// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      IPv6 tunneling device
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
 *      Yasuyuki Kozakai        <kozakai@linux-ipv6.org>
 *
 *      Based on:
 *      linux/net/ipv6/sit.c and linux/net/ipv4/ipip.c
 *
 *      RFC 2473
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/sockios.h>
#include <linux/icmp.h>
#include <linux/if.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/icmpv6.h>
#include <linux/init.h>
#include <linux/route.h>
#include <linux/rtnetlink.h>
#include <linux/netfilter_ipv6.h>
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/etherdevice.h>

#include <linux/uaccess.h>
#include <linux/atomic.h>

#include <net/icmp.h>
#include <net/ip.h>
#include <net/ip_tunnels.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/ip6_tunnel.h>
#include <net/xfrm.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/netdev_lock.h>
#include <net/dst_metadata.h>
#include <net/inet_dscp.h>

MODULE_AUTHOR("Ville Nuorvala");
MODULE_DESCRIPTION("IPv6 tunneling device");
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("ip6tnl");
MODULE_ALIAS_NETDEV("ip6tnl0");

#define IP6_TUNNEL_HASH_SIZE_SHIFT  5
#define IP6_TUNNEL_HASH_SIZE (1 << IP6_TUNNEL_HASH_SIZE_SHIFT)

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");

static u32 HASH(const struct in6_addr *addr1, const struct in6_addr *addr2)
{
        u32 hash = ipv6_addr_hash(addr1) ^ ipv6_addr_hash(addr2);

        return hash_32(hash, IP6_TUNNEL_HASH_SIZE_SHIFT);
}

static int ip6_tnl_dev_init(struct net_device *dev);
static void ip6_tnl_dev_setup(struct net_device *dev);
static struct rtnl_link_ops ip6_link_ops __read_mostly;

static unsigned int ip6_tnl_net_id __read_mostly;
struct ip6_tnl_net {
        /* the IPv6 tunnel fallback device */
        struct net_device *fb_tnl_dev;
        /* lists for storing tunnels in use */
        struct ip6_tnl __rcu *tnls_r_l[IP6_TUNNEL_HASH_SIZE];
        struct ip6_tnl __rcu *tnls_wc[1];
        struct ip6_tnl __rcu **tnls[2];
        struct ip6_tnl __rcu *collect_md_tun;
};

static inline int ip6_tnl_mpls_supported(void)
{
        return IS_ENABLED(CONFIG_MPLS);
}

#define for_each_ip6_tunnel_rcu(start) \
        for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))

/**
 * ip6_tnl_lookup - fetch tunnel matching the end-point addresses
 *   @net: network namespace
 *   @link: ifindex of underlying interface
 *   @remote: the address of the tunnel exit-point
 *   @local: the address of the tunnel entry-point
 *
 * Return:
 *   tunnel matching given end-points if found,
 *   else fallback tunnel if its device is up,
 *   else %NULL
 **/

static struct ip6_tnl *
ip6_tnl_lookup(struct net *net, int link,
               const struct in6_addr *remote, const struct in6_addr *local)
{
        unsigned int hash = HASH(remote, local);
        struct ip6_tnl *t, *cand = NULL;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
        struct in6_addr any;

        for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
                if (!ipv6_addr_equal(local, &t->parms.laddr) ||
                    !ipv6_addr_equal(remote, &t->parms.raddr) ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (link == t->parms.link)
                        return t;
                else
                        cand = t;
        }

        memset(&any, 0, sizeof(any));
        hash = HASH(&any, local);
        for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
                if (!ipv6_addr_equal(local, &t->parms.laddr) ||
                    !ipv6_addr_any(&t->parms.raddr) ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (link == t->parms.link)
                        return t;
                else if (!cand)
                        cand = t;
        }

        hash = HASH(remote, &any);
        for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
                if (!ipv6_addr_equal(remote, &t->parms.raddr) ||
                    !ipv6_addr_any(&t->parms.laddr) ||
                    !(t->dev->flags & IFF_UP))
                        continue;

                if (link == t->parms.link)
                        return t;
                else if (!cand)
                        cand = t;
        }

        if (cand)
                return cand;

        t = rcu_dereference(ip6n->collect_md_tun);
        if (t && t->dev->flags & IFF_UP)
                return t;

        t = rcu_dereference(ip6n->tnls_wc[0]);
        if (t && (t->dev->flags & IFF_UP))
                return t;

        return NULL;
}

/**
 * ip6_tnl_bucket - get head of list matching given tunnel parameters
 *   @ip6n: the private data for ip6_vti in the netns
 *   @p: parameters containing tunnel end-points
 *
 * Description:
 *   ip6_tnl_bucket() returns the head of the list matching the
 *   &struct in6_addr entries laddr and raddr in @p.
 *
 * Return: head of IPv6 tunnel list
 **/

static struct ip6_tnl __rcu **
ip6_tnl_bucket(struct ip6_tnl_net *ip6n, const struct __ip6_tnl_parm *p)
{
        const struct in6_addr *remote = &p->raddr;
        const struct in6_addr *local = &p->laddr;
        unsigned int h = 0;
        int prio = 0;

        if (!ipv6_addr_any(remote) || !ipv6_addr_any(local)) {
                prio = 1;
                h = HASH(remote, local);
        }
        return &ip6n->tnls[prio][h];
}

/**
 * ip6_tnl_link - add tunnel to hash table
 *   @ip6n: the private data for ip6_vti in the netns
 *   @t: tunnel to be added
 **/

static void
ip6_tnl_link(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp = ip6_tnl_bucket(ip6n, &t->parms);

        if (t->parms.collect_md)
                rcu_assign_pointer(ip6n->collect_md_tun, t);
        rcu_assign_pointer(t->next , rtnl_dereference(*tp));
        rcu_assign_pointer(*tp, t);
}

/**
 * ip6_tnl_unlink - remove tunnel from hash table
 *   @ip6n: the private data for ip6_vti in the netns
 *   @t: tunnel to be removed
 **/

static void
ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp;
        struct ip6_tnl *iter;

        if (t->parms.collect_md)
                rcu_assign_pointer(ip6n->collect_md_tun, NULL);

        for (tp = ip6_tnl_bucket(ip6n, &t->parms);
             (iter = rtnl_dereference(*tp)) != NULL;
             tp = &iter->next) {
                if (t == iter) {
                        rcu_assign_pointer(*tp, t->next);
                        break;
                }
        }
}

static void ip6_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 int ip6_tnl_create2(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ip6_tnl_net *ip6n = net_generic(t->net, ip6_tnl_net_id);
        int err;

        dev->rtnl_link_ops = &ip6_link_ops;
        err = register_netdevice(dev);
        if (err < 0)
                goto out;

        strcpy(t->parms.name, dev->name);

        ip6_tnl_link(ip6n, t);
        return 0;

out:
        return err;
}

/**
 * ip6_tnl_create - create a new tunnel
 *   @net: network namespace
 *   @p: tunnel parameters
 *
 * Description:
 *   Create tunnel matching given parameters.
 *
 * Return:
 *   created tunnel or error pointer
 **/

static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
{
        struct net_device *dev;
        struct ip6_tnl *t;
        char name[IFNAMSIZ];
        int err = -E2BIG;

        if (p->name[0]) {
                if (!dev_valid_name(p->name))
                        goto failed;
                strscpy(name, p->name, IFNAMSIZ);
        } else {
                sprintf(name, "ip6tnl%%d");
        }
        err = -ENOMEM;
        dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
                           ip6_tnl_dev_setup);
        if (!dev)
                goto failed;

        dev_net_set(dev, net);

        t = netdev_priv(dev);
        t->parms = *p;
        t->net = dev_net(dev);
        err = ip6_tnl_create2(dev);
        if (err < 0)
                goto failed_free;

        return t;

failed_free:
        free_netdev(dev);
failed:
        return ERR_PTR(err);
}

/**
 * ip6_tnl_locate - find or create tunnel matching given parameters
 *   @net: network namespace
 *   @p: tunnel parameters
 *   @create: != 0 if allowed to create new tunnel if no match found
 *
 * Description:
 *   ip6_tnl_locate() first tries to locate an existing tunnel
 *   based on @parms. If this is unsuccessful, but @create is set a new
 *   tunnel device is created and registered for use.
 *
 * Return:
 *   matching tunnel or error pointer
 **/

static struct ip6_tnl *ip6_tnl_locate(struct net *net,
                struct __ip6_tnl_parm *p, int create)
{
        const struct in6_addr *remote = &p->raddr;
        const struct in6_addr *local = &p->laddr;
        struct ip6_tnl __rcu **tp;
        struct ip6_tnl *t;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

        for (tp = ip6_tnl_bucket(ip6n, p);
             (t = rtnl_dereference(*tp)) != NULL;
             tp = &t->next) {
                if (ipv6_addr_equal(local, &t->parms.laddr) &&
                    ipv6_addr_equal(remote, &t->parms.raddr) &&
                    p->link == t->parms.link) {
                        if (create)
                                return ERR_PTR(-EEXIST);

                        return t;
                }
        }
        if (!create)
                return ERR_PTR(-ENODEV);
        return ip6_tnl_create(net, p);
}

/**
 * ip6_tnl_dev_uninit - tunnel device uninitializer
 *   @dev: the device to be destroyed
 *
 * Description:
 *   ip6_tnl_dev_uninit() removes tunnel from its list
 **/

static void
ip6_tnl_dev_uninit(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = t->net;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

        if (dev == ip6n->fb_tnl_dev)
                RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
        else
                ip6_tnl_unlink(ip6n, t);
        dst_cache_reset(&t->dst_cache);
        netdev_put(dev, &t->dev_tracker);
}

/**
 * ip6_tnl_parse_tlv_enc_lim - handle encapsulation limit option
 *   @skb: received socket buffer
 *   @raw: the ICMPv6 error message data
 *
 * Return:
 *   0 if none was found,
 *   else index to encapsulation limit
 **/

__u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
{
        const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)raw;
        unsigned int nhoff = raw - skb->data;
        unsigned int off = nhoff + sizeof(*ipv6h);
        u8 nexthdr = ipv6h->nexthdr;

        while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) {
                struct ipv6_opt_hdr *hdr;
                u16 optlen;

                if (!pskb_may_pull(skb, off + sizeof(*hdr)))
                        break;

                hdr = (struct ipv6_opt_hdr *)(skb->data + off);
                if (nexthdr == NEXTHDR_FRAGMENT) {
                        optlen = 8;
                } else if (nexthdr == NEXTHDR_AUTH) {
                        optlen = ipv6_authlen(hdr);
                } else {
                        optlen = ipv6_optlen(hdr);
                }

                if (!pskb_may_pull(skb, off + optlen))
                        break;

                hdr = (struct ipv6_opt_hdr *)(skb->data + off);
                if (nexthdr == NEXTHDR_FRAGMENT) {
                        struct frag_hdr *frag_hdr = (struct frag_hdr *)hdr;

                        if (frag_hdr->frag_off)
                                break;
                }
                if (nexthdr == NEXTHDR_DEST) {
                        u16 i = 2;

                        while (1) {
                                struct ipv6_tlv_tnl_enc_lim *tel;

                                /* No more room for encapsulation limit */
                                if (i + sizeof(*tel) > optlen)
                                        break;

                                tel = (struct ipv6_tlv_tnl_enc_lim *)(skb->data + off + i);
                                /* return index of option if found and valid */
                                if (tel->type == IPV6_TLV_TNL_ENCAP_LIMIT &&
                                    tel->length == 1)
                                        return i + off - nhoff;
                                /* else jump to next option */
                                if (tel->type)
                                        i += tel->length + 2;
                                else
                                        i++;
                        }
                }
                nexthdr = hdr->nexthdr;
                off += optlen;
        }
        return 0;
}
EXPORT_SYMBOL(ip6_tnl_parse_tlv_enc_lim);

/* ip6_tnl_err() should handle errors in the tunnel according to the
 * specifications in RFC 2473.
 */
static int
ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
            u8 *type, u8 *code, int *msg, __u32 *info, int offset)
{
        const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)skb->data;
        struct net *net = dev_net(skb->dev);
        u8 rel_type = ICMPV6_DEST_UNREACH;
        u8 rel_code = ICMPV6_ADDR_UNREACH;
        __u32 rel_info = 0;
        struct ip6_tnl *t;
        int err = -ENOENT;
        int rel_msg = 0;
        u8 tproto;
        __u16 len;

        /* If the packet doesn't contain the original IPv6 header we are
           in trouble since we might need the source address for further
           processing of the error. */

        rcu_read_lock();
        t = ip6_tnl_lookup(dev_net(skb->dev), skb->dev->ifindex, &ipv6h->daddr, &ipv6h->saddr);
        if (!t)
                goto out;

        tproto = READ_ONCE(t->parms.proto);
        if (tproto != ipproto && tproto != 0)
                goto out;

        err = 0;

        switch (*type) {
        case ICMPV6_DEST_UNREACH:
                net_dbg_ratelimited("%s: Path to destination invalid or inactive!\n",
                                    t->parms.name);
                rel_msg = 1;
                break;
        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);
                        rel_msg = 1;
                }
                break;
        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 == *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);
                                rel_msg = 1;
                        }
                } else {
                        net_dbg_ratelimited("%s: Recipient unable to parse tunneled packet!\n",
                                            t->parms.name);
                }
                break;
        }
        case ICMPV6_PKT_TOOBIG: {
                __u32 mtu;

                ip6_update_pmtu(skb, net, htonl(*info), 0, 0,
                                sock_net_uid(net, NULL));
                mtu = *info - offset;
                if (mtu < IPV6_MIN_MTU)
                        mtu = IPV6_MIN_MTU;
                len = sizeof(*ipv6h) + ntohs(ipv6h->payload_len);
                if (len > mtu) {
                        rel_type = ICMPV6_PKT_TOOBIG;
                        rel_code = 0;
                        rel_info = mtu;
                        rel_msg = 1;
                }
                break;
        }
        case NDISC_REDIRECT:
                ip6_redirect(skb, net, skb->dev->ifindex, 0,
                             sock_net_uid(net, NULL));
                break;
        }

        *type = rel_type;
        *code = rel_code;
        *info = rel_info;
        *msg = rel_msg;

out:
        rcu_read_unlock();
        return err;
}

static int
ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
           u8 type, u8 code, int offset, __be32 info)
{
        __u32 rel_info = ntohl(info);
        const struct iphdr *eiph;
        struct sk_buff *skb2;
        int err, rel_msg = 0;
        u8 rel_type = type;
        u8 rel_code = code;
        struct rtable *rt;
        struct flowi4 fl4;

        err = ip6_tnl_err(skb, IPPROTO_IPIP, opt, &rel_type, &rel_code,
                          &rel_msg, &rel_info, offset);
        if (err < 0)
                return err;

        if (rel_msg == 0)
                return 0;

        switch (rel_type) {
        case ICMPV6_DEST_UNREACH:
                if (rel_code != ICMPV6_ADDR_UNREACH)
                        return 0;
                rel_type = ICMP_DEST_UNREACH;
                rel_code = ICMP_HOST_UNREACH;
                break;
        case ICMPV6_PKT_TOOBIG:
                if (rel_code != 0)
                        return 0;
                rel_type = ICMP_DEST_UNREACH;
                rel_code = ICMP_FRAG_NEEDED;
                break;
        default:
                return 0;
        }

        if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
                return 0;

        skb2 = skb_clone(skb, GFP_ATOMIC);
        if (!skb2)
                return 0;

        /* Remove debris left by IPv6 stack. */
        memset(IPCB(skb2), 0, sizeof(*IPCB(skb2)));

        skb_dst_drop(skb2);

        skb_pull(skb2, offset);
        skb_reset_network_header(skb2);
        eiph = ip_hdr(skb2);
        if (eiph->version != 4 || eiph->ihl < 5)
                goto out;

        /* Try to guess incoming interface */
        rt = ip_route_output_ports(dev_net(skb->dev), &fl4, NULL, eiph->saddr,
                                   0, 0, 0, IPPROTO_IPIP,
                                   eiph->tos & INET_DSCP_MASK, 0);
        if (IS_ERR(rt))
                goto out;

        skb2->dev = rt->dst.dev;
        ip_rt_put(rt);

        /* route "incoming" packet */
        if (rt->rt_flags & RTCF_LOCAL) {
                rt = ip_route_output_ports(dev_net(skb->dev), &fl4, NULL,
                                           eiph->daddr, eiph->saddr, 0, 0,
                                           IPPROTO_IPIP,
                                           eiph->tos & INET_DSCP_MASK, 0);
                if (IS_ERR(rt) || rt->dst.dev->type != ARPHRD_TUNNEL6) {
                        if (!IS_ERR(rt))
                                ip_rt_put(rt);
                        goto out;
                }
                skb_dst_set(skb2, &rt->dst);
        } else {
                if (ip_route_input(skb2, eiph->daddr, eiph->saddr,
                                   ip4h_dscp(eiph), skb2->dev) ||
                    skb_dst_dev(skb2)->type != ARPHRD_TUNNEL6)
                        goto out;
        }

        /* change mtu on this route */
        if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) {
                if (rel_info > dst6_mtu(skb_dst(skb2)))
                        goto out;

                skb_dst_update_pmtu_no_confirm(skb2, rel_info);
        }

        icmp_send(skb2, rel_type, rel_code, htonl(rel_info));

out:
        kfree_skb(skb2);
        return 0;
}

static int
ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
           u8 type, u8 code, int offset, __be32 info)
{
        __u32 rel_info = ntohl(info);
        int err, rel_msg = 0;
        u8 rel_type = type;
        u8 rel_code = code;

        err = ip6_tnl_err(skb, IPPROTO_IPV6, opt, &rel_type, &rel_code,
                          &rel_msg, &rel_info, offset);
        if (err < 0)
                return err;

        if (rel_msg && pskb_may_pull(skb, offset + sizeof(struct ipv6hdr))) {
                struct rt6_info *rt;
                struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

                if (!skb2)
                        return 0;

                skb_dst_drop(skb2);
                skb_pull(skb2, offset);
                skb_reset_network_header(skb2);

                /* Try to guess incoming interface */
                rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr,
                                NULL, 0, skb2, 0);

                if (rt && rt->dst.dev)
                        skb2->dev = rt->dst.dev;

                icmpv6_send(skb2, rel_type, rel_code, rel_info);

                ip6_rt_put(rt);

                kfree_skb(skb2);
        }

        return 0;
}

static int
mplsip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
            u8 type, u8 code, int offset, __be32 info)
{
        __u32 rel_info = ntohl(info);
        int err, rel_msg = 0;
        u8 rel_type = type;
        u8 rel_code = code;

        err = ip6_tnl_err(skb, IPPROTO_MPLS, opt, &rel_type, &rel_code,
                          &rel_msg, &rel_info, offset);
        return err;
}

static int ip4ip6_dscp_ecn_decapsulate(const struct ip6_tnl *t,
                                       const struct ipv6hdr *ipv6h,
                                       struct sk_buff *skb)
{
        __u8 dsfield = ipv6_get_dsfield(ipv6h) & ~INET_ECN_MASK;

        if (t->parms.flags & IP6_TNL_F_RCV_DSCP_COPY)
                ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, dsfield);

        return IP6_ECN_decapsulate(ipv6h, skb);
}

static int ip6ip6_dscp_ecn_decapsulate(const struct ip6_tnl *t,
                                       const struct ipv6hdr *ipv6h,
                                       struct sk_buff *skb)
{
        if (t->parms.flags & IP6_TNL_F_RCV_DSCP_COPY)
                ipv6_copy_dscp(ipv6_get_dsfield(ipv6h), ipv6_hdr(skb));

        return IP6_ECN_decapsulate(ipv6h, skb);
}

static inline int mplsip6_dscp_ecn_decapsulate(const struct ip6_tnl *t,
                                               const struct ipv6hdr *ipv6h,
                                               struct sk_buff *skb)
{
        /* ECN is not supported in AF_MPLS */
        return 0;
}

__u32 ip6_tnl_get_cap(struct ip6_tnl *t,
                             const struct in6_addr *laddr,
                             const struct in6_addr *raddr)
{
        struct __ip6_tnl_parm *p = &t->parms;
        int ltype = ipv6_addr_type(laddr);
        int rtype = ipv6_addr_type(raddr);
        __u32 flags = 0;

        if (ltype == IPV6_ADDR_ANY || rtype == IPV6_ADDR_ANY) {
                flags = IP6_TNL_F_CAP_PER_PACKET;
        } else if (ltype & (IPV6_ADDR_UNICAST|IPV6_ADDR_MULTICAST) &&
                   rtype & (IPV6_ADDR_UNICAST|IPV6_ADDR_MULTICAST) &&
                   !((ltype|rtype) & IPV6_ADDR_LOOPBACK) &&
                   (!((ltype|rtype) & IPV6_ADDR_LINKLOCAL) || p->link)) {
                if (ltype&IPV6_ADDR_UNICAST)
                        flags |= IP6_TNL_F_CAP_XMIT;
                if (rtype&IPV6_ADDR_UNICAST)
                        flags |= IP6_TNL_F_CAP_RCV;
        }
        return flags;
}
EXPORT_SYMBOL(ip6_tnl_get_cap);

/* called with rcu_read_lock() */
int ip6_tnl_rcv_ctl(struct ip6_tnl *t,
                                  const struct in6_addr *laddr,
                                  const struct in6_addr *raddr)
{
        struct __ip6_tnl_parm *p = &t->parms;
        int ret = 0;
        struct net *net = t->net;

        if ((p->flags & IP6_TNL_F_CAP_RCV) ||
            ((p->flags & IP6_TNL_F_CAP_PER_PACKET) &&
             (ip6_tnl_get_cap(t, laddr, raddr) & IP6_TNL_F_CAP_RCV))) {
                struct net_device *ldev = NULL;

                if (p->link)
                        ldev = dev_get_by_index_rcu(net, p->link);

                if ((ipv6_addr_is_multicast(laddr) ||
                     likely(ipv6_chk_addr_and_flags(net, laddr, ldev, false,
                                                    0, IFA_F_TENTATIVE))) &&
                    ((p->flags & IP6_TNL_F_ALLOW_LOCAL_REMOTE) ||
                     likely(!ipv6_chk_addr_and_flags(net, raddr, ldev, true,
                                                     0, IFA_F_TENTATIVE))))
                        ret = 1;
        }
        return ret;
}
EXPORT_SYMBOL_GPL(ip6_tnl_rcv_ctl);

static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb,
                         const struct tnl_ptk_info *tpi,
                         struct metadata_dst *tun_dst,
                         int (*dscp_ecn_decapsulate)(const struct ip6_tnl *t,
                                                const struct ipv6hdr *ipv6h,
                                                struct sk_buff *skb),
                         bool log_ecn_err)
{
        const struct ipv6hdr *ipv6h;
        int nh, err;

        if (test_bit(IP_TUNNEL_CSUM_BIT, tunnel->parms.i_flags) !=
            test_bit(IP_TUNNEL_CSUM_BIT, tpi->flags)) {
                DEV_STATS_INC(tunnel->dev, rx_crc_errors);
                DEV_STATS_INC(tunnel->dev, rx_errors);
                goto drop;
        }

        if (test_bit(IP_TUNNEL_SEQ_BIT, tunnel->parms.i_flags)) {
                if (!test_bit(IP_TUNNEL_SEQ_BIT, tpi->flags) ||
                    (tunnel->i_seqno &&
                     (s32)(ntohl(tpi->seq) - tunnel->i_seqno) < 0)) {
                        DEV_STATS_INC(tunnel->dev, rx_fifo_errors);
                        DEV_STATS_INC(tunnel->dev, rx_errors);
                        goto drop;
                }
                tunnel->i_seqno = ntohl(tpi->seq) + 1;
        }

        skb->protocol = tpi->proto;

        /* Warning: All skb pointers will be invalidated! */
        if (tunnel->dev->type == ARPHRD_ETHER) {
                if (!pskb_may_pull(skb, ETH_HLEN)) {
                        DEV_STATS_INC(tunnel->dev, rx_length_errors);
                        DEV_STATS_INC(tunnel->dev, rx_errors);
                        goto drop;
                }

                skb->protocol = eth_type_trans(skb, tunnel->dev);
                skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
        } else {
                skb->dev = tunnel->dev;
                skb_reset_mac_header(skb);
        }

        /* Save offset of outer header relative to skb->head,
         * because we are going to reset the network header to the inner header
         * and might change skb->head.
         */
        nh = skb_network_header(skb) - skb->head;

        skb_reset_network_header(skb);

        if (skb_vlan_inet_prepare(skb, true)) {
                DEV_STATS_INC(tunnel->dev, rx_length_errors);
                DEV_STATS_INC(tunnel->dev, rx_errors);
                goto drop;
        }

        /* Get the outer header. */
        ipv6h = (struct ipv6hdr *)(skb->head + nh);

        memset(skb->cb, 0, sizeof(struct inet6_skb_parm));

        __skb_tunnel_rx(skb, tunnel->dev, tunnel->net);

        err = dscp_ecn_decapsulate(tunnel, ipv6h, skb);
        if (unlikely(err)) {
                if (log_ecn_err)
                        net_info_ratelimited("non-ECT from %pI6 with DS=%#x\n",
                                             &ipv6h->saddr,
                                             ipv6_get_dsfield(ipv6h));
                if (err > 1) {
                        DEV_STATS_INC(tunnel->dev, rx_frame_errors);
                        DEV_STATS_INC(tunnel->dev, rx_errors);
                        goto drop;
                }
        }

        dev_sw_netstats_rx_add(tunnel->dev, skb->len);

        skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(tunnel->dev)));

        if (tun_dst)
                skb_dst_set(skb, (struct dst_entry *)tun_dst);

        gro_cells_receive(&tunnel->gro_cells, skb);
        return 0;

drop:
        if (tun_dst)
                dst_release((struct dst_entry *)tun_dst);
        kfree_skb(skb);
        return 0;
}

int ip6_tnl_rcv(struct ip6_tnl *t, struct sk_buff *skb,
                const struct tnl_ptk_info *tpi,
                struct metadata_dst *tun_dst,
                bool log_ecn_err)
{
        int (*dscp_ecn_decapsulate)(const struct ip6_tnl *t,
                                    const struct ipv6hdr *ipv6h,
                                    struct sk_buff *skb);

        dscp_ecn_decapsulate = ip6ip6_dscp_ecn_decapsulate;
        if (tpi->proto == htons(ETH_P_IP))
                dscp_ecn_decapsulate = ip4ip6_dscp_ecn_decapsulate;

        return __ip6_tnl_rcv(t, skb, tpi, tun_dst, dscp_ecn_decapsulate,
                             log_ecn_err);
}
EXPORT_SYMBOL(ip6_tnl_rcv);

static const struct tnl_ptk_info tpi_v6 = {
        /* no tunnel info required for ipxip6. */
        .proto = htons(ETH_P_IPV6),
};

static const struct tnl_ptk_info tpi_v4 = {
        /* no tunnel info required for ipxip6. */
        .proto = htons(ETH_P_IP),
};

static const struct tnl_ptk_info tpi_mpls = {
        /* no tunnel info required for mplsip6. */
        .proto = htons(ETH_P_MPLS_UC),
};

static int ipxip6_rcv(struct sk_buff *skb, u8 ipproto,
                      const struct tnl_ptk_info *tpi,
                      int (*dscp_ecn_decapsulate)(const struct ip6_tnl *t,
                                                  const struct ipv6hdr *ipv6h,
                                                  struct sk_buff *skb))
{
        struct ip6_tnl *t;
        const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
        struct metadata_dst *tun_dst = NULL;
        int ret = -1;

        rcu_read_lock();
        t = ip6_tnl_lookup(dev_net(skb->dev), skb->dev->ifindex, &ipv6h->saddr, &ipv6h->daddr);

        if (t) {
                u8 tproto = READ_ONCE(t->parms.proto);

                if (tproto != ipproto && tproto != 0)
                        goto drop;
                if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
                        goto drop;
                ipv6h = ipv6_hdr(skb);
                if (!ip6_tnl_rcv_ctl(t, &ipv6h->daddr, &ipv6h->saddr))
                        goto drop;
                if (iptunnel_pull_header(skb, 0, tpi->proto, false))
                        goto drop;
                if (t->parms.collect_md) {
                        IP_TUNNEL_DECLARE_FLAGS(flags) = { };

                        tun_dst = ipv6_tun_rx_dst(skb, flags, 0, 0);
                        if (!tun_dst)
                                goto drop;
                }
                ret = __ip6_tnl_rcv(t, skb, tpi, tun_dst, dscp_ecn_decapsulate,
                                    log_ecn_error);
        }

        rcu_read_unlock();

        return ret;

drop:
        rcu_read_unlock();
        kfree_skb(skb);
        return 0;
}

static int ip4ip6_rcv(struct sk_buff *skb)
{
        return ipxip6_rcv(skb, IPPROTO_IPIP, &tpi_v4,
                          ip4ip6_dscp_ecn_decapsulate);
}

static int ip6ip6_rcv(struct sk_buff *skb)
{
        return ipxip6_rcv(skb, IPPROTO_IPV6, &tpi_v6,
                          ip6ip6_dscp_ecn_decapsulate);
}

static int mplsip6_rcv(struct sk_buff *skb)
{
        return ipxip6_rcv(skb, IPPROTO_MPLS, &tpi_mpls,
                          mplsip6_dscp_ecn_decapsulate);
}

struct ipv6_tel_txoption {
        struct ipv6_txoptions ops;
        __u8 dst_opt[8];
};

static void init_tel_txopt(struct ipv6_tel_txoption *opt, __u8 encap_limit)
{
        memset(opt, 0, sizeof(struct ipv6_tel_txoption));

        opt->dst_opt[2] = IPV6_TLV_TNL_ENCAP_LIMIT;
        opt->dst_opt[3] = 1;
        opt->dst_opt[4] = encap_limit;
        opt->dst_opt[5] = IPV6_TLV_PADN;
        opt->dst_opt[6] = 1;

        opt->ops.dst1opt = (struct ipv6_opt_hdr *) opt->dst_opt;
        opt->ops.opt_nflen = 8;
}

/**
 * ip6_tnl_addr_conflict - compare packet addresses to tunnel's own
 *   @t: the outgoing tunnel device
 *   @hdr: IPv6 header from the incoming packet
 *
 * Description:
 *   Avoid trivial tunneling loop by checking that tunnel exit-point
 *   doesn't match source of incoming packet.
 *
 * Return:
 *   1 if conflict,
 *   0 else
 **/

static inline bool
ip6_tnl_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)
{
        return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
}

int ip6_tnl_xmit_ctl(struct ip6_tnl *t,
                     const struct in6_addr *laddr,
                     const struct in6_addr *raddr)
{
        struct __ip6_tnl_parm *p = &t->parms;
        int ret = 0;
        struct net *net = t->net;

        if (t->parms.collect_md)
                return 1;

        if ((p->flags & IP6_TNL_F_CAP_XMIT) ||
            ((p->flags & IP6_TNL_F_CAP_PER_PACKET) &&
             (ip6_tnl_get_cap(t, laddr, raddr) & IP6_TNL_F_CAP_XMIT))) {
                struct net_device *ldev = NULL;

                rcu_read_lock();
                if (p->link)
                        ldev = dev_get_by_index_rcu(net, p->link);

                if (unlikely(!ipv6_chk_addr_and_flags(net, laddr, ldev, false,
                                                      0, IFA_F_TENTATIVE)))
                        pr_warn_ratelimited("%s xmit: Local address not yet configured!\n",
                                            p->name);
                else if (!(p->flags & IP6_TNL_F_ALLOW_LOCAL_REMOTE) &&
                         !ipv6_addr_is_multicast(raddr) &&
                         unlikely(ipv6_chk_addr_and_flags(net, raddr, ldev,
                                                          true, 0, IFA_F_TENTATIVE)))
                        pr_warn_ratelimited("%s xmit: Routing loop! Remote address found on this node!\n",
                                            p->name);
                else
                        ret = 1;
                rcu_read_unlock();
        }
        return ret;
}
EXPORT_SYMBOL_GPL(ip6_tnl_xmit_ctl);

/**
 * ip6_tnl_xmit - encapsulate packet and send
 *   @skb: the outgoing socket buffer
 *   @dev: the outgoing tunnel device
 *   @dsfield: dscp code for outer header
 *   @fl6: flow of tunneled packet
 *   @encap_limit: encapsulation limit
 *   @pmtu: Path MTU is stored if packet is too big
 *   @proto: next header value
 *
 * Description:
 *   Build new header and do some sanity checks on the packet before sending
 *   it.
 *
 * Return:
 *   0 on success
 *   -1 fail
 *   %-EMSGSIZE message too big. return mtu in this case.
 **/

int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
                 struct flowi6 *fl6, int encap_limit, __u32 *pmtu,
                 __u8 proto)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = t->net;
        struct ipv6hdr *ipv6h;
        struct ipv6_tel_txoption opt;
        struct dst_entry *dst = NULL, *ndst = NULL;
        struct net_device *tdev;
        int mtu;
        unsigned int eth_hlen = t->dev->type == ARPHRD_ETHER ? ETH_HLEN : 0;
        unsigned int psh_hlen = sizeof(struct ipv6hdr) + t->encap_hlen;
        unsigned int max_headroom = psh_hlen;
        __be16 payload_protocol;
        bool use_cache = false;
        u8 hop_limit;
        int err = -1;

        payload_protocol = skb_protocol(skb, true);

        if (t->parms.collect_md) {
                hop_limit = skb_tunnel_info(skb)->key.ttl;
                goto route_lookup;
        } else {
                hop_limit = t->parms.hop_limit;
        }

        /* NBMA tunnel */
        if (ipv6_addr_any(&t->parms.raddr)) {
                if (payload_protocol == htons(ETH_P_IPV6)) {
                        struct in6_addr *addr6;
                        struct neighbour *neigh;
                        int addr_type;

                        if (!skb_dst(skb))
                                goto tx_err_link_failure;

                        neigh = dst_neigh_lookup(skb_dst(skb),
                                                 &ipv6_hdr(skb)->daddr);
                        if (!neigh)
                                goto tx_err_link_failure;

                        addr6 = (struct in6_addr *)&neigh->primary_key;
                        addr_type = ipv6_addr_type(addr6);

                        if (addr_type == IPV6_ADDR_ANY)
                                addr6 = &ipv6_hdr(skb)->daddr;

                        memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
                        neigh_release(neigh);
                } else if (payload_protocol == htons(ETH_P_IP)) {
                        const struct rtable *rt = skb_rtable(skb);

                        if (!rt)
                                goto tx_err_link_failure;

                        if (rt->rt_gw_family == AF_INET6)
                                memcpy(&fl6->daddr, &rt->rt_gw6, sizeof(fl6->daddr));
                }
        } else if (t->parms.proto != 0 && !(t->parms.flags &
                                            (IP6_TNL_F_USE_ORIG_TCLASS |
                                             IP6_TNL_F_USE_ORIG_FWMARK))) {
                /* enable the cache only if neither the outer protocol nor the
                 * routing decision depends on the current inner header value
                 */
                use_cache = true;
        }

        if (use_cache)
                dst = dst_cache_get(&t->dst_cache);

        if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr))
                goto tx_err_link_failure;

        if (!dst) {
route_lookup:
                /* add dsfield to flowlabel for route lookup */
                fl6->flowlabel = ip6_make_flowinfo(dsfield, fl6->flowlabel);

                dst = ip6_route_output(net, NULL, fl6);

                if (dst->error)
                        goto tx_err_link_failure;
                dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), NULL, 0);
                if (IS_ERR(dst)) {
                        err = PTR_ERR(dst);
                        dst = NULL;
                        goto tx_err_link_failure;
                }
                if (t->parms.collect_md && ipv6_addr_any(&fl6->saddr) &&
                    ipv6_dev_get_saddr(net, ip6_dst_idev(dst)->dev,
                                       &fl6->daddr, 0, &fl6->saddr))
                        goto tx_err_link_failure;
                ndst = dst;
        }

        tdev = dst_dev(dst);

        if (tdev == dev) {
                DEV_STATS_INC(dev, collisions);
                net_warn_ratelimited("%s: Local routing loop detected!\n",
                                     t->parms.name);
                goto tx_err_dst_release;
        }
        mtu = dst6_mtu(dst) - eth_hlen - psh_hlen - t->tun_hlen;
        if (encap_limit >= 0) {
                max_headroom += 8;
                mtu -= 8;
        }
        mtu = max(mtu, skb->protocol == htons(ETH_P_IPV6) ?
                       IPV6_MIN_MTU : IPV4_MIN_MTU);

        skb_dst_update_pmtu_no_confirm(skb, mtu);
        if (skb->len - t->tun_hlen - eth_hlen > mtu && !skb_is_gso(skb)) {
                *pmtu = mtu;
                err = -EMSGSIZE;
                goto tx_err_dst_release;
        }

        if (t->err_count > 0) {
                if (time_before(jiffies,
                                t->err_time + IP6TUNNEL_ERR_TIMEO)) {
                        t->err_count--;

                        dst_link_failure(skb);
                } else {
                        t->err_count = 0;
                }
        }

        skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));

        /*
         * Okay, now see if we can stuff it in the buffer as-is.
         */
        max_headroom += LL_RESERVED_SPACE(tdev);

        if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
            (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
                struct sk_buff *new_skb;

                new_skb = skb_realloc_headroom(skb, max_headroom);
                if (!new_skb)
                        goto tx_err_dst_release;

                if (skb->sk)
                        skb_set_owner_w(new_skb, skb->sk);
                consume_skb(skb);
                skb = new_skb;
        }

        if (t->parms.collect_md) {
                if (t->encap.type != TUNNEL_ENCAP_NONE)
                        goto tx_err_dst_release;
        } else {
                if (use_cache && ndst)
                        dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr);
        }
        skb_dst_set(skb, dst);

        if (hop_limit == 0) {
                if (payload_protocol == htons(ETH_P_IP))
                        hop_limit = ip_hdr(skb)->ttl;
                else if (payload_protocol == htons(ETH_P_IPV6))
                        hop_limit = ipv6_hdr(skb)->hop_limit;
                else
                        hop_limit = ip6_dst_hoplimit(dst);
        }

        /* Calculate max headroom for all the headers and adjust
         * needed_headroom if necessary.
         */
        max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr)
                        + dst->header_len + t->hlen;
        ip_tunnel_adj_headroom(dev, max_headroom);

        err = ip6_tnl_encap(skb, t, &proto, fl6);
        if (err)
                return err;

        if (encap_limit >= 0) {
                init_tel_txopt(&opt, encap_limit);
                proto = ipv6_push_frag_opts(skb, &opt.ops, proto);
        }

        skb_push(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        ipv6h = ipv6_hdr(skb);
        ip6_flow_hdr(ipv6h, dsfield,
                     ip6_make_flowlabel(net, skb, fl6->flowlabel, true, fl6));
        ipv6h->hop_limit = hop_limit;
        ipv6h->nexthdr = proto;
        ipv6h->saddr = fl6->saddr;
        ipv6h->daddr = fl6->daddr;
        ip6tunnel_xmit(NULL, skb, dev, 0);
        return 0;
tx_err_link_failure:
        DEV_STATS_INC(dev, tx_carrier_errors);
        dst_link_failure(skb);
tx_err_dst_release:
        dst_release(dst);
        return err;
}
EXPORT_SYMBOL(ip6_tnl_xmit);

static inline int
ipxip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev,
                u8 protocol)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct ipv6hdr *ipv6h;
        const struct iphdr  *iph;
        int encap_limit = -1;
        __u16 offset;
        struct flowi6 fl6;
        __u8 dsfield, orig_dsfield;
        __u32 mtu;
        u8 tproto;
        int err;

        tproto = READ_ONCE(t->parms.proto);
        if (tproto != protocol && tproto != 0)
                return -1;

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

                tun_info = skb_tunnel_info(skb);
                if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
                             ip_tunnel_info_af(tun_info) != AF_INET6))
                        return -1;
                key = &tun_info->key;
                memset(&fl6, 0, sizeof(fl6));
                fl6.flowi6_proto = protocol;
                fl6.saddr = key->u.ipv6.src;
                fl6.daddr = key->u.ipv6.dst;
                fl6.flowlabel = key->label;
                dsfield =  key->tos;
                switch (protocol) {
                case IPPROTO_IPIP:
                        iph = ip_hdr(skb);
                        orig_dsfield = ipv4_get_dsfield(iph);
                        break;
                case IPPROTO_IPV6:
                        ipv6h = ipv6_hdr(skb);
                        orig_dsfield = ipv6_get_dsfield(ipv6h);
                        break;
                default:
                        orig_dsfield = dsfield;
                        break;
                }
        } else {
                if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                        encap_limit = t->parms.encap_limit;
                if (protocol == IPPROTO_IPV6) {
                        offset = ip6_tnl_parse_tlv_enc_lim(skb,
                                                skb_network_header(skb));
                        /* ip6_tnl_parse_tlv_enc_lim() might have
                         * reallocated skb->head
                         */
                        if (offset > 0) {
                                struct ipv6_tlv_tnl_enc_lim *tel;

                                tel = (void *)&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;
                        }
                }

                memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
                fl6.flowi6_proto = protocol;

                if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                        fl6.flowi6_mark = skb->mark;
                else
                        fl6.flowi6_mark = t->parms.fwmark;
                switch (protocol) {
                case IPPROTO_IPIP:
                        iph = ip_hdr(skb);
                        orig_dsfield = ipv4_get_dsfield(iph);
                        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
                                dsfield = orig_dsfield;
                        else
                                dsfield = ip6_tclass(t->parms.flowinfo);
                        break;
                case IPPROTO_IPV6:
                        ipv6h = ipv6_hdr(skb);
                        orig_dsfield = ipv6_get_dsfield(ipv6h);
                        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
                                dsfield = orig_dsfield;
                        else
                                dsfield = ip6_tclass(t->parms.flowinfo);
                        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)
                                fl6.flowlabel |= ip6_flowlabel(ipv6h);
                        break;
                default:
                        orig_dsfield = dsfield = ip6_tclass(t->parms.flowinfo);
                        break;
                }
        }

        fl6.flowi6_uid = sock_net_uid(dev_net(dev), NULL);
        dsfield = INET_ECN_encapsulate(dsfield, orig_dsfield);

        if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6))
                return -1;

        skb_set_inner_ipproto(skb, protocol);

        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
                           protocol);
        if (err != 0) {
                /* XXX: send ICMP error even if DF is not set. */
                if (err == -EMSGSIZE)
                        switch (protocol) {
                        case IPPROTO_IPIP:
                                icmp_ndo_send(skb, ICMP_DEST_UNREACH,
                                              ICMP_FRAG_NEEDED, htonl(mtu));
                                break;
                        case IPPROTO_IPV6:
                                icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
                                break;
                        default:
                                break;
                        }
                return -1;
        }

        return 0;
}

static netdev_tx_t
ip6_tnl_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        u8 ipproto;
        int ret;

        if (!pskb_inet_may_pull(skb))
                goto tx_err;

        switch (skb->protocol) {
        case htons(ETH_P_IP):
                ipproto = IPPROTO_IPIP;
                break;
        case htons(ETH_P_IPV6):
                if (ip6_tnl_addr_conflict(t, ipv6_hdr(skb)))
                        goto tx_err;
                ipproto = IPPROTO_IPV6;
                break;
        case htons(ETH_P_MPLS_UC):
                ipproto = IPPROTO_MPLS;
                break;
        default:
                goto tx_err;
        }

        ret = ipxip6_tnl_xmit(skb, dev, ipproto);
        if (ret < 0)
                goto tx_err;

        return NETDEV_TX_OK;

tx_err:
        DEV_STATS_INC(dev, tx_errors);
        DEV_STATS_INC(dev, tx_dropped);
        kfree_skb(skb);
        return NETDEV_TX_OK;
}

static void ip6_tnl_link_config(struct ip6_tnl *t)
{
        struct net_device *dev = t->dev;
        struct net_device *tdev = NULL;
        struct __ip6_tnl_parm *p = &t->parms;
        struct flowi6 *fl6 = &t->fl.u.ip6;
        int t_hlen;
        int mtu;

        __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;

        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->flags |= IFF_POINTOPOINT;
        else
                dev->flags &= ~IFF_POINTOPOINT;

        t->tun_hlen = 0;
        t->hlen = t->encap_hlen + t->tun_hlen;
        t_hlen = t->hlen + sizeof(struct ipv6hdr);

        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) {
                        tdev = rt->dst.dev;
                        ip6_rt_put(rt);
                }

                if (!tdev && p->link)
                        tdev = __dev_get_by_index(t->net, p->link);

                if (tdev) {
                        dev->needed_headroom = tdev->hard_header_len +
                                tdev->needed_headroom + t_hlen;
                        mtu = min_t(unsigned int, tdev->mtu, IP6_MAX_MTU);

                        mtu = mtu - t_hlen;
                        if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                                mtu -= 8;

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

/**
 * ip6_tnl_change - update the tunnel parameters
 *   @t: tunnel to be changed
 *   @p: tunnel configuration parameters
 *
 * Description:
 *   ip6_tnl_change() updates the tunnel parameters
 **/

static void
ip6_tnl_change(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.fwmark = p->fwmark;
        dst_cache_reset(&t->dst_cache);
        ip6_tnl_link_config(t);
}

static void ip6_tnl_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
{
        struct net *net = t->net;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

        ip6_tnl_unlink(ip6n, t);
        synchronize_net();
        ip6_tnl_change(t, p);
        ip6_tnl_link(ip6n, t);
        netdev_state_change(t->dev);
}

static int ip6_tnl0_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p,
                           bool strict)
{
        /* For the default ip6tnl0 device, allow changing only the protocol
         * (the IP6_TNL_F_CAP_PER_PACKET flag is set on ip6tnl0, and all other
         * parameters are 0).
         */
        if (strict &&
            (!ipv6_addr_any(&p->laddr) || !ipv6_addr_any(&p->raddr) ||
             p->flags != t->parms.flags || p->hop_limit || p->encap_limit ||
             p->flowinfo || p->link || p->fwmark || p->collect_md))
                return -EINVAL;

        t->parms.proto = p->proto;
        netdev_state_change(t->dev);
        return 0;
}

static void
ip6_tnl_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm *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->proto = u->proto;
        memcpy(p->name, u->name, sizeof(u->name));
}

static void
ip6_tnl_parm_to_user(struct ip6_tnl_parm *u, const struct __ip6_tnl_parm *p)
{
        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->proto = p->proto;
        memcpy(u->name, p->name, sizeof(u->name));
}

/**
 * ip6_tnl_siocdevprivate - configure ipv6 tunnels from userspace
 *   @dev: virtual device associated with tunnel
 *   @ifr: unused
 *   @data: parameters passed from userspace
 *   @cmd: command to be performed
 *
 * Description:
 *   ip6_tnl_ioctl() is used for managing IPv6 tunnels
 *   from userspace.
 *
 *   The possible commands are the following:
 *     %SIOCGETTUNNEL: get tunnel parameters for device
 *     %SIOCADDTUNNEL: add tunnel matching given tunnel parameters
 *     %SIOCCHGTUNNEL: change tunnel parameters to those given
 *     %SIOCDELTUNNEL: delete tunnel
 *
 *   The fallback device "ip6tnl0", created during module
 *   initialization, can be used for creating other tunnel devices.
 *
 * Return:
 *   0 on success,
 *   %-EFAULT if unable to copy data to or from userspace,
 *   %-EPERM if current process hasn't %CAP_NET_ADMIN set
 *   %-EINVAL if passed tunnel parameters are invalid,
 *   %-EEXIST if changing a tunnel's parameters would cause a conflict
 *   %-ENODEV if attempting to change or delete a nonexisting device
 **/

static int
ip6_tnl_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
                       void __user *data, int cmd)
{
        int err = 0;
        struct ip6_tnl_parm p;
        struct __ip6_tnl_parm p1;
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = t->net;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

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

        switch (cmd) {
        case SIOCGETTUNNEL:
                if (dev == ip6n->fb_tnl_dev) {
                        if (copy_from_user(&p, data, sizeof(p))) {
                                err = -EFAULT;
                                break;
                        }
                        ip6_tnl_parm_from_user(&p1, &p);
                        t = ip6_tnl_locate(net, &p1, 0);
                        if (IS_ERR(t))
                                t = netdev_priv(dev);
                } else {
                        memset(&p, 0, sizeof(p));
                }
                ip6_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))
                        break;
                err = -EFAULT;
                if (copy_from_user(&p, data, sizeof(p)))
                        break;
                err = -EINVAL;
                if (p.proto != IPPROTO_IPV6 && p.proto != IPPROTO_IPIP &&
                    p.proto != 0)
                        break;
                ip6_tnl_parm_from_user(&p1, &p);
                t = ip6_tnl_locate(net, &p1, cmd == SIOCADDTUNNEL);
                if (cmd == SIOCCHGTUNNEL) {
                        if (!IS_ERR(t)) {
                                if (t->dev != dev) {
                                        err = -EEXIST;
                                        break;
                                }
                        } else
                                t = netdev_priv(dev);
                        if (dev == ip6n->fb_tnl_dev)
                                ip6_tnl0_update(t, &p1, false);
                        else
                                ip6_tnl_update(t, &p1);
                }
                if (!IS_ERR(t)) {
                        err = 0;
                        ip6_tnl_parm_to_user(&p, &t->parms);
                        if (copy_to_user(data, &p, sizeof(p)))
                                err = -EFAULT;

                } else {
                        err = PTR_ERR(t);
                }
                break;
        case SIOCDELTUNNEL:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        break;

                if (dev == ip6n->fb_tnl_dev) {
                        err = -EFAULT;
                        if (copy_from_user(&p, data, sizeof(p)))
                                break;
                        err = -ENOENT;
                        ip6_tnl_parm_from_user(&p1, &p);
                        t = ip6_tnl_locate(net, &p1, 0);
                        if (IS_ERR(t))
                                break;
                        err = -EPERM;
                        if (t->dev == ip6n->fb_tnl_dev)
                                break;
                        dev = t->dev;
                }
                err = 0;
                unregister_netdevice(dev);
                break;
        default:
                err = -EINVAL;
        }
        return err;
}

/**
 * ip6_tnl_change_mtu - change mtu manually for tunnel device
 *   @dev: virtual device associated with tunnel
 *   @new_mtu: the new mtu
 *
 * Return:
 *   0 on success,
 *   %-EINVAL if mtu too small
 **/

int ip6_tnl_change_mtu(struct net_device *dev, int new_mtu)
{
        struct ip6_tnl *tnl = netdev_priv(dev);
        int t_hlen;

        t_hlen = tnl->hlen + sizeof(struct ipv6hdr);
        if (tnl->parms.proto == IPPROTO_IPV6) {
                if (new_mtu < IPV6_MIN_MTU)
                        return -EINVAL;
        } else {
                if (new_mtu < ETH_MIN_MTU)
                        return -EINVAL;
        }
        if (tnl->parms.proto == IPPROTO_IPV6 || tnl->parms.proto == 0) {
                if (new_mtu > IP6_MAX_MTU - dev->hard_header_len - t_hlen)
                        return -EINVAL;
        } else {
                if (new_mtu > IP_MAX_MTU - dev->hard_header_len - t_hlen)
                        return -EINVAL;
        }
        WRITE_ONCE(dev->mtu, new_mtu);
        return 0;
}
EXPORT_SYMBOL(ip6_tnl_change_mtu);

int ip6_tnl_get_iflink(const struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);

        return READ_ONCE(t->parms.link);
}
EXPORT_SYMBOL(ip6_tnl_get_iflink);

int ip6_tnl_encap_add_ops(const struct ip6_tnl_encap_ops *ops,
                          unsigned int num)
{
        if (num >= MAX_IPTUN_ENCAP_OPS)
                return -ERANGE;

        return !cmpxchg((const struct ip6_tnl_encap_ops **)
                        &ip6tun_encaps[num],
                        NULL, ops) ? 0 : -1;
}
EXPORT_SYMBOL(ip6_tnl_encap_add_ops);

int ip6_tnl_encap_del_ops(const struct ip6_tnl_encap_ops *ops,
                          unsigned int num)
{
        int ret;

        if (num >= MAX_IPTUN_ENCAP_OPS)
                return -ERANGE;

        ret = (cmpxchg((const struct ip6_tnl_encap_ops **)
                       &ip6tun_encaps[num],
                       ops, NULL) == ops) ? 0 : -1;

        synchronize_net();

        return ret;
}
EXPORT_SYMBOL(ip6_tnl_encap_del_ops);

int ip6_tnl_encap_setup(struct ip6_tnl *t,
                        struct ip_tunnel_encap *ipencap)
{
        int hlen;

        memset(&t->encap, 0, sizeof(t->encap));

        hlen = ip6_encap_hlen(ipencap);
        if (hlen < 0)
                return hlen;

        t->encap.type = ipencap->type;
        t->encap.sport = ipencap->sport;
        t->encap.dport = ipencap->dport;
        t->encap.flags = ipencap->flags;

        t->encap_hlen = hlen;
        t->hlen = t->encap_hlen + t->tun_hlen;

        return 0;
}
EXPORT_SYMBOL_GPL(ip6_tnl_encap_setup);

static int ip6_tnl_fill_forward_path(struct net_device_path_ctx *ctx,
                                     struct net_device_path *path)
{
        struct ip6_tnl *t = netdev_priv(ctx->dev);
        struct flowi6 fl6 = {
                .daddr = t->parms.raddr,
        };
        struct dst_entry *dst;
        int err;

        dst = ip6_route_output(dev_net(ctx->dev), NULL, &fl6);
        if (!dst->error) {
                path->type = DEV_PATH_TUN;
                path->tun.src_v6 = t->parms.laddr;
                path->tun.dst_v6 = t->parms.raddr;
                path->tun.l3_proto = IPPROTO_IPV6;
                path->dev = ctx->dev;
                ctx->dev = dst->dev;
        }

        err = dst->error;
        dst_release(dst);

        return err;
}

static const struct net_device_ops ip6_tnl_netdev_ops = {
        .ndo_init       = ip6_tnl_dev_init,
        .ndo_uninit     = ip6_tnl_dev_uninit,
        .ndo_start_xmit = ip6_tnl_start_xmit,
        .ndo_siocdevprivate = ip6_tnl_siocdevprivate,
        .ndo_change_mtu = ip6_tnl_change_mtu,
        .ndo_get_stats64 = dev_get_tstats64,
        .ndo_get_iflink = ip6_tnl_get_iflink,
        .ndo_fill_forward_path = ip6_tnl_fill_forward_path,
};

#define IPXIPX_FEATURES (NETIF_F_SG |           \
                         NETIF_F_FRAGLIST |     \
                         NETIF_F_HIGHDMA |      \
                         NETIF_F_GSO_SOFTWARE | \
                         NETIF_F_HW_CSUM)

/**
 * ip6_tnl_dev_setup - setup virtual tunnel device
 *   @dev: virtual device associated with tunnel
 *
 * Description:
 *   Initialize function pointers and device parameters
 **/

static void ip6_tnl_dev_setup(struct net_device *dev)
{
        dev->netdev_ops = &ip6_tnl_netdev_ops;
        dev->header_ops = &ip_tunnel_header_ops;
        dev->needs_free_netdev = true;
        dev->priv_destructor = ip6_dev_free;

        dev->type = ARPHRD_TUNNEL6;
        dev->flags |= IFF_NOARP;
        dev->addr_len = sizeof(struct in6_addr);
        dev->lltx = true;
        dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
        netif_keep_dst(dev);

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

        /* This perm addr will be used as interface identifier by IPv6 */
        dev->addr_assign_type = NET_ADDR_RANDOM;
        eth_random_addr(dev->perm_addr);
}


/**
 * ip6_tnl_dev_init_gen - general initializer for all tunnel devices
 *   @dev: virtual device associated with tunnel
 **/

static inline int
ip6_tnl_dev_init_gen(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int ret;
        int t_hlen;

        t->dev = dev;

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

        ret = gro_cells_init(&t->gro_cells, dev);
        if (ret)
                goto destroy_dst;

        t->tun_hlen = 0;
        t->hlen = t->encap_hlen + t->tun_hlen;
        t_hlen = t->hlen + sizeof(struct ipv6hdr);

        dev->type = ARPHRD_TUNNEL6;
        dev->mtu = ETH_DATA_LEN - t_hlen;
        if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                dev->mtu -= 8;
        dev->min_mtu = ETH_MIN_MTU;
        dev->max_mtu = IP6_MAX_MTU - dev->hard_header_len - t_hlen;

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

destroy_dst:
        dst_cache_destroy(&t->dst_cache);

        return ret;
}

/**
 * ip6_tnl_dev_init - initializer for all non fallback tunnel devices
 *   @dev: virtual device associated with tunnel
 **/

static int ip6_tnl_dev_init(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int err = ip6_tnl_dev_init_gen(dev);

        if (err)
                return err;
        ip6_tnl_link_config(t);
        if (t->parms.collect_md)
                netif_keep_dst(dev);
        return 0;
}

/**
 * ip6_fb_tnl_dev_init - initializer for fallback tunnel device
 *   @dev: fallback device
 *
 * Return: 0
 **/

static int __net_init ip6_fb_tnl_dev_init(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = dev_net(dev);
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

        t->net = net;
        t->parms.proto = IPPROTO_IPV6;

        rcu_assign_pointer(ip6n->tnls_wc[0], t);
        return 0;
}

static int ip6_tnl_validate(struct nlattr *tb[], struct nlattr *data[],
                            struct netlink_ext_ack *extack)
{
        u8 proto;

        if (!data || !data[IFLA_IPTUN_PROTO])
                return 0;

        proto = nla_get_u8(data[IFLA_IPTUN_PROTO]);
        if (proto != IPPROTO_IPV6 &&
            proto != IPPROTO_IPIP &&
            proto != 0)
                return -EINVAL;

        return 0;
}

static void ip6_tnl_netlink_parms(struct nlattr *data[],
                                  struct __ip6_tnl_parm *parms)
{
        memset(parms, 0, sizeof(*parms));

        if (!data)
                return;

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

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

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

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

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

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

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

        if (data[IFLA_IPTUN_PROTO])
                parms->proto = nla_get_u8(data[IFLA_IPTUN_PROTO]);

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

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

static int ip6_tnl_newlink(struct net_device *dev,
                           struct rtnl_newlink_params *params,
                           struct netlink_ext_ack *extack)
{
        struct nlattr **data = params->data;
        struct nlattr **tb = params->tb;
        struct ip_tunnel_encap ipencap;
        struct ip6_tnl_net *ip6n;
        struct ip6_tnl *nt, *t;
        struct net *net;
        int err;

        net = params->link_net ? : dev_net(dev);
        ip6n = net_generic(net, ip6_tnl_net_id);
        nt = netdev_priv(dev);
        nt->net = net;

        if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
                err = ip6_tnl_encap_setup(nt, &ipencap);
                if (err < 0)
                        return err;
        }

        ip6_tnl_netlink_parms(data, &nt->parms);

        if (nt->parms.collect_md) {
                if (rtnl_dereference(ip6n->collect_md_tun))
                        return -EEXIST;
        } else {
                t = ip6_tnl_locate(net, &nt->parms, 0);
                if (!IS_ERR(t))
                        return -EEXIST;
        }

        err = ip6_tnl_create2(dev);
        if (!err && tb[IFLA_MTU])
                ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU]));

        return err;
}

static int ip6_tnl_changelink(struct net_device *dev, struct nlattr *tb[],
                              struct nlattr *data[],
                              struct netlink_ext_ack *extack)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct __ip6_tnl_parm p;
        struct net *net = t->net;
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
        struct ip_tunnel_encap ipencap;

        if (dev == ip6n->fb_tnl_dev) {
                if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
                        /* iproute2 always sets TUNNEL_ENCAP_FLAG_CSUM6, so
                         * let's ignore this flag.
                         */
                        ipencap.flags &= ~TUNNEL_ENCAP_FLAG_CSUM6;
                        if (memchr_inv(&ipencap, 0, sizeof(ipencap))) {
                                NL_SET_ERR_MSG(extack,
                                               "Only protocol can be changed for fallback tunnel, not encap params");
                                return -EINVAL;
                        }
                }

                ip6_tnl_netlink_parms(data, &p);
                if (ip6_tnl0_update(t, &p, true) < 0) {
                        NL_SET_ERR_MSG(extack,
                                       "Only protocol can be changed for fallback tunnel");
                        return -EINVAL;
                }

                return 0;
        }

        if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
                int err = ip6_tnl_encap_setup(t, &ipencap);

                if (err < 0)
                        return err;
        }
        ip6_tnl_netlink_parms(data, &p);
        if (p.collect_md)
                return -EINVAL;

        t = ip6_tnl_locate(net, &p, 0);
        if (!IS_ERR(t)) {
                if (t->dev != dev)
                        return -EEXIST;
        } else
                t = netdev_priv(dev);

        ip6_tnl_update(t, &p);
        return 0;
}

static void ip6_tnl_dellink(struct net_device *dev, struct list_head *head)
{
        struct net *net = dev_net(dev);
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);

        if (dev != ip6n->fb_tnl_dev)
                unregister_netdevice_queue(dev, head);
}

static size_t ip6_tnl_get_size(const struct net_device *dev)
{
        return
                /* IFLA_IPTUN_LINK */
                nla_total_size(4) +
                /* IFLA_IPTUN_LOCAL */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_IPTUN_REMOTE */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_IPTUN_TTL */
                nla_total_size(1) +
                /* IFLA_IPTUN_ENCAP_LIMIT */
                nla_total_size(1) +
                /* IFLA_IPTUN_FLOWINFO */
                nla_total_size(4) +
                /* IFLA_IPTUN_FLAGS */
                nla_total_size(4) +
                /* IFLA_IPTUN_PROTO */
                nla_total_size(1) +
                /* IFLA_IPTUN_ENCAP_TYPE */
                nla_total_size(2) +
                /* IFLA_IPTUN_ENCAP_FLAGS */
                nla_total_size(2) +
                /* IFLA_IPTUN_ENCAP_SPORT */
                nla_total_size(2) +
                /* IFLA_IPTUN_ENCAP_DPORT */
                nla_total_size(2) +
                /* IFLA_IPTUN_COLLECT_METADATA */
                nla_total_size(0) +
                /* IFLA_IPTUN_FWMARK */
                nla_total_size(4) +
                0;
}

static int ip6_tnl_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
        struct ip6_tnl *tunnel = netdev_priv(dev);
        struct __ip6_tnl_parm *parm = &tunnel->parms;

        if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
            nla_put_in6_addr(skb, IFLA_IPTUN_LOCAL, &parm->laddr) ||
            nla_put_in6_addr(skb, IFLA_IPTUN_REMOTE, &parm->raddr) ||
            nla_put_u8(skb, IFLA_IPTUN_TTL, parm->hop_limit) ||
            nla_put_u8(skb, IFLA_IPTUN_ENCAP_LIMIT, parm->encap_limit) ||
            nla_put_be32(skb, IFLA_IPTUN_FLOWINFO, parm->flowinfo) ||
            nla_put_u32(skb, IFLA_IPTUN_FLAGS, parm->flags) ||
            nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->proto) ||
            nla_put_u32(skb, IFLA_IPTUN_FWMARK, parm->fwmark))
                goto nla_put_failure;

        if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE, tunnel->encap.type) ||
            nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT, tunnel->encap.sport) ||
            nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT, tunnel->encap.dport) ||
            nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS, tunnel->encap.flags))
                goto nla_put_failure;

        if (parm->collect_md)
                if (nla_put_flag(skb, IFLA_IPTUN_COLLECT_METADATA))
                        goto nla_put_failure;

        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

struct net *ip6_tnl_get_link_net(const struct net_device *dev)
{
        struct ip6_tnl *tunnel = netdev_priv(dev);

        return READ_ONCE(tunnel->net);
}
EXPORT_SYMBOL(ip6_tnl_get_link_net);

static const struct nla_policy ip6_tnl_policy[IFLA_IPTUN_MAX + 1] = {
        [IFLA_IPTUN_LINK]               = { .type = NLA_U32 },
        [IFLA_IPTUN_LOCAL]              = { .len = sizeof(struct in6_addr) },
        [IFLA_IPTUN_REMOTE]             = { .len = sizeof(struct in6_addr) },
        [IFLA_IPTUN_TTL]                = { .type = NLA_U8 },
        [IFLA_IPTUN_ENCAP_LIMIT]        = { .type = NLA_U8 },
        [IFLA_IPTUN_FLOWINFO]           = { .type = NLA_U32 },
        [IFLA_IPTUN_FLAGS]              = { .type = NLA_U32 },
        [IFLA_IPTUN_PROTO]              = { .type = NLA_U8 },
        [IFLA_IPTUN_ENCAP_TYPE]         = { .type = NLA_U16 },
        [IFLA_IPTUN_ENCAP_FLAGS]        = { .type = NLA_U16 },
        [IFLA_IPTUN_ENCAP_SPORT]        = { .type = NLA_U16 },
        [IFLA_IPTUN_ENCAP_DPORT]        = { .type = NLA_U16 },
        [IFLA_IPTUN_COLLECT_METADATA]   = { .type = NLA_FLAG },
        [IFLA_IPTUN_FWMARK]             = { .type = NLA_U32 },
};

static struct rtnl_link_ops ip6_link_ops __read_mostly = {
        .kind           = "ip6tnl",
        .maxtype        = IFLA_IPTUN_MAX,
        .policy         = ip6_tnl_policy,
        .priv_size      = sizeof(struct ip6_tnl),
        .setup          = ip6_tnl_dev_setup,
        .validate       = ip6_tnl_validate,
        .newlink        = ip6_tnl_newlink,
        .changelink     = ip6_tnl_changelink,
        .dellink        = ip6_tnl_dellink,
        .get_size       = ip6_tnl_get_size,
        .fill_info      = ip6_tnl_fill_info,
        .get_link_net   = ip6_tnl_get_link_net,
};

static struct xfrm6_tunnel ip4ip6_handler __read_mostly = {
        .handler        = ip4ip6_rcv,
        .err_handler    = ip4ip6_err,
        .priority       =       1,
};

static struct xfrm6_tunnel ip6ip6_handler __read_mostly = {
        .handler        = ip6ip6_rcv,
        .err_handler    = ip6ip6_err,
        .priority       =       1,
};

static struct xfrm6_tunnel mplsip6_handler __read_mostly = {
        .handler        = mplsip6_rcv,
        .err_handler    = mplsip6_err,
        .priority       =       1,
};

static void __net_exit ip6_tnl_exit_rtnl_net(struct net *net, struct list_head *list)
{
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
        struct net_device *dev, *aux;
        int h;
        struct ip6_tnl *t;

        for_each_netdev_safe(net, dev, aux)
                if (dev->rtnl_link_ops == &ip6_link_ops)
                        unregister_netdevice_queue(dev, list);

        for (h = 0; h < IP6_TUNNEL_HASH_SIZE; h++) {
                t = rtnl_net_dereference(net, ip6n->tnls_r_l[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, list);

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

        t = rtnl_net_dereference(net, ip6n->tnls_wc[0]);
        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, list);

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

static int __net_init ip6_tnl_init_net(struct net *net)
{
        struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
        struct ip6_tnl *t = NULL;
        int err;

        ip6n->tnls[0] = ip6n->tnls_wc;
        ip6n->tnls[1] = ip6n->tnls_r_l;

        if (!net_has_fallback_tunnels(net))
                return 0;
        err = -ENOMEM;
        ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
                                        NET_NAME_UNKNOWN, ip6_tnl_dev_setup);

        if (!ip6n->fb_tnl_dev)
                goto err_alloc_dev;
        dev_net_set(ip6n->fb_tnl_dev, net);
        ip6n->fb_tnl_dev->rtnl_link_ops = &ip6_link_ops;
        /* FB netdevice is special: we have one, and only one per netns.
         * Allowing to move it to another netns is clearly unsafe.
         */
        ip6n->fb_tnl_dev->netns_immutable = true;

        err = ip6_fb_tnl_dev_init(ip6n->fb_tnl_dev);
        if (err < 0)
                goto err_register;

        err = register_netdev(ip6n->fb_tnl_dev);
        if (err < 0)
                goto err_register;

        t = netdev_priv(ip6n->fb_tnl_dev);

        strcpy(t->parms.name, ip6n->fb_tnl_dev->name);
        return 0;

err_register:
        free_netdev(ip6n->fb_tnl_dev);
err_alloc_dev:
        return err;
}

static struct pernet_operations ip6_tnl_net_ops = {
        .init = ip6_tnl_init_net,
        .exit_rtnl = ip6_tnl_exit_rtnl_net,
        .id   = &ip6_tnl_net_id,
        .size = sizeof(struct ip6_tnl_net),
};

/**
 * ip6_tunnel_init - register protocol and reserve needed resources
 *
 * Return: 0 on success
 **/

static int __init ip6_tunnel_init(void)
{
        int  err;

        if (!ipv6_mod_enabled())
                return -EOPNOTSUPP;

        err = register_pernet_device(&ip6_tnl_net_ops);
        if (err < 0)
                goto out_pernet;

        err = xfrm6_tunnel_register(&ip4ip6_handler, AF_INET);
        if (err < 0) {
                pr_err("%s: can't register ip4ip6\n", __func__);
                goto out_ip4ip6;
        }

        err = xfrm6_tunnel_register(&ip6ip6_handler, AF_INET6);
        if (err < 0) {
                pr_err("%s: can't register ip6ip6\n", __func__);
                goto out_ip6ip6;
        }

        if (ip6_tnl_mpls_supported()) {
                err = xfrm6_tunnel_register(&mplsip6_handler, AF_MPLS);
                if (err < 0) {
                        pr_err("%s: can't register mplsip6\n", __func__);
                        goto out_mplsip6;
                }
        }

        err = rtnl_link_register(&ip6_link_ops);
        if (err < 0)
                goto rtnl_link_failed;

        return 0;

rtnl_link_failed:
        if (ip6_tnl_mpls_supported())
                xfrm6_tunnel_deregister(&mplsip6_handler, AF_MPLS);
out_mplsip6:
        xfrm6_tunnel_deregister(&ip6ip6_handler, AF_INET6);
out_ip6ip6:
        xfrm6_tunnel_deregister(&ip4ip6_handler, AF_INET);
out_ip4ip6:
        unregister_pernet_device(&ip6_tnl_net_ops);
out_pernet:
        return err;
}

/**
 * ip6_tunnel_cleanup - free resources and unregister protocol
 **/

static void __exit ip6_tunnel_cleanup(void)
{
        rtnl_link_unregister(&ip6_link_ops);
        if (xfrm6_tunnel_deregister(&ip4ip6_handler, AF_INET))
                pr_info("%s: can't deregister ip4ip6\n", __func__);

        if (xfrm6_tunnel_deregister(&ip6ip6_handler, AF_INET6))
                pr_info("%s: can't deregister ip6ip6\n", __func__);

        if (ip6_tnl_mpls_supported() &&
            xfrm6_tunnel_deregister(&mplsip6_handler, AF_MPLS))
                pr_info("%s: can't deregister mplsip6\n", __func__);
        unregister_pernet_device(&ip6_tnl_net_ops);
}

module_init(ip6_tunnel_init);
module_exit(ip6_tunnel_cleanup);