[INET]: Introduce tunnel4/tunnel6

Basically this patch moves the generic tunnel protocol stuff out of
xfrm4_tunnel/xfrm6_tunnel and moves it into the new files of tunnel4.c
and tunnel6 respectively.

The reason for this is that the problem that Hugo uncovered is only
the tip of the iceberg.  The real problem is that when we removed the
dependency of ipip on xfrm4_tunnel we didn't really consider the module
case at all.

For instance, as it is it's possible to build both ipip and xfrm4_tunnel
as modules and if the latter is loaded then ipip simply won't load.

After considering the alternatives I've decided that the best way out of
this is to restore the dependency of ipip on the non-xfrm-specific part
of xfrm4_tunnel.  This is acceptable IMHO because the intention of the
removal was really to be able to use ipip without the xfrm subsystem.
This is still preserved by this patch.

So now both ipip/xfrm4_tunnel depend on the new tunnel4.c which handles
the arbitration between the two.  The order of processing is determined
by a simple integer which ensures that ipip gets processed before
xfrm4_tunnel.

The situation for ICMP handling is a little bit more complicated since
we may not have enough information to determine who it's for.  It's not
a big deal at the moment since the xfrm ICMP handlers are basically
no-ops.  In future we can deal with this when we look at ICMP caching
in general.

The user-visible change to this is the removal of the TUNNEL Kconfig
prompts.  This makes sense because it can only be used through IPCOMP
as it stands.

The addition of the new modules shouldn't introduce any problems since
module dependency will cause them to be loaded.

Oh and I also turned some unnecessary pskb's in IPv6 related to this
patch to skb's.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 35 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 48597538db3..ff9040c9255 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -44,7 +44,6 @@
 
 #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>
@@ -391,7 +390,7 @@ parse_tlv_tnl_enc_lim(struct sk_buff *skb, __u8 * raw)
  *   to the specifications in RFC 2473.
  **/
 
-static void 
+static int
 ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	   int type, int code, int offset, __u32 info)
 {
@@ -402,6 +401,7 @@ ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	int rel_code = ICMPV6_ADDR_UNREACH;
 	__u32 rel_info = 0;
 	__u16 len;
+	int err = -ENOENT;
 
 	/* If the packet doesn't contain the original IPv6 header we are 
 	   in trouble since we might need the source address for further 
@@ -411,6 +411,8 @@ ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	if ((t = ip6ip6_tnl_lookup(&ipv6h->daddr, &ipv6h->saddr)) == NULL)
 		goto out;
 
+	err = 0;
+
 	switch (type) {
 		__u32 teli;
 		struct ipv6_tlv_tnl_enc_lim *tel;
@@ -492,6 +494,7 @@ ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	}
 out:
 	read_unlock(&ip6ip6_lock);
+	return err;
 }
 
 static inline void ip6ip6_ecn_decapsulate(struct ipv6hdr *outer_iph,
@@ -511,9 +514,8 @@ static inline void ip6ip6_ecn_decapsulate(struct ipv6hdr *outer_iph,
  **/
 
 static int 
-ip6ip6_rcv(struct sk_buff **pskb)
+ip6ip6_rcv(struct sk_buff *skb)
 {
-	struct sk_buff *skb = *pskb;
 	struct ipv6hdr *ipv6h;
 	struct ip6_tnl *t;
 
@@ -1112,39 +1114,12 @@ ip6ip6_fb_tnl_dev_init(struct net_device *dev)
 	return 0;
 }
 
-#ifdef CONFIG_INET6_TUNNEL
 static struct xfrm6_tunnel ip6ip6_handler = {
 	.handler	= ip6ip6_rcv,
 	.err_handler	= ip6ip6_err,
+	.priority	=	1,
 };
 
-static inline int ip6ip6_register(void)
-{
-	return xfrm6_tunnel_register(&ip6ip6_handler);
-}
-
-static inline int ip6ip6_unregister(void)
-{
-	return xfrm6_tunnel_deregister(&ip6ip6_handler);
-}
-#else
-static struct inet6_protocol xfrm6_tunnel_protocol = {
-	.handler	= ip6ip6_rcv,
-	.err_handler	= ip6ip6_err,
-	.flags		= INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
-};
-
-static inline int ip6ip6_register(void)
-{
-	return inet6_add_protocol(&xfrm6_tunnel_protocol, IPPROTO_IPV6);
-}
-
-static inline int ip6ip6_unregister(void)
-{
-	return inet6_del_protocol(&xfrm6_tunnel_protocol, IPPROTO_IPV6);
-}
-#endif
-
 /**
  * ip6_tunnel_init - register protocol and reserve needed resources
  *
@@ -1155,7 +1130,7 @@ static int __init ip6_tunnel_init(void)
 {
 	int  err;
 
-	if (ip6ip6_register() < 0) {
+	if (xfrm6_tunnel_register(&ip6ip6_handler)) {
 		printk(KERN_ERR "ip6ip6 init: can't register tunnel\n");
 		return -EAGAIN;
 	}
@@ -1174,7 +1149,7 @@ static int __init ip6_tunnel_init(void)
 	}
 	return 0;
 fail:
-	ip6ip6_unregister();
+	xfrm6_tunnel_deregister(&ip6ip6_handler);
 	return err;
 }
 
@@ -1184,7 +1159,7 @@ fail:
 
 static void __exit ip6_tunnel_cleanup(void)
 {
-	if (ip6ip6_unregister() < 0)
+	if (xfrm6_tunnel_deregister(&ip6ip6_handler))
 		printk(KERN_INFO "ip6ip6 close: can't deregister tunnel\n");
 
 	unregister_netdev(ip6ip6_fb_tnl_dev);