Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 833 insertions, 0 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
new file mode 100644
index 000000000000..b788f55e139b
--- /dev/null
+++ b/net/ipv6/sit.c
@@ -0,0 +1,833 @@
+/*
+ *      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>
+ *
+ *      $Id: sit.c,v 1.53 2001/09/25 05:09:53 davem Exp $
+ *
+ *      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
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/sched.h>
+#include <linux/net.h>
+#include <linux/in6.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/icmp.h>
+#include <asm/uaccess.h>
+#include <linux/init.h>
+#include <linux/netfilter_ipv4.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/ipip.h>
+#include <net/inet_ecn.h>
+#include <net/xfrm.h>
+#include <net/dsfield.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) ((addr^(addr>>4))&0xF)
+
+static int ipip6_fb_tunnel_init(struct net_device *dev);
+static int ipip6_tunnel_init(struct net_device *dev);
+static void ipip6_tunnel_setup(struct net_device *dev);
+
+static struct net_device *ipip6_fb_tunnel_dev;
+
+static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
+static struct ip_tunnel *tunnels_r[HASH_SIZE];
+static struct ip_tunnel *tunnels_l[HASH_SIZE];
+static struct ip_tunnel *tunnels_wc[1];
+static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
+
+static DEFINE_RWLOCK(ipip6_lock);
+
+static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local)
+{
+        unsigned h0 = HASH(remote);
+        unsigned h1 = HASH(local);
+        struct ip_tunnel *t;
+
+        for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
+                if (local == t->parms.iph.saddr &&
+                    remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
+                        return t;
+        }
+        for (t = tunnels_r[h0]; t; t = t->next) {
+                if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
+                        return t;
+        }
+        for (t = tunnels_l[h1]; t; t = t->next) {
+                if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
+                        return t;
+        }
+        if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
+                return t;
+        return NULL;
+}
+
+static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t)
+{
+        u32 remote = t->parms.iph.daddr;
+        u32 local = t->parms.iph.saddr;
+        unsigned h = 0;
+        int prio = 0;
+
+        if (remote) {
+                prio |= 2;
+                h ^= HASH(remote);
+        }
+        if (local) {
+                prio |= 1;
+                h ^= HASH(local);
+        }
+        return &tunnels[prio][h];
+}
+
+static void ipip6_tunnel_unlink(struct ip_tunnel *t)
+{
+        struct ip_tunnel **tp;
+
+        for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
+                if (t == *tp) {
+                        write_lock_bh(&ipip6_lock);
+                        *tp = t->next;
+                        write_unlock_bh(&ipip6_lock);
+                        break;
+                }
+        }
+}
+
+static void ipip6_tunnel_link(struct ip_tunnel *t)
+{
+        struct ip_tunnel **tp = ipip6_bucket(t);
+
+        t->next = *tp;
+        write_lock_bh(&ipip6_lock);
+        *tp = t;
+        write_unlock_bh(&ipip6_lock);
+}
+
+static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
+{
+        u32 remote = parms->iph.daddr;
+        u32 local = parms->iph.saddr;
+        struct ip_tunnel *t, **tp, *nt;
+        struct net_device *dev;
+        unsigned h = 0;
+        int prio = 0;
+        char name[IFNAMSIZ];
+
+        if (remote) {
+                prio |= 2;
+                h ^= HASH(remote);
+        }
+        if (local) {
+                prio |= 1;
+                h ^= HASH(local);
+        }
+        for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
+                if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
+                        return t;
+        }
+        if (!create)
+                goto failed;
+
+        if (parms->name[0])
+                strlcpy(name, parms->name, IFNAMSIZ);
+        else {
+                int i;
+                for (i=1; i<100; i++) {
+                        sprintf(name, "sit%d", i);
+                        if (__dev_get_by_name(name) == NULL)
+                                break;
+                }
+                if (i==100)
+                        goto failed;
+        }
+
+        dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
+        if (dev == NULL)
+                return NULL;
+
+        nt = dev->priv;
+        dev->init = ipip6_tunnel_init;
+        nt->parms = *parms;
+
+        if (register_netdevice(dev) < 0) {
+                free_netdev(dev);
+                goto failed;
+        }
+
+        dev_hold(dev);
+
+        ipip6_tunnel_link(nt);
+        /* Do not decrement MOD_USE_COUNT here. */
+        return nt;
+
+failed:
+        return NULL;
+}
+
+static void ipip6_tunnel_uninit(struct net_device *dev)
+{
+        if (dev == ipip6_fb_tunnel_dev) {
+                write_lock_bh(&ipip6_lock);
+                tunnels_wc[0] = NULL;
+                write_unlock_bh(&ipip6_lock);
+                dev_put(dev);
+        } else {
+                ipip6_tunnel_unlink((struct ip_tunnel*)dev->priv);
+                dev_put(dev);
+        }
+}
+
+
+static void ipip6_err(struct sk_buff *skb, u32 info)
+{
+#ifndef I_WISH_WORLD_WERE_PERFECT
+
+/* It is not :-( All the routers (except for Linux) return only
+   8 bytes of packet payload. It means, that precise relaying of
+   ICMP in the real Internet is absolutely infeasible.
+ */
+        struct iphdr *iph = (struct iphdr*)skb->data;
+        int type = skb->h.icmph->type;
+        int code = skb->h.icmph->code;
+        struct ip_tunnel *t;
+
+        switch (type) {
+        default:
+        case ICMP_PARAMETERPROB:
+                return;
+
+        case ICMP_DEST_UNREACH:
+                switch (code) {
+                case ICMP_SR_FAILED:
+                case ICMP_PORT_UNREACH:
+                        /* Impossible event. */
+                        return;
+                case ICMP_FRAG_NEEDED:
+                        /* Soft state for pmtu is maintained by IP core. */
+                        return;
+                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;
+                break;
+        }
+
+        read_lock(&ipip6_lock);
+        t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
+        if (t == NULL || t->parms.iph.daddr == 0)
+                goto out;
+        if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
+                goto out;
+
+        if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
+                t->err_count++;
+        else
+                t->err_count = 1;
+        t->err_time = jiffies;
+out:
+        read_unlock(&ipip6_lock);
+        return;
+#else
+        struct iphdr *iph = (struct iphdr*)dp;
+        int hlen = iph->ihl<<2;
+        struct ipv6hdr *iph6;
+        int type = skb->h.icmph->type;
+        int code = skb->h.icmph->code;
+        int rel_type = 0;
+        int rel_code = 0;
+        int rel_info = 0;
+        struct sk_buff *skb2;
+        struct rt6_info *rt6i;
+
+        if (len < hlen + sizeof(struct ipv6hdr))
+                return;
+        iph6 = (struct ipv6hdr*)(dp + hlen);
+
+        switch (type) {
+        default:
+                return;
+        case ICMP_PARAMETERPROB:
+                if (skb->h.icmph->un.gateway < hlen)
+                        return;
+
+                /* So... This guy found something strange INSIDE encapsulated
+                   packet. Well, he is fool, but what can we do ?
+                 */
+                rel_type = ICMPV6_PARAMPROB;
+                rel_info = skb->h.icmph->un.gateway - hlen;
+                break;
+
+        case ICMP_DEST_UNREACH:
+                switch (code) {
+                case ICMP_SR_FAILED:
+                case ICMP_PORT_UNREACH:
+                        /* Impossible event. */
+                        return;
+                case ICMP_FRAG_NEEDED:
+                        /* Too complicated case ... */
+                        return;
+                default:
+                        /* All others are translated to HOST_UNREACH.
+                           rfc2003 contains "deep thoughts" about NET_UNREACH,
+                           I believe, it is just ether pollution. --ANK
+                         */
+                        rel_type = ICMPV6_DEST_UNREACH;
+                        rel_code = ICMPV6_ADDR_UNREACH;
+                        break;
+                }
+                break;
+        case ICMP_TIME_EXCEEDED:
+                if (code != ICMP_EXC_TTL)
+                        return;
+                rel_type = ICMPV6_TIME_EXCEED;
+                rel_code = ICMPV6_EXC_HOPLIMIT;
+                break;
+        }
+
+        /* Prepare fake skb to feed it to icmpv6_send */
+        skb2 = skb_clone(skb, GFP_ATOMIC);
+        if (skb2 == NULL)
+                return;
+        dst_release(skb2->dst);
+        skb2->dst = NULL;
+        skb_pull(skb2, skb->data - (u8*)iph6);
+        skb2->nh.raw = skb2->data;
+
+        /* Try to guess incoming interface */
+        rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0);
+        if (rt6i && rt6i->rt6i_dev) {
+                skb2->dev = rt6i->rt6i_dev;
+
+                rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0);
+
+                if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) {
+                        struct ip_tunnel * t = (struct ip_tunnel*)rt6i->rt6i_dev->priv;
+                        if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) {
+                                rel_type = ICMPV6_DEST_UNREACH;
+                                rel_code = ICMPV6_ADDR_UNREACH;
+                        }
+                        icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
+                }
+        }
+        kfree_skb(skb2);
+        return;
+#endif
+}
+
+static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
+{
+        if (INET_ECN_is_ce(iph->tos))
+                IP6_ECN_set_ce(skb->nh.ipv6h);
+}
+
+static int ipip6_rcv(struct sk_buff *skb)
+{
+        struct iphdr *iph;
+        struct ip_tunnel *tunnel;
+
+        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
+                goto out;
+
+        iph = skb->nh.iph;
+
+        read_lock(&ipip6_lock);
+        if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
+                secpath_reset(skb);
+                skb->mac.raw = skb->nh.raw;
+                skb->nh.raw = skb->data;
+                memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
+                skb->protocol = htons(ETH_P_IPV6);
+                skb->pkt_type = PACKET_HOST;
+                tunnel->stat.rx_packets++;
+                tunnel->stat.rx_bytes += skb->len;
+                skb->dev = tunnel->dev;
+                dst_release(skb->dst);
+                skb->dst = NULL;
+                nf_reset(skb);
+                ipip6_ecn_decapsulate(iph, skb);
+                netif_rx(skb);
+                read_unlock(&ipip6_lock);
+                return 0;
+        }
+
+        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
+        kfree_skb(skb);
+        read_unlock(&ipip6_lock);
+out:
+        return 0;
+}
+
+/* Returns the embedded IPv4 address if the IPv6 address
+   comes from 6to4 (RFC 3056) addr space */
+
+static inline u32 try_6to4(struct in6_addr *v6dst)
+{
+        u32 dst = 0;
+
+        if (v6dst->s6_addr16[0] == htons(0x2002)) {
+                /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
+                memcpy(&dst, &v6dst->s6_addr16[1], 4);
+        }
+        return dst;
+}
+
+/*
+ *      This function assumes it is being called from dev_queue_xmit()
+ *      and that skb is filled properly by that function.
+ */
+
+static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
+        struct net_device_stats *stats = &tunnel->stat;
+        struct iphdr  *tiph = &tunnel->parms.iph;
+        struct ipv6hdr *iph6 = skb->nh.ipv6h;
+        u8     tos = tunnel->parms.iph.tos;
+        struct rtable *rt;                      /* Route to the other host */
+        struct net_device *tdev;                        /* Device to other host */
+        struct iphdr  *iph;                     /* Our new IP header */
+        int    max_headroom;                    /* The extra header space needed */
+        u32    dst = tiph->daddr;
+        int    mtu;
+        struct in6_addr *addr6; 
+        int addr_type;
+
+        if (tunnel->recursion++) {
+                tunnel->stat.collisions++;
+                goto tx_error;
+        }
+
+        if (skb->protocol != htons(ETH_P_IPV6))
+                goto tx_error;
+
+        if (!dst)
+                dst = try_6to4(&iph6->daddr);
+
+        if (!dst) {
+                struct neighbour *neigh = NULL;
+
+                if (skb->dst)
+                        neigh = skb->dst->neighbour;
+
+                if (neigh == NULL) {
+                        if (net_ratelimit())
+                                printk(KERN_DEBUG "sit: nexthop == NULL\n");
+                        goto tx_error;
+                }
+
+                addr6 = (struct in6_addr*)&neigh->primary_key;
+                addr_type = ipv6_addr_type(addr6);
+
+                if (addr_type == IPV6_ADDR_ANY) {
+                        addr6 = &skb->nh.ipv6h->daddr;
+                        addr_type = ipv6_addr_type(addr6);
+                }
+
+                if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
+                        goto tx_error_icmp;
+
+                dst = addr6->s6_addr32[3];
+        }
+
+        {
+                struct flowi fl = { .nl_u = { .ip4_u =
+                                              { .daddr = dst,
+                                                .saddr = tiph->saddr,
+                                                .tos = RT_TOS(tos) } },
+                                    .oif = tunnel->parms.link,
+                                    .proto = IPPROTO_IPV6 };
+                if (ip_route_output_key(&rt, &fl)) {
+                        tunnel->stat.tx_carrier_errors++;
+                        goto tx_error_icmp;
+                }
+        }
+        if (rt->rt_type != RTN_UNICAST) {
+                ip_rt_put(rt);
+                tunnel->stat.tx_carrier_errors++;
+                goto tx_error_icmp;
+        }
+        tdev = rt->u.dst.dev;
+
+        if (tdev == dev) {
+                ip_rt_put(rt);
+                tunnel->stat.collisions++;
+                goto tx_error;
+        }
+
+        if (tiph->frag_off)
+                mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
+        else
+                mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
+
+        if (mtu < 68) {
+                tunnel->stat.collisions++;
+                ip_rt_put(rt);
+                goto tx_error;
+        }
+        if (mtu < IPV6_MIN_MTU)
+                mtu = IPV6_MIN_MTU;
+        if (tunnel->parms.iph.daddr && skb->dst)
+                skb->dst->ops->update_pmtu(skb->dst, mtu);
+
+        if (skb->len > mtu) {
+                icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
+                ip_rt_put(rt);
+                goto tx_error;
+        }
+
+        if (tunnel->err_count > 0) {
+                if (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)+sizeof(struct iphdr);
+
+        if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
+                struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
+                if (!new_skb) {
+                        ip_rt_put(rt);
+                        stats->tx_dropped++;
+                        dev_kfree_skb(skb);
+                        tunnel->recursion--;
+                        return 0;
+                }
+                if (skb->sk)
+                        skb_set_owner_w(new_skb, skb->sk);
+                dev_kfree_skb(skb);
+                skb = new_skb;
+                iph6 = skb->nh.ipv6h;
+        }
+
+        skb->h.raw = skb->nh.raw;
+        skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
+        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+        dst_release(skb->dst);
+        skb->dst = &rt->u.dst;
+
+        /*
+         *      Push down and install the IPIP header.
+         */
+
+        iph                     =       skb->nh.iph;
+        iph->version            =       4;
+        iph->ihl                =       sizeof(struct iphdr)>>2;
+        if (mtu > IPV6_MIN_MTU)
+                iph->frag_off   =       htons(IP_DF);
+        else
+                iph->frag_off   =       0;
+
+        iph->protocol           =       IPPROTO_IPV6;
+        iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
+        iph->daddr              =       rt->rt_dst;
+        iph->saddr              =       rt->rt_src;
+
+        if ((iph->ttl = tiph->ttl) == 0)
+                iph->ttl        =       iph6->hop_limit;
+
+        nf_reset(skb);
+
+        IPTUNNEL_XMIT();
+        tunnel->recursion--;
+        return 0;
+
+tx_error_icmp:
+        dst_link_failure(skb);
+tx_error:
+        stats->tx_errors++;
+        dev_kfree_skb(skb);
+        tunnel->recursion--;
+        return 0;
+}
+
+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 *t;
+
+        switch (cmd) {
+        case SIOCGETTUNNEL:
+                t = NULL;
+                if (dev == ipip6_fb_tunnel_dev) {
+                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
+                                err = -EFAULT;
+                                break;
+                        }
+                        t = ipip6_tunnel_locate(&p, 0);
+                }
+                if (t == NULL)
+                        t = (struct ip_tunnel*)dev->priv;
+                memcpy(&p, &t->parms, sizeof(p));
+                if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
+                        err = -EFAULT;
+                break;
+
+        case SIOCADDTUNNEL:
+        case SIOCCHGTUNNEL:
+                err = -EPERM;
+                if (!capable(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.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
+                    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(&p, cmd == SIOCADDTUNNEL);
+
+                if (dev != ipip6_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 = (struct ip_tunnel*)dev->priv;
+                                ipip6_tunnel_unlink(t);
+                                t->parms.iph.saddr = p.iph.saddr;
+                                t->parms.iph.daddr = p.iph.daddr;
+                                memcpy(dev->dev_addr, &p.iph.saddr, 4);
+                                memcpy(dev->broadcast, &p.iph.daddr, 4);
+                                ipip6_tunnel_link(t);
+                                netdev_state_change(dev);
+                        }
+                }
+
+                if (t) {
+                        err = 0;
+                        if (cmd == SIOCCHGTUNNEL) {
+                                t->parms.iph.ttl = p.iph.ttl;
+                                t->parms.iph.tos = p.iph.tos;
+                        }
+                        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 (!capable(CAP_NET_ADMIN))
+                        goto done;
+
+                if (dev == ipip6_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(&p, 0)) == NULL)
+                                goto done;
+                        err = -EPERM;
+                        if (t == ipip6_fb_tunnel_dev->priv)
+                                goto done;
+                        dev = t->dev;
+                }
+                err = unregister_netdevice(dev);
+                break;
+
+        default:
+                err = -EINVAL;
+        }
+
+done:
+        return err;
+}
+
+static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
+{
+        return &(((struct ip_tunnel*)dev->priv)->stat);
+}
+
+static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
+{
+        if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
+                return -EINVAL;
+        dev->mtu = new_mtu;
+        return 0;
+}
+
+static void ipip6_tunnel_setup(struct net_device *dev)
+{
+        SET_MODULE_OWNER(dev);
+        dev->uninit             = ipip6_tunnel_uninit;
+        dev->destructor         = free_netdev;
+        dev->hard_start_xmit    = ipip6_tunnel_xmit;
+        dev->get_stats          = ipip6_tunnel_get_stats;
+        dev->do_ioctl           = ipip6_tunnel_ioctl;
+        dev->change_mtu         = ipip6_tunnel_change_mtu;
+
+        dev->type               = ARPHRD_SIT;
+        dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
+        dev->mtu                = 1500 - sizeof(struct iphdr);
+        dev->flags              = IFF_NOARP;
+        dev->iflink             = 0;
+        dev->addr_len           = 4;
+}
+
+static int ipip6_tunnel_init(struct net_device *dev)
+{
+        struct net_device *tdev = NULL;
+        struct ip_tunnel *tunnel;
+        struct iphdr *iph;
+
+        tunnel = (struct ip_tunnel*)dev->priv;
+        iph = &tunnel->parms.iph;
+
+        tunnel->dev = dev;
+        strcpy(tunnel->parms.name, dev->name);
+
+        memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
+        memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
+
+        if (iph->daddr) {
+                struct flowi fl = { .nl_u = { .ip4_u =
+                                              { .daddr = iph->daddr,
+                                                .saddr = iph->saddr,
+                                                .tos = RT_TOS(iph->tos) } },
+                                    .oif = tunnel->parms.link,
+                                    .proto = IPPROTO_IPV6 };
+                struct rtable *rt;
+                if (!ip_route_output_key(&rt, &fl)) {
+                        tdev = rt->u.dst.dev;
+                        ip_rt_put(rt);
+                }
+                dev->flags |= IFF_POINTOPOINT;
+        }
+
+        if (!tdev && tunnel->parms.link)
+                tdev = __dev_get_by_index(tunnel->parms.link);
+
+        if (tdev) {
+                dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
+                dev->mtu = tdev->mtu - sizeof(struct iphdr);
+                if (dev->mtu < IPV6_MIN_MTU)
+                        dev->mtu = IPV6_MIN_MTU;
+        }
+        dev->iflink = tunnel->parms.link;
+
+        return 0;
+}
+
+int __init ipip6_fb_tunnel_init(struct net_device *dev)
+{
+        struct ip_tunnel *tunnel = dev->priv;
+        struct iphdr *iph = &tunnel->parms.iph;
+
+        tunnel->dev = dev;
+        strcpy(tunnel->parms.name, dev->name);
+
+        iph->version            = 4;
+        iph->protocol           = IPPROTO_IPV6;
+        iph->ihl                = 5;
+        iph->ttl                = 64;
+
+        dev_hold(dev);
+        tunnels_wc[0]           = tunnel;
+        return 0;
+}
+
+static struct net_protocol sit_protocol = {
+        .handler        =       ipip6_rcv,
+        .err_handler    =       ipip6_err,
+};
+
+void __exit sit_cleanup(void)
+{
+        inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
+        unregister_netdev(ipip6_fb_tunnel_dev);
+}
+
+int __init sit_init(void)
+{
+        int err;
+
+        printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
+
+        if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) {
+                printk(KERN_INFO "sit init: Can't add protocol\n");
+                return -EAGAIN;
+        }
+
+        ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0", 
+                                           ipip6_tunnel_setup);
+        if (!ipip6_fb_tunnel_dev) {
+                err = -ENOMEM;
+                goto err1;
+        }
+
+        ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
+
+        if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
+                goto err2;
+
+ out:
+        return err;
+ err2:
+        free_netdev(ipip6_fb_tunnel_dev);
+ err1:
+        inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
+        goto out;
+}