Moved IsRestrictedVolume func to runner-go. Updated implementation

container/volume.go

@@ -0,0 +1,43 @@
+// Copyright 2021 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+package container
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// IsRestrictedVolume is helper function that
+// returns true if mounting the volume is restricted for un-trusted containers.
+func IsRestrictedVolume(path string) bool {
+	path, err := filepath.Abs(path)
+	if err != nil {
+		return true
+	}
+
+	path = strings.ToLower(path)
+
+	switch {
+	case path == "/":
+	case path == "/etc":
+	case path == "/etc/docker" || strings.HasPrefix(path, "/etc/docker/"):
+	case path == "/var":
+	case path == "/var/run" || strings.HasPrefix(path, "/var/run/"):
+	case path == "/proc" || strings.HasPrefix(path, "/proc/"):
+	case path == "/usr/local/bin" || strings.HasPrefix(path, "/usr/local/bin/"):
+	case path == "/usr/local/sbin" || strings.HasPrefix(path, "/usr/local/sbin/"):
+	case path == "/usr/bin" || strings.HasPrefix(path, "/usr/bin/"):
+	case path == "/bin" || strings.HasPrefix(path, "/bin/"):
+	case path == "/mnt" || strings.HasPrefix(path, "/mnt/"):
+	case path == "/mount" || strings.HasPrefix(path, "/mount/"):
+	case path == "/media" || strings.HasPrefix(path, "/media/"):
+	case path == "/sys" || strings.HasPrefix(path, "/sys/"):
+	case path == "/dev" || strings.HasPrefix(path, "/dev/"):
+	default:
+		return false
+	}
+
+	return true
+}

container/volume_test.go

@@ -0,0 +1,43 @@
+// Copyright 2021 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+package container
+
+import "testing"
+
+func TestIsRestrictedVolume(t *testing.T) {
+	restrictedPaths := []string{
+		"/",
+		"../../../../../../../../../../../../var/run",
+		"/var/run",
+		"//var/run",
+		"/var/run/",
+		"/var/run/.",
+		"/var//run/",
+		"/var/run//",
+		"/var/run/test/..",
+		"/./var/run",
+		"/var/./run",
+	}
+
+	allowedPaths := []string{
+		"/drone",
+		"/drone/var/run",
+		"/development",
+		"/var/lib",
+		"/etc/ssh",
+	}
+
+	for _, path := range restrictedPaths {
+		if result := IsRestrictedVolume(path); result != true {
+			t.Errorf("Test failed for restricted path %q", path)
+		}
+	}
+
+	for _, path := range allowedPaths {
+		if result := IsRestrictedVolume(path); result != false {
+			t.Errorf("Test failed for allowed path %q", path)
+		}
+	}
+}