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[IPV6] IP6TUNNEL: Add support to IPv4 over IPv6 tunnel.
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Some notes
- Protocol number IPPROTO_IPIP is used for IPv4 over IPv6 packets.
- If IP6_TNL_F_USE_ORIG_TCLASS is set, TOS in IPv4 header is copied to
  Traffic Class in outer IPv6 header on xmit.
- IP6_TNL_F_USE_ORIG_FLOWLABEL is ignored on xmit of IPv4 packets, because
  IPv4 header does not have flow label.
- Kernel sends ICMP error if IPv4 packet is too big on xmit, even if
  DF flag is not set.

Signed-off-by: Yasuyuki Kozakai <[email protected]>
Signed-off-by: YOSHIFUJI Hideaki <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@yasuyuki5
yasuyuki5 authored and David S. Miller committed Apr 26, 2007
1 parent 61ec2ae commit c4d3efa
Showing 1 changed file with 185 additions and 5 deletions.
190 changes: 185 additions & 5 deletions net/ipv6/ip6_tunnel.c
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,15 @@
/*
* IPv6 over IPv6 tunnel device
* IPv6 tunneling device
* Linux INET6 implementation
*
* Authors:
* Ville Nuorvala <[email protected]>
* Yasuyuki Kozakai <[email protected]>
*
* $Id$
*
* Based on:
* linux/net/ipv6/sit.c
* linux/net/ipv6/sit.c and linux/net/ipv4/ipip.c
*
* RFC 2473
*
Expand All @@ -24,6 +25,7 @@
#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>
Expand All @@ -41,6 +43,7 @@
#include <asm/uaccess.h>
#include <asm/atomic.h>

#include <net/icmp.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
Expand All @@ -51,7 +54,7 @@
#include <net/inet_ecn.h>

MODULE_AUTHOR("Ville Nuorvala");
MODULE_DESCRIPTION("IPv6-in-IPv6 tunnel");
MODULE_DESCRIPTION("IPv6 tunneling device");
MODULE_LICENSE("GPL");

#define IPV6_TLV_TEL_DST_SIZE 8
Expand All @@ -63,6 +66,7 @@ MODULE_LICENSE("GPL");
#endif

#define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK)
#define IPV6_TCLASS_SHIFT 20

#define HASH_SIZE 32

Expand Down Expand Up @@ -469,6 +473,104 @@ ip6_tnl_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
return err;
}

static int
ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
int type, int code, int offset, __u32 info)
{
int rel_msg = 0;
int rel_type = type;
int rel_code = code;
__u32 rel_info = info;
int err;
struct sk_buff *skb2;
struct iphdr *eiph;
struct flowi fl;
struct rtable *rt;

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

if (rel_msg == 0)
return 0;

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

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

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

dst_release(skb2->dst);
skb2->dst = NULL;
skb_pull(skb2, offset);
skb2->nh.raw = skb2->data;
eiph = skb2->nh.iph;

/* Try to guess incoming interface */
memset(&fl, 0, sizeof(fl));
fl.fl4_dst = eiph->saddr;
fl.fl4_tos = RT_TOS(eiph->tos);
fl.proto = IPPROTO_IPIP;
if (ip_route_output_key(&rt, &fl))
goto out;

skb2->dev = rt->u.dst.dev;

/* route "incoming" packet */
if (rt->rt_flags & RTCF_LOCAL) {
ip_rt_put(rt);
rt = NULL;
fl.fl4_dst = eiph->daddr;
fl.fl4_src = eiph->saddr;
fl.fl4_tos = eiph->tos;
if (ip_route_output_key(&rt, &fl) ||
rt->u.dst.dev->type != ARPHRD_TUNNEL) {
ip_rt_put(rt);
goto out;
}
} else {
ip_rt_put(rt);
if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos,
skb2->dev) ||
skb2->dst->dev->type != ARPHRD_TUNNEL)
goto out;
}

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

skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
rel_info = htonl(rel_info);
}

icmp_send(skb2, rel_type, rel_code, rel_info);

out:
kfree_skb(skb2);
return 0;
}

static int
ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
int type, int code, int offset, __u32 info)
Expand Down Expand Up @@ -513,6 +615,19 @@ ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
return 0;
}

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

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

if (INET_ECN_is_ce(dsfield))
IP_ECN_set_ce(skb->nh.iph);
}

static void ip6ip6_dscp_ecn_decapsulate(struct ip6_tnl *t,
struct ipv6hdr *ipv6h,
struct sk_buff *skb)
Expand Down Expand Up @@ -605,6 +720,11 @@ static int ip6_tnl_rcv(struct sk_buff *skb, __u16 protocol,
return 0;
}

static int ip4ip6_rcv(struct sk_buff *skb)
{
return ip6_tnl_rcv(skb, ETH_P_IP, ip4ip6_dscp_ecn_decapsulate);
}

static int ip6ip6_rcv(struct sk_buff *skb)
{
return ip6_tnl_rcv(skb, ETH_P_IPV6, ip6ip6_dscp_ecn_decapsulate);
Expand Down Expand Up @@ -691,7 +811,7 @@ static inline int ip6_tnl_xmit_ctl(struct ip6_tnl *t)
* it.
*
* Return:
* 0
* 0 on success
* -1 fail
* %-EMSGSIZE message too big. return mtu in this case.
**/
Expand Down Expand Up @@ -808,6 +928,44 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
return err;
}

static inline int
ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct ip6_tnl *t = netdev_priv(dev);
struct iphdr *iph = skb->nh.iph;
int encap_limit = -1;
struct flowi fl;
__u8 dsfield;
__u32 mtu;
int err;

if (!ip6_tnl_xmit_ctl(t))
return -1;

if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
encap_limit = t->parms.encap_limit;

memcpy(&fl, &t->fl, sizeof (fl));
fl.proto = IPPROTO_IPIP;

dsfield = ipv4_get_dsfield(iph);

if ((t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS))
fl.fl6_flowlabel |= ntohl(((__u32)iph->tos << IPV6_TCLASS_SHIFT)
& IPV6_TCLASS_MASK);

err = ip6_tnl_xmit2(skb, dev, dsfield, &fl, encap_limit, &mtu);
if (err != 0) {
/* XXX: send ICMP error even if DF is not set. */
if (err == -EMSGSIZE)
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
return -1;
}

return 0;
}

static inline int
ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
{
Expand Down Expand Up @@ -867,6 +1025,9 @@ ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
}

switch (skb->protocol) {
case __constant_htons(ETH_P_IP):
ret = ip4ip6_tnl_xmit(skb, dev);
break;
case __constant_htons(ETH_P_IPV6):
ret = ip6ip6_tnl_xmit(skb, dev);
break;
Expand Down Expand Up @@ -1199,6 +1360,12 @@ ip6ip6_fb_tnl_dev_init(struct net_device *dev)
return 0;
}

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

static struct xfrm6_tunnel ip6ip6_handler = {
.handler = ip6ip6_rcv,
.err_handler = ip6ip6_err,
Expand All @@ -1215,9 +1382,16 @@ static int __init ip6_tunnel_init(void)
{
int err;

if (xfrm6_tunnel_register(&ip4ip6_handler, AF_INET)) {
printk(KERN_ERR "ip4ip6 init: can't register tunnel\n");
err = -EAGAIN;
goto out;
}

if (xfrm6_tunnel_register(&ip6ip6_handler, AF_INET6)) {
printk(KERN_ERR "ip6ip6 init: can't register tunnel\n");
return -EAGAIN;
err = -EAGAIN;
goto unreg_ip4ip6;
}
ip6ip6_fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
ip6ip6_tnl_dev_setup);
Expand All @@ -1235,6 +1409,9 @@ static int __init ip6_tunnel_init(void)
return 0;
fail:
xfrm6_tunnel_deregister(&ip6ip6_handler, AF_INET6);
unreg_ip4ip6:
xfrm6_tunnel_deregister(&ip4ip6_handler, AF_INET);
out:
return err;
}

Expand All @@ -1258,6 +1435,9 @@ static void __exit ip6ip6_destroy_tunnels(void)

static void __exit ip6_tunnel_cleanup(void)
{
if (xfrm6_tunnel_deregister(&ip4ip6_handler, AF_INET))
printk(KERN_INFO "ip4ip6 close: can't deregister tunnel\n");

if (xfrm6_tunnel_deregister(&ip6ip6_handler, AF_INET6))
printk(KERN_INFO "ip6ip6 close: can't deregister tunnel\n");

Expand Down

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