[IPV6] MIP6: Loadable module support for MIPv6.

This patch makes MIPv6 loadable module named "mip6".

Here is a modprobe.conf(5) example to load it automatically
when user application uses XFRM state for MIPv6:

alias xfrm-type-10-43 mip6
alias xfrm-type-10-60 mip6

Some MIPv6 feature is not included by this modular, however,
it should not be affected to other features like either IPsec
or IPv6 with and without the patch.
We may discuss XFRM, MH (RAW socket) and ancillary data/sockopt
separately for future work.

Loadable features:
* MH receiving check (to send ICMP error back)
* RO header parsing and building (i.e. RH2 and HAO in DSTOPTS)
* XFRM policy/state database handling for RO

These are NOT covered as loadable:
* Home Address flags and its rule on source address selection
* XFRM sub policy (depends on its own kernel option)
* XFRM functions to receive RO as IPv6 extension header
* MH sending/receiving through raw socket if user application
  opens it (since raw socket allows to do so)
* RH2 sending as ancillary data
* RH2 operation with setsockopt(2)

Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 3 deletions

diff --git a/net/ipv6/mip6.c b/net/ipv6/mip6.c
index 13b7160fb892..20c78ecff6a1 100644
--- a/net/ipv6/mip6.c
+++ b/net/ipv6/mip6.c
@@ -30,6 +30,7 @@
 #include <net/sock.h>
 #include <net/ipv6.h>
 #include <net/ip6_checksum.h>
+#include <net/rawv6.h>
 #include <net/xfrm.h>
 #include <net/mip6.h>
 
@@ -86,7 +87,7 @@ static int mip6_mh_len(int type)
         return len;
 }
 
-int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
+static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
 {
         struct ip6_mh *mh;
 
@@ -471,7 +472,7 @@ static struct xfrm_type mip6_rthdr_type =
         .remote_addr    = mip6_xfrm_addr,
 };
 
-int __init mip6_init(void)
+static int __init mip6_init(void)
 {
         printk(KERN_INFO "Mobile IPv6\n");
 
@@ -483,18 +484,33 @@ int __init mip6_init(void)
                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
                 goto mip6_rthdr_xfrm_fail;
         }
+        if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
+                printk(KERN_INFO "%s: can't add rawv6 mh filter\n", __FUNCTION__);
+                goto mip6_rawv6_mh_fail;
+        }
+
+
         return 0;
 
+ mip6_rawv6_mh_fail:
+        xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
  mip6_rthdr_xfrm_fail:
         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
  mip6_destopt_xfrm_fail:
         return -EAGAIN;
 }
 
-void __exit mip6_fini(void)
+static void __exit mip6_fini(void)
 {
+        if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
+                printk(KERN_INFO "%s: can't remove rawv6 mh filter\n", __FUNCTION__);
         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
 }
+
+module_init(mip6_init);
+module_exit(mip6_fini);
+
+MODULE_LICENSE("GPL");