Add an API to change net namespace of RDMA device

Add an API to change net namespace of RDMA device similar to

$ rdma dev set [DEV] netns NSNAME

Signed-off-by: Parav Pandit <parav@mellanox.com>

nl/rdma_link_linux.go

@@ -31,4 +31,5 @@ const (
 	RDMA_NLDEV_ATTR_PORT_PHYS_STATE = 13
 	RDMA_NLDEV_ATTR_DEV_NODE_TYPE   = 14
 	RDMA_NLDEV_SYS_ATTR_NETNS_MODE  = 66
+	RDMA_NLDEV_NET_NS_FD            = 68
 )

rdma_link_linux.go

@@ -238,3 +238,27 @@ func (h *Handle) RdmaSystemSetNetnsMode(NewMode string) error {
 	_, err = req.Execute(unix.NETLINK_RDMA, 0)
 	return err
 }
+
+// RdmaLinkSetNsFd puts the RDMA device into a new network namespace. The
+// fd must be an open file descriptor to a network namespace.
+// Similar to: `rdma dev set $dev netns $ns`
+func RdmaLinkSetNsFd(link *RdmaLink, fd uint32) error {
+	return pkgHandle.RdmaLinkSetNsFd(link, fd)
+}
+
+// RdmaLinkSetNsFd puts the RDMA device into a new network namespace. The
+// fd must be an open file descriptor to a network namespace.
+// Similar to: `rdma dev set $dev netns $ns`
+func (h *Handle) RdmaLinkSetNsFd(link *RdmaLink, fd uint32) error {
+	proto := getProtoField(nl.RDMA_NL_NLDEV, nl.RDMA_NLDEV_CMD_SET)
+	req := h.newNetlinkRequest(proto, unix.NLM_F_ACK)
+
+	data := nl.NewRtAttr(nl.RDMA_NLDEV_ATTR_DEV_INDEX,
+		nl.Uint32Attr(link.Attrs.Index))
+	req.AddData(data)
+
+	data = nl.NewRtAttr(nl.RDMA_NLDEV_NET_NS_FD, nl.Uint32Attr(fd))
+	req.AddData(data)
+
+	return execRdmaSetLink(req)
+}

rdma_link_test.go

@@ -3,6 +3,7 @@
 package netlink
 
 import (
+	"github.com/vishvananda/netns"
 	"io/ioutil"
 	"strings"
 	"testing"
@@ -99,3 +100,55 @@ func TestRdmaSystemSetNetnsMode(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestRdmaLinkSetNsFd(t *testing.T) {
+	minKernelRequired(t, 5, 2)
+	setupRdmaKModule(t, "ib_core")
+
+	mode, err := RdmaSystemGetNetnsMode()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log("current rdma netns mode", mode)
+	err = RdmaSystemSetNetnsMode("exclusive")
+	if err != nil {
+		t.Fatal(err)
+	}
+	basens, err := netns.Get()
+	if err != nil {
+		RdmaSystemSetNetnsMode(mode)
+		t.Fatal("Failed to get basens")
+	}
+	defer basens.Close()
+
+	newns, err := netns.New()
+	if err != nil {
+		RdmaSystemSetNetnsMode(mode)
+		t.Fatal("Failed to create newns")
+	}
+
+	netns.Set(basens)
+	link, err := RdmaLinkByName("foo")
+	if err != nil {
+		// Remove the namespace as RDMA subsystem requires
+		// no namespace to exist when changing net namespace mode
+		newns.Close()
+		RdmaSystemSetNetnsMode(mode)
+		t.Fatal(err)
+	}
+	t.Log("rdma link: ", link)
+
+	err = RdmaLinkSetNsFd(link, uint32(newns))
+	if err != nil {
+		newns.Close()
+		RdmaSystemSetNetnsMode(mode)
+		t.Fatal(err)
+	}
+
+	newns.Close()
+	//Set the old mode back at start of the test
+	err = RdmaSystemSetNetnsMode(mode)
+	if err != nil {
+		t.Fatal(err)
+	}
+}