[IPV4]: Primary and secondary addresses

Add an option to make secondary IP addresses get promoted
when primary IP addresses are removed from the device.
It defaults to off to preserve existing behavior.

Signed-off-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 6fafb27877a7d5adbac3b0419f82a37eed1fc9c7..7e1e15f934f340851c503c789e701724d81bcb0c 100644 (file)
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -29,6 +29,7 @@ struct ipv4_devconf
        int     no_xfrm;
        int     no_policy;
        int     force_igmp_version;
+       int     promote_secondaries;
        void    *sysctl;
 };
 
@@ -71,6 +72,7 @@ struct in_device
 #define IN_DEV_SEC_REDIRECTS(in_dev)   (ipv4_devconf.secure_redirects || (in_dev)->cnf.secure_redirects)
 #define IN_DEV_IDTAG(in_dev)           ((in_dev)->cnf.tag)
 #define IN_DEV_MEDIUM_ID(in_dev)       ((in_dev)->cnf.medium_id)
+#define IN_DEV_PROMOTE_SECONDARIES(in_dev)     (ipv4_devconf.promote_secondaries || (in_dev)->cnf.promote_secondaries)
 
 #define IN_DEV_RX_REDIRECTS(in_dev) \
        ((IN_DEV_FORWARD(in_dev) && \

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 772998147e3ef989988c184520f6dacba9fb601d..23032d9d607154fd48e41422f346c3ddcb8e72e6 100644 (file)
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -399,6 +399,7 @@ enum
        NET_IPV4_CONF_FORCE_IGMP_VERSION=17,
        NET_IPV4_CONF_ARP_ANNOUNCE=18,
        NET_IPV4_CONF_ARP_IGNORE=19,
+       NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
        __NET_IPV4_CONF_MAX
 };
 

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 3cc96730c4ed285d4a1f65e69ca659290b26abe0..478a30179a527149a837bf1092e1cda0b704456f 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -233,11 +233,14 @@ int inet_addr_onlink(struct in_device *in_dev, u32 a, u32 b)
 static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
                         int destroy)
 {
+       struct in_ifaddr *promote = NULL;
        struct in_ifaddr *ifa1 = *ifap;
 
        ASSERT_RTNL();
 
-       /* 1. Deleting primary ifaddr forces deletion all secondaries */
+       /* 1. Deleting primary ifaddr forces deletion all secondaries 
+        * unless alias promotion is set
+        **/
 
        if (!(ifa1->ifa_flags & IFA_F_SECONDARY)) {
                struct in_ifaddr *ifa;
@@ -251,11 +254,16 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
                                continue;
                        }
 
-                       *ifap1 = ifa->ifa_next;
+                       if (!IN_DEV_PROMOTE_SECONDARIES(in_dev)) {
+                               *ifap1 = ifa->ifa_next;
 
-                       rtmsg_ifa(RTM_DELADDR, ifa);
-                       notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa);
-                       inet_free_ifa(ifa);
+                               rtmsg_ifa(RTM_DELADDR, ifa);
+                               notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa);
+                               inet_free_ifa(ifa);
+                       } else {
+                               promote = ifa;
+                               break;
+                       }
                }
        }
 
@@ -281,6 +289,13 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
                if (!in_dev->ifa_list)
                        inetdev_destroy(in_dev);
        }
+
+       if (promote && IN_DEV_PROMOTE_SECONDARIES(in_dev)) {
+               /* not sure if we should send a delete notify first? */
+               promote->ifa_flags &= ~IFA_F_SECONDARY;
+               rtmsg_ifa(RTM_NEWADDR, promote);
+               notifier_call_chain(&inetaddr_chain, NETDEV_UP, promote);
+       }
 }
 
 static int inet_insert_ifa(struct in_ifaddr *ifa)
@@ -1384,6 +1399,15 @@ static struct devinet_sysctl_table {
                        .proc_handler   = &ipv4_doint_and_flush,
                        .strategy       = &ipv4_doint_and_flush_strategy,
                },
+               {
+                       .ctl_name       = NET_IPV4_CONF_PROMOTE_SECONDARIES,
+                       .procname       = "promote_secondaries",
+                       .data           = &ipv4_devconf.promote_secondaries,
+                       .maxlen         = sizeof(int),
+                       .mode           = 0644,
+                       .proc_handler   = &ipv4_doint_and_flush,
+                       .strategy       = &ipv4_doint_and_flush_strategy,
+               },
        },
        .devinet_dev = {
                {