net: add ARP notify option for devices

This adds another inet device option to enable gratuitous ARP
when device is brought up or address change. This is handy for
clusters or virtualization.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index c7712787933c1734c98a0191db23d9cb2886d0f8..ff3f219ee4d7bc590ecea9a9144c094f78f07dbd 100644 (file)
--- 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 06fcdb45106bb1a39c5c7606345cd3c0d8487743..acef2a770b6bce589b2cf6e84680e892b235a351 100644 (file)
--- 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 39d471d1163b4e8a54a95f56584f04e8a65a2d61..e76d3b22a46645b503283138b317ced96a0fbbef 100644 (file)
--- 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 fafeb48f27c046d0b6586e2797b40397a6a76f19..b38423ca711ad5ef191db6b74205c6cc945cc463 100644 (file)
--- 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 309997edc8a5169546e87ed2a51e51214e4bea6f..d519a6a6672634902f93459e0581e92a2af51f0b 100644 (file)
--- 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"),