net: Add compat ioctl support for the ipv4 multicast ioctl SIOCGETSGCNT

SIOCGETSGCNT is not a unique ioctl value as it it maps tio SIOCPROTOPRIVATE +1,
which unfortunately means the existing infrastructure for compat networking
ioctls is insufficient.  A trivial compact ioctl implementation would conflict
with:

SIOCAX25ADDUID
SIOCAIPXPRISLT
SIOCGETSGCNT_IN6
SIOCGETSGCNT
SIOCRSSCAUSE
SIOCX25SSUBSCRIP
SIOCX25SDTEFACILITIES

To make this work I have updated the compat_ioctl decode path to mirror the
the normal ioctl decode path.  I have added an ipv4 inet_compat_ioctl function
so that I can have ipv4 specific compat ioctls.   I have added a compat_ioctl
function into struct proto so I can break out ioctls by which kind of ip socket
I am using.  I have added a compat_raw_ioctl function because SIOCGETSGCNT only
works on raw sockets.  I have added a ipmr_compat_ioctl that mirrors the normal
ipmr_ioctl.

This was necessary because unfortunately the struct layout for the SIOCGETSGCNT
has unsigned longs in it so changes between 32bit and 64bit kernels.

This change was sufficient to run a 32bit ip multicast routing daemon on a
64bit kernel.

Reported-by: Bill Fenner <fenner@aristanetworks.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/mroute.h b/include/linux/mroute.h
index 0fa7a3a874c8..b21d567692b2 100644
--- a/include/linux/mroute.h
+++ b/include/linux/mroute.h
@@ -150,6 +150,7 @@ static inline int ip_mroute_opt(int opt)
 extern int ip_mroute_setsockopt(struct sock *, int, char __user *, unsigned int);
 extern int ip_mroute_getsockopt(struct sock *, int, char __user *, int __user *);
 extern int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg);
+extern int ipmr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg);
 extern int ip_mr_init(void);
 #else
 static inline