Improve error message if data dir and config unavailable due to permissions

lib/config/fileconf.go

@@ -20,8 +20,10 @@ import (
 	"bytes"
 	"crypto/tls"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net"
 	"net/url"
 	"os"
@@ -91,7 +93,10 @@ type FileConfig struct {
 func ReadFromFile(filePath string) (*FileConfig, error) {
 	f, err := os.Open(filePath)
 	if err != nil {
-		return nil, trace.Wrap(err, fmt.Sprintf("failed to open file: %v", filePath))
+		if errors.Is(err, fs.ErrPermission) {
+			return nil, trace.Wrap(err, "failed to open file for Teleport configuration: %v. Ensure that you are running as a user with appropriate permissions.", filePath)
+		}
+		return nil, trace.Wrap(err, "failed to open file for Teleport configuration at %v", filePath)
 	}
 	defer f.Close()
 	return ReadConfig(f)

lib/service/service.go

@@ -24,8 +24,10 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -626,6 +628,9 @@ func NewTeleport(cfg *Config) (*TeleportProcess, error) {
 	if os.IsNotExist(err) {
 		err := os.MkdirAll(cfg.DataDir, os.ModeDir|0700)
 		if err != nil {
+			if errors.Is(err, fs.ErrPermission) {
+				cfg.Log.Errorf("Teleport does not have permission to write to: %v. Ensure that you are running as a user with appropriate permissions.", cfg.DataDir)
+			}
 			return nil, trace.ConvertSystemError(err)
 		}
 	}
@@ -642,6 +647,9 @@ func NewTeleport(cfg *Config) (*TeleportProcess, error) {
 	cfg.HostUUID, err = utils.ReadHostUUID(cfg.DataDir)
 	if err != nil {
 		if !trace.IsNotFound(err) {
+			if errors.Is(err, fs.ErrPermission) {
+				cfg.Log.Errorf("Teleport does not have permission to write to: %v. Ensure that you are running as a user with appropriate permissions.", cfg.DataDir)
+			}
 			return nil, trace.Wrap(err)
 		}
 		if len(cfg.Identities) != 0 {
@@ -662,6 +670,9 @@ func NewTeleport(cfg *Config) (*TeleportProcess, error) {
 			cfg.Log.Infof("Generating new host UUID: %v.", cfg.HostUUID)
 		}
 		if err := utils.WriteHostUUID(cfg.DataDir, cfg.HostUUID); err != nil {
+			if errors.Is(err, fs.ErrPermission) {
+				cfg.Log.Errorf("Teleport does not have permission to write to: %v. Ensure that you are running as a user with appropriate permissions.", cfg.DataDir)
+			}
 			return nil, trace.Wrap(err)
 		}
 	}

lib/utils/utils.go

@@ -18,8 +18,10 @@ package utils
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net"
 	"net/url"
 	"os"
@@ -320,10 +322,18 @@ func ReadPath(path string) ([]byte, error) {
 	}
 	abs, err := filepath.EvalSymlinks(s)
 	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 nil, err
+		}
 		return nil, trace.ConvertSystemError(err)
 	}
 	bytes, err := os.ReadFile(abs)
 	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 nil, err
+		}
 		return nil, trace.ConvertSystemError(err)
 	}
 	return bytes, nil
@@ -429,6 +439,10 @@ func GetFreeTCPPorts(n int, offset ...int) (PortList, error) {
 func ReadHostUUID(dataDir string) (string, error) {
 	out, err := ReadPath(filepath.Join(dataDir, HostUUIDFile))
 	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 "", err
+		}
 		return "", trace.Wrap(err)
 	}
 	return strings.TrimSpace(string(out)), nil
@@ -438,6 +452,10 @@ func ReadHostUUID(dataDir string) (string, error) {
 func WriteHostUUID(dataDir string, id string) error {
 	err := os.WriteFile(filepath.Join(dataDir, HostUUIDFile), []byte(id), os.ModeExclusive|0400)
 	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 err
+		}
 		return trace.ConvertSystemError(err)
 	}
 	return nil