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, 16 insertions, 0 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index f2b6110..45b89d7 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -880,6 +880,19 @@ int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 }
 EXPORT_SYMBOL(inet_ioctl);
 
+#ifdef CONFIG_COMPAT
+int inet_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	struct sock *sk = sock->sk;
+	int err = -ENOIOCTLCMD;
+
+	if (sk->sk_prot->compat_ioctl)
+		err = sk->sk_prot->compat_ioctl(sk, cmd, arg);
+
+	return err;
+}
+#endif
+
 const struct proto_ops inet_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
@@ -903,6 +916,7 @@ const struct proto_ops inet_stream_ops = {
 #ifdef CONFIG_COMPAT
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
+	.compat_ioctl	   = inet_compat_ioctl,
 #endif
 };
 EXPORT_SYMBOL(inet_stream_ops);
@@ -929,6 +943,7 @@ const struct proto_ops inet_dgram_ops = {
 #ifdef CONFIG_COMPAT
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
+	.compat_ioctl	   = inet_compat_ioctl,
 #endif
 };
 EXPORT_SYMBOL(inet_dgram_ops);
@@ -959,6 +974,7 @@ static const struct proto_ops inet_sockraw_ops = {
 #ifdef CONFIG_COMPAT
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
+	.compat_ioctl	   = inet_compat_ioctl,
 #endif
 };