5 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index c7712787933c..ff3f219ee4d7 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -782,6 +782,12 @@ arp_ignore - INTEGER
         The max value from conf/{all,interface}/arp_ignore is used
         when ARP request is received on the {interface}
 
+arp_notify - BOOLEAN
+        Define mode for notification of address and device changes.
+        0 - (default): do nothing
+        1 - Generate gratuitous arp replies when device is brought up
+            or hardware address changes.
+
 arp_accept - BOOLEAN
         Define behavior when gratuitous arp replies are received:
         0 - drop gratuitous arp frames
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 06fcdb45106b..acef2a770b6b 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -108,6 +108,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
 #define IN_DEV_ARPFILTER(in_dev)        IN_DEV_ORCONF((in_dev), ARPFILTER)
 #define IN_DEV_ARP_ANNOUNCE(in_dev)     IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE)
 #define IN_DEV_ARP_IGNORE(in_dev)       IN_DEV_MAXCONF((in_dev), ARP_IGNORE)
+#define IN_DEV_ARP_NOTIFY(in_dev)       IN_DEV_MAXCONF((in_dev), ARP_NOTIFY)
 
 struct in_ifaddr
 {
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 39d471d1163b..e76d3b22a466 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -490,6 +490,7 @@ enum
         NET_IPV4_CONF_ARP_IGNORE=19,
         NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
         NET_IPV4_CONF_ARP_ACCEPT=21,
+        NET_IPV4_CONF_ARP_NOTIFY=22,
         __NET_IPV4_CONF_MAX
 };
 
diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index fafeb48f27c0..b38423ca711a 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -219,6 +219,7 @@ static const struct trans_ctl_table trans_net_ipv4_conf_vars_table[] = {
         { NET_IPV4_CONF_ARP_IGNORE,             "arp_ignore" },
         { NET_IPV4_CONF_PROMOTE_SECONDARIES,    "promote_secondaries" },
         { NET_IPV4_CONF_ARP_ACCEPT,             "arp_accept" },
+        { NET_IPV4_CONF_ARP_NOTIFY,             "arp_notify" },
         {}
 };
 
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 309997edc8a5..d519a6a66726 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1075,6 +1075,14 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
                         }
                 }
                 ip_mc_up(in_dev);
+                /* fall through */
+        case NETDEV_CHANGEADDR:
+                if (IN_DEV_ARP_NOTIFY(in_dev))
+                        arp_send(ARPOP_REQUEST, ETH_P_ARP,
+                                 in_dev->ifa_list->ifa_address,
+                                 dev,
+                                 in_dev->ifa_list->ifa_address,
+                                 NULL, dev->dev_addr, NULL);
                 break;
         case NETDEV_DOWN:
                 ip_mc_down(in_dev);
@@ -1439,6 +1447,7 @@ static struct devinet_sysctl_table {
                 DEVINET_SYSCTL_RW_ENTRY(ARP_ANNOUNCE, "arp_announce"),
                 DEVINET_SYSCTL_RW_ENTRY(ARP_IGNORE, "arp_ignore"),
                 DEVINET_SYSCTL_RW_ENTRY(ARP_ACCEPT, "arp_accept"),
+                DEVINET_SYSCTL_RW_ENTRY(ARP_NOTIFY, "arp_notify"),
 
                 DEVINET_SYSCTL_FLUSHING_ENTRY(NOXFRM, "disable_xfrm"),
                 DEVINET_SYSCTL_FLUSHING_ENTRY(NOPOLICY, "disable_policy"),