[XFRM] IPV6: Update outbound state timestamp for each sending.

With this patch transformation state is updated last used time
for each sending. Xtime is used for it like other state lifetime
expiration.
Mobile IPv6 enabled nodes will want to know traffic status of each
binding (e.g. judgement to request binding refresh by correspondent node,
or to keep home/care-of nonce alive by mobile node).
The last used timestamp is an important hint about it.
Based on MIPL2 kernel patch.

This patch was also written by: Henrik Petander <petander@tcs.hut.fi>
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/xfrm.h

@@ -236,6 +236,7 @@ enum xfrm_attr_type_t {
 	XFRMA_ETIMER_THRESH,
 	XFRMA_SRCADDR,		/* xfrm_address_t */
 	XFRMA_COADDR,		/* xfrm_address_t */
+	XFRMA_LASTUSED,
 	__XFRMA_MAX
 
 #define XFRMA_MAX (__XFRMA_MAX - 1)

include/net/xfrm.h

@@ -167,6 +167,9 @@ struct xfrm_state
 	struct xfrm_lifetime_cur curlft;
 	struct timer_list	timer;
 
+	/* Last used time */
+	u64			lastused;
+
 	/* Reference to data common to all the instances of this
 	 * transformer. */
 	struct xfrm_type	*type;

net/ipv6/xfrm6_output.c

@@ -75,6 +75,8 @@ static int xfrm6_output_one(struct sk_buff *skb)
 
 		x->curlft.bytes += skb->len;
 		x->curlft.packets++;
+		if (x->props.mode == XFRM_MODE_ROUTEOPTIMIZATION)
+			x->lastused = (u64)xtime.tv_sec;
 
 		spin_unlock_bh(&x->lock);
 

net/xfrm/xfrm_user.c

@@ -595,6 +595,9 @@ static int dump_one_state(struct xfrm_state *x, int count, void *ptr)
 	if (x->coaddr)
 		RTA_PUT(skb, XFRMA_COADDR, sizeof(*x->coaddr), x->coaddr);
 
+	if (x->lastused)
+		RTA_PUT(skb, XFRMA_LASTUSED, sizeof(x->lastused), &x->lastused);
+
 	nlh->nlmsg_len = skb->tail - b;
 out:
 	sp->this_idx++;