net ipv6: Prevent neighbor add if protocol is disabled on device
Disabling IPv6 on an interface removes existing entries but nothing prevents
new entries from being manually added. To that end, add a new neigh_table
operation, allow_add, that is called on RTM_NEWNEIGH to see if neighbor
entries are allowed on a given device. If IPv6 is disabled on the device,
allow_add returns false and passes a message back to the user via extack.
$ echo 1 > /proc/sys/net/ipv6/conf/eth1/disable_ipv6
$ ip -6 neigh add fe80::4c88:bff:fe21:2704 dev eth1 lladdr de:ad:be:ef:01:01
Error: IPv6 is disabled on this device.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 3e5438b..50a67bd 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -205,6 +205,8 @@ struct neigh_table {
int (*pconstructor)(struct pneigh_entry *);
void (*pdestructor)(struct pneigh_entry *);
void (*proxy_redo)(struct sk_buff *skb);
+ bool (*allow_add)(const struct net_device *dev,
+ struct netlink_ext_ack *extack);
char *id;
struct neigh_parms parms;
struct list_head parms_list;