netlink: Implment netlink_broadcast_filtered

When netlink sockets are used to convey data that is in a namespace
we need a way to select a subset of the listening sockets to deliver
the packet to.  For the network namespace we have been doing this
by only transmitting packets in the correct network namespace.

For data belonging to other namespaces netlink_bradcast_filtered
provides a mechanism that allows us to examine the destination
socket and to decide if we should transmit the specified packet
to it.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 6eaca5e1e8ca..59d066936ab9 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -188,6 +188,10 @@ extern int netlink_has_listeners(struct sock *sk, unsigned int group);
 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);
 extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 pid,
                              __u32 group, gfp_t allocation);
+extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
+        __u32 pid, __u32 group, gfp_t allocation,
+        int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
+        void *filter_data);
 extern int netlink_set_err(struct sock *ssk, __u32 pid, __u32 group, int code);
 extern int netlink_register_notifier(struct notifier_block *nb);
 extern int netlink_unregister_notifier(struct notifier_block *nb);