support sudo configuration and daemon mode

authdaemon/connection.go

@@ -7,8 +7,8 @@ import (
 // ProcessConnection runs the same logic as POST /connection: CA cert, user create/reconcile, principals.
 // Use this when DisableHTTPS is true (e.g. embedded in Newt) instead of calling the API.
 func (s *Server) ProcessConnection(req ConnectionRequest) {
-	logger.Info("connection: niceId=%q username=%q metadata.sudo=%v metadata.homedir=%v",
-		req.NiceId, req.Username, req.Metadata.Sudo, req.Metadata.Homedir)
+	logger.Info("connection: niceId=%q username=%q metadata.sudoMode=%q metadata.sudoCommands=%v metadata.homedir=%v metadata.groups=%v",
+		req.NiceId, req.Username, req.Metadata.SudoMode, req.Metadata.SudoCommands, req.Metadata.Homedir, req.Metadata.Groups)
 
 	cfg := &s.cfg
 	if cfg.CACertPath != "" {

authdaemon/host_linux.go

@@ -122,6 +122,55 @@ func sudoGroup() string {
 	return "sudo"
 }
 
+const skelDir = "/etc/skel"
+
+// copySkelInto copies files from srcDir (e.g. /etc/skel) into dstDir (e.g. user's home).
+// Only creates files that don't already exist. All created paths are chowned to uid:gid.
+func copySkelInto(srcDir, dstDir string, uid, gid int) {
+	entries, err := os.ReadDir(srcDir)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			logger.Warn("auth-daemon: read %s: %v", srcDir, err)
+		}
+		return
+	}
+	for _, e := range entries {
+		name := e.Name()
+		src := filepath.Join(srcDir, name)
+		dst := filepath.Join(dstDir, name)
+		if e.IsDir() {
+			if st, err := os.Stat(dst); err == nil && st.IsDir() {
+				copySkelInto(src, dst, uid, gid)
+				continue
+			}
+			if err := os.MkdirAll(dst, 0755); err != nil {
+				logger.Warn("auth-daemon: mkdir %s: %v", dst, err)
+				continue
+			}
+			if err := os.Chown(dst, uid, gid); err != nil {
+				logger.Warn("auth-daemon: chown %s: %v", dst, err)
+			}
+			copySkelInto(src, dst, uid, gid)
+			continue
+		}
+		if _, err := os.Stat(dst); err == nil {
+			continue
+		}
+		data, err := os.ReadFile(src)
+		if err != nil {
+			logger.Warn("auth-daemon: read %s: %v", src, err)
+			continue
+		}
+		if err := os.WriteFile(dst, data, 0644); err != nil {
+			logger.Warn("auth-daemon: write %s: %v", dst, err)
+			continue
+		}
+		if err := os.Chown(dst, uid, gid); err != nil {
+			logger.Warn("auth-daemon: chown %s: %v", dst, err)
+		}
+	}
+}
+
 // ensureUser creates the system user if missing, or reconciles sudo and homedir to match meta.
 func ensureUser(username string, meta ConnectionMetadata) error {
 	if username == "" {
@@ -137,6 +186,43 @@ func ensureUser(username string, meta ConnectionMetadata) error {
 	return reconcileUser(u, meta)
 }
 
+// desiredGroups returns the exact list of supplementary groups the user should have:
+// meta.Groups plus the sudo group when meta.SudoMode is "full" (deduped).
+func desiredGroups(meta ConnectionMetadata) []string {
+	seen := make(map[string]struct{})
+	var out []string
+	for _, g := range meta.Groups {
+		g = strings.TrimSpace(g)
+		if g == "" {
+			continue
+		}
+		if _, ok := seen[g]; ok {
+			continue
+		}
+		seen[g] = struct{}{}
+		out = append(out, g)
+	}
+	if meta.SudoMode == "full" {
+		sg := sudoGroup()
+		if _, ok := seen[sg]; !ok {
+			out = append(out, sg)
+		}
+	}
+	return out
+}
+
+// setUserGroups sets the user's supplementary groups to exactly groups (local mirrors metadata).
+// When groups is empty, clears all supplementary groups (usermod -G "").
+func setUserGroups(username string, groups []string) {
+	list := strings.Join(groups, ",")
+	cmd := exec.Command("usermod", "-G", list, username)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		logger.Warn("auth-daemon: usermod -G %s: %v (output: %s)", list, err, string(out))
+	} else {
+		logger.Info("auth-daemon: set %s supplementary groups to %s", username, list)
+	}
+}
+
 func createUser(username string, meta ConnectionMetadata) error {
 	args := []string{"-s", "/bin/bash"}
 	if meta.Homedir {
@@ -150,56 +236,96 @@ func createUser(username string, meta ConnectionMetadata) error {
 		return fmt.Errorf("useradd %s: %w (output: %s)", username, err, string(out))
 	}
 	logger.Info("auth-daemon: created user %s (homedir=%v)", username, meta.Homedir)
-	if meta.Sudo {
-		group := sudoGroup()
-		cmd := exec.Command("usermod", "-aG", group, username)
-		if out, err := cmd.CombinedOutput(); err != nil {
-			logger.Warn("auth-daemon: usermod -aG %s %s: %v (output: %s)", group, username, err, string(out))
-		} else {
-			logger.Info("auth-daemon: added %s to %s", username, group)
+	if meta.Homedir {
+		if u, err := user.Lookup(username); err == nil && u.HomeDir != "" {
+			uid, gid := mustAtoi(u.Uid), mustAtoi(u.Gid)
+			copySkelInto(skelDir, u.HomeDir, uid, gid)
 		}
+	}
+	setUserGroups(username, desiredGroups(meta))
+	switch meta.SudoMode {
+	case "full":
 		if err := configurePasswordlessSudo(username); err != nil {
 			logger.Warn("auth-daemon: configure passwordless sudo for %s: %v", username, err)
 		}
+	case "commands":
+		if len(meta.SudoCommands) > 0 {
+			if err := configureSudoCommands(username, meta.SudoCommands); err != nil {
+				logger.Warn("auth-daemon: configure sudo commands for %s: %v", username, err)
+			}
+		}
+	default:
+		removeSudoers(username)
 	}
 	return nil
 }
 
-// configurePasswordlessSudo creates a sudoers.d file to allow passwordless sudo for the user
-func configurePasswordlessSudo(username string) error {
-	sudoersFile := filepath.Join("/etc/sudoers.d", fmt.Sprintf("90-pangolin-%s", username))
-	content := fmt.Sprintf("# Created by newt auth-daemon\n%s ALL=(ALL) NOPASSWD:ALL\n", username)
-	
-	// Write to temp file first
+const sudoersFilePrefix = "90-pangolin-"
+
+func sudoersPath(username string) string {
+	return filepath.Join("/etc/sudoers.d", sudoersFilePrefix+username)
+}
+
+// writeSudoersFile writes content to the user's sudoers.d file and validates with visudo.
+func writeSudoersFile(username, content string) error {
+	sudoersFile := sudoersPath(username)
 	tmpFile := sudoersFile + ".tmp"
 	if err := os.WriteFile(tmpFile, []byte(content), 0440); err != nil {
 		return fmt.Errorf("write temp sudoers file: %w", err)
 	}
-	
-	// Validate with visudo
 	cmd := exec.Command("visudo", "-c", "-f", tmpFile)
 	if out, err := cmd.CombinedOutput(); err != nil {
 		os.Remove(tmpFile)
 		return fmt.Errorf("visudo validation failed: %w (output: %s)", err, string(out))
 	}
-	
-	// Move to final location
 	if err := os.Rename(tmpFile, sudoersFile); err != nil {
 		os.Remove(tmpFile)
 		return fmt.Errorf("move sudoers file: %w", err)
 	}
-	
+	return nil
+}
+
+// configurePasswordlessSudo creates a sudoers.d file to allow passwordless sudo for the user.
+func configurePasswordlessSudo(username string) error {
+	content := fmt.Sprintf("# Created by Pangolin auth-daemon\n%s ALL=(ALL) NOPASSWD:ALL\n", username)
+	if err := writeSudoersFile(username, content); err != nil {
+		return err
+	}
 	logger.Info("auth-daemon: configured passwordless sudo for %s", username)
 	return nil
 }
 
-// removePasswordlessSudo removes the sudoers.d file for the user
-func removePasswordlessSudo(username string) {
-	sudoersFile := filepath.Join("/etc/sudoers.d", fmt.Sprintf("90-newt-%s", username))
+// configureSudoCommands creates a sudoers.d file allowing only the listed commands (NOPASSWD).
+// Each command should be a full path (e.g. /usr/bin/systemctl).
+func configureSudoCommands(username string, commands []string) error {
+	var b strings.Builder
+	b.WriteString("# Created by Pangolin auth-daemon (restricted commands)\n")
+	n := 0
+	for _, c := range commands {
+		c = strings.TrimSpace(c)
+		if c == "" {
+			continue
+		}
+		fmt.Fprintf(&b, "%s ALL=(ALL) NOPASSWD: %s\n", username, c)
+		n++
+	}
+	if n == 0 {
+		return fmt.Errorf("no valid sudo commands")
+	}
+	if err := writeSudoersFile(username, b.String()); err != nil {
+		return err
+	}
+	logger.Info("auth-daemon: configured restricted sudo for %s (%d commands)", username, len(commands))
+	return nil
+}
+
+// removeSudoers removes the sudoers.d file for the user.
+func removeSudoers(username string) {
+	sudoersFile := sudoersPath(username)
 	if err := os.Remove(sudoersFile); err != nil && !os.IsNotExist(err) {
-		logger.Warn("auth-daemon: remove passwordless sudo for %s: %v", username, err)
+		logger.Warn("auth-daemon: remove sudoers for %s: %v", username, err)
 	} else if err == nil {
-		logger.Info("auth-daemon: removed passwordless sudo for %s", username)
+		logger.Info("auth-daemon: removed sudoers for %s", username)
 	}
 }
 
@@ -209,66 +335,37 @@ func mustAtoi(s string) int {
 }
 
 func reconcileUser(u *user.User, meta ConnectionMetadata) error {
-	group := sudoGroup()
-	inGroup, err := userInGroup(u.Username, group)
-	if err != nil {
-		logger.Warn("auth-daemon: check group %s: %v", group, err)
-		inGroup = false
-	}
-	if meta.Sudo && !inGroup {
-		cmd := exec.Command("usermod", "-aG", group, u.Username)
-		if out, err := cmd.CombinedOutput(); err != nil {
-			logger.Warn("auth-daemon: usermod -aG %s %s: %v (output: %s)", group, u.Username, err, string(out))
-		} else {
-			logger.Info("auth-daemon: added %s to %s", u.Username, group)
-		}
-	} else if !meta.Sudo && inGroup {
-		cmd := exec.Command("gpasswd", "-d", u.Username, group)
-		if out, err := cmd.CombinedOutput(); err != nil {
-			logger.Warn("auth-daemon: gpasswd -d %s %s: %v (output: %s)", u.Username, group, err, string(out))
-		} else {
-			logger.Info("auth-daemon: removed %s from %s", u.Username, group)
-		}
-	}
-	
-	// Configure passwordless sudo
-	if meta.Sudo {
+	setUserGroups(u.Username, desiredGroups(meta))
+	switch meta.SudoMode {
+	case "full":
 		if err := configurePasswordlessSudo(u.Username); err != nil {
 			logger.Warn("auth-daemon: configure passwordless sudo for %s: %v", u.Username, err)
 		}
-	} else {
-		removePasswordlessSudo(u.Username)
+	case "commands":
+		if len(meta.SudoCommands) > 0 {
+			if err := configureSudoCommands(u.Username, meta.SudoCommands); err != nil {
+				logger.Warn("auth-daemon: configure sudo commands for %s: %v", u.Username, err)
+			}
+		} else {
+			removeSudoers(u.Username)
+		}
+	default:
+		removeSudoers(u.Username)
 	}
 	if meta.Homedir && u.HomeDir != "" {
+		uid, gid := mustAtoi(u.Uid), mustAtoi(u.Gid)
 		if st, err := os.Stat(u.HomeDir); err != nil || !st.IsDir() {
 			if err := os.MkdirAll(u.HomeDir, 0755); err != nil {
 				logger.Warn("auth-daemon: mkdir %s: %v", u.HomeDir, err)
 			} else {
-				uid, gid := mustAtoi(u.Uid), mustAtoi(u.Gid)
 				_ = os.Chown(u.HomeDir, uid, gid)
+				copySkelInto(skelDir, u.HomeDir, uid, gid)
 				logger.Info("auth-daemon: created home %s for %s", u.HomeDir, u.Username)
 			}
+		} else {
+			// Ensure .bashrc etc. exist (e.g. home existed but was empty or skel was minimal)
+			copySkelInto(skelDir, u.HomeDir, uid, gid)
 		}
 	}
 	return nil
 }
-
-func userInGroup(username, groupName string) (bool, error) {
-	// getent group wheel returns "wheel:x:10:user1,user2"
-	cmd := exec.Command("getent", "group", groupName)
-	out, err := cmd.Output()
-	if err != nil {
-		return false, err
-	}
-	parts := strings.SplitN(strings.TrimSpace(string(out)), ":", 4)
-	if len(parts) < 4 {
-		return false, nil
-	}
-	members := strings.Split(parts[3], ",")
-	for _, m := range members {
-		if strings.TrimSpace(m) == username {
-			return true, nil
-		}
-	}
-	return false, nil
-}

authdaemon/routes.go

@@ -13,8 +13,10 @@ func (s *Server) registerRoutes() {
 
 // ConnectionMetadata is the metadata object in POST /connection.
 type ConnectionMetadata struct {
-	Sudo    bool `json:"sudo"`
-	Homedir bool `json:"homedir"`
+	SudoMode     string   `json:"sudoMode"`     // "none" | "full" | "commands"
+	SudoCommands []string `json:"sudoCommands"`  // used when sudoMode is "commands"
+	Homedir      bool     `json:"homedir"`
+	Groups       []string `json:"groups"`        // system groups to add the user to
 }
 
 // ConnectionRequest is the JSON body for POST /connection.

main.go

@@ -1378,15 +1378,18 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 
 		// Define the structure of the incoming message
 		type SSHCertData struct {
-			MessageId int    `json:"messageId"`
-			AgentPort int    `json:"agentPort"`
-			AgentHost string `json:"agentHost"`
-			CACert    string `json:"caCert"`
-			Username  string `json:"username"`
-			NiceID    string `json:"niceId"`
-			Metadata  struct {
-				Sudo    bool `json:"sudo"`
-				Homedir bool `json:"homedir"`
+			MessageId          int    `json:"messageId"`
+			AgentPort          int    `json:"agentPort"`
+			AgentHost          string `json:"agentHost"`
+			ExternalAuthDaemon bool   `json:"externalAuthDaemon"`
+			CACert             string `json:"caCert"`
+			Username           string `json:"username"`
+			NiceID             string `json:"niceId"`
+			Metadata           struct {
+				SudoMode     string   `json:"sudoMode"`
+				SudoCommands []string `json:"sudoCommands"`
+				Homedir      bool     `json:"homedir"`
+				Groups       []string `json:"groups"`
 			} `json:"metadata"`
 		}
 
@@ -1406,7 +1409,7 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 		}
 
 		// Check if we're running the auth daemon internally
-		if authDaemonServer != nil {
+		if authDaemonServer != nil && !certData.ExternalAuthDaemon { // if the auth daemon is running internally and the external auth daemon is not enabled
 			// Call ProcessConnection directly when running internally
 			logger.Debug("Calling internal auth daemon ProcessConnection for user %s", certData.Username)
 
@@ -1415,8 +1418,10 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 				NiceId:   certData.NiceID,
 				Username: certData.Username,
 				Metadata: authdaemon.ConnectionMetadata{
-					Sudo:    certData.Metadata.Sudo,
-					Homedir: certData.Metadata.Homedir,
+					SudoMode:     certData.Metadata.SudoMode,
+					SudoCommands: certData.Metadata.SudoCommands,
+					Homedir:      certData.Metadata.Homedir,
+					Groups:       certData.Metadata.Groups,
 				},
 			})
 
@@ -1450,8 +1455,10 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 				"niceId":   certData.NiceID,
 				"username": certData.Username,
 				"metadata": map[string]interface{}{
-					"sudo":    certData.Metadata.Sudo,
-					"homedir": certData.Metadata.Homedir,
+					"sudoMode":     certData.Metadata.SudoMode,
+					"sudoCommands": certData.Metadata.SudoCommands,
+					"homedir":      certData.Metadata.Homedir,
+					"groups":       certData.Metadata.Groups,
 				},
 			}