vxlan.c

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/*
 * VXLAN: Virtual eXtensible Local Area Network
 *
 * Copyright (c) 2012 Vyatta Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * TODO
 *  - use IANA UDP port number (when defined)
 *  - IPv6 (not in RFC)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/rculist.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/igmp.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/hash.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/rtnetlink.h>
#include <net/route.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#define VXLAN_VERSION   "0.1"

#define VNI_HASH_BITS   10
#define VNI_HASH_SIZE   (1<<VNI_HASH_BITS)
#define FDB_HASH_BITS   8
#define FDB_HASH_SIZE   (1<<FDB_HASH_BITS)
#define FDB_AGE_DEFAULT 300 /* 5 min */
#define FDB_AGE_INTERVAL (10 * HZ)  /* rescan interval */

#define VXLAN_N_VID (1u << 24)
#define VXLAN_VID_MASK  (VXLAN_N_VID - 1)
/* IP header + UDP + VXLAN + Ethernet header */
#define VXLAN_HEADROOM (20 + 8 + 8 + 14)

#define VXLAN_FLAGS 0x08000000  /* struct vxlanhdr.vx_flags required value. */

/* VXLAN protocol header */
struct vxlanhdr {
    __be32 vx_flags;
    __be32 vx_vni;
};

/* UDP port for VXLAN traffic. */
static unsigned int vxlan_port __read_mostly = 8472;
module_param_named(udp_port, vxlan_port, uint, 0444);
MODULE_PARM_DESC(udp_port, "Destination UDP port");

static bool log_ecn_error = true;
module_param(log_ecn_error, bool, 0644);
MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");

/* per-net private data for this module */
static unsigned int vxlan_net_id;
struct vxlan_net {
    struct socket     *sock;    /* UDP encap socket */
    struct hlist_head vni_list[VNI_HASH_SIZE];
};

/* Forwarding table entry */
struct vxlan_fdb {
    struct hlist_node hlist;    /* linked list of entries */
    struct rcu_head   rcu;
    unsigned long     updated;  /* jiffies */
    unsigned long     used;
    __be32        remote_ip;
    u16       state;    /* see ndm_state */
    u8        eth_addr[ETH_ALEN];
};

/* Per-cpu network traffic stats */
struct vxlan_stats {
    u64         rx_packets;
    u64         rx_bytes;
    u64         tx_packets;
    u64         tx_bytes;
    struct u64_stats_sync   syncp;
};

/* Pseudo network device */
struct vxlan_dev {
    struct hlist_node hlist;
    struct net_device *dev;
    struct vxlan_stats __percpu *stats;
    __u32         vni;      /* virtual network id */
    __be32            gaddr;    /* multicast group */
    __be32        saddr;    /* source address */
    unsigned int      link;     /* link to multicast over */
    __u16         port_min; /* source port range */
    __u16         port_max;
    __u8          tos;      /* TOS override */
    __u8          ttl;
    bool          learn;

    unsigned long     age_interval;
    struct timer_list age_timer;
    spinlock_t    hash_lock;
    unsigned int      addrcnt;
    unsigned int      addrmax;
    unsigned int      addrexceeded;

    struct hlist_head fdb_head[FDB_HASH_SIZE];
};

/* salt for hash table */
static u32 vxlan_salt __read_mostly;

static inline struct hlist_head *vni_head(struct net *net, u32 id)
{
    struct vxlan_net *vn = net_generic(net, vxlan_net_id);

    return &vn->vni_list[hash_32(id, VNI_HASH_BITS)];
}

/* Look up VNI in a per net namespace table */
static struct vxlan_dev *vxlan_find_vni(struct net *net, u32 id)
{
    struct vxlan_dev *vxlan;
    struct hlist_node *node;

    hlist_for_each_entry_rcu(vxlan, node, vni_head(net, id), hlist) {
        if (vxlan->vni == id)
            return vxlan;
    }

    return NULL;
}

/* Fill in neighbour message in skbuff. */
static int vxlan_fdb_info(struct sk_buff *skb, struct vxlan_dev *vxlan,
               const struct vxlan_fdb *fdb,
               u32 portid, u32 seq, int type, unsigned int flags)
{
    unsigned long now = jiffies;
    struct nda_cacheinfo ci;
    struct nlmsghdr *nlh;
    struct ndmsg *ndm;

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

    ndm = nlmsg_data(nlh);
    memset(ndm, 0, sizeof(*ndm));
    ndm->ndm_family = AF_BRIDGE;
    ndm->ndm_state = fdb->state;
    ndm->ndm_ifindex = vxlan->dev->ifindex;
    ndm->ndm_flags = NTF_SELF;
    ndm->ndm_type = NDA_DST;

    if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->eth_addr))
        goto nla_put_failure;

    if (nla_put_be32(skb, NDA_DST, fdb->remote_ip))
        goto nla_put_failure;

    ci.ndm_used  = jiffies_to_clock_t(now - fdb->used);
    ci.ndm_confirmed = 0;
    ci.ndm_updated   = jiffies_to_clock_t(now - fdb->updated);
    ci.ndm_refcnt    = 0;

    if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
        goto nla_put_failure;

    return nlmsg_end(skb, nlh);

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

static inline size_t vxlan_nlmsg_size(void)
{
    return NLMSG_ALIGN(sizeof(struct ndmsg))
        + nla_total_size(ETH_ALEN) /* NDA_LLADDR */
        + nla_total_size(sizeof(__be32)) /* NDA_DST */
        + nla_total_size(sizeof(struct nda_cacheinfo));
}

static void vxlan_fdb_notify(struct vxlan_dev *vxlan,
                 const struct vxlan_fdb *fdb, int type)
{
    struct net *net = dev_net(vxlan->dev);
    struct sk_buff *skb;
    int err = -ENOBUFS;

    skb = nlmsg_new(vxlan_nlmsg_size(), GFP_ATOMIC);
    if (skb == NULL)
        goto errout;

    err = vxlan_fdb_info(skb, vxlan, fdb, 0, 0, type, 0);
    if (err < 0) {
        /* -EMSGSIZE implies BUG in vxlan_nlmsg_size() */
        WARN_ON(err == -EMSGSIZE);
        kfree_skb(skb);
        goto errout;
    }

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

/* Hash Ethernet address */
static u32 eth_hash(const unsigned char *addr)
{
    u64 value = get_unaligned((u64 *)addr);

    /* only want 6 bytes */
#ifdef __BIG_ENDIAN
    value >>= 16;
#else
    value <<= 16;
#endif
    return hash_64(value, FDB_HASH_BITS);
}

/* Hash chain to use given mac address */
static inline struct hlist_head *vxlan_fdb_head(struct vxlan_dev *vxlan,
                        const u8 *mac)
{
    return &vxlan->fdb_head[eth_hash(mac)];
}

/* Look up Ethernet address in forwarding table */
static struct vxlan_fdb *vxlan_find_mac(struct vxlan_dev *vxlan,
                    const u8 *mac)

{
    struct hlist_head *head = vxlan_fdb_head(vxlan, mac);
    struct vxlan_fdb *f;
    struct hlist_node *node;

    hlist_for_each_entry_rcu(f, node, head, hlist) {
        if (compare_ether_addr(mac, f->eth_addr) == 0)
            return f;
    }

    return NULL;
}

/* Add new entry to forwarding table -- assumes lock held */
static int vxlan_fdb_create(struct vxlan_dev *vxlan,
                const u8 *mac, __be32 ip,
                __u16 state, __u16 flags)
{
    struct vxlan_fdb *f;
    int notify = 0;

    f = vxlan_find_mac(vxlan, mac);
    if (f) {
        if (flags & NLM_F_EXCL) {
            netdev_dbg(vxlan->dev,
                   "lost race to create %pM\n", mac);
            return -EEXIST;
        }
        if (f->state != state) {
            f->state = state;
            f->updated = jiffies;
            notify = 1;
        }
    } else {
        if (!(flags & NLM_F_CREATE))
            return -ENOENT;

        if (vxlan->addrmax && vxlan->addrcnt >= vxlan->addrmax)
            return -ENOSPC;

        netdev_dbg(vxlan->dev, "add %pM -> %pI4\n", mac, &ip);
        f = kmalloc(sizeof(*f), GFP_ATOMIC);
        if (!f)
            return -ENOMEM;

        notify = 1;
        f->remote_ip = ip;
        f->state = state;
        f->updated = f->used = jiffies;
        memcpy(f->eth_addr, mac, ETH_ALEN);

        ++vxlan->addrcnt;
        hlist_add_head_rcu(&f->hlist,
                   vxlan_fdb_head(vxlan, mac));
    }

    if (notify)
        vxlan_fdb_notify(vxlan, f, RTM_NEWNEIGH);

    return 0;
}

static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f)
{
    netdev_dbg(vxlan->dev,
            "delete %pM\n", f->eth_addr);

    --vxlan->addrcnt;
    vxlan_fdb_notify(vxlan, f, RTM_DELNEIGH);

    hlist_del_rcu(&f->hlist);
    kfree_rcu(f, rcu);
}

/* Add static entry (via netlink) */
static int vxlan_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
             struct net_device *dev,
             const unsigned char *addr, u16 flags)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    __be32 ip;
    int err;

    if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_REACHABLE))) {
        pr_info("RTM_NEWNEIGH with invalid state %#x\n",
            ndm->ndm_state);
        return -EINVAL;
    }

    if (tb[NDA_DST] == NULL)
        return -EINVAL;

    if (nla_len(tb[NDA_DST]) != sizeof(__be32))
        return -EAFNOSUPPORT;

    ip = nla_get_be32(tb[NDA_DST]);

    spin_lock_bh(&vxlan->hash_lock);
    err = vxlan_fdb_create(vxlan, addr, ip, ndm->ndm_state, flags);
    spin_unlock_bh(&vxlan->hash_lock);

    return err;
}

/* Delete entry (via netlink) */
static int vxlan_fdb_delete(struct ndmsg *ndm, struct net_device *dev,
                const unsigned char *addr)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct vxlan_fdb *f;
    int err = -ENOENT;

    spin_lock_bh(&vxlan->hash_lock);
    f = vxlan_find_mac(vxlan, addr);
    if (f) {
        vxlan_fdb_destroy(vxlan, f);
        err = 0;
    }
    spin_unlock_bh(&vxlan->hash_lock);

    return err;
}

/* Dump forwarding table */
static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
              struct net_device *dev, int idx)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    unsigned int h;

    for (h = 0; h < FDB_HASH_SIZE; ++h) {
        struct vxlan_fdb *f;
        struct hlist_node *n;
        int err;

        hlist_for_each_entry_rcu(f, n, &vxlan->fdb_head[h], hlist) {
            if (idx < cb->args[0])
                goto skip;

            err = vxlan_fdb_info(skb, vxlan, f,
                         NETLINK_CB(cb->skb).portid,
                         cb->nlh->nlmsg_seq,
                         RTM_NEWNEIGH,
                         NLM_F_MULTI);
            if (err < 0)
                break;
skip:
            ++idx;
        }
    }

    return idx;
}

/* Watch incoming packets to learn mapping between Ethernet address
 * and Tunnel endpoint.
 */
static void vxlan_snoop(struct net_device *dev,
            __be32 src_ip, const u8 *src_mac)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct vxlan_fdb *f;
    int err;

    f = vxlan_find_mac(vxlan, src_mac);
    if (likely(f)) {
        f->used = jiffies;
        if (likely(f->remote_ip == src_ip))
            return;

        if (net_ratelimit())
            netdev_info(dev,
                    "%pM migrated from %pI4 to %pI4\n",
                    src_mac, &f->remote_ip, &src_ip);

        f->remote_ip = src_ip;
        f->updated = jiffies;
    } else {
        /* learned new entry */
        spin_lock(&vxlan->hash_lock);
        err = vxlan_fdb_create(vxlan, src_mac, src_ip,
                       NUD_REACHABLE,
                       NLM_F_EXCL|NLM_F_CREATE);
        spin_unlock(&vxlan->hash_lock);
    }
}


/* See if multicast group is already in use by other ID */
static bool vxlan_group_used(struct vxlan_net *vn,
                 const struct vxlan_dev *this)
{
    const struct vxlan_dev *vxlan;
    struct hlist_node *node;
    unsigned h;

    for (h = 0; h < VNI_HASH_SIZE; ++h)
        hlist_for_each_entry(vxlan, node, &vn->vni_list[h], hlist) {
            if (vxlan == this)
                continue;

            if (!netif_running(vxlan->dev))
                continue;

            if (vxlan->gaddr == this->gaddr)
                return true;
        }

    return false;
}

/* kernel equivalent to IP_ADD_MEMBERSHIP */
static int vxlan_join_group(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);
    struct sock *sk = vn->sock->sk;
    struct ip_mreqn mreq = {
        .imr_multiaddr.s_addr = vxlan->gaddr,
    };
    int err;

    /* Already a member of group */
    if (vxlan_group_used(vn, vxlan))
        return 0;

    /* Need to drop RTNL to call multicast join */
    rtnl_unlock();
    lock_sock(sk);
    err = ip_mc_join_group(sk, &mreq);
    release_sock(sk);
    rtnl_lock();

    return err;
}


/* kernel equivalent to IP_DROP_MEMBERSHIP */
static int vxlan_leave_group(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);
    int err = 0;
    struct sock *sk = vn->sock->sk;
    struct ip_mreqn mreq = {
        .imr_multiaddr.s_addr = vxlan->gaddr,
    };

    /* Only leave group when last vxlan is done. */
    if (vxlan_group_used(vn, vxlan))
        return 0;

    /* Need to drop RTNL to call multicast leave */
    rtnl_unlock();
    lock_sock(sk);
    err = ip_mc_leave_group(sk, &mreq);
    release_sock(sk);
    rtnl_lock();

    return err;
}

/* Callback from net/ipv4/udp.c to receive packets */
static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
    struct iphdr *oip;
    struct vxlanhdr *vxh;
    struct vxlan_dev *vxlan;
    struct vxlan_stats *stats;
    __u32 vni;
    int err;

    /* pop off outer UDP header */
    __skb_pull(skb, sizeof(struct udphdr));

    /* Need Vxlan and inner Ethernet header to be present */
    if (!pskb_may_pull(skb, sizeof(struct vxlanhdr)))
        goto error;

    /* Drop packets with reserved bits set */
    vxh = (struct vxlanhdr *) skb->data;
    if (vxh->vx_flags != htonl(VXLAN_FLAGS) ||
        (vxh->vx_vni & htonl(0xff))) {
        netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
               ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
        goto error;
    }

    __skb_pull(skb, sizeof(struct vxlanhdr));

    /* Is this VNI defined? */
    vni = ntohl(vxh->vx_vni) >> 8;
    vxlan = vxlan_find_vni(sock_net(sk), vni);
    if (!vxlan) {
        netdev_dbg(skb->dev, "unknown vni %d\n", vni);
        goto drop;
    }

    if (!pskb_may_pull(skb, ETH_HLEN)) {
        vxlan->dev->stats.rx_length_errors++;
        vxlan->dev->stats.rx_errors++;
        goto drop;
    }

    /* Re-examine inner Ethernet packet */
    oip = ip_hdr(skb);
    skb->protocol = eth_type_trans(skb, vxlan->dev);

    /* Ignore packet loops (and multicast echo) */
    if (compare_ether_addr(eth_hdr(skb)->h_source,
                   vxlan->dev->dev_addr) == 0)
        goto drop;

    if (vxlan->learn)
        vxlan_snoop(skb->dev, oip->saddr, eth_hdr(skb)->h_source);

    __skb_tunnel_rx(skb, vxlan->dev);
    skb_reset_network_header(skb);
    skb->ip_summed = CHECKSUM_NONE;

    err = IP_ECN_decapsulate(oip, skb);
    if (unlikely(err)) {
        if (log_ecn_error)
            net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
                         &oip->saddr, oip->tos);
        if (err > 1) {
            ++vxlan->dev->stats.rx_frame_errors;
            ++vxlan->dev->stats.rx_errors;
            goto drop;
        }
    }

    stats = this_cpu_ptr(vxlan->stats);
    u64_stats_update_begin(&stats->syncp);
    stats->rx_packets++;
    stats->rx_bytes += skb->len;
    u64_stats_update_end(&stats->syncp);

    netif_rx(skb);

    return 0;
error:
    /* Put UDP header back */
    __skb_push(skb, sizeof(struct udphdr));

    return 1;
drop:
    /* Consume bad packet */
    kfree_skb(skb);
    return 0;
}

/* Extract dsfield from inner protocol */
static inline u8 vxlan_get_dsfield(const struct iphdr *iph,
                   const struct sk_buff *skb)
{
    if (skb->protocol == htons(ETH_P_IP))
        return iph->tos;
    else if (skb->protocol == htons(ETH_P_IPV6))
        return ipv6_get_dsfield((const struct ipv6hdr *)iph);
    else
        return 0;
}

/* Propogate ECN bits out */
static inline u8 vxlan_ecn_encap(u8 tos,
                 const struct iphdr *iph,
                 const struct sk_buff *skb)
{
    u8 inner = vxlan_get_dsfield(iph, skb);

    return INET_ECN_encapsulate(tos, inner);
}

static __be32 vxlan_find_dst(struct vxlan_dev *vxlan, struct sk_buff *skb)
{
    const struct ethhdr *eth = (struct ethhdr *) skb->data;
    const struct vxlan_fdb *f;

    if (is_multicast_ether_addr(eth->h_dest))
        return vxlan->gaddr;

    f = vxlan_find_mac(vxlan, eth->h_dest);
    if (f)
        return f->remote_ip;
    else
        return vxlan->gaddr;

}

static void vxlan_sock_free(struct sk_buff *skb)
{
    sock_put(skb->sk);
}

/* On transmit, associate with the tunnel socket */
static void vxlan_set_owner(struct net_device *dev, struct sk_buff *skb)
{
    struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);
    struct sock *sk = vn->sock->sk;

    skb_orphan(skb);
    sock_hold(sk);
    skb->sk = sk;
    skb->destructor = vxlan_sock_free;
}

/* Compute source port for outgoing packet
 *   first choice to use L4 flow hash since it will spread
 *     better and maybe available from hardware
 *   secondary choice is to use jhash on the Ethernet header
 */
static u16 vxlan_src_port(const struct vxlan_dev *vxlan, struct sk_buff *skb)
{
    unsigned int range = (vxlan->port_max - vxlan->port_min) + 1;
    u32 hash;

    hash = skb_get_rxhash(skb);
    if (!hash)
        hash = jhash(skb->data, 2 * ETH_ALEN,
                 (__force u32) skb->protocol);

    return (((u64) hash * range) >> 32) + vxlan->port_min;
}

/* Transmit local packets over Vxlan
 *
 * Outer IP header inherits ECN and DF from inner header.
 * Outer UDP destination is the VXLAN assigned port.
 *           source port is based on hash of flow
 */
static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct rtable *rt;
    const struct iphdr *old_iph;
    struct iphdr *iph;
    struct vxlanhdr *vxh;
    struct udphdr *uh;
    struct flowi4 fl4;
    unsigned int pkt_len = skb->len;
    __be32 dst;
    __u16 src_port;
    __be16 df = 0;
    __u8 tos, ttl;
    int err;

    dst = vxlan_find_dst(vxlan, skb);
    if (!dst)
        goto drop;

    /* Need space for new headers (invalidates iph ptr) */
    if (skb_cow_head(skb, VXLAN_HEADROOM))
        goto drop;

    old_iph = ip_hdr(skb);

    ttl = vxlan->ttl;
    if (!ttl && IN_MULTICAST(ntohl(dst)))
        ttl = 1;

    tos = vxlan->tos;
    if (tos == 1)
        tos = vxlan_get_dsfield(old_iph, skb);

    src_port = vxlan_src_port(vxlan, skb);

    memset(&fl4, 0, sizeof(fl4));
    fl4.flowi4_oif = vxlan->link;
    fl4.flowi4_tos = RT_TOS(tos);
    fl4.daddr = dst;
    fl4.saddr = vxlan->saddr;

    rt = ip_route_output_key(dev_net(dev), &fl4);
    if (IS_ERR(rt)) {
        netdev_dbg(dev, "no route to %pI4\n", &dst);
        dev->stats.tx_carrier_errors++;
        goto tx_error;
    }

    if (rt->dst.dev == dev) {
        netdev_dbg(dev, "circular route to %pI4\n", &dst);
        ip_rt_put(rt);
        dev->stats.collisions++;
        goto tx_error;
    }

    memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
    IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
                  IPSKB_REROUTED);
    skb_dst_drop(skb);
    skb_dst_set(skb, &rt->dst);

    vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
    vxh->vx_flags = htonl(VXLAN_FLAGS);
    vxh->vx_vni = htonl(vxlan->vni << 8);

    __skb_push(skb, sizeof(*uh));
    skb_reset_transport_header(skb);
    uh = udp_hdr(skb);

    uh->dest = htons(vxlan_port);
    uh->source = htons(src_port);

    uh->len = htons(skb->len);
    uh->check = 0;

    __skb_push(skb, sizeof(*iph));
    skb_reset_network_header(skb);
    iph     = ip_hdr(skb);
    iph->version    = 4;
    iph->ihl    = sizeof(struct iphdr) >> 2;
    iph->frag_off   = df;
    iph->protocol   = IPPROTO_UDP;
    iph->tos    = vxlan_ecn_encap(tos, old_iph, skb);
    iph->daddr  = dst;
    iph->saddr  = fl4.saddr;
    iph->ttl    = ttl ? : ip4_dst_hoplimit(&rt->dst);

    vxlan_set_owner(dev, skb);

    /* See __IPTUNNEL_XMIT */
    skb->ip_summed = CHECKSUM_NONE;
    ip_select_ident(iph, &rt->dst, NULL);

    err = ip_local_out(skb);
    if (likely(net_xmit_eval(err) == 0)) {
        struct vxlan_stats *stats = this_cpu_ptr(vxlan->stats);

        u64_stats_update_begin(&stats->syncp);
        stats->tx_packets++;
        stats->tx_bytes += pkt_len;
        u64_stats_update_end(&stats->syncp);
    } else {
        dev->stats.tx_errors++;
        dev->stats.tx_aborted_errors++;
    }
    return NETDEV_TX_OK;

drop:
    dev->stats.tx_dropped++;
    goto tx_free;

tx_error:
    dev->stats.tx_errors++;
tx_free:
    dev_kfree_skb(skb);
    return NETDEV_TX_OK;
}

/* Walk the forwarding table and purge stale entries */
static void vxlan_cleanup(unsigned long arg)
{
    struct vxlan_dev *vxlan = (struct vxlan_dev *) arg;
    unsigned long next_timer = jiffies + FDB_AGE_INTERVAL;
    unsigned int h;

    if (!netif_running(vxlan->dev))
        return;

    spin_lock_bh(&vxlan->hash_lock);
    for (h = 0; h < FDB_HASH_SIZE; ++h) {
        struct hlist_node *p, *n;
        hlist_for_each_safe(p, n, &vxlan->fdb_head[h]) {
            struct vxlan_fdb *f
                = container_of(p, struct vxlan_fdb, hlist);
            unsigned long timeout;

            if (f->state & NUD_PERMANENT)
                continue;

            timeout = f->used + vxlan->age_interval * HZ;
            if (time_before_eq(timeout, jiffies)) {
                netdev_dbg(vxlan->dev,
                       "garbage collect %pM\n",
                       f->eth_addr);
                f->state = NUD_STALE;
                vxlan_fdb_destroy(vxlan, f);
            } else if (time_before(timeout, next_timer))
                next_timer = timeout;
        }
    }
    spin_unlock_bh(&vxlan->hash_lock);

    mod_timer(&vxlan->age_timer, next_timer);
}

/* Setup stats when device is created */
static int vxlan_init(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);

    vxlan->stats = alloc_percpu(struct vxlan_stats);
    if (!vxlan->stats)
        return -ENOMEM;

    return 0;
}

/* Start ageing timer and join group when device is brought up */
static int vxlan_open(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    int err;

    if (vxlan->gaddr) {
        err = vxlan_join_group(dev);
        if (err)
            return err;
    }

    if (vxlan->age_interval)
        mod_timer(&vxlan->age_timer, jiffies + FDB_AGE_INTERVAL);

    return 0;
}

/* Purge the forwarding table */
static void vxlan_flush(struct vxlan_dev *vxlan)
{
    unsigned h;

    spin_lock_bh(&vxlan->hash_lock);
    for (h = 0; h < FDB_HASH_SIZE; ++h) {
        struct hlist_node *p, *n;
        hlist_for_each_safe(p, n, &vxlan->fdb_head[h]) {
            struct vxlan_fdb *f
                = container_of(p, struct vxlan_fdb, hlist);
            vxlan_fdb_destroy(vxlan, f);
        }
    }
    spin_unlock_bh(&vxlan->hash_lock);
}

/* Cleanup timer and forwarding table on shutdown */
static int vxlan_stop(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);

    if (vxlan->gaddr)
        vxlan_leave_group(dev);

    del_timer_sync(&vxlan->age_timer);

    vxlan_flush(vxlan);

    return 0;
}

/* Merge per-cpu statistics */
static struct rtnl_link_stats64 *vxlan_stats64(struct net_device *dev,
                           struct rtnl_link_stats64 *stats)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    struct vxlan_stats tmp, sum = { 0 };
    unsigned int cpu;

    for_each_possible_cpu(cpu) {
        unsigned int start;
        const struct vxlan_stats *stats
            = per_cpu_ptr(vxlan->stats, cpu);

        do {
            start = u64_stats_fetch_begin_bh(&stats->syncp);
            memcpy(&tmp, stats, sizeof(tmp));
        } while (u64_stats_fetch_retry_bh(&stats->syncp, start));

        sum.tx_bytes   += tmp.tx_bytes;
        sum.tx_packets += tmp.tx_packets;
        sum.rx_bytes   += tmp.rx_bytes;
        sum.rx_packets += tmp.rx_packets;
    }

    stats->tx_bytes   = sum.tx_bytes;
    stats->tx_packets = sum.tx_packets;
    stats->rx_bytes   = sum.rx_bytes;
    stats->rx_packets = sum.rx_packets;

    stats->multicast = dev->stats.multicast;
    stats->rx_length_errors = dev->stats.rx_length_errors;
    stats->rx_frame_errors = dev->stats.rx_frame_errors;
    stats->rx_errors = dev->stats.rx_errors;

    stats->tx_dropped = dev->stats.tx_dropped;
    stats->tx_carrier_errors  = dev->stats.tx_carrier_errors;
    stats->tx_aborted_errors  = dev->stats.tx_aborted_errors;
    stats->collisions  = dev->stats.collisions;
    stats->tx_errors = dev->stats.tx_errors;

    return stats;
}

/* Stub, nothing needs to be done. */
static void vxlan_set_multicast_list(struct net_device *dev)
{
}

static const struct net_device_ops vxlan_netdev_ops = {
    .ndo_init       = vxlan_init,
    .ndo_open       = vxlan_open,
    .ndo_stop       = vxlan_stop,
    .ndo_start_xmit     = vxlan_xmit,
    .ndo_get_stats64    = vxlan_stats64,
    .ndo_set_rx_mode    = vxlan_set_multicast_list,
    .ndo_change_mtu     = eth_change_mtu,
    .ndo_validate_addr  = eth_validate_addr,
    .ndo_set_mac_address    = eth_mac_addr,
    .ndo_fdb_add        = vxlan_fdb_add,
    .ndo_fdb_del        = vxlan_fdb_delete,
    .ndo_fdb_dump       = vxlan_fdb_dump,
};

/* Info for udev, that this is a virtual tunnel endpoint */
static struct device_type vxlan_type = {
    .name = "vxlan",
};

static void vxlan_free(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);

    free_percpu(vxlan->stats);
    free_netdev(dev);
}

/* Initialize the device structure. */
static void vxlan_setup(struct net_device *dev)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    unsigned h;
    int low, high;

    eth_hw_addr_random(dev);
    ether_setup(dev);
    dev->hard_header_len = ETH_HLEN + VXLAN_HEADROOM;

    dev->netdev_ops = &vxlan_netdev_ops;
    dev->destructor = vxlan_free;
    SET_NETDEV_DEVTYPE(dev, &vxlan_type);

    dev->tx_queue_len = 0;
    dev->features   |= NETIF_F_LLTX;
    dev->features   |= NETIF_F_NETNS_LOCAL;
    dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;

    spin_lock_init(&vxlan->hash_lock);

    init_timer_deferrable(&vxlan->age_timer);
    vxlan->age_timer.function = vxlan_cleanup;
    vxlan->age_timer.data = (unsigned long) vxlan;

    inet_get_local_port_range(&low, &high);
    vxlan->port_min = low;
    vxlan->port_max = high;

    vxlan->dev = dev;

    for (h = 0; h < FDB_HASH_SIZE; ++h)
        INIT_HLIST_HEAD(&vxlan->fdb_head[h]);
}

static const struct nla_policy vxlan_policy[IFLA_VXLAN_MAX + 1] = {
    [IFLA_VXLAN_ID]     = { .type = NLA_U32 },
    [IFLA_VXLAN_GROUP]  = { .len = FIELD_SIZEOF(struct iphdr, daddr) },
    [IFLA_VXLAN_LINK]   = { .type = NLA_U32 },
    [IFLA_VXLAN_LOCAL]  = { .len = FIELD_SIZEOF(struct iphdr, saddr) },
    [IFLA_VXLAN_TOS]    = { .type = NLA_U8 },
    [IFLA_VXLAN_TTL]    = { .type = NLA_U8 },
    [IFLA_VXLAN_LEARNING]   = { .type = NLA_U8 },
    [IFLA_VXLAN_AGEING] = { .type = NLA_U32 },
    [IFLA_VXLAN_LIMIT]  = { .type = NLA_U32 },
    [IFLA_VXLAN_PORT_RANGE] = { .len  = sizeof(struct ifla_vxlan_port_range) },
};

static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[])
{
    if (tb[IFLA_ADDRESS]) {
        if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) {
            pr_debug("invalid link address (not ethernet)\n");
            return -EINVAL;
        }

        if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) {
            pr_debug("invalid all zero ethernet address\n");
            return -EADDRNOTAVAIL;
        }
    }

    if (!data)
        return -EINVAL;

    if (data[IFLA_VXLAN_ID]) {
        __u32 id = nla_get_u32(data[IFLA_VXLAN_ID]);
        if (id >= VXLAN_VID_MASK)
            return -ERANGE;
    }

    if (data[IFLA_VXLAN_GROUP]) {
        __be32 gaddr = nla_get_be32(data[IFLA_VXLAN_GROUP]);
        if (!IN_MULTICAST(ntohl(gaddr))) {
            pr_debug("group address is not IPv4 multicast\n");
            return -EADDRNOTAVAIL;
        }
    }

    if (data[IFLA_VXLAN_PORT_RANGE]) {
        const struct ifla_vxlan_port_range *p
            = nla_data(data[IFLA_VXLAN_PORT_RANGE]);

        if (ntohs(p->high) < ntohs(p->low)) {
            pr_debug("port range %u .. %u not valid\n",
                 ntohs(p->low), ntohs(p->high));
            return -EINVAL;
        }
    }

    return 0;
}

static int vxlan_newlink(struct net *net, struct net_device *dev,
             struct nlattr *tb[], struct nlattr *data[])
{
    struct vxlan_dev *vxlan = netdev_priv(dev);
    __u32 vni;
    int err;

    if (!data[IFLA_VXLAN_ID])
        return -EINVAL;

    vni = nla_get_u32(data[IFLA_VXLAN_ID]);
    if (vxlan_find_vni(net, vni)) {
        pr_info("duplicate VNI %u\n", vni);
        return -EEXIST;
    }
    vxlan->vni = vni;

    if (data[IFLA_VXLAN_GROUP])
        vxlan->gaddr = nla_get_be32(data[IFLA_VXLAN_GROUP]);

    if (data[IFLA_VXLAN_LOCAL])
        vxlan->saddr = nla_get_be32(data[IFLA_VXLAN_LOCAL]);

    if (data[IFLA_VXLAN_LINK] &&
        (vxlan->link = nla_get_u32(data[IFLA_VXLAN_LINK]))) {
        struct net_device *lowerdev
             = __dev_get_by_index(net, vxlan->link);

        if (!lowerdev) {
            pr_info("ifindex %d does not exist\n", vxlan->link);
            return -ENODEV;
        }

        if (!tb[IFLA_MTU])
            dev->mtu = lowerdev->mtu - VXLAN_HEADROOM;

        /* update header length based on lower device */
        dev->hard_header_len = lowerdev->hard_header_len +
                       VXLAN_HEADROOM;
    }

    if (data[IFLA_VXLAN_TOS])
        vxlan->tos  = nla_get_u8(data[IFLA_VXLAN_TOS]);

    if (!data[IFLA_VXLAN_LEARNING] || nla_get_u8(data[IFLA_VXLAN_LEARNING]))
        vxlan->learn = true;

    if (data[IFLA_VXLAN_AGEING])
        vxlan->age_interval = nla_get_u32(data[IFLA_VXLAN_AGEING]);
    else
        vxlan->age_interval = FDB_AGE_DEFAULT;

    if (data[IFLA_VXLAN_LIMIT])
        vxlan->addrmax = nla_get_u32(data[IFLA_VXLAN_LIMIT]);

    if (data[IFLA_VXLAN_PORT_RANGE]) {
        const struct ifla_vxlan_port_range *p
            = nla_data(data[IFLA_VXLAN_PORT_RANGE]);
        vxlan->port_min = ntohs(p->low);
        vxlan->port_max = ntohs(p->high);
    }

    err = register_netdevice(dev);
    if (!err)
        hlist_add_head_rcu(&vxlan->hlist, vni_head(net, vxlan->vni));

    return err;
}

static void vxlan_dellink(struct net_device *dev, struct list_head *head)
{
    struct vxlan_dev *vxlan = netdev_priv(dev);

    hlist_del_rcu(&vxlan->hlist);

    unregister_netdevice_queue(dev, head);
}

static size_t vxlan_get_size(const struct net_device *dev)
{

    return nla_total_size(sizeof(__u32)) +  /* IFLA_VXLAN_ID */
        nla_total_size(sizeof(__be32)) +/* IFLA_VXLAN_GROUP */
        nla_total_size(sizeof(__u32)) + /* IFLA_VXLAN_LINK */
        nla_total_size(sizeof(__be32))+ /* IFLA_VXLAN_LOCAL */
        nla_total_size(sizeof(__u8)) +  /* IFLA_VXLAN_TTL */
        nla_total_size(sizeof(__u8)) +  /* IFLA_VXLAN_TOS */
        nla_total_size(sizeof(__u8)) +  /* IFLA_VXLAN_LEARNING */
        nla_total_size(sizeof(__u32)) + /* IFLA_VXLAN_AGEING */
        nla_total_size(sizeof(__u32)) + /* IFLA_VXLAN_LIMIT */
        nla_total_size(sizeof(struct ifla_vxlan_port_range)) +
        0;
}

static int vxlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
    const struct vxlan_dev *vxlan = netdev_priv(dev);
    struct ifla_vxlan_port_range ports = {
        .low =  htons(vxlan->port_min),
        .high = htons(vxlan->port_max),
    };

    if (nla_put_u32(skb, IFLA_VXLAN_ID, vxlan->vni))
        goto nla_put_failure;

    if (vxlan->gaddr && nla_put_be32(skb, IFLA_VXLAN_GROUP, vxlan->gaddr))
        goto nla_put_failure;

    if (vxlan->link && nla_put_u32(skb, IFLA_VXLAN_LINK, vxlan->link))
        goto nla_put_failure;

    if (vxlan->saddr && nla_put_be32(skb, IFLA_VXLAN_LOCAL, vxlan->saddr))
        goto nla_put_failure;

    if (nla_put_u8(skb, IFLA_VXLAN_TTL, vxlan->ttl) ||
        nla_put_u8(skb, IFLA_VXLAN_TOS, vxlan->tos) ||
        nla_put_u8(skb, IFLA_VXLAN_LEARNING, vxlan->learn) ||
        nla_put_u32(skb, IFLA_VXLAN_AGEING, vxlan->age_interval) ||
        nla_put_u32(skb, IFLA_VXLAN_LIMIT, vxlan->addrmax))
        goto nla_put_failure;

    if (nla_put(skb, IFLA_VXLAN_PORT_RANGE, sizeof(ports), &ports))
        goto nla_put_failure;

    return 0;

nla_put_failure:
    return -EMSGSIZE;
}

static struct rtnl_link_ops vxlan_link_ops __read_mostly = {
    .kind       = "vxlan",
    .maxtype    = IFLA_VXLAN_MAX,
    .policy     = vxlan_policy,
    .priv_size  = sizeof(struct vxlan_dev),
    .setup      = vxlan_setup,
    .validate   = vxlan_validate,
    .newlink    = vxlan_newlink,
    .dellink    = vxlan_dellink,
    .get_size   = vxlan_get_size,
    .fill_info  = vxlan_fill_info,
};

static __net_init int vxlan_init_net(struct net *net)
{
    struct vxlan_net *vn = net_generic(net, vxlan_net_id);
    struct sock *sk;
    struct sockaddr_in vxlan_addr = {
        .sin_family = AF_INET,
        .sin_addr.s_addr = htonl(INADDR_ANY),
    };
    int rc;
    unsigned h;

    /* Create UDP socket for encapsulation receive. */
    rc = sock_create_kern(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &vn->sock);
    if (rc < 0) {
        pr_debug("UDP socket create failed\n");
        return rc;
    }
    /* Put in proper namespace */
    sk = vn->sock->sk;
    sk_change_net(sk, net);

    vxlan_addr.sin_port = htons(vxlan_port);

    rc = kernel_bind(vn->sock, (struct sockaddr *) &vxlan_addr,
             sizeof(vxlan_addr));
    if (rc < 0) {
        pr_debug("bind for UDP socket %pI4:%u (%d)\n",
             &vxlan_addr.sin_addr, ntohs(vxlan_addr.sin_port), rc);
        sk_release_kernel(sk);
        vn->sock = NULL;
        return rc;
    }

    /* Disable multicast loopback */
    inet_sk(sk)->mc_loop = 0;

    /* Mark socket as an encapsulation socket. */
    udp_sk(sk)->encap_type = 1;
    udp_sk(sk)->encap_rcv = vxlan_udp_encap_recv;
    udp_encap_enable();

    for (h = 0; h < VNI_HASH_SIZE; ++h)
        INIT_HLIST_HEAD(&vn->vni_list[h]);

    return 0;
}

static __net_exit void vxlan_exit_net(struct net *net)
{
    struct vxlan_net *vn = net_generic(net, vxlan_net_id);

    if (vn->sock) {
        sk_release_kernel(vn->sock->sk);
        vn->sock = NULL;
    }
}

static struct pernet_operations vxlan_net_ops = {
    .init = vxlan_init_net,
    .exit = vxlan_exit_net,
    .id   = &vxlan_net_id,
    .size = sizeof(struct vxlan_net),
};

static int __init vxlan_init_module(void)
{
    int rc;

    get_random_bytes(&vxlan_salt, sizeof(vxlan_salt));

    rc = register_pernet_device(&vxlan_net_ops);
    if (rc)
        goto out1;

    rc = rtnl_link_register(&vxlan_link_ops);
    if (rc)
        goto out2;

    return 0;

out2:
    unregister_pernet_device(&vxlan_net_ops);
out1:
    return rc;
}
module_init(vxlan_init_module);

static void __exit vxlan_cleanup_module(void)
{
    rtnl_link_unregister(&vxlan_link_ops);
    unregister_pernet_device(&vxlan_net_ops);
}
module_exit(vxlan_cleanup_module);

MODULE_LICENSE("GPL");
MODULE_VERSION(VXLAN_VERSION);
MODULE_AUTHOR("Stephen Hemminger <[email protected]>");
MODULE_ALIAS_RTNL_LINK("vxlan");