[AUTOMATION] fix(localruntime): harden guard socket dir

internal/localruntime/socket.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"syscall"
 )
 
 func DefaultSocketPath() string {
@@ -14,5 +15,29 @@ func DefaultSocketPath() string {
 }
 
 func EnsureSocketDir(socketPath string) error {
-	return os.MkdirAll(filepath.Dir(socketPath), 0o700)
+	dir := filepath.Dir(socketPath)
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return err
+	}
+
+	info, err := os.Lstat(dir)
+	if err != nil {
+		return err
+	}
+	if info.Mode()&os.ModeSymlink != 0 {
+		return fmt.Errorf("socket directory %q must not be a symlink", dir)
+	}
+	if !info.IsDir() {
+		return fmt.Errorf("socket directory %q is not a directory", dir)
+	}
+
+	stat, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return fmt.Errorf("socket directory %q owner could not be verified", dir)
+	}
+	if int(stat.Uid) != os.Getuid() {
+		return fmt.Errorf("socket directory %q must be owned by uid %d", dir, os.Getuid())
+	}
+
+	return os.Chmod(dir, 0o700)
 }

internal/localruntime/socket_test.go

@@ -0,0 +1,84 @@
+package localruntime
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"testing"
+)
+
+func TestEnsureSocketDirCreatesPrivateDirectory(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	socketPath := filepath.Join(root, "guard", "kontext.sock")
+	if err := EnsureSocketDir(socketPath); err != nil {
+		t.Fatalf("EnsureSocketDir() error = %v", err)
+	}
+
+	info, err := os.Stat(filepath.Dir(socketPath))
+	if err != nil {
+		t.Fatalf("Stat() error = %v", err)
+	}
+	if got := info.Mode().Perm(); got != 0o700 {
+		t.Fatalf("socket dir mode = %o, want 700", got)
+	}
+
+	stat, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		t.Fatal("socket dir stat missing uid")
+	}
+	if got := int(stat.Uid); got != os.Getuid() {
+		t.Fatalf("socket dir owner uid = %d, want %d", got, os.Getuid())
+	}
+}
+
+func TestEnsureSocketDirTightensExistingDirectoryPermissions(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	dir := filepath.Join(root, "guard")
+	if err := os.MkdirAll(dir, 0o777); err != nil {
+		t.Fatalf("MkdirAll() error = %v", err)
+	}
+	if err := os.Chmod(dir, 0o777); err != nil {
+		t.Fatalf("Chmod() setup error = %v", err)
+	}
+
+	socketPath := filepath.Join(dir, "kontext.sock")
+	if err := EnsureSocketDir(socketPath); err != nil {
+		t.Fatalf("EnsureSocketDir() error = %v", err)
+	}
+
+	info, err := os.Stat(dir)
+	if err != nil {
+		t.Fatalf("Stat() error = %v", err)
+	}
+	if got := info.Mode().Perm(); got != 0o700 {
+		t.Fatalf("socket dir mode = %o, want 700", got)
+	}
+}
+
+func TestEnsureSocketDirRejectsSymlinkDirectory(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	target := filepath.Join(root, "target")
+	if err := os.MkdirAll(target, 0o700); err != nil {
+		t.Fatalf("MkdirAll() error = %v", err)
+	}
+
+	link := filepath.Join(root, "guard")
+	if err := os.Symlink(target, link); err != nil {
+		t.Fatalf("Symlink() error = %v", err)
+	}
+
+	err := EnsureSocketDir(filepath.Join(link, "kontext.sock"))
+	if err == nil {
+		t.Fatal("EnsureSocketDir() error = nil, want symlink rejection")
+	}
+	if !strings.Contains(err.Error(), "must not be a symlink") {
+		t.Fatalf("EnsureSocketDir() error = %v, want symlink rejection", err)
+	}
+}