ipv6: flush nd cache on IFF_NOARP change

This patch is the IPv6 equivalent of commit
6c8b4e3ff81b ("arp: flush arp cache on IFF_NOARP change")

Without it, we keep buggy neighbours in the cache, with destination
MAC address equal to our own MAC address.

Tested:
 tcpdump -i eth0 -s 0 ip6 -n -e &
 ip link set dev eth0 arp off
 ping6 remote   // sends buggy frames
 ip link set dev eth0 arp on
 ping6 remote   // should work once kernel is patched

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Mario Fanelli <mariofanelli@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 0a05b35a90fc946dc0de3ae76e4a682ca4438932..c53331cfed95dcbb6672b80282125516e904a84f 100644 (file)
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1650,6 +1650,7 @@ int ndisc_rcv(struct sk_buff *skb)
 static int ndisc_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
 {
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+       struct netdev_notifier_change_info *change_info;
        struct net *net = dev_net(dev);
        struct inet6_dev *idev;
 
@@ -1664,6 +1665,11 @@ static int ndisc_netdev_event(struct notifier_block *this, unsigned long event,
                        ndisc_send_unsol_na(dev);
                in6_dev_put(idev);
                break;
+       case NETDEV_CHANGE:
+               change_info = ptr;
+               if (change_info->flags_changed & IFF_NOARP)
+                       neigh_changeaddr(&nd_tbl, dev);
+               break;
        case NETDEV_DOWN:
                neigh_ifdown(&nd_tbl, dev);
                fib6_run_gc(0, net, false);