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Explicitly Disable Duplicate Address Detection For Container Side Veth #695

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merged 3 commits into from
Feb 9, 2022
Merged

Explicitly Disable Duplicate Address Detection For Container Side Veth #695

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8ede7ee
Disable DAD for container side veth
Jan 25, 2022
2be2960
Add boolean to enable/disable dad
Feb 9, 2022
ba47b49
Enhanced dad set to 1
Feb 9, 2022
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32 changes: 6 additions & 26 deletions plugins/main/bridge/bridge.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"net"
"os"
"runtime"
Expand Down Expand Up @@ -57,6 +56,7 @@ type NetConf struct {
PromiscMode bool `json:"promiscMode"`
Vlan int `json:"vlan"`
MacSpoofChk bool `json:"macspoofchk,omitempty"`
EnableDad bool `json:"enabledad,omitempty"`

Args struct {
Cni BridgeArgs `json:"cni,omitempty"`
Expand Down Expand Up @@ -402,20 +402,6 @@ func setupBridge(n *NetConf) (*netlink.Bridge, *current.Interface, error) {
}, nil
}

// disableIPV6DAD disables IPv6 Duplicate Address Detection (DAD)
// for an interface, if the interface does not support enhanced_dad.
// We do this because interfaces with hairpin mode will see their own DAD packets
func disableIPV6DAD(ifName string) error {
// ehanced_dad sends a nonce with the DAD packets, so that we can safely
// ignore ourselves
enh, err := ioutil.ReadFile(fmt.Sprintf("/proc/sys/net/ipv6/conf/%s/enhanced_dad", ifName))
if err == nil && string(enh) == "1\n" {
return nil
}
f := fmt.Sprintf("/proc/sys/net/ipv6/conf/%s/accept_dad", ifName)
return ioutil.WriteFile(f, []byte("0"), 0644)
}

func enableIPForward(family int) error {
if family == netlink.FAMILY_V4 {
return ip.EnableIP4Forward()
Expand Down Expand Up @@ -516,18 +502,12 @@ func cmdAdd(args *skel.CmdArgs) error {

// Configure the container hardware address and IP address(es)
if err := netns.Do(func(_ ns.NetNS) error {
// Disable IPv6 DAD just in case hairpin mode is enabled on the
// bridge. Hairpin mode causes echos of neighbor solicitation
// packets, which causes DAD failures.
for _, ipc := range result.IPs {
if ipc.Address.IP.To4() == nil && (n.HairpinMode || n.PromiscMode) {
if err := disableIPV6DAD(args.IfName); err != nil {
return err
}
break
}
if n.EnableDad {
_, _ = sysctl.Sysctl(fmt.Sprintf("/net/ipv6/conf/%s/enhanced_dad", args.IfName), "1")
_, _ = sysctl.Sysctl(fmt.Sprintf("net/ipv6/conf/%s/accept_dad", args.IfName), "1")
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} else {
_, _ = sysctl.Sysctl(fmt.Sprintf("net/ipv6/conf/%s/accept_dad", args.IfName), "0")
}

_, _ = sysctl.Sysctl(fmt.Sprintf("net/ipv4/conf/%s/arp_notify", args.IfName), "1")

// Add the IP to the interface
Expand Down