fix(zip): Add path validation

samcli/local/lambdafn/zip.py

@@ -7,6 +7,8 @@
 import os
 import zipfile
 
+from samcli.commands.exceptions import UserException
+
 LOG = logging.getLogger(__name__)
 
 S_IFLNK = 0xA
@@ -48,15 +50,27 @@ def _extract(file_info, output_dir, zip_ref):
     -------
     string
         Returns the target path the Zip Entry was extracted to.
+
+    Raises
+    ------
+    ValueError
+        If the extraction path is not valid
     """
 
     # Handle any regular file/directory entries
     if not _is_symlink(file_info):
         return zip_ref.extract(file_info, output_dir)
 
     source = zip_ref.read(file_info.filename).decode("utf8")
+    output_dir = os.path.normpath(output_dir)
     link_name = os.path.normpath(os.path.join(output_dir, file_info.filename))
 
+    output_dir_abs = os.path.abspath(output_dir)
+    link_name_abs = os.path.abspath(link_name)
+
+    if not link_name_abs.startswith(output_dir_abs + os.sep) and link_name_abs != output_dir_abs:
+        raise UserException(f"Failed to extract file from the zip file. The '{file_info.filename}' is invalid")
+
     # make leading dirs if needed
     leading_dirs = os.path.dirname(link_name)
     if not os.path.exists(leading_dirs):
@@ -85,19 +99,22 @@ def unzip(zip_file_path, output_dir, permission=None):
     permission : int
         Permission to set in an octal int form
     """
-
+    extracted_path = None
     with zipfile.ZipFile(zip_file_path, "r") as zip_ref:
         # For each item in the zip file, extract the file and set permissions if available
         for file_info in zip_ref.infolist():
-            extracted_path = _extract(file_info, output_dir, zip_ref)
-
-            # If the extracted_path is a symlink, do not set the permissions. If the target of the symlink does not
-            # exist, then os.chmod will fail with FileNotFoundError
-            if not os.path.islink(extracted_path):
-                _set_permissions(file_info, extracted_path)
-                _override_permissions(extracted_path, permission)
-
-    if not os.path.islink(extracted_path):
+            try:
+                extracted_path = _extract(file_info, output_dir, zip_ref)
+
+                # If the extracted_path is a symlink, do not set the permissions. If the target of the symlink does not
+                # exist, then os.chmod will fail with FileNotFoundError
+                if not os.path.islink(extracted_path):
+                    _set_permissions(file_info, extracted_path)
+                    _override_permissions(extracted_path, permission)
+            except Exception as ex:
+                LOG.debug("Failed to extract '%s' from %s: %s", file_info.filename, zip_file_path, ex)
+
+    if extracted_path is not None and not os.path.islink(extracted_path):
         _override_permissions(output_dir, permission)