Registry-support: decompress can delete files outside scope via relative paths

@@ -113,7 +113,7 @@ func decompress(targetDir string, tarFile string, excludeFiles []string) error {
 			continue
 		}
 
-		target := path.Join(targetDir, filepath.Clean(header.Name))
+		target := CleanFilepath(targetDir, header.Name)
 		switch header.Typeflag {
 		case tar.TypeDir:
 			err = os.MkdirAll(target, os.FileMode(header.Mode))
@@ -122,7 +122,6 @@ func decompress(targetDir string, tarFile string, excludeFiles []string) error {
 				return returnedErr
 			}
 		case tar.TypeReg:
-			/* #nosec G304 -- target is produced using path.Join which cleans the dir path */
 			w, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
 			if err != nil {
 				returnedErr = multierror.Append(returnedErr, err)
@@ -192,3 +191,10 @@ func getHTTPClient(options RegistryOptions) *http.Client {
 		Timeout: overriddenTimeout,
 	}
 }
+
+// Cleans a child path to ensure that there is no escaping from the parent directory with the use of ../ escape methods
+// Ensures that the child path is always contained and absolutely pathed from the parent
+func CleanFilepath(parent string, child string)string{
+	target := path.Join(parent, filepath.Clean("/"+child))
+	return target
+}

@@ -18,6 +18,7 @@ package library
 import (
 	"reflect"
 	"testing"
+	"strings"
 )
 
 func TestValidateStackVersionTag(t *testing.T) {
@@ -130,3 +131,82 @@ func TestSplitVersionFromStack(t *testing.T) {
 		})
 	}
 }
+
+func TestCleanFilepath(t *testing.T) {
+	tests := []struct {
+		name       		string
+		parentPath   	string
+		childPath 		string
+		expectedPath 	string
+	}{
+		{
+			name:       "Absolute child path with leading slash",
+			parentPath: ".",
+			childPath: "/test/tmp",
+			expectedPath: "test/tmp",
+		},
+		{
+			name:       "Absolute child path without leading slash",
+			parentPath: ".",
+			childPath: "test/tmp",
+			expectedPath: "test/tmp",
+		},
+		{
+			name:       "Relative child path without leading slash",
+			parentPath: ".",
+			childPath: "../../../../test/tmp",
+			expectedPath: "test/tmp",
+		},
+		{
+			name:       "Relative child path with leading slash",
+			parentPath: ".",
+			childPath: "/../../../../test/tmp",
+			expectedPath: "test/tmp",
+		},
+		{
+			name:       "Absolute child path with leading slash and escape capabilities",
+			parentPath: ".",
+			childPath: "/home/../../../../test/tmp",
+			expectedPath: "test/tmp",
+		},
+		{
+			name:       "Absolute child path with leading slash and escape capabilities (parent path not current dir)",
+			parentPath: "newHome/dir",
+			childPath: "/home/../../../../test/tmp",
+			expectedPath: "newHome/dir/test/tmp",
+		},
+		{
+			name:       "Relative child path without leading slash and escape capabilities (parent path not current dir)",
+			parentPath: "newHome/dir",
+			childPath: "../home/../../../../test/tmp",
+			expectedPath: "newHome/dir/test/tmp",
+		},
+		{
+			name:       "Blank child path",
+			parentPath: "dir",
+			childPath: "",
+			expectedPath: "dir",
+		},
+		{
+			name:       "Child path only escape characters",
+			parentPath: "dir",
+			childPath: "../../../../../",
+			expectedPath: "dir",
+		},
+		{
+			name:       "Single file as child path",
+			parentPath: "dir",
+			childPath: "test.txt",
+			expectedPath: "dir/test.txt",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			path:= CleanFilepath(test.parentPath, test.childPath)
+			if !strings.EqualFold(test.expectedPath, path) {
+				t.Errorf("Expected: %s, Got: %s", test.expectedPath, path)
+			}
+		})
+	}
+}