root/net/ipv6/ip6_gre.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      GRE over IPv6 protocol decoder.
 *
 *      Authors: Dmitry Kozlov (xeb@mail.ru)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/in6.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/hash.h>
#include <linux/if_tunnel.h>
#include <linux/ip6_tunnel.h>

#include <net/sock.h>
#include <net/ip.h>
#include <net/ip_tunnels.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/addrconf.h>
#include <net/arp.h>
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/netdev_lock.h>
#include <net/rtnetlink.h>

#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/ip6_tunnel.h>
#include <net/gre.h>
#include <net/erspan.h>
#include <net/dst_metadata.h>


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");

#define IP6_GRE_HASH_SIZE_SHIFT  5
#define IP6_GRE_HASH_SIZE (1 << IP6_GRE_HASH_SIZE_SHIFT)

static unsigned int ip6gre_net_id __read_mostly;
struct ip6gre_net {
        struct ip6_tnl __rcu *tunnels[4][IP6_GRE_HASH_SIZE];

        struct ip6_tnl __rcu *collect_md_tun;
        struct ip6_tnl __rcu *collect_md_tun_erspan;
        struct net_device *fb_tunnel_dev;
};

static struct rtnl_link_ops ip6gre_link_ops __read_mostly;
static struct rtnl_link_ops ip6gre_tap_ops __read_mostly;
static struct rtnl_link_ops ip6erspan_tap_ops __read_mostly;
static int ip6gre_tunnel_init(struct net_device *dev);
static void ip6gre_tunnel_setup(struct net_device *dev);
static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t);
static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu);
static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu);

/* Tunnel hash table */

/*
   4 hash tables:

   3: (remote,local)
   2: (remote,*)
   1: (*,local)
   0: (*,*)

   We require exact key match i.e. if a key is present in packet
   it will match only tunnel with the same key; if it is not present,
   it will match only keyless tunnel.

   All keysless packets, if not matched configured keyless tunnels
   will match fallback tunnel.
 */

#define HASH_KEY(key) (((__force u32)key^((__force u32)key>>4))&(IP6_GRE_HASH_SIZE - 1))
static u32 HASH_ADDR(const struct in6_addr *addr)
{
        u32 hash = ipv6_addr_hash(addr);

        return hash_32(hash, IP6_GRE_HASH_SIZE_SHIFT);
}

#define tunnels_r_l     tunnels[3]
#define tunnels_r       tunnels[2]
#define tunnels_l       tunnels[1]
#define tunnels_wc      tunnels[0]

static bool ip6gre_tunnel_match(struct ip6_tnl *t, int dev_type, int link,
                                int *cand_score, struct ip6_tnl **ret)
{
        int score = 0;

        if (t->dev->type != ARPHRD_IP6GRE &&
            t->dev->type != dev_type)
                return false;

        if (t->parms.link != link)
                score |= 1;
        if (t->dev->type != dev_type)
                score |= 2;
        if (score == 0) {
                *ret = t;
                return true;
        }

        if (score < *cand_score) {
                *ret = t;
                *cand_score = score;
        }
        return false;
}

/* Given src, dst and key, find appropriate for input tunnel. */
static struct ip6_tnl *ip6gre_tunnel_lookup(struct net_device *dev,
                const struct in6_addr *remote, const struct in6_addr *local,
                __be32 key, __be16 gre_proto)
{
        struct net *net = dev_net(dev);
        int link = dev->ifindex;
        unsigned int h0 = HASH_ADDR(remote);
        unsigned int h1 = HASH_KEY(key);
        struct ip6_tnl *t, *cand = NULL;
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
        int dev_type = (gre_proto == htons(ETH_P_TEB) ||
                        gre_proto == htons(ETH_P_ERSPAN) ||
                        gre_proto == htons(ETH_P_ERSPAN2)) ?
                       ARPHRD_ETHER : ARPHRD_IP6GRE;
        struct net_device *ndev;
        int cand_score = 4;

        for_each_ip_tunnel_rcu(t, ign->tunnels_r_l[h0 ^ h1]) {
                if (!ipv6_addr_equal(local, &t->parms.laddr) ||
                    !ipv6_addr_equal(remote, &t->parms.raddr) ||
                    key != t->parms.i_key ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (ip6gre_tunnel_match(t, dev_type, link, &cand_score, &cand))
                        return cand;
        }

        for_each_ip_tunnel_rcu(t, ign->tunnels_r[h0 ^ h1]) {
                if (!ipv6_addr_equal(remote, &t->parms.raddr) ||
                    key != t->parms.i_key ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (ip6gre_tunnel_match(t, dev_type, link, &cand_score, &cand))
                        return cand;
        }

        for_each_ip_tunnel_rcu(t, ign->tunnels_l[h1]) {
                if ((!ipv6_addr_equal(local, &t->parms.laddr) &&
                          (!ipv6_addr_equal(local, &t->parms.raddr) ||
                                 !ipv6_addr_is_multicast(local))) ||
                    key != t->parms.i_key ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (ip6gre_tunnel_match(t, dev_type, link, &cand_score, &cand))
                        return cand;
        }

        for_each_ip_tunnel_rcu(t, ign->tunnels_wc[h1]) {
                if (t->parms.i_key != key ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (ip6gre_tunnel_match(t, dev_type, link, &cand_score, &cand))
                        return cand;
        }

        if (cand)
                return cand;

        if (gre_proto == htons(ETH_P_ERSPAN) ||
            gre_proto == htons(ETH_P_ERSPAN2))
                t = rcu_dereference(ign->collect_md_tun_erspan);
        else
                t = rcu_dereference(ign->collect_md_tun);

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

        ndev = READ_ONCE(ign->fb_tunnel_dev);
        if (ndev && ndev->flags & IFF_UP)
                return netdev_priv(ndev);

        return NULL;
}

static struct ip6_tnl __rcu **__ip6gre_bucket(struct ip6gre_net *ign,
                const struct __ip6_tnl_parm *p)
{
        const struct in6_addr *remote = &p->raddr;
        const struct in6_addr *local = &p->laddr;
        unsigned int h = HASH_KEY(p->i_key);
        int prio = 0;

        if (!ipv6_addr_any(local))
                prio |= 1;
        if (!ipv6_addr_any(remote) && !ipv6_addr_is_multicast(remote)) {
                prio |= 2;
                h ^= HASH_ADDR(remote);
        }

        return &ign->tunnels[prio][h];
}

static void ip6gre_tunnel_link_md(struct ip6gre_net *ign, struct ip6_tnl *t)
{
        if (t->parms.collect_md)
                rcu_assign_pointer(ign->collect_md_tun, t);
}

static void ip6erspan_tunnel_link_md(struct ip6gre_net *ign, struct ip6_tnl *t)
{
        if (t->parms.collect_md)
                rcu_assign_pointer(ign->collect_md_tun_erspan, t);
}

static void ip6gre_tunnel_unlink_md(struct ip6gre_net *ign, struct ip6_tnl *t)
{
        if (t->parms.collect_md)
                rcu_assign_pointer(ign->collect_md_tun, NULL);
}

static void ip6erspan_tunnel_unlink_md(struct ip6gre_net *ign,
                                       struct ip6_tnl *t)
{
        if (t->parms.collect_md)
                rcu_assign_pointer(ign->collect_md_tun_erspan, NULL);
}

static inline struct ip6_tnl __rcu **ip6gre_bucket(struct ip6gre_net *ign,
                const struct ip6_tnl *t)
{
        return __ip6gre_bucket(ign, &t->parms);
}

static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp = ip6gre_bucket(ign, t);

        rcu_assign_pointer(t->next, rtnl_dereference(*tp));
        rcu_assign_pointer(*tp, t);
}

static void ip6gre_tunnel_unlink(struct ip6gre_net *ign, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp;
        struct ip6_tnl *iter;

        for (tp = ip6gre_bucket(ign, t);
             (iter = rtnl_dereference(*tp)) != NULL;
             tp = &iter->next) {
                if (t == iter) {
                        rcu_assign_pointer(*tp, t->next);
                        break;
                }
        }
}

static struct ip6_tnl *ip6gre_tunnel_find(struct net *net,
                                           const struct __ip6_tnl_parm *parms,
                                           int type)
{
        const struct in6_addr *remote = &parms->raddr;
        const struct in6_addr *local = &parms->laddr;
        __be32 key = parms->i_key;
        int link = parms->link;
        struct ip6_tnl *t;
        struct ip6_tnl __rcu **tp;
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

        for (tp = __ip6gre_bucket(ign, parms);
             (t = rtnl_dereference(*tp)) != NULL;
             tp = &t->next)
                if (ipv6_addr_equal(local, &t->parms.laddr) &&
                    ipv6_addr_equal(remote, &t->parms.raddr) &&
                    key == t->parms.i_key &&
                    link == t->parms.link &&
                    type == t->dev->type)
                        break;

        return t;
}

static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
                const struct __ip6_tnl_parm *parms, int create)
{
        struct ip6_tnl *t, *nt;
        struct net_device *dev;
        char name[IFNAMSIZ];
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

        t = ip6gre_tunnel_find(net, parms, ARPHRD_IP6GRE);
        if (t && create)
                return NULL;
        if (t || !create)
                return t;

        if (parms->name[0]) {
                if (!dev_valid_name(parms->name))
                        return NULL;
                strscpy(name, parms->name);
        } else {
                strscpy(name, "ip6gre%d");
        }
        dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
                           ip6gre_tunnel_setup);
        if (!dev)
                return NULL;

        dev_net_set(dev, net);

        nt = netdev_priv(dev);
        nt->parms = *parms;
        dev->rtnl_link_ops = &ip6gre_link_ops;

        nt->dev = dev;
        nt->net = dev_net(dev);

        if (register_netdevice(dev) < 0)
                goto failed_free;

        ip6gre_tnl_link_config(nt, 1);
        ip6gre_tunnel_link(ign, nt);
        return nt;

failed_free:
        free_netdev(dev);
        return NULL;
}

static void ip6erspan_tunnel_uninit(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);

        ip6erspan_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        dst_cache_reset(&t->dst_cache);
        netdev_put(dev, &t->dev_tracker);
}

static void ip6gre_tunnel_uninit(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);

        ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        if (ign->fb_tunnel_dev == dev)
                WRITE_ONCE(ign->fb_tunnel_dev, NULL);
        dst_cache_reset(&t->dst_cache);
        netdev_put(dev, &t->dev_tracker);
}


static int ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                       u8 type, u8 code, int offset, __be32 info)
{
        struct net *net = dev_net(skb->dev);
        const struct ipv6hdr *ipv6h;
        struct tnl_ptk_info tpi;
        struct ip6_tnl *t;

        if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IPV6),
                             offset) < 0)
                return -EINVAL;

        ipv6h = (const struct ipv6hdr *)skb->data;
        t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr,
                                 tpi.key, tpi.proto);
        if (!t)
                return -ENOENT;

        switch (type) {
        case ICMPV6_DEST_UNREACH:
                net_dbg_ratelimited("%s: Path to destination invalid or inactive!\n",
                                    t->parms.name);
                if (code != ICMPV6_PORT_UNREACH)
                        break;
                return 0;
        case ICMPV6_TIME_EXCEED:
                if (code == ICMPV6_EXC_HOPLIMIT) {
                        net_dbg_ratelimited("%s: Too small hop limit or routing loop in tunnel!\n",
                                            t->parms.name);
                        break;
                }
                return 0;
        case ICMPV6_PARAMPROB: {
                struct ipv6_tlv_tnl_enc_lim *tel;
                __u32 teli;

                teli = 0;
                if (code == ICMPV6_HDR_FIELD)
                        teli = ip6_tnl_parse_tlv_enc_lim(skb, skb->data);

                if (teli && teli == be32_to_cpu(info) - 2) {
                        tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
                        if (tel->encap_limit == 0) {
                                net_dbg_ratelimited("%s: Too small encapsulation limit or routing loop in tunnel!\n",
                                                    t->parms.name);
                        }
                } else {
                        net_dbg_ratelimited("%s: Recipient unable to parse tunneled packet!\n",
                                            t->parms.name);
                }
                return 0;
        }
        case ICMPV6_PKT_TOOBIG:
                ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
                return 0;
        case NDISC_REDIRECT:
                ip6_redirect(skb, net, skb->dev->ifindex, 0,
                             sock_net_uid(net, NULL));
                return 0;
        }

        if (time_before(jiffies, t->err_time + IP6TUNNEL_ERR_TIMEO))
                t->err_count++;
        else
                t->err_count = 1;
        t->err_time = jiffies;

        return 0;
}

static int ip6gre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
{
        const struct ipv6hdr *ipv6h;
        struct ip6_tnl *tunnel;

        ipv6h = ipv6_hdr(skb);
        tunnel = ip6gre_tunnel_lookup(skb->dev,
                                      &ipv6h->saddr, &ipv6h->daddr, tpi->key,
                                      tpi->proto);
        if (tunnel) {
                if (tunnel->parms.collect_md) {
                        IP_TUNNEL_DECLARE_FLAGS(flags);
                        struct metadata_dst *tun_dst;
                        __be64 tun_id;

                        ip_tunnel_flags_copy(flags, tpi->flags);
                        tun_id = key32_to_tunnel_id(tpi->key);

                        tun_dst = ipv6_tun_rx_dst(skb, flags, tun_id, 0);
                        if (!tun_dst)
                                return PACKET_REJECT;

                        ip6_tnl_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
                } else {
                        ip6_tnl_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
                }

                return PACKET_RCVD;
        }

        return PACKET_REJECT;
}

static int ip6erspan_rcv(struct sk_buff *skb,
                         struct tnl_ptk_info *tpi,
                         int gre_hdr_len)
{
        struct erspan_base_hdr *ershdr;
        const struct ipv6hdr *ipv6h;
        struct erspan_md2 *md2;
        struct ip6_tnl *tunnel;
        u8 ver;

        if (unlikely(!pskb_may_pull(skb, sizeof(*ershdr))))
                return PACKET_REJECT;

        ipv6h = ipv6_hdr(skb);
        ershdr = (struct erspan_base_hdr *)skb->data;
        ver = ershdr->ver;

        tunnel = ip6gre_tunnel_lookup(skb->dev,
                                      &ipv6h->saddr, &ipv6h->daddr, tpi->key,
                                      tpi->proto);
        if (tunnel) {
                int len = erspan_hdr_len(ver);

                if (unlikely(!pskb_may_pull(skb, len)))
                        return PACKET_REJECT;

                if (__iptunnel_pull_header(skb, len,
                                           htons(ETH_P_TEB),
                                           false, false) < 0)
                        return PACKET_REJECT;

                if (tunnel->parms.collect_md) {
                        struct erspan_metadata *pkt_md, *md;
                        IP_TUNNEL_DECLARE_FLAGS(flags);
                        struct metadata_dst *tun_dst;
                        struct ip_tunnel_info *info;
                        unsigned char *gh;
                        __be64 tun_id;

                        __set_bit(IP_TUNNEL_KEY_BIT, tpi->flags);
                        ip_tunnel_flags_copy(flags, tpi->flags);
                        tun_id = key32_to_tunnel_id(tpi->key);

                        tun_dst = ipv6_tun_rx_dst(skb, flags, tun_id,
                                                  sizeof(*md));
                        if (!tun_dst)
                                return PACKET_REJECT;

                        /* MUST set options_len before referencing options */
                        info = &tun_dst->u.tun_info;
                        info->options_len = sizeof(*md);

                        /* skb can be uncloned in __iptunnel_pull_header, so
                         * old pkt_md is no longer valid and we need to reset
                         * it
                         */
                        gh = skb_network_header(skb) +
                             skb_network_header_len(skb);
                        pkt_md = (struct erspan_metadata *)(gh + gre_hdr_len +
                                                            sizeof(*ershdr));
                        md = ip_tunnel_info_opts(info);
                        md->version = ver;
                        md2 = &md->u.md2;
                        memcpy(md2, pkt_md, ver == 1 ? ERSPAN_V1_MDSIZE :
                                                       ERSPAN_V2_MDSIZE);
                        __set_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
                                  info->key.tun_flags);

                        ip6_tnl_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);

                } else {
                        ip6_tnl_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
                }

                return PACKET_RCVD;
        }

        return PACKET_REJECT;
}

static int gre_rcv(struct sk_buff *skb)
{
        struct tnl_ptk_info tpi;
        bool csum_err = false;
        int hdr_len;

        hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IPV6), 0);
        if (hdr_len < 0)
                goto drop;

        if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false))
                goto drop;

        if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) ||
                     tpi.proto == htons(ETH_P_ERSPAN2))) {
                if (ip6erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
                        return 0;
                goto out;
        }

        if (ip6gre_rcv(skb, &tpi) == PACKET_RCVD)
                return 0;

out:
        icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
drop:
        kfree_skb(skb);
        return 0;
}

static int gre_handle_offloads(struct sk_buff *skb, bool csum)
{
        return iptunnel_handle_offloads(skb,
                                        csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
}

static void prepare_ip6gre_xmit_ipv4(struct sk_buff *skb,
                                     struct net_device *dev,
                                     struct flowi6 *fl6, __u8 *dsfield,
                                     int *encap_limit)
{
        const struct iphdr *iph = ip_hdr(skb);
        struct ip6_tnl *t = netdev_priv(dev);

        if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                *encap_limit = t->parms.encap_limit;

        memcpy(fl6, &t->fl.u.ip6, sizeof(*fl6));

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
                *dsfield = ipv4_get_dsfield(iph);
        else
                *dsfield = ip6_tclass(t->parms.flowinfo);

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                fl6->flowi6_mark = skb->mark;
        else
                fl6->flowi6_mark = t->parms.fwmark;

        fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);
}

static int prepare_ip6gre_xmit_ipv6(struct sk_buff *skb,
                                    struct net_device *dev,
                                    struct flowi6 *fl6, __u8 *dsfield,
                                    int *encap_limit)
{
        struct ipv6hdr *ipv6h;
        struct ip6_tnl *t = netdev_priv(dev);
        __u16 offset;

        offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb));
        /* ip6_tnl_parse_tlv_enc_lim() might have reallocated skb->head */
        ipv6h = ipv6_hdr(skb);

        if (offset > 0) {
                struct ipv6_tlv_tnl_enc_lim *tel;

                tel = (struct ipv6_tlv_tnl_enc_lim *)&skb_network_header(skb)[offset];
                if (tel->encap_limit == 0) {
                        icmpv6_ndo_send(skb, ICMPV6_PARAMPROB,
                                        ICMPV6_HDR_FIELD, offset + 2);
                        return -1;
                }
                *encap_limit = tel->encap_limit - 1;
        } else if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) {
                *encap_limit = t->parms.encap_limit;
        }

        memcpy(fl6, &t->fl.u.ip6, sizeof(*fl6));

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
                *dsfield = ipv6_get_dsfield(ipv6h);
        else
                *dsfield = ip6_tclass(t->parms.flowinfo);

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)
                fl6->flowlabel |= ip6_flowlabel(ipv6h);

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                fl6->flowi6_mark = skb->mark;
        else
                fl6->flowi6_mark = t->parms.fwmark;

        fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);

        return 0;
}

static int prepare_ip6gre_xmit_other(struct sk_buff *skb,
                                     struct net_device *dev,
                                     struct flowi6 *fl6, __u8 *dsfield,
                                     int *encap_limit)
{
        struct ip6_tnl *t = netdev_priv(dev);

        if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                *encap_limit = t->parms.encap_limit;

        memcpy(fl6, &t->fl.u.ip6, sizeof(*fl6));

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
                *dsfield = 0;
        else
                *dsfield = ip6_tclass(t->parms.flowinfo);

        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                fl6->flowi6_mark = skb->mark;
        else
                fl6->flowi6_mark = t->parms.fwmark;

        fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);

        return 0;
}

static struct ip_tunnel_info *skb_tunnel_info_txcheck(struct sk_buff *skb)
{
        struct ip_tunnel_info *tun_info;

        tun_info = skb_tunnel_info(skb);
        if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX)))
                return ERR_PTR(-EINVAL);

        return tun_info;
}

static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
                               struct net_device *dev, __u8 dsfield,
                               struct flowi6 *fl6, int encap_limit,
                               __u32 *pmtu, __be16 proto)
{
        struct ip6_tnl *tunnel = netdev_priv(dev);
        IP_TUNNEL_DECLARE_FLAGS(flags);
        __be16 protocol;

        if (dev->type == ARPHRD_ETHER)
                IPCB(skb)->flags = 0;

        if (dev->header_ops && dev->type == ARPHRD_IP6GRE)
                fl6->daddr = ((struct ipv6hdr *)skb->data)->daddr;
        else
                fl6->daddr = tunnel->parms.raddr;

        /* Push GRE header. */
        protocol = (dev->type == ARPHRD_ETHER) ? htons(ETH_P_TEB) : proto;

        if (tunnel->parms.collect_md) {
                struct ip_tunnel_info *tun_info;
                const struct ip_tunnel_key *key;
                int tun_hlen;

                tun_info = skb_tunnel_info_txcheck(skb);
                if (IS_ERR(tun_info) ||
                    unlikely(ip_tunnel_info_af(tun_info) != AF_INET6))
                        return -EINVAL;

                key = &tun_info->key;
                memset(fl6, 0, sizeof(*fl6));
                fl6->flowi6_proto = IPPROTO_GRE;
                fl6->daddr = key->u.ipv6.dst;
                fl6->flowlabel = key->label;
                fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);
                fl6->fl6_gre_key = tunnel_id_to_key32(key->tun_id);

                dsfield = key->tos;
                ip_tunnel_flags_zero(flags);
                __set_bit(IP_TUNNEL_CSUM_BIT, flags);
                __set_bit(IP_TUNNEL_KEY_BIT, flags);
                __set_bit(IP_TUNNEL_SEQ_BIT, flags);
                ip_tunnel_flags_and(flags, flags, key->tun_flags);
                tun_hlen = gre_calc_hlen(flags);

                if (skb_cow_head(skb, dev->needed_headroom ?: tun_hlen + tunnel->encap_hlen))
                        return -ENOMEM;

                gre_build_header(skb, tun_hlen,
                                 flags, protocol,
                                 tunnel_id_to_key32(tun_info->key.tun_id),
                                 test_bit(IP_TUNNEL_SEQ_BIT, flags) ?
                                 htonl(atomic_fetch_inc(&tunnel->o_seqno)) :
                                 0);

        } else {
                if (skb_cow_head(skb, dev->needed_headroom ?: tunnel->hlen))
                        return -ENOMEM;

                ip_tunnel_flags_copy(flags, tunnel->parms.o_flags);

                gre_build_header(skb, tunnel->tun_hlen, flags,
                                 protocol, tunnel->parms.o_key,
                                 test_bit(IP_TUNNEL_SEQ_BIT, flags) ?
                                 htonl(atomic_fetch_inc(&tunnel->o_seqno)) :
                                 0);
        }

        return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu,
                            NEXTHDR_GRE);
}

static inline int ip6gre_xmit_ipv4(struct sk_buff *skb, struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int encap_limit = -1;
        struct flowi6 fl6;
        __u8 dsfield = 0;
        __u32 mtu;
        int err;

        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

        if (!t->parms.collect_md)
                prepare_ip6gre_xmit_ipv4(skb, dev, &fl6,
                                         &dsfield, &encap_limit);

        err = gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
                                                t->parms.o_flags));
        if (err)
                return -1;

        err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
                          skb->protocol);
        if (err != 0) {
                /* XXX: send ICMP error even if DF is not set. */
                if (err == -EMSGSIZE)
                        icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
                                      htonl(mtu));
                return -1;
        }

        return 0;
}

static inline int ip6gre_xmit_ipv6(struct sk_buff *skb, struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ipv6hdr *ipv6h = ipv6_hdr(skb);
        int encap_limit = -1;
        struct flowi6 fl6;
        __u8 dsfield = 0;
        __u32 mtu;
        int err;

        if (ipv6_addr_equal(&t->parms.raddr, &ipv6h->saddr))
                return -1;

        if (!t->parms.collect_md &&
            prepare_ip6gre_xmit_ipv6(skb, dev, &fl6, &dsfield, &encap_limit))
                return -1;

        if (gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
                                              t->parms.o_flags)))
                return -1;

        err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit,
                          &mtu, skb->protocol);
        if (err != 0) {
                if (err == -EMSGSIZE)
                        icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
                return -1;
        }

        return 0;
}

static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int encap_limit = -1;
        struct flowi6 fl6;
        __u8 dsfield = 0;
        __u32 mtu;
        int err;

        if (!t->parms.collect_md &&
            prepare_ip6gre_xmit_other(skb, dev, &fl6, &dsfield, &encap_limit))
                return -1;

        err = gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
                                                t->parms.o_flags));
        if (err)
                return err;
        err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu, skb->protocol);

        return err;
}

static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb,
        struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        __be16 payload_protocol;
        int ret;

        if (!pskb_inet_may_pull(skb))
                goto tx_err;

        if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
                goto tx_err;

        payload_protocol = skb_protocol(skb, true);
        switch (payload_protocol) {
        case htons(ETH_P_IP):
                ret = ip6gre_xmit_ipv4(skb, dev);
                break;
        case htons(ETH_P_IPV6):
                ret = ip6gre_xmit_ipv6(skb, dev);
                break;
        default:
                ret = ip6gre_xmit_other(skb, dev);
                break;
        }

        if (ret < 0)
                goto tx_err;

        return NETDEV_TX_OK;

tx_err:
        if (!t->parms.collect_md || !IS_ERR(skb_tunnel_info_txcheck(skb)))
                DEV_STATS_INC(dev, tx_errors);
        DEV_STATS_INC(dev, tx_dropped);
        kfree_skb(skb);
        return NETDEV_TX_OK;
}

static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
                                         struct net_device *dev)
{
        struct ip_tunnel_info *tun_info = NULL;
        struct ip6_tnl *t = netdev_priv(dev);
        struct dst_entry *dst = skb_dst(skb);
        IP_TUNNEL_DECLARE_FLAGS(flags) = { };
        bool truncate = false;
        int encap_limit = -1;
        __u8 dsfield = false;
        struct flowi6 fl6;
        int err = -EINVAL;
        __be16 proto;
        __u32 mtu;
        int nhoff;

        if (!pskb_inet_may_pull(skb))
                goto tx_err;

        if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
                goto tx_err;

        if (gre_handle_offloads(skb, false))
                goto tx_err;

        if (skb->len > dev->mtu + dev->hard_header_len) {
                if (pskb_trim(skb, dev->mtu + dev->hard_header_len))
                        goto tx_err;
                truncate = true;
        }

        nhoff = skb_network_offset(skb);
        if (skb->protocol == htons(ETH_P_IP) &&
            (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
                truncate = true;

        if (skb->protocol == htons(ETH_P_IPV6)) {
                int thoff;

                if (skb_transport_header_was_set(skb))
                        thoff = skb_transport_offset(skb);
                else
                        thoff = nhoff + sizeof(struct ipv6hdr);
                if (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff)
                        truncate = true;
        }

        if (skb_cow_head(skb, dev->needed_headroom ?: t->hlen))
                goto tx_err;

        __clear_bit(IP_TUNNEL_KEY_BIT, t->parms.o_flags);
        IPCB(skb)->flags = 0;

        /* For collect_md mode, derive fl6 from the tunnel key,
         * for native mode, call prepare_ip6gre_xmit_{ipv4,ipv6}.
         */
        if (t->parms.collect_md) {
                const struct ip_tunnel_key *key;
                struct erspan_metadata *md;
                __be32 tun_id;

                tun_info = skb_tunnel_info_txcheck(skb);
                if (IS_ERR(tun_info) ||
                    unlikely(ip_tunnel_info_af(tun_info) != AF_INET6))
                        goto tx_err;

                key = &tun_info->key;
                memset(&fl6, 0, sizeof(fl6));
                fl6.flowi6_proto = IPPROTO_GRE;
                fl6.daddr = key->u.ipv6.dst;
                fl6.flowlabel = key->label;
                fl6.flowi6_uid = sock_net_uid(dev_net(dev), NULL);
                fl6.fl6_gre_key = tunnel_id_to_key32(key->tun_id);

                dsfield = key->tos;
                if (!test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
                              tun_info->key.tun_flags))
                        goto tx_err;
                if (tun_info->options_len < sizeof(*md))
                        goto tx_err;
                md = ip_tunnel_info_opts(tun_info);

                tun_id = tunnel_id_to_key32(key->tun_id);
                if (md->version == 1) {
                        erspan_build_header(skb,
                                            ntohl(tun_id),
                                            ntohl(md->u.index), truncate,
                                            false);
                        proto = htons(ETH_P_ERSPAN);
                } else if (md->version == 2) {
                        erspan_build_header_v2(skb,
                                               ntohl(tun_id),
                                               md->u.md2.dir,
                                               get_hwid(&md->u.md2),
                                               truncate, false);
                        proto = htons(ETH_P_ERSPAN2);
                } else {
                        goto tx_err;
                }
        } else {
                switch (skb->protocol) {
                case htons(ETH_P_IP):
                        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
                        prepare_ip6gre_xmit_ipv4(skb, dev, &fl6,
                                                 &dsfield, &encap_limit);
                        break;
                case htons(ETH_P_IPV6):
                        if (ipv6_addr_equal(&t->parms.raddr, &ipv6_hdr(skb)->saddr))
                                goto tx_err;
                        if (prepare_ip6gre_xmit_ipv6(skb, dev, &fl6,
                                                     &dsfield, &encap_limit))
                                goto tx_err;
                        break;
                default:
                        memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
                        break;
                }

                if (t->parms.erspan_ver == 1) {
                        erspan_build_header(skb, ntohl(t->parms.o_key),
                                            t->parms.index,
                                            truncate, false);
                        proto = htons(ETH_P_ERSPAN);
                } else if (t->parms.erspan_ver == 2) {
                        erspan_build_header_v2(skb, ntohl(t->parms.o_key),
                                               t->parms.dir,
                                               t->parms.hwid,
                                               truncate, false);
                        proto = htons(ETH_P_ERSPAN2);
                } else {
                        goto tx_err;
                }

                fl6.daddr = t->parms.raddr;
        }

        /* Push GRE header. */
        __set_bit(IP_TUNNEL_SEQ_BIT, flags);
        gre_build_header(skb, 8, flags, proto, 0,
                         htonl(atomic_fetch_inc(&t->o_seqno)));

        /* TooBig packet may have updated dst->dev's mtu */
        if (!t->parms.collect_md && dst) {
                mtu = READ_ONCE(dst_dev(dst)->mtu);
                if (dst6_mtu(dst) > mtu)
                        dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
        }
        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
                           NEXTHDR_GRE);
        if (err != 0) {
                /* XXX: send ICMP error even if DF is not set. */
                if (err == -EMSGSIZE) {
                        if (skb->protocol == htons(ETH_P_IP))
                                icmp_ndo_send(skb, ICMP_DEST_UNREACH,
                                              ICMP_FRAG_NEEDED, htonl(mtu));
                        else
                                icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
                }

                goto tx_err;
        }
        return NETDEV_TX_OK;

tx_err:
        if (!IS_ERR(tun_info))
                DEV_STATS_INC(dev, tx_errors);
        DEV_STATS_INC(dev, tx_dropped);
        kfree_skb(skb);
        return NETDEV_TX_OK;
}

static void ip6gre_tnl_link_config_common(struct ip6_tnl *t)
{
        struct net_device *dev = t->dev;
        struct __ip6_tnl_parm *p = &t->parms;
        struct flowi6 *fl6 = &t->fl.u.ip6;

        if (dev->type != ARPHRD_ETHER) {
                __dev_addr_set(dev, &p->laddr, sizeof(struct in6_addr));
                memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr));
        }

        /* Set up flowi template */
        fl6->saddr = p->laddr;
        fl6->daddr = p->raddr;
        fl6->flowi6_oif = p->link;
        fl6->flowlabel = 0;
        fl6->flowi6_proto = IPPROTO_GRE;
        fl6->fl6_gre_key = t->parms.o_key;

        if (!(p->flags&IP6_TNL_F_USE_ORIG_TCLASS))
                fl6->flowlabel |= IPV6_TCLASS_MASK & p->flowinfo;
        if (!(p->flags&IP6_TNL_F_USE_ORIG_FLOWLABEL))
                fl6->flowlabel |= IPV6_FLOWLABEL_MASK & p->flowinfo;

        p->flags &= ~(IP6_TNL_F_CAP_XMIT|IP6_TNL_F_CAP_RCV|IP6_TNL_F_CAP_PER_PACKET);
        p->flags |= ip6_tnl_get_cap(t, &p->laddr, &p->raddr);

        if (p->flags&IP6_TNL_F_CAP_XMIT &&
                        p->flags&IP6_TNL_F_CAP_RCV && dev->type != ARPHRD_ETHER)
                dev->flags |= IFF_POINTOPOINT;
        else
                dev->flags &= ~IFF_POINTOPOINT;
}

static void ip6gre_tnl_link_config_route(struct ip6_tnl *t, int set_mtu,
                                         int t_hlen)
{
        const struct __ip6_tnl_parm *p = &t->parms;
        struct net_device *dev = t->dev;

        if (p->flags & IP6_TNL_F_CAP_XMIT) {
                int strict = (ipv6_addr_type(&p->raddr) &
                              (IPV6_ADDR_MULTICAST|IPV6_ADDR_LINKLOCAL));

                struct rt6_info *rt = rt6_lookup(t->net,
                                                 &p->raddr, &p->laddr,
                                                 p->link, NULL, strict);

                if (!rt)
                        return;

                if (rt->dst.dev) {
                        unsigned short dst_len = rt->dst.dev->hard_header_len +
                                                 t_hlen;

                        if (t->dev->header_ops)
                                dev->hard_header_len = dst_len;
                        else
                                dev->needed_headroom = dst_len;

                        if (set_mtu) {
                                int mtu = rt->dst.dev->mtu - t_hlen;

                                if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                                        mtu -= 8;
                                if (dev->type == ARPHRD_ETHER)
                                        mtu -= ETH_HLEN;

                                if (mtu < IPV6_MIN_MTU)
                                        mtu = IPV6_MIN_MTU;
                                WRITE_ONCE(dev->mtu, mtu);
                        }
                }
                ip6_rt_put(rt);
        }
}

static int ip6gre_calc_hlen(struct ip6_tnl *tunnel)
{
        int t_hlen;

        tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
        tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;

        t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);

        if (tunnel->dev->header_ops)
                tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;
        else
                tunnel->dev->needed_headroom = LL_MAX_HEADER + t_hlen;

        return t_hlen;
}

static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)
{
        ip6gre_tnl_link_config_common(t);
        ip6gre_tnl_link_config_route(t, set_mtu, ip6gre_calc_hlen(t));
}

static void ip6gre_tnl_copy_tnl_parm(struct ip6_tnl *t,
                                     const struct __ip6_tnl_parm *p)
{
        t->parms.laddr = p->laddr;
        t->parms.raddr = p->raddr;
        t->parms.flags = p->flags;
        t->parms.hop_limit = p->hop_limit;
        t->parms.encap_limit = p->encap_limit;
        t->parms.flowinfo = p->flowinfo;
        t->parms.link = p->link;
        t->parms.proto = p->proto;
        t->parms.i_key = p->i_key;
        t->parms.o_key = p->o_key;
        ip_tunnel_flags_copy(t->parms.i_flags, p->i_flags);
        ip_tunnel_flags_copy(t->parms.o_flags, p->o_flags);
        t->parms.fwmark = p->fwmark;
        t->parms.erspan_ver = p->erspan_ver;
        t->parms.index = p->index;
        t->parms.dir = p->dir;
        t->parms.hwid = p->hwid;
        dst_cache_reset(&t->dst_cache);
}

static int ip6gre_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p,
                             int set_mtu)
{
        ip6gre_tnl_copy_tnl_parm(t, p);
        ip6gre_tnl_link_config(t, set_mtu);
        return 0;
}

static void ip6gre_tnl_parm_from_user(struct __ip6_tnl_parm *p,
        const struct ip6_tnl_parm2 *u)
{
        p->laddr = u->laddr;
        p->raddr = u->raddr;
        p->flags = u->flags;
        p->hop_limit = u->hop_limit;
        p->encap_limit = u->encap_limit;
        p->flowinfo = u->flowinfo;
        p->link = u->link;
        p->i_key = u->i_key;
        p->o_key = u->o_key;
        gre_flags_to_tnl_flags(p->i_flags, u->i_flags);
        gre_flags_to_tnl_flags(p->o_flags, u->o_flags);
        memcpy(p->name, u->name, sizeof(u->name));
}

static void ip6gre_tnl_parm_to_user(struct ip6_tnl_parm2 *u,
        const struct __ip6_tnl_parm *p)
{
        u->proto = IPPROTO_GRE;
        u->laddr = p->laddr;
        u->raddr = p->raddr;
        u->flags = p->flags;
        u->hop_limit = p->hop_limit;
        u->encap_limit = p->encap_limit;
        u->flowinfo = p->flowinfo;
        u->link = p->link;
        u->i_key = p->i_key;
        u->o_key = p->o_key;
        u->i_flags = gre_tnl_flags_to_gre_flags(p->i_flags);
        u->o_flags = gre_tnl_flags_to_gre_flags(p->o_flags);
        memcpy(u->name, p->name, sizeof(u->name));
}

static int ip6gre_tunnel_siocdevprivate(struct net_device *dev,
                                        struct ifreq *ifr, void __user *data,
                                        int cmd)
{
        int err = 0;
        struct ip6_tnl_parm2 p;
        struct __ip6_tnl_parm p1;
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = t->net;
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

        memset(&p1, 0, sizeof(p1));

        switch (cmd) {
        case SIOCGETTUNNEL:
                if (dev == ign->fb_tunnel_dev) {
                        if (copy_from_user(&p, data, sizeof(p))) {
                                err = -EFAULT;
                                break;
                        }
                        ip6gre_tnl_parm_from_user(&p1, &p);
                        t = ip6gre_tunnel_locate(net, &p1, 0);
                        if (!t)
                                t = netdev_priv(dev);
                }
                memset(&p, 0, sizeof(p));
                ip6gre_tnl_parm_to_user(&p, &t->parms);
                if (copy_to_user(data, &p, sizeof(p)))
                        err = -EFAULT;
                break;

        case SIOCADDTUNNEL:
        case SIOCCHGTUNNEL:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        goto done;

                err = -EFAULT;
                if (copy_from_user(&p, data, sizeof(p)))
                        goto done;

                err = -EINVAL;
                if ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING))
                        goto done;

                if (!(p.i_flags&GRE_KEY))
                        p.i_key = 0;
                if (!(p.o_flags&GRE_KEY))
                        p.o_key = 0;

                ip6gre_tnl_parm_from_user(&p1, &p);
                t = ip6gre_tunnel_locate(net, &p1, cmd == SIOCADDTUNNEL);

                if (dev != ign->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
                        if (t) {
                                if (t->dev != dev) {
                                        err = -EEXIST;
                                        break;
                                }
                        } else {
                                t = netdev_priv(dev);

                                ip6gre_tunnel_unlink(ign, t);
                                synchronize_net();
                                ip6gre_tnl_change(t, &p1, 1);
                                ip6gre_tunnel_link(ign, t);
                                netdev_state_change(dev);
                        }
                }

                if (t) {
                        err = 0;

                        memset(&p, 0, sizeof(p));
                        ip6gre_tnl_parm_to_user(&p, &t->parms);
                        if (copy_to_user(data, &p, sizeof(p)))
                                err = -EFAULT;
                } else
                        err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
                break;

        case SIOCDELTUNNEL:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        goto done;

                if (dev == ign->fb_tunnel_dev) {
                        err = -EFAULT;
                        if (copy_from_user(&p, data, sizeof(p)))
                                goto done;
                        err = -ENOENT;
                        ip6gre_tnl_parm_from_user(&p1, &p);
                        t = ip6gre_tunnel_locate(net, &p1, 0);
                        if (!t)
                                goto done;
                        err = -EPERM;
                        if (t == netdev_priv(ign->fb_tunnel_dev))
                                goto done;
                        dev = t->dev;
                }
                unregister_netdevice(dev);
                err = 0;
                break;

        default:
                err = -EINVAL;
        }

done:
        return err;
}

static int ip6gre_header(struct sk_buff *skb, struct net_device *dev,
                         unsigned short type, const void *daddr,
                         const void *saddr, unsigned int len)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ipv6hdr *ipv6h;
        int needed;
        __be16 *p;

        needed = t->hlen + sizeof(*ipv6h);
        if (skb_headroom(skb) < needed &&
            pskb_expand_head(skb, HH_DATA_ALIGN(needed - skb_headroom(skb)),
                             0, GFP_ATOMIC))
                return -needed;

        ipv6h = skb_push(skb, needed);
        ip6_flow_hdr(ipv6h, 0, ip6_make_flowlabel(dev_net(dev), skb,
                                                  t->fl.u.ip6.flowlabel,
                                                  true, &t->fl.u.ip6));
        ipv6h->hop_limit = t->parms.hop_limit;
        ipv6h->nexthdr = NEXTHDR_GRE;
        ipv6h->saddr = t->parms.laddr;
        ipv6h->daddr = t->parms.raddr;

        p = (__be16 *)(ipv6h + 1);
        p[0] = ip_tunnel_flags_to_be16(t->parms.o_flags);
        p[1] = htons(type);

        /*
         *      Set the source hardware address.
         */

        if (saddr)
                memcpy(&ipv6h->saddr, saddr, sizeof(struct in6_addr));
        if (daddr)
                memcpy(&ipv6h->daddr, daddr, sizeof(struct in6_addr));
        if (!ipv6_addr_any(&ipv6h->daddr))
                return t->hlen;

        return -t->hlen;
}

static const struct header_ops ip6gre_header_ops = {
        .create = ip6gre_header,
};

static const struct net_device_ops ip6gre_netdev_ops = {
        .ndo_init               = ip6gre_tunnel_init,
        .ndo_uninit             = ip6gre_tunnel_uninit,
        .ndo_start_xmit         = ip6gre_tunnel_xmit,
        .ndo_siocdevprivate     = ip6gre_tunnel_siocdevprivate,
        .ndo_change_mtu         = ip6_tnl_change_mtu,
        .ndo_get_iflink         = ip6_tnl_get_iflink,
};

static void ip6gre_dev_free(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);

        gro_cells_destroy(&t->gro_cells);
        dst_cache_destroy(&t->dst_cache);
}

static void ip6gre_tunnel_setup(struct net_device *dev)
{
        dev->netdev_ops = &ip6gre_netdev_ops;
        dev->needs_free_netdev = true;
        dev->priv_destructor = ip6gre_dev_free;

        dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
        dev->type = ARPHRD_IP6GRE;

        dev->flags |= IFF_NOARP;
        dev->addr_len = sizeof(struct in6_addr);
        netif_keep_dst(dev);
        /* This perm addr will be used as interface identifier by IPv6 */
        dev->addr_assign_type = NET_ADDR_RANDOM;
        eth_random_addr(dev->perm_addr);
}

#define GRE6_FEATURES (NETIF_F_SG |             \
                       NETIF_F_FRAGLIST |       \
                       NETIF_F_HIGHDMA |        \
                       NETIF_F_HW_CSUM)

static void ip6gre_tnl_init_features(struct net_device *dev)
{
        struct ip6_tnl *nt = netdev_priv(dev);

        dev->features           |= GRE6_FEATURES;
        dev->hw_features        |= GRE6_FEATURES;

        /* TCP offload with GRE SEQ is not supported, nor can we support 2
         * levels of outer headers requiring an update.
         */
        if (test_bit(IP_TUNNEL_SEQ_BIT, nt->parms.o_flags))
                return;
        if (test_bit(IP_TUNNEL_CSUM_BIT, nt->parms.o_flags) &&
            nt->encap.type != TUNNEL_ENCAP_NONE)
                return;

        dev->features |= NETIF_F_GSO_SOFTWARE;
        dev->hw_features |= NETIF_F_GSO_SOFTWARE;

        dev->lltx = true;
}

static int ip6gre_tunnel_init_common(struct net_device *dev)
{
        struct ip6_tnl *tunnel;
        int ret;
        int t_hlen;

        tunnel = netdev_priv(dev);

        tunnel->dev = dev;
        strscpy(tunnel->parms.name, dev->name);

        ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
        if (ret)
                return ret;

        ret = gro_cells_init(&tunnel->gro_cells, dev);
        if (ret)
                goto cleanup_dst_cache_init;

        t_hlen = ip6gre_calc_hlen(tunnel);
        dev->mtu = ETH_DATA_LEN - t_hlen;
        if (dev->type == ARPHRD_ETHER)
                dev->mtu -= ETH_HLEN;
        if (!(tunnel->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                dev->mtu -= 8;

        if (tunnel->parms.collect_md) {
                netif_keep_dst(dev);
        }
        ip6gre_tnl_init_features(dev);

        netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
        netdev_lockdep_set_classes(dev);
        return 0;

cleanup_dst_cache_init:
        dst_cache_destroy(&tunnel->dst_cache);
        return ret;
}

static int ip6gre_tunnel_init(struct net_device *dev)
{
        struct ip6_tnl *tunnel;
        int ret;

        ret = ip6gre_tunnel_init_common(dev);
        if (ret)
                return ret;

        tunnel = netdev_priv(dev);

        if (tunnel->parms.collect_md)
                return 0;

        __dev_addr_set(dev, &tunnel->parms.laddr, sizeof(struct in6_addr));
        memcpy(dev->broadcast, &tunnel->parms.raddr, sizeof(struct in6_addr));

        if (ipv6_addr_any(&tunnel->parms.raddr))
                dev->header_ops = &ip6gre_header_ops;

        return 0;
}

static void ip6gre_fb_tunnel_init(struct net_device *dev)
{
        struct ip6_tnl *tunnel = netdev_priv(dev);

        tunnel->dev = dev;
        tunnel->net = dev_net(dev);
        strscpy(tunnel->parms.name, dev->name);

        tunnel->hlen            = sizeof(struct ipv6hdr) + 4;
}

static struct inet6_protocol ip6gre_protocol __read_mostly = {
        .handler     = gre_rcv,
        .err_handler = ip6gre_err,
        .flags       = INET6_PROTO_FINAL,
};

static void __net_exit ip6gre_exit_rtnl_net(struct net *net, struct list_head *head)
{
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
        struct net_device *dev, *aux;
        int prio;

        for_each_netdev_safe(net, dev, aux)
                if (dev->rtnl_link_ops == &ip6gre_link_ops ||
                    dev->rtnl_link_ops == &ip6gre_tap_ops ||
                    dev->rtnl_link_ops == &ip6erspan_tap_ops)
                        unregister_netdevice_queue(dev, head);

        for (prio = 0; prio < 4; prio++) {
                int h;
                for (h = 0; h < IP6_GRE_HASH_SIZE; h++) {
                        struct ip6_tnl *t;

                        t = rtnl_net_dereference(net, ign->tunnels[prio][h]);

                        while (t) {
                                /* If dev is in the same netns, it has already
                                 * been added to the list by the previous loop.
                                 */
                                if (!net_eq(dev_net(t->dev), net))
                                        unregister_netdevice_queue(t->dev, head);

                                t = rtnl_net_dereference(net, t->next);
                        }
                }
        }
}

static int __net_init ip6gre_init_net(struct net *net)
{
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
        struct net_device *ndev;
        int err;

        if (!net_has_fallback_tunnels(net))
                return 0;
        ndev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
                            NET_NAME_UNKNOWN, ip6gre_tunnel_setup);
        if (!ndev) {
                err = -ENOMEM;
                goto err_alloc_dev;
        }
        ign->fb_tunnel_dev = ndev;
        dev_net_set(ign->fb_tunnel_dev, net);
        /* FB netdevice is special: we have one, and only one per netns.
         * Allowing to move it to another netns is clearly unsafe.
         */
        ign->fb_tunnel_dev->netns_immutable = true;

        ip6gre_fb_tunnel_init(ign->fb_tunnel_dev);
        ign->fb_tunnel_dev->rtnl_link_ops = &ip6gre_link_ops;

        err = register_netdev(ign->fb_tunnel_dev);
        if (err)
                goto err_reg_dev;

        rcu_assign_pointer(ign->tunnels_wc[0],
                           netdev_priv(ign->fb_tunnel_dev));
        return 0;

err_reg_dev:
        free_netdev(ndev);
err_alloc_dev:
        return err;
}

static struct pernet_operations ip6gre_net_ops = {
        .init = ip6gre_init_net,
        .exit_rtnl = ip6gre_exit_rtnl_net,
        .id   = &ip6gre_net_id,
        .size = sizeof(struct ip6gre_net),
};

static int ip6gre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
                                  struct netlink_ext_ack *extack)
{
        __be16 flags;

        if (!data)
                return 0;

        flags = 0;
        if (data[IFLA_GRE_IFLAGS])
                flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
        if (data[IFLA_GRE_OFLAGS])
                flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
        if (flags & (GRE_VERSION|GRE_ROUTING))
                return -EINVAL;

        return 0;
}

static int ip6gre_tap_validate(struct nlattr *tb[], struct nlattr *data[],
                               struct netlink_ext_ack *extack)
{
        struct in6_addr daddr;

        if (tb[IFLA_ADDRESS]) {
                if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
                        return -EINVAL;
                if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
                        return -EADDRNOTAVAIL;
        }

        if (!data)
                goto out;

        if (data[IFLA_GRE_REMOTE]) {
                daddr = nla_get_in6_addr(data[IFLA_GRE_REMOTE]);
                if (ipv6_addr_any(&daddr))
                        return -EINVAL;
        }

out:
        return ip6gre_tunnel_validate(tb, data, extack);
}

static int ip6erspan_tap_validate(struct nlattr *tb[], struct nlattr *data[],
                                  struct netlink_ext_ack *extack)
{
        __be16 flags = 0;
        int ret, ver = 0;

        if (!data)
                return 0;

        ret = ip6gre_tap_validate(tb, data, extack);
        if (ret)
                return ret;

        /* ERSPAN should only have GRE sequence and key flag */
        if (data[IFLA_GRE_OFLAGS])
                flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
        if (data[IFLA_GRE_IFLAGS])
                flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
        if (!data[IFLA_GRE_COLLECT_METADATA] &&
            flags != (GRE_SEQ | GRE_KEY))
                return -EINVAL;

        /* ERSPAN Session ID only has 10-bit. Since we reuse
         * 32-bit key field as ID, check it's range.
         */
        if (data[IFLA_GRE_IKEY] &&
            (ntohl(nla_get_be32(data[IFLA_GRE_IKEY])) & ~ID_MASK))
                return -EINVAL;

        if (data[IFLA_GRE_OKEY] &&
            (ntohl(nla_get_be32(data[IFLA_GRE_OKEY])) & ~ID_MASK))
                return -EINVAL;

        if (data[IFLA_GRE_ERSPAN_VER]) {
                ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);
                if (ver != 1 && ver != 2)
                        return -EINVAL;
        }

        if (ver == 1) {
                if (data[IFLA_GRE_ERSPAN_INDEX]) {
                        u32 index = nla_get_u32(data[IFLA_GRE_ERSPAN_INDEX]);

                        if (index & ~INDEX_MASK)
                                return -EINVAL;
                }
        } else if (ver == 2) {
                if (data[IFLA_GRE_ERSPAN_DIR]) {
                        u16 dir = nla_get_u8(data[IFLA_GRE_ERSPAN_DIR]);

                        if (dir & ~(DIR_MASK >> DIR_OFFSET))
                                return -EINVAL;
                }

                if (data[IFLA_GRE_ERSPAN_HWID]) {
                        u16 hwid = nla_get_u16(data[IFLA_GRE_ERSPAN_HWID]);

                        if (hwid & ~(HWID_MASK >> HWID_OFFSET))
                                return -EINVAL;
                }
        }

        return 0;
}

static void ip6erspan_set_version(struct nlattr *data[],
                                  struct __ip6_tnl_parm *parms)
{
        if (!data)
                return;

        parms->erspan_ver = 1;
        if (data[IFLA_GRE_ERSPAN_VER])
                parms->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);

        if (parms->erspan_ver == 1) {
                if (data[IFLA_GRE_ERSPAN_INDEX])
                        parms->index = nla_get_u32(data[IFLA_GRE_ERSPAN_INDEX]);
        } else if (parms->erspan_ver == 2) {
                if (data[IFLA_GRE_ERSPAN_DIR])
                        parms->dir = nla_get_u8(data[IFLA_GRE_ERSPAN_DIR]);
                if (data[IFLA_GRE_ERSPAN_HWID])
                        parms->hwid = nla_get_u16(data[IFLA_GRE_ERSPAN_HWID]);
        }
}

static void ip6gre_netlink_parms(struct nlattr *data[],
                                struct __ip6_tnl_parm *parms)
{
        memset(parms, 0, sizeof(*parms));

        if (!data)
                return;

        if (data[IFLA_GRE_LINK])
                parms->link = nla_get_u32(data[IFLA_GRE_LINK]);

        if (data[IFLA_GRE_IFLAGS])
                gre_flags_to_tnl_flags(parms->i_flags,
                                       nla_get_be16(data[IFLA_GRE_IFLAGS]));

        if (data[IFLA_GRE_OFLAGS])
                gre_flags_to_tnl_flags(parms->o_flags,
                                       nla_get_be16(data[IFLA_GRE_OFLAGS]));

        if (data[IFLA_GRE_IKEY])
                parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);

        if (data[IFLA_GRE_OKEY])
                parms->o_key = nla_get_be32(data[IFLA_GRE_OKEY]);

        if (data[IFLA_GRE_LOCAL])
                parms->laddr = nla_get_in6_addr(data[IFLA_GRE_LOCAL]);

        if (data[IFLA_GRE_REMOTE])
                parms->raddr = nla_get_in6_addr(data[IFLA_GRE_REMOTE]);

        if (data[IFLA_GRE_TTL])
                parms->hop_limit = nla_get_u8(data[IFLA_GRE_TTL]);

        if (data[IFLA_GRE_ENCAP_LIMIT])
                parms->encap_limit = nla_get_u8(data[IFLA_GRE_ENCAP_LIMIT]);

        if (data[IFLA_GRE_FLOWINFO])
                parms->flowinfo = nla_get_be32(data[IFLA_GRE_FLOWINFO]);

        if (data[IFLA_GRE_FLAGS])
                parms->flags = nla_get_u32(data[IFLA_GRE_FLAGS]);

        if (data[IFLA_GRE_FWMARK])
                parms->fwmark = nla_get_u32(data[IFLA_GRE_FWMARK]);

        if (data[IFLA_GRE_COLLECT_METADATA])
                parms->collect_md = true;
}

static int ip6gre_tap_init(struct net_device *dev)
{
        int ret;

        ret = ip6gre_tunnel_init_common(dev);
        if (ret)
                return ret;

        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

        return 0;
}

static const struct net_device_ops ip6gre_tap_netdev_ops = {
        .ndo_init = ip6gre_tap_init,
        .ndo_uninit = ip6gre_tunnel_uninit,
        .ndo_start_xmit = ip6gre_tunnel_xmit,
        .ndo_set_mac_address = eth_mac_addr,
        .ndo_validate_addr = eth_validate_addr,
        .ndo_change_mtu = ip6_tnl_change_mtu,
        .ndo_get_iflink = ip6_tnl_get_iflink,
};

static int ip6erspan_calc_hlen(struct ip6_tnl *tunnel)
{
        int t_hlen;

        tunnel->tun_hlen = 8;
        tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
                       erspan_hdr_len(tunnel->parms.erspan_ver);

        t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
        tunnel->dev->needed_headroom = LL_MAX_HEADER + t_hlen;
        return t_hlen;
}

static int ip6erspan_tap_init(struct net_device *dev)
{
        struct ip6_tnl *tunnel;
        int t_hlen;
        int ret;

        tunnel = netdev_priv(dev);

        tunnel->dev = dev;
        strscpy(tunnel->parms.name, dev->name);

        ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
        if (ret)
                return ret;

        ret = gro_cells_init(&tunnel->gro_cells, dev);
        if (ret)
                goto cleanup_dst_cache_init;

        t_hlen = ip6erspan_calc_hlen(tunnel);
        dev->mtu = ETH_DATA_LEN - t_hlen;
        if (dev->type == ARPHRD_ETHER)
                dev->mtu -= ETH_HLEN;
        if (!(tunnel->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                dev->mtu -= 8;

        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
        ip6erspan_tnl_link_config(tunnel, 1);

        netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
        netdev_lockdep_set_classes(dev);
        return 0;

cleanup_dst_cache_init:
        dst_cache_destroy(&tunnel->dst_cache);
        return ret;
}

static const struct net_device_ops ip6erspan_netdev_ops = {
        .ndo_init =             ip6erspan_tap_init,
        .ndo_uninit =           ip6erspan_tunnel_uninit,
        .ndo_start_xmit =       ip6erspan_tunnel_xmit,
        .ndo_set_mac_address =  eth_mac_addr,
        .ndo_validate_addr =    eth_validate_addr,
        .ndo_change_mtu =       ip6_tnl_change_mtu,
        .ndo_get_iflink =       ip6_tnl_get_iflink,
};

static void ip6gre_tap_setup(struct net_device *dev)
{

        ether_setup(dev);

        dev->max_mtu = 0;
        dev->netdev_ops = &ip6gre_tap_netdev_ops;
        dev->needs_free_netdev = true;
        dev->priv_destructor = ip6gre_dev_free;

        dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
        dev->priv_flags &= ~IFF_TX_SKB_SHARING;
        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
        netif_keep_dst(dev);
}

static bool ip6gre_netlink_encap_parms(struct nlattr *data[],
                                       struct ip_tunnel_encap *ipencap)
{
        bool ret = false;

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

        if (!data)
                return ret;

        if (data[IFLA_GRE_ENCAP_TYPE]) {
                ret = true;
                ipencap->type = nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]);
        }

        if (data[IFLA_GRE_ENCAP_FLAGS]) {
                ret = true;
                ipencap->flags = nla_get_u16(data[IFLA_GRE_ENCAP_FLAGS]);
        }

        if (data[IFLA_GRE_ENCAP_SPORT]) {
                ret = true;
                ipencap->sport = nla_get_be16(data[IFLA_GRE_ENCAP_SPORT]);
        }

        if (data[IFLA_GRE_ENCAP_DPORT]) {
                ret = true;
                ipencap->dport = nla_get_be16(data[IFLA_GRE_ENCAP_DPORT]);
        }

        return ret;
}

static int ip6gre_newlink_common(struct net *link_net, struct net_device *dev,
                                 struct nlattr *tb[], struct nlattr *data[],
                                 struct netlink_ext_ack *extack)
{
        struct ip6_tnl *nt;
        struct ip_tunnel_encap ipencap;
        int err;

        nt = netdev_priv(dev);

        if (ip6gre_netlink_encap_parms(data, &ipencap)) {
                int err = ip6_tnl_encap_setup(nt, &ipencap);

                if (err < 0)
                        return err;
        }

        if (dev->type == ARPHRD_ETHER && !tb[IFLA_ADDRESS])
                eth_hw_addr_random(dev);

        nt->dev = dev;
        nt->net = link_net;

        err = register_netdevice(dev);
        if (err)
                goto out;

        if (tb[IFLA_MTU])
                ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU]));

out:
        return err;
}

static int ip6gre_newlink(struct net_device *dev,
                          struct rtnl_newlink_params *params,
                          struct netlink_ext_ack *extack)
{
        struct net *net = params->link_net ? : dev_net(dev);
        struct ip6_tnl *nt = netdev_priv(dev);
        struct nlattr **data = params->data;
        struct nlattr **tb = params->tb;
        struct ip6gre_net *ign;
        int err;

        ip6gre_netlink_parms(data, &nt->parms);
        ign = net_generic(net, ip6gre_net_id);

        if (nt->parms.collect_md) {
                if (rtnl_dereference(ign->collect_md_tun))
                        return -EEXIST;
        } else {
                if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
                        return -EEXIST;
        }

        err = ip6gre_newlink_common(net, dev, tb, data, extack);
        if (!err) {
                ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);
                ip6gre_tunnel_link_md(ign, nt);
                ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
        }
        return err;
}

static struct ip6_tnl *
ip6gre_changelink_common(struct net_device *dev, struct nlattr *tb[],
                         struct nlattr *data[], struct __ip6_tnl_parm *p_p,
                         struct netlink_ext_ack *extack)
{
        struct ip6_tnl *t, *nt = netdev_priv(dev);
        struct net *net = nt->net;
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
        struct ip_tunnel_encap ipencap;

        if (dev == ign->fb_tunnel_dev)
                return ERR_PTR(-EINVAL);

        if (ip6gre_netlink_encap_parms(data, &ipencap)) {
                int err = ip6_tnl_encap_setup(nt, &ipencap);

                if (err < 0)
                        return ERR_PTR(err);
        }

        ip6gre_netlink_parms(data, p_p);

        t = ip6gre_tunnel_locate(net, p_p, 0);

        if (t) {
                if (t->dev != dev)
                        return ERR_PTR(-EEXIST);
        } else {
                t = nt;
        }

        return t;
}

static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],
                             struct nlattr *data[],
                             struct netlink_ext_ack *extack)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
        struct __ip6_tnl_parm p;

        t = ip6gre_changelink_common(dev, tb, data, &p, extack);
        if (IS_ERR(t))
                return PTR_ERR(t);

        ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        ip6gre_tnl_change(t, &p, !tb[IFLA_MTU]);
        ip6gre_tunnel_link_md(ign, t);
        ip6gre_tunnel_link(ign, t);
        return 0;
}

static void ip6gre_dellink(struct net_device *dev, struct list_head *head)
{
        struct net *net = dev_net(dev);
        struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

        if (dev != ign->fb_tunnel_dev)
                unregister_netdevice_queue(dev, head);
}

static size_t ip6gre_get_size(const struct net_device *dev)
{
        return
                /* IFLA_GRE_LINK */
                nla_total_size(4) +
                /* IFLA_GRE_IFLAGS */
                nla_total_size(2) +
                /* IFLA_GRE_OFLAGS */
                nla_total_size(2) +
                /* IFLA_GRE_IKEY */
                nla_total_size(4) +
                /* IFLA_GRE_OKEY */
                nla_total_size(4) +
                /* IFLA_GRE_LOCAL */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_GRE_REMOTE */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_GRE_TTL */
                nla_total_size(1) +
                /* IFLA_GRE_ENCAP_LIMIT */
                nla_total_size(1) +
                /* IFLA_GRE_FLOWINFO */
                nla_total_size(4) +
                /* IFLA_GRE_FLAGS */
                nla_total_size(4) +
                /* IFLA_GRE_ENCAP_TYPE */
                nla_total_size(2) +
                /* IFLA_GRE_ENCAP_FLAGS */
                nla_total_size(2) +
                /* IFLA_GRE_ENCAP_SPORT */
                nla_total_size(2) +
                /* IFLA_GRE_ENCAP_DPORT */
                nla_total_size(2) +
                /* IFLA_GRE_COLLECT_METADATA */
                nla_total_size(0) +
                /* IFLA_GRE_FWMARK */
                nla_total_size(4) +
                /* IFLA_GRE_ERSPAN_INDEX */
                nla_total_size(4) +
                0;
}

static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct __ip6_tnl_parm *p = &t->parms;
        IP_TUNNEL_DECLARE_FLAGS(o_flags);

        ip_tunnel_flags_copy(o_flags, p->o_flags);

        if (p->erspan_ver == 1 || p->erspan_ver == 2) {
                if (!p->collect_md)
                        __set_bit(IP_TUNNEL_KEY_BIT, o_flags);

                if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, p->erspan_ver))
                        goto nla_put_failure;

                if (p->erspan_ver == 1) {
                        if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, p->index))
                                goto nla_put_failure;
                } else {
                        if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, p->dir))
                                goto nla_put_failure;
                        if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, p->hwid))
                                goto nla_put_failure;
                }
        }

        if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
            nla_put_be16(skb, IFLA_GRE_IFLAGS,
                         gre_tnl_flags_to_gre_flags(p->i_flags)) ||
            nla_put_be16(skb, IFLA_GRE_OFLAGS,
                         gre_tnl_flags_to_gre_flags(o_flags)) ||
            nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
            nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||
            nla_put_in6_addr(skb, IFLA_GRE_LOCAL, &p->laddr) ||
            nla_put_in6_addr(skb, IFLA_GRE_REMOTE, &p->raddr) ||
            nla_put_u8(skb, IFLA_GRE_TTL, p->hop_limit) ||
            nla_put_u8(skb, IFLA_GRE_ENCAP_LIMIT, p->encap_limit) ||
            nla_put_be32(skb, IFLA_GRE_FLOWINFO, p->flowinfo) ||
            nla_put_u32(skb, IFLA_GRE_FLAGS, p->flags) ||
            nla_put_u32(skb, IFLA_GRE_FWMARK, p->fwmark))
                goto nla_put_failure;

        if (nla_put_u16(skb, IFLA_GRE_ENCAP_TYPE,
                        t->encap.type) ||
            nla_put_be16(skb, IFLA_GRE_ENCAP_SPORT,
                         t->encap.sport) ||
            nla_put_be16(skb, IFLA_GRE_ENCAP_DPORT,
                         t->encap.dport) ||
            nla_put_u16(skb, IFLA_GRE_ENCAP_FLAGS,
                        t->encap.flags))
                goto nla_put_failure;

        if (p->collect_md) {
                if (nla_put_flag(skb, IFLA_GRE_COLLECT_METADATA))
                        goto nla_put_failure;
        }

        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

static const struct nla_policy ip6gre_policy[IFLA_GRE_MAX + 1] = {
        [IFLA_GRE_LINK]        = { .type = NLA_U32 },
        [IFLA_GRE_IFLAGS]      = { .type = NLA_U16 },
        [IFLA_GRE_OFLAGS]      = { .type = NLA_U16 },
        [IFLA_GRE_IKEY]        = { .type = NLA_U32 },
        [IFLA_GRE_OKEY]        = { .type = NLA_U32 },
        [IFLA_GRE_LOCAL]       = { .len = sizeof_field(struct ipv6hdr, saddr) },
        [IFLA_GRE_REMOTE]      = { .len = sizeof_field(struct ipv6hdr, daddr) },
        [IFLA_GRE_TTL]         = { .type = NLA_U8 },
        [IFLA_GRE_ENCAP_LIMIT] = { .type = NLA_U8 },
        [IFLA_GRE_FLOWINFO]    = { .type = NLA_U32 },
        [IFLA_GRE_FLAGS]       = { .type = NLA_U32 },
        [IFLA_GRE_ENCAP_TYPE]   = { .type = NLA_U16 },
        [IFLA_GRE_ENCAP_FLAGS]  = { .type = NLA_U16 },
        [IFLA_GRE_ENCAP_SPORT]  = { .type = NLA_U16 },
        [IFLA_GRE_ENCAP_DPORT]  = { .type = NLA_U16 },
        [IFLA_GRE_COLLECT_METADATA] = { .type = NLA_FLAG },
        [IFLA_GRE_FWMARK]       = { .type = NLA_U32 },
        [IFLA_GRE_ERSPAN_INDEX] = { .type = NLA_U32 },
        [IFLA_GRE_ERSPAN_VER]   = { .type = NLA_U8 },
        [IFLA_GRE_ERSPAN_DIR]   = { .type = NLA_U8 },
        [IFLA_GRE_ERSPAN_HWID]  = { .type = NLA_U16 },
};

static void ip6erspan_tap_setup(struct net_device *dev)
{
        ether_setup(dev);

        dev->max_mtu = 0;
        dev->netdev_ops = &ip6erspan_netdev_ops;
        dev->needs_free_netdev = true;
        dev->priv_destructor = ip6gre_dev_free;

        dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
        dev->priv_flags &= ~IFF_TX_SKB_SHARING;
        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
        netif_keep_dst(dev);
}

static int ip6erspan_newlink(struct net_device *dev,
                             struct rtnl_newlink_params *params,
                             struct netlink_ext_ack *extack)
{
        struct net *net = params->link_net ? : dev_net(dev);
        struct ip6_tnl *nt = netdev_priv(dev);
        struct nlattr **data = params->data;
        struct nlattr **tb = params->tb;
        struct ip6gre_net *ign;
        int err;

        ip6gre_netlink_parms(data, &nt->parms);
        ip6erspan_set_version(data, &nt->parms);
        ign = net_generic(net, ip6gre_net_id);

        if (nt->parms.collect_md) {
                if (rtnl_dereference(ign->collect_md_tun_erspan))
                        return -EEXIST;
        } else {
                if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
                        return -EEXIST;
        }

        err = ip6gre_newlink_common(net, dev, tb, data, extack);
        if (!err) {
                ip6erspan_tnl_link_config(nt, !tb[IFLA_MTU]);
                ip6erspan_tunnel_link_md(ign, nt);
                ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
        }
        return err;
}

static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu)
{
        ip6gre_tnl_link_config_common(t);
        ip6gre_tnl_link_config_route(t, set_mtu, ip6erspan_calc_hlen(t));
}

static int ip6erspan_tnl_change(struct ip6_tnl *t,
                                const struct __ip6_tnl_parm *p, int set_mtu)
{
        ip6gre_tnl_copy_tnl_parm(t, p);
        ip6erspan_tnl_link_config(t, set_mtu);
        return 0;
}

static int ip6erspan_changelink(struct net_device *dev, struct nlattr *tb[],
                                struct nlattr *data[],
                                struct netlink_ext_ack *extack)
{
        struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);
        struct __ip6_tnl_parm p;
        struct ip6_tnl *t;

        t = ip6gre_changelink_common(dev, tb, data, &p, extack);
        if (IS_ERR(t))
                return PTR_ERR(t);

        ip6erspan_set_version(data, &p);
        ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        ip6erspan_tnl_change(t, &p, !tb[IFLA_MTU]);
        ip6erspan_tunnel_link_md(ign, t);
        ip6gre_tunnel_link(ign, t);
        return 0;
}

static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
        .kind           = "ip6gre",
        .maxtype        = IFLA_GRE_MAX,
        .policy         = ip6gre_policy,
        .priv_size      = sizeof(struct ip6_tnl),
        .setup          = ip6gre_tunnel_setup,
        .validate       = ip6gre_tunnel_validate,
        .newlink        = ip6gre_newlink,
        .changelink     = ip6gre_changelink,
        .dellink        = ip6gre_dellink,
        .get_size       = ip6gre_get_size,
        .fill_info      = ip6gre_fill_info,
        .get_link_net   = ip6_tnl_get_link_net,
};

static struct rtnl_link_ops ip6gre_tap_ops __read_mostly = {
        .kind           = "ip6gretap",
        .maxtype        = IFLA_GRE_MAX,
        .policy         = ip6gre_policy,
        .priv_size      = sizeof(struct ip6_tnl),
        .setup          = ip6gre_tap_setup,
        .validate       = ip6gre_tap_validate,
        .newlink        = ip6gre_newlink,
        .changelink     = ip6gre_changelink,
        .get_size       = ip6gre_get_size,
        .fill_info      = ip6gre_fill_info,
        .get_link_net   = ip6_tnl_get_link_net,
};

static struct rtnl_link_ops ip6erspan_tap_ops __read_mostly = {
        .kind           = "ip6erspan",
        .maxtype        = IFLA_GRE_MAX,
        .policy         = ip6gre_policy,
        .priv_size      = sizeof(struct ip6_tnl),
        .setup          = ip6erspan_tap_setup,
        .validate       = ip6erspan_tap_validate,
        .newlink        = ip6erspan_newlink,
        .changelink     = ip6erspan_changelink,
        .get_size       = ip6gre_get_size,
        .fill_info      = ip6gre_fill_info,
        .get_link_net   = ip6_tnl_get_link_net,
};

/*
 *      And now the modules code and kernel interface.
 */

static int __init ip6gre_init(void)
{
        int err;

        pr_info("GRE over IPv6 tunneling driver\n");

        err = register_pernet_device(&ip6gre_net_ops);
        if (err < 0)
                return err;

        err = inet6_add_protocol(&ip6gre_protocol, IPPROTO_GRE);
        if (err < 0) {
                pr_info("%s: can't add protocol\n", __func__);
                goto add_proto_failed;
        }

        err = rtnl_link_register(&ip6gre_link_ops);
        if (err < 0)
                goto rtnl_link_failed;

        err = rtnl_link_register(&ip6gre_tap_ops);
        if (err < 0)
                goto tap_ops_failed;

        err = rtnl_link_register(&ip6erspan_tap_ops);
        if (err < 0)
                goto erspan_link_failed;

out:
        return err;

erspan_link_failed:
        rtnl_link_unregister(&ip6gre_tap_ops);
tap_ops_failed:
        rtnl_link_unregister(&ip6gre_link_ops);
rtnl_link_failed:
        inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
add_proto_failed:
        unregister_pernet_device(&ip6gre_net_ops);
        goto out;
}

static void __exit ip6gre_fini(void)
{
        rtnl_link_unregister(&ip6gre_tap_ops);
        rtnl_link_unregister(&ip6gre_link_ops);
        rtnl_link_unregister(&ip6erspan_tap_ops);
        inet6_del_protocol(&ip6gre_protocol, IPPROTO_GRE);
        unregister_pernet_device(&ip6gre_net_ops);
}

module_init(ip6gre_init);
module_exit(ip6gre_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("D. Kozlov <xeb@mail.ru>");
MODULE_DESCRIPTION("GRE over IPv6 tunneling device");
MODULE_ALIAS_RTNL_LINK("ip6gre");
MODULE_ALIAS_RTNL_LINK("ip6gretap");
MODULE_ALIAS_RTNL_LINK("ip6erspan");
MODULE_ALIAS_NETDEV("ip6gre0");