netlink: make socket filters work on netlink

Make socket filters work for netlink unicast and notifications.
This is useful for applications like Zebra that get overrun with
messages that are then ignored.

Note: netlink messages are in host byte order, but packet filter
state machine operations are done as network byte order.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 524e826bb976ad9c26c1bd0f07fae77147e624ae..86bd8660a8f2789c5e1ec83c1f66c1b8c9131bd4 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -886,6 +886,13 @@ retry:
        if (netlink_is_kernel(sk))
                return netlink_unicast_kernel(sk, skb);
 
+       if (sk_filter(sk, skb)) {
+               int err = skb->len;
+               kfree_skb(skb);
+               sock_put(sk);
+               return err;
+       }
+
        err = netlink_attachskb(sk, skb, nonblock, &timeo, ssk);
        if (err == 1)
                goto retry;
@@ -980,6 +987,9 @@ static inline int do_one_broadcast(struct sock *sk,
                netlink_overrun(sk);
                /* Clone failed. Notify ALL listeners. */
                p->failure = 1;
+       } else if (sk_filter(sk, p->skb2)) {
+               kfree_skb(p->skb2);
+               p->skb2 = NULL;
        } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
                netlink_overrun(sk);
        } else {
@@ -1533,8 +1543,13 @@ static int netlink_dump(struct sock *sk)
 
        if (len > 0) {
                mutex_unlock(nlk->cb_mutex);
-               skb_queue_tail(&sk->sk_receive_queue, skb);
-               sk->sk_data_ready(sk, len);
+
+               if (sk_filter(sk, skb))
+                       kfree_skb(skb);
+               else {
+                       skb_queue_tail(&sk->sk_receive_queue, skb);
+                       sk->sk_data_ready(sk, skb->len);
+               }
                return 0;
        }
 
@@ -1544,8 +1559,12 @@ static int netlink_dump(struct sock *sk)
 
        memcpy(nlmsg_data(nlh), &len, sizeof(len));
 
-       skb_queue_tail(&sk->sk_receive_queue, skb);
-       sk->sk_data_ready(sk, skb->len);
+       if (sk_filter(sk, skb))
+               kfree_skb(skb);
+       else {
+               skb_queue_tail(&sk->sk_receive_queue, skb);
+               sk->sk_data_ready(sk, skb->len);
+       }
 
        if (cb->done)
                cb->done(cb);