issue 2117: disallow admin username

cmd/limactl/copy.go

@@ -48,10 +48,7 @@ func copyAction(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
-	u, err := osutil.LimaUser(false)
-	if err != nil {
-		return err
-	}
+
 	instDirs := make(map[string]string)
 	scpFlags := []string{}
 	scpArgs := []string{}
@@ -86,6 +83,10 @@ func copyAction(cmd *cobra.Command, args []string) error {
 			if inst.Status == store.StatusStopped {
 				return fmt.Errorf("instance %q is stopped, run `limactl start %s` to start the instance", instName, instName)
 			}
+			u, err := osutil.LimaUser(false, inst.LimaVersion)
+			if err != nil {
+				return err
+			}
 			if legacySSH {
 				scpFlags = append(scpFlags, "-P", fmt.Sprintf("%d", inst.SSHLocalPort))
 				scpArgs = append(scpArgs, fmt.Sprintf("%[email protected]:%s", u.Username, path[1]))

pkg/cidata/cidata.go

@@ -25,6 +25,7 @@ import (
 	"github.com/lima-vm/lima/pkg/sshutil"
 	"github.com/lima-vm/lima/pkg/store/filenames"
 	"github.com/lima-vm/lima/pkg/usrlocalsharelima"
+	"github.com/lima-vm/lima/pkg/version"
 	"github.com/sirupsen/logrus"
 )
 
@@ -115,7 +116,7 @@ func GenerateISO9660(instDir, name string, y *limayaml.LimaYAML, udpDNSLocalPort
 	if err := limayaml.Validate(y, false); err != nil {
 		return err
 	}
-	u, err := osutil.LimaUser(true)
+	u, err := osutil.LimaUser(true, version.Version)
 	if err != nil {
 		return err
 	}

pkg/limayaml/defaults.go

@@ -27,6 +27,7 @@ import (
 	"github.com/lima-vm/lima/pkg/ptr"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
 	"github.com/lima-vm/lima/pkg/store/filenames"
+	"github.com/lima-vm/lima/pkg/version/versionutil"
 )
 
 const (
@@ -753,8 +754,10 @@ func fixUpForPlainMode(y *LimaYAML) {
 
 func executeGuestTemplate(format, instDir string, param map[string]string) (bytes.Buffer, error) {
 	tmpl, err := template.New("").Parse(format)
+	limaVersion := ReadInstLimaVersion(instDir)
+
 	if err == nil {
-		user, _ := osutil.LimaUser(false)
+		user, _ := osutil.LimaUser(false, limaVersion)
 		data := map[string]interface{}{
 			"Home":  fmt.Sprintf("/home/%s.linux", user.Username),
 			"Name":  filepath.Base(instDir),
@@ -771,9 +774,11 @@ func executeGuestTemplate(format, instDir string, param map[string]string) (byte
 }
 
 func executeHostTemplate(format, instDir string, param map[string]string) (bytes.Buffer, error) {
+	limaVersion := ReadInstLimaVersion(instDir)
+
 	tmpl, err := template.New("").Parse(format)
 	if err == nil {
-		user, _ := osutil.LimaUser(false)
+		user, _ := osutil.LimaUser(false, limaVersion)
 		home, _ := os.UserHomeDir()
 		limaHome, _ := dirnames.LimaDir()
 		data := map[string]interface{}{
@@ -1074,3 +1079,15 @@ func unique(s []string) []string {
 	}
 	return list
 }
+
+func ReadInstLimaVersion(instDir string) string {
+	limaVersionFile := filepath.Join(instDir, filenames.LimaVersion)
+	limaVersion := ""
+	if version, err := os.ReadFile(limaVersionFile); err == nil {
+		limaVersion = strings.TrimSpace(string(version))
+		if _, err = versionutil.Parse(limaVersion); err != nil {
+			logrus.Warnf("treating lima version %q from %q as very latest release", limaVersion, limaVersionFile)
+		}
+	}
+	return limaVersion
+}

pkg/limayaml/defaults_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/lima-vm/lima/pkg/ptr"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
 	"github.com/lima-vm/lima/pkg/store/filenames"
+	"github.com/lima-vm/lima/pkg/version"
 	"github.com/sirupsen/logrus"
 	"gotest.tools/v3/assert"
 )
@@ -53,7 +54,7 @@ func TestFillDefault(t *testing.T) {
 	assert.NilError(t, err)
 	limaHome, err := dirnames.LimaDir()
 	assert.NilError(t, err)
-	user, err := osutil.LimaUser(false)
+	user, err := osutil.LimaUser(false, version.Version)
 	assert.NilError(t, err)
 
 	guestHome := fmt.Sprintf("/home/%s.linux", user.Username)

pkg/limayaml/validate.go

@@ -15,6 +15,7 @@ import (
 	"github.com/lima-vm/lima/pkg/localpathutil"
 	"github.com/lima-vm/lima/pkg/networks"
 	"github.com/lima-vm/lima/pkg/osutil"
+	"github.com/lima-vm/lima/pkg/version"
 	"github.com/sirupsen/logrus"
 )
 
@@ -117,7 +118,7 @@ func Validate(y *LimaYAML, warn bool) error {
 		return fmt.Errorf("field `memory` has an invalid value: %w", err)
 	}
 
-	u, err := osutil.LimaUser(false)
+	u, err := osutil.LimaUser(false, version.Version)
 	if err != nil {
 		return fmt.Errorf("internal error (not an error of YAML): %w", err)
 	}

pkg/osutil/user.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/lima-vm/lima/pkg/version/versionutil"
 	"github.com/sirupsen/logrus"
 )
 
@@ -35,7 +36,10 @@ var (
 // regexUsername matches user and group names to be valid for `useradd`.
 // `useradd` allows names with a trailing '$', but it feels prudent to map those
 // names to the fallback user as well, so the regex does not allow them.
-var regexUsername = regexp.MustCompile("^[a-z_][a-z0-9_-]*$")
+var (
+	regexUsername           = regexp.MustCompile("^[a-z_][a-z0-9_-]*$")
+	notAllowedUsernameRegex = regexp.MustCompile(`^admin$`)
+)
 
 // regexPath detects valid Linux path.
 var regexPath = regexp.MustCompile("^[/a-zA-Z0-9_-]+$")
@@ -106,11 +110,26 @@ func call(args []string) (string, error) {
 	return strings.TrimSpace(string(out)), nil
 }
 
-func LimaUser(warn bool) (*user.User, error) {
+func IsBlockedUsername(username, limaVersion string) bool {
+	if versionutil.GreaterThan(limaVersion, "0.23.2") {
+		return notAllowedUsernameRegex.MatchString(username)
+	}
+	return false
+}
+
+func LimaUser(warn bool, limaVersion string) (*user.User, error) {
 	cache.warnings = []string{}
 	cache.Do(func() {
 		cache.u, cache.err = user.Current()
 		if cache.err == nil {
+			//	check if the username is blocked
+			if IsBlockedUsername(cache.u.Username, limaVersion) {
+				warning := fmt.Sprintf("local user %q is not a allowed (must not match %q); using %q username instead",
+					cache.u.Username, notAllowedUsernameRegex.String(), fallbackUser)
+				cache.warnings = append(cache.warnings, warning)
+				cache.u.Username = fallbackUser
+			}
+
 			if !regexUsername.MatchString(cache.u.Username) {
 				warning := fmt.Sprintf("local user %q is not a valid Linux username (must match %q); using %q username instead",
 					cache.u.Username, regexUsername.String(), fallbackUser)

pkg/osutil/user_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestLimaUserWarn(t *testing.T) {
-	_, err := LimaUser(true)
+	_, err := LimaUser(true, "")
 	assert.NilError(t, err)
 }
 
@@ -18,29 +18,37 @@ func validUsername(username string) bool {
 }
 
 func TestLimaUsername(t *testing.T) {
-	user, err := LimaUser(false)
+	user, err := LimaUser(false, "")
 	assert.NilError(t, err)
 	// check for reasonable unix user name
 	assert.Assert(t, validUsername(user.Username), user.Username)
 }
 
 func TestLimaUserUid(t *testing.T) {
-	user, err := LimaUser(false)
+	user, err := LimaUser(false, "")
 	assert.NilError(t, err)
 	_, err = strconv.Atoi(user.Uid)
 	assert.NilError(t, err)
 }
 
 func TestLimaUserGid(t *testing.T) {
-	user, err := LimaUser(false)
+	user, err := LimaUser(false, "")
 	assert.NilError(t, err)
 	_, err = strconv.Atoi(user.Gid)
 	assert.NilError(t, err)
 }
 
 func TestLimaHomeDir(t *testing.T) {
-	user, err := LimaUser(false)
+	user, err := LimaUser(false, "")
 	assert.NilError(t, err)
 	// check for absolute unix path (/home)
 	assert.Assert(t, path.IsAbs(user.HomeDir), user.HomeDir)
 }
+
+func TestBlockedUsers(t *testing.T) {
+	//	admin is a blocked username
+	assert.Assert(t, IsBlockedUsername("admin", "0.23.1") == false, "testing on low version of lima")
+	assert.Assert(t, IsBlockedUsername("admin", "0.23.3") == true, "testing on high version of lima")
+	assert.Assert(t, IsBlockedUsername("randomuser", "0.23.1") == false, "testing on low version of lima")
+	assert.Assert(t, IsBlockedUsername("randomuser", "0.23.3") == false, "testing on low version of lima")
+}

pkg/sshutil/sshutil.go

@@ -19,8 +19,10 @@ import (
 	"github.com/lima-vm/lima/pkg/ioutilx"
 	"github.com/lima-vm/lima/pkg/lockutil"
 	"github.com/lima-vm/lima/pkg/osutil"
+	"github.com/lima-vm/lima/pkg/store"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
 	"github.com/lima-vm/lima/pkg/store/filenames"
+	"github.com/lima-vm/lima/pkg/version"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/cpu"
 )
@@ -228,7 +230,13 @@ func SSHOpts(instDir string, useDotSSH, forwardAgent, forwardX11, forwardX11Trus
 	if len(controlSock) >= osutil.UnixPathMax {
 		return nil, fmt.Errorf("socket path %q is too long: >= UNIX_PATH_MAX=%d", controlSock, osutil.UnixPathMax)
 	}
-	u, err := osutil.LimaUser(false)
+	instName := filepath.Base(instDir)
+	inst, err := store.Inspect(instName)
+	limaVersion := version.Version
+	if err == nil {
+		limaVersion = inst.LimaVersion
+	}
+	u, err := osutil.LimaUser(false, limaVersion)
 	if err != nil {
 		return nil, err
 	}