Ipvlan should return an error when an address is already in use.

The ipvlan code already knows how to detect when a duplicate address is
about to be assigned to an ipvlan device.  However, that failure is not
propogated outward and leads to a silent failure.

Introduce a validation step at ip address creation time and allow device
drivers to register to validate the incoming ip addresses.  The ipvlan
code is the first consumer.  If it detects an address in use, we can
return an error to the user before beginning to commit the new ifa in
the networking code.

This can be especially useful if it is necessary to provision many
ipvlans in containers.  The provisioning software (or operator) can use
this to detect situations where an ip address is unexpectedly in use.

Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index a2e9d6ea1349..e7c04c4e4bcd 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -150,8 +150,15 @@ struct in_ifaddr {
         unsigned long           ifa_tstamp; /* updated timestamp */
 };
 
+struct in_validator_info {
+        __be32                  ivi_addr;
+        struct in_device        *ivi_dev;
+};
+
 int register_inetaddr_notifier(struct notifier_block *nb);
 int unregister_inetaddr_notifier(struct notifier_block *nb);
+int register_inetaddr_validator_notifier(struct notifier_block *nb);
+int unregister_inetaddr_validator_notifier(struct notifier_block *nb);
 
 void inet_netconf_notify_devconf(struct net *net, int event, int type,
                                  int ifindex, struct ipv4_devconf *devconf);