sit: Setup and TX path for sit/UDP foo-over-udp encapsulation

[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / sit.c

/*
 *      IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *      Changes:
 * Roger Venning <r.venning@telstra.com>:       6to4 support
 * Nate Thompson <nate@thebog.net>:             6to4 support
 * Fred Templin <fred.l.templin@boeing.com>:    isatap support
 */

#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/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/icmp.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <linux/netfilter_ipv4.h>
#include <linux/if_ether.h>

#include <net/sock.h>
#include <net/snmp.h>

#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/ndisc.h>
#include <net/addrconf.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/ip_tunnels.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/dsfield.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

/*
   This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c

   For comments look at net/ipv4/ip_gre.c --ANK
 */

#define HASH_SIZE  16
#define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)

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 int ipip6_tunnel_init(struct net_device *dev);
static void ipip6_tunnel_setup(struct net_device *dev);
static void ipip6_dev_free(struct net_device *dev);
static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
                      __be32 *v4dst);
static struct rtnl_link_ops sit_link_ops __read_mostly;

static int sit_net_id __read_mostly;
struct sit_net {
        struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
        struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
        struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
        struct ip_tunnel __rcu *tunnels_wc[1];
        struct ip_tunnel __rcu **tunnels[4];

        struct net_device *fb_tunnel_dev;
};

/*
 * Must be invoked with rcu_read_lock
 */
static struct ip_tunnel *ipip6_tunnel_lookup(struct net *net,
                struct net_device *dev, __be32 remote, __be32 local)
{
        unsigned int h0 = HASH(remote);
        unsigned int h1 = HASH(local);
        struct ip_tunnel *t;
        struct sit_net *sitn = net_generic(net, sit_net_id);

        for_each_ip_tunnel_rcu(t, sitn->tunnels_r_l[h0 ^ h1]) {
                if (local == t->parms.iph.saddr &&
                    remote == t->parms.iph.daddr &&
                    (!dev || !t->parms.link || dev->ifindex == t->parms.link) &&
                    (t->dev->flags & IFF_UP))
                        return t;
        }
        for_each_ip_tunnel_rcu(t, sitn->tunnels_r[h0]) {
                if (remote == t->parms.iph.daddr &&
                    (!dev || !t->parms.link || dev->ifindex == t->parms.link) &&
                    (t->dev->flags & IFF_UP))
                        return t;
        }
        for_each_ip_tunnel_rcu(t, sitn->tunnels_l[h1]) {
                if (local == t->parms.iph.saddr &&
                    (!dev || !t->parms.link || dev->ifindex == t->parms.link) &&
                    (t->dev->flags & IFF_UP))
                        return t;
        }
        t = rcu_dereference(sitn->tunnels_wc[0]);
        if ((t != NULL) && (t->dev->flags & IFF_UP))
                return t;
        return NULL;
}

static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
                struct ip_tunnel_parm *parms)
{
        __be32 remote = parms->iph.daddr;
        __be32 local = parms->iph.saddr;
        unsigned int h = 0;
        int prio = 0;

        if (remote) {
                prio |= 2;
                h ^= HASH(remote);
        }
        if (local) {
                prio |= 1;
                h ^= HASH(local);
        }
        return &sitn->tunnels[prio][h];
}

static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
                struct ip_tunnel *t)
{
        return __ipip6_bucket(sitn, &t->parms);
}

static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
{
        struct ip_tunnel __rcu **tp;
        struct ip_tunnel *iter;

        for (tp = ipip6_bucket(sitn, t);
             (iter = rtnl_dereference(*tp)) != NULL;
             tp = &iter->next) {
                if (t == iter) {
                        rcu_assign_pointer(*tp, t->next);
                        break;
                }
        }
}

static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
{
        struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);

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

static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
{
#ifdef CONFIG_IPV6_SIT_6RD
        struct ip_tunnel *t = netdev_priv(dev);

        if (t->dev == sitn->fb_tunnel_dev) {
                ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
                t->ip6rd.relay_prefix = 0;
                t->ip6rd.prefixlen = 16;
                t->ip6rd.relay_prefixlen = 0;
        } else {
                struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
                memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
        }
#endif
}

static int ipip6_tunnel_create(struct net_device *dev)
{
        struct ip_tunnel *t = netdev_priv(dev);
        struct net *net = dev_net(dev);
        struct sit_net *sitn = net_generic(net, sit_net_id);
        int err;

        err = ipip6_tunnel_init(dev);
        if (err < 0)
                goto out;
        ipip6_tunnel_clone_6rd(dev, sitn);

        if ((__force u16)t->parms.i_flags & SIT_ISATAP)
                dev->priv_flags |= IFF_ISATAP;

        err = register_netdevice(dev);
        if (err < 0)
                goto out;

        strcpy(t->parms.name, dev->name);
        dev->rtnl_link_ops = &sit_link_ops;

        dev_hold(dev);

        ipip6_tunnel_link(sitn, t);
        return 0;

out:
        return err;
}

static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
                struct ip_tunnel_parm *parms, int create)
{
        __be32 remote = parms->iph.daddr;
        __be32 local = parms->iph.saddr;
        struct ip_tunnel *t, *nt;
        struct ip_tunnel __rcu **tp;
        struct net_device *dev;
        char name[IFNAMSIZ];
        struct sit_net *sitn = net_generic(net, sit_net_id);

        for (tp = __ipip6_bucket(sitn, parms);
            (t = rtnl_dereference(*tp)) != NULL;
             tp = &t->next) {
                if (local == t->parms.iph.saddr &&
                    remote == t->parms.iph.daddr &&
                    parms->link == t->parms.link) {
                        if (create)
                                return NULL;
                        else
                                return t;
                }
        }
        if (!create)
                goto failed;

        if (parms->name[0])
                strlcpy(name, parms->name, IFNAMSIZ);
        else
                strcpy(name, "sit%d");

        dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
                           ipip6_tunnel_setup);
        if (dev == NULL)
                return NULL;

        dev_net_set(dev, net);

        nt = netdev_priv(dev);

        nt->parms = *parms;
        if (ipip6_tunnel_create(dev) < 0)
                goto failed_free;

        return nt;

failed_free:
        ipip6_dev_free(dev);
failed:
        return NULL;
}

#define for_each_prl_rcu(start)                 \
        for (prl = rcu_dereference(start);      \
             prl;                               \
             prl = rcu_dereference(prl->next))

static struct ip_tunnel_prl_entry *
__ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
{
        struct ip_tunnel_prl_entry *prl;

        for_each_prl_rcu(t->prl)
                if (prl->addr == addr)
                        break;
        return prl;

}

static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
                                struct ip_tunnel_prl __user *a)
{
        struct ip_tunnel_prl kprl, *kp;
        struct ip_tunnel_prl_entry *prl;
        unsigned int cmax, c = 0, ca, len;
        int ret = 0;

        if (copy_from_user(&kprl, a, sizeof(kprl)))
                return -EFAULT;
        cmax = kprl.datalen / sizeof(kprl);
        if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
                cmax = 1;

        /* For simple GET or for root users,
         * we try harder to allocate.
         */
        kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
                kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
                NULL;

        rcu_read_lock();

        ca = t->prl_count < cmax ? t->prl_count : cmax;

        if (!kp) {
                /* We don't try hard to allocate much memory for
                 * non-root users.
                 * For root users, retry allocating enough memory for
                 * the answer.
                 */
                kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
                if (!kp) {
                        ret = -ENOMEM;
                        goto out;
                }
        }

        c = 0;
        for_each_prl_rcu(t->prl) {
                if (c >= cmax)
                        break;
                if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
                        continue;
                kp[c].addr = prl->addr;
                kp[c].flags = prl->flags;
                c++;
                if (kprl.addr != htonl(INADDR_ANY))
                        break;
        }
out:
        rcu_read_unlock();

        len = sizeof(*kp) * c;
        ret = 0;
        if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
                ret = -EFAULT;

        kfree(kp);

        return ret;
}

static int
ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
{
        struct ip_tunnel_prl_entry *p;
        int err = 0;

        if (a->addr == htonl(INADDR_ANY))
                return -EINVAL;

        ASSERT_RTNL();

        for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
                if (p->addr == a->addr) {
                        if (chg) {
                                p->flags = a->flags;
                                goto out;
                        }
                        err = -EEXIST;
                        goto out;
                }
        }

        if (chg) {
                err = -ENXIO;
                goto out;
        }

        p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
        if (!p) {
                err = -ENOBUFS;
                goto out;
        }

        p->next = t->prl;
        p->addr = a->addr;
        p->flags = a->flags;
        t->prl_count++;
        rcu_assign_pointer(t->prl, p);
out:
        return err;
}

static void prl_list_destroy_rcu(struct rcu_head *head)
{
        struct ip_tunnel_prl_entry *p, *n;

        p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
        do {
                n = rcu_dereference_protected(p->next, 1);
                kfree(p);
                p = n;
        } while (p);
}

static int
ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
{
        struct ip_tunnel_prl_entry *x;
        struct ip_tunnel_prl_entry __rcu **p;
        int err = 0;

        ASSERT_RTNL();

        if (a && a->addr != htonl(INADDR_ANY)) {
                for (p = &t->prl;
                     (x = rtnl_dereference(*p)) != NULL;
                     p = &x->next) {
                        if (x->addr == a->addr) {
                                *p = x->next;
                                kfree_rcu(x, rcu_head);
                                t->prl_count--;
                                goto out;
                        }
                }
                err = -ENXIO;
        } else {
                x = rtnl_dereference(t->prl);
                if (x) {
                        t->prl_count = 0;
                        call_rcu(&x->rcu_head, prl_list_destroy_rcu);
                        t->prl = NULL;
                }
        }
out:
        return err;
}

static int
isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
{
        struct ip_tunnel_prl_entry *p;
        int ok = 1;

        rcu_read_lock();
        p = __ipip6_tunnel_locate_prl(t, iph->saddr);
        if (p) {
                if (p->flags & PRL_DEFAULT)
                        skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
                else
                        skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
        } else {
                const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;

                if (ipv6_addr_is_isatap(addr6) &&
                    (addr6->s6_addr32[3] == iph->saddr) &&
                    ipv6_chk_prefix(addr6, t->dev))
                        skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
                else
                        ok = 0;
        }
        rcu_read_unlock();
        return ok;
}

static void ipip6_tunnel_uninit(struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        struct sit_net *sitn = net_generic(tunnel->net, sit_net_id);

        if (dev == sitn->fb_tunnel_dev) {
                RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
        } else {
                ipip6_tunnel_unlink(sitn, tunnel);
                ipip6_tunnel_del_prl(tunnel, NULL);
        }
        ip_tunnel_dst_reset_all(tunnel);
        dev_put(dev);
}

/* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH
 * if sufficient data bytes are available
 */
static int ipip6_err_gen_icmpv6_unreach(struct sk_buff *skb)
{
        const struct iphdr *iph = (const struct iphdr *) skb->data;
        struct rt6_info *rt;
        struct sk_buff *skb2;

        if (!pskb_may_pull(skb, iph->ihl * 4 + sizeof(struct ipv6hdr) + 8))
                return 1;

        skb2 = skb_clone(skb, GFP_ATOMIC);

        if (!skb2)
                return 1;

        skb_dst_drop(skb2);
        skb_pull(skb2, iph->ihl * 4);
        skb_reset_network_header(skb2);

        rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0, 0);

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

        icmpv6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);

        if (rt)
                ip6_rt_put(rt);

        kfree_skb(skb2);

        return 0;
}

static int ipip6_err(struct sk_buff *skb, u32 info)
{
        const struct iphdr *iph = (const struct iphdr *)skb->data;
        const int type = icmp_hdr(skb)->type;
        const int code = icmp_hdr(skb)->code;
        struct ip_tunnel *t;
        int err;

        switch (type) {
        default:
        case ICMP_PARAMETERPROB:
                return 0;

        case ICMP_DEST_UNREACH:
                switch (code) {
                case ICMP_SR_FAILED:
                        /* Impossible event. */
                        return 0;
                default:
                        /* All others are translated to HOST_UNREACH.
                           rfc2003 contains "deep thoughts" about NET_UNREACH,
                           I believe they are just ether pollution. --ANK
                         */
                        break;
                }
                break;
        case ICMP_TIME_EXCEEDED:
                if (code != ICMP_EXC_TTL)
                        return 0;
                break;
        case ICMP_REDIRECT:
                break;
        }

        err = -ENOENT;

        t = ipip6_tunnel_lookup(dev_net(skb->dev),
                                skb->dev,
                                iph->daddr,
                                iph->saddr);
        if (t == NULL)
                goto out;

        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
                                 t->parms.link, 0, IPPROTO_IPV6, 0);
                err = 0;
                goto out;
        }
        if (type == ICMP_REDIRECT) {
                ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
                              IPPROTO_IPV6, 0);
                err = 0;
                goto out;
        }

        if (t->parms.iph.daddr == 0)
                goto out;

        err = 0;
        if (!ipip6_err_gen_icmpv6_unreach(skb))
                goto out;

        if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
                goto out;

        if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
                t->err_count++;
        else
                t->err_count = 1;
        t->err_time = jiffies;
out:
        return err;
}

static inline bool is_spoofed_6rd(struct ip_tunnel *tunnel, const __be32 v4addr,
                                  const struct in6_addr *v6addr)
{
        __be32 v4embed = 0;
        if (check_6rd(tunnel, v6addr, &v4embed) && v4addr != v4embed)
                return true;
        return false;
}

/* Checks if an address matches an address on the tunnel interface.
 * Used to detect the NAT of proto 41 packets and let them pass spoofing test.
 * Long story:
 * This function is called after we considered the packet as spoofed
 * in is_spoofed_6rd.
 * We may have a router that is doing NAT for proto 41 packets
 * for an internal station. Destination a.a.a.a/PREFIX:bbbb:bbbb
 * will be translated to n.n.n.n/PREFIX:bbbb:bbbb. And is_spoofed_6rd
 * function will return true, dropping the packet.
 * But, we can still check if is spoofed against the IP
 * addresses associated with the interface.
 */
static bool only_dnatted(const struct ip_tunnel *tunnel,
        const struct in6_addr *v6dst)
{
        int prefix_len;

#ifdef CONFIG_IPV6_SIT_6RD
        prefix_len = tunnel->ip6rd.prefixlen + 32
                - tunnel->ip6rd.relay_prefixlen;
#else
        prefix_len = 48;
#endif
        return ipv6_chk_custom_prefix(v6dst, prefix_len, tunnel->dev);
}

/* Returns true if a packet is spoofed */
static bool packet_is_spoofed(struct sk_buff *skb,
                              const struct iphdr *iph,
                              struct ip_tunnel *tunnel)
{
        const struct ipv6hdr *ipv6h;

        if (tunnel->dev->priv_flags & IFF_ISATAP) {
                if (!isatap_chksrc(skb, iph, tunnel))
                        return true;

                return false;
        }

        if (tunnel->dev->flags & IFF_POINTOPOINT)
                return false;

        ipv6h = ipv6_hdr(skb);

        if (unlikely(is_spoofed_6rd(tunnel, iph->saddr, &ipv6h->saddr))) {
                net_warn_ratelimited("Src spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
                                     &iph->saddr, &ipv6h->saddr,
                                     &iph->daddr, &ipv6h->daddr);
                return true;
        }

        if (likely(!is_spoofed_6rd(tunnel, iph->daddr, &ipv6h->daddr)))
                return false;

        if (only_dnatted(tunnel, &ipv6h->daddr))
                return false;

        net_warn_ratelimited("Dst spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
                             &iph->saddr, &ipv6h->saddr,
                             &iph->daddr, &ipv6h->daddr);
        return true;
}

static int ipip6_rcv(struct sk_buff *skb)
{
        const struct iphdr *iph = ip_hdr(skb);
        struct ip_tunnel *tunnel;
        int err;

        tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
                                     iph->saddr, iph->daddr);
        if (tunnel != NULL) {
                struct pcpu_sw_netstats *tstats;

                if (tunnel->parms.iph.protocol != IPPROTO_IPV6 &&
                    tunnel->parms.iph.protocol != 0)
                        goto out;

                skb->mac_header = skb->network_header;
                skb_reset_network_header(skb);
                IPCB(skb)->flags = 0;
                skb->protocol = htons(ETH_P_IPV6);

                if (packet_is_spoofed(skb, iph, tunnel)) {
                        tunnel->dev->stats.rx_errors++;
                        goto out;
                }

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

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

                tstats = this_cpu_ptr(tunnel->dev->tstats);
                u64_stats_update_begin(&tstats->syncp);
                tstats->rx_packets++;
                tstats->rx_bytes += skb->len;
                u64_stats_update_end(&tstats->syncp);

                netif_rx(skb);

                return 0;
        }

        /* no tunnel matched,  let upstream know, ipsec may handle it */
        return 1;
out:
        kfree_skb(skb);
        return 0;
}

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

static int ipip_rcv(struct sk_buff *skb)
{
        const struct iphdr *iph;
        struct ip_tunnel *tunnel;

        iph = ip_hdr(skb);
        tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
                                     iph->saddr, iph->daddr);
        if (tunnel != NULL) {
                if (tunnel->parms.iph.protocol != IPPROTO_IPIP &&
                    tunnel->parms.iph.protocol != 0)
                        goto drop;

                if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
                        goto drop;
                if (iptunnel_pull_header(skb, 0, tpi.proto))
                        goto drop;
                return ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error);
        }

        return 1;

drop:
        kfree_skb(skb);
        return 0;
}

/*
 * If the IPv6 address comes from 6rd / 6to4 (RFC 3056) addr space this function
 * stores the embedded IPv4 address in v4dst and returns true.
 */
static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
                      __be32 *v4dst)
{
#ifdef CONFIG_IPV6_SIT_6RD
        if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
                              tunnel->ip6rd.prefixlen)) {
                unsigned int pbw0, pbi0;
                int pbi1;
                u32 d;

                pbw0 = tunnel->ip6rd.prefixlen >> 5;
                pbi0 = tunnel->ip6rd.prefixlen & 0x1f;

                d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
                    tunnel->ip6rd.relay_prefixlen;

                pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
                if (pbi1 > 0)
                        d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
                             (32 - pbi1);

                *v4dst = tunnel->ip6rd.relay_prefix | htonl(d);
                return true;
        }
#else
        if (v6dst->s6_addr16[0] == htons(0x2002)) {
                /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
                memcpy(v4dst, &v6dst->s6_addr16[1], 4);
                return true;
        }
#endif
        return false;
}

static inline __be32 try_6rd(struct ip_tunnel *tunnel,
                             const struct in6_addr *v6dst)
{
        __be32 dst = 0;
        check_6rd(tunnel, v6dst, &dst);
        return dst;
}

/*
 *      This function assumes it is being called from dev_queue_xmit()
 *      and that skb is filled properly by that function.
 */

static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                                     struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        const struct iphdr  *tiph = &tunnel->parms.iph;
        const struct ipv6hdr *iph6 = ipv6_hdr(skb);
        u8     tos = tunnel->parms.iph.tos;
        __be16 df = tiph->frag_off;
        struct rtable *rt;              /* Route to the other host */
        struct net_device *tdev;        /* Device to other host */
        unsigned int max_headroom;      /* The extra header space needed */
        __be32 dst = tiph->daddr;
        struct flowi4 fl4;
        int    mtu;
        const struct in6_addr *addr6;
        int addr_type;
        u8 ttl;
        int err;
        u8 protocol = IPPROTO_IPV6;
        int t_hlen = tunnel->hlen + sizeof(struct iphdr);

        if (skb->protocol != htons(ETH_P_IPV6))
                goto tx_error;

        if (tos == 1)
                tos = ipv6_get_dsfield(iph6);

        /* ISATAP (RFC4214) - must come before 6to4 */
        if (dev->priv_flags & IFF_ISATAP) {
                struct neighbour *neigh = NULL;
                bool do_tx_error = false;

                if (skb_dst(skb))
                        neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);

                if (neigh == NULL) {
                        net_dbg_ratelimited("nexthop == NULL\n");
                        goto tx_error;
                }

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

                if ((addr_type & IPV6_ADDR_UNICAST) &&
                     ipv6_addr_is_isatap(addr6))
                        dst = addr6->s6_addr32[3];
                else
                        do_tx_error = true;

                neigh_release(neigh);
                if (do_tx_error)
                        goto tx_error;
        }

        if (!dst)
                dst = try_6rd(tunnel, &iph6->daddr);

        if (!dst) {
                struct neighbour *neigh = NULL;
                bool do_tx_error = false;

                if (skb_dst(skb))
                        neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);

                if (neigh == NULL) {
                        net_dbg_ratelimited("nexthop == NULL\n");
                        goto tx_error;
                }

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

                if (addr_type == IPV6_ADDR_ANY) {
                        addr6 = &ipv6_hdr(skb)->daddr;
                        addr_type = ipv6_addr_type(addr6);
                }

                if ((addr_type & IPV6_ADDR_COMPATv4) != 0)
                        dst = addr6->s6_addr32[3];
                else
                        do_tx_error = true;

                neigh_release(neigh);
                if (do_tx_error)
                        goto tx_error;
        }

        rt = ip_route_output_ports(tunnel->net, &fl4, NULL,
                                   dst, tiph->saddr,
                                   0, 0,
                                   IPPROTO_IPV6, RT_TOS(tos),
                                   tunnel->parms.link);
        if (IS_ERR(rt)) {
                dev->stats.tx_carrier_errors++;
                goto tx_error_icmp;
        }
        if (rt->rt_type != RTN_UNICAST) {
                ip_rt_put(rt);
                dev->stats.tx_carrier_errors++;
                goto tx_error_icmp;
        }
        tdev = rt->dst.dev;

        if (tdev == dev) {
                ip_rt_put(rt);
                dev->stats.collisions++;
                goto tx_error;
        }

        skb = iptunnel_handle_offloads(skb, false, SKB_GSO_SIT);
        if (IS_ERR(skb)) {
                ip_rt_put(rt);
                goto out;
        }

        if (df) {
                mtu = dst_mtu(&rt->dst) - t_hlen;

                if (mtu < 68) {
                        dev->stats.collisions++;
                        ip_rt_put(rt);
                        goto tx_error;
                }

                if (mtu < IPV6_MIN_MTU) {
                        mtu = IPV6_MIN_MTU;
                        df = 0;
                }

                if (tunnel->parms.iph.daddr && skb_dst(skb))
                        skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);

                if (skb->len > mtu && !skb_is_gso(skb)) {
                        icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
                        ip_rt_put(rt);
                        goto tx_error;
                }
        }

        if (tunnel->err_count > 0) {
                if (time_before(jiffies,
                                tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
                        tunnel->err_count--;
                        dst_link_failure(skb);
                } else
                        tunnel->err_count = 0;
        }

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

        if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
            (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
                struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
                if (!new_skb) {
                        ip_rt_put(rt);
                        dev->stats.tx_dropped++;
                        kfree_skb(skb);
                        return NETDEV_TX_OK;
                }
                if (skb->sk)
                        skb_set_owner_w(new_skb, skb->sk);
                dev_kfree_skb(skb);
                skb = new_skb;
                iph6 = ipv6_hdr(skb);
        }
        ttl = tiph->ttl;
        if (ttl == 0)
                ttl = iph6->hop_limit;
        tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));

        if (ip_tunnel_encap(skb, tunnel, &protocol, &fl4) < 0) {
                ip_rt_put(rt);
                goto tx_error;
        }

        err = iptunnel_xmit(skb->sk, rt, skb, fl4.saddr, fl4.daddr,
                            protocol, tos, ttl, df,
                            !net_eq(tunnel->net, dev_net(dev)));
        iptunnel_xmit_stats(err, &dev->stats, dev->tstats);
        return NETDEV_TX_OK;

tx_error_icmp:
        dst_link_failure(skb);
tx_error:
        kfree_skb(skb);
out:
        dev->stats.tx_errors++;
        return NETDEV_TX_OK;
}

static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        const struct iphdr  *tiph = &tunnel->parms.iph;

        skb = iptunnel_handle_offloads(skb, false, SKB_GSO_IPIP);
        if (IS_ERR(skb))
                goto out;

        ip_tunnel_xmit(skb, dev, tiph, IPPROTO_IPIP);
        return NETDEV_TX_OK;
out:
        dev->stats.tx_errors++;
        return NETDEV_TX_OK;
}

static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
                                   struct net_device *dev)
{
        switch (skb->protocol) {
        case htons(ETH_P_IP):
                ipip_tunnel_xmit(skb, dev);
                break;
        case htons(ETH_P_IPV6):
                ipip6_tunnel_xmit(skb, dev);
                break;
        default:
                goto tx_err;
        }

        return NETDEV_TX_OK;

tx_err:
        dev->stats.tx_errors++;
        kfree_skb(skb);
        return NETDEV_TX_OK;

}

static void ipip6_tunnel_bind_dev(struct net_device *dev)
{
        struct net_device *tdev = NULL;
        struct ip_tunnel *tunnel;
        const struct iphdr *iph;
        struct flowi4 fl4;

        tunnel = netdev_priv(dev);
        iph = &tunnel->parms.iph;

        if (iph->daddr) {
                struct rtable *rt = ip_route_output_ports(tunnel->net, &fl4,
                                                          NULL,
                                                          iph->daddr, iph->saddr,
                                                          0, 0,
                                                          IPPROTO_IPV6,
                                                          RT_TOS(iph->tos),
                                                          tunnel->parms.link);

                if (!IS_ERR(rt)) {
                        tdev = rt->dst.dev;
                        ip_rt_put(rt);
                }
                dev->flags |= IFF_POINTOPOINT;
        }

        if (!tdev && tunnel->parms.link)
                tdev = __dev_get_by_index(tunnel->net, tunnel->parms.link);

        if (tdev) {
                int t_hlen = tunnel->hlen + sizeof(struct iphdr);

                dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
                dev->mtu = tdev->mtu - t_hlen;
                if (dev->mtu < IPV6_MIN_MTU)
                        dev->mtu = IPV6_MIN_MTU;
        }
        dev->iflink = tunnel->parms.link;
}

static void ipip6_tunnel_update(struct ip_tunnel *t, struct ip_tunnel_parm *p)
{
        struct net *net = t->net;
        struct sit_net *sitn = net_generic(net, sit_net_id);

        ipip6_tunnel_unlink(sitn, t);
        synchronize_net();
        t->parms.iph.saddr = p->iph.saddr;
        t->parms.iph.daddr = p->iph.daddr;
        memcpy(t->dev->dev_addr, &p->iph.saddr, 4);
        memcpy(t->dev->broadcast, &p->iph.daddr, 4);
        ipip6_tunnel_link(sitn, t);
        t->parms.iph.ttl = p->iph.ttl;
        t->parms.iph.tos = p->iph.tos;
        if (t->parms.link != p->link) {
                t->parms.link = p->link;
                ipip6_tunnel_bind_dev(t->dev);
        }
        ip_tunnel_dst_reset_all(t);
        netdev_state_change(t->dev);
}

#ifdef CONFIG_IPV6_SIT_6RD
static int ipip6_tunnel_update_6rd(struct ip_tunnel *t,
                                   struct ip_tunnel_6rd *ip6rd)
{
        struct in6_addr prefix;
        __be32 relay_prefix;

        if (ip6rd->relay_prefixlen > 32 ||
            ip6rd->prefixlen + (32 - ip6rd->relay_prefixlen) > 64)
                return -EINVAL;

        ipv6_addr_prefix(&prefix, &ip6rd->prefix, ip6rd->prefixlen);
        if (!ipv6_addr_equal(&prefix, &ip6rd->prefix))
                return -EINVAL;
        if (ip6rd->relay_prefixlen)
                relay_prefix = ip6rd->relay_prefix &
                               htonl(0xffffffffUL <<
                                     (32 - ip6rd->relay_prefixlen));
        else
                relay_prefix = 0;
        if (relay_prefix != ip6rd->relay_prefix)
                return -EINVAL;

        t->ip6rd.prefix = prefix;
        t->ip6rd.relay_prefix = relay_prefix;
        t->ip6rd.prefixlen = ip6rd->prefixlen;
        t->ip6rd.relay_prefixlen = ip6rd->relay_prefixlen;
        ip_tunnel_dst_reset_all(t);
        netdev_state_change(t->dev);
        return 0;
}
#endif

static int
ipip6_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        int err = 0;
        struct ip_tunnel_parm p;
        struct ip_tunnel_prl prl;
        struct ip_tunnel *t = netdev_priv(dev);
        struct net *net = t->net;
        struct sit_net *sitn = net_generic(net, sit_net_id);
#ifdef CONFIG_IPV6_SIT_6RD
        struct ip_tunnel_6rd ip6rd;
#endif

        switch (cmd) {
        case SIOCGETTUNNEL:
#ifdef CONFIG_IPV6_SIT_6RD
        case SIOCGET6RD:
#endif
                if (dev == sitn->fb_tunnel_dev) {
                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
                                err = -EFAULT;
                                break;
                        }
                        t = ipip6_tunnel_locate(net, &p, 0);
                        if (t == NULL)
                                t = netdev_priv(dev);
                }

                err = -EFAULT;
                if (cmd == SIOCGETTUNNEL) {
                        memcpy(&p, &t->parms, sizeof(p));
                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
                                         sizeof(p)))
                                goto done;
#ifdef CONFIG_IPV6_SIT_6RD
                } else {
                        ip6rd.prefix = t->ip6rd.prefix;
                        ip6rd.relay_prefix = t->ip6rd.relay_prefix;
                        ip6rd.prefixlen = t->ip6rd.prefixlen;
                        ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
                                         sizeof(ip6rd)))
                                goto done;
#endif
                }
                err = 0;
                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, ifr->ifr_ifru.ifru_data, sizeof(p)))
                        goto done;

                err = -EINVAL;
                if (p.iph.protocol != IPPROTO_IPV6 &&
                    p.iph.protocol != IPPROTO_IPIP &&
                    p.iph.protocol != 0)
                        goto done;
                if (p.iph.version != 4 ||
                    p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
                        goto done;
                if (p.iph.ttl)
                        p.iph.frag_off |= htons(IP_DF);

                t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);

                if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
                        if (t != NULL) {
                                if (t->dev != dev) {
                                        err = -EEXIST;
                                        break;
                                }
                        } else {
                                if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
                                    (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
                                        err = -EINVAL;
                                        break;
                                }
                                t = netdev_priv(dev);
                        }

                        ipip6_tunnel_update(t, &p);
                }

                if (t) {
                        err = 0;
                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, 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 == sitn->fb_tunnel_dev) {
                        err = -EFAULT;
                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
                                goto done;
                        err = -ENOENT;
                        if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
                                goto done;
                        err = -EPERM;
                        if (t == netdev_priv(sitn->fb_tunnel_dev))
                                goto done;
                        dev = t->dev;
                }
                unregister_netdevice(dev);
                err = 0;
                break;

        case SIOCGETPRL:
                err = -EINVAL;
                if (dev == sitn->fb_tunnel_dev)
                        goto done;
                err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
                break;

        case SIOCADDPRL:
        case SIOCDELPRL:
        case SIOCCHGPRL:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        goto done;
                err = -EINVAL;
                if (dev == sitn->fb_tunnel_dev)
                        goto done;
                err = -EFAULT;
                if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
                        goto done;

                switch (cmd) {
                case SIOCDELPRL:
                        err = ipip6_tunnel_del_prl(t, &prl);
                        break;
                case SIOCADDPRL:
                case SIOCCHGPRL:
                        err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
                        break;
                }
                ip_tunnel_dst_reset_all(t);
                netdev_state_change(dev);
                break;

#ifdef CONFIG_IPV6_SIT_6RD
        case SIOCADD6RD:
        case SIOCCHG6RD:
        case SIOCDEL6RD:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        goto done;

                err = -EFAULT;
                if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
                                   sizeof(ip6rd)))
                        goto done;

                if (cmd != SIOCDEL6RD) {
                        err = ipip6_tunnel_update_6rd(t, &ip6rd);
                        if (err < 0)
                                goto done;
                } else
                        ipip6_tunnel_clone_6rd(dev, sitn);

                err = 0;
                break;
#endif

        default:
                err = -EINVAL;
        }

done:
        return err;
}

static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        int t_hlen = tunnel->hlen + sizeof(struct iphdr);

        if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - t_hlen)
                return -EINVAL;
        dev->mtu = new_mtu;
        return 0;
}

static const struct net_device_ops ipip6_netdev_ops = {
        .ndo_uninit     = ipip6_tunnel_uninit,
        .ndo_start_xmit = sit_tunnel_xmit,
        .ndo_do_ioctl   = ipip6_tunnel_ioctl,
        .ndo_change_mtu = ipip6_tunnel_change_mtu,
        .ndo_get_stats64 = ip_tunnel_get_stats64,
};

static void ipip6_dev_free(struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);

        free_percpu(tunnel->dst_cache);
        free_percpu(dev->tstats);
        free_netdev(dev);
}

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

static void ipip6_tunnel_setup(struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        int t_hlen = tunnel->hlen + sizeof(struct iphdr);

        dev->netdev_ops         = &ipip6_netdev_ops;
        dev->destructor         = ipip6_dev_free;

        dev->type               = ARPHRD_SIT;
        dev->hard_header_len    = LL_MAX_HEADER + t_hlen;
        dev->mtu                = ETH_DATA_LEN - t_hlen;
        dev->flags              = IFF_NOARP;
        dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
        dev->iflink             = 0;
        dev->addr_len           = 4;
        dev->features           |= NETIF_F_LLTX;
        dev->features           |= SIT_FEATURES;
        dev->hw_features        |= SIT_FEATURES;
}

static int ipip6_tunnel_init(struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);

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

        memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
        memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);

        ipip6_tunnel_bind_dev(dev);
        dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
        if (!dev->tstats)
                return -ENOMEM;

        tunnel->dst_cache = alloc_percpu(struct ip_tunnel_dst);
        if (!tunnel->dst_cache) {
                free_percpu(dev->tstats);
                return -ENOMEM;
        }

        return 0;
}

static int __net_init ipip6_fb_tunnel_init(struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        struct iphdr *iph = &tunnel->parms.iph;
        struct net *net = dev_net(dev);
        struct sit_net *sitn = net_generic(net, sit_net_id);

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

        iph->version            = 4;
        iph->protocol           = IPPROTO_IPV6;
        iph->ihl                = 5;
        iph->ttl                = 64;

        dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
        if (!dev->tstats)
                return -ENOMEM;

        tunnel->dst_cache = alloc_percpu(struct ip_tunnel_dst);
        if (!tunnel->dst_cache) {
                free_percpu(dev->tstats);
                return -ENOMEM;
        }

        dev_hold(dev);
        rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
        return 0;
}

static int ipip6_validate(struct nlattr *tb[], struct nlattr *data[])
{
        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 ipip6_netlink_parms(struct nlattr *data[],
                                struct ip_tunnel_parm *parms)
{
        memset(parms, 0, sizeof(*parms));

        parms->iph.version = 4;
        parms->iph.protocol = IPPROTO_IPV6;
        parms->iph.ihl = 5;
        parms->iph.ttl = 64;

        if (!data)
                return;

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

        if (data[IFLA_IPTUN_LOCAL])
                parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);

        if (data[IFLA_IPTUN_REMOTE])
                parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);

        if (data[IFLA_IPTUN_TTL]) {
                parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
                if (parms->iph.ttl)
                        parms->iph.frag_off = htons(IP_DF);
        }

        if (data[IFLA_IPTUN_TOS])
                parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);

        if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
                parms->iph.frag_off = htons(IP_DF);

        if (data[IFLA_IPTUN_FLAGS])
                parms->i_flags = nla_get_be16(data[IFLA_IPTUN_FLAGS]);

        if (data[IFLA_IPTUN_PROTO])
                parms->iph.protocol = nla_get_u8(data[IFLA_IPTUN_PROTO]);

}

/* This function returns true when ENCAP attributes are present in the nl msg */
static bool ipip6_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_IPTUN_ENCAP_TYPE]) {
                ret = true;
                ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]);
        }

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

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

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

        return ret;
}

#ifdef CONFIG_IPV6_SIT_6RD
/* This function returns true when 6RD attributes are present in the nl msg */
static bool ipip6_netlink_6rd_parms(struct nlattr *data[],
                                    struct ip_tunnel_6rd *ip6rd)
{
        bool ret = false;
        memset(ip6rd, 0, sizeof(*ip6rd));

        if (!data)
                return ret;

        if (data[IFLA_IPTUN_6RD_PREFIX]) {
                ret = true;
                nla_memcpy(&ip6rd->prefix, data[IFLA_IPTUN_6RD_PREFIX],
                           sizeof(struct in6_addr));
        }

        if (data[IFLA_IPTUN_6RD_RELAY_PREFIX]) {
                ret = true;
                ip6rd->relay_prefix =
                        nla_get_be32(data[IFLA_IPTUN_6RD_RELAY_PREFIX]);
        }

        if (data[IFLA_IPTUN_6RD_PREFIXLEN]) {
                ret = true;
                ip6rd->prefixlen = nla_get_u16(data[IFLA_IPTUN_6RD_PREFIXLEN]);
        }

        if (data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]) {
                ret = true;
                ip6rd->relay_prefixlen =
                        nla_get_u16(data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]);
        }

        return ret;
}
#endif

static int ipip6_newlink(struct net *src_net, struct net_device *dev,
                         struct nlattr *tb[], struct nlattr *data[])
{
        struct net *net = dev_net(dev);
        struct ip_tunnel *nt;
        struct ip_tunnel_encap ipencap;
#ifdef CONFIG_IPV6_SIT_6RD
        struct ip_tunnel_6rd ip6rd;
#endif
        int err;

        nt = netdev_priv(dev);

        if (ipip6_netlink_encap_parms(data, &ipencap)) {
                err = ip_tunnel_encap_setup(nt, &ipencap);
                if (err < 0)
                        return err;
        }

        ipip6_netlink_parms(data, &nt->parms);

        if (ipip6_tunnel_locate(net, &nt->parms, 0))
                return -EEXIST;

        err = ipip6_tunnel_create(dev);
        if (err < 0)
                return err;

#ifdef CONFIG_IPV6_SIT_6RD
        if (ipip6_netlink_6rd_parms(data, &ip6rd))
                err = ipip6_tunnel_update_6rd(nt, &ip6rd);
#endif

        return err;
}

static int ipip6_changelink(struct net_device *dev, struct nlattr *tb[],
                          struct nlattr *data[])
{
        struct ip_tunnel *t = netdev_priv(dev);
        struct ip_tunnel_parm p;
        struct ip_tunnel_encap ipencap;
        struct net *net = t->net;
        struct sit_net *sitn = net_generic(net, sit_net_id);
#ifdef CONFIG_IPV6_SIT_6RD
        struct ip_tunnel_6rd ip6rd;
#endif
        int err;

        if (dev == sitn->fb_tunnel_dev)
                return -EINVAL;

        if (ipip6_netlink_encap_parms(data, &ipencap)) {
                err = ip_tunnel_encap_setup(t, &ipencap);
                if (err < 0)
                        return err;
        }

        ipip6_netlink_parms(data, &p);

        if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
            (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
                return -EINVAL;

        t = ipip6_tunnel_locate(net, &p, 0);

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

        ipip6_tunnel_update(t, &p);

#ifdef CONFIG_IPV6_SIT_6RD
        if (ipip6_netlink_6rd_parms(data, &ip6rd))
                return ipip6_tunnel_update_6rd(t, &ip6rd);
#endif

        return 0;
}

static size_t ipip6_get_size(const struct net_device *dev)
{
        return
                /* IFLA_IPTUN_LINK */
                nla_total_size(4) +
                /* IFLA_IPTUN_LOCAL */
                nla_total_size(4) +
                /* IFLA_IPTUN_REMOTE */
                nla_total_size(4) +
                /* IFLA_IPTUN_TTL */
                nla_total_size(1) +
                /* IFLA_IPTUN_TOS */
                nla_total_size(1) +
                /* IFLA_IPTUN_PMTUDISC */
                nla_total_size(1) +
                /* IFLA_IPTUN_FLAGS */
                nla_total_size(2) +
                /* IFLA_IPTUN_PROTO */
                nla_total_size(1) +
#ifdef CONFIG_IPV6_SIT_6RD
                /* IFLA_IPTUN_6RD_PREFIX */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_IPTUN_6RD_RELAY_PREFIX */
                nla_total_size(4) +
                /* IFLA_IPTUN_6RD_PREFIXLEN */
                nla_total_size(2) +
                /* IFLA_IPTUN_6RD_RELAY_PREFIXLEN */
                nla_total_size(2) +
#endif
                /* 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) +
                0;
}

static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
        struct ip_tunnel *tunnel = netdev_priv(dev);
        struct ip_tunnel_parm *parm = &tunnel->parms;

        if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
            nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
            nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
            nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
            nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
            nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
                       !!(parm->iph.frag_off & htons(IP_DF))) ||
            nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->iph.protocol) ||
            nla_put_be16(skb, IFLA_IPTUN_FLAGS, parm->i_flags))
                goto nla_put_failure;

#ifdef CONFIG_IPV6_SIT_6RD
        if (nla_put(skb, IFLA_IPTUN_6RD_PREFIX, sizeof(struct in6_addr),
                    &tunnel->ip6rd.prefix) ||
            nla_put_be32(skb, IFLA_IPTUN_6RD_RELAY_PREFIX,
                         tunnel->ip6rd.relay_prefix) ||
            nla_put_u16(skb, IFLA_IPTUN_6RD_PREFIXLEN,
                        tunnel->ip6rd.prefixlen) ||
            nla_put_u16(skb, IFLA_IPTUN_6RD_RELAY_PREFIXLEN,
                        tunnel->ip6rd.relay_prefixlen))
                goto nla_put_failure;
#endif

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

        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
        [IFLA_IPTUN_LINK]               = { .type = NLA_U32 },
        [IFLA_IPTUN_LOCAL]              = { .type = NLA_U32 },
        [IFLA_IPTUN_REMOTE]             = { .type = NLA_U32 },
        [IFLA_IPTUN_TTL]                = { .type = NLA_U8 },
        [IFLA_IPTUN_TOS]                = { .type = NLA_U8 },
        [IFLA_IPTUN_PMTUDISC]           = { .type = NLA_U8 },
        [IFLA_IPTUN_FLAGS]              = { .type = NLA_U16 },
        [IFLA_IPTUN_PROTO]              = { .type = NLA_U8 },
#ifdef CONFIG_IPV6_SIT_6RD
        [IFLA_IPTUN_6RD_PREFIX]         = { .len = sizeof(struct in6_addr) },
        [IFLA_IPTUN_6RD_RELAY_PREFIX]   = { .type = NLA_U32 },
        [IFLA_IPTUN_6RD_PREFIXLEN]      = { .type = NLA_U16 },
        [IFLA_IPTUN_6RD_RELAY_PREFIXLEN] = { .type = NLA_U16 },
#endif
        [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 },
};

static void ipip6_dellink(struct net_device *dev, struct list_head *head)
{
        struct net *net = dev_net(dev);
        struct sit_net *sitn = net_generic(net, sit_net_id);

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

static struct rtnl_link_ops sit_link_ops __read_mostly = {
        .kind           = "sit",
        .maxtype        = IFLA_IPTUN_MAX,
        .policy         = ipip6_policy,
        .priv_size      = sizeof(struct ip_tunnel),
        .setup          = ipip6_tunnel_setup,
        .validate       = ipip6_validate,
        .newlink        = ipip6_newlink,
        .changelink     = ipip6_changelink,
        .get_size       = ipip6_get_size,
        .fill_info      = ipip6_fill_info,
        .dellink        = ipip6_dellink,
};

static struct xfrm_tunnel sit_handler __read_mostly = {
        .handler        =       ipip6_rcv,
        .err_handler    =       ipip6_err,
        .priority       =       1,
};

static struct xfrm_tunnel ipip_handler __read_mostly = {
        .handler        =       ipip_rcv,
        .err_handler    =       ipip6_err,
        .priority       =       2,
};

static void __net_exit sit_destroy_tunnels(struct net *net,
                                           struct list_head *head)
{
        struct sit_net *sitn = net_generic(net, sit_net_id);
        struct net_device *dev, *aux;
        int prio;

        for_each_netdev_safe(net, dev, aux)
                if (dev->rtnl_link_ops == &sit_link_ops)
                        unregister_netdevice_queue(dev, head);

        for (prio = 1; prio < 4; prio++) {
                int h;
                for (h = 0; h < HASH_SIZE; h++) {
                        struct ip_tunnel *t;

                        t = rtnl_dereference(sitn->tunnels[prio][h]);
                        while (t != NULL) {
                                /* 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_dereference(t->next);
                        }
                }
        }
}

static int __net_init sit_init_net(struct net *net)
{
        struct sit_net *sitn = net_generic(net, sit_net_id);
        struct ip_tunnel *t;
        int err;

        sitn->tunnels[0] = sitn->tunnels_wc;
        sitn->tunnels[1] = sitn->tunnels_l;
        sitn->tunnels[2] = sitn->tunnels_r;
        sitn->tunnels[3] = sitn->tunnels_r_l;

        sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
                                           NET_NAME_UNKNOWN,
                                           ipip6_tunnel_setup);
        if (!sitn->fb_tunnel_dev) {
                err = -ENOMEM;
                goto err_alloc_dev;
        }
        dev_net_set(sitn->fb_tunnel_dev, net);
        sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;
        /* FB netdevice is special: we have one, and only one per netns.
         * Allowing to move it to another netns is clearly unsafe.
         */
        sitn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;

        err = ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
        if (err)
                goto err_dev_free;

        ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);

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

        t = netdev_priv(sitn->fb_tunnel_dev);

        strcpy(t->parms.name, sitn->fb_tunnel_dev->name);
        return 0;

err_reg_dev:
        dev_put(sitn->fb_tunnel_dev);
err_dev_free:
        ipip6_dev_free(sitn->fb_tunnel_dev);
err_alloc_dev:
        return err;
}

static void __net_exit sit_exit_net(struct net *net)
{
        LIST_HEAD(list);

        rtnl_lock();
        sit_destroy_tunnels(net, &list);
        unregister_netdevice_many(&list);
        rtnl_unlock();
}

static struct pernet_operations sit_net_ops = {
        .init = sit_init_net,
        .exit = sit_exit_net,
        .id   = &sit_net_id,
        .size = sizeof(struct sit_net),
};

static void __exit sit_cleanup(void)
{
        rtnl_link_unregister(&sit_link_ops);
        xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
        xfrm4_tunnel_deregister(&ipip_handler, AF_INET);

        unregister_pernet_device(&sit_net_ops);
        rcu_barrier(); /* Wait for completion of call_rcu()'s */
}

static int __init sit_init(void)
{
        int err;

        pr_info("IPv6 over IPv4 tunneling driver\n");

        err = register_pernet_device(&sit_net_ops);
        if (err < 0)
                return err;
        err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
        if (err < 0) {
                pr_info("%s: can't register ip6ip4\n", __func__);
                goto xfrm_tunnel_failed;
        }
        err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
        if (err < 0) {
                pr_info("%s: can't register ip4ip4\n", __func__);
                goto xfrm_tunnel4_failed;
        }
        err = rtnl_link_register(&sit_link_ops);
        if (err < 0)
                goto rtnl_link_failed;

out:
        return err;

rtnl_link_failed:
        xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
xfrm_tunnel4_failed:
        xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
xfrm_tunnel_failed:
        unregister_pernet_device(&sit_net_ops);
        goto out;
}

module_init(sit_init);
module_exit(sit_cleanup);
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("sit");
MODULE_ALIAS_NETDEV("sit0");