#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/vmalloc.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>
#include "internal.h"

#define LABEL_NOT_SPECIFIED (1<<20)
#define MAX_NEW_LABELS 2

/* This maximum ha length copied from the definition of struct neighbour */
#define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, sizeof(unsigned long)))

struct mpls_route { /* next hop label forwarding entry */
        struct net_device __rcu *rt_dev;
        struct rcu_head         rt_rcu;
        u32                     rt_label[MAX_NEW_LABELS];
        u8                      rt_protocol; /* routing protocol that set this entry */
        u8                      rt_labels;
        u8                      rt_via_alen;
        u8                      rt_via_table;
        u8                      rt_via[0];
};

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

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;
}

static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
{
        return rcu_dereference_rtnl(dev->mpls_ptr);
}

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

static unsigned int mpls_rt_header_size(const struct mpls_route *rt)
{
        /* The size of the layer 2.5 labels to be added for this route */
        return rt->rt_labels * sizeof(struct mpls_shim_hdr);
}

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

static 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_network_seglen(skb) <= mtu)
                return false;

        return true;
}

static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
                        struct mpls_entry_decoded dec)
{
        /* RFC4385 and RFC5586 encode other packets in mpls such that
         * they don't conflict with the ip version number, making
         * decoding by examining the ip version correct in everything
         * except for the strangest cases.
         *
         * The strange cases if we choose to support them will require
         * manual configuration.
         */
        struct iphdr *hdr4;
        bool success = true;

        /* 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;

        /* Use ip_hdr to find the ip protocol version */
        hdr4 = ip_hdr(skb);
        if (hdr4->version == 4) {
                skb->protocol = htons(ETH_P_IP);
                csum_replace2(&hdr4->check,
                              htons(hdr4->ttl << 8),
                              htons(dec.ttl << 8));
                hdr4->ttl = dec.ttl;
        }
        else if (hdr4->version == 6) {
                struct ipv6hdr *hdr6 = ipv6_hdr(skb);
                skb->protocol = htons(ETH_P_IPV6);
                hdr6->hop_limit = dec.ttl;
        }
        else
                /* version 0 and version 1 are used by pseudo wires */
                success = false;
        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_entry_decoded dec;
        struct net_device *out_dev;
        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 || !mdev->input_enabled)
                goto drop;

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

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

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

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

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

        skb_orphan(skb);

        rt = mpls_route_input_rcu(net, dec.label);
        if (!rt)
                goto drop;

        /* Find the output device */
        out_dev = rcu_dereference(rt->rt_dev);
        if (!mpls_output_possible(out_dev))
                goto drop;

        if (skb_warn_if_lro(skb))
                goto drop;

        skb_forward_csum(skb);

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

        /* Verify the destination can hold the packet */
        new_header_size = mpls_rt_header_size(rt);
        mtu = mpls_dev_mtu(out_dev);
        if (mpls_pkt_too_big(skb, mtu - new_header_size))
                goto drop;

        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 drop;

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

        if (unlikely(!new_header_size && dec.bos)) {
                /* Penultimate hop popping */
                if (!mpls_egress(rt, skb, dec))
                        goto drop;
        } 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 = rt->rt_labels - 1; i >= 0; i--) {
                        hdr[i] = mpls_entry_encode(rt->rt_label[i], dec.ttl, 0, bos);
                        bos = false;
                }
        }

        err = neigh_xmit(rt->rt_via_table, out_dev, rt->rt_via, skb);
        if (err)
                net_dbg_ratelimited("%s: packet transmission failed: %d\n",
                                    __func__, err);
        return 0;

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 },
};

struct mpls_route_config {
        u32             rc_protocol;
        u32             rc_ifindex;
        u16             rc_via_table;
        u16             rc_via_alen;
        u8              rc_via[MAX_VIA_ALEN];
        u32             rc_label;
        u32             rc_output_labels;
        u32             rc_output_label[MAX_NEW_LABELS];
        u32             rc_nlflags;
        struct nl_info  rc_nlinfo;
};

static struct mpls_route *mpls_rt_alloc(size_t alen)
{
        struct mpls_route *rt;

        rt = kzalloc(sizeof(*rt) + alen, GFP_KERNEL);
        if (rt)
                rt->rt_via_alen = alen;
        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 >= 16))
                rtmsg_lfib(event, index, rt, nlh, net, portid, nlm_flags);
}

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

        ASSERT_RTNL();

        platform_label = rtnl_dereference(net->mpls.platform_label);
        rt = rtnl_dereference(platform_label[index]);
        if (!dev || (rt && (rtnl_dereference(rt->rt_dev) == dev))) {
                rcu_assign_pointer(platform_label[index], new);
                old = rt;
        }

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

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

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 = 16; index < platform_labels; index++) {
                if (!rtnl_dereference(platform_label[index]))
                        return index;
        }
        return LABEL_NOT_SPECIFIED;
}

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 net_device *dev = NULL;
        struct mpls_route *rt, *old;
        unsigned index;
        int i;
        int err = -EINVAL;

        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);
        }

        /* The first 16 labels are reserved, and may not be set */
        if (index < 16)
                goto errout;

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

        /* Ensure only a supported number of labels are present */
        if (cfg->rc_output_labels > MAX_NEW_LABELS)
                goto errout;

        err = -ENODEV;
        dev = dev_get_by_index(net, cfg->rc_ifindex);
        if (!dev)
                goto errout;

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

        err = -EINVAL;
        if ((cfg->rc_via_table == NEIGH_LINK_TABLE) &&
            (dev->addr_len != cfg->rc_via_alen))
                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 = -ENOMEM;
        rt = mpls_rt_alloc(cfg->rc_via_alen);
        if (!rt)
                goto errout;

        rt->rt_labels = cfg->rc_output_labels;
        for (i = 0; i < rt->rt_labels; i++)
                rt->rt_label[i] = cfg->rc_output_label[i];
        rt->rt_protocol = cfg->rc_protocol;
        RCU_INIT_POINTER(rt->rt_dev, dev);
        rt->rt_via_table = cfg->rc_via_table;
        memcpy(rt->rt_via, cfg->rc_via, cfg->rc_via_alen);

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

        dev_put(dev);
        return 0;

errout:
        if (dev)
                dev_put(dev);
        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;

        /* The first 16 labels are reserved, and may not be removed */
        if (index < 16)
                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, NULL, &cfg->rc_nlinfo);

        err = 0;
errout:
        return err;
}

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

static const struct ctl_table mpls_dev_table[] = {
        {
                .procname       = "input",
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
                .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 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;

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

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

        return 0;

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

static void mpls_dev_sysctl_unregister(struct mpls_dev *mdev)
{
        struct ctl_table *table;

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

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

        ASSERT_RTNL();

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

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

        rcu_assign_pointer(dev->mpls_ptr, mdev);

        return mdev;

free:
        kfree(mdev);
        return ERR_PTR(err);
}

static void mpls_ifdown(struct net_device *dev)
{
        struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
        struct mpls_dev *mdev;
        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;
                if (rtnl_dereference(rt->rt_dev) != dev)
                        continue;
                rt->rt_dev = NULL;
        }

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

        mpls_dev_sysctl_unregister(mdev);

        RCU_INIT_POINTER(dev->mpls_ptr, NULL);

        kfree_rcu(mdev, rcu);
}

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;

        switch(event) {
        case NETDEV_REGISTER:
                /* For now just support ethernet devices */
                if ((dev->type == ARPHRD_ETHER) ||
                    (dev->type == ARPHRD_LOOPBACK)) {
                        mdev = mpls_add_dev(dev);
                        if (IS_ERR(mdev))
                                return notifier_from_errno(PTR_ERR(mdev));
                }
                break;

        case NETDEV_UNREGISTER:
                mpls_ifdown(dev);
                break;
        case NETDEV_CHANGENAME:
                mdev = mpls_dev_get(dev);
                if (mdev) {
                        int err;

                        mpls_dev_sysctl_unregister(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;
}

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

        /* len needs to be an even multiple of 4 (the label size) */
        if (len & 3)
                return -EINVAL;

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

        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;
        }
        *labels = nla_labels;
        return 0;
}

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);
        if (err < 0)
                goto errout;

        err = -EINVAL;
        rtm = nlmsg_data(nlh);
        memset(cfg, 0, sizeof(*cfg));

        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_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:
                {
                        u32 label_count;
                        if (nla_get_labels(nla, 1, &label_count,
                                           &cfg->rc_label))
                                goto errout;

                        /* The first 16 labels are reserved, and may not be set */
                        if (cfg->rc_label < 16)
                                goto errout;

                        break;
                }
                case RTA_VIA:
                {
                        struct rtvia *via = nla_data(nla);
                        if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr))
                                goto errout;
                        cfg->rc_via_alen   = nla_len(nla) -
                                offsetof(struct rtvia, rtvia_addr);
                        if (cfg->rc_via_alen > MAX_VIA_ALEN)
                                goto errout;

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

                        memcpy(cfg->rc_via, via->rtvia_addr, cfg->rc_via_alen);
                        break;
                }
                default:
                        /* Unsupported attribute */
                        goto errout;
                }
        }

        err = 0;
errout:
        return err;
}

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

        err = rtm_to_route_config(skb, nlh, &cfg);
        if (err < 0)
                return err;

        return mpls_route_del(&cfg);
}


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

        err = rtm_to_route_config(skb, nlh, &cfg);
        if (err < 0)
                return err;

        return mpls_route_add(&cfg);
}

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 (rt->rt_labels &&
            nla_put_labels(skb, RTA_NEWDST, rt->rt_labels, rt->rt_label))
                goto nla_put_failure;
        if (nla_put_via(skb, rt->rt_via_table, rt->rt_via, rt->rt_via_alen))
                goto nla_put_failure;
        dev = rtnl_dereference(rt->rt_dev);
        if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
                goto nla_put_failure;
        if (nla_put_labels(skb, RTA_DST, 1, &label))
                goto nla_put_failure;

        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 < 16)
                index = 16;

        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(2 + rt->rt_via_alen)   /* RTA_VIA */
                + nla_total_size(4);                    /* RTA_DST */
        if (rt->rt_labels)                              /* RTA_NEWDST */
                payload += nla_total_size(rt->rt_labels * 4);
        if (rt->rt_dev)                                 /* RTA_OIF */
                payload += nla_total_size(4);
        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 = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
                if (!labels)
                        labels = vzalloc(size);

                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(lo->addr_len);
                if (!rt0)
                        goto nort0;
                RCU_INIT_POINTER(rt0->rt_dev, lo);
                rt0->rt_protocol = RTPROT_KERNEL;
                rt0->rt_via_table = NEIGH_LINK_TABLE;
                memcpy(rt0->rt_via, lo->dev_addr, lo->addr_len);
        }
        if (limit > MPLS_LABEL_IPV6NULL) {
                struct net_device *lo = net->loopback_dev;
                rt2 = mpls_rt_alloc(lo->addr_len);
                if (!rt2)
                        goto nort2;
                RCU_INIT_POINTER(rt2->rt_dev, lo);
                rt2->rt_protocol = RTPROT_KERNEL;
                rt2->rt_via_table = NEIGH_LINK_TABLE;
                memcpy(rt2->rt_via, 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, 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;
}

static const struct ctl_table mpls_table[] = {
        {
                .procname       = "platform_labels",
                .data           = NULL,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = mpls_platform_labels,
        },
        { }
};

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

        net->mpls.platform_labels = 0;
        net->mpls.platform_label = NULL;

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

        table[0].data = net;
        net->mpls.ctl = register_net_sysctl(net, "net/mpls", table);
        if (net->mpls.ctl == NULL)
                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_rt_free(rt);
        }
        rtnl_unlock();

        kvfree(platform_label);
}

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

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_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);
        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);
        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);