From afb83b3049c3c0b5b578f051e277562c6b8e513d Mon Sep 17 00:00:00 2001
From: Viktor Liu <17948409+lixmal@users.noreply.github.com>
Date: Mon, 11 May 2026 16:58:49 +0900
Subject: [PATCH] [client] Use unique temp file and clean up on failure when
 writing ssh config (#6064)

---
 client/ssh/config/manager.go | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/client/ssh/config/manager.go b/client/ssh/config/manager.go
index 01822ead6..b58bf2233 100644
--- a/client/ssh/config/manager.go
+++ b/client/ssh/config/manager.go
@@ -229,18 +229,31 @@ func (m *Manager) buildHostPatterns(peer PeerSSHInfo) []string {
 
 func (m *Manager) writeSSHConfig(sshConfig string) error {
 	sshConfigPath := filepath.Join(m.sshConfigDir, m.sshConfigFile)
-	sshConfigPathTmp := sshConfigPath + ".tmp"
 
 	if err := os.MkdirAll(m.sshConfigDir, 0755); err != nil {
 		return fmt.Errorf("create SSH config directory %s: %w", m.sshConfigDir, err)
 	}
 
-	if err := writeFileWithTimeout(sshConfigPathTmp, []byte(sshConfig), 0644); err != nil {
-		return fmt.Errorf("write SSH config file %s: %w", sshConfigPath, err)
+	tmp, err := os.CreateTemp(m.sshConfigDir, m.sshConfigFile+".*.tmp")
+	if err != nil {
+		return fmt.Errorf("create temp SSH config: %w", err)
+	}
+	tmpPath := tmp.Name()
+	defer func() {
+		if err := os.Remove(tmpPath); err != nil && !os.IsNotExist(err) {
+			log.Debugf("remove temp SSH config %s: %v", tmpPath, err)
+		}
+	}()
+	if err := tmp.Close(); err != nil {
+		return fmt.Errorf("close temp SSH config %s: %w", tmpPath, err)
 	}
 
-	if err := os.Rename(sshConfigPathTmp, sshConfigPath); err != nil {
-		return fmt.Errorf("rename ssh config %s -> %s: %w", sshConfigPathTmp, sshConfigPath, err)
+	if err := writeFileWithTimeout(tmpPath, []byte(sshConfig), 0644); err != nil {
+		return fmt.Errorf("write SSH config file %s: %w", tmpPath, err)
+	}
+
+	if err := os.Rename(tmpPath, sshConfigPath); err != nil {
+		return fmt.Errorf("rename SSH config %s -> %s: %w", tmpPath, sshConfigPath, err)
 	}
 
 	log.Infof("Created NetBird SSH client config: %s", sshConfigPath)