1 files changed, 1163 insertions, 0 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
new file mode 100644
index 000000000000..3b1c9fa184ae
--- /dev/null
+++ b/net/ipv6/ip6_tunnel.c
@@ -0,0 +1,1163 @@
+/*
+ *      IPv6 over IPv6 tunnel device
+ *      Linux INET6 implementation
+ *
+ *      Authors:
+ *      Ville Nuorvala          <vnuorval@tcs.hut.fi>   
+ *
+ *      $Id$
+ *
+ *      Based on:
+ *      linux/net/ipv6/sit.c
+ *
+ *      RFC 2473
+ *
+ *      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/config.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/sockios.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 <asm/uaccess.h>
+#include <asm/atomic.h>
+
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+#include <net/ip6_tunnel.h>
+#include <net/xfrm.h>
+#include <net/dsfield.h>
+#include <net/inet_ecn.h>
+
+MODULE_AUTHOR("Ville Nuorvala");
+MODULE_DESCRIPTION("IPv6-in-IPv6 tunnel");
+MODULE_LICENSE("GPL");
+
+#define IPV6_TLV_TEL_DST_SIZE 8
+
+#ifdef IP6_TNL_DEBUG
+#define IP6_TNL_TRACE(x...) printk(KERN_DEBUG "%s:" x "\n", __FUNCTION__)
+#else
+#define IP6_TNL_TRACE(x...) do {;} while(0)
+#endif
+
+#define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK)
+
+#define HASH_SIZE  32
+
+#define HASH(addr) (((addr)->s6_addr32[0] ^ (addr)->s6_addr32[1] ^ \
+                     (addr)->s6_addr32[2] ^ (addr)->s6_addr32[3]) & \
+                    (HASH_SIZE - 1))
+
+static int ip6ip6_fb_tnl_dev_init(struct net_device *dev);
+static int ip6ip6_tnl_dev_init(struct net_device *dev);
+static void ip6ip6_tnl_dev_setup(struct net_device *dev);
+
+/* the IPv6 tunnel fallback device */
+static struct net_device *ip6ip6_fb_tnl_dev;
+
+
+/* lists for storing tunnels in use */
+static struct ip6_tnl *tnls_r_l[HASH_SIZE];
+static struct ip6_tnl *tnls_wc[1];
+static struct ip6_tnl **tnls[2] = { tnls_wc, tnls_r_l };
+
+/* lock for the tunnel lists */
+static DEFINE_RWLOCK(ip6ip6_lock);
+
+static inline struct dst_entry *ip6_tnl_dst_check(struct ip6_tnl *t)
+{
+        struct dst_entry *dst = t->dst_cache;
+
+        if (dst && dst->obsolete && 
+            dst->ops->check(dst, t->dst_cookie) == NULL) {
+                t->dst_cache = NULL;
+                dst_release(dst);
+                return NULL;
+        }
+
+        return dst;
+}
+
+static inline void ip6_tnl_dst_reset(struct ip6_tnl *t)
+{
+        dst_release(t->dst_cache);
+        t->dst_cache = NULL;
+}
+
+static inline void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst)
+{
+        struct rt6_info *rt = (struct rt6_info *) dst;
+        t->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+        dst_release(t->dst_cache);
+        t->dst_cache = dst;
+}
+
+/**
+ * ip6ip6_tnl_lookup - fetch tunnel matching the end-point addresses
+ *   @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 *
+ip6ip6_tnl_lookup(struct in6_addr *remote, struct in6_addr *local)
+{
+        unsigned h0 = HASH(remote);
+        unsigned h1 = HASH(local);
+        struct ip6_tnl *t;
+
+        for (t = tnls_r_l[h0 ^ h1]; t; t = t->next) {
+                if (ipv6_addr_equal(local, &t->parms.laddr) &&
+                    ipv6_addr_equal(remote, &t->parms.raddr) &&
+                    (t->dev->flags & IFF_UP))
+                        return t;
+        }
+        if ((t = tnls_wc[0]) != NULL && (t->dev->flags & IFF_UP))
+                return t;
+
+        return NULL;
+}
+
+/**
+ * ip6ip6_bucket - get head of list matching given tunnel parameters
+ *   @p: parameters containing tunnel end-points 
+ *
+ * Description:
+ *   ip6ip6_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 **
+ip6ip6_bucket(struct ip6_tnl_parm *p)
+{
+        struct in6_addr *remote = &p->raddr;
+        struct in6_addr *local = &p->laddr;
+        unsigned h = 0;
+        int prio = 0;
+
+        if (!ipv6_addr_any(remote) || !ipv6_addr_any(local)) {
+                prio = 1;
+                h = HASH(remote) ^ HASH(local);
+        }
+        return &tnls[prio][h];
+}
+
+/**
+ * ip6ip6_tnl_link - add tunnel to hash table
+ *   @t: tunnel to be added
+ **/
+
+static void
+ip6ip6_tnl_link(struct ip6_tnl *t)
+{
+        struct ip6_tnl **tp = ip6ip6_bucket(&t->parms);
+
+        t->next = *tp;
+        write_lock_bh(&ip6ip6_lock);
+        *tp = t;
+        write_unlock_bh(&ip6ip6_lock);
+}
+
+/**
+ * ip6ip6_tnl_unlink - remove tunnel from hash table
+ *   @t: tunnel to be removed
+ **/
+
+static void
+ip6ip6_tnl_unlink(struct ip6_tnl *t)
+{
+        struct ip6_tnl **tp;
+
+        for (tp = ip6ip6_bucket(&t->parms); *tp; tp = &(*tp)->next) {
+                if (t == *tp) {
+                        write_lock_bh(&ip6ip6_lock);
+                        *tp = t->next;
+                        write_unlock_bh(&ip6ip6_lock);
+                        break;
+                }
+        }
+}
+
+/**
+ * ip6_tnl_create() - create a new tunnel
+ *   @p: tunnel parameters
+ *   @pt: pointer to new tunnel
+ *
+ * Description:
+ *   Create tunnel matching given parameters.
+ * 
+ * Return: 
+ *   0 on success
+ **/
+
+static int
+ip6_tnl_create(struct ip6_tnl_parm *p, struct ip6_tnl **pt)
+{
+        struct net_device *dev;
+        struct ip6_tnl *t;
+        char name[IFNAMSIZ];
+        int err;
+
+        if (p->name[0]) {
+                strlcpy(name, p->name, IFNAMSIZ);
+        } else {
+                int i;
+                for (i = 1; i < IP6_TNL_MAX; i++) {
+                        sprintf(name, "ip6tnl%d", i);
+                        if (__dev_get_by_name(name) == NULL)
+                                break;
+                }
+                if (i == IP6_TNL_MAX) 
+                        return -ENOBUFS;
+        }
+        dev = alloc_netdev(sizeof (*t), name, ip6ip6_tnl_dev_setup);
+        if (dev == NULL)
+                return -ENOMEM;
+
+        t = dev->priv;
+        dev->init = ip6ip6_tnl_dev_init;
+        t->parms = *p;
+
+        if ((err = register_netdevice(dev)) < 0) {
+                free_netdev(dev);
+                return err;
+        }
+        dev_hold(dev);
+
+        ip6ip6_tnl_link(t);
+        *pt = t;
+        return 0;
+}
+
+/**
+ * ip6ip6_tnl_locate - find or create tunnel matching given parameters
+ *   @p: tunnel parameters 
+ *   @create: != 0 if allowed to create new tunnel if no match found
+ *
+ * Description:
+ *   ip6ip6_tnl_locate() first tries to locate an existing tunnel
+ *   based on @parms. If this is unsuccessful, but @create is set a new
+ *   tunnel device is created and registered for use.
+ *
+ * Return:
+ *   0 if tunnel located or created,
+ *   -EINVAL if parameters incorrect,
+ *   -ENODEV if no matching tunnel available
+ **/
+
+static int
+ip6ip6_tnl_locate(struct ip6_tnl_parm *p, struct ip6_tnl **pt, int create)
+{
+        struct in6_addr *remote = &p->raddr;
+        struct in6_addr *local = &p->laddr;
+        struct ip6_tnl *t;
+
+        if (p->proto != IPPROTO_IPV6)
+                return -EINVAL;
+
+        for (t = *ip6ip6_bucket(p); t; t = t->next) {
+                if (ipv6_addr_equal(local, &t->parms.laddr) &&
+                    ipv6_addr_equal(remote, &t->parms.raddr)) {
+                        *pt = t;
+                        return (create ? -EEXIST : 0);
+                }
+        }
+        if (!create)
+                return -ENODEV;
+        
+        return ip6_tnl_create(p, pt);
+}
+
+/**
+ * ip6ip6_tnl_dev_uninit - tunnel device uninitializer
+ *   @dev: the device to be destroyed
+ *   
+ * Description:
+ *   ip6ip6_tnl_dev_uninit() removes tunnel from its list
+ **/
+
+static void
+ip6ip6_tnl_dev_uninit(struct net_device *dev)
+{
+        struct ip6_tnl *t = dev->priv;
+
+        if (dev == ip6ip6_fb_tnl_dev) {
+                write_lock_bh(&ip6ip6_lock);
+                tnls_wc[0] = NULL;
+                write_unlock_bh(&ip6ip6_lock);
+        } else {
+                ip6ip6_tnl_unlink(t);
+        }
+        ip6_tnl_dst_reset(t);
+        dev_put(dev);
+}
+
+/**
+ * parse_tvl_tnl_enc_lim - handle encapsulation limit option
+ *   @skb: received socket buffer
+ *
+ * Return: 
+ *   0 if none was found, 
+ *   else index to encapsulation limit
+ **/
+
+static __u16
+parse_tlv_tnl_enc_lim(struct sk_buff *skb, __u8 * raw)
+{
+        struct ipv6hdr *ipv6h = (struct ipv6hdr *) raw;
+        __u8 nexthdr = ipv6h->nexthdr;
+        __u16 off = sizeof (*ipv6h);
+
+        while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) {
+                __u16 optlen = 0;
+                struct ipv6_opt_hdr *hdr;
+                if (raw + off + sizeof (*hdr) > skb->data &&
+                    !pskb_may_pull(skb, raw - skb->data + off + sizeof (*hdr)))
+                        break;
+
+                hdr = (struct ipv6_opt_hdr *) (raw + off);
+                if (nexthdr == NEXTHDR_FRAGMENT) {
+                        struct frag_hdr *frag_hdr = (struct frag_hdr *) hdr;
+                        if (frag_hdr->frag_off)
+                                break;
+                        optlen = 8;
+                } else if (nexthdr == NEXTHDR_AUTH) {
+                        optlen = (hdr->hdrlen + 2) << 2;
+                } else {
+                        optlen = ipv6_optlen(hdr);
+                }
+                if (nexthdr == NEXTHDR_DEST) {
+                        __u16 i = off + 2;
+                        while (1) {
+                                struct ipv6_tlv_tnl_enc_lim *tel;
+
+                                /* No more room for encapsulation limit */
+                                if (i + sizeof (*tel) > off + optlen)
+                                        break;
+
+                                tel = (struct ipv6_tlv_tnl_enc_lim *) &raw[i];
+                                /* return index of option if found and valid */
+                                if (tel->type == IPV6_TLV_TNL_ENCAP_LIMIT &&
+                                    tel->length == 1)
+                                        return i;
+                                /* else jump to next option */
+                                if (tel->type)
+                                        i += tel->length + 2;
+                                else
+                                        i++;
+                        }
+                }
+                nexthdr = hdr->nexthdr;
+                off += optlen;
+        }
+        return 0;
+}
+
+/**
+ * ip6ip6_err - tunnel error handler
+ *
+ * Description:
+ *   ip6ip6_err() should handle errors in the tunnel according
+ *   to the specifications in RFC 2473.
+ **/
+
+static void 
+ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+           int type, int code, int offset, __u32 info)
+{
+        struct ipv6hdr *ipv6h = (struct ipv6hdr *) skb->data;
+        struct ip6_tnl *t;
+        int rel_msg = 0;
+        int rel_type = ICMPV6_DEST_UNREACH;
+        int rel_code = ICMPV6_ADDR_UNREACH;
+        __u32 rel_info = 0;
+        __u16 len;
+
+        /* If the packet doesn't contain the original IPv6 header we are 
+           in trouble since we might need the source address for further 
+           processing of the error. */
+
+        read_lock(&ip6ip6_lock);
+        if ((t = ip6ip6_tnl_lookup(&ipv6h->daddr, &ipv6h->saddr)) == NULL)
+                goto out;
+
+        switch (type) {
+                __u32 teli;
+                struct ipv6_tlv_tnl_enc_lim *tel;
+                __u32 mtu;
+        case ICMPV6_DEST_UNREACH:
+                if (net_ratelimit())
+                        printk(KERN_WARNING
+                               "%s: Path to destination invalid "
+                               "or inactive!\n", t->parms.name);
+                rel_msg = 1;
+                break;
+        case ICMPV6_TIME_EXCEED:
+                if (code == ICMPV6_EXC_HOPLIMIT) {
+                        if (net_ratelimit())
+                                printk(KERN_WARNING
+                                       "%s: Too small hop limit or "
+                                       "routing loop in tunnel!\n", 
+                                       t->parms.name);
+                        rel_msg = 1;
+                }
+                break;
+        case ICMPV6_PARAMPROB:
+                /* ignore if parameter problem not caused by a tunnel
+                   encapsulation limit sub-option */
+                if (code != ICMPV6_HDR_FIELD) {
+                        break;
+                }
+                teli = parse_tlv_tnl_enc_lim(skb, skb->data);
+
+                if (teli && teli == ntohl(info) - 2) {
+                        tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
+                        if (tel->encap_limit == 0) {
+                                if (net_ratelimit())
+                                        printk(KERN_WARNING
+                                               "%s: Too small encapsulation "
+                                               "limit or routing loop in "
+                                               "tunnel!\n", t->parms.name);
+                                rel_msg = 1;
+                        }
+                }
+                break;
+        case ICMPV6_PKT_TOOBIG:
+                mtu = ntohl(info) - offset;
+                if (mtu < IPV6_MIN_MTU)
+                        mtu = IPV6_MIN_MTU;
+                t->dev->mtu = mtu;
+
+                if ((len = sizeof (*ipv6h) + ipv6h->payload_len) > mtu) {
+                        rel_type = ICMPV6_PKT_TOOBIG;
+                        rel_code = 0;
+                        rel_info = mtu;
+                        rel_msg = 1;
+                }
+                break;
+        }
+        if (rel_msg &&  pskb_may_pull(skb, offset + sizeof (*ipv6h))) {
+                struct rt6_info *rt;
+                struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
+                if (!skb2)
+                        goto out;
+
+                dst_release(skb2->dst);
+                skb2->dst = NULL;
+                skb_pull(skb2, offset);
+                skb2->nh.raw = skb2->data;
+
+                /* Try to guess incoming interface */
+                rt = rt6_lookup(&skb2->nh.ipv6h->saddr, NULL, 0, 0);
+
+                if (rt && rt->rt6i_dev)
+                        skb2->dev = rt->rt6i_dev;
+
+                icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
+
+                if (rt)
+                        dst_release(&rt->u.dst);
+
+                kfree_skb(skb2);
+        }
+out:
+        read_unlock(&ip6ip6_lock);
+}
+
+static inline void ip6ip6_ecn_decapsulate(struct ipv6hdr *outer_iph,
+                                          struct sk_buff *skb)
+{
+        struct ipv6hdr *inner_iph = skb->nh.ipv6h;
+
+        if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
+                IP6_ECN_set_ce(inner_iph);
+}
+
+/**
+ * ip6ip6_rcv - decapsulate IPv6 packet and retransmit it locally
+ *   @skb: received socket buffer
+ *
+ * Return: 0
+ **/
+
+static int 
+ip6ip6_rcv(struct sk_buff **pskb, unsigned int *nhoffp)
+{
+        struct sk_buff *skb = *pskb;
+        struct ipv6hdr *ipv6h;
+        struct ip6_tnl *t;
+
+        if (!pskb_may_pull(skb, sizeof (*ipv6h)))
+                goto discard;
+
+        ipv6h = skb->nh.ipv6h;
+
+        read_lock(&ip6ip6_lock);
+
+        if ((t = ip6ip6_tnl_lookup(&ipv6h->saddr, &ipv6h->daddr)) != NULL) {
+                if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+                        kfree_skb(skb);
+                        return 0;
+                }
+
+                if (!(t->parms.flags & IP6_TNL_F_CAP_RCV)) {
+                        t->stat.rx_dropped++;
+                        read_unlock(&ip6ip6_lock);
+                        goto discard;
+                }
+                secpath_reset(skb);
+                skb->mac.raw = skb->nh.raw;
+                skb->nh.raw = skb->data;
+                skb->protocol = htons(ETH_P_IPV6);
+                skb->pkt_type = PACKET_HOST;
+                memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
+                skb->dev = t->dev;
+                dst_release(skb->dst);
+                skb->dst = NULL;
+                if (t->parms.flags & IP6_TNL_F_RCV_DSCP_COPY)
+                        ipv6_copy_dscp(ipv6h, skb->nh.ipv6h);
+                ip6ip6_ecn_decapsulate(ipv6h, skb);
+                t->stat.rx_packets++;
+                t->stat.rx_bytes += skb->len;
+                netif_rx(skb);
+                read_unlock(&ip6ip6_lock);
+                return 0;
+        }
+        read_unlock(&ip6ip6_lock);
+        icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0, skb->dev);
+discard:
+        return 1;
+}
+
+static inline struct ipv6_txoptions *create_tel(__u8 encap_limit)
+{
+        struct ipv6_tlv_tnl_enc_lim *tel;
+        struct ipv6_txoptions *opt;
+        __u8 *raw;
+
+        int opt_len = sizeof(*opt) + 8;
+
+        if (!(opt = kmalloc(opt_len, GFP_ATOMIC))) {
+                return NULL;
+        }
+        memset(opt, 0, opt_len);
+        opt->tot_len = opt_len;
+        opt->dst0opt = (struct ipv6_opt_hdr *) (opt + 1);
+        opt->opt_nflen = 8;
+
+        tel = (struct ipv6_tlv_tnl_enc_lim *) (opt->dst0opt + 1);
+        tel->type = IPV6_TLV_TNL_ENCAP_LIMIT;
+        tel->length = 1;
+        tel->encap_limit = encap_limit;
+
+        raw = (__u8 *) opt->dst0opt;
+        raw[5] = IPV6_TLV_PADN;
+        raw[6] = 1;
+
+        return opt;
+}
+
+/**
+ * ip6ip6_tnl_addr_conflict - compare packet addresses to tunnel's own
+ *   @t: the outgoing tunnel device
+ *   @hdr: IPv6 header from the incoming packet 
+ *
+ * Description:
+ *   Avoid trivial tunneling loop by checking that tunnel exit-point 
+ *   doesn't match source of incoming packet.
+ *
+ * Return: 
+ *   1 if conflict,
+ *   0 else
+ **/
+
+static inline int
+ip6ip6_tnl_addr_conflict(struct ip6_tnl *t, struct ipv6hdr *hdr)
+{
+        return ipv6_addr_equal(&t->parms.raddr, &hdr->saddr);
+}
+
+/**
+ * ip6ip6_tnl_xmit - encapsulate packet and send 
+ *   @skb: the outgoing socket buffer
+ *   @dev: the outgoing tunnel device 
+ *
+ * Description:
+ *   Build new header and do some sanity checks on the packet before sending
+ *   it.
+ *
+ * Return: 
+ *   0
+ **/
+
+static int 
+ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct ip6_tnl *t = (struct ip6_tnl *) dev->priv;
+        struct net_device_stats *stats = &t->stat;
+        struct ipv6hdr *ipv6h = skb->nh.ipv6h;
+        struct ipv6_txoptions *opt = NULL;
+        int encap_limit = -1;
+        __u16 offset;
+        struct flowi fl;
+        struct dst_entry *dst;
+        struct net_device *tdev;
+        int mtu;
+        int max_headroom = sizeof(struct ipv6hdr);
+        u8 proto;
+        int err;
+        int pkt_len;
+        int dsfield;
+
+        if (t->recursion++) {
+                stats->collisions++;
+                goto tx_err;
+        }
+        if (skb->protocol != htons(ETH_P_IPV6) ||
+            !(t->parms.flags & IP6_TNL_F_CAP_XMIT) ||
+            ip6ip6_tnl_addr_conflict(t, ipv6h)) {
+                goto tx_err;
+        }
+        if ((offset = parse_tlv_tnl_enc_lim(skb, skb->nh.raw)) > 0) {
+                struct ipv6_tlv_tnl_enc_lim *tel;
+                tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->nh.raw[offset];
+                if (tel->encap_limit == 0) {
+                        icmpv6_send(skb, ICMPV6_PARAMPROB,
+                                    ICMPV6_HDR_FIELD, offset + 2, skb->dev);
+                        goto tx_err;
+                }
+                encap_limit = tel->encap_limit - 1;
+        } else if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) {
+                encap_limit = t->parms.encap_limit;
+        }
+        memcpy(&fl, &t->fl, sizeof (fl));
+        proto = fl.proto;
+
+        dsfield = ipv6_get_dsfield(ipv6h);
+        if ((t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS))
+                fl.fl6_flowlabel |= (*(__u32 *) ipv6h & IPV6_TCLASS_MASK);
+        if ((t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL))
+                fl.fl6_flowlabel |= (*(__u32 *) ipv6h & IPV6_FLOWLABEL_MASK);
+
+        if (encap_limit >= 0 && (opt = create_tel(encap_limit)) == NULL)
+                goto tx_err;
+
+        if ((dst = ip6_tnl_dst_check(t)) != NULL)
+                dst_hold(dst);
+        else
+                dst = ip6_route_output(NULL, &fl);
+
+        if (dst->error || xfrm_lookup(&dst, &fl, NULL, 0) < 0)
+                goto tx_err_link_failure;
+
+        tdev = dst->dev;
+
+        if (tdev == dev) {
+                stats->collisions++;
+                if (net_ratelimit())
+                        printk(KERN_WARNING 
+                               "%s: Local routing loop detected!\n",
+                               t->parms.name);
+                goto tx_err_dst_release;
+        }
+        mtu = dst_mtu(dst) - sizeof (*ipv6h);
+        if (opt) {
+                max_headroom += 8;
+                mtu -= 8;
+        }
+        if (mtu < IPV6_MIN_MTU)
+                mtu = IPV6_MIN_MTU;
+        if (skb->dst && mtu < dst_mtu(skb->dst)) {
+                struct rt6_info *rt = (struct rt6_info *) skb->dst;
+                rt->rt6i_flags |= RTF_MODIFIED;
+                rt->u.dst.metrics[RTAX_MTU-1] = mtu;
+        }
+        if (skb->len > mtu) {
+                icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
+                goto tx_err_dst_release;
+        }
+
+        /*
+         * Okay, now see if we can stuff it in the buffer as-is.
+         */
+        max_headroom += LL_RESERVED_SPACE(tdev);
+        
+        if (skb_headroom(skb) < max_headroom || 
+            skb_cloned(skb) || skb_shared(skb)) {
+                struct sk_buff *new_skb;
+                
+                if (!(new_skb = skb_realloc_headroom(skb, max_headroom)))
+                        goto tx_err_dst_release;
+
+                if (skb->sk)
+                        skb_set_owner_w(new_skb, skb->sk);
+                kfree_skb(skb);
+                skb = new_skb;
+        }
+        dst_release(skb->dst);
+        skb->dst = dst_clone(dst);
+
+        skb->h.raw = skb->nh.raw;
+
+        if (opt)
+                ipv6_push_nfrag_opts(skb, opt, &proto, NULL);
+
+        skb->nh.raw = skb_push(skb, sizeof(struct ipv6hdr));
+        ipv6h = skb->nh.ipv6h;
+        *(u32*)ipv6h = fl.fl6_flowlabel | htonl(0x60000000);
+        dsfield = INET_ECN_encapsulate(0, dsfield);
+        ipv6_change_dsfield(ipv6h, ~INET_ECN_MASK, dsfield);
+        ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
+        ipv6h->hop_limit = t->parms.hop_limit;
+        ipv6h->nexthdr = proto;
+        ipv6_addr_copy(&ipv6h->saddr, &fl.fl6_src);
+        ipv6_addr_copy(&ipv6h->daddr, &fl.fl6_dst);
+        nf_reset(skb);
+        pkt_len = skb->len;
+        err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, 
+                      skb->dst->dev, dst_output);
+
+        if (err == NET_XMIT_SUCCESS || err == NET_XMIT_CN) {
+                stats->tx_bytes += pkt_len;
+                stats->tx_packets++;
+        } else {
+                stats->tx_errors++;
+                stats->tx_aborted_errors++;
+        }
+        ip6_tnl_dst_store(t, dst);
+
+        if (opt)
+                kfree(opt);
+
+        t->recursion--;
+        return 0;
+tx_err_link_failure:
+        stats->tx_carrier_errors++;
+        dst_link_failure(skb);
+tx_err_dst_release:
+        dst_release(dst);
+        if (opt)
+                kfree(opt);
+tx_err:
+        stats->tx_errors++;
+        stats->tx_dropped++;
+        kfree_skb(skb);
+        t->recursion--;
+        return 0;
+}
+
+static void ip6_tnl_set_cap(struct ip6_tnl *t)
+{
+        struct ip6_tnl_parm *p = &t->parms;
+        struct in6_addr *laddr = &p->laddr;
+        struct in6_addr *raddr = &p->raddr;
+        int ltype = ipv6_addr_type(laddr);
+        int rtype = ipv6_addr_type(raddr);
+
+        p->flags &= ~(IP6_TNL_F_CAP_XMIT|IP6_TNL_F_CAP_RCV);
+
+        if (ltype != IPV6_ADDR_ANY && rtype != IPV6_ADDR_ANY &&
+            ((ltype|rtype) &
+             (IPV6_ADDR_UNICAST|
+              IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL|
+              IPV6_ADDR_MAPPED|IPV6_ADDR_RESERVED)) == IPV6_ADDR_UNICAST) {
+                struct net_device *ldev = NULL;
+                int l_ok = 1;
+                int r_ok = 1;
+
+                if (p->link)
+                        ldev = dev_get_by_index(p->link);
+                
+                if (ltype&IPV6_ADDR_UNICAST && !ipv6_chk_addr(laddr, ldev, 0))
+                        l_ok = 0;
+                
+                if (rtype&IPV6_ADDR_UNICAST && ipv6_chk_addr(raddr, NULL, 0))
+                        r_ok = 0;
+                
+                if (l_ok && r_ok) {
+                        if (ltype&IPV6_ADDR_UNICAST)
+                                p->flags |= IP6_TNL_F_CAP_XMIT;
+                        if (rtype&IPV6_ADDR_UNICAST)
+                                p->flags |= IP6_TNL_F_CAP_RCV;
+                }
+                if (ldev)
+                        dev_put(ldev);
+        }
+}
+
+static void ip6ip6_tnl_link_config(struct ip6_tnl *t)
+{
+        struct net_device *dev = t->dev;
+        struct ip6_tnl_parm *p = &t->parms;
+        struct flowi *fl = &t->fl;
+
+        memcpy(&dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
+        memcpy(&dev->broadcast, &p->raddr, sizeof(struct in6_addr));
+
+        /* Set up flowi template */
+        ipv6_addr_copy(&fl->fl6_src, &p->laddr);
+        ipv6_addr_copy(&fl->fl6_dst, &p->raddr);
+        fl->oif = p->link;
+        fl->fl6_flowlabel = 0;
+
+        if (!(p->flags&IP6_TNL_F_USE_ORIG_TCLASS))
+                fl->fl6_flowlabel |= IPV6_TCLASS_MASK & p->flowinfo;
+        if (!(p->flags&IP6_TNL_F_USE_ORIG_FLOWLABEL))
+                fl->fl6_flowlabel |= IPV6_FLOWLABEL_MASK & p->flowinfo;
+
+        ip6_tnl_set_cap(t);
+
+        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) {
+                struct rt6_info *rt = rt6_lookup(&p->raddr, &p->laddr,
+                                                 p->link, 0);
+
+                if (rt == NULL)
+                        return;
+
+                if (rt->rt6i_dev) {
+                        dev->hard_header_len = rt->rt6i_dev->hard_header_len +
+                                sizeof (struct ipv6hdr);
+
+                        dev->mtu = rt->rt6i_dev->mtu - sizeof (struct ipv6hdr);
+
+                        if (dev->mtu < IPV6_MIN_MTU)
+                                dev->mtu = IPV6_MIN_MTU;
+                }
+                dst_release(&rt->u.dst);
+        }
+}
+
+/**
+ * ip6ip6_tnl_change - update the tunnel parameters
+ *   @t: tunnel to be changed
+ *   @p: tunnel configuration parameters
+ *   @active: != 0 if tunnel is ready for use
+ *
+ * Description:
+ *   ip6ip6_tnl_change() updates the tunnel parameters
+ **/
+
+static int
+ip6ip6_tnl_change(struct ip6_tnl *t, struct ip6_tnl_parm *p)
+{
+        ipv6_addr_copy(&t->parms.laddr, &p->laddr);
+        ipv6_addr_copy(&t->parms.raddr, &p->raddr);
+        t->parms.flags = p->flags;
+        t->parms.hop_limit = p->hop_limit;
+        t->parms.encap_limit = p->encap_limit;
+        t->parms.flowinfo = p->flowinfo;
+        ip6ip6_tnl_link_config(t);
+        return 0;
+}
+
+/**
+ * ip6ip6_tnl_ioctl - configure ipv6 tunnels from userspace 
+ *   @dev: virtual device associated with tunnel
+ *   @ifr: parameters passed from userspace
+ *   @cmd: command to be performed
+ *
+ * Description:
+ *   ip6ip6_tnl_ioctl() is used for managing IPv6 tunnels 
+ *   from userspace. 
+ *
+ *   The possible commands are the following:
+ *     %SIOCGETTUNNEL: get tunnel parameters for device
+ *     %SIOCADDTUNNEL: add tunnel matching given tunnel parameters
+ *     %SIOCCHGTUNNEL: change tunnel parameters to those given
+ *     %SIOCDELTUNNEL: delete tunnel
+ *
+ *   The fallback device "ip6tnl0", created during module 
+ *   initialization, can be used for creating other tunnel devices.
+ *
+ * Return:
+ *   0 on success,
+ *   %-EFAULT if unable to copy data to or from userspace,
+ *   %-EPERM if current process hasn't %CAP_NET_ADMIN set
+ *   %-EINVAL if passed tunnel parameters are invalid,
+ *   %-EEXIST if changing a tunnel's parameters would cause a conflict
+ *   %-ENODEV if attempting to change or delete a nonexisting device
+ **/
+
+static int
+ip6ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
+{
+        int err = 0;
+        int create;
+        struct ip6_tnl_parm p;
+        struct ip6_tnl *t = NULL;
+
+        switch (cmd) {
+        case SIOCGETTUNNEL:
+                if (dev == ip6ip6_fb_tnl_dev) {
+                        if (copy_from_user(&p,
+                                           ifr->ifr_ifru.ifru_data,
+                                           sizeof (p))) {
+                                err = -EFAULT;
+                                break;
+                        }
+                        if ((err = ip6ip6_tnl_locate(&p, &t, 0)) == -ENODEV)
+                                t = (struct ip6_tnl *) dev->priv;
+                        else if (err)
+                                break;
+                } else
+                        t = (struct ip6_tnl *) 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;
+                create = (cmd == SIOCADDTUNNEL);
+                if (!capable(CAP_NET_ADMIN))
+                        break;
+                if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p))) {
+                        err = -EFAULT;
+                        break;
+                }
+                if (!create && dev != ip6ip6_fb_tnl_dev) {
+                        t = (struct ip6_tnl *) dev->priv;
+                }
+                if (!t && (err = ip6ip6_tnl_locate(&p, &t, create))) {
+                        break;
+                }
+                if (cmd == SIOCCHGTUNNEL) {
+                        if (t->dev != dev) {
+                                err = -EEXIST;
+                                break;
+                        }
+                        ip6ip6_tnl_unlink(t);
+                        err = ip6ip6_tnl_change(t, &p);
+                        ip6ip6_tnl_link(t);
+                        netdev_state_change(dev);
+                }
+                if (copy_to_user(ifr->ifr_ifru.ifru_data,
+                                 &t->parms, sizeof (p))) {
+                        err = -EFAULT;
+                } else {
+                        err = 0;
+                }
+                break;
+        case SIOCDELTUNNEL:
+                err = -EPERM;
+                if (!capable(CAP_NET_ADMIN))
+                        break;
+
+                if (dev == ip6ip6_fb_tnl_dev) {
+                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data,
+                                           sizeof (p))) {
+                                err = -EFAULT;
+                                break;
+                        }
+                        err = ip6ip6_tnl_locate(&p, &t, 0);
+                        if (err)
+                                break;
+                        if (t == ip6ip6_fb_tnl_dev->priv) {
+                                err = -EPERM;
+                                break;
+                        }
+                } else {
+                        t = (struct ip6_tnl *) dev->priv;
+                }
+                err = unregister_netdevice(t->dev);
+                break;
+        default:
+                err = -EINVAL;
+        }
+        return err;
+}
+
+/**
+ * ip6ip6_tnl_get_stats - return the stats for tunnel device 
+ *   @dev: virtual device associated with tunnel
+ *
+ * Return: stats for device
+ **/
+
+static struct net_device_stats *
+ip6ip6_tnl_get_stats(struct net_device *dev)
+{
+        return &(((struct ip6_tnl *) dev->priv)->stat);
+}
+
+/**
+ * ip6ip6_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
+ip6ip6_tnl_change_mtu(struct net_device *dev, int new_mtu)
+{
+        if (new_mtu < IPV6_MIN_MTU) {
+                return -EINVAL;
+        }
+        dev->mtu = new_mtu;
+        return 0;
+}
+
+/**
+ * ip6ip6_tnl_dev_setup - setup virtual tunnel device
+ *   @dev: virtual device associated with tunnel
+ *
+ * Description:
+ *   Initialize function pointers and device parameters
+ **/
+
+static void ip6ip6_tnl_dev_setup(struct net_device *dev)
+{
+        SET_MODULE_OWNER(dev);
+        dev->uninit = ip6ip6_tnl_dev_uninit;
+        dev->destructor = free_netdev;
+        dev->hard_start_xmit = ip6ip6_tnl_xmit;
+        dev->get_stats = ip6ip6_tnl_get_stats;
+        dev->do_ioctl = ip6ip6_tnl_ioctl;
+        dev->change_mtu = ip6ip6_tnl_change_mtu;
+
+        dev->type = ARPHRD_TUNNEL6;
+        dev->hard_header_len = LL_MAX_HEADER + sizeof (struct ipv6hdr);
+        dev->mtu = ETH_DATA_LEN - sizeof (struct ipv6hdr);
+        dev->flags |= IFF_NOARP;
+        dev->addr_len = sizeof(struct in6_addr);
+}
+
+
+/**
+ * ip6ip6_tnl_dev_init_gen - general initializer for all tunnel devices
+ *   @dev: virtual device associated with tunnel
+ **/
+
+static inline void
+ip6ip6_tnl_dev_init_gen(struct net_device *dev)
+{
+        struct ip6_tnl *t = (struct ip6_tnl *) dev->priv;
+        t->fl.proto = IPPROTO_IPV6;
+        t->dev = dev;
+        strcpy(t->parms.name, dev->name);
+}
+
+/**
+ * ip6ip6_tnl_dev_init - initializer for all non fallback tunnel devices
+ *   @dev: virtual device associated with tunnel
+ **/
+
+static int
+ip6ip6_tnl_dev_init(struct net_device *dev)
+{
+        struct ip6_tnl *t = (struct ip6_tnl *) dev->priv;
+        ip6ip6_tnl_dev_init_gen(dev);
+        ip6ip6_tnl_link_config(t);
+        return 0;
+}
+
+/**
+ * ip6ip6_fb_tnl_dev_init - initializer for fallback tunnel device
+ *   @dev: fallback device
+ *
+ * Return: 0
+ **/
+
+static int 
+ip6ip6_fb_tnl_dev_init(struct net_device *dev)
+{
+        struct ip6_tnl *t = dev->priv;
+        ip6ip6_tnl_dev_init_gen(dev);
+        dev_hold(dev);
+        tnls_wc[0] = t;
+        return 0;
+}
+
+static struct xfrm6_tunnel ip6ip6_handler = {
+        .handler = ip6ip6_rcv,
+        .err_handler = ip6ip6_err,
+};
+
+/**
+ * ip6_tunnel_init - register protocol and reserve needed resources
+ *
+ * Return: 0 on success
+ **/
+
+static int __init ip6_tunnel_init(void)
+{
+        int  err;
+
+        if (xfrm6_tunnel_register(&ip6ip6_handler) < 0) {
+                printk(KERN_ERR "ip6ip6 init: can't register tunnel\n");
+                return -EAGAIN;
+        }
+        ip6ip6_fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
+                                         ip6ip6_tnl_dev_setup);
+
+        if (!ip6ip6_fb_tnl_dev) {
+                err = -ENOMEM;
+                goto fail;
+        }
+        ip6ip6_fb_tnl_dev->init = ip6ip6_fb_tnl_dev_init;
+
+        if ((err = register_netdev(ip6ip6_fb_tnl_dev))) {
+                free_netdev(ip6ip6_fb_tnl_dev);
+                goto fail;
+        }
+        return 0;
+fail:
+        xfrm6_tunnel_deregister(&ip6ip6_handler);
+        return err;
+}
+
+/**
+ * ip6_tunnel_cleanup - free resources and unregister protocol
+ **/
+
+static void __exit ip6_tunnel_cleanup(void)
+{
+        if (xfrm6_tunnel_deregister(&ip6ip6_handler) < 0)
+                printk(KERN_INFO "ip6ip6 close: can't deregister tunnel\n");
+
+        unregister_netdev(ip6ip6_fb_tnl_dev);
+}
+
+module_init(ip6_tunnel_init);
+module_exit(ip6_tunnel_cleanup);