gvisor/runsc: use a veth link address instead of generating a new one

PiperOrigin-RevId: 248367340
Change-Id: Id792afcfff9c9d2cfd62cae21048316267b4a924

kokoro/run_tests.sh

@@ -153,10 +153,6 @@ run_docker_tests() {
   # configuration, e.g. save/restore not supported with hostnet.
   declare -a variations=("" "-kvm" "-hostnet" "-overlay")
   for v in "${variations[@]}"; do
-    # FIXME(b/132073574): we need to flush arp tables, otherwise tests fail with
-    # timeout.
-    sudo ip neigh show
-    sudo ip neigh flush dev docker0
     # Run runsc tests with docker that are tagged manual.
     bazel test \
       "${BAZEL_BUILD_FLAGS[@]}" \

runsc/boot/network.go

@@ -16,7 +16,6 @@ package boot
 
 import (
 	"fmt"
-	"math/rand"
 	"net"
 	"syscall"
 
@@ -52,11 +51,12 @@ type DefaultRoute struct {
 
 // FDBasedLink configures an fd-based link.
 type FDBasedLink struct {
-	Name       string
-	MTU        int
-	Addresses  []net.IP
-	Routes     []Route
-	GSOMaxSize uint32
+	Name        string
+	MTU         int
+	Addresses   []net.IP
+	Routes      []Route
+	GSOMaxSize  uint32
+	LinkAddress []byte
 }
 
 // LoopbackLink configures a loopback li nk.
@@ -134,7 +134,7 @@ func (n *Network) CreateLinksAndRoutes(args *CreateLinksAndRoutesArgs, _ *struct
 			return fmt.Errorf("failed to dup FD %v: %v", oldFD, err)
 		}
 
-		mac := tcpip.LinkAddress(generateRndMac())
+		mac := tcpip.LinkAddress(link.LinkAddress)
 		linkEP, err := fdbased.New(&fdbased.Options{
 			FD:                 newFD,
 			MTU:                uint32(link.MTU),
@@ -220,13 +220,3 @@ func ipToAddressMask(ip net.IP) tcpip.AddressMask {
 	_, addr := ipToAddressAndProto(ip)
 	return tcpip.AddressMask(addr)
 }
-
-// generateRndMac returns a random local MAC address.
-// Copied from eth_random_addr() (include/linux/etherdevice.h)
-func generateRndMac() net.HardwareAddr {
-	mac := make(net.HardwareAddr, 6)
-	rand.Read(mac)
-	mac[0] &^= 0x1 // clear multicast bit
-	mac[0] |= 0x2  // set local assignment bit (IEEE802)
-	return mac
-}

runsc/sandbox/network.go

@@ -246,6 +246,7 @@ func createInterfacesAndRoutesFromNS(conn *urpc.Client, nsPath string, enableGSO
 		if err != nil {
 			return fmt.Errorf("getting link for interface %q: %v", iface.Name, err)
 		}
+		link.LinkAddress = []byte(ifaceLink.Attrs().HardwareAddr)
 
 		if enableGSO {
 			gso, err := isGSOEnabled(fd, iface.Name)