Prevent overwriting existing host_uuid file

lib/service/service.go

@@ -164,6 +164,7 @@ import (
 	"github.com/gravitational/teleport/lib/utils"
 	awsutils "github.com/gravitational/teleport/lib/utils/aws"
 	"github.com/gravitational/teleport/lib/utils/cert"
+	"github.com/gravitational/teleport/lib/utils/hostid"
 	logutils "github.com/gravitational/teleport/lib/utils/log"
 	vc "github.com/gravitational/teleport/lib/versioncontrol"
 	"github.com/gravitational/teleport/lib/versioncontrol/endpoint"
@@ -2934,7 +2935,7 @@ func (process *TeleportProcess) initSSH() error {
 		storagePresence := local.NewPresenceService(process.storage.BackendStorage)
 
 		// read the host UUID:
-		serverID, err := utils.ReadOrMakeHostUUID(cfg.DataDir)
+		serverID, err := hostid.ReadOrCreateFile(cfg.DataDir)
 		if err != nil {
 			return trace.Wrap(err)
 		}
@@ -4439,7 +4440,7 @@ func (process *TeleportProcess) initProxyEndpoint(conn *Connector) error {
 	}
 
 	// read the host UUID:
-	serverID, err := utils.ReadOrMakeHostUUID(cfg.DataDir)
+	serverID, err := hostid.ReadOrCreateFile(cfg.DataDir)
 	if err != nil {
 		return trace.Wrap(err)
 	}
@@ -6498,7 +6499,7 @@ func readOrGenerateHostID(ctx context.Context, cfg *servicecfg.Config, kubeBacke
 		if err := persistHostIDToStorages(ctx, cfg, kubeBackend); err != nil {
 			return trace.Wrap(err)
 		}
-	} else if kubeBackend != nil && utils.HostUUIDExistsLocally(cfg.DataDir) {
+	} else if kubeBackend != nil && hostid.ExistsLocally(cfg.DataDir) {
 		// This case is used when loading a Teleport pre-11 agent with storage attached.
 		// In this case, we have to copy the "host_uuid" from the agent to the secret
 		// in case storage is removed later.
@@ -6537,14 +6538,14 @@ func readHostIDFromStorages(ctx context.Context, dataDir string, kubeBackend kub
 	}
 	// Even if running in Kubernetes fallback to local storage if `host_uuid` was
 	// not found in secret.
-	hostID, err := utils.ReadHostUUID(dataDir)
+	hostID, err := hostid.ReadFile(dataDir)
 	return hostID, trace.Wrap(err)
 }
 
 // persistHostIDToStorages writes the cfg.HostUUID to local data and to
 // Kubernetes Secret if this process is running on a Kubernetes Cluster.
 func persistHostIDToStorages(ctx context.Context, cfg *servicecfg.Config, kubeBackend kubernetesBackend) error {
-	if err := utils.WriteHostUUID(cfg.DataDir, cfg.HostUUID); err != nil {
+	if err := hostid.WriteFile(cfg.DataDir, cfg.HostUUID); err != nil {
 		if errors.Is(err, fs.ErrPermission) {
 			cfg.Logger.ErrorContext(ctx, "Teleport does not have permission to write to the data directory. Ensure that you are running as a user with appropriate permissions.", "data_dir", cfg.DataDir)
 		}
@@ -6563,7 +6564,7 @@ func persistHostIDToStorages(ctx context.Context, cfg *servicecfg.Config, kubeBa
 // loadHostIDFromKubeSecret reads the host_uuid from the Kubernetes secret with
 // the expected key: `/host_uuid`.
 func loadHostIDFromKubeSecret(ctx context.Context, kubeBackend kubernetesBackend) (string, error) {
-	item, err := kubeBackend.Get(ctx, backend.NewKey(utils.HostUUIDFile))
+	item, err := kubeBackend.Get(ctx, backend.NewKey(hostid.FileName))
 	if err != nil {
 		return "", trace.Wrap(err)
 	}
@@ -6576,7 +6577,7 @@ func writeHostIDToKubeSecret(ctx context.Context, kubeBackend kubernetesBackend,
 	_, err := kubeBackend.Put(
 		ctx,
 		backend.Item{
-			Key:   backend.NewKey(utils.HostUUIDFile),
+			Key:   backend.NewKey(hostid.FileName),
 			Value: []byte(id),
 		},
 	)

lib/service/service_test.go

@@ -69,6 +69,7 @@ import (
 	"github.com/gravitational/teleport/lib/services"
 	"github.com/gravitational/teleport/lib/services/local"
 	"github.com/gravitational/teleport/lib/utils"
+	"github.com/gravitational/teleport/lib/utils/hostid"
 )
 
 func TestMain(m *testing.M) {
@@ -1167,7 +1168,7 @@ func Test_readOrGenerateHostID(t *testing.T) {
 			dataDir := t.TempDir()
 			// write host_uuid file to temp dir.
 			if len(tt.args.hostIDContent) > 0 {
-				err := utils.WriteHostUUID(dataDir, tt.args.hostIDContent)
+				err := hostid.WriteFile(dataDir, tt.args.hostIDContent)
 				require.NoError(t, err)
 			}
 

lib/srv/regular/sshserver.go

@@ -71,6 +71,7 @@ import (
 	"github.com/gravitational/teleport/lib/sshutils/x11"
 	"github.com/gravitational/teleport/lib/teleagent"
 	"github.com/gravitational/teleport/lib/utils"
+	"github.com/gravitational/teleport/lib/utils/hostid"
 )
 
 var log = logrus.WithFields(logrus.Fields{
@@ -724,7 +725,7 @@ func New(
 	options ...ServerOption,
 ) (*Server, error) {
 	// read the host UUID:
-	uuid, err := utils.ReadOrMakeHostUUID(dataDir)
+	uuid, err := hostid.ReadOrCreateFile(dataDir)
 	if err != nil {
 		return nil, trace.Wrap(err)
 	}

lib/teleterm/services/connectmycomputer/connectmycomputer.go

@@ -41,6 +41,7 @@ import (
 	"github.com/gravitational/teleport/lib/defaults"
 	"github.com/gravitational/teleport/lib/teleterm/clusters"
 	"github.com/gravitational/teleport/lib/utils"
+	"github.com/gravitational/teleport/lib/utils/hostid"
 )
 
 type RoleSetup struct {
@@ -395,7 +396,7 @@ func (n *NodeJoinWait) getNodeNameFromHostUUIDFile(ctx context.Context, cluster
 			// the file is empty.
 			//
 			// Here we need to be able to distinguish between both of those two cases.
-			out, err := utils.ReadPath(utils.GetHostUUIDPath(dataDir))
+			out, err := utils.ReadPath(hostid.GetPath(dataDir))
 			if err != nil {
 				if trace.IsNotFound(err) {
 					continue
@@ -536,7 +537,7 @@ type NodeDelete struct {
 
 // Run grabs the host UUID of an agent from a disk and deletes the node with that name.
 func (n *NodeDelete) Run(ctx context.Context, presence Presence, cluster *clusters.Cluster) error {
-	hostUUID, err := utils.ReadHostUUID(getAgentDataDir(n.cfg.AgentsDir, cluster.ProfileName))
+	hostUUID, err := hostid.ReadFile(getAgentDataDir(n.cfg.AgentsDir, cluster.ProfileName))
 	if trace.IsNotFound(err) {
 		return nil
 	}
@@ -585,7 +586,7 @@ type NodeName struct {
 
 // Get returns the host UUID of the agent from a disk.
 func (n *NodeName) Get(cluster *clusters.Cluster) (string, error) {
-	hostUUID, err := utils.ReadHostUUID(getAgentDataDir(n.cfg.AgentsDir, cluster.ProfileName))
+	hostUUID, err := hostid.ReadFile(getAgentDataDir(n.cfg.AgentsDir, cluster.ProfileName))
 	return hostUUID, trace.Wrap(err)
 }
 

lib/teleterm/services/connectmycomputer/connectmycomputer_test.go

@@ -35,7 +35,7 @@ import (
 	"github.com/gravitational/teleport/lib/defaults"
 	"github.com/gravitational/teleport/lib/teleterm/api/uri"
 	"github.com/gravitational/teleport/lib/teleterm/clusters"
-	"github.com/gravitational/teleport/lib/utils"
+	"github.com/gravitational/teleport/lib/utils/hostid"
 )
 
 func TestRoleSetupRun_WithNonLocalUser(t *testing.T) {
@@ -472,7 +472,7 @@ func mustMakeHostUUIDFile(t *testing.T, agentsDir string, profileName string) st
 	err = os.MkdirAll(dataDir, agentsDirStat.Mode())
 	require.NoError(t, err)
 
-	hostUUID, err := utils.ReadOrMakeHostUUID(dataDir)
+	hostUUID, err := hostid.ReadOrCreateFile(dataDir)
 	require.NoError(t, err)
 
 	return hostUUID

lib/utils/hostid/hostid.go

@@ -0,0 +1,61 @@
+// Teleport
+// Copyright (C) 2024 Gravitational, Inc.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package hostid
+
+import (
+	"errors"
+	"io/fs"
+	"path/filepath"
+	"strings"
+
+	"github.com/gravitational/trace"
+
+	"github.com/gravitational/teleport/lib/utils"
+)
+
+const (
+	// FileName is the file name where the host UUID file is stored
+	FileName = "host_uuid"
+)
+
+// GetPath returns the path to the host UUID file given the data directory.
+func GetPath(dataDir string) string {
+	return filepath.Join(dataDir, FileName)
+}
+
+// ExistsLocally checks if dataDir/host_uuid file exists in local storage.
+func ExistsLocally(dataDir string) bool {
+	_, err := ReadFile(dataDir)
+	return err == nil
+}
+
+// ReadFile reads host UUID from the file in the data dir
+func ReadFile(dataDir string) (string, error) {
+	out, err := utils.ReadPath(GetPath(dataDir))
+	if err != nil {
+		if errors.Is(err, fs.ErrPermission) {
+			//do not convert to system error as this loses the ability to compare that it is a permission error
+			return "", trace.Wrap(err)
+		}
+		return "", trace.ConvertSystemError(err)
+	}
+	id := strings.TrimSpace(string(out))
+	if id == "" {
+		return "", trace.NotFound("host uuid is empty")
+	}
+	return id, nil
+}

lib/utils/hostid/hostid_test.go

@@ -0,0 +1,113 @@
+//go:build !windows
+
+// Teleport
+// Copyright (C) 2024 Gravitational, Inc.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package hostid_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
+
+	"github.com/gravitational/teleport/lib/utils"
+	"github.com/gravitational/teleport/lib/utils/hostid"
+)
+
+func TestMain(m *testing.M) {
+	utils.InitLoggerForTests()
+	os.Exit(m.Run())
+}
+
+func TestReadOrCreate(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+
+	var wg errgroup.Group
+	concurrency := 10
+	ids := make([]string, concurrency)
+	barrier := make(chan struct{})
+
+	for i := 0; i < concurrency; i++ {
+		wg.Go(func() error {
+			<-barrier
+			id, err := hostid.ReadOrCreateFile(dir)
+			ids[i] = id
+			return err
+		})
+	}
+
+	close(barrier)
+
+	require.NoError(t, wg.Wait())
+	require.Equal(t, slices.Repeat([]string{ids[0]}, concurrency), ids)
+}
+
+func TestIdempotence(t *testing.T) {
+	t.Parallel()
+
+	// call twice, get same result
+	dir := t.TempDir()
+	id, err := hostid.ReadOrCreateFile(dir)
+	require.Len(t, id, 36)
+	require.NoError(t, err)
+	uuidCopy, err := hostid.ReadOrCreateFile(dir)
+	require.NoError(t, err)
+	require.Equal(t, id, uuidCopy)
+}
+
+func TestBadLocation(t *testing.T) {
+	t.Parallel()
+
+	// call with a read-only dir, make sure to get an error
+	id, err := hostid.ReadOrCreateFile("/bad-location")
+	require.Empty(t, id)
+	require.Error(t, err)
+	require.Regexp(t, "^.*no such file or directory.*$", err.Error())
+}
+
+func TestIgnoreWhitespace(t *testing.T) {
+	t.Parallel()
+
+	// newlines are getting ignored
+	dir := t.TempDir()
+	id := fmt.Sprintf("%s\n", uuid.NewString())
+	err := os.WriteFile(filepath.Join(dir, hostid.FileName), []byte(id), 0666)
+	require.NoError(t, err)
+	out, err := hostid.ReadFile(dir)
+	require.NoError(t, err)
+	require.Equal(t, strings.TrimSpace(id), out)
+}
+
+func TestRegenerateEmpty(t *testing.T) {
+	t.Parallel()
+
+	// empty UUID in file is regenerated
+	dir := t.TempDir()
+	err := os.WriteFile(filepath.Join(dir, hostid.FileName), nil, 0666)
+	require.NoError(t, err)
+	out, err := hostid.ReadOrCreateFile(dir)
+	require.NoError(t, err)
+	require.Len(t, out, 36)
+}