Merge branch 'for-next' of git://gitorious.org/kernel-hsi/kernel-hsi

[mirror_ubuntu-artful-kernel.git] / net / ipv4 / fib_frontend.c

/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              IPv4 Forwarding Information Base: FIB frontend.
 *
 * Authors:     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.
 */

#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/capability.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/if_addr.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>

#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/ip_fib.h>
#include <net/rtnetlink.h>
#include <net/xfrm.h>

#ifndef CONFIG_IP_MULTIPLE_TABLES

static int __net_init fib4_rules_init(struct net *net)
{
        struct fib_table *local_table, *main_table;

        local_table = fib_trie_table(RT_TABLE_LOCAL);
        if (local_table == NULL)
                return -ENOMEM;

        main_table  = fib_trie_table(RT_TABLE_MAIN);
        if (main_table == NULL)
                goto fail;

        hlist_add_head_rcu(&local_table->tb_hlist,
                                &net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX]);
        hlist_add_head_rcu(&main_table->tb_hlist,
                                &net->ipv4.fib_table_hash[TABLE_MAIN_INDEX]);
        return 0;

fail:
        kfree(local_table);
        return -ENOMEM;
}
#else

struct fib_table *fib_new_table(struct net *net, u32 id)
{
        struct fib_table *tb;
        unsigned int h;

        if (id == 0)
                id = RT_TABLE_MAIN;
        tb = fib_get_table(net, id);
        if (tb)
                return tb;

        tb = fib_trie_table(id);
        if (!tb)
                return NULL;
        h = id & (FIB_TABLE_HASHSZ - 1);
        hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);
        return tb;
}

struct fib_table *fib_get_table(struct net *net, u32 id)
{
        struct fib_table *tb;
        struct hlist_node *node;
        struct hlist_head *head;
        unsigned int h;

        if (id == 0)
                id = RT_TABLE_MAIN;
        h = id & (FIB_TABLE_HASHSZ - 1);

        rcu_read_lock();
        head = &net->ipv4.fib_table_hash[h];
        hlist_for_each_entry_rcu(tb, node, head, tb_hlist) {
                if (tb->tb_id == id) {
                        rcu_read_unlock();
                        return tb;
                }
        }
        rcu_read_unlock();
        return NULL;
}
#endif /* CONFIG_IP_MULTIPLE_TABLES */

static void fib_flush(struct net *net)
{
        int flushed = 0;
        struct fib_table *tb;
        struct hlist_node *node;
        struct hlist_head *head;
        unsigned int h;

        for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
                head = &net->ipv4.fib_table_hash[h];
                hlist_for_each_entry(tb, node, head, tb_hlist)
                        flushed += fib_table_flush(tb);
        }

        if (flushed)
                rt_cache_flush(net, -1);
}

/*
 * Find address type as if only "dev" was present in the system. If
 * on_dev is NULL then all interfaces are taken into consideration.
 */
static inline unsigned __inet_dev_addr_type(struct net *net,
                                            const struct net_device *dev,
                                            __be32 addr)
{
        struct flowi4           fl4 = { .daddr = addr };
        struct fib_result       res;
        unsigned ret = RTN_BROADCAST;
        struct fib_table *local_table;

        if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
                return RTN_BROADCAST;
        if (ipv4_is_multicast(addr))
                return RTN_MULTICAST;

#ifdef CONFIG_IP_MULTIPLE_TABLES
        res.r = NULL;
#endif

        local_table = fib_get_table(net, RT_TABLE_LOCAL);
        if (local_table) {
                ret = RTN_UNICAST;
                rcu_read_lock();
                if (!fib_table_lookup(local_table, &fl4, &res, FIB_LOOKUP_NOREF)) {
                        if (!dev || dev == res.fi->fib_dev)
                                ret = res.type;
                }
                rcu_read_unlock();
        }
        return ret;
}

unsigned int inet_addr_type(struct net *net, __be32 addr)
{
        return __inet_dev_addr_type(net, NULL, addr);
}
EXPORT_SYMBOL(inet_addr_type);

unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
                                __be32 addr)
{
        return __inet_dev_addr_type(net, dev, addr);
}
EXPORT_SYMBOL(inet_dev_addr_type);

/* Given (packet source, input interface) and optional (dst, oif, tos):
 * - (main) check, that source is valid i.e. not broadcast or our local
 *   address.
 * - figure out what "logical" interface this packet arrived
 *   and calculate "specific destination" address.
 * - check, that packet arrived from expected physical interface.
 * called with rcu_read_lock()
 */
int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, u8 tos,
                        int oif, struct net_device *dev, __be32 *spec_dst,
                        u32 *itag)
{
        struct in_device *in_dev;
        struct flowi4 fl4;
        struct fib_result res;
        int no_addr, rpf, accept_local;
        bool dev_match;
        int ret;
        struct net *net;

        fl4.flowi4_oif = 0;
        fl4.flowi4_iif = oif;
        fl4.daddr = src;
        fl4.saddr = dst;
        fl4.flowi4_tos = tos;
        fl4.flowi4_scope = RT_SCOPE_UNIVERSE;

        no_addr = rpf = accept_local = 0;
        in_dev = __in_dev_get_rcu(dev);
        if (in_dev) {
                no_addr = in_dev->ifa_list == NULL;

                /* Ignore rp_filter for packets protected by IPsec. */
                rpf = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(in_dev);

                accept_local = IN_DEV_ACCEPT_LOCAL(in_dev);
                fl4.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0;
        }

        if (in_dev == NULL)
                goto e_inval;

        net = dev_net(dev);
        if (fib_lookup(net, &fl4, &res))
                goto last_resort;
        if (res.type != RTN_UNICAST) {
                if (res.type != RTN_LOCAL || !accept_local)
                        goto e_inval;
        }
        *spec_dst = FIB_RES_PREFSRC(net, res);
        fib_combine_itag(itag, &res);
        dev_match = false;

#ifdef CONFIG_IP_ROUTE_MULTIPATH
        for (ret = 0; ret < res.fi->fib_nhs; ret++) {
                struct fib_nh *nh = &res.fi->fib_nh[ret];

                if (nh->nh_dev == dev) {
                        dev_match = true;
                        break;
                }
        }
#else
        if (FIB_RES_DEV(res) == dev)
                dev_match = true;
#endif
        if (dev_match) {
                ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
                return ret;
        }
        if (no_addr)
                goto last_resort;
        if (rpf == 1)
                goto e_rpf;
        fl4.flowi4_oif = dev->ifindex;

        ret = 0;
        if (fib_lookup(net, &fl4, &res) == 0) {
                if (res.type == RTN_UNICAST) {
                        *spec_dst = FIB_RES_PREFSRC(net, res);
                        ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
                }
        }
        return ret;

last_resort:
        if (rpf)
                goto e_rpf;
        *spec_dst = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
        *itag = 0;
        return 0;

e_inval:
        return -EINVAL;
e_rpf:
        return -EXDEV;
}

static inline __be32 sk_extract_addr(struct sockaddr *addr)
{
        return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
}

static int put_rtax(struct nlattr *mx, int len, int type, u32 value)
{
        struct nlattr *nla;

        nla = (struct nlattr *) ((char *) mx + len);
        nla->nla_type = type;
        nla->nla_len = nla_attr_size(4);
        *(u32 *) nla_data(nla) = value;

        return len + nla_total_size(4);
}

static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,
                                 struct fib_config *cfg)
{
        __be32 addr;
        int plen;

        memset(cfg, 0, sizeof(*cfg));
        cfg->fc_nlinfo.nl_net = net;

        if (rt->rt_dst.sa_family != AF_INET)
                return -EAFNOSUPPORT;

        /*
         * Check mask for validity:
         * a) it must be contiguous.
         * b) destination must have all host bits clear.
         * c) if application forgot to set correct family (AF_INET),
         *    reject request unless it is absolutely clear i.e.
         *    both family and mask are zero.
         */
        plen = 32;
        addr = sk_extract_addr(&rt->rt_dst);
        if (!(rt->rt_flags & RTF_HOST)) {
                __be32 mask = sk_extract_addr(&rt->rt_genmask);

                if (rt->rt_genmask.sa_family != AF_INET) {
                        if (mask || rt->rt_genmask.sa_family)
                                return -EAFNOSUPPORT;
                }

                if (bad_mask(mask, addr))
                        return -EINVAL;

                plen = inet_mask_len(mask);
        }

        cfg->fc_dst_len = plen;
        cfg->fc_dst = addr;

        if (cmd != SIOCDELRT) {
                cfg->fc_nlflags = NLM_F_CREATE;
                cfg->fc_protocol = RTPROT_BOOT;
        }

        if (rt->rt_metric)
                cfg->fc_priority = rt->rt_metric - 1;

        if (rt->rt_flags & RTF_REJECT) {
                cfg->fc_scope = RT_SCOPE_HOST;
                cfg->fc_type = RTN_UNREACHABLE;
                return 0;
        }

        cfg->fc_scope = RT_SCOPE_NOWHERE;
        cfg->fc_type = RTN_UNICAST;

        if (rt->rt_dev) {
                char *colon;
                struct net_device *dev;
                char devname[IFNAMSIZ];

                if (copy_from_user(devname, rt->rt_dev, IFNAMSIZ-1))
                        return -EFAULT;

                devname[IFNAMSIZ-1] = 0;
                colon = strchr(devname, ':');
                if (colon)
                        *colon = 0;
                dev = __dev_get_by_name(net, devname);
                if (!dev)
                        return -ENODEV;
                cfg->fc_oif = dev->ifindex;
                if (colon) {
                        struct in_ifaddr *ifa;
                        struct in_device *in_dev = __in_dev_get_rtnl(dev);
                        if (!in_dev)
                                return -ENODEV;
                        *colon = ':';
                        for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next)
                                if (strcmp(ifa->ifa_label, devname) == 0)
                                        break;
                        if (ifa == NULL)
                                return -ENODEV;
                        cfg->fc_prefsrc = ifa->ifa_local;
                }
        }

        addr = sk_extract_addr(&rt->rt_gateway);
        if (rt->rt_gateway.sa_family == AF_INET && addr) {
                cfg->fc_gw = addr;
                if (rt->rt_flags & RTF_GATEWAY &&
                    inet_addr_type(net, addr) == RTN_UNICAST)
                        cfg->fc_scope = RT_SCOPE_UNIVERSE;
        }

        if (cmd == SIOCDELRT)
                return 0;

        if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw)
                return -EINVAL;

        if (cfg->fc_scope == RT_SCOPE_NOWHERE)
                cfg->fc_scope = RT_SCOPE_LINK;

        if (rt->rt_flags & (RTF_MTU | RTF_WINDOW | RTF_IRTT)) {
                struct nlattr *mx;
                int len = 0;

                mx = kzalloc(3 * nla_total_size(4), GFP_KERNEL);
                if (mx == NULL)
                        return -ENOMEM;

                if (rt->rt_flags & RTF_MTU)
                        len = put_rtax(mx, len, RTAX_ADVMSS, rt->rt_mtu - 40);

                if (rt->rt_flags & RTF_WINDOW)
                        len = put_rtax(mx, len, RTAX_WINDOW, rt->rt_window);

                if (rt->rt_flags & RTF_IRTT)
                        len = put_rtax(mx, len, RTAX_RTT, rt->rt_irtt << 3);

                cfg->fc_mx = mx;
                cfg->fc_mx_len = len;
        }

        return 0;
}

/*
 * Handle IP routing ioctl calls.
 * These are used to manipulate the routing tables
 */
int ip_rt_ioctl(struct net *net, unsigned int cmd, void __user *arg)
{
        struct fib_config cfg;
        struct rtentry rt;
        int err;

        switch (cmd) {
        case SIOCADDRT:         /* Add a route */
        case SIOCDELRT:         /* Delete a route */
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;

                if (copy_from_user(&rt, arg, sizeof(rt)))
                        return -EFAULT;

                rtnl_lock();
                err = rtentry_to_fib_config(net, cmd, &rt, &cfg);
                if (err == 0) {
                        struct fib_table *tb;

                        if (cmd == SIOCDELRT) {
                                tb = fib_get_table(net, cfg.fc_table);
                                if (tb)
                                        err = fib_table_delete(tb, &cfg);
                                else
                                        err = -ESRCH;
                        } else {
                                tb = fib_new_table(net, cfg.fc_table);
                                if (tb)
                                        err = fib_table_insert(tb, &cfg);
                                else
                                        err = -ENOBUFS;
                        }

                        /* allocated by rtentry_to_fib_config() */
                        kfree(cfg.fc_mx);
                }
                rtnl_unlock();
                return err;
        }
        return -EINVAL;
}

const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
        [RTA_DST]               = { .type = NLA_U32 },
        [RTA_SRC]               = { .type = NLA_U32 },
        [RTA_IIF]               = { .type = NLA_U32 },
        [RTA_OIF]               = { .type = NLA_U32 },
        [RTA_GATEWAY]           = { .type = NLA_U32 },
        [RTA_PRIORITY]          = { .type = NLA_U32 },
        [RTA_PREFSRC]           = { .type = NLA_U32 },
        [RTA_METRICS]           = { .type = NLA_NESTED },
        [RTA_MULTIPATH]         = { .len = sizeof(struct rtnexthop) },
        [RTA_FLOW]              = { .type = NLA_U32 },
};

static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
                             struct nlmsghdr *nlh, struct fib_config *cfg)
{
        struct nlattr *attr;
        int err, remaining;
        struct rtmsg *rtm;

        err = nlmsg_validate(nlh, sizeof(*rtm), RTA_MAX, rtm_ipv4_policy);
        if (err < 0)
                goto errout;

        memset(cfg, 0, sizeof(*cfg));

        rtm = nlmsg_data(nlh);
        cfg->fc_dst_len = rtm->rtm_dst_len;
        cfg->fc_tos = rtm->rtm_tos;
        cfg->fc_table = rtm->rtm_table;
        cfg->fc_protocol = rtm->rtm_protocol;
        cfg->fc_scope = rtm->rtm_scope;
        cfg->fc_type = rtm->rtm_type;
        cfg->fc_flags = rtm->rtm_flags;
        cfg->fc_nlflags = nlh->nlmsg_flags;

        cfg->fc_nlinfo.pid = NETLINK_CB(skb).pid;
        cfg->fc_nlinfo.nlh = nlh;
        cfg->fc_nlinfo.nl_net = net;

        if (cfg->fc_type > RTN_MAX) {
                err = -EINVAL;
                goto errout;
        }

        nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
                switch (nla_type(attr)) {
                case RTA_DST:
                        cfg->fc_dst = nla_get_be32(attr);
                        break;
                case RTA_OIF:
                        cfg->fc_oif = nla_get_u32(attr);
                        break;
                case RTA_GATEWAY:
                        cfg->fc_gw = nla_get_be32(attr);
                        break;
                case RTA_PRIORITY:
                        cfg->fc_priority = nla_get_u32(attr);
                        break;
                case RTA_PREFSRC:
                        cfg->fc_prefsrc = nla_get_be32(attr);
                        break;
                case RTA_METRICS:
                        cfg->fc_mx = nla_data(attr);
                        cfg->fc_mx_len = nla_len(attr);
                        break;
                case RTA_MULTIPATH:
                        cfg->fc_mp = nla_data(attr);
                        cfg->fc_mp_len = nla_len(attr);
                        break;
                case RTA_FLOW:
                        cfg->fc_flow = nla_get_u32(attr);
                        break;
                case RTA_TABLE:
                        cfg->fc_table = nla_get_u32(attr);
                        break;
                }
        }

        return 0;
errout:
        return err;
}

static int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct fib_config cfg;
        struct fib_table *tb;
        int err;

        err = rtm_to_fib_config(net, skb, nlh, &cfg);
        if (err < 0)
                goto errout;

        tb = fib_get_table(net, cfg.fc_table);
        if (tb == NULL) {
                err = -ESRCH;
                goto errout;
        }

        err = fib_table_delete(tb, &cfg);
errout:
        return err;
}

static int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct fib_config cfg;
        struct fib_table *tb;
        int err;

        err = rtm_to_fib_config(net, skb, nlh, &cfg);
        if (err < 0)
                goto errout;

        tb = fib_new_table(net, cfg.fc_table);
        if (tb == NULL) {
                err = -ENOBUFS;
                goto errout;
        }

        err = fib_table_insert(tb, &cfg);
errout:
        return err;
}

static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        unsigned int h, s_h;
        unsigned int e = 0, s_e;
        struct fib_table *tb;
        struct hlist_node *node;
        struct hlist_head *head;
        int dumped = 0;

        if (nlmsg_len(cb->nlh) >= sizeof(struct rtmsg) &&
            ((struct rtmsg *) nlmsg_data(cb->nlh))->rtm_flags & RTM_F_CLONED)
                return ip_rt_dump(skb, cb);

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

        for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
                e = 0;
                head = &net->ipv4.fib_table_hash[h];
                hlist_for_each_entry(tb, node, head, tb_hlist) {
                        if (e < s_e)
                                goto next;
                        if (dumped)
                                memset(&cb->args[2], 0, sizeof(cb->args) -
                                                 2 * sizeof(cb->args[0]));
                        if (fib_table_dump(tb, skb, cb) < 0)
                                goto out;
                        dumped = 1;
next:
                        e++;
                }
        }
out:
        cb->args[1] = e;
        cb->args[0] = h;

        return skb->len;
}

/* Prepare and feed intra-kernel routing request.
 * Really, it should be netlink message, but :-( netlink
 * can be not configured, so that we feed it directly
 * to fib engine. It is legal, because all events occur
 * only when netlink is already locked.
 */
static void fib_magic(int cmd, int type, __be32 dst, int dst_len, struct in_ifaddr *ifa)
{
        struct net *net = dev_net(ifa->ifa_dev->dev);
        struct fib_table *tb;
        struct fib_config cfg = {
                .fc_protocol = RTPROT_KERNEL,
                .fc_type = type,
                .fc_dst = dst,
                .fc_dst_len = dst_len,
                .fc_prefsrc = ifa->ifa_local,
                .fc_oif = ifa->ifa_dev->dev->ifindex,
                .fc_nlflags = NLM_F_CREATE | NLM_F_APPEND,
                .fc_nlinfo = {
                        .nl_net = net,
                },
        };

        if (type == RTN_UNICAST)
                tb = fib_new_table(net, RT_TABLE_MAIN);
        else
                tb = fib_new_table(net, RT_TABLE_LOCAL);

        if (tb == NULL)
                return;

        cfg.fc_table = tb->tb_id;

        if (type != RTN_LOCAL)
                cfg.fc_scope = RT_SCOPE_LINK;
        else
                cfg.fc_scope = RT_SCOPE_HOST;

        if (cmd == RTM_NEWROUTE)
                fib_table_insert(tb, &cfg);
        else
                fib_table_delete(tb, &cfg);
}

void fib_add_ifaddr(struct in_ifaddr *ifa)
{
        struct in_device *in_dev = ifa->ifa_dev;
        struct net_device *dev = in_dev->dev;
        struct in_ifaddr *prim = ifa;
        __be32 mask = ifa->ifa_mask;
        __be32 addr = ifa->ifa_local;
        __be32 prefix = ifa->ifa_address & mask;

        if (ifa->ifa_flags & IFA_F_SECONDARY) {
                prim = inet_ifa_byprefix(in_dev, prefix, mask);
                if (prim == NULL) {
                        pr_warn("%s: bug: prim == NULL\n", __func__);
                        return;
                }
        }

        fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim);

        if (!(dev->flags & IFF_UP))
                return;

        /* Add broadcast address, if it is explicitly assigned. */
        if (ifa->ifa_broadcast && ifa->ifa_broadcast != htonl(0xFFFFFFFF))
                fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32, prim);

        if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&
            (prefix != addr || ifa->ifa_prefixlen < 32)) {
                fib_magic(RTM_NEWROUTE,
                          dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
                          prefix, ifa->ifa_prefixlen, prim);

                /* Add network specific broadcasts, when it takes a sense */
                if (ifa->ifa_prefixlen < 31) {
                        fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32, prim);
                        fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
                                  32, prim);
                }
        }
}

/* Delete primary or secondary address.
 * Optionally, on secondary address promotion consider the addresses
 * from subnet iprim as deleted, even if they are in device list.
 * In this case the secondary ifa can be in device list.
 */
void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)
{
        struct in_device *in_dev = ifa->ifa_dev;
        struct net_device *dev = in_dev->dev;
        struct in_ifaddr *ifa1;
        struct in_ifaddr *prim = ifa, *prim1 = NULL;
        __be32 brd = ifa->ifa_address | ~ifa->ifa_mask;
        __be32 any = ifa->ifa_address & ifa->ifa_mask;
#define LOCAL_OK        1
#define BRD_OK          2
#define BRD0_OK         4
#define BRD1_OK         8
        unsigned ok = 0;
        int subnet = 0;         /* Primary network */
        int gone = 1;           /* Address is missing */
        int same_prefsrc = 0;   /* Another primary with same IP */

        if (ifa->ifa_flags & IFA_F_SECONDARY) {
                prim = inet_ifa_byprefix(in_dev, any, ifa->ifa_mask);
                if (prim == NULL) {
                        pr_warn("%s: bug: prim == NULL\n", __func__);
                        return;
                }
                if (iprim && iprim != prim) {
                        pr_warn("%s: bug: iprim != prim\n", __func__);
                        return;
                }
        } else if (!ipv4_is_zeronet(any) &&
                   (any != ifa->ifa_local || ifa->ifa_prefixlen < 32)) {
                fib_magic(RTM_DELROUTE,
                          dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
                          any, ifa->ifa_prefixlen, prim);
                subnet = 1;
        }

        /* Deletion is more complicated than add.
         * We should take care of not to delete too much :-)
         *
         * Scan address list to be sure that addresses are really gone.
         */

        for (ifa1 = in_dev->ifa_list; ifa1; ifa1 = ifa1->ifa_next) {
                if (ifa1 == ifa) {
                        /* promotion, keep the IP */
                        gone = 0;
                        continue;
                }
                /* Ignore IFAs from our subnet */
                if (iprim && ifa1->ifa_mask == iprim->ifa_mask &&
                    inet_ifa_match(ifa1->ifa_address, iprim))
                        continue;

                /* Ignore ifa1 if it uses different primary IP (prefsrc) */
                if (ifa1->ifa_flags & IFA_F_SECONDARY) {
                        /* Another address from our subnet? */
                        if (ifa1->ifa_mask == prim->ifa_mask &&
                            inet_ifa_match(ifa1->ifa_address, prim))
                                prim1 = prim;
                        else {
                                /* We reached the secondaries, so
                                 * same_prefsrc should be determined.
                                 */
                                if (!same_prefsrc)
                                        continue;
                                /* Search new prim1 if ifa1 is not
                                 * using the current prim1
                                 */
                                if (!prim1 ||
                                    ifa1->ifa_mask != prim1->ifa_mask ||
                                    !inet_ifa_match(ifa1->ifa_address, prim1))
                                        prim1 = inet_ifa_byprefix(in_dev,
                                                        ifa1->ifa_address,
                                                        ifa1->ifa_mask);
                                if (!prim1)
                                        continue;
                                if (prim1->ifa_local != prim->ifa_local)
                                        continue;
                        }
                } else {
                        if (prim->ifa_local != ifa1->ifa_local)
                                continue;
                        prim1 = ifa1;
                        if (prim != prim1)
                                same_prefsrc = 1;
                }
                if (ifa->ifa_local == ifa1->ifa_local)
                        ok |= LOCAL_OK;
                if (ifa->ifa_broadcast == ifa1->ifa_broadcast)
                        ok |= BRD_OK;
                if (brd == ifa1->ifa_broadcast)
                        ok |= BRD1_OK;
                if (any == ifa1->ifa_broadcast)
                        ok |= BRD0_OK;
                /* primary has network specific broadcasts */
                if (prim1 == ifa1 && ifa1->ifa_prefixlen < 31) {
                        __be32 brd1 = ifa1->ifa_address | ~ifa1->ifa_mask;
                        __be32 any1 = ifa1->ifa_address & ifa1->ifa_mask;

                        if (!ipv4_is_zeronet(any1)) {
                                if (ifa->ifa_broadcast == brd1 ||
                                    ifa->ifa_broadcast == any1)
                                        ok |= BRD_OK;
                                if (brd == brd1 || brd == any1)
                                        ok |= BRD1_OK;
                                if (any == brd1 || any == any1)
                                        ok |= BRD0_OK;
                        }
                }
        }

        if (!(ok & BRD_OK))
                fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32, prim);
        if (subnet && ifa->ifa_prefixlen < 31) {
                if (!(ok & BRD1_OK))
                        fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32, prim);
                if (!(ok & BRD0_OK))
                        fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32, prim);
        }
        if (!(ok & LOCAL_OK)) {
                fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim);

                /* Check, that this local address finally disappeared. */
                if (gone &&
                    inet_addr_type(dev_net(dev), ifa->ifa_local) != RTN_LOCAL) {
                        /* And the last, but not the least thing.
                         * We must flush stray FIB entries.
                         *
                         * First of all, we scan fib_info list searching
                         * for stray nexthop entries, then ignite fib_flush.
                         */
                        if (fib_sync_down_addr(dev_net(dev), ifa->ifa_local))
                                fib_flush(dev_net(dev));
                }
        }
#undef LOCAL_OK
#undef BRD_OK
#undef BRD0_OK
#undef BRD1_OK
}

static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb)
{

        struct fib_result       res;
        struct flowi4           fl4 = {
                .flowi4_mark = frn->fl_mark,
                .daddr = frn->fl_addr,
                .flowi4_tos = frn->fl_tos,
                .flowi4_scope = frn->fl_scope,
        };

#ifdef CONFIG_IP_MULTIPLE_TABLES
        res.r = NULL;
#endif

        frn->err = -ENOENT;
        if (tb) {
                local_bh_disable();

                frn->tb_id = tb->tb_id;
                rcu_read_lock();
                frn->err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);

                if (!frn->err) {
                        frn->prefixlen = res.prefixlen;
                        frn->nh_sel = res.nh_sel;
                        frn->type = res.type;
                        frn->scope = res.scope;
                }
                rcu_read_unlock();
                local_bh_enable();
        }
}

static void nl_fib_input(struct sk_buff *skb)
{
        struct net *net;
        struct fib_result_nl *frn;
        struct nlmsghdr *nlh;
        struct fib_table *tb;
        u32 pid;

        net = sock_net(skb->sk);
        nlh = nlmsg_hdr(skb);
        if (skb->len < NLMSG_SPACE(0) || skb->len < nlh->nlmsg_len ||
            nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*frn)))
                return;

        skb = skb_clone(skb, GFP_KERNEL);
        if (skb == NULL)
                return;
        nlh = nlmsg_hdr(skb);

        frn = (struct fib_result_nl *) NLMSG_DATA(nlh);
        tb = fib_get_table(net, frn->tb_id_in);

        nl_fib_lookup(frn, tb);

        pid = NETLINK_CB(skb).pid;      /* pid of sending process */
        NETLINK_CB(skb).pid = 0;        /* from kernel */
        NETLINK_CB(skb).dst_group = 0;  /* unicast */
        netlink_unicast(net->ipv4.fibnl, skb, pid, MSG_DONTWAIT);
}

static int __net_init nl_fib_lookup_init(struct net *net)
{
        struct sock *sk;
        sk = netlink_kernel_create(net, NETLINK_FIB_LOOKUP, 0,
                                   nl_fib_input, NULL, THIS_MODULE);
        if (sk == NULL)
                return -EAFNOSUPPORT;
        net->ipv4.fibnl = sk;
        return 0;
}

static void nl_fib_lookup_exit(struct net *net)
{
        netlink_kernel_release(net->ipv4.fibnl);
        net->ipv4.fibnl = NULL;
}

static void fib_disable_ip(struct net_device *dev, int force, int delay)
{
        if (fib_sync_down_dev(dev, force))
                fib_flush(dev_net(dev));
        rt_cache_flush(dev_net(dev), delay);
        arp_ifdown(dev);
}

static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
        struct net_device *dev = ifa->ifa_dev->dev;
        struct net *net = dev_net(dev);

        switch (event) {
        case NETDEV_UP:
                fib_add_ifaddr(ifa);
#ifdef CONFIG_IP_ROUTE_MULTIPATH
                fib_sync_up(dev);
#endif
                atomic_inc(&net->ipv4.dev_addr_genid);
                rt_cache_flush(dev_net(dev), -1);
                break;
        case NETDEV_DOWN:
                fib_del_ifaddr(ifa, NULL);
                atomic_inc(&net->ipv4.dev_addr_genid);
                if (ifa->ifa_dev->ifa_list == NULL) {
                        /* Last address was deleted from this interface.
                         * Disable IP.
                         */
                        fib_disable_ip(dev, 1, 0);
                } else {
                        rt_cache_flush(dev_net(dev), -1);
                }
                break;
        }
        return NOTIFY_DONE;
}

static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct net_device *dev = ptr;
        struct in_device *in_dev = __in_dev_get_rtnl(dev);
        struct net *net = dev_net(dev);

        if (event == NETDEV_UNREGISTER) {
                fib_disable_ip(dev, 2, -1);
                return NOTIFY_DONE;
        }

        if (!in_dev)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_UP:
                for_ifa(in_dev) {
                        fib_add_ifaddr(ifa);
                } endfor_ifa(in_dev);
#ifdef CONFIG_IP_ROUTE_MULTIPATH
                fib_sync_up(dev);
#endif
                atomic_inc(&net->ipv4.dev_addr_genid);
                rt_cache_flush(dev_net(dev), -1);
                break;
        case NETDEV_DOWN:
                fib_disable_ip(dev, 0, 0);
                break;
        case NETDEV_CHANGEMTU:
        case NETDEV_CHANGE:
                rt_cache_flush(dev_net(dev), 0);
                break;
        case NETDEV_UNREGISTER_BATCH:
                /* The batch unregister is only called on the first
                 * device in the list of devices being unregistered.
                 * Therefore we should not pass dev_net(dev) in here.
                 */
                rt_cache_flush_batch(NULL);
                break;
        }
        return NOTIFY_DONE;
}

static struct notifier_block fib_inetaddr_notifier = {
        .notifier_call = fib_inetaddr_event,
};

static struct notifier_block fib_netdev_notifier = {
        .notifier_call = fib_netdev_event,
};

static int __net_init ip_fib_net_init(struct net *net)
{
        int err;
        size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ;

        /* Avoid false sharing : Use at least a full cache line */
        size = max_t(size_t, size, L1_CACHE_BYTES);

        net->ipv4.fib_table_hash = kzalloc(size, GFP_KERNEL);
        if (net->ipv4.fib_table_hash == NULL)
                return -ENOMEM;

        err = fib4_rules_init(net);
        if (err < 0)
                goto fail;
        return 0;

fail:
        kfree(net->ipv4.fib_table_hash);
        return err;
}

static void ip_fib_net_exit(struct net *net)
{
        unsigned int i;

#ifdef CONFIG_IP_MULTIPLE_TABLES
        fib4_rules_exit(net);
#endif

        rtnl_lock();
        for (i = 0; i < FIB_TABLE_HASHSZ; i++) {
                struct fib_table *tb;
                struct hlist_head *head;
                struct hlist_node *node, *tmp;

                head = &net->ipv4.fib_table_hash[i];
                hlist_for_each_entry_safe(tb, node, tmp, head, tb_hlist) {
                        hlist_del(node);
                        fib_table_flush(tb);
                        fib_free_table(tb);
                }
        }
        rtnl_unlock();
        kfree(net->ipv4.fib_table_hash);
}

static int __net_init fib_net_init(struct net *net)
{
        int error;

        error = ip_fib_net_init(net);
        if (error < 0)
                goto out;
        error = nl_fib_lookup_init(net);
        if (error < 0)
                goto out_nlfl;
        error = fib_proc_init(net);
        if (error < 0)
                goto out_proc;
out:
        return error;

out_proc:
        nl_fib_lookup_exit(net);
out_nlfl:
        ip_fib_net_exit(net);
        goto out;
}

static void __net_exit fib_net_exit(struct net *net)
{
        fib_proc_exit(net);
        nl_fib_lookup_exit(net);
        ip_fib_net_exit(net);
}

static struct pernet_operations fib_net_ops = {
        .init = fib_net_init,
        .exit = fib_net_exit,
};

void __init ip_fib_init(void)
{
        rtnl_register(PF_INET, RTM_NEWROUTE, inet_rtm_newroute, NULL, NULL);
        rtnl_register(PF_INET, RTM_DELROUTE, inet_rtm_delroute, NULL, NULL);
        rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib, NULL);

        register_pernet_subsys(&fib_net_ops);
        register_netdevice_notifier(&fib_netdev_notifier);
        register_inetaddr_notifier(&fib_inetaddr_notifier);

        fib_trie_init();
}