Add support for loading XDP programs with flags

link_linux.go

@@ -568,6 +568,12 @@ func (h *Handle) LinkSetNsFd(link Link, fd int) error {
 // LinkSetXdpFd adds a bpf function to the driver. The fd must be a bpf
 // program loaded with bpf(type=BPF_PROG_TYPE_XDP)
 func LinkSetXdpFd(link Link, fd int) error {
+	return LinkSetXdpFdWithFlags(link, fd, 0)
+}
+
+// LinkSetXdpFdWithFlags adds a bpf function to the driver with the given
+// options. The fd must be a bpf program loaded with bpf(type=BPF_PROG_TYPE_XDP)
+func LinkSetXdpFdWithFlags(link Link, fd, flags int) error {
 	base := link.Attrs()
 	ensureIndex(base)
 	req := nl.NewNetlinkRequest(syscall.RTM_SETLINK, syscall.NLM_F_ACK)
@@ -576,7 +582,7 @@ func LinkSetXdpFd(link Link, fd int) error {
 	msg.Index = int32(base.Index)
 	req.AddData(msg)
 
-	addXdpAttrs(&LinkXdp{Fd: fd}, req)
+	addXdpAttrs(&LinkXdp{Fd: fd, Flags: uint32(flags)}, req)
 
 	_, err := req.Execute(syscall.NETLINK_ROUTE, 0)
 	return err

link_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/vishvananda/netlink/nl"
 	"github.com/vishvananda/netns"
 )
 
@@ -1157,6 +1158,9 @@ func TestLinkXdp(t *testing.T) {
 	if err := LinkSetXdpFd(testXdpLink, fd); err != nil {
 		t.Fatal(err)
 	}
+	if err := LinkSetXdpFdWithFlags(testXdpLink, fd, nl.XDP_FLAGS_UPDATE_IF_NOEXIST); err != syscall.EBUSY {
+		t.Fatal(err)
+	}
 	if err := LinkSetXdpFd(testXdpLink, -1); err != nil {
 		t.Fatal(err)
 	}

nl/link_linux.go

@@ -443,6 +443,13 @@ func (msg *VfTrust) Serialize() []byte {
 	return (*(*[SizeofVfTrust]byte)(unsafe.Pointer(msg)))[:]
 }
 
+const (
+	XDP_FLAGS_UPDATE_IF_NOEXIST = 1 << iota
+	XDP_FLAGS_SKB_MODE
+	XDP_FLAGS_DRV_MODE
+	XDP_FLAGS_MASK = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE
+)
+
 const (
 	IFLA_XDP_UNSPEC   = iota
 	IFLA_XDP_FD       /* fd of xdp program to attach, or -1 to remove */