xfrm: Report user triggered expirations against the users socket

When a policy expiration is triggered from user space the request
travels through km_policy_expired and ultimately into
xfrm_exp_policy_notify which calls build_polexpire.  build_polexpire
uses the netlink port passed to km_policy_expired as the source port for
the netlink message it builds.

When a state expiration is triggered from user space the request travles
through km_state_expired and ultimately into xfrm_exp_state_notify which
calls build_expire.  build_expire uses the netlink port passed to
km_state_expired as the source port for the netlink message it builds.

Pass nlh->nlmsg_pid from the user generated netlink message that
requested the expiration to km_policy_expired and km_state_expired
instead of current->pid which is not a netlink port number.

Cc: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_user.c

@@ -1930,7 +1930,7 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 		// reset the timers here?
 		WARN(1, "Dont know what to do with soft policy expire\n");
 	}
-	km_policy_expired(xp, p->dir, up->hard, current->pid);
+	km_policy_expired(xp, p->dir, up->hard, nlh->nlmsg_pid);
 
 out:
 	xfrm_pol_put(xp);
@@ -1958,7 +1958,7 @@ static int xfrm_add_sa_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 	err = -EINVAL;
 	if (x->km.state != XFRM_STATE_VALID)
 		goto out;
-	km_state_expired(x, ue->hard, current->pid);
+	km_state_expired(x, ue->hard, nlh->nlmsg_pid);
 
 	if (ue->hard) {
 		uid_t loginuid = audit_get_loginuid(current);