3 files changed, 45 insertions, 6 deletions

diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index ea2dbed2e..03ddebdbd 100755
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -107,6 +107,9 @@ type ndpState struct {
 	// The NIC this ndpState is for.
 	nic *NIC
 
+	// configs is the per-interface NDP configurations.
+	configs NDPConfigurations
+
 	// The DAD state to send the next NS message, or resolve the address.
 	dad map[tcpip.Address]dadState
 }
@@ -149,7 +152,7 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref
 		panic(fmt.Sprintf("ndpdad: already performing DAD for addr %s on NIC(%d)", addr, ndp.nic.ID()))
 	}
 
-	remaining := ndp.nic.stack.ndpConfigs.DupAddrDetectTransmits
+	remaining := ndp.configs.DupAddrDetectTransmits
 
 	{
 		done, err := ndp.doDuplicateAddressDetection(addr, remaining, ref)
@@ -165,7 +168,7 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref
 
 	var done bool
 	var timer *time.Timer
-	timer = time.AfterFunc(ndp.nic.stack.ndpConfigs.RetransmitTimer, func() {
+	timer = time.AfterFunc(ndp.configs.RetransmitTimer, func() {
 		var d bool
 		var err *tcpip.Error
 
@@ -218,7 +221,6 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref
 		if doDadIteration() && ndp.nic.stack.ndpDisp != nil {
 			ndp.nic.stack.ndpDisp.OnDuplicateAddressDetectionStatus(ndp.nic.ID(), addr, d, err)
 		}
-
 	})
 
 	ndp.dad[addr] = dadState{
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index 2d29fa88e..a867f8c00 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -46,6 +46,10 @@ type NIC struct {
 
 	stats NICStats
 
+	// ndp is the NDP related state for NIC.
+	//
+	// Note, read and write operations on ndp require that the NIC is
+	// appropriately locked.
 	ndp ndpState
 }
 
@@ -80,6 +84,7 @@ const (
 	NeverPrimaryEndpoint
 )
 
+// newNIC returns a new NIC using the default NDP configurations from stack.
 func newNIC(stack *Stack, id tcpip.NICID, name string, ep LinkEndpoint, loopback bool) *NIC {
 	// TODO(b/141011931): Validate a LinkEndpoint (ep) is valid. For
 	// example, make sure that the link address it provides is a valid
@@ -105,7 +110,8 @@ func newNIC(stack *Stack, id tcpip.NICID, name string, ep LinkEndpoint, loopback
 			},
 		},
 		ndp: ndpState{
-			dad: make(map[tcpip.Address]dadState),
+			configs: stack.ndpConfigs,
+			dad:     make(map[tcpip.Address]dadState),
 		},
 	}
 	nic.ndp.nic = nic
@@ -937,6 +943,18 @@ func (n *NIC) dupTentativeAddrDetected(addr tcpip.Address) *tcpip.Error {
 	return n.removePermanentAddressLocked(addr)
 }
 
+// setNDPConfigs sets the NDP configurations for n.
+//
+// Note, if c contains invalid NDP configuration values, it will be fixed to
+// use default values for the erroneous values.
+func (n *NIC) setNDPConfigs(c NDPConfigurations) {
+	c.validate()
+
+	n.mu.Lock()
+	n.ndp.configs = c
+	n.mu.Unlock()
+}
+
 type networkEndpointKind int32
 
 const (
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 5ea432a24..242d2150c 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -399,7 +399,7 @@ type Stack struct {
 	// TODO(gvisor.dev/issue/940): S/R this field.
 	portSeed uint32
 
-	// ndpConfigs is the NDP configurations used by interfaces.
+	// ndpConfigs is the default NDP configurations used by interfaces.
 	ndpConfigs NDPConfigurations
 
 	// autoGenIPv6LinkLocal determines whether or not the stack will attempt
@@ -433,7 +433,7 @@ type Options struct {
 	// stack (false).
 	HandleLocal bool
 
-	// NDPConfigs is the NDP configurations used by interfaces.
+	// NDPConfigs is the default NDP configurations used by interfaces.
 	//
 	// By default, NDPConfigs will have a zero value for its
 	// DupAddrDetectTransmits field, implying that DAD will not be performed
@@ -1425,6 +1425,25 @@ func (s *Stack) DupTentativeAddrDetected(id tcpip.NICID, addr tcpip.Address) *tc
 	return nic.dupTentativeAddrDetected(addr)
 }
 
+// SetNDPConfigurations sets the per-interface NDP configurations on the NIC
+// with ID id to c.
+//
+// Note, if c contains invalid NDP configuration values, it will be fixed to
+// use default values for the erroneous values.
+func (s *Stack) SetNDPConfigurations(id tcpip.NICID, c NDPConfigurations) *tcpip.Error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	nic, ok := s.nics[id]
+	if !ok {
+		return tcpip.ErrUnknownNICID
+	}
+
+	nic.setNDPConfigs(c)
+
+	return nil
+}
+
 // PortSeed returns a 32 bit value that can be used as a seed value for port
 // picking.
 //