From 879945f56103d937a7fee84bfe7662dc2a5be708 Mon Sep 17 00:00:00 2001
From: sxt1001 <shixuantong1@huawei.com>
Date: Thu, 17 Oct 2024 20:45:07 +0800
Subject: [PATCH] feat: Ensure random passwords contain multiple character
 types (#5815)

Reference:https://github.com/canonical/cloud-init/commit/879945f56103d937a7fee84bfe7662dc2a5be708
Conflict:NA

The complexity of the random password generated by the
rand_user_password() method may not meet the security configuration
requirements of the system authentication module. This can cause
chpasswd to fail.

This commit ensures we generate a password using 4 different character
classes.

Fixes GH-5814

Co-authored-by: James Falcon <james.falcon@canonical.com>
---
 cloudinit/config/cc_set_passwords.py          | 33 +++++++++++++---
 .../unittests/config/test_cc_set_passwords.py | 38 +++++++++++++++++++
 2 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/cloudinit/config/cc_set_passwords.py b/cloudinit/config/cc_set_passwords.py
index 24d8267..d46c7f2 100644
--- a/cloudinit/config/cc_set_passwords.py
+++ b/cloudinit/config/cc_set_passwords.py
@@ -9,7 +9,8 @@
 
 import logging
 import re
-from string import ascii_letters, digits
+import random
+import string
 from textwrap import dedent
 from typing import List
 
@@ -89,9 +90,6 @@ __doc__ = get_meta_doc(meta)
 
 LOG = logging.getLogger(__name__)
 
-# We are removing certain 'painful' letters/numbers
-PW_SET = "".join([x for x in ascii_letters + digits if x not in "loLOI01"])
-
 
 def get_users_by_type(users_list: list, pw_type: str) -> list:
     """either password or type: RANDOM is required, user is always required"""
@@ -307,4 +305,29 @@ def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None:
 
 
 def rand_user_password(pwlen=20):
-    return util.rand_str(pwlen, select_from=PW_SET)
+    if pwlen < 4:
+        raise ValueError("Password length must be at least 4 characters.")
+
+    # There are often restrictions on the minimum number of character
+    # classes required in a password, so ensure we at least one character
+    # from each class.
+    res_rand_list = [
+        random.choice(string.digits),
+        random.choice(string.ascii_lowercase),
+        random.choice(string.ascii_uppercase),
+        random.choice(string.punctuation),
+    ]
+
+    res_rand_list.extend(
+        list(
+            util.rand_str(
+                pwlen - len(res_rand_list),
+                select_from=string.digits
+                + string.ascii_lowercase
+                + string.ascii_uppercase
+                + string.punctuation,
+            )
+        )
+    )
+    random.shuffle(res_rand_list)
+    return "".join(res_rand_list)
diff --git a/tests/unittests/config/test_cc_set_passwords.py b/tests/unittests/config/test_cc_set_passwords.py
index ef34a8c..b5d561c 100644
--- a/tests/unittests/config/test_cc_set_passwords.py
+++ b/tests/unittests/config/test_cc_set_passwords.py
@@ -1,6 +1,7 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
 import logging
+import string
 from unittest import mock
 
 import pytest
@@ -555,6 +556,43 @@ class TestExpire:
             assert "Expired passwords" not in caplog.text
 
 
+class TestRandUserPassword:
+    def _get_str_class_num(self, str):
+        return sum(
+            [
+                any(c.islower() for c in str),
+                any(c.isupper() for c in str),
+                any(c.isupper() for c in str),
+                any(c in string.punctuation for c in str),
+            ]
+        )
+
+    @pytest.mark.parametrize(
+        "strlen, expected_result",
+        [
+            (1, ValueError),
+            (2, ValueError),
+            (3, ValueError),
+            (4, 4),
+            (5, 4),
+            (5, 4),
+            (6, 4),
+            (20, 4),
+        ],
+    )
+    def test_rand_user_password(self, strlen, expected_result):
+        if expected_result is ValueError:
+            with pytest.raises(
+                expected_result,
+                match="Password length must be at least 4 characters.",
+            ):
+                setpass.rand_user_password(strlen)
+        else:
+            rand_password = setpass.rand_user_password(strlen)
+            assert len(rand_password) == strlen
+            assert self._get_str_class_num(rand_password) == expected_result
+
+
 class TestSetPasswordsSchema:
     @pytest.mark.parametrize(
         "config, expectation",
-- 
2.33.0