Added _TEMPLAR_SANDBOX_MODE config (#85222)

* Added _TEMPLAR_SANDBOX_MODE config

* allows unsafe attribute checks to be disabled in Jinja sandbox

* Update lib/ansible/_internal/_templating/_jinja_bits.py

Co-authored-by: Matt Clay <matt@mystile.com>

---------

Co-authored-by: Matt Clay <matt@mystile.com>
(cherry picked from commit 91453e30af)

changelogs/fragments/sandbox_config.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - templating - Added ``_ANSIBLE_TEMPLAR_SANDBOX_MODE=allow_unsafe_attributes`` environment variable to disable Jinja template attribute sandbox. (https://github.com/ansible/ansible/issues/85202)

lib/ansible/_internal/_templating/_jinja_bits.py

@@ -49,6 +49,7 @@ from ._jinja_common import (
     TruncationMarker,
     validate_arg_type,
     JinjaCallContext,
+    _SandboxMode,
 )
 from ._jinja_plugins import JinjaPluginIntercept, _query, _lookup, _now, _wrap_plugin_output, get_first_marker_arg, _DirectCall, _jinja_const_template_warning
 from ._lazy_containers import (
@@ -588,6 +589,13 @@ class AnsibleEnvironment(ImmutableSandboxedEnvironment):
 
             return template_obj
 
+    def is_safe_attribute(self, obj: t.Any, attr: str, value: t.Any) -> bool:
+        # deprecated: description="remove relaxed template sandbox mode support" core_version="2.23"
+        if _TemplateConfig.sandbox_mode == _SandboxMode.ALLOW_UNSAFE_ATTRIBUTES:
+            return True
+
+        return super().is_safe_attribute(obj, attr, value)
+
     @property
     def lexer(self) -> AnsibleLexer:
         """Return/cache an AnsibleLexer with settings from the current AnsibleEnvironment"""

lib/ansible/_internal/_templating/_jinja_common.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import abc
 import collections.abc as c
+import enum
 import inspect
 import itertools
 import typing as t
@@ -24,10 +25,16 @@ from ...module_utils.datatag import native_type_name
 _patch_jinja()  # apply Jinja2 patches before types are declared that are dependent on the changes
 
 
+class _SandboxMode(enum.Enum):
+    DEFAULT = enum.auto()
+    ALLOW_UNSAFE_ATTRIBUTES = enum.auto()
+
+
 class _TemplateConfig:
     allow_embedded_templates: bool = config.get_config_value("ALLOW_EMBEDDED_TEMPLATES")
     allow_broken_conditionals: bool = config.get_config_value('ALLOW_BROKEN_CONDITIONALS')
     jinja_extensions: list[str] = config.get_config_value('DEFAULT_JINJA2_EXTENSIONS')
+    sandbox_mode: _SandboxMode = _SandboxMode.__members__[config.get_config_value('_TEMPLAR_SANDBOX_MODE').upper()]
 
     unknown_type_encountered_handler = ErrorHandler.from_config('_TEMPLAR_UNKNOWN_TYPE_ENCOUNTERED')
     unknown_type_conversion_handler = ErrorHandler.from_config('_TEMPLAR_UNKNOWN_TYPE_CONVERSION')

lib/ansible/config/base.yml

@@ -2036,6 +2036,19 @@ TASK_TIMEOUT:
   - {key: task_timeout, section: defaults}
   type: integer
   version_added: '2.10'
+_TEMPLAR_SANDBOX_MODE:
+  name: Control Jinja template sandbox behavior
+  default: default
+  description:
+    - The default Jinja sandbox behavior blocks template access to all `_` prefixed object attributes and known collection mutation methods (e.g., `dict.clear()`, `list.append()`).
+  type: choices
+  choices:
+    - default
+    - allow_unsafe_attributes
+  env: [{name: _ANSIBLE_TEMPLAR_SANDBOX_MODE}]
+  deprecated:
+    why: controlling sandbox behavior is a temporary workaround
+    version: '2.23'
 _TEMPLAR_UNKNOWN_TYPE_CONVERSION:
   name: Templar unknown type conversion behavior
   default: warning

test/units/_internal/templating/test_templar.py

@@ -43,7 +43,7 @@ from ansible._internal._templating import _transform
 from ansible.utils.collection_loader._collection_finder import _AnsibleCollectionFinder
 from ansible._internal._datatag._tags import Origin, TrustedAsTemplate
 from ansible.plugins.loader import init_plugin_loader
-from ansible._internal._templating._jinja_common import _TemplateConfig
+from ansible._internal._templating._jinja_common import _TemplateConfig, _SandboxMode
 from ansible._internal._templating._jinja_plugins import _lookup
 from ansible._internal._templating import _jinja_plugins
 from ansible._internal._templating._engine import TemplateEngine, TemplateOptions
@@ -1058,3 +1058,19 @@ def test_jinja_const_template_finalized() -> None:
     with _DeferredWarningContext(variables={}):  # suppress warning from usage of embedded template
         with unittest.mock.patch.object(_TemplateConfig, 'allow_embedded_templates', True):
             assert not _JinjaConstTemplate.is_tagged_on(TemplateEngine().template(TRUST.tag("{{ '{{ 1 }}' }}")))
+
+
+@pytest.mark.parametrize("template,expected", (
+    ("{% set x=[] %}{% set _=x.append(42) %}{{ x }}", [42]),
+    ("{{ (32).__or__(64) }}", 96),
+    ("{% set x={'foo': 42} %}{% set _=x.clear() %}{{ x }}", {}),
+))
+def test_unsafe_attr_access(template: str, expected: object) -> None:
+    """Verify that unsafe attribute access fails by default and works when explicitly configured."""
+    assert _TemplateConfig.sandbox_mode == _SandboxMode.DEFAULT
+
+    with pytest.raises(AnsibleUndefinedVariable):
+        TemplateEngine().template(TRUST.tag(template))
+
+    with unittest.mock.patch.object(_TemplateConfig, 'sandbox_mode', _SandboxMode.ALLOW_UNSAFE_ATTRIBUTES):
+        assert TemplateEngine().template(TRUST.tag(template)) == expected