ipv6: allow routes to be configured with expire values

Add the support for adding expire value to routes,  requested by
Tom Gundersen <teg@jklm.no> for systemd-networkd, and NetworkManager
wants it too.

implement it by adding the new RTNETLINK attribute RTA_EXPIRES.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/rtnetlink.h

@@ -311,6 +311,7 @@ enum rtattr_type_t {
 	RTA_PREF,
 	RTA_ENCAP_TYPE,
 	RTA_ENCAP,
+	RTA_EXPIRES,
 	__RTA_MAX
 };
 

net/ipv6/route.c

@@ -2709,6 +2709,7 @@ static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
 	[RTA_PREF]              = { .type = NLA_U8 },
 	[RTA_ENCAP_TYPE]	= { .type = NLA_U16 },
 	[RTA_ENCAP]		= { .type = NLA_NESTED },
+	[RTA_EXPIRES]		= { .type = NLA_U32 },
 };
 
 static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -2809,6 +2810,15 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (tb[RTA_ENCAP_TYPE])
 		cfg->fc_encap_type = nla_get_u16(tb[RTA_ENCAP_TYPE]);
 
+	if (tb[RTA_EXPIRES]) {
+		unsigned long timeout = addrconf_timeout_fixup(nla_get_u32(tb[RTA_EXPIRES]), HZ);
+
+		if (addrconf_finite_timeout(timeout)) {
+			cfg->fc_expires = jiffies_to_clock_t(timeout * HZ);
+			cfg->fc_flags |= RTF_EXPIRES;
+		}
+	}
+
 	err = 0;
 errout:
 	return err;