/*
 *      Linux NET3:     Internet Group Management Protocol  [IGMP]
 *
 *      This code implements the IGMP protocol as defined in RFC1112. There has
 *      been a further revision of this protocol since which is now supported.
 *
 *      If you have trouble with this module be careful what gcc you have used,
 *      the older version didn't come out right using gcc 2.5.8, the newer one
 *      seems to fall out with gcc 2.6.2.
 *
 *      Authors:
 *              Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 *      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:
 *
 *              Alan Cox        :       Added lots of __inline__ to optimise
 *                                      the memory usage of all the tiny little
 *                                      functions.
 *              Alan Cox        :       Dumped the header building experiment.
 *              Alan Cox        :       Minor tweaks ready for multicast routing
 *                                      and extended IGMP protocol.
 *              Alan Cox        :       Removed a load of inline directives. Gcc 2.5.8
 *                                      writes utterly bogus code otherwise (sigh)
 *                                      fixed IGMP loopback to behave in the manner
 *                                      desired by mrouted, fixed the fact it has been
 *                                      broken since 1.3.6 and cleaned up a few minor
 *                                      points.
 *
 *              Chih-Jen Chang  :       Tried to revise IGMP to Version 2
 *              Tsu-Sheng Tsao          E-mail: chihjenc@scf.usc.edu and tsusheng@scf.usc.edu
 *                                      The enhancements are mainly based on Steve Deering's
 *                                      ipmulti-3.5 source code.
 *              Chih-Jen Chang  :       Added the igmp_get_mrouter_info and
 *              Tsu-Sheng Tsao          igmp_set_mrouter_info to keep track of
 *                                      the mrouted version on that device.
 *              Chih-Jen Chang  :       Added the max_resp_time parameter to
 *              Tsu-Sheng Tsao          igmp_heard_query(). Using this parameter
 *                                      to identify the multicast router version
 *                                      and do what the IGMP version 2 specified.
 *              Chih-Jen Chang  :       Added a timer to revert to IGMP V2 router
 *              Tsu-Sheng Tsao          if the specified time expired.
 *              Alan Cox        :       Stop IGMP from 0.0.0.0 being accepted.
 *              Alan Cox        :       Use GFP_ATOMIC in the right places.
 *              Christian Daudt :       igmp timer wasn't set for local group
 *                                      memberships but was being deleted,
 *                                      which caused a "del_timer() called
 *                                      from %p with timer not initialized\n"
 *                                      message (960131).
 *              Christian Daudt :       removed del_timer from
 *                                      igmp_timer_expire function (960205).
 *             Christian Daudt :       igmp_heard_report now only calls
 *                                     igmp_timer_expire if tm->running is
 *                                     true (960216).
 *              Malcolm Beattie :       ttl comparison wrong in igmp_rcv made
 *                                      igmp_heard_query never trigger. Expiry
 *                                      miscalculation fixed in igmp_heard_query
 *                                      and random() made to return unsigned to
 *                                      prevent negative expiry times.
 *              Alexey Kuznetsov:       Wrong group leaving behaviour, backport
 *                                      fix from pending 2.1.x patches.
 *              Alan Cox:               Forget to enable FDDI support earlier.
 *              Alexey Kuznetsov:       Fixed leaving groups on device down.
 *              Alexey Kuznetsov:       Accordance to igmp-v2-06 draft.
 *              David L Stevens:        IGMPv3 support, with help from
 *                                      Vinay Kulkarni
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <linux/times.h>
#include <linux/pkt_sched.h>
#include <linux/byteorder/generic.h>

#include <net/net_namespace.h>
#include <net/arp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/inet_common.h>
#include <linux/netfilter_ipv4.h>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif
#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#endif

#ifdef CONFIG_IP_MULTICAST
/* Parameter names and values are taken from igmp-v2-06 draft */

#define IGMP_V2_UNSOLICITED_REPORT_INTERVAL     (10*HZ)
#define IGMP_V3_UNSOLICITED_REPORT_INTERVAL     (1*HZ)
#define IGMP_QUERY_INTERVAL                     (125*HZ)
#define IGMP_QUERY_RESPONSE_INTERVAL            (10*HZ)

#define IGMP_INITIAL_REPORT_DELAY               (1)

/* IGMP_INITIAL_REPORT_DELAY is not from IGMP specs!
 * IGMP specs require to report membership immediately after
 * joining a group, but we delay the first report by a
 * small interval. It seems more natural and still does not
 * contradict to specs provided this delay is small enough.
 */

#define IGMP_V1_SEEN(in_dev) \
        (IPV4_DEVCONF_ALL(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 1 || \
         IN_DEV_CONF_GET((in_dev), FORCE_IGMP_VERSION) == 1 || \
         ((in_dev)->mr_v1_seen && \
          time_before(jiffies, (in_dev)->mr_v1_seen)))
#define IGMP_V2_SEEN(in_dev) \
        (IPV4_DEVCONF_ALL(dev_net(in_dev->dev), FORCE_IGMP_VERSION) == 2 || \
         IN_DEV_CONF_GET((in_dev), FORCE_IGMP_VERSION) == 2 || \
         ((in_dev)->mr_v2_seen && \
          time_before(jiffies, (in_dev)->mr_v2_seen)))

static int unsolicited_report_interval(struct in_device *in_dev)
{
        int interval_ms, interval_jiffies;

        if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev))
                interval_ms = IN_DEV_CONF_GET(
                        in_dev,
                        IGMPV2_UNSOLICITED_REPORT_INTERVAL);
        else /* v3 */
                interval_ms = IN_DEV_CONF_GET(
                        in_dev,
                        IGMPV3_UNSOLICITED_REPORT_INTERVAL);

        interval_jiffies = msecs_to_jiffies(interval_ms);

        /* _timer functions can't handle a delay of 0 jiffies so ensure
         *  we always return a positive value.
         */
        if (interval_jiffies <= 0)
                interval_jiffies = 1;
        return interval_jiffies;
}

static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im);
static void igmpv3_del_delrec(struct in_device *in_dev, struct ip_mc_list *im);
static void igmpv3_clear_delrec(struct in_device *in_dev);
static int sf_setstate(struct ip_mc_list *pmc);
static void sf_markstate(struct ip_mc_list *pmc);
#endif
static void ip_mc_clear_src(struct ip_mc_list *pmc);
static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
                         int sfcount, __be32 *psfsrc, int delta);

static void ip_ma_put(struct ip_mc_list *im)
{
        if (refcount_dec_and_test(&im->refcnt)) {
                in_dev_put(im->interface);
                kfree_rcu(im, rcu);
        }
}

#define for_each_pmc_rcu(in_dev, pmc)                           \
        for (pmc = rcu_dereference(in_dev->mc_list);            \
             pmc != NULL;                                       \
             pmc = rcu_dereference(pmc->next_rcu))

#define for_each_pmc_rtnl(in_dev, pmc)                          \
        for (pmc = rtnl_dereference(in_dev->mc_list);           \
             pmc != NULL;                                       \
             pmc = rtnl_dereference(pmc->next_rcu))

static void ip_sf_list_clear_all(struct ip_sf_list *psf)
{
        struct ip_sf_list *next;

        while (psf) {
                next = psf->sf_next;
                kfree(psf);
                psf = next;
        }
}

#ifdef CONFIG_IP_MULTICAST

/*
 *      Timer management
 */

static void igmp_stop_timer(struct ip_mc_list *im)
{
        spin_lock_bh(&im->lock);
        if (del_timer(&im->timer))
                refcount_dec(&im->refcnt);
        im->tm_running = 0;
        im->reporter = 0;
        im->unsolicit_count = 0;
        spin_unlock_bh(&im->lock);
}

/* It must be called with locked im->lock */
static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
{
        int tv = prandom_u32() % max_delay;

        im->tm_running = 1;
        if (!mod_timer(&im->timer, jiffies+tv+2))
                refcount_inc(&im->refcnt);
}

static void igmp_gq_start_timer(struct in_device *in_dev)
{
        int tv = prandom_u32() % in_dev->mr_maxdelay;
        unsigned long exp = jiffies + tv + 2;

        if (in_dev->mr_gq_running &&
            time_after_eq(exp, (in_dev->mr_gq_timer).expires))
                return;

        in_dev->mr_gq_running = 1;
        if (!mod_timer(&in_dev->mr_gq_timer, exp))
                in_dev_hold(in_dev);
}

static void igmp_ifc_start_timer(struct in_device *in_dev, int delay)
{
        int tv = prandom_u32() % delay;

        if (!mod_timer(&in_dev->mr_ifc_timer, jiffies+tv+2))
                in_dev_hold(in_dev);
}

static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
{
        spin_lock_bh(&im->lock);
        im->unsolicit_count = 0;
        if (del_timer(&im->timer)) {
                if ((long)(im->timer.expires-jiffies) < max_delay) {
                        add_timer(&im->timer);
                        im->tm_running = 1;
                        spin_unlock_bh(&im->lock);
                        return;
                }
                refcount_dec(&im->refcnt);
        }
        igmp_start_timer(im, max_delay);
        spin_unlock_bh(&im->lock);
}


/*
 *      Send an IGMP report.
 */

#define IGMP_SIZE (sizeof(struct igmphdr)+sizeof(struct iphdr)+4)


static int is_in(struct ip_mc_list *pmc, struct ip_sf_list *psf, int type,
        int gdeleted, int sdeleted)
{
        switch (type) {
        case IGMPV3_MODE_IS_INCLUDE:
        case IGMPV3_MODE_IS_EXCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                if (!(pmc->gsquery && !psf->sf_gsresp)) {
                        if (pmc->sfmode == MCAST_INCLUDE)
                                return 1;
                        /* don't include if this source is excluded
                         * in all filters
                         */
                        if (psf->sf_count[MCAST_INCLUDE])
                                return type == IGMPV3_MODE_IS_INCLUDE;
                        return pmc->sfcount[MCAST_EXCLUDE] ==
                                psf->sf_count[MCAST_EXCLUDE];
                }
                return 0;
        case IGMPV3_CHANGE_TO_INCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                return psf->sf_count[MCAST_INCLUDE] != 0;
        case IGMPV3_CHANGE_TO_EXCLUDE:
                if (gdeleted || sdeleted)
                        return 0;
                if (pmc->sfcount[MCAST_EXCLUDE] == 0 ||
                    psf->sf_count[MCAST_INCLUDE])
                        return 0;
                return pmc->sfcount[MCAST_EXCLUDE] ==
                        psf->sf_count[MCAST_EXCLUDE];
        case IGMPV3_ALLOW_NEW_SOURCES:
                if (gdeleted || !psf->sf_crcount)
                        return 0;
                return (pmc->sfmode == MCAST_INCLUDE) ^ sdeleted;
        case IGMPV3_BLOCK_OLD_SOURCES:
                if (pmc->sfmode == MCAST_INCLUDE)
                        return gdeleted || (psf->sf_crcount && sdeleted);
                return psf->sf_crcount && !gdeleted && !sdeleted;
        }
        return 0;
}

static int
igmp_scount(struct ip_mc_list *pmc, int type, int gdeleted, int sdeleted)
{
        struct ip_sf_list *psf;
        int scount = 0;

        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (!is_in(pmc, psf, type, gdeleted, sdeleted))
                        continue;
                scount++;
        }
        return scount;
}

/* source address selection per RFC 3376 section 4.2.13 */
static __be32 igmpv3_get_srcaddr(struct net_device *dev,
                                 const struct flowi4 *fl4)
{
        struct in_device *in_dev = __in_dev_get_rcu(dev);
        const struct in_ifaddr *ifa;

        if (!in_dev)
                return htonl(INADDR_ANY);

        in_dev_for_each_ifa_rcu(ifa, in_dev) {
                if (fl4->saddr == ifa->ifa_local)
                        return fl4->saddr;
        }

        return htonl(INADDR_ANY);
}

static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu)
{
        struct sk_buff *skb;
        struct rtable *rt;
        struct iphdr *pip;
        struct igmpv3_report *pig;
        struct net *net = dev_net(dev);
        struct flowi4 fl4;
        int hlen = LL_RESERVED_SPACE(dev);
        int tlen = dev->needed_tailroom;
        unsigned int size = mtu;

        while (1) {
                skb = alloc_skb(size + hlen + tlen,
                                GFP_ATOMIC | __GFP_NOWARN);
                if (skb)
                        break;
                size >>= 1;
                if (size < 256)
                        return NULL;
        }
        skb->priority = TC_PRIO_CONTROL;

        rt = ip_route_output_ports(net, &fl4, NULL, IGMPV3_ALL_MCR, 0,
                                   0, 0,
                                   IPPROTO_IGMP, 0, dev->ifindex);
        if (IS_ERR(rt)) {
                kfree_skb(skb);
                return NULL;
        }

        skb_dst_set(skb, &rt->dst);
        skb->dev = dev;

        skb_reserve(skb, hlen);
        skb_tailroom_reserve(skb, mtu, tlen);

        skb_reset_network_header(skb);
        pip = ip_hdr(skb);
        skb_put(skb, sizeof(struct iphdr) + 4);

        pip->version  = 4;
        pip->ihl      = (sizeof(struct iphdr)+4)>>2;
        pip->tos      = 0xc0;
        pip->frag_off = htons(IP_DF);
        pip->ttl      = 1;
        pip->daddr    = fl4.daddr;

        rcu_read_lock();
        pip->saddr    = igmpv3_get_srcaddr(dev, &fl4);
        rcu_read_unlock();

        pip->protocol = IPPROTO_IGMP;
        pip->tot_len  = 0;      /* filled in later */
        ip_select_ident(net, skb, NULL);
        ((u8 *)&pip[1])[0] = IPOPT_RA;
        ((u8 *)&pip[1])[1] = 4;
        ((u8 *)&pip[1])[2] = 0;
        ((u8 *)&pip[1])[3] = 0;

        skb->transport_header = skb->network_header + sizeof(struct iphdr) + 4;
        skb_put(skb, sizeof(*pig));
        pig = igmpv3_report_hdr(skb);
        pig->type = IGMPV3_HOST_MEMBERSHIP_REPORT;
        pig->resv1 = 0;
        pig->csum = 0;
        pig->resv2 = 0;
        pig->ngrec = 0;
        return skb;
}

static int igmpv3_sendpack(struct sk_buff *skb)
{
        struct igmphdr *pig = igmp_hdr(skb);
        const int igmplen = skb_tail_pointer(skb) - skb_transport_header(skb);

        pig->csum = ip_compute_csum(igmp_hdr(skb), igmplen);

        return ip_local_out(dev_net(skb_dst(skb)->dev), skb->sk, skb);
}

static int grec_size(struct ip_mc_list *pmc, int type, int gdel, int sdel)
{
        return sizeof(struct igmpv3_grec) + 4*igmp_scount(pmc, type, gdel, sdel);
}

static struct sk_buff *add_grhead(struct sk_buff *skb, struct ip_mc_list *pmc,
        int type, struct igmpv3_grec **ppgr, unsigned int mtu)
{
        struct net_device *dev = pmc->interface->dev;
        struct igmpv3_report *pih;
        struct igmpv3_grec *pgr;

        if (!skb) {
                skb = igmpv3_newpack(dev, mtu);
                if (!skb)
                        return NULL;
        }
        pgr = skb_put(skb, sizeof(struct igmpv3_grec));
        pgr->grec_type = type;
        pgr->grec_auxwords = 0;
        pgr->grec_nsrcs = 0;
        pgr->grec_mca = pmc->multiaddr;
        pih = igmpv3_report_hdr(skb);
        pih->ngrec = htons(ntohs(pih->ngrec)+1);
        *ppgr = pgr;
        return skb;
}

#define AVAILABLE(skb)  ((skb) ? skb_availroom(skb) : 0)

static struct sk_buff *add_grec(struct sk_buff *skb, struct ip_mc_list *pmc,
        int type, int gdeleted, int sdeleted)
{
        struct net_device *dev = pmc->interface->dev;
        struct net *net = dev_net(dev);
        struct igmpv3_report *pih;
        struct igmpv3_grec *pgr = NULL;
        struct ip_sf_list *psf, *psf_next, *psf_prev, **psf_list;
        int scount, stotal, first, isquery, truncate;
        unsigned int mtu;

        if (pmc->multiaddr == IGMP_ALL_HOSTS)
                return skb;
        if (ipv4_is_local_multicast(pmc->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)
                return skb;

        mtu = READ_ONCE(dev->mtu);
        if (mtu < IPV4_MIN_MTU)
                return skb;

        isquery = type == IGMPV3_MODE_IS_INCLUDE ||
                  type == IGMPV3_MODE_IS_EXCLUDE;
        truncate = type == IGMPV3_MODE_IS_EXCLUDE ||
                    type == IGMPV3_CHANGE_TO_EXCLUDE;

        stotal = scount = 0;

        psf_list = sdeleted ? &pmc->tomb : &pmc->sources;

        if (!*psf_list)
                goto empty_source;

        pih = skb ? igmpv3_report_hdr(skb) : NULL;

        /* EX and TO_EX get a fresh packet, if needed */
        if (truncate) {
                if (pih && pih->ngrec &&
                    AVAILABLE(skb) < grec_size(pmc, type, gdeleted, sdeleted)) {
                        if (skb)
                                igmpv3_sendpack(skb);
                        skb = igmpv3_newpack(dev, mtu);
                }
        }
        first = 1;
        psf_prev = NULL;
        for (psf = *psf_list; psf; psf = psf_next) {
                __be32 *psrc;

                psf_next = psf->sf_next;

                if (!is_in(pmc, psf, type, gdeleted, sdeleted)) {
                        psf_prev = psf;
                        continue;
                }

                /* Based on RFC3376 5.1. Should not send source-list change
                 * records when there is a filter mode change.
                 */
                if (((gdeleted && pmc->sfmode == MCAST_EXCLUDE) ||
                     (!gdeleted && pmc->crcount)) &&
                    (type == IGMPV3_ALLOW_NEW_SOURCES ||
                     type == IGMPV3_BLOCK_OLD_SOURCES) && psf->sf_crcount)
                        goto decrease_sf_crcount;

                /* clear marks on query responses */
                if (isquery)
                        psf->sf_gsresp = 0;

                if (AVAILABLE(skb) < sizeof(__be32) +
                    first*sizeof(struct igmpv3_grec)) {
                        if (truncate && !first)
                                break;   /* truncate these */
                        if (pgr)
                                pgr->grec_nsrcs = htons(scount);
                        if (skb)
                                igmpv3_sendpack(skb);
                        skb = igmpv3_newpack(dev, mtu);
                        first = 1;
                        scount = 0;
                }
                if (first) {
                        skb = add_grhead(skb, pmc, type, &pgr, mtu);
                        first = 0;
                }
                if (!skb)
                        return NULL;
                psrc = skb_put(skb, sizeof(__be32));
                *psrc = psf->sf_inaddr;
                scount++; stotal++;
                if ((type == IGMPV3_ALLOW_NEW_SOURCES ||
                     type == IGMPV3_BLOCK_OLD_SOURCES) && psf->sf_crcount) {
decrease_sf_crcount:
                        psf->sf_crcount--;
                        if ((sdeleted || gdeleted) && psf->sf_crcount == 0) {
                                if (psf_prev)
                                        psf_prev->sf_next = psf->sf_next;
                                else
                                        *psf_list = psf->sf_next;
                                kfree(psf);
                                continue;
                        }
                }
                psf_prev = psf;
        }

empty_source:
        if (!stotal) {
                if (type == IGMPV3_ALLOW_NEW_SOURCES ||
                    type == IGMPV3_BLOCK_OLD_SOURCES)
                        return skb;
                if (pmc->crcount || isquery) {
                        /* make sure we have room for group header */
                        if (skb && AVAILABLE(skb) < sizeof(struct igmpv3_grec)) {
                                igmpv3_sendpack(skb);
                                skb = NULL; /* add_grhead will get a new one */
                        }
                        skb = add_grhead(skb, pmc, type, &pgr, mtu);
                }
        }
        if (pgr)
                pgr->grec_nsrcs = htons(scount);

        if (isquery)
                pmc->gsquery = 0;       /* clear query state on report */
        return skb;
}

static int igmpv3_send_report(struct in_device *in_dev, struct ip_mc_list *pmc)
{
        struct sk_buff *skb = NULL;
        struct net *net = dev_net(in_dev->dev);
        int type;

        if (!pmc) {
                rcu_read_lock();
                for_each_pmc_rcu(in_dev, pmc) {
                        if (pmc->multiaddr == IGMP_ALL_HOSTS)
                                continue;
                        if (ipv4_is_local_multicast(pmc->multiaddr) &&
                             !net->ipv4.sysctl_igmp_llm_reports)
                                continue;
                        spin_lock_bh(&pmc->lock);
                        if (pmc->sfcount[MCAST_EXCLUDE])
                                type = IGMPV3_MODE_IS_EXCLUDE;
                        else
                                type = IGMPV3_MODE_IS_INCLUDE;
                        skb = add_grec(skb, pmc, type, 0, 0);
                        spin_unlock_bh(&pmc->lock);
                }
                rcu_read_unlock();
        } else {
                spin_lock_bh(&pmc->lock);
                if (pmc->sfcount[MCAST_EXCLUDE])
                        type = IGMPV3_MODE_IS_EXCLUDE;
                else
                        type = IGMPV3_MODE_IS_INCLUDE;
                skb = add_grec(skb, pmc, type, 0, 0);
                spin_unlock_bh(&pmc->lock);
        }
        if (!skb)
                return 0;
        return igmpv3_sendpack(skb);
}

/*
 * remove zero-count source records from a source filter list
 */
static void igmpv3_clear_zeros(struct ip_sf_list **ppsf)
{
        struct ip_sf_list *psf_prev, *psf_next, *psf;

        psf_prev = NULL;
        for (psf = *ppsf; psf; psf = psf_next) {
                psf_next = psf->sf_next;
                if (psf->sf_crcount == 0) {
                        if (psf_prev)
                                psf_prev->sf_next = psf->sf_next;
                        else
                                *ppsf = psf->sf_next;
                        kfree(psf);
                } else
                        psf_prev = psf;
        }
}

static void kfree_pmc(struct ip_mc_list *pmc)
{
        ip_sf_list_clear_all(pmc->sources);
        ip_sf_list_clear_all(pmc->tomb);
        kfree(pmc);
}

static void igmpv3_send_cr(struct in_device *in_dev)
{
        struct ip_mc_list *pmc, *pmc_prev, *pmc_next;
        struct sk_buff *skb = NULL;
        int type, dtype;

        rcu_read_lock();
        spin_lock_bh(&in_dev->mc_tomb_lock);

        /* deleted MCA's */
        pmc_prev = NULL;
        for (pmc = in_dev->mc_tomb; pmc; pmc = pmc_next) {
                pmc_next = pmc->next;
                if (pmc->sfmode == MCAST_INCLUDE) {
                        type = IGMPV3_BLOCK_OLD_SOURCES;
                        dtype = IGMPV3_BLOCK_OLD_SOURCES;
                        skb = add_grec(skb, pmc, type, 1, 0);
                        skb = add_grec(skb, pmc, dtype, 1, 1);
                }
                if (pmc->crcount) {
                        if (pmc->sfmode == MCAST_EXCLUDE) {
                                type = IGMPV3_CHANGE_TO_INCLUDE;
                                skb = add_grec(skb, pmc, type, 1, 0);
                        }
                        pmc->crcount--;
                        if (pmc->crcount == 0) {
                                igmpv3_clear_zeros(&pmc->tomb);
                                igmpv3_clear_zeros(&pmc->sources);
                        }
                }
                if (pmc->crcount == 0 && !pmc->tomb && !pmc->sources) {
                        if (pmc_prev)
                                pmc_prev->next = pmc_next;
                        else
                                in_dev->mc_tomb = pmc_next;
                        in_dev_put(pmc->interface);
                        kfree_pmc(pmc);
                } else
                        pmc_prev = pmc;
        }
        spin_unlock_bh(&in_dev->mc_tomb_lock);

        /* change recs */
        for_each_pmc_rcu(in_dev, pmc) {
                spin_lock_bh(&pmc->lock);
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        type = IGMPV3_BLOCK_OLD_SOURCES;
                        dtype = IGMPV3_ALLOW_NEW_SOURCES;
                } else {
                        type = IGMPV3_ALLOW_NEW_SOURCES;
                        dtype = IGMPV3_BLOCK_OLD_SOURCES;
                }
                skb = add_grec(skb, pmc, type, 0, 0);
                skb = add_grec(skb, pmc, dtype, 0, 1);  /* deleted sources */

                /* filter mode changes */
                if (pmc->crcount) {
                        if (pmc->sfmode == MCAST_EXCLUDE)
                                type = IGMPV3_CHANGE_TO_EXCLUDE;
                        else
                                type = IGMPV3_CHANGE_TO_INCLUDE;
                        skb = add_grec(skb, pmc, type, 0, 0);
                        pmc->crcount--;
                }
                spin_unlock_bh(&pmc->lock);
        }
        rcu_read_unlock();

        if (!skb)
                return;
        (void) igmpv3_sendpack(skb);
}

static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc,
        int type)
{
        struct sk_buff *skb;
        struct iphdr *iph;
        struct igmphdr *ih;
        struct rtable *rt;
        struct net_device *dev = in_dev->dev;
        struct net *net = dev_net(dev);
        __be32  group = pmc ? pmc->multiaddr : 0;
        struct flowi4 fl4;
        __be32  dst;
        int hlen, tlen;

        if (type == IGMPV3_HOST_MEMBERSHIP_REPORT)
                return igmpv3_send_report(in_dev, pmc);

        if (ipv4_is_local_multicast(group) && !net->ipv4.sysctl_igmp_llm_reports)
                return 0;

        if (type == IGMP_HOST_LEAVE_MESSAGE)
                dst = IGMP_ALL_ROUTER;
        else
                dst = group;

        rt = ip_route_output_ports(net, &fl4, NULL, dst, 0,
                                   0, 0,
                                   IPPROTO_IGMP, 0, dev->ifindex);
        if (IS_ERR(rt))
                return -1;

        hlen = LL_RESERVED_SPACE(dev);
        tlen = dev->needed_tailroom;
        skb = alloc_skb(IGMP_SIZE + hlen + tlen, GFP_ATOMIC);
        if (!skb) {
                ip_rt_put(rt);
                return -1;
        }
        skb->priority = TC_PRIO_CONTROL;

        skb_dst_set(skb, &rt->dst);

        skb_reserve(skb, hlen);

        skb_reset_network_header(skb);
        iph = ip_hdr(skb);
        skb_put(skb, sizeof(struct iphdr) + 4);

        iph->version  = 4;
        iph->ihl      = (sizeof(struct iphdr)+4)>>2;
        iph->tos      = 0xc0;
        iph->frag_off = htons(IP_DF);
        iph->ttl      = 1;
        iph->daddr    = dst;
        iph->saddr    = fl4.saddr;
        iph->protocol = IPPROTO_IGMP;
        ip_select_ident(net, skb, NULL);
        ((u8 *)&iph[1])[0] = IPOPT_RA;
        ((u8 *)&iph[1])[1] = 4;
        ((u8 *)&iph[1])[2] = 0;
        ((u8 *)&iph[1])[3] = 0;

        ih = skb_put(skb, sizeof(struct igmphdr));
        ih->type = type;
        ih->code = 0;
        ih->csum = 0;
        ih->group = group;
        ih->csum = ip_compute_csum((void *)ih, sizeof(struct igmphdr));

        return ip_local_out(net, skb->sk, skb);
}

static void igmp_gq_timer_expire(struct timer_list *t)
{
        struct in_device *in_dev = from_timer(in_dev, t, mr_gq_timer);

        in_dev->mr_gq_running = 0;
        igmpv3_send_report(in_dev, NULL);
        in_dev_put(in_dev);
}

static void igmp_ifc_timer_expire(struct timer_list *t)
{
        struct in_device *in_dev = from_timer(in_dev, t, mr_ifc_timer);

        igmpv3_send_cr(in_dev);
        if (in_dev->mr_ifc_count) {
                in_dev->mr_ifc_count--;
                igmp_ifc_start_timer(in_dev,
                                     unsolicited_report_interval(in_dev));
        }
        in_dev_put(in_dev);
}

static void igmp_ifc_event(struct in_device *in_dev)
{
        struct net *net = dev_net(in_dev->dev);
        if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev))
                return;
        in_dev->mr_ifc_count = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
        igmp_ifc_start_timer(in_dev, 1);
}


static void igmp_timer_expire(struct timer_list *t)
{
        struct ip_mc_list *im = from_timer(im, t, timer);
        struct in_device *in_dev = im->interface;

        spin_lock(&im->lock);
        im->tm_running = 0;

        if (im->unsolicit_count && --im->unsolicit_count)
                igmp_start_timer(im, unsolicited_report_interval(in_dev));

        im->reporter = 1;
        spin_unlock(&im->lock);

        if (IGMP_V1_SEEN(in_dev))
                igmp_send_report(in_dev, im, IGMP_HOST_MEMBERSHIP_REPORT);
        else if (IGMP_V2_SEEN(in_dev))
                igmp_send_report(in_dev, im, IGMPV2_HOST_MEMBERSHIP_REPORT);
        else
                igmp_send_report(in_dev, im, IGMPV3_HOST_MEMBERSHIP_REPORT);

        ip_ma_put(im);
}

/* mark EXCLUDE-mode sources */
static int igmp_xmarksources(struct ip_mc_list *pmc, int nsrcs, __be32 *srcs)
{
        struct ip_sf_list *psf;
        int i, scount;

        scount = 0;
        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (scount == nsrcs)
                        break;
                for (i = 0; i < nsrcs; i++) {
                        /* skip inactive filters */
                        if (psf->sf_count[MCAST_INCLUDE] ||
                            pmc->sfcount[MCAST_EXCLUDE] !=
                            psf->sf_count[MCAST_EXCLUDE])
                                break;
                        if (srcs[i] == psf->sf_inaddr) {
                                scount++;
                                break;
                        }
                }
        }
        pmc->gsquery = 0;
        if (scount == nsrcs)    /* all sources excluded */
                return 0;
        return 1;
}

static int igmp_marksources(struct ip_mc_list *pmc, int nsrcs, __be32 *srcs)
{
        struct ip_sf_list *psf;
        int i, scount;

        if (pmc->sfmode == MCAST_EXCLUDE)
                return igmp_xmarksources(pmc, nsrcs, srcs);

        /* mark INCLUDE-mode sources */
        scount = 0;
        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (scount == nsrcs)
                        break;
                for (i = 0; i < nsrcs; i++)
                        if (srcs[i] == psf->sf_inaddr) {
                                psf->sf_gsresp = 1;
                                scount++;
                                break;
                        }
        }
        if (!scount) {
                pmc->gsquery = 0;
                return 0;
        }
        pmc->gsquery = 1;
        return 1;
}

/* return true if packet was dropped */
static bool igmp_heard_report(struct in_device *in_dev, __be32 group)
{
        struct ip_mc_list *im;
        struct net *net = dev_net(in_dev->dev);

        /* Timers are only set for non-local groups */

        if (group == IGMP_ALL_HOSTS)
                return false;
        if (ipv4_is_local_multicast(group) && !net->ipv4.sysctl_igmp_llm_reports)
                return false;

        rcu_read_lock();
        for_each_pmc_rcu(in_dev, im) {
                if (im->multiaddr == group) {
                        igmp_stop_timer(im);
                        break;
                }
        }
        rcu_read_unlock();
        return false;
}

/* return true if packet was dropped */
static bool igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
        int len)
{
        struct igmphdr          *ih = igmp_hdr(skb);
        struct igmpv3_query *ih3 = igmpv3_query_hdr(skb);
        struct ip_mc_list       *im;
        __be32                  group = ih->group;
        int                     max_delay;
        int                     mark = 0;
        struct net              *net = dev_net(in_dev->dev);


        if (len == 8) {
                if (ih->code == 0) {
                        /* Alas, old v1 router presents here. */

                        max_delay = IGMP_QUERY_RESPONSE_INTERVAL;
                        in_dev->mr_v1_seen = jiffies +
                                (in_dev->mr_qrv * in_dev->mr_qi) +
                                in_dev->mr_qri;
                        group = 0;
                } else {
                        /* v2 router present */
                        max_delay = ih->code*(HZ/IGMP_TIMER_SCALE);
                        in_dev->mr_v2_seen = jiffies +
                                (in_dev->mr_qrv * in_dev->mr_qi) +
                                in_dev->mr_qri;
                }
                /* cancel the interface change timer */
                in_dev->mr_ifc_count = 0;
                if (del_timer(&in_dev->mr_ifc_timer))
                        __in_dev_put(in_dev);
                /* clear deleted report items */
                igmpv3_clear_delrec(in_dev);
        } else if (len < 12) {
                return true;    /* ignore bogus packet; freed by caller */
        } else if (IGMP_V1_SEEN(in_dev)) {
                /* This is a v3 query with v1 queriers present */
                max_delay = IGMP_QUERY_RESPONSE_INTERVAL;
                group = 0;
        } else if (IGMP_V2_SEEN(in_dev)) {
                /* this is a v3 query with v2 queriers present;
                 * Interpretation of the max_delay code is problematic here.
                 * A real v2 host would use ih_code directly, while v3 has a
                 * different encoding. We use the v3 encoding as more likely
                 * to be intended in a v3 query.
                 */
                max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
                if (!max_delay)
                        max_delay = 1;  /* can't mod w/ 0 */
        } else { /* v3 */
                if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)))
                        return true;

                ih3 = igmpv3_query_hdr(skb);
                if (ih3->nsrcs) {
                        if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)
                                           + ntohs(ih3->nsrcs)*sizeof(__be32)))
                                return true;
                        ih3 = igmpv3_query_hdr(skb);
                }

                max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
                if (!max_delay)
                        max_delay = 1;  /* can't mod w/ 0 */

                in_dev->mr_maxdelay = max_delay;

                /* RFC3376, 4.1.6. QRV and 4.1.7. QQIC, when the most recently
                 * received value was zero, use the default or statically
                 * configured value.
                 */
                in_dev->mr_qrv = ih3->qrv ?: net->ipv4.sysctl_igmp_qrv;
                in_dev->mr_qi = IGMPV3_QQIC(ih3->qqic)*HZ ?: IGMP_QUERY_INTERVAL;

                /* RFC3376, 8.3. Query Response Interval:
                 * The number of seconds represented by the [Query Response
                 * Interval] must be less than the [Query Interval].
                 */
                if (in_dev->mr_qri >= in_dev->mr_qi)
                        in_dev->mr_qri = (in_dev->mr_qi/HZ - 1)*HZ;

                if (!group) { /* general query */
                        if (ih3->nsrcs)
                                return true;    /* no sources allowed */
                        igmp_gq_start_timer(in_dev);
                        return false;
                }
                /* mark sources to include, if group & source-specific */
                mark = ih3->nsrcs != 0;
        }

        /*
         * - Start the timers in all of our membership records
         *   that the query applies to for the interface on
         *   which the query arrived excl. those that belong
         *   to a "local" group (224.0.0.X)
         * - For timers already running check if they need to
         *   be reset.
         * - Use the igmp->igmp_code field as the maximum
         *   delay possible
         */
        rcu_read_lock();
        for_each_pmc_rcu(in_dev, im) {
                int changed;

                if (group && group != im->multiaddr)
                        continue;
                if (im->multiaddr == IGMP_ALL_HOSTS)
                        continue;
                if (ipv4_is_local_multicast(im->multiaddr) &&
                    !net->ipv4.sysctl_igmp_llm_reports)
                        continue;
                spin_lock_bh(&im->lock);
                if (im->tm_running)
                        im->gsquery = im->gsquery && mark;
                else
                        im->gsquery = mark;
                changed = !im->gsquery ||
                        igmp_marksources(im, ntohs(ih3->nsrcs), ih3->srcs);
                spin_unlock_bh(&im->lock);
                if (changed)
                        igmp_mod_timer(im, max_delay);
        }
        rcu_read_unlock();
        return false;
}

/* called in rcu_read_lock() section */
int igmp_rcv(struct sk_buff *skb)
{
        /* This basically follows the spec line by line -- see RFC1112 */
        struct igmphdr *ih;
        struct net_device *dev = skb->dev;
        struct in_device *in_dev;
        int len = skb->len;
        bool dropped = true;

        if (netif_is_l3_master(dev)) {
                dev = dev_get_by_index_rcu(dev_net(dev), IPCB(skb)->iif);
                if (!dev)
                        goto drop;
        }

        in_dev = __in_dev_get_rcu(dev);
        if (!in_dev)
                goto drop;

        if (!pskb_may_pull(skb, sizeof(struct igmphdr)))
                goto drop;

        if (skb_checksum_simple_validate(skb))
                goto drop;

        ih = igmp_hdr(skb);
        switch (ih->type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:
                dropped = igmp_heard_query(in_dev, skb, len);
                break;
        case IGMP_HOST_MEMBERSHIP_REPORT:
        case IGMPV2_HOST_MEMBERSHIP_REPORT:
                /* Is it our report looped back? */
                if (rt_is_output_route(skb_rtable(skb)))
                        break;
                /* don't rely on MC router hearing unicast reports */
                if (skb->pkt_type == PACKET_MULTICAST ||
                    skb->pkt_type == PACKET_BROADCAST)
                        dropped = igmp_heard_report(in_dev, ih->group);
                break;
        case IGMP_PIM:
#ifdef CONFIG_IP_PIMSM_V1
                return pim_rcv_v1(skb);
#endif
        case IGMPV3_HOST_MEMBERSHIP_REPORT:
        case IGMP_DVMRP:
        case IGMP_TRACE:
        case IGMP_HOST_LEAVE_MESSAGE:
        case IGMP_MTRACE:
        case IGMP_MTRACE_RESP:
                break;
        default:
                break;
        }

drop:
        if (dropped)
                kfree_skb(skb);
        else
                consume_skb(skb);
        return 0;
}

#endif


/*
 *      Add a filter to a device
 */

static void ip_mc_filter_add(struct in_device *in_dev, __be32 addr)
{
        char buf[MAX_ADDR_LEN];
        struct net_device *dev = in_dev->dev;

        /* Checking for IFF_MULTICAST here is WRONG-WRONG-WRONG.
           We will get multicast token leakage, when IFF_MULTICAST
           is changed. This check should be done in ndo_set_rx_mode
           routine. Something sort of:
           if (dev->mc_list && dev->flags&IFF_MULTICAST) { do it; }
           --ANK
           */
        if (arp_mc_map(addr, buf, dev, 0) == 0)
                dev_mc_add(dev, buf);
}

/*
 *      Remove a filter from a device
 */

static void ip_mc_filter_del(struct in_device *in_dev, __be32 addr)
{
        char buf[MAX_ADDR_LEN];
        struct net_device *dev = in_dev->dev;

        if (arp_mc_map(addr, buf, dev, 0) == 0)
                dev_mc_del(dev, buf);
}

#ifdef CONFIG_IP_MULTICAST
/*
 * deleted ip_mc_list manipulation
 */
static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im)
{
        struct ip_mc_list *pmc;
        struct net *net = dev_net(in_dev->dev);

        /* this is an "ip_mc_list" for convenience; only the fields below
         * are actually used. In particular, the refcnt and users are not
         * used for management of the delete list. Using the same structure
         * for deleted items allows change reports to use common code with
         * non-deleted or query-response MCA's.
         */
        pmc = kzalloc(sizeof(*pmc), GFP_KERNEL);
        if (!pmc)
                return;
        spin_lock_init(&pmc->lock);
        spin_lock_bh(&im->lock);
        pmc->interface = im->interface;
        in_dev_hold(in_dev);
        pmc->multiaddr = im->multiaddr;
        pmc->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
        pmc->sfmode = im->sfmode;
        if (pmc->sfmode == MCAST_INCLUDE) {
                struct ip_sf_list *psf;

                pmc->tomb = im->tomb;
                pmc->sources = im->sources;
                im->tomb = im->sources = NULL;
                for (psf = pmc->sources; psf; psf = psf->sf_next)
                        psf->sf_crcount = pmc->crcount;
        }
        spin_unlock_bh(&im->lock);

        spin_lock_bh(&in_dev->mc_tomb_lock);
        pmc->next = in_dev->mc_tomb;
        in_dev->mc_tomb = pmc;
        spin_unlock_bh(&in_dev->mc_tomb_lock);
}

/*
 * restore ip_mc_list deleted records
 */
static void igmpv3_del_delrec(struct in_device *in_dev, struct ip_mc_list *im)
{
        struct ip_mc_list *pmc, *pmc_prev;
        struct ip_sf_list *psf;
        struct net *net = dev_net(in_dev->dev);
        __be32 multiaddr = im->multiaddr;

        spin_lock_bh(&in_dev->mc_tomb_lock);
        pmc_prev = NULL;
        for (pmc = in_dev->mc_tomb; pmc; pmc = pmc->next) {
                if (pmc->multiaddr == multiaddr)
                        break;
                pmc_prev = pmc;
        }
        if (pmc) {
                if (pmc_prev)
                        pmc_prev->next = pmc->next;
                else
                        in_dev->mc_tomb = pmc->next;
        }
        spin_unlock_bh(&in_dev->mc_tomb_lock);

        spin_lock_bh(&im->lock);
        if (pmc) {
                im->interface = pmc->interface;
                if (im->sfmode == MCAST_INCLUDE) {
                        swap(im->tomb, pmc->tomb);
                        swap(im->sources, pmc->sources);
                        for (psf = im->sources; psf; psf = psf->sf_next)
                                psf->sf_crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
                } else {
                        im->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
                }
                in_dev_put(pmc->interface);
                kfree_pmc(pmc);
        }
        spin_unlock_bh(&im->lock);
}

/*
 * flush ip_mc_list deleted records
 */
static void igmpv3_clear_delrec(struct in_device *in_dev)
{
        struct ip_mc_list *pmc, *nextpmc;

        spin_lock_bh(&in_dev->mc_tomb_lock);
        pmc = in_dev->mc_tomb;
        in_dev->mc_tomb = NULL;
        spin_unlock_bh(&in_dev->mc_tomb_lock);

        for (; pmc; pmc = nextpmc) {
                nextpmc = pmc->next;
                ip_mc_clear_src(pmc);
                in_dev_put(pmc->interface);
                kfree_pmc(pmc);
        }
        /* clear dead sources, too */
        rcu_read_lock();
        for_each_pmc_rcu(in_dev, pmc) {
                struct ip_sf_list *psf;

                spin_lock_bh(&pmc->lock);
                psf = pmc->tomb;
                pmc->tomb = NULL;
                spin_unlock_bh(&pmc->lock);
                ip_sf_list_clear_all(psf);
        }
        rcu_read_unlock();
}
#endif

static void igmp_group_dropped(struct ip_mc_list *im)
{
        struct in_device *in_dev = im->interface;
#ifdef CONFIG_IP_MULTICAST
        struct net *net = dev_net(in_dev->dev);
        int reporter;
#endif

        if (im->loaded) {
                im->loaded = 0;
                ip_mc_filter_del(in_dev, im->multiaddr);
        }

#ifdef CONFIG_IP_MULTICAST
        if (im->multiaddr == IGMP_ALL_HOSTS)
                return;
        if (ipv4_is_local_multicast(im->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)
                return;

        reporter = im->reporter;
        igmp_stop_timer(im);

        if (!in_dev->dead) {
                if (IGMP_V1_SEEN(in_dev))
                        return;
                if (IGMP_V2_SEEN(in_dev)) {
                        if (reporter)
                                igmp_send_report(in_dev, im, IGMP_HOST_LEAVE_MESSAGE);
                        return;
                }
                /* IGMPv3 */
                igmpv3_add_delrec(in_dev, im);

                igmp_ifc_event(in_dev);
        }
#endif
}

static void igmp_group_added(struct ip_mc_list *im, unsigned int mode)
{
        struct in_device *in_dev = im->interface;
#ifdef CONFIG_IP_MULTICAST
        struct net *net = dev_net(in_dev->dev);
#endif

        if (im->loaded == 0) {
                im->loaded = 1;
                ip_mc_filter_add(in_dev, im->multiaddr);
        }

#ifdef CONFIG_IP_MULTICAST
        if (im->multiaddr == IGMP_ALL_HOSTS)
                return;
        if (ipv4_is_local_multicast(im->multiaddr) && !net->ipv4.sysctl_igmp_llm_reports)
                return;

        if (in_dev->dead)
                return;

        im->unsolicit_count = net->ipv4.sysctl_igmp_qrv;
        if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev)) {
                spin_lock_bh(&im->lock);
                igmp_start_timer(im, IGMP_INITIAL_REPORT_DELAY);
                spin_unlock_bh(&im->lock);
                return;
        }
        /* else, v3 */

        /* Based on RFC3376 5.1, for newly added INCLUDE SSM, we should
         * not send filter-mode change record as the mode should be from
         * IN() to IN(A).
         */
        if (mode == MCAST_EXCLUDE)
                im->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;

        igmp_ifc_event(in_dev);
#endif
}


/*
 *      Multicast list managers
 */

static u32 ip_mc_hash(const struct ip_mc_list *im)
{
        return hash_32((__force u32)im->multiaddr, MC_HASH_SZ_LOG);
}

static void ip_mc_hash_add(struct in_device *in_dev,
                           struct ip_mc_list *im)
{
        struct ip_mc_list __rcu **mc_hash;
        u32 hash;

        mc_hash = rtnl_dereference(in_dev->mc_hash);
        if (mc_hash) {
                hash = ip_mc_hash(im);
                im->next_hash = mc_hash[hash];
                rcu_assign_pointer(mc_hash[hash], im);
                return;
        }

        /* do not use a hash table for small number of items */
        if (in_dev->mc_count < 4)
                return;

        mc_hash = kzalloc(sizeof(struct ip_mc_list *) << MC_HASH_SZ_LOG,
                          GFP_KERNEL);
        if (!mc_hash)
                return;

        for_each_pmc_rtnl(in_dev, im) {
                hash = ip_mc_hash(im);
                im->next_hash = mc_hash[hash];
                RCU_INIT_POINTER(mc_hash[hash], im);
        }

        rcu_assign_pointer(in_dev->mc_hash, mc_hash);
}

static void ip_mc_hash_remove(struct in_device *in_dev,
                              struct ip_mc_list *im)
{
        struct ip_mc_list __rcu **mc_hash = rtnl_dereference(in_dev->mc_hash);
        struct ip_mc_list *aux;

        if (!mc_hash)
                return;
        mc_hash += ip_mc_hash(im);
        while ((aux = rtnl_dereference(*mc_hash)) != im)
                mc_hash = &aux->next_hash;
        *mc_hash = im->next_hash;
}


/*
 *      A socket has joined a multicast group on device dev.
 */
static void __ip_mc_inc_group(struct in_device *in_dev, __be32 addr,
                              unsigned int mode)
{
        struct ip_mc_list *im;

        ASSERT_RTNL();

        for_each_pmc_rtnl(in_dev, im) {
                if (im->multiaddr == addr) {
                        im->users++;
                        ip_mc_add_src(in_dev, &addr, mode, 0, NULL, 0);
                        goto out;
                }
        }

        im = kzalloc(sizeof(*im), GFP_KERNEL);
        if (!im)
                goto out;

        im->users = 1;
        im->interface = in_dev;
        in_dev_hold(in_dev);
        im->multiaddr = addr;
        /* initial mode is (EX, empty) */
        im->sfmode = mode;
        im->sfcount[mode] = 1;
        refcount_set(&im->refcnt, 1);
        spin_lock_init(&im->lock);
#ifdef CONFIG_IP_MULTICAST
        timer_setup(&im->timer, igmp_timer_expire, 0);
#endif

        im->next_rcu = in_dev->mc_list;
        in_dev->mc_count++;
        rcu_assign_pointer(in_dev->mc_list, im);

        ip_mc_hash_add(in_dev, im);

#ifdef CONFIG_IP_MULTICAST
        igmpv3_del_delrec(in_dev, im);
#endif
        igmp_group_added(im, mode);
        if (!in_dev->dead)
                ip_rt_multicast_event(in_dev);
out:
        return;
}

void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
{
        __ip_mc_inc_group(in_dev, addr, MCAST_EXCLUDE);
}
EXPORT_SYMBOL(ip_mc_inc_group);

static int ip_mc_check_iphdr(struct sk_buff *skb)
{
        const struct iphdr *iph;
        unsigned int len;
        unsigned int offset = skb_network_offset(skb) + sizeof(*iph);

        if (!pskb_may_pull(skb, offset))
                return -EINVAL;

        iph = ip_hdr(skb);

        if (iph->version != 4 || ip_hdrlen(skb) < sizeof(*iph))
                return -EINVAL;

        offset += ip_hdrlen(skb) - sizeof(*iph);

        if (!pskb_may_pull(skb, offset))
                return -EINVAL;

        iph = ip_hdr(skb);

        if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
                return -EINVAL;

        len = skb_network_offset(skb) + ntohs(iph->tot_len);
        if (skb->len < len || len < offset)
                return -EINVAL;

        skb_set_transport_header(skb, offset);

        return 0;
}

static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
{
        unsigned int len = skb_transport_offset(skb);

        len += sizeof(struct igmpv3_report);

        return pskb_may_pull(skb, len) ? 0 : -EINVAL;
}

static int ip_mc_check_igmp_query(struct sk_buff *skb)
{
        unsigned int len = skb_transport_offset(skb);

        len += sizeof(struct igmphdr);
        if (skb->len < len)
                return -EINVAL;

        /* IGMPv{1,2}? */
        if (skb->len != len) {
                /* or IGMPv3? */
                len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr);
                if (skb->len < len || !pskb_may_pull(skb, len))
                        return -EINVAL;
        }

        /* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer
         * all-systems destination addresses (224.0.0.1) for general queries
         */
        if (!igmp_hdr(skb)->group &&
            ip_hdr(skb)->daddr != htonl(INADDR_ALLHOSTS_GROUP))
                return -EINVAL;

        return 0;
}

static int ip_mc_check_igmp_msg(struct sk_buff *skb)
{
        switch (igmp_hdr(skb)->type) {
        case IGMP_HOST_LEAVE_MESSAGE:
        case IGMP_HOST_MEMBERSHIP_REPORT:
        case IGMPV2_HOST_MEMBERSHIP_REPORT:
                /* fall through */
                return 0;
        case IGMPV3_HOST_MEMBERSHIP_REPORT:
                return ip_mc_check_igmp_reportv3(skb);
        case IGMP_HOST_MEMBERSHIP_QUERY:
                return ip_mc_check_igmp_query(skb);
        default:
                return -ENOMSG;
        }
}

static inline __sum16 ip_mc_validate_checksum(struct sk_buff *skb)
{
        return skb_checksum_simple_validate(skb);
}

static int __ip_mc_check_igmp(struct sk_buff *skb)

{
        struct sk_buff *skb_chk;
        unsigned int transport_len;
        unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr);
        int ret = -EINVAL;

        transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb);

        skb_chk = skb_checksum_trimmed(skb, transport_len,
                                       ip_mc_validate_checksum);
        if (!skb_chk)
                goto err;

        if (!pskb_may_pull(skb_chk, len))
                goto err;

        ret = ip_mc_check_igmp_msg(skb_chk);
        if (ret)
                goto err;

        ret = 0;

err:
        if (skb_chk && skb_chk != skb)
                kfree_skb(skb_chk);

        return ret;
}

/**
 * ip_mc_check_igmp - checks whether this is a sane IGMP packet
 * @skb: the skb to validate
 *
 * Checks whether an IPv4 packet is a valid IGMP packet. If so sets
 * skb transport header accordingly and returns zero.
 *
 * -EINVAL: A broken packet was detected, i.e. it violates some internet
 *  standard
 * -ENOMSG: IP header validation succeeded but it is not an IGMP packet.
 * -ENOMEM: A memory allocation failure happened.
 *
 * Caller needs to set the skb network header and free any returned skb if it
 * differs from the provided skb.
 */
int ip_mc_check_igmp(struct sk_buff *skb)
{
        int ret = ip_mc_check_iphdr(skb);

        if (ret < 0)
                return ret;

        if (ip_hdr(skb)->protocol != IPPROTO_IGMP)
                return -ENOMSG;

        return __ip_mc_check_igmp(skb);
}
EXPORT_SYMBOL(ip_mc_check_igmp);

/*
 *      Resend IGMP JOIN report; used by netdev notifier.
 */
static void ip_mc_rejoin_groups(struct in_device *in_dev)
{
#ifdef CONFIG_IP_MULTICAST
        struct ip_mc_list *im;
        int type;
        struct net *net = dev_net(in_dev->dev);

        ASSERT_RTNL();

        for_each_pmc_rtnl(in_dev, im) {
                if (im->multiaddr == IGMP_ALL_HOSTS)
                        continue;
                if (ipv4_is_local_multicast(im->multiaddr) &&
                    !net->ipv4.sysctl_igmp_llm_reports)
                        continue;

                /* a failover is happening and switches
                 * must be notified immediately
                 */
                if (IGMP_V1_SEEN(in_dev))
                        type = IGMP_HOST_MEMBERSHIP_REPORT;
                else if (IGMP_V2_SEEN(in_dev))
                        type = IGMPV2_HOST_MEMBERSHIP_REPORT;
                else
                        type = IGMPV3_HOST_MEMBERSHIP_REPORT;
                igmp_send_report(in_dev, im, type);
        }
#endif
}

/*
 *      A socket has left a multicast group on device dev
 */

void ip_mc_dec_group(struct in_device *in_dev, __be32 addr)
{
        struct ip_mc_list *i;
        struct ip_mc_list __rcu **ip;

        ASSERT_RTNL();

        for (ip = &in_dev->mc_list;
             (i = rtnl_dereference(*ip)) != NULL;
             ip = &i->next_rcu) {
                if (i->multiaddr == addr) {
                        if (--i->users == 0) {
                                ip_mc_hash_remove(in_dev, i);
                                *ip = i->next_rcu;
                                in_dev->mc_count--;
                                igmp_group_dropped(i);
                                ip_mc_clear_src(i);

                                if (!in_dev->dead)
                                        ip_rt_multicast_event(in_dev);

                                ip_ma_put(i);
                                return;
                        }
                        break;
                }
        }
}
EXPORT_SYMBOL(ip_mc_dec_group);

/* Device changing type */

void ip_mc_unmap(struct in_device *in_dev)
{
        struct ip_mc_list *pmc;

        ASSERT_RTNL();

        for_each_pmc_rtnl(in_dev, pmc)
                igmp_group_dropped(pmc);
}

void ip_mc_remap(struct in_device *in_dev)
{
        struct ip_mc_list *pmc;

        ASSERT_RTNL();

        for_each_pmc_rtnl(in_dev, pmc) {
#ifdef CONFIG_IP_MULTICAST
                igmpv3_del_delrec(in_dev, pmc);
#endif
                igmp_group_added(pmc, pmc->sfmode);
        }
}

/* Device going down */

void ip_mc_down(struct in_device *in_dev)
{
        struct ip_mc_list *pmc;

        ASSERT_RTNL();

        for_each_pmc_rtnl(in_dev, pmc)
                igmp_group_dropped(pmc);

#ifdef CONFIG_IP_MULTICAST
        in_dev->mr_ifc_count = 0;
        if (del_timer(&in_dev->mr_ifc_timer))
                __in_dev_put(in_dev);
        in_dev->mr_gq_running = 0;
        if (del_timer(&in_dev->mr_gq_timer))
                __in_dev_put(in_dev);
#endif

        ip_mc_dec_group(in_dev, IGMP_ALL_HOSTS);
}

#ifdef CONFIG_IP_MULTICAST
static void ip_mc_reset(struct in_device *in_dev)
{
        struct net *net = dev_net(in_dev->dev);

        in_dev->mr_qi = IGMP_QUERY_INTERVAL;
        in_dev->mr_qri = IGMP_QUERY_RESPONSE_INTERVAL;
        in_dev->mr_qrv = net->ipv4.sysctl_igmp_qrv;
}
#else
static void ip_mc_reset(struct in_device *in_dev)
{
}
#endif

void ip_mc_init_dev(struct in_device *in_dev)
{
        ASSERT_RTNL();

#ifdef CONFIG_IP_MULTICAST
        timer_setup(&in_dev->mr_gq_timer, igmp_gq_timer_expire, 0);
        timer_setup(&in_dev->mr_ifc_timer, igmp_ifc_timer_expire, 0);
#endif
        ip_mc_reset(in_dev);

        spin_lock_init(&in_dev->mc_tomb_lock);
}

/* Device going up */

void ip_mc_up(struct in_device *in_dev)
{
        struct ip_mc_list *pmc;

        ASSERT_RTNL();

        ip_mc_reset(in_dev);
        ip_mc_inc_group(in_dev, IGMP_ALL_HOSTS);

        for_each_pmc_rtnl(in_dev, pmc) {
#ifdef CONFIG_IP_MULTICAST
                igmpv3_del_delrec(in_dev, pmc);
#endif
                igmp_group_added(pmc, pmc->sfmode);
        }
}

/*
 *      Device is about to be destroyed: clean up.
 */

void ip_mc_destroy_dev(struct in_device *in_dev)
{
        struct ip_mc_list *i;

        ASSERT_RTNL();

        /* Deactivate timers */
        ip_mc_down(in_dev);
#ifdef CONFIG_IP_MULTICAST
        igmpv3_clear_delrec(in_dev);
#endif

        while ((i = rtnl_dereference(in_dev->mc_list)) != NULL) {
                in_dev->mc_list = i->next_rcu;
                in_dev->mc_count--;
                ip_ma_put(i);
        }
}

/* RTNL is locked */
static struct in_device *ip_mc_find_dev(struct net *net, struct ip_mreqn *imr)
{
        struct net_device *dev = NULL;
        struct in_device *idev = NULL;

        if (imr->imr_ifindex) {
                idev = inetdev_by_index(net, imr->imr_ifindex);
                return idev;
        }
        if (imr->imr_address.s_addr) {
                dev = __ip_dev_find(net, imr->imr_address.s_addr, false);
                if (!dev)
                        return NULL;
        }

        if (!dev) {
                struct rtable *rt = ip_route_output(net,
                                                    imr->imr_multiaddr.s_addr,
                                                    0, 0, 0);
                if (!IS_ERR(rt)) {
                        dev = rt->dst.dev;
                        ip_rt_put(rt);
                }
        }
        if (dev) {
                imr->imr_ifindex = dev->ifindex;
                idev = __in_dev_get_rtnl(dev);
        }
        return idev;
}

/*
 *      Join a socket to a group
 */

static int ip_mc_del1_src(struct ip_mc_list *pmc, int sfmode,
        __be32 *psfsrc)
{
        struct ip_sf_list *psf, *psf_prev;
        int rv = 0;

        psf_prev = NULL;
        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (psf->sf_inaddr == *psfsrc)
                        break;
                psf_prev = psf;
        }
        if (!psf || psf->sf_count[sfmode] == 0) {
                /* source filter not found, or count wrong =>  bug */
                return -ESRCH;
        }
        psf->sf_count[sfmode]--;
        if (psf->sf_count[sfmode] == 0) {
                ip_rt_multicast_event(pmc->interface);
        }
        if (!psf->sf_count[MCAST_INCLUDE] && !psf->sf_count[MCAST_EXCLUDE]) {
#ifdef CONFIG_IP_MULTICAST
                struct in_device *in_dev = pmc->interface;
                struct net *net = dev_net(in_dev->dev);
#endif

                /* no more filters for this source */
                if (psf_prev)
                        psf_prev->sf_next = psf->sf_next;
                else
                        pmc->sources = psf->sf_next;
#ifdef CONFIG_IP_MULTICAST
                if (psf->sf_oldin &&
                    !IGMP_V1_SEEN(in_dev) && !IGMP_V2_SEEN(in_dev)) {
                        psf->sf_crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
                        psf->sf_next = pmc->tomb;
                        pmc->tomb = psf;
                        rv = 1;
                } else
#endif
                        kfree(psf);
        }
        return rv;
}

#ifndef CONFIG_IP_MULTICAST
#define igmp_ifc_event(x)       do { } while (0)
#endif

static int ip_mc_del_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
                         int sfcount, __be32 *psfsrc, int delta)
{
        struct ip_mc_list *pmc;
        int     changerec = 0;
        int     i, err;

        if (!in_dev)
                return -ENODEV;
        rcu_read_lock();
        for_each_pmc_rcu(in_dev, pmc) {
                if (*pmca == pmc->multiaddr)
                        break;
        }
        if (!pmc) {
                /* MCA not found?? bug */
                rcu_read_unlock();
                return -ESRCH;
        }
        spin_lock_bh(&pmc->lock);
        rcu_read_unlock();
#ifdef CONFIG_IP_MULTICAST
        sf_markstate(pmc);
#endif
        if (!delta) {
                err = -EINVAL;
                if (!pmc->sfcount[sfmode])
                        goto out_unlock;
                pmc->sfcount[sfmode]--;
        }
        err = 0;
        for (i = 0; i < sfcount; i++) {
                int rv = ip_mc_del1_src(pmc, sfmode, &psfsrc[i]);

                changerec |= rv > 0;
                if (!err && rv < 0)
                        err = rv;
        }
        if (pmc->sfmode == MCAST_EXCLUDE &&
            pmc->sfcount[MCAST_EXCLUDE] == 0 &&
            pmc->sfcount[MCAST_INCLUDE]) {
#ifdef CONFIG_IP_MULTICAST
                struct ip_sf_list *psf;
                struct net *net = dev_net(in_dev->dev);
#endif

                /* filter mode change */
                pmc->sfmode = MCAST_INCLUDE;
#ifdef CONFIG_IP_MULTICAST
                pmc->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
                in_dev->mr_ifc_count = pmc->crcount;
                for (psf = pmc->sources; psf; psf = psf->sf_next)
                        psf->sf_crcount = 0;
                igmp_ifc_event(pmc->interface);
        } else if (sf_setstate(pmc) || changerec) {
                igmp_ifc_event(pmc->interface);
#endif
        }
out_unlock:
        spin_unlock_bh(&pmc->lock);
        return err;
}

/*
 * Add multicast single-source filter to the interface list
 */
static int ip_mc_add1_src(struct ip_mc_list *pmc, int sfmode,
        __be32 *psfsrc)
{
        struct ip_sf_list *psf, *psf_prev;

        psf_prev = NULL;
        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (psf->sf_inaddr == *psfsrc)
                        break;
                psf_prev = psf;
        }
        if (!psf) {
                psf = kzalloc(sizeof(*psf), GFP_ATOMIC);
                if (!psf)
                        return -ENOBUFS;
                psf->sf_inaddr = *psfsrc;
                if (psf_prev) {
                        psf_prev->sf_next = psf;
                } else
                        pmc->sources = psf;
        }
        psf->sf_count[sfmode]++;
        if (psf->sf_count[sfmode] == 1) {
                ip_rt_multicast_event(pmc->interface);
        }
        return 0;
}

#ifdef CONFIG_IP_MULTICAST
static void sf_markstate(struct ip_mc_list *pmc)
{
        struct ip_sf_list *psf;
        int mca_xcount = pmc->sfcount[MCAST_EXCLUDE];

        for (psf = pmc->sources; psf; psf = psf->sf_next)
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        psf->sf_oldin = mca_xcount ==
                                psf->sf_count[MCAST_EXCLUDE] &&
                                !psf->sf_count[MCAST_INCLUDE];
                } else
                        psf->sf_oldin = psf->sf_count[MCAST_INCLUDE] != 0;

}

static int sf_setstate(struct ip_mc_list *pmc)
{
        struct ip_sf_list *psf, *dpsf;
        int mca_xcount = pmc->sfcount[MCAST_EXCLUDE];
        int qrv = pmc->interface->mr_qrv;
        int new_in, rv;

        rv = 0;
        for (psf = pmc->sources; psf; psf = psf->sf_next) {
                if (pmc->sfcount[MCAST_EXCLUDE]) {
                        new_in = mca_xcount == psf->sf_count[MCAST_EXCLUDE] &&
                                !psf->sf_count[MCAST_INCLUDE];
                } else
                        new_in = psf->sf_count[MCAST_INCLUDE] != 0;
                if (new_in) {
                        if (!psf->sf_oldin) {
                                struct ip_sf_list *prev = NULL;

                                for (dpsf = pmc->tomb; dpsf; dpsf = dpsf->sf_next) {
                                        if (dpsf->sf_inaddr == psf->sf_inaddr)
                                                break;
                                        prev = dpsf;
                                }
                                if (dpsf) {
                                        if (prev)
                                                prev->sf_next = dpsf->sf_next;
                                        else
                                                pmc->tomb = dpsf->sf_next;
                                        kfree(dpsf);
                                }
                                psf->sf_crcount = qrv;
                                rv++;
                        }
                } else if (psf->sf_oldin) {

                        psf->sf_crcount = 0;
                        /*
                         * add or update "delete" records if an active filter
                         * is now inactive
                         */
                        for (dpsf = pmc->tomb; dpsf; dpsf = dpsf->sf_next)
                                if (dpsf->sf_inaddr == psf->sf_inaddr)
                                        break;
                        if (!dpsf) {
                                dpsf = kmalloc(sizeof(*dpsf), GFP_ATOMIC);
                                if (!dpsf)
                                        continue;
                                *dpsf = *psf;
                                /* pmc->lock held by callers */
                                dpsf->sf_next = pmc->tomb;
                                pmc->tomb = dpsf;
                        }
                        dpsf->sf_crcount = qrv;
                        rv++;
                }
        }
        return rv;
}
#endif

/*
 * Add multicast source filter list to the interface list
 */
static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
                         int sfcount, __be32 *psfsrc, int delta)
{
        struct ip_mc_list *pmc;
        int     isexclude;
        int     i, err;

        if (!in_dev)
                return -ENODEV;
        rcu_read_lock();
        for_each_pmc_rcu(in_dev, pmc) {
                if (*pmca == pmc->multiaddr)
                        break;
        }
        if (!pmc) {
                /* MCA not found?? bug */
                rcu_read_unlock();
                return -ESRCH;
        }
        spin_lock_bh(&pmc->lock);
        rcu_read_unlock();

#ifdef CONFIG_IP_MULTICAST
        sf_markstate(pmc);
#endif
        isexclude = pmc->sfmode == MCAST_EXCLUDE;
        if (!delta)
                pmc->sfcount[sfmode]++;
        err = 0;
        for (i = 0; i < sfcount; i++) {
                err = ip_mc_add1_src(pmc, sfmode, &psfsrc[i]);
                if (err)
                        break;
        }
        if (err) {
                int j;

                if (!delta)
                        pmc->sfcount[sfmode]--;
                for (j = 0; j < i; j++)
                        (void) ip_mc_del1_src(pmc, sfmode, &psfsrc[j]);
        } else if (isexclude != (pmc->sfcount[MCAST_EXCLUDE] != 0)) {
#ifdef CONFIG_IP_MULTICAST
                struct ip_sf_list *psf;
                struct net *net = dev_net(pmc->interface->dev);
                in_dev = pmc->interface;
#endif

                /* filter mode change */
                if (pmc->sfcount[MCAST_EXCLUDE])
                        pmc->sfmode = MCAST_EXCLUDE;
                else if (pmc->sfcount[MCAST_INCLUDE])
                        pmc->sfmode = MCAST_INCLUDE;
#ifdef CONFIG_IP_MULTICAST
                /* else no filters; keep old mode for reports */

                pmc->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
                in_dev->mr_ifc_count = pmc->crcount;
                for (psf = pmc->sources; psf; psf = psf->sf_next)
                        psf->sf_crcount = 0;
                igmp_ifc_event(in_dev);
        } else if (sf_setstate(pmc)) {
                igmp_ifc_event(in_dev);
#endif
        }
        spin_unlock_bh(&pmc->lock);
        return err;
}

static void ip_mc_clear_src(struct ip_mc_list *pmc)
{
        struct ip_sf_list *tomb, *sources;

        spin_lock_bh(&pmc->lock);
        tomb = pmc->tomb;
        pmc->tomb = NULL;
        sources = pmc->sources;
        pmc->sources = NULL;
        pmc->sfmode = MCAST_EXCLUDE;
        pmc->sfcount[MCAST_INCLUDE] = 0;
        pmc->sfcount[MCAST_EXCLUDE] = 1;
        spin_unlock_bh(&pmc->lock);

        ip_sf_list_clear_all(tomb);
        ip_sf_list_clear_all(sources);
}

/* Join a multicast group
 */
static int __ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr,
                              unsigned int mode)
{
        __be32 addr = imr->imr_multiaddr.s_addr;
        struct ip_mc_socklist *iml, *i;
        struct in_device *in_dev;
        struct inet_sock *inet = inet_sk(sk);
        struct net *net = sock_net(sk);
        int ifindex;
        int count = 0;
        int err;

        ASSERT_RTNL();

        if (!ipv4_is_multicast(addr))
                return -EINVAL;

        in_dev = ip_mc_find_dev(net, imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }

        err = -EADDRINUSE;
        ifindex = imr->imr_ifindex;
        for_each_pmc_rtnl(inet, i) {
                if (i->multi.imr_multiaddr.s_addr == addr &&
                    i->multi.imr_ifindex == ifindex)
                        goto done;
                count++;
        }
        err = -ENOBUFS;
        if (count >= net->ipv4.sysctl_igmp_max_memberships)
                goto done;
        iml = sock_kmalloc(sk, sizeof(*iml), GFP_KERNEL);
        if (!iml)
                goto done;

        memcpy(&iml->multi, imr, sizeof(*imr));
        iml->next_rcu = inet->mc_list;
        iml->sflist = NULL;
        iml->sfmode = mode;
        rcu_assign_pointer(inet->mc_list, iml);
        __ip_mc_inc_group(in_dev, addr, mode);
        err = 0;
done:
        return err;
}

/* Join ASM (Any-Source Multicast) group
 */
int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr)
{
        return __ip_mc_join_group(sk, imr, MCAST_EXCLUDE);
}
EXPORT_SYMBOL(ip_mc_join_group);

/* Join SSM (Source-Specific Multicast) group
 */
int ip_mc_join_group_ssm(struct sock *sk, struct ip_mreqn *imr,
                         unsigned int mode)
{
        return __ip_mc_join_group(sk, imr, mode);
}

static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml,
                           struct in_device *in_dev)
{
        struct ip_sf_socklist *psf = rtnl_dereference(iml->sflist);
        int err;

        if (!psf) {
                /* any-source empty exclude case */
                return ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
                        iml->sfmode, 0, NULL, 0);
        }
        err = ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
                        iml->sfmode, psf->sl_count, psf->sl_addr, 0);
        RCU_INIT_POINTER(iml->sflist, NULL);
        /* decrease mem now to avoid the memleak warning */
        atomic_sub(IP_SFLSIZE(psf->sl_max), &sk->sk_omem_alloc);
        kfree_rcu(psf, rcu);
        return err;
}

int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ip_mc_socklist *iml;
        struct ip_mc_socklist __rcu **imlp;
        struct in_device *in_dev;
        struct net *net = sock_net(sk);
        __be32 group = imr->imr_multiaddr.s_addr;
        u32 ifindex;
        int ret = -EADDRNOTAVAIL;

        ASSERT_RTNL();

        in_dev = ip_mc_find_dev(net, imr);
        if (!imr->imr_ifindex && !imr->imr_address.s_addr && !in_dev) {
                ret = -ENODEV;
                goto out;
        }
        ifindex = imr->imr_ifindex;
        for (imlp = &inet->mc_list;
             (iml = rtnl_dereference(*imlp)) != NULL;
             imlp = &iml->next_rcu) {
                if (iml->multi.imr_multiaddr.s_addr != group)
                        continue;
                if (ifindex) {
                        if (iml->multi.imr_ifindex != ifindex)
                                continue;
                } else if (imr->imr_address.s_addr && imr->imr_address.s_addr !=
                                iml->multi.imr_address.s_addr)
                        continue;

                (void) ip_mc_leave_src(sk, iml, in_dev);

                *imlp = iml->next_rcu;

                if (in_dev)
                        ip_mc_dec_group(in_dev, group);

                /* decrease mem now to avoid the memleak warning */
                atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
                kfree_rcu(iml, rcu);
                return 0;
        }
out:
        return ret;
}
EXPORT_SYMBOL(ip_mc_leave_group);

int ip_mc_source(int add, int omode, struct sock *sk, struct
        ip_mreq_source *mreqs, int ifindex)
{
        int err;
        struct ip_mreqn imr;
        __be32 addr = mreqs->imr_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev = NULL;
        struct inet_sock *inet = inet_sk(sk);
        struct ip_sf_socklist *psl;
        struct net *net = sock_net(sk);
        int leavegroup = 0;
        int i, j, rv;

        if (!ipv4_is_multicast(addr))
                return -EINVAL;

        ASSERT_RTNL();

        imr.imr_multiaddr.s_addr = mreqs->imr_multiaddr;
        imr.imr_address.s_addr = mreqs->imr_interface;
        imr.imr_ifindex = ifindex;
        in_dev = ip_mc_find_dev(net, &imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }
        err = -EADDRNOTAVAIL;

        for_each_pmc_rtnl(inet, pmc) {
                if ((pmc->multi.imr_multiaddr.s_addr ==
                     imr.imr_multiaddr.s_addr) &&
                    (pmc->multi.imr_ifindex == imr.imr_ifindex))
                        break;
        }
        if (!pmc) {             /* must have a prior join */
                err = -EINVAL;
                goto done;
        }
        /* if a source filter was set, must be the same mode as before */
        if (pmc->sflist) {
                if (pmc->sfmode != omode) {
                        err = -EINVAL;
                        goto done;
                }
        } else if (pmc->sfmode != omode) {
                /* allow mode switches for empty-set filters */
                ip_mc_add_src(in_dev, &mreqs->imr_multiaddr, omode, 0, NULL, 0);
                ip_mc_del_src(in_dev, &mreqs->imr_multiaddr, pmc->sfmode, 0,
                        NULL, 0);
                pmc->sfmode = omode;
        }

        psl = rtnl_dereference(pmc->sflist);
        if (!add) {
                if (!psl)
                        goto done;      /* err = -EADDRNOTAVAIL */
                rv = !0;
                for (i = 0; i < psl->sl_count; i++) {
                        rv = memcmp(&psl->sl_addr[i], &mreqs->imr_sourceaddr,
                                sizeof(__be32));
                        if (rv == 0)
                                break;
                }
                if (rv)         /* source not found */
                        goto done;      /* err = -EADDRNOTAVAIL */

                /* special case - (INCLUDE, empty) == LEAVE_GROUP */
                if (psl->sl_count == 1 && omode == MCAST_INCLUDE) {
                        leavegroup = 1;
                        goto done;
                }

                /* update the interface filter */
                ip_mc_del_src(in_dev, &mreqs->imr_multiaddr, omode, 1,
                        &mreqs->imr_sourceaddr, 1);

                for (j = i+1; j < psl->sl_count; j++)
                        psl->sl_addr[j-1] = psl->sl_addr[j];
                psl->sl_count--;
                err = 0;
                goto done;
        }
        /* else, add a new source to the filter */

        if (psl && psl->sl_count >= net->ipv4.sysctl_igmp_max_msf) {
                err = -ENOBUFS;
                goto done;
        }
        if (!psl || psl->sl_count == psl->sl_max) {
                struct ip_sf_socklist *newpsl;
                int count = IP_SFBLOCK;

                if (psl)
                        count += psl->sl_max;
                newpsl = sock_kmalloc(sk, IP_SFLSIZE(count), GFP_KERNEL);
                if (!newpsl) {
                        err = -ENOBUFS;
                        goto done;
                }
                newpsl->sl_max = count;
                newpsl->sl_count = count - IP_SFBLOCK;
                if (psl) {
                        for (i = 0; i < psl->sl_count; i++)
                                newpsl->sl_addr[i] = psl->sl_addr[i];
                        /* decrease mem now to avoid the memleak warning */
                        atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc);
                        kfree_rcu(psl, rcu);
                }
                rcu_assign_pointer(pmc->sflist, newpsl);
                psl = newpsl;
        }
        rv = 1; /* > 0 for insert logic below if sl_count is 0 */
        for (i = 0; i < psl->sl_count; i++) {
                rv = memcmp(&psl->sl_addr[i], &mreqs->imr_sourceaddr,
                        sizeof(__be32));
                if (rv == 0)
                        break;
        }
        if (rv == 0)            /* address already there is an error */
                goto done;
        for (j = psl->sl_count-1; j >= i; j--)
                psl->sl_addr[j+1] = psl->sl_addr[j];
        psl->sl_addr[i] = mreqs->imr_sourceaddr;
        psl->sl_count++;
        err = 0;
        /* update the interface list */
        ip_mc_add_src(in_dev, &mreqs->imr_multiaddr, omode, 1,
                &mreqs->imr_sourceaddr, 1);
done:
        if (leavegroup)
                err = ip_mc_leave_group(sk, &imr);
        return err;
}

int ip_mc_msfilter(struct sock *sk, struct ip_msfilter *msf, int ifindex)
{
        int err = 0;
        struct ip_mreqn imr;
        __be32 addr = msf->imsf_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev;
        struct inet_sock *inet = inet_sk(sk);
        struct ip_sf_socklist *newpsl, *psl;
        struct net *net = sock_net(sk);
        int leavegroup = 0;

        if (!ipv4_is_multicast(addr))
                return -EINVAL;
        if (msf->imsf_fmode != MCAST_INCLUDE &&
            msf->imsf_fmode != MCAST_EXCLUDE)
                return -EINVAL;

        ASSERT_RTNL();

        imr.imr_multiaddr.s_addr = msf->imsf_multiaddr;
        imr.imr_address.s_addr = msf->imsf_interface;
        imr.imr_ifindex = ifindex;
        in_dev = ip_mc_find_dev(net, &imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }

        /* special case - (INCLUDE, empty) == LEAVE_GROUP */
        if (msf->imsf_fmode == MCAST_INCLUDE && msf->imsf_numsrc == 0) {
                leavegroup = 1;
                goto done;
        }

        for_each_pmc_rtnl(inet, pmc) {
                if (pmc->multi.imr_multiaddr.s_addr == msf->imsf_multiaddr &&
                    pmc->multi.imr_ifindex == imr.imr_ifindex)
                        break;
        }
        if (!pmc) {             /* must have a prior join */
                err = -EINVAL;
                goto done;
        }
        if (msf->imsf_numsrc) {
                newpsl = sock_kmalloc(sk, IP_SFLSIZE(msf->imsf_numsrc),
                                                           GFP_KERNEL);
                if (!newpsl) {
                        err = -ENOBUFS;
                        goto done;
                }
                newpsl->sl_max = newpsl->sl_count = msf->imsf_numsrc;
                memcpy(newpsl->sl_addr, msf->imsf_slist,
                        msf->imsf_numsrc * sizeof(msf->imsf_slist[0]));
                err = ip_mc_add_src(in_dev, &msf->imsf_multiaddr,
                        msf->imsf_fmode, newpsl->sl_count, newpsl->sl_addr, 0);
                if (err) {
                        sock_kfree_s(sk, newpsl, IP_SFLSIZE(newpsl->sl_max));
                        goto done;
                }
        } else {
                newpsl = NULL;
                (void) ip_mc_add_src(in_dev, &msf->imsf_multiaddr,
                                     msf->imsf_fmode, 0, NULL, 0);
        }
        psl = rtnl_dereference(pmc->sflist);
        if (psl) {
                (void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
                        psl->sl_count, psl->sl_addr, 0);
                /* decrease mem now to avoid the memleak warning */
                atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc);
                kfree_rcu(psl, rcu);
        } else
                (void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
                        0, NULL, 0);
        rcu_assign_pointer(pmc->sflist, newpsl);
        pmc->sfmode = msf->imsf_fmode;
        err = 0;
done:
        if (leavegroup)
                err = ip_mc_leave_group(sk, &imr);
        return err;
}

int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
        struct ip_msfilter __user *optval, int __user *optlen)
{
        int err, len, count, copycount;
        struct ip_mreqn imr;
        __be32 addr = msf->imsf_multiaddr;
        struct ip_mc_socklist *pmc;
        struct in_device *in_dev;
        struct inet_sock *inet = inet_sk(sk);
        struct ip_sf_socklist *psl;
        struct net *net = sock_net(sk);

        ASSERT_RTNL();

        if (!ipv4_is_multicast(addr))
                return -EINVAL;

        imr.imr_multiaddr.s_addr = msf->imsf_multiaddr;
        imr.imr_address.s_addr = msf->imsf_interface;
        imr.imr_ifindex = 0;
        in_dev = ip_mc_find_dev(net, &imr);

        if (!in_dev) {
                err = -ENODEV;
                goto done;
        }
        err = -EADDRNOTAVAIL;

        for_each_pmc_rtnl(inet, pmc) {
                if (pmc->multi.imr_multiaddr.s_addr == msf->imsf_multiaddr &&
                    pmc->multi.imr_ifindex == imr.imr_ifindex)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        msf->imsf_fmode = pmc->sfmode;
        psl = rtnl_dereference(pmc->sflist);
        if (!psl) {
                len = 0;
                count = 0;
        } else {
                count = psl->sl_count;
        }
        copycount = count < msf->imsf_numsrc ? count : msf->imsf_numsrc;
        len = copycount * sizeof(psl->sl_addr[0]);
        msf->imsf_numsrc = count;
        if (put_user(IP_MSFILTER_SIZE(copycount), optlen) ||
            copy_to_user(optval, msf, IP_MSFILTER_SIZE(0))) {
                return -EFAULT;
        }
        if (len &&
            copy_to_user(&optval->imsf_slist[0], psl->sl_addr, len))
                return -EFAULT;
        return 0;
done:
        return err;
}

int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
        struct group_filter __user *optval, int __user *optlen)
{
        int err, i, count, copycount;
        struct sockaddr_in *psin;
        __be32 addr;
        struct ip_mc_socklist *pmc;
        struct inet_sock *inet = inet_sk(sk);
        struct ip_sf_socklist *psl;

        ASSERT_RTNL();

        psin = (struct sockaddr_in *)&gsf->gf_group;
        if (psin->sin_family != AF_INET)
                return -EINVAL;
        addr = psin->sin_addr.s_addr;
        if (!ipv4_is_multicast(addr))
                return -EINVAL;

        err = -EADDRNOTAVAIL;

        for_each_pmc_rtnl(inet, pmc) {
                if (pmc->multi.imr_multiaddr.s_addr == addr &&
                    pmc->multi.imr_ifindex == gsf->gf_interface)
                        break;
        }
        if (!pmc)               /* must have a prior join */
                goto done;
        gsf->gf_fmode = pmc->sfmode;
        psl = rtnl_dereference(pmc->sflist);
        count = psl ? psl->sl_count : 0;
        copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
        gsf->gf_numsrc = count;
        if (put_user(GROUP_FILTER_SIZE(copycount), optlen) ||
            copy_to_user(optval, gsf, GROUP_FILTER_SIZE(0))) {
                return -EFAULT;
        }
        for (i = 0; i < copycount; i++) {
                struct sockaddr_storage ss;

                psin = (struct sockaddr_in *)&ss;
                memset(&ss, 0, sizeof(ss));
                psin->sin_family = AF_INET;
                psin->sin_addr.s_addr = psl->sl_addr[i];
                if (copy_to_user(&optval->gf_slist[i], &ss, sizeof(ss)))
                        return -EFAULT;
        }
        return 0;
done:
        return err;
}

/*
 * check if a multicast source filter allows delivery for a given <src,dst,intf>
 */
int ip_mc_sf_allow(struct sock *sk, __be32 loc_addr, __be32 rmt_addr,
                   int dif, int sdif)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ip_mc_socklist *pmc;
        struct ip_sf_socklist *psl;
        int i;
        int ret;

        ret = 1;
        if (!ipv4_is_multicast(loc_addr))
                goto out;

        rcu_read_lock();
        for_each_pmc_rcu(inet, pmc) {
                if (pmc->multi.imr_multiaddr.s_addr == loc_addr &&
                    (pmc->multi.imr_ifindex == dif ||
                     (sdif && pmc->multi.imr_ifindex == sdif)))
                        break;
        }
        ret = inet->mc_all;
        if (!pmc)
                goto unlock;
        psl = rcu_dereference(pmc->sflist);
        ret = (pmc->sfmode == MCAST_EXCLUDE);
        if (!psl)
                goto unlock;

        for (i = 0; i < psl->sl_count; i++) {
                if (psl->sl_addr[i] == rmt_addr)
                        break;
        }
        ret = 0;
        if (pmc->sfmode == MCAST_INCLUDE && i >= psl->sl_count)
                goto unlock;
        if (pmc->sfmode == MCAST_EXCLUDE && i < psl->sl_count)
                goto unlock;
        ret = 1;
unlock:
        rcu_read_unlock();
out:
        return ret;
}

/*
 *      A socket is closing.
 */

void ip_mc_drop_socket(struct sock *sk)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ip_mc_socklist *iml;
        struct net *net = sock_net(sk);

        if (!inet->mc_list)
                return;

        rtnl_lock();
        while ((iml = rtnl_dereference(inet->mc_list)) != NULL) {
                struct in_device *in_dev;

                inet->mc_list = iml->next_rcu;
                in_dev = inetdev_by_index(net, iml->multi.imr_ifindex);
                (void) ip_mc_leave_src(sk, iml, in_dev);
                if (in_dev)
                        ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr);
                /* decrease mem now to avoid the memleak warning */
                atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
                kfree_rcu(iml, rcu);
        }
        rtnl_unlock();
}

/* called with rcu_read_lock() */
int ip_check_mc_rcu(struct in_device *in_dev, __be32 mc_addr, __be32 src_addr, u8 proto)
{
        struct ip_mc_list *im;
        struct ip_mc_list __rcu **mc_hash;
        struct ip_sf_list *psf;
        int rv = 0;

        mc_hash = rcu_dereference(in_dev->mc_hash);
        if (mc_hash) {
                u32 hash = hash_32((__force u32)mc_addr, MC_HASH_SZ_LOG);

                for (im = rcu_dereference(mc_hash[hash]);
                     im != NULL;
                     im = rcu_dereference(im->next_hash)) {
                        if (im->multiaddr == mc_addr)
                                break;
                }
        } else {
                for_each_pmc_rcu(in_dev, im) {
                        if (im->multiaddr == mc_addr)
                                break;
                }
        }
        if (im && proto == IPPROTO_IGMP) {
                rv = 1;
        } else if (im) {
                if (src_addr) {
                        for (psf = im->sources; psf; psf = psf->sf_next) {
                                if (psf->sf_inaddr == src_addr)
                                        break;
                        }
                        if (psf)
                                rv = psf->sf_count[MCAST_INCLUDE] ||
                                        psf->sf_count[MCAST_EXCLUDE] !=
                                        im->sfcount[MCAST_EXCLUDE];
                        else
                                rv = im->sfcount[MCAST_EXCLUDE] != 0;
                } else
                        rv = 1; /* unspecified source; tentatively allow */
        }
        return rv;
}

#if defined(CONFIG_PROC_FS)
struct igmp_mc_iter_state {
        struct seq_net_private p;
        struct net_device *dev;
        struct in_device *in_dev;
};

#define igmp_mc_seq_private(seq)        ((struct igmp_mc_iter_state *)(seq)->private)

static inline struct ip_mc_list *igmp_mc_get_first(struct seq_file *seq)
{
        struct net *net = seq_file_net(seq);
        struct ip_mc_list *im = NULL;
        struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);

        state->in_dev = NULL;
        for_each_netdev_rcu(net, state->dev) {
                struct in_device *in_dev;

                in_dev = __in_dev_get_rcu(state->dev);
                if (!in_dev)
                        continue;
                im = rcu_dereference(in_dev->mc_list);
                if (im) {
                        state->in_dev = in_dev;
                        break;
                }
        }
        return im;
}

static struct ip_mc_list *igmp_mc_get_next(struct seq_file *seq, struct ip_mc_list *im)
{
        struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);

        im = rcu_dereference(im->next_rcu);
        while (!im) {
                state->dev = next_net_device_rcu(state->dev);
                if (!state->dev) {
                        state->in_dev = NULL;
                        break;
                }
                state->in_dev = __in_dev_get_rcu(state->dev);
                if (!state->in_dev)
                        continue;
                im = rcu_dereference(state->in_dev->mc_list);
        }
        return im;
}

static struct ip_mc_list *igmp_mc_get_idx(struct seq_file *seq, loff_t pos)
{
        struct ip_mc_list *im = igmp_mc_get_first(seq);
        if (im)
                while (pos && (im = igmp_mc_get_next(seq, im)) != NULL)
                        --pos;
        return pos ? NULL : im;
}

static void *igmp_mc_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(rcu)
{
        rcu_read_lock();
        return *pos ? igmp_mc_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *igmp_mc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct ip_mc_list *im;
        if (v == SEQ_START_TOKEN)
                im = igmp_mc_get_first(seq);
        else
                im = igmp_mc_get_next(seq, v);
        ++*pos;
        return im;
}

static void igmp_mc_seq_stop(struct seq_file *seq, void *v)
        __releases(rcu)
{
        struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);

        state->in_dev = NULL;
        state->dev = NULL;
        rcu_read_unlock();
}

static int igmp_mc_seq_show(struct seq_file *seq, void *v)
{
        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                         "Idx\tDevice    : Count Querier\tGroup    Users Timer\tReporter\n");
        else {
                struct ip_mc_list *im = (struct ip_mc_list *)v;
                struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);
                char   *querier;
                long delta;

#ifdef CONFIG_IP_MULTICAST
                querier = IGMP_V1_SEEN(state->in_dev) ? "V1" :
                          IGMP_V2_SEEN(state->in_dev) ? "V2" :
                          "V3";
#else
                querier = "NONE";
#endif

                if (rcu_access_pointer(state->in_dev->mc_list) == im) {
                        seq_printf(seq, "%d\t%-10s: %5d %7s\n",
                                   state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
                }

                delta = im->timer.expires - jiffies;
                seq_printf(seq,
                           "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",
                           im->multiaddr, im->users,
                           im->tm_running,
                           im->tm_running ? jiffies_delta_to_clock_t(delta) : 0,
                           im->reporter);
        }
        return 0;
}

static const struct seq_operations igmp_mc_seq_ops = {
        .start  =       igmp_mc_seq_start,
        .next   =       igmp_mc_seq_next,
        .stop   =       igmp_mc_seq_stop,
        .show   =       igmp_mc_seq_show,
};

struct igmp_mcf_iter_state {
        struct seq_net_private p;
        struct net_device *dev;
        struct in_device *idev;
        struct ip_mc_list *im;
};

#define igmp_mcf_seq_private(seq)       ((struct igmp_mcf_iter_state *)(seq)->private)

static inline struct ip_sf_list *igmp_mcf_get_first(struct seq_file *seq)
{
        struct net *net = seq_file_net(seq);
        struct ip_sf_list *psf = NULL;
        struct ip_mc_list *im = NULL;
        struct igmp_mcf_iter_state *state = igmp_mcf_seq_private(seq);

        state->idev = NULL;
        state->im = NULL;
        for_each_netdev_rcu(net, state->dev) {
                struct in_device *idev;
                idev = __in_dev_get_rcu(state->dev);
                if (unlikely(!idev))
                        continue;
                im = rcu_dereference(idev->mc_list);
                if (likely(im)) {
                        spin_lock_bh(&im->lock);
                        psf = im->sources;
                        if (likely(psf)) {
                                state->im = im;
                                state->idev = idev;
                                break;
                        }
                        spin_unlock_bh(&im->lock);
                }
        }
        return psf;
}

static struct ip_sf_list *igmp_mcf_get_next(struct seq_file *seq, struct ip_sf_list *psf)
{
        struct igmp_mcf_iter_state *state = igmp_mcf_seq_private(seq);

        psf = psf->sf_next;
        while (!psf) {
                spin_unlock_bh(&state->im->lock);
                state->im = state->im->next;
                while (!state->im) {
                        state->dev = next_net_device_rcu(state->dev);
                        if (!state->dev) {
                                state->idev = NULL;
                                goto out;
                        }
                        state->idev = __in_dev_get_rcu(state->dev);
                        if (!state->idev)
                                continue;
                        state->im = rcu_dereference(state->idev->mc_list);
                }
                if (!state->im)
                        break;
                spin_lock_bh(&state->im->lock);
                psf = state->im->sources;
        }
out:
        return psf;
}

static struct ip_sf_list *igmp_mcf_get_idx(struct seq_file *seq, loff_t pos)
{
        struct ip_sf_list *psf = igmp_mcf_get_first(seq);
        if (psf)
                while (pos && (psf = igmp_mcf_get_next(seq, psf)) != NULL)
                        --pos;
        return pos ? NULL : psf;
}

static void *igmp_mcf_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(rcu)
{
        rcu_read_lock();
        return *pos ? igmp_mcf_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *igmp_mcf_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct ip_sf_list *psf;
        if (v == SEQ_START_TOKEN)
                psf = igmp_mcf_get_first(seq);
        else
                psf = igmp_mcf_get_next(seq, v);
        ++*pos;
        return psf;
}

static void igmp_mcf_seq_stop(struct seq_file *seq, void *v)
        __releases(rcu)
{
        struct igmp_mcf_iter_state *state = igmp_mcf_seq_private(seq);
        if (likely(state->im)) {
                spin_unlock_bh(&state->im->lock);
                state->im = NULL;
        }
        state->idev = NULL;
        state->dev = NULL;
        rcu_read_unlock();
}

static int igmp_mcf_seq_show(struct seq_file *seq, void *v)
{
        struct ip_sf_list *psf = (struct ip_sf_list *)v;
        struct igmp_mcf_iter_state *state = igmp_mcf_seq_private(seq);

        if (v == SEQ_START_TOKEN) {
                seq_puts(seq, "Idx Device        MCA        SRC    INC    EXC\n");
        } else {
                seq_printf(seq,
                           "%3d %6.6s 0x%08x "
                           "0x%08x %6lu %6lu\n",
                           state->dev->ifindex, state->dev->name,
                           ntohl(state->im->multiaddr),
                           ntohl(psf->sf_inaddr),
                           psf->sf_count[MCAST_INCLUDE],
                           psf->sf_count[MCAST_EXCLUDE]);
        }
        return 0;
}

static const struct seq_operations igmp_mcf_seq_ops = {
        .start  =       igmp_mcf_seq_start,
        .next   =       igmp_mcf_seq_next,
        .stop   =       igmp_mcf_seq_stop,
        .show   =       igmp_mcf_seq_show,
};