// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#include <linux/module.h>
#include <linux/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/cache.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>

#include <net/flow.h>
#include <net/inet_dscp.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/nexthop.h>
#include <net/rtnetlink.h>
#include <net/xfrm.h>
#include <net/l3mdev.h>
#include <net/lwtunnel.h>
#include <trace/events/fib.h>

#ifndef CONFIG_IP_MULTIPLE_TABLES

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

        main_table  = fib_trie_table(RT_TABLE_MAIN, NULL);
        if (!main_table)
                return -ENOMEM;

        local_table = fib_trie_table(RT_TABLE_LOCAL, main_table);
        if (!local_table)
                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:
        fib_free_table(main_table);
        return -ENOMEM;
}
#else

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

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

        if (id == RT_TABLE_LOCAL && !net->ipv4.fib_has_custom_rules)
                alias = fib_new_table(net, RT_TABLE_MAIN);

        tb = fib_trie_table(id, alias);
        if (!tb)
                return NULL;

        switch (id) {
        case RT_TABLE_MAIN:
                rcu_assign_pointer(net->ipv4.fib_main, tb);
                break;
        case RT_TABLE_DEFAULT:
                rcu_assign_pointer(net->ipv4.fib_default, tb);
                break;
        default:
                break;
        }

        h = id & (FIB_TABLE_HASHSZ - 1);
        hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);
        return tb;
}
EXPORT_SYMBOL_GPL(fib_new_table);

/* caller must hold either rtnl or rcu read lock */
struct fib_table *fib_get_table(struct net *net, u32 id)
{
        struct fib_table *tb;
        struct hlist_head *head;
        unsigned int h;

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

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

static void fib_replace_table(struct net *net, struct fib_table *old,
                              struct fib_table *new)
{
#ifdef CONFIG_IP_MULTIPLE_TABLES
        switch (new->tb_id) {
        case RT_TABLE_MAIN:
                rcu_assign_pointer(net->ipv4.fib_main, new);
                break;
        case RT_TABLE_DEFAULT:
                rcu_assign_pointer(net->ipv4.fib_default, new);
                break;
        default:
                break;
        }

#endif
        /* replace the old table in the hlist */
        hlist_replace_rcu(&old->tb_hlist, &new->tb_hlist);
}

int fib_unmerge(struct net *net)
{
        struct fib_table *old, *new, *main_table;

        /* attempt to fetch local table if it has been allocated */
        old = fib_get_table(net, RT_TABLE_LOCAL);
        if (!old)
                return 0;

        new = fib_trie_unmerge(old);
        if (!new)
                return -ENOMEM;

        /* table is already unmerged */
        if (new == old)
                return 0;

        /* replace merged table with clean table */
        fib_replace_table(net, old, new);
        fib_free_table(old);

        /* attempt to fetch main table if it has been allocated */
        main_table = fib_get_table(net, RT_TABLE_MAIN);
        if (!main_table)
                return 0;

        /* flush local entries from main table */
        fib_table_flush_external(main_table);

        return 0;
}

void fib_flush(struct net *net)
{
        int flushed = 0;
        unsigned int h;

        for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
                struct hlist_head *head = &net->ipv4.fib_table_hash[h];
                struct hlist_node *tmp;
                struct fib_table *tb;

                hlist_for_each_entry_safe(tb, tmp, head, tb_hlist)
                        flushed += fib_table_flush(net, tb, false);
        }

        if (flushed)
                rt_cache_flush(net);
}

/*
 * 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 int __inet_dev_addr_type(struct net *net,
                                                const struct net_device *dev,
                                                __be32 addr, u32 tb_id)
{
        struct flowi4           fl4 = { .daddr = addr };
        struct fib_result       res;
        unsigned int ret = RTN_BROADCAST;
        struct fib_table *table;

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

        rcu_read_lock();

        table = fib_get_table(net, tb_id);
        if (table) {
                ret = RTN_UNICAST;
                if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {
                        struct fib_nh_common *nhc = fib_info_nhc(res.fi, 0);

                        if (!dev || dev == nhc->nhc_dev)
                                ret = res.type;
                }
        }

        rcu_read_unlock();
        return ret;
}

unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id)
{
        return __inet_dev_addr_type(net, NULL, addr, tb_id);
}
EXPORT_SYMBOL(inet_addr_type_table);

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

unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
                                __be32 addr)
{
        u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;

        return __inet_dev_addr_type(net, dev, addr, rt_table);
}
EXPORT_SYMBOL(inet_dev_addr_type);

/* inet_addr_type with dev == NULL but using the table from a dev
 * if one is associated
 */
unsigned int inet_addr_type_dev_table(struct net *net,
                                      const struct net_device *dev,
                                      __be32 addr)
{
        u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;

        return __inet_dev_addr_type(net, NULL, addr, rt_table);
}
EXPORT_SYMBOL(inet_addr_type_dev_table);

__be32 fib_compute_spec_dst(struct sk_buff *skb)
{
        struct net_device *dev = skb->dev;
        struct in_device *in_dev;
        struct fib_result res;
        struct rtable *rt;
        struct net *net;
        int scope;

        rt = skb_rtable(skb);
        if ((rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | RTCF_LOCAL)) ==
            RTCF_LOCAL)
                return ip_hdr(skb)->daddr;

        in_dev = __in_dev_get_rcu(dev);

        net = dev_net(dev);

        scope = RT_SCOPE_UNIVERSE;
        if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {
                bool vmark = in_dev && IN_DEV_SRC_VMARK(in_dev);
                struct flowi4 fl4 = {
                        .flowi4_iif = LOOPBACK_IFINDEX,
                        .flowi4_l3mdev = l3mdev_master_ifindex_rcu(dev),
                        .daddr = ip_hdr(skb)->saddr,
                        .flowi4_dscp = ip4h_dscp(ip_hdr(skb)),
                        .flowi4_scope = scope,
                        .flowi4_mark = vmark ? skb->mark : 0,
                };
                if (!fib_lookup(net, &fl4, &res, 0))
                        return fib_result_prefsrc(net, &res);
        } else {
                scope = RT_SCOPE_LINK;
        }

        return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);
}

bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
{
        bool dev_match = false;
#ifdef CONFIG_IP_ROUTE_MULTIPATH
        if (unlikely(fi->nh)) {
                dev_match = nexthop_uses_dev(fi->nh, dev);
        } else {
                int ret;

                for (ret = 0; ret < fib_info_num_path(fi); ret++) {
                        const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);

                        if (nhc_l3mdev_matches_dev(nhc, dev)) {
                                dev_match = true;
                                break;
                        }
                }
        }
#else
        if (fib_info_nhc(fi, 0)->nhc_dev == dev)
                dev_match = true;
#endif

        return dev_match;
}
EXPORT_SYMBOL_GPL(fib_info_nh_uses_dev);

/* 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()
 */
static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
                                 dscp_t dscp, int oif, struct net_device *dev,
                                 int rpf, struct in_device *idev, u32 *itag)
{
        struct net *net = dev_net(dev);
        enum skb_drop_reason reason;
        struct flow_keys flkeys;
        int ret, no_addr;
        struct fib_result res;
        struct flowi4 fl4;
        bool dev_match;

        fl4.flowi4_oif = 0;
        fl4.flowi4_l3mdev = l3mdev_master_ifindex_rcu(dev);
        fl4.flowi4_iif = oif ? : LOOPBACK_IFINDEX;
        fl4.daddr = src;
        fl4.saddr = dst;
        fl4.flowi4_dscp = dscp;
        fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
        fl4.flowi4_tun_key.tun_id = 0;
        fl4.flowi4_flags = 0;
        fl4.flowi4_uid = sock_net_uid(net, NULL);
        fl4.flowi4_multipath_hash = 0;

        no_addr = idev->ifa_list == NULL;

        fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;
        if (!fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys)) {
                fl4.flowi4_proto = 0;
                fl4.fl4_sport = 0;
                fl4.fl4_dport = 0;
        } else {
                swap(fl4.fl4_sport, fl4.fl4_dport);
        }

        if (fib_lookup(net, &fl4, &res, 0))
                goto last_resort;
        if (res.type != RTN_UNICAST) {
                if (res.type != RTN_LOCAL) {
                        reason = SKB_DROP_REASON_IP_INVALID_SOURCE;
                        goto e_inval;
                } else if (!IN_DEV_ACCEPT_LOCAL(idev)) {
                        reason = SKB_DROP_REASON_IP_LOCAL_SOURCE;
                        goto e_inval;
                }
        }
        fib_combine_itag(itag, &res);

        dev_match = fib_info_nh_uses_dev(res.fi, dev);
        /* This is not common, loopback packets retain skb_dst so normally they
         * would not even hit this slow path.
         */
        dev_match = dev_match || (res.type == RTN_LOCAL &&
                                  dev == net->loopback_dev);
        if (dev_match) {
                ret = FIB_RES_NHC(res)->nhc_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, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {
                if (res.type == RTN_UNICAST)
                        ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;
        }
        return ret;

last_resort:
        if (rpf)
                goto e_rpf;
        *itag = 0;
        return 0;

e_inval:
        return -reason;
e_rpf:
        return -SKB_DROP_REASON_IP_RPFILTER;
}

/* Ignore rp_filter for packets protected by IPsec. */
int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
                        dscp_t dscp, int oif, struct net_device *dev,
                        struct in_device *idev, u32 *itag)
{
        int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);
        struct net *net = dev_net(dev);

        if (!r && !fib_num_tclassid_users(net) &&
            (dev->ifindex != oif || !IN_DEV_TX_REDIRECTS(idev))) {
                if (IN_DEV_ACCEPT_LOCAL(idev))
                        goto ok;
                /* with custom local routes in place, checking local addresses
                 * only will be too optimistic, with custom rules, checking
                 * local addresses only can be too strict, e.g. due to vrf
                 */
                if (net->ipv4.fib_has_custom_local_routes ||
                    fib4_has_custom_rules(net))
                        goto full_check;
                /* Within the same container, it is regarded as a martian source,
                 * and the same host but different containers are not.
                 */
                if (inet_lookup_ifaddr_rcu(net, src))
                        return -SKB_DROP_REASON_IP_LOCAL_SOURCE;

ok:
                *itag = 0;
                return 0;
        }

full_check:
        return __fib_validate_source(skb, src, dst, dscp, oif, dev, r, idev,
                                     itag);
}

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;
                cfg->fc_table = l3mdev_fib_table(dev);
                if (colon) {
                        const struct in_ifaddr *ifa;
                        struct in_device *in_dev;

                        in_dev = __in_dev_get_rtnl_net(dev);
                        if (!in_dev)
                                return -ENODEV;

                        *colon = ':';

                        in_dev_for_each_ifa_rtnl_net(net, ifa, in_dev) {
                                if (strcmp(ifa->ifa_label, devname) == 0)
                                        break;
                        }

                        if (!ifa)
                                return -ENODEV;
                        cfg->fc_prefsrc = ifa->ifa_local;
                }
        }

        addr = sk_extract_addr(&rt->rt_gateway);
        if (rt->rt_gateway.sa_family == AF_INET && addr) {
                unsigned int addr_type;

                cfg->fc_gw4 = addr;
                cfg->fc_gw_family = AF_INET;
                addr_type = inet_addr_type_table(net, addr, cfg->fc_table);
                if (rt->rt_flags & RTF_GATEWAY &&
                    addr_type == RTN_UNICAST)
                        cfg->fc_scope = RT_SCOPE_UNIVERSE;
        }

        if (!cfg->fc_table)
                cfg->fc_table = RT_TABLE_MAIN;

        if (cmd == SIOCDELRT)
                return 0;

        if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw_family)
                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 = kcalloc(3, nla_total_size(4), GFP_KERNEL);
                if (!mx)
                        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, struct rtentry *rt)
{
        struct fib_config cfg;
        int err;

        switch (cmd) {
        case SIOCADDRT:         /* Add a route */
        case SIOCDELRT:         /* Delete a route */
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                rtnl_net_lock(net);
                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(net, tb, &cfg,
                                                               NULL);
                                else
                                        err = -ESRCH;
                        } else {
                                tb = fib_new_table(net, cfg.fc_table);
                                if (tb)
                                        err = fib_table_insert(net, tb,
                                                               &cfg, NULL);
                                else
                                        err = -ENOBUFS;
                        }

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

const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
        [RTA_UNSPEC]            = { .strict_start_type = RTA_DPORT + 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 },
        [RTA_ENCAP_TYPE]        = { .type = NLA_U16 },
        [RTA_ENCAP]             = { .type = NLA_NESTED },
        [RTA_UID]               = { .type = NLA_U32 },
        [RTA_MARK]              = { .type = NLA_U32 },
        [RTA_TABLE]             = { .type = NLA_U32 },
        [RTA_IP_PROTO]          = { .type = NLA_U8 },
        [RTA_SPORT]             = { .type = NLA_U16 },
        [RTA_DPORT]             = { .type = NLA_U16 },
        [RTA_NH_ID]             = { .type = NLA_U32 },
};

int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,
                    struct netlink_ext_ack *extack)
{
        struct rtvia *via;
        int alen;

        if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr)) {
                NL_SET_ERR_MSG(extack, "Invalid attribute length for RTA_VIA");
                return -EINVAL;
        }

        via = nla_data(nla);
        alen = nla_len(nla) - offsetof(struct rtvia, rtvia_addr);

        switch (via->rtvia_family) {
        case AF_INET:
                if (alen != sizeof(__be32)) {
                        NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_VIA");
                        return -EINVAL;
                }
                cfg->fc_gw_family = AF_INET;
                cfg->fc_gw4 = *((__be32 *)via->rtvia_addr);
                break;
        case AF_INET6:
#if IS_ENABLED(CONFIG_IPV6)
                if (alen != sizeof(struct in6_addr)) {
                        NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_VIA");
                        return -EINVAL;
                }
                cfg->fc_gw_family = AF_INET6;
                cfg->fc_gw6 = *((struct in6_addr *)via->rtvia_addr);
#else
                NL_SET_ERR_MSG(extack, "IPv6 support not enabled in kernel");
                return -EINVAL;
#endif
                break;
        default:
                NL_SET_ERR_MSG(extack, "Unsupported address family in RTA_VIA");
                return -EINVAL;
        }

        return 0;
}

static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
                             struct nlmsghdr *nlh, struct fib_config *cfg,
                             struct netlink_ext_ack *extack)
{
        bool has_gw = false, has_via = false;
        struct nlattr *attr;
        int err, remaining;
        struct rtmsg *rtm;

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

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

        rtm = nlmsg_data(nlh);

        if (!inet_validate_dscp(rtm->rtm_tos)) {
                NL_SET_ERR_MSG(extack,
                               "Invalid dsfield (tos): ECN bits must be 0");
                err = -EINVAL;
                goto errout;
        }
        cfg->fc_dscp = inet_dsfield_to_dscp(rtm->rtm_tos);

        cfg->fc_dst_len = rtm->rtm_dst_len;
        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.portid = NETLINK_CB(skb).portid;
        cfg->fc_nlinfo.nlh = nlh;
        cfg->fc_nlinfo.nl_net = net;

        if (cfg->fc_type > RTN_MAX) {
                NL_SET_ERR_MSG(extack, "Invalid route type");
                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:
                        has_gw = true;
                        cfg->fc_gw4 = nla_get_be32(attr);
                        if (cfg->fc_gw4)
                                cfg->fc_gw_family = AF_INET;
                        break;
                case RTA_VIA:
                        has_via = true;
                        err = fib_gw_from_via(cfg, attr, extack);
                        if (err)
                                goto errout;
                        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:
                        err = lwtunnel_valid_encap_type_attr(nla_data(attr),
                                                             nla_len(attr),
                                                             extack);
                        if (err < 0)
                                goto errout;
                        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;
                case RTA_ENCAP:
                        cfg->fc_encap = attr;
                        break;
                case RTA_ENCAP_TYPE:
                        cfg->fc_encap_type = nla_get_u16(attr);
                        err = lwtunnel_valid_encap_type(cfg->fc_encap_type,
                                                        extack);
                        if (err < 0)
                                goto errout;
                        break;
                case RTA_NH_ID:
                        cfg->fc_nh_id = nla_get_u32(attr);
                        break;
                }
        }

        if (cfg->fc_dst_len > 32) {
                NL_SET_ERR_MSG(extack, "Invalid prefix length");
                err = -EINVAL;
                goto errout;
        }

        if (cfg->fc_dst_len < 32 && (ntohl(cfg->fc_dst) << cfg->fc_dst_len)) {
                NL_SET_ERR_MSG(extack, "Invalid prefix for given prefix length");
                err = -EINVAL;
                goto errout;
        }

        if (cfg->fc_nh_id) {
                if (cfg->fc_oif || cfg->fc_gw_family ||
                    cfg->fc_encap || cfg->fc_mp) {
                        NL_SET_ERR_MSG(extack,
                                       "Nexthop specification and nexthop id are mutually exclusive");
                        err = -EINVAL;
                        goto errout;
                }
        }

        if (has_gw && has_via) {
                NL_SET_ERR_MSG(extack,
                               "Nexthop configuration can not contain both GATEWAY and VIA");
                err = -EINVAL;
                goto errout;
        }

        if (!cfg->fc_table)
                cfg->fc_table = RT_TABLE_MAIN;

        return 0;
errout:
        return err;
}

static int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        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, extack);
        if (err < 0)
                goto errout;

        rtnl_net_lock(net);

        if (cfg.fc_nh_id && !nexthop_find_by_id(net, cfg.fc_nh_id)) {
                NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
                err = -EINVAL;
                goto unlock;
        }

        tb = fib_get_table(net, cfg.fc_table);
        if (!tb) {
                NL_SET_ERR_MSG(extack, "FIB table does not exist");
                err = -ESRCH;
                goto unlock;
        }

        err = fib_table_delete(net, tb, &cfg, extack);
unlock:
        rtnl_net_unlock(net);
errout:
        return err;
}

static int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        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, extack);
        if (err < 0)
                goto errout;

        rtnl_net_lock(net);

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

        err = fib_table_insert(net, tb, &cfg, extack);
        if (!err && cfg.fc_type == RTN_LOCAL)
                net->ipv4.fib_has_custom_local_routes = true;

unlock:
        rtnl_net_unlock(net);
errout:
        return err;
}

int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
                          struct fib_dump_filter *filter,
                          struct netlink_callback *cb)
{
        struct netlink_ext_ack *extack = cb->extack;
        struct nlattr *tb[RTA_MAX + 1];
        struct rtmsg *rtm;
        int err, i;

        if (filter->rtnl_held)
                ASSERT_RTNL();

        rtm = nlmsg_payload(nlh, sizeof(*rtm));
        if (!rtm) {
                NL_SET_ERR_MSG(extack, "Invalid header for FIB dump request");
                return -EINVAL;
        }

        if (rtm->rtm_dst_len || rtm->rtm_src_len  || rtm->rtm_tos   ||
            rtm->rtm_scope) {
                NL_SET_ERR_MSG(extack, "Invalid values in header for FIB dump request");
                return -EINVAL;
        }

        if (rtm->rtm_flags & ~(RTM_F_CLONED | RTM_F_PREFIX)) {
                NL_SET_ERR_MSG(extack, "Invalid flags for FIB dump request");
                return -EINVAL;
        }
        if (rtm->rtm_flags & RTM_F_CLONED)
                filter->dump_routes = false;
        else
                filter->dump_exceptions = false;

        filter->flags    = rtm->rtm_flags;
        filter->protocol = rtm->rtm_protocol;
        filter->rt_type  = rtm->rtm_type;
        filter->table_id = rtm->rtm_table;

        err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
                                            rtm_ipv4_policy, extack);
        if (err < 0)
                return err;

        for (i = 0; i <= RTA_MAX; ++i) {
                int ifindex;

                if (!tb[i])
                        continue;

                switch (i) {
                case RTA_TABLE:
                        filter->table_id = nla_get_u32(tb[i]);
                        break;
                case RTA_OIF:
                        ifindex = nla_get_u32(tb[i]);
                        if (filter->rtnl_held)
                                filter->dev = __dev_get_by_index(net, ifindex);
                        else
                                filter->dev = dev_get_by_index_rcu(net, ifindex);
                        if (!filter->dev)
                                return -ENODEV;
                        break;
                default:
                        NL_SET_ERR_MSG(extack, "Unsupported attribute in dump request");
                        return -EINVAL;
                }
        }

        if (filter->flags || filter->protocol || filter->rt_type ||
            filter->table_id || filter->dev) {
                filter->filter_set = 1;
                cb->answer_flags = NLM_F_DUMP_FILTERED;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ip_valid_fib_dump_req);

static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct fib_dump_filter filter = {
                .dump_routes = true,
                .dump_exceptions = true,
                .rtnl_held = false,
        };
        const struct nlmsghdr *nlh = cb->nlh;
        struct net *net = sock_net(skb->sk);
        unsigned int h, s_h;
        unsigned int e = 0, s_e;
        struct fib_table *tb;
        struct hlist_head *head;
        int dumped = 0, err = 0;

        rcu_read_lock();
        if (cb->strict_check) {
                err = ip_valid_fib_dump_req(net, nlh, &filter, cb);
                if (err < 0)
                        goto unlock;
        } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
                struct rtmsg *rtm = nlmsg_data(nlh);

                filter.flags = rtm->rtm_flags & (RTM_F_PREFIX | RTM_F_CLONED);
        }

        /* ipv4 does not use prefix flag */
        if (filter.flags & RTM_F_PREFIX)
                goto unlock;

        if (filter.table_id) {
                tb = fib_get_table(net, filter.table_id);
                if (!tb) {
                        if (rtnl_msg_family(cb->nlh) != PF_INET)
                                goto unlock;

                        NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist");
                        err = -ENOENT;
                        goto unlock;
                }
                err = fib_table_dump(tb, skb, cb, &filter);
                goto unlock;
        }

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

        err = 0;
        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_rcu(tb, head, tb_hlist) {
                        if (e < s_e)
                                goto next;
                        if (dumped)
                                memset(&cb->args[2], 0, sizeof(cb->args) -
                                                 2 * sizeof(cb->args[0]));
                        err = fib_table_dump(tb, skb, cb, &filter);
                        if (err < 0)
                                goto out;
                        dumped = 1;
next:
                        e++;
                }
        }
out:

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

unlock:
        rcu_read_unlock();
        return err;
}

/* 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, u32 rt_priority)
{
        struct net *net = dev_net(ifa->ifa_dev->dev);
        u32 tb_id = l3mdev_fib_table(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_priority = rt_priority,
                .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 (!tb_id)
                tb_id = (type == RTN_UNICAST) ? RT_TABLE_MAIN : RT_TABLE_LOCAL;

        tb = fib_new_table(net, tb_id);
        if (!tb)
                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(net, tb, &cfg, NULL);
        else
                fib_table_delete(net, tb, &cfg, NULL);
}

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) {
                        pr_warn("%s: bug: prim == NULL\n", __func__);
                        return;
                }
        }

        fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim, 0);

        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, 0);
                arp_invalidate(dev, ifa->ifa_broadcast, false);
        }

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

                /* Add the network broadcast address, when it makes sense */
                if (ifa->ifa_prefixlen < 31) {
                        fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
                                  32, prim, 0);
                        arp_invalidate(dev, prefix | ~mask, false);
                }
        }
}

void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric)
{
        __be32 prefix = ifa->ifa_address & ifa->ifa_mask;
        struct in_device *in_dev = ifa->ifa_dev;
        struct net_device *dev = in_dev->dev;

        if (!(dev->flags & IFF_UP) ||
            ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) ||
            ipv4_is_zeronet(prefix) ||
            (prefix == ifa->ifa_local && ifa->ifa_prefixlen == 32))
                return;

        /* add the new */
        fib_magic(RTM_NEWROUTE,
                  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
                  prefix, ifa->ifa_prefixlen, ifa, new_metric);

        /* delete the old */
        fib_magic(RTM_DELROUTE,
                  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
                  prefix, ifa->ifa_prefixlen, ifa, ifa->ifa_rt_priority);
}

/* 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 int 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) {
                        /* if the device has been deleted, we don't perform
                         * address promotion
                         */
                        if (!in_dev->dead)
                                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)) {
                if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
                        fib_magic(RTM_DELROUTE,
                                  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
                                  any, ifa->ifa_prefixlen, prim, 0);
                subnet = 1;
        }

        if (in_dev->dead)
                goto no_promotions;

        /* 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.
         */
        rcu_read_lock();
        in_dev_for_each_ifa_rcu(ifa1, in_dev) {
                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;
                        }
                }
        }
        rcu_read_unlock();

no_promotions:
        if (!(ok & BRD_OK))
                fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
                          prim, 0);
        if (subnet && ifa->ifa_prefixlen < 31) {
                if (!(ok & BRD1_OK))
                        fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32,
                                  prim, 0);
                if (!(ok & BRD0_OK))
                        fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32,
                                  prim, 0);
        }
        if (!(ok & LOCAL_OK)) {
                unsigned int addr_type;

                fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim, 0);

                /* Check, that this local address finally disappeared. */
                addr_type = inet_addr_type_dev_table(dev_net(dev), dev,
                                                     ifa->ifa_local);
                if (gone && addr_type != 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, 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 net *net, struct fib_result_nl *frn)
{

        struct fib_result       res;
        struct flowi4           fl4 = {
                .flowi4_mark = frn->fl_mark,
                .daddr = frn->fl_addr,
                .flowi4_dscp = inet_dsfield_to_dscp(frn->fl_tos),
                .flowi4_scope = frn->fl_scope,
        };
        struct fib_table *tb;

        rcu_read_lock();

        tb = fib_get_table(net, frn->tb_id_in);

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

                frn->tb_id = tb->tb_id;
                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;
                }
                local_bh_enable();
        }

        rcu_read_unlock();
}

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

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

        skb = netlink_skb_clone(skb, GFP_KERNEL);
        if (!skb)
                return;
        nlh = nlmsg_hdr(skb);

        frn = nlmsg_data(nlh);
        nl_fib_lookup(net, frn);

        portid = NETLINK_CB(skb).portid;      /* netlink portid */
        NETLINK_CB(skb).portid = 0;        /* from kernel */
        NETLINK_CB(skb).dst_group = 0;  /* unicast */
        nlmsg_unicast(net->ipv4.fibnl, skb, portid);
}

static int __net_init nl_fib_lookup_init(struct net *net)
{
        struct sock *sk;
        struct netlink_kernel_cfg cfg = {
                .input  = nl_fib_input,
        };

        sk = netlink_kernel_create(net, NETLINK_FIB_LOOKUP, &cfg);
        if (!sk)
                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, unsigned long event,
                           bool force)
{
        if (fib_sync_down_dev(dev, event, force))
                fib_flush(dev_net(dev));
        else
                rt_cache_flush(dev_net(dev));
        arp_ifdown(dev);
}

static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct in_ifaddr *ifa = 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, RTNH_F_DEAD);
#endif
                atomic_inc(&net->ipv4.dev_addr_genid);
                rt_cache_flush(net);
                break;
        case NETDEV_DOWN:
                fib_del_ifaddr(ifa, NULL);
                atomic_inc(&net->ipv4.dev_addr_genid);
                if (!ifa->ifa_dev->ifa_list) {
                        /* Last address was deleted from this interface.
                         * Disable IP.
                         */
                        fib_disable_ip(dev, event, true);
                } else {
                        rt_cache_flush(net);
                }
                break;
        }
        return NOTIFY_DONE;
}

static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct netdev_notifier_changeupper_info *upper_info = ptr;
        struct netdev_notifier_info_ext *info_ext = ptr;
        struct in_device *in_dev;
        struct net *net = dev_net(dev);
        struct in_ifaddr *ifa;
        unsigned int flags;

        if (event == NETDEV_UNREGISTER) {
                fib_disable_ip(dev, event, true);
                rt_flush_dev(dev);
                return NOTIFY_DONE;
        }

        in_dev = __in_dev_get_rtnl(dev);
        if (!in_dev)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_UP:
                in_dev_for_each_ifa_rtnl(ifa, in_dev) {
                        fib_add_ifaddr(ifa);
                }
#ifdef CONFIG_IP_ROUTE_MULTIPATH
                fib_sync_up(dev, RTNH_F_DEAD);
#endif
                atomic_inc(&net->ipv4.dev_addr_genid);
                rt_cache_flush(net);
                break;
        case NETDEV_DOWN:
                fib_disable_ip(dev, event, false);
                break;
        case NETDEV_CHANGE:
                flags = netif_get_flags(dev);
                if (flags & (IFF_RUNNING | IFF_LOWER_UP))
                        fib_sync_up(dev, RTNH_F_LINKDOWN);
                else
                        fib_sync_down_dev(dev, event, false);
                rt_cache_flush(net);
                break;
        case NETDEV_CHANGEMTU:
                fib_sync_mtu(dev, info_ext->ext.mtu);
                rt_cache_flush(net);
                break;
        case NETDEV_CHANGEUPPER:
                upper_info = ptr;
                /* flush all routes if dev is linked to or unlinked from
                 * an L3 master device (e.g., VRF)
                 */
                if (upper_info->upper_dev &&
                    netif_is_l3_master(upper_info->upper_dev))
                        fib_disable_ip(dev, NETDEV_DOWN, true);
                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;

        err = fib4_notifier_init(net);
        if (err)
                return err;

#ifdef CONFIG_IP_ROUTE_MULTIPATH
        /* Default to 3-tuple */
        net->ipv4.sysctl_fib_multipath_hash_fields =
                FIB_MULTIPATH_HASH_FIELD_DEFAULT_MASK;
#endif

        /* 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) {
                err = -ENOMEM;
                goto err_table_hash_alloc;
        }

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

err_rules_init:
        kfree(net->ipv4.fib_table_hash);
err_table_hash_alloc:
        fib4_notifier_exit(net);
        return err;
}

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

        ASSERT_RTNL_NET(net);
#ifdef CONFIG_IP_MULTIPLE_TABLES
        RCU_INIT_POINTER(net->ipv4.fib_main, NULL);
        RCU_INIT_POINTER(net->ipv4.fib_default, NULL);
#endif
        /* Destroy the tables in reverse order to guarantee that the
         * local table, ID 255, is destroyed before the main table, ID
         * 254. This is necessary as the local table may contain
         * references to data contained in the main table.
         */
        for (i = FIB_TABLE_HASHSZ - 1; i >= 0; i--) {
                struct hlist_head *head = &net->ipv4.fib_table_hash[i];
                struct hlist_node *tmp;
                struct fib_table *tb;

                hlist_for_each_entry_safe(tb, tmp, head, tb_hlist) {
                        hlist_del(&tb->tb_hlist);
                        fib_table_flush(net, tb, true);
                        fib_free_table(tb);
                }
        }

#ifdef CONFIG_IP_MULTIPLE_TABLES
        fib4_rules_exit(net);
#endif

        kfree(net->ipv4.fib_table_hash);
        fib4_notifier_exit(net);
}

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

#ifdef CONFIG_IP_ROUTE_CLASSID
        atomic_set(&net->ipv4.fib_num_tclassid_users, 0);
#endif
        error = ip_fib_net_init(net);
        if (error < 0)
                goto out;

        error = fib4_semantics_init(net);
        if (error)
                goto out_semantics;

        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:
        fib4_semantics_exit(net);
out_semantics:
        rtnl_net_lock(net);
        ip_fib_net_exit(net);
        rtnl_net_unlock(net);
        goto out;
}

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

static void __net_exit fib_net_exit_batch(struct list_head *net_list)
{
        struct net *net;

        rtnl_lock();
        list_for_each_entry(net, net_list, exit_list) {
                __rtnl_net_lock(net);
                ip_fib_net_exit(net);
                __rtnl_net_unlock(net);
        }
        rtnl_unlock();

        list_for_each_entry(net, net_list, exit_list)
                fib4_semantics_exit(net);
}

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

static const struct rtnl_msg_handler fib_rtnl_msg_handlers[] __initconst = {
        {.protocol = PF_INET, .msgtype = RTM_NEWROUTE,
         .doit = inet_rtm_newroute, .flags = RTNL_FLAG_DOIT_PERNET},
        {.protocol = PF_INET, .msgtype = RTM_DELROUTE,
         .doit = inet_rtm_delroute, .flags = RTNL_FLAG_DOIT_PERNET},
        {.protocol = PF_INET, .msgtype = RTM_GETROUTE, .dumpit = inet_dump_fib,
         .flags = RTNL_FLAG_DUMP_UNLOCKED | RTNL_FLAG_DUMP_SPLIT_NLM_DONE},
};

void __init ip_fib_init(void)
{
        fib_trie_init();

        register_pernet_subsys(&fib_net_ops);

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

        rtnl_register_many(fib_rtnl_msg_handlers);
}