macvlan: set proxy_arp in time of creating interface

Resolves CNI part of https://github.com/coreos/rkt/issues/1765
Second part would be adding similar lines into kvm flavored macvlan
support (in time of creating macvtap device).

diff --git a/plugins/main/macvlan/macvlan.go b/plugins/main/macvlan/macvlan.go
index f6891a3..0635f26 100644 (file)
--- a/plugins/main/macvlan/macvlan.go
+++ b/plugins/main/macvlan/macvlan.go
@@ -26,9 +26,14 @@ import (
        "github.com/appc/cni/pkg/ns"
        "github.com/appc/cni/pkg/skel"
        "github.com/appc/cni/pkg/types"
+       "github.com/appc/cni/pkg/utils/sysctl"
        "github.com/vishvananda/netlink"
 )
 
+const (
+       IPv4InterfaceArpProxySysctlTemplate = "net.ipv4.conf.%s.proxy_arp"
+)
+
 type NetConf struct {
        types.NetConf
        Master string `json:"master"`
@@ -80,7 +85,7 @@ func createMacvlan(conf *NetConf, ifName string, netns *os.File) error {
                return fmt.Errorf("failed to lookup master %q: %v", conf.Master, err)
        }
 
-       // due to kernel bug we have to create with tmpname or it might
+       // due to kernel bug we have to create with tmpName or it might
        // collide with the name on the host and error out
        tmpName, err := ip.RandomVethName()
        if err != nil {
@@ -101,6 +106,14 @@ func createMacvlan(conf *NetConf, ifName string, netns *os.File) error {
                return fmt.Errorf("failed to create macvlan: %v", err)
        }
 
+       // TODO: duplicate following lines for ipv6 support, when it will be added in other places
+       ipv4SysctlValueName := fmt.Sprintf(IPv4InterfaceArpProxySysctlTemplate, tmpName)
+       if _, err := sysctl.Sysctl(ipv4SysctlValueName, "1"); err != nil {
+               // remove the newly added link and ignore errors, because we already are in a failed state
+               _ = netlink.LinkDel(mv)
+               return fmt.Errorf("failed to set proxy_arp on newly added interface %q: %v", tmpName, err)
+       }
+
        return ns.WithNetNS(netns, false, func(_ *os.File) error {
                err := renameLink(tmpName, ifName)
                if err != nil {