Fixes crash when writing kubeconfig with tctl auth sign --tar

lib/client/identityfile/identity.go

@@ -137,6 +137,9 @@ type ConfigWriter interface {
 	// permissions if the file is new.
 	WriteFile(name string, data []byte, perm os.FileMode) error
 
+	// ReadFile reads the file at tpath `name`
+	ReadFile(name string) ([]byte, error)
+
 	// Remove removes a file.
 	Remove(name string) error
 
@@ -152,6 +155,11 @@ func (s *StandardConfigWriter) WriteFile(name string, data []byte, perm os.FileM
 	return os.WriteFile(name, data, perm)
 }
 
+// ReadFile reads the file at tpath `name`, returning
+func (s *StandardConfigWriter) ReadFile(name string) ([]byte, error) {
+	return os.ReadFile(name)
+}
+
 // Remove removes the named file or (empty) directory.
 // If there is an error, it will be of type *PathError.
 func (s *StandardConfigWriter) Remove(name string) error {
@@ -389,7 +397,7 @@ func Write(ctx context.Context, cfg WriteConfig) (filesWritten []string, err err
 
 	case FormatKubernetes:
 		filesWritten = append(filesWritten, cfg.OutputPath)
-		// If the user does not want to override,  it will merge the previous kubeconfig
+		// If the user does not want to override, it will merge the previous kubeconfig
 		// with the new entry.
 		if err := checkOverwrite(ctx, writer, cfg.OverwriteDestination, filesWritten...); err != nil && !trace.IsAlreadyExists(err) {
 			return nil, trace.Wrap(err)
@@ -408,13 +416,13 @@ func Write(ctx context.Context, cfg WriteConfig) (filesWritten []string, err err
 			kubeCluster = []string{cfg.KubeClusterName}
 		}
 
-		if err := kubeconfig.Update(cfg.OutputPath, kubeconfig.Values{
+		if err := kubeconfig.UpdateConfig(cfg.OutputPath, kubeconfig.Values{
 			TeleportClusterName: cfg.Key.ClusterName,
 			ClusterAddr:         cfg.KubeProxyAddr,
 			Credentials:         cfg.Key,
 			TLSServerName:       cfg.KubeTLSServerName,
 			KubeClusters:        kubeCluster,
-		}, cfg.KubeStoreAllCAs); err != nil {
+		}, cfg.KubeStoreAllCAs, writer); err != nil {
 			return nil, trace.Wrap(err)
 		}
 

lib/client/identityfile/identity_test.go

@@ -180,6 +180,42 @@ func TestWrite(t *testing.T) {
 	assertKubeconfigContents(t, cfg.OutputPath, key.ClusterName, "far.away.cluster", cfg.KubeTLSServerName)
 }
 
+// Assert that the kubeconfig writer only writes to the supplied filesystem
+// abstraction, and not to the system
+func TestWriteKubeOnlyWritesToWriter(t *testing.T) {
+	key := newClientKey(t)
+	outputDir := t.TempDir()
+
+	fs := NewInMemoryConfigWriter()
+	cfg := WriteConfig{
+		Key:    key,
+		Writer: fs,
+	}
+
+	cfg.OutputPath = filepath.Join(outputDir, "kubeconfig")
+	cfg.Format = FormatOpenSSH
+	cfg.KubeProxyAddr = "far.away.cluster"
+	cfg.KubeTLSServerName = constants.KubeTeleportProxyALPNPrefix + "far.away.cluster"
+	files, err := Write(context.Background(), cfg)
+	require.NoError(t, err)
+
+	// Assert that none of the listed files
+	for _, fn := range files {
+		// assert that no such file exists on the system filesystem
+		_, err := os.Stat(fn)
+		require.Error(t, err)
+
+		// assert that the file exists is in the filesystem abstraction
+		require.Contains(t, fs.files, fn)
+	}
+
+	// Assert that nothing has written to the temp dir without it being added to
+	// the returned file list
+	actualFiles, err := os.ReadDir(outputDir)
+	require.NoError(t, err)
+	require.Empty(t, actualFiles)
+}
+
 func TestWriteAllFormats(t *testing.T) {
 	for _, format := range KnownFileFormats {
 		t.Run(string(format), func(t *testing.T) {

lib/client/identityfile/inmemory_config_writer.go

@@ -20,36 +20,52 @@ import (
 	"io/fs"
 	"os"
 	"sync"
-	"time"
 
 	"github.com/gravitational/trace"
+	"github.com/jonboulle/clockwork"
 
 	"github.com/gravitational/teleport/lib/utils"
 )
 
+type InMemoryFS map[string]*utils.InMemoryFile
+
+type InMemoryConfigWriterOption func(*InMemoryConfigWriter)
+
+func WithClock(clock clockwork.Clock) InMemoryConfigWriterOption {
+	return func(w *InMemoryConfigWriter) {
+		w.clock = clock
+	}
+}
+
 // NewInMemoryConfigWriter creates a new virtual file system
 // It stores the files contents and their properties in memory
-func NewInMemoryConfigWriter() *InMemoryConfigWriter {
-	return &InMemoryConfigWriter{
+func NewInMemoryConfigWriter(options ...InMemoryConfigWriterOption) *InMemoryConfigWriter {
+	w := &InMemoryConfigWriter{
 		mux:   &sync.RWMutex{},
-		files: make(map[string]*utils.InMemoryFile),
+		clock: clockwork.NewRealClock(),
+		files: InMemoryFS{},
 	}
+	for _, option := range options {
+		option(w)
+	}
+	return w
 }
 
 // InMemoryConfigWriter is a basic virtual file system abstraction that writes into memory
 //
 //	instead of writing to a more persistent storage.
 type InMemoryConfigWriter struct {
 	mux   *sync.RWMutex
-	files map[string]*utils.InMemoryFile
+	clock clockwork.Clock
+	files InMemoryFS
 }
 
 // WriteFile writes the given data to path `name`
 // It replaces the file if it already exists
 func (m *InMemoryConfigWriter) WriteFile(name string, data []byte, perm os.FileMode) error {
 	m.mux.Lock()
 	defer m.mux.Unlock()
-	m.files[name] = utils.NewInMemoryFile(name, perm, time.Now(), data)
+	m.files[name] = utils.NewInMemoryFile(name, perm, m.clock.Now(), data)
 
 	return nil
 }
@@ -92,7 +108,13 @@ func (m *InMemoryConfigWriter) ReadFile(name string) ([]byte, error) {
 	return f.Content(), nil
 }
 
-// Open is not implemented but exists here to satisfy the io/fs.ReadFileFS interface.
+// Open is not implemented but exists here to satisfy the io/fs. interface.
 func (m *InMemoryConfigWriter) Open(name string) (fs.File, error) {
 	return nil, trace.NotImplemented("Open is not implemented for InMemoryConfigWriter")
 }
+
+func (m *InMemoryConfigWriter) WithReadonlyFiles(fn func(InMemoryFS) error) error {
+	m.mux.RLock()
+	defer m.mux.RUnlock()
+	return fn(m.files)
+}

lib/kube/kubeconfig/kubeconfig.go

@@ -101,17 +101,47 @@ type ExecValues struct {
 	Env map[string]string
 }
 
+// ConfigFS is a simple filesystem abstraction to allow alternative file
+// writing options when generating kube config files.
+type ConfigFS interface {
+	// WriteFile writes the given data to path `name`, using the specified
+	// permissions if the file is new.
+	WriteFile(name string, data []byte, perm os.FileMode) error
+
+	ReadFile(name string) ([]byte, error)
+}
+
+// defaultConfigFS is a ConfigFS that is backed by the system filesystem
+type defaultConfigFS struct{}
+
+func (defaultConfigFS) WriteFile(name string, data []byte, perm os.FileMode) error {
+	return os.WriteFile(name, data, perm)
+}
+
+func (defaultConfigFS) ReadFile(name string) ([]byte, error) {
+	return os.ReadFile(name)
+}
+
 // Update adds Teleport configuration to kubeconfig.
 //
 // If `path` is empty, Update will try to guess it based on the environment or
 // known defaults.
 func Update(path string, v Values, storeAllCAs bool) error {
+	return UpdateConfig(path, v, storeAllCAs, defaultConfigFS{})
+}
+
+// UpdateConfig adds Teleport configuration to kubeconfig, reading and writing
+// from the supplied ConfigFS
+//
+// If `path` is empty, Update will try to guess it based on the environment or
+// known defaults.
+func UpdateConfig(path string, v Values, storeAllCAs bool, fs ConfigFS) error {
 	contextTmpl, err := parseContextOverrideTemplate(v.OverrideContext)
 	if err != nil {
 		return trace.Wrap(err)
 	}
 
-	config, err := Load(path)
+	config, err := LoadConfig(path, fs)
 	if err != nil {
 		return trace.Wrap(err)
 	}
@@ -237,7 +267,7 @@ func Update(path string, v Values, storeAllCAs bool) error {
 		log.WithError(err).Warn("Kubernetes integration is not supported when logging in with a non-rsa private key.")
 	}
 
-	return Save(path, *config)
+	return SaveConfig(path, *config, fs)
 }
 
 func setContext(contexts map[string]*clientcmdapi.Context, name, cluster, auth, kubeName, namespace string) {
@@ -337,37 +367,98 @@ func removeByServerAddr(config *clientcmdapi.Config, wantServer string) {
 // Load tries to read a kubeconfig file and if it can't, returns an error.
 // One exception, missing files result in empty configs, not an error.
 func Load(path string) (*clientcmdapi.Config, error) {
+	return LoadConfig(path, defaultConfigFS{})
+}
+
+// LoadConfig tries to read a kubeconfig file and if it can't, returns an error.
+// One exception, missing files result in empty configs, not an error.
+func LoadConfig(path string, fs ConfigFS) (*clientcmdapi.Config, error) {
 	filename, err := finalPath(path)
 	if err != nil {
 		return nil, trace.Wrap(err)
 	}
-	config, err := clientcmd.LoadFromFile(filename)
-	if err != nil && !os.IsNotExist(err) {
+
+	configBytes, err := fs.ReadFile(filename)
+	switch {
+	case os.IsNotExist(err):
+		return clientcmdapi.NewConfig(), nil
+
+	case err != nil:
+		err = trace.ConvertSystemError(err)
+		return nil, trace.WrapWithMessage(err, "failed to load existing kubeconfig %q: %v", filename, err)
+	}
+
+	config, err := clientcmd.Load(configBytes)
+	if err != nil {
 		err = trace.ConvertSystemError(err)
 		return nil, trace.WrapWithMessage(err, "failed to parse existing kubeconfig %q: %v", filename, err)
 	}
 	if config == nil {
 		config = clientcmdapi.NewConfig()
 	}
 
+	// Now that we are using clientcmd.Load() we need to manually set all of the
+	// object origin values manually. We used to use clientcmd.LoadFile() that
+	// did it for us.
+	setConfigOriginsAndDefaults(config, filename)
+
 	return config, nil
 }
 
+// setConfigOriginsAndDefaults sets up the origin info for the config file.
+func setConfigOriginsAndDefaults(config *clientcmdapi.Config, filename string) {
+	// set LocationOfOrigin on every Cluster, User, and Context
+	for key, obj := range config.AuthInfos {
+		obj.LocationOfOrigin = filename
+		config.AuthInfos[key] = obj
+	}
+	for key, obj := range config.Clusters {
+		obj.LocationOfOrigin = filename
+		config.Clusters[key] = obj
+	}
+	for key, obj := range config.Contexts {
+		obj.LocationOfOrigin = filename
+		config.Contexts[key] = obj
+	}
+
+	if config.AuthInfos == nil {
+		config.AuthInfos = map[string]*clientcmdapi.AuthInfo{}
+	}
+	if config.Clusters == nil {
+		config.Clusters = map[string]*clientcmdapi.Cluster{}
+	}
+	if config.Contexts == nil {
+		config.Contexts = map[string]*clientcmdapi.Context{}
+	}
+}
+
 // Save saves updated config to location specified by environment variable or
 // default location
 func Save(path string, config clientcmdapi.Config) error {
+	return SaveConfig(path, config, defaultConfigFS{})
+}
+
+// Save saves updated config to location specified by environment variable or
+// default location.
+func SaveConfig(path string, config clientcmdapi.Config, fs ConfigFS) error {
 	filename, err := finalPath(path)
 	if err != nil {
 		return trace.Wrap(err)
 	}
 
-	if err := clientcmd.WriteToFile(config, filename); err != nil {
+	configBytes, err := clientcmd.Write(config)
+	if err != nil {
+		return trace.ConvertSystemError(err)
+	}
+
+	if err := fs.WriteFile(filename, configBytes, 0600); err != nil {
 		return trace.ConvertSystemError(err)
 	}
 	return nil
+
 }
 
-// finalPath returns the final path to kubeceonfig using, in order of
+// finalPath returns the final path to kubeconfig using, in order of
 // precedence:
 // - `customPath`, if not empty
 // - ${KUBECONFIG} environment variable

lib/tbot/config/template.go

@@ -28,6 +28,7 @@ import (
 	"github.com/gravitational/teleport/api/utils/keys"
 	"github.com/gravitational/teleport/lib/auth"
 	"github.com/gravitational/teleport/lib/client"
+	"github.com/gravitational/teleport/lib/client/identityfile"
 	"github.com/gravitational/teleport/lib/tbot/bot"
 	"github.com/gravitational/teleport/lib/tbot/identity"
 )
@@ -129,6 +130,15 @@ func (b *BotConfigWriter) Stat(name string) (fs.FileInfo, error) {
 	return nil, &os.PathError{Op: "stat", Path: name, Err: os.ErrNotExist}
 }
 
+// ReadFile reads a given file. This implementation always returns not found.
+func (b *BotConfigWriter) ReadFile(name string) ([]byte, error) {
+	return nil, &os.PathError{Op: "read", Path: name, Err: os.ErrNotExist}
+}
+
+// compile-time assertion that the BotConfigWriter implements the
+// identityfile.ConfigWriter interface
+var _ identityfile.ConfigWriter = (*BotConfigWriter)(nil)
+
 // newClientKey returns a sane client.Key for the given bot identity.
 func newClientKey(ident *identity.Identity, hostCAs []types.CertAuthority) (*client.Key, error) {
 	pk, err := keys.ParsePrivateKey(ident.PrivateKeyBytes)

tool/tctl/common/auth_command.go

@@ -255,8 +255,8 @@ func (a *AuthCommand) GenerateKeys(ctx context.Context) error {
 // GenerateAndSignKeys generates a new keypair and signs it for role
 func (a *AuthCommand) GenerateAndSignKeys(ctx context.Context, clusterAPI auth.ClientI) error {
 	if a.streamTarfile {
-		tarWriter := newTarWriter(os.Stdout, clockwork.NewRealClock())
-		defer tarWriter.Close()
+		tarWriter := newTarWriter(clockwork.NewRealClock())
+		defer tarWriter.Archive(os.Stdout)
 		a.identityWriter = tarWriter
 	}
 
@@ -952,7 +952,7 @@ func (a *AuthCommand) checkKubeCluster(ctx context.Context, clusterAPI auth.Clie
 	if a.outputFormat != identityfile.FormatKubernetes && a.kubeCluster != "" {
 		// User set --kube-cluster-name but it's not actually used for the chosen --format.
 		// Print a warning but continue.
-		fmt.Printf("Note: --kube-cluster-name is only used with --format=%q, ignoring for --format=%q\n", identityfile.FormatKubernetes, a.outputFormat)
+		fmt.Fprintf(a.helperMsgDst(), "Note: --kube-cluster-name is only used with --format=%q, ignoring for --format=%q\n", identityfile.FormatKubernetes, a.outputFormat)
 	}
 	if a.outputFormat != identityfile.FormatKubernetes {
 		return nil
@@ -979,7 +979,7 @@ func (a *AuthCommand) checkProxyAddr(ctx context.Context, clusterAPI auth.Client
 	if a.outputFormat != identityfile.FormatKubernetes && a.proxyAddr != "" {
 		// User set --proxy but it's not actually used for the chosen --format.
 		// Print a warning but continue.
-		fmt.Printf("Note: --proxy is only used with --format=%q, ignoring for --format=%q\n", identityfile.FormatKubernetes, a.outputFormat)
+		fmt.Fprintf(a.helperMsgDst(), "Note: --proxy is only used with --format=%q, ignoring for --format=%q\n", identityfile.FormatKubernetes, a.outputFormat)
 		return nil
 	}
 	if a.outputFormat != identityfile.FormatKubernetes {