fix 714-plugin add netns validation reinforcement

Signed-off-by: s00613818 <[email protected]>

Author: s00613818

go.mod

@@ -5,4 +5,6 @@ go 1.14
 require (
 	github.com/onsi/ginkgo/v2 v2.1.3
 	github.com/onsi/gomega v1.17.0
+	github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f
+	golang.org/x/sys v0.0.0-20210423082822-04245dca01da
 )

go.sum

@@ -41,6 +41,8 @@ github.com/onsi/gomega v1.17.0/go.mod h1:HnhC7FXeEQY45zxNK3PPoIUhzk/80Xly9PcubAl
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
+github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f h1:p4VB7kIXpOQvVn1ZaTIVp+3vuYAXFe3OJEvjbUYJLaA=
+github.com/vishvananda/netns v0.0.0-20210104183010-2eb08e3e575f/go.mod h1:DD4vA1DwXk04H54A1oHXtwZmA0grkVMdPxx/VGLCah0=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
@@ -63,6 +65,7 @@ golang.org/x/sys v0.0.0-20190904154756-749cb33beabd/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20191005200804-aed5e4c7ecf9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200217220822-9197077df867/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

pkg/skel/skel.go

@@ -24,22 +24,26 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"runtime"
 	"strings"
 
 	"github.com/containernetworking/cni/pkg/types"
 	"github.com/containernetworking/cni/pkg/utils"
 	"github.com/containernetworking/cni/pkg/version"
+	"github.com/vishvananda/netns"
+	"golang.org/x/sys/unix"
 )
 
 // CmdArgs captures all the arguments passed in to the plugin
 // via both env vars and stdin
 type CmdArgs struct {
-	ContainerID string
-	Netns       string
-	IfName      string
-	Args        string
-	Path        string
-	StdinData   []byte
+	ContainerID   string
+	Netns         string
+	IfName        string
+	Args          string
+	Path          string
+	NetnsOverride string
+	StdinData     []byte
 }
 
 type dispatcher struct {
@@ -55,7 +59,7 @@ type dispatcher struct {
 type reqForCmdEntry map[string]bool
 
 func (t *dispatcher) getCmdArgsFromEnv() (string, *CmdArgs, *types.Error) {
-	var cmd, contID, netns, ifName, args, path string
+	var cmd, contID, netns, ifName, args, path, netnsOverride string
 
 	vars := []struct {
 		name      string
@@ -116,6 +120,15 @@ func (t *dispatcher) getCmdArgsFromEnv() (string, *CmdArgs, *types.Error) {
 				"DEL":   true,
 			},
 		},
+		{
+			"CNI_NETNS_OVERRIDE",
+			&netnsOverride,
+			reqForCmdEntry{
+				"ADD":   false,
+				"CHECK": false,
+				"DEL":   false,
+			},
+		},
 	}
 
 	argsMissing := make([]string, 0)
@@ -143,12 +156,13 @@ func (t *dispatcher) getCmdArgsFromEnv() (string, *CmdArgs, *types.Error) {
 	}
 
 	cmdArgs := &CmdArgs{
-		ContainerID: contID,
-		Netns:       netns,
-		IfName:      ifName,
-		Args:        args,
-		Path:        path,
-		StdinData:   stdinData,
+		ContainerID:   contID,
+		Netns:         netns,
+		IfName:        ifName,
+		Args:          args,
+		Path:          path,
+		StdinData:     stdinData,
+		NetnsOverride: netnsOverride,
 	}
 	return cmd, cmdArgs, nil
 }
@@ -190,6 +204,39 @@ func validateConfig(jsonBytes []byte) *types.Error {
 	return nil
 }
 
+// Returns an object representing the current OS thread's network namespace
+func getCurrentNS() (netns.NsHandle, error) {
+	// Lock the thread in case other goroutine executes in it and changes its
+	// network namespace after getCurrentThreadNetNSPath(), otherwise it might
+	// return an unexpected network namespace.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+	return netns.GetFromPath(getCurrentThreadNetNSPath())
+}
+
+func getCurrentThreadNetNSPath() string {
+	// /proc/self/ns/net returns the namespace of the main thread, not
+	// of whatever thread this goroutine is running on.  Make sure we
+	// use the thread's net namespace since the thread is switching around
+	return fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid())
+}
+
+func checkNetNS(nsPath string) (bool, *types.Error) {
+	ns, err := netns.GetFromPath(nsPath)
+	if err != nil {
+		return false, nil
+	}
+	defer ns.Close()
+
+	pluginNS, err := getCurrentNS()
+	if err != nil {
+		return false, types.NewError(types.ErrInvalidNetNS, "get plugin's netns failed", "")
+	}
+	defer pluginNS.Close()
+
+	return pluginNS.Equal(ns), nil
+}
+
 func (t *dispatcher) pluginMain(cmdAdd, cmdCheck, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo, about string) *types.Error {
 	cmd, cmdArgs, err := t.getCmdArgsFromEnv()
 	if err != nil {
@@ -217,6 +264,17 @@ func (t *dispatcher) pluginMain(cmdAdd, cmdCheck, cmdDel func(_ *CmdArgs) error,
 	switch cmd {
 	case "ADD":
 		err = t.checkVersionAndCall(cmdArgs, versionInfo, cmdAdd)
+		if err != nil {
+			return err
+		}
+		if strings.ToUpper(cmdArgs.NetnsOverride) != "TRUE" || cmdArgs.NetnsOverride != "1" {
+			isPluginNetNS, checkErr := checkNetNS(cmdArgs.Netns)
+			if checkErr != nil {
+				return checkErr
+			} else if isPluginNetNS {
+				return types.NewError(types.ErrInvalidNetNS, "plugin's netns and netns from CNI_NETNS should not be the same", "")
+			}
+		}
 	case "CHECK":
 		configVersion, err := t.ConfVersionDecoder.Decode(cmdArgs.StdinData)
 		if err != nil {
@@ -241,6 +299,17 @@ func (t *dispatcher) pluginMain(cmdAdd, cmdCheck, cmdDel func(_ *CmdArgs) error,
 		return types.NewError(types.ErrIncompatibleCNIVersion, "plugin version does not allow CHECK", "")
 	case "DEL":
 		err = t.checkVersionAndCall(cmdArgs, versionInfo, cmdDel)
+		if err != nil {
+			return err
+		}
+		if strings.ToUpper(cmdArgs.NetnsOverride) != "TRUE" || cmdArgs.NetnsOverride != "1" {
+			isPluginNetNS, checkErr := checkNetNS(cmdArgs.Netns)
+			if checkErr != nil {
+				return checkErr
+			} else if isPluginNetNS {
+				return types.NewError(types.ErrInvalidNetNS, "plugin's netns and netns from CNI_NETNS should not be the same", "")
+			}
+		}
 	case "VERSION":
 		if err := versionInfo.Encode(t.Stdout); err != nil {
 			return types.NewError(types.ErrIOFailure, err.Error(), "")

pkg/types/types.go

@@ -165,6 +165,7 @@ const (
 	ErrIOFailure                               // 5
 	ErrDecodingFailure                         // 6
 	ErrInvalidNetworkConfig                    // 7
+	ErrInvalidNetNS                            // 8
 	ErrTryAgainLater               uint = 11
 	ErrInternal                    uint = 999
 )