Use interface-specific NDP configurations instead of the stack-wide default.

This change makes it so that NDP work is done using the per-interface NDP
configurations instead of the stack-wide default NDP configurations to correctly
implement RFC 4861 section 6.3.2 (note here, a host is a single NIC operating
as a host device), and RFC 4862 section 5.1.

Test: Test that we can set NDP configurations on a per-interface basis without
affecting the configurations of other interfaces or the stack-wide default. Also
make sure that after the configurations are updated, the updated configurations
are used for NDP processes (e.g. Duplicate Address Detection).
PiperOrigin-RevId: 276525661

1 files changed, 19 insertions, 1 deletions

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 (