;
            nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nlmsgerr));
            skb_trim(skb, nlh->nlmsg_len);
            e = NLMSG_DATA(nlh);
            e->error = -ETIMEDOUT;
            memset(&e->msg, 0, sizeof(e->msg));

            rtnl_unicast(skb, net, NETLINK_CB(skb).portid);
        } else {
            kfree_skb(skb);
        }
    }

    ipmr_cache_free(c);
}


/* Timer process for the unresolved queue. */

static void ipmr_expire_process(unsigned long arg)
{
    struct mr_table *mrt = (struct mr_table *)arg;
    unsigned long now;
    unsigned long expires;
    struct mfc_cache *c, *next;

    if (!spin_trylock(&mfc_unres_lock)) {
        mod_timer(&mrt->ipmr_expire_timer, jiffies+HZ/10);
        return;
    }

    if (list_empty(&mrt->mfc_unres_queue))
        goto out;

    now = jiffies;
    expires = 10*HZ;

    list_for_each_entry_safe(c, next, &mrt->mfc_unres_queue, list) {
        if (time_after(c->mfc_un.unres.expires, now)) {
            unsigned long interval = c->mfc_un.unres.expires - now;
            if (interval < expires)
                expires = interval;
            continue;
        }

        list_del(&c->list);
        ipmr_destroy_unres(mrt, c);
    }

    if (!list_empty(&mrt->mfc_unres_queue))
        mod_timer(&mrt->ipmr_expire_timer, jiffies + expires);

out:
    spin_unlock(&mfc_unres_lock);
}

/* Fill oifs list. It is called under write locked mrt_lock. */

static void ipmr_update_thresholds(struct mr_table *mrt, struct mfc_cache *cache,
                   unsigned char *ttls)
{
    int vifi;

    cache->mfc_un.res.minvif = MAXVIFS;
    cache->mfc_un.res.maxvif = 0;
    memset(cache->mfc_un.res.ttls, 255, MAXVIFS);

    for (vifi = 0; vifi < mrt->maxvif; vifi++) {
        if (VIF_EXISTS(mrt, vifi) &&
            ttls[vifi] && ttls[vifi] < 255) {
            cache->mfc_un.res.ttls[vifi] = ttls[vifi];
            if (cache->mfc_un.res.minvif > vifi)
                cache->mfc_un.res.minvif = vifi;
            if (cache->mfc_un.res.maxvif <= vifi)
                cache->mfc_un.res.maxvif = vifi + 1;
        }
    }
}

static int vif_add(struct net *net, struct mr_table *mrt,
           struct vifctl *vifc, int mrtsock)
{
    int vifi = vifc->vifc_vifi;
    struct vif_device *v = &mrt->vif_table[vifi];
    struct net_device *dev;
    struct in_device *in_dev;
    int err;

    /* Is vif busy ? */
    if (VIF_EXISTS(mrt, vifi))
        return -EADDRINUSE;

    switch (vifc->vifc_flags) {
#ifdef CONFIG_IP_PIMSM
    case VIFF_REGISTER:
        /*
         * Special Purpose VIF in PIM
         * All the packets will be sent to the daemon
         */
        if (mrt->mroute_reg_vif_num >= 0)
            return -EADDRINUSE;
        dev = ipmr_reg_vif(net, mrt);
        if (!dev)
            return -ENOBUFS;
        err = dev_set_allmulti(dev, 1);
        if (err) {
            unregister_netdevice(dev);
            dev_put(dev);
            return err;
        }
        break;
#endif
    case VIFF_TUNNEL:
        dev = ipmr_new_tunnel(net, vifc);
        if (!dev)
            return -ENOBUFS;
        err = dev_set_allmulti(dev, 1);
        if (err) {
            ipmr_del_tunnel(dev, vifc);
            dev_put(dev);
            return err;
        }
        break;

    case VIFF_USE_IFINDEX:
    case 0:
        if (vifc->vifc_flags == VIFF_USE_IFINDEX) {
            dev = dev_get_by_index(net, vifc->vifc_lcl_ifindex);
            if (dev && __in_dev_get_rtnl(dev) == NULL) {
                dev_put(dev);
                return -EADDRNOTAVAIL;
            }
        } else {
            dev = ip_dev_find(net, vifc->vifc_lcl_addr.s_addr);
        }
        if (!dev)
            return -EADDRNOTAVAIL;
        err = dev_set_allmulti(dev, 1);
        if (err) {
            dev_put(dev);
            return err;
        }
        break;
    default:
        return -EINVAL;
    }

    in_dev = __in_dev_get_rtnl(dev);
    if (!in_dev) {
        dev_put(dev);
        return -EADDRNOTAVAIL;
    }
    IPV4_DEVCONF(in_dev->cnf, MC_FORWARDING)++;
    ip_rt_multicast_event(in_dev);

    /* Fill in the VIF structures */

    v->rate_limit = vifc->vifc_rate_limit;
    v->local = vifc->vifc_lcl_addr.s_addr;
    v->remote = vifc->vifc_rmt_addr.s_addr;
    v->flags = vifc->vifc_flags;
    if (!mrtsock)
        v->flags |= VIFF_STATIC;
    v->threshold = vifc->vifc_threshold;
    v->bytes_in = 0;
    v->bytes_out = 0;
    v->pkt_in = 0;
    v->pkt_out = 0;
    v->link = dev->ifindex;
    if (v->flags & (VIFF_TUNNEL | VIFF_REGISTER))
        v->link = dev->iflink;

    /* And finish update writing critical data */
    write_lock_bh(&mrt_lock);
    v->dev = dev;
#ifdef CONFIG_IP_PIMSM
    if (v->flags & VIFF_REGISTER)
        mrt->mroute_reg_vif_num = vifi;
#endif
    if (vifi+1 > mrt->maxvif)
        mrt->maxvif = vifi+1;
    write_unlock_bh(&mrt_lock);
    return 0;
}

/* called with rcu_read_lock() */
static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
                     __be32 origin,
                     __be32 mcastgrp)
{
    int line = MFC_HASH(mcastgrp, origin);
    struct mfc_cache *c;

    list_for_each_entry_rcu(c, &mrt->mfc_cache_array[line], list) {
        if (c->mfc_origin == origin && c->mfc_mcastgrp == mcastgrp)
            return c;
    }
    return NULL;
}

/*
 *  Allocate a multicast cache entry
 */
static struct mfc_cache *ipmr_cache_alloc(void)
{
    struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_KERNEL);

    if (c)
        c->mfc_un.res.minvif = MAXVIFS;
    return c;
}

static struct mfc_cache *ipmr_cache_alloc_unres(void)
{
    struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_ATOMIC);

    if (c) {
        skb_queue_head_init(&c->mfc_un.unres.unresolved);
        c->mfc_un.unres.expires = jiffies + 10*HZ;
    }
    return c;
}

/*
 *  A cache entry has gone into a resolved state from queued
 */

static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt,
                   struct mfc_cache *uc, struct mfc_cache *c)
{
    struct sk_buff *skb;
    struct nlmsgerr *e;

    /* Play the pending entries through our router */

    while ((skb = __skb_dequeue(&uc->mfc_un.unres.unresolved))) {
        if (ip_hdr(skb)->version == 0) {
            struct nlmsghdr *nlh = (struct nlmsghdr *)skb_pull(skb, sizeof(struct iphdr));

            if (__ipmr_fill_mroute(mrt, skb, c, NLMSG_DATA(nlh)) > 0) {
                nlh->nlmsg_len = skb_tail_pointer(skb) -
                         (u8 *)nlh;
            } else {
                nlh->nlmsg_type = NLMSG_ERROR;
                nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nlmsgerr));
                skb_trim(skb, nlh->nlmsg_len);
                e = NLMSG_DATA(nlh);
                e->error = -EMSGSIZE;
                memset(&e->msg, 0, sizeof(e->msg));
            }

            rtnl_unicast(skb, net, NETLINK_CB(skb).portid);
        } else {
            ip_mr_forward(net, mrt, skb, c, 0);
        }
    }
}

/*
 *  Bounce a cache query up to mrouted. We could use netlink for this but mrouted
 *  expects the following bizarre scheme.
 *
 *  Called under mrt_lock.
 */

static int ipmr_cache_report(struct mr_table *mrt,
                 struct sk_buff *pkt, vifi_t vifi, int assert)
{
    struct sk_buff *skb;
    const int ihl = ip_hdrlen(pkt);
    struct igmphdr *igmp;
    struct igmpmsg *msg;
    struct sock *mroute_sk;
    int ret;

#ifdef CONFIG_IP_PIMSM
    if (assert == IGMPMSG_WHOLEPKT)
        skb = skb_realloc_headroom(pkt, sizeof(struct iphdr));
    else
#endif
        skb = alloc_skb(128, GFP_ATOMIC);

    if (!skb)
        return -ENOBUFS;

#ifdef CONFIG_IP_PIMSM
    if (assert == IGMPMSG_WHOLEPKT) {
        /* Ugly, but we have no choice with this interface.
         * Duplicate old header, fix ihl, length etc.
         * And all this only to mangle msg->im_msgtype and
         * to set msg->im_mbz to "mbz" :-)
         */
        skb_push(skb, sizeof(struct iphdr));
        skb_reset_network_header(skb);
        skb_reset_transport_header(skb);
        msg = (struct igmpmsg *)skb_network_header(skb);
        memcpy(msg, skb_network_header(pkt), sizeof(struct iphdr));
        msg->im_msgtype = IGMPMSG_WHOLEPKT;
        msg->im_mbz = 0;
        msg->im_vif = mrt->mroute_reg_vif_num;
        ip_hdr(skb)->ihl = sizeof(struct iphdr) >> 2;
        ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(pkt)->tot_len) +
                         sizeof(struct iphdr));
    } else
#endif
    {

    /* Copy the IP header */

    skb->network_header = skb->tail;
    skb_put(skb, ihl);
    skb_copy_to_linear_data(skb, pkt->data, ihl);
    ip_hdr(skb)->protocol = 0;  /* Flag to the kernel this is a route add */
    msg = (struct igmpmsg *)skb_network_header(skb);
    msg->im_vif = vifi;
    skb_dst_set(skb, dst_clone(skb_dst(pkt)));

    /* Add our header */

    igmp = (struct igmphdr *)skb_put(skb, sizeof(struct igmphdr));
    igmp->type  =
    msg->im_msgtype = assert;
    igmp->code  = 0;
    ip_hdr(skb)->tot_len = htons(skb->len);     /* Fix the length */
    skb->transport_header = skb->network_header;
    }

    rcu_read_lock();
    mroute_sk = rcu_dereference(mrt->mroute_sk);
    if (mroute_sk == NULL) {
        rcu_read_unlock();
        kfree_skb(skb);
        return -EINVAL;
    }

    /* Deliver to mrouted */

    ret = sock_queue_rcv_skb(mroute_sk, skb);
    rcu_read_unlock();
    if (ret < 0) {
        net_warn_ratelimited("mroute: pending queue full, dropping entries\n");
        kfree_skb(skb);
    }

    return ret;
}

/*
 *  Queue a packet for resolution. It gets locked cache entry!
 */

static int
ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi, struct sk_buff *skb)
{
    bool found = false;
    int err;
    struct mfc_cache *c;
    const struct iphdr *iph = ip_hdr(skb);

    spin_lock_bh(&mfc_unres_lock);
    list_for_each_entry(c, &mrt->mfc_unres_queue, list) {
        if (c->mfc_mcastgrp == iph->daddr &&
            c->mfc_origin == iph->saddr) {
            found = true;
            break;
        }
    }

    if (!found) {
        /* Create a new entry if allowable */

        if (atomic_read(&mrt->cache_resolve_queue_len) >= 10 ||
            (c = ipmr_cache_alloc_unres()) == NULL) {
            spin_unlock_bh(&mfc_unres_lock);

            kfree_skb(skb);
            return -ENOBUFS;
        }

        /* Fill in the new cache entry */

        c->mfc_parent   = -1;
        c->mfc_origin   = iph->saddr;
        c->mfc_mcastgrp = iph->daddr;

        /* Reflect first query at mrouted. */

        err = ipmr_cache_report(mrt, skb, vifi, IGMPMSG_NOCACHE);
        if (err < 0) {
            /* If the report failed throw the cache entry
               out - Brad Parker
             */
            spin_unlock_bh(&mfc_unres_lock);

            ipmr_cache_free(c);
            kfree_skb(skb);
            return err;
        }

        atomic_inc(&mrt->cache_resolve_queue_len);
        list_add(&c->list, &mrt->mfc_unres_queue);

        if (atomic_read(&mrt->cache_resolve_queue_len) == 1)
            mod_timer(&mrt->ipmr_expire_timer, c->mfc_un.unres.expires);
    }

    /* See if we can append the packet */

    if (c->mfc_un.unres.unresolved.qlen > 3) {
        kfree_skb(skb);
        err = -ENOBUFS;
    } else {
        skb_queue_tail(&c->mfc_un.unres.unresolved, skb);
        err = 0;
    }

    spin_unlock_bh(&mfc_unres_lock);
    return err;
}

/*
 *  MFC cache manipulation by user space mroute daemon
 */

static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
{
    int line;
    struct mfc_cache *c, *next;

    line = MFC_HASH(mfc->mfcc_mcastgrp.s_addr, mfc->mfcc_origin.s_addr);

    list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[line], list) {
        if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
            c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
            list_del_rcu(&c->list);

            ipmr_cache_free(c);
            return 0;
        }
    }
    return -ENOENT;
}

static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
            struct mfcctl *mfc, int mrtsock)
{
    bool found = false;
    int line;
    struct mfc_cache *uc, *c;

    if (mfc->mfcc_parent >= MAXVIFS)
        return -ENFILE;

    line = MFC_HASH(mfc->mfcc_mcastgrp.s_addr, mfc->mfcc_origin.s_addr);

    list_for_each_entry(c, &mrt->mfc_cache_array[line], list) {
        if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
            c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
            found = true;
            break;
        }
    }

    if (found) {
        write_lock_bh(&mrt_lock);
        c->mfc_parent = mfc->mfcc_parent;
        ipmr_update_thresholds(mrt, c, mfc->mfcc_ttls);
        if (!mrtsock)
            c->mfc_flags |= MFC_STATIC;
        write_unlock_bh(&mrt_lock);
        return 0;
    }

    if (!ipv4_is_multicast(mfc->mfcc_mcastgrp.s_addr))
        return -EINVAL;

    c = ipmr_cache_alloc();
    if (c == NULL)
        return -ENOMEM;

    c->mfc_origin = mfc->mfcc_origin.s_addr;
    c->mfc_mcastgrp = mfc->mfcc_mcastgrp.s_addr;
    c->mfc_parent = mfc->mfcc_parent;
    ipmr_update_thresholds(mrt, c, mfc->mfcc_ttls);
    if (!mrtsock)
        c->mfc_flags |= MFC_STATIC;

    list_add_rcu(&c->list, &mrt->mfc_cache_array[line]);

    /*
     *  Check to see if we resolved a queued list. If so we
     *  need to send on the frames and tidy up.
     */
    found = false;
    spin_lock_bh(&mfc_unres_lock);
    list_for_each_entry(uc, &mrt->mfc_unres_queue, list) {
        if (uc->mfc_origin == c->mfc_origin &&
            uc->mfc_mcastgrp == c->mfc_mcastgrp) {
            list_del(&uc->list);
            atomic_dec(&mrt->cache_resolve_queue_len);
            found = true;
            break;
        }
    }
    if (list_empty(&mrt->mfc_unres_queue))
        del_timer(&mrt->ipmr_expire_timer);
    spin_unlock_bh(&mfc_unres_lock);

    if (found) {
        ipmr_cache_resolve(net, mrt, uc, c);
        ipmr_cache_free(uc);
    }
    return 0;
}

/*
 *  Close the multicast socket, and clear the vif tables etc
 */

static void mroute_clean_tables(struct mr_table *mrt)
{
    int i;
    LIST_HEAD(list);
    struct mfc_cache *c, *next;

    /* Shut down all active vif entries */

    for (i = 0; i < mrt->maxvif; i++) {
        if (!(mrt->vif_table[i].flags & VIFF_STATIC))
            vif_delete(mrt, i, 0, &list);
    }
    unregister_netdevice_many(&list);

    /* Wipe the cache */

    for (i = 0; i < MFC_LINES; i++) {
        list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[i], list) {
            if (c->mfc_flags & MFC_STATIC)
                continue;
            list_del_rcu(&c->list);
            ipmr_cache_free(c);
        }
    }

    if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
        spin_lock_bh(&mfc_unres_lock);
        list_for_each_entry_safe(c, next, &mrt->mfc_unres_queue, list) {
            list_del(&c->list);
            ipmr_destroy_unres(mrt, c);
        }
        spin_unlock_bh(&mfc_unres_lock);
    }
}

/* called from ip_ra_control(), before an RCU grace period,
 * we dont need to call synchronize_rcu() here
 */
static void mrtsock_destruct(struct sock *sk)
{
    struct net *net = sock_net(sk);
    struct mr_table *mrt;

    rtnl_lock();
    ipmr_for_each_table(mrt, net) {
        if (sk == rtnl_dereference(mrt->mroute_sk)) {
            IPV4_DEVCONF_ALL(net, MC_FORWARDING)--;
            RCU_INIT_POINTER(mrt->mroute_sk, NULL);
            mroute_clean_tables(mrt);
        }
    }
    rtnl_unlock();
}

/*
 *  Socket options and virtual interface manipulation. The whole
 *  virtual interface system is a complete heap, but unfortunately
 *  that's how BSD mrouted happens to think. Maybe one day with a proper
 *  MOSPF/PIM router set up we can clean this up.
 */

int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen)
{
    int ret;
    struct vifctl vif;
    struct mfcctl mfc;
    struct net *net = sock_net(sk);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return -ENOENT;

    if (optname != MRT_INIT) {
        if (sk != rcu_access_pointer(mrt->mroute_sk) &&
            !capable(CAP_NET_ADMIN))
            return -EACCES;
    }

    switch (optname) {
    case MRT_INIT:
        if (sk->sk_type != SOCK_RAW ||
            inet_sk(sk)->inet_num != IPPROTO_IGMP)
            return -EOPNOTSUPP;
        if (optlen != sizeof(int))
            return -ENOPROTOOPT;

        rtnl_lock();
        if (rtnl_dereference(mrt->mroute_sk)) {
            rtnl_unlock();
            return -EADDRINUSE;
        }

        ret = ip_ra_control(sk, 1, mrtsock_destruct);
        if (ret == 0) {
            rcu_assign_pointer(mrt->mroute_sk, sk);
            IPV4_DEVCONF_ALL(net, MC_FORWARDING)++;
        }
        rtnl_unlock();
        return ret;
    case MRT_DONE:
        if (sk != rcu_access_pointer(mrt->mroute_sk))
            return -EACCES;
        return ip_ra_control(sk, 0, NULL);
    case MRT_ADD_VIF:
    case MRT_DEL_VIF:
        if (optlen != sizeof(vif))
            return -EINVAL;
        if (copy_from_user(&vif, optval, sizeof(vif)))
            return -EFAULT;
        if (vif.vifc_vifi >= MAXVIFS)
            return -ENFILE;
        rtnl_lock();
        if (optname == MRT_ADD_VIF) {
            ret = vif_add(net, mrt, &vif,
                      sk == rtnl_dereference(mrt->mroute_sk));
        } else {
            ret = vif_delete(mrt, vif.vifc_vifi, 0, NULL);
        }
        rtnl_unlock();
        return ret;

        /*
         *  Manipulate the forwarding caches. These live
         *  in a sort of kernel/user symbiosis.
         */
    case MRT_ADD_MFC:
    case MRT_DEL_MFC:
        if (optlen != sizeof(mfc))
            return -EINVAL;
        if (copy_from_user(&mfc, optval, sizeof(mfc)))
            return -EFAULT;
        rtnl_lock();
        if (optname == MRT_DEL_MFC)
            ret = ipmr_mfc_delete(mrt, &mfc);
        else
            ret = ipmr_mfc_add(net, mrt, &mfc,
                       sk == rtnl_dereference(mrt->mroute_sk));
        rtnl_unlock();
        return ret;
        /*
         *  Control PIM assert.
         */
    case MRT_ASSERT:
    {
        int v;
        if (get_user(v, (int __user *)optval))
            return -EFAULT;
        mrt->mroute_do_assert = (v) ? 1 : 0;
        return 0;
    }
#ifdef CONFIG_IP_PIMSM
    case MRT_PIM:
    {
        int v;

        if (get_user(v, (int __user *)optval))
            return -EFAULT;
        v = (v) ? 1 : 0;

        rtnl_lock();
        ret = 0;
        if (v != mrt->mroute_do_pim) {
            mrt->mroute_do_pim = v;
            mrt->mroute_do_assert = v;
        }
        rtnl_unlock();
        return ret;
    }
#endif
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
    case MRT_TABLE:
    {
        u32 v;

        if (optlen != sizeof(u32))
            return -EINVAL;
        if (get_user(v, (u32 __user *)optval))
            return -EFAULT;

        /* "pimreg%u" should not exceed 16 bytes (IFNAMSIZ) */
        if (v != RT_TABLE_DEFAULT && v >= 1000000000)
            return -EINVAL;

        rtnl_lock();
        ret = 0;
        if (sk == rtnl_dereference(mrt->mroute_sk)) {
            ret = -EBUSY;
        } else {
            if (!ipmr_new_table(net, v))
                ret = -ENOMEM;
            raw_sk(sk)->ipmr_table = v;
        }
        rtnl_unlock();
        return ret;
    }
#endif
    /*
     *  Spurious command, or MRT_VERSION which you cannot
     *  set.
     */
    default:
        return -ENOPROTOOPT;
    }
}

/*
 *  Getsock opt support for the multicast routing system.
 */

int ip_mroute_getsockopt(struct sock *sk, int optname, char __user *optval, int __user *optlen)
{
    int olr;
    int val;
    struct net *net = sock_net(sk);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return -ENOENT;

    if (optname != MRT_VERSION &&
#ifdef CONFIG_IP_PIMSM
       optname != MRT_PIM &&
#endif
       optname != MRT_ASSERT)
        return -ENOPROTOOPT;

    if (get_user(olr, optlen))
        return -EFAULT;

    olr = min_t(unsigned int, olr, sizeof(int));
    if (olr < 0)
        return -EINVAL;

    if (put_user(olr, optlen))
        return -EFAULT;
    if (optname == MRT_VERSION)
        val = 0x0305;
#ifdef CONFIG_IP_PIMSM
    else if (optname == MRT_PIM)
        val = mrt->mroute_do_pim;
#endif
    else
        val = mrt->mroute_do_assert;
    if (copy_to_user(optval, &val, olr))
        return -EFAULT;
    return 0;
}

/*
 *  The IP multicast ioctl support routines.
 */

int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg)
{
    struct sioc_sg_req sr;
    struct sioc_vif_req vr;
    struct vif_device *vif;
    struct mfc_cache *c;
    struct net *net = sock_net(sk);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return -ENOENT;

    switch (cmd) {
    case SIOCGETVIFCNT:
        if (copy_from_user(&vr, arg, sizeof(vr)))
            return -EFAULT;
        if (vr.vifi >= mrt->maxvif)
            return -EINVAL;
        read_lock(&mrt_lock);
        vif = &mrt->vif_table[vr.vifi];
        if (VIF_EXISTS(mrt, vr.vifi)) {
            vr.icount = vif->pkt_in;
            vr.ocount = vif->pkt_out;
            vr.ibytes = vif->bytes_in;
            vr.obytes = vif->bytes_out;
            read_unlock(&mrt_lock);

            if (copy_to_user(arg, &vr, sizeof(vr)))
                return -EFAULT;
            return 0;
        }
        read_unlock(&mrt_lock);
        return -EADDRNOTAVAIL;
    case SIOCGETSGCNT:
        if (copy_from_user(&sr, arg, sizeof(sr)))
            return -EFAULT;

        rcu_read_lock();
        c = ipmr_cache_find(mrt, sr.src.s_addr, sr.grp.s_addr);
        if (c) {
            sr.pktcnt = c->mfc_un.res.pkt;
            sr.bytecnt = c->mfc_un.res.bytes;
            sr.wrong_if = c->mfc_un.res.wrong_if;
            rcu_read_unlock();

            if (copy_to_user(arg, &sr, sizeof(sr)))
                return -EFAULT;
            return 0;
        }
        rcu_read_unlock();
        return -EADDRNOTAVAIL;
    default:
        return -ENOIOCTLCMD;
    }
}

#ifdef CONFIG_COMPAT
struct compat_sioc_sg_req {
    struct in_addr src;
    struct in_addr grp;
    compat_ulong_t pktcnt;
    compat_ulong_t bytecnt;
    compat_ulong_t wrong_if;
};

struct compat_sioc_vif_req {
    vifi_t  vifi;       /* Which iface */
    compat_ulong_t icount;
    compat_ulong_t ocount;
    compat_ulong_t ibytes;
    compat_ulong_t obytes;
};

int ipmr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
{
    struct compat_sioc_sg_req sr;
    struct compat_sioc_vif_req vr;
    struct vif_device *vif;
    struct mfc_cache *c;
    struct net *net = sock_net(sk);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return -ENOENT;

    switch (cmd) {
    case SIOCGETVIFCNT:
        if (copy_from_user(&vr, arg, sizeof(vr)))
            return -EFAULT;
        if (vr.vifi >= mrt->maxvif)
            return -EINVAL;
        read_lock(&mrt_lock);
        vif = &mrt->vif_table[vr.vifi];
        if (VIF_EXISTS(mrt, vr.vifi)) {
            vr.icount = vif->pkt_in;
            vr.ocount = vif->pkt_out;
            vr.ibytes = vif->bytes_in;
            vr.obytes = vif->bytes_out;
            read_unlock(&mrt_lock);

            if (copy_to_user(arg, &vr, sizeof(vr)))
                return -EFAULT;
            return 0;
        }
        read_unlock(&mrt_lock);
        return -EADDRNOTAVAIL;
    case SIOCGETSGCNT:
        if (copy_from_user(&sr, arg, sizeof(sr)))
            return -EFAULT;

        rcu_read_lock();
        c = ipmr_cache_find(mrt, sr.src.s_addr, sr.grp.s_addr);
        if (c) {
            sr.pktcnt = c->mfc_un.res.pkt;
            sr.bytecnt = c->mfc_un.res.bytes;
            sr.wrong_if = c->mfc_un.res.wrong_if;
            rcu_read_unlock();

            if (copy_to_user(arg, &sr, sizeof(sr)))
                return -EFAULT;
            return 0;
        }
        rcu_read_unlock();
        return -EADDRNOTAVAIL;
    default:
        return -ENOIOCTLCMD;
    }
}
#endif


static int ipmr_device_event(struct notifier_block *this, unsigned long event, void *ptr)
{
    struct net_device *dev = ptr;
    struct net *net = dev_net(dev);
    struct mr_table *mrt;
    struct vif_device *v;
    int ct;

    if (event != NETDEV_UNREGISTER)
        return NOTIFY_DONE;

    ipmr_for_each_table(mrt, net) {
        v = &mrt->vif_table[0];
        for (ct = 0; ct < mrt->maxvif; ct++, v++) {
            if (v->dev == dev)
                vif_delete(mrt, ct, 1, NULL);
        }
    }
    return NOTIFY_DONE;
}


static struct notifier_block ip_mr_notifier = {
    .notifier_call = ipmr_device_event,
};

/*
 *  Encapsulate a packet by attaching a valid IPIP header to it.
 *  This avoids tunnel drivers and other mess and gives us the speed so
 *  important for multicast video.
 */

static void ip_encap(struct sk_buff *skb, __be32 saddr, __be32 daddr)
{
    struct iphdr *iph;
    const struct iphdr *old_iph = ip_hdr(skb);

    skb_push(skb, sizeof(struct iphdr));
    skb->transport_header = skb->network_header;
    skb_reset_network_header(skb);
    iph = ip_hdr(skb);

    iph->version    =   4;
    iph->tos    =   old_iph->tos;
    iph->ttl    =   old_iph->ttl;
    iph->frag_off   =   0;
    iph->daddr  =   daddr;
    iph->saddr  =   saddr;
    iph->protocol   =   IPPROTO_IPIP;
    iph->ihl    =   5;
    iph->tot_len    =   htons(skb->len);
    ip_select_ident(iph, skb_dst(skb), NULL);
    ip_send_check(iph);

    memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
    nf_reset(skb);
}

static inline int ipmr_forward_finish(struct sk_buff *skb)
{
    struct ip_options *opt = &(IPCB(skb)->opt);

    IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
    IP_ADD_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTOCTETS, skb->len);

    if (unlikely(opt->optlen))
        ip_forward_options(skb);

    return dst_output(skb);
}

/*
 *  Processing handlers for ipmr_forward
 */

static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
                struct sk_buff *skb, struct mfc_cache *c, int vifi)
{
    const struct iphdr *iph = ip_hdr(skb);
    struct vif_device *vif = &mrt->vif_table[vifi];
    struct net_device *dev;
    struct rtable *rt;
    struct flowi4 fl4;
    int    encap = 0;

    if (vif->dev == NULL)
        goto out_free;

#ifdef CONFIG_IP_PIMSM
    if (vif->flags & VIFF_REGISTER) {
        vif->pkt_out++;
        vif->bytes_out += skb->len;
        vif->dev->stats.tx_bytes += skb->len;
        vif->dev->stats.tx_packets++;
        ipmr_cache_report(mrt, skb, vifi, IGMPMSG_WHOLEPKT);
        goto out_free;
    }
#endif

    if (vif->flags & VIFF_TUNNEL) {
        rt = ip_route_output_ports(net, &fl4, NULL,
                       vif->remote, vif->local,
                       0, 0,
                       IPPROTO_IPIP,
                       RT_TOS(iph->tos), vif->link);
        if (IS_ERR(rt))
            goto out_free;
        encap = sizeof(struct iphdr);
    } else {
        rt = ip_route_output_ports(net, &fl4, NULL, iph->daddr, 0,
                       0, 0,
                       IPPROTO_IPIP,
                       RT_TOS(iph->tos), vif->link);
        if (IS_ERR(rt))
            goto out_free;
    }

    dev = rt->dst.dev;

    if (skb->len+encap > dst_mtu(&rt->dst) && (ntohs(iph->frag_off) & IP_DF)) {
        /* Do not fragment multicasts. Alas, IPv4 does not
         * allow to send ICMP, so that packets will disappear
         * to blackhole.
         */

        IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
        ip_rt_put(rt);
        goto out_free;
    }

    encap += LL_RESERVED_SPACE(dev) + rt->dst.header_len;

    if (skb_cow(skb, encap)) {
        ip_rt_put(rt);
        goto out_free;
    }

    vif->pkt_out++;
    vif->bytes_out += skb->len;

    skb_dst_drop(skb);
    skb_dst_set(skb, &rt->dst);
    ip_decrease_ttl(ip_hdr(skb));

    /* FIXME: forward and output firewalls used to be called here.
     * What do we do with netfilter? -- RR
     */
    if (vif->flags & VIFF_TUNNEL) {
        ip_encap(skb, vif->local, vif->remote);
        /* FIXME: extra output firewall step used to be here. --RR */
        vif->dev->stats.tx_packets++;
        vif->dev->stats.tx_bytes += skb->len;
    }

    IPCB(skb)->flags |= IPSKB_FORWARDED;

    /*
     * RFC1584 teaches, that DVMRP/PIM router must deliver packets locally
     * not only before forwarding, but after forwarding on all output
     * interfaces. It is clear, if mrouter runs a multicasting
     * program, it should receive packets not depending to what interface
     * program is joined.
     * If we will not make it, the program will have to join on all
     * interfaces. On the other hand, multihoming host (or router, but
     * not mrouter) cannot join to more than one interface - it will
     * result in receiving multiple packets.
     */
    NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev, dev,
        ipmr_forward_finish);
    return;

out_free:
    kfree_skb(skb);
}

static int ipmr_find_vif(struct mr_table *mrt, struct net_device *dev)
{
    int ct;

    for (ct = mrt->maxvif-1; ct >= 0; ct--) {
        if (mrt->vif_table[ct].dev == dev)
            break;
    }
    return ct;
}

/* "local" means that we should preserve one skb (for local delivery) */

static int ip_mr_forward(struct net *net, struct mr_table *mrt,
             struct sk_buff *skb, struct mfc_cache *cache,
             int local)
{
    int psend = -1;
    int vif, ct;

    vif = cache->mfc_parent;
    cache->mfc_un.res.pkt++;
    cache->mfc_un.res.bytes += skb->len;

    /*
     * Wrong interface: drop packet and (maybe) send PIM assert.
     */
    if (mrt->vif_table[vif].dev != skb->dev) {
        int true_vifi;

        if (rt_is_output_route(skb_rtable(skb))) {
            /* It is our own packet, looped back.
             * Very complicated situation...
             *
             * The best workaround until routing daemons will be
             * fixed is not to redistribute packet, if it was
             * send through wrong interface. It means, that
             * multicast applications WILL NOT work for
             * (S,G), which have default multicast route pointing
             * to wrong oif. In any case, it is not a good
             * idea to use multicasting applications on router.
             */
            goto dont_forward;
        }

        cache->mfc_un.res.wrong_if++;
        true_vifi = ipmr_find_vif(mrt, skb->dev);

        if (true_vifi >= 0 && mrt->mroute_do_assert &&
            /* pimsm uses asserts, when switching from RPT to SPT,
             * so that we cannot check that packet arrived on an oif.
             * It is bad, but otherwise we would need to move pretty
             * large chunk of pimd to kernel. Ough... --ANK
             */
            (mrt->mroute_do_pim ||
             cache->mfc_un.res.ttls[true_vifi] < 255) &&
            time_after(jiffies,
                   cache->mfc_un.res.last_assert + MFC_ASSERT_THRESH)) {
            cache->mfc_un.res.last_assert = jiffies;
            ipmr_cache_report(mrt, skb, true_vifi, IGMPMSG_WRONGVIF);
        }
        goto dont_forward;
    }

    mrt->vif_table[vif].pkt_in++;
    mrt->vif_table[vif].bytes_in += skb->len;

    /*
     *  Forward the frame
     */
    for (ct = cache->mfc_un.res.maxvif - 1;
         ct >= cache->mfc_un.res.minvif; ct--) {
        if (ip_hdr(skb)->ttl > cache->mfc_un.res.ttls[ct]) {
            if (psend != -1) {
                struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

                if (skb2)
                    ipmr_queue_xmit(net, mrt, skb2, cache,
                            psend);
            }
            psend = ct;
        }
    }
    if (psend != -1) {
        if (local) {
            struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

            if (skb2)
                ipmr_queue_xmit(net, mrt, skb2, cache, psend);
        } else {
            ipmr_queue_xmit(net, mrt, skb, cache, psend);
            return 0;
        }
    }

dont_forward:
    if (!local)
        kfree_skb(skb);
    return 0;
}

static struct mr_table *ipmr_rt_fib_lookup(struct net *net, struct sk_buff *skb)
{
    struct rtable *rt = skb_rtable(skb);
    struct iphdr *iph = ip_hdr(skb);
    struct flowi4 fl4 = {
        .daddr = iph->daddr,
        .saddr = iph->saddr,
        .flowi4_tos = RT_TOS(iph->tos),
        .flowi4_oif = (rt_is_output_route(rt) ?
                   skb->dev->ifindex : 0),
        .flowi4_iif = (rt_is_output_route(rt) ?
                   LOOPBACK_IFINDEX :
                   skb->dev->ifindex),
        .flowi4_mark = skb->mark,
    };
    struct mr_table *mrt;
    int err;

    err = ipmr_fib_lookup(net, &fl4, &mrt);
    if (err)
        return ERR_PTR(err);
    return mrt;
}

/*
 *  Multicast packets for forwarding arrive here
 *  Called with rcu_read_lock();
 */

int ip_mr_input(struct sk_buff *skb)
{
    struct mfc_cache *cache;
    struct net *net = dev_net(skb->dev);
    int local = skb_rtable(skb)->rt_flags & RTCF_LOCAL;
    struct mr_table *mrt;

    /* Packet is looped back after forward, it should not be
     * forwarded second time, but still can be delivered locally.
     */
    if (IPCB(skb)->flags & IPSKB_FORWARDED)
        goto dont_forward;

    mrt = ipmr_rt_fib_lookup(net, skb);
    if (IS_ERR(mrt)) {
        kfree_skb(skb);
        return PTR_ERR(mrt);
    }
    if (!local) {
        if (IPCB(skb)->opt.router_alert) {
            if (ip_call_ra_chain(skb))
                return 0;
        } else if (ip_hdr(skb)->protocol == IPPROTO_IGMP) {
            /* IGMPv1 (and broken IGMPv2 implementations sort of
             * Cisco IOS <= 11.2(8)) do not put router alert
             * option to IGMP packets destined to routable
             * groups. It is very bad, because it means
             * that we can forward NO IGMP messages.
             */
            struct sock *mroute_sk;

            mroute_sk = rcu_dereference(mrt->mroute_sk);
            if (mroute_sk) {
                nf_reset(skb);
                raw_rcv(mroute_sk, skb);
                return 0;
            }
            }
    }

    /* already under rcu_read_lock() */
    cache = ipmr_cache_find(mrt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);

    /*
     *  No usable cache entry
     */
    if (cache == NULL) {
        int vif;

        if (local) {
            struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
            ip_local_deliver(skb);
            if (skb2 == NULL)
                return -ENOBUFS;
            skb = skb2;
        }

        read_lock(&mrt_lock);
        vif = ipmr_find_vif(mrt, skb->dev);
        if (vif >= 0) {
            int err2 = ipmr_cache_unresolved(mrt, vif, skb);
            read_unlock(&mrt_lock);

            return err2;
        }
        read_unlock(&mrt_lock);
        kfree_skb(skb);
        return -ENODEV;
    }

    read_lock(&mrt_lock);
    ip_mr_forward(net, mrt, skb, cache, local);
    read_unlock(&mrt_lock);

    if (local)
        return ip_local_deliver(skb);

    return 0;

dont_forward:
    if (local)
        return ip_local_deliver(skb);
    kfree_skb(skb);
    return 0;
}

#ifdef CONFIG_IP_PIMSM
/* called with rcu_read_lock() */
static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
             unsigned int pimlen)
{
    struct net_device *reg_dev = NULL;
    struct iphdr *encap;

    encap = (struct iphdr *)(skb_transport_header(skb) + pimlen);
    /*
     * Check that:
     * a. packet is really sent to a multicast group
     * b. packet is not a NULL-REGISTER
     * c. packet is not truncated
     */
    if (!ipv4_is_multicast(encap->daddr) ||
        encap->tot_len == 0 ||
        ntohs(encap->tot_len) + pimlen > skb->len)
        return 1;

    read_lock(&mrt_lock);
    if (mrt->mroute_reg_vif_num >= 0)
        reg_dev = mrt->vif_table[mrt->mroute_reg_vif_num].dev;
    read_unlock(&mrt_lock);

    if (reg_dev == NULL)
        return 1;

    skb->mac_header = skb->network_header;
    skb_pull(skb, (u8 *)encap - skb->data);
    skb_reset_network_header(skb);
    skb->protocol = htons(ETH_P_IP);
    skb->ip_summed = CHECKSUM_NONE;
    skb->pkt_type = PACKET_HOST;

    skb_tunnel_rx(skb, reg_dev);

    netif_rx(skb);

    return NET_RX_SUCCESS;
}
#endif

#ifdef CONFIG_IP_PIMSM_V1
/*
 * Handle IGMP messages of PIMv1
 */

int pim_rcv_v1(struct sk_buff *skb)
{
    struct igmphdr *pim;
    struct net *net = dev_net(skb->dev);
    struct mr_table *mrt;

    if (!pskb_may_pull(skb, sizeof(*pim) + sizeof(struct iphdr)))
        goto drop;

    pim = igmp_hdr(skb);

    mrt = ipmr_rt_fib_lookup(net, skb);
    if (IS_ERR(mrt))
        goto drop;
    if (!mrt->mroute_do_pim ||
        pim->group != PIM_V1_VERSION || pim->code != PIM_V1_REGISTER)
        goto drop;

    if (__pim_rcv(mrt, skb, sizeof(*pim))) {
drop:
        kfree_skb(skb);
    }
    return 0;
}
#endif

#ifdef CONFIG_IP_PIMSM_V2
static int pim_rcv(struct sk_buff *skb)
{
    struct pimreghdr *pim;
    struct net *net = dev_net(skb->dev);
    struct mr_table *mrt;

    if (!pskb_may_pull(skb, sizeof(*pim) + sizeof(struct iphdr)))
        goto drop;

    pim = (struct pimreghdr *)skb_transport_header(skb);
    if (pim->type != ((PIM_VERSION << 4) | (PIM_REGISTER)) ||
        (pim->flags & PIM_NULL_REGISTER) ||
        (ip_compute_csum((void *)pim, sizeof(*pim)) != 0 &&
         csum_fold(skb_checksum(skb, 0, skb->len, 0))))
        goto drop;

    mrt = ipmr_rt_fib_lookup(net, skb);
    if (IS_ERR(mrt))
        goto drop;
    if (__pim_rcv(mrt, skb, sizeof(*pim))) {
drop:
        kfree_skb(skb);
    }
    return 0;
}
#endif

static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
                  struct mfc_cache *c, struct rtmsg *rtm)
{
    int ct;
    struct rtnexthop *nhp;
    struct nlattr *mp_attr;

    /* If cache is unresolved, don't try to parse IIF and OIF */
    if (c->mfc_parent >= MAXVIFS)
        return -ENOENT;

    if (VIF_EXISTS(mrt, c->mfc_parent) &&
        nla_put_u32(skb, RTA_IIF, mrt->vif_table[c->mfc_parent].dev->ifindex) < 0)
        return -EMSGSIZE;

    if (!(mp_attr = nla_nest_start(skb, RTA_MULTIPATH)))
        return -EMSGSIZE;

    for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) {
        if (VIF_EXISTS(mrt, ct) && c->mfc_un.res.ttls[ct] < 255) {
            if (!(nhp = nla_reserve_nohdr(skb, sizeof(*nhp)))) {
                nla_nest_cancel(skb, mp_attr);
                return -EMSGSIZE;
            }

            nhp->rtnh_flags = 0;
            nhp->rtnh_hops = c->mfc_un.res.ttls[ct];
            nhp->rtnh_ifindex = mrt->vif_table[ct].dev->ifindex;
            nhp->rtnh_len = sizeof(*nhp);
        }
    }

    nla_nest_end(skb, mp_attr);

    rtm->rtm_type = RTN_MULTICAST;
    return 1;
}

int ipmr_get_route(struct net *net, struct sk_buff *skb,
           __be32 saddr, __be32 daddr,
           struct rtmsg *rtm, int nowait)
{
    struct mfc_cache *cache;
    struct mr_table *mrt;
    int err;

    mrt = ipmr_get_table(net, RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return -ENOENT;

    rcu_read_lock();
    cache = ipmr_cache_find(mrt, saddr, daddr);

    if (cache == NULL) {
        struct sk_buff *skb2;
        struct iphdr *iph;
        struct net_device *dev;
        int vif = -1;

        if (nowait) {
            rcu_read_unlock();
            return -EAGAIN;
        }

        dev = skb->dev;
        read_lock(&mrt_lock);
        if (dev)
            vif = ipmr_find_vif(mrt, dev);
        if (vif < 0) {
            read_unlock(&mrt_lock);
            rcu_read_unlock();
            return -ENODEV;
        }
        skb2 = skb_clone(skb, GFP_ATOMIC);
        if (!skb2) {
            read_unlock(&mrt_lock);
            rcu_read_unlock();
            return -ENOMEM;
        }

        skb_push(skb2, sizeof(struct iphdr));
        skb_reset_network_header(skb2);
        iph = ip_hdr(skb2);
        iph->ihl = sizeof(struct iphdr) >> 2;
        iph->saddr = saddr;
        iph->daddr = daddr;
        iph->version = 0;
        err = ipmr_cache_unresolved(mrt, vif, skb2);
        read_unlock(&mrt_lock);
        rcu_read_unlock();
        return err;
    }

    read_lock(&mrt_lock);
    if (!nowait && (rtm->rtm_flags & RTM_F_NOTIFY))
        cache->mfc_flags |= MFC_NOTIFY;
    err = __ipmr_fill_mroute(mrt, skb, cache, rtm);
    read_unlock(&mrt_lock);
    rcu_read_unlock();
    return err;
}

static int ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
                u32 portid, u32 seq, struct mfc_cache *c)
{
    struct nlmsghdr *nlh;
    struct rtmsg *rtm;

    nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*rtm), NLM_F_MULTI);
    if (nlh == NULL)
        return -EMSGSIZE;

    rtm = nlmsg_data(nlh);
    rtm->rtm_family   = RTNL_FAMILY_IPMR;
    rtm->rtm_dst_len  = 32;
    rtm->rtm_src_len  = 32;
    rtm->rtm_tos      = 0;
    rtm->rtm_table    = mrt->id;
    if (nla_put_u32(skb, RTA_TABLE, mrt->id))
        goto nla_put_failure;
    rtm->rtm_type     = RTN_MULTICAST;
    rtm->rtm_scope    = RT_SCOPE_UNIVERSE;
    rtm->rtm_protocol = RTPROT_UNSPEC;
    rtm->rtm_flags    = 0;

    if (nla_put_be32(skb, RTA_SRC, c->mfc_origin) ||
        nla_put_be32(skb, RTA_DST, c->mfc_mcastgrp))
        goto nla_put_failure;
    if (__ipmr_fill_mroute(mrt, skb, c, rtm) < 0)
        goto nla_put_failure;

    return nlmsg_end(skb, nlh);

nla_put_failure:
    nlmsg_cancel(skb, nlh);
    return -EMSGSIZE;
}

static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct net *net = sock_net(skb->sk);
    struct mr_table *mrt;
    struct mfc_cache *mfc;
    unsigned int t = 0, s_t;
    unsigned int h = 0, s_h;
    unsigned int e = 0, s_e;

    s_t = cb->args[0];
    s_h = cb->args[1];
    s_e = cb->args[2];

    rcu_read_lock();
    ipmr_for_each_table(mrt, net) {
        if (t < s_t)
            goto next_table;
        if (t > s_t)
            s_h = 0;
        for (h = s_h; h < MFC_LINES; h++) {
            list_for_each_entry_rcu(mfc, &mrt->mfc_cache_array[h], list) {
                if (e < s_e)
                    goto next_entry;
                if (ipmr_fill_mroute(mrt, skb,
                             NETLINK_CB(cb->skb).portid,
                             cb->nlh->nlmsg_seq,
                             mfc) < 0)
                    goto done;
next_entry:
                e++;
            }
            e = s_e = 0;
        }
        s_h = 0;
next_table:
        t++;
    }
done:
    rcu_read_unlock();

    cb->args[2] = e;
    cb->args[1] = h;
    cb->args[0] = t;

    return skb->len;
}

#ifdef CONFIG_PROC_FS
/*
 *  The /proc interfaces to multicast routing :
 *  /proc/net/ip_mr_cache & /proc/net/ip_mr_vif
 */
struct ipmr_vif_iter {
    struct seq_net_private p;
    struct mr_table *mrt;
    int ct;
};

static struct vif_device *ipmr_vif_seq_idx(struct net *net,
                       struct ipmr_vif_iter *iter,
                       loff_t pos)
{
    struct mr_table *mrt = iter->mrt;

    for (iter->ct = 0; iter->ct < mrt->maxvif; ++iter->ct) {
        if (!VIF_EXISTS(mrt, iter->ct))
            continue;
        if (pos-- == 0)
            return &mrt->vif_table[iter->ct];
    }
    return NULL;
}

static void *ipmr_vif_seq_start(struct seq_file *seq, loff_t *pos)
    __acquires(mrt_lock)
{
    struct ipmr_vif_iter *iter = seq->private;
    struct net *net = seq_file_net(seq);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return ERR_PTR(-ENOENT);

    iter->mrt = mrt;

    read_lock(&mrt_lock);
    return *pos ? ipmr_vif_seq_idx(net, seq->private, *pos - 1)
        : SEQ_START_TOKEN;
}

static void *ipmr_vif_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    struct ipmr_vif_iter *iter = seq->private;
    struct net *net = seq_file_net(seq);
    struct mr_table *mrt = iter->mrt;

    ++*pos;
    if (v == SEQ_START_TOKEN)
        return ipmr_vif_seq_idx(net, iter, 0);

    while (++iter->ct < mrt->maxvif) {
        if (!VIF_EXISTS(mrt, iter->ct))
            continue;
        return &mrt->vif_table[iter->ct];
    }
    return NULL;
}

static void ipmr_vif_seq_stop(struct seq_file *seq, void *v)
    __releases(mrt_lock)
{
    read_unlock(&mrt_lock);
}

static int ipmr_vif_seq_show(struct seq_file *seq, void *v)
{
    struct ipmr_vif_iter *iter = seq->private;
    struct mr_table *mrt = iter->mrt;

    if (v == SEQ_START_TOKEN) {
        seq_puts(seq,
             "Interface      BytesIn  PktsIn  BytesOut PktsOut Flags Local    Remote\n");
    } else {
        const struct vif_device *vif = v;
        const char *name =  vif->dev ? vif->dev->name : "none";

        seq_printf(seq,
               "%2Zd %-10s %8ld %7ld  %8ld %7ld %05X %08X %08X\n",
               vif - mrt->vif_table,
               name, vif->bytes_in, vif->pkt_in,
               vif->bytes_out, vif->pkt_out,
               vif->flags, vif->local, vif->remote);
    }
    return 0;
}

static const struct seq_operations ipmr_vif_seq_ops = {
    .start = ipmr_vif_seq_start,
    .next  = ipmr_vif_seq_next,
    .stop  = ipmr_vif_seq_stop,
    .show  = ipmr_vif_seq_show,
};

static int ipmr_vif_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &ipmr_vif_seq_ops,
                sizeof(struct ipmr_vif_iter));
}

static const struct file_operations ipmr_vif_fops = {
    .owner   = THIS_MODULE,
    .open    = ipmr_vif_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};

struct ipmr_mfc_iter {
    struct seq_net_private p;
    struct mr_table *mrt;
    struct list_head *cache;
    int ct;
};


static struct mfc_cache *ipmr_mfc_seq_idx(struct net *net,
                      struct ipmr_mfc_iter *it, loff_t pos)
{
    struct mr_table *mrt = it->mrt;
    struct mfc_cache *mfc;

    rcu_read_lock();
    for (it->ct = 0; it->ct < MFC_LINES; it->ct++) {
        it->cache = &mrt->mfc_cache_array[it->ct];
        list_for_each_entry_rcu(mfc, it->cache, list)
            if (pos-- == 0)
                return mfc;
    }
    rcu_read_unlock();

    spin_lock_bh(&mfc_unres_lock);
    it->cache = &mrt->mfc_unres_queue;
    list_for_each_entry(mfc, it->cache, list)
        if (pos-- == 0)
            return mfc;
    spin_unlock_bh(&mfc_unres_lock);

    it->cache = NULL;
    return NULL;
}


static void *ipmr_mfc_seq_start(struct seq_file *seq, loff_t *pos)
{
    struct ipmr_mfc_iter *it = seq->private;
    struct net *net = seq_file_net(seq);
    struct mr_table *mrt;

    mrt = ipmr_get_table(net, RT_TABLE_DEFAULT);
    if (mrt == NULL)
        return ERR_PTR(-ENOENT);

    it->mrt = mrt;
    it->cache = NULL;
    it->ct = 0;
    return *pos ? ipmr_mfc_seq_idx(net, seq->private, *pos - 1)
        : SEQ_START_TOKEN;
}

static void *ipmr_mfc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    struct mfc_cache *mfc = v;
    struct ipmr_mfc_iter *it = seq->private;
    struct net *net = seq_file_net(seq);
    struct mr_table *mrt = it->mrt;

    ++*pos;

    if (v == SEQ_START_TOKEN)
        return ipmr_mfc_seq_idx(net, seq->private, 0);

    if (mfc->list.next != it->cache)
        return list_entry(mfc->list.next, struct mfc_cache, list);

    if (it->cache == &mrt->mfc_unres_queue)
        goto end_of_list;

    BUG_ON(it->cache != &mrt->mfc_cache_array[it->ct]);

    while (++it->ct < MFC_LINES) {
        it->cache = &mrt->mfc_cache_array[it->ct];
        if (list_empty(it->cache))
            continue;
        return list_first_entry(it->cache, struct mfc_cache, list);
    }

    /* exhausted cache_array, show unresolved */
    rcu_read_unlock();
    it->cache = &mrt->mfc_unres_queue;
    it->ct = 0;

    spin_lock_bh(&mfc_unres_lock);
    if (!list_empty(it->cache))
        return list_first_entry(it->cache, struct mfc_cache, list);

end_of_list:
    spin_unlock_bh(&mfc_unres_lock);
    it->cache = NULL;

    return NULL;
}

static void ipmr_mfc_seq_stop(struct seq_file *seq, void *v)
{
    struct ipmr_mfc_iter *it = seq->private;
    struct mr_table *mrt = it->mrt;

    if (it->cache == &mrt->mfc_unres_queue)
        spin_unlock_bh(&mfc_unres_lock);
    else if (it->cache == &mrt->mfc_cache_array[it->ct])
        rcu_read_unlock();
}

static int ipmr_mfc_seq_show(struct seq_file *seq, void *v)
{
    int n;

    if (v == SEQ_START_TOKEN) {
        seq_puts(seq,
         "Group    Origin   Iif     Pkts    Bytes    Wrong Oifs\n");
    } else {
        const struct mfc_cache *mfc = v;
        const struct ipmr_mfc_iter *it = seq->private;
        const struct mr_table *mrt = it->mrt;

        seq_printf(seq, "%08X %08X %-3hd",
               (__force u32) mfc->mfc_mcastgrp,
               (__force u32) mfc->mfc_origin,
               mfc->mfc_parent);

        if (it->cache != &mrt->mfc_unres_queue) {
            seq_printf(seq, " %8lu %8lu %8lu",
                   mfc->mfc_un.res.pkt,
                   mfc->mfc_un.res.bytes,
                   mfc->mfc_un.res.wrong_if);
            for (n = mfc->mfc_un.res.minvif;
                 n < mfc->mfc_un.res.maxvif; n++) {
                if (VIF_EXISTS(mrt, n) &&
                    mfc->mfc_un.res.ttls[n] < 255)
                    seq_printf(seq,
                       " %2d:%-3d",
                       n, mfc->mfc_un.res.ttls[n]);
            }
        } else {
            /* unresolved mfc_caches don't contain
             * pkt, bytes and wrong_if values
             */
            seq_printf(seq, " %8lu %8lu %8lu", 0ul, 0ul, 0ul);
        }
        seq_putc(seq, '\n');
    }
    return 0;
}

static const struct seq_operations ipmr_mfc_seq_ops = {
    .start = ipmr_mfc_seq_start,
    .next  = ipmr_mfc_seq_next,
    .stop  = ipmr_mfc_seq_stop,
    .show  = ipmr_mfc_seq_show,
};

static int ipmr_mfc_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &ipmr_mfc_seq_ops,
                sizeof(struct ipmr_mfc_iter));
}

static const struct file_operations ipmr_mfc_fops = {
    .owner   = THIS_MODULE,
    .open    = ipmr_mfc_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};
#endif

#ifdef CONFIG_IP_PIMSM_V2
static const struct net_protocol pim_protocol = {
    .handler    =   pim_rcv,
    .netns_ok   =   1,
};
#endif


/*
 *  Setup for IP multicast routing
 */
static int __net_init ipmr_net_init(struct net *net)
{
    int err;

    err = ipmr_rules_init(net);
    if (err < 0)
        goto fail;

#ifdef CONFIG_PROC_FS
    err = -ENOMEM;
    if (!proc_net_fops_create(net, "ip_mr_vif", 0, &ipmr_vif_fops))
        goto proc_vif_fail;
    if (!proc_net_fops_create(net, "ip_mr_cache", 0, &ipmr_mfc_fops))
        goto proc_cache_fail;
#endif
    return 0;

#ifdef CONFIG_PROC_FS
proc_cache_fail:
    proc_net_remove(net, "ip_mr_vif");
proc_vif_fail:
    ipmr_rules_exit(net);
#endif
fail:
    return err;
}

static void __net_exit ipmr_net_exit(struct net *net)
{
#ifdef CONFIG_PROC_FS
    proc_net_remove(net, "ip_mr_cache");
    proc_net_remove(net, "ip_mr_vif");
#endif
    ipmr_rules_exit(net);
}

static struct pernet_operations ipmr_net_ops = {
    .init = ipmr_net_init,
    .exit = ipmr_net_exit,
};

int __init ip_mr_init(void)
{
    int err;

    mrt_cachep = kmem_cache_create("ip_mrt_cache",
                       sizeof(struct mfc_cache),
                       0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
                       NULL);
    if (!mrt_cachep)
        return -ENOMEM;

    err = register_pernet_subsys(&ipmr_net_ops);
    if (err)
        goto reg_pernet_fail;

    err = register_netdevice_notifier(&ip_mr_notifier);
    if (err)
        goto reg_notif_fail;
#ifdef CONFIG_IP_PIMSM_V2
    if (inet_add_protocol(&pim_protocol, IPPROTO_PIM) < 0) {
        pr_err("%s: can't add PIM protocol\n", __func__);
        err = -EAGAIN;
        goto add_proto_fail;
    }
#endif
    rtnl_register(RTNL_FAMILY_IPMR, RTM_GETROUTE,
              NULL, ipmr_rtm_dumproute, NULL);
    return 0;

#ifdef CONFIG_IP_PIMSM_V2
add_proto_fail:
    unregister_netdevice_notifier(&ip_mr_notifier);
#endif
reg_notif_fail:
    unregister_pernet_subsys(&ipmr_net_ops);
reg_pernet_fail:
    kmem_cache_destroy(mrt_cachep);
    return err;
}