ipv4: introduce address lifetime

There are some usecase when lifetime of ipv4 addresses might be helpful.
For example:
1) initramfs networkmanager uses a DHCP daemon to learn network
configuration parameters
2) initramfs networkmanager addresses, routes and DNS configuration
3) initramfs networkmanager is requested to stop
4) initramfs networkmanager stops all daemons including dhclient
5) there are addresses and routes configured but no daemon running. If
the system doesn't start networkmanager for some reason, addresses and
routes will be used forever, which violates RFC 2131.

This patch is essentially a backport of ivp6 address lifetime mechanism
for ipv4 addresses.

Current "ip" tool supports this without any patch (since it does not
distinguish between ipv4 and ipv6 addresses in this perspective.

Also, this should be back-compatible with all current netlink users.

Reported-by: Pavel Šimerda <psimerda@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index a9d828976a77..ea1e3b863890 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -166,6 +166,12 @@ struct in_ifaddr {
         unsigned char           ifa_flags;
         unsigned char           ifa_prefixlen;
         char                    ifa_label[IFNAMSIZ];
+
+        /* In seconds, relative to tstamp. Expiry is at tstamp + HZ * lft. */
+        __u32                   ifa_valid_lft;
+        __u32                   ifa_preferred_lft;
+        unsigned long           ifa_cstamp; /* created timestamp */
+        unsigned long           ifa_tstamp; /* updated timestamp */
 };
 
 extern int register_inetaddr_notifier(struct notifier_block *nb);