/*
 *      IPv6 Address [auto]configuration
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

/*
 *      Changes:
 *
 *      Janos Farkas                    :       delete timer on ifdown
 *      <chexum@bankinf.banki.hu>
 *      Andi Kleen                      :       kill double kfree on module
 *                                              unload.
 *      Maciej W. Rozycki               :       FDDI support
 *      sekiya@USAGI                    :       Don't send too many RS
 *                                              packets.
 *      yoshfuji@USAGI                  :       Fixed interval between DAD
 *                                              packets.
 *      YOSHIFUJI Hideaki @USAGI        :       improved accuracy of
 *                                              address validation timer.
 *      YOSHIFUJI Hideaki @USAGI        :       Privacy Extensions (RFC3041)
 *                                              support.
 *      Yuji SEKIYA @USAGI              :       Don't assign a same IPv6
 *                                              address on a same interface.
 *      YOSHIFUJI Hideaki @USAGI        :       ARCnet support
 *      YOSHIFUJI Hideaki @USAGI        :       convert /proc/net/if_inet6 to
 *                                              seq_file.
 *      YOSHIFUJI Hideaki @USAGI        :       improved source address
 *                                              selection; consider scope,
 *                                              status etc.
 */

#define pr_fmt(fmt) "IPv6: " fmt

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/inet.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_addr.h>
#include <linux/if_arp.h>
#include <linux/if_arcnet.h>
#include <linux/if_infiniband.h>
#include <linux/route.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/slab.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#include <linux/capability.h>
#include <linux/delay.h>
#include <linux/notifier.h>
#include <linux/string.h>
#include <linux/hash.h>

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

#include <net/6lowpan.h>
#include <net/firewire.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/tcp.h>
#include <net/ip.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/l3mdev.h>
#include <linux/if_tunnel.h>
#include <linux/rtnetlink.h>
#include <linux/netconf.h>
#include <linux/random.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>

#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/export.h>

/* Set to 3 to get tracing... */
#define ACONF_DEBUG 2

#if ACONF_DEBUG >= 3
#define ADBG(fmt, ...) printk(fmt, ##__VA_ARGS__)
#else
#define ADBG(fmt, ...) do { if (0) printk(fmt, ##__VA_ARGS__); } while (0)
#endif

#define INFINITY_LIFE_TIME      0xFFFFFFFF

#define IPV6_MAX_STRLEN \
        sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")

static inline u32 cstamp_delta(unsigned long cstamp)
{
        return (cstamp - INITIAL_JIFFIES) * 100UL / HZ;
}

static inline s32 rfc3315_s14_backoff_init(s32 irt)
{
        /* multiply 'initial retransmission time' by 0.9 .. 1.1 */
        u64 tmp = (900000 + prandom_u32() % 200001) * (u64)irt;
        do_div(tmp, 1000000);
        return (s32)tmp;
}

static inline s32 rfc3315_s14_backoff_update(s32 rt, s32 mrt)
{
        /* multiply 'retransmission timeout' by 1.9 .. 2.1 */
        u64 tmp = (1900000 + prandom_u32() % 200001) * (u64)rt;
        do_div(tmp, 1000000);
        if ((s32)tmp > mrt) {
                /* multiply 'maximum retransmission time' by 0.9 .. 1.1 */
                tmp = (900000 + prandom_u32() % 200001) * (u64)mrt;
                do_div(tmp, 1000000);
        }
        return (s32)tmp;
}

#ifdef CONFIG_SYSCTL
static int addrconf_sysctl_register(struct inet6_dev *idev);
static void addrconf_sysctl_unregister(struct inet6_dev *idev);
#else
static inline int addrconf_sysctl_register(struct inet6_dev *idev)
{
        return 0;
}

static inline void addrconf_sysctl_unregister(struct inet6_dev *idev)
{
}
#endif

static void ipv6_regen_rndid(struct inet6_dev *idev);
static void ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpaddr);

static int ipv6_generate_eui64(u8 *eui, struct net_device *dev);
static int ipv6_count_addresses(struct inet6_dev *idev);
static int ipv6_generate_stable_address(struct in6_addr *addr,
                                        u8 dad_count,
                                        const struct inet6_dev *idev);

/*
 *      Configured unicast address hash table
 */
static struct hlist_head inet6_addr_lst[IN6_ADDR_HSIZE];
static DEFINE_SPINLOCK(addrconf_hash_lock);

static void addrconf_verify(void);
static void addrconf_verify_rtnl(void);
static void addrconf_verify_work(struct work_struct *);

static struct workqueue_struct *addrconf_wq;
static DECLARE_DELAYED_WORK(addr_chk_work, addrconf_verify_work);

static void addrconf_join_anycast(struct inet6_ifaddr *ifp);
static void addrconf_leave_anycast(struct inet6_ifaddr *ifp);

static void addrconf_type_change(struct net_device *dev,
                                 unsigned long event);
static int addrconf_ifdown(struct net_device *dev, int how);

static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
                                                  int plen,
                                                  const struct net_device *dev,
                                                  u32 flags, u32 noflags);

static void addrconf_dad_start(struct inet6_ifaddr *ifp);
static void addrconf_dad_work(struct work_struct *w);
static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id);
static void addrconf_dad_run(struct inet6_dev *idev);
static void addrconf_rs_timer(unsigned long data);
static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifa);
static void ipv6_ifa_notify(int event, struct inet6_ifaddr *ifa);

static void inet6_prefix_notify(int event, struct inet6_dev *idev,
                                struct prefix_info *pinfo);
static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
                               struct net_device *dev);

static struct ipv6_devconf ipv6_devconf __read_mostly = {
        .forwarding             = 0,
        .hop_limit              = IPV6_DEFAULT_HOPLIMIT,
        .mtu6                   = IPV6_MIN_MTU,
        .accept_ra              = 1,
        .accept_redirects       = 1,
        .autoconf               = 1,
        .force_mld_version      = 0,
        .mldv1_unsolicited_report_interval = 10 * HZ,
        .mldv2_unsolicited_report_interval = HZ,
        .dad_transmits          = 1,
        .rtr_solicits           = MAX_RTR_SOLICITATIONS,
        .rtr_solicit_interval   = RTR_SOLICITATION_INTERVAL,
        .rtr_solicit_max_interval = RTR_SOLICITATION_MAX_INTERVAL,
        .rtr_solicit_delay      = MAX_RTR_SOLICITATION_DELAY,
        .use_tempaddr           = 0,
        .temp_valid_lft         = TEMP_VALID_LIFETIME,
        .temp_prefered_lft      = TEMP_PREFERRED_LIFETIME,
        .regen_max_retry        = REGEN_MAX_RETRY,
        .max_desync_factor      = MAX_DESYNC_FACTOR,
        .max_addresses          = IPV6_MAX_ADDRESSES,
        .accept_ra_defrtr       = 1,
        .accept_ra_from_local   = 0,
        .accept_ra_min_hop_limit= 1,
        .accept_ra_pinfo        = 1,
#ifdef CONFIG_IPV6_ROUTER_PREF
        .accept_ra_rtr_pref     = 1,
        .rtr_probe_interval     = 60 * HZ,
#ifdef CONFIG_IPV6_ROUTE_INFO
        .accept_ra_rt_info_max_plen = 0,
#endif
#endif
        .proxy_ndp              = 0,
        .accept_source_route    = 0,    /* we do not accept RH0 by default. */
        .disable_ipv6           = 0,
        .accept_dad             = 1,
        .suppress_frag_ndisc    = 1,
        .accept_ra_mtu          = 1,
        .stable_secret          = {
                .initialized = false,
        },
        .use_oif_addrs_only     = 0,
        .ignore_routes_with_linkdown = 0,
        .keep_addr_on_down      = 0,
};

static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
        .forwarding             = 0,
        .hop_limit              = IPV6_DEFAULT_HOPLIMIT,
        .mtu6                   = IPV6_MIN_MTU,
        .accept_ra              = 1,
        .accept_redirects       = 1,
        .autoconf               = 1,
        .force_mld_version      = 0,
        .mldv1_unsolicited_report_interval = 10 * HZ,
        .mldv2_unsolicited_report_interval = HZ,
        .dad_transmits          = 1,
        .rtr_solicits           = MAX_RTR_SOLICITATIONS,
        .rtr_solicit_interval   = RTR_SOLICITATION_INTERVAL,
        .rtr_solicit_max_interval = RTR_SOLICITATION_MAX_INTERVAL,
        .rtr_solicit_delay      = MAX_RTR_SOLICITATION_DELAY,
        .use_tempaddr           = 0,
        .temp_valid_lft         = TEMP_VALID_LIFETIME,
        .temp_prefered_lft      = TEMP_PREFERRED_LIFETIME,
        .regen_max_retry        = REGEN_MAX_RETRY,
        .max_desync_factor      = MAX_DESYNC_FACTOR,
        .max_addresses          = IPV6_MAX_ADDRESSES,
        .accept_ra_defrtr       = 1,
        .accept_ra_from_local   = 0,
        .accept_ra_min_hop_limit= 1,
        .accept_ra_pinfo        = 1,
#ifdef CONFIG_IPV6_ROUTER_PREF
        .accept_ra_rtr_pref     = 1,
        .rtr_probe_interval     = 60 * HZ,
#ifdef CONFIG_IPV6_ROUTE_INFO
        .accept_ra_rt_info_max_plen = 0,
#endif
#endif
        .proxy_ndp              = 0,
        .accept_source_route    = 0,    /* we do not accept RH0 by default. */
        .disable_ipv6           = 0,
        .accept_dad             = 1,
        .suppress_frag_ndisc    = 1,
        .accept_ra_mtu          = 1,
        .stable_secret          = {
                .initialized = false,
        },
        .use_oif_addrs_only     = 0,
        .ignore_routes_with_linkdown = 0,
        .keep_addr_on_down      = 0,
};

/* Check if a valid qdisc is available */
static inline bool addrconf_qdisc_ok(const struct net_device *dev)
{
        return !qdisc_tx_is_noop(dev);
}

static void addrconf_del_rs_timer(struct inet6_dev *idev)
{
        if (del_timer(&idev->rs_timer))
                __in6_dev_put(idev);
}

static void addrconf_del_dad_work(struct inet6_ifaddr *ifp)
{
        if (cancel_delayed_work(&ifp->dad_work))
                __in6_ifa_put(ifp);
}

static void addrconf_mod_rs_timer(struct inet6_dev *idev,
                                  unsigned long when)
{
        if (!timer_pending(&idev->rs_timer))
                in6_dev_hold(idev);
        mod_timer(&idev->rs_timer, jiffies + when);
}

static void addrconf_mod_dad_work(struct inet6_ifaddr *ifp,
                                   unsigned long delay)
{
        if (!delayed_work_pending(&ifp->dad_work))
                in6_ifa_hold(ifp);
        mod_delayed_work(addrconf_wq, &ifp->dad_work, delay);
}

static int snmp6_alloc_dev(struct inet6_dev *idev)
{
        int i;

        idev->stats.ipv6 = alloc_percpu(struct ipstats_mib);
        if (!idev->stats.ipv6)
                goto err_ip;

        for_each_possible_cpu(i) {
                struct ipstats_mib *addrconf_stats;
                addrconf_stats = per_cpu_ptr(idev->stats.ipv6, i);
                u64_stats_init(&addrconf_stats->syncp);
        }


        idev->stats.icmpv6dev = kzalloc(sizeof(struct icmpv6_mib_device),
                                        GFP_KERNEL);
        if (!idev->stats.icmpv6dev)
                goto err_icmp;
        idev->stats.icmpv6msgdev = kzalloc(sizeof(struct icmpv6msg_mib_device),
                                           GFP_KERNEL);
        if (!idev->stats.icmpv6msgdev)
                goto err_icmpmsg;

        return 0;

err_icmpmsg:
        kfree(idev->stats.icmpv6dev);
err_icmp:
        free_percpu(idev->stats.ipv6);
err_ip:
        return -ENOMEM;
}

static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
{
        struct inet6_dev *ndev;
        int err = -ENOMEM;

        ASSERT_RTNL();

        if (dev->mtu < IPV6_MIN_MTU)
                return ERR_PTR(-EINVAL);

        ndev = kzalloc(sizeof(struct inet6_dev), GFP_KERNEL);
        if (!ndev)
                return ERR_PTR(err);

        rwlock_init(&ndev->lock);
        ndev->dev = dev;
        INIT_LIST_HEAD(&ndev->addr_list);
        setup_timer(&ndev->rs_timer, addrconf_rs_timer,
                    (unsigned long)ndev);
        memcpy(&ndev->cnf, dev_net(dev)->ipv6.devconf_dflt, sizeof(ndev->cnf));

        if (ndev->cnf.stable_secret.initialized)
                ndev->addr_gen_mode = IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
        else
                ndev->addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64;

        ndev->cnf.mtu6 = dev->mtu;
        ndev->nd_parms = neigh_parms_alloc(dev, &nd_tbl);
        if (!ndev->nd_parms) {
                kfree(ndev);
                return ERR_PTR(err);
        }
        if (ndev->cnf.forwarding)
                dev_disable_lro(dev);
        /* We refer to the device */
        dev_hold(dev);

        if (snmp6_alloc_dev(ndev) < 0) {
                ADBG(KERN_WARNING
                        "%s: cannot allocate memory for statistics; dev=%s.\n",
                        __func__, dev->name);
                neigh_parms_release(&nd_tbl, ndev->nd_parms);
                dev_put(dev);
                kfree(ndev);
                return ERR_PTR(err);
        }

        if (snmp6_register_dev(ndev) < 0) {
                ADBG(KERN_WARNING
                        "%s: cannot create /proc/net/dev_snmp6/%s\n",
                        __func__, dev->name);
                goto err_release;
        }

        /* One reference from device. */
        in6_dev_hold(ndev);

        if (dev->flags & (IFF_NOARP | IFF_LOOPBACK))
                ndev->cnf.accept_dad = -1;

#if IS_ENABLED(CONFIG_IPV6_SIT)
        if (dev->type == ARPHRD_SIT && (dev->priv_flags & IFF_ISATAP)) {
                pr_info("%s: Disabled Multicast RS\n", dev->name);
                ndev->cnf.rtr_solicits = 0;
        }
#endif

        INIT_LIST_HEAD(&ndev->tempaddr_list);
        ndev->desync_factor = U32_MAX;
        if ((dev->flags&IFF_LOOPBACK) ||
            dev->type == ARPHRD_TUNNEL ||
            dev->type == ARPHRD_TUNNEL6 ||
            dev->type == ARPHRD_SIT ||
            dev->type == ARPHRD_NONE) {
                ndev->cnf.use_tempaddr = -1;
        } else
                ipv6_regen_rndid(ndev);

        ndev->token = in6addr_any;

        if (netif_running(dev) && addrconf_qdisc_ok(dev))
                ndev->if_flags |= IF_READY;

        ipv6_mc_init_dev(ndev);
        ndev->tstamp = jiffies;
        err = addrconf_sysctl_register(ndev);
        if (err) {
                ipv6_mc_destroy_dev(ndev);
                snmp6_unregister_dev(ndev);
                goto err_release;
        }
        /* protected by rtnl_lock */
        rcu_assign_pointer(dev->ip6_ptr, ndev);

        /* Join interface-local all-node multicast group */
        ipv6_dev_mc_inc(dev, &in6addr_interfacelocal_allnodes);

        /* Join all-node multicast group */
        ipv6_dev_mc_inc(dev, &in6addr_linklocal_allnodes);

        /* Join all-router multicast group if forwarding is set */
        if (ndev->cnf.forwarding && (dev->flags & IFF_MULTICAST))
                ipv6_dev_mc_inc(dev, &in6addr_linklocal_allrouters);

        return ndev;

err_release:
        neigh_parms_release(&nd_tbl, ndev->nd_parms);
        ndev->dead = 1;
        in6_dev_finish_destroy(ndev);
        return ERR_PTR(err);
}

static struct inet6_dev *ipv6_find_idev(struct net_device *dev)
{
        struct inet6_dev *idev;

        ASSERT_RTNL();

        idev = __in6_dev_get(dev);
        if (!idev) {
                idev = ipv6_add_dev(dev);
                if (IS_ERR(idev))
                        return NULL;
        }

        if (dev->flags&IFF_UP)
                ipv6_mc_up(idev);
        return idev;
}

static int inet6_netconf_msgsize_devconf(int type)
{
        int size =  NLMSG_ALIGN(sizeof(struct netconfmsg))
                    + nla_total_size(4);        /* NETCONFA_IFINDEX */
        bool all = false;

        if (type == NETCONFA_ALL)
                all = true;

        if (all || type == NETCONFA_FORWARDING)
                size += nla_total_size(4);
#ifdef CONFIG_IPV6_MROUTE
        if (all || type == NETCONFA_MC_FORWARDING)
                size += nla_total_size(4);
#endif
        if (all || type == NETCONFA_PROXY_NEIGH)
                size += nla_total_size(4);

        if (all || type == NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN)
                size += nla_total_size(4);

        return size;
}

static int inet6_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
                                      struct ipv6_devconf *devconf, u32 portid,
                                      u32 seq, int event, unsigned int flags,
                                      int type)
{
        struct nlmsghdr  *nlh;
        struct netconfmsg *ncm;
        bool all = false;

        nlh = nlmsg_put(skb, portid, seq, event, sizeof(struct netconfmsg),
                        flags);
        if (!nlh)
                return -EMSGSIZE;

        if (type == NETCONFA_ALL)
                all = true;

        ncm = nlmsg_data(nlh);
        ncm->ncm_family = AF_INET6;

        if (nla_put_s32(skb, NETCONFA_IFINDEX, ifindex) < 0)
                goto nla_put_failure;

        if ((all || type == NETCONFA_FORWARDING) &&
            nla_put_s32(skb, NETCONFA_FORWARDING, devconf->forwarding) < 0)
                goto nla_put_failure;
#ifdef CONFIG_IPV6_MROUTE
        if ((all || type == NETCONFA_MC_FORWARDING) &&
            nla_put_s32(skb, NETCONFA_MC_FORWARDING,
                        devconf->mc_forwarding) < 0)
                goto nla_put_failure;
#endif
        if ((all || type == NETCONFA_PROXY_NEIGH) &&
            nla_put_s32(skb, NETCONFA_PROXY_NEIGH, devconf->proxy_ndp) < 0)
                goto nla_put_failure;

        if ((all || type == NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN) &&
            nla_put_s32(skb, NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
                        devconf->ignore_routes_with_linkdown) < 0)
                goto nla_put_failure;

        nlmsg_end(skb, nlh);
        return 0;

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

void inet6_netconf_notify_devconf(struct net *net, int type, int ifindex,
                                  struct ipv6_devconf *devconf)
{
        struct sk_buff *skb;
        int err = -ENOBUFS;

        skb = nlmsg_new(inet6_netconf_msgsize_devconf(type), GFP_KERNEL);
        if (!skb)
                goto errout;

        err = inet6_netconf_fill_devconf(skb, ifindex, devconf, 0, 0,
                                         RTM_NEWNETCONF, 0, type);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in inet6_netconf_msgsize_devconf() */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }
        rtnl_notify(skb, net, 0, RTNLGRP_IPV6_NETCONF, NULL, GFP_KERNEL);
        return;
errout:
        rtnl_set_sk_err(net, RTNLGRP_IPV6_NETCONF, err);
}

static const struct nla_policy devconf_ipv6_policy[NETCONFA_MAX+1] = {
        [NETCONFA_IFINDEX]      = { .len = sizeof(int) },
        [NETCONFA_FORWARDING]   = { .len = sizeof(int) },
        [NETCONFA_PROXY_NEIGH]  = { .len = sizeof(int) },
        [NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN]  = { .len = sizeof(int) },
};

static int inet6_netconf_get_devconf(struct sk_buff *in_skb,
                                     struct nlmsghdr *nlh)
{
        struct net *net = sock_net(in_skb->sk);
        struct nlattr *tb[NETCONFA_MAX+1];
        struct netconfmsg *ncm;
        struct sk_buff *skb;
        struct ipv6_devconf *devconf;
        struct inet6_dev *in6_dev;
        struct net_device *dev;
        int ifindex;
        int err;

        err = nlmsg_parse(nlh, sizeof(*ncm), tb, NETCONFA_MAX,
                          devconf_ipv6_policy);
        if (err < 0)
                goto errout;

        err = -EINVAL;
        if (!tb[NETCONFA_IFINDEX])
                goto errout;

        ifindex = nla_get_s32(tb[NETCONFA_IFINDEX]);
        switch (ifindex) {
        case NETCONFA_IFINDEX_ALL:
                devconf = net->ipv6.devconf_all;
                break;
        case NETCONFA_IFINDEX_DEFAULT:
                devconf = net->ipv6.devconf_dflt;
                break;
        default:
                dev = __dev_get_by_index(net, ifindex);
                if (!dev)
                        goto errout;
                in6_dev = __in6_dev_get(dev);
                if (!in6_dev)
                        goto errout;
                devconf = &in6_dev->cnf;
                break;
        }

        err = -ENOBUFS;
        skb = nlmsg_new(inet6_netconf_msgsize_devconf(NETCONFA_ALL), GFP_ATOMIC);
        if (!skb)
                goto errout;

        err = inet6_netconf_fill_devconf(skb, ifindex, devconf,
                                         NETLINK_CB(in_skb).portid,
                                         nlh->nlmsg_seq, RTM_NEWNETCONF, 0,
                                         NETCONFA_ALL);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in inet6_netconf_msgsize_devconf() */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }
        err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
errout:
        return err;
}

static int inet6_netconf_dump_devconf(struct sk_buff *skb,
                                      struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        int h, s_h;
        int idx, s_idx;
        struct net_device *dev;
        struct inet6_dev *idev;
        struct hlist_head *head;

        s_h = cb->args[0];
        s_idx = idx = cb->args[1];

        for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
                idx = 0;
                head = &net->dev_index_head[h];
                rcu_read_lock();
                cb->seq = atomic_read(&net->ipv6.dev_addr_genid) ^
                          net->dev_base_seq;
                hlist_for_each_entry_rcu(dev, head, index_hlist) {
                        if (idx < s_idx)
                                goto cont;
                        idev = __in6_dev_get(dev);
                        if (!idev)
                                goto cont;

                        if (inet6_netconf_fill_devconf(skb, dev->ifindex,
                                                       &idev->cnf,
                                                       NETLINK_CB(cb->skb).portid,
                                                       cb->nlh->nlmsg_seq,
                                                       RTM_NEWNETCONF,
                                                       NLM_F_MULTI,
                                                       NETCONFA_ALL) < 0) {
                                rcu_read_unlock();
                                goto done;
                        }
                        nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
                        idx++;
                }
                rcu_read_unlock();
        }
        if (h == NETDEV_HASHENTRIES) {
                if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_ALL,
                                               net->ipv6.devconf_all,
                                               NETLINK_CB(cb->skb).portid,
                                               cb->nlh->nlmsg_seq,
                                               RTM_NEWNETCONF, NLM_F_MULTI,
                                               NETCONFA_ALL) < 0)
                        goto done;
                else
                        h++;
        }
        if (h == NETDEV_HASHENTRIES + 1) {
                if (inet6_netconf_fill_devconf(skb, NETCONFA_IFINDEX_DEFAULT,
                                               net->ipv6.devconf_dflt,
                                               NETLINK_CB(cb->skb).portid,
                                               cb->nlh->nlmsg_seq,
                                               RTM_NEWNETCONF, NLM_F_MULTI,
                                               NETCONFA_ALL) < 0)
                        goto done;
                else
                        h++;
        }
done:
        cb->args[0] = h;
        cb->args[1] = idx;

        return skb->len;
}

#ifdef CONFIG_SYSCTL
static void dev_forward_change(struct inet6_dev *idev)
{
        struct net_device *dev;
        struct inet6_ifaddr *ifa;

        if (!idev)
                return;
        dev = idev->dev;
        if (idev->cnf.forwarding)
                dev_disable_lro(dev);
        if (dev->flags & IFF_MULTICAST) {
                if (idev->cnf.forwarding) {
                        ipv6_dev_mc_inc(dev, &in6addr_linklocal_allrouters);
                        ipv6_dev_mc_inc(dev, &in6addr_interfacelocal_allrouters);
                        ipv6_dev_mc_inc(dev, &in6addr_sitelocal_allrouters);
                } else {
                        ipv6_dev_mc_dec(dev, &in6addr_linklocal_allrouters);
                        ipv6_dev_mc_dec(dev, &in6addr_interfacelocal_allrouters);
                        ipv6_dev_mc_dec(dev, &in6addr_sitelocal_allrouters);
                }
        }

        list_for_each_entry(ifa, &idev->addr_list, if_list) {
                if (ifa->flags&IFA_F_TENTATIVE)
                        continue;
                if (idev->cnf.forwarding)
                        addrconf_join_anycast(ifa);
                else
                        addrconf_leave_anycast(ifa);
        }
        inet6_netconf_notify_devconf(dev_net(dev), NETCONFA_FORWARDING,
                                     dev->ifindex, &idev->cnf);
}


static void addrconf_forward_change(struct net *net, __s32 newf)
{
        struct net_device *dev;
        struct inet6_dev *idev;

        for_each_netdev(net, dev) {
                idev = __in6_dev_get(dev);
                if (idev) {
                        int changed = (!idev->cnf.forwarding) ^ (!newf);
                        idev->cnf.forwarding = newf;
                        if (changed)
                                dev_forward_change(idev);
                }
        }
}

static int addrconf_fixup_forwarding(struct ctl_table *table, int *p, int newf)
{
        struct net *net;
        int old;

        if (!rtnl_trylock())
                return restart_syscall();

        net = (struct net *)table->extra2;
        old = *p;
        *p = newf;

        if (p == &net->ipv6.devconf_dflt->forwarding) {
                if ((!newf) ^ (!old))
                        inet6_netconf_notify_devconf(net, NETCONFA_FORWARDING,
                                                     NETCONFA_IFINDEX_DEFAULT,
                                                     net->ipv6.devconf_dflt);
                rtnl_unlock();
                return 0;
        }

        if (p == &net->ipv6.devconf_all->forwarding) {
                int old_dflt = net->ipv6.devconf_dflt->forwarding;

                net->ipv6.devconf_dflt->forwarding = newf;
                if ((!newf) ^ (!old_dflt))
                        inet6_netconf_notify_devconf(net, NETCONFA_FORWARDING,
                                                     NETCONFA_IFINDEX_DEFAULT,
                                                     net->ipv6.devconf_dflt);

                addrconf_forward_change(net, newf);
                if ((!newf) ^ (!old))
                        inet6_netconf_notify_devconf(net, NETCONFA_FORWARDING,
                                                     NETCONFA_IFINDEX_ALL,
                                                     net->ipv6.devconf_all);
        } else if ((!newf) ^ (!old))
                dev_forward_change((struct inet6_dev *)table->extra1);
        rtnl_unlock();

        if (newf)
                rt6_purge_dflt_routers(net);
        return 1;
}

static void addrconf_linkdown_change(struct net *net, __s32 newf)
{
        struct net_device *dev;
        struct inet6_dev *idev;

        for_each_netdev(net, dev) {
                idev = __in6_dev_get(dev);
                if (idev) {
                        int changed = (!idev->cnf.ignore_routes_with_linkdown) ^ (!newf);

                        idev->cnf.ignore_routes_with_linkdown = newf;
                        if (changed)
                                inet6_netconf_notify_devconf(dev_net(dev),
                                                             NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
                                                             dev->ifindex,
                                                             &idev->cnf);
                }
        }
}

static int addrconf_fixup_linkdown(struct ctl_table *table, int *p, int newf)
{
        struct net *net;
        int old;

        if (!rtnl_trylock())
                return restart_syscall();

        net = (struct net *)table->extra2;
        old = *p;
        *p = newf;

        if (p == &net->ipv6.devconf_dflt->ignore_routes_with_linkdown) {
                if ((!newf) ^ (!old))
                        inet6_netconf_notify_devconf(net,
                                                     NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
                                                     NETCONFA_IFINDEX_DEFAULT,
                                                     net->ipv6.devconf_dflt);
                rtnl_unlock();
                return 0;
        }

        if (p == &net->ipv6.devconf_all->ignore_routes_with_linkdown) {
                net->ipv6.devconf_dflt->ignore_routes_with_linkdown = newf;
                addrconf_linkdown_change(net, newf);
                if ((!newf) ^ (!old))
                        inet6_netconf_notify_devconf(net,
                                                     NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
                                                     NETCONFA_IFINDEX_ALL,
                                                     net->ipv6.devconf_all);
        }
        rtnl_unlock();

        return 1;
}

#endif

/* Nobody refers to this ifaddr, destroy it */
void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp)
{
        WARN_ON(!hlist_unhashed(&ifp->addr_lst));

#ifdef NET_REFCNT_DEBUG
        pr_debug("%s\n", __func__);
#endif

        in6_dev_put(ifp->idev);

        if (cancel_delayed_work(&ifp->dad_work))
                pr_notice("delayed DAD work was pending while freeing ifa=%p\n",
                          ifp);

        if (ifp->state != INET6_IFADDR_STATE_DEAD) {
                pr_warn("Freeing alive inet6 address %p\n", ifp);
                return;
        }
        ip6_rt_put(ifp->rt);

        kfree_rcu(ifp, rcu);
}

static void
ipv6_link_dev_addr(struct inet6_dev *idev, struct inet6_ifaddr *ifp)
{
        struct list_head *p;
        int ifp_scope = ipv6_addr_src_scope(&ifp->addr);

        /*
         * Each device address list is sorted in order of scope -
         * global before linklocal.
         */
        list_for_each(p, &idev->addr_list) {
                struct inet6_ifaddr *ifa
                        = list_entry(p, struct inet6_ifaddr, if_list);
                if (ifp_scope >= ipv6_addr_src_scope(&ifa->addr))
                        break;
        }

        list_add_tail(&ifp->if_list, p);
}

static u32 inet6_addr_hash(const struct in6_addr *addr)
{
        return hash_32(ipv6_addr_hash(addr), IN6_ADDR_HSIZE_SHIFT);
}

/* On success it returns ifp with increased reference count */

static struct inet6_ifaddr *
ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
              const struct in6_addr *peer_addr, int pfxlen,
              int scope, u32 flags, u32 valid_lft, u32 prefered_lft)
{
        struct inet6_ifaddr *ifa = NULL;
        struct rt6_info *rt;
        unsigned int hash;
        int err = 0;
        int addr_type = ipv6_addr_type(addr);

        if (addr_type == IPV6_ADDR_ANY ||
            addr_type & IPV6_ADDR_MULTICAST ||
            (!(idev->dev->flags & IFF_LOOPBACK) &&
             addr_type & IPV6_ADDR_LOOPBACK))
                return ERR_PTR(-EADDRNOTAVAIL);

        rcu_read_lock_bh();
        if (idev->dead) {
                err = -ENODEV;                  /*XXX*/
                goto out2;
        }

        if (idev->cnf.disable_ipv6) {
                err = -EACCES;
                goto out2;
        }

        spin_lock(&addrconf_hash_lock);

        /* Ignore adding duplicate addresses on an interface */
        if (ipv6_chk_same_addr(dev_net(idev->dev), addr, idev->dev)) {
                ADBG("ipv6_add_addr: already assigned\n");
                err = -EEXIST;
                goto out;
        }

        ifa = kzalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC);

        if (!ifa) {
                ADBG("ipv6_add_addr: malloc failed\n");
                err = -ENOBUFS;
                goto out;
        }

        rt = addrconf_dst_alloc(idev, addr, false);
        if (IS_ERR(rt)) {
                err = PTR_ERR(rt);
                goto out;
        }

        neigh_parms_data_state_setall(idev->nd_parms);

        ifa->addr = *addr;
        if (peer_addr)
                ifa->peer_addr = *peer_addr;

        spin_lock_init(&ifa->lock);
        INIT_DELAYED_WORK(&ifa->dad_work, addrconf_dad_work);
        INIT_HLIST_NODE(&ifa->addr_lst);
        ifa->scope = scope;
        ifa->prefix_len = pfxlen;
        ifa->flags = flags | IFA_F_TENTATIVE;
        ifa->valid_lft = valid_lft;
        ifa->prefered_lft = prefered_lft;
        ifa->cstamp = ifa->tstamp = jiffies;
        ifa->tokenized = false;

        ifa->rt = rt;

        ifa->idev = idev;
        in6_dev_hold(idev);

        /* For caller */
        in6_ifa_hold(ifa);

        /* Add to big hash table */
        hash = inet6_addr_hash(addr);

        hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]);
        spin_unlock(&addrconf_hash_lock);

        write_lock(&idev->lock);
        /* Add to inet6_dev unicast addr list. */
        ipv6_link_dev_addr(idev, ifa);

        if (ifa->flags&IFA_F_TEMPORARY) {
                list_add(&ifa->tmp_list, &idev->tempaddr_list);
                in6_ifa_hold(ifa);
        }

        in6_ifa_hold(ifa);
        write_unlock(&idev->lock);
out2:
        rcu_read_unlock_bh();

        if (likely(err == 0))
                inet6addr_notifier_call_chain(NETDEV_UP, ifa);
        else {
                kfree(ifa);
                ifa = ERR_PTR(err);
        }

        return ifa;
out:
        spin_unlock(&addrconf_hash_lock);
        goto out2;
}

enum cleanup_prefix_rt_t {
        CLEANUP_PREFIX_RT_NOP,    /* no cleanup action for prefix route */
        CLEANUP_PREFIX_RT_DEL,    /* delete the prefix route */
        CLEANUP_PREFIX_RT_EXPIRE, /* update the lifetime of the prefix route */
};

/*
 * Check, whether the prefix for ifp would still need a prefix route
 * after deleting ifp. The function returns one of the CLEANUP_PREFIX_RT_*
 * constants.
 *
 * 1) we don't purge prefix if address was not permanent.
 *    prefix is managed by its own lifetime.
 * 2) we also don't purge, if the address was IFA_F_NOPREFIXROUTE.
 * 3) if there are no addresses, delete prefix.
 * 4) if there are still other permanent address(es),
 *    corresponding prefix is still permanent.
 * 5) if there are still other addresses with IFA_F_NOPREFIXROUTE,
 *    don't purge the prefix, assume user space is managing it.
 * 6) otherwise, update prefix lifetime to the
 *    longest valid lifetime among the corresponding
 *    addresses on the device.
 *    Note: subsequent RA will update lifetime.
 **/
static enum cleanup_prefix_rt_t
check_cleanup_prefix_route(struct inet6_ifaddr *ifp, unsigned long *expires)
{
        struct inet6_ifaddr *ifa;
        struct inet6_dev *idev = ifp->idev;
        unsigned long lifetime;
        enum cleanup_prefix_rt_t action = CLEANUP_PREFIX_RT_DEL;

        *expires = jiffies;

        list_for_each_entry(ifa, &idev->addr_list, if_list) {
                if (ifa == ifp)
                        continue;
                if (!ipv6_prefix_equal(&ifa->addr, &ifp->addr,
                                       ifp->prefix_len))
                        continue;
                if (ifa->flags & (IFA_F_PERMANENT | IFA_F_NOPREFIXROUTE))
                        return CLEANUP_PREFIX_RT_NOP;

                action = CLEANUP_PREFIX_RT_EXPIRE;

                spin_lock(&ifa->lock);

                lifetime = addrconf_timeout_fixup(ifa->valid_lft, HZ);
                /*
                 * Note: Because this address is
                 * not permanent, lifetime <
                 * LONG_MAX / HZ here.
                 */
                if (time_before(*expires, ifa->tstamp + lifetime * HZ))
                        *expires = ifa->tstamp + lifetime * HZ;
                spin_unlock(&ifa->lock);
        }

        return action;
}

static void
cleanup_prefix_route(struct inet6_ifaddr *ifp, unsigned long expires, bool del_rt)
{
        struct rt6_info *rt;

        rt = addrconf_get_prefix_route(&ifp->addr,
                                       ifp->prefix_len,
                                       ifp->idev->dev,
                                       0, RTF_GATEWAY | RTF_DEFAULT);
        if (rt) {
                if (del_rt)
                        ip6_del_rt(rt);
                else {
                        if (!(rt->rt6i_flags & RTF_EXPIRES))
                                rt6_set_expires(rt, expires);
                        ip6_rt_put(rt);
                }
        }
}


/* This function wants to get referenced ifp and releases it before return */

static void ipv6_del_addr(struct inet6_ifaddr *ifp)
{
        int state;
        enum cleanup_prefix_rt_t action = CLEANUP_PREFIX_RT_NOP;
        unsigned long expires;

        ASSERT_RTNL();

        spin_lock_bh(&ifp->lock);
        state = ifp->state;
        ifp->state = INET6_IFADDR_STATE_DEAD;
        spin_unlock_bh(&ifp->lock);

        if (state == INET6_IFADDR_STATE_DEAD)
                goto out;

        spin_lock_bh(&addrconf_hash_lock);
        hlist_del_init_rcu(&ifp->addr_lst);
        spin_unlock_bh(&addrconf_hash_lock);

        write_lock_bh(&ifp->idev->lock);

        if (ifp->flags&IFA_F_TEMPORARY) {
                list_del(&ifp->tmp_list);
                if (ifp->ifpub) {
                        in6_ifa_put(ifp->ifpub);
                        ifp->ifpub = NULL;
                }
                __in6_ifa_put(ifp);
        }

        if (ifp->flags & IFA_F_PERMANENT && !(ifp->flags & IFA_F_NOPREFIXROUTE))
                action = check_cleanup_prefix_route(ifp, &expires);

        list_del_init(&ifp->if_list);
        __in6_ifa_put(ifp);

        write_unlock_bh(&ifp->idev->lock);

        addrconf_del_dad_work(ifp);

        ipv6_ifa_notify(RTM_DELADDR, ifp);

        inet6addr_notifier_call_chain(NETDEV_DOWN, ifp);

        if (action != CLEANUP_PREFIX_RT_NOP) {
                cleanup_prefix_route(ifp, expires,
                        action == CLEANUP_PREFIX_RT_DEL);
        }

        /* clean up prefsrc entries */
        rt6_remove_prefsrc(ifp);
out:
        in6_ifa_put(ifp);
}

static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, struct inet6_ifaddr *ift)
{
        struct inet6_dev *idev = ifp->idev;
        struct in6_addr addr, *tmpaddr;
        unsigned long tmp_prefered_lft, tmp_valid_lft, tmp_tstamp, age;
        unsigned long regen_advance;
        int tmp_plen;
        int ret = 0;
        u32 addr_flags;
        unsigned long now = jiffies;
        long max_desync_factor;
        s32 cnf_temp_preferred_lft;

        write_lock_bh(&idev->lock);
        if (ift) {
                spin_lock_bh(&ift->lock);
                memcpy(&addr.s6_addr[8], &ift->addr.s6_addr[8], 8);
                spin_unlock_bh(&ift->lock);
                tmpaddr = &addr;
        } else {
                tmpaddr = NULL;
        }
retry:
        in6_dev_hold(idev);
        if (idev->cnf.use_tempaddr <= 0) {
                write_unlock_bh(&idev->lock);
                pr_info("%s: use_tempaddr is disabled\n", __func__);
                in6_dev_put(idev);
                ret = -1;
                goto out;
        }
        spin_lock_bh(&ifp->lock);
        if (ifp->regen_count++ >= idev->cnf.regen_max_retry) {
                idev->cnf.use_tempaddr = -1;    /*XXX*/
                spin_unlock_bh(&ifp->lock);
                write_unlock_bh(&idev->lock);
                pr_warn("%s: regeneration time exceeded - disabled temporary address support\n",
                        __func__);
                in6_dev_put(idev);
                ret = -1;
                goto out;
        }
        in6_ifa_hold(ifp);
        memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);
        ipv6_try_regen_rndid(idev, tmpaddr);
        memcpy(&addr.s6_addr[8], idev->rndid, 8);
        age = (now - ifp->tstamp) / HZ;

        regen_advance = idev->cnf.regen_max_retry *
                        idev->cnf.dad_transmits *
                        NEIGH_VAR(idev->nd_parms, RETRANS_TIME) / HZ;

        /* recalculate max_desync_factor each time and update
         * idev->desync_factor if it's larger
         */
        cnf_temp_preferred_lft = READ_ONCE(idev->cnf.temp_prefered_lft);
        max_desync_factor = min_t(__u32,
                                  idev->cnf.max_desync_factor,
                                  cnf_temp_preferred_lft - regen_advance);

        if (unlikely(idev->desync_factor > max_desync_factor)) {
                if (max_desync_factor > 0) {
                        get_random_bytes(&idev->desync_factor,
                                         sizeof(idev->desync_factor));
                        idev->desync_factor %= max_desync_factor;
                } else {
                        idev->desync_factor = 0;
                }
        }

        tmp_valid_lft = min_t(__u32,
                              ifp->valid_lft,
                              idev->cnf.temp_valid_lft + age);
        tmp_prefered_lft = cnf_temp_preferred_lft + age -
                            idev->desync_factor;
        tmp_prefered_lft = min_t(__u32, ifp->prefered_lft, tmp_prefered_lft);
        tmp_plen = ifp->prefix_len;
        tmp_tstamp = ifp->tstamp;
        spin_unlock_bh(&ifp->lock);

        write_unlock_bh(&idev->lock);

        /* A temporary address is created only if this calculated Preferred
         * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
         * an implementation must not create a temporary address with a zero
         * Preferred Lifetime.
         * Use age calculation as in addrconf_verify to avoid unnecessary
         * temporary addresses being generated.
         */
        age = (now - tmp_tstamp + ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
        if (tmp_prefered_lft <= regen_advance + age) {
                in6_ifa_put(ifp);
                in6_dev_put(idev);
                ret = -1;
                goto out;
        }

        addr_flags = IFA_F_TEMPORARY;
        /* set in addrconf_prefix_rcv() */
        if (ifp->flags & IFA_F_OPTIMISTIC)
                addr_flags |= IFA_F_OPTIMISTIC;

        ift = ipv6_add_addr(idev, &addr, NULL, tmp_plen,
                            ipv6_addr_scope(&addr), addr_flags,
                            tmp_valid_lft, tmp_prefered_lft);
        if (IS_ERR(ift)) {
                in6_ifa_put(ifp);
                in6_dev_put(idev);
                pr_info("%s: retry temporary address regeneration\n", __func__);
                tmpaddr = &addr;
                write_lock_bh(&idev->lock);
                goto retry;
        }

        spin_lock_bh(&ift->lock);
        ift->ifpub = ifp;
        ift->cstamp = now;
        ift->tstamp = tmp_tstamp;
        spin_unlock_bh(&ift->lock);

        addrconf_dad_start(ift);
        in6_ifa_put(ift);
        in6_dev_put(idev);
out:
        return ret;
}

/*
 *      Choose an appropriate source address (RFC3484)
 */
enum {
        IPV6_SADDR_RULE_INIT = 0,
        IPV6_SADDR_RULE_LOCAL,
        IPV6_SADDR_RULE_SCOPE,
        IPV6_SADDR_RULE_PREFERRED,
#ifdef CONFIG_IPV6_MIP6
        IPV6_SADDR_RULE_HOA,
#endif
        IPV6_SADDR_RULE_OIF,
        IPV6_SADDR_RULE_LABEL,
        IPV6_SADDR_RULE_PRIVACY,
        IPV6_SADDR_RULE_ORCHID,
        IPV6_SADDR_RULE_PREFIX,
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
        IPV6_SADDR_RULE_NOT_OPTIMISTIC,
#endif
        IPV6_SADDR_RULE_MAX
};

struct ipv6_saddr_score {
        int                     rule;
        int                     addr_type;
        struct inet6_ifaddr     *ifa;
        DECLARE_BITMAP(scorebits, IPV6_SADDR_RULE_MAX);
        int                     scopedist;
        int                     matchlen;
};

struct ipv6_saddr_dst {
        const struct in6_addr *addr;
        int ifindex;
        int scope;
        int label;
        unsigned int prefs;
};

static inline int ipv6_saddr_preferred(int type)
{
        if (type & (IPV6_ADDR_MAPPED|IPV6_ADDR_COMPATv4|IPV6_ADDR_LOOPBACK))
                return 1;
        return 0;
}

static inline bool ipv6_use_optimistic_addr(struct inet6_dev *idev)
{
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
        return idev && idev->cnf.optimistic_dad && idev->cnf.use_optimistic;
#else
        return false;
#endif
}

static int ipv6_get_saddr_eval(struct net *net,
                               struct ipv6_saddr_score *score,
                               struct ipv6_saddr_dst *dst,
                               int i)
{
        int ret;

        if (i <= score->rule) {
                switch (i) {
                case IPV6_SADDR_RULE_SCOPE:
                        ret = score->scopedist;
                        break;
                case IPV6_SADDR_RULE_PREFIX:
                        ret = score->matchlen;
                        break;
                default:
                        ret = !!test_bit(i, score->scorebits);
                }
                goto out;
        }

        switch (i) {
        case IPV6_SADDR_RULE_INIT:
                /* Rule 0: remember if hiscore is not ready yet */
                ret = !!score->ifa;
                break;
        case IPV6_SADDR_RULE_LOCAL:
                /* Rule 1: Prefer same address */
                ret = ipv6_addr_equal(&score->ifa->addr, dst->addr);
                break;
        case IPV6_SADDR_RULE_SCOPE:
                /* Rule 2: Prefer appropriate scope
                 *
                 *      ret
                 *       ^
                 *    -1 |  d 15
                 *    ---+--+-+---> scope
                 *       |
                 *       |             d is scope of the destination.
                 *  B-d  |  \
                 *       |   \      <- smaller scope is better if
                 *  B-15 |    \        if scope is enough for destination.
                 *       |             ret = B - scope (-1 <= scope >= d <= 15).
                 * d-C-1 | /
                 *       |/         <- greater is better
                 *   -C  /             if scope is not enough for destination.
                 *      /|             ret = scope - C (-1 <= d < scope <= 15).
                 *
                 * d - C - 1 < B -15 (for all -1 <= d <= 15).
                 * C > d + 14 - B >= 15 + 14 - B = 29 - B.
                 * Assume B = 0 and we get C > 29.
                 */
                ret = __ipv6_addr_src_scope(score->addr_type);
                if (ret >= dst->scope)
                        ret = -ret;
                else
                        ret -= 128;     /* 30 is enough */
                score->scopedist = ret;
                break;
        case IPV6_SADDR_RULE_PREFERRED:
            {
                /* Rule 3: Avoid deprecated and optimistic addresses */
                u8 avoid = IFA_F_DEPRECATED;

                if (!ipv6_use_optimistic_addr(score->ifa->idev))
                        avoid |= IFA_F_OPTIMISTIC;
                ret = ipv6_saddr_preferred(score->addr_type) ||
                      !(score->ifa->flags & avoid);
                break;
            }
#ifdef CONFIG_IPV6_MIP6
        case IPV6_SADDR_RULE_HOA:
            {
                /* Rule 4: Prefer home address */
                int prefhome = !(dst->prefs & IPV6_PREFER_SRC_COA);
                ret = !(score->ifa->flags & IFA_F_HOMEADDRESS) ^ prefhome;
                break;
            }
#endif
        case IPV6_SADDR_RULE_OIF:
                /* Rule 5: Prefer outgoing interface */
                ret = (!dst->ifindex ||
                       dst->ifindex == score->ifa->idev->dev->ifindex);
                break;
        case IPV6_SADDR_RULE_LABEL:
                /* Rule 6: Prefer matching label */
                ret = ipv6_addr_label(net,
                                      &score->ifa->addr, score->addr_type,
                                      score->ifa->idev->dev->ifindex) == dst->label;
                break;
        case IPV6_SADDR_RULE_PRIVACY:
            {
                /* Rule 7: Prefer public address
                 * Note: prefer temporary address if use_tempaddr >= 2
                 */
                int preftmp = dst->prefs & (IPV6_PREFER_SRC_PUBLIC|IPV6_PREFER_SRC_TMP) ?
                                !!(dst->prefs & IPV6_PREFER_SRC_TMP) :
                                score->ifa->idev->cnf.use_tempaddr >= 2;
                ret = (!(score->ifa->flags & IFA_F_TEMPORARY)) ^ preftmp;
                break;
            }
        case IPV6_SADDR_RULE_ORCHID:
                /* Rule 8-: Prefer ORCHID vs ORCHID or
                 *          non-ORCHID vs non-ORCHID
                 */
                ret = !(ipv6_addr_orchid(&score->ifa->addr) ^
                        ipv6_addr_orchid(dst->addr));
                break;
        case IPV6_SADDR_RULE_PREFIX:
                /* Rule 8: Use longest matching prefix */
                ret = ipv6_addr_diff(&score->ifa->addr, dst->addr);
                if (ret > score->ifa->prefix_len)
                        ret = score->ifa->prefix_len;
                score->matchlen = ret;
                break;
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
        case IPV6_SADDR_RULE_NOT_OPTIMISTIC:
                /* Optimistic addresses still have lower precedence than other
                 * preferred addresses.
                 */
                ret = !(score->ifa->flags & IFA_F_OPTIMISTIC);
                break;
#endif
        default:
                ret = 0;
        }

        if (ret)
                __set_bit(i, score->scorebits);
        score->rule = i;
out:
        return ret;
}

static int __ipv6_dev_get_saddr(struct net *net,
                                struct ipv6_saddr_dst *dst,
                                struct inet6_dev *idev,
                                struct ipv6_saddr_score *scores,
                                int hiscore_idx)
{
        struct ipv6_saddr_score *score = &scores[1 - hiscore_idx], *hiscore = &scores[hiscore_idx];

        read_lock_bh(&idev->lock);
        list_for_each_entry(score->ifa, &idev->addr_list, if_list) {
                int i;

                /*
                 * - Tentative Address (RFC2462 section 5.4)
                 *  - A tentative address is not considered
                 *    "assigned to an interface" in the traditional
                 *    sense, unless it is also flagged as optimistic.
                 * - Candidate Source Address (section 4)
                 *  - In any case, anycast addresses, multicast
                 *    addresses, and the unspecified address MUST
                 *    NOT be included in a candidate set.
                 */
                if ((score->ifa->flags & IFA_F_TENTATIVE) &&
                    (!(score->ifa->flags & IFA_F_OPTIMISTIC)))
                        continue;

                score->addr_type = __ipv6_addr_type(&score->ifa->addr);

                if (unlikely(score->addr_type == IPV6_ADDR_ANY ||
                             score->addr_type & IPV6_ADDR_MULTICAST)) {
                        net_dbg_ratelimited("ADDRCONF: unspecified / multicast address assigned as unicast address on %s",
                                            idev->dev->name);
                        continue;
                }

                score->rule = -1;
                bitmap_zero(score->scorebits, IPV6_SADDR_RULE_MAX);

                for (i = 0; i < IPV6_SADDR_RULE_MAX; i++) {
                        int minihiscore, miniscore;

                        minihiscore = ipv6_get_saddr_eval(net, hiscore, dst, i);
                        miniscore = ipv6_get_saddr_eval(net, score, dst, i);

                        if (minihiscore > miniscore) {
                                if (i == IPV6_SADDR_RULE_SCOPE &&
                                    score->scopedist > 0) {
                                        /*
                                         * special case:
                                         * each remaining entry
                                         * has too small (not enough)
                                         * scope, because ifa entries
                                         * are sorted by their scope
                                         * values.
                                         */
                                        goto out;
                                }
                                break;
                        } else if (minihiscore < miniscore) {
                                if (hiscore->ifa)
                                        in6_ifa_put(hiscore->ifa);

                                in6_ifa_hold(score->ifa);

                                swap(hiscore, score);
                                hiscore_idx = 1 - hiscore_idx;

                                /* restore our iterator */
                                score->ifa = hiscore->ifa;

                                break;
                        }
                }
        }
out:
        read_unlock_bh(&idev->lock);
        return hiscore_idx;
}

static int ipv6_get_saddr_master(struct net *net,
                                 const struct net_device *dst_dev,
                                 const struct net_device *master,
                                 struct ipv6_saddr_dst *dst,
                                 struct ipv6_saddr_score *scores,
                                 int hiscore_idx)
{
        struct inet6_dev *idev;

        idev = __in6_dev_get(dst_dev);
        if (idev)
                hiscore_idx = __ipv6_dev_get_saddr(net, dst, idev,
                                                   scores, hiscore_idx);

        idev = __in6_dev_get(master);
        if (idev)
                hiscore_idx = __ipv6_dev_get_saddr(net, dst, idev,
                                                   scores, hiscore_idx);

        return hiscore_idx;
}

int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
                       const struct in6_addr *daddr, unsigned int prefs,
                       struct in6_addr *saddr)
{
        struct ipv6_saddr_score scores[2], *hiscore;
        struct ipv6_saddr_dst dst;
        struct inet6_dev *idev;
        struct net_device *dev;
        int dst_type;
        bool use_oif_addr = false;
        int hiscore_idx = 0;

        dst_type = __ipv6_addr_type(daddr);
        dst.addr = daddr;
        dst.ifindex = dst_dev ? dst_dev->ifindex : 0;
        dst.scope = __ipv6_addr_src_scope(dst_type);
        dst.label = ipv6_addr_label(net, daddr, dst_type, dst.ifindex);
        dst.prefs = prefs;

        scores[hiscore_idx].rule = -1;
        scores[hiscore_idx].ifa = NULL;

        rcu_read_lock();

        /* Candidate Source Address (section 4)
         *  - multicast and link-local destination address,
         *    the set of candidate source address MUST only
         *    include addresses assigned to interfaces
         *    belonging to the same link as the outgoing
         *    interface.
         * (- For site-local destination addresses, the
         *    set of candidate source addresses MUST only
         *    include addresses assigned to interfaces
         *    belonging to the same site as the outgoing
         *    interface.)
         *  - "It is RECOMMENDED that the candidate source addresses
         *    be the set of unicast addresses assigned to the
         *    interface that will be used to send to the destination
         *    (the 'outgoing' interface)." (RFC 6724)
         */
        if (dst_dev) {
                idev = __in6_dev_get(dst_dev);
                if ((dst_type & IPV6_ADDR_MULTICAST) ||
                    dst.scope <= IPV6_ADDR_SCOPE_LINKLOCAL ||
                    (idev && idev->cnf.use_oif_addrs_only)) {
                        use_oif_addr = true;
                }
        }

        if (use_oif_addr) {
                if (idev)
                        hiscore_idx = __ipv6_dev_get_saddr(net, &dst, idev, scores, hiscore_idx);
        } else {
                const struct net_device *master;
                int master_idx = 0;

                /* if dst_dev exists and is enslaved to an L3 device, then
                 * prefer addresses from dst_dev and then the master over
                 * any other enslaved devices in the L3 domain.
                 */
                master = l3mdev_master_dev_rcu(dst_dev);
                if (master) {
                        master_idx = master->ifindex;

                        hiscore_idx = ipv6_get_saddr_master(net, dst_dev,
                                                            master, &dst,
                                                            scores, hiscore_idx);

                        if (scores[hiscore_idx].ifa)
                                goto out;
                }

                for_each_netdev_rcu(net, dev) {
                        /* only consider addresses on devices in the
                         * same L3 domain
                         */
                        if (l3mdev_master_ifindex_rcu(dev) != master_idx)
                                continue;
                        idev = __in6_dev_get(dev);
                        if (!idev)
                                continue;
                        hiscore_idx = __ipv6_dev_get_saddr(net, &dst, idev, scores, hiscore_idx);
                }
        }

out:
        rcu_read_unlock();

        hiscore = &scores[hiscore_idx];
        if (!hiscore->ifa)
                return -EADDRNOTAVAIL;

        *saddr = hiscore->ifa->addr;
        in6_ifa_put(hiscore->ifa);
        return 0;
}
EXPORT_SYMBOL(ipv6_dev_get_saddr);

int __ipv6_get_lladdr(struct inet6_dev *idev, struct in6_addr *addr,
                      u32 banned_flags)
{
        struct inet6_ifaddr *ifp;
        int err = -EADDRNOTAVAIL;

        list_for_each_entry_reverse(ifp, &idev->addr_list, if_list) {
                if (ifp->scope > IFA_LINK)
                        break;
                if (ifp->scope == IFA_LINK &&
                    !(ifp->flags & banned_flags)) {
                        *addr = ifp->addr;
                        err = 0;
                        break;
                }
        }
        return err;
}

int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
                    u32 banned_flags)
{
        struct inet6_dev *idev;
        int err = -EADDRNOTAVAIL;

        rcu_read_lock();
        idev = __in6_dev_get(dev);
        if (idev) {
                read_lock_bh(&idev->lock);
                err = __ipv6_get_lladdr(idev, addr, banned_flags);
                read_unlock_bh(&idev->lock);
        }
        rcu_read_unlock();
        return err;
}

static int ipv6_count_addresses(struct inet6_dev *idev)
{
        int cnt = 0;
        struct inet6_ifaddr *ifp;

        read_lock_bh(&idev->lock);
        list_for_each_entry(ifp, &idev->addr_list, if_list)
                cnt++;
        read_unlock_bh(&idev->lock);
        return cnt;
}

int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
                  const struct net_device *dev, int strict)
{
        return ipv6_chk_addr_and_flags(net, addr, dev, strict, IFA_F_TENTATIVE);
}
EXPORT_SYMBOL(ipv6_chk_addr);

int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
                            const struct net_device *dev, int strict,
                            u32 banned_flags)
{
        struct inet6_ifaddr *ifp;
        unsigned int hash = inet6_addr_hash(addr);
        u32 ifp_flags;

        rcu_read_lock_bh();
        hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
                if (!net_eq(dev_net(ifp->idev->dev), net))
                        continue;
                /* Decouple optimistic from tentative for evaluation here.
                 * Ban optimistic addresses explicitly, when required.
                 */
                ifp_flags = (ifp->flags&IFA_F_OPTIMISTIC)
                            ? (ifp->flags&~IFA_F_TENTATIVE)
                            : ifp->flags;
                if (ipv6_addr_equal(&ifp->addr, addr) &&
                    !(ifp_flags&banned_flags) &&
                    (!dev || ifp->idev->dev == dev ||
                     !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))) {
                        rcu_read_unlock_bh();
                        return 1;
                }
        }

        rcu_read_unlock_bh();
        return 0;
}
EXPORT_SYMBOL(ipv6_chk_addr_and_flags);

static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
                               struct net_device *dev)
{
        unsigned int hash = inet6_addr_hash(addr);
        struct inet6_ifaddr *ifp;

        hlist_for_each_entry(ifp, &inet6_addr_lst[hash], addr_lst) {
                if (!net_eq(dev_net(ifp->idev->dev), net))
                        continue;
                if (ipv6_addr_equal(&ifp->addr, addr)) {
                        if (!dev || ifp->idev->dev == dev)
                                return true;
                }
        }
        return false;
}

/* Compares an address/prefix_len with addresses on device @dev.
 * If one is found it returns true.
 */
bool ipv6_chk_custom_prefix(const struct in6_addr *addr,
        const unsigned int prefix_len, struct net_device *dev)
{
        struct inet6_dev *idev;
        struct inet6_ifaddr *ifa;
        bool ret = false;

        rcu_read_lock();
        idev = __in6_dev_get(dev);
        if (idev) {
                read_lock_bh(&idev->lock);
                list_for_each_entry(ifa, &idev->addr_list, if_list) {
                        ret = ipv6_prefix_equal(addr, &ifa->addr, prefix_len);
                        if (ret)
                                break;
                }
                read_unlock_bh(&idev->lock);
        }
        rcu_read_unlock();

        return ret;
}
EXPORT_SYMBOL(ipv6_chk_custom_prefix);

int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
{
        struct inet6_dev *idev;
        struct inet6_ifaddr *ifa;
        int     onlink;

        onlink = 0;
        rcu_read_lock();
        idev = __in6_dev_get(dev);
        if (idev) {
                read_lock_bh(&idev->lock);
                list_for_each_entry(ifa, &idev->addr_list, if_list) {
                        onlink = ipv6_prefix_equal(addr, &ifa->addr,
                                                   ifa->prefix_len);
                        if (onlink)
                                break;
                }
                read_unlock_bh(&idev->lock);
        }
        rcu_read_unlock();
        return onlink;
}
EXPORT_SYMBOL(ipv6_chk_prefix);

struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
                                     struct net_device *dev, int strict)
{
        struct inet6_ifaddr *ifp, *result = NULL;
        unsigned int hash = inet6_addr_hash(addr);

        rcu_read_lock_bh();
        hlist_for_each_entry_rcu_bh(ifp, &inet6_addr_lst[hash], addr_lst) {
                if (!net_eq(dev_net(ifp->idev->dev), net))
                        continue;
                if (ipv6_addr_equal(&ifp->addr, addr)) {
                        if (!dev || ifp->idev->dev == dev ||
                            !(ifp->scope&(IFA_LINK|IFA_HOST) || strict)) {
                                result = ifp;
                                in6_ifa_hold(ifp);
                                break;
                        }
                }
        }
        rcu_read_unlock_bh();

        return result;
}

/* Gets referenced address, destroys ifaddr */

static void addrconf_dad_stop(struct inet6_ifaddr *ifp, int dad_failed)
{
        if (dad_failed)
                ifp->flags |= IFA_F_DADFAILED;

        if (ifp->flags&IFA_F_PERMANENT) {
                spin_lock_bh(&ifp->lock);
                addrconf_del_dad_work(ifp);
                ifp->flags |= IFA_F_TENTATIVE;
                spin_unlock_bh(&ifp->lock);
                if (dad_failed)
                        ipv6_ifa_notify(0, ifp);
                in6_ifa_put(ifp);
        } else if (ifp->flags&IFA_F_TEMPORARY) {
                struct inet6_ifaddr *ifpub;
                spin_lock_bh(&ifp->lock);
                ifpub = ifp->ifpub;
                if (ifpub) {
                        in6_ifa_hold(ifpub);
                        spin_unlock_bh(&ifp->lock);
                        ipv6_create_tempaddr(ifpub, ifp);
                        in6_ifa_put(ifpub);
                } else {
                        spin_unlock_bh(&ifp->lock);
                }
                ipv6_del_addr(ifp);
        } else {
                ipv6_del_addr(ifp);
        }
}

static int addrconf_dad_end(struct inet6_ifaddr *ifp)
{
        int err = -ENOENT;

        spin_lock_bh(&ifp->lock);
        if (ifp->state == INET6_IFADDR_STATE_DAD) {
                ifp->state = INET6_IFADDR_STATE_POSTDAD;
                err = 0;
        }
        spin_unlock_bh(&ifp->lock);

        return err;
}

void addrconf_dad_failure(struct inet6_ifaddr *ifp)
{
        struct inet6_dev *idev = ifp->idev;
        struct net *net = dev_net(ifp->idev->dev);

        if (addrconf_dad_end(ifp)) {
                in6_ifa_put(ifp);
                return;
        }

        net_info_ratelimited("%s: IPv6 duplicate address %pI6c detected!\n",
                             ifp->idev->dev->name, &ifp->addr);

        spin_lock_bh(&ifp->lock);

        if (ifp->flags & IFA_F_STABLE_PRIVACY) {
                int scope = ifp->scope;
                u32 flags = ifp->flags;
                struct in6_addr new_addr;
                struct inet6_ifaddr *ifp2;
                u32 valid_lft, preferred_lft;
                int pfxlen = ifp->prefix_len;
                int retries = ifp->stable_privacy_retry + 1;

                if (retries > net->ipv6.sysctl.idgen_retries) {
                        net_info_ratelimited("%s: privacy stable address generation failed because of DAD conflicts!\n",
                                             ifp->idev->dev->name);
                        goto errdad;
                }

                new_addr = ifp->addr;
                if (ipv6_generate_stable_address(&new_addr, retries,
                                                 idev))
                        goto errdad;

                valid_lft = ifp->valid_lft;
                preferred_lft = ifp->prefered_lft;

                spin_unlock_bh(&ifp->lock);

                if (idev->cnf.max_addresses &&
                    ipv6_count_addresses(idev) >=
                    idev->cnf.max_addresses)
                        goto lock_errdad;

                net_info_ratelimited("%s: generating new stable privacy address because of DAD conflict\n",
                                     ifp->idev->dev->name);

                ifp2 = ipv6_add_addr(idev, &new_addr, NULL, pfxlen,
                                     scope, flags, valid_lft,
                                     preferred_lft);
                if (IS_ERR(ifp2))
                        goto lock_errdad;

                spin_lock_bh(&ifp2->lock);
                ifp2->stable_privacy_retry = retries;
                ifp2->state = INET6_IFADDR_STATE_PREDAD;
                spin_unlock_bh(&ifp2->lock);

                addrconf_mod_dad_work(ifp2, net->ipv6.sysctl.idgen_delay);
                in6_ifa_put(ifp2);
lock_errdad:
                spin_lock_bh(&ifp->lock);
        }

errdad:
        /* transition from _POSTDAD to _ERRDAD */
        ifp->state = INET6_IFADDR_STATE_ERRDAD;
        spin_unlock_bh(&ifp->lock);

        addrconf_mod_dad_work(ifp, 0);
        in6_ifa_put(ifp);
}

/* Join to solicited addr multicast group.
 * caller must hold RTNL */
void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr)
{
        struct in6_addr maddr;

        if (dev->flags&(IFF_LOOPBACK|IFF_NOARP))
                return;

        addrconf_addr_solict_mult(addr, &maddr);
        ipv6_dev_mc_inc(dev, &maddr);
}

/* caller must hold RTNL */
void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr)
{
        struct in6_addr maddr;

        if (idev->dev->flags&(IFF_LOOPBACK|IFF_NOARP))
                return;

        addrconf_addr_solict_mult(addr, &maddr);
        __ipv6_dev_mc_dec(idev, &maddr);
}

/* caller must hold RTNL */
static void addrconf_join_anycast(struct inet6_ifaddr *ifp)
{
        struct in6_addr addr;

        if (ifp->prefix_len >= 127) /* RFC 6164 */
                return;
        ipv6_addr_prefix(&addr, &ifp->addr, ifp->prefix_len);
        if (ipv6_addr_any(&addr))
                return;
        __ipv6_dev_ac_inc(ifp->idev, &addr);
}

/* caller must hold RTNL */
static void addrconf_leave_anycast(struct inet6_ifaddr *ifp)
{
        struct in6_addr addr;

        if (ifp->prefix_len >= 127) /* RFC 6164 */
                return;
        ipv6_addr_prefix(&addr, &ifp->addr, ifp->prefix_len);
        if (ipv6_addr_any(&addr))
                return;
        __ipv6_dev_ac_dec(ifp->idev, &addr);
}

static int addrconf_ifid_eui64(u8 *eui, struct net_device *dev)
{
        if (dev->addr_len != EUI64_ADDR_LEN)
                return -1;
        memcpy(eui, dev->dev_addr, EUI64_ADDR_LEN);
        eui[0] ^= 2;
        return 0;
}

static int addrconf_ifid_ieee1394(u8 *eui, struct net_device *dev)
{
        union fwnet_hwaddr *ha;

        if (dev->addr_len != FWNET_ALEN)
                return -1;

        ha = (union fwnet_hwaddr *)dev->dev_addr;

        memcpy(eui, &ha->uc.uniq_id, sizeof(ha->uc.uniq_id));
        eui[0] ^= 2;
        return 0;
}

static int addrconf_ifid_arcnet(u8 *eui, struct net_device *dev)
{
        /* XXX: inherit EUI-64 from other interface -- yoshfuji */
        if (dev->addr_len != ARCNET_ALEN)
                return -1;
        memset(eui, 0, 7);
        eui[7] = *(u8 *)dev->dev_addr;
        return 0;
}

static int addrconf_ifid_infiniband(u8 *eui, struct net_device *dev)
{
        if (dev->addr_len != INFINIBAND_ALEN)
                return -1;
        memcpy(eui, dev->dev_addr + 12, 8);
        eui[0] |= 2;
        return 0;
}

static int __ipv6_isatap_ifid(u8 *eui, __be32 addr)
{
        if (addr == 0)
                return -1;
        eui[0] = (ipv4_is_zeronet(addr) || ipv4_is_private_10(addr) ||
                  ipv4_is_loopback(addr) || ipv4_is_linklocal_169(addr) ||
                  ipv4_is_private_172(addr) || ipv4_is_test_192(addr) ||
                  ipv4_is_anycast_6to4(addr) || ipv4_is_private_192(addr) ||
                  ipv4_is_test_198(addr) || ipv4_is_multicast(addr) ||
                  ipv4_is_lbcast(addr)) ? 0x00 : 0x02;
        eui[1] = 0;
        eui[2] = 0x5E;
        eui[3] = 0xFE;
        memcpy(eui + 4, &addr, 4);
        return 0;
}

static int addrconf_ifid_sit(u8 *eui, struct net_device *dev)
{
        if (dev->priv_flags & IFF_ISATAP)
                return __ipv6_isatap_ifid(eui, *(__be32 *)dev->dev_addr);
        return -1;
}

static int addrconf_ifid_gre(u8 *eui, struct net_device *dev)
{
        return __ipv6_isatap_ifid(eui, *(__be32 *)dev->dev_addr);
}

static int addrconf_ifid_ip6tnl(u8 *eui, struct net_device *dev)
{
        memcpy(eui, dev->perm_addr, 3);
        memcpy(eui + 5, dev->perm_addr + 3, 3);
        eui[3] = 0xFF;
        eui[4] = 0xFE;
        eui[0] ^= 2;
        return 0;
}

static int ipv6_generate_eui64(u8 *eui, struct net_device *dev)
{
        switch (dev->type) {
        case ARPHRD_ETHER:
        case ARPHRD_FDDI:
                return addrconf_ifid_eui48(eui, dev);
        case ARPHRD_ARCNET:
                return addrconf_ifid_arcnet(eui, dev);
        case ARPHRD_INFINIBAND:
                return addrconf_ifid_infiniband(eui, dev);
        case ARPHRD_SIT:
                return addrconf_ifid_sit(eui, dev);
        case ARPHRD_IPGRE:
                return addrconf_ifid_gre(eui, dev);
        case ARPHRD_6LOWPAN:
                return addrconf_ifid_eui64(eui, dev);
        case ARPHRD_IEEE1394:
                return addrconf_ifid_ieee1394(eui, dev);
        case ARPHRD_TUNNEL6:
                return addrconf_ifid_ip6tnl(eui, dev);
        }
        return -1;
}

static int ipv6_inherit_eui64(u8 *eui, struct inet6_dev *idev)
{
        int err = -1;
        struct inet6_ifaddr *ifp;

        read_lock_bh(&idev->lock);
        list_for_each_entry_reverse(ifp, &idev->addr_list, if_list) {
                if (ifp->scope > IFA_LINK)
                        break;
                if (ifp->scope == IFA_LINK && !(ifp->flags&IFA_F_TENTATIVE)) {
                        memcpy(eui, ifp->addr.s6_addr+8, 8);
                        err = 0;
                        break;
                }
        }
        read_unlock_bh(&idev->lock);
        return err;
}

/* (re)generation of randomized interface identifier (RFC 3041 3.2, 3.5) */
static void ipv6_regen_rndid(struct inet6_dev *idev)
{
regen:
        get_random_bytes(idev->rndid, sizeof(idev->rndid));
        idev->rndid[0] &= ~0x02;

        /*
         * <draft-ietf-ipngwg-temp-addresses-v2-00.txt>:
         * check if generated address is not inappropriate
         *
         *  - Reserved subnet anycast (RFC 2526)
         *      11111101 11....11 1xxxxxxx
         *  - ISATAP (RFC4214) 6.1
         *      00-00-5E-FE-xx-xx-xx-xx
         *  - value 0
         *  - XXX: already assigned to an address on the device
         */
        if (idev->rndid[0] == 0xfd &&
            (idev->rndid[1]&idev->rndid[2]&idev->rndid[3]&idev->rndid[4]&idev->rndid[5]&idev->rndid[6]) == 0xff &&
            (idev->rndid[7]&0x80))
                goto regen;
        if ((idev->rndid[0]|idev->rndid[1]) == 0) {
                if (idev->rndid[2] == 0x5e && idev->rndid[3] == 0xfe)
                        goto regen;
                if ((idev->rndid[2]|idev->rndid[3]|idev->rndid[4]|idev->rndid[5]|idev->rndid[6]|idev->rndid[7]) == 0x00)
                        goto regen;
        }
}

static void  ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpaddr)
{
        if (tmpaddr && memcmp(idev->rndid, &tmpaddr->s6_addr[8], 8) == 0)
                ipv6_regen_rndid(idev);
}

/*
 *      Add prefix route.
 */

static void
addrconf_prefix_route(struct in6_addr *pfx, int plen, struct net_device *dev,
                      unsigned long expires, u32 flags)
{
        struct fib6_config cfg = {
                .fc_table = l3mdev_fib_table(dev) ? : RT6_TABLE_PREFIX,
                .fc_metric = IP6_RT_PRIO_ADDRCONF,
                .fc_ifindex = dev->ifindex,
                .fc_expires = expires,
                .fc_dst_len = plen,
                .fc_flags = RTF_UP | flags,
                .fc_nlinfo.nl_net = dev_net(dev),
                .fc_protocol = RTPROT_KERNEL,
        };

        cfg.fc_dst = *pfx;

        /* Prevent useless cloning on PtP SIT.
           This thing is done here expecting that the whole
           class of non-broadcast devices need not cloning.
         */
#if IS_ENABLED(CONFIG_IPV6_SIT)
        if (dev->type == ARPHRD_SIT && (dev->flags & IFF_POINTOPOINT))
                cfg.fc_flags |= RTF_NONEXTHOP;
#endif

        ip6_route_add(&cfg);
}


static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
                                                  int plen,
                                                  const struct net_device *dev,
                                                  u32 flags, u32 noflags)
{
        struct fib6_node *fn;
        struct rt6_info *rt = NULL;
        struct fib6_table *table;
        u32 tb_id = l3mdev_fib_table(dev) ? : RT6_TABLE_PREFIX;

        table = fib6_get_table(dev_net(dev), tb_id);
        if (!table)
                return NULL;

        read_lock_bh(&table->tb6_lock);
        fn = fib6_locate(&table->tb6_root, pfx, plen, NULL, 0);
        if (!fn)
                goto out;

        noflags |= RTF_CACHE;
        for (rt = fn->leaf; rt; rt = rt->dst.rt6_next) {
                if (rt->dst.dev->ifindex != dev->ifindex)
                        continue;
                if ((rt->rt6i_flags & flags) != flags)
                        continue;
                if ((rt->rt6i_flags & noflags) != 0)
                        continue;
                dst_hold(&rt->dst);
                break;
        }
out:
        read_unlock_bh(&table->tb6_lock);
        return rt;
}


/* Create "default" multicast route to the interface */

static void addrconf_add_mroute(struct net_device *dev)
{
        struct fib6_config cfg = {
                .fc_table = l3mdev_fib_table(dev) ? : RT6_TABLE_LOCAL,
                .fc_metric = IP6_RT_PRIO_ADDRCONF,
                .fc_ifindex = dev->ifindex,
                .fc_dst_len = 8,
                .fc_flags = RTF_UP,
                .fc_nlinfo.nl_net = dev_net(dev),
        };

        ipv6_addr_set(&cfg.fc_dst, htonl(0xFF000000), 0, 0, 0);

        ip6_route_add(&cfg);
}

static struct inet6_dev *addrconf_add_dev(struct net_device *dev)
{
        struct inet6_dev *idev;

        ASSERT_RTNL();

        idev = ipv6_find_idev(dev);
        if (!idev)
                return ERR_PTR(-ENOBUFS);

        if (idev->cnf.disable_ipv6)
                return ERR_PTR(-EACCES);

        /* Add default multicast route */
        if (!(dev->flags & IFF_LOOPBACK) && !netif_is_l3_master(dev))
                addrconf_add_mroute(dev);

        return idev;
}

static void manage_tempaddrs(struct inet6_dev *idev,
                             struct inet6_ifaddr *ifp,
                             __u32 valid_lft, __u32 prefered_lft,
                             bool create, unsigned long now)
{
        u32 flags;
        struct inet6_ifaddr *ift;

        read_lock_bh(&idev->lock);
        /* update all temporary addresses in the list */
        list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
                int age, max_valid, max_prefered;

                if (ifp != ift->ifpub)
                        continue;

                /* RFC 4941 section 3.3:
                 * If a received option will extend the lifetime of a public
                 * address, the lifetimes of temporary addresses should
                 * be extended, subject to the overall constraint that no
                 * temporary addresses should ever remain "valid" or "preferred"
                 * for a time longer than (TEMP_VALID_LIFETIME) or
                 * (TEMP_PREFERRED_LIFETIME - DESYNC_FACTOR), respectively.
                 */
                age = (now - ift->cstamp) / HZ;
                max_valid = idev->cnf.temp_valid_lft - age;
                if (max_valid < 0)
                        max_valid = 0;

                max_prefered = idev->cnf.temp_prefered_lft -
                               idev->desync_factor - age;
                if (max_prefered < 0)
                        max_prefered = 0;

                if (valid_lft > max_valid)
                        valid_lft = max_valid;

                if (prefered_lft > max_prefered)
                        prefered_lft = max_prefered;

                spin_lock(&ift->lock);
                flags = ift->flags;
                ift->valid_lft = valid_lft;
                ift->prefered_lft = prefered_lft;
                ift->tstamp = now;
                if (prefered_lft > 0)
                        ift->flags &= ~IFA_F_DEPRECATED;

                spin_unlock(&ift->lock);
                if (!(flags&IFA_F_TENTATIVE))
                        ipv6_ifa_notify(0, ift);
        }

        if ((create || list_empty(&idev->tempaddr_list)) &&
            idev->cnf.use_tempaddr > 0) {
                /* When a new public address is created as described
                 * in [ADDRCONF], also create a new temporary address.
                 * Also create a temporary address if it's enabled but
                 * no temporary address currently exists.
                 */
                read_unlock_bh(&idev->lock);
                ipv6_create_tempaddr(ifp, NULL);
        } else {
                read_unlock_bh(&idev->lock);
        }
}

static bool is_addr_mode_generate_stable(struct inet6_dev *idev)
{
        return idev->addr_gen_mode == IN6_ADDR_GEN_MODE_STABLE_PRIVACY ||
               idev->addr_gen_mode == IN6_ADDR_GEN_MODE_RANDOM;
}

int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev,
                                 const struct prefix_info *pinfo,
                                 struct inet6_dev *in6_dev,
                                 const struct in6_addr *addr, int addr_type,
                                 u32 addr_flags, bool sllao, bool tokenized,
                                 __u32 valid_lft, u32 prefered_lft)
{
        struct inet6_ifaddr *ifp = ipv6_get_ifaddr(net, addr, dev, 1);
        int create = 0, update_lft = 0;

        if (!ifp && valid_lft) {
                int max_addresses = in6_dev->cnf.max_addresses;

#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
                if (in6_dev->cnf.optimistic_dad &&
                    !net->ipv6.devconf_all->forwarding && sllao)
                        addr_flags |= IFA_F_OPTIMISTIC;
#endif

                /* Do not allow to create too much of autoconfigured
                 * addresses; this would be too easy way to crash kernel.
                 */
                if (!max_addresses ||
                    ipv6_count_addresses(in6_dev) < max_addresses)
                        ifp = ipv6_add_addr(in6_dev, addr, NULL,
                                            pinfo->prefix_len,
                                            addr_type&IPV6_ADDR_SCOPE_MASK,
                                            addr_flags, valid_lft,
                                            prefered_lft);

                if (IS_ERR_OR_NULL(ifp))
                        return -1;

                update_lft = 0;
                create = 1;
                spin_lock_bh(&ifp->lock);
                ifp->flags |= IFA_F_MANAGETEMPADDR;
                ifp->cstamp = jiffies;
                ifp->tokenized = tokenized;
                spin_unlock_bh(&ifp->lock);
                addrconf_dad_start(ifp);
        }

        if (ifp) {
                u32 flags;
                unsigned long now;
                u32 stored_lft;

                /* update lifetime (RFC2462 5.5.3 e) */
                spin_lock_bh(&ifp->lock);
                now = jiffies;
                if (ifp->valid_lft > (now - ifp->tstamp) / HZ)
                        stored_lft = ifp->valid_lft - (now - ifp->tstamp) / HZ;
                else
                        stored_lft = 0;
                if (!update_lft && !create && stored_lft) {
                        const u32 minimum_lft = min_t(u32,
                                stored_lft, MIN_VALID_LIFETIME);
                        valid_lft = max(valid_lft, minimum_lft);

                        /* RFC4862 Section 5.5.3e:
                         * "Note that the preferred lifetime of the
                         *  corresponding address is always reset to
                         *  the Preferred Lifetime in the received
                         *  Prefix Information option, regardless of
                         *  whether the valid lifetime is also reset or
                         *  ignored."
                         *
                         * So we should always update prefered_lft here.
                         */
                        update_lft = 1;
                }

                if (update_lft) {
                        ifp->valid_lft = valid_lft;
                        ifp->prefered_lft = prefered_lft;
                        ifp->tstamp = now;
                        flags = ifp->flags;
                        ifp->flags &= ~IFA_F_DEPRECATED;
                        spin_unlock_bh(&ifp->lock);

                        if (!(flags&IFA_F_TENTATIVE))
                                ipv6_ifa_notify(0, ifp);
                } else
                        spin_unlock_bh(&ifp->lock);

                manage_tempaddrs(in6_dev, ifp, valid_lft, prefered_lft,
                                 create, now);

                in6_ifa_put(ifp);
                addrconf_verify();
        }

        return 0;
}
EXPORT_SYMBOL_GPL(addrconf_prefix_rcv_add_addr);

void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
{
        struct prefix_info *pinfo;
        __u32 valid_lft;
        __u32 prefered_lft;
        int addr_type, err;
        u32 addr_flags = 0;
        struct inet6_dev *in6_dev;
        struct net *net = dev_net(dev);

        pinfo = (struct prefix_info *) opt;

        if (len < sizeof(struct prefix_info)) {
                ADBG("addrconf: prefix option too short\n");
                return;
        }

        /*
         *      Validation checks ([ADDRCONF], page 19)
         */

        addr_type = ipv6_addr_type(&pinfo->prefix);

        if (addr_type & (IPV6_ADDR_MULTICAST|IPV6_ADDR_LINKLOCAL))
                return;

        valid_lft = ntohl(pinfo->valid);
        prefered_lft = ntohl(pinfo->prefered);

        if (prefered_lft > valid_lft) {
                net_warn_ratelimited("addrconf: prefix option has invalid lifetime\n");
                return;
        }

        in6_dev = in6_dev_get(dev);

        if (!in6_dev) {
                net_dbg_ratelimited("addrconf: device %s not configured\n",
                                    dev->name);
                return;
        }

        /*
         *      Two things going on here:
         *      1) Add routes for on-link prefixes
         *      2) Configure prefixes with the auto flag set
         */

        if (pinfo->onlink) {
                struct rt6_info *rt;
                unsigned long rt_expires;

                /* Avoid arithmetic overflow. Really, we could
                 * save rt_expires in seconds, likely valid_lft,
                 * but it would require division in fib gc, that it
                 * not good.
                 */
                if (HZ > USER_HZ)
                        rt_expires = addrconf_timeout_fixup(valid_lft, HZ);
                else
                        rt_expires = addrconf_timeout_fixup(valid_lft, USER_HZ);

                if (addrconf_finite_timeout(rt_expires))
                        rt_expires *= HZ;

                rt = addrconf_get_prefix_route(&pinfo->prefix,
                                               pinfo->prefix_len,
                                               dev,
                                               RTF_ADDRCONF | RTF_PREFIX_RT,
                                               RTF_GATEWAY | RTF_DEFAULT);

                if (rt) {
                        /* Autoconf prefix route */
                        if (valid_lft == 0) {
                                ip6_del_rt(rt);
                                rt = NULL;
                        } else if (addrconf_finite_timeout(rt_expires)) {
                                /* not infinity */
                                rt6_set_expires(rt, jiffies + rt_expires);
                        } else {
                                rt6_clean_expires(rt);
                        }
                } else if (valid_lft) {
                        clock_t expires = 0;
                        int flags = RTF_ADDRCONF | RTF_PREFIX_RT;
                        if (addrconf_finite_timeout(rt_expires)) {
                                /* not infinity */
                                flags |= RTF_EXPIRES;
                                expires = jiffies_to_clock_t(rt_expires);
                        }
                        addrconf_prefix_route(&pinfo->prefix, pinfo->prefix_len,
                                              dev, expires, flags);
                }
                ip6_rt_put(rt);
        }

        /* Try to figure out our local address for this prefix */

        if (pinfo->autoconf && in6_dev->cnf.autoconf) {
                struct in6_addr addr;
                bool tokenized = false, dev_addr_generated = false;

                if (pinfo->prefix_len == 64) {
                        memcpy(&addr, &pinfo->prefix, 8);

                        if (!ipv6_addr_any(&in6_dev->token)) {
                                read_lock_bh(&in6_dev->lock);
                                memcpy(addr.s6_addr + 8,
                                       in6_dev->token.s6_addr + 8, 8);
                                read_unlock_bh(&in6_dev->lock);
                                tokenized = true;
                        } else if (is_addr_mode_generate_stable(in6_dev) &&
                                   !ipv6_generate_stable_address(&addr, 0,
                                                                 in6_dev)) {
                                addr_flags |= IFA_F_STABLE_PRIVACY;
                                goto ok;
                        } else if (ipv6_generate_eui64(addr.s6_addr + 8, dev) &&
                                   ipv6_inherit_eui64(addr.s6_addr + 8, in6_dev)) {
                                goto put;
                        } else {
                                dev_addr_generated = true;
                        }
                        goto ok;
                }
                net_dbg_ratelimited("IPv6 addrconf: prefix with wrong length %d\n",
                                    pinfo->prefix_len);
                goto put;

ok:
                err = addrconf_prefix_rcv_add_addr(net, dev, pinfo, in6_dev,
                                                   &addr, addr_type,
                                                   addr_flags, sllao,
                                                   tokenized, valid_lft,
                                                   prefered_lft);
                if (err)
                        goto put;

                /* Ignore error case here because previous prefix add addr was
                 * successful which will be notified.
                 */
                ndisc_ops_prefix_rcv_add_addr(net, dev, pinfo, in6_dev, &addr,
                                              addr_type, addr_flags, sllao,
                                              tokenized, valid_lft,
                                              prefered_lft,
                                              dev_addr_generated);
        }
        inet6_prefix_notify(RTM_NEWPREFIX, in6_dev, pinfo);
put:
        in6_dev_put(in6_dev);
}

/*
 *      Set destination address.
 *      Special case for SIT interfaces where we create a new "virtual"
 *      device.
 */
int addrconf_set_dstaddr(struct net *net, void __user *arg)
{
        struct in6_ifreq ireq;
        struct net_device *dev;
        int err = -EINVAL;

        rtnl_lock();

        err = -EFAULT;
        if (copy_from_user(&ireq, arg, sizeof(struct in6_ifreq)))
                goto err_exit;

        dev = __dev_get_by_index(net, ireq.ifr6_ifindex);

        err = -ENODEV;
        if (!dev)
                goto err_exit;

#if IS_ENABLED(CONFIG_IPV6_SIT)
        if (dev->type == ARPHRD_SIT) {
                const struct net_device_ops *ops = dev->netdev_ops;
                struct ifreq ifr;
                struct ip_tunnel_parm p;

                err = -EADDRNOTAVAIL;
                if (!(ipv6_addr_type(&ireq.ifr6_addr) & IPV6_ADDR_COMPATv4))
                        goto err_exit;

                memset(&p, 0, sizeof(p));
                p.iph.daddr = ireq.ifr6_addr.s6_addr32[3];
                p.iph.saddr = 0;
                p.iph.version = 4;
                p.iph.ihl = 5;
                p.iph.protocol = IPPROTO_IPV6;
                p.iph.ttl = 64;
                ifr.ifr_ifru.ifru_data = (__force void __user *)&p;

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

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

                if (err == 0) {
                        err = -ENOBUFS;
                        dev = __dev_get_by_name(net, p.name);
                        if (!dev)
                                goto err_exit;
                        err = dev_open(dev);
                }
        }
#endif

err_exit:
        rtnl_unlock();
        return err;
}

static int ipv6_mc_config(struct sock *sk, bool join,
                          const struct in6_addr *addr, int ifindex)
{
        int ret;

        ASSERT_RTNL();

        lock_sock(sk);
        if (join)
                ret = ipv6_sock_mc_join(sk, ifindex, addr);
        else
                ret = ipv6_sock_mc_drop(sk, ifindex, addr);
        release_sock(sk);

        return ret;
}

/*
 *      Manual configuration of address on an interface
 */
static int inet6_addr_add(struct net *net, int ifindex,
                          const struct in6_addr *pfx,
                          const struct in6_addr *peer_pfx,
                          unsigned int plen, __u32 ifa_flags,
                          __u32 prefered_lft, __u32 valid_lft)
{
        struct inet6_ifaddr *ifp;
        struct inet6_dev *idev;
        struct net_device *dev;
        unsigned long timeout;
        clock_t expires;
        int scope;
        u32 flags;

        ASSERT_RTNL();

        if (plen > 128)
                return -EINVAL;

        /* check the lifetime */
        if (!valid_lft || prefered_lft > valid_lft)
                return -EINVAL;

        if (ifa_flags & IFA_F_MANAGETEMPADDR && plen != 64)
                return -EINVAL;

        dev = __dev_get_by_index(net, ifindex);
        if (!dev)
                return -ENODEV;

        idev = addrconf_add_dev(dev);
        if (IS_ERR(idev))
                return PTR_ERR(idev);

        if (ifa_flags & IFA_F_MCAUTOJOIN) {
                int ret = ipv6_mc_config(net->ipv6.mc_autojoin_sk,
                                         true, pfx, ifindex);

                if (ret < 0)
                        return ret;
        }

        scope = ipv6_addr_scope(pfx);

        timeout = addrconf_timeout_fixup(valid_lft, HZ);
        if (addrconf_finite_timeout(timeout)) {
                expires = jiffies_to_clock_t(timeout * HZ);
                valid_lft = timeout;
                flags = RTF_EXPIRES;
        } else {
                expires = 0;
                flags = 0;
                ifa_flags |= IFA_F_PERMANENT;
        }

        timeout = addrconf_timeout_fixup(prefered_lft, HZ);
        if (addrconf_finite_timeout(timeout)) {
                if (timeout == 0)
                        ifa_flags |= IFA_F_DEPRECATED;
                prefered_lft = timeout;
        }

        ifp = ipv6_add_addr(idev, pfx, peer_pfx, plen, scope, ifa_flags,
                            valid_lft, prefered_lft);

        if (!IS_ERR(ifp)) {
                if (!(ifa_flags & IFA_F_NOPREFIXROUTE)) {
                        addrconf_prefix_route(&ifp->addr, ifp->prefix_len, dev,
                                              expires, flags);
                }

                /*
                 * Note that section 3.1 of RFC 4429 indicates
                 * that the Optimistic flag should not be set for
                 * manually configured addresses
                 */
                addrconf_dad_start(ifp);
                if (ifa_flags & IFA_F_MANAGETEMPADDR)
                        manage_tempaddrs(idev, ifp, valid_lft, prefered_lft,
                                         true, jiffies);
                in6_ifa_put(ifp);
                addrconf_verify_rtnl();
                return 0;
        } else if (ifa_flags & IFA_F_MCAUTOJOIN) {
                ipv6_mc_config(net->ipv6.mc_autojoin_sk,
                               false, pfx, ifindex);
        }

        return PTR_ERR(ifp);
}

static int inet6_addr_del(struct net *net, int ifindex, u32 ifa_flags,
                          const struct in6_addr *pfx, unsigned int plen)
{
        struct inet6_ifaddr *ifp;
        struct inet6_dev *idev;
        struct net_device *dev;

        if (plen > 128)
                return -EINVAL;

        dev = __dev_get_by_index(net, ifindex);
        if (!dev)
                return -ENODEV;

        idev = __in6_dev_get(dev);
        if (!idev)
                return -ENXIO;

        read_lock_bh(&idev->lock);
        list_for_each_entry(ifp, &idev->addr_list, if_list) {
                if (ifp->prefix_len == plen &&
                    ipv6_addr_equal(pfx, &ifp->addr)) {
                        in6_ifa_hold(ifp);
                        read_unlock_bh(&idev->lock);

                        if (!(ifp->flags & IFA_F_TEMPORARY) &&
                            (ifa_flags & IFA_F_MANAGETEMPADDR))
                                manage_tempaddrs(idev, ifp, 0, 0, false,
                                                 jiffies);
                        ipv6_del_addr(ifp);
                        addrconf_verify_rtnl();
                        if (ipv6_addr_is_multicast(pfx)) {
                                ipv6_mc_config(net->ipv6.mc_autojoin_sk,
                                               false, pfx, dev->ifindex);
                        }
                        return 0;
                }
        }
        read_unlock_bh(&idev->lock);
        return -EADDRNOTAVAIL;
}


int addrconf_add_ifaddr(struct net *net, void __user *arg)
{
        struct in6_ifreq ireq;
        int err;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        if (copy_from_user(&ireq, arg, sizeof(struct in6_ifreq)))
                return -EFAULT;

        rtnl_lock();
        err = inet6_addr_add(net, ireq.ifr6_ifindex, &ireq.ifr6_addr, NULL,
                             ireq.ifr6_prefixlen, IFA_F_PERMANENT,
                             INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);
        rtnl_unlock();
        return err;
}

int addrconf_del_ifaddr(struct net *net, void __user *arg)
{
        struct in6_ifreq ireq;
        int err;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        if (copy_from_user(&ireq, arg, sizeof(struct in6_ifreq)))
                return -EFAULT;

        rtnl_lock();
        err = inet6_addr_del(net, ireq.ifr6_ifindex, 0, &ireq.ifr6_addr,
                             ireq.ifr6_prefixlen);
        rtnl_unlock();
        return err;
}

static void add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
                     int plen, int scope)
{
        struct inet6_ifaddr *ifp;

        ifp = ipv6_add_addr(idev, addr, NULL, plen,
                            scope, IFA_F_PERMANENT,
                            INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);
        if (!IS_ERR(ifp)) {
                spin_lock_bh(&ifp->lock);
                ifp->flags &= ~IFA_F_TENTATIVE;
                spin_unlock_bh(&ifp->lock);
                rt_genid_bump_ipv6(dev_net(idev->dev));
                ipv6_ifa_notify(RTM_NEWADDR, ifp);
                in6_ifa_put(ifp);
        }
}

#if IS_ENABLED(CONFIG_IPV6_SIT)
static void sit_add_v4_addrs(struct inet6_dev *idev)
{
        struct in6_addr addr;
        struct net_device *dev;
        struct net *net = dev_net(idev->dev);
        int scope, plen;
        u32 pflags = 0;

        ASSERT_RTNL();

        memset(&addr, 0, sizeof(struct in6_addr));
        memcpy(&addr.s6_addr32[3], idev->dev->dev_addr, 4);

        if (idev->dev->flags&IFF_POINTOPOINT) {
                addr.s6_addr32[0] = htonl(0xfe800000);
                scope = IFA_LINK;
                plen = 64;
        } else {
                scope = IPV6_ADDR_COMPATv4;
                plen = 96;
                pflags |= RTF_NONEXTHOP;
        }

        if (addr.s6_addr32[3]) {
                add_addr(idev, &addr, plen, scope);
                addrconf_prefix_route(&addr, plen, idev->dev, 0, pflags);
                return;
        }

        for_each_netdev(net, dev) {
                struct in_device *in_dev = __in_dev_get_rtnl(dev);
                if (in_dev && (dev->flags & IFF_UP)) {
                        struct in_ifaddr *ifa;

                        int flag = scope;

                        for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {

                                addr.s6_addr32[3] = ifa->ifa_local;

                                if (ifa->ifa_scope == RT_SCOPE_LINK)
                                        continue;
                                if (ifa->ifa_scope >= RT_SCOPE_HOST) {
                                        if (idev->dev->flags&IFF_POINTOPOINT)
                                                continue;
                                        flag |= IFA_HOST;
                                }

                                add_addr(idev, &addr, plen, flag);
                                addrconf_prefix_route(&addr, plen, idev->dev, 0,
                                                      pflags);
                        }
                }
        }
}
#endif

static void init_loopback(struct net_device *dev)
{
        struct inet6_dev  *idev;
        struct net_device *sp_dev;
        struct inet6_ifaddr *sp_ifa;
        struct rt6_info *sp_rt;

        /* ::1 */

        ASSERT_RTNL();

        idev = ipv6_find_idev(dev);
        if (!idev) {
                pr_debug("%s: add_dev failed\n", __func__);
                return;
        }

        add_addr(idev, &in6addr_loopback, 128, IFA_HOST);

        /* Add routes to other interface's IPv6 addresses */
        for_each_netdev(dev_net(dev), sp_dev) {
                if (!strcmp(sp_dev->name, dev->name))
                        continue;

                idev = __in6_dev_get(sp_dev);
                if (!idev)
                        continue;

                read_lock_bh(&idev->lock);
                list_for_each_entry(sp_ifa, &idev->addr_list, if_list) {

                        if (sp_ifa->flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE))
                                continue;

                        if (sp_ifa->rt) {
                                /* This dst has been added to garbage list when