/
ptp.go
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/
ptp.go
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// Copyright 2015 CNI authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"encoding/json"
"errors"
"fmt"
"net"
"os"
"runtime"
"github.com/j-keck/arping"
"github.com/vishvananda/netlink"
"github.com/containernetworking/cni/pkg/skel"
"github.com/containernetworking/cni/pkg/types"
"github.com/containernetworking/cni/pkg/types/current"
"github.com/containernetworking/cni/pkg/version"
"github.com/containernetworking/plugins/pkg/ip"
"github.com/containernetworking/plugins/pkg/ipam"
"github.com/containernetworking/plugins/pkg/ns"
"github.com/containernetworking/plugins/pkg/utils"
bv "github.com/containernetworking/plugins/pkg/utils/buildversion"
)
func init() {
// this ensures that main runs only on main thread (thread group leader).
// since namespace ops (unshare, setns) are done for a single thread, we
// must ensure that the goroutine does not jump from OS thread to thread
runtime.LockOSThread()
}
type NetConf struct {
types.NetConf
IPMasq bool `json:"ipMasq"`
MTU int `json:"mtu"`
}
func setupContainerVeth(netns ns.NetNS, ifName string, mtu int, pr *current.Result) (*current.Interface, *current.Interface, error) {
// The IPAM result will be something like IP=192.168.3.5/24, GW=192.168.3.1.
// What we want is really a point-to-point link but veth does not support IFF_POINTTOPOINT.
// Next best thing would be to let it ARP but set interface to 192.168.3.5/32 and
// add a route like "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// Unfortunately that won't work as the GW will be outside the interface's subnet.
// Our solution is to configure the interface with 192.168.3.5/24, then delete the
// "192.168.3.0/24 dev $ifName" route that was automatically added. Then we add
// "192.168.3.1/32 dev $ifName" and "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// In other words we force all traffic to ARP via the gateway except for GW itself.
hostInterface := ¤t.Interface{}
containerInterface := ¤t.Interface{}
err := netns.Do(func(hostNS ns.NetNS) error {
hostVeth, contVeth0, err := ip.SetupVeth(ifName, mtu, hostNS)
if err != nil {
return err
}
hostInterface.Name = hostVeth.Name
hostInterface.Mac = hostVeth.HardwareAddr.String()
containerInterface.Name = contVeth0.Name
containerInterface.Mac = contVeth0.HardwareAddr.String()
containerInterface.Sandbox = netns.Path()
for _, ipc := range pr.IPs {
// All addresses apply to the container veth interface
ipc.Interface = current.Int(1)
}
pr.Interfaces = []*current.Interface{hostInterface, containerInterface}
if err = ipam.ConfigureIface(ifName, pr); err != nil {
return err
}
contVeth, err := net.InterfaceByName(ifName)
if err != nil {
return fmt.Errorf("failed to look up %q: %v", ifName, err)
}
for _, ipc := range pr.IPs {
// Delete the route that was automatically added
route := netlink.Route{
LinkIndex: contVeth.Index,
Dst: &net.IPNet{
IP: ipc.Address.IP.Mask(ipc.Address.Mask),
Mask: ipc.Address.Mask,
},
Scope: netlink.SCOPE_NOWHERE,
}
if err := netlink.RouteDel(&route); err != nil {
return fmt.Errorf("failed to delete route %v: %v", route, err)
}
addrBits := 32
if ipc.Version == "6" {
addrBits = 128
}
for _, r := range []netlink.Route{
{
LinkIndex: contVeth.Index,
Dst: &net.IPNet{
IP: ipc.Gateway,
Mask: net.CIDRMask(addrBits, addrBits),
},
Scope: netlink.SCOPE_LINK,
Src: ipc.Address.IP,
},
{
LinkIndex: contVeth.Index,
Dst: &net.IPNet{
IP: ipc.Address.IP.Mask(ipc.Address.Mask),
Mask: ipc.Address.Mask,
},
Scope: netlink.SCOPE_UNIVERSE,
Gw: ipc.Gateway,
Src: ipc.Address.IP,
},
} {
if err := netlink.RouteAdd(&r); err != nil {
return fmt.Errorf("failed to add route %v: %v", r, err)
}
}
}
// Send a gratuitous arp for all v4 addresses
for _, ipc := range pr.IPs {
if ipc.Version == "4" {
_ = arping.GratuitousArpOverIface(ipc.Address.IP, *contVeth)
}
}
return nil
})
if err != nil {
return nil, nil, err
}
return hostInterface, containerInterface, nil
}
func setupHostVeth(vethName string, result *current.Result) error {
// hostVeth moved namespaces and may have a new ifindex
veth, err := netlink.LinkByName(vethName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", vethName, err)
}
for _, ipc := range result.IPs {
maskLen := 128
if ipc.Address.IP.To4() != nil {
maskLen = 32
}
ipn := &net.IPNet{
IP: ipc.Gateway,
Mask: net.CIDRMask(maskLen, maskLen),
}
addr := &netlink.Addr{IPNet: ipn, Label: ""}
if err = netlink.AddrAdd(veth, addr); err != nil {
return fmt.Errorf("failed to add IP addr (%#v) to veth: %v", ipn, err)
}
ipn = &net.IPNet{
IP: ipc.Address.IP,
Mask: net.CIDRMask(maskLen, maskLen),
}
// dst happens to be the same as IP/net of host veth
if err = ip.AddHostRoute(ipn, nil, veth); err != nil && !os.IsExist(err) {
return fmt.Errorf("failed to add route on host: %v", err)
}
}
return nil
}
func cmdAdd(args *skel.CmdArgs) error {
conf := NetConf{}
if err := json.Unmarshal(args.StdinData, &conf); err != nil {
return fmt.Errorf("failed to load netconf: %v", err)
}
// run the IPAM plugin and get back the config to apply
r, err := ipam.ExecAdd(conf.IPAM.Type, args.StdinData)
if err != nil {
return err
}
// Invoke ipam del if err to avoid ip leak
defer func() {
if err != nil {
ipam.ExecDel(conf.IPAM.Type, args.StdinData)
}
}()
// Convert whatever the IPAM result was into the current Result type
result, err := current.NewResultFromResult(r)
if err != nil {
return err
}
if len(result.IPs) == 0 {
return errors.New("IPAM plugin returned missing IP config")
}
if err := ip.EnableForward(result.IPs); err != nil {
return fmt.Errorf("Could not enable IP forwarding: %v", err)
}
netns, err := ns.GetNS(args.Netns)
if err != nil {
return fmt.Errorf("failed to open netns %q: %v", args.Netns, err)
}
defer netns.Close()
hostInterface, containerInterface, err := setupContainerVeth(netns, args.IfName, conf.MTU, result)
if err != nil {
return err
}
if err = setupHostVeth(hostInterface.Name, result); err != nil {
return err
}
if conf.IPMasq {
chain := utils.FormatChainName(conf.Name, args.ContainerID)
comment := utils.FormatComment(conf.Name, args.ContainerID)
for _, ipc := range result.IPs {
if err = ip.SetupIPMasq(&ipc.Address, chain, comment); err != nil {
return err
}
}
}
// Only override the DNS settings in the previous result if any DNS fields
// were provided to the ptp plugin. This allows, for example, IPAM plugins
// to specify the DNS settings instead of the ptp plugin.
if dnsConfSet(conf.DNS) {
result.DNS = conf.DNS
}
result.Interfaces = []*current.Interface{hostInterface, containerInterface}
return types.PrintResult(result, conf.CNIVersion)
}
func dnsConfSet(dnsConf types.DNS) bool {
return dnsConf.Nameservers != nil ||
dnsConf.Search != nil ||
dnsConf.Options != nil ||
dnsConf.Domain != ""
}
func cmdDel(args *skel.CmdArgs) error {
conf := NetConf{}
if err := json.Unmarshal(args.StdinData, &conf); err != nil {
return fmt.Errorf("failed to load netconf: %v", err)
}
if err := ipam.ExecDel(conf.IPAM.Type, args.StdinData); err != nil {
return err
}
if args.Netns == "" {
return nil
}
// There is a netns so try to clean up. Delete can be called multiple times
// so don't return an error if the device is already removed.
// If the device isn't there then don't try to clean up IP masq either.
var ipnets []*net.IPNet
err := ns.WithNetNSPath(args.Netns, func(_ ns.NetNS) error {
var err error
ipnets, err = ip.DelLinkByNameAddr(args.IfName)
if err != nil && err == ip.ErrLinkNotFound {
return nil
}
return err
})
if err != nil {
return err
}
if len(ipnets) != 0 && conf.IPMasq {
chain := utils.FormatChainName(conf.Name, args.ContainerID)
comment := utils.FormatComment(conf.Name, args.ContainerID)
for _, ipn := range ipnets {
err = ip.TeardownIPMasq(ipn, chain, comment)
}
}
return err
}
func main() {
skel.PluginMain(cmdAdd, cmdCheck, cmdDel, version.All, bv.BuildString("ptp"))
}
func cmdCheck(args *skel.CmdArgs) error {
conf := NetConf{}
if err := json.Unmarshal(args.StdinData, &conf); err != nil {
return fmt.Errorf("failed to load netconf: %v", err)
}
netns, err := ns.GetNS(args.Netns)
if err != nil {
return fmt.Errorf("failed to open netns %q: %v", args.Netns, err)
}
defer netns.Close()
// run the IPAM plugin and get back the config to apply
err = ipam.ExecCheck(conf.IPAM.Type, args.StdinData)
if err != nil {
return err
}
if conf.NetConf.RawPrevResult == nil {
return fmt.Errorf("ptp: Required prevResult missing")
}
if err := version.ParsePrevResult(&conf.NetConf); err != nil {
return err
}
// Convert whatever the IPAM result was into the current Result type
result, err := current.NewResultFromResult(conf.PrevResult)
if err != nil {
return err
}
var contMap current.Interface
// Find interfaces for name whe know, that of host-device inside container
for _, intf := range result.Interfaces {
if args.IfName == intf.Name {
if args.Netns == intf.Sandbox {
contMap = *intf
continue
}
}
}
// The namespace must be the same as what was configured
if args.Netns != contMap.Sandbox {
return fmt.Errorf("Sandbox in prevResult %s doesn't match configured netns: %s",
contMap.Sandbox, args.Netns)
}
//
// Check prevResults for ips, routes and dns against values found in the container
if err := netns.Do(func(_ ns.NetNS) error {
// Check interface against values found in the container
err := validateCniContainerInterface(contMap)
if err != nil {
return err
}
err = ip.ValidateExpectedInterfaceIPs(args.IfName, result.IPs)
if err != nil {
return err
}
err = ip.ValidateExpectedRoute(result.Routes)
if err != nil {
return err
}
return nil
}); err != nil {
return err
}
return nil
}
func validateCniContainerInterface(intf current.Interface) error {
var link netlink.Link
var err error
if intf.Name == "" {
return fmt.Errorf("Container interface name missing in prevResult: %v", intf.Name)
}
link, err = netlink.LinkByName(intf.Name)
if err != nil {
return fmt.Errorf("ptp: Container Interface name in prevResult: %s not found", intf.Name)
}
if intf.Sandbox == "" {
return fmt.Errorf("ptp: Error: Container interface %s should not be in host namespace", link.Attrs().Name)
}
_, isVeth := link.(*netlink.Veth)
if !isVeth {
return fmt.Errorf("Error: Container interface %s not of type veth/p2p", link.Attrs().Name)
}
if intf.Mac != "" {
if intf.Mac != link.Attrs().HardwareAddr.String() {
return fmt.Errorf("ptp: Interface %s Mac %s doesn't match container Mac: %s", intf.Name, intf.Mac, link.Attrs().HardwareAddr)
}
}
return nil
}