#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/sysctl.h>
#include <linux/net.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/ipv6.h>
#include <linux/mpls.h>
#include <linux/netconf.h>
#include <linux/vmalloc.h>
#include <linux/percpu.h>
#include <net/ip.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/ip_fib.h>
#include <net/netevent.h>
#include <net/netns/generic.h>
#if IS_ENABLED(CONFIG_IPV6)
#include <net/ipv6.h>
#endif
#include <net/addrconf.h>
#include <net/nexthop.h>
#include "internal.h"

/* max memory we will use for mpls_route */
#define MAX_MPLS_ROUTE_MEM      4096

/* Maximum number of labels to look ahead at when selecting a path of
 * a multipath route
 */
#define MAX_MP_SELECT_LABELS 4

#define MPLS_NEIGH_TABLE_UNSPEC (NEIGH_LINK_TABLE + 1)

static int zero = 0;
static int one = 1;
static int label_limit = (1 << 20) - 1;
static int ttl_max = 255;

static void rtmsg_lfib(int event, u32 label, struct mpls_route *rt,
                       struct nlmsghdr *nlh, struct net *net, u32 portid,
                       unsigned int nlm_flags);

static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned index)
{
        struct mpls_route *rt = NULL;

        if (index < net->mpls.platform_labels) {
                struct mpls_route __rcu **platform_label =
                        rcu_dereference(net->mpls.platform_label);
                rt = rcu_dereference(platform_label[index]);
        }
        return rt;
}

bool mpls_output_possible(const struct net_device *dev)
{
        return dev && (dev->flags & IFF_UP) && netif_carrier_ok(dev);
}
EXPORT_SYMBOL_GPL(mpls_output_possible);

static u8 *__mpls_nh_via(struct mpls_route *rt, struct mpls_nh *nh)
{
        return (u8 *)nh + rt->rt_via_offset;
}

static const u8 *mpls_nh_via(const struct mpls_route *rt,
                             const struct mpls_nh *nh)
{
        return __mpls_nh_via((struct mpls_route *)rt, (struct mpls_nh *)nh);
}

static unsigned int mpls_nh_header_size(const struct mpls_nh *nh)
{
        /* The size of the layer 2.5 labels to be added for this route */
        return nh->nh_labels * sizeof(struct mpls_shim_hdr);
}

unsigned int mpls_dev_mtu(const struct net_device *dev)
{
        /* The amount of data the layer 2 frame can hold */
        return dev->mtu;
}
EXPORT_SYMBOL_GPL(mpls_dev_mtu);

bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
{
        if (skb->len <= mtu)
                return false;

        if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
                return false;

        return true;
}
EXPORT_SYMBOL_GPL(mpls_pkt_too_big);

void mpls_stats_inc_outucastpkts(struct net_device *dev,
                                 const struct sk_buff *skb)
{
        struct mpls_dev *mdev;

        if (skb->protocol == htons(ETH_P_MPLS_UC)) {
                mdev = mpls_dev_get(dev);
                if (mdev)
                        MPLS_INC_STATS_LEN(mdev, skb->len,
                                           tx_packets,
                                           tx_bytes);
        } else if (skb->protocol == htons(ETH_P_IP)) {
                IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
#if IS_ENABLED(CONFIG_IPV6)
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                struct inet6_dev *in6dev = __in6_dev_get(dev);

                if (in6dev)
                        IP6_UPD_PO_STATS(dev_net(dev), in6dev,
                                         IPSTATS_MIB_OUT, skb->len);
#endif
        }
}
EXPORT_SYMBOL_GPL(mpls_stats_inc_outucastpkts);

static u32 mpls_multipath_hash(struct mpls_route *rt, struct sk_buff *skb)
{
        struct mpls_entry_decoded dec;
        unsigned int mpls_hdr_len = 0;
        struct mpls_shim_hdr *hdr;
        bool eli_seen = false;
        int label_index;
        u32 hash = 0;

        for (label_index = 0; label_index < MAX_MP_SELECT_LABELS;
             label_index++) {
                mpls_hdr_len += sizeof(*hdr);
                if (!pskb_may_pull(skb, mpls_hdr_len))
                        break;

                /* Read and decode the current label */
                hdr = mpls_hdr(skb) + label_index;
                dec = mpls_entry_decode(hdr);

                /* RFC6790 - reserved labels MUST NOT be used as keys
                 * for the load-balancing function
                 */
                if (likely(dec.label >= MPLS_LABEL_FIRST_UNRESERVED)) {
                        hash = jhash_1word(dec.label, hash);

                        /* The entropy label follows the entropy label
                         * indicator, so this means that the entropy
                         * label was just added to the hash - no need to
                         * go any deeper either in the label stack or in the
                         * payload
                         */
                        if (eli_seen)
                                break;
                } else if (dec.label == MPLS_LABEL_ENTROPY) {
                        eli_seen = true;
                }

                if (!dec.bos)
                        continue;

                /* found bottom label; does skb have room for a header? */
                if (pskb_may_pull(skb, mpls_hdr_len + sizeof(struct iphdr))) {
                        const struct iphdr *v4hdr;

                        v4hdr = (const struct iphdr *)(hdr + 1);
                        if (v4hdr->version == 4) {
                                hash = jhash_3words(ntohl(v4hdr->saddr),
                                                    ntohl(v4hdr->daddr),
                                                    v4hdr->protocol, hash);
                        } else if (v4hdr->version == 6 &&
                                   pskb_may_pull(skb, mpls_hdr_len +
                                                 sizeof(struct ipv6hdr))) {
                                const struct ipv6hdr *v6hdr;

                                v6hdr = (const struct ipv6hdr *)(hdr + 1);
                                hash = __ipv6_addr_jhash(&v6hdr->saddr, hash);
                                hash = __ipv6_addr_jhash(&v6hdr->daddr, hash);
                                hash = jhash_1word(v6hdr->nexthdr, hash);
                        }
                }

                break;
        }

        return hash;
}

static struct mpls_nh *mpls_get_nexthop(struct mpls_route *rt, u8 index)
{
        return (struct mpls_nh *)((u8 *)rt->rt_nh + index * rt->rt_nh_size);
}

/* number of alive nexthops (rt->rt_nhn_alive) and the flags for
 * a next hop (nh->nh_flags) are modified by netdev event handlers.
 * Since those fields can change at any moment, use READ_ONCE to
 * access both.
 */
static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt,
                                             struct sk_buff *skb)
{
        u32 hash = 0;
        int nh_index = 0;
        int n = 0;
        u8 alive;

        /* No need to look further into packet if there's only
         * one path
         */
        if (rt->rt_nhn == 1)
                return rt->rt_nh;

        alive = READ_ONCE(rt->rt_nhn_alive);
        if (alive == 0)
                return NULL;

        hash = mpls_multipath_hash(rt, skb);
        nh_index = hash % alive;
        if (alive == rt->rt_nhn)
                goto out;
        for_nexthops(rt) {
                unsigned int nh_flags = READ_ONCE(nh->nh_flags);

                if (nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
                        continue;
                if (n == nh_index)
                        return nh;
                n++;
        } endfor_nexthops(rt);

out:
        return mpls_get_nexthop(rt, nh_index);
}

static bool mpls_egress(struct net *net, struct mpls_route *rt,
                        struct sk_buff *skb, struct mpls_entry_decoded dec)
{
        enum mpls_payload_type payload_type;
        bool success = false;

        /* The IPv4 code below accesses through the IPv4 header
         * checksum, which is 12 bytes into the packet.
         * The IPv6 code below accesses through the IPv6 hop limit
         * which is 8 bytes into the packet.
         *
         * For all supported cases there should always be at least 12
         * bytes of packet data present.  The IPv4 header is 20 bytes
         * without options and the IPv6 header is always 40 bytes
         * long.
         */
        if (!pskb_may_pull(skb, 12))
                return false;

        payload_type = rt->rt_payload_type;
        if (payload_type == MPT_UNSPEC)
                payload_type = ip_hdr(skb)->version;

        switch (payload_type) {
        case MPT_IPV4: {
                struct iphdr *hdr4 = ip_hdr(skb);
                u8 new_ttl;
                skb->protocol = htons(ETH_P_IP);

                /* If propagating TTL, take the decremented TTL from
                 * the incoming MPLS header, otherwise decrement the
                 * TTL, but only if not 0 to avoid underflow.
                 */
                if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
                    (rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
                     net->mpls.ip_ttl_propagate))
                        new_ttl = dec.ttl;
                else
                        new_ttl = hdr4->ttl ? hdr4->ttl - 1 : 0;

                csum_replace2(&hdr4->check,
                              htons(hdr4->ttl << 8),
                              htons(new_ttl << 8));
                hdr4->ttl = new_ttl;
                success = true;
                break;
        }
        case MPT_IPV6: {
                struct ipv6hdr *hdr6 = ipv6_hdr(skb);
                skb->protocol = htons(ETH_P_IPV6);

                /* If propagating TTL, take the decremented TTL from
                 * the incoming MPLS header, otherwise decrement the
                 * hop limit, but only if not 0 to avoid underflow.
                 */
                if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
                    (rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
                     net->mpls.ip_ttl_propagate))
                        hdr6->hop_limit = dec.ttl;
                else if (hdr6->hop_limit)
                        hdr6->hop_limit = hdr6->hop_limit - 1;
                success = true;
                break;
        }
        case MPT_UNSPEC:
                /* Should have decided which protocol it is by now */
                break;
        }

        return success;
}

static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
                        struct packet_type *pt, struct net_device *orig_dev)
{
        struct net *net = dev_net(dev);
        struct mpls_shim_hdr *hdr;
        struct mpls_route *rt;
        struct mpls_nh *nh;
        struct mpls_entry_decoded dec;
        struct net_device *out_dev;
        struct mpls_dev *out_mdev;
        struct mpls_dev *mdev;
        unsigned int hh_len;
        unsigned int new_header_size;
        unsigned int mtu;
        int err;

        /* Careful this entire function runs inside of an rcu critical section */

        mdev = mpls_dev_get(dev);
        if (!mdev)
                goto drop;

        MPLS_INC_STATS_LEN(mdev, skb->len, rx_packets,
                           rx_bytes);

        if (!mdev->input_enabled) {
                MPLS_INC_STATS(mdev, rx_dropped);
                goto drop;
        }

        if (skb->pkt_type != PACKET_HOST)
                goto err;

        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                goto err;

        if (!pskb_may_pull(skb, sizeof(*hdr)))
                goto err;

        /* Read and decode the label */
        hdr = mpls_hdr(skb);
        dec = mpls_entry_decode(hdr);

        rt = mpls_route_input_rcu(net, dec.label);
        if (!rt) {
                MPLS_INC_STATS(mdev, rx_noroute);
                goto drop;
        }

        nh = mpls_select_multipath(rt, skb);
        if (!nh)
                goto err;

        /* Pop the label */
        skb_pull(skb, sizeof(*hdr));
        skb_reset_network_header(skb);

        skb_orphan(skb);

        if (skb_warn_if_lro(skb))
                goto err;

        skb_forward_csum(skb);

        /* Verify ttl is valid */
        if (dec.ttl <= 1)
                goto err;
        dec.ttl -= 1;

        /* Find the output device */
        out_dev = rcu_dereference(nh->nh_dev);
        if (!mpls_output_possible(out_dev))
                goto tx_err;

        /* Verify the destination can hold the packet */
        new_header_size = mpls_nh_header_size(nh);
        mtu = mpls_dev_mtu(out_dev);
        if (mpls_pkt_too_big(skb, mtu - new_header_size))
                goto tx_err;

        hh_len = LL_RESERVED_SPACE(out_dev);
        if (!out_dev->header_ops)
                hh_len = 0;

        /* Ensure there is enough space for the headers in the skb */
        if (skb_cow(skb, hh_len + new_header_size))
                goto tx_err;

        skb->dev = out_dev;
        skb->protocol = htons(ETH_P_MPLS_UC);

        if (unlikely(!new_header_size && dec.bos)) {
                /* Penultimate hop popping */
                if (!mpls_egress(dev_net(out_dev), rt, skb, dec))
                        goto err;
        } else {
                bool bos;
                int i;
                skb_push(skb, new_header_size);
                skb_reset_network_header(skb);
                /* Push the new labels */
                hdr = mpls_hdr(skb);
                bos = dec.bos;
                for (i = nh->nh_labels - 1; i >= 0; i--) {
                        hdr[i] = mpls_entry_encode(nh->nh_label[i],
                                                   dec.ttl, 0, bos);
                        bos = false;
                }
        }

        mpls_stats_inc_outucastpkts(out_dev, skb);

        /* If via wasn't specified then send out using device address */
        if (nh->nh_via_table == MPLS_NEIGH_TABLE_UNSPEC)
                err = neigh_xmit(NEIGH_LINK_TABLE, out_dev,
                                 out_dev->dev_addr, skb);
        else
                err = neigh_xmit(nh->nh_via_table, out_dev,
                                 mpls_nh_via(rt, nh), skb);
        if (err)
                net_dbg_ratelimited("%s: packet transmission failed: %d\n",
                                    __func__, err);
        return 0;

tx_err:
        out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
        if (out_mdev)
                MPLS_INC_STATS(out_mdev, tx_errors);
        goto drop;
err:
        MPLS_INC_STATS(mdev, rx_errors);
drop:
        kfree_skb(skb);
        return NET_RX_DROP;
}

static struct packet_type mpls_packet_type __read_mostly = {
        .type = cpu_to_be16(ETH_P_MPLS_UC),
        .func = mpls_forward,
};

static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
        [RTA_DST]               = { .type = NLA_U32 },
        [RTA_OIF]               = { .type = NLA_U32 },
        [RTA_TTL_PROPAGATE]     = { .type = NLA_U8 },
};

struct mpls_route_config {
        u32                     rc_protocol;
        u32                     rc_ifindex;
        u8                      rc_via_table;
        u8                      rc_via_alen;
        u8                      rc_via[MAX_VIA_ALEN];
        u32                     rc_label;
        u8                      rc_ttl_propagate;
        u8                      rc_output_labels;
        u32                     rc_output_label[MAX_NEW_LABELS];
        u32                     rc_nlflags;
        enum mpls_payload_type  rc_payload_type;
        struct nl_info          rc_nlinfo;
        struct rtnexthop        *rc_mp;
        int                     rc_mp_len;
};

/* all nexthops within a route have the same size based on max
 * number of labels and max via length for a hop
 */
static struct mpls_route *mpls_rt_alloc(u8 num_nh, u8 max_alen, u8 max_labels)
{
        u8 nh_size = MPLS_NH_SIZE(max_labels, max_alen);
        struct mpls_route *rt;
        size_t size;

        size = sizeof(*rt) + num_nh * nh_size;
        if (size > MAX_MPLS_ROUTE_MEM)
                return ERR_PTR(-EINVAL);

        rt = kzalloc(size, GFP_KERNEL);
        if (!rt)
                return ERR_PTR(-ENOMEM);

        rt->rt_nhn = num_nh;
        rt->rt_nhn_alive = num_nh;
        rt->rt_nh_size = nh_size;
        rt->rt_via_offset = MPLS_NH_VIA_OFF(max_labels);

        return rt;
}

static void mpls_rt_free(struct mpls_route *rt)
{
        if (rt)
                kfree_rcu(rt, rt_rcu);
}

static void mpls_notify_route(struct net *net, unsigned index,
                              struct mpls_route *old, struct mpls_route *new,
                              const struct nl_info *info)
{
        struct nlmsghdr *nlh = info ? info->nlh : NULL;
        unsigned portid = info ? info->portid : 0;
        int event = new ? RTM_NEWROUTE : RTM_DELROUTE;
        struct mpls_route *rt = new ? new : old;
        unsigned nlm_flags = (old && new) ? NLM_F_REPLACE : 0;
        /* Ignore reserved labels for now */
        if (rt && (index >= MPLS_LABEL_FIRST_UNRESERVED))
                rtmsg_lfib(event, index, rt, nlh, net, portid, nlm_flags);
}

static void mpls_route_update(struct net *net, unsigned index,
                              struct mpls_route *new,
                              const struct nl_info *info)
{
        struct mpls_route __rcu **platform_label;
        struct mpls_route *rt;

        ASSERT_RTNL();

        platform_label = rtnl_dereference(net->mpls.platform_label);
        rt = rtnl_dereference(platform_label[index]);
        rcu_assign_pointer(platform_label[index], new);

        mpls_notify_route(net, index, rt, new, info);

        /* If we removed a route free it now */
        mpls_rt_free(rt);
}

static unsigned find_free_label(struct net *net)
{
        struct mpls_route __rcu **platform_label;
        size_t platform_labels;
        unsigned index;

        platform_label = rtnl_dereference(net->mpls.platform_label);
        platform_labels = net->mpls.platform_labels;
        for (index = MPLS_LABEL_FIRST_UNRESERVED; index < platform_labels;
             index++) {
                if (!rtnl_dereference(platform_label[index]))
                        return index;
        }
        return LABEL_NOT_SPECIFIED;
}

#if IS_ENABLED(CONFIG_INET)
static struct net_device *inet_fib_lookup_dev(struct net *net,
                                              const void *addr)
{
        struct net_device *dev;
        struct rtable *rt;
        struct in_addr daddr;

        memcpy(&daddr, addr, sizeof(struct in_addr));
        rt = ip_route_output(net, daddr.s_addr, 0, 0, 0);
        if (IS_ERR(rt))
                return ERR_CAST(rt);

        dev = rt->dst.dev;
        dev_hold(dev);

        ip_rt_put(rt);

        return dev;
}
#else
static struct net_device *inet_fib_lookup_dev(struct net *net,
                                              const void *addr)
{
        return ERR_PTR(-EAFNOSUPPORT);
}
#endif

#if IS_ENABLED(CONFIG_IPV6)
static struct net_device *inet6_fib_lookup_dev(struct net *net,
                                               const void *addr)
{
        struct net_device *dev;
        struct dst_entry *dst;
        struct flowi6 fl6;
        int err;

        if (!ipv6_stub)
                return ERR_PTR(-EAFNOSUPPORT);

        memset(&fl6, 0, sizeof(fl6));
        memcpy(&fl6.daddr, addr, sizeof(struct in6_addr));
        err = ipv6_stub->ipv6_dst_lookup(net, NULL, &dst, &fl6);
        if (err)
                return ERR_PTR(err);

        dev = dst->dev;
        dev_hold(dev);
        dst_release(dst);

        return dev;
}
#else
static struct net_device *inet6_fib_lookup_dev(struct net *net,
                                               const void *addr)
{
        return ERR_PTR(-EAFNOSUPPORT);
}
#endif

static struct net_device *find_outdev(struct net *net,
                                      struct mpls_route *rt,
                                      struct mpls_nh *nh, int oif)
{
        struct net_device *dev = NULL;

        if (!oif) {
                switch (nh->nh_via_table) {
                case NEIGH_ARP_TABLE:
                        dev = inet_fib_lookup_dev(net, mpls_nh_via(rt, nh));
                        break;
                case NEIGH_ND_TABLE:
                        dev = inet6_fib_lookup_dev(net, mpls_nh_via(rt, nh));
                        break;
                case NEIGH_LINK_TABLE:
                        break;
                }
        } else {
                dev = dev_get_by_index(net, oif);
        }

        if (!dev)
                return ERR_PTR(-ENODEV);

        if (IS_ERR(dev))
                return dev;

        /* The caller is holding rtnl anyways, so release the dev reference */
        dev_put(dev);

        return dev;
}

static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
                              struct mpls_nh *nh, int oif)
{
        struct net_device *dev = NULL;
        int err = -ENODEV;

        dev = find_outdev(net, rt, nh, oif);
        if (IS_ERR(dev)) {
                err = PTR_ERR(dev);
                dev = NULL;
                goto errout;
        }

        /* Ensure this is a supported device */
        err = -EINVAL;
        if (!mpls_dev_get(dev))
                goto errout;

        if ((nh->nh_via_table == NEIGH_LINK_TABLE) &&
            (dev->addr_len != nh->nh_via_alen))
                goto errout;

        RCU_INIT_POINTER(nh->nh_dev, dev);

        if (!(dev->flags & IFF_UP)) {
                nh->nh_flags |= RTNH_F_DEAD;
        } else {
                unsigned int flags;

                flags = dev_get_flags(dev);
                if (!(flags & (IFF_RUNNING | IFF_LOWER_UP)))
                        nh->nh_flags |= RTNH_F_LINKDOWN;
        }

        return 0;

errout:
        return err;
}

static int mpls_nh_build_from_cfg(struct mpls_route_config *cfg,
                                  struct mpls_route *rt)
{
        struct net *net = cfg->rc_nlinfo.nl_net;
        struct mpls_nh *nh = rt->rt_nh;
        int err;
        int i;

        if (!nh)
                return -ENOMEM;

        err = -EINVAL;

        nh->nh_labels = cfg->rc_output_labels;
        for (i = 0; i < nh->nh_labels; i++)
                nh->nh_label[i] = cfg->rc_output_label[i];

        nh->nh_via_table = cfg->rc_via_table;
        memcpy(__mpls_nh_via(rt, nh), cfg->rc_via, cfg->rc_via_alen);
        nh->nh_via_alen = cfg->rc_via_alen;

        err = mpls_nh_assign_dev(net, rt, nh, cfg->rc_ifindex);
        if (err)
                goto errout;

        if (nh->nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
                rt->rt_nhn_alive--;

        return 0;

errout:
        return err;
}

static int mpls_nh_build(struct net *net, struct mpls_route *rt,
                         struct mpls_nh *nh, int oif, struct nlattr *via,
                         struct nlattr *newdst, u8 max_labels)
{
        int err = -ENOMEM;

        if (!nh)
                goto errout;

        if (newdst) {
                err = nla_get_labels(newdst, max_labels,
                                     &nh->nh_labels, nh->nh_label);
                if (err)
                        goto errout;
        }

        if (via) {
                err = nla_get_via(via, &nh->nh_via_alen, &nh->nh_via_table,
                                  __mpls_nh_via(rt, nh));
                if (err)
                        goto errout;
        } else {
                nh->nh_via_table = MPLS_NEIGH_TABLE_UNSPEC;
        }

        err = mpls_nh_assign_dev(net, rt, nh, oif);
        if (err)
                goto errout;

        return 0;

errout:
        return err;
}

static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,
                              u8 cfg_via_alen, u8 *max_via_alen,
                              u8 *max_labels)
{
        int remaining = len;
        u8 nhs = 0;

        *max_via_alen = 0;
        *max_labels = 0;

        while (rtnh_ok(rtnh, remaining)) {
                struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
                int attrlen;
                u8 n_labels = 0;

                attrlen = rtnh_attrlen(rtnh);
                nla = nla_find(attrs, attrlen, RTA_VIA);
                if (nla && nla_len(nla) >=
                    offsetof(struct rtvia, rtvia_addr)) {
                        int via_alen = nla_len(nla) -
                                offsetof(struct rtvia, rtvia_addr);

                        if (via_alen <= MAX_VIA_ALEN)
                                *max_via_alen = max_t(u16, *max_via_alen,
                                                      via_alen);
                }

                nla = nla_find(attrs, attrlen, RTA_NEWDST);
                if (nla &&
                    nla_get_labels(nla, MAX_NEW_LABELS, &n_labels, NULL) != 0)
                        return 0;

                *max_labels = max_t(u8, *max_labels, n_labels);

                /* number of nexthops is tracked by a u8.
                 * Check for overflow.
                 */
                if (nhs == 255)
                        return 0;
                nhs++;

                rtnh = rtnh_next(rtnh, &remaining);
        }

        /* leftover implies invalid nexthop configuration, discard it */
        return remaining > 0 ? 0 : nhs;
}

static int mpls_nh_build_multi(struct mpls_route_config *cfg,
                               struct mpls_route *rt, u8 max_labels)
{
        struct rtnexthop *rtnh = cfg->rc_mp;
        struct nlattr *nla_via, *nla_newdst;
        int remaining = cfg->rc_mp_len;
        int err = 0;
        u8 nhs = 0;

        change_nexthops(rt) {
                int attrlen;

                nla_via = NULL;
                nla_newdst = NULL;

                err = -EINVAL;
                if (!rtnh_ok(rtnh, remaining))
                        goto errout;

                /* neither weighted multipath nor any flags
                 * are supported
                 */
                if (rtnh->rtnh_hops || rtnh->rtnh_flags)
                        goto errout;

                attrlen = rtnh_attrlen(rtnh);
                if (attrlen > 0) {
                        struct nlattr *attrs = rtnh_attrs(rtnh);

                        nla_via = nla_find(attrs, attrlen, RTA_VIA);
                        nla_newdst = nla_find(attrs, attrlen, RTA_NEWDST);
                }

                err = mpls_nh_build(cfg->rc_nlinfo.nl_net, rt, nh,
                                    rtnh->rtnh_ifindex, nla_via, nla_newdst,
                                    max_labels);
                if (err)
                        goto errout;

                if (nh->nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
                        rt->rt_nhn_alive--;

                rtnh = rtnh_next(rtnh, &remaining);
                nhs++;
        } endfor_nexthops(rt);

        rt->rt_nhn = nhs;

        return 0;

errout:
        return err;
}

static int mpls_route_add(struct mpls_route_config *cfg)
{
        struct mpls_route __rcu **platform_label;
        struct net *net = cfg->rc_nlinfo.nl_net;
        struct mpls_route *rt, *old;
        int err = -EINVAL;
        u8 max_via_alen;
        unsigned index;
        u8 max_labels;
        u8 nhs;

        index = cfg->rc_label;

        /* If a label was not specified during insert pick one */
        if ((index == LABEL_NOT_SPECIFIED) &&
            (cfg->rc_nlflags & NLM_F_CREATE)) {
                index = find_free_label(net);
        }

        /* Reserved labels may not be set */
        if (index < MPLS_LABEL_FIRST_UNRESERVED)
                goto errout;

        /* The full 20 bit range may not be supported. */
        if (index >= net->mpls.platform_labels)
                goto errout;

        /* Append makes no sense with mpls */
        err = -EOPNOTSUPP;
        if (cfg->rc_nlflags & NLM_F_APPEND)
                goto errout;

        err = -EEXIST;
        platform_label = rtnl_dereference(net->mpls.platform_label);
        old = rtnl_dereference(platform_label[index]);
        if ((cfg->rc_nlflags & NLM_F_EXCL) && old)
                goto errout;

        err = -EEXIST;
        if (!(cfg->rc_nlflags & NLM_F_REPLACE) && old)
                goto errout;

        err = -ENOENT;
        if (!(cfg->rc_nlflags & NLM_F_CREATE) && !old)
                goto errout;

        err = -EINVAL;
        if (cfg->rc_mp) {
                nhs = mpls_count_nexthops(cfg->rc_mp, cfg->rc_mp_len,
                                          cfg->rc_via_alen, &max_via_alen,
                                          &max_labels);
        } else {
                max_via_alen = cfg->rc_via_alen;
                max_labels = cfg->rc_output_labels;
                nhs = 1;
        }

        if (nhs == 0)
                goto errout;

        err = -ENOMEM;
        rt = mpls_rt_alloc(nhs, max_via_alen, max_labels);
        if (IS_ERR(rt)) {
                err = PTR_ERR(rt);
                goto errout;
        }

        rt->rt_protocol = cfg->rc_protocol;
        rt->rt_payload_type = cfg->rc_payload_type;
        rt->rt_ttl_propagate = cfg->rc_ttl_propagate;

        if (cfg->rc_mp)
                err = mpls_nh_build_multi(cfg, rt, max_labels);
        else
                err = mpls_nh_build_from_cfg(cfg, rt);
        if (err)
                goto freert;

        mpls_route_update(net, index, rt, &cfg->rc_nlinfo);

        return 0;

freert:
        mpls_rt_free(rt);
errout:
        return err;
}

static int mpls_route_del(struct mpls_route_config *cfg)
{
        struct net *net = cfg->rc_nlinfo.nl_net;
        unsigned index;
        int err = -EINVAL;

        index = cfg->rc_label;

        /* Reserved labels may not be removed */
        if (index < MPLS_LABEL_FIRST_UNRESERVED)
                goto errout;

        /* The full 20 bit range may not be supported */
        if (index >= net->mpls.platform_labels)
                goto errout;

        mpls_route_update(net, index, NULL, &cfg->rc_nlinfo);

        err = 0;
errout:
        return err;
}

static void mpls_get_stats(struct mpls_dev *mdev,
                           struct mpls_link_stats *stats)
{
        struct mpls_pcpu_stats *p;
        int i;

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

        for_each_possible_cpu(i) {
                struct mpls_link_stats local;
                unsigned int start;

                p = per_cpu_ptr(mdev->stats, i);
                do {
                        start = u64_stats_fetch_begin(&p->syncp);
                        local = p->stats;
                } while (u64_stats_fetch_retry(&p->syncp, start));

                stats->rx_packets       += local.rx_packets;
                stats->rx_bytes         += local.rx_bytes;
                stats->tx_packets       += local.tx_packets;
                stats->tx_bytes         += local.tx_bytes;
                stats->rx_errors        += local.rx_errors;
                stats->tx_errors        += local.tx_errors;
                stats->rx_dropped       += local.rx_dropped;
                stats->tx_dropped       += local.tx_dropped;
                stats->rx_noroute       += local.rx_noroute;
        }
}

static int mpls_fill_stats_af(struct sk_buff *skb,
                              const struct net_device *dev)

{
        struct mpls_link_stats *stats;
        struct mpls_dev *mdev;
        struct nlattr *nla;

        mdev = mpls_dev_get(dev);
        if (!mdev)
                return -ENODATA;

        nla = nla_reserve_64bit(skb, MPLS_STATS_LINK,
                                sizeof(struct mpls_link_stats),
                                MPLS_STATS_UNSPEC);
        if (!nla)
                return -EMSGSIZE;

        stats = nla_data(nla);
        mpls_get_stats(mdev, stats);

        return 0;
}

static size_t mpls_get_stats_af_size(const struct net_device *dev)
{
        struct mpls_dev *mdev;

        mdev = mpls_dev_get(dev);
        if (!mdev)
                return 0;

        return nla_total_size_64bit(sizeof(struct mpls_link_stats));
}

static int mpls_netconf_fill_devconf(struct sk_buff *skb, struct mpls_dev *mdev,
                                     u32 portid, u32 seq, int event,
                                     unsigned int flags, int type)
{
        struct nlmsghdr  *nlh;
        struct netconfmsg *ncm;
        bool all = false;

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

        if (type == NETCONFA_ALL)
                all = true;

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

        if (nla_put_s32(skb, NETCONFA_IFINDEX, mdev->dev->ifindex) < 0)
                goto nla_put_failure;

        if ((all || type == NETCONFA_INPUT) &&
            nla_put_s32(skb, NETCONFA_INPUT,
                        mdev->input_enabled) < 0)
                goto nla_put_failure;

        nlmsg_end(skb, nlh);
        return 0;

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

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

        if (type == NETCONFA_ALL)
                all = true;

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

        return size;
}

static void mpls_netconf_notify_devconf(struct net *net, int event,
                                        int type, struct mpls_dev *mdev)
{
        struct sk_buff *skb;
        int err = -ENOBUFS;

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

        err = mpls_netconf_fill_devconf(skb, mdev, 0, 0, event, 0, type);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in mpls_netconf_msgsize_devconf() */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }

        rtnl_notify(skb, net, 0, RTNLGRP_MPLS_NETCONF, NULL, GFP_KERNEL);
        return;
errout:
        if (err < 0)
                rtnl_set_sk_err(net, RTNLGRP_MPLS_NETCONF, err);
}

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

static int mpls_netconf_get_devconf(struct sk_buff *in_skb,
                                    struct nlmsghdr *nlh,
                                    struct netlink_ext_ack *extack)
{
        struct net *net = sock_net(in_skb->sk);
        struct nlattr *tb[NETCONFA_MAX + 1];
        struct netconfmsg *ncm;
        struct net_device *dev;
        struct mpls_dev *mdev;
        struct sk_buff *skb;
        int ifindex;
        int err;

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

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

        ifindex = nla_get_s32(tb[NETCONFA_IFINDEX]);
        dev = __dev_get_by_index(net, ifindex);
        if (!dev)
                goto errout;

        mdev = mpls_dev_get(dev);
        if (!mdev)
                goto errout;

        err = -ENOBUFS;
        skb = nlmsg_new(mpls_netconf_msgsize_devconf(NETCONFA_ALL), GFP_KERNEL);
        if (!skb)
                goto errout;

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

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

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

        for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
                idx = 0;
                head = &net->dev_index_head[h];
                rcu_read_lock();
                cb->seq = net->dev_base_seq;
                hlist_for_each_entry_rcu(dev, head, index_hlist) {
                        if (idx < s_idx)
                                goto cont;
                        mdev = mpls_dev_get(dev);
                        if (!mdev)
                                goto cont;
                        if (mpls_netconf_fill_devconf(skb, mdev,
                                                      NETLINK_CB(cb->skb).portid,
                                                      cb->nlh->nlmsg_seq,
                                                      RTM_NEWNETCONF,
                                                      NLM_F_MULTI,
                                                      NETCONFA_ALL) < 0) {
                                rcu_read_unlock();
                                goto done;
                        }
                        nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
                        idx++;
                }
                rcu_read_unlock();
        }
done:
        cb->args[0] = h;
        cb->args[1] = idx;

        return skb->len;
}

#define MPLS_PERDEV_SYSCTL_OFFSET(field)        \
        (&((struct mpls_dev *)0)->field)

static int mpls_conf_proc(struct ctl_table *ctl, int write,
                          void __user *buffer,
                          size_t *lenp, loff_t *ppos)
{
        int oval = *(int *)ctl->data;
        int ret = proc_dointvec(ctl, write, buffer, lenp, ppos);

        if (write) {
                struct mpls_dev *mdev = ctl->extra1;
                int i = (int *)ctl->data - (int *)mdev;
                struct net *net = ctl->extra2;
                int val = *(int *)ctl->data;

                if (i == offsetof(struct mpls_dev, input_enabled) &&
                    val != oval) {
                        mpls_netconf_notify_devconf(net, RTM_NEWNETCONF,
                                                    NETCONFA_INPUT, mdev);
                }
        }

        return ret;
}

static const struct ctl_table mpls_dev_table[] = {
        {
                .procname       = "input",
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = mpls_conf_proc,
                .data           = MPLS_PERDEV_SYSCTL_OFFSET(input_enabled),
        },
        { }
};

static int mpls_dev_sysctl_register(struct net_device *dev,
                                    struct mpls_dev *mdev)
{
        char path[sizeof("net/mpls/conf/") + IFNAMSIZ];
        struct net *net = dev_net(dev);
        struct ctl_table *table;
        int i;

        table = kmemdup(&mpls_dev_table, sizeof(mpls_dev_table), GFP_KERNEL);
        if (!table)
                goto out;

        /* Table data contains only offsets relative to the base of
         * the mdev at this point, so make them absolute.
         */
        for (i = 0; i < ARRAY_SIZE(mpls_dev_table); i++) {
                table[i].data = (char *)mdev + (uintptr_t)table[i].data;
                table[i].extra1 = mdev;
                table[i].extra2 = net;
        }

        snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name);

        mdev->sysctl = register_net_sysctl(net, path, table);
        if (!mdev->sysctl)
                goto free;

        mpls_netconf_notify_devconf(net, RTM_NEWNETCONF, NETCONFA_ALL, mdev);
        return 0;

free:
        kfree(table);
out:
        return -ENOBUFS;
}

static void mpls_dev_sysctl_unregister(struct net_device *dev,
                                       struct mpls_dev *mdev)
{
        struct net *net = dev_net(dev);
        struct ctl_table *table;

        table = mdev->sysctl->ctl_table_arg;
        unregister_net_sysctl_table(mdev->sysctl);
        kfree(table);

        mpls_netconf_notify_devconf(net, RTM_DELNETCONF, 0, mdev);
}

static struct mpls_dev *mpls_add_dev(struct net_device *dev)
{
        struct mpls_dev *mdev;
        int err = -ENOMEM;
        int i;

        ASSERT_RTNL();

        mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
        if (!mdev)
                return ERR_PTR(err);

        mdev->stats = alloc_percpu(struct mpls_pcpu_stats);
        if (!mdev->stats)
                goto free;

        for_each_possible_cpu(i) {
                struct mpls_pcpu_stats *mpls_stats;

                mpls_stats = per_cpu_ptr(mdev->stats, i);
                u64_stats_init(&mpls_stats->syncp);
        }

        mdev->dev = dev;

        err = mpls_dev_sysctl_register(dev, mdev);
        if (err)
                goto free;

        rcu_assign_pointer(dev->mpls_ptr, mdev);

        return mdev;

free:
        free_percpu(mdev->stats);
        kfree(mdev);
        return ERR_PTR(err);
}

static void mpls_dev_destroy_rcu(struct rcu_head *head)
{
        struct mpls_dev *mdev = container_of(head, struct mpls_dev, rcu);

        free_percpu(mdev->stats);
        kfree(mdev);
}

static void mpls_ifdown(struct net_device *dev, int event)
{
        struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
        u8 alive, deleted;
        unsigned index;

        platform_label = rtnl_dereference(net->mpls.platform_label);
        for (index = 0; index < net->mpls.platform_labels; index++) {
                struct mpls_route *rt = rtnl_dereference(platform_label[index]);

                if (!rt)
                        continue;

                alive = 0;
                deleted = 0;
                change_nexthops(rt) {
                        unsigned int nh_flags = nh->nh_flags;

                        if (rtnl_dereference(nh->nh_dev) != dev)
                                goto next;

                        switch (event) {
                        case NETDEV_DOWN:
                        case NETDEV_UNREGISTER:
                                nh_flags |= RTNH_F_DEAD;
                                /* fall through */
                        case NETDEV_CHANGE:
                                nh_flags |= RTNH_F_LINKDOWN;
                                break;
                        }
                        if (event == NETDEV_UNREGISTER)
                                RCU_INIT_POINTER(nh->nh_dev, NULL);

                        if (nh->nh_flags != nh_flags)
                                WRITE_ONCE(nh->nh_flags, nh_flags);
next:
                        if (!(nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)))
                                alive++;
                        if (!rtnl_dereference(nh->nh_dev))
                                deleted++;
                } endfor_nexthops(rt);

                WRITE_ONCE(rt->rt_nhn_alive, alive);

                /* if there are no more nexthops, delete the route */
                if (event == NETDEV_UNREGISTER && deleted == rt->rt_nhn)
                        mpls_route_update(net, index, NULL, NULL);
        }
}

static void mpls_ifup(struct net_device *dev, unsigned int flags)
{
        struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
        unsigned index;
        u8 alive;

        platform_label = rtnl_dereference(net->mpls.platform_label);
        for (index = 0; index < net->mpls.platform_labels; index++) {
                struct mpls_route *rt = rtnl_dereference(platform_label[index]);

                if (!rt)
                        continue;

                alive = 0;
                change_nexthops(rt) {
                        unsigned int nh_flags = nh->nh_flags;
                        struct net_device *nh_dev =
                                rtnl_dereference(nh->nh_dev);

                        if (!(nh_flags & flags)) {
                                alive++;
                                continue;
                        }
                        if (nh_dev != dev)
                                continue;
                        alive++;
                        nh_flags &= ~flags;
                        WRITE_ONCE(nh->nh_flags, nh_flags);
                } endfor_nexthops(rt);

                WRITE_ONCE(rt->rt_nhn_alive, alive);
        }
}

static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
                           void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct mpls_dev *mdev;
        unsigned int flags;

        if (event == NETDEV_REGISTER) {
                /* For now just support Ethernet, IPGRE, SIT and IPIP devices */
                if (dev->type == ARPHRD_ETHER ||
                    dev->type == ARPHRD_LOOPBACK ||
                    dev->type == ARPHRD_IPGRE ||
                    dev->type == ARPHRD_SIT ||
                    dev->type == ARPHRD_TUNNEL) {
                        mdev = mpls_add_dev(dev);
                        if (IS_ERR(mdev))
                                return notifier_from_errno(PTR_ERR(mdev));
                }
                return NOTIFY_OK;
        }

        mdev = mpls_dev_get(dev);
        if (!mdev)
                return NOTIFY_OK;

        switch (event) {
        case NETDEV_DOWN:
                mpls_ifdown(dev, event);
                break;
        case NETDEV_UP:
                flags = dev_get_flags(dev);
                if (flags & (IFF_RUNNING | IFF_LOWER_UP))
                        mpls_ifup(dev, RTNH_F_DEAD | RTNH_F_LINKDOWN);
                else
                        mpls_ifup(dev, RTNH_F_DEAD);
                break;
        case NETDEV_CHANGE:
                flags = dev_get_flags(dev);
                if (flags & (IFF_RUNNING | IFF_LOWER_UP))
                        mpls_ifup(dev, RTNH_F_DEAD | RTNH_F_LINKDOWN);
                else
                        mpls_ifdown(dev, event);
                break;
        case NETDEV_UNREGISTER:
                mpls_ifdown(dev, event);
                mdev = mpls_dev_get(dev);
                if (mdev) {
                        mpls_dev_sysctl_unregister(dev, mdev);
                        RCU_INIT_POINTER(dev->mpls_ptr, NULL);
                        call_rcu(&mdev->rcu, mpls_dev_destroy_rcu);
                }
                break;
        case NETDEV_CHANGENAME:
                mdev = mpls_dev_get(dev);
                if (mdev) {
                        int err;

                        mpls_dev_sysctl_unregister(dev, mdev);
                        err = mpls_dev_sysctl_register(dev, mdev);
                        if (err)
                                return notifier_from_errno(err);
                }
                break;
        }
        return NOTIFY_OK;
}

static struct notifier_block mpls_dev_notifier = {
        .notifier_call = mpls_dev_notify,
};

static int nla_put_via(struct sk_buff *skb,
                       u8 table, const void *addr, int alen)
{
        static const int table_to_family[NEIGH_NR_TABLES + 1] = {
                AF_INET, AF_INET6, AF_DECnet, AF_PACKET,
        };
        struct nlattr *nla;
        struct rtvia *via;
        int family = AF_UNSPEC;

        nla = nla_reserve(skb, RTA_VIA, alen + 2);
        if (!nla)
                return -EMSGSIZE;

        if (table <= NEIGH_NR_TABLES)
                family = table_to_family[table];

        via = nla_data(nla);
        via->rtvia_family = family;
        memcpy(via->rtvia_addr, addr, alen);
        return 0;
}

int nla_put_labels(struct sk_buff *skb, int attrtype,
                   u8 labels, const u32 label[])
{
        struct nlattr *nla;
        struct mpls_shim_hdr *nla_label;
        bool bos;
        int i;
        nla = nla_reserve(skb, attrtype, labels*4);
        if (!nla)
                return -EMSGSIZE;

        nla_label = nla_data(nla);
        bos = true;
        for (i = labels - 1; i >= 0; i--) {
                nla_label[i] = mpls_entry_encode(label[i], 0, 0, bos);
                bos = false;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(nla_put_labels);

int nla_get_labels(const struct nlattr *nla,
                   u8 max_labels, u8 *labels, u32 label[])
{
        unsigned len = nla_len(nla);
        struct mpls_shim_hdr *nla_label;
        u8 nla_labels;
        bool bos;
        int i;

        /* len needs to be an even multiple of 4 (the label size). Number
         * of labels is a u8 so check for overflow.
         */
        if (len & 3 || len / 4 > 255)
                return -EINVAL;

        /* Limit the number of new labels allowed */
        nla_labels = len/4;
        if (nla_labels > max_labels)
                return -EINVAL;

        /* when label == NULL, caller wants number of labels */
        if (!label)
                goto out;

        nla_label = nla_data(nla);
        bos = true;
        for (i = nla_labels - 1; i >= 0; i--, bos = false) {
                struct mpls_entry_decoded dec;
                dec = mpls_entry_decode(nla_label + i);

                /* Ensure the bottom of stack flag is properly set
                 * and ttl and tc are both clear.
                 */
                if ((dec.bos != bos) || dec.ttl || dec.tc)
                        return -EINVAL;

                switch (dec.label) {
                case MPLS_LABEL_IMPLNULL:
                        /* RFC3032: This is a label that an LSR may
                         * assign and distribute, but which never
                         * actually appears in the encapsulation.
                         */
                        return -EINVAL;
                }

                label[i] = dec.label;
        }
out:
        *labels = nla_labels;
        return 0;
}
EXPORT_SYMBOL_GPL(nla_get_labels);

int nla_get_via(const struct nlattr *nla, u8 *via_alen,
                u8 *via_table, u8 via_addr[])
{
        struct rtvia *via = nla_data(nla);
        int err = -EINVAL;
        int alen;

        if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr))
                goto errout;
        alen = nla_len(nla) -
                        offsetof(struct rtvia, rtvia_addr);
        if (alen > MAX_VIA_ALEN)
                goto errout;

        /* Validate the address family */
        switch (via->rtvia_family) {
        case AF_PACKET:
                *via_table = NEIGH_LINK_TABLE;
                break;
        case AF_INET:
                *via_table = NEIGH_ARP_TABLE;
                if (alen != 4)
                        goto errout;
                break;
        case AF_INET6:
                *via_table = NEIGH_ND_TABLE;
                if (alen != 16)
                        goto errout;
                break;
        default:
                /* Unsupported address family */
                goto errout;
        }

        memcpy(via_addr, via->rtvia_addr, alen);
        *via_alen = alen;
        err = 0;

errout:
        return err;
}

static int rtm_to_route_config(struct sk_buff *skb,  struct nlmsghdr *nlh,
                               struct mpls_route_config *cfg)
{
        struct rtmsg *rtm;
        struct nlattr *tb[RTA_MAX+1];
        int index;
        int err;

        err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_mpls_policy,
                          NULL);
        if (err < 0)
                goto errout;

        err = -EINVAL;
        rtm = nlmsg_data(nlh);

        if (rtm->rtm_family != AF_MPLS)
                goto errout;
        if (rtm->rtm_dst_len != 20)
                goto errout;
        if (rtm->rtm_src_len != 0)
                goto errout;
        if (rtm->rtm_tos != 0)
                goto errout;
        if (rtm->rtm_table != RT_TABLE_MAIN)
                goto errout;
        /* Any value is acceptable for rtm_protocol */

        /* As mpls uses destination specific addresses
         * (or source specific address in the case of multicast)
         * all addresses have universal scope.
         */
        if (rtm->rtm_scope != RT_SCOPE_UNIVERSE)
                goto errout;
        if (rtm->rtm_type != RTN_UNICAST)
                goto errout;
        if (rtm->rtm_flags != 0)
                goto errout;

        cfg->rc_label           = LABEL_NOT_SPECIFIED;
        cfg->rc_protocol        = rtm->rtm_protocol;
        cfg->rc_via_table       = MPLS_NEIGH_TABLE_UNSPEC;
        cfg->rc_ttl_propagate   = MPLS_TTL_PROP_DEFAULT;
        cfg->rc_nlflags         = nlh->nlmsg_flags;
        cfg->rc_nlinfo.portid   = NETLINK_CB(skb).portid;
        cfg->rc_nlinfo.nlh      = nlh;
        cfg->rc_nlinfo.nl_net   = sock_net(skb->sk);

        for (index = 0; index <= RTA_MAX; index++) {
                struct nlattr *nla = tb[index];
                if (!nla)
                        continue;

                switch (index) {
                case RTA_OIF:
                        cfg->rc_ifindex = nla_get_u32(nla);
                        break;
                case RTA_NEWDST:
                        if (nla_get_labels(nla, MAX_NEW_LABELS,
                                           &cfg->rc_output_labels,
                                           cfg->rc_output_label))
                                goto errout;
                        break;
                case RTA_DST:
                {
                        u8 label_count;
                        if (nla_get_labels(nla, 1, &label_count,
                                           &cfg->rc_label))
                                goto errout;

                        /* Reserved labels may not be set */
                        if (cfg->rc_label < MPLS_LABEL_FIRST_UNRESERVED)
                                goto errout;

                        break;
                }
                case RTA_VIA:
                {
                        if (nla_get_via(nla, &cfg->rc_via_alen,
                                        &cfg->rc_via_table, cfg->rc_via))
                                goto errout;
                        break;
                }
                case RTA_MULTIPATH:
                {
                        cfg->rc_mp = nla_data(nla);
                        cfg->rc_mp_len = nla_len(nla);
                        break;
                }
                case RTA_TTL_PROPAGATE:
                {
                        u8 ttl_propagate = nla_get_u8(nla);

                        if (ttl_propagate > 1)
                                goto errout;
                        cfg->rc_ttl_propagate = ttl_propagate ?
                                MPLS_TTL_PROP_ENABLED :
                                MPLS_TTL_PROP_DISABLED;
                        break;
                }
                default:
                        /* Unsupported attribute */
                        goto errout;
                }
        }

        err = 0;
errout:
        return err;
}

static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        struct mpls_route_config *cfg;
        int err;

        cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
        if (!cfg)
                return -ENOMEM;

        err = rtm_to_route_config(skb, nlh, cfg);
        if (err < 0)
                goto out;

        err = mpls_route_del(cfg);
out:
        kfree(cfg);

        return err;
}


static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        struct mpls_route_config *cfg;
        int err;

        cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
        if (!cfg)
                return -ENOMEM;

        err = rtm_to_route_config(skb, nlh, cfg);
        if (err < 0)
                goto out;

        err = mpls_route_add(cfg);
out:
        kfree(cfg);

        return err;
}

static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
                           u32 label, struct mpls_route *rt, int flags)
{
        struct net_device *dev;
        struct nlmsghdr *nlh;
        struct rtmsg *rtm;

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

        rtm = nlmsg_data(nlh);
        rtm->rtm_family = AF_MPLS;
        rtm->rtm_dst_len = 20;
        rtm->rtm_src_len = 0;
        rtm->rtm_tos = 0;
        rtm->rtm_table = RT_TABLE_MAIN;
        rtm->rtm_protocol = rt->rt_protocol;
        rtm->rtm_scope = RT_SCOPE_UNIVERSE;
        rtm->rtm_type = RTN_UNICAST;
        rtm->rtm_flags = 0;

        if (nla_put_labels(skb, RTA_DST, 1, &label))
                goto nla_put_failure;

        if (rt->rt_ttl_propagate != MPLS_TTL_PROP_DEFAULT) {
                bool ttl_propagate =
                        rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED;

                if (nla_put_u8(skb, RTA_TTL_PROPAGATE,
                               ttl_propagate))
                        goto nla_put_failure;
        }
        if (rt->rt_nhn == 1) {
                const struct mpls_nh *nh = rt->rt_nh;

                if (nh->nh_labels &&
                    nla_put_labels(skb, RTA_NEWDST, nh->nh_labels,
                                   nh->nh_label))
                        goto nla_put_failure;
                if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC &&
                    nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh),
                                nh->nh_via_alen))
                        goto nla_put_failure;
                dev = rtnl_dereference(nh->nh_dev);
                if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
                        goto nla_put_failure;
                if (nh->nh_flags & RTNH_F_LINKDOWN)
                        rtm->rtm_flags |= RTNH_F_LINKDOWN;
                if (nh->nh_flags & RTNH_F_DEAD)
                        rtm->rtm_flags |= RTNH_F_DEAD;
        } else {
                struct rtnexthop *rtnh;
                struct nlattr *mp;
                u8 linkdown = 0;
                u8 dead = 0;

                mp = nla_nest_start(skb, RTA_MULTIPATH);
                if (!mp)
                        goto nla_put_failure;

                for_nexthops(rt) {
                        dev = rtnl_dereference(nh->nh_dev);
                        if (!dev)
                                continue;

                        rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
                        if (!rtnh)
                                goto nla_put_failure;

                        rtnh->rtnh_ifindex = dev->ifindex;
                        if (nh->nh_flags & RTNH_F_LINKDOWN) {
                                rtnh->rtnh_flags |= RTNH_F_LINKDOWN;
                                linkdown++;
                        }
                        if (nh->nh_flags & RTNH_F_DEAD) {
                                rtnh->rtnh_flags |= RTNH_F_DEAD;
                                dead++;
                        }

                        if (nh->nh_labels && nla_put_labels(skb, RTA_NEWDST,
                                                            nh->nh_labels,
                                                            nh->nh_label))
                                goto nla_put_failure;
                        if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC &&
                            nla_put_via(skb, nh->nh_via_table,
                                        mpls_nh_via(rt, nh),
                                        nh->nh_via_alen))
                                goto nla_put_failure;

                        /* length of rtnetlink header + attributes */
                        rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
                } endfor_nexthops(rt);

                if (linkdown == rt->rt_nhn)
                        rtm->rtm_flags |= RTNH_F_LINKDOWN;
                if (dead == rt->rt_nhn)
                        rtm->rtm_flags |= RTNH_F_DEAD;

                nla_nest_end(skb, mp);
        }

        nlmsg_end(skb, nlh);
        return 0;

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

static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        struct mpls_route __rcu **platform_label;
        size_t platform_labels;
        unsigned int index;

        ASSERT_RTNL();

        index = cb->args[0];
        if (index < MPLS_LABEL_FIRST_UNRESERVED)
                index = MPLS_LABEL_FIRST_UNRESERVED;

        platform_label = rtnl_dereference(net->mpls.platform_label);
        platform_labels = net->mpls.platform_labels;
        for (; index < platform_labels; index++) {
                struct mpls_route *rt;
                rt = rtnl_dereference(platform_label[index]);
                if (!rt)
                        continue;

                if (mpls_dump_route(skb, NETLINK_CB(cb->skb).portid,
                                    cb->nlh->nlmsg_seq, RTM_NEWROUTE,
                                    index, rt, NLM_F_MULTI) < 0)
                        break;
        }
        cb->args[0] = index;

        return skb->len;
}

static inline size_t lfib_nlmsg_size(struct mpls_route *rt)
{
        size_t payload =
                NLMSG_ALIGN(sizeof(struct rtmsg))
                + nla_total_size(4)                     /* RTA_DST */
                + nla_total_size(1);                    /* RTA_TTL_PROPAGATE */

        if (rt->rt_nhn == 1) {
                struct mpls_nh *nh = rt->rt_nh;

                if (nh->nh_dev)
                        payload += nla_total_size(4); /* RTA_OIF */
                if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC) /* RTA_VIA */
                        payload += nla_total_size(2 + nh->nh_via_alen);
                if (nh->nh_labels) /* RTA_NEWDST */
                        payload += nla_total_size(nh->nh_labels * 4);
        } else {
                /* each nexthop is packed in an attribute */
                size_t nhsize = 0;

                for_nexthops(rt) {
                        if (!rtnl_dereference(nh->nh_dev))
                                continue;
                        nhsize += nla_total_size(sizeof(struct rtnexthop));
                        /* RTA_VIA */
                        if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC)
                                nhsize += nla_total_size(2 + nh->nh_via_alen);
                        if (nh->nh_labels)
                                nhsize += nla_total_size(nh->nh_labels * 4);
                } endfor_nexthops(rt);
                /* nested attribute */
                payload += nla_total_size(nhsize);
        }

        return payload;
}

static void rtmsg_lfib(int event, u32 label, struct mpls_route *rt,
                       struct nlmsghdr *nlh, struct net *net, u32 portid,
                       unsigned int nlm_flags)
{
        struct sk_buff *skb;
        u32 seq = nlh ? nlh->nlmsg_seq : 0;
        int err = -ENOBUFS;

        skb = nlmsg_new(lfib_nlmsg_size(rt), GFP_KERNEL);
        if (skb == NULL)
                goto errout;

        err = mpls_dump_route(skb, portid, seq, event, label, rt, nlm_flags);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in lfib_nlmsg_size */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }
        rtnl_notify(skb, net, portid, RTNLGRP_MPLS_ROUTE, nlh, GFP_KERNEL);

        return;
errout:
        if (err < 0)
                rtnl_set_sk_err(net, RTNLGRP_MPLS_ROUTE, err);
}

static int resize_platform_label_table(struct net *net, size_t limit)
{
        size_t size = sizeof(struct mpls_route *) * limit;

        size_t old_limit;
        size_t cp_size;
        struct mpls_route __rcu **labels = NULL, **old;
        struct mpls_route *rt0 = NULL, *rt2 = NULL;
        unsigned index;

        if (size) {
                labels = kvzalloc(size, GFP_KERNEL);
                if (!labels)
                        goto nolabels;
        }

        /* In case the predefined labels need to be populated */
        if (limit > MPLS_LABEL_IPV4NULL) {
                struct net_device *lo = net->loopback_dev;
                rt0 = mpls_rt_alloc(1, lo->addr_len, 0);
                if (IS_ERR(rt0))
                        goto nort0;
                RCU_INIT_POINTER(rt0->rt_nh->nh_dev, lo);
                rt0->rt_protocol = RTPROT_KERNEL;
                rt0->rt_payload_type = MPT_IPV4;
                rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
                rt0->rt_nh->nh_via_table = NEIGH_LINK_TABLE;
                rt0->rt_nh->nh_via_alen = lo->addr_len;
                memcpy(__mpls_nh_via(rt0, rt0->rt_nh), lo->dev_addr,
                       lo->addr_len);
        }
        if (limit > MPLS_LABEL_IPV6NULL) {
                struct net_device *lo = net->loopback_dev;
                rt2 = mpls_rt_alloc(1, lo->addr_len, 0);
                if (IS_ERR(rt2))
                        goto nort2;
                RCU_INIT_POINTER(rt2->rt_nh->nh_dev, lo);
                rt2->rt_protocol = RTPROT_KERNEL;
                rt2->rt_payload_type = MPT_IPV6;
                rt2->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
                rt2->rt_nh->nh_via_table = NEIGH_LINK_TABLE;
                rt2->rt_nh->nh_via_alen = lo->addr_len;
                memcpy(__mpls_nh_via(rt2, rt2->rt_nh), lo->dev_addr,
                       lo->addr_len);
        }

        rtnl_lock();
        /* Remember the original table */
        old = rtnl_dereference(net->mpls.platform_label);
        old_limit = net->mpls.platform_labels;

        /* Free any labels beyond the new table */
        for (index = limit; index < old_limit; index++)
                mpls_route_update(net, index, NULL, NULL);

        /* Copy over the old labels */
        cp_size = size;
        if (old_limit < limit)
                cp_size = old_limit * sizeof(struct mpls_route *);

        memcpy(labels, old, cp_size);

        /* If needed set the predefined labels */
        if ((old_limit <= MPLS_LABEL_IPV6NULL) &&
            (limit > MPLS_LABEL_IPV6NULL)) {
                RCU_INIT_POINTER(labels[MPLS_LABEL_IPV6NULL], rt2);
                rt2 = NULL;
        }

        if ((old_limit <= MPLS_LABEL_IPV4NULL) &&
            (limit > MPLS_LABEL_IPV4NULL)) {
                RCU_INIT_POINTER(labels[MPLS_LABEL_IPV4NULL], rt0);
                rt0 = NULL;
        }

        /* Update the global pointers */
        net->mpls.platform_labels = limit;
        rcu_assign_pointer(net->mpls.platform_label, labels);

        rtnl_unlock();

        mpls_rt_free(rt2);
        mpls_rt_free(rt0);

        if (old) {
                synchronize_rcu();
                kvfree(old);
        }
        return 0;

nort2:
        mpls_rt_free(rt0);
nort0:
        kvfree(labels);
nolabels:
        return -ENOMEM;
}

static int mpls_platform_labels(struct ctl_table *table, int write,
                                void __user *buffer, size_t *lenp, loff_t *ppos)
{
        struct net *net = table->data;
        int platform_labels = net->mpls.platform_labels;
        int ret;
        struct ctl_table tmp = {
                .procname       = table->procname,
                .data           = &platform_labels,
                .maxlen         = sizeof(int),
                .mode           = table->mode,
                .extra1         = &zero,
                .extra2         = &label_limit,
        };

        ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);

        if (write && ret == 0)
                ret = resize_platform_label_table(net, platform_labels);

        return ret;
}

#define MPLS_NS_SYSCTL_OFFSET(field)            \
        (&((struct net *)0)->field)

static const struct ctl_table mpls_table[] = {
        {
                .procname       = "platform_labels",
                .data           = NULL,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = mpls_platform_labels,
        },
        {
                .procname       = "ip_ttl_propagate",
                .data           = MPLS_NS_SYSCTL_OFFSET(mpls.ip_ttl_propagate),
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &zero,
                .extra2         = &one,
        },
        {
                .procname       = "default_ttl",
                .data           = MPLS_NS_SYSCTL_OFFSET(mpls.default_ttl),
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &one,
                .extra2         = &ttl_max,
        },
        { }
};

static int mpls_net_init(struct net *net)
{
        struct ctl_table *table;
        int i;

        net->mpls.platform_labels = 0;
        net->mpls.platform_label = NULL;
        net->mpls.ip_ttl_propagate = 1;
        net->mpls.default_ttl = 255;

        table = kmemdup(mpls_table, sizeof(mpls_table), GFP_KERNEL);
        if (table == NULL)
                return -ENOMEM;

        /* Table data contains only offsets relative to the base of
         * the mdev at this point, so make them absolute.
         */
        for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
                table[i].data = (char *)net + (uintptr_t)table[i].data;

        net->mpls.ctl = register_net_sysctl(net, "net/mpls", table);
        if (net->mpls.ctl == NULL) {
                kfree(table);
                return -ENOMEM;
        }

        return 0;
}

static void mpls_net_exit(struct net *net)
{
        struct mpls_route __rcu **platform_label;
        size_t platform_labels;
        struct ctl_table *table;
        unsigned int index;

        table = net->mpls.ctl->ctl_table_arg;
        unregister_net_sysctl_table(net->mpls.ctl);
        kfree(table);

        /* An rcu grace period has passed since there was a device in
         * the network namespace (and thus the last in flight packet)
         * left this network namespace.  This is because
         * unregister_netdevice_many and netdev_run_todo has completed
         * for each network device that was in this network namespace.
         *
         * As such no additional rcu synchronization is necessary when
         * freeing the platform_label table.
         */
        rtnl_lock();
        platform_label = rtnl_dereference(net->mpls.platform_label);
        platform_labels = net->mpls.platform_labels;
        for (index = 0; index < platform_labels; index++) {
                struct mpls_route *rt = rtnl_dereference(platform_label[index]);
                RCU_INIT_POINTER(platform_label[index], NULL);
                mpls_notify_route(net, index, rt, NULL, NULL);
                mpls_rt_free(rt);
        }
        rtnl_unlock();

        kvfree(platform_label);
}

static struct pernet_operations mpls_net_ops = {
        .init = mpls_net_init,
        .exit = mpls_net_exit,
};

static struct rtnl_af_ops mpls_af_ops __read_mostly = {
        .family            = AF_MPLS,
        .fill_stats_af     = mpls_fill_stats_af,
        .get_stats_af_size = mpls_get_stats_af_size,
};

static int __init mpls_init(void)
{
        int err;

        BUILD_BUG_ON(sizeof(struct mpls_shim_hdr) != 4);

        err = register_pernet_subsys(&mpls_net_ops);
        if (err)
                goto out;

        err = register_netdevice_notifier(&mpls_dev_notifier);
        if (err)
                goto out_unregister_pernet;

        dev_add_pack(&mpls_packet_type);

        rtnl_af_register(&mpls_af_ops);

        rtnl_register(PF_MPLS, RTM_NEWROUTE, mpls_rtm_newroute, NULL, NULL);
        rtnl_register(PF_MPLS, RTM_DELROUTE, mpls_rtm_delroute, NULL, NULL);
        rtnl_register(PF_MPLS, RTM_GETROUTE, NULL, mpls_dump_routes, NULL);
        rtnl_register(PF_MPLS, RTM_GETNETCONF, mpls_netconf_get_devconf,
                      mpls_netconf_dump_devconf, NULL);
        err = 0;
out:
        return err;

out_unregister_pernet:
        unregister_pernet_subsys(&mpls_net_ops);
        goto out;
}
module_init(mpls_init);

static void __exit mpls_exit(void)
{
        rtnl_unregister_all(PF_MPLS);
        rtnl_af_unregister(&mpls_af_ops);
        dev_remove_pack(&mpls_packet_type);
        unregister_netdevice_notifier(&mpls_dev_notifier);
        unregister_pernet_subsys(&mpls_net_ops);
}
module_exit(mpls_exit);

MODULE_DESCRIPTION("MultiProtocol Label Switching");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_NETPROTO(PF_MPLS);