net: Add support for fill_slave_info to VRF device

Allows userspace to have direct access to VRF table association
versus looking up master device and its table.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -877,6 +877,24 @@ static int vrf_fillinfo(struct sk_buff *skb,
 	return nla_put_u32(skb, IFLA_VRF_TABLE, vrf->tb_id);
 }
 
+static size_t vrf_get_slave_size(const struct net_device *bond_dev,
+				 const struct net_device *slave_dev)
+{
+	return nla_total_size(sizeof(u32));  /* IFLA_VRF_PORT_TABLE */
+}
+
+static int vrf_fill_slave_info(struct sk_buff *skb,
+			       const struct net_device *vrf_dev,
+			       const struct net_device *slave_dev)
+{
+	struct net_vrf *vrf = netdev_priv(vrf_dev);
+
+	if (nla_put_u32(skb, IFLA_VRF_PORT_TABLE, vrf->tb_id))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 static const struct nla_policy vrf_nl_policy[IFLA_VRF_MAX + 1] = {
 	[IFLA_VRF_TABLE] = { .type = NLA_U32 },
 };
@@ -890,6 +908,9 @@ static struct rtnl_link_ops vrf_link_ops __read_mostly = {
 	.validate	= vrf_validate,
 	.fill_info	= vrf_fillinfo,
 
+	.get_slave_size  = vrf_get_slave_size,
+	.fill_slave_info = vrf_fill_slave_info,
+
 	.newlink	= vrf_newlink,
 	.dellink	= vrf_dellink,
 	.setup		= vrf_setup,

include/uapi/linux/if_link.h

@@ -405,6 +405,14 @@ enum {
 
 #define IFLA_VRF_MAX (__IFLA_VRF_MAX - 1)
 
+enum {
+	IFLA_VRF_PORT_UNSPEC,
+	IFLA_VRF_PORT_TABLE,
+	__IFLA_VRF_PORT_MAX
+};
+
+#define IFLA_VRF_PORT_MAX (__IFLA_VRF_PORT_MAX - 1)
+
 /* IPVLAN section */
 enum {
 	IFLA_IPVLAN_UNSPEC,