[PATCH RFC v4 bpf-next 01/11] net: Add XDP setup and query commands for Tx programs

[David Ahern <dsahern@kernel.org>]

From: David Ahern <dahern@digitalocean.com>

Add new netdev commands, XDP_SETUP_PROG_EGRESS and
XDP_QUERY_PROG_EGRESS.

Update dev_change_xdp_fd and dev_xdp_install to take an egress argument.
If egress bool is set, then use XDP_SETUP_PROG_EGRESS in dev_xdp_install
and XDP_QUERY_PROG_EGRESS in dev_change_xdp_fd.

Update dev_xdp_uninstall to query for XDP_QUERY_PROG_EGRESS and if a
program is installed call dev_xdp_install with the egress argument set
to true.

This enables existing infrastructure to be used for XDP programs in
the egress path.

Signed-off-by: David Ahern <dahern@digitalocean.com>
Co-developed-by: Prashant Bhole <prashantbhole.linux@gmail.com>
Signed-off-by: Prashant Bhole <prashantbhole.linux@gmail.com>
---
 include/linux/netdevice.h |  4 +++-
 net/core/dev.c            | 30 +++++++++++++++++++++---------
 net/core/rtnetlink.c      |  2 +-
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6c3f7032e8d9..d0dd0706ece4 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -868,8 +868,10 @@ enum bpf_netdev_command {
 	 */
 	XDP_SETUP_PROG,
 	XDP_SETUP_PROG_HW,
+	XDP_SETUP_PROG_EGRESS,
 	XDP_QUERY_PROG,
 	XDP_QUERY_PROG_HW,
+	XDP_QUERY_PROG_EGRESS,
 	/* BPF program for offload callbacks, invoked at program load time. */
 	BPF_OFFLOAD_MAP_ALLOC,
 	BPF_OFFLOAD_MAP_FREE,
@@ -3767,7 +3769,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 
 typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
 int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
-		      int fd, u32 flags);
+		      int fd, u32 flags, bool egress);
 u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
 		    enum bpf_netdev_command cmd);
 int xdp_umem_query(struct net_device *dev, u16 queue_id);
diff --git a/net/core/dev.c b/net/core/dev.c
index e10bd680dc03..27fc96ea0fdb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8587,7 +8587,7 @@ u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
 
 static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
 			   struct netlink_ext_ack *extack, u32 flags,
-			   struct bpf_prog *prog)
+			   struct bpf_prog *prog, bool egress)
 {
 	bool non_hw = !(flags & XDP_FLAGS_HW_MODE);
 	struct bpf_prog *prev_prog = NULL;
@@ -8605,7 +8605,7 @@ static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
 	if (flags & XDP_FLAGS_HW_MODE)
 		xdp.command = XDP_SETUP_PROG_HW;
 	else
-		xdp.command = XDP_SETUP_PROG;
+		xdp.command = egress ? XDP_SETUP_PROG_EGRESS : XDP_SETUP_PROG;
 	xdp.extack = extack;
 	xdp.flags = flags;
 	xdp.prog = prog;
@@ -8626,7 +8626,8 @@ static void dev_xdp_uninstall(struct net_device *dev)
 	bpf_op_t ndo_bpf;
 
 	/* Remove generic XDP */
-	WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL));
+	WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL,
+				false));
 
 	/* Remove from the driver */
 	ndo_bpf = dev->netdev_ops->ndo_bpf;
@@ -8638,14 +8639,20 @@ static void dev_xdp_uninstall(struct net_device *dev)
 	WARN_ON(ndo_bpf(dev, &xdp));
 	if (xdp.prog_id)
 		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
-					NULL));
+					NULL, false));
 
 	/* Remove HW offload */
 	memset(&xdp, 0, sizeof(xdp));
 	xdp.command = XDP_QUERY_PROG_HW;
 	if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
 		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
-					NULL));
+					NULL, false));
+	/* Remove egress program */
+	memset(&xdp, 0, sizeof(xdp));
+	xdp.command = XDP_QUERY_PROG_EGRESS;
+	if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
+		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
+					NULL, true));
 }
 
 /**
@@ -8658,7 +8665,7 @@ static void dev_xdp_uninstall(struct net_device *dev)
  *	Set or clear a bpf program for a device
  */
 int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
-		      int fd, u32 flags)
+		      int fd, u32 flags, bool egress)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	enum bpf_netdev_command query;
@@ -8670,7 +8677,11 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 	ASSERT_RTNL();
 
 	offload = flags & XDP_FLAGS_HW_MODE;
-	query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
+	if (egress)
+		query = XDP_QUERY_PROG_EGRESS;
+	else
+		query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
+
 
 	bpf_op = bpf_chk = ops->ndo_bpf;
 	if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
@@ -8685,7 +8696,8 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 	if (fd >= 0) {
 		u32 prog_id;
 
-		if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
+		if (!offload && !egress &&
+		    __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
 			NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
 			return -EEXIST;
 		}
@@ -8717,7 +8729,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 			return 0;
 	}
 
-	err = dev_xdp_install(dev, bpf_op, extack, flags, prog);
+	err = dev_xdp_install(dev, bpf_op, extack, flags, prog, egress);
 	if (err < 0 && prog)
 		bpf_prog_put(prog);
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 14e6ea21c378..a488ab995f3e 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2801,7 +2801,7 @@ static int do_setlink(const struct sk_buff *skb,
 		if (xdp[IFLA_XDP_FD]) {
 			err = dev_change_xdp_fd(dev, extack,
 						nla_get_s32(xdp[IFLA_XDP_FD]),
-						xdp_flags);
+						xdp_flags, false);
 			if (err)
 				goto errout;
 			status |= DO_SETLINK_NOTIFY;
-- 
2.21.1 (Apple Git-122.3)