/*
 *      IPv6 virtual tunneling interface
 *
 *      Copyright (C) 2013 secunet Security Networks AG
 *
 *      Author:
 *      Steffen Klassert <steffen.klassert@secunet.com>
 *
 *      Based on:
 *      net/ipv6/ip6_tunnel.c
 *
 *      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.
 */

#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/if_tunnel.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/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/net_namespace.h>
#include <net/netns/generic.h>

#define HASH_SIZE_SHIFT  5
#define HASH_SIZE (1 << HASH_SIZE_SHIFT)

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, HASH_SIZE_SHIFT);
}

static int vti6_dev_init(struct net_device *dev);
static void vti6_dev_setup(struct net_device *dev);
static struct rtnl_link_ops vti6_link_ops __read_mostly;

static int vti6_net_id __read_mostly;
struct vti6_net {
        /* the vti6 tunnel fallback device */
        struct net_device *fb_tnl_dev;
        /* lists for storing tunnels in use */
        struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];
        struct ip6_tnl __rcu *tnls_wc[1];
        struct ip6_tnl __rcu **tnls[2];
};

#define for_each_vti6_tunnel_rcu(start) \
        for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))

/**
 * vti6_tnl_lookup - fetch tunnel matching the end-point addresses
 *   @net: network namespace
 *   @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 *
vti6_tnl_lookup(struct net *net, const struct in6_addr *remote,
                const struct in6_addr *local)
{
        unsigned int hash = HASH(remote, local);
        struct ip6_tnl *t;
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);

        for_each_vti6_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))
                        return t;
        }
        t = rcu_dereference(ip6n->tnls_wc[0]);
        if (t && (t->dev->flags & IFF_UP))
                return t;

        return NULL;
}

/**
 * vti6_tnl_bucket - get head of list matching given tunnel parameters
 *   @p: parameters containing tunnel end-points
 *
 * Description:
 *   vti6_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 **
vti6_tnl_bucket(struct vti6_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];
}

static void
vti6_tnl_link(struct vti6_net *ip6n, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp = vti6_tnl_bucket(ip6n, &t->parms);

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

static void
vti6_tnl_unlink(struct vti6_net *ip6n, struct ip6_tnl *t)
{
        struct ip6_tnl __rcu **tp;
        struct ip6_tnl *iter;

        for (tp = vti6_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 vti6_dev_free(struct net_device *dev)
{
        free_percpu(dev->tstats);
        free_netdev(dev);
}

static int vti6_tnl_create2(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = dev_net(dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);
        int err;

        err = vti6_dev_init(dev);
        if (err < 0)
                goto out;

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

        strcpy(t->parms.name, dev->name);
        dev->rtnl_link_ops = &vti6_link_ops;

        dev_hold(dev);
        vti6_tnl_link(ip6n, t);

        return 0;

out:
        return err;
}

static struct ip6_tnl *vti6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
{
        struct net_device *dev;
        struct ip6_tnl *t;
        char name[IFNAMSIZ];
        int err;

        if (p->name[0])
                strlcpy(name, p->name, IFNAMSIZ);
        else
                sprintf(name, "ip6_vti%%d");

        dev = alloc_netdev(sizeof(*t), name, vti6_dev_setup);
        if (dev == NULL)
                goto failed;

        dev_net_set(dev, net);

        t = netdev_priv(dev);
        t->parms = *p;
        t->net = dev_net(dev);

        err = vti6_tnl_create2(dev);
        if (err < 0)
                goto failed_free;

        return t;

failed_free:
        vti6_dev_free(dev);
failed:
        return NULL;
}

/**
 * vti6_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:
 *   vti6_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 NULL
 **/
static struct ip6_tnl *vti6_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 vti6_net *ip6n = net_generic(net, vti6_net_id);

        for (tp = vti6_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))
                        return t;
        }
        if (!create)
                return NULL;
        return vti6_tnl_create(net, p);
}

/**
 * vti6_dev_uninit - tunnel device uninitializer
 *   @dev: the device to be destroyed
 *
 * Description:
 *   vti6_dev_uninit() removes tunnel from its list
 **/
static void vti6_dev_uninit(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = dev_net(dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);

        if (dev == ip6n->fb_tnl_dev)
                RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
        else
                vti6_tnl_unlink(ip6n, t);
        ip6_tnl_dst_reset(t);
        dev_put(dev);
}

static int vti6_rcv(struct sk_buff *skb)
{
        struct ip6_tnl *t;
        const struct ipv6hdr *ipv6h = ipv6_hdr(skb);

        rcu_read_lock();

        if ((t = vti6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr,
                                 &ipv6h->daddr)) != NULL) {
                struct pcpu_tstats *tstats;

                if (t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) {
                        rcu_read_unlock();
                        goto discard;
                }

                if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
                        rcu_read_unlock();
                        return 0;
                }

                if (!ip6_tnl_rcv_ctl(t, &ipv6h->daddr, &ipv6h->saddr)) {
                        t->dev->stats.rx_dropped++;
                        rcu_read_unlock();
                        goto discard;
                }

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

                skb->mark = 0;
                secpath_reset(skb);
                skb->dev = t->dev;

                rcu_read_unlock();
                return 0;
        }
        rcu_read_unlock();
        return 1;

discard:
        kfree_skb(skb);
        return 0;
}

/**
 * vti6_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
vti6_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)
{
        return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
}

/**
 * vti6_xmit - send a packet
 *   @skb: the outgoing socket buffer
 *   @dev: the outgoing tunnel device
 **/
static int vti6_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct net *net = dev_net(dev);
        struct ip6_tnl *t = netdev_priv(dev);
        struct net_device_stats *stats = &t->dev->stats;
        struct dst_entry *dst = NULL, *ndst = NULL;
        struct flowi6 fl6;
        struct ipv6hdr *ipv6h = ipv6_hdr(skb);
        struct net_device *tdev;
        int err = -1;

        if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||
            !ip6_tnl_xmit_ctl(t) || vti6_addr_conflict(t, ipv6h))
                return err;

        dst = ip6_tnl_dst_check(t);
        if (!dst) {
                memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));

                ndst = ip6_route_output(net, NULL, &fl6);

                if (ndst->error)
                        goto tx_err_link_failure;
                ndst = xfrm_lookup(net, ndst, flowi6_to_flowi(&fl6), NULL, 0);
                if (IS_ERR(ndst)) {
                        err = PTR_ERR(ndst);
                        ndst = NULL;
                        goto tx_err_link_failure;
                }
                dst = ndst;
        }

        if (!dst->xfrm || dst->xfrm->props.mode != XFRM_MODE_TUNNEL)
                goto tx_err_link_failure;

        tdev = dst->dev;

        if (tdev == dev) {
                stats->collisions++;
                net_warn_ratelimited("%s: Local routing loop detected!\n",
                                     t->parms.name);
                goto tx_err_dst_release;
        }


        skb_dst_drop(skb);
        skb_dst_set_noref(skb, dst);

        ip6tunnel_xmit(skb, dev);
        if (ndst) {
                dev->mtu = dst_mtu(ndst);
                ip6_tnl_dst_store(t, ndst);
        }

        return 0;
tx_err_link_failure:
        stats->tx_carrier_errors++;
        dst_link_failure(skb);
tx_err_dst_release:
        dst_release(ndst);
        return err;
}

static netdev_tx_t
vti6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net_device_stats *stats = &t->dev->stats;
        int ret;

        switch (skb->protocol) {
        case htons(ETH_P_IPV6):
                ret = vti6_xmit(skb, dev);
                break;
        default:
                goto tx_err;
        }

        if (ret < 0)
                goto tx_err;

        return NETDEV_TX_OK;

tx_err:
        stats->tx_errors++;
        stats->tx_dropped++;
        kfree_skb(skb);
        return NETDEV_TX_OK;
}

static void vti6_link_config(struct ip6_tnl *t)
{
        struct dst_entry *dst;
        struct net_device *dev = t->dev;
        struct __ip6_tnl_parm *p = &t->parms;
        struct flowi6 *fl6 = &t->fl.u.ip6;

        memcpy(dev->dev_addr, &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->flowi6_mark = be32_to_cpu(p->i_key);
        fl6->flowi6_proto = p->proto;
        fl6->flowlabel = 0;

        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;

        dev->iflink = p->link;

        if (p->flags & IP6_TNL_F_CAP_XMIT) {

                dst = ip6_route_output(dev_net(dev), NULL, fl6);
                if (dst->error)
                        return;

                dst = xfrm_lookup(dev_net(dev), dst, flowi6_to_flowi(fl6),
                                  NULL, 0);
                if (IS_ERR(dst))
                        return;

                if (dst->dev) {
                        dev->hard_header_len = dst->dev->hard_header_len;

                        dev->mtu = dst_mtu(dst);

                        if (dev->mtu < IPV6_MIN_MTU)
                                dev->mtu = IPV6_MIN_MTU;
                }
                dst_release(dst);
        }
}

/**
 * vti6_tnl_change - update the tunnel parameters
 *   @t: tunnel to be changed
 *   @p: tunnel configuration parameters
 *
 * Description:
 *   vti6_tnl_change() updates the tunnel parameters
 **/
static int
vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
{
        t->parms.laddr = p->laddr;
        t->parms.raddr = p->raddr;
        t->parms.link = p->link;
        t->parms.i_key = p->i_key;
        t->parms.o_key = p->o_key;
        t->parms.proto = p->proto;
        ip6_tnl_dst_reset(t);
        vti6_link_config(t);
        return 0;
}

static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
{
        struct net *net = dev_net(t->dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);
        int err;

        vti6_tnl_unlink(ip6n, t);
        synchronize_net();
        err = vti6_tnl_change(t, p);
        vti6_tnl_link(ip6n, t);
        netdev_state_change(t->dev);
        return err;
}

static void
vti6_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm2 *u)
{
        p->laddr = u->laddr;
        p->raddr = u->raddr;
        p->link = u->link;
        p->i_key = u->i_key;
        p->o_key = u->o_key;
        p->proto = u->proto;

        memcpy(p->name, u->name, sizeof(u->name));
}

static void
vti6_parm_to_user(struct ip6_tnl_parm2 *u, const struct __ip6_tnl_parm *p)
{
        u->laddr = p->laddr;
        u->raddr = p->raddr;
        u->link = p->link;
        u->i_key = p->i_key;
        u->o_key = p->o_key;
        u->proto = p->proto;

        memcpy(u->name, p->name, sizeof(u->name));
}

/**
 * vti6_tnl_ioctl - configure vti6 tunnels from userspace
 *   @dev: virtual device associated with tunnel
 *   @ifr: parameters passed from userspace
 *   @cmd: command to be performed
 *
 * Description:
 *   vti6_ioctl() is used for managing vti6 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 "ip6_vti0", 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
vti6_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        int err = 0;
        struct ip6_tnl_parm2 p;
        struct __ip6_tnl_parm p1;
        struct ip6_tnl *t = NULL;
        struct net *net = dev_net(dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);

        switch (cmd) {
        case SIOCGETTUNNEL:
                if (dev == ip6n->fb_tnl_dev) {
                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
                                err = -EFAULT;
                                break;
                        }
                        vti6_parm_from_user(&p1, &p);
                        t = vti6_locate(net, &p1, 0);
                } else {
                        memset(&p, 0, sizeof(p));
                }
                if (t == NULL)
                        t = netdev_priv(dev);
                vti6_parm_to_user(&p, &t->parms);
                if (copy_to_user(ifr->ifr_ifru.ifru_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, ifr->ifr_ifru.ifru_data, sizeof(p)))
                        break;
                err = -EINVAL;
                if (p.proto != IPPROTO_IPV6  && p.proto != 0)
                        break;
                vti6_parm_from_user(&p1, &p);
                t = vti6_locate(net, &p1, cmd == SIOCADDTUNNEL);
                if (dev != ip6n->fb_tnl_dev && cmd == SIOCCHGTUNNEL) {
                        if (t != NULL) {
                                if (t->dev != dev) {
                                        err = -EEXIST;
                                        break;
                                }
                        } else
                                t = netdev_priv(dev);

                        err = vti6_update(t, &p1);
                }
                if (t) {
                        err = 0;
                        vti6_parm_to_user(&p, &t->parms);
                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
                                err = -EFAULT;

                } else
                        err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
                break;
        case SIOCDELTUNNEL:
                err = -EPERM;
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        break;

                if (dev == ip6n->fb_tnl_dev) {
                        err = -EFAULT;
                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
                                break;
                        err = -ENOENT;
                        vti6_parm_from_user(&p1, &p);
                        t = vti6_locate(net, &p1, 0);
                        if (t == NULL)
                                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;
}

/**
 * vti6_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
 **/
static int vti6_change_mtu(struct net_device *dev, int new_mtu)
{
        if (new_mtu < IPV6_MIN_MTU)
                return -EINVAL;

        dev->mtu = new_mtu;
        return 0;
}

static const struct net_device_ops vti6_netdev_ops = {
        .ndo_uninit     = vti6_dev_uninit,
        .ndo_start_xmit = vti6_tnl_xmit,
        .ndo_do_ioctl   = vti6_ioctl,
        .ndo_change_mtu = vti6_change_mtu,
        .ndo_get_stats64 = ip_tunnel_get_stats64,
};

/**
 * vti6_dev_setup - setup virtual tunnel device
 *   @dev: virtual device associated with tunnel
 *
 * Description:
 *   Initialize function pointers and device parameters
 **/
static void vti6_dev_setup(struct net_device *dev)
{
        struct ip6_tnl *t;

        dev->netdev_ops = &vti6_netdev_ops;
        dev->destructor = vti6_dev_free;

        dev->type = ARPHRD_TUNNEL6;
        dev->hard_header_len = LL_MAX_HEADER + sizeof(struct ipv6hdr);
        dev->mtu = ETH_DATA_LEN;
        t = netdev_priv(dev);
        dev->flags |= IFF_NOARP;
        dev->addr_len = sizeof(struct in6_addr);
        dev->features |= NETIF_F_NETNS_LOCAL;
        dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
}

/**
 * vti6_dev_init_gen - general initializer for all tunnel devices
 *   @dev: virtual device associated with tunnel
 **/
static inline int vti6_dev_init_gen(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int i;

        t->dev = dev;
        t->net = dev_net(dev);
        dev->tstats = alloc_percpu(struct pcpu_tstats);
        if (!dev->tstats)
                return -ENOMEM;
        for_each_possible_cpu(i) {
                struct pcpu_tstats *stats;
                stats = per_cpu_ptr(dev->tstats, i);
                u64_stats_init(&stats->syncp);
        }
        return 0;
}

/**
 * vti6_dev_init - initializer for all non fallback tunnel devices
 *   @dev: virtual device associated with tunnel
 **/
static int vti6_dev_init(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        int err = vti6_dev_init_gen(dev);

        if (err)
                return err;
        vti6_link_config(t);
        return 0;
}

/**
 * vti6_fb_tnl_dev_init - initializer for fallback tunnel device
 *   @dev: fallback device
 *
 * Return: 0
 **/
static int __net_init vti6_fb_tnl_dev_init(struct net_device *dev)
{
        struct ip6_tnl *t = netdev_priv(dev);
        struct net *net = dev_net(dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);
        int err = vti6_dev_init_gen(dev);

        if (err)
                return err;

        t->parms.proto = IPPROTO_IPV6;
        dev_hold(dev);

        vti6_link_config(t);

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

static int vti6_validate(struct nlattr *tb[], struct nlattr *data[])
{
        return 0;
}

static void vti6_netlink_parms(struct nlattr *data[],
                               struct __ip6_tnl_parm *parms)
{
        memset(parms, 0, sizeof(*parms));

        if (!data)
                return;

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

        if (data[IFLA_VTI_LOCAL])
                nla_memcpy(&parms->laddr, data[IFLA_VTI_LOCAL],
                           sizeof(struct in6_addr));

        if (data[IFLA_VTI_REMOTE])
                nla_memcpy(&parms->raddr, data[IFLA_VTI_REMOTE],
                           sizeof(struct in6_addr));

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

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

static int vti6_newlink(struct net *src_net, struct net_device *dev,
                        struct nlattr *tb[], struct nlattr *data[])
{
        struct net *net = dev_net(dev);
        struct ip6_tnl *nt;

        nt = netdev_priv(dev);
        vti6_netlink_parms(data, &nt->parms);

        nt->parms.proto = IPPROTO_IPV6;

        if (vti6_locate(net, &nt->parms, 0))
                return -EEXIST;

        return vti6_tnl_create2(dev);
}

static int vti6_changelink(struct net_device *dev, struct nlattr *tb[],
                           struct nlattr *data[])
{
        struct ip6_tnl *t;
        struct __ip6_tnl_parm p;
        struct net *net = dev_net(dev);
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);

        if (dev == ip6n->fb_tnl_dev)
                return -EINVAL;

        vti6_netlink_parms(data, &p);

        t = vti6_locate(net, &p, 0);

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

        return vti6_update(t, &p);
}

static size_t vti6_get_size(const struct net_device *dev)
{
        return
                /* IFLA_VTI_LINK */
                nla_total_size(4) +
                /* IFLA_VTI_LOCAL */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_VTI_REMOTE */
                nla_total_size(sizeof(struct in6_addr)) +
                /* IFLA_VTI_IKEY */
                nla_total_size(4) +
                /* IFLA_VTI_OKEY */
                nla_total_size(4) +
                0;
}

static int vti6_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_VTI_LINK, parm->link) ||
            nla_put(skb, IFLA_VTI_LOCAL, sizeof(struct in6_addr),
                    &parm->laddr) ||
            nla_put(skb, IFLA_VTI_REMOTE, sizeof(struct in6_addr),
                    &parm->raddr) ||
            nla_put_be32(skb, IFLA_VTI_IKEY, parm->i_key) ||
            nla_put_be32(skb, IFLA_VTI_OKEY, parm->o_key))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

static const struct nla_policy vti6_policy[IFLA_VTI_MAX + 1] = {
        [IFLA_VTI_LINK]         = { .type = NLA_U32 },
        [IFLA_VTI_LOCAL]        = { .len = sizeof(struct in6_addr) },
        [IFLA_VTI_REMOTE]       = { .len = sizeof(struct in6_addr) },
        [IFLA_VTI_IKEY]         = { .type = NLA_U32 },
        [IFLA_VTI_OKEY]         = { .type = NLA_U32 },
};

static struct rtnl_link_ops vti6_link_ops __read_mostly = {
        .kind           = "vti6",
        .maxtype        = IFLA_VTI_MAX,
        .policy         = vti6_policy,
        .priv_size      = sizeof(struct ip6_tnl),
        .setup          = vti6_dev_setup,
        .validate       = vti6_validate,
        .newlink        = vti6_newlink,
        .changelink     = vti6_changelink,
        .get_size       = vti6_get_size,
        .fill_info      = vti6_fill_info,
};

static struct xfrm_tunnel_notifier vti6_handler __read_mostly = {
        .handler        = vti6_rcv,
        .priority       =       1,
};

static void __net_exit vti6_destroy_tunnels(struct vti6_net *ip6n)
{
        int h;
        struct ip6_tnl *t;
        LIST_HEAD(list);

        for (h = 0; h < HASH_SIZE; h++) {
                t = rtnl_dereference(ip6n->tnls_r_l[h]);
                while (t != NULL) {
                        unregister_netdevice_queue(t->dev, &list);
                        t = rtnl_dereference(t->next);
                }
        }

        t = rtnl_dereference(ip6n->tnls_wc[0]);
        unregister_netdevice_queue(t->dev, &list);
        unregister_netdevice_many(&list);
}

static int __net_init vti6_init_net(struct net *net)
{
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);
        struct ip6_tnl *t = NULL;
        int err;

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

        err = -ENOMEM;
        ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6_vti0",
                                        vti6_dev_setup);

        if (!ip6n->fb_tnl_dev)
                goto err_alloc_dev;
        dev_net_set(ip6n->fb_tnl_dev, net);

        err = vti6_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:
        vti6_dev_free(ip6n->fb_tnl_dev);
err_alloc_dev:
        return err;
}

static void __net_exit vti6_exit_net(struct net *net)
{
        struct vti6_net *ip6n = net_generic(net, vti6_net_id);

        rtnl_lock();
        vti6_destroy_tunnels(ip6n);
        rtnl_unlock();
}

static struct pernet_operations vti6_net_ops = {
        .init = vti6_init_net,
        .exit = vti6_exit_net,
        .id   = &vti6_net_id,
        .size = sizeof(struct vti6_net),
};

/**
 * vti6_tunnel_init - register protocol and reserve needed resources
 *
 * Return: 0 on success
 **/
static int __init vti6_tunnel_init(void)
{

        int  err;

        err = register_pernet_device(&vti6_net_ops);
        if (err < 0)
                goto out_pernet;

        err = xfrm6_mode_tunnel_input_register(&vti6_handler);
        if (err < 0) {
                pr_err("%s: can't register vti6\n", __func__);
                goto out;
        }
        err = rtnl_link_register(&vti6_link_ops);
        if (err < 0)
                goto rtnl_link_failed;

        return 0;

rtnl_link_failed:
        xfrm6_mode_tunnel_input_deregister(&vti6_handler);
out:
        unregister_pernet_device(&vti6_net_ops);
out_pernet:
        return err;
}

/**
 * vti6_tunnel_cleanup - free resources and unregister protocol
 **/
static void __exit vti6_tunnel_cleanup(void)
{
        rtnl_link_unregister(&vti6_link_ops);
        if (xfrm6_mode_tunnel_input_deregister(&vti6_handler))
                pr_info("%s: can't deregister vti6\n", __func__);

        unregister_pernet_device(&vti6_net_ops);
}

module_init(vti6_tunnel_init);
module_exit(vti6_tunnel_cleanup);
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("vti6");
MODULE_ALIAS_NETDEV("ip6_vti0");
MODULE_AUTHOR("Steffen Klassert");
MODULE_DESCRIPTION("IPv6 virtual tunnel interface");