ipv6: enable IPV6_FLOWLABEL_MGR for getsockopt

It is already possible to set/put/renew a label
with IPV6_FLOWLABEL_MGR and setsockopt. This patch
add the possibility to get information about this
label (current value, time before expiration, etc).

It helps application to take decision for a renew
or a release of the label.

v2:
 * Add spin_lock to prevent race condition
 * return -ENOENT if no result found
 * check if flr_action is GET

v3:
 * move the spin_lock to protect only the
   relevant code

Signed-off-by: Florent Fourcot <florent.fourcot@enst-bretagne.fr>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 0 deletions

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index 819578e..4a06ed0 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -475,6 +475,32 @@ static inline void fl_link(struct ipv6_pinfo *np, struct ipv6_fl_socklist *sfl,
 	spin_unlock_bh(&ip6_sk_fl_lock);
 }
 
+int ipv6_flowlabel_opt_get(struct sock *sk, struct in6_flowlabel_req *freq)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct ipv6_fl_socklist *sfl;
+
+	rcu_read_lock_bh();
+
+	for_each_sk_fl_rcu(np, sfl) {
+		if (sfl->fl->label == (np->flow_label & IPV6_FLOWLABEL_MASK)) {
+			spin_lock_bh(&ip6_fl_lock);
+			freq->flr_label = sfl->fl->label;
+			freq->flr_dst = sfl->fl->dst;
+			freq->flr_share = sfl->fl->share;
+			freq->flr_expires = (sfl->fl->expires - jiffies) / HZ;
+			freq->flr_linger = sfl->fl->linger / HZ;
+
+			spin_unlock_bh(&ip6_fl_lock);
+			rcu_read_unlock_bh();
+			return 0;
+		}
+	}
+	rcu_read_unlock_bh();
+
+	return -ENOENT;
+}
+
 int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 {
 	int uninitialized_var(err);