3 files changed, 99 insertions, 0 deletions
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index 78d451cca..ca3a7a07e 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -1215,6 +1215,11 @@ func (n *NIC) ID() tcpip.NICID {
 	return n.id
 }
 
+// Name returns the name of n.
+func (n *NIC) Name() string {
+	return n.name
+}
+
 // Stack returns the instance of the Stack that owns this NIC.
 func (n *NIC) Stack() *Stack {
 	return n.stack
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index b793f1d74..6eac16e16 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -890,6 +890,15 @@ func (s *Stack) CreateNICWithOptions(id tcpip.NICID, ep LinkEndpoint, opts NICOp
 		return tcpip.ErrDuplicateNICID
 	}
 
+	// Make sure name is unique, unless unnamed.
+	if opts.Name != "" {
+		for _, n := range s.nics {
+			if n.Name() == opts.Name {
+				return tcpip.ErrDuplicateNICID
+			}
+		}
+	}
+
 	n := newNIC(s, id, opts.Name, ep, opts.Context)
 
 	s.nics[id] = n
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index 24133e6f2..7ba604442 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -1792,6 +1792,91 @@ func TestAddProtocolAddressWithOptions(t *testing.T) {
 	verifyAddresses(t, expectedAddresses, gotAddresses)
 }
 
+func TestCreateNICWithOptions(t *testing.T) {
+	type callArgsAndExpect struct {
+		nicID tcpip.NICID
+		opts  stack.NICOptions
+		err   *tcpip.Error
+	}
+
+	tests := []struct {
+		desc  string
+		calls []callArgsAndExpect
+	}{
+		{
+			desc: "DuplicateNICID",
+			calls: []callArgsAndExpect{
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{Name: "eth1"},
+					err:   nil,
+				},
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{Name: "eth2"},
+					err:   tcpip.ErrDuplicateNICID,
+				},
+			},
+		},
+		{
+			desc: "DuplicateName",
+			calls: []callArgsAndExpect{
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{Name: "lo"},
+					err:   nil,
+				},
+				{
+					nicID: tcpip.NICID(2),
+					opts:  stack.NICOptions{Name: "lo"},
+					err:   tcpip.ErrDuplicateNICID,
+				},
+			},
+		},
+		{
+			desc: "Unnamed",
+			calls: []callArgsAndExpect{
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{},
+					err:   nil,
+				},
+				{
+					nicID: tcpip.NICID(2),
+					opts:  stack.NICOptions{},
+					err:   nil,
+				},
+			},
+		},
+		{
+			desc: "UnnamedDuplicateNICID",
+			calls: []callArgsAndExpect{
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{},
+					err:   nil,
+				},
+				{
+					nicID: tcpip.NICID(1),
+					opts:  stack.NICOptions{},
+					err:   tcpip.ErrDuplicateNICID,
+				},
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			s := stack.New(stack.Options{})
+			ep := channel.New(0, 0, tcpip.LinkAddress("\x00\x00\x00\x00\x00\x00"))
+			for _, call := range test.calls {
+				if got, want := s.CreateNICWithOptions(call.nicID, ep, call.opts), call.err; got != want {
+					t.Fatalf("CreateNICWithOptions(%v, _, %+v) = %v, want %v", call.nicID, call.opts, got, want)
+				}
+			}
+		})
+	}
+}
+
 func TestNICStats(t *testing.T) {
 	s := stack.New(stack.Options{
 		NetworkProtocols: []stack.NetworkProtocol{fakeNetFactory()},