[RFC net-next 10/14] tun: set tx path XDP program

[Prashant Bhole <prashantbhole.linux@gmail.com>]

From: David Ahern <dahern@digitalocean.com>

This patch adds a way to set tx path XDP program in tun driver
by handling XDP_SETUP_PROG_TX and XDP_QUERY_PROG_TX in ndo_bpf
handler.

Signed-off-by: David Ahern <dahern@digitalocean.com>
Signed-off-by: Prashant Bhole <prashantbhole.linux@gmail.com>
---
 drivers/net/tun.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d078b4659897..8aee7abd53a2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -239,6 +239,7 @@ struct tun_struct {
 	u32 rx_batched;
 	struct tun_pcpu_stats __percpu *pcpu_stats;
 	struct bpf_prog __rcu *xdp_prog;
+	struct bpf_prog __rcu *xdp_tx_prog;
 	struct tun_prog __rcu *steering_prog;
 	struct tun_prog __rcu *filter_prog;
 	struct ethtool_link_ksettings link_ksettings;
@@ -1189,15 +1190,21 @@ tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 }
 
 static int tun_xdp_set(struct net_device *dev, struct bpf_prog *prog,
-		       struct netlink_ext_ack *extack)
+		       bool tx, struct netlink_ext_ack *extack)
 {
 	struct tun_struct *tun = netdev_priv(dev);
 	struct tun_file *tfile;
 	struct bpf_prog *old_prog;
 	int i;
 
-	old_prog = rtnl_dereference(tun->xdp_prog);
-	rcu_assign_pointer(tun->xdp_prog, prog);
+	if (tx) {
+		old_prog = rtnl_dereference(tun->xdp_tx_prog);
+		rcu_assign_pointer(tun->xdp_tx_prog, prog);
+	} else {
+		old_prog = rtnl_dereference(tun->xdp_prog);
+		rcu_assign_pointer(tun->xdp_prog, prog);
+	}
+
 	if (old_prog)
 		bpf_prog_put(old_prog);
 
@@ -1218,12 +1225,16 @@ static int tun_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 	return 0;
 }
 
-static u32 tun_xdp_query(struct net_device *dev)
+static u32 tun_xdp_query(struct net_device *dev, bool tx)
 {
 	struct tun_struct *tun = netdev_priv(dev);
 	const struct bpf_prog *xdp_prog;
 
-	xdp_prog = rtnl_dereference(tun->xdp_prog);
+	if (tx)
+		xdp_prog = rtnl_dereference(tun->xdp_tx_prog);
+	else
+		xdp_prog = rtnl_dereference(tun->xdp_prog);
+
 	if (xdp_prog)
 		return xdp_prog->aux->id;
 
@@ -1234,13 +1245,20 @@ static int tun_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 {
 	switch (xdp->command) {
 	case XDP_SETUP_PROG:
-		return tun_xdp_set(dev, xdp->prog, xdp->extack);
+		return tun_xdp_set(dev, xdp->prog, false, xdp->extack);
+	case XDP_SETUP_PROG_TX:
+		return tun_xdp_set(dev, xdp->prog, true, xdp->extack);
 	case XDP_QUERY_PROG:
-		xdp->prog_id = tun_xdp_query(dev);
-		return 0;
+		xdp->prog_id = tun_xdp_query(dev, false);
+		break;
+	case XDP_QUERY_PROG_TX:
+		xdp->prog_id = tun_xdp_query(dev, true);
+		break;
 	default:
 		return -EINVAL;
 	}
+
+	return 0;
 }
 
 static int tun_net_change_carrier(struct net_device *dev, bool new_carrier)
-- 
2.21.0