2 files changed, 25 insertions, 3 deletions
diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index d983ac390..245694118 100644
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -538,11 +538,29 @@ func (ndp *ndpState) sendDADPacket(addr tcpip.Address) *tcpip.Error {
 	r := makeRoute(header.IPv6ProtocolNumber, header.IPv6Any, snmc, ndp.nic.linkEP.LinkAddress(), ref, false, false)
 	defer r.Release()
 
-	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborSolicitMinimumSize)
-	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborSolicitMinimumSize))
+	linkAddr := ndp.nic.linkEP.LinkAddress()
+	isValidLinkAddr := header.IsValidUnicastEthernetAddress(linkAddr)
+	ndpNSSize := header.ICMPv6NeighborSolicitMinimumSize
+	if isValidLinkAddr {
+		// Only include a Source Link Layer Address option if the NIC has a valid
+		// link layer address.
+		//
+		// TODO(b/141011931): Validate a LinkEndpoint's link address (provided by
+		// LinkEndpoint.LinkAddress) before reaching this point.
+		ndpNSSize += header.NDPLinkLayerAddressSize
+	}
+
+	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + ndpNSSize)
+	pkt := header.ICMPv6(hdr.Prepend(ndpNSSize))
 	pkt.SetType(header.ICMPv6NeighborSolicit)
 	ns := header.NDPNeighborSolicit(pkt.NDPPayload())
 	ns.SetTargetAddress(addr)
+
+	if isValidLinkAddr {
+		ns.Options().Serialize(header.NDPOptionsSerializer{
+			header.NDPSourceLinkLayerAddressOption(linkAddr),
+		})
+	}
 	pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
 
 	sent := r.Stats().ICMP.V6PacketsSent
diff --git a/pkg/tcpip/stack/ndp_test.go b/pkg/tcpip/stack/ndp_test.go
index ad2c6f601..726468e41 100644
--- a/pkg/tcpip/stack/ndp_test.go
+++ b/pkg/tcpip/stack/ndp_test.go
@@ -417,7 +417,11 @@ func TestDADResolve(t *testing.T) {
 				checker.IPv6(t, p.Pkt.Header.View().ToVectorisedView().First(),
 					checker.TTL(header.NDPHopLimit),
 					checker.NDPNS(
-						checker.NDPNSTargetAddress(addr1)))
+						checker.NDPNSTargetAddress(addr1),
+						checker.NDPNSOptions([]header.NDPOption{
+							header.NDPSourceLinkLayerAddressOption(linkAddr1),
+						}),
+					))
 			}
 		})
 	}