github.com/rish1988/moby@v25.0.2+incompatible/libnetwork/drivers/bridge/setup_device_linux.go (about)

     1  package bridge
     2  
     3  import (
     4  	"context"
     5  	"fmt"
     6  	"os"
     7  	"path/filepath"
     8  
     9  	"github.com/containerd/log"
    10  	"github.com/docker/docker/libnetwork/netutils"
    11  	"github.com/vishvananda/netlink"
    12  )
    13  
    14  // SetupDevice create a new bridge interface/
    15  func setupDevice(config *networkConfiguration, i *bridgeInterface) error {
    16  	// We only attempt to create the bridge when the requested device name is
    17  	// the default one. The default bridge name can be overridden with the
    18  	// DOCKER_TEST_CREATE_DEFAULT_BRIDGE env var. It should be used only for
    19  	// test purpose.
    20  	var defaultBridgeName string
    21  	if defaultBridgeName = os.Getenv("DOCKER_TEST_CREATE_DEFAULT_BRIDGE"); defaultBridgeName == "" {
    22  		defaultBridgeName = DefaultBridgeName
    23  	}
    24  	if config.BridgeName != defaultBridgeName && config.DefaultBridge {
    25  		return NonDefaultBridgeExistError(config.BridgeName)
    26  	}
    27  
    28  	// Set the bridgeInterface netlink.Bridge.
    29  	i.Link = &netlink.Bridge{
    30  		LinkAttrs: netlink.LinkAttrs{
    31  			Name: config.BridgeName,
    32  		},
    33  	}
    34  
    35  	// Set the bridge's MAC address. Requires kernel version 3.3 or up.
    36  	hwAddr := netutils.GenerateRandomMAC()
    37  	i.Link.Attrs().HardwareAddr = hwAddr
    38  	log.G(context.TODO()).Debugf("Setting bridge mac address to %s", hwAddr)
    39  
    40  	if err := i.nlh.LinkAdd(i.Link); err != nil {
    41  		log.G(context.TODO()).WithError(err).Errorf("Failed to create bridge %s via netlink", config.BridgeName)
    42  		return err
    43  	}
    44  
    45  	return nil
    46  }
    47  
    48  func setupMTU(config *networkConfiguration, i *bridgeInterface) error {
    49  	if err := i.nlh.LinkSetMTU(i.Link, config.Mtu); err != nil {
    50  		log.G(context.TODO()).WithError(err).Errorf("Failed to set bridge MTU %s via netlink", config.BridgeName)
    51  		return err
    52  	}
    53  	return nil
    54  }
    55  
    56  func setupDefaultSysctl(config *networkConfiguration, i *bridgeInterface) error {
    57  	// Disable IPv6 router advertisements originating on the bridge
    58  	sysPath := filepath.Join("/proc/sys/net/ipv6/conf/", config.BridgeName, "accept_ra")
    59  	if _, err := os.Stat(sysPath); err != nil {
    60  		log.G(context.TODO()).
    61  			WithField("bridge", config.BridgeName).
    62  			WithField("syspath", sysPath).
    63  			Info("failed to read ipv6 net.ipv6.conf.<bridge>.accept_ra")
    64  		return nil
    65  	}
    66  	if err := os.WriteFile(sysPath, []byte{'0', '\n'}, 0o644); err != nil {
    67  		log.G(context.TODO()).WithError(err).Warn("unable to disable IPv6 router advertisement")
    68  	}
    69  	return nil
    70  }
    71  
    72  // SetupDeviceUp ups the given bridge interface.
    73  func setupDeviceUp(config *networkConfiguration, i *bridgeInterface) error {
    74  	err := i.nlh.LinkSetUp(i.Link)
    75  	if err != nil {
    76  		return fmt.Errorf("Failed to set link up for %s: %v", config.BridgeName, err)
    77  	}
    78  
    79  	// Attempt to update the bridge interface to refresh the flags status,
    80  	// ignoring any failure to do so.
    81  	if lnk, err := i.nlh.LinkByName(config.BridgeName); err == nil {
    82  		i.Link = lnk
    83  	} else {
    84  		log.G(context.TODO()).Warnf("Failed to retrieve link for interface (%s): %v", config.BridgeName, err)
    85  	}
    86  	return nil
    87  }